Research on fast calculation of dynamic process with thermal effects in electromagnetic device based on semi-analytical modeling

Dynamic characteristics of some electrical actuators such as contactor or relay can be accurately obtained with Finite Element method though the calculation takes usually long time. However, for some high power device such calculation can be meaningless because it disregards the thermal effects of the coil. And these thermal effects can produce significant impaction to the output characters. Indeed such problems are difficult to handle because it involves coupled phenomena from various physical domains, namely thermal, electric and magnet effect. Much research has been done to deal with such multi-physics problem. Our research focuses on embedding the thermal model of the coil to the already established semi-analytical model, which can calculate the dynamic process both efficiently and accurately. As a matter of fact, the Joule heat of the coil has two main effects: altering the B-H characters of the ferromagnetic materials and altering the resistivity of the charged coil. And these changes will in turn affect the dynamic process and the heating power of the coil. The thermal transient process featured by heating power, heat radiation power and thermal resistance etc, is studied to make this coupling feasible for fast calculation based on semi-analytical model. JQ-52F, a high power DC contactor with solenoid structure, is chosen as an example to elaborate our research.