Impedance-source inverters with coupled inductors can provide much higher voltage gains, but occasionally at the expense of discontinuous input currents and large voltage spikes at their dc-links. The former is caused by the absence of inductances at their inputs, while the latter is due to unintentional interruptions of leakage currents through their coupled inductors. These problems have now been solved here by a new family of dual-winding impedance-source inverters (DW-ISIs). Each DW-ISI can recycle the leakage energy from its two windings to a few clamping capacitors, which in turn help prevent the voltage spikes. This, together with the presence of an inductance for smoothing its input current, renders the family of DW-ISIs to be highly effective, while not compromising the voltage and current stresses when compared with other precedent inverters. In addition, to simplify the circuit analysis, a reactive component elimination method has been proposed in this article. Simulation and experimental results have confirmed the validity of the proposed topologies.

Traditional ways of applying ampere-second and volt-second balances have commonly been adopted for calculating state variables of a converter. However, it becomes tedious and error prone when using complicated topologies having many inductors and capacitors. Therefore, to simplify the circuit analysis, a reactive component elimination method has been proposed in this letter to be applied for all converter topologies. To demonstrate the method, current and voltage stresses of a coupled-inductor impedance-source inverter have been determined using both the traditional and the proposed methods. Their subsequent comparison confirms the effectiveness of the proposed method.

Coupled-inductor-based impedance-source inverters have been suggested as a solution for improving the voltage boost capability. However, large voltage spikes can sometimes appear across the switch bridge if the leakage inductance of the coupled inductor cannot be nullified. Higher voltage-rated switches are, therefore, necessary for implementing each inverter with generally lower efficiency anticipated. To solve the above issues, this article proposes a high-efficiency T-source inverter (HE-TSI) with leakage energy recycled through several passive elements and, hence, avoided voltage spikes across the switch bridge. To reveal the prominent characteristics of the HE-TSI, it has been compared with the traditional T-source inverter in the terms of extents of voltage spikes across the switch bridge, voltage stresses, current stresses, and efficiency. The simulation and experimental results have verified the validity of the proposed HE-TSI.

The original Y-source inverter applies a three-winding coupled inductor to obtain a high voltage gain. However, the leakage inductances of the coupled inductors have also been introduced to the circuit, which can cause great voltage spikes at dc-link and reduce the efficiency. This paper proposed a modified Y-source inverter to overcome the issues brought by the leakage inductances. It inherits all the advantages of the Y-source inverter. In addition, the proposed topology has the ability to provide a higher boost ratio and continuous input current, thus enlarging its application area. The great features of the proposed inverter have been proven through the experiments in this paper.

In this paper, many impedance-source inverters with coupled inductors have been investigated to obtain a high step-up boost ratio. However, the leakage inductors in these topologies induce great voltage spikes at the dc link, which will increase the voltage stress of switches. Thus, the power level of inverters is limited. Furthermore, the efficiency of the inverters can be degraded by the losses associated with leakage inductors. To address abovementioned issues, this paper proposes a family of low-spike high-efficiency Y-source inverters. The proposed inverters have the ability of eliminating voltage spikes at the dc link and recycling the leakage energy via the additional diode and capacitor. In order to show the excellent characteristics of the proposed topologies, this paper compares the performances of the proposed inverters and the improved-Y-source inverter in many aspects. Simulation and experimental results have verified the abilities of the proposed inverters.

The Y-source inverter uses different turns ratios of a coupled inductor and a controllable duty ratio to vary its gain. However, its input current is discontinuous, and any leakage inductances of its coupled inductor will lead to unintentional dc-link voltage spikes and gain reduction. To solve these problems, an extended quasi-Y-source inverter has been proposed in this study, which compared with the Y-source inverter, uses an extra inductor and an extra capacitor. Although the extras may not appear attractive, they have successfully helped with the suppression of leakage effects, which decrease the voltage spikes, and hence permit the main magnetic core size to be much smaller. Concurrently, the continuous input current can be also achieved. Besides, inrush current at startup has been reduced to a more acceptable value, which together with other features of the proposed inverter, have been proven through experiments.