Problem solving

Stepper motor driver FAQ
Release Date : 2019-03-08 09:23:11

1. What is a stepper motor, and what is a stepper motor driver?

The stepping motor is a special motor used for control. Its rotation is operated step by step at a fixed angle (called "step angle"). It is characterized by no accumulation error (accuracy is 100%), so it is widely used. Used in a variety of open loop control. The operation of the stepping motor is driven by an electronic device. This device is a stepping motor driver. It converts the pulse signal from the control system into the angular displacement of the stepping motor, or: every pulse signal sent by the control system. The stepper motor is rotated one step angle by the drive. Therefore, the speed of the stepper motor is proportional to the frequency of the pulse signal. Therefore, controlling the frequency of the stepping pulse signal can accurately adjust the speed of the motor; controlling the number of stepping pulses can accurately position the motor.

2. What is the breakdown of the drive?

To understand the "segmentation", we must first understand the concept of "step angle": it means the angle at which the motor rotates every time the control system sends a step pulse signal. The motor is given a step angle value when it leaves the factory. For example, the value given by the 86BYG250A motor is 0.9°/1.8 (° means 0.9° for half-step operation and 1.8° for full-step operation). This step angle It can be called 'motor inherent step angle', it is not necessarily the true step angle of the actual working of the motor, the true step angle is related to the driver, the type of the drive used by the inherent step angle of the motor and the working state of the motor True step angle 0.9°/1.8° drive works in half step state 0.9°0.9°/1.8° subdivision drive works in 5 subdivision state 0.36°0.9°/1.8° subdivision drive works in 10 subdivision state 0.18°0.9 °/1.8° subdivision driver works in 20 subdivision state 0.09°0.9°/1.8° subdivision driver works in 40 subdivision state 0.045° As can be seen from the above table: stepper motor drives through subdivision drive, its step The distance angle becomes smaller. If the driver works in the 10 subdivision state, the step angle is only one tenth of the 'inherent step angle of the motor', that is: "When the driver works in the whole step without subdivision In the state, the control system sends a step pulse every time, the motor rotates by 1.8°; In the 10 subdivision state, the motor only rotates 0.18°", which is the basic concept of subdivision. The subdivision function is completely generated by the drive* precisely controlling the phase current of the motor, independent of the motor.

3. What are the advantages of driver segmentation, why do I recommend using the segmentation feature?

The main advantage of the driver subdivision is that the low frequency oscillation of the motor is completely eliminated. Low-frequency oscillation is an inherent characteristic of stepper motors (especially reactive motors), and subdivision is the only way to eliminate it. If your stepper motor sometimes needs to work in the resonance zone (such as arcing), select the subdivision driver. Is the only choice. The output torque of the motor is increased. Especially for three-phase reactive motors, the torque is increased by about 30-40% compared to the case without subdivision. Improve the resolution of the motor. Since the step angle is reduced and the uniformity of the step is improved, it is self-evident that 'increasing the resolution of the motor'. These advantages, especially in terms of performance, are not a quantitative change, but a qualitative leap. According to our records, users who used the non-segmented drive were mostly selected as subdivision drivers after comparison. So we recommend that you choose the segmentation drive.

4. What is a hybrid stepping motor and what is a reactive stepping motor? What is the difference between the two?

Different in structure and material, the reactive motor does not have a permanent magnetic material inside the hybrid motor, so the reactive motor has no self-resistance, and the hybrid motor has self-resistance (that is, there is a certain degree when the motor is not powered). Self-locking force) has different running performance. The hybrid motor runs relatively smoothly, the output torque is relatively large, and the running sound is small. There are differences in price between the two motors, and reactive motors are relatively cheaper than hybrid motors.

5. What is the phase number of the stepper motor, should I choose a phase motor with several phases?

The number of phases of the stepper motor refers to the number of coil groups inside the motor. Currently, two-phase, three-phase, four-phase, and five-phase stepping motors are commonly used. The number of phases of the motor is different, and the step angle is also different. Generally, the step angle of the two-phase motor is 0.9°/1.8°, the three-phase is 0.75°/1.5°, and the five-phase is 0.36°/0.72°. When there is no subdivision driver, the user mainly * selects stepper motors with different phase numbers to meet the requirements of their own step angle. If a subdivision driver is used, the 'phase number' will become meaningless, and the user can change the step angle by simply changing the number of subdivisions on the drive.

6. I am preparing to choose a five-phase hybrid stepping motor. Any suggestions?

The five-phase hybrid stepping motor is in a phase-out state, so we recommend: If you must use a five-phase step angle (0.36°), please use a two-phase hybrid stepping motor and a matching subdivision driver. 5 The step angle in the subdivided state is also 0.36°, and the stepped angle after subdivision is more uniform than the inherent step angle of the five phases, the positioning accuracy is higher, the operation is more stable, and the output is larger.