步进电机的单片机控制外文翻译
附录2:英文资料及其中文翻译 Stepper motor is an electrical pulse will be converted into angular displacement of the implementing agencies. Put it in simple language-speaking: When the stepper drive pulse signal to a receiver, it drives stepper motor rotation direction by setting a fixed point of view (and the step angle). You can control the number of pulses to control the amount of angular displacement, so as to achieve the purpose of accurate positioning; At the same time, you can by controlling the pulse frequency to control the motor rotation speed and acceleration, so as to achieve the purpose of speed. Stepper motor directly from the AC-DC power supply, and must use special equipment - stepper motor drive. Stepper motor drive system performance, in addition to their own performance with the motor on the outside, but also to a large extent depend on the drive is good or bad. A typical stepper motor drive system is operated by the stepper motor controller, stepper motor drives and stepper motor body is composed of three parts. Stepper motor controller stepper pulse and direction signal, each made of a pulse, stepper motor-driven stepper motor drives a rotor rotating step angle, that is, step-by-step further. High or low speed stepper motor, or speed, or deceleration, start or stop pulses are entirely dependent on whether the level or frequency. Decide the direction of the signal controller stepper motor clockwise or counterclockwise rotation. Typically, the stepper motor drive circuit from the logic control, power driver circuit, protection circuit and power components. Stepper motor drive controller, once received from the direction of the signal and step pulse, the control circuit on a pre-determined way of the electrical power-phase stepper motor excitation windings of the conduction or cut-off signal. Control circuit output signal power is low, can not provide the necessary stepping motor output power, the need for power amplifier, which is stepper motor driven power drive part. Power stepper motor drive circuit to control the input current winding to form a space for rotating magnetic field excitation, the rotor-driven movement. Protection circuit in the event of short circuit, overload, overheating, such as failure to stop the rapid drive and motor. Motor is usually for the permanent magnet rotor, when the current flows through the stator windings, the stator windings produce a magnetic field vector. The magnetic field will lead to a rotor angle of rotation, making a pair of rotor and stator magnetic field direction of the magnetic field direction. When the stator rotating magnetic field vector from a different angle. Also as the rotor magnetic field to a point of view. An electrical pulse for each input, the motor rotation angle step. Its output and input of the angular displacement is proportional to the pulses, with pulse frequency proportional to speed. Power to change the order of winding, the electrical will be reversed. We can, therefore, control the pulse number, frequency and electrical power windings of each phase to control the order of rotation of stepper motor. Stepper motor types: Permanent magnet (PM). Magnetic generally two-phase stepper, torque and are smaller and generally stepping angle of 7.5 degrees or 15 degrees; put more wind for air-conditioning. Reactive (VR), the domestic general called BF, have a common three-phase reaction, step angle of 1.5 degrees; also have five-phase reaction. Noise, no torque has been set at a large number of out. Hybrid (HB), common two-phase hybrid, five-phase hybrid, three-phase hybrid, four-phase hybrid, two-phase can be common with the four-phase drive, five-phase three-phase must be used with their drives; Two-phase, four-phase hybrid step angle is 1.8 degrees more than a small size, great distance, and low noise; Five-phase hybrid stepping motor is generally 0.72, the motor step angle small, high resolution, but the complexity of drive circuits, wiring problems, such as the 5-phase system of 10 lines. Three-phase hybrid stepping motor step angle of 1.2 degrees, but according to the use of 1.8 degrees, the three-phase hybrid stepping motor has a two-phase mixed than the five-phase hybrid more pole will help electric folder symmetric angle, it can be more than two-phase, five-phase high accuracy, the error even smaller, run more smoothly. Stepper motor to maintain torque: stepper motor power means no rotation, the stator locked rotor torque. It is a stepper motor, one of the most important parameters, usually in the low-speed stepper motor torque at the time of close to maintain the torque. As the stepper motor output torque increases with the speed of constant attenuation, the output power also increases with the speed of change, so as to maintain torque on the stepper motor to measure the parameters of one of the most important. For example, when people say that the stepper motor 2N.m, in the absence of special circumstances that means for maintaining the torque of the stepper motor 2N.m. Precision stepper motors: stepper motor step angle accuracy of 3-5%, not cumulative. Start frequency of no-load: the stepper motor in case of no-load to the normal start of the pulse frequency, if the pulse frequency is higher than the value of motor does not start, possible to lose steps or blocking. In the case of the load, start frequency should be lower. If you want to achieve high-speed rotation motor, pulse frequency should be to accelerate the process, that is, the lower frequency to start, and then rose to a certain acceleration of the desired frequency (motor speed from low rise to high-speed). Step angle: that is to send a pulse, the electrical angle corresponding to rotation. Torque positioning: positioning torque stepper motor does not refer to the case of electricity, locked rotor torque stator. Operating frequency: step-by-step stepper motor can run without losing the highest frequency. Subdivision Drive: stepper motor drives the main aim is to weaken or eliminate low-frequency vibration of the stepper motor to improve the accuracy of the motor running. Reduce noise. If the step angle is 1.8 ° (full step) the two-phase hybrid stepping motor, if the breakdown of the breakdown of the number of drives for the 8, then the operation of the electrical pulse for each resolution of 0.072 °, the precision of motor can reach or close to 0.225 °, also depends on the breakdown of the breakdown of the drive current control accuracy and other factors, the breakdown of the number of the more difficult the greater the precision of control. 步进电机是一种将电脉冲转化为角位移的执行机构。通俗一点讲:当步进驱动器接收到一个脉冲信号,它就驱动步进电机按设定的方向转动一个固定的角度(及步进角)。您可以通过控制脉冲个数来控制角位移量,从而达到准确定位的目的;同时您可以通过控制脉冲频率来控制电机转动的速度和加速度,从而达到调速的目的。 步进电机不能直接接到交直流电源上工作,而必须使用专用设备——步进电机驱动器.步进电机驱动系统的性能,除与电机本身的性能有关外,也在很大程度上取决于驱动器的优劣。典型的步进电机驱动系统是由步进电机控制器、步进电机驱动器和步进电机本体三部分组成。步进电机控制器发出步进脉冲和方向信号,每发一个脉冲,步进电机驱动器驱动步进电机转子旋转一个步距角,即步进一步。步进电机转速的高低、升速或降速、启动或停止都完全取决于脉冲的有无或频率的高低。控制器的方向信号决定步进电机的顺时针或逆时针旋转。通常,步进电机驱动器由逻辑控制电路、功率驱动电路、保护电路和电源组成。步进电机驱动器一旦接收到来自控制器的方向信号和步进脉冲,控制电路就按预先设定的电机通电方式产生步进电机各相励磁绕组导通或截止信号。控制电路输出的信号功率很低,不能提供步进电机所需的输出功率,必须进行功率放大,这就是步进电机驱动器的功率驱
步进电机外文翻译
英文资料及其中文翻译Stepper motor is an electrical pulse will be converted into angular displacement of the implementing agencies. Put it in simple language-speaking: When the stepper drive pulse signal to a receiver, it drives stepper motor rotation direction by setting a fixed point of view (and the step angle). You can control the number of pulses to control the amount of angular displacement, so as to achieve the purpose of accurate positioning; At the same time, you can by controlling the pulse frequency to control the motor rotation speed and acceleration, so as to achieve the purpose of speed.Stepper motor directly from the AC-DC power supply, and must use special equipment - stepper motor drive. Stepper motor drive system performance, in addition to their own performance with the motor on the outside, but also to a large extent depend on the drive is good or bad. A typical stepper motor drive system is operated by the stepper motor controller, stepper motor drives and stepper motor body is composed of three parts. Stepper motor controller stepper pulse and direction signal, each made of a pulse, stepper motor-driven stepper motor drives a rotor rotating step angle, that is, step-by-step further. High or low speed stepper motor, or speed, or deceleration, start or stop pulses are entirely dependent on whether the level or frequency. Decide the direction of the signal controller stepper motor clockwise or counterclockwise rotation. Typically, the stepper motor drive circuit from the logic control, power driver circuit, protection circuit and power components. Stepper motor drive controller, once received from the direction of the signal and step pulse, the control circuit on a pre-determined way of the electrical power-phase stepper motor excitation windings of the conduction or cut-off signal. Control circuit output signal power is low, can not provide the necessary stepping motor output power, the need for power amplifier, which is stepper motor driven power drive part. Power stepper motor drive circuit to control the input current winding to form a space forrotating magnetic field excitation, the rotor-driven movement.Protection circuit in the event of short circuit, overload, overheating, such as failure to stop the rapid drive and motor.Motor is usually for the permanent magnet rotor, when the current flows through the stator windings, the stator windings produce a magnetic field vector. The magnetic field will lead to a rotor angle of rotation, making a pair of rotor and stator magnetic field direction of the magnetic field direction. When the stator rotating magnetic field vector from a different angle.Also as the rotor magnetic field to a point of view.An electrical pulse for each input, the motor rotation angle step. Its output and input of the angular displacement is proportional to the pulses, with pulse frequency proportional to speed. Power to change the order of winding, the electrical will be reversed. We can, therefore, control the pulse number, frequency and electrical power windings of each phase to control the order of rotation of stepper motor.Stepper motor types:Permanent magnet (PM). Magnetic generally two-phase stepper, torque and are smaller and generally stepping angle of 7.5 degrees or 15 degrees; put more wind for air-conditioning.Reactive (VR), the domestic general called BF, have a common three-phase reaction, step angle of 1.5 degrees; also have five-phase reaction. Noise, no torque has been set at a large number of out.Hybrid (HB), common two-phase hybrid, five-phase hybrid, three-phase hybrid, four-phase hybrid, two-phase can be common with the four-phase drive, five-phase three-phase must be used with their drives;Two-phase, four-phase hybrid step angle is 1.8 degrees more than a small size, great distance, and low noise;Five-phase hybrid stepping motor is generally 0.72, the motor step angle small, high resolution, but the complexity of drive circuits, wiring problems, such as the 5-phase system of 10 lines.Three-phase hybrid stepping motor step angle of 1.2 degrees, but according to the use of 1.8 degrees, the three-phase hybrid stepping motor has atwo-phase mixed than the five-phase hybrid more pole will help electric folder symmetric angle, it can be more than two-phase, five-phase high accuracy, the error even smaller, run more smoothly.Stepper motor to maintain torque: stepper motor power means no rotation, the stator locked rotor torque. It is a