Highly Efficient Asymmetric Boost Half-Bridge Diode-Clamped DC/DC Converter Under Wide Input Voltage Range

This article proposes highly efficient asymmetric boost half-bridge diode-clamped dc/dc converter that can accommodate a wide input voltage range. The proposed converter uses a boost half-bridge structure at the primary side and an active diode-clamped cell at the secondary side along with small size primary-side/secondary-side capacitors. Thus, this circuit is small and can be developed at low cost, but it experiences different resonance combinations during the first half and remaining half switching periods. By incorporating an active diode-clamped cell and asymmetric resonance, the proposed converter accomplishes nearly zero-voltage-switching turn-
off
at the upper secondary-side switch and turn-
off
at the voltage closed to half of the output voltage at the lower secondary-side switch regardless of variation in input voltage. This helps to reduce switching losses at the secondary-side switches. We identified the accurate voltage gain of the proposed converter and obtained its detailed design guideline taking the asymmetric resonance into account. Furthermore, the currents flowing through the output diodes are unbalanced due to the asymmetric resonance, but can be balanced by applying different secondary-side duty ratios. A 400-W rated prototype that converts 48–72 V input to a 380-V output is designed and tested to validate the concept. The prototype demonstrates 95.9% peak efficiency and enhanced efficiency performance over the wide input voltage range.