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www.ozeninc.com [email protected] (408) 732 4665 1210 E Arques Ave St 207 Sunnyvale, CA 94085
Reliable World Class Insights
Your Silicon Valley Partner in Simulation
ANSYS Sales, Consulting, Training & Support
© 2012 ANSYS, Inc. December 18, 20141
Modeling Wireless Power Transfer in ANSYS
© 2012 ANSYS, Inc. December 18, 20142
Physical domains and systems
Thermal domain
Electromagnetic domain
Fluid Flow domain
Mechanical domain
© 2012 ANSYS, Inc. December 18, 20143
Physical domains and systems
Transmitter coil sub-system
Control
Power supply
Circuit
Receiver coil sub-system
Load Circuit
© 2012 ANSYS, Inc. December 18, 20144
Geometry
© 2012 ANSYS, Inc. December 18, 20145
Near-Field (Inductive coupling, resonant) • Not based on propagating EM waves• Operates at distances less than a wavelength of
transmission signal• Resonance obtained by use of external circuit capacitor• Typical challenges include: coil size, shape, number of
turns, saturation, self and mutual inductance, AC resistance, frequency response, losses, efficiency
Far-Field (resonant)• Microwave Type• Operating range to ~10 meters• Tradeoff between directionality and transmission
efficiency• Self capacitance of coil turns is of importance
Wireless Power Transfer
© 2012 ANSYS, Inc. December 18, 20146
Method Map
1mm 1cm 10cm 1m 10m 100m
100%
50%
0%
Transfer Distance
Effic
ienc
y
Resonance type
Induction type (~15W) Induction type (~50kW)
Microwave type
Ref.:EE Times Japan 2009.10
© 2012 ANSYS, Inc. December 18, 20147
1mm 1cm 10cm 1m 10m 100m
100%
50%
0%
Transfer Distance
Effic
ienc
y
Resonance type
Induction type (~15W) Induction type (~50kW)
Microwave type
ANSYS Solution for each WPT type
HFSSDesigner
MaxwellSimplorer
Ref.:EE Times Japan 2009.10
© 2011 ANSYS, Inc. December 18, 2014
8
Large Gap Transformer Design Using Computational Electromagnetics (CEM)
© 2011 ANSYS, Inc. December 18, 2014
9
• Low reluctance flux path is available
• Mutual Coupling between the coils can be easily determined using Magnetic Circuit approach
• Leakage flux can be considered to be negligible
• Mutual inductance can be derived using flux balance
• Analytical solution possible within permissible level of accuracy
Transformer
© 2011 ANSYS, Inc. December 18, 2014
10
• No Specific path for the magnetic flux
• Leakage flux is significant enough and can not be neglected
• Analytical methods are proposed for calculation of Mutual inductance using Maxwell’s formula for two coaxial circular coils
Large Gap Transformer
𝑴𝑴 =𝟐𝟐𝝁𝝁𝟎𝟎 𝑹𝑹𝒑𝒑𝑹𝑹𝒔𝒔
𝒌𝒌𝟏𝟏 − 𝒌𝒌𝟐𝟐
𝟐𝟐𝑲𝑲 𝒌𝒌 − 𝑬𝑬 𝒌𝒌
𝑲𝑲 𝒌𝒌 ,𝑬𝑬 𝒌𝒌 are elliptical integrals of first and second kind
Application of these formulas to real life cases is almost impossible
Computation Electromagnetics can help to reduce problem complexity significantly - Maxwell
© 2011 ANSYS, Inc. December 18, 2014
11
Maxwell
© 2011 ANSYS, Inc. December 18, 2014
12
• Easy-to-use GUI• Features entered through GUI• Fast Learning Curve• Integrated under ANSYS Workbench (WB)
