Either non-magnetic rings or welded rings consisting of alternate magnetic and non-magnetic seg-
ments are used at present to hold in place the magnets and pole pieces of high-peripheral-speed rotor of
permanent magnet (PM) machines[1~4].The authors use three different methods-equivalent magnetic
circuit method,graphical method and finite element method-to prove that magnetic rings can also be
used for PM machines and are better than the above-mentioned two types of rings.
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