Modified multilevel buck-boost converter with equal voltage across each capacitor: Analysis and experimental investigations

Abstract

Recently, the circuitry of Multilevel Buck-Boost Converter (here, called MBBC1) is suggested in the literature to attain high inverting voltage by increasing the output levels of the classical buck-boost converter. However, the only circuitry is suggested and detail investigations are not provided. The major drawbacks of MBBC1 are the voltages across the load capacitors side are unequal and the input current is not continuous. Therefore, the MBBC1 is not well suited to feed multilevel inverter where a stack of capacitors is required with equal voltage across each capacitor. A new modified MBBC called MBBC2 is proposed to achieve continuous input current and equal voltage across each capacitor. The circuitry of MBBC1 and MBBC2 configurations are analysed with non-idealities to investigate its effects on the voltage conversion ratio. The Continuous Conduction Mode (CCM) and Discontinuous Conduction Mode (DCM) boundary conditions and modes of operation for MBBC1 and MBBC2 configurations are presented. The procedure for basics design and components selection is elaborated. Additionally, comparison of MBBC1, MBBC2 and recently proposed a non-isolated DC-DC configuration is provided. The performances of MBBC1 and MBBC2 configurations are tested with simulation and experimental work, and obtained results consistently show a good agreement with the theoretical approach. - The Institution of Engineering and Technology 2019.