Design considerations on a 36-slot 28-pole permanent magnet drive

Abstract

High torque permanent magnet drives with short axial length and large outer diameter are well known to be suitable for hybrid traction applications. High pole numbers and a large rotor inner diameter allow for direct crankshaft mounting and therefore for a compact integration of the electrical machine. Pole pair numbers vary from four to ten depending on the ratio of outer to inner diameter. Decreasing installation space and increasing torque demands require higher pole pair numbers resulting in higher excitation frequencies and high iron losses. This research presents design considerations on a 28 pole 25 kW permanent magnet drive with high short time overload capability. Electromagnetical, mechanical and thermal aspects are discussed.