励磁电流实现不对称半桥直流变换器ZVS的研究

Research on ZVS AHB DC/DC Converter Employing Magnetizing Current

为在较宽负载范围内实现初级开关管的零电压开关(ZVS),传统的不对称半桥(Asymmetrical Half-bridge,简称AHB)直流变换器常采用增大变压器漏感或在初级串接一个电感的方法,但这样会带来很多不良影响。研究了一种新颖的AHB直流变换器初级开关管ZVS的实现方法及其电路工作原理,给出了关键电路参数设计依据。在空载至满载范围内,该变换器无需串接外加电感,利用变压器励磁电流即可实现初级开关管ZVS,适用于小功率应用场合。试验结果表明,该电路具有结构简单、实现容易、成本低及变换效率高等优点。

By increasing the leakage inductance of the transformer or introducing an additional inductance, the conventional asymmetrical half-bridge （AHB） converter can achieve zero voltage switching （ZVS） for the primary side switches in a wider range of load, and at the same time some shortcomings are brought.A novel method to achieve ZVS for the primary side switches of AHB converter and its operation principle are analyzed,and the design criteria of the key circuit parameters are also presented.By employing the magnetizing current of the transformer,ZVS is obtained for the primary side switches from no load to full load.The converter is appropriate to low power applications.The experimental results show that the proposed circuit has the advantages of simple structure, easy realization, low cost and high efficiency.