A study on the relation between rotor rib and maximum power of IPMSM in flux weakening region

This paper investigates the change of maximum power of an Interior Permanent Magnet Synchronous Motor (IPMSM) according to the rotor rib without the alteration of design factors related to the motor. As increasing the thickness of a rotor rib, it relieves stress concentration when the rotor rotates at high speed. However, the amount of leakage flux which comes from the PM makes the performance reduction of IPMSM. On the contrary, as a rib thickness is reduced, the opposite pattern occurs. Therefore, a decision of the rotor rib thickness is important. In addition, a rib thickness affects the d, q axis inductances and these factors result in the variation of the output power of IPMSM in the flux weakening region. Especially, as d-axis inductance changes, higher torque can be obtained. As a result, by redesigning the rotor rib, maximum power increased by ten percent in some cases. Therefore, the relation between rotor rib and maximum power of IPMSM in flux weakening region is identified by using finite element analysis (FEM) and equivalent circuit analysis.