A Dual-Transformer-Based Resonant Converter With Constant Switching Frequency and Variable Input/Output Gains for Aircraft Electrification

This paper proposes a novel dual-transformer-based resonant converter for electric aircraft applications. Different from conventional resonant converter topologies, the proposed converter operates at constant switching frequency and provides variable input/output gains. All switches in the proposed converter operate with soft switching for a full range of load and voltage. Most importantly, the proposed topology does not require current sharing control since the transformers do not operate in parallel, which makes it robust to parameter variation. Mathematical models for the converter are derived in detail to estimate soft switching range, power losses, and efficiency of the converter. Comparisons show that the efficiency of the converter is competitive with other common topologies such as dual active bridge and LLC resonant converters. In addition, it is shown that the number of switches can be significantly reduced when more transformers are connected. Finally, simulation results for a 332-kW system and experimental results for a 5-kW laboratory-scale prototype have shown the effectiveness of the converter, achieving 98.95% peak efficiency.