Optimization of Power Sharing and Switching Frequency in Si/WBG Hybrid Half-Bridge Converters Using Power Loss Models

Abstract

The Si/WBG hybrid half-bridge (HHB) coordinates the hybrid-frequency operation and power-sharing ratio between the low-frequency Si phase and the high-frequency WBG phase to offer the same WBG benefits but with a much-reduced cost, in comparison to a full WBG solution. However, no generalized methodology has been reported so far to realize the full-scale optimization of switching frequency and the power-sharing ratio between those phases. In this paper, we first develop a generalized power loss model for Si/WBG HHB with total power loss as output and switching frequency and power-sharing ratio as a continuous input variable. And then develop a dynamic power-sharing ratio and switching frequency control to achieve minimum power loss over a wide load range. A 3-kW prototype of the Si/SiC HHB-based DC/DC converter is built to validate the power loss model and proposed control strategy. In comparison with several fixed parameters, the dynamic parameters obtained by the proposed power loss model achieve a 6-18% total power loss reduction without sacrificing power quality performance.