Comparative study of the design and manufacturing processes of electrical motors with low and high energy permanent magnets

The author reviews the evolution of permanent magnet materials and different permanent magnet electrical motors. Comparative aspects of the designs, magnet systems and manufacturing methods are discussed for brushed and brushless motors with `metallic´, `ferrite´ and `rare earth´ magnets. Electro-magnetic design data and performance of typical motors are given from a manufacturing range of 20 mm to 300 mm outside diameters and 2 poles to 36 poles for both `power´ and `torque´ applications