Windage loss reduction for hybrid excitation flux switching motors based on rotor structure design

This paper presents design study on windage loss reduction for hybrid excitation flux switching motor employing two types of rotor structure. Conventional flux switching motors have a rotor structure with salient poles, by which windage loss at high speed region becomes serious. To reduce the windage loss, two types rotor are built: One is a cylindrical rotor employing iron rib between adjacent salient poles and shrouds placed at both ends in axial direction of rotor body and, the other is only employing the shrouds. Experimental tests using two machines combining with an existing stator and two rotors are conducted. As a result, the rotor with only the shrouds can greatly reduce the windage loss while keeping the maximum torque and power, and motor efficiency at high speed region as it is. From a viewpoint of windage loss reduction, different rotor configurations with and without the shroud are investigated by 3D-FEA based fluid analyses and discussed.