Research On Sensorless Control Performance Improvement Of Permanent Magnet Synchronous Motor Electrical Drive For Electrical Vehicle

Permanent magnet synchronous motor is widely used in electric vehicle traction system,owing to its wide speed range,high torque density,low noise and small size.Normally,resolver is used to obtain rotor position information,but it has some problems,such as installation zero deviation,high system cost,low reliability,no fault redundancy configuration and so on.Therefore,it is of great significance to study the sensorless electric drive system.However,there are still some problems in realizing high performance sensorless control technology.Firstly,system optimization design is difficult to take in to account multi-objective requirements simultaneously.Secondly,initial position detection accuracy is low and reliability is poor.Thirdly,the high frequency injection method has some shortcomings in position estimation accuracy,dynamic and static performance.Fourthly,it is difficult for compound control algorithm to switch smoothly when wide speed range is realized.In this regard,the main research work and achievements of this paper are summarized as follows:1)A multi-objective visualization design method based on D-partition method is proposed,aiming at solving the problem of system optimization design.Firstly,discrete domain D-partition method is proposed,which can accurately obtain the parameter stable region.Secondly,time-and frequency-domain specifications as well as the influence of parameter uncertainties are graphically analyzed.Finally,the parameter optional regions satisfying multiple constraints are obtained to ensure the stability of the system and achieve multi-objective optimization.This method can not only directly and clearly analyze the distribution and trend of performance specifications,but also flexibly and concisely complete multi-objective optimization.2)The initial position detection is thoroughly studied.Firstly,a high frequency rotating injection method based on current amplitude demodulation is proposed,including three-phase current amplitude demodulation and self-adjusting frame amplitude convergence,which simplifies the signal processing and improves the accuracy of position estimation.The recursive discrete Fourier transform is used to calculate the amplitude and reduce the filtering link.Secondly,a high frequency pulsating injection method based on direct signal modulation is proposed,in order to overcome the problems of small stability range and long dynamic convergence time caused by low-pass filter.Finally,the strategy of connection fault self-inspection is put forward to improve the safety of electric drive system.3)Low speed sensorless control is thoroughly studied.Firstly,a high frequency rotating injection method based on dynamic coordinate system is proposed,so as to simplify the signal processing and reduce the accuracy of position estimation affected by non-ideal factors.An inverter nonlinearity compensation strategy is proposed to reduce six-time ripples in the estimated position.Secondly,a high frequency pulsating injection method based on moving average filter is proposed to improve the stability and convergence speed of the position observation system.Finally,a unified visualization model is proposed based on the analysis of high frequency injection mechanism,which can derive new high frequency injection methods.4)Wide speed range sensorless control is thoroughly studied.Firstly,a harmonic elimination method based on cascaded second order generalized integrator is proposed,so as to improve estimated position accuracy and the stability.Secondly,a composite control based on current non-linear regulation is proposed,which shortens the switching time of current-frequency control + sliding observer,and reduces the speed fluctuation.Finally,as for hybrid sensorless control based on high frequency injection and sliding mode observer,the switching strategies based on double phase locked loop and single phase locked loop are studied,respectively.It is demonstrated that stable operation and smooth transition in a wide speed range can be obtained.In addition,simulation and experimental results prove the correctness and validity of the research work and achievements.