A Pulsewidth Modulation Technique for High-Voltage Gain Operation of Three-Phase Z-Source Inverters

Z-source inverter (ZSI) was recently proposed as a single-stage buck-boost dc-ac power conversion topology. It augments voltage boost capability to the typical voltage buck operation of the conventional voltage source inverter with enhanced reliability. However, its boosting capability could be limited; therefore, it may not suit applications requiring a high-voltage boosting gain. To enhance the boosting capability, this paper proposes a new pulsewidth modulation (PWM) technique to control the generation of the shoot-through intervals in three-phase ZSIs. The proposed modulation technique achieves a reliable high-voltage gain operation without adding any extra hardware to the ZSI structure, which preserves its single-stage buck-boost conversion nature. In this paper, the principle of the proposed modulation technique is analyzed in detail, and the comparison of the ZSI performance under the conventional and the proposed PWM techniques is given. The simulation and experimental results are shown to verify the analysis of the proposed concept.