Losses and Thermal Analysis of High Speed PM Machine

There is increasing interest in high speed machines for industry applications due to the merits of high power density and small size. However, the heat dissipation of the high speed machine becomes a series problem also due to the small size and high power loss density. Therefore, how to estimate accurately the power losses and temperature rise is a big issue for the high speed machine design. In this paper, the calculation methods of power losses and temperature of high speed PM generator are studied. The air friction loss on the rotor surface is calculated by analytical method; and the core loss, copper loss and losses in the rotor are calculated based on the transient field-circuit coupled finite element analysis. The temperature field distribution of the machine is also analyzed using the finite element method. The calculated temperature is compared with the tested result for a high speed permanent magnet prototype machine.