A Linear-Resonant Hybrid Bridge DC–DC Converter

A linear-resonant hybrid bridge dc–dc converter is proposed in this article. The converter adds a set of linear-bridge-arm based on the traditional half-bridge LLC resonant converter. This converter can operate in a high-voltage-gain (HG) mode and a low-voltage-gain (LG) mode by adopting pulsewidth modulation strategy and pulse frequency modulation strategy respectively. In the HG mode, it can control the inductor current increasing linearly by the linear-bridge-arm to obtain higher voltage gain and wider output range than the traditional LLC resonant converter, and the voltage gain is less affected by the magnetizing inductor. In the LG mode, the voltage gain characteristics of the proposed converter are similar to that of the traditional LLC resonant converter. The proposed converter works with negligible feedback current. In addition, all power switches can realize soft-switching in a wide load range. The working principle, voltage gain, design approach, and topologies comparison are introduced in this article. Finally, an experimental prototype based on constant current and constant voltage charging was built, with 400 V input voltage, 180–310 V output voltage, and 0–4.5 A output current. The experimental results verified its feasibility.