The Z‐source inverter is one of the most interesting power electronic converters. Over the past decades, research and development have been in high demand to meet the challenges for improving the converter performance with reduced weight and cost while having high efficiency along with high gain or boost factor. Since the inception, tons of resolutions, customizations, and improvements have appeared to achieve these performance goals. To overcome the most common drawback, i.e. the low boost factor of classical Z‐source inverters, the switched inductor/capacitor and switched boost Z‐source inverter topologies have become predominant in the recent epoch. Furthermore, the higher component voltage stress, discontinuous input current, and high inrush start‐up current issues have also been addressed and solved in various literature as part of this topical advancement. In this study, a comprehensive review of various switched impedance network‐based Z‐source inverter topologies has been accomplished for providing a quick report to researchers and engineers so that they can consider this as a one‐stop solution for selecting inverters from this group. The overall study covers the methodology, features, and relevant important results of the latest switched Z‐source inverter models in order to demonstrate the coordination between pitfalls and improvements.

In this paper, the performance of a new Z-source inverter (ZSI)-based single-stage power conditioning system (PCS) is analyzed for a standalone photovoltaic (PV) power generation system. The proposed ZSI-based PCS includes two main parts: one is the input from PV units and the other is the ZSI. In this work, a new topology, termed the switched inductor-assisted strong boost ZSI (SL-SBZSI), is introduced for improving the performance of the PCS. The proposed topology shows high boosting capability during the voltage sag in PV units due to variations in solar irradiation and temperature. Another key advantage is the reduced capacitor voltage stress and semiconductor switch voltage stress of the inverter bridge, which ultimately minimizes the size and cost of the single-stage PCS. The proposed ZSI topology falls under the doubly grounded category of inverter by sharing the common ground between the input and output. This is an additional feature that can minimize the leakage current of PV units at the ac output end. The operational principles, detailed mathematical modeling, and characteristics of the proposed SL-SBZSI for a standalone photovoltaic (PV) power generation system is presented in this paper for analyzing performance. The simulation results, which are performed in MATLAB/Simulink, demonstrate the improved performance of the proposed SL-SBZSI for the standalone PV system. The performance of the proposed topology is also evaluated through an experimental validation on a laboratory-based PV system. the world was around 90 GW in 2012 and the target amount is estimated as approximately 350 GW by the end of 2020. Evidently, PV energy is one of the most promising sources for mitigating future load demands.Generally, PV energy is received from sun, and its extraction involves a large installation cost. The basic cost of this system relies on the photovoltaic panels and the interfacing power electronic converter that couples the source with the load. This part is commonly known as the power conditioning system (PCS). Figure 1 represents the traditional boost converter-based dual-stage and the Z-source inverter (ZSI)-based single-stage PCS. The main function of the PCS is to convert the output DC voltage of the PV unit into 50/60 Hz AC voltage suitable for households and grid applications. Traditionally, a voltage source inverter (VSI) with a DC-DC boost converter comprising the dual-stage PCS is used to convert the DC output power into AC power [7]. This additional DC-DC boost converter increases the size and cost of the PV power generation system. A ZSI for PV systems as presented in [8] obsoletes the additional boost converter with its distinct impedance network. Due to its shoot-through characteristics, the ZSI-based PCS can boost the input voltage of the PV system during voltage fluctuations due to changes in solar irradiation and environmental temperature. Although the ZSI turns the dual-stage traditional system into a single-stage system, it inherits some certain drawbacks regarding its performance, such as...

This paper aims to develop a new switched inductor assisted strong boost Z-source inverter (SL-SBZSI) topology with high voltage gain and analyze the steady-state characteristics of the proposed topology. In the proposed topology, two switched inductors are used within the series impedance structure of the Z-source inverter (ZSI) in order to achieve the high voltage gain. The steady-state characteristics of the proposed topology are analyzed to disseminate its several advantages as compared to traditional ZSIs. The key advantages include the higher boost factor with lower shoot-through duty ratio and lower voltage stresses on capacitors as well as on switches of the inverter bridge. Furthermore, the proposed topology has the soft-start ability which significantly reduces the inrush start-up current while comparing with the traditional ZSI. In the proposed topology, a common ground is shared between the output AC voltage and the input DC voltage source which categorizes this topology to the doubly grounded inverter. The characteristics of the proposed SL-SBZSI are analyzed by considering two operating condition where the simple boost pulse width modulation (PWM) scheme is used to extract the shoot-through pulses. The characteristics of the proposed topology are also compared with different existing topologies along with the conventional modified capacitor assisted Z-source inverter (MCA-ZSI), whose boost factor is much closer to the proposed topology. Rigorous mathematical analyses are presented to clearly demonstrate the benefits of the proposed topology while simulation studies are carried out to demonstrate its distinct features as compared to the existing topology. Finally, experimental studies are conducted to further validate the theoretical and simulation results.

This paper introduces an improved quadratic DC-DC boost converter to provide an ultra-high level voltage gain with the switched-capacitor cell based structure. The proposed converter has the ability to excel the output voltage gain to the ultra-high level without any voltage doubler circuit. Hence, the total number of components is less compared to the conventional topologies. The proposed converter offers reduced voltage stress on the capacitors, diodes, and semiconductor switches while generating a high voltage gain effect with a low duty cycle. In addition, the continuous source current (CSC) and input-to-output side ground-sharing features are also available for renewable energy applications. The steady-state and comparative performance analysis with similar topologies and power loss calculations are presented in this paper. Furthermore, the simulation results extracted from the Matlab/Simulink are compared and analyzed with the conventional topology. Finally, the experiments are carried out by designing a 150 W laboratory prototype where the peak efficiency is found 90% while delivering 80 W power to the load side.INDEX TERMS DC-DC converter, high voltage gain, non-isolated, voltage stress, quadratic boost converter.

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