Soft Magnetic Composite Axial Flux Seven-Phase Machine
ICEM2006-CHANIA
Soft Magnetic Composite Axial Flux Seven-Phase Machine F. Locment, E. Semail and F. Piriou Laboratory of Power Electronic of Lille 1/21
ENSAM & University of Lille, France
Soft Magnetic Composite Axial Flux Seven-Phase Machine
Outline
ICEM2006-CHANIA
I> Introduction
II> Machine: 3d-modelling and experimental results 6 EXPERIMENTAL 3D-FEM
Cogging torque (Nm)
4 2 0 -2 -4 -6 0
5
10
15
Position (°)
III> Drive : experimental torque DC
0
drive motor Torque
Repartition
Tref
iM1qref
of reference
0
torques
iM2qref 0 iM3qref
2/21
R(θ) +-
PI +-
PI R(9θ) +-
PI +-
cospθ − sin pθ R(θ) = sin pθ cospθ
R(3θ) +-
PI
M3α M3β
M2α M2β
vM2βref
R-1(θ)
iM2d iM2q
iM3q
vBref vCref
[C7 ]
vDref
PWM
7-Phase
vEref
VSI
AFPM
vFref vGref
vM3βref iM1α
M1α M1β
iM1β
M3α M3β
M2α M2β
iM2α R-1(9θ)
[C7 ]
−1
iM2β iM3α
R-1(3θ)
iM3β ABCDEFG
encoder
vAref
ABCDEFG
iM3d
Optical
M1α M1β
vM1βref
vM3αref
PI
iM1q
AFPM
vM1αref
vM2αref
iM1d
transducer
IV> Conclusion
PI
+-
θ
iA,iB,iC,iD,iE,iF,iG
Soft Magnetic Composite Axial Flux Seven-Phase Machine
I. Introduction Why such a seven-phase axial-flux Machine ? ICEM2006-CHANIA
Axial or radial Flux Machine ? Earliest machines are axial-flux machines (Faraday 1831) Reasons for shelving axial-flux machines? Manufacturing difficulties and corresponding high costs : • for control of uniform air gap (axial magnetic attraction) • for laminated sheets and slot of the stator
3/21
Iron lamination enrolled and compacted as a spiral
Soft Magnetic Composite Axial Flux Seven-Phase Machine
I. Introduction Why a SMC Axial Flux Seven-Phase Machine ? ICEM2006-CHANIA
Axial or radial Flux Machine ? 1>Earliest machines are axial-flux machines (Faraday 1831) 2>Reasons for shelving axial-flux machines? Manufacturing difficulties and corresponding high costs : • for control of uniform air gap (axial magnetic attraction) • for laminated sheets and slot of the stator core Not easy to cut slots in a stator made with iron lamination enrolled and compacted as a spiral 4/21
Soft Magnetic Composite Axial Flux Seven-Phase Machine
I. Introduction Why a SMC Axial Flux Seven-Phase Machine ? ICEM2006-CHANIA
Axial or radial Flux Machine ? 1>Earliest machines are axial-flux machines (Faraday 1831) 2>Reasons for shelving axial-flux machines? Manufacturing difficulties and corresponding high costs : • for control of uniform air gap (axial magnetic attraction) • for laminated sheets and teeth of the stator • for windings arrangement : asymmetry
5/21
Problem of space with end windings at inner radius
Soft Magnetic Composite Axial Flux Seven-Phase Machine
I. Introduction Consequences of manufacturing difficulties ICEM2006-CHANIA
1> Use of Soft Magnetic Composite ? 3D magnetic property easy to cut slots
6/21
New process of fabrication
Soft Magnetic Composite Axial Flux Seven-Phase Machine
I. Introduction Consequences of manufacturing difficulties ICEM2006-CHANIA
2> Simple arrangements of the winding Toroidal winding
No distributed winding
Concentrated winding
flux linked by one phase is not sinusoidal Consequence for 3-phase axial machine 7/21
Non-sinusoidal Electromotive forces except with special shapes of magnets
No performant vector control with weak torque ripples
Soft Magnetic Composite Axial Flux Seven-Phase Machine
I. Introduction
ICEM2006-CHANIA
Two interesting points of multiphase machines: 1. performant vector control with weak torque ripple even with non-sinusoidal emf 2. intrinsically fault-tolerant machine (already used in electrical ship, future offshore wind generator ?)
