Control of a 7-phase Machine in Fault Mode Operation
IECON 2006
Control of a Seven-phase Axial Flux Machine in Fault Mode Operation F. Locment, E. Semail, X. Kestelyn, A. Bouscayrol Laboratory of Power Electronic of Lille 1
ENSAM & University of Lille, France
Control of a 7-phase Machine in Fault Mode Operation
Outline A G B
51, 43°
I> Introduction
F C
E
D
IECON 2006
II> 7-phase drive with special design for fault operation III> Opening two phases: effect on the torque of the vector controlled 7-phase machine IV> Improved vector control when only 5 phases are supplied vM1
iM1
VBUS
iM1 vM2
iM2
iBUS
iM2
SE
V> Conclusion 2
vM3
iM3
M1 eM1
M2 eM2
M3 m
iM3
eM3
TM1
Ω TM2 Ω TM3 Ω
T
Ω
SM Ω
TLoad
Control of a 7-phase Machine in Fault Mode Operation
I. Introduction Reliability required for the drives of on-board systems such as IECON 2006
automotive, aircraft, marine propulsion, offshore windgenerator Mean Time Between Failure (MTBF) ? Electronic Power Devices are the most critical part of the drive Effect of a failure ? Phases of the machine are opened Critical for wye-coupled 3-phase machines 3
Control of a 7-phase Machine in Fault Mode Operation
I. Introduction Intrinsic reliability of multi-phase machines Why seven phases ? IECON 2006
• using the third harmonic of emf for the torque •smooth torque in fault mode operation (two open phases) • reasonable number of connexions A
30 °
G
jsA2 jsB2
i1
jsB1
B
51, 43°
v1
α
α i5
v2
jsA1
i2
F C
jsΑ3
vn (k-2)α
S
vk
jsΒ3
4
N
6-phase
E
D
7-phase
ik
5-phase
Control of a 7-phase Machine in Fault Mode Operation
I. Introduction What happens when only 5 phases are supplied ?
IECON 2006
J Average Torque BUT
L Torque Ripples
Challenges ? 1> Reducing the torque ripples by control 5
2> Finding a friendly machine for fault operation
Control of a 7-phase Machine in Fault Mode Operation
A machine
A G
specifically IECON 2006
B
51, 43°
F C
designed E
D
for fault operation Special spectrum of electromotive force 6
Control of a 7-phase Machine in Fault Mode Operation
II. The 7-phase drive
IECON 2006
Axial flux PM machine, with two rotors
7-leg Voltage Source Inverter
Dspace 100 5 controller board
7-phase axial-flux Supply electron ic charge
7
Back-ground with DC motor, seven-phase machine and torque transducer (MAGTROL TM211)
Control of a 7-phase Machine in Fault Mode Operation
II. The 7-phase drive N
S
Φ
Φ
S
N
IECON 2006
(a) NN type
N
1 slot/pole/phase
S
(b) NS type
No filtering effect
Rated Torque with 50°C in winding (Nm)
65
Rated current at 65 Nm (A) 4/5 arc pole for the
5
magnet repartition
8
Seven phases with toroidal winding
N
S
6 poles
t l u a rf o f g n i t s n re o e i t t a n r I e p o
5
cancellation of the fifth harmonic
Control of a 7-phase Machine in Fault Mode Operation
II. The 7-phase drive Synoptic of the 7-phase vector control
IECON 2006
0
Repartition
Tref
of reference torques
iM1qref 0 iM2qref 0
vM1αref
PI
+-
R(θ) +-
PI +-
R(9θ) PI
+-
R(3θ) +-
PI
iM1q
9
A generalization of 3phase vector control in dq-reference frame
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
+-
iM3qref
M2α M2β
vM1βref vM2αref
PI
M1α M1β
M2 [C7 ]
−1
iM2β
iM3α R-1(3θ)
M3 i M3β
ABCDEFG
θ
iA,iB,iC,iD,iE,iF,iG
Control of a 7-phase Machine in Fault Mode Operation
A
Effect of opening
G B
51, 43°
IECON 2006
two phases
F C
on a vector controlled 7-phase machine 10
E
D
Control of a 7-phase Machine in Fault Mode Operation
III. Vector controlled 7-phase machine: effect of a fault 5 4
Phases A and B are opened
3
Currents (A)
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2 1 0 -1
EN TS
-2
-5 0
iA 0.02
0.04
0.06
iB 0.08
iC
iD 0.1
iE 0.12
iF
iG 0.14
Time (s) 11
Measured 7 measured currents currents in normal in faultoperation operation without change of control
CU
-4
RR
-3
Control of a 7-phase Machine in Fault Mode Operation
III. Vector controlled 7-phase machine: effect of a fault Experimental torques in the seven-phase machine
In normal operation
50 40
Torques (Nm)
In fault operation
20
S E U Q R O T
10 0
normal mode (NM) without modification (DM1) with modification (DM2)
-10 -20 0
Spectral analysis of torques 25 normal mode (NM) without modification (DM1) with modification (DM2)
)
0.02
0.04
0.06
0.08
0.1
0.12
0.14
20
Time (s)
Interaction between the nonsymmetrical system of currents and the symmetrical system of 12 electromotive forces
Torques (Nm)
IECON 2006
30
15
10
5
0
0
1
2
3
4
Order of harmonics
5
6
Control of a 7-phase Machine in Fault Mode Operation
Improved control thanks to IECON 2006
a Multi-machine concept 50 40
Torque with improved control
Torques (Nm)
30 20
0
normal mode (NM) without modification (DM1) with modification (DM2)
-10 -20 0
13
S E U Q R O T
10
0.02
0.04
0.06
0.08
Time (s)
