Variable DC-Link Voltage LLC Resonant DC/DC Converter With Wide Bandgap Power 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
resonant dc/dc converters are extensively applied in multiple scenarios, such as electric vehicle charger and renewable energy generation. In this article, the design process of a high-frequency wide-range
LLC
resonant dc/dc converter using gallium nitride HEMTs and silicon carbide diodes is demonstrated in details. To increase the operation range, variable dc-link voltage control is utilized and investigated via analyzing the impact of the dc-link voltage on the operation point. The power loss model of the system based on the characterization results is presented and validated via simulation study. A 3.7 kW and 500 kHz experimental prototype is built to verify the proposed design process. The experimental results reveal that variable dc-link voltage control can increase power efficiency of
LLC
converter in all the operation range.