Research on Influence of Motor Parameters on the Negative-Salient Permanent Magnet Synchronous Motor

The d-axis inductance
$(L_{d})$
of the negative-salient permanent magnet synchronous motor (NSPMSM) is larger than the q-axis inductance
$(L_{q})$
. Compared with the traditional motor, the NSPMSM has the characteristics of a high overload capacity, wide speed range, and preventing permanent magnet demagnetization. Positive d-axis current
$(i_{d})$
is applied to control positive reluctance torque when running at base speed. When the motor is running at high speed, a relatively small
$i_{d}$
can achieve speed expansion and effectively expand the motor flux-weakening range. The use of a magnetic bridge to increase the
$L_{d}$
and a W-type permanent magnet to reduce the
$L_{q}$
is proposed in this article as a novel NSPMSM rotor structure. Firstly, the working principle of the NSPMSM was determined according to the equivalent magnetic circuit. Secondly, using the finite element method, the influence of motor structure on torque and speed performance of NSPMSM was analyzed, and the motor structure was optimized. Thirdly, the effect of the internal power factor angle on the performance of the two motors is analyzed. Finally, the short circuit simulation and analysis verified that the NSPMSM has a stronger short circuit current suppression ability without sacrificing overload ability.