Quasi Z-source Inverter Topology Research Articles

Hybrid PV-Wind, Micro-Grid Development Using Quasi-Z-Source Inverter Modeling and Control—Experimental Investigation

This research work deals with the modeling and control of a hybrid photovoltaic (PV)-Wind micro-grid using Quasi Z-source inverter (QZsi). This inverter has major benefits as it provides better buck/boost characteristics, can regulate the phase angle output, has less harmonic contents, does not require the filter and has high power performance characteristics over the conventional inverter. A single ended primary inductance converter (SEPIC) module used as DC-DC switched power apparatus is employed for maximum power point tracking (MPPT) functions which provide high voltage gain throughout the process. Moreover, a modified power ratio variable step (MPRVS) based perturb & observe (P&O) method has been proposed, as part of the PV MPPT action, which forces the operating point close to the maximum power point (MPP). The proposed controller effectively correlates with the hybrid PV, Wind and battery system and provides integration of distributed generation (DG) with loads under varying operating conditions. The proposed standalone micro grid system is applicable specifically in rural places. The dSPACE real-time hardware platform has been employed to test the proposed micro grid system under varying wind speed, solar irradiation, load cutting and removing conditions etc. The experimental results based on a real-time digital platform, under dynamic conditions, justify the performance of a hybrid PV-Wind micro-grid with Quasi Z-Source inverter topology.

Soft-switched quasi-Z-source inverter-fed permanent magnet synchronous machine for hybrid/electric vehicle applications

The switching frequency of power converters is increasingly high to reduce the size of passive elements and improve the dynamic performance of electric power-train in hybrid/electric vehicle applications. Thus, the development of soft-switching technology devices has taken an accelerated pace. This paper introduces a novel soft switching bidirectional quasi-Z-source inverter (QZSI). By using a resonant capacitor and coupled inductors, the proposed QZSI topology provides a solution to hard-switching problems for variable speed electric drives for hybrid/electric vehicle applications. A soft switching topology is presented, which aims at reducing active devices switching stresses as well as mastering the slew rate dv/dt that have an adverse effect over the motor/generator windings. The effectiveness of the proposed topology has been analytically studied and simulated in Matlab/Simulink and the results have been validated by experiment for both propulsion (motoring) and braking (generating) modes on the laboratory test bench.