Modulation of Bidirectional AC/DC Converters Based on Half-Bridge Direct-Matrix Structure

This letter proposes a half-bridge bidirectional isolated matrix-based ac/dc converter for compact ac/dc power conversion applications. The converter can control not only the dc voltage or current, but also the power factor of the ac current with a single conversion stage, which helps to achieve a higher power density with a lower complexity. The converter operates with zero-voltage switching or zero-current switching in all switches. Hence, the switching frequency of the converter can be increased higher, leading to smaller passive components. Besides the simple circuit, the modulation scheme derived from time domain analyses is also easy to implement. The proposed topology has been verified by experimental results for a 2-kW SiC-based prototype. A high efficiency of 96.8% was achieved at a full load condition. The current total harmonic distortion (THD) is lower than 4% and the power density is 1.8 kW/dm(3).