0.1
0.12
0.14
Control of a 7-phase Machine in Fault Mode Operation
III. Improved vector control with 5-phase supplied Tools to get the results ?
IECON 2006
* Vectorial formalism: important for high number of phases ; * Graphical Energetic Macroscopic Representation; For a wye-coupled 3-phase PM machine
Electrical source
ibus
im
vm
Vbus
im
Voltage Source Inverter
Tm
Ω
Ω
Tload
MM
em RM 1iM 1 + LM 1
diM 1 = vM 1 − eM 1 dt
Equivalence of a 3-phase machine to 14
a 2-phase machine ( d-q components)
im . em = Tm Ω
Mechanical load
Control of a 7-phase Machine in Fault Mode Operation
III. Improved vector control with 5-phase supplied uur uur diM1 uuur uuur RM1iM1 + LM1 = vM1 − eM1 dt vM1 iM1
IECON 2006
VBUS
vM2
uuur uur eM1.iM1 = TM1.Ω iM1
iM2
M1 eM1
M2
SE iM2
iBUS
vM3
iM3
eM2
M3 iM3
m
DC bus
Electrical coupling
eM3
Fictitious machine
T = TM1 + TM2 + TM3 TM1 Ω TM2
T
SM
Ω TM3
Ω
FΩ + J
Ω
Mecanical coupling
Equivalence of a 7-phase machine to 15
Ω
a set of 3 2-phase machines
TLoad
dΩ = T − TLoad dt
Load
Control of a 7-phase Machine in Fault Mode Operation
III. Improved vector control with 5-phase supplied Basic original idea 6 freedom degrees : IECON 2006
Wye-coupled 7 phase machine
control of the 3 2-phase machines 4 freedom degrees :
In case of 2 open phases
control of only 2 2-phase machines which ones?
Impossible to control the currents in one of the three machines 16
No torque ripples in this machine if its EMF = 0
Control of a 7-phase Machine in Fault Mode Operation
III. Improved vector control with 5-phase supplied Fictitious 2-phase machines M1
Families of odd harmonics 1, 13, 15, 27, …,
M2
5, 9, 19, 23, …,
M3
3, 11, 17, 25, …,
IECON 2006
7h ± 132
100
M1
EXPERIMENTAL 3D-FEM
Cancellation of the fifth harmonic
Back-emf (%)
80
M3
60
40
M2 20
17
0 0 1
3
5
7
9
11
13
15
Order of harmonics
17
19
21
23
Control of a 7-phase Machine in Fault Mode Operation
III. Improved vector control with 5-phase supplied Choice:
Opening of two phases
torque can be imposed
IECON 2006
by M1 and M3 Physical mandatory currents of M2?
Solution for M2 currents 18
iM 1α iM 1β iM 3α i M 3β
= I M 1 sin (ω t ) = − I M 1 cos (ω t ) =0 =0
0 0 iA I sin ( ) i 0 ωt B M1 iC − I M 1 cos (ωt ) iC i i = = [C7 ] . iM 2α D D i iE iM 2 β E iF 0 iF 0 iG − ( iC + iD + iE + iF )
iM 2α = − I M 1 sin (ω t ) iM 2 β = 0.801938I M 1 cos (ω t ) − 0.867767 I M 1 sin (ω t )
4+2 current references for the PI controlers
Control of a 7-phase Machine in Fault Mode Operation
III. Improved vector control with 5-phase supplied By the cancellation of the emf fifth harmonic
IECON 2006
No torque produced by the fictitious M2 machine even if supplied
Without changing modeling of the 7-phase machine No torque ripples by change of M2 reference currents Constant torque references for M1 and M3
19
Control of a 7-phase Machine in Fault Mode Operation
IV. Conclusion Vector control for a 7-phase machine
IECON 2006
Smooth torque even with non-sinusoidal emf
Vector control with two open phases Average torque but torque ripples
Modified Vector control with two open phases A smooth torque can be obtained in this machine when one or two phases are opened thanks to : •slight modification of the DESIGN of the machine 20
•slight modification of the control
