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Advanced Electrical Machines :

Introduction to electricalmachine technology and

application areas

Dr. Chris Gerada

PEMC research group

University of Nottingham

chris.gerada@nottingham.ac.uk

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Course outline

1. Introduction to electrical machine technology and application areas.

2. Electrical Machines Basics

Electric and Magnetic Circuit theory, Torque production and DC machines

3. Machine windings and d-q representation

4. Basic Machine Types and Characteristics

Induction Machines (IM), Wound Field (WF) and (PM)Synchronous Machines(SM), Brushless DC (BLDC)

machines, Switched Reluctance machines (SRM), and Flux Switching (FS) machines

5. Electrical Machine design and sizing

6. Materials for electrical machines

7. Thermal management

8. High performance drives

9. Design case studies

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Course details

Requirements : Basic understanding of Electrical Machines

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Enabling Technology, Drivers and Application Areas

• Enabling Technology

• Power Electronics

• Microprocessors

• New Materials (Permanent Magnets)

• The technological improvements are leading to:

• Higher Speed Machines

• Higher Torque Density

• New machine topologies which only operate

through power electronics

• Higher operating temperatures

• High performance and Energy efficient control

•

Drivers• Energy Efficiency and reduced CO2 emissions

• Energy Utilisation

• More Electric Transport

• Renewable Energy

• Application Areas :

•

Traditional Applications• Industrial Drives

• Pumps

• Generators

• Expanding application areas

• Embedded generation

• Electrical and Hybrid Vehicles

• The all Electric ship

• The more Electric Aircraft

• Automation and manufacture

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Distributed Generation

• At present CHP is the most significant type of embedded generation and simultaneously produces

electrical power and useful heat.

• Generally the electrical power is consumed inside the CHP premises, although power may be

exported or imported from the distribution system.

• The heat which is generated is used in industrial processes, space heating and/or district heating.

• Various technologies may be used in CHP plants  –  reciprocating IC engines, steam-turbines, gas-

turbines etc.

Source: Jenkins, N., Allen, R., Crossly, P., Kirschen, D. and Strbac, G. Embedded Generation. IEE Power and Energy Series 31

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Electric and Hybrid Vehicles• Improved Vehicle Efficiency

• Different types of machines can be used for traction :

• Induction Motors

• PM Brushless DC

• PM Brushless AC

• Switched Reluctance

• Highly cost-competitive environment

• Demanding torque speed characteristics and

operating environment

• Electrical Machines are also increasingly being used

for :

• Electrically Assisted Turbocharging (very high speed

machines)

• Electrical Power Steering (low torque ripple

requirement)

• Waste energy recovery

In-wheel motors by Porsche - 1900

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Marine Propulsion

More Electric Propulsion

• Fewer installed/running prime

movers

• Electrical interconnectivity provides

greater operational flexibility

• Reduced manning and life-cycle costs

• Ship layout flexibility

• Reduced vulnerability

Conventional Mechanical

Propulsion

• Numerous gas-turbine (GT) and diesel

generator (DG) units

• Prime-movers remote from propellers

due to ship layout constraints

• Limited operational flexibility

Rolls-Royce - Podded propulsor- The unit acts as a propulsor and rudder, with

an integrated electric motor located within the hydrodynamically optimisedhousing driving the shaft

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Power Sources “Conventional” Aircraft 

Jet Fuel

Propulsion

Thrust (  40MW)

Gearbox driven

hydraulic pump

Electrical

Gearbox driven

generators

Hydraulic

High pressure

air “bled” from

engine

Pneumatic

Fuel pumps

and oil pumps

on engine

Mechanical200kW 1.2MW 240kW 100kW

Total “non-thrust” power 1.7MW

Figures for a typical A320/B737 size aircraft

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“More Electric Aircraft” Concept 

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‘More-Electric’ Aircraft Machines 

• Note the relative power transmission capabilities of hydraulic and electrical systems.

Area: 64.52 mm2

Pressure: 13.79 Mpa

Velocity: 0.3m/s

Area: 64.52 mm2

Current density: 9.3 A/mm2 

Voltage: 270 V

Power = 267 W

• Challenges for electro-mechanical actuators EMAs.

• High power density motors and converters

• High speed motors have high inertial energy storage

• Gear jamming potential

• Cooling Methods

• Reliability of power electronics

• Drive Integration

• Fault tolerance

• Sensors

•

Diagnostics

Power = 162, 000 WHydraulic Line Electric Cable

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Fundamental matters

1. What constitutes an electrical machine?

2. Why are there different forms?

3. How do they work?

4. How can I analyse the method of working of a particular machine

type?

5. How big will a machine have to be to deliver a particular power?

6. How do I deal with the losses?

7. What do I need to know to use a particular machine type?

8. How do I control a machine to achieve the required performance?

9. How do I design an electrical machine?