A Novel Electric Field Stress Optimization Method for High-voltage IGBT Module Based on AC Dielectrophoresis

High-voltage IGBT modules are the critical components of new power systems. However, since the IGBT is subjected to unipolar square wave voltage for a long time, it is very easy for space charge accumulation to occur at the triple point, which will cause electric field distortion and eventually insulation damage. In this paper, the nonlinear conductive materials with adjustable nonlinear coefficients and switch-field stress were constructed based on AC dielectrophoresis for homogenizing the electric field. Firstly, a spatio-temporal evolution model considering “electric field stress-time-temperature” was constructed based on the classical Debye model and the carrier hopping conductivity model. Further, the dielectrophoresis process parameters corresponding to the optimal electric field distributions at 30°C, 60°C, and 90°C were calculated by simulation. Finally, the effectiveness of the above method in suppressing the local electric field distortion of IGBT was verified by partial discharge test, which can significantly improve partial discharge inception voltage (PDIV) by 31.5%.