Modified One-Cycle Controlled Bidirectional High-Power-Factor AC-to-DC Converter

Abstract

AC-to-DC converters based on one-cycle control exhibit instability in current control at light load conditions as well as when they are operating in the inverting mode. In this paper, a modified one-cycle controller for bidirectional AC-to-DC converter is proposed. A fictitious current component in phase with the utility voltage is synthesized. The sum of this current component and the actual load current is compared with the sawtooth waveform to generate the gating pulses for the switches. This modification not only renders stability to the converter at light load conditions and the inverting mode of operations but also enables the converter to seamlessly transfer its operation from the rectifying mode to the inverting mode and vice versa. Detailed simulation studies are carried out to verify the effectiveness of the proposed scheme. To validate the viability of the scheme, detailed experimental studies are carried out on a 2-kW laboratory prototype.