Operation of highly rated permanent magnet synchronous machines

Many applications call for drives with very high power/torque per unit weight/volume. Typical examples are drives for aerospace actuation systems and for electric or hybrid automotive transmissions. Permanent magnet machines of various types are strong contenders for these applications and to get the most from a given frame size they will be designed with high electric and magnetic loadings. Drive specifications quite often call for constant torque over a limited low speed range followed by constant power over an extended high speed range. Usually the high speed range involves operation of the machine at the supply voltage ceiling with flux weakening. The problem is examined from the viewpoint of trying to establish operating conditions using fixed parameters based on unsaturated or saturated conditions in comparison to a full account of saturation. This study can be seen as being related to strategies that might be implemented in a controller for the drive of the chosen machine