Research On The Position Sensorless Vector Control Of Permanent Magnet Synchronous Motor For Electric Vehicle

Under the influence of environmental protection and energy crisis,electric vehicles have made considerable progress in recent years as an energy-saving and environmentally-friendly vehicle.As the heart of electric vehicles,motor drive systems play a significant role in electric vehicles,and have a profound impact on the performance of the vehicle.Permanent magnet synchronous motor is widely used as the driving actuator of electric vehicles.High-performance vector control technology is widely used in the control of permanent magnet synchronous motor.But in order to achiev the magnetic field orientation,mechanical sensors need to be installed to detect the rotor position information.This will increase the cost and complexity of the system and reduce the reliability of the system.Therefore,it is of great theoretical and practical significance to carry out research on the position sensorless vector control technology of permanent magnet synchronous motor.In this paper,the double closed-loop vector control system of surface-mounted permanent magnet synchronous motor is taken as the research object.And the method of position sensorless control in the whole speed range is studied.The specific research content is as follows:In order to improve the anti-disturbance capability and the dynamic response performance,the speed controller and the current controller of PMSM vector control system are ameliorated.This lays a firm foundation for subsequent sensorless control.After the detailed analysis of the traditional sliding mode reaching law,combined with sliding mode variable structure control theory,a new sliding mode speed controller based on the new double-power reaching law is designed.Then the coupling of the current loop in the traditional permanent magnet synchronous motor vector control system is analyzed in detail.In order to realize the decoupling of the d-q axis current,a decoupled current controller based on the internal model principle is designed.Finally,the simulation analysis is implemented.Aiming at the position sensorless control of permanent magnet synchronous motors in the middle and high speed region,a rotor position detection method with on-line identification of motor parameters based on adaptive second-order sliding mode observer is studied.Firstly,according to the mathematical model of motor and the theory of super-twisting algorithm,an adaptive second-order sliding mode observer is designed,in which the real-time estimation of stator resistance and rotor speed is realized.This observer avoids the use of low-pass filter and eliminates the adverse effects caused by perturbation of stator resistance parameters.Secondly,in the synchronous rotating coordinate frame,a second-order sliding mode observer is designed to estimate the permanent magnet flux of the rotor.Therefore,the adverse effects on the position tracking observer caused by perturbation of permanent magnet flux are eliminated.So the accurate estimation of rotor position is realized.Finally,a simulation comparison study is conducted based on the theoretical analysis.Aiming at the position sensorless control of permanent magnet synchronous motor in low speed region,two pulsating high-frequency square-waveform voltage injection methods based on the filterless signal separation strategy are studied.Firstly,the shortcomings of traditional pulsating high-frequency sinusoidal voltage signal injection method are analyzed.Based on these analyses,two types of high-frequency square-waveform voltage signal injection strategies are proposed: square-waveform voltage signal injected into the estimation synchronous rotating coordinate frame and square-waveform voltage signal injected into the stationary coordinate frame.Secondly,the advantages and disadvantages of these two types of square-waveform voltage signal injection strategies are analyzed.Then a filterless signal separation strategy is proposed to solve the problem of signal's attenuation and delay caused by the filter.As a result,sensorless vector control of PMSM in the low speed region is realized.Finally,the simulation analysis is implemented.Aiming at the sensorless vector control of PMSM in the whole speed range,a kind of composite observer is designed,which integrates the pulsating high-frequency square-waveform voltage signal injection method and the adaptive second-order sliding mode observer method very well.