Optimal split ratio for high speed induction machines

The split ratio of several types of electrical machines has been identified as an important optimisation parameter. While the optimisation of split ratio in high-speed permanent magnet, switched reluctance and flux-switching machines has been researched, this parameter has often been neglected in the design of high-speed induction machines. In this paper, using a described multi-domain design environment which puts equal weight on the electromagnetic, mechanical and thermal aspects, the rotor split ratio together with the rotor slot shape and electric and magnetic loadings are identified as important and sensitive parameters in the design of high speed, high power density laminated-rotor induction machines. This is shown using a design case study which involves improving the power density of an existing 10 kW, 75kpm laminated rotor induction machine.