Harmonic-Balance Based Power Flow and ZVS Analysis of a Quad-Active Bridge DC-DC Converter

The power flow control of multi-active bridge converters requires a comprehensive steady-state analysis of the converter and the determination of conditions for zero voltage switching of all switches in the converter which result in minimum switching loss. This paper aims to model and carry out the power flow and Zero Voltage Switching (ZVS) analyses of Quad-active-bridge (QAB) dc-dc converter. The dynamic as well as the steady state analyses of the converter were carried out, thereby determining the phase shifts required to meet commanded load powers. The full equivalent circuit model of the converter which includes winding resistances and magnetizing inductances is used rather than the popular lossless star-equivalent circuit model that may introduce significant error in the converter's analysis. The conditions which ensure the converter working in ZVS mode are determined and experimentally verified.