Performance comparison of wound field and permanent magnet excited electric machines

A thorough analysis of all dimensions of permanent magnet (PM) application in electric machines is carried out in the paper. Available literature on this topic is focused on their single advantage- the ability to generate magnetic field without electric current- and neglects their numerous drawbacks. Electrically conductive magnets dissipate losses when exposed to a variable air gap permeance in an electric machine. Constant flux of permanent magnets is powerless against effects of armature reaction in a synchronous machine. The uncontrollable price of rare- earth permanent magnets is far above the cost for any other material used in an electric machine.