Variable DC-Link Voltage LLC Resonant DC/DC Converter With Wide Bandgap Power Devices

Abstract

Application of wide bandgap power devices enables the power electronics system to achieve higher efficiency, improved power density and reduced weight. Wide range <i>LLC</i> resonant dc&#x002F;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 <i>LLC</i> resonant dc&#x002F;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 <i>LLC</i> converter in all the operation range.