A Novel Control Method for Quasi-Z-Source Resonant DC-DC Converters

This paper presents a control strategy for a DC-DC quasi-Z-source (qZSC) resonant converter that makes the DC bus voltage between the Z-source network and the transformer almost immune to input voltage and load variations. By varying the zero-voltage states of Z-source converters and implementing closed-loop control, the switching frequency is fixed, achieving zero voltage switching (ZVS) and zero current switching (ZCS) resulting in improved efficiency. Without fixing the frequency, a resonant converter’s design must accommodate a wide range of switching frequencies, complicating the design and control of the resonant tank. Simulation and experimental results validate the method, demonstrating significant improvements in efficiency and stability under various conditions.