摘要
死区时间的合理选取是LLC变换器MOSFET开关管在宽调节范围内实现零电压开通(ZVS)以降低电磁干扰并提升运行效率的必要条件。现有选取方法因忽略MOSFET关断过程对死区时间的重要影响,选取结果实用性较差。通过理论研究给出了使LLC变换器在宽调节范围内实现ZVS的死区时间选取原则,参照该原则详细描述并合理简化最恶劣工况下计及MOSFET关断瞬态的LLC变换器工作过程。在此基础上,通过对MOSFET手册中数据的分析运用,精确算得最恶劣工况下LLC变换器实现ZVS所需死区时间的最小值,最终给出LLC变换器在宽调节范围内实现ZVS所需死区时间设定值的计算方法。该方法计算过程简单直观,实验结果亦验证了其正确性和有效性。
The rational selection of dead-time for the MOSFETs of LLC converter is essential to achieve the ZVS(Zero Voltage Switching) within a wide adjustment range for reducing the electromagnetic interference and improving the operational efficiency. The existing selection methods ignoring the influence of the MOSFET turn-off transient on the dead-time have lower applicability. Theoretical analysis is carried out to obtain the dead-time selection principles for achieving ZVS within a wide adjustment range of LLC converter,according to which,the operational behaviors of LLC converter including the turn-off transient of MOSFET in the worst operating conditions are exactly described and properly simplified. A method based on the specifications of MOSFET datasheet is presented for calculating the minimum dead-time required in the worst operating conditions to realize the ZVS within a wide adjustment range of LLC converter. The proposed method is simple and intuitive,and its correctness and validity are verified by the experimental results.
引文
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