Energy Conversion

Electric machines are a technology of choice in many modern energy conversion applications, including propulsion for hybrid-electric vehicles, wind energy generation, and flywheel energy storage systems. Interest in machines is steadily increasing due in large part to the flexibility of controls offered by modern computers and power electronic devices. In this course, the tools required for analysis and design of electromechanical energy conversion are developed. Upon completion of the course, a student?s engineering toolbox should contain 1) an understanding of the basic principles of static and electromechanical energy conversion, 2) methods to control static power converters, 3) knowledge of the use of reference frame theory applied to the analysis of rotating devices, 4) an understanding of the steady-state and dynamic characteristics of induction, permanent magnet synchronous, and wound-rotor synchronous machines, and 5) state variable analysis of electromechanical devices and converter supplied electromechanical drive systems.


Credit Hours:


Learning Objective:

A student who successfully fulfills the course requirements will have demonstrated an ability to:
  • Recognize the basic principles of electromechanical energy conversion
  • Use reference frame theory to manipulate dynamic equations of electric machinery
  • Calculate the dynamic performance of electric machinery in the time domain
  • Identify similarities and differences in the operating characteristics of induction, permanent-magnet synchronous, and wound-rotor synchronous machines
  • Use dc-ac power conversion circuits to control electric machinery


Our society runs on electricity. At the heart of the power system, large generators convert mechanical to electrical energy in the form of 3-phase ac power. At the edges of the grid, many industrial, commercial, and residential applications require electrical to mechanical energy conversion. The electric energy conversion processes in cutting-edge applications, such as wind turbines, solar photovoltaics, and electric vehicles, are all based on the same fundamentals.

This is an introductory course for graduate students on rotating electric machinery and power electronic drives. The course covers the theoretical aspects of electromechanical energy conversion and provides a rigorous treatment of several major classes of electric machines. Also, we present basics of three-phase dc-ac power electronic converters.

This course is for you if: 

  • You have completed and undergraduate course on electric machines, and you are already familiar with their basic operating principles; but you are curious to learn more about the underlying physics and would like to hone your machine analysis and control skillset
  • You have heard of terms like qd currents, Park's transformation, or vector control, and you are interested in understanding what they mean
  • You want to learn the dynamic models of 3-phase electric motors and generators, which are used in time-domain computer simulations of power electronic-based systems
  • You want to be educated on some key technologies that enable us to engineer better products to serve our society's need for greater sustainability.

Topics Covered:

  1. Introduction
  2. Reference Frame Theory
  3. Electromechanical Energy Conversion
  4. Distributed Windings
  5. Permanent-Magnet AC Machines
  6. Wound-Rotor Synchronous Machines
  7. Induction Machines
  8. Power Electronics


ECE 321 or a course in electromechanical motion devices.

Applied / Theory:



8 homework assignments during the semester submitted via Gradescope.


Midterm and final exams, proctored online with Examity.



  1. Analysis of Electric Machinery and Drive Systems (e-book available through the Purdue Libraries), 3rd Edition, P.C. Krause, O. Wasynczuk, S.D. Sudhoff, and S. Pekarek, John Wiley, 2013, ISBN No. 9781118024294

Computer Requirements:

Some homework assignments will require numerical calculations and/or time-domain simulations, using a software tool like MATLAB or Python (using Google Colab).