L2D10 Power Conversion



Level 2 Power Conversion

I took over this course from Dr. Peter Marshall a couple of years ago and have made very few changes to the course or examination formats. The rest of this booklet is virtually the same as before except that I have changed the recommended textbooks and added a few more.

My office is 6bAB04. Dr. R Seebold (r.seebold@surrey.ac.uk ) 17/10/07

This manual gives details of the level 2 module Power Conversion and includes the syllabus, tutorial questions and method of assessment.

The module has 24 lectures.

Tutorials

The manual includes some interesting questions – often you have to make sensible estimates for some of the data.

Examination

The exam is 2 hours, 5 questions with no choice and closed book.

That sounds tough - however in compensation it is an OPEN EXAM and the majority of each question is reproduced in this manual. The wording of the questions should be identical (apart from corrected typos) but THE DATA WILL BE DIFFERENT. That means you will have to practise and practise the questions and then do the full calculations with new numbers in the exam. You will also have to transcribe the answers on to the answer sheet. Each question consists of lots of parts and you get full marks for the right numerical answer and zero for the wrong one (I do allow some margin for rounding). You get no marks for producing the wrong answer even if some of the method is correct (but you have had several months to sort things out). I do check that there is sensible working in your main answer books to discourage copying but my main attention is on your answer sheets. STUDENTS WHO DO NOT TRANSCIBE THEIR ANSWERS TO THE ANSWER SHEET GET HEAVILY FINED IN TERMS OF MARKS.

There is a strong parallel here to music students who practise and practise a particular piece and then perform this under assessment conditions. The advantages are:

No ‘luck’ or question spotting

No surprises

No exam nerves

All of the advantages of coursework without copying and excessive marking.

About 25% of the paper will be ‘closed’ and you do not get to see these parts in advance. The closed parts are aimed at rewarding the really bright student who has read around the subject. THE CLOSED PARTS WILL BE ON GREEN AND THERMAL ASPECTS.

Syllabus etc

UNIVERSITY OF SURREY - MODULE CATALOGUE

|Module Short Name : |EE2.pwc |  |Module Title : |Power Conversion |

 Objectives/Learning Outcomes

|Module Aims: To provide an optional module which motivates students into studying some aspects of electrical, electronic and electromechanical|

|engineering which are outside the mainstream interests of the School. To raise awareness of Energy issues. |

|Learning Objectives: On completion of the module, a student will have demonstrated a basic competence in performance calculations for d.c. |

|machines, universal motors, transformers, induction motors and three-phase controlled rectifier/inverters. |

 Content

|Fundamentals |

|[1-3] Conversion, Loss & Rating: Units, orders of magnitude, conservation of energy, fundamental limitations to output of rotating machines |

|(why is a 1 kW motor a 1 kW motor?), simple RC thermal model, exponential solution leading to steady and transient rating, switching v linear |

|electronic conversion. |

|[4] EMF & Torque Production: Magnetic flux, magnetic characteristics, basic mechanisms, principle of operation of machines and transformers, |

|equivalence of BIL and BLU. |

|[5-6] Power: Why AC ? Why three phase ? |

|Machines |

|[7-9] Power Generation: Fossil fuels, Elementary thermodynamics, Thermal efficiency, Combined heat & power. Renewable energy sources, wind, |

|wave, solar. |

|[10] Universal (AC series) Motor: Development of analysis from DC motor, instantaneous and average power, review of RMS, complex notation, |

|power factor, phasor diagram, comparison of AC and DC performance. |

|[11-12] Transformers: Basic equations, imperfections...leakage, finite permeability, saturation, eddy current, hysteresis. Effect of frequency|

|on relative importance of imperfections. Equivalent circuit model. Simple design. |

|[13-16] Three Phase Induction Motor: Construction and advantages, rotating magnetic field, synchronous speed, development of equivalent |

|circuit for rotor only, torque–speed characteristic. Supply requirements for speed control. |

|[17-18] Efficient Utilisation of Electrical Energy: Energy saving in pumps, fans. Regeneration in traction applications. |

|Power Electronic Conversion |

|[19-20] Rectifier, Inverter: Systems rather than device approach. Basic operation in terms of a matrix of ideal switching elements, terminal |

|characteristics derived from switching points for 3 phase controlled rectifier with high inductance load. Energy saving through cross-channel |

|dc link. |

 Prerequisites

|None. |

Pattern of Delivery

|Spring: 24 hours (2 per week) |

Methods of Teaching/Learning

|Lectures |

 Methods of Assessment and Weighting

|By 100% coursework tested in a formal examination setting. 10 credits. |

  Selected Texts

T.Wildi |Electric Machines, Drives, and Power Systems (6th Ed.) |0131969188 |Pearson | £65 |B | |A.Hughes |Electric Motors and Drives (3rd Ed.) |978-0-7506-4718-2 |Newnes | £17 |C | |P.C.Sen |Principles of Electric Machines and Power Electronics (2nd Ed.) |0-471-02295-0 |Wiley | £100 |C | |J. Twidell & T. Weir |Renewable Energy Resources (2nd Ed.) |9780419253303 |Taylor & Francis | £30 |C | |Y.Cengel & M.A Boles |Thermodynamics (5th Ed. In SI units) |007-125084-0 |McGraw Hill | £44 |C | |

Dr Roger Seebold November 2007

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