stepper motor, one of the most important parameters, usually in the low-speed stepper motor torque at the time of close to maintain the torque. As the stepper motor output torque increases with the speed of constant attenuation, the output power also increases with the speed of change, so as to maintain torque on the stepper motor to measure the parameters of one of the most important. For example, when people say that the stepper motor 2N.m, in the absence of special circumstances that means for maintaining the torque of the stepper motor 2N.m.Precision stepper motors: stepper motor step angle accuracy of 3-5%, not cumulative.Start frequency of no-load: the stepper motor in case of no-load to the normal start of the pulse frequency, if the pulse frequency is higher than the value of motor does not start, possible to lose steps or blocking. In the case of the load, start frequency should be lower. If you want to achieve high-speed rotation motor, pulse frequency should be to accelerate the process, that is, the lower frequency to start, and then rose to a certain acceleration of the desired frequency (motor speed from low rise to high-speed).Step angle: that is to send a pulse, the electrical angle corresponding to rotation.Torque positioning: positioning torque stepper motor does not refer to the case of electricity, locked rotor torque stator.Operating frequency: step-by-step stepper motor can run without losing the highest frequency.Subdivision Drive: stepper motor drives the main aim is to weaken or eliminate low-frequency vibration of the stepper motor to improve the accuracy of the motor running. Reduce noise. If the step angle is 1.8 °(full step) the two-phase hybrid stepping motor, if the breakdown of the breakdown of thenumber of drives for the 8, then the operation of the electrical pulse for each resolution of 0.072 °, the precision of motor can reach or close to 0.225 °, also depends on the breakdown of the breakdown of the drive current control accuracy and other factors, the breakdown of the number of the more difficult the greater the precision of control.步进电机是一种将电脉冲转化为角位移的执行机构。
步进电机的微机和单片机控制
步进电机的微机和单片机控制霍迎辉,陈宇翔 (广东工业大学自动化研究所,广州市 510090)摘 要:主要介绍了在windows 平台下实现对步进电机控制的一个实际系统。
本系统利用单片机控制步进电机,减少对CPU 资源的占用;步进电机的转速和步长在windows 下设置。
软件编程使用了“操作数+操作码”的结构,使得程序简练而实用。
关键词:步进电机;单片机;微机Stepper Motor Controlled Using PC &SCMH UO Y ing -hui ,CHE N Y u -xiang(Automation Institute ,G uangdong University of T echnology )Abstract :In this paper ,we proposed a practical system for controlling stepper m otor based on Windows.Theapplication of SC M ,which controls the stepper m otor ,cuts down the occupation of res ources of CPU.M oreover the rotation speed and the step length are m odulated on PC.The structureof ”operand &operator ”is applied ,which makes the programs sim ple and realistic.K eyw ords:stepper m otor ;SC M ;PC1 前言步进电机广泛应用于各种需要精确定位的场合,如数字机床等。
在没有齿轮的情况下,步值可以由每步90度到每步0.36度。
而且步进电机可以快速起停,并能直接接收数字量。
步进电机细分控制(英文)
1/17AN1495APPLICATION NOTE1INTRODUCTIONMicrostepping a stepper motor may be used to achieve one or both of two objectives; 1) increase the position resolution or 2) achieve smoother operation of the motor. In either case the basic the-ory of operation is the same.The simplified model of a stepper motor is a permanent magnet rotor and two coils on the stator separated by 90 degrees, as shown in Figure 1. In classical full step operation an equal current is delivered to each of the coils and the rotor will align itself with the resulting magnetic vector along one of the 45 degree axis. To step the motor, the current in one of the two coils is reversed and the rotor will rotate 90 degrees. The complete full step sequence is shown in figure 2. Half step drive,where the current in the coil is turned off for one step period before being turned on in the opposite direction, has been used to double the step resolution of a motor. In either full and half step drive,the motor can be positioned only at one of the 4 (8 for half step) defined positions.[4][5] Therefore,the number of steps per electrical revolution and the number of poles on the motor determine the resolution of the motor. Typical motors are designed for 1.8 degree steps (200 steps per revolution)or 7.5 degree steps (48 steps per revolution). The resolution may be doubled to 0.9 or 3.75 degrees by driving the motor in half step. Further increasing the resolution requires positioning the rotor at positions between the full step and half step positions.Figure 1. Model of stepper motorMICROSTEPPING STEPPER MOTOR DRIVEUSING PEAK DETECTING CURRENT CONTROL Stepper motors are very well suited for positioning applications since they can achieve very good positional accuracy without complicated feedback loops associated with servo sys-tems. However their resolution, when driven in the conventional full or half step modes of operation, is limited by the configuration of the motor. Many designers today are seeking alternatives to increase the resolution of the stepper motor drives. This application note will discuss implementation of microstepping drives using peak detecting current control where the sense resistor is connected between the bottom of the bridge and ground. Examples show the implementation of microstepping drives with several currently available chips and chip sets. REV . 2AN1495/0604AN1495 APPLICATION NOTEFigure 2. Full step sequence.Another issue occurs at low operating speeds. At low speeds, both the full and half step drive tend to make abrupt mechanical steps since the time the rotor takes to move to the next position can be much less than the step period. This stepping action contributes to jerky movement and mechanical noise in the system. Looking at the simplified model of the stepper motor in Figure 1, it can be seen that if the two coils were driven by sine and cosine waveforms the motor would operate as a syn-chronous machine and run very smoothly. These sinusoidal waveforms may be produced by a mi-crostepping drive .Microstepping can be implemented in either a voltage mode or current mode drive. In voltage mode drive, the appropriate duty cycle would be generated by the controller so that the voltage applied to the coil (Vsupply * duty cycle) is the appropriate value for the desired position. In current mode drives, the winding current is sensed and controlled to be the appropriate value for the desired po-sition. This application note will consider only current mode drive implemented using peak detecting current controllers.To understand the microstepping concept, consider the simplified model of the stepper motor as shown in Figure 1. As previously discussed when the two coils are energized with equal currents, the re-sulting magnetic vector will be at 45° and the permanent magnet of the rotor will align with that vec-tor. However, if the two coils are energized by currents of different magnitude, the resulting magnetic vector will be at an angle other than 45° and the rotor would attempt to align with the new magnetic vector. If one coil were driven with a current that was twice the current in the second coil the magnetic vector would be at 30°, as shown in Figure 3. For any given desired position, the re-quired currents are defined by the sine and cosine of the desired angle.To implement a microstepping drive, two D/A converters are used to set the current level in the coils of the motor, as shown in the block diagram in Figure 4.2/17AN1495 APPLICATION NOTE Figure 3. Example alignment of microstepingFigure 4. Block Diagram of microstepping motor drive.2MICROSTEPPING WITH THE L6208In a typical application the L6208, which integrates two H-Bridges with the current control, drives a bipolar stepper in either full or half step modes. The internal state machine generates the full step or half step sequence from the clock and direction inputs. [1] Although at first glance it is not obvious that the L6208 may be used in a microstepping application, it is possible since the current control circuits have separate reference inputs.To implement a microstepping application, a variable voltage proportional to the desired output cur-rent must be applied to each of the reference pins. In the block diagrams above, the two required D/A converters provide the required voltages. A simple and inexpensive alternative to a D/A con-3/17AN1495 APPLICATION NOTEverter chip is to use a counter/timer in the microprocessor to generate a PWM output for each phase and pass this through a voltage divider and low pass filter to get the desired voltage. The Vref input voltage is equal to the microprocessor power supply voltage times the divider ratio of the resistor divider times the PWM duty cycle. Figure 5 shows the connection between a microcontroller and the L6208. The complete circuit schematic for the power section is shown in appendix A.Since the L6208 includes an internal phase generation circuit, this circuit must be synchronized to the externally provided reference voltages. Again a simple solution is possible. The initial state of the decoding logic after reset is known and may be used as the starting state. After applying a reset to the L6208, either at power up or by forcing a reset from the microprocessor, the full-scale voltage is applied to both Vref pins to align the stepper motor to the known state that corresponds to one of the full step positions. Once the motor is aligned, the references can be reduced to 70.7%, which is the correct value for the currents for the 45-degree position in the microstepping sequence. After the motor is aligned the microcontroller can move through the sine/cosine table to generate the ap-propriate reference levels to move in either direction. The software also has to set the appropriate direction on the CW/CCW pin and generate a clock pulse for each phase reversal that is required. This occurs whenever the phase crosses a 90° boundary in the sine table. By operating the L6208 in the full step mode and providing clock signals at the appropriate time, the decoding logic will out-put the correct phase information for the bridges. Using the L6208 in the half step mode with the appropriate clock signals can improve the performance at the zero cross over of the current, as will be discussed later.Figure 5. Circuit connections for the L6208Figure 6 shows the operating waveforms when using the L6208 in full step mode and varying the reference inputs to achieve microstepping. Trace 1 is the clock input to the L6208. Traces 2 and 3 on the plot are the VrefA and VrefB inputs applied to the L6208. Trace 4 is the motor current in chan-nel B. Although the current has the discontinuities near zero that are typical of a peak detection cur-rent control method, the resulting output matches the desired sine wave reasonably well.4/17AN1495 APPLICATION NOTE Figure 6. Microstepping waveforms: Typical OperationFigure 7. Microstepping waveforms: Current can not follow desired sine wave3SPEED LIMITATIONSSince the motor coil is primarily an inductance, the rate of current change in the coils is limited by the L/R time constant of the motor. As the motor is operated at higher speeds, the L/R time constant of the motor limits the rate of current change and the current can no longer follow the desired sine wave. Figure 7 shows the motor current at a higher rotational frequency. On this scope trace, we see two effects. First, the filter on the reference voltage is starting to roll off the reference signal and5/17AN1495 APPLICATION NOTEsecond, the motor current is limited by the motor time constant and it begins to look more like a triangle