Distribution and Optimization of Temperature-stress Field of Epoxy Solid Sealed High-capacity High-frequency Transformer
The high-frequency transformer(HFT),sealed with epoxy material for overall insulation,effectively reduces equipment volume and improves power density.However,uneven temperature distribution within the large-capacity HFT can lead to concentrated thermal stress in the epoxy resin,resulting in machine cracking and insulation failure.This study focuses on a 10 kV high-voltage large-capacity epoxy-sealed HFT as the research subject.A temperature simulation mod-el and stress calculation model have been developed to determine the thermal stress distribution of the HFT under rated operating conditions.The thermal stress is primarily concentrated in the epoxy layer between the iron core and winding.A method for reducing local thermal stress is proposed by enhancing the thermal conductivity of epoxy resin through mate-rial modification in order to decrease the hot spot temperature of the HFT,and the stress in epoxy resin between iron core and winding can be reduced,thereby increasing safety factor from 0.965 to 1.035.Two measures are taken,such as in-creasing the glass fiber reinforced materials and stress buffer layer,thus,the modulus of elasticity of the encapsulated structure is greatly reduced,the maximum tensile force inside is lowered,and the safety coefficient is increased from 1.035 to 2.691,which guides the structural design of large-capacity epoxy encapsulated high-frequency transformers.A 10 kV/200 kVA prototype is developed to perform validation through-30～120℃high and low temperature impact tests,and its crack resistance performance and effectiveness of reducing thermal stresses methods are verified.
high-frequency transformerepoxy resinstress distributionelastic modulushigh and low temperature im-pact
万方数据
维普
