The Research Of Brushless DC Motor Control System Of Electric Bicycle

In recent years, With the rapid development of social economy, gasoline car has caused serious environment pollution because of its waste gas, a large oil resources is also demanded, Electric bicycle spread quickly for its energy saving, portability and affordable price, it has become an ideal vehicle for short trip. Electric bicycle share in a large amount of bicycle market, so developing the electric bicycle has a good social significance.Currently, brushless DC Motor (BLDCM) is the main driving source of the electric bicycle. In this paper, discuss the working principle and PWM speed control means in detail based on the structure of the BLDCM, explain the energy regenerative braking principle and control law to improve the endurance capacity of bicycle batteries. Since BLDCM is a strong coupling, multivariate and nonlinear systems, it is difficult to establish accurate mathematical model and hardly to achieve good results by using the classical PID control. Fuzzy control does not rely on the precise model of the controlled object, the application method of it is also relatively mature, commonly used two-dimensional fuzzy controller with PID control can improve the dynamic and static performance of the system. BLDCM of electric bicycle use double close-loop cascade control system, with current inner loop PI control and speed outer loop adaptive Fuzzy PID control, which can achieve PID control parameters self-tuning and improve the adaptability and robustness in ensuring the steady-state performance of the premise of the control system.According to the function of electric bicycle, designed the software and hardware of BLDCM control system. Hardware design based on ATmega32 microcontroller, peripheral circuits include power circuit, functional control circuit, three-phase full-bridge inverter circuit, under-voltage, over-current protection circuit. System software design use modular structure and C programming language. Each module is gived according to the functional requirements, such as the Hall-signal capture module, commutation module, A/D converter module, "speed-current" double close-loop speed control module. Build the double close-loop speed control system simulation model of BLDCM using Fuzzy Logic and SimPower System toolbox under the environment of Matlab/Simulink, also analysis the stimulation wave shape. Finally, creat and debug the hardware circuit of the controller, demonstrate the feasibility of the design of BLDCM control system.