Design And Research Of Permanent Magnet Brushless DC Motor Control System

At present, the government is making great efforts to develop new energy industry, and promote energy saving and consumption reducing. Permanent magnet brushless DC motor(BLDC) as a part of the new energy industry, has achieved large-scale application in electric vehicles, and has a good development prospects. So, the research and design of BLDC control system has strong application value and necessity.On the basis of consulting a large amount of documents, the structure and principle of BLDC is introduced and the simulation experiment of PID control system of BLDC is presented in this paper. Then the effects of two modes that current control and direct torque control on the response of BLDC are analyzed. After comprehensive comparison, this paper chooses current control method to design the BLDC control system. When the BLDC is running in a larger speed range, the speed response has a larger overshoot, performance of the controller is not satisfactory. So, based on the PID controller, the parameter adaptive fuzzy PID controller structure is designed combined with fuzzy control theory in this paper. Through simulation experiments, conclusion shows that the fuzzy PID controller has great speed response and torque response. Compared with PID controller, which significantly increases the range of speed adjustment, and achieves good control effects.Based on Kalman filter, a rotor position identification method for BLDC is designed in this paper. Firstly, according to the BLDC parameters, we calculate BLDC phase’s back-EMF, obtain smooth waveforms after the Kalman filter, then calculate line back-EMF and judge the reversing signal according to the line back-EMF zerocrossing. Secondly, a logical method of treating position signal is used for filtering the dithering of the position signal, to enhance the ability to detect the rotor position in low speed. According to simulation experiments, the rotor position identification method can effectively identify rotor positions, and provide accurate rotor position signal. This method effectively broadens the scope of identifying rotor position, so that it could match fuzzy PID control system.Finally, a driving module of the BLDC is designed in this paper, to realize the fuzzy PID controller and rotor position identification. In which, the DSP TMS320F2812 chip is taken as the control core, and both the N channel MOSFET drive circuit and signal acquisition circuit is included. According to the control system designed in this paper, the software structure of the control system is designed, and some modules are debugged.