Fully Digital Three-phase Hybrid Step Motor Drive System

Step motor is one kind of the most widely used motors in the field of industrial control. It has the advantage of low cost and simple drive system. With the developments of power converters technology and high performance microprocessors, motor drive is moving towards fully digital direction. Based on an overall review of related papers published at home and abroad, this dissertation makes deep research on the fully digital control of three-phase hybrid step motor. A fully digital three-phase hybrid step motor drive system based on Digital Signal Processor (DSP) and Intelligent Power Module(IPM) is designed. This drive system has the advantages of simple structure, low cost, and excellent performance. Firstly, this dissertation analyzes the running principle of the three-phase hybrid step motor, and establishes a ideal model by ignoring some non-linear factor. An open-loop control scheme is selected. Then design of digital PI regulators is introduced.Pulse Width Modulation (PWM) technique is one of the most important contents in the digital current control. Two PWM algorithms–Asymmetric Regular Sampling PWM and Space Vector PWM, is described. in detail, and then a fast algorithm of Space Vector PWM is got by combining the advantages of the two algorithm. Four modes of overmodulation for Space Vector PWM are presented .in detail and then their advantages and shortcomings are analyzed.Then the dissertation introduces the design of hardware and software for the system. The hardware structure and program block are given.Finally, the simulation model and the experiment equipment are introduced. The results of simulation and experimentation approve that the control strategy presented in this dissertation is quite effective. The experiment result also shows that this drive system is advanced.