A Novel Three-Phase Seven-Level Hybrid Flying-Capacitor Inverter

Abstract

In this paper, a novel three-phase seven-level hybrid flying-capacitor (7L-HFC) inverter topology is proposed, which stems from the five-level hybrid flying capacitor (5L-HFC) and the six-level hybrid flying-capacitor (6L-HFC) inverters. Although the proposed 7L-HFC inverter has the same structure with 5L-HFC and 6L-HFC, the THD of line-to-line voltage is reduced at the full range of the modulation indices. Moreover, the total voltage stress of IGBTs is also reduced in the proposed 7L-HFC inverter. In addition, the proposed topology has much lower number of devices than the conventional seven-level diode-clamped inverter (7L-DCI) and flying capacitor inverter (7L-FCI). Furthermore, the power losses of the proposed topology are lower than that of the 5L-HFC, 6L-HFC and 7L-DCI at medium and high modulation indices. The performance of the proposed 7L-HFC inverter has been verified through simulation results.