Novel Pulse-width Modulation Strategy to Minimize the Switching Losses of Z-Source Inverters

This article proposes a novel pulse-width modulation strategy to minimize switching losses of the Z-source inverter. The Z-source inverter has different pulse-width modulation patterns unlike the conventional voltage source inverter. Shoot-through states have been inserted within the zero states of the traditional pulse-width modulation patterns of a voltage source inverter to boost DC input voltage. Thus, the Z-source inverter has six active states, two zero states, and additional shoot-through states differentiating the Z-source and conventional voltage source inverters. The currents flowing through the switches of the Z-source inverter are larger than those of the conventional voltage source inverter, because Z-network currents must flow through the switches during the shoot-through states. Therefore, shoot-through currents increase the total switching losses of the Z-source inverter. In this article, switching losses of the Z-source inverter with the existing pulse-width modulation strategy are analyzed in detail. Then, new modulation signals of the Z-source inverter are introduced to produce unique pulse-width modulation patterns that minimize the switching losses of the Z-source inverter. The switching losses of the Z-source inverter with both pulse-width modulation strategies are simulated and compared. In addition, an experimental system has been built and tested to verify the effectiveness of the proposed strategy.