Stepping motor has the characteristics of fast starting and stopping speed, accurate stepping and positioning, so it is often used as the control element of industrial process control and instruments. At present, the typical control method is to control the stepping motor with the pulse sequence generated by single chip microcomputer. However, the adoption of single-chip microcomputer control not only requires the design of complex control programs and I /O interface circuits, but also has poor adaptability and low reliability to the harsh environment of industrial sites. The stepper motor based on PLC control has the advantages of simple design, convenient implementation, high positioning accuracy and flexible parameter setting. Used in industrial process control, with high reliability and convenient monitoring.

Main characteristics of stepping motor

(1) step angle and static step error: the step angle of stepping motor is an important parameter to determine the pulse equivalent of open-loop servo system. The step angle of reactive stepping motor in CNC machine tools is generally 0.5 ~ 0.3. Generally speaking, the smaller the step angle, the higher the machining accuracy. Static step error refers to the difference between theoretical step angle and actual step angle, which is expressed in minutes and is generally 65430. The stepping error is mainly caused by the manufacturing error of pitch angle of stepping motor, uneven air gap between stator and rotor, and uneven electromagnetic torque of each phase. Stepping error directly affects the machining accuracy and dynamic characteristics of stepping motor.

(2) Dynamic frequency fd: When there is no load, the stepping motor suddenly starts from the static state, and the maximum frequency allowed for normal operation without losing step is called starting frequency or jumping frequency, which is expressed by fd. If the starting frequency is greater than the jumping frequency, the stepping motor cannot be started normally. Fd is related to the load inertia and generally decreases with the increase of the load inertia. When starting with no load, the change frequency of the energized state of the stator winding of the stepping motor cannot be higher than the jump frequency.

(3) The highest working frequency fmax for continuous operation is the acceptable limit frequency fmax for stepping motor to keep running without losing step, which is called the highest working frequency. It is a parameter that determines the highest change frequency of stator winding electrification state, and it determines the highest speed of stepping motor. Its value is greater than fq and varies with the nature and size of the load and the driving power supply.

(4) Acceleration and deceleration characteristics: The acceleration and deceleration characteristics of stepping motor describe that the stator winding is conductive during the acceleration and deceleration of stepping motor from static to working frequency and from working frequency to static.

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