Thermal Stress Analysis of Epoxy Resin Encapsulated Solid State Transformer's Cracking Caused by Temperature Shock

Solid-state high-frequency transformers are the core components of power electronic transformers and have become a research hotspot. The research object of this article is 30kHz/200kVA epoxy resin encapsulated solid-state high-frequency transformer. Insulation cracking occurred during the temperature shock test. Using COMSOL software simulation, the results show that the contact point between the winding and the epoxy resin bears greater thermal stress at the beginning of the temperature shock, the thermal stress near the outer surface is smaller. As the temperature shock progresses, epoxy resin insulation presents extremely uneven temperature field distribution, the insulation thermal stress near the outer surface will increase and appear to be a maximum. Furthermore, reducing the expansion coefficient and Young's modulus of epoxy resin can reduce thermal stress. Increasing the thermal conductivity of epoxy resin can improve the temperature field and prevent local temperature gradients from being too high.