waveform than the desired sine wave. Although moving the pole of the filter on the refer-ence voltage will make the reference signal appear more ideal, it will have little effect on the motor current at this point since the motor current is primarily limited by the L/R characteristics of the mo-tor. When approaching this point, the motor will run smoothly in full step mode and the micropro-cessor could easily change to full step drive.If the step rate is increased further, the motor will stall when the current can no longer reach a value large enough to produce the required torque. Figure 8 shows a typical current waveform when the motor has stalled. The almost pure triangular current waveform is similar to the triangular waveform that would result if the motor were being driven in the full step mode at this step rate. At this oper-ating point the current is entirely controlled by the L/R time constant of the motor and no chopping is occurring.Figure 8. Waveforms when motor has stalled4SLOW VS. FAST DECAY MODEWhen implementing current controlled motor drives, the designer has a choice of the recirculation path the current flows in during the "off" time. Figure 9 shows the two recirculation options imple-mented in the L6208. Applying the chopping to only one side of the bridge allows the current to re-circulate around a low voltage loop, in the upper transistors with the L6208. Since the rate of change of the current is controlled primarily by the L/R time constant of the motor, the current decays rela-tively slowly, hence the designation of slow decay mode. However applying the chopping to both sides of the bridge results in the current recirculating back to the power supply and a higher voltage across the coil, hence a fast decay mode. The L6208 also implements a type of synchronous rec-tification that turns on the MOS transistor in parallel with the conducting diode to reduce the power dissipation. [1]The selection of the decay mode influences the operation of a microstepping drive in several ways. The most obvious is the magnitude of the ripple current. Drives implemented using the fast decay mode will have, for the same off time or chopping frequency, a higher ripple current than drives im-plemented using a slow decay mode. This difference in itself is not significant for most stepper mo-6/17AN1495 APPLICATION NOTEtor drives. Issues with the stability of the current control loop are discussed elsewhere [3].When microstepping at a relatively high speed, the selection of the decay mode affects the ability of the drive to follow the desired current level. At any time, the rate of change of current is deter-mined by the inductance of the motor and the voltage across the coil. In the slow decay mode, the voltage across the coil during the off time is only the drop across one transistor and one diode so the current changes very slowly. As the desired current level is lowered, it is the rate of change dur-ing the off time that determines how quickly the current transitions to the new level. At low speeds, the effect may not be too noticeable. However, at higher speeds, the motor current cannot decay fast enough to follow the desired decreasing slope of the sine wave. During this time the current change is limited by the time constant imposed by the motor inductance and the slow decay path and can remain higher than the set value. The current will continue to decay at the slow rate until a phase reversal occurs, at which point the bridge reverses, applying the full supply voltage across the coil, effectively putting the bridge in a fast decay mode and the current will decay quickly to zero. Selecting the fast decay mode can improve the ability of the drive to follow fast decreases in the current. The waveforms in Figure 6 are achieved using the fast decay mode.The ability of the drive to increase current on the upper slope of the sine wave is not affected by the choice of the decay mode since the voltage applied to the coil during the on time is the same. Figure 9. PWM current control decay modes.7/17AN1495 APPLICATION NOTE 8/175MINIMUM CURRENT ISSUESWhen operating a chopping current control that has a minimum duty cycle, the current cannot be taken below a level that is effectively set by the motor resistance and the minimum duty cycle. Con-stant off time controls, like the L6208, have a minimum on time that is set primarily by the propaga-tion delays from the end of the off time until the comparator detects a current above the threshold and retriggers the monostable putting the bridge in the recirculation mode again. This minimum on time and the off time set by the monostable set a minimum working duty cycle for the circuit. When this duty cycle is applied to the motor, a current will be established. If a reference corresponding to a current lower than this minimum is set on the input, the circuit will detect that the motor current is above the reference. However, since the IC is already operating at its minimum duty cycle, the cur-rent can not go any lower and thus will not reach the current level desired by the reference level.The minimum duty cycle in other controllers can some times be adjusted. The minimum on time in the L6506, for example, is set by the width of the sync pulse. By varying the duty cycle of the oscil-lator, the minimum duty cycle of the output can also be changed. Since the sync pulse is also used to mask the switching noise in the system, reducing the minimum duty cycle is not always possible.[3]Figure 10 shows the operating waveforms at the minimum current level. The traces in the oscilo-graph are:Ch 1 :Voltage on output pinCh 2 :V refCh 3 :V senseCh 4 :Load current (20mA/div)Figure 10. Oscillograph of the minimum currentAt the start of each cycle the bridge is turned on and the motor current flows through the sense re-sistor to produce the voltage V sense . However at this operating point the sense voltage is already greater than the Vref input voltage, as can be seen in Figure 10. The comparator will detect that V senseis greater than Vref and cause the circuit switch the bridge into the recirculation mode andAN1495 APPLICATION NOTE the output is switched off after a delay that is determined by the response time of the circuit. The output pulse width, and hence the operating current, are set by the response of the circuit to a con-dition where the current sense comparator detects a current above the set value as soon as the drive is turned on. Since this pulse width can not be reduced further, the current that flows is the minimum that the device can regulate. In Figure 10, the minimum current is approximately 100mA. The minimum current level means a nonlinear transfer function exists between reference in (usually a voltage) to current out. Figure 11 shows the resulting transfer function between reference and out-put current.Figure 11. Transfer function showing nonlinearityThe transfer function also depends on the chopping mode, fast decay (enable chopping) or slow decay (phase chopping) as shown in Figure 11. In slow decay mode the current changes very slow-ly during recirculation and has a small ripple value. When operating in fast decay the transfer func-tion also has a discontinuity in the slope at low levels. At the minimum current level, the duty cycle is small and when operating at this point the current typically is discontinuous, that is the current rises to a peak value and decays back to zero during each cycle. The flat section of the current transfer function corresponds to this minimum current. When the reference is increased, the device begins to regulate current however the device will still operate in the discontinuous mode. Continu-ing to increase the reference, the device will begin to operate in the continuous current mode, where the current does not decay to zero in each cycle. When the current changes from discontinuous to continuous, the slope of the transfer function changes. The result is that there are two discontinui-ties in the transfer function, one set by the minimum current and one set by the change in slope. In theory the slow decay mode could also have two discontinuities, however in practical examples the minimum current is reached before the current goes discontinuous.The minimum achievable current effectively sets a limit on the number of microsteps per step by setting minimum current for the first microstep. Since the fast decay mode has a lower minimum current, fast decay can be used to minimize the effect of the minimum current, but will introduce another error due to the change of the slope. The latter can be compensated for by adjusting the DAC value.It is, however, possible to get zero current in a phase by disabling the bridge when zero current is desired in that phase. When using drivers that have an enable input for each bridge simply disabling the bridge will force the current to zero. The L6208, however, does not have a separate enable input for each bridge so we need to use another trick of the logic to disable the bridge at the appropriate time. When driven in the half step mode, one bridge is disabled in each of the even states [2]. This operating sequence can be used to disable the bridge at the appropriate times. To achieve this, op-9/17AN1495 APPLICATION NOTEerate the L6208 in half step mode and apply a pulse to the clock input at the same time that the desired current is set to zero. At the next change of current apply a second pulse to the clock input and set the current value for the first microstep. The step sequence generator in the L6208 will cause the change from current in one direction in the bridge, to the bridge being disabled, to current in the reverse direction as shown in Figure 12.Figure 12. Microstepping waveforms with improved performance at zero current.The effects of the minimum current can be seen in the motor movement as errors in the motor po-sition or as a jerky movement in a constant speed movement. How much the minimum current af-fects the drive depends primarily on the number of microsteps implemented per step. Since zero current can be achieved as described above, the positions at the 90 degree intervals where one coil is driven by zero current and the other is driven by the full scale current can easily be implemented. However, the next microstep where the current in one coil is small is most affected. If the desired current for any position is less than the minimum current, an error occurs. If the current required for the first microstep after the zero current position is greater than the minimum current, no error is contributed. Fortunately, since the desired current profile is a sine wave, the first step after the zero crossing has the largest relative increase in current of any microstep. If the required current for this first microstep is greater then the minimum current the device can regulate, there will be no error in the current to the motor due to the minimum current.If the design required that one step (90 Deg.) be divided into 16 microsteps, the angle for the first step would be 5.625 Deg. The sine of 5.625 degrees is 0.098. When using an 8-bit D/A, the closest available value would correspond to an input of 25 out of 255. No other microstep needs a current less than this (except the 0 as discussed above). As long as the minimum current is less than the value corresponding 25/255 of the peak current, there will be no noticeable error contributed by the minimum current. Another way to express this that no error will be noticeable if the output current can be regulated to plus or minus 1 LSB