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Simulation Based Performance Characterization of an Electric Drive Train System
Authors: Zed (Zhangjun) Tang, Wendy Lei
Presenter: Scott Stanton
Ansoft LLC
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Electric Drive Train Configuration
Energy Storage Unit
Traction Motor
Generator
Drive Cycle
ICE Engine
Power Electronics
Control Unit
Electrical Grid
ICE: Internal Combustion Engine
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Electric Drive Train Example
300 Volt Battery Pack
2-Mode Transmission
Power Electronics
Full-Size SUV 2-Mode Hybrid
Controller
ICE
Traction Motor
Chevrolet Tahoe
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Electric Drive Train Applications
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Contents
• Efficiency Map of Traction Motor• Equivalent Circuit Model Extraction• Vector Controller• Conclusions• Future Work
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Basis for Research – 2004 Toyota Prius
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Contents
• Efficiency Map of Traction Motor• Equivalent Circuit Model Extraction• Vector Controller
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Efficiency Map of Traction Motor
Synchronous MotorPhasor Diagram
Synchronous MotorLosses
Q Axis D Axis
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Use Transient with Motion for Accurate Losses Calculation
Transient with Motion
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Eddy Losses on Permanent Magnets
Assign zero current to the permanent magnets:
Jtot = 0Apply boundary condition to each magnet
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Extract the Capability Curve of IPM
Idealized Torque vs. Speed Curve Comparing with Capability Curve
ConstantTorque
ConstantPower
Output Torque
Motor Speed
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0.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00 80.00 90.00Primary Sweep
0.00
50.00
100.00
150.00
200.00
250.00
300.00
350.00
400.00
Y1
Ansoft Corporation Maxwell2DDesign1Torque vs. Load Angle @ CurrentsCurv
Optimal Torque Output at Different Currents
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Efficiency Map of Traction Motor
Speed (RPM)
Out
put T
orqu
e (N
*m)
Effi
cien
cy (%
)
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Contents
• Efficiency Map of Traction Motor• Equivalent Circuit Model Extraction• Vector Controller
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ECE Method
IA
IB
ICΘ
Input Variables
Output Parameters- λa, λb, λ
c
- Torque
Goal: Create a state space type equivalent circuit extracted (ECE) model from magnetostatic FEA parametric solution for use in a system simulation
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System Representation
Where:
Torque
Theta
Bac
k EM
F
Inputs:Ia, Ib, Ic, Theta
Outputs:EMF: Va, Vb, VcTorque
CurrentIa, Ib, Ic
dtdV
LI
T
mT
λλλ
=
+=
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• Assume Wye connected winding• IA = Im * cos(Θ
* PolePairs - β )
• IB = Im * cos(Θ
* PolePairs - β – 120)• IC = Im * cos(Θ
* PolePairs - β – 240)
• Let phi = Θ
* PolePairs - β• Independent
Solution Method
IA
IB
IC
Iy
Ix
• Dependent
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Input Parameter Variations
• Im from 0 to Imax : 9 steps• Beta from 0 to 330 deg: 30 steps• Rotor angle: 0 to 60 electrical deg: 10 steps• Total number of solutions:
• 9 * 30 * 10 = 2700 independent solutions
Good for rapid design using Distributed Solve Option (DSO)
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DSO – Distributed Solve Option
…
Host
Nodes
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User Defined Simplorer®
Models
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Simplorer®
ECE Circuit
ECE - LINKECE - LINKECE - LINKECE - LINK
Beta_IN Im_IN Theta_IND
D
D
ω +
+Φ
GAIN
GAIN
GAIN
GAIN
GAIN
GAIN
GAIN
GAINn
GAIN
ATAN2 GAINIxb
Ixc
Iyb
Iyc
A
A
A
RA
RB
RC
L1
L2
L3
e1
e3
e2
IA
IB
IC
Coordinate transformation realized using VHDL-AMS
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Verify ECE Model Against FEA Transient
• Open Circuit Back EMF
0.000 0.002 0.004 0.006 0.008 0.010 0.012Primary Sweep
-300.00
-200.00
-100.00
0.00
100.00
200.00
300.00
Y1
Ansoft Corporation OC_EMFBack EMFCurve Info
InducedVoltage(PhA)Setup1 : Transient
InducedVoltage(PhB)Setup1 : Transient
InducedVoltage(PhC)Setup1 : Transient
Y Component 1Imported
Y Component 2Imported
Y Component 3Imported
0.0005 0.0010 0.0015 0.0020 0.0025 0.0030Primary Sweep
190.00
200.00
210.00
220.00
230.00
240.00
Y1
Ansoft Corporation OC_EMFBack EMF
Curve Info avg
InducedVoltage(PhA)Setup1 : Transient 225.0685
