DC-Link Voltage Fluctuation Reduction of Vector Controlled PMSM Drives with Reduced DC-Link Capacitor

In some applications, to increase the system power density and lower the system cost, the dc-link capacitance of PMSM drives needs to be reduced. However, such practice may cause considerable dc-link voltage fluctuation. In this study, a method is proposed to reduce the dc-link voltage fluctuation. By adjusting the sixth harmonic component of the inverter dc-link current, the proposed method can indirectly lower the dc-link capacitor current, thus reducing the dc-link voltage fluctuation. Compared with other voltage fluctuation reduction methods, the proposed method is independent of a controllable front-end rectifier, and it does not require any motor parameters. The simulation results show that the proposed method is feasible.