Adaptive shoot-through duty ratio control methodology of stand-alone quasi Z-source inverter

Abstract

This paper presents an adaptive shoot-through duty ratio control methodology for a stand-alone three-phase quasi-Z-source inverter (qZSI). In practice, variable active and reactive load powers must be met by a qZSI-based stand-alone system. In this context, existing shoot-through control schemes for qZSI adjust the capacitor voltage or DC-link voltage at a fixed reference value. This causes extra voltage stresses on switches, high distortions, and an operating range reduction of the power inverter under variable load demands. On the contrary, the proposed shoot-through control scheme adjusts the shoot-through duty ratio adaptively based on load voltage feedback to improve performances. In this logic, the controllable shoot-through duty ratio facilitates various improved features in comparison to conventional schemes under load power variations. These features include reduced voltage stress across the switches, reduced distortions, and an extended operating range. The suggested proportional-integral (PI)-based scheme has a single control loop with a single measured quantity, i.e., sensing of load voltage only. The proposed concept has been verified via both simulation and experimental studies.