462 / 2022-03-15 23:09:55

Thermal Cross-coupling Effect Analysis of High–voltage Multi-chips IGBT Models considering Chip size

MMC-HVDC,Thermal Cross-coupling Effect,High–voltage Multi-chips IGBT Models,Chip size

Thermal Cross-coupling Effect Analysis of High–voltage Multi-chips IGBT Models considering Chip size

Weicheng Wang, Lingyu Zhu, Cao Zhan, Zhang Yaxin,Qianming Jiao, Shengchang Ji

State Key Lab of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an,

China

wangweichemg@stu.xjtu.edu.cn

Purpose/Aim

High voltage IGBT power models have been widely utilized in power electronics equipment, like modular multilevel converter (MMC-HVDC) transmission systems. Parallel chips are packaged inside the high power IGBT modules to derive larger current capacity. Thus, thermal cross-coupling (TCC) effect among multi-chips is significant in the context of junction temperature estimation and reliability assessment. Though many researches have been conducted on the TCC effect, the influence of chip size is not investigated. To address this issue, IGBT modules with same packaging structure and various chip sizes are investigated in this paper.

Experimental/Modeling methods

A finite element model (FEM) of IGBT modules are established to derive compact physical thermal models under power step responses. The accuracy of the thermal model is verified by the transient thermal impedance. Besides, junction temperature profile of each chip under MMC working conditions are estimated to analysis uneven thermal distribution induced by TCC effect. An analytical relationship between coupling thermal resistor and chip size is derived using effect heat transfer area.

Results/discussion

The results show that chips in the center have larger average junction temperature and junction temperature fluctuation than that of peripheral chips. Moreover, the uneven thermal distribution is more serious among lager chip size, namely the average junction temperature and junction temperature fluctuation are larger and more unbalanced.

Conclusions

Thermal coupling effect is more significant with larger chip size. The coupling thermal resistor is negative correlation to the chip size, since the effect heat transfer area is positive correlation to the chip size.