A Wide Range Output Voltage Gain Operation With Mode Transition of Single Input Dual Output LLC Converter

摘要

This paper proposes a single-input dual-output LLC converter that expands the output voltage gain. The proposed circuit has three degrees of freedom (switching frequency and two-phase angles) and five operation modes. The five operation modes operate in half bridge, full bridge, and combinations thereof. Each of the transformers on the primary side is connected to the bridge in series or in parallel depending on the operation mode. By connecting the primary bridge structure using the operation mode, a wide range of gain is realized. The secondary circuit consists of an active bridge, and the two loads can be controlled independently using phase shift (PS) control. This paper also clarifies the control method to realize a mode transition between mode. For the transition between operating modes, by estimating the phase shift angle after the transition, there is no large error between the output voltages and a seamless transition is realized. The validity of the proposed system is confirmed with a prototype. The proposed circuit shows that the output voltage gain obtained is 0.25 to 1.0 or more. Moreover, the transition between modes has also been confirmed by experiments.