Variable DC-Link Voltage LLC Resonant DC/DC Converter Using Wide Band Gap Semiconductor Devices

Application of wide bandgap power devices enables the power electronics system to achieve higher efficiency, improved power density and reduced weight. Wide range LLC converters are extensively applied in various application scenarios such as electric vehicle on-board charger and renewable energy generation due to their intrinsic zero voltage switching features and simple control implementation. In this paper, the design process of a high-frequency wide-range LLC resonant DC/DC converter using wide bandgap (WBG) devices is demonstrated in details. To broaden the operation range, linear feedback variable DC-link voltage control is utilized. The power loss model of the system is introduced and validated via simulation study. A 3.7 kW and 500 kHz experimental prototype is built with WBG devices. The experimental results reveal that peak power efficiency of the system can reach 98.4% with the variable DC-link voltage control while that of the conventional constant DC-link voltage control is 97.6%.