The common problems of stepper motor driver

What is the phase of the stepper motor driver? How do users choose from the phase number of it?

The phase number of the stepper motor driver refers to the class number of the coil in the motor, and now the common are 2, 3, 4, and 5 phase stepper motor driver. The step angle of the motor varies with the phase number. The stepping angle of the 2 phase stepper motor driver is 1.8°, the 3 phase is 1.5°, and the 5 phase is 0.72°. Without subdividing the driver, users mainly rely on the phase number to satisfy the requirement for the stepping angle. If using the subdividing driver, there is no meaning for the phase number, and users can change the step angle by altering the subdivided number of drivers.

What are the special requirements for the control system when using subdivision drivers?

The subdivision of the driver will generate a qualitative leap for the operating performance of the motor. But the improvement is produced by the drive itself and is not relative to the motor control system. The only notice for users is the change of the motor step angle, which may affect the stepper signal frequency sent from the stepper motor controller for the step angle to become smaller after subdividing the motor, and the required stepper signal frequency is correspondingly improved. Take 1.8° stepper motor as an example: the stepper angle of the driver in the half-step is 0.9°, and in the 10 subdivided is 0.18°, and under the condition of the same motor rotating speed, the frequency of the stepper signal sent by the control system in the 10 subdivided state is five times that of the half-step operation.

How much is the precision of the stepper motor? Can it be accumulated?

The general stepping motor precision is 3~5% of the stepping Angle. The single step of the motor can not affect the precision of the next step. Therefore, the stepper motor precision can not be accumulated.

What surface temperature is allowed for the stepper motor?

First, the high surface temperature of the stepper motor will cause the degaussing of the motor magnetic materials and make the torque decline or lose. Therefore, the highest surface temperature of the stepper motor relies on the demagnetization point of different magnetic materials. Generally speaking, the demagnetization point of magnetic materials is more than 130℃. Accordingly, the normal surface temperature of the stepper motor is 80-90℃.

Why the torque of the stepper motor descend with the increase of the rotation speed?

When the cnc stepper motor rotates, the inductance of each phase winding of the motor will form a reverse electromotive force. The higher the frequency, the bigger the reverse electromotive force. Under its action, the motor phase current decreases with the increase of frequency (or speed), resulting in a decrease in torque.

Does the fine fraction of the subdivision drive represent precision?

The subdivision technology of the stepper motor is virtually an electronic damping technology, and its main purpose is to decline or remove the low-frequency vibration of the stepper motor. The improvement of motor precision is only an attached function of the subdivision technology. Such as, for the two phase hybrid stepper motor with a 1.8° stepping Angle, if the fine fraction of the subdivision stepper driver is set 4, the operation resolution ratio of the motor is 0.45° per pulse, and whether the precision can reach or approach 0.45° depends on the subdivision current control and other factors. There may be a great distinction in subdivision stepper motor driver precision between different manufacturers, and the bigger the fine fraction, the harder the control.

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