9/15/20141

Md Zarafi Ahmad, Erwan Sulaiman, Zainal Alam

Haron, Faisal Khan, and Mubin Aizat Mazlan

Dept. of Electrical Power Engineering

Faculty of Electrical and Electronic Engineering

Universiti Tun Hussein Onn Malaysia

World Virtual Conference on Advanced Research in

Mechanical and Materials Engineering, 2014

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OUTLINES

1• Introduction

2• Design Restrictions and Specifications

3

• FEA-Based Performance Analysis• Improved Design Structure

• Flux Characteristic at Various Current Densities

• Cogging Torque

• Induced Voltage

• Torque and Power Profile

4 • Conclusion

INTRODUCTION

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Fig. 1 Classification of electrical machines

INTRODUCTION

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• High performance application of AC

machines required:

i. High torque density

ii. High power density

iii. High reliability

iv. High efficiency

INTRODUCTION

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• Previously, the

interior permanent

magnet

synchronous

machines (IPMSM)

are mostly used in

electric vehicle (EV)

A better machine such as flux switching machine (FSM) is selected

5. Complex structure

Problems of IPMSM

4. Low rotor mechanical strength- Necessity of large no. of bridges- Less robust in high speed condition

1. Distributed armature windings - Longer coil end length- High copper loss

3. High PM volume (1.1kg)

2. Constant PM flux

INTRODUCTION

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• However, most of research done on FSMs are focused

on inner-rotor configuration and hard to find report on

outer-rotor configuration.

• Lately, an outer-rotor PM FSM for in-wheel drive has

been proposed for light traction EV applications

• Nonetheless, with constant PM as a main flux

source, it also may suffer from demagnetization and

un-controllable flux.

• Thus, this research presents analysis of a new dual

excitation flux switching machine (DEFSM) with outer-

rotor configuration for In-Wheel Drive EV. PM

DC Field Excitation

DESIGN CONDITIONS AND SPECIFICATIONS

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Items Unit

Outer-

rotor

DEFSM

Geometrical

dimension

and volume

Motor diameter mm 264

Motor stack length mm 70

Shaft radius mm 30

Air gap length mm 0.8

PM weight kg 1.0

Input voltage

and current

Max. DC-bus voltage inverter V 650

Max. inverter current Arms 360

Max. armature current

density, Ja

Arms/mm2 30

Max. FEC current density, Je A/mm2 30

Output

performances

Maximum torque Nm 333

Maximum power kW 123

Machine weight kg 30

Power density kW/kg 4.1

Table I. Design conditions and specifications of outer-rotor DEFS Motor

DESIGN CONDITIONS AND SPECIFICATIONS

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Fig. 3 Initial design

Non-Overlap windingAC

PM Rotor

FEC

Rotor pole width = Stator

tooth width

PM and AC at least 1/3

of stator body

Rotor depth 15%-20% of

machine’s radius

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Design Improvement Process

Fig. 4 Design parameters

Fig. 5 Optimization process

Start

Deterministic Optimization

Tn (Nm), Pn (kW), (n=1)

n = n + 1

Vary rotor parameters

D1, D2, D3

Vary PM parameters

D5, D6

Vary FEC Slot Parameters

D7, D8

Vary Armature Slot

Parameters D9, D10

Tn = In +1

Pn = Pn + 1

End

No

Yes

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Fig. 6 Initial design Fig. 7 Improved design

Tmax = 243.52 Nm

Pmax = 110.31 kW

Tmax = 298.46 Nm

Pmax = 138.75 kW

3. Design Improvement Process

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FEA BASED PERFORMANCE ANALYSIS

-0.06

-0.04

-0.02

0

0.02

0.04

0.06

0 3 6 9 12 15 18 21 24 27 30 33 36

ϕ [Wb]

Rotor [º]

Je=0 Je=5 Je=10 Je=15

Je=20 Je=25 Je=30

-0.06

-0.04

-0.02

0

0.02

0.04

0.06

0 3 6 9 12 15 18 21 24 27 30 33 36

ϕ [Wb]

Rotor [˚]

Je=0 Je=5 Je=10 Je=15

Je=20 Je=25 Je=30

(a) Original design (b) Improved design

Fig. 8 U-phase flux linkage

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FEA BASED PERFORMANCE ANALYSIS

Fig. 9 Cogging torque Fig. 10 Back-emf

-5

-4

-3

-2

-1

0

1

2

3

4

5

0 3 6 9 12 15 18 21 24 27 30 33 36

T [Nm]

Rotor position [°]

Improved design Original design

-200

-150

-100

-50

0

50

100

150

200

0 3 6 9 12 15 18 21 24 27 30 33 36

Back-emf [V]

Rotor [°]

Improved design

Original design

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FEA BASED PERFORMANCE ANALYSIS

Fig. 11 Torque and Power vs Speed

0

20

40

60

80

100

120

140

160

0

50

100

150

200

250

300

350

0 5000 10000 15000 20000

P [kW]T [Nm]

Speed [r/min]

Improved design Initial Improved design Initial

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CONCLUSION

This paper has discussed and demonstrated the

design analysis improvement on 12slot-14pole

DEFSM with outer-rotor configuration.

Some improvement on the torque and power has

been achieved which give the torque density and

power density of 10.19 Nm/kg and 4.74

kW/kg, respectively.

Further design investigation and improvement will

be conducted to achieve the target performances of

torque and power.