谐振变换器用新品功率MOSFET—UniFETTM耐用体二极管特性

Robust Body Diode Characteristics of the Latest Power MOSFETs, UniFETII for Resonant Converters

在服务器电源和通信电源应用领域，谐振变换器是一种十分令人关注的拓扑。它具有提升功效，减少元器件数量和抑制电磁干扰等优点，但是体二极管的使用有时会导致系统故障。为适应谐振变换器，提出了一种被称为UniFETII的新型功率MOSFET。它提升了体二极管的耐用性和COSS中的输出存储能量，使负面影响最小化。首先介绍了LLC谐振变换器和MOSFET的故障机理，在此基础上详细描述了UniFETTM II MOSFET技术和应用优势，并通过实验验证其正确性。结果证明MOSFET—UniFETTM在减少了门极电荷和输出电容存储能量的同时，提高了开关频率，降低了驱动损耗和输出电容损耗。

In applications of server and telecom power supplies, resonant converters are one of the most exciting topologies whose performance increases power efficiency, minimizes components count, and reduces Electromagnetic Interference （EMI）. However, use of the body diode in resonant converters sometimes leads to system failures. A new power MOSFET, called UniFET II, is optimized for resonant converters. It has improved body diode ruggedness and output stored energy in COSS, while minimizing negative effects. Firstly, the failure mechanisms for both LLC resonant converter and MOSFET are presented, and then a detailed description of UniFETTM II MOSFET technology and application benefits is also provided, which is verified through an ex- perimental prototype converter using UniFETTM II MOSFET. The results show that with reduced gate charge and stored energy in output capacitance, switching efficiency is increased and driving and output capacitive losses are decreased.