基于开关能量均衡的并联碳化硅MOSFET芯片筛选
Chip Screening for Parallel Silicon Carbide MOSFET Based on Switching Energy Balancing
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摘要: 由于碳化硅MOSFET芯片生产制造工艺尚不够成熟,导致芯片参数分散性很大,使其在并联应用时的开关能量产生很大的差异。特别是在高频应用中,开关能量的不均衡将造成芯片发热分布不均衡,并严重影响碳化硅MOSFET模块的可靠性。该文测试获得30个单芯片碳化硅MOSFET器件参数的分散性,建立单芯片碳化硅MOSFET器件并联动态特性测试实验平台和单芯片碳化硅MOSFET器件并联的等效电路计算模型。分别通过改变并联器件的转移特性曲线、导通电阻、栅极内阻和极间电容的差异数值,获取并联器件开关能量和开通瞬态峰值电流的不均衡度。在此基础上,提出基于开关能量均衡的并联碳化硅MOSFET芯片的筛选策略,并通过实验对计算模型芯片筛选策略进行验证。计算结果和实验结果均表明,以瞬态电流均衡为目标的并联碳化硅MOSFET芯片筛选策略,并不能够可靠地保证并联芯片开关能量的均衡,在该文所提筛选策略基础上,可以利用芯片参数对开关能量的补偿效应,实现并联碳化硅MOSFET芯片开关能量的均衡。Abstract: Due to the immaturity of the manufacturing process of silicon carbide MOSFET chips, the static parameters of the chips are very dispersive. This leads to a large difference in switching energy when the chips are used in parallel. In high frequency applications, the mismatch of switching energy will have a significant impact on the heat distribution of the chips, and then which seriously affects the reliability of the silicon carbide MOSFET module. In this paper, the spread of static parameters of 30 single chip silicon carbide MOSFET devices was obtained by tests. An experimental platform for the tests of parallel single chip silicon carbide MOSFET dynamic characteristics and a parallel single chip silicon carbide MOSFET equivalent circuit calculation model was built. The difference of the transfer characteristic curve, on-resistance, gate internal resistance and inter-electrode capacitance of the parallel device were changed and the difference between the parallel switching energy and the turn-on transient peak current was obtained by the simulation model. On the base of calculation results, silicon carbide MOSFET chip screening strategy based on switching energy balancing was proposed. The results of the chip screening strategy were verified by experiments. The simulation and experimental results show that chip screening with transient current balance as the target could not reliably guarantee the switching energy balance in parallel connection. Based on the proposed screening strategy, making use of the compensation effect of the device parameters can balancing the switching energy.