An Extend Control Algorithm in PV-ZSI Capacitor-Assisted with Shoot-Through Allowable Boundary on Different Load Cases

Abstract

This paper proposed an extend controller on Capacitor Voltage Control (CVC) for Z-Source Inverter (ZSI) network when it been applied at the PV generation. The improved controller is been combined with the existing MPPT algorithm. Although, the existing CVC has some drawback as it produces an unnecessary shoot through signal period which cause the capacitor voltage at ZSI cannot be constantly maintained. Therefore, the modification has been included a deviation of the duty cycle of the shoot through. It is to enhance the existing CVC performance and to increase the efficiency of the whole PV generation whenever the input PV irradiation is changed. At the same time, it is also able to maintain a constant dc-link voltage at ZSI. This proposed control algorithm has been verified throughout simulations tests using linear and non-linear loads by observing the constant dc-link capacitor voltage. This proposed controller has also been compared with the existing conventional CVC with the same load conditions. At the end, the improved controller has shown the ability to maintain the dc-link inverter at PV generation and to limit the allowable boundary of the capacitor voltage to not overflow from the rated value. In terms of quality at the output the proposed controller is able to reduce the total harmonic distortion at the load connections.