Full-Bridge and Half-Bridge Topology Morphing Method for A Wide Output Voltage Range Based on Optimal Trajectory Control

The full-bridge (FB) LLC resonant converter, with its multiple operating modes, is very suitable for wide voltage range applications. To enhance its dynamic performance under wide output voltage variations, this article presents a topology morphing (TPM) method based on optimal trajectory control. Using this method, the optimal switching point is designed and calculated during the TPM between the half-bridge (HB) mode and the FB mode to achieve fast and smooth switching, thus ensuring a continuous output from the converter. For the first time, detailed formulaic derivations for the trajectory radii before and after switching were provided. To test the effectiveness of this method, experimental verification was carried out on a 3.3 kW prototype. The results demonstrate that there are no significant transients in the resonant components or output voltage during TPM.