T
u s o
m
up
For performant vector control (torque quality) Multiphase machines impose less constraints on the designer than three-phase machines
8/21
It is particularly interesting for axial-flux machines.
ICEM2006-CHANIA
Soft Magnetic Composite Axial Flux Seven-Phase Machine
Characteristics of the machine
9/21
Soft Magnetic Composite Axial Flux Seven-Phase Machine
II. Characteristics of the machine
ICEM2006-CHANIA
Two rotors, 6 poles, a SMC stator with 42 slots
MAGNETS ROTORS COILS
STATOR
mm 189
287mm
10/21
ATOMET EM1(QMP)
NdFeB N48
Soft Magnetic Composite Axial Flux Seven-Phase Machine
II. Characteristics of the machine N
S
Φ
Seven phases with toroidal winding
Φ
S
ICEM2006-CHANIA
N
S
N
(a) NN type
N
S
(b) NS type
1 slot/pole/phase
No filtering effect
Nominal power at 750 rpm (kW) 5 Nominal Torque with 50°C in coil (Nm) 65 Nominal Speed (rpm) 750 Nominal current at 65 Nm (A) 5 • 4/5 arc pole for the magnet repartition: cancellation of the fifth harmonic of emf • shift of one slot (mechanical angle 4.3°) between the two rotors : reduction of the cogging torque 11/21
Soft Magnetic Composite Axial Flux Seven-Phase Machine
II. Characteristics of the machine
ICEM2006-CHANIA
Determination of the characteristics? 1>Classical analytical modelling by determination of average flux magnetic density in airgap for determination : • of main geometrical characteristics • rms value of main harmonic of emf.
2> 3D-Finite Element Method for determination of more sensitive characteristics: • cogging torque ; • harmonics of flux magnetic density and emf ; 12/21
Soft Magnetic Composite Axial Flux Seven-Phase Machine
II. Characteristics of the machine
ICEM2006-CHANIA
With a shift of 4.3° between the two rotors
60°
airgap magnetic flux density by 3D-FEM (Carmel) for 1rd/s
6 % of error on the first harmonic
Electromotive force 13/21
Electromotive force
Soft Magnetic Composite Axial Flux Seven-Phase Machine
II. Characteristics of the machine Cogging Torque 0.25 p.u.
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Peak value 0.06 in p.u.
3D-FEM cogging torque
14/21
without and with shift
Comparison of cogging torques
between rotors
with shift between rotors (experimental and simulation)
ICEM2006-CHANIA
Soft Magnetic Composite Axial Flux Seven-Phase Machine
Characteristics of the drive
15/21
Soft Magnetic Composite Axial Flux Seven-Phase Machine
III. Characteristics of the drive 7-leg Voltage
ICEM2006-CHANIA
Source Inverter
Dspace 100 5 controller board
7-phase axial-flux Supply electron ic charge
16/21
Back-ground with DC motor, seven-phase machine and torque transducer (MAGTROL TM211)
Soft Magnetic Composite Axial Flux Seven-Phase Machine
III. Characteristics of the drive
ICEM2006-CHANIA
Multi-machine modelling of a seven-phase machine
ell W wn o kn
Wye-coupled
ONE 2-phase machine (d,q)
3-phase machine Sinusoidal emf required for 2-phase machine for vector control
on i t za i l ra e n e G
17/21
Wye-coupled 7-phase machine
THREE 2-phase machines mechanically and electrically coupled
Sinusoidal emf required for EACH 2-phase machine
