Stepper motor problem, stepper driver subdivision how to understand 5

Subdivision is to further refine the step angle on the motor name plate to achieve the purpose of improving positioning accuracy. So your understanding is right. But after the subdivision multiplier exceeds a certain multiple, the drive is made.

The computing power and operation speed and control accuracy requirements are increased, so it will be limited by a similar 10 times, and the actual control accuracy is not improved after more than 10 times subdivision.

That information is old, and I've done it all down to 128, and there's nothing wrong with it.

The ideal situation of stepper motor drive is to provide a sine wave (power) with a fixed phase difference, and the two-phase motor is 90 degrees apart, and the positive 90 degree difference is positive to negative 90 degrees and reversed. The sinusoidal frequency is the rotational speed that takes one step in a cycle.

If several points are inserted in a cycle so that the current is close to sinusoidal, it is subdivided. 10 subdivisions insert 10 points, but a cycle is still one step. Each microstep is.

The subdivision actually controls the current precisely, does not affect the moment and helps to increase the torque, which is the rotational speed.

The driver is controlled by the switching circuit, that is, the SPWM is applied, and the large subdivision will multiply the number of switches, and there will be no problem with low speed, and high speed will be troublesome. In short, in the end, there is the question of the switching frequency that can be realized.

Stepper motor subdivision learning.

Subdivided in stepper motor applications, the essence is the setting of the electronic gear ratio, but the stepper motor is in the open-loop control mode, and the position of the final stop of the rotor is affected by the magnitude of the load torque.

It is a drive control technology developed in the mid-70s that can significantly improve the overall performance of stepper motors. It is by controlling the current in the windings of each phase, so that they rise or fall according to a certain law, that is, a plurality of stable intermediate current states are formed between the zero current and the maximum current, and there will also be a plurality of stable intermediate states in the direction of the corresponding resultant magnetic field vector, and rotate according to the subdivision step.

The amplitude of the resultant magnetic field vector determines the magnitude of the rotational moment of the stepper motor, and the direction of the resultant magnetic field vector determines the magnitude of the step angle after subdivision. The subdivision drive technology further improves the angle accuracy and running smoothness of the stepper motor.

Grow your app. The stepper motor subdivision drive technology was first proposed by American scholars at the annual meeting of incremental motion control systems and devices in the United States. Initially, the control of the phase current of the stepper motor was realized by hardware, and the phase current of each phase winding was controlled by n transistors forming n parallel circuits, and the phase current was controlled by the combination of transistor conduction numbers.

With the development of computer technology, especially the emergence of single-chip microcomputer, a new situation has been created in the subdivision drive technology of stepper motor. The subdivision drive circuit of the stepper motor controlled by single-chip microcomputer not only reduces the volume of the control system and simplifies the circuit, but also further improves the subdivision accuracy and the intelligence of the control system, so that the subdivision drive technology has been promoted.

1. To understand the subdivision, we must first understand the concept of step angle: it represents the angle of rotation of the control system for each step pulse signal. The value of a step angle is given when the motor leaves the factory, such as the value given by the FY86EL402A motor, this step angle can be called the 'inherent step angle of the motor', which is not necessarily the real step angle when the motor actually works.

2. The number of subdivisions refers to the fact that the real step angle of the motor is a fraction of the inherent step angle (whole step). As can be seen from the above table: when the stepper motor driver works in the state of 10 subdivisions, its step angle is only one-tenth of the 'inherent step angle of the motor', which is the basic concept of subdivision.

3. A more accurate description of the subdivision characteristics of the driver is the number of running beats, which refers to the number of pulses required for each rotation of the gear pitch when the stepper motor is running. Please note that if the number of running beats is set to 30, the number will be broken down according to the correspondence in the table above, not an integer. The subdivision function is generated entirely by the stepper driver by precisely controlling the phase current of the motor, independent of the motor.

The main function of stepper motor driver subdivision is to improve the accuracy of stepper motors.

Usually there are subdivisions 2, 4, 8, 16, 32, 62, 128, 256, 512....

In foreign countries, for the stepper system, the two-phase hybrid stepper motor and the corresponding subdivision driver are mainly used. But in China, the majority of users are not particularly aware of the "subdivision", some just think that the subdivision is to improve the accuracy, in fact, the subdivision is mainly to improve the running performance of the motor, the description is as follows: the subdivision control of the stepper motor is realized by the driver to accurately control the phase current of the stepper motor, taking the two-phase motor as an example, if the rated phase current of the motor is 3A, if the conventional driver (such as the commonly used constant current chopper mode) is used to drive the motor, the motor runs every step, and its windings are in The current will change from 0 to 3A or from 3A to 0, and the huge change in phase current will inevitably cause vibration and noise in the operation of the motor.

