Research Of Digital Low-Voltage DC Servo Control System Based On DSP

Permanet magnet brushless DC motor (BLDCM) has been widely used in the industrial and military fields. The major advantages lie in efficiency, speed control, simple structure and good reliability. Digital controller is pivotal to servo system for high precision, high response and other good performance. The digital servo control system based on DSP is still one of the most popular researches.In this paper, to meet the demands of low voltage, high power and reliability, the mathematical and simulation model are built, and the control algorithm is optimized based on MAXON BLDCM. A digital low voltage servo control system of triple closed loops with current, speed and position is achieved and verified through experiments of system prototype.Firstly, the basic structure and working mechanism of BLDCM are analysed and the frame structure of triple closed loops digital servo control system is presented. By comparing the different PWM modes, a PWM mode adapt to the control system is chosen.Secondly, the simulation model of BLDCM triple closed loop control system is built using Matlab/Simulink. A self-adaptive fuzzy PID controller applied to position control is designed, which can improve static and dynamic performance of the system.Thirdly, the prototype of triple closed loop servo control system based on DSP is designed. Hardware system includes three phase inverter, current and voltage detection circuit, position sensoring and other modules. Software system is designed by modularization, which consists of a main program and some interrupt subprograms. The subprograms provide the functions of current sampling, PID control algorithm and commutation.Finally, soft and hardware debugging of the prototype is implemented and its performance is validated. The results of experiment show the scheme of a triple closed-loop digital low voltage servo control system is feasible and efficient. It provides a foundation for futher research.