Research on Flux-Weakening and DC-link Voltage Compensation of PMSM Drive System without Electrolytic Capacitor

The permanent magnet synchronous motor drive system without electrolytic capacitors using small capacitance capacitors is a research hotspot in the field of household appliances. This article proposes a flux-weakening control strategy for a permanent magnet synchronous motor drive system without electrolytic capacitors. It is based on the equivalent current power-tracking method, taking into account the fluctuation range of DC bus voltage and speed, to obtain the expected value of the d-axis current. This results in good power and speed tracking effect, while improving the power factor on the grid side and reducing the amplitude of bus overvoltage during startup. Secondly, when the DC-link voltage fluctuates to a low point below the back electromotive force of the motor, it will affect the current control effect and cause the DC-link voltage to rise or even overvoltage. A DC-link voltage compensation control strategy is proposed, which proportionally compensates for the expected voltage output from the current loop, achieving a reduction in the rise and fluctuation amplitude of the DC-link voltage. Finally, a simulation model was established, and the effectiveness of the algorithm was verified by the simulation results.