If the subdivision driver is used, the motor is driven in the state of 10 subdivisions, and the motor runs every microstep, and the current changes in the winding only 3A, and the current changes in a sinusoidal curve law, so that the vibration and noise of the motor are greatly improved, therefore, the advantage in performance is the real advantage of the subdivision. Because the subdivision driver needs to accurately control the phase current of the motor, the technical and process requirements for the driver must be quite high, and the cost will be high. Note that there are some drives in China that use "smoothing" to replace subdivisions, and some are also called subdivisions, but this is not a real subdivision, and I hope that the majority of users must distinguish the essence of the two is different:

1 "Smoothing" does not accurately control the phase current of the motor, but only slows down the rate of change of the current, so "smoothing" does not produce microsteps, while the subdivided microsteps can be used for precise positioning.

2. After the phase current of the motor is smoothed, it will cause the torque of the motor to decrease, while the subdivision control will not cause the decrease of the motor torque, on the contrary, the torque will increase.

A few subdivisions are equivalent to a "control accuracy" increased several times (the angle of rotation of the motor by each pulse is smaller, the error caused by losing a few pulses during the execution process is smaller, and the control accuracy is higher), if you want to keep the speed constant, the frequency should be increased by the corresponding multiple.

For example, it turns out that the motor uses 200 pulses for one revolution, and you do 2 subdivisions, then the motor will take 400 (200*2) pulses for one revolution.

The general subdivision has 2 4 8 16 32 and possibly 64 128.

Generally, the subdivision is added to improve the control accuracy, but the subdivision is the increase of the electrical pulse state to improve the accuracy, in fact, there are errors in the subdivision, but there are also errors in the accuracy of mechanical manufacturing, which can not be completely avoided.

The stepper driver has a number of subdivisions, and the number of subdivisions is to subdivide the step angle of the stepper motor, for example, the step angle of the stepper motor is, when there is no number of subdivisions, that is, when the number of subdivisions is 1, the pulse foot of the stepper driver, every time a pulse is received, the stepper motor rotates, if the number of subdivisions is 2, the pulse foot of the stepper driver, every time a pulse is received, the stepper motor rotates, so that some control can be more accurate.

The subdivision of the stepper driver has two functions, one is similar to an electronic gear, which can adjust the control pulse equivalent; The second is to improve the running performance of the stepper motor, especially to reduce the vibration and noise of the stepper. For example, the EZM series of stepper drivers from Innex introduces improved interpolation control technology, which allows users to achieve high interpolation performance even in full half-step operation, but with reduced control pulse requirements.

Yes. The stepper driver transmits the subdivision pulse to the stepper motor, in fact, the step angle becomes smaller in this process, for example, the stepper driver is in the subdivision state of 20, and the real step angle is only one-twentieth.

It can solve the vibration of the stepper motor at low speed: this problem can be solved well by subdividing the stepper driver, so that the vibration of the stepper motor at low speed can also be well solved in the resonance area.

The number of subdivisions of the stepper motor driver can be used to adjust the control pulse equivalent, and at the same time, it can improve the smoothness of the stepper motor operation and reduce the noise of the motor operation. The larger the subdivision setting, the higher the control pulse frequency required for the motor to run at the same speed.

The so-called subdivision number of the stepper driver actually refers to the number of steps (pulse number) to complete by subdividing the inherent original step angle of the motor into multiple steps, for example, the inherent step angle is a pulse corresponding to 10 °, when the number of subdivisions is 2, then the motor needs to take 2 steps (two pulses) to rotate 10 °, then the real step angle at this time is 10 2 = 5 °, that is, a pulse can only make the motor rotate 5 °, so the subdivision can improve the accuracy (resolution) of the stepper motor, At the same time, the speed of the motor can be changed (but it should be noted that if you do not change the number of input pulses sent by the host computer, the positioning of the motor will be inaccurate, and the position will deviate).

The stepper motor driver subdivision is simply to divide the step angle of the stepper motor into immediate steps, and the user can improve the running stability of the motor through subdivision, reduce vibration and noise; On the other hand, the user can subdivide and adjust the pulse equivalent.

The function of stepper motor driver subdivision is to improve the accuracy of stepper motors.

The stepper motor driver is an actuator that converts the electrical pulse into angular displacement, when the stepper driver receives a pulse signal, it drives the stepper motor to rotate a fixed angle (called "step angle") in the set direction, and its rotation belt is running step by step at a fixed angle.

The angular displacement can be controlled by controlling the coarse number of pulses, so as to achieve the purpose of accurate positioning; At the same time, the speed and acceleration of the motor can be controlled by controlling the pulse frequency, so as to achieve the purpose of speed regulation and positioning.