over the range 24 to 255. There is no system level require-ment to maintain the accuracy for inputs less than 24.10/17AN1495 APPLICATION NOTE6L6506 & L6203/L298Microstepping drives can be implemented using the L6506 controller and bridge IC's like the L6201, L6202, L6203 and L298. The main difference between the standard half step application and a mi-crostepping application is that the two references of the L6506 are set by D/A converter outputs. Figure 13 shows a microstepping application using the L6506 and the L6203. Outputs Px 1 through Px 4 from the microprocessor set the phase for the L6506/L6203 combination and output Px 5 and PX 6 are used to enable the bridges. Again, the D/A function could be implemented using the PWM outputs of the microprocessor as was done in the example above or it could be implemented using and integrated D/A. The same logic configuration can be used with the L6201, L6202 or L298. When using the typical connection between the L6506 and the L6203 (as shown in Figure 13a), the PWM signal is applied to one of the phase inputs (the phase that is normally high) and you get the slow decay mode of operation.To implement the fast decay mode of operation, the PWM signal needs to be applied to the EN-ABLE inputs of the L6203s. This can be accomplished by rearranging the connections from the mi-croprocessor. Inputs IN 1 and IN 2 of the L6203s are disconnected from the L6506 and connected directly to the Px 1 through Px 4 outputs of the microprocessor, which will continue to provide the phase information as before. The two PWM current control loops in the L6506 are then used to con-trol the ENABLE inputs of the two L6203, as shown in Figure 13b. Px 5 and Px 6 are now connected to the inputs of the L6506 so that each bridge can be disabled to get zero current. Finally the Power On Reset (POR) is connected to the RESET input of the L6506 to disable the bridge during power up.Figure 13a. Microstepping using L6506 and L6203 (Slow Decay)11/17AN1495 APPLICATION NOTEFigure 13b. Microstepping using L6506 and L6203 (Fast Decay)7PBL3717, TEA3717, TEA3718 AND L6219Devices like the PBL3717, TEA3717 TEA3718 and L6219 can also be used to implement mi-crostepping. The main limitation in these devices is that, due to their internal connections, they can only implement the slow decay mode. The microstepping application is the same as the typical ap-plication for the device except that D/A converters must control the reference pins. With these de-vices since the reference is designed to operate from 5V and includes an internal voltage divider, a low impedance output must be used to drive the reference. If the PWM from the microprocessor is used for the D/A function, then only an RC filter is used without the second resistor for the divider. The resulting signal must them be buffered by an amplifier before driving the reference input. The connections between the microprocessor and the PBL3717 family of devices are shown in Fig-ure 14. For the best resolution it is suggested to set the I0 and I1 inputs to select the maximum cur-rent level. One should also be aware that the specifications of the L6219 have a minimum input reference voltage level. This level must be respected and will then determine the minimum current that can be achieved in a microstepping circuit.12/17AN1495 APPLICATION NOTE Figure 14. Microstepping connection using PBL37178CONCLUSIONAlthough they were not designed specifically to implement microstepping, many of the integrated motor control/drive circuits can be used to implement microstepping stepper motor drives. The lim-its imposed by a peak detecting current control technique and the selected decay mode will directly affect the performance of the motor drive. Specifically it's ability to follow the desired current wave-form. So long as these limits allow the designer to achieve the desired resolution in the microstep-ping application the devices provide a cost effective implementation.9REFERENCES[1] A NEW FULLY INTEGRATED STEPPER MOTOR DRIVER IC, Domenico Arrigo, Thomas L. Hopkins, Angelo Genova, Vincenzo Marano, and Aldo Novelli, Proceedings of PCIM 2001, Septer-mber 2001, Intertech Communication[2] L6208 Data Sheet[3] STEPPER MOTOR DRIVES, COMMON PROBLEMS AND SOLUTIONS, AN460, T. Hopkins, STMicroelectronics[4] L297 Data Sheet[5] THE L297 STEPPER MOTOR CONTROLLER, AN470, STMicroelectronics[6] STEPPER MOTOR DRIVING, AN235, H. Sax, STMicroelectronics13/17AN1495 APPLICATION NOTE APPENDIX AFigure 15. Scheme of the EVAL6208N14/17AN1495 APPLICATION NOTEAPPENDIX BThe following is an excerpt from the firmware which executes on the ST7264 based control which is part of the Practispin evaluation system. This code segment is executed when the decision has been made that it is time for the L6208 to take the next microstep (either forward or reverse).; PB.4 is the L6208 clock pin; PB.5 is the L6208 reset pin; stepstate is a byte variable which controls the motor stepping.; torquscaler is a byte used to modulate the normalized sine wave values read from the table to set the current level; TAOC1LR is a register that controls Vrefa (via the duty cycle into the low pass filter) ; TBOC1LR is a register that controls Vrefb (via the duty cycle into the low pass filter) bres PBDR,#4; take clock back low ready to generate rising edge lat-erbset PBDR,#5; normal state for resetjumpifflagclear forward,doclockrev; jump if direction is reverse;direction is forwardinc stepstatejrne for002; skip if stepstate has not rolled over to zerobres PBDR,#5; activate reset to maintain sync (just for added noiseimmunity insurance)for002:ld a,stepstateand a,#%00011111; use only lower five bits as index for table lookupld x,a ; save index; on indexes 8 and 9, clock L6208 to sequence through zero and then polarity reversal and a,#%00001110cp a,#8 ; 8 or 9jrne for001bset PBDR,#4 ; rising edge for clockfor001:ld a,(microtable1,x) ; get normalized value from tableld y,torquescalermul y,a ; y:a = (table value) * torquescalerld TAOC1LR,y ; duty cycle = (table value) * torquescaler/256; repeat for phase Bld a,(microtable2,x)ld y,torquescalermul y,ald TBOC1LR,yjp pwmend; end of routine for forward stepdoclockrev:;direction is reversedec stepstatejrne rev002bres PBDR,#5; activate reset to maintain syncrev002:ld a,stepstateand a,#%00011111ld x,ainc a; 7 or 8 =>> 8 or 9and a,#%00001110cp a,#8 ; 8 or 915/17AN1495 APPLICATION NOTE16/17jrne rev001bset PBDR,#4 ; rising edge for clockrev001:ld a,(microtable1,x)ld y,torquescalermul y,ald TAOC1LR,yld a,(microtable2,x)ld y,torquescalermul y,ald TBOC1LR,yjp pwmend; The lookup table holds the magnitude of a sine wave normalized to a peak value of 256. ; Each line of 16 entries represents 90 degrees or one full step (thus 16 microsteps per step).; Table reference labels at 45 degrees (microtable1) and 135 degrees (microtable2) are provided for convenience; to allow easy lookup of two waveforms with 90 degree phase relationship.; Since only five bits (0 to 31) of the stepstate table index are used, references using microtable1 roll over through; just the first two lines of the table while references using microtable2 stay within the second and third lines; of the overall table.microtable1:; degrees 45 90dc.b180,197,212,224,235,244,250,253,254,253,250,244,235,224,212,197microtable2:; degrees 135 0dc.b180,161,141,120,097,074,049,024,000,024,049,074,097,120,141,161; degrees 45 +90dc.b180,197,212,224,235,244,250,253,254,253,250,244,235,224,212,197Table 1. Revision HistoryDate Revision Description of ChangesApril 20021First IssueJune 20042Replaced the Appendix B that contains assembler code for an ST7264.Changed the Style-sheet following the new "Corporate T echnicalPubblications Design Guide"。
【资料】步进电机和伺服电机的系统控制中英文翻译资料
【关键字】资料SELECTING THE MOTOR THAT SUITS YOUR APPLICATION Motion control, in its widest sense, could relate to anything from a welding robot to the hydraulic system in a mobile crane. In the field of Electronic Motion Control, we are primarily concerned with systems falling within a limited power range, typically up to about 10HP (7KW), and requiring precision in one or more aspects. This may involve accurate control of distance or speed, very often both and sometimes other parameters such as torque or acceleration rate. In the case of the two examples given, the welding robot requires precise control of both speed and distance; the crane hydraulic system uses the driver as the feedback system so its accuracy varies with the skill of the operator. This wouldn’t be considered a motion control system in the strict sense of the term. Our standard motion control system consists of three basic elements:Fig. 1 Elements of motion control systemThe motor,This may be a stepper motor (either rotary or linear), a DC brush motor or a brushless servo motor. The motor needs to be fitted with some kind of feedback device unless it is a stepper motor.Fig. 2 shows a system complete with feedback to control motor speed. Such a system is known as a closed-loop velocity servo system.Fig. 2 Typical closed loop (velocity) servo systemThe drive,this is an electronic power amplifier that delivers the power to operate the motor in response to low-level control signals. In general, the drive will be specifically designed to operate with a particular motor type –you can’t use a stepper drive to operate a DC brush motor, for instance.Application Areas of Motor TypesStepper MotorsStepper Motor BenefitsStepper motors have the following benefits:• Low cost• Ruggedness• Simplicity in construction• High reliability• No maintenance• Wide acceptance• No tweaking to stabilize• No feedback components are needed• They work in just about any environment• Inherently more failsafe than servo motors.There is virtually no conceivable failure within the stepper drive module that could cause the motor to run away. Stepper motors are simple to drive and control in an open-loop configuration. They only require four leads. They provide excellent torque at low speeds, up to 5 times the continuous torque of a brush motor of the same frame size or double the torque of the equivalent brushless motor. This often eliminates the need for a gearbox. A stepper-driven-system is inherently stiff, with known limits to the dynamic position error.Stepper Motor DisadvantagesStepper motors have the following disadvantages:• Resonance effects and relatively long settling times• Rough performance at low speed unless a micro step drive is used• Liability to undetected position loss as a result of operating open-loop• They consume current regardless of load conditions and therefore tend to run hot• Losses at speed are relatively high and can cause excessive heating, and they are frequently noisy (especially at high speeds).