IRREVERSIBLE DEMAGNETIZATION LOSS FOR ELECTRIC MACHINES WITH ARC-SHAPED PERMANENT-MAGNETS STABILIZED IN AIR

For electric machines with their permanent magnet assemblies stabilize d in air, a certain amount of irreversible loss of magnetization will occur in permanent magnets when magnet material with knee points in th e demagnetization curve is used. To estimate quantitatively the irreve rsible demagnetization loss in permanent magnet machines, the maximum loss of magnetization, the remanent flux loss and the demagnetization area are defined as their three figures of merits. A series of design curves for predicting the irreversible demagnetization loss for are-sh aped permanent magnets stabilized in air is presented in the paper. Th e effects of material characteristics, magnet geometry and its magneti c orientation on these merits are also discussed. Design curves are ob tained from field computation results by using the multi-hysteresis-lo op PM model recently proposed by the first author. These design curves are useful for permanent magnet machine designers.