Effect of control strategies on the two torque-producing mechanisms in high-speed PMSMs

The interest for high-speed Permanent-Magnet Synchronous Machines (PMSMs) is high. Often such machines are equipped with a conductive sleeve that is wrapped around the magnets, i.e. the Shielding Cylinder (SC). Its goal is to reduce the overall rotor losses, thereby protecting the magnets from overheating. In such machines torque is produced in two ways [1]; due to interaction between the magnets and the stator currents and due to interaction between the SC and asynchronous components in the magnetic field. The resulting torque components are indicated as T_PM and T_SC.