• They can exhibit lag-lead oscillation, which is difficult to damp. There is a limit to their available size, and positioning accuracy relies on the mechanics (e.g., ball screw accuracy). Many of these drawbacks can be overcome by the use of a closed-loop control scheme. Note: The Comp motor Zeta Series minimizes or reduces many of these different stepper motor disadvantages. There are three main stepper motor types:• Permanent Magnet (P.M.) Motors• Variable Reluctance (V.R.) Motors• Hybrid MotorsWhen the motor is driven in its full-step mode, energizing two windings or “phases” at a time (see Fig. 3), the torque available on each step will be the same (subject to very small variations in the motor and drive characteristics). In the half-step mode, we are alternately energizing two phases and then only one as shown in Fig. 4. Assuming the drive delivers the same winding current in each case, this will cause greater torque to be produced when there are two windings energized. In other words, alternate steps will be strong and weak. This does not represent a major deterrent to motor performance—the available torque is obviously limited by the weaker step, but there will be a significant improvement in low-speed smoothness over the full-step mode.Clearly, we would like to produce approximately equal torque on every step, and this torque should be at the level of the stronger step. We can achieve this by using a higher current level when there is only one winding energized. This does not over dissipate the motor because the manufacturer’s current rating assumes two phases to be energized the current rating is based on the allowable case temperature). With only one phase energized, the same total power will be dissipated if the current is increased by 40%. Using this higher current in the one-phase-on state produces approximately equal torque on alternate steps (see Fig. 5).Fig. 3 Full step currentFig. 4 Half step currentFig.5 Half step current, profiledWe have seen that energizing both phases with equal currents produces an intermediate step position half-way between the one-phase-one positions. If the two phase currents are unequal, the rotor position will be shifted towards the stronger pole. This effect is utilized in the micro stepping drive, which subdivides the basic motor step by proportioning the current in the two windings. In this way, the step size is reduced and the low-speed smoothness is dramatically improved. High-resolution micro step drives divide the full motor step into as many as 500 micro steps, giving 100,000 steps per revolution. In this situation, the current pattern in the windings closely resembles two sine waves with a 90°phase shift between them (see Fig. 6). The motor is now being driven very much as though it is a conventional AC synchronous motor. In fact, the stepper motor can be driven in this way from a 60 Hz-US (50Hz-Europe) sine wave source by including a capacitor inseries with one phase. It will rotate at 72 rpm.Fig. 6 Phase currents in micro step modeStandard 200-Step Hybrid MotorThe standard stepper motor operates in the same way as our simple model, but has a greater number of teeth on the rotor and stator, giving a smaller basic step size. The rotor is in two sections as before, but has 50 teeth on each section. The half-tooth displacement between the two sections is retained. The stator has 8 poles each with 5 teeth, making a total of 40 teeth (see Fig. 7).Fig.7 200-step hybrid motorIf we imagine that a tooth is placed in each of the gaps between the stator poles, there would be a total of 48 teeth, two less than the number of rotor teeth. So if rotor and stator teeth are aligned at 12 o’clock, they will also be aligned at 6 o’clock. At 3 o’clock and 9 o’clock the teeth will be misaligned. However, due to the displacement between the sets of rotor teeth, alignment will occur at 3 o’clock and 9 o’clock at the other end of the rotor.The windings are arranged in sets of four, and wound such that diametrically-opposite poles are the same. So referring to Fig. 7, the north poles at 12 and 6 o’clock attract the south-pole teeth at the front of the rotor; the south poles at 3 and 9 o’clock attract the north-pole teeth at the back. By switching current to the second set of c oils, the stator field pattern rotates through 45°. However, to align with this new field, the rotor only has to turn through 1.8°. This is equivalent to one quarter of a tooth pitch on the rotor, giving 200 full steps per revolution.Note that there are as many detent positions as there are full steps per rev, normally 200. The detent positions correspond with rotor teeth being fully aligned with stator teeth. When power is applied to a stepper drive, it is usual for it to energize in the “zero phase” state in which there is current in both sets of windings. The resulting rotor position does not correspond with a natural detent position, so an unloaded motor will always move by at least one half steps at power-on. Of course, if the system was turned off other than in the zero phase state, or the motor is moved in the meantime, a greater movement may be seen at power-up.Another point to remember is that for a given current pattern in the windings, there are as many stable positions as there are rotor teeth (50 for a 200-step motor). If a motor isde-synchronized, the resulting positional error will always be a whole number of rotor teeth or a multiple of 7.2°. A motor cannot “miss” individual steps – position errors of one or two steps must be due to noise, spurious step pulses or a controller fault.Fig. 8 Digital servo driveDigital Servo Drive OperationFig.8 shows the components of a digital drive for a servo motor. All the main control functions are carried out by the microprocessor, which drives a D-to-A converter to produce an analog torque demand signal. From this point on, the drive is very much like an analog servo amplifier.Feedback information is derived from an encoder attached to the motor shaft. The encoder generates a pulse stream from which the processor can determine the distance traveled, and by calculating the pulse frequency it is possible to measure velocity.The digital drive performs the same operations as its analog counterpart, but does so by solving a series of equations. The microprocessor is programmed with a mathematical model (or “algorithm”) of the equivalent analog system. This model predicts the behavior of the system. It also takes into account additional information like the output velocity, the rate of change of the input and the various tuning settings.To solve all the equations takes a finite amount of time, even with a fast processor –this time is typically between 100ms and 2ms. During this time, the torque demand must remain constant at its previously-calculated value and there will be no response to a change at the input or output. This “update time” therefore becomes a critical factor in the performance of a digital servo and in a high-performance system it must be kept to a minimum.The tuning of a digital servo is performed either by pushbuttons or by sending numerical data from a computer or terminal. No potentiometer adjustments are involved. The tuning data is used to set various coefficients in the servo algorithm and hence determines the behavior of the system. Even if the tuning is carried out using pushbuttons, the final values can be uploaded to a terminal to allow easy repetition.Some applications, the load inertia varies between wide limits – think of an arm robot that starts off unloaded and later carries a heavy load at full extension. The change in inertia may well be a factor of 20 or more, and such a change requires that the drive isre-tuned to maintain stable performance. This is simply achieved by sending the new tuning values at the appropriate point in the operating cycle.步进电机和伺服电机的系统控制运动控制,在其最广泛的意义上说,可能与任何移动式起重机中焊接机器人液压系统有关。
步进电机概述论文翻译英文版
外文文献:Knowledge of the stepper motorWhat is a stepper motor:The stepping motor as executing components, electromechanical integration is one of the key products, widely used in a variety of automatic control systems. With the development of microelectronics and computer technology, the stepper motor demand grow with each passing day, has been applied in various fields of the national economy.Stepping motor is a kind of electrical pulses into angular displacement of the implementing agencies. When stepping drive receives a pulse signal, it drives stepper motor rotate in the direction set by a fixed angle ( called the " step " ), it is the rotation at a fixed angle step by step operation. The number of pulses to control the amount of angular displacement through the control, so as to achieve the purpose of accurate positioning; also can control the pulse frequency to control motor rotation speed and acceleration, so as to achieve the purpose of speed. Special motor stepper motor control can be used as a, using its no accumulation of error ( accuracy of 100% ) characteristics, widely used in all kinds of open-loop control.Now more commonly used step motor comprises stepper motor ( VR ), permanent magnet stepper motor ( PM ), hybrid stepping motor ( HB ) and single-phase stepping motor.Permanent magnet stepper motor for general two-phase, torque and small volume, the step angle is 7.5 degree or 15 degree;Reaction stepping motor is generally three-phase, can achieve a high torque output, step angle is 1.5 degrees, but the noise and vibration are great. The rotor magnetic circuit made of soft magnetic material reaction stepper motor, a multi-phase excitation winding stator, using magnetic torque changes.Hybrid stepping motor is mixed the advantages of permanent magnet type andreaction type. It is divided into two phase and five phase: two-phase stepper angle is 1.8 degree and five phase stepper angle is 0.72 degrees. Application of the stepping motor is the most widely, is also this subdivision driving of stepper motor selection scheme.Some of the basic parameters of step motor:The natural step motor:It says every hair a step pulse signal control system, motor rotation angle. Motor factory is a step angle values, such as type 86BYG250A motor is given a value of 0.9°/1.8 °( said a half step of work is 0.9 °, the whole step of work is 1.8 °), this step can be called ' motor fixed step ', it doesn't have to be the actual motor work when the real step angle, angle and drive the real steps.Stepper motor phase number:Is the number of coils inside the motor, commonly used in a two-phase, three-phase, four phase, five phase stepper motor. The number of motor phase is different, the step angle is also different, the general two-phase motor step angle is 0.9°/1.8 °, three-phase 0.75 °/1.5 °, five phase of 0.36 °/0.72 °. In the absence of subdivision drive, users mainly rely on different phases of the stepper motor to meet their own requirements of step angle. If you use a subdivision driver, is ' phase ' will become meaningless, users only need to change the fine fraction in the drive, you can change the step angle.Keep the torque ( HOLDINGTORQUE ):Is the stepper motor power but there is no rotation, the stator locked rotor torque. It is one of the most important parameters of step motor, usually stepper motor in the low-speed torque to keep the torque. Because of the larger output torque stepper motor with speed and continuous decay, increases the output power with the speed of change, so keep the torque becomes one of the most important parameters of step motor. For example, when people say 2N.m stepper motor, in the absence of exceptional circumstances described in that refers to keep the torquemotor for the 2N.m step.DETENTTORQUE:DETENTTORQUE:Refers to the stepper motor is not energized condition, the stator locked rotor torque. DETENTTORQUE does not have a unified way of translation in China, easy to make people misunderstand; as the rotor reaction stepper motor is not permanent magnetic material, so it has no DETENTTORQUE.Some of the characteristic of step motor:The 1 stepper motor step angle accuracy for 3-5%, and no accumulation.2 stepper motor appearance allows the maximum temperature.Stepper motor temperature is too high will first make the motor magnetic material demagnetization, resulting in lower torque and loss, so the highest temperature of motor appearance allows should depend on the different motor demagnetization magnetic materials; generally