3-Bridge LLC Resonant Converter with Auxiliary Switches Operating Over Wide Output Voltage Control Range

In this paper, a 3-bridge LLC resonant converter with auxiliary switches for a wide output voltage control range is presented. The proposed converter can be controlled in the following two ways to achieve a wide controllable output voltage control range of V-o similar to 3V(o). The first control mechanism is done through pulse width modulation (PM) of the auxiliary switches and the primary switching devices. The second control mechanism is done through frequency modulation (FM) of the primary switching devices configured to operate in the full bridge switching modes, when the auxiliary switches are 50% duty ratio or turned-off. The feasibility of the proposed converter is verified with experimental results of a 5kW prototype.