An H8 Current-Source Inverter Using Single-Gate WBG Bidirectional Switches

Due to the high forward voltage drop of reverse-blocking (RB) switches, conventional current-source inverters (CSIs) typically suffer efficiency penalties. Bidirectional (BD) switches, on the other hand, can also block reverse voltages but with less conduction loss than RB switches, making them more attractive candidates for CSI switches. This article discusses the difficulties inherent in implementing BD switches in CSIs, such as dc-link overvoltage, interphase short circuit, more complicated commutation schemes, high body diode conduction loss, and additional gate control signals. To address these issues, a new CSI topology (H8-CSI-BD) is proposed, which is optimized for the use of single-gate wide bandgap (WBG) BD switches. The proposed topology and its modulation scheme guarantee safe operation of CSI, eliminate BD switch’s body diode conduction loss, and achieve significant efficiency improvement. In addition, its requirement for single-gate control signals for its BD switches simplifies control and gate drive circuits noticeably. The advantages of the H8-CSI-BD topology over the other CSIs using either RB or BD switches are confirmed by analysis, simulation, and experimental results.