Loss Analysis and Efficiency Test of a 3 MW 10 kV AC to ±750 V DC Power Electronic Transformer

In this paper, a 3 MW 10 kV AC to ±750 V DC power electronic transformer (PET) based on cascaded H-bridge (CHB) and isolated series resonant dual active bridge (SRDAB) converters is introduced first. Power losses are analyzed for this PET, including the hard-switching CHB, the soft-switching SRDAB and the medium-frequency isolation transformer (MFT). The results show that the losses of this PET is not only dependent of the input power but also dependent of the power flow direction. The field efficiency measurement results of the 3 MW 10 kV AC to ±750 V DC PET proved the correctness and accuracy of the loss analysis and the power flow dependency characteristics of this PET.