4 kW Auxiliary Power Module for Electric Vehicles Utilizing a Dual-Phase LLC DC-DC Converter

This paper introduces a novel resonant tank design approach for dual-phase LLC DC-DC resonant converters in Auxiliary Power Module (APM) applications. The proposed design ensures that the impedance of one phase is consistently either larger or smaller than that of the other phase across a wide range of input and output voltages. As a result, only a single Switch-Controlled Capacitor (SCC) circuit is needed to achieve current sharing across the load range. This reduces system complexity and implementation costs without compromising efficiency or current-sharing performance. The design procedure is detailed for both phases, and experimental results from a full-scale, GaN-based 4 kW APM validate the effectiveness of the proposed approach in maintaining current sharing across varying input/output voltages and load conditions. Furthermore, flat efficiency curves with calculated average of more than 95.5% were achieved for different battery voltages, with a peak efficiency surpassing 96.3%.