高压直流继电器线圈温度场数值算法

High-voltage high-power DC relays are key components in the field of new energy vehicles. Multi-turns high-density winding coils in relays are key components in the magnetic circuit, and its working temperature will seriously affect the electromagnetic parameters of relays. The temperature of this kind of coil is high and uneven after working for a long time or reaching steady state. However, in the past studies, the multi-turn coil was mostly considered as a single component or a region that temperature was distributed uniformly, which was inconsistent with its actual temperature distribution. It could not provide the reference value of accurate maximum temperature for thermal design, and thermal design is the key step of relay's life reliability. In this paper, a numerical algorithm for temperature field of multi-turn high-density coils based on the thermal resistance network method and finite difference method is proposed, taking the influence of material properties in the winding such as copper wire, insulating paint, air etc. and dimension parameter like the diameter of wire, thickness of insulting paint, distance among wires etc. into account. With this method, the temperature distribution inside multi-turn coils can be worked out efficiently. By comparison with the finite element method and experimental results, the feasibility and high computational efficiency of the method proposed in this paper are proved. It provides the basis for thermal design of relays, and also provides a theoretical reference for the accurate calculation of the temperature in multi-field problems in relays.