Model and Control of Integrated Six-switch Buck-Boost and CLLLC Cascaded Converter

An integrated six-switch Buck-Boost and CLLLC cascaded converter (ISSBB-CLLLC) is proposed in this paper, which is suitable for high-voltage applications. To realize the flying capacitor voltage balance, current ripple optimization and output voltage regulation, a model of the converter is established, and a control strategy is proposed. Firstly, the balance of flying capacitor voltage in six-switch Buck-Boost circuit is analyzed, and a voltage balance control method (FCV-BCM) is proposed, which is implemented by alternatively using the redundant switching states. Next, a model of the ISSBB-CLLLC is derived and a dual closed-loop control based on phase shift control (DLC-PSC) is proposed to regulate the output voltage, which can further optimize the current ripple of inductor in six-switch Buck-Boost circuit as well. Finally, the experimental results are given to verify the effectiveness of the control strategies.