Optimization of Under-Voltage Starting Performance of PMSM Based on Improved Voltage-Loop Quasi-Z-Source Inverter

Low-voltage servo systems often use batteries for power. As the battery continues to discharge, the DC bus voltage of the inverter circuit gradually decreases. Before triggering the undervoltage shutdown protection, a derating method is generally used in engineering under undervoltage conditions. At this time, back electromotive force saturation occurs, and the starting current and torque are limited, leading to a decline in starting performance and a slower overall system response speed. To address this issue, a new control strategy is proposed, which combines the Quasi-Z-source network with the traditional low-voltage servo driver. Additionally, the rate of change of the phase current amplitude of the permanent magnet synchronous motor (PMSM) is introduced into the voltage loop control circuit of the Quasi-Z-source network as a compensation amount, forming a positive feedback voltage loop control structure. This improves the DC bus voltage and its dynamic response performance, increases the motor starting current and starting torque, thereby improving the starting performance of the system under undervoltage conditions. The effectiveness of the proposed control strategy is verified through MATLAB/Simulink simulations and experiments.