Charles R. Frontczak
Tempel Steel Company

Abstract

Some say that electro-magnetic designers for electric motors and generators have a secret recipe. It’s somewhat true, because these designers used many years of painfully acquired knowledge. Today however, engineers rely on a great number of computer generated tools to aid in the process. Some are home grown while others are purchased. This paper discusses a computer based solution, Finite Element Analysis (FEA), which may be used to design motors and generators.
Designs come in two basic varieties. First are the designs which spawn from existing products. These are the most straight forward because there is usually a good platform of test results. Second are those designs that require a clean sheet approach, this being the most difficult.
The use of computer aided design tools such as FEA can speed up the design cycle and can perform many more case studies and iterations of data in a shorter period of time.
This paper focuses on electrical steel grade selection for Hybrid I.P.M. Electric Motors. Choosing the proper steel is the foundation of any good electro-magnetic machine. In most cases, there is insufficient data available for accurate properties of steel characteristics, especially high frequencies. Tempel has developed methods, including Epstein and ring tests that generate a comprehensive range of core loss, permeability and magnetizing force data as functions of both frequency and induction. The use of this data input in JMAG allows the user to make educated decisions and places numerical values for each case study.
Additionally, I’ve added the iron loss differences between three methods of securing lamination stacks. These three methods are inter-locking, welding, and bonding.