Alternatives for leakage reduction in a novel claw-pole electrically magnetized synchronous machine

The leakage characteristics of a novel claw-pole electrically magnetized synchronous machine are discussed in this paper. The novelty of the machine is that the magnetizing coils are placed in magnetically conducting end-plates, thus eliminating the need of slip-rings in the rotor. A previous study comparing this machine with a permanent magnet alternative showed a 20% higher leakage in the electrically magnetized machine, and 15% lower torque. Using 3D finite element simulations, an in-depth study of the leakage paths in this machine has been carried out, together with an assessment of the solutions that contribute to reduce the leakage. It is shown that the output torque can be improved by up to 113% by combining different types of permanent magnets around the claw-poles.