Principle and classification of stepper motor drivers

A stepper motor driver is an actuator that converts electrical impulses into angular displacement. When the stepper driver receives a pulse signal, it drives the stepper motor to roll a fixed viewpoint (called the "step angle") in a set direction, and its rotation is to move step by step with a fixed viewpoint. The angular displacement can be manipulated by manipulating the number of pulses, and then the intention of accurate positioning can be achieved; Together, the speed and acceleration of the motor rolling can be controlled by manipulating the pulse frequency, and then the intention of speed regulation and positioning can be achieved.

Principle and classification of stepper motor drivers

The principle of the stepper motor driver is powered by a unipolar DC power supply. As long as the windings of each phase of the stepper motor are energized according to the appropriate timing, the stepper motor can be stepped and rolled.

There are three fundamental driving forms of stepper motor drivers: whole step, half step, and subdivision. The main difference is the accuracy with which the motor coil current is manipulated (i.e., the excitation method). Generally, stepper motors have the characteristics of low-frequency vibration, and the balance of low-speed operation of the motor can be improved through subdivision and coordination.

Whole-step drive

In the whole step operation, the same kind of stepper motor can be equipped with both a whole/half-step driver and a subdivision driver, but the operation function is different. The stepper motor driver cycles the two coils of the two-phase stepper motor according to the pulse/direction command (the coil is charged to set the current), and each pulse of this drive method will cause the motor to move by one fundamental step angle, i.e. 1.80 degrees (a total of 200 step angles are specified for one turn of a two-phase motor).

Half-step drive

In the single-phase excitation, the motor shaft stops to the whole step position, and after the driver receives the down-pulse, if the other phase is excited and the original successive is in the excitation state, the motor shaft will move half a step angle and stop at the center of the adjacent two whole step positions. The two-phase coil is thus cyclically single-phase, and then the dual-phase excitation stepper motor rolls in a half-step method of 0.90 degrees per pulse.

Segment-driven

The subdivision drive form has the advantages of low vibration at low speed and high positioning accuracy. Subdivision drives are widely used in stepper applications where low-speed operation is sometimes required (i.e., the motor shaft sometimes operates at 60 rpm or F) or where positioning accuracy is less than 0.90 degrees. The basic principle is to separate the two coils of the motor according to the sine and cosine steps for fine current manipulation, and then make the distance of a step angle divided into thousands of subdivision steps. For example, the drive method of 16 subdivisions can make the stepper motor with 200 gauge steps per revolution achieve a running accuracy of 200 * 16 = 3200 steps per revolution (i.e. 0.1125*).

Principle and classification of stepper motor drivers

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