Brushless Direct Current Motor Speed Control System

Brushless direct current motor(BLDCM) is a new kind of electromechanical products. It has not only the characteristics of asynchronous motor's simple structure, operational reliability and convenient maintain but also the characteristics of good adjusting performance of DC motor. So there is important theoretical research value and practical significance in using the technology of automation, embedded system to accomplish the control of BLDCM.Based on the BLDCM working principle, comparison and analyse of the current research achievement of BLDCM control system, this paper mainly focuses on speed adjustment of the BLDCM control system. The mathematical model of BLDCM is established with the phase variable, and presents the specific method of speed adjustment, then analyses a number of characterisics based on this.With the research background of BLDCM speed control system in the application of the weld walking device, a kind of BLDCM speed control system is designed based on digital signal processor(DSP). The whole DC system uses double close-loop control. The outer loop is speed loop, and inner loop is current loop. A method of control-variable adjustment Fuzzy-PI control using in the speed loop has been designed. The method is mainly based on the scope of the deviation between given speed and feedback speed of the system to decided to use the method of fuzzy control or PI control with dead-zone. In the fuzzy controller, we get the fuzzy rules based on using the method of Mamdani relation and do a lot of experiment. Matlab/Simulink tool has been used in modeling and simulation analysis about this system, simulation result shows that this system has high response speed, no overshoot, and high control quality.The master controller of this system adopts TMS320F2812 DSP, as parts of the system composition, the power convert circuit, current-measure circuit, switch circuit, position dectection circuit and so on have been designed to realize the speed control of BLDCM. The design of circuit mainly rely on the character of high integrated level, simple circuit, high level of antijamming capability, good robustness and so on, and used in the BLDCM speed control system. The software design is based on the function of the whole system, which shows the specific software flow.