Expansion Transition Speed of PMSM under MTPA Control Strategy Based on Improved Voltage Loop Quasi-Z Source Inverter

Maximum Torque Per Ampere (MTPA) control strategy effectively enhances the efficiency of permanent magnet synchronous motors (PMSMs), widely applied to extend the driving range of electric vehicles. However, as the battery discharges, the DC bus voltage of the inverter decreases gradually, limiting the switching frequency of the MTPA control strategy due to the voltage limit circle constraint. This reduction affects the acceleration performance and uphill climbing capability of electric vehicles. To address this issue, a novel control strategy is proposed. It introduces a Quasi-Z source network into the PMSM inverter and utilizes the rate of change of phase current amplitudes of the PMSM as a compensating factor in the voltage loop control of the Quasi-Z source network. This forms a positive feedback voltage loop control structure, enhancing the DC bus voltage and its dynamic response performance, thereby improving the switching frequency and extending the operating range of the PMSM. MATLAB/Simulink simulations and experimental validations demonstrate the effectiveness and feasibility of the proposed control strategy.