PM motors for very high dynamic applications

This paper presents some design considerations for permanent magnet (PM) motors to achieve high dynamic performance. This is obtained by maximizing the ratio between the motor torque and the rotor inertia. It will be demonstrated that to obtain an optimal solution, the motor has to be designed on the border between the thermal and magnetic limit, always satisfying the required torque. The surface--mounted PM motor is a promising solution for such a requirement. However, the paper shows that the interior PM motor with tangential magnetization could be a competitor, thanks to the higher air--gap flux density. Analytical investigations and simulation results are presented in the paper for both motor topologies. Finally, experimental tests are given to validate the theoretical results.