Research With Fuzzy Reasoning Base On Differential Speed Control Of Electric Vehicle With Wheel Hub Type Brushless DC

Electric vehicles (EV) have become an important way to solve the energy shortage and environmental pollution because of its simple structure and can use a variety of resources. And the in-wheel brushless DC motor (IWBLDCM) has got more and more applications in electric vehicles due to its own advantages.The driveling of the vehicles is through installing the in-wheel brushless DC motor in the wheel hub directly, thus can eliminate the clutch、deceleration device、 mechanical differential(MD) and other components which can simplifies the vehicle structure and improve the transmission efficiency in some degree. For eliminating the mechanical differential, the electric vehicles’ inner wheel staying put and outer wheel slipping because of the inner and outer wheel taking different distance when in steering which will reduce tire life even cause serious traffic accidents. thus require electronic differential control system to achieve differential.In this paper, after the analysis of the advantages and disadvantages of torque differential control and speed differential control based on the theory of mechanical differential control, we introduced the electronic differential(ED) strategy which is based on the equivalent of output electromagnetic torque, namely we can achieve the differential control if the output electromagnetic torque is equal when both sides of the wheel suffered different resistance in steering.In this paper, we adopted the bipolar PWM modulation on speed loop and current loop control system based on the detailed analysis of unipolar and bipolar PWM modulation and the dynamic mathematical mode of IWBLDCM which can achieve non steady-state error and better dynamic performance.In order to improve the vehicle’s stability and dynamic performance of speed response in steering, in this paper we introduced the fuzzy PID controller in the speed loop of the control system which can use the fuzzy control to adjust the PID parameters of the speed controller. Compared to the traditional PID control, the fuzzy PID control has a better control precision and better dynamic performance of speed response.In this paper we built the simulation model of ED control system for IWBLDCM in corresponding development environment based on the equivalent of output electromagnetic torque. The simulation results have proved that the electronic differential control strategy we adopted can achieve the differential and also the stability and dynamic performance of speed response when in steering.In this paper, we designed the software of ED control system based on TMS320F2812.