Self-adapting Controller Design Of Motor For Electric Vehicle

Today's society is faced with two major problems, which is energy crisis and environmental pollution. At the same time, the electric vehicle is attracting more attention in many country because of its significant advantages for energy saving and cheaply. The driving motor is a central part of the electric vehicle and the key component is product the high performance motor. With the features such as small size, high efficiency, reliable performance, wide speed range and low noise characteristics and so on, the brushless DC motor(BLDCM) has been widely applied and developed among the electric vehicles.This paper takes BLDCM and its Controller as research objects based on motor's mathematical model, controlling theory and system performance index, and then established a simulation model of direct control system for BLDCM which is used the self-adjusting PID control strategy based on fuzzy reasoning rules. The control system realized speed and current double closed loop control,thereinto,the speed loop is outer loop and the current loop is inner loop. The simulation experiment results by MATLAB show that the system just took 0.02 s from original state to the given rotating speed and kept the speed stable when it get disturbed. Moreover, the value of ITAE was about 12%below the conventional PI control system, it means that the fuzzy PI controller is more efficient to suppress the torque pulsation and increase control system's steady ability.After the in-depth theoretical analysis and simulation, the BLDCM controller based on DSP28335 control chip of electric vehicle was designed. The controller incorporated power driving and inverter circuit, current-sensing circuit, power-switching circuit, rotor position detecting circuit and so on, it also could adaptable to the motor which nominal voltage is 48 V and rated current is less than 16 A. Moreover, the modules about the rotor position detection signal, current sampling and velocity measurement, PWM pulse driving generator and double closed ring regulation were designed in the software.The experiment was implemented after completing joint debugging of hardware and software for system. The waveforms of the terminal voltage, the rotor position signals and PWM commutation signal were watch. Moreover, through watching and analyzing the differences of speed variations between open-loop control system and closed-loop control system, we can know that the BLDCM controller based on double closed loop control which was designed in this paper could work normally, and compared with the open loop control BLDCM controller in the market, the control system has the advantages of small overshoot, good stability and fast response which took less than 1s from original speed tothe given rotating speed. That proves the correctness and rationality of the controller design.