Structural Aspects of PM Rotors

Structural design of a rotor of a high-speed electrical machine represents a challenging task. At high rotational frequencies centrifugal forces and, accordingly, stress in the rotor material become very high. Temperature increase in the rotor due to induced eddy currents and friction will produce additional, thermal stress between the rotor parts with different thermal properties. High-speed rotors must be capable of withstanding those stresses and also transfer of electromagnetic torque must be ensured over the whole rotor.