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In this article, a quasi-resonant bridgeless power factor correction (PFC) converter is presented. Aiming to improve the input current total harmonic distortion, a single auxiliary switch with low voltage stress than the similar counterparts is employed. Due to resonant operation, the size and value of the passive components are reduced and maximum voltage gain of four is achieved which is higher than that of conventional buck PFC converter. Also, soft switching condition for the main semiconductor elements is realized from 20% of nominal power to full load and entire input voltage range (90 to 130 Vrms) without employing any extra component. The operating modes are explained and the theoretical analysis is discussed in details. A straightforward design procedure for the proposed converter is presented. A 200 W, 160 kHz laboratory prototype is implemented to verify the theoretical analysis and the effectiveness of the proposed topology. [ABSTRACT FROM AUTHOR]

A nonisolated bidirectional dc–dc converter with high voltage gain, low voltage stress, low component count, and soft-switching features is presented in this paper. In this topology, coupled inductors and voltage multiplier cells are merged to achieve high step-up/down voltage gain. Also, due to using active clamp circuits, the voltage stress of power switches is relatively low. Thus, the low voltage switches with low on-resistance can be employed to reduce the conduction losses. Furthermore, zero-voltage switching is accomplished in both high step-up and high step-down modes for all power switches, and due to zero-current switching operation of all antiparallel diodes, the reverse recovery losses are reduced. In order to verify the theoretical analysis and the converter performance, a 200 W prototype circuit of the proposed converter is implemented in the laboratory. [ABSTRACT FROM AUTHOR]

This paper proposes a soft switching nonisolated dc/dc interleaved converter incorporating coupled inductors and switched capacitors for high step-up applications. The converter integrates the interleaved structure and winding-cross-coupled inductors technique to reduce current stress of semiconductor devices and diminish the input current ripple considerably. In addition, the interleaved converter has the automatic current sharing characteristic. The applied zero voltage transition cell provides soft switching in a wide range of load variations with a minimum number of elements. In this topology, all semiconductor devices are soft switched, having eliminated switching losses and alleviating the reverse recovery problem of the output diodes. In addition, the voltage stress across the switches is very low. The theoretical analysis and design procedure of the introduced topology are presented. Also, the proposed converter is compared to the latest similar soft switched high step-up converters. The accuracy of the theoretical analysis is validated by a 200-W prototype operating at 100 kHz. [ABSTRACT FROM PUBLISHER]

This study introduces a soft-switching non-isolated bidirectional DC-DC converter with high voltage conversion ratio and low voltage stress across semiconductor devices. The presented topology is well suited for high step-up/step-down applications. By integrating coupled inductors and switched capacitors techniques, a high step-up/step-down voltage gain is achieved. Active clamp circuits are employed in both high step-up and high step-down operating states to recycle the leakage inductance energy and realise zero-voltage-switching condition for all switches to mitigate the switching losses and improve efficiency. Also, the reverse recovery problem of the body diodes is completely alleviated owing to zero-current-switching performance. The operation principles and theoretical analysis of proposed converter are presented in details. Finally, the experimental results of a 200 W prototype circuit are provided to confirm the validity of the proposed topology. [ABSTRACT FROM AUTHOR]

A new interleaved high step-up DC–DC converter is presented in this study which integrates coupled inductors and voltage multipliers techniques into interleaved structure to provide high voltage gain without extreme duty cycle. The voltage stress across power metal–oxide–semiconductor field-effect transistors is very low, so low voltage rating switches with lower Rds(on) can be used. A modified version of winding cross-coupled inductors technique is employed to minimise the input current ripple, and also the reverse recovery problem of the output diodes is alleviated because of the leakage inductance of the coupled inductors. Also, the leakage energy is absorbed and recycled to the output by the passive clamp scheme. In addition, automatic current sharing performance between the interleaved phases is established without any extra circuit. The operating principles of the proposed converter are explained and the theoretical analysis is provided, and in order to verify the effectiveness of the proposed converter, a 170 W, 30-360 V laboratory prototype is implemented. [ABSTRACT FROM AUTHOR]

In this study, a novel soft-switched high step-up DC/DC converter is presented. This converter is suitable to be employed in photovoltaic and fuel cell systems. The proposed topology is based on coupled inductors and switchedcapacitor techniques to provide high step-up gain. Also, due to high conversion ratio, and symmetrical structure of the proposed topology, the voltage stress of semiconductor elements is low; therefore, high performance metal-oxide- semiconductor field-effect transistors with low ON-resistance, and also low-voltage rating diodes can be utilised to reduce the circuit cost, conduction, and reverse-recovery losses which improve the converter efficiency and power density. Furthermore, by adopting an active clamp circuit, the stored energy in the leakage inductance of coupled inductors is recycled and zero-voltage-switching turn-on condition for both main and clamp switches are provided. Operating principle and steady-state analysis of the converter are discussed in detail. Finally, an experimental prototype of the proposed converter with 200W output power is implemented which verifies the theoretical analysis. [ABSTRACT FROM AUTHOR]