Low-Frequency DC-Link Capacitor Current Mitigation in Reduced Switch Count Single-Phase to Three-Phase Converter

This article proposes an approach to mitigate the dc-link double-frequency ripple current in a three-leg single-phase to three-phase converter. This article is based on an economical active phase converter (APC) utilizing a fewer number of switches. The presented approach does not demand either bulky dc side passive ripple filter or additional semiconductor switches typically employed in active dc-link ripple filters. The proposed method introduces an appropriately selected ac capacitor into the APC circuit, also known as auxiliary capacitor-based APC, which mitigates the dc-link double-frequency ripple. Reduction of power loss in the equivalent series resistor of the dc-bus capacitor associated with the dc-link double-frequency ripple current enhances the lifetime of electrolytic capacitor typically employed in the APC. At full load, the dc-link current at double-fundamental frequency is reduced by more than 50% and the temperature rise in the dc-bus electrolytic capacitors is reduced by more than 30%. The proposed method is validated experimentally using a laboratory prototype APC. Theoretical and simulation results of the dc-link double-frequency current are in close agreement with the experimental findings.