A Split-Inductor Flying Capacitor Converter for Medium-Voltage Application

This article presents a split-inductor flying capacitor (SIFC) converter for medium-voltage applications to improve reliability and eliminate the shoot-through issue. Reliability and lower total harmonic distortion (THD), mainly caused by the pulsewidth modulation (PWM) dead time, are the vital aspects while designing higher power density converters. The dead time in the PWM can be reduced/removed in the proposed converter. This will increase the voltage/current gain and enhance the quality of the voltage/current waveforms even at lower modulation index and light loads than the traditional flying capacitor (FC) and neutral point clamped (NPC) converters. Furthermore, an improved phase-shifted PWM (IPS-PWM) is used to maintain the flying capacitor’s nominal reference voltage. A comparison is made between SIFC and five different existing multilevel topologies. The proposed converter has higher voltage/current gain, lower THD over conventional FC and NPC converters, and higher efficiency than the other three topologies. Finally, the SIFC converter’s robustness with IPS-PWM is validated using experimental results in different operating conditions such as sudden load changes, modulation index, output frequency, and power factor (unity, lagging, and leading).