A transformer comparison for three-phase single active bridges

This paper investigates the impact of the transformer configuration on the performance of the three-phase single active bridge. The investigated configurations are a wye-wye connected transformer, a wye-delta connected transformer and a delta-wye connected transformer. The converter's operation is described in detail for all transformer configurations. Voltage and current waveforms of all converter components are derived analytically. Furthermore, current and voltage stresses of the converter components are compared and the advantages and disadvantages of the different transformer configurations are discussed. The comparison shows large difference of the voltage and current stresses for the different configurations resulting in a large deviations in power density and efficiency. Experimental results taken from a 5 kW / 80 kHz laboratory breadboard three-phase single active bridge verify the analysis.