An Integrated Flying Capacitor Three-Level DC/DC Converter With Mismatch Power Processing Capability

In this article, an integrated flying capacitor three-level dc/dc converter with mismatch power processing capability is proposed. The proposed converter has two photovoltaic (PV) input interfaces in series and can provide an additional current path for PV modules to eliminate mismatched power. Through the integrated flying capacitor, the voltage stress of all primary switches is reduced. Furthermore, a flying capacitor voltage active balancing control strategy is proposed to balance the voltage stress of primary switches. By adjusting the time when the main power flows through the flying capacitor to compensate for the effect of the mismatched power on the flying capacitor, the voltage of the flying capacitor can be controlled to half of the total input voltage. In addition, all switches in the converter operate under zero voltage switching (ZVS) conditions, and the switches on the main power circuit have a fixed 0.5-duty cycle, making the converter highly efficient and high power transmission capability in all cases. A 500 W laboratory prototype was constructed, and experiments were carried out to verify the validity of the theory.