Roles of coercivity and remanent flux density of permanent magnet in interior permanent magnet synchronous motor (IPMSM) performance for electric vehicle applications

Abstract

We used four rotor topologies of an interior permanent magnet synchronous motor (IPMSM) to investigate the effects of remanent flux density (Br) and coercivity (Hc) of permanent magnet on motor performance. Commercial strontium hexaferrite (SrFe12O19: energy product, (BH)max, of 4.62 MGOe) and Nd-Fe-B ((BH)max of 38.2 MGOe) magnets were used for the rotor designs. The same machine specifications and magnet volume keep constant, while the Hc and Br vary to calculate torque and energy efficiency with the finite-element analysis. A combination of high Hc and low Br more effectively increased maximum torque of IPMSM when the hexaferrite magnet was used. For Nd-Fe-B magnet, the same combination did not affect maximum torque, but increased energy efficiency at high speed. Therefore, the Hc value of a permanent magnet is more effective than the Br in producing high maximum torque for SrM-magnet based IPMSM and high energy efficiency at high speed for Nd-Fe-B magnet based IPMSM.

Analytical Modelling of a Six-Phase Surface Mounted Permanent Magnet Synchronous Motor

“…where 𝜏 𝑠 is the slot pitch and can be defined as: where 𝐷 𝑖𝑟 is the inner diameter of rotor and and 𝑍 is the number of slots. The factor if PM motor (𝛾) is computed via the below expression (10):…”

“…where p is the number of pole pair. The volume of the armature part being an essential parameter in determining the 𝐷 𝑖𝑟 and 𝐿 can be calculated as (10):…”

Comparison of Simulation Methods for Angular Dependency When Modeling Demagnetization

“…In [13] and [14], irreversible demagnetization of spoke-type motors with ferrites is studied, but inclined fields were not considered. A ferrite-assisted reluctance motor is evaluated for demagnetization in [15] but inclined fields are not mentioned.…”