speaking, demagnetization point magnetic material in 130 degrees Celsius above, some even as high as 200 degrees Celsius stepping motor, so the surface temperature at 80-90 degrees Celsius completely normal.3 stepper motor torque will decrease with the increase of rotational speed.When the stepper motor rotates, the electrical inductance of the winding will form a reverse electromotive force; the higher the frequency, the greater the reverse emf. Under the influence of it, the motor with frequency ( or speed ) increase and the phase current is reduced, resulting in lower torque.4 stepper motor speed can be normal operation, but if it is more than a certain speed will not start, and accompanied by howling.Stepper motor is a technical parameter: no-load start frequency, namely the stepper motor under no-load condition can pulse frequency start, if the pulsefrequency is higher than the value, the motor can not start properly, may have lost step or stall. In under the condition of the load, start frequency should be less. If you want to enable the motor to rotate at high speed, pulse frequency should accelerate the process is started, the lower frequency, and then according to certain acceleration up to high frequency desired ( motor speed from low speed to high speed ).Characteristics of stepper motor with its significant, play an important purpose in the era of digital manufacturing. With the different development of digital technology and stepper motor itself technology improves, the stepper motor will be applied in more fields.How to determine the stepper motor driver DC power supply:A. Determination of the voltageHybrid stepping motor driver power supply voltage is generally a wide range (such as the IM483 supply voltage of 12 ~ 48VDC), the supply voltage is usually based on the work of the motor speed and response to the request to choose. If the motor operating speed higher or faster response to the request, then the voltage value is high, but note that the ripple voltage can not exceed the maximum input voltage of the drive, or it may damage the drive.B. Determination of CurrentPower supply current is generally based on the output phase current drive I to determine. If a linear power supply, power supply current is generally preferable 1.1 to 1.3 times the I; if we adopt the switching power supply, power supply current is generally preferable to I, 1.5 to 2.0 times.The main characteristics of stepping motor:A stepper motor drive can be added operate pulse drive signal must be no pulse when the stepper motor at rest, such asIf adding the appropriate pulse signal, it will to a certain angle (called the step angle) rotation. Rotation speed and pulse frequency is proportional to.2 Dragon step angle stepper motor version is 7.5 degrees, 360 degrees around,takes 48 pulses to complete.3 stepper motor has instant start and rapid cessation of superior characteristics. Change the pulse of the order of 4, you can easily change the direction of rotation. Therefore, the current printers, plotters, robotics, and so devices are the core of the stepper motor as the driving force.Stepper motor control exampleWe use four-phase unipolar stepper motor as an example. The structure shown in Figure 1:Four four-phase winding leads (as opposed to phase A1 A2 B1 phase phase B2) and two public lines (to the power of positive). The windings of one phase to the power of the ground. So that the windings will be inspired. We use four-phase eight-beat control, ie, 1 phase 2 phase alternating turn, would enhance resolution.0.9 °per step can be transferred to control the motor excitation is transferred in order as follows:If the requirements of motor reversal, the transmission excitation signal can be reversed. 2 control schemeControl system block diagram is as followsThe program uses AT89S51 as the main control device. It is compatible with the AT89C51, but also increased the SPI interface and the watchdog module, which not only makes the debugging process becomes easy and also more stable. The microcontroller in the program mainly for field signal acquisition and operation of the stepper motor to calculate the direction and speed information. Then sent to the CPLD.CPLD with EPM7128SLC84-15, EPM7128 programmable logic device of large-scale, for the ALTERA company's MAX7000 family. High impedance, electrically erasable and other characteristics, can be used for the 2500 unit, the working voltage of +5 V. CPLD receives information sent from the microcontroller after converted to the corresponding control signal output to the stepper motor drive. Put the control signal drives the motor windings after the input, to achieve effective control of the motor.2.1 The hardware structure of the motor driveMotor drive using the following circuit:R1-R8 in which the resistance value of 320Ω. R9-R12 resistance value 2.2KΩ. Q1-Q4 as Darlington D401A, Q5-Q8 for the S8550. J1, J2 and the stepper motor connected to the six-lead。
步进电机中英文翻译
步进电机知识什么是步进电机步进电机是一种将电脉冲转化为角位移的执行机构。
通俗一点讲:当步进驱动器接收到一个脉冲信号,它就驱动步进电机按设定的方向转动一个固定的角度(及步进角)。
您可以通过控制脉冲个数来控制角位移量,从而达到准确定位的目的;同时您可以通过控制脉冲频率来控制电机转动的速度和加速度,从而达到调速的目的。
步进电机分哪几种步进电机分三种:永磁式(PM),反应式(VR)和混合式(HB)永磁式步进一般为两相,转矩和体积较小,步进角一般为7.5度或15度;反应式步进一般为三相,可实现大转矩输出,步进角一般为1.5度,但噪声和振动都很大。
在欧美等发达国家80年代已被淘汰;混合式步进是指混合了永磁式和反应式的优点。
它又分为两相和五相:两相步进角一般为1.8度而五相步进角一般为 0.72度。
这种步进电机的应用最为广泛。
什么是保持转矩(HOLDING TORQUE)保持转矩(HOLDING TORQUE)是指步进电机通电但没有转动时,定子锁住转子的力矩。
它是步进电机最重要的参数之一,通常步进电机在低速时的力矩接近保持转矩。
由于步进电机的输出力矩随速度的增大而不断衰减,输出功率也随速度的增大而变化,所以保持转矩就成为了衡量步进电机最重要的参数之一。
比如,当人们说2N.m的步进电机,在没有特殊说明的情况下是指保持转矩为2N.m的步进电机。
什么是DETENT TORQUEDETENT TORQUE 是指步进电机没有通电的情况下,定子锁住转子的力矩。
DETENT TORQUE 在国内没有统一的翻译方式,容易使大家产生误解;由于反应式步进电机的转子不是永磁材料,所以它没有DETENT TORQUE。
步进电机精度为多少?是否累积一般步进电机的精度为步进角的3-5%,且不累积。
步进电机的外表温度允许达到多少步进电机温度过高首先会使电机的磁性材料退磁,从而导致力矩下降乃至于失步,因此电机外表允许的最高温度应取决于不同电机磁性材料的退磁点;一般来讲,磁性材料的退磁点都在摄氏130度以上,有的甚至高达摄氏200度以上,所以步进电机外表温度在摄氏80-90度完全正常。
单片机控制系统外文翻译
Microcomputer SystemsElectronic systems are used for handing information in the most general sense; this information may be telephone conversation, instrument read or a company’s accounts, but in each case the same main type of operation are involved: the processing, storage and transmission of information. in conventional electronic design these operations are combined at the function level; for example a counter, whether electronic or mechanical, stores the current and increments it by one as required.A system such as an electronic clock which employs counters has its storage and processing capabilities spread throughout the system because each counter is able to store and process numbers.Present day microprocessor based systems depart from this conventional approach by separating the three functions of processing, storage, and transmission into different section of the system. This partitioning into three main functions was devised by Von Neumann during the 1940s, and was not conceived especially for microcomputers. Almost every computer ever made has been designed with this structure, and despite the enormous range in their physical forms, they have all been of essentially the same basic design.In a microprocessor based system the processing will be performed in the microprocessor itself. The storage will be by means of memory circuits and the communication of information into and out of the system will be by means of special input/output(I/O) circuits. It would be impossible to identify a particular piece of hardware which performed the counting in a microprocessor based clock because the time would be stored in the memory and incremented at regular intervals but the microprocessor. However, the software which defined the system’s behavior woul d contain sections that performed as counters. The apparently rather abstract approach to the architecture of the microprocessor and its associated circuits allows it to be very flexible in use, since the system is definedalmost entirely software. The design process is largely one of software engineering, and the similar problems of construction and maintenance which occur in conventional engineering are encountered when producing software.The figure1.1 illustrates how these three sections within a microcomputer are connected in terms of the communication of information within the machine. The system is controlled by the microprocessor which supervises the transfer of information between itself and the memory and input/output sections. The external connections relate to the rest (that is, the non-computer part) of the engineering system.Fig.1.1 Three Sections of a Typical MicrocomputerAlthough only one storage section has been shown in the diagram, in practice two distinct types of memory RAM and ROM are used. In each case, the word ‘memory’ is rather inappropriate since a computers memory is more like a filing cabinet in concept; information is stored in a set of numbered ‘boxes’ and it is referenced by the serial number of the ‘box’ in questio n.Microcomputers use RAM (Random Access Memory) into which data can be written and from which data can be read again when needed. This data can be read back from the memory in any sequence desired, and not necessarily the same order in which it was w ritten, hence the expression ‘random’ access memory. Another type of ROM (Read Only Memory) is used to hold fixed patterns of information which cannot be affected by the microprocessor; these patterns are not lost when power is removed and are normally used to hold the program which defines the behavior of a microprocessor based system. ROMs can be read like RAMs, but unlike RAMs they cannot be used to store variable information. Some ROMs have their data patterns put in during manufacture, while others are programmable by the user by means of special equipment and are called programmable ROMs. The widely used programmable ROMs are erasable by means of special ultraviolet lamps and are referred to as EPROMs, short for Erasable Programmable Read OnlyMemories. Other new types of device can be erased electrically without the need for ultraviolet light, which are called Electrically Erasable Programmable Read Only Memories, EEPROMs.The microprocessor processes data under the control of the program, controlling the flow of information to and from memory and input/output devices. Some input/output devices are general-purpose types while others are designed for controlling special hardware such as disc drives or controlling information transmission to other computers. Most types of I/O devices are programmable to some extent, allowing different modes of operation, while some actually contain special-purpose microprocessors to permit quite complex operations to be carried out without directly involving the main microprocessor.The microprocessor , memory and input/output circuit may all be contained on the same integrated circuit provided that the application does not require too much program or data storage . This is usually the case in low-cost application such as the controllers used in microwave ovens and automatic washing machines . The use of single package allows considerable cost savings to e made when articles are manufactured in large quantities . As technology develops , more and more powerful processors and larger and larger amounts of memory are being incorporated into single chip microcomputers with resulting saving in assembly costs in the final products . For the foreseeable future , however , it will continue to be necessary to interconnect a number of integrated circuits to make a microcomputer whenever larger amounts of storage or input/output are required.Another major engineering