Modulation Strategy for Cascaded DC/DC Converter through Integration of CLLLC and Six-Switch Buck-Boost Topology

This paper proposes a cascaded DC/DC converter which integrates the six-switch Buck-Boost circuit with CLLLC converter by sharing a bridge arm and shows advantages of bidirectional energy flow, high voltage rating, high efficiency and wide input voltage range. First, an alternative PWM strategy (APWM) for the six-switch Buck-Boost circuit is proposed to balance its flying capacitor voltage. Next, a control method for both current ripple optimization and power control (CRO-PC) is proposed which can reduce 73.5% of current ripple. Finally, a 2 kW/ 20 kHz prototype was built to demonstrate the performance of the proposed method.