Study Of Robust Sensorless Control Methods For Interior Permanent Magnet Synchronous Motors Of Vehicles

Permanent magnet synchronous motors(PMSM),with advantages of high efficiency,high power density and wide speed range,are widely used in the field of electric vehicles.The sensorless control,canceling the use of hardware sensors,adopts software algorithm and computation to obtain the rotor position,and thus facilitate the motor drive control.The sensorless control brings merits of hardware cost reduction,reliability improvement,volume saving and compatibility and power density enhancements,and its application in the motor control system of vehicles is promisingBecause of the harsh and complex conditions during the driving operations,for PMSM and especially interior PMSM(IPMSM)of vehicle drives which exists the nonlinear characteristics of time-varying and coupling,its system parameter deviations are inevitable.Moreover,the external noise and the nonlinear effects in the system will also brings adverse effects to the control.In such conditions,the accurate state information and fine control methods are significant for IPMSM high-performance control.This paper conducts the research on IPMSM control system,implements the analysis and designs of its sensorless control methods,and hence provide references for the research and application of sensorless control of IPMSM drives in vehicles.For the problem of parameter deviations of motor in real vehicles,the mathematical model of IPMSM control system and its electrical equations in the twophase stationary frame are built by considering the motor parameter uncertainties,and a robust rotor position observer for IPMSM based on the sliding mode observation(SMO)is presented to estimate the rotor position and speed.And considering the problem of output torque error caused by the IPMSM parameter deviations,the motor parameter estimation based on model reference adaptive system(MRAS)is used to estimate the inductance and permanent magnet flux of the motor online,and then the actual electromagnetic torque output of the motor can be calculated,thus the corresponding torque compensation effect can be obtained by comparing the torque estimation with the instruction.On this basis,the IPMSM sensorless torque control method is established to obtain more accurate torque control based on the SMO rotor position estimation and MRAS parameter estimation and respective torque compensation.Performance of IPMSM sensorless torque control system is analyzed by simulations,and results show that the approach can effectively estimate the rotor position and speed,and regulate the torque.In order to reduce the chattering phenomenon caused by the classical sliding mode control and hence to improve the performance of estimations,a robust rotor position observer for IPMSM based on the high order sliding mode observation(HOSMO)is proposed to provide the information of rotor position and speed by considering model parameter uncertainties and external disturbances.For the accurate speed control of IPMSM,a nonlinear robust speed control method based on backstepping control is designed.The presented method introduces the integral control and sliding mode actions into the control simultaneously to handle the maximum and average errors in the tracking and improve robustness of the control system at the same time.By combining the designed observation approaches and control methods,the IPMSM sensorless control system and its simulation model can be established.Simulation results show that the designed sensorless control system can achieve fine estimation and control,and maintain good robustness to uncertainties and interferences.Furthermore,in ordrer to realize sensorless control of IPMSM in low speed range,the proposed robust rotor position observation method based on SMO is combined with high frequency injection(HFI)based rotor position detection method which is suitable for low speed application.By using the results from these two methods respectively,the information of the position and speed estimation can be obtained,thus the sensorless control for IPMSM can be realized.The analysis results show that the designed method can effectively guarantee the estimations of rotor position and speed for IPMSM during low speed,realize control to higher speed range and achieve good control performance.Finally,the sensorless control methods are applied to the IPMSM control design motor-transmission integrated drive system for vehicle.Test bench experiment for IPMSM is first conducted to measure motor parameters of inductance and permanent magnet flux,and to calibrate the current trajectories of maximum torque per ampere(MTPA)and flux weakening(FW).By using the experiment resulrs of torque and speed responses of the motor,the IPMSM control system model is validated.In order to analyze the performance,the sensorless torque and speed control performance for IPMSM of vehicle is first investigated.Furthermore,IPMSM-2AMT integrated drive control strategy are designed,and the sensorless control methods are applied to the IPMSM control systems.Results show that the designed approach can effectively achieve the IPMSM control and ensure the operations of the integrated drive system.