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ENM056 Electrical machines - design and analysis, LP1 HT22 (7.5 hp)

Course is offered by the Department of Electrical Engineering

Contact details

Responsible division: Division of Electric Power Engineering, Visiting address: Hörsalsvägen 11

Course purpose

The aim of the course is to teach students about (1) principles and procedure to design a permanent magnet synchronous machine for electric propulsion, and (2) methods to analyze steady-state and dynamic performance of induction machines used in industrial applications.

Schedule:

See Time Edit and course schedule information (xlsx) in General Information of the course website.

Course literature

An internal textbook (in PDF) can be download found in General Information of the course website. It is in draft version and includes most (but not all) knowledge required for the course. For the completed contents of the course, please refer to the lecture PPTs, tutorial materials, design assignment, and lab instruction. These materials will be uploaded in this course website part by part. 

For further reading about the machine design and analysis in general, please read reference materials:

  • Design of Rotating Electrical Machines, by Juha Pyrhönen, published by John Wiley & Sons.
  • Electric Machinery Fundamentals, by Stephen Chapman, published by McGrawHill.

Course design

The course covers the following sections:

  1. Introduction of the course and different electrical machines.
  2. Electromagnetics, magnetic circuits and torque generation.
  3. Rotating magnetic field.
  4. Winding arrangements and calculations.
  5. Machine modeling in different coordinate systems.
  6. Induction machine.
  7. Permanent magnet synchronous machine.
  8. Synchronous generator.
  9. Electrical machines for traction applications.

Course arrangement
This course runs in the first quarter of each academic year. The course comprises of:

  • 18 lectures (2 × 45 min per lecture)
  • 10 tutorials (2 × 45 min per tutorial)
  • 1 session of practical laboratory work on induction machine (1 × 4 hours)
  • 4 sessions of modelling and simulation on induction machine (computer lab)
  • 6 sessions of design assignment in computer room

Lectures and tutorials are held in classroom at Chalmers campus. The practical laboratory work (the class is divided into small groups) will be in the Grundkurslabb (Room 3502) found in the Division of Electric Power Engineering (Hörsalsvägen 11, after the Division entrance, go up the stairs and turn around to the left). Computer exercises and design assignments will be held in a computer room in Chalmers.

Practical lab work (compulsory)
There is one session of practical lab work to determine parameters of an induction motor and measure the starting performance. Before coming to the lab, the home assignments must be done, and the safety instructions must be read and understood. The lab papers with the home assignment MUST be uploaded to the course website not later than Sunday, 18th September. This will be checked by teachers before the lab work can start. Students without uploaded home assignments are NOT allowed to do the lab.

Modeling and simulation (compulsory)
There are 4 sessions of computer exercise (MATLAB) for modeling and simulation of the induction machine measured in the practical lab. The sessions are used for students to build the induction machine model with the measured parameters, simulate the start-up, and compare the simulated results with the measured ones. The students are expected to explain the comparisons to the teachers. The teachers will give “Passed” if the comparisons and explanations are reasonable.

Design assignment (compulsory, max 20 points)
All students are required to take part in the design assignment, in which the knowledge learnt in the lectures and tutorials will be used.

  • The goal is for students to use the knowledge learnt in the course to design their own motors (PMSMs for electric vehicles) under given specifications.
  • Design assignment will be done in small groups of 3 persons. The students are grouped randomly by teachers in the first week. Adjustments can be made for the students who have conflicts in schedule with other courses. These students must inform the teachers in the first 2 days after course starts. The same group will do the practical lab work, simulation exercise, and design assignment.
  • Design instructions and consultancy will be arranged in 6 dedicated sessions.
  • The design work should be conducted in MATLAB.
  • Report including specifications, design process, design results and motivations for the selections of key parameters should be sent to the design assignment teacher before the deadline. One report per group is required.
  • The score will be given based on the quality of the report according to 4 criteria (max 5 points per criterion).
  • Deadline for design assignment draft report Part 1 is Sunday, 25th September. Deadline for the final report is Thursday, 13th October. The reports should be uploaded to the website before deadlines.

