Comparison of Negative-salient Permanent Magnet Synchronous Machines with Concentrated and Distributed Stator Windings

Negative-salient permanent magnet synchronous machines(NSPMSM) characterized with L-d greater than L-q. D-axis current strengthens the permanent magnetic field at rated speed or lower than the rated speed, which not only can avoid the risk of irreversible demagnetization of the permanent magnet but also can make no-load back EMF lower. In this paper, we optimized a new NSPMSM rotor structure. With the same rotor, we compared four types of windings, two of which are fractional-slot concentrated windings(FSCW), and the other two are integer-slot distributed windings(ISDW). By using finite element analysis, we analyzed the no-load air gap flux density, winding functions, no-load back electromotive force(EMF), d-axis inductance, characteristic current, short circuit current, constant power speed range and high-speed permanent magnets loss of four types machines. According to comparative analysis, we summarized the advantages and disadvantages of FSCW and ISDW NSPMSM.