application of microcomputers is in process control. Here the presence of the microcomputer is usually more apparent to the user because provision is normally made for programming the microcomputer for the particular application. In process control applications the benefits lf fitting the entire system on to single chip are usually outweighed by the high design cost involved, because this sort lf equipment is produced in smaller quantities. Moreover, process controllers are usually more complicated so that it is more difficult to make them as single integrated circuits. Two approaches are possible; the controller can be implemented as a general-purpose microcomputer rather like a more robust version lf a hobby computer, or as a ‘packaged’ system, signed for replacing controllers based on older technologies such as electromagnetic relays. In the former case the system would probably be programmed in conventional programming languages such as the ones to9 be introduced later, while in the other case a special-purpose language might be used, for example one which allowed the function of the controller to be described in terms of relay interconnections, In either case programs can be stored in RAM, which allows them to be altered to suit changes in application, but this makes the overall system vulnerable to loss lf power unless batteries are used to ensure continuity of supply. Alternatively programs can be stored in ROM, in which case they virtually become part of the electronic ‘hardware’ and are often referred to as firmware.More sophisticated process controllers require minicomputers for their implementation, although the use of large scale integrated circuits ‘the distinction between mini and microcomputers, Products and process controllers of various kinds represent the majority of present-day microcomputer applications, the exact figures depending on one’s interpretation of the word ‘product’. Virtually all engineering and scientific uses of microcomputers can be assigned to one or other of these categories. But in thesystem we most study Pressure and Pressure Transmitters. Pressure arises when a force is applied over an area. Provided the force is one Newton and uniformly over the area of one square meters, the pressure has been designated one Pascal. Pressure is a universal processing condition. It is also a condition of life on the planet: we live at the bottom of an atmospheric ocean that extends upward for many miles. This mass of air has weight, and this weight pressing downward causes atmospheric pressure. Water, a fundamental necessity of life, is supplied to most of us under pressure. In the typical process plant, pressure influences boiling point temperatures, condensing point temperatures, process efficiency, costs, and other important factors. The measurement and control of pressure or lack of it-vacuum-in the typical process plant is critical.单片机控制系统广义地说,微型计算机控制系统(单片机控制系统)是用于处理信息的,这种被用于处理的信息可以是电话交谈,也可以是仪器的读数或者是一个企业的帐户,但是各种情况下都涉及到相同的主要操作:信息的处理、信息的存储和信息的传递。
外文翻译-步进电机外文翻译,中英对照
中文步进电机步进电机是将电脉冲信号转变为角位移或线位移的开环控制元步进电机件。
在非超载的情况下,电机的转速、停止的位置只取决于脉冲信号的频率和脉冲数,而不受负载变化的影响,当步进驱动器接收到一个脉冲信号,它就驱动步进电机按设定的方向转动一个固定的角度,称为“步距角”,它的旋转是以固定的角度一步一步运行的。
可以通过控制脉冲个数来控制角位移量,从而达到准确定位的目的;同时可以通过控制脉冲频率来控制电机转动的速度和加速度,从而达到调速的目的。
工作原理步进电机是一种感应电机,它的工作原理是利用电子电路,将直流电变成分时供电的,多相时序控制电流,用这种电流为步进电机供电,步进电机才能正常工作,驱动器就是为步进电机分时供电的,多相时序控制器虽然步进电机已被广泛地应用,但步进电机并不能象普通的直流电机,交流电机在常规下使用。
它必须由双环形脉冲信号、功率驱动电路等组成控制系统方可使用。
因此用好步进电机却非易事,它涉及到机械、电机、电子及计算机等许多专业知识。
步进电机作为执行元件,是机电一体化的关键产品之一, 广泛应用在各种自动化控制系统中。
随着微电子和计算机技术的发展,步进电机的需求量与日俱增,在各个国民经济领域都有应用。
分类现在比较常用的步进电机包括反应式步进电机(VR)、永磁式步进电机(PM)、混合式步进电机(HB)和单相式步进电机等。
永磁式步进电机永磁式步进电机一般为两相,转矩和体积较小,步进角一般为7.5度或15度;永磁式步进电动机输出力矩大,动态性能好,但步距角大。
反应式步进电机反应式步进电机一般为三相,可实现大转矩输出,步进角一般为1.5度,但噪声和振动都很大。
反应式步进电机的转子磁路由软磁材料制成,定子上有多相励磁绕组,利用磁导的变化产生转矩。
反应式步进电动机结构简单,生产成本低,步距角小;但动态性能差。
混合式步进电机混合式步进电动机综合了反应式、永磁式步进电动机两者的优点,它的步距角小,出力大,动态性能好,是目前性能最高的步进电动机。
外文翻译----步进电机基础
资料翻译英文资料Stepper Motor Basics[TieluoLin.Jianxun Zhang.DSP-based microstep controller of stepper motor.Intelligent Control and Automation, 2004.Fifth World Congress on Volume 5, 15-19 June 2004.]A stepper motor is an electromechanical device which converts electrical pulses into discrete mechanical movements. The shaft or spindle of a stepper motor rotates in discrete step increments when electrical command pulses are applied to it in the proper sequence. The motors rotation has several direct relationships to these applied input pulses. The sequence of the applied pulses is directly related to the direction of motor shafts rotation. The speed of the motor shafts rotation is directly related to the frequency of the input pulses and the length of rotation is directly related to the number of input pulses applied.Stepper Motor Advantages and DisadvantagesAdvantages1. The rotation angle of the motor is proportional to the input pulse.2. The motor has full torque at standstill (if the windings are energized)3. Precise positioning and repeatability of movement since good stepper motors have an accuracy of 3 – 5% of a step and this error is non cumulative from one step to the next.4. Excellent response to starting/stopping/reversing.5. Very reliable since there are no contact brushes in the motor. Therefore the life of the motor is simply dependant on the life of the bearing.6. The motors response to digital input pulses provides open-loop control, making the motor simpler and less costly to control.7. It is possible to achieve very low speed synchronous rotation with a load that is directly coupled to the shaft.8. A wide range of rotational speeds can be realized as the speed is proportional to the frequency of the input pulses.Disadvantages1. Resonances can occur if not properly controlled.2. Not easy to operate at extremely high speeds.Open Loop OperationOne of the most significant advantages of a stepper motor is its ability to be accurately controlled in an open loop system. Open loop control means no feedback information about position is needed. This type of control eliminates the need for expensive sensing and feedback devices such as optical encoders. Your position is known simply by keeping track of the input step pulses.Stepper Motor TypesThere are three basic stepper motor types. They are :• Variable-reluctance• Permanent-magnet• HybridVariable-reluctance (VR)This type of stepper motor has been around for a long time. It is probably the easiest to understand from a structural point of view. Figure 1 shows a cross section of a typical V.R. stepper motor. This type of motor consists of a soft iron multi-toothed rotor and a wound stator. When the stator windings are energized with DC current the poles become magnetized. Rotation occurs when the rotor teeth are attracted to the energized stator poles.Figure 1. Cross-section of a variablereluctance(VR) motor.Permanent Magnet (PM)Often referred to as a “tin can” or “canstock” motor the permanent magnet step motor is a low cost and low resolution type motor with typical step angles of 7.5° to 15°. (48 –24steps/revolution) PM motors as the name implies have permanent magnets added to the motor structure. The rotor no longer has teeth as with the VR motor. Instead the rotor is magnetized with alternating north and south poles situated in a straight line parallel to the rotor shaft. These magnetized rotor poles provide an increased magnetic flux intensity and because of this the PM motor exhibits improved torque characteristics when compared with the VR type.Hybrid (HB)The hybrid stepper motor is more expensive than the PM stepper motor but provides better performance with respect to step resolution, torque and speed. Typical step angles for the HB stepper motor range from 3.6°to 0.9°(100 –400 steps per revolution). Thehybrid stepper motor combines the best features of both the PM and VR type stepper motors. The rotor is multi-toothed like the VR motor and contains an axially magnetized concentric magnet around its shaft. The teeth on the rotor provide an even better path which helps guide the magnetic flux to preferred locations in theairgap. This further increases the detent, holding and dynamic torque characteristics of the motor when compared with both the VR and PM types.The two most commonly used types of stepper motors are the permanent magnet and the hybrid types. If a designer is not sure which type will best fit his applications requirements he should first evaluate the PM type as it is normally several times less expensive. If not then the hybrid motor may be the right choice.There also excist some special stepper motor designs. One is the disc magnet motor. Here the rotor is designed sa a disc with rare earth magnets, See fig. 5 . This motor type has some advantages such as very low inertia and a optimized magnetic flow path with no coupling between the two stator windings. These qualities are essential in some applications.Size and PowerIn addition to being classified by their step angle stepper motors are also classified according to frame sizes which correspond to the diameter of the body of the motor. For instance a size 11 stepper motor has a body diameter of approximately 1.1 inches. Likewise a size 23 stepper motor has a body diameter of 2.3 inches (58 mm), etc. The body length may however, vary from motor to motor within the same frame size classification. As a general rule the available torque output from a motor of a particular frame size will increase with increased body length.Power levels for IC-driven stepper motors typically range from below a watt for very small motors up to 10 –20 watts for larger motors. The maximum power dissipation level or thermal limits of the motor are seldom clearly stated in the motor manufacturersdata. To determine this we must apply the relationship P=V×I For example, a size 23 step motor may be rated at 6V and 1A per phase. Therefore, with two phases energizedthe motor has a rated power dissipation of 12 watts. It is normal practice to rate a stepper motor at the power dissipation level where the motor case rises 65°C above the ambient in still air. Therefore, if the motor can be mounted to a heatsink it is oftenpossible to increase the allowable power dissipation level. This is important as the motor is designed to be and should be used at its maximum power dissipation ,to be efficient froma size/output power/cost point of view.When to Use a StepperMotorA stepper motor can be a good choice henever controlled movement is equired. They can be used to advantage in applications where you need to control rotation angle, speed, position and synchronism. Because of the inherent advantages listed previously, stepper motors have found their place in many different applications. Some of these include printers, plotters, highend office equipment, hard disk drives, medical equipment, fax machines, automotive and many more.The Rotating Magnetic FieldWhen a phase winding of a stepper motor is energized with current a magnetic flux is developed in the stator. The d When a phase winding of a stepper motor is energized with current a magnetic flux is developed irection of this flux is determined by the “Right Ha ndRule” which states: “If the coil is grasped in the right hand with the fingers pointing in the direction of the current in the winding (the thumb is extended at a 90°angleto the fingers), then the thumb will point in the direction of the magnetic field.”Figure 2 shows the magnetic flux path developed when phase B is energized with winding current in the direction shown. The rotor then aligns itself so that the flux opposition is minimized. In this case the motor would rotate clockwise so that its south pole aligns with the north pole of the stator B at position 2 and its north pole aligns with the south pole of stator B at position 6. To get the motor to rotate we can now see that we must provide a sequence of energizing the stator windings in such a fashion that provides a rotating magnetic flux field which the rotor follows due to magnetic attraction.Figure 2 Magnetic flux path through atwo-pole stepper motor with a lag betweenthe rotor and stator.Torque GenerationThe torque produced by a stepper motor depends on several factors.