Water cooling system design and thermal analysis for low speed permanent magnet machines

Effective cooling is of paramount importance for low speed permanent magnet (LSPM) machines due to their high power density and low speed. In this paper, a water cooling system is presented, and the three dimensional temperature fields are calculated for this type of machine. The steady-state heat transfer mathematic models are established, and hypothetical conditions are presented, together with boundary conditions and loads are calculated. Considering eddy current losses in the permanent magnet (PM) and the assembly clearance between the stator frame and the water jacket, the cooling system must completely satisfy the requirement with enough safety margins. The temperature distributions at different assembly clearances are presented, and several temperature curves of main parts of the LSPM machine are obtained.