A three-phase PWM AC-DC converter with low switching frequency and high power factor using DSP-based repetitive control technique

This paper presents a novel digital control scheme for PWM AC-DC converters with low switching frequency used in high-power applications. The proposed scheme incorporates an inner current loop with an outer voltage loop to improve input power factor and regulate the output DC-link voltage. The inner current loop consists of a predictive controller and a repetitive controller. The outer voltage loop is composed of a digital PI controller and a load current compensator. A PWM AC-DC converter employing DSP control has been constructed to verify the proposed control scheme. A nearly unit input power factor can be achieved even with a low switching frequency. Experimental results confirm the feasibility and features of the proposed repetitive control scheme for unit power factor regulation