WBG and Si Hybrid Half-Bridge Power Processing Toward Optimal Efficiency, Power Quality, and Cost Tradeoff

Wide-bandgap (WBG) power semiconductors offer a higher switching frequency and lower switching loss than their silicon counterparts but suffer from a significantly higher component cost. In this article, we propose a new WBG and Si hybrid half-bridge (HHB) power processing approach, which combines the high-frequency performance of WBG and low cost of Si toward optimal tradeoff among efficiency, power quality, and cost. The HHB approach uses a low-frequency base-power Si half bridge in a typical power converter to achieve a full-power conversion at a low cost and a high-frequency fractional-power WBG half bridge in parallel to improve the efficiency and power quality at a reasonable cost penalty. A current ripple and a cost analysis model are developed in great detail to indicates that the HHB approach can achieve a 20%-50% device cost reduction in comparison to an all-WBG converter design while offering almost the same efficiency and power quality. A simple control strategy is developed to enable the unique operation of the proposed HHB approach in this article. The HHB approach combining with the proposed control strategy can be easily implemented in a wide range of power converters. A 3-kW bidirectional dc-dc converter is built using Si IGBTs and SiC mosfets as a case study to validate the HHB concept. In comparison with the all-SiC design, the HHB-based converter achieves a comparable efficiency and two times higher current spectrum with at least 17% total cost reduction and 33% capacitor rms current reduction.