Three-level half-bridge LLC converter with phase shift and frequency modulation control

摘要

This paper presented a three-level(TL) half-bridge(HB) soft switching LLC series resonant dc/dc converter and proposed two control modes: phase shift (PS) control and frequency modulation (FM) control. It analyzed the range of zero-voltage switching (ZVS) under phase shift mode in detail and the condition to achieve soft switching. It is able to achieve wide voltage gain range by switching between this two control modes, which is attractive for energy storage system applications with wide voltage variation. Voltage stress of each main switch is half of the input voltage. Soft switching for all the switches can be achieved in this circuit, so high efficiency can be achieved.