A PV-Inspired Low-Common-Mode Dual-Active-Bridge Converter for Aerospace Applications

In the framework of the more electric aircraft, the use of isolated dc-dc power conversion for the electrical power distribution system is one of the most investigated solutions. If the dc-dc converter produces a variable common-mode voltage, the leakage current can flow in the interwinding parasitic capacitance of the high-frequency transformer, leading to insulation deterioration and early failure. This paper proposes to use modified H-bridge structures, already employed in the photovoltaic system for dc-ac power converters, to enable a constant common-mode voltage for isolated dc-dc converters. The analysis shows that this solution can achieve the same efficiency as the conventional one, while simulations and experiments show a strong reduction of the common-mode current flowing through the transformer. A reliability analysis showed that the lifetime of the high-frequency transformer can be extended with the proposed solution.