Isolated LLC Converter for PEV Charging for Wide-range Voltage Gain using Six-switch Bridge

Abstract

This paper proposes a dual LLC converter based on a six-switch bridge to charge deeply depleted plug-in electric vehicle onboard battery packs. The primary-side switch network comprises an input series or parallel, and two types of transformer-independent modes. Thus, there are four operation modes. In the input series mode, normalized voltage gains are scaled to 0.5 therefore, a low output voltage can be obtained. In addition, in the input parallel mode, the normalized voltage gains are scaled to 2.0. These four modes operate at the resonant frequency at the switching frequency. Therefore, the efficiency performance can be optimized over a wide output voltage range. The validity of the proposed system is confirmed with a 1-kW prototype.