A new soft‐switching multi‐input quasi‐Z‐source converter for hybrid sources systems

Abstract

This study focuses on a zero voltage transition multi-input quasi-Z-source converter (qZSC). This topology can be used for input sources with different voltages and currents to provide a constant output voltage. In the proposed structure, several qZSCs are combined and the output filter of all stages is eliminated. Therefore, the overall number of circuit elements, cost, volume and weight are reduced in comparison with when they are in a separate operation. In this converter, the soft-switching conditions are provided for all stages by using only one auxiliary circuit. The employed technique provides zero-voltage zero-current switching (ZVZCS) and zero-voltage switching for main switches at turnon and turn-off instants, respectively. The auxiliary switch turns on under zero-current switching and turns off under ZVZCS. Furthermore, the reverse recovery losses of diodes are reduced. The theoretical foundation of the proposed converter is presented and its performance is simulated by OrCAD software. The obtained results show 3.5% improvement in the efficiency at nominal loads, compared to its hard-switching counterpart. A dual-input prototype of the proposed structure is successfully built to support the validity of the theoretical analysis. 1Recently, the fuel crisis, global warming and environmental pollution are major factors in shifting to renewable energy sources. Moreover, the Kyoto Protocol promotes us to use clean energies including fuel cell, photovoltaic (PV), wind energy, and so forth. The most important capability of PV and wind energy sources is to serve the energy demand, even in distant or out of grid places and in densely populated areas [1].Renewable energy sources deliver various power in different environmental conditions such as different seasons and climates. Thereby, concurrent use of two or more energy sources is essential. In order to provide regulated voltage from several energy sources, different multi-input topologies have been proposed in recent years. In the multi-input converters (MICs), the number of passive elements and the current stress of semiconductors are reduced. High flexibility as well as better management in energy sources are other benefits of using MICs [2,3].The boost converter is used conventionally in the renewable energy section due to the continuous input current in This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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“…Coupled inductor based soft‐switching cells are implemented in this converter in order to reduce power loss. Multi‐port quasi‐Z‐source converter (qZSC) is discussed in literature, [112]. The proposed converter discussed in this literature uses only one auxiliary switch in order to facilitate soft‐switching technique.…”

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“…In Table 10, the proposed converter is compared to different multi-port converters in terms of total number of semiconductor switches, number of ports, and supported modes (with assumption that the converters can be modified to fit our application). In comparison to [4,10,[24][25][26][27][28], the proposed converter is the only isolated converter that can achieve all six described modes of operation. The converters described in [26,27] are non-isolated converters that are highly undesirable in a hybrid aircraft application, where safety is of utmost importance.…”

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