Electrical Machines (3 credits)

Course Description

The course introduces UG students to the various types of electrical machines, their operational principles, characteristics and analysis. The course covers topics on transformers, DC machines, induction machines and synchronous machines.

Prerequisites

• There are no specific prerequisites. However, an understanding of AC circuit analysis and basic magnetostatics is expected.

Topics that will be discussed

• Transformers

  • Review of magnetic circuits – Review of AC circuit theory – AC analysis using phasors – Introducing the ideal single-phase two winding transformer – Leakage flux and magnetising flux in transformer – Losses in a practical transformer – Transformer equivalent circuits – OC and SC tests – Analysis using phasor diagrams – Voltage regulation and efficiency analysis – Three-phase transformer – Per unit analysis in three-phase systems – Parallel operation of transformers

• DC Machines

  • Reveiw of Lorentz force - Homopolar and heteropolar DC machines – Elementary heteropolar DC motor – Practical windings and commutator-brush arrangement – Separately excited DC generator – EMF equation – Armature reaction – OCC and load characteristics – Series, shunt and compound excitation – Voltage build up in DC generator – DC motors – Starting methods – Speed control methods – Speed-Torque characteristics – Commutation issues – Modified DC machines: Amplidyne and Metadyne

• Rotating AC machines

  • Distributed stator windings – MMF pattern in distributed winding machines – Distributed windings with sinusoidal excitation – Generation of pulsating and rotating magnetic fields – Three-phase induction machines: Operating principle – Equivalent circuits for steady state analysis – No-load and blocked rotor tests – Slip-torque characteristics and efficiency analysis – Starting methods – Single-phase machines – Three-phase alternators – Equivalent circuit and phasor diagram – OC and SC tests – Synchronisation to grid – Grid connected operation – Prime-mover and field control – Power-angle characteristics – V and inverted V curves

Textbooks

• S. D. Umans, Fitzgerald & Kingsley's Electric Machinery, 7th ed. New York, NY, USA: McGraw-Hill, 2013.

• S. J. Chapman, Electric Machinery Fundamentals, 5th ed. New York, NY, USA: McGraw-Hill Education, 2011.

Grading

• Quiz-1: 20%

• Quiz-2: 20%

• Assignments and Tutorials: 20%

• Final exam: 40%