Influence of Electrical Steel Grade on Different Types of Traction Motors

This paper provides a systematic approach to study the influence of electrical steel grade on electric vehicle traction motor performance. A permanent magnet assisted synchronous reluctance motor, an interior permanent magnet motor and an induction motor are considered to systematically quantify the influence of lamination thicknesses from 0.1 to 0.35mm, and materials with 3% and 6.5% silicon contents. Laminations with low silicon steel are better candidates in terms of peak and continuous torque production for low-speed operations. 0.1mm 6.5% silicon steel - 10JNEX900 can achieve higher efficiency and better flux-weakening capability above 400 Hz. Its higher mechanical strength is beneficial for complex rotor structure with bridges under stress from centrifugal forces. Therefore, grade choice relies on a compromise between low and high speed performance, propulsion system cost estimation and manufacturing challenges. Application related priorities define which grade is best suited.