Research On MTPA Control Strategy Of Permanent Magnet Synchronous Motor Based On High-Frequency Square Wave Signal Injection

With the superiority of wide modulation range,high-power density,and strong stability,the permanent magnet synchronous motor(PMSM)is extensively applied in various industrial fields such as computer numerical control(CNC)machine tools,electric vehicles,etc.The improvement of PMSM work efficiency can effectively reduce energy consumption and equipment operation costs.Therefore,aiming to achieve the efficient control of PMSM,this thesis takes the interior permanent magnet synchronous motor(IPMSM)as the research object based on the high-frequency(HF)square wave signal injection.Then the research is carried out on how to achieve the maximum torque per ampere(MTPA)control of IPMSM.Based on the IPMSM mathematical model and the theoretical basis of MTPA control,this thesis proposes an HF square wave injection-based MTPA control strategy,aiming at the problems of low injected frequency and dependence on digital filter in the conventional HF sinusoidal signal injection control.The proposed control strategy extracts the effective information of MTPA control from the HF component of the induced current through square wave voltage injection.Due to that the HF square wave signal does not have the limitation of waveform distortion,thus the injected frequency can be very high,which can achieve the decoupling of the fundamental frequency component and the HF component of the motor,and reduce the impact of the injected signal on the system’s fundamental frequency closed-loop control.In the process of HF signal extraction and processing,the digital filter of the traditional sinusoidal signal injection method is not needed,hence the dynamic performance of the system is enhanced,the calculation burden is reduced and the use of the additional hardware platform is avoided.To make the proposed MTPA control strategy applicable to the sensorless IPMSM control system,this thesis combines the HF pulsating signal injection method in a low-speed range and injects two voltage signals with large differences in frequency and amplitude into the motor simultaneously.The efficient control of IPMSM can be achieved through their respective signal processing.Moreover,an improved full-order sliding mode observer control scheme is employed to achieve sensorless control of IPMSM in the middle-and high-speed ranges by extracting rotor information from the fundamental wave equations.The proposed scheme can achieve the MTPA control by combining the square wave signal injection method at the same time.In this thesis,the proposed scheme is verified in the MATLAB /Simulink simulation environment.Meanwhile,a complete test platform of the motor system is built and the software control algorithm is designed to implement the proposed MTPA control strategy of the IPMSM system.Both the simulation and experimental results demonstrate the effectiveness and feasibility of the proposed control strategy.