Hot spot temperature is an important parameter which directly affects insulation life of power electronic transformer. For guiding reasonably insulation epoxy encapsulation design of the power electronic transformer

the equivalent model of 220 kW/30 kHz power electronic transformer is constructed

and the influence of the thermal conductivity of epoxy insulating material on temperature distribution characteristic of transformer at different operation conditions. The results show that the hot spot temperature of power electronic transformer with coaxial distribution of high and low voltage windings is mainly located at the height which is 56% from the bottom of winding

and it gradually increases with the increase of load coefficient. In the case of short circuit

the hot spot temperature of high and low voltage windings rises at the speed of 8 ℃/s and 22 ℃/s respectively. The hot spot temperature of the transformer decreases significantly with the increase of the thermal conductivity of the epoxy insulating material. When the thermal conductivity of the epoxy insulating material is higher than 1.1 W/(m·K)

the hot spot temperature variation tends to be gentle. At this time

the temperature distribution of the transformer meets the requirements of China national standard GB/T 1094.11—2022 specification and has a load margin of 30%. The research work can provide theoretical reference for the design of epoxy insulation encapsulation of power electronic transformer.