Analysis of Switch Losses in Cycloconverter-Type High Frequency Link Converter for Bidirectional Battery Chargers

On-board chargers with bi-directional power flow capability should display high power density to make them suitable for vehicle-to-grid applications. Selecting an optimal power topology and evaluating power losses in various power device candidates are important steps in the design and development of battery chargers. This paper presents an analysis of switch power losses in a 3.3kW cyclo-converter type high-frequency link converter with silicon carbide MOSFET. Although power losses are caused by many passive and active components, power losses in semiconductors are typically the dominant factors influencing the estimation the power conversion efficiency. In this respect, efficiency can be improved to achieve high power density by adopting the ac-ac power conversion architecture and by using wide bandgap devices. A theoretical power loss model for the proposed system is derived, and power losses in various power devices are estimated. In addition, the power losses in cyclo-converter type high- frequency link converter proves its superiority over the conventional dual-active-bridge converter, one of the popular circuit topologies for galvanic- isolated battery chargers. The analysis results for the power loss models are validated through PSIM thermal simulations.