Research On Position Sensorless Control Technology Of Permanent Magnet Synchronous Motor For Vehicle

Permanent magnet synchronous motor(PMSM)has the characteristics of low maintenance cost,high efficiency,high power density,large starting torque and strong fluxweaking capability,which has been widely used in the drive train of EV and the HEV.The vector control of PMSM needs accurate rotor position information providing a reference by physical sensors,which can be replaced by the sensorless rotor position estimation technology.In order to simplify the structure of PMSM and reduce the cost,the following research work is carried out.In this paper,the working principle and model of PMSM are analyzed,and the rotor position identification method of low-speed-operation is established.The control scheme of that is injecting the high frequency pulsed voltage signal into the estimated rotor position coordinate,at the same time,extracting the feedback current signals containing the rotor position error information,then adopting the rotor position observer to identify the rotor position information.As for the high-speed-operation,the modified back-EMF rotor position estimation method is established.The output of the LPF is reassigned as a feedback for the SMO to minimize the phase lage.A new PLL scheme is designed which features the non-speeddirection-difference rotor position estimation.In order to enhance the rotor position identification ability,a modified full-speed-range rotor position estimation method is established with the aid of hysteresis control technology.It combines high frequency signal injection method within low speed range and static condition,while the back-EMF method for high speed range.In addition,in order to ensure that the proposed PMSM controller has good dynamic characteristics and robustness,the double closed-loop control strategy is adopted,which involves the adaptive disturbance rejection controller and an anti-saturation PI controller for the speed and current feedback loop respectively.MATLAB/Simulink simulation results show that good rotor position identification accuracy and speed response characteristics are achieved.The sensorless rotor position estimation technology heavily relies on the current feedback signals,as the result,the stability of which is more vulnerable towards current distortion than its counterpart with position sensors.To relieve the problem,the method of on-line adjusting the dead zone time is developed based on the nonlinear characteristics of the inverter switching characteristics.The simulation model of PMSM is established in MATLAB/Simulink,and the simulation verification is carried out.It can be concluded that the inverter output current distortion is alleviated in starting and the speed reversing.