Stepper Drive Micro-step Selection

- Jul 20, 2018-

Stepper drive micro-step selection

At this stage, the stepper motor drivers on the market are all micro-step drivers. The more categories and proportions of subdivisions, the more precise the angle of rotation of the stepper motor. But micro-step stepper motor drive  have any benefit without harm? To understand the “subdivision” of a stepper motor driver, first understand the concept of “step angle” of the stepper motor: it means that the control system sends a step pulse every time.

Signal, the angle at which the motor rotates. The motor is given a step angle value when it leaves the factory, for example, the value given by the motor is 7.5°/15° (indicating 7.5° for half-step operation and 15° for full-step operation).

This step angle can be called "the inherent step angle of the motor", it is not necessarily the true step angle of the actual working of the motor, and the true step angle is related to the driver.

When the stepping motor is driven by the subdivision driver, the step angle becomes smaller. For example, when 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,

Say: When the driver works in the whole step state without subdivision, the control system sends a step pulse every time, the motor rotates 7.5°; while the subdivision driver works in the 10 subdivision state, the motor only rotates.

1.5°, this is the basic concept of subdivision. The subdivision function is completely caused by the drive's precise control of the phase current of the motor, independent of the motor.

Advantages of  micro-step stepper motor controller

The main advantages of driver subdivision are:

1.Eliminates the low frequency oscillation of the motor: low frequency oscillation is an inherent characteristic of a stepper motor (especially a reactive motor), and subdivision is the only way to eliminate it.If the stepper motor is sometimes to work in the resonant region (such as taking an arc), selecting the subdivision driver is the only option.

2.The output torque of the stepping motor is increased: especially for three-phase reactive stepping motors, the torque is increased by about 30-40% than without subdivision.

3.Improve the resolution of the motor: Since the step angle is reduced and the step uniformity is improved, it is self-evident that "improving the resolution of the motor".

Shortcomings of stepper motor driver subdivision

Since the subdivided data is continuously written to the ADC, the more subdivision, the larger the amount of data, and the CPU resources, so it is generally only used as a single module.

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