Steady‐State and Transient Analysis of LLC and iLLC Resonant DC–DC Converters with Wide Voltage Operations Using GaN Technology for Light‐Duty xEV Charging Systems

Abstract

In recent times resonant converters have become more popular due to the demand for xEV chargers increasing rapidly. Due to its unique characteristics in operating the converter in either zero‐voltage or zero‐current switching during switching conditions, hence it reduces the switching and conduction losses. From the literature, there are several converters in the resonating networks one of its own is inductor‐inductor‐capacitor (LLC), it has a drawback of higher conduction losses at light loads, poor transient performance, and stability. Hence, this article investigates an electric vehicle (EV) charger for xEV charging stations using an interleaved inductor‐inductor‐capacitor (iLLC) DC‐DC converter. It has features of lower losses during various loads, better transient performance with low ripples and stable regulation during sudden variations. An integrated closed‐loop technique is proposed with a constant voltage charging mode of operation, along with a hybrid control scheme of variable frequency + phase shift modulation (VFPSM). To examine the performance of the proposed system, it is compared with the LLC converter under similar operating conditions and a detailed steady‐state and transient analysis is presented. The prototype is built using GaN switches at a rated power of 3.3 kW at an efficiency of 98.2%.