Compact Bidirectional GaN Buck-Boost Converter for Negative Rail Supply in Bipolar DC-Grids

A volume and weight optimized high-frequency bidirectional buck-boost converter for negative rail supply of modern bipolar DC micro-grids up to -300V is presented. By use of state-of-the-art eGaNHEMTs and ZVS turn-on, switching frequencies far beyond the range of similarly rated silicon based converters can be achieved. This enables higher power density while maintaining high efficiency of more than 97% at rated output power of 3kW. The proposed converter achieves soft turn-on for each operating point by using a control principle that only requires the measurement of DC-values.