Operation Modes and Characteristics of the Z-Source Inverter With Small Inductance or Low Power Factor

The Z-source inverter, utilizing a unique LC network and previously forbidden shoot-through states, provides unique features, such as the ability to buck and boost voltage with a simple single-stage structure. The analysis and control methods provided in the literature are based on an assumption that the inductor current is relatively large, continuous, and has small ripple. This assumption becomes invalid when the load power factor is low or the inductance is small in order to minimize the inductor's size and weight for some applications where volume and weight are crucial. Under these conditions, the inductor current has high ripple or even becomes discontinuous. As a result, the Z-source inverter exhibits new operation modes that have not been discussed before. This paper analyzes these new operation modes and the associated circuit characteristics.