A High Efficiency Asymmetrical Half-Bridge Converter with Integrated Boost Converter in Secondary Rectifier


A conventional asymmetrical half-bridge (AHB) converter is one of the most promising topologies in low-to-medium power applications because of zero-voltage switching (ZVS) of all switches and small number of components. However, when the converter is designed taking a hold-up time into consideration, it has a large DC offset current in a transformer and a small transformer turns-ratio. To solve these problems, a new AHB converter with an integrated boost converter is proposed in this letter. Because the proposed converter compensates for the hold-up time using the integrated boost converter without additional loss in the nominal state, it can achieve the optimized efficiency regardless of the hold-up time. The effectiveness and feasibility are verified with a 250-400V input and 45V/3.3A output prototype.


  1. Hold-up time
  2. DC/DC converter
  3. Asymmetrical half-bridge converter
  4. High efficiency



Fig. 1. The conventional AHB converters. (a) DCS HB converter and (b) boost-cascaded AHB converter.

Fig. 2. The proposed converter.


Fig.3. Waveforms of the prototype converters with 400v input,3.3A/45v output The conventional AHB converter and (b) the proposed converter

Fig.4.Transient operation during the hold-up time

Fig.5. Measured Efficiency


In this letter, a boost-integrated AHB converter is proposed. The proposed converter integrates a boost converter in the rectifier in a new manner. Because the proposed converter can obtain an additional voltage gain during a hold-up time, it can be designed optimally in the nominal state regardless of the hold-up time requirement. Furthermore, since the proposed converter does not cause an additional loss in the nominal state, it can achieve the optimized efficiency.


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