University of Utah

Department of Electrical and Computer Engineering

ECE 5570                         Control of Electric Motors                            Fall 2010

 

Instructor:                   Professor Marc Bodson

Office:                        MEB 3268, Tel.: 581-8590

E-mail:                        bodson@eng.utah.edu

Class:                          MWF 2:00PM-2:50PM, WEB 1460

Class web page:          http://www.ece.utah.edu/~ece5570/

Lab web page:            http://www.ece.utah.edu/nsf_5570

 

1.   Introduction

Electric actuators are at the core of many industrial applications, including manufacturing, process control, and transportation. New developments in power electronics and computing technology have made it possible to control a variety of motors, including AC motors, and to achieve fast and precise tracking. Advanced features of computer-controlled systems, such as adaptation and efficiency optimization are also becoming increasingly common.

 

2.   Course Objectives

The objectives of the course are to:

 

·       provide an understanding of the operation of the motors, of their state-space models, and of the use of these models for simulations and for control system design.

·       give a working knowledge of methods used for the control of DC and AC motors, including open-loop and closed-loop methods and the selection of the controller parameters.

 

3.   Course Contents

Introduction to electric motors: Basics of electromagnetic energy conversion and derivation of electric motor models. Linear and switching amplifiers, pulse-width modulation. Power electronic devices, topologies of electrical drives, and quadrants of operation. Optical encoders, resolvers, and other position sensors.

 

Control of brush DC motors: Construction and operation of brush DC motors. Model of a permanent-magnet brush DC motor. Steady-state characteristics and torque limits. Dynamic response under voltage and current command. PID control laws for speed and position regulation. Switching and time-optimal control algorithms. Separately excited, shunt, and series DC motors. Field weakening.

 

Control of synchronous motors: Construction and operation of synchronous motors. Model of a two-phase permanent-magnet synchronous motor. Static and dynamic characteristics. Open-loop control, stepping and microstepping. Closed-loop quadrature control. DQ transformation and DQ model. Closed-loop control in the DQ frame of reference. Torque optimization and field weakening. Hybrid stepper motors and reluctance motors.

 

Control of induction motors: Construction and operation of induction motors. Model of a two-phase induction motor. Steady-state characteristics, equivalent circuit, and torque curves under voltage and current commands. Open-loop control with constant V/f. Closed-loop slip control. Models in rotating frames of reference. DQ transformation for induction motors and field-oriented control.

 

Brushless DC motors: Construction, modeling, and characteristics of three-phase permanent magnet synchronous motors. Sinusoidal commutation and quadrature control. Six-step commutation.

 

Three-phase motors: Three-phase supplies and connections. Three-phase to two-phase transformation. Unitary transformations and three-phase DQ transformation. Model of a three-phase synchronous motor and equivalent two-phase motor model. Control of three-phase synchronous motors using the DQ transformation. Three-phase induction motors: modeling and two-phase equivalent motor.

 

4.   Prerequisites

A basic course on control system design (ECE 3510, ME EN 5200/6200, CH EN 4203, or equivalent) is required. A course on state-space analysis (ME EN 5210/6210, CH EN 5203, or equivalent) is recommended but not required.

 

5.  Textbook

Course notes are available for purchase at the University’s bookstore.

 

6.  Office hours

Fixed office hours are not scheduled for this class. The instructor will be available for questions after class, and individual appointments will be made upon request after class or through email. Drop-in’s at the instructor’s office are acceptable, but will only be accommodated as circumstances permit.

 

7.  Grading

Grades will be based on homeworks, labs, and a final project. There will be no exams. Homeworks will consist in exercises and in computer simulations. The simulations will implement nonlinear models of electric motors to analyze their responses and to design control systems. Laboratory experiments will complement the homeworks by providing practical experience with the control of DC motors, stepper motors, induction motors, and brushless DC motors. The final project is described in next section.

 

Students should respect the due dates listed on the assignments. Reports may be turned in within a three-day grace period at no penalty (for example, homework due on Friday may be returned up to Monday at 5pm). Between three days and a week after the due date, 80% of the earned grade will be given. Work will not be accepted beyond a week without approval of the instructor.

 

8.  Final Project

Completion of a project is required for the class. A project consists in an independent investigation of a topic of current interest related to the course. Students are responsible for the selection of the topic of their project, and may consider subjects that are related to their own research. However, the topic must approved by the instructor. The timetable is the following:

Oct. 8: Submit a project description with references (1 page).

Nov. 12: Submit a partial report with the results obtained until then (5 pages).

Dec. 10: Submit a final report (15-30 pages + appendix).

A typical project consists in a survey of at least 3 papers from the research literature, organized around a common topic. The most convenient source is the IEEE Xplore database freely available to users of the University of Utah’s network (www.ieeexplore.ieee.org). Examples of journals with contributions in the field of electric motor control are the IEEE Trans. on Industry Applications, the IEEE Trans. on Industrial Electronics, and the IEEE Trans. on Control Systems Technology. Other publications available from the university’s library system may also be consulted, and web search engines such as Google can be useful. Copies of the papers used for a project must be attached in the appendix of the report.

The criteria for the grading of the reports will be:

(a) originality and critical thinking

(b) technical accuracy

(c) scope of the work

(d) quality of presentation (logical organization, clarity and neatness of the report).

Copying from papers (or simply paraphrasing) will not be considered a valid contribution. Students are expected to write the report in their own words and to demonstrate that they have read the papers, understood them, and thought about them in a critical and investigative manner. Examples of contributions include: critical evaluation of the significance of the results, comparison of different approaches, independent verification of the results (e.g., through simulations), and simplified or expanded analysis of the results. A project may be approved with a small number of papers if extensive validation of a concept in simulations or in experiments is proposed.

Examples of topics include:

·       Control of doubly-fed induction motors or generators

·       Control of synchronous generators with field winding

·       Split-phase induction motors or generators

·       Rotor time constant estimation for induction motors

·       Variable structure control & direct torque control

·       Real-time parameter estimation for electric machines