Transient coupled electro-magnetic thermal analysis of a permanent magnet brushless DC motor

Permanent magnet brushless DC motors used in aerospace generally have numerous qualities such as light weight, small size, and high efficiency. This means that the thermal design of those motors is very serious. In order to obtain an accurate thermal field simulation of a permanent magnet brushless DC motor, both electromagnetic and thermal fields have to be calculated in a coupled simulation. In this paper, the computation is based on finite element method which applied to a four-pole 3-phase 30kW permanent magnet brushless DC motor. The coupling of the fields is performed via a detailed loss calculation and the temperature dependence of the permanent magnets and conductive materials. The simulation results are presented and the results are compared with experimental data to validate the model.