Finite element analysis of a permanent magnet synchronous machine with an external rotor for a position sensorless control

Permanent magnet synchronous machines with an external rotor nowadays gain in significance for high performance electrical drive systems such as with hybrid electric vehicles. With these applications, the machine will operate in a wide speed range and on the other hand with very fast changing loads in both motor and generator operational modes. In order to achieve a robust machine design, a position-sensorless control scheme using the dependence of the stator inductances on the rotor position is of great interest. With this intent, the paper discusses finite element analyses for the optimization of such permanent magnet machines with external rotors. Regarding the geometry parameters, a magnetic saliency necessary for the sensorless control scheme has to be preserved in the whole range of the operational modes.