Reverse power flow control possibilities of galvanically isolated impedance-source DC-DC converters

Galvanically isolated impedance-source (IS) dc-dc converters are a high performance solution proven for emerging power electronics applications. However, studies of their bidirectional operation have been scarce. Focus in this paper is on the reverse power transfer possibilities of the high performance quasi-Z-source (qZS) series resonant dc-dc converter. This enables extension of functionality and application range of the converter to the energy storage and buffering systems. Two novel methods of reverse power flow control were introduced: one that requires no qZS network reconfiguration and is based on the resonant properties of the given topology, while the other is based on the qZS network reconfiguration into LC filter and does not depend on whether an IS converter is resonant or not. Experimental study was conducted for the power level of 250 W within the output voltage range of 20 V to 30 V. Experimental results corroborate the theoretical predictions and show that one of the methods is superior to the other by efficiency values and curve flatness.