Efficient Modulation Strategies to Minimize Switching Losses in Dual-Inverter Systems

The dual-inverter (DI) with galvanically isolated dc supplies offers advantages such as multilevel and fault-tolerant operation, superior dc voltage utilization, and simple control, making it particularly attractive for traction applications. The DI provides significant flexibility in output voltage synthesis by utilizing two conventional voltage-source inverters (VSIs) to supply each end of the load. This article leverages that flexibility by proposing several modulation strategies, where one inverter operates in a six-step (square-wave) mode, and the other utilizes a modified space vector pulse width modulation (SVPWM) or discontinuous pulse width modulation (DPWM). These strategies efficiently reduce switching losses while maintaining low implementation complexity through the reference signal deformation approach. The proposed modulations are theoretically analyzed for switching loss reduction and experimentally validated on an induction machine under closed-loop field-oriented control to confirm their effectiveness compared to conventional approaches.