Asymmetric isolated unidirectional multi-level DC-DC power converter

Abstract

This paper proposes an asymmetric unidirectional isolated multi-level DC-DC power converter (AUIMLDDPC). A three-winding transformer (TWT) is used as the interface between a half-bridge inverter (HBI) and two full-bridge rectifiers (FBRs). The turn numbers for two secondary windings of TWT are not the same. Thus, it results in unequal DC output voltages of the two FBRs. A selection circuit is adopted to control the unequal DC output voltages of two FBRS to be connected in series or stand-alone, and thus, generates a non-zero two-level voltage to control the magnitude of the output DC voltage of the proposed AUIMLDDPC. An output L-C filter is applied to filter out the high frequency harmonic of the non-zero two-level voltage. The secondary windings with unequal turn numbers for TWT can reduce the voltage change of the non-zero two-level voltage. Therefore, it can reduce the L-C filter capacity. To validate the performance of the proposed AUIMLDDPC, a hardware prototype is developed. The experimental results are as expected. Keywords: Multi-level, DC-DC, Half-bridge inverter, Full-bridge rectifier