A Novel Single Capacitor-Based T-Type Bidirectional Converter with Buck-Boost Capabilities

This paper introduces a novel bidirectional switched-capacitor converter topology with buck-boost capabilities. Unlike traditional T-type inverters that use two capacitors, the proposed topology utilizes only a single capacitor, reducing the number of capacitors by 50%. Normal, buck, and boost modes make the topology versatile for various applications. It can be used as a three-phase two-level or three-level inverter in all modes. A switched capacitor unit boosts the input voltage without requiring boost inductors or filter capacitors. This not only increases the DC link voltage but also boosts the power throughput without an increase in current which is a significant advantage in power electronics. The proposed topology controls switched capacitor unit inrush current with a soft-starting circuit. The buck mode operation is achieved by connecting a capacitor whose voltage is maintained at half the DC link voltage, resulting in a superior output voltage quality with reduced total harmonic distortion. In addition, a novel switching strategy maintains capacitor voltage balance during buckand boost modes along with the suppression of inrush current during steady state and improves DC link voltage stability. The proposed topology is compared to conventional and recent works in terms of device count. Finally, the proposed concept is validated experimentally and the results are found to be promising