Efficiency Improvement from Topology Modification of the Single-Switch Isolated Quasi-Z-Source DC-DC Converter

Single-switch converters can be an attractive solution for low-cost and low-power applications. This paper studies efficiency improvements from topology modifications of the single-switch galvanically isolated quasi-Z-source DC-DC converter. The following approaches were studied: synchronous rectification in the quasi-Z-source network, implementation of a voltage multiplier rectifier and the multidevice switching stage, and elimination of the DC blocking capacitor from the primary winding of the isolation transformer. To evaluate the performance improvement, the efficiency was measured for all approaches in a wide input voltage and power range. It was shown that thanks to the proposed modifications, the peak efficiency of the single-switch galvanically isolated quasi-Z-source DC-DC converter was increased to 95.5%, which includes the auxiliary power and control system losses.