Research On Sensorless Control Of Permanent Magnet Synchronous Motor Based On High Frequency Injection Method

The advantages of permanent magnet synchronous motor(PMSM)are small volume,high efficiency,high power density and so on,which makes it widely used in the drive system of electric vehicle.At present,the controller of PMSM is based on vector control and the position sensor is needed to provide the rotor position information.When the position sensor fails to provide the motor rotor position signal,the motor drive system can?t be in goodrunning.Sensorless technology can provide the rotor position signal in place of the position sensor to realize closed-loop control.The thesis is based on the project of general project of scientific research of Liaoning provincial department of education “research on fault diagnosis method of six phase permanent magnet motor drive system for electric vehicle(LGD2016030)” and national natural science foundation of china “fault diagnosis and fault tolerant control of multiphase motor drive control system for electric vehicle(61603263)”.In view of the fault of the motor position sensor in electric vehicle,the rotor position is obtained by the high frequency oscillation injection method and this enables the electric vehicle to start smoothly and operate stably at medium and low speed.Firstly,the principle of high frequency voltage injection method is analyzed,and then designs the IIR digital bandpass filter to extract rotor error signals of high frequency current signal,demodulation method of high frequency current signal and the rotor position estimation based on phase locked loop.At the same time,based on the principle of I system,the PI controller parameters of current loop and speed loop are designed.In addition,in order to modify the parameters and export data of the system,the GUI based on PMSM control system is designed to realize the dynamic simulation of the system.Finally,the simulation model based on pulsating high frequency voltage injection method of permanent magnet synchronous motor sensorless system is built in MATLAB/Simulink environment.The effectiveness and feasibility of the method is verified by the analysis and comparison of the simulation results.The influence of the frequency and amplitude of the injected high-frequency voltage signal,which are brought by the change of stator resistance and the bandwidth of the filter on the rotor position estimation accuracy are analyzed,and the improvement measures are proposed.For the current development process of digital signal processor system,it is not only long cycle but also low efficiency.In this paper,based on the Simulink code generation technology on DSP,it can improve the speed and efficiency of DSP system.In the MATLAB/Simulink environment,the model based on DSP motor control algorithm is built,modeling motor logic control function by Stateflow and defining the system hardware and software interface.Finally,through the Simulink code generation technology,the embedded C code for the DSP chip is successfully generated.On the basis of the embedded code generation,a 30 kW permanent magnet synchronous motor is used as the control object,and based on DSP28335 as the core control of permanent magnet synchronous motor sensorless experimental platform is built.The experimental results show that the sensorless vector control system of permanent magnet synchronous motor based on the high frequency voltage injection method can effectively track the position of the rotor in the low-speed and medium-speed,and the electric drive motor of electric vehicle can be operated at low speed when the position sensor fails.