A Modulation Scheme to Reduce Leakage Current of Split-Capacitor Four-Wire Current Source Inverter

The transformer-less split-capacitor four-wire current source inverter is effective to reduce leakage current, but its effect is closely related to the impedance of the neutral wire and common mode voltage. The leakage current can be almost eliminated when the impedance of the neutral wire is zero, but the zero impedance condition does not hold in practice. To further suppress the leakage current, a new carrier-based modulation scheme with reduced common mode (CM) voltage is proposed in this article. The resulting CM voltage (peak-to-peak) is half that of the conventional modulation scheme. Moreover, the conducted interference is also effectively reduced. The experimental results validate the effectiveness of the proposed modulation scheme.