星载1MHz GaN LLC变换器低反向导通损耗控制

Low Reverse Conduction Loss Control for 1MHz GaN-Based LLC Converter Used in Satellite Application

氮化镓(GaN)器件反向导通压降一般超过1.8V,400W 1MHz LLC变换器一次侧GaN器件反向导通损耗超过单管总损耗15%。该文提出一种应用于1MHz星载GaNLLC变换器一次侧开关管的低反向导通损耗控制,根据GaN器件结电容放电时间调整死区,在保证实现零电压软开关(ZVS)的前提下缩短GaN器件反向导通时间以降低反向导通损耗。所提控制基于数学模型,对GaN器件等效输出结电容与LLC死区内谐振电流进行推导,计算LLC一次侧GaN器件结电容放电时间作为不同工况下死区调节依据。使用抗辐照GaN器件搭建400W 1MHz LLC变换器原理样机,验证所提死区控制。与固定死区(100ns)策略相比,一次侧GaN器件的单管损耗在10%负载与满载下分别降低32%与16%,整机效率分别提高1%和0.2%。

GaN devices typically have a reverse voltage drop above 1.8V,and the reverse conduction loss of the GaN device on the primary switch exceeds 15%in a 1MHz LLC converter.A low reverse conduction loss control is proposed to reduce the reverse conduction loss in the primary switch of the GaN-based 1MHz LLC resonance converter.The basic idea of the proposed control is to shorten the reverse conduction time of the primary switch on the premise of ensuring zero voltage switching(ZVS).The output capacitance discharge model is built to calculate the dead time and determine the turn-on instant of the primary switch.A 400W 1MHz GaN-based LLC converter with radiation-hardened GaN devices is built to verify the proposed dead time control.Compared with the fixed dead time strategy,the loss of the primary switch is decreased by 32%under 10%load and 16%under full load,respectively.