Sensorless Magnetic Flux Balancing Strategies for Novel Dual Active Bridge Converter ZVS Modulation Patterns

Novel Dual Active Bridge Converter (DAB) ZVS modulation schemes are proposed, which switch without adapting the switching frequency or the transformer on the entire operating area at zero voltage. During the start-up and transients where the modulation parameters are adjusted to ensure the desired power transfer, an offset occurs in the magnetic flux of the transformer, which may lead to saturation. This paper proposes sensorless strategies to balance the magnetic flux for the proposed modulation patterns during the start-up and transients. The strategies were verified experimentally.