Research On Dead Time Compensation In Permanent Magnet Synchronous Motor Drive Based On FOC

To prevent the short circuit of the bridge arm in the same phase of the inverter,we should add the dead time to the driving signal.Yet,the dead zone effect is the major source of the disturbance of the PMSM of the electric vehicle.It can cause increasing vibration and noise of the electric vehicle,and the decreasing speed and torque.The traditional static dead zone compensation method cannot achieve the ideal effect in the real.This paper puts forward a dynamic compensation algorithm based on fuzzy controller,which can improve the stability of dead zone compensation.The sliding mode controller is used to restrain the disturbance caused by the environment temperature changes and the mechanical friction of the rotor,so as to improve the anti-interference ability of the motor servo system in the dynamic environment.To solve the problem that the dead zone effect of inverter is greatly affected by the complex external environment,it's proposed that the traditional static compensation method can be combined with the fuzzy control algorithm.The static compensation value is obtained by experiment to form a static compensation table.The paper also designs the fuzzy control logic to obtain the actual output voltage and the setting output voltage,to adjust the compensation table dynamically.Thus,it can achieve the optimal compensation effect.In terms of the problem that the torque and speed of PMSM are affected by the high temperature and friction during operation,the paper presents a sliding mode controller to adjust the speed and torque.It overcomes the oscillation problem caused by the traditional PI controller under the external interference.The mathematical model of PMSM nonlinear system is established,and the exponential approach law is used as the approach function of the sliding mode controller to realize the sliding mode motion of torque and speed,which can improve the anti-interference ability.In the experiment,STM32 MCU is used as the realization platform,the hardware platform is designed by modules,and the software is compiled and debugged by time-sharing framework.The proposed algorithm is applied to verify the effect in real road environment.The harmonic component of inverter output waveform is reduced to less than 5%,and the change of speed and torque is smooth without jitter.The system can overcome the disturbance in the major real environment and achieve a more stable and comfortable driving experience.