• The step rate• The drive current in the windings• The drive design or typeIn a stepper motor a torque is developed when the magnetic fluxes of the rotor and stator are displaced from each other. The stator is made up of a high permeability magnetic material. The presence of this high permeability material causes the magnetic flux to be confined for the most part to the paths defined by the stator structure in the same fashion that currents are confined to the conductors of an electronic circuit. This serves to concentrate the flux at the stator poles. Thetorque output produced by the motor is proportional to the intensity of the magnetic flux generated when the winding is energized.The basic relationship which defines the intensity of the magneticflux is defined by:H = (N ×i) ÷ l where:N = The number of winding turnsi = currentH = Magnetic field intensityl = Magnetic flux path lengthThis relationship shows that the magnetic flux intensity and consequently the torque is proportional to the number of winding turns and the current and inversely proportional to the length of the magnetic flux path. From this basic relationship one can see that the same frame size stepper motor could have very different torque output capabilities simply by changing the winding parameters. More detailed information on how the winding parameters affect the output capability of the motor can be found in the application note entitled “DriveCircuit Basics”.Stepping ModesThe following are the most common drive modes.• Wave Drive (1 phase on)• Full Step Drive (2 phases on)• Half Step Drive (1 & 2 phases on)• Micro stepping (Continuously varying motor currents)For the following discussions please refer to the figure 3.Figure 3 Unipolar and bipolar wound stepper motors.In Wave Drive only one winding is energized at any given time. The stator is energized according to the sequence A B A B and the rotor steps from position8 2 4 6. For unipolar and bipolar wo und motors with the same winding parameters this excitation mode would result in the same mechanical position. The disadvantage of this drive mode is that in the unipolar wound motor you are only using 25% and in the bipolar motor only 50% of the total motor winding at any given time. This means that you are not getting the maximum torque output from the motor.In Full Step Drive you are energizingtwo phases at any given time.The stator is energized according to the sequence AB A B A B AB and the rotor steps from position 1 3 5 7 . Full step mode results in the same angular movement as 1 phase on drive but the mechanical position is offset by one half of a fullstep. The torque output of the unipolar wound motor is lower than the bipolar motor (for motors with the same winding parameters) since the unipolar motor uses only 50% of the available winding while the bipolar motor uses the entire winding.Half Step Drive combines both wave and full step (1&2 phases on) drive modes. Every second step onlyone phase is energized and during the other steps one phase on each stator. The stator is energized according to the sequence AB B A B A A B B A B A and the rotor steps from position 1 2 3 4 5 6 7 8. This results in angular movements that are half of those in 1- or 2-phases-on drive modes. Half stepping can reduce a phenomena referred to as resonance which can be experiencedin 1- or 2-phases-on drive modes.The excitation sequences for the above drive modes are summarized in Table 1. Table 1. Excitation sequences for different drive modesIn Microstepping Drive the currents in the windings are continuously varying to be able to break up one full step into many smaller discrete steps. More information on microstepping can be found in the microstepping chapter.Single Step Response and ResonancesThe single-step response characteristics of a stepper motor is shown in figure 4.Figure 4 Single step response vs. time.When one step pulse is applied to a stepper motor the rotor behaves in a manner as defined by the above curve.The step time t is the time it takes the motor shaft to rotate one step angle once the first step pulse is applied. This step time is highly dependent on the ratio of torque to inertia (load) as well as the type of driver used.Since the torque is a function of the displacement it follows that the acceleration will also be. Therefore, when moving in large step increments a high torque is developed and consequently a high acceleration. This can cause overshots and ringing as shown. The settling time T is the time it takes these oscillations or ringing to cease. In certain applications this phenomena can be undesirable. It is possible to reduce or eliminate this behaviour by microstepping the stepper motor. For more information on micro stepping please consult the microstepping note.Stepper motors can often exhibit a phenomena refered to as resonance at certain step rates. This can be seen as a sudden loss or drop in torque at certain speeds which can result in missed steps or loss of synchronism. It occurs when the input step pulserate coincides with the natural oscillation frequency of the rotor. Often there is a resonance area around the 100 – 200 pps region and also one in the high step pulse rate region. The resonance phenomena of a stepper motor comes from its basic construction and therefore it is not possible to eliminate it completely. It is also dependent upon the load conditions. It can be reduced by driving the motor in half or micro stepping modes.中文译文步进电机基础[林铁国,张建勋.基于DSP的微控制器的步进电机控制和自动化, 2004 。
步进电机概述论文中英文资料对照外文翻译文献综述
步进电机概述中英文资料对照外文翻译文献综述外文文献:Knowledge of the stepper motorWhat is a stepper motor:Stepper motor is a kind of electrical pulses into angular displacement of the implementing agency. Popular little lesson: When the driver receives a step pulse signal, it will drive a stepper motor to set the direction of rotation at a fixed angle (and the step angle). You can control the number of pulses to control the angular displacement, so as to achieve accurate positioning purposes; the same time you can control the pulse frequency to control the motor rotation speed and acceleration, to achieve speed control purposes.What kinds of stepper motor sub-:In three stepper motors: permanent magnet (PM), reactive (VR) and hybrid (HB) permanent magnet stepper usually two-phase, torque, and smaller, step angle of 7.5 degrees or the general 15 degrees; reaction step is generally three-phase, can achieve high torque output, step angle of 1.5 degrees is generally, but the noise and vibration are large. 80 countries in Europe and America have been eliminated; hybrid stepper is a mix of permanent magnet and reactive advantages. It consists of two phases and the five-phase: two-phase step angle of 1.8 degrees while the general five-phase step angle of 0.72 degrees generally. The most widely used Stepper Motor.What is to keep the torque (HOLDING TORQUE)How much precision stepper motor? Whether the cumulative:The general accuracy of the stepper motor step angle of 3-5%, and not cumulative.Stepper motor to allow the minimum amount of surface temperatureStepper motor to allow the minimum amount of surface temperature:Stepper motor causes the motor temperature is too high the first magnetic demagnetization, resulting in loss of torque down even further, so the motor surface temperature should be themaximum allowed depending on the motor demagnetization of magnetic material points; Generally speaking, the magnetic demagnetization points are above 130 degrees Celsius, and some even as high as 200 degrees Celsius, so the stepper motor surface temperature of 80-90 degrees Celsius is normal.How to determine the stepper motor driver DC power supply:A. Determination of the voltageHybrid stepping motor driver power supply voltage is generally a wide range (such as the IM483 supply voltage of 12 ~ 48VDC), the supply voltage is usually based on the work of the motor speed and response to the request to choose. If the motor operating speed higher or faster response to the request, then the voltage value is high, but note that the ripple voltage can not exceed the maximum input voltage of the drive, or it may damage the drive.B. Determination of CurrentPower supply current is generally based on the output phase current drive I to determine. If a linear power supply, power supply current is generally preferable 1.1 to 1.3 times the I; if we adopt the switching power supply, power supply current is generally preferable to I, 1.5 to 2.0 times.The main characteristics of stepping motor:A stepper motor drive can be added operate pulse drive signal must be no pulse when the stepper motor at rest, such asIf adding the appropriate pulse signal, it will to a certain angle (called the step angle) rotation. Rotation speed and pulse frequency is proportional to.2 Dragon step angle stepper motor version is 7.5 degrees, 360 degrees around, takes 48 pulses to complete.3 stepper motor has instant start and rapid cessation of superior characteristics.Change the pulse of the order of 4, you can easily change the direction of rotation. Therefore, the current printers, plotters, robotics, and so devices are the core of the stepper motor as the driving force.Stepper motor control exampleWe use four-phase unipolar stepper motor as an example. The structure shown in Figure 1: Four four-phase winding leads (as opposed to phase A1 A2 B1 phase phase B2) and twopublic lines (to the power of positive). The windings of one phase to the power of the ground. So that the windings will be inspired. We use four-phase eight-beat control, ie, 1 phase 2 phase alternating turn, would enhance resolution. 0.9 ° per step can be transferred to control the motor excitation is transferred in order as follows:If the requirements of motor reversal, the transmission excitation signal can be reversed. 2 control schemeControl system block diagram is as followsThe program uses AT89S51 as the main control device. It is compatible with the AT89C51, but also increased the SPI interface and the watchdog module, which not only makes the debugging process becomes easy and also more stable. The microcontroller in the program mainly for field signal acquisition and operation of the stepper motor to calculate the direction and speed information. Then sent to the CPLD.CPLD with EPM7128SLC84-15, EPM7128 programmable logic device of large-scale, for the ALTERA company's MAX7000 family. High impedance, electrically erasable and other characteristics, can be used for the 2500 unit, the working voltage of +5 V. CPLD receives information sent from the microcontroller after converted to the corresponding control signal output to the stepper motor drive. Put the control signal drives the motor windings after the input, to achieve effective control of the motor. 2.1 The hardware structure of the motor drive Motor drive using the following circuit:R1-R8 in which the resistance value of 320Ω. R9-R12 resistance value 2.2KΩ. Q1-Q4 as Darlington D401A, Q5-Q8 for the S8550. J1, J2 and the stepper motor connected to the six-lead。
