The Study On Control System For Brushless DC Motor Based On PSoC

The electric bicycle is popular more and more for its environmental, portable, simple structure, easy to maintain and other outstanding advantages. In recent years the market demand is growing fast, more and more people begin to use the electric bicycles. The key technology for electric bicycles is the control of Brushless DC motor (BLDCM). Due to cost constraints, at present, many of BLDCM controllers are plagued with problems. Our objectives of this study are to settle the key technical issues, and design a BLDCM controller for electric bicycles to meet the needs of low-cost, high reliability and complete function.Based on the structure and working principle of BLDCM, the voltage equation of BLDCM in conduction, freewheeling and commutation state are presented. After that, the dynamic mathematical model of BLDCM is also introduced. On this basis, the thesis has made a profound analysis of electric bicycles'performance. According to the demand of the improvements of the products we designed the switching power supply and improved the drive circuit of the MOSFET. The detecting circuits of the current and the hall states are described in this paper.After analyzing some of the characteristics of PID model, the digital PI controller is designed to ensure its better effects of the control system. The control systerm is improved for the demands of the market.Finally, the motor with a rated voltage of 48V, rated power of 350W is selected as prototype to test the performance and functions of the controller, the graphics and data of the test results indicate that this controller can satisfy the needs of the market with low cost and good reliability.