Novel Bipolar-Type Direct AC–AC Converter Topology Based on Non-Differential AC Choppers

This paper introduces a novel H-bridge structured ac–ac pulsewidth modulation (PWM) converter topology based on two-level non-differential ac chopper legs, which can work at the non-inverting and inverting modes for the utility voltage compensation. Compared to the traditional bipolar-type H-bridge ac–ac converter, no bidirectional switches are switched in a complementary manner to overcome the commutation problem due to the delayed response of electronic circuits and semiconductor switching devices. The detailed PWM control signals and operational principles are presented to regulate the output voltage in a bipolar manner. Especially the main advantage is that the proposed ac–ac converter has the same buck/boost operation process for non-inverting and inverting modes, which ensures the continuously average current supply to the low-voltage output side without a high-value capacitor to support power. Additionally, due to the common sharing ground of the input and output, the feature that output can reverse or maintain phase angle with input is supported well. Then, the detailed analysis, design conditions, and experimental verification based on a 1 kW experimental prototype are presented.