I © The Switch 2011 1

PERMANENT MAGNET MATERIAL PROPERTY

CRITERIA IN WIND POWER APPLICATION 14th of June 2012

I © The Switch 2011 2

CONTENTS

The Switch

Turbine technology

Generator types

PMG rotor designs for WP

Demagnetization risk

Usage of magnets in different generator types

Other requirements for magnetic circuit in

generators

Cost reduction options

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“We are setting the standard for modern drive train

technology. Currently, we are in close to 20 wind turbine designs and are building the capacity for them.”

– Jukka-Pekka Mäkinen,

President and CEO

BUSINESS

3 I © The Switch 2011

WIND POWER EMERGING BUSINESSES

Solar & fuel cell converters

Variable speed genset drive trains

Industrial electrical drive trains

THE SWITCH AREAS OF

OPERATION

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THE SWITCH DRIVE™

The soul of every reliable wind turbine

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LOCATIONS

The Switch

Hudson, NH,

USA

The Switch

Headquarters

Vantaa, Finland

The Switch

Beijing, China The Switch

Lu’an, Anhui,

China

Medium Size Electrical

Machines

Deyang, Sichuan, China

The Switch

Lappeenranta,

Finland The Switch

Vaasa, Finland

The Switch

Chennai,

India

The Switch

Gumi-City,

Korea

The Switch

Hong Kong, China

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Hangzhou, China

The Switch

Barcelona, Spain

The Switch

Hamburg,

Germany

The Switch

Silkeborg,

Denmark

6 I © The Switch 2011

WIND TURBINE

Turbine automation

• Yaw control

• Pitch control

• Speed control

• Torque control

Electric drive

• Traditional wind turbine:

Gear + high speed IM

• Direct drive without gear

Source:http://windeis.anl.gov/guide/basics/turbine.html

AN EXAMPLE

1. Cooler

2. Generator

3. Automation

4. Anemometer

5. Coupling

6. Mechanical brake

7. Gearbox

8. Main shaft

9. Yaw gear

10. Machine bed

11. Main bearing

12. Hub control

13. Pitch controller

14. Blade

Source: Vestas V82-1.65 MW broshure

TYPICAL POWER CURVE:

V82-1.65 MW

Source: Vestas V82-1.65 MW broshure

GENERATOR OPTIONS

Double fed induction generator

Directly net coupled induction machine

Electrically excited synchronous generator Permanent magnet synchronous generator

PRODUCT PORTFOLIO POWER

SPEED

1.0

2.0

3.0

4.0

5.0

6.0

LOW MEDIUM 1500 1000

3.3 MW/13 rpm

4.25 MW/16 rpm

1.65 MW/17 rpm

1.65 MW/120 rpm

3.3 MW/136 rpm

1.65 MW/150 rpm

5.9 MW/1100rpm

5.6 MW/1200rpm

3.3 MW/1000 rpm

3.3 MW/1500 rpm

2.7 MW/1000 rpm 2.7 MW/1500 rpm

2.2 MW/1500 rpm 2.2 MW/1000 rpm

1.6 MW/1000 rpm 1.6 MW/1500 rpm

1.1 MW/1000 rpm 1.1 MW/1500 rpm

3.2 MW/414 rpm

1.4 MW/292 rpm

3.3 MW/365 rpm

FD: 3.2 MW/346 rpm

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Options GENERATOR CONSTRUCTION

HS DD MS In standard platform

Option

Turbine

technology

Low-speed/

Direct driven

Medium-

speed

High-speed

Machine

construction

Inner rotor

Outer rotor

Cooling

arrangement

IP 54

Air/air

IP54

Air/water

IP23

Magnet

assembly

Surface-mounted

magnet modules

Surface-mounted

magnets

Embedded

magnets

Winding

Random

wound

Form

wound

Litz

wire

Voltage

Low voltage

Medium

voltage

DIRECT-DRIVE GENERATORS

• Increasing efficiency towards partial loads

• Best overall drive-train efficiency

• No gearbox, no fast-rotating parts

→ Increased reliability

• Highest torque density due to large cooling area in active parts

• Mechanical interface design for turbine in co-operation with turbine

designer

• Generator bearing can act as a turbine main bearing

• Large generator size due to high torque

• Possibility to integrate break system to generator construction

kW

86

88

90

92

94

96

0 1000 2000 3000 4000 5000

Eff

icie

nc

y (

%)

DIRECT-DRIVE GENERATORS

1.65 MW direct-drive outer rotor

Generator Frame size: 2250

3.3 MW, 13 rpm direct-drive outer rotor

generator. Frame size: 3000

Outer rotor generators

DIRECT-DRIVE GENERATORS

4.25 MW, 16 rpm direct-drive generator in test setup

Frame size: 3150

Down wind generators

GEARED GENERATORS

• 1- or 2-stage gearbox

• Generator speed is usually 100 to 500 rpm

• Typically flange mounting between generator

and gearbox

• Integrated drive train with a simplified

structural design (FusionDrive®)

• Lowest nacelle weight

• Improved total turbine cost effectiveness

Medium speed generators

High-speed generators

GEARED GENERATORS

• 1000 to 2000 rpm speed range with 3-stage gearboxes

• Small generator size, high efficiency

• Stand-alone component

→ Can be used with different turbine designs

• Rotor has embedded magnets

→ Well protected against centrifugal forces and corrosion

• Typically leg-mounted

• Air-to-air or air-to-liquid cooling

• Easily possible to replace existing DFIG without changing nacelle layout

• Requires heavy gearbox with high-speed shaft

GEARED GENERATORS

5.9 MW, 1100 rpm

Frame size: 710

2.2 MW, 1500 rpm

Frame size: 500

High-speed generators

ROTOR DESIGN

• For direct –drive

• and medium-speed generators:

