Three-Phase Buck-Boost Split-Source Inverter With Improved Bus Utilization

Split source inverters (SSIs) have gained attention as potential alternatives to conventional two-stage systems in applications that require integrating a dc source into an inverter powertrain via a step-up operation such as in fuel cell-powered systems. By incorporating the voltage boost functionality directly into the inverter, SSIs eliminate the additional dc–dc stage which typically consists of semiconductor devices subjected to high current and/or voltage stresses. However, the conventional variant of the topology suffers from poor utilization of the dc-bus voltage and constraints over the dc voltage gain limiting its use in various applications. In this work, a novel variant of the converter $-$ buck-boost split source inverter (BSI), is introduced which improves the dc-bus utilization by modifying the conventional circuitry and enables control of power injection from multiple dc sources. Furthermore, the modification provides an extra degree of freedom allowing a larger variation of the voltage gain, which can be beneficial in applications requiring different voltage levels (e.g., with different fuel cell types). In this study, the operation of the topology is analyzed, and suitable modulation methods for the converter are developed analytically and validated through PLECS simulations. Finally, a SiC-based experimental prototype is designed and tested to validate the performance of the proposed converter.