Sensorless Control Of Permanent Magnet Synchronous Motor For Electric Vehicles

Energy-saving and environment-friendly Electric Vehicles is the main developmental direction of the world's automobile.High performance Permanent Magnet Synchronous Motor is the key system of Electric Vehicles and accurate detection of rotor position and speed can guarantee PMSM running normally.The traditional PMSM rotor position and speed are detected by mechanical sensors,which increases the mechanical cost and is vulnerable to environmental impact,resulting in damage and seriously affecting the safety and stability of Electric Vehicles.The paper studies the sensorless vector control technology in low,medium and high speed and full speed range of PMSM.The main work is as follows:The paper establishes PMSM vector control system mode and designs the motor speed regulator and current regulator.In order to overcome the overshoot problem in traditional PMSM vector control system,a speed regulation method based on feedback gain is proposed.The model of PMSM vector control systems before and after improved are established with Matlab.The simulation results show that the improved method can effectively suppress the overshooting phenomenon and improve the anti-jamming and steady-state performance of the system.Since it is difficult to obtain the initial position of the PMSM rotor,a direct axis direction judgment method,which is based on the relationship between inductance and current,can be used to estimate the initial position of the rotor by the saturation characteristics of the rotor magnetic circuit of the motor.The rotor position and speed of PMSM at low speed are estimated by pulse vibration high frequency signal injection method.Simulation results verify that the proposed algorithm can effectively estimate the speed and rotor position of the motor under zero and low speed conditions.The shortcomings of the traditional Extended Kalman Filter(EKF)algorithm estimating the rotation speed and rotor position of PMSM at medium and high speed were analyzed and improved.Traditional EKF existing model error easily leads to filter divergence and slow convergence speed.This paper proposes a fading filtering algorithm to increase the proportion of current information and weaken the old information by multiple fading factor insteading of the conventional scalar fading factor.A sensorless control algorithm is proposed to realize the control within full speed range of PMSM and verified by simulation.A model of dual-motor front-and rear-axle drive type EV is built.A torque distribution control strategy is designed based on two operating modes,which respectively are single motor driving and double motor driving.The method switches the two working modes in real time according to the total vehicle demand torque in order to realize the efficient operation of motor for the safe running of vehicles.