EJ2222 Design of Electrical Machines 7.5 credits

Konstruktion av elektriska maskiner

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

    Second cycle
  • Main field of study

    Electrical Engineering
  • Grading scale

    P, F

Course offerings

Autumn 19 for programme students

Autumn 18 for programme students

Intended learning outcomes

The overall goal of the course is that the participant, after a completed course, should have a deep understanding of how Maxwell’s equations and fundamental principles within heat transfer can be applied to analyze and design electric machines.

After the course, the participants should be able to:

·        Apply the theory of MMF-waves to estimate air-gap flux densities, magnetic flux, inductances, and to derive the steady-state equivalent circuit of the induction machine (IM)

·        Apply the theory of MMF-waves to analyze and understand limits of permanent-magnet synchronous machines (PMSMs)

·        Implement a finite-element (FEM) based solver in a Matlab environment to solve static and quasi static, two-dimensional magnetic problems

·        Use FEM-based computations to estimate different performance parameters of IMs and PMSMs

·        Estimate stator and rotor resistances, magnetizing inductances and leakage-inductance components for IMs and corresponding parameters for PMSMs using analytical and numerical methods

·        Carry out a preliminary electromagnetic sizing of an IM given a defined torque request and thermal limitations

·        Carry out FEM-based computations on PMSMs to extract data to implement transient PMSM models including magnetic saturation, magnetic cross saturation and the impact of harmonics

·        Carry out FEM-based computations to estimate the resulting temperature distribution in an electric machine of IM or PMSM type

Course main content

The course covers the following topics:

·        The theory related to MMF waves (including harmonics) and how this theory is applied to electric machinery

·        The steady-state equivalent circuit of the induction machine derived using the MMF theory

·        Analytical models to estimate corresponding circuit parameters for IMs and PMSMs

·        Magnetic and thermal sizing of IMs

·        The finite element method and how it can be applied to solve static and quasi static two-dimensional magnetic problems

·        Transient models of PMSMs

·        Thermal modeling of electric machinery using the finite-element method

Disposition

The main contents of the course are comprised in the course literature  and are presented through a series of lectures. Parallel with these lectures, a number of computer-based project assignments should be solved and handed in in the form of smaller technical reports.

Eligibility

Knowledge in electromagnetic field theory corresponding to EI1200. An introduction to electric machinery corresponding to EJ2201 is recommended but is not a formal requirement. 120 hp and English B or equivalent.

Recommended prerequisites

Knowledge in electromagnetic field theory corresponding to EI1200. An introduction to electric machinery corresponding to EJ2201 is recommended but is not a formal requirement. 120 hp and English B or equivalent. 

Literature

O. Wallmark, AC Machine Analysis – Fundamental Theory, KTH Royal Institute of Technology, Stockholm, Sweden.

Examination

  • PRO1 - Project Work, 2.5, grading scale: P, F
  • PRO2 - Project Work, 1.5, grading scale: P, F
  • PRO3 - Project Work, 1.5, grading scale: P, F
  • PRO4 - Project Work, 2.0, grading scale: P, F
  • PRO5 - Project Work, 1.5, grading scale: P, F

Four out of five project works shall be completed where PRO1, PRO2, an PRO4 are mandatory.

PRO1: Analysis of an industrial induction machine using FEM (2.5 hp, mandatory)

PRO2: Electromagnetic sizing of an industrial induction machine (1.5 hp, mandatory)

PRO3: Transient modeling of permanent-magnet synchronous machinery (1,5hp)

PRO4: Thermal modeling of permanent-magnet synchronous machines using the finite-element method (2 hp, mandatory)

PRO5: Implementation of a finite-element based solver in Matlab (1,5 hp)

Requirements for final grade

Four handed in project reports that are judged passed.

Offered by

EECS/Electrical Energy Engineering

Contact

Oskar Wallmark

Examiner

Oskar Wallmark <owa@kth.se>

Version

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