Mitigation measures of the electric field in the medium-voltage power module: Effect of voltage types and recommendations for designers

In the medium-voltage silicon carbide device power module, the higher voltage level will induce higher electric field stress in critical internal points such as the edge of the conductor on the direct bonded copper (DBC) substrate. This can lead to partial discharge and subsequently accelerated ageing of the insulating medium in the module. Therefore, it is important to reduce the high electric field strength. Herein, the related technical methods of electric field control are reviewed and compared by combining the ease of implementation in real power module and the field control effect. In addition, systematic explanations of the electric field drift and influencing factors of the electric field strength under different voltage types within different module structures are presented. Finally, for half-bridge power modules with different substrates structures, suggestions on how to implement non-linear field-dependent materials to reduce the electric field strength are given.