Control Strategy for Zero-Voltage-Switching Multi-Resonant Three-Level Converters

Zero-voltage-switching multi-resonant three-level converters have some advantages such as reduced the voltage stress of the switches and diodes; ZVS achieved in a wider range and significantly reduced filter. They use the interleaved PFM control strategy. This paper presents the implementation of the interleaved PFM control strategy. Due to slight differences between the control circuits and drive circuits of the switches, there is slight difference between the duty cycles of the two switches, which results in the voltage of flying capacitor is not equal to the half of the input voltage. This paper proposes voltage control of the flying capacitor, which adjusts turn-off time of the switches, to ensure the voltage of flying capacitor equal to the half of the input voltage. The experimental results are presented to verify the effectiveness of the proposed methods