Control method of PMSM driving system with small DC-link capacitor

摘要

This paper proposes a capacitor-less inverter for AC motor driving system. The proposed converter consists of a single-phase diode rectifier, a small film capacitor at the DC bus, a three-phase voltage-source inverter, and a permanent magnet synchronous motor (PMSM). Since the DC bus capacitor is quite small, the input current of the AC source will be affected directly by the three-phase inverter power. Therefore, the proposed system can realize following two functions: 1) It stabilizes the motor driving and regulates the motor speed, and 2) it controls the input current and DC bus voltage waveform in order to obtain a unity-power-factor operation at the source side and suppresses LC resonance. This article puts forward the reference d-q axis current generation and DC bus voltage control method. The three-phase inverter and the PMSM are considered as a controlled current source to simplify the analysis of the whole system. The input current control method is proposed to achieve high power factor on the input side. A DC bus voltage controller is introduced to suppress the LC resonance. The simulation and experiment results validate the effectivity of the system.