A new synchronous rectifier (SR) gate drive circuit is presented in this study. The proposed SR driver generates the driving signal according to the SR voltage polarity without using any external control signal. Also, it can turn off the SR with delay and keeps the SR on after its drain source voltage becomes positive. In addition, this driver recovers part of the driving energy in a resonant manner. The proposed SR driving circuit is suitable for some zero voltage transition (ZVT) synchronous buck converters. It can also be used for some high-frequency resonant converters and high-frequency discontinuous conduction mode pulse-width modulation circuits. In this study, the proposed driver is applied to a ZVT synchronous buck converter and the presented experimental results confirm the theoretical analysis.

This paper deals with the optimization of the driving techniques for the ZVT synchronous buck converter proposed in [1]. Two new gate drive circuits are proposed to allow this converter to operate by only one control signal as a 12V voltage regulator module (VRM). Voltage-driven method is applied for the synchronous rectifier. In addition, the control signal drives the main and auxiliary switches by one driving circuit. Both of the circuits are supplied by the input voltage. As a result, no supply voltage is required. This approach decreases both the complexity and cost in converter hardware implementation and is suitable for practical applications. In addition, the proposed SR driving scheme can also be used for many high frequency resonant converters and some high frequency discontinuous current mode PWM circuits. The ZVT synchronous buck converter with new gate drive circuits is analyzed and the presented experimental results confirm the theoretical analysis.

In this study, a new zero voltage switching (ZVS) synchronous buck converter with ultra-high step-down conversion ratio is introduced. By combining coupled inductors and energy-transferring capacitors, operating duty cycle is significantly extended while the voltage stress across the switches is reduced. Thereby, extremely low voltage gain can be achieved and the conduction loss is reduced owing to using switches with lower voltage rating. Also, by applying the interleaved method and complementary pulses for switches, the current stress and the output current ripple are reduced. In the proposed converter, soft switching condition is achieved for all switches without any auxiliary circuit. As a result, the overall efficiency of the introduced converter is improved. The converter operation and its design considerations are discussed. Experimental results are presented to validate the theoretical analysis.

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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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This paper introduces a new high step down four-phase converter with soft switching and automatic uniform current sharing. The phase number of the introduced topology can be expanded. In this converter, the main switches are turned on under zero voltage zero current switching condition and turned off under zero voltage switching. Also, the auxiliary switches and diodes operate respectively under zero voltage switching and zero current switching conditions. In the proposed architecture, the duty cycle is extended and the semiconductors voltage stress is reduced by applying series capacitors and coupled inductors. The leakage energy associated with the coupled inductors is absorbed and the reverse recovery losses of diodes are eliminated. Uniform current sharing between four phases is achieved without any extra current sharing control circuit. Furthermore, by utilizing the interleaved method, the current stress and the output current ripple are reduced. This converter provides above advantages while its input and output grounds are connected. As a result, the introduced topology can provide high step down conversions at high frequencies. The converter operation and its characteristics are analysed in detail. The accuracy of the theoretical analysis is verified by a laboratory prototype.

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