Graphical User Interface (GUI)
© 2011 ANSYS, Inc. December 18, 2014
13
Measured
Automatic Adaptive Meshing
© 2011 ANSYS, Inc. December 18, 2014
14
• Allows any arbitrary mathematical manipulation of basic field quantities• Allows to easily define any post-processing quantity
Fields Calculator
© 2011 ANSYS, Inc. December 18, 2014
15
• Flexible and easy-to-use post-processing capabilities• Field plots can be generated in volumes, on surfaces and on any defined planes. Mesh,
magnitude, vector and streamline plots of basic field quantities are readily available
Post Processing
© 2011 ANSYS, Inc. December 18, 2014
16
• Arbitrary time-dependent voltage and current excitations to drive the coils• Measured waveform can be imported to be used as a coil excitation• Maxwell is capable of modeling translational, rotational cylindrical and rotational non-cylindrical
(relay type) motion• Equation of Motion can be considered
Time domain analysis with motion
© 2012 ANSYS, Inc. December 18, 201417
Inductive Type Coupling – Near Field
1) Electromagnetic analysis to determine R, L, M
Magnetic → R, L, MR
C C
R
LLM
2) Resonant circuit realized by a lumped capacitance parameter in the circuit simulator
© 2012 ANSYS, Inc. December 18, 201418
Example
20kW @ 400V/20kHz
Core
CoilShield Plate
Secondary Coil
Primary Coil
© 2012 ANSYS, Inc. December 18, 201419
Solution Flow Chart
MagnetostaticAnalysis
Frequency domainAnalysis Circuit Analysis
AC / TRState-Space Model
Circuit / Drive / Controller designWaveform, Efficiency, Power factor, Response
Frequency domainAnalysis
Field, Loss
Core, Winding
GapSliding
© 2012 ANSYS, Inc. December 18, 201420
• A Static Magnetic analysis using ANSYS Maxwell can calculate the self as well as mutual inductances of such a system
• Coils can be modelled as a lumped objects to reduce the simulation complexity
Magnetostatic Analysis using Maxwell
L1 MM L2
© 2012 ANSYS, Inc. December 18, 201421
Flux Density Distribution
© 2012 ANSYS, Inc. December 18, 201422
0.00 100.00 200.00 300.00 400.00H (A_per_meter)
0.00
0.10
0.20
0.30
0.40
0.50
0.60
B (t
esla
)
Magnetostatic Analysis using Maxwell
Verification for core saturation– Core’s BH curve, Mag_B field plot– No magnetic saturation
Nonlinear BH curve 0.00 20.00 40.00 60.00 80.00 100.00Current [A]
0.00
0.01
0.10
1.00
Gap
[met
er]
2D_Static_BHMutual Inductance L12 ANSOFT
Matrix1.L(C [nH]
0.0000e+000
5.7000e+003
1.1400e+004
1.7100e+004
2.2800e+004
2.8500e+004
3.4200e+004
Specification Area
As Maximum Flux Density is within linear region, cores can be modelled as Linear magnetic material
© 2011 ANSYS, Inc. December 18, 2014
23
Parametric Analysis
• In Example, we assumed that spacing between the coils is fixed and axis of the sender and receiver is perfectly aligned
• In Practice,– Distance between the coils can vary significantly – Misalignments in coil axis can also be present
• Analysis needs to be performed to determine magnetic coupling between two coils as function of the spatial location with respect to each other
