EJ3222 Introduction to AC Machine Analysis 7.5 credits

Introduktion till elmaskinanalys

Apart from representing a cornerstone in a wide range of industrial applications, induction and permanent-magnet machines are now an important part of environmentally friendly transport and energy production solutions. Since electric machinery has been around for close to 200 years, the related theory is well developed and represents an important and interesting application of the low-frequency approximation of Maxwell’s equations.

The aim of this course is to present an introduction to the theory of ac machine analysis at a somewhat more fundamental level than what is found in undergraduate/graduate-level courses. Hence, while the topics covered are commonly covered in an introductory course, focus is here put on model derivations in order to obtain a deeper level of understanding. After the course, the student should be well fit to apply the theory as well as to consult relevant research literature in order to further extend their knowledge.

  • Education cycle

    Third cycle
  • Main field of study

  • Grading scale

    P, F

Course offerings

Autumn 18 for programme students

  • Periods

    Autumn 18 P1 (7.5 credits)

  • Application code


  • Start date


  • End date


  • Language of instruction


  • Campus

    KTH Campus

  • Tutoring time


  • Form of study


  • Number of places

    No limitation

Information for research students about course offerings

Given in connection with EJ2222 every year in P1

Intended learning outcomes

After completion of the course the student shall be able to:

·         Analyze induction and permanent-magnet machines using analytical methods and the finite element method

·         Carry out a preliminary electromagnetic sizing of an industrial induction machine

·         Carry out thermal analysis of electric machinery using methods based on the finite element method and a lumped parameter approach

·         Implement a finite-element based solver in a Matlab environment

Course main content

Methods for design and analysis of induction and permanent machinery:

·         The magnetomotive force concept and its applications in electric machinery

·         Fundamental and harmonic winding factors

·         A thorough derivation of the equivalent-circuit induction machine model

·         Electromagnetic sizing of induction machines using the progressive rotor growth concept

·         An introduction to the finite element method applied to electric machinery

·         The dq transformation: machine modeling, voltage current constraints, impact of zero sequence

·         Magnetic saturation, cross saturation and impact of flux-linkage harmonics

·         Transient permanent-magnet machine models utilizing FEM data

·         The heat equation

·         Newton’s and Fourier's cooling laws

·         A model for predicting equivalent thermal conductivity of stator slots using the theory of two-component composite materials

·         Air-gap heat transfer

·         Lumped-parameter thermal modeling


Lectures, computer exercises, project work


PhD students at KTH, PhD students from other universities


O. Wallmark, AC Machine Analysis – Fundamental Theory, KTH Royal Institute of Technology and handouts.

Required equipment



  • EXA1 - Examination, 7.5, grading scale: P, F

The examination consists of five project works where the student demonstrates that he/she has obtained the necessary knowledge to verify the models and methods described in the course literature. The results shall then be compiled into five written project reports clearly showing how the models have been implemented together with comments on the obtained results. The projects and the associated project reports should be carried out individually. 

Requirements for final grade

Five approved project reports. A project report is deemed approved (by the course examiner) if all tasks have been solved and given a clear account for.

Offered by

EECS/Electric Power and Energy Systems


Oskar Wallmark, oskar.wallmark@ee.kth.se


Oskar Wallmark <owa@kth.se>


Course syllabus valid from: Spring 2015.
Examination information valid from: Spring 2019.