• → Allow the maximum power to be captured from the magnet

• Maximum flux in air gap

• Typically protected with a module construction (hermetically sealed)

• Must be firmly fastened against centrifugal forces

Magnet modules in an outer rotor

direct-drive generator

3.3 MW medium-speed

generator

Surface mounted magnets

ROTOR DESIGN

• For high-speed generators:

• Magnets are built inside a sealed corrosion-resistant metal enclosure

• No threat due to centrifugal forces

• Hermetic sealing provides protection from the environment

(rotor is impregnated)

• Tangentially multiple magnets / pole

3.3 MW high-speed generator rotor

Embedded magnets

Magnet grade

Most critical raw materials:

Neodymium (Nd) mainly to increase remanence flux (together with

Praseodym; PrNd ~50 €/kg (5/2012)

Dysprosium (Dy) to increase coersivity (demag. resistance); FeDy

~550 €/kg

Terbium (Tb) to increase coersivity; ~1200 €/kg

Grade Dy PrNd Tb Typical use

4X SH 3...4 % 26...27 % 0 Direct drive

40 UH 5...6 % 25...26 % 1...2 % Medium speed

38 EH 3...4 % 24...25 % 2...3 % High-speed

Raw material sources outside China Case study with nine mines / known recourses

Mine Country Location Company

1 Australia Dubbo Alkane Recources Ltd

2 Australia Nolans Arafura Recources Ltd

3 Canada Nechalacho Avalon Rare Metals Inc

4 Canada Hoidas lake Great Western Minerals Group

5 South Africa Steenkampakraal Great Western Minerals Group

6 Greenland Kvaenefjeld Greenland Minerals & Energy Ltd

7 Australia Mt. Weld Lynas

8 USA / Ca Mt. Pass Molycorp Minerals LLC

9 USA / Wo Bear Lodge Rare Element Recources Ltd

RE recources in 9 mines (kton):

3 MW PMG consumes RE-materials (not magnets):

- Direct Drive 800 kg

- Medium speed 130 kg

- High speed 80 kg

Pr 489

Nd 1606

Tb 20

Dy 104

Sum 2220

DD MS HS

PrNd 8980 56125 114292 GW

Dy 2628 16425 12483 GW

Generator capasity built with 9 mines recources:

Demagnetization Magnet grade is selected based on the demagnetization

calculation

External field

Rotor temperature

Typical factors

Rated frequency / speed (HS worst – DD easiest)

Air-gap length

Tangential tention

4MAGNETS_MOD1

-250

0

250

100 200 300

mm

(E-3) Tesla

CURVE C2D_13Flux density / Normal componentPath_5 Time (s.) : 0,038

TOIM_P12_NL

-200

-99,999

0

100

200

300

0 50 100

mm

(E-3) Tesla

CURVE C2D_5Flux density / Normal componentPath_1 Time (s.) : 26,1E-3

3PH_SC_HOT

200

300

400

500

600

700

0 50 100

mm

(E-3) Tesla

CURVE C2D_232Flux density / Normal componentPath_1 Time (s.) : 184,799999E-3

HS

MS

DD

Critical level 100 °C

Demagnetization risk Typical requirements (worst case):

Max ambient temp ~45 °C => max rotor temperature

Min 12 m/s wind

Short circuit in terminal box

Against present design criteria says:

Places where the above conditions is even theoretically possible are few

A short circuit in terminal box or winding would destroy the machine anyway. In

case of a short circuit further away cable impedance will restrict the sc-current and

field

Statistical reasons

Other typical requirements in WP Life time 25 years (< 2% flux reduction)

< 1% ( or even < 0.5 %) cogging

Magnet shape

Skewing

Rotor

Stator

Forming Air-gap shape

Asymmetry

Rotor poles

Stator slots

IP54 construction (rotor typically requires air circulation for cooling)

Sea environment (salt)

REDUCING MAGNET GRADE (COST) BY

DIRECT COOLING WITH INPUT FILTER

Typical requirement IP54 =>

Water jacket (+ air circulation)

Internal air circualtion + heat exchanger

Replace HEX with Goretex filter and exhaust pipe

10...15 °C cooler air for cooling => upgrade or lower grade

magnets

Is applicable for symmetric or asymmetric cooling arrangement

Filter has to be changed every 3...5 years

Is not real IP54

Requires change of thinking

EXAMPLE ON DE-RATING • Normally generator is designed for

worst possible operating conditions

that occur very rarely (blue circle =

rated point)

• By lowering the design temp by 10

°C, generator would be able to deliver

3.3 MW (green circle = rated point)

• How often the ambient really exceeds

40 °C while there is nearly full wind?

In europe once a year?? Now the

generator designs are according to

such conditions

• Each drop of ~20 °C enables using

one grade cheaper magnets

0

20

40

60

80

100

120

140

0 10 20 30 40 50 60

Po

wer

[%

]

Ambient temperature [°C]

2.5 MW HS-turbine alternatives

Currentdesign

Increasedpower

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Äyritie 8 C

FI-01510 Vantaa, Finland

Tel +358 20 783 8200

Fax +358 20 783 8570

Thank You