© 2011 ANSYS, Inc. December 18, 2014
24
Parametric Analysis using Maxwell
© 2011 ANSYS, Inc. December 18, 2014
25
Parametric Analysis using Maxwell
© 2011 ANSYS, Inc. December 18, 2014
26
Parametric Analysis using Maxwell
Mutual Inductance Vs Gap Vs Slide
Coupling Coefficient Vs Gap Vs Slide
© 2012 ANSYS, Inc. December 18, 201427
Eddy Current (Frequency domain)• Impedance vs frequency
• State Space Model for Circuit Analysis
• Losses
• Eddy current shielding
Shield Plate (Aluminum)
Core(Power Ferrite)
© 2011 ANSYS, Inc. December 18, 2014
28
Loss CalculationSpecifying Eddy Current Calculations in Shields
Define Electrical Conductivity for the shields in Siemens/mShields are modelled as Aluminum in this example and are specified with Conductivity of Aluminum
Turn ON the eddy current calculation for the shield objects
© 2011 ANSYS, Inc. December 18, 2014
29
Loss CalculationSpecifying Core Loss Calculations in Core Plates
Input Core Loss vs Frequency data for the range of frequencies that you wish to operate onCore Loss Coefficients are calculated automatically
Turn ON Core Loss calculation for the cores
© 2011 ANSYS, Inc. December 18, 2014
30
Loss CalculationCore Losses in the Core Plates at 100 kHz
© 2011 ANSYS, Inc. December 18, 2014
31
• Once the Large Gap Transformer is analyzed in isolation, it needs to be included in a system level simulation
• The model of the transformer represented on system level should include the accurate representation as simulated using CEM
• A state space representation can be extracted from CEM model by defining a frequency sweep
• A frequency sweep will also help in analyzing system performance to frequency deviations
Frequency Sweep
© 2011 ANSYS, Inc. December 18, 2014
32
Frequency Sweep
Core Loss Vs Frequency
© 2011 ANSYS, Inc. December 18, 2014
33
Large Gap Transformer Design Using Computational Electromagnetics (CEM)
© 2012 ANSYS, Inc. December 18, 201434
0 0
R1
(1/87) ohm
R2
(1/348) ohm
L1
0.19267mH
L2
0.048166mH
M1
0.5668
Cs
1.93uF
Cp
5.24uF
Rload
10ohm
W+
WM1
W+
WM2
E1AMPL=200VFREQ=10kHz
Coupling Simulation EM and Circuit
0 0
R1
(1/87-0.004) ohm
R2
(1/348-0.001) ohm
Cs
1.87uF
Cp
5.23uF
Rload
10ohm
W+
WM1
W+
WM2
E1AMPL=200VFREQ=10kHz
Current_1st_1:src
Current_1st_2:src
Current_2nd_1:src
Current_2nd_2:src
Current_1st_1:snk
Current_1st_2:snk
Current_2nd_1:snk
Current_2nd_2:snk
=
AC / Frequency domain TR / Time domain
Model Generated by Field Simulator
© 2012 ANSYS, Inc. December 18, 201435
Circuit Design: Resonance Capacitor type
SS, SP, PS, PP type
Ref.: ANSYS Automotive Seminar, 30.Oct.2012, “Design of A Zero-Voltage-Switching Large-Air-Gap Wireless Charger for Plug-in Hybrid Electric Vehicles”. Kevin (Hua) Bai, Department of Electrical and Computer Engineering, Kettering University
© 2012 ANSYS, Inc. December 18, 201436
0
0
0
R1
7.2mOhm
R2
3.6mOhm
Cs
1.72uF
Cp
4.96uF
Rload
13ohm
W
+WM1
W
+WM2
D4
D3
D2
D1
IGBT4
IGBT3
IGBT2
IGBT1
C1
1000uF
TRANS4
DT4
TRANS3
SINE1.VAL > TRIANG1.VAL
TRANS2
DT1
TRANS1
