Development of an Optimisation Tool for the Mechanical Design of Permanent Magnet Rotors in High-Speed Electric Machines

High-speed electrical machines (HSEMs) are increasingly used in applications such as air handling devices. Using surface-mounted permanent magnet (PM) rotors manufactured from rare earth metals, they provide benefits over their mechanical transmission counterparts. However, these PMs have low tensile strength and are prone to failure under large centrifugal loads when rotating. The ability to predict these stresses is extremely important to rotor design. A novel stress analysis theory for three-cylinder rotors has been developed using generalised plane strain (GPS) theory but remains complex and inefficient to use to manually design rotors. The mechanical optimisation of rotor design has not been widely explored in literature and has not been completed using the GPS theory for three-cylinder rotors. This paper utilises the GPS theory to produce an automatic optimisation tool for the mechanical design of three-cylinder PM rotors.