On the proximity effects of high-energy magnets on M-19 magnetic steel core

Permanent magnet synchronous motors (PMSM) and asynchronous induction motors (IM) are widely used in the industry for a diverse set of applications. Although the use of induction motors is increasing for industrial applications due to cost inconsistency in rare earth magnets, PMSM motors are still being used because of their compact size, high power density, and greater efficiency. In interior permanent magnet synchronous motor (IPMSM) and surface mounted permanent magnet synchronous motor (SPMSM), the non-oriented silicon steel core is in continuous contact with high-energy rare earth magnets. This paper focusses on the effects of these high-energy magnets on the magnetic properties of M-19 steel core. It is observed that the relative permeability of the M-19 steel decreases when it is kept in contact with three sintered Neodymium (NdFeB), grade N45 permanent magnets. This leads to decrease in the inductance of the motor. It thus depicts a very important concept which is generally ignored while designing motors especially for electric propulsion and industrial applications where the effects can be significant.