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, leakage current can flow in the inter-winding 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 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.