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This unit will cover the following:

(1) Transformers

• Principles of single-phase transformer operation.

• Analysis of transformers using equivalent circuits including load calculations, open- and short-circuit tests, regulation and loss mechanisms.

• Uses of transformers, overview of transformer construction, and basic design principles.

(2) Induction Machines

• Production of a rotating field using three-phase windings, and induced emf.

• Principles of operation and analysis of induction machines using reduced steady state equivalent circuits, including the concept of slip, performance calculations, loss mechanisms, efficiency, torque/speed characteristics, load curves and speed of operation.

• Induction machine speed control by classical means and the need for variable frequency operation.

(3) Synchronous Machines

• Machine topologies and construction.

• Principles of operation and analysis of permanent magnet and wound field synchronous machines using their reduced steady state equivalent circuits, including performance calculations using phasor diagrams.

• Overview of the brushless DC motor equivalent circuit and torque/speed characteristics.

(4) DC-DC converters

• Principle of switched-mode power conversion.

• Power MOSFET device.

• Step-up and step-down DC-DC converters.

• Bi-directional step-down / step-up DC-DC converter.

• High-frequency transformer isolation and the two-transistor forward converter.

• Inductive switching waveforms and switching losses.

(5) AC-DC Converters

• Single-phase diode rectifier circuit with inductor or capacitor DC filter.

• Calculation of active power, apparent power and power factor.

• Power transfer in AC circuits to non-linear loads, harmonics and power factor.

The course unit aims to: Introduce the operating principles of electrical machines and power electronic circuits. The main electrical machine and power electronic converter types will be studied, along with basic analysis methods, providing a basis for equipment design and systems analysis. Practical, measurement techniques and equipment characteristics will also be studied.

On the successful completion of the course, students will be able to:

ILO 1: Describe using sketched waveforms the operation of DC-DC converters and single-phase rectifiers.

ILO 2: Formulate equivalent circuits of transformers, induction, synchronous and BLDC machines.

ILO 3: Model transformer and machine behaviour using per-phase equivalent circuits.

ILO 4: Measure induction motor characteristics and DC-DC converter waveforms and critically evaluate the results.

ILO 5: Evaluate the technical, environmental and sustainability impacts of electrical drive and power electronic technologies.

ILO 6: Analyse DC-DC and AC-DC converter waveforms, calculate operating conditions, component values and switching losses.

Coursework:
Machines Lab (10%)
Power electronics Lab (10%)
The coursework forms 20% of the unit assessment

Coursework prep and submission - 4 hours.

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D. O’Kelly:’Performance and control of electrical drives’, McGraw-Hill
G.R. Slemon: ‘Electrical Machines and Drives’, Addison Wesley
Mohan, Undeland and Robbins, ‘Power Electronics: Converters, Applications and Design’, Wiley.