A Soft-Switched Bidirectional Single-phase Single-Stage AC-DC Isolated Converter with Active Power Factor Correction and Reduced Power Device Count

Single-phase single-stage bidirectional AC-DC converters are widely used in grid-connected applications. They attract increasing attention in research and industrial community because of their advantages of lower cost, higher efficiency, and lower power semiconductor device count as compared to traditional two-stage topologies. However, most existing single-stage AC-DC power factor correction (PFC) topologies exhibit the drawbacks of uncontrolled bus voltage, not actively shaped input current, hard-switching operation, and large count of power semiconductor devices, etc. In this paper, based on dual-active-bridge structure, a novel soft-switched bidirectional single-phase single-stage AC-DC converter is proposed with remarkably lower count of power semiconductor devices, as compared to existing bidirectional AC-DC isolated converter topologies. The AC-side current is actively shaped with a unity power factor and a low total harmonic distortion. Soft switching operation is achieved for all switches. The proposed topology exhibits great potential to achieve a higher efficiency, a higher power density, and lower cost.