Department of Mechanical Engineering

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For prices and dates, please visit the Course Overview

Mrs Gillian Elsworth
Centre for Power Transmission and Motion Control
Department of Mechanical Engineering
University of Bath
Claverton Down
Bath BA2 7AY


Tel: +44 (0)1225 386371

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This course is run in conjunction with the IMechE.


ED - Electrical drives for mechanical engineers

This introductory module presents the fundamental theory of electromagnetism, power electronics, and electromechanical energy conversion. Upon completion, participants will know the principles of electrical motors, be able to select drives for given applications, appreciate requirements for controllers, and understand power electronic circuits. The concepts of speed/position control for DC, AC, and stepper motors are presented and typical problems associated with electrical drives, including dynamic characteristics and efficiency, are elaborated in the classroom and laboratory.


Who should apply

Mechanical engineers, graduates, technicians, managers and supervisory staff, particularly those new to the field of electrical engineering. Although the course material is more descriptive than mathematical, a basic mathematical knowledge is helpful.



Further details

Upon completion, participants should be able to do the following:

  • Understand the principles of electricity, magnetism, and electromagnetism, and the relationship between voltage, current, magnetic flux, flux linkage, force, torque
  • Know the characteristics and applications of power electronic components and circuits
  • Select and size electric motors for given applications based on torque/speed characteristics, efficiency, cost, supply requirements, dynamic performance, and controllability
  • Explain the operating principles of classic and brushless DC motors, synchronous/asynchronous AC motors, and stepper motors
  • Understand pulse-width-modulation and its application in AC and DC drives
  • Know the principles of speed/position control for both DC and AC motors, and identify supply requirements

Fundamental principles

  • DC systems, 1- and 3-phase AC systems
  • Electrical sources, transformers and power electronic converters
  • Effects of resistive, capacitive, and inductive loads.

Electricity and electromagnetism

  • Microscopic and macroscopic effects of electricity
  • Principles of magnetism and electro-magnetism
  • Relationship between voltage, current, magnetic flux, flux linkage, force, torque.

General theory of electro-mechanical conversion

  • Mechanical and electrical energy accumulation, losses, and power transfer
  • Force and torque production
  • Interaction of coils, reluctance torque
  • Rotating magnetic fields for constant torque production.

Magnetism and permanent magnets

  • Magnetic energy of ferromagnetic materials
  • Magnetisation and demagnetisation, B-H diagrams, hysteresis
  • Alnico, rare-earth, and neodym alloys.

Power-electronic devices and circuits

  • Semiconductor devices - diode, thyristor, GTO thyristor, BJT, MOSFET, IGBT
  • Half-bridge converters for voltage and current control
  • Full-bridge power converter
  • Switching power losses.

Power converters for drives

  • DC to AC converters - single phase and three phase inverters
  • Square-wave voltage source inverters, PWM inverters
  • Harmonic content of drive signals.

DC motors and drives

  • Basic mathematical model of direct current motors
  • Separate, shunt, series, and compound excitation principles
  • Permanent magnet iron and ironless motors
  • Drive selection, continuous and incremental servo systems.

Stepper motors and drives

  • Hybrid, VR, and PM stepper motors
  • Performance characteristics and time response
  • Full and half step motor drives, micro-stepping.

Brushless DC motors and drives

  • Motor construction
  • Trapezoidal and sinusoidal BDCM
  • Servo control.

Induction motors and drives

  • Basic construction and mathematical modelling
  • Options for speed control (pole changing, voltage amplitude, frequency control)
  • Transient operation
  • Impact of non-sinusoidal excitation
  • Vector control.
  1. DC motors
  2. DC-DC PWM converter
  3. Induction motors
  4. Brushless DC motors.
  1. Permanent magnet motor characteristics
  2. DC-DC PWM converter
  3. PM stepper motor drive
  4. Hybrid stepper motor drive
  5. AC motor drive
  6. Brushless motor drive.