基于优化对称布局的多芯片SiC模块动态均流

Dynamic Current Sharing of Multichip SiC Module With Optimal Symmetric Layout

由于开关速度非常快,多芯片并联碳化硅（silicon carbide,SiC）功率模块的电压、电流振荡问题比硅（silicon,Si）器件更加突出,对寄生参数的要求也更高。然而,现有的商业化大功率SiC模块采用多芯片并联模式,大多沿用Si器件的封装技术,寄生参数不仅偏大,且存在明显的不对称性,不能充分发挥SiC器件的优越性能,亟需新的封装结构,以改善模块内的电热应力分布。首先,针对直接覆铜板（direct bonded copper,DBC）寄生电感的计算,提出两种简化计算方法,并将计算结果与有限元进行对比,基于这两种方法进行新型DBC布局的辅助设计,针对几种不同的三芯片并联功率模块,对比研究DBC布局对寄生参数分布、电流分布特性的影响,揭示寄生参数对多芯片并联模块电流分布的影响机理。最后,提出一种物理对称的新型功率模块封装结构,以实现各芯片间的电流均衡。对比分析表明,所提出的新型DBC布局能够显著减小回路之间的寄生参数差异,提升了SiC芯片间的电流分布一致性,有利于提升并联芯片额定电流的使用率,改善模块电–热应力的均衡性。

Due to very fast switching speed,the voltage and current ringing of silicon carbide（SiC） power modules are more prominent than those of silicon（Si） ones,and SiC power modules are much more sensitive to stray parameters.Most of the commercial SiC high power multi-chip modules,however,still adopt the packaging technology of Si ones.In a SiC multi-chip power module,the stray inductances are large and asymmetrical,which limit the superior performances of SiC devices.New packaging structures are urgently needed to balance the distribution of electro-thermal stress in the module.In this paper,two simplified methods are proposed to calculate the parasitic inductances of direct bonded copper（DBC） in power module,compared with finite element method（FEM）.Stray parameters distribution and current sharing in the several kinds of DBC layouts are comparatively studied.Mechanism of current sharing in a multi-chip power module is proposed.A symmetrical DBC structure is presented to confirm the stray inductances and drain current among paralleled branches in the power module.Compared with traditional DBC layouts of power modules,the proposed DBC layout significantly overcome the asymmetry of stray inductances among paralleled power loops.By using the symmetrical packaging,the current sharing characteristic among paralleled SiC chips in the whole module is improved.This paper is beneficial to ensure the utilization rated current and the electro-thermal stress in a multi-chip SiC module.