  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 switching 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 include 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.
