Magnetically geared machines for electrical vehicle and renewable energy applications

Early in this millennium a paper by K. Attalah and D. Howe [1] re-ignited a worldwide research on magnetic gear devices. With help of finite element calculations they were able to show, that a specific magnetic gear topology with similarities to the classical planetary mechanical gear, was able to deliver a torque of 100 Nm in a cylindrical volume of one liter (100 Nm/l). This practical torque density number is really important compared to rule of thumb torque density values of classical electrical machines since it is not only percent but a decade higher.