Speed Control On Stepping Motor (Three Phases And Six Times) With Single-Chip Microcomputer

The stepping motor is a precision electromechanical incremental actuator. It widely uses the digital approach for control of industrial machines. According to torque vs. speed characteristic of stepping motor, the higher startup speed is, the smaller startup torque is and then the worse the capability of driving load is. When the startup speed is higher, stepping motor will lose steps. While stopping, it will also lose steps because of inertia. So, it needs to take speed control measures on control of stepping motor. Mathematic model of the system is educed by dynamics equation and torque vs. speed characteristic of stepping motor. It adopts speed control arithmetic of exponential rule and deals with process of acceleration and deceleration via discrete method. It uses Timer to control the pulse interval at the output. It adopts method of combining checking table with computation and achieves control of acceleration and deceleration. Single-chip microcomputer that is the core of system controls stepping motor. The system is programmed by C51 language. It consists of eleven modules that each of them will achieve its corresponding function. Software and hardware is debuged by the emulational system. The test system is designed to test the rotate speed and steps of stepping motor. Finally, according to the direction of LED display, running steps and speed are input by keyboard. The system's run is controlled by functional keys. Stepping motor will run to the given steps if the "start" key is pressed. Meanwhile, stepping motor will stop if the "stop" key is pressed during its running. The research shows: the method of acceleration and deceleration via exponential rule will greatly improve the highest running frequency of stepping motor and shorten the acceleration and deceleration time.