Soft Magnetic Composite Axial Flux Seven-Phase Machine
III. Characteristics of the drive Fictitious 2-phase Families of odd machines harmonics M1 1, 13, 15, 27, …, M2 M3
5, 9, 19, 23, …, 3, 11, 17, 25, …,
M1
EXPERIMENTAL 3D-FEM
80
Back-emf (%)
ICEM2006-CHANIA
100
M3
60
40
M2 20
0 0 1
3
5
7
9
11
13
15
17
19
21
23
Order of harmonics
1>Only one harmonic/2-phase fictitious machine (as for classical 3-phase machine)
Ideal emf with only the 1st, the 3rd and the 5th harmonic
2>For good ability in open-phase fault operation 18/21
smallest emf for M2
Soft Magnetic Composite Axial Flux Seven-Phase Machine
III. Characteristics of the drive
ICEM2006-CHANIA
Synoptic of the 7-phase vector control 0
Repartition
Tref
R(θ) +-
iM1qref
PI +-
0
of reference
PI R(9θ) PI
0
R(3θ) +-
iM3qref
PI
iM1q
[C 7
19/21
]=
2 7
1 2 1 2 1 2 1 2 1 2 1 2 1 2
1
0
1
0
2π 7 4π cos 7 6π cos 7 8π cos 7 10π cos 7 12π cos 7
2π 7 4π sin 7 6π sin 7 8π sin 7 10π sin 7 12π sin 7
4π 7 8π cos 7 12π cos 7 16 π cos 7 20π cos 7 24π cos 7
4π 7 8π sin 7 12π sin 7 16π sin 7 20π sin 7 24π sin 7
cos
sin
cos
sin
1 cos cos cos cos cos cos
6π 7 12π 7 18π 7 24π 7 30π 7 36π 7
0 sin sin sin sin sin sin
6π 7 12π 7 18π 7 24π 7 30π 7 36π 7
R-1(θ)
[ C7 ]
vDref
PWM
7-Phase
vEref
VSI
AFPM
vFref vGref
M1 i M1β
M1α M1β M2α M2β M3α M3β
iM2α R-1(9θ)
iM3d iM3q
vBref vCref
vM3βref iM1α
iM2d iM2q
vAref
ABCDEFG
iM1d
cos pθ − sin pθ R(θ) = sin pθ cos pθ
vM2βref
M3α M3β
vM3αref
PI
+-
M1α M1β M2α M2β
vM1βref vM2αref
+-
iM2qref
torques
vM1αref
PI
+-
M2 [C7 ]
−1
iM2β
iM3α R-1(3θ)
M3 i M3β
ABCDEFG
θ
iA,iB,iC,iD,iE,iF,iG
Soft Magnetic Composite Axial Flux Seven-Phase Machine
III. Characteristics of the drive Currents in one phase for two cases
Measured mechanical torques
ICEM2006-CHANIA
Only M1 machine supplied
- 65 Nm -70 Nm
M1 and M3 supplied Amplitude of 0.04 p.u. 20/21
(1st and 3rd harmonics) for pulsating torque
Soft Magnetic Composite Axial Flux Seven-Phase Machine
IV. Conclusion • If vector control and weak torque ripples are required
Multiphase axial-flux machines are very interesting because sinusoidal emfs are not necessary. Pr ot ot yp e
ICEM2006-CHANIA
• If axial spatial constraints are imposed
For the quality of torque, the seven-phase drive presents good characteristics in agreement with predeterminations obtained by 3D-FEM
Performance of the drive with two open phases? Other paper in poster session: « A Vector Controlled Axial-flux Seven-phase Machine in Fault Operation” 21/21
Soft Magnetic Composite Axial Flux Seven-Phase Machine
IV. Conclusion • If vector control and weak torque ripples are required • If axial spatial constraints are imposed ICEM2006-CHANIA
Multiphase axial-flux machines are very interesting because sinusoidal emfs are not necessary. For the quality of torque, the seven-phase drive presents good characteristics in agreement with predeterminations obtained by 3D-FEM For the efficiency of the drive and its thermal limits, further investigations on materials and modelling must be achieved to predict the obtained results. 22/21
