Design and Control of Modified Capacitor Assisted Extended Boost Quasi-Z Source Multilevel Inverter /

Abstract

Due to increase demand of renewable and clean energy integration, the need of inverters and their control is increasing. Traditional inverters have a drawback because of the introduction of dead time in the switches to avoid damaging the inverters. Z source inverters (ZSI) were introduced to counter this drawback and has an additional advantage of boosting voltage at the input of inverter. The 7 level 18 switch inverter is implemented for its relatively lower number of levels and switches for three phase operation. The inverter is modulated using a fast SVPWM algorithm which utilizes a new transformation i.e., dq-gh. The transformation greatly reduces the steps required for calculating the duty cycles and thus lowers the requirements for the computational power of the modulator. For a stable and reliable integration of these clean energy sources requires a controller to regulate the system parameters. Various control techniques are already been deployed such as classical, intelligent, and robust controllers etc. In this research work, a novel reaching-law based sliding-mode controller (SMC) is designed. The control law is derived based upon equivalent control and a novel reaching law. The existence condition for the derived control law has been proved. The proportional integral (PI) controller is also applied for the proposed topology and the performance is then compared with the proposed controller. Various test scenarios are developed to evaluate both controllers. It can be seen from the results that SMC performs better than PI controller in all test scenarios. Furthermore, the SMC controller is verified by using hardware-in-loop (HIL) setup.