Yliopiston
kampusalue
HYBRID EXCITATION
SYNCHRONOUS MACHINES
(HESMs)
FOR ISLAND OPERATION
Katteden Kamiev
Janne Nerg
Juha Pyrhönen
CONTENTS
• Introduction
• Classification
• Mechanical Considerations
• Radial Flux Machines
• Example Machine
• Finite Element Analysis
• Conclusion
• References
INTRODUCTION
Boundary conditions set e.g. by the marine classification societies
• The generator voltage must remain within ±10% in all cases
• The generator sustainable short circuit current must be three time
the rated current at least for two seconds
Short circuit current depends on the induced
voltage and the direct axis inductance
I sc,pu =
Ef,pu
Ld,pu
= 3 ⋅ I n,pu ,
where Ef,pu is the induced per unit voltage and Ld,pu is the per unit synchronous inductance.
CLASSIFICATION of HESMs
Combining excitation sources
• series hybrid excitation
• parallel hybrid excitation
Locations of PMs and
excitation coils
Classification of HESMs
PM+EW
PMs in the Rotor
EW
in the
Rotor
(Brushes/
Brushless)
EW
in the
Stator
(Brushless)
PMs in the Stator
EW
in the
Machine’s
End
(Brushless)
EW
in the
Stator
(Brushless)
Classification of HESMs
PMs and excitation coils
are located on the rotor side.
[4]-[7]
Synchronous/Permanent Magnet
Hybrid AC Machine
Combination Rotor
Hybrid Excitation
Machine (CRHE)
Classification of HESMs
PMs are in the rotor and
excitation coils are in the
stator. [8]
Consequent Pole PM Hybrid
Excitation Machine (CPPM)
PMs are in the rotor side and excitation
coils are in the machine’s end. [9]
Hybrid Excitation Machine with Powered
Iron Core
PMs and excitation coils
are in the stator. [10]
Hybrid Excitation Doubly
Salient Machine
Classification of HESMs
Operation Principle
Applications
HESM has two excitation sources. One
is the PM source that provides the airgap with constant flux and the other
one is the EW (DC current) that acts
as the flux regulator to adjust the air
gap flux distribution.
• as a generator it may be used in
an island operation
(alp, island, ship, etc.)
• as a motor HESM is attractive for
traction applications, for example,
in electric, hybrid electric and fuel
cell vehicles
Special Features
• two excitation sources which can be
connected either in series or in parallel
• location of PMs and excitation coils
• bi-directional DC current
Mechanical Considerations
Advantages of radial flux vs. axial flux construction
• The rotor of a radial flux machine may be more rugged than the rotor
of an axial flux machine
• Ideally, radial flux machine produces no axial forces
• Radial flux machine is easier to cool as the rotor can in some cases
be built as hollow
• Damper winding is easier to arrange in a radial flux machine
• The radial flux rotor dimensions may easily be adjusted to produce
a suitable inertia for the prime mover
Radial Flux Machines
The advantages of the SPM vs VPM
SPM
- Utilizes the PM material
best
- Magnets mechanically
vulnerable
- Damper winding
construction is complicated
- Low volume of magnets
because of only small
magnet stray flux
- Good damper properties
VPM
- High air gap flux density
- High efficiency
a)
b)
c)
- High armature reaction
- Mechanically rugged
- Higher magnet stray
losses
→ increase the volume of
magnets
d)
e)
f)
→ higher magnet price
- Good damper properties
Different rotor constructions of radial flux machines.
(a) Rotor-surface-mounted magnets, (b) magnets embedded
in the surface, (c) pole shoe rotor, (d) tangentially
embedded magnets, (e) radially embedded magnets, (f) two
magnets per pole in the V position.
EXAMPLE MACHINE
Structure
Design specifications
Cross-section view
Main geometry data
Parameter
Value
Unit
Parameter
Value
Unit
Phase number, m
3
-
750
mm
Nominal power, Pn
400
kW
Air gap
diameter, Ds
Length, l
400
mm
Nominal voltage, Un
400
V
Nominal current, In
725
A
Number of PMs
per pole
2
-
Power factor, cosφ
0.8
-
Rotational speed, n
750
rpm
Frequency, f
50
Hz
Number of
pole pairs, p
4
-
EXAMPLE MACHINE
Operation Principal
PM
EW
N
S
S
N
N
N
S
S
S
N
N
S
Magnetic flux paths due to PMs (blue lines)
and excitation coils (red lines)
Magnetic path of the PM flux: N pole
of the PM → PM pole body → air gap
→ stator tooth → stator yoke →
stator tooth → air gap → PM/EW pole
body → S pole of the neighbour
PM/own pole to form a loop.
