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This paper proposes a family of soft-switching bidirectional converters. In many applications, the bidirectional converters operate over a wide range of duty cycle and load variations. In the proposed converters, in order to extend the zero-voltage switching operation range, two supplemental voltage sources utilizing passive components are implemented in the auxiliary circuit. By using this method, the soft-switching features are ensured for an extensive range of the converter duty cycles. This is achieved independent of the output power value or the converter operation mode, and so, soft switching is ensured within the entire converter operating region. In these converters, all semiconductors components are soft switched, and the auxiliary circuit does not contribute to the complexity of the control circuit. Also, no extra voltage stress exists on the main switches and the voltage stress on the auxiliary switches is lower than the main switches voltage stress. In this paper, the proposed bidirectional buck/boost converter is analyzed and to confirm the feasibility of the proposed method, experimental results of a 150-W prototype converter are presented. [ABSTRACT FROM PUBLISHER]

The interleaved bidirectional buck–boost converter dual active half-bridge (IBBC-DAHB) dc–dc converter consists of two converters IBBC and DAHB and a coupled inductor. The IBBC-DAHB converter has significant features such as low ripple current at the low-voltage side, low current stress on the input inductors, voltage stress across the switches less than the high-voltage side, high voltage gain, and zero-voltage soft switching. The converter offers high efficiency using phase-shift modulation when it operates at a nominal design operating point. However, the efficiency decreases due to high circulating current, high current stress, and limited soft-switching range when the source and load voltages deviate from their nominal values. This paper employs both duty cycle and phase-shift modulation methods to improve the above mentioned shortcomings using voltage matching for the DAHB converter. The proposed converter is analyzed and a 500-W experimental prototype with 40–60 V input voltage and 400 V output voltage under 100 kHz switching frequency is implemented to verify the theoretical results. The maximum efficiency of 97.15% is achieved at 60 V and 400 W. A flat efficiency characteristic for the converter is derived by the proposed control method, where the efficiency at 20% of nominal load is 91% and much higher than the phase-shift control, which is 70.8%. [ABSTRACT FROM AUTHOR]

In this paper, a novel four-phase interleaved high step-down converter is presented. The proposed converter can provide an extremely high step-down voltage conversion ratio within a moderate duty cycle. There are four main advantages of the proposed converter. First, the blocking capacitors can store energy as usual. Therefore, they are used as voltage sources to reduce the input voltage as well as to reduce the switch voltage stresses. Second, due to the charge balance of the dc blocking capacitors, the converter possesses an automatic uniform current sharing characteristic of the interleaved phases without adopting any extra circuitry. Third, due to the phase shift between the interleaved phases, the architecture provides a low output current ripple. Fourth, the number of phases can be expanded or reduced to any even phases; therefore, the converter has a wide range of applications. Finally, the operating principles and analysis of this architecture are given, and an experimental prototype is also provided to verify the effectiveness of the proposed converter. [ABSTRACT FROM PUBLISHER]

A new resonant converter having low voltage stress and nearly constant efficiency against line variation for high- and wide-input-voltage applications is presented in this paper. It is similar to a three-level zero-voltage-switching pulsewidth modulation converter (TL ZVS PWMC) with two flying capacitors. In the proposed converter, however, two flying capacitors are used as the resonant capacitors, and the output voltage regulation is achieved by frequency modulation. The main advantages of the proposed converter are that, since the sum of the voltages of two resonant capacitors is constant and is equal to half of the input voltage, the voltage across each switch clamps to half of the input voltage and keeps the balance. Moreover, all main switches and rectifier diodes are softly switched under full-line and full-load conditions, and high efficiency can be constantly achieved over a wide input voltage range. These advantages solve the drawbacks on TL ZVS PWMCs. The features, operation principles, and relevant analysis results over a wide input voltage range of the proposed converter are presented in this paper. The validity of this study is confirmed by the experimental results of a prototype converter with 400–600-V input, 48-V/10-A output, and 200-kHz resonant frequency. The experimental results show that the maximum efficiency of the proposed converter is 95.08% under a full-load and a 600-V input and slightly varies across the 400–600-V input voltage range. [ABSTRACT FROM AUTHOR]