The Applications Of Rare Earth Permanent Magnet Brushless DC Motor In Electric Vehicles

As the energy crisis and environmental awareness increase, the electric car are becoming of the future trend of automobile development. It has the features of clean non-pollution, energy source diversification and high efficiency. It can solve a series of problems caused by fuel cars. But our electric vehicle technology is still in the developing stage, many key problems are going to be solved. Motor and control technology is one of the key technologies of electric vehicles, they are the most important problems that are need to solve.BLDCM has the features of AC motor like simple, reliable and easy maintenance, and also has the features of DC motor like high efficiency,without excitation and good speed performance. It has been widely applied in various fields today.Secondly, the paper describes the principle of permanent magnet brushless motor and mathematical models, and introduced brushless DC motor speed control system of composition and theory; in order to verify the effectiveness and feasibility of the proposed method, the paper using Matlab simulation software set up control System model and made the simulation theory. The speed loop and current loop have both used PI regulator. Simulation and experimental results showed that the proposed method is correct and effective, and it provides a reference to the actual control system. The paper also proposed to use electronic differential instead of the traditional mechanical differential.In addition to use the traditional mechanical brake, the paper also increased the braking energy feedback.Based on this, the paper design of a dual-loop control system hardware of brushless DC motor of electric vehicles.In the design of the system, it used the TMS320F2812DSP chip as the processor. The entire control system took the isolation drive to improve system security and reliability. The thesis also details the design process and the design methodspower of the inverter circuit, PWM signal isolation circuit, the current detection circuit and system protection circuit. Finally, the paper designed the software part. The Software design used the modular concept. The program were programmed by C language. The paper introduced the control system of each module in the DSP software, and alse used the CCS DSP integrated development environment for software debugging to improve the development efficiency.