Beyond Induction Motors—Technology Trends to Move Up Efficiency

TLDR

Premium/IE3 motors are now mandatory in North America, and the IEC 60034‑30 2nd Edition will introduce Super‑Premium/IE4 and Ultra‑Premium/IE5 classes; recent market entrants include IE4‑class line‑start permanent‑magnet and squirrel‑cage induction motors for fixed‑speed applications, IE4‑class synchronous reluctance motors for variable‑speed, and moving to IE5 may require shifting from radial‑flux induction to PM or reluctance technologies using rare‑earth or ferrite magnets. The study presents an efficiency analysis of emerging electric motor technologies, focusing on axial‑flux permanent‑magnet synchronous motors. The authors evaluate potential efficiency gains from various design options and discuss the theoretical maximum efficiency achievable with these options. They find that design options can yield significant efficiency gains, approaching the theoretical maximum efficiency limits.

Abstract

Premium/IE3 efficiency class motors are now mandatory in North America. Super-Premium/IE4 and Ultra-Premium/IE5 efficiency classes are to be defined in the 2nd Edition of the IEC 60034-30 standard. For line-start fixed-speed applications, Super-Premium/IE4-class line-start permanentmagnet (PM) motors and squirrel-cage induction motors are recent entrances in the industrial motor market. For variable-speed applications, IE4-class synchronous reluctance motors are also a recent entrance in the market. For the low-power range, moving from the IE4 to the IE5 class may require moving away from radial-flux induction motor technology and into PM and reluctance technology, either using rare-earth or ferrite magnets. In this paper, efficiency analysis on the best available emerging electric motor technologies, such as axial-flux PM synchronous motors, is presented. The potential efficiency gain associated with several design options as well as some considerations on the theoretical maximum efficiency achievable taking into account those existing design options.