Research on Transient Electric Field Calculation in Welded Devices Considering Dielectric Relaxation of Insulating Materials

High-voltage, high-power welding-type IGBT devices are essential in high-voltage DC equipment. Accurate transient electric field distribution within these devices is crucial for effective insulation design. During operation, these devices face positive polarity repetitive square waves, leading to dielectric relaxation in insulating materials and resulting in electric field distortion. However, current methods do not consider this effect. This paper presents a transient electric field calculation model for welding-type IGBT devices that includes dielectric relaxation. Using the complex frequency domain finite element method and complex sparse matrix direct solving algorithm, the internal transient electric field distribution is analyzed, and the impact of dielectric relaxation is studied. By adjusting encapsulation insulating material parameters, the electric field intensity at weak insulation points is significantly reduced, demonstrating effective insulation design through well-matched insulating materials.