Magnetic path of the flux due to the
electric excitation: pole of the
electric excitation → S pole of the
neighbour PM → PM pole → air gap
→ stator tooth → stator yoke →
stator tooth → air gap → electrically
excited pole to form a loop.
E = EPM + Ef
Finite Element Analysis
Flux lines of the HESM
Positive excitation current
Zero excitation current
Finite Element Analysis
600
1
Positive DC
Zero DC
Negative DC
400
Positive DC
Zero DC
Negative DC
0.8
200
Normal flux density [T]
Induced phase voltage [V]
0.6
0
-200
0.4
0.2
0
-0.2
-0.4
-0.6
-400
-0.8
-600
0
0.002
0.004
0.006
0.008
t [s]
0.01
0.012
0.014
0.016
Armature winding EMF waveforms
-1
0
100
200
300
400
500
x [mm]
600
700
800
Air gap flux density distributions
Finite Element Analysis
Short-circuit current as a function of time
CONCLUSION
HESMs
- combine advantages of PM machines and
traditional synchronous machines
- have different constructions
- have good flux control capability
- can increase the short-circuit current
REFERENCES
[1]. Hybrid Excitation Synchronous Machines: Energy-Efficient Solution for Vehicles Propulsion
Amara, Y.; Vido, L.; Gabsi, M.; Hoang, E.; Hamid Ben Ahmed, A.; Lecrivain, M.; Vehicular Technology, IEEE
Transactions on Volume 58, Issue 5, Jun 2009 Page(s):2137 - 2149
Digital Object Identifier 10.1109/TVT.2008.2009306
[2]. Direct control of air-gap flux in permanent-magnet machines
J. S. Hsu, IEEE Trans. Energy Convers., vol. 15, no. 4, pp. 361–365,Dec. 2000.
[3]. A new axial flux surface mounted permanent magnet machine capable of field control
M. Aydin, S. Huang, and T. A. Lipo, in Conf. Rec. IEEE
IAS Annu. Meeting, 2002, vol. 2, pp. 1250–1257.
[4]. A synchronous/permanent magnet hybrid AC machine
Xiaogang Luo; Lipo, T.A.;Energy Conversion, IEEE Transaction on Volume 15, Issue 2, June 2000
Page(s):203 - 210
Digital Object Identifier 10.1109/60.867001
[5]. Trial production of a hybrid excitation type synchronous machine
N. Naoe and T. Fukami,
Electric Machines and Drives Conference, 2001. IEMDC 2001.
IEEE International, pp. 545-547,2001.
REFERENCES
[6]. Design and test of permanent magnet synchronous motor with auxiliary excitation
winding for electric vehicle application
G. Henneberger, J. R. Hadji-Minaglou, and R. C. Ciorba
Proc. Eur. Power Electron. Chapter Symp., Lausanne, Switzerland,
Oct. 1994, pp. 645–649.
[7]. A double excited synchronous machine for direct drive application - Design and prototype tests
D. Fodorean, A. Djerdir, I. A. Viorel, and A. Miraoui,
IEEE Trans. Energy Convers., vol. 22, no. 3, pp. 656–665, Sep. 2007.
[8]. Consequent-pole permanent-magnet machine with extended field-weakening capability
Tapia, J.A.; Leonardi, F.; Lipo, T.A.;
Industry Applications, IEEE Transactions on
Volume 39, Issue 6, Nov.-Dec. 2003 Page(s):1704 - 1709
Digital Object Identifier 10.1109/TIA.2003.818993
[9]. Hybrid excitation machines with powdered iron core for electrical traction drive applications
Kosaka, T.; Matsui, N.;
Electrical Machines and Systems, 2008. ICEMS 2008. International Conference on 17-20 Oct. 2008
Page(s):2974 – 2979
[10]. Static characteristics of a novel hybrid excitation doubly salient machine
Chen Zhihui; Sun Yaping; Yan Yangguang;
Electrical Machines and Systems, 2005. ICEMS 2005. Proceedings of the Eighth International
Conference on Volume 1, 27-29 Sept. 2005 Page(s):718 - 721 Vol. 1
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