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This article proposes a novel interleaved three-phase pulsewidth modulation (PWM) single-stage resonant ac–dc converter with high-frequency isolation. The proposed converter comes from an interleaved three-phase power factor correction (PFC) semistage and a three-phase LLC resonant dc–dc semistage. Soft-switching commutation can be achieved on the power switches in this converter including zero-voltage-switching-on on the primary side power switches and zero-current-switching-off on the secondary diodes. The LLC resonant tank in the dc–dc semistage serves as a bandpass filter that attenuates the line-frequency ripple and keeps the switching frequency component passing through the transformer. The high frequency transformer keeps in a small size. Steady-state analysis of the resonant dc–dc semistage for PWM control is proposed to analyze the dc-link voltage stress. Moreover, the dc-link capacitor value can be greatly reduced without affecting the PFC operation. A prototype that converts a wide three-phase input voltage to 300 V dc output voltage is built and tested. The experimental results present an almost unity power factor with a conversion efficiency as high as 96.3% with total harmonic distortion as low as 3.86% at a full-load condition. [ABSTRACT FROM AUTHOR]

This paper proposes a family of magnetic coupling nonisolated bidirectional dc–dc converters, which can achieve soft-switching operation in both power flow directions with a simple auxiliary circuit. Compared with conventional zero-voltage-transition converters, the additional resonant inductor is eliminated and magnetic core number is reduced. Therefore, both high efficiency and low cost are achieved. First, a general zero-voltage-switching (ZVS) magnetic coupling structure is proposed for a bidirectional buck/boost converter, based on which 13 different ZVS topologies with different connections of auxiliary circuit are derived. It is very beneficial in practical industrial applications because engineers can choose an optimal one according to converter performance characteristics, and the topology derivation methodology can be easily extended to other bidirectional dc–dc converters. Second, based on the general structure, operation principle and performance characteristics of all proposed topologies are simultaneously obtained, which can facilitate topology comparison and selection processes. Finally, in order to verify the effectiveness of theoretical analysis, design considerations and experiment results of a 500-W prototype circuit are demonstrated. [ABSTRACT FROM PUBLISHER]

In conventional dc–dc converters with synchronous rectifiers, hard-switching operation of the main switch and reverse-recovery problem of the synchronous switch result in degraded performance. In order to avoid these two undesired shortcomings, employing a coupled inductor is a simple yet effective solution. Apart from the improved soft-switching characteristic, low component count is also achieved since only a coupled winding and a series auxiliary diode are added. In this paper, a general zero-voltage-switching (ZVS) topology with a coupled inductor is proposed and based on which, a family of ZVS synchronous buck, boost, and buck–boost converters is readily obtained. For each fundamental dc–dc converter, several viable ZVS topologies evolve, among which an optimum topology can be chosen according to the different requirement in practical engineering applications. To help the topology selection, generalized analysis and individual comparison are also undertaken. In addition, design consideration is illustrated and experiment results are provided to validate converter effectiveness. Furthermore, thanks to its generality, the topology derivation and generalized analysis can be easily extended to various synchronous dc–dc converters. [ABSTRACT FROM PUBLISHER]

This paper proposes a bidirectional three-level LLC resonant converter with a new pulse width and amplitude modulation control method. With different control signals, it has three different operation modes with different voltage gains. Therefore, it can achieve wide voltage gain range by switching among these three modes, which is attractive for energy storage system applications needing wide voltage variation. The proposed topology operates with constant switching frequency, which is easy to implement with digital control, and it can achieve soft switching for all the switches and diodes in the circuit as a conventional LLC resonant converter. The performance of the proposed converter is validated by the experimental results from a 1-kW prototype with 20 A maximum output current. [ABSTRACT FROM PUBLISHER]

A novel partial power conversion device (PPCD) is proposed to realize power flow control and voltage compensation in a three-phase power distribution system in this paper. The PPCD circuit, which is derived from the conventional push–pull forward converter, can achieve arbitrary voltage output without any large electrolytic capacitors. Thus, the system reliability can be enhanced. Furthermore, the converter has no full-rated components, which reduces the cost. In this paper, an injection model for power flow control is derived. A minimum power transfer control strategy is proposed to minimize the power losses during the operation. A closed-loop control method employing the synchronous reference frame theory for voltage compensation is also developed to enable the precise control. The systems with PPCD are simulated by MATLAB/Simulink to verify the functions. The experiments for voltage compensation are carried out based on a 30-kW prototype, which shows the effectiveness. [ABSTRACT FROM PUBLISHER]