Learning objectives (after completion of this course, the student should be able to):

  1. describe working principle and main parts of synchronous machines and induction machines, and manufacturing process of electrical machines.
  2. model electromagnetic excitation, permanent magnets, and lamination materials considering saturation.
  3. calculate reluctance, magnetic flux, flux linkage, and inductance.
  4. calculate operating points of permanent magnets under no-load and load conditions of a permanent magnet synchronous machine (PMSM).
  5. describe various type of windings, e.g. distributed and concentrated windings, single-layer or multi-layer windings, integer slot or fractional slot windings.
  6. draw the distribution of phase coils in slots of a three-phase machine and calculate winding factors for both distributed and concentrated windings.
  7. design double-layer three-phase windings including selection of coil turns, series and parallel branches, and wire strand with a proper copper fill factor.
  8. calculate electromotive force (EMF) of a PMSM at no-load.
  9. describe different coordinate systems including three-phase and two-phase stationary coordinate systems, d-q rotating coordinate system.
  10. calculate inductances in d- and q-axis by using magnetic circuits for a PMSM and model it in d-q coordinate system.
  11. design a PMSM for electric vehicle applications, calculate power, power factor, torque, copper losses, iron losses, and efficiency.
  12. describe how geometrical parameters and material characteristics affect the performance of the PMSM.
  13. draw equivalent circuit and calculate steady-state performance of induction machines and analyze the influence of circuit parameters on torque-speed curve of induction machines.
  14. perform a practical experiment in order to determine the equivalent circuit parameters of an induction machine and acquire relevant quantities during a start-up.
  15. describe the dynamic model of the induction machine in different coordinate systems, perform a simulation of the starting process using MATLAB, and evaluate the simulated results with the measurements.
  16. draw phasor diagram and control reactive power by field current in a synchronous generator.
  17. describe different kinds of traction motors and discuss their features.
  18. identify the ethical aspects needed to be considered in design and use of electrical machines.

Examination form

The examination of the course (total 100 points) includes 3 parts:

  1. Lab work and simulation exercise are compulsory. Students must conduct the lab exercises according to the requirements and follow the safety instructions. Participation in the lab sessions is registered by teachers. Evaluation on simulations and measurements should be done together with teachers in the computer room. The work should reach the quality of “PASSED” given from the teachers. The knowledge learn from the lab work will be examined in the final examination.
  2. Design assignment (total 20 points) is compulsory. Demonstration of design programs for teachers is required. In order to pass the course, the minimum score of the assignment is 10 points. The score will be given based on following criteria (5 points per criterion).
  • Accuracy of numerical calculations. Since the numerical calculations are performed using MATLAB, the results should be close to the correct values to receive higher points. The total points will be determined based on the percentage of correct calculations.
  • Completeness of report. It will be verified if all the questions have been answered, the necessary information such as appendices, author details, and relevant figures are included, and the maximum page limit is respected.
  • Concepts understanding. The answers to the theoretical questions will be used to evaluate the conceptual understanding.
  • Formatting: The overall formatting of the report, including grammar, figure, table, and equation, will be used to evaluate the quality of the report. The participants are encouraged to use the uploaded template.
  1. Final examination (total 80 points). The examination will be arranged in the last week of the course period. Students should apply for the examination themselves online. The final examination will be written examination for 4 hours. The final examination will cover the knowledge learnt in the lectures, the tutorials, lab work, simulation exercise, and design assignment. Some information given in the lectures and tutorials is also critical for preparation of final examination. Therefore, attendance of these teaching moments is important.
  2. Grades of the course will be evaluated based on the total points (max 100 points = 20 design assignment points + 80 final examination points). To pass the course, a student must (1) participated the practical lab work; (2) conducted the computer exercise and explained the simulation/measurement results for teachers; (3) demonstrated the design program and provided design assignment report; and (4) total points not less than 55 points. Final grades: 55-69 points: Grade 3; 70-84 points: Grade 4; and 85-100 points: Grade 5. Re-examinations are arranged 2 times per year by the university. The difficulty level of re-exams is the same as the last final examination. The lab work results and the points from the design assignments will be valid for 3 years.

Course website (Canvas) is used for the course organization and communication between teachers and students. 

Old examination questions
Old examination questions and their simplified answers will be uploaded in the course website two weeks before the final examination. No middle term trial examination.

Language:
All course activities will be conducted in English only. The reports must be written in English. 

Changes made since the last year:

  • The lectures and tutorials will be conducted in classroom in this year. It is different from last year in which we had hybrid teaching format. No recorded videos. 
  • Practical lab: the homework to prepare the lab should be uploaded with specific date.
  • Design assignment: introduce an evaluation method with 4 criteria, 5 points for each criterion.

 

Course summary:

Date Details Due