InducedVoltage(PhB)Setup1 : Transient -105.5390
InducedVoltage(PhC)Setup1 : Transient -102.5586
Y Component 1Imported 224.6388
Y Component 2Imported -105.1177
Y Component 3Imported -102.3206
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Verify ECE Model Against FEA Transient
• Unbalanced Phase Currents
0.000 0.002 0.004 0.006 0.008 0.010 0.012Primary Sweep
-0.40
-0.30
-0.20
-0.10
0.00
0.10
0.20
0.30
0.40
0.50
Y1
Ansoft Corporation Test_tranXY Plot 2Curve Info
FluxLinkage(PhA)Setup1 : Transient
FluxLinkage(PhB)Setup1 : Transient
FluxLinkage(PhC)Setup1 : Transient
Y Component 1Imported
Y Component 2Imported
Y Component 3Imported
0.000 0.002 0.004 0.006 0.008 0.010 0.012Primary Sweep
-0.50
-0.40
-0.30
-0.20
-0.10
0.00
0.10
0.20
0.30
0.40
0.50
Y1
Ansoft Corporation Test_tran1Flux LinkageCurve Info
FluxLinkage(PhA)Setup1 : Transient
FluxLinkage(PhB)Setup1 : Transient
FluxLinkage(PhC)Setup1 : Transient
Y Component 1Imported
Y Component 2Imported
Y Component 3Imported
0.000 0.002 0.004 0.006 0.008 0.010 0.012Primary Sweep
-0.30
-0.20
-0.10
0.00
0.10
0.20
0.30
Y1
Ansoft Corporation Test_tranFlux LinkageCurve Info
FluxLinkage(PhA)Setup1 : Transient
FluxLinkage(PhB)Setup1 : Transient
FluxLinkage(PhC)Setup1 : Transient
Y Component 1Imported
Y Component 2Imported
Y Component 3Imported
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Contents
• Efficiency Map of Traction Motor• Equivalent Circuit Model Extraction• Vector Controller• Energy Storage Sub-system• System Integration
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Vector Control with Step Load
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Vector Control with Step Load
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Vector Control with Step Load
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Vector Control with Ramp Load, Mfg. IGBT and Deadtime Control
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Vector Control with Ramp Load, Mfg. IGBT and Deadtime Control
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Maximum Torque per Ampere (MTPA) and Field Weakening Control
Voltage and Current Limitation Equations
lim22
lim22
)()( UiLiLu
Iiii
qqfddes
qds
≤++=
≤+=
ψω
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Maximum Torque per Ampere (MTPA) and Field Weakening Control
id, iq calculation equations for field weakening control
22lim
22
lim
dq
d
edd
fd
iIi
LiL
LU
Li
−=
⎟⎟⎠
⎞⎜⎜⎝
⎛−⎟⎟
⎠
⎞⎜⎜⎝
⎛+−=
ωψ
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Maximum Torque per Ampere (MTPA) and Field Weakening Control
For this IPM exported from RMxprt: lim/ ILdf >ψSo, there is no such control phase with maximal constant output power
( ) ( )( )
( )
q
fdde
q
ddq
dqe
fqfq
d
fd
L
iLU
i
LLL
LLULL
Li
22
lim
22
lim2
4
8
ψω
ωψψ
ψ
+−⎟⎟⎠
⎞⎜⎜⎝
⎛
=
−
−⎟⎟⎠
⎞⎜⎜⎝
⎛+−
+−=
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Maximum Torque per Ampere (MTPA) and Field Weakening Control
MTPA Control
Field Weakening Control
lim/ ILdf >ψStable:li/ ILdf >ψ
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Maximum Torque per Ampere (MTPA) and Field Weakening Control
From the calculation equation of ideal maximal speed:
)*(* lim
limmax ILP
U
df −=Ω
ψ
We can get the maximal speed is 5475 rpm, which coincides with the simulation result.
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Maximum Torque per Ampere (MTPA) and Field Weakening Control
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Future Work
• Field-weakening that includes accurate FEA model
• Energy Storage Sub-system• System Integration
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Maximum Torque per Ampere (MTPA) and Field Weakening Control
fψToo steep because the Ld, Lq and calculated by RMxprt are not precise enough for FWC. FEA model is recommended.
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Conclusion
• Efficiency Map of Traction Motor– Calculated Using Transient FEA
• Equivalent Circuit Model– Extracted Based on Static FEA
• Torque-Speed Capability– Implemented Using Vector Control
• Field-weakening Controller – Implemented to Enhance the Vector Control
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References
•Report on Toyota/Prius Motor Torque Capability, Torque Property, No- Load Back EMF, and Mechanical Losses, J. S. Hsu, Ph.D., C. W. Ayers, C. L. Coomer, R. H. Wiles, Oak Ridge National Laboratory
•Report on Toyota/Prius Motor Design and manufacturing Assessment, J. S. Hsu, C. W. Ayers, C. L. Coomer, Oak Ridge National Laboratory
•Evaluation of 2004 Toyota Prius Hybrid Electric Drive System Interim Report, C. W. Ayers, J. S. Hsu, L. D. Marlino, C. W. Miller,G. W. Ott, Jr.,C. B. Oland, Oak Ridge National Laboratory