Study on air friction loss of high speed PM machine

Air friction loss of rotor surface for a high speed machine is quite large and difficult to be determined accurately. In this paper, the rotor friction loss for a high speed permanent magnet machine with rated speed of 60000rpm was studied theoretically and experimentally. The friction losses for different rotor speeds were calculated based on the 3D finite element analysis of fluid field. The experimental friction losses were obtained by loss separation based on the tested total losses of the machine for different rotor speeds. The calculated friction losses are accorded with the tested results which show the validity and feasibility of the calculation method of friction loss.