SINE1.VAL < TRIANG1.VAL
STATE_11_4
SET: TSV4:=0SET: TSV3:=0SET: TSV2:=0SET: TSV1:=0DEL: DT4##Dead_Time
STATE_11_3
SET: TSV4:=0SET: TSV3:=1SET: TSV2:=1SET: TSV1:=0
STATE_11_2
SET: TSV4:=0SET: TSV3:=0SET: TSV2:=0SET: TSV1:=0DEL: DT1##Dead_Time
STATE_11_1
SET: TSV4:=1SET: TSV3:=0SET: TSV2:=0SET: TSV1:=1
TRIANG1
AMPL=1FREQ=Carrier_Freq
SINE1
AMPL=Modulation_IndexFREQ=Frequency
ICA: FML_INIT1
Modulation_Index:=0Carrier_Freq:=20kFrequency:=20k
DC_Source:=400Dead_Time:=2u
~
3PHAS
~
~
A * sin (2 * pi * f * t + PHI + phi_u)
PHI = 0°
PHI = -120°
PHI = -240°
THREE_PHASE1D5
D6
D7
D8
D9
D10 Battery- +
LBATT_A1
D11
D12
D13
D14
C2
1uF
2.00 2.20 2.40 2.60 2.80 3.00Time [ms]
-150.00
-100.00
-50.00
0.00
50.00
100.00
150.00
Y1
[A]
Curve Info rmsWM1.I
TR 41.6165
WM2.ITR 34.8648
2.00 2.20 2.40 2.60 2.80 3.00Time [ms]
-800.00
-300.00
200.00
700.00
Y1
[V]
Curve Info rmsWM1.V
TR 281.0066
WM2.VTR 321.9453
2.900 2.925 2.950 2.975 3.000Time [ms]
-250.00
-125.00
0.00
125.00
250.00
Y1
[A]
-1000.00
-500.00
0.00
500.00
873.02
Y2
[V]
MX1: 2.9200MX2: 2.9811
-408.7847-315.0105-64.8250
-40.2840-377.1247-319.5653 -53.6971
-0.0037
0.0610
Curve Info Y Axis rmsWM1.I
TR Y1 38.9542
WM2.ITR Y1 34.1140
WM1.VTR Y2 276.0822
WM2.VTR Y2 316.6292
PWRProbe
PWR_Probe1
Current_1:srcCurrent_2:src
Current_1:snkCurrent_2:snk
PWRProbe
PWR_Probe2
System Simulation
AC400V Rectify InverterWireless Power Transformer Battery
Controller
© 2012 ANSYS, Inc. December 18, 201437
Efficiency Map
Output/Input Power
Tuned capacitance for each condition
90%
50%
20%
[%]100
cos
×=
=
in
out
PPVIP
η
θ
Effic
ienc
y[%
]
Sliding [mm]Gap [mm]
Gap Sliding
Max.96%
© 2011 ANSYS, Inc.38
Efficiency as a function of sliding direction and distance
• Gap between coils kept constant
© 2011 ANSYS, Inc.39
Efficiency as a function of gap between coils
• Zero sliding
Gap
© 2012 ANSYS, Inc. December 18, 201440
Field solution using the currents from the circuit simulation
Magnetic Field Intensity Magnetic Flux Density
0.00 0.20 0.40 0.60 0.80 1.00Distance [meter]
0.00
0.00
0.01
0.10
1.00
10.00
Mag
_B [m
Tesl
a]2D_EddyXY Plot 1 ANSOFT
Curve InfoMag_B
Setup1 : LastAdaptiveFreq='20kHz' Phase='0deg'
Distance
Distance
© 2012 ANSYS, Inc. December 18, 201441
Field solution using the currents from the circuit simulation
Core Losses Shield Losses
Primary
Secondary
© 2012 ANSYS, Inc. December 18, 201442
Summary
ANSYS offers a comprehensive modeling solution for Wireless Power Transfer systems:
– Magnetostatic – Frequency domain– Circuit and system level– Multiphysics
Wireless Power TransferElectromagnetics
System Level ModelingElectromagnetic-Circuit
0
0
0
R1
7.2mOhm
R2
3.6mOhm
Cs
1.72uF
Cp
4.96uF
Rload
13ohm
W
+WM1
W
+WM2
D4
D3
D2
D1
IGBT4
IGBT3
IGBT2
IGBT1
C1
1000uF
TRANS4
DT4
TRANS3
SINE1.VAL > TRIANG1.VAL
TRANS2
DT1
TRANS1
SINE1.VAL < TRIANG1.VAL
STATE_11_4
SET: TSV4:=0SET: TSV3:=0SET: TSV2:=0SET: TSV1:=0DEL: DT4##Dead_Time
STATE_11_3
SET: TSV4:=0SET: TSV3:=1SET: TSV2:=1SET: TSV1:=0
STATE_11_2
SET: TSV4:=0SET: TSV3:=0SET: TSV2:=0SET: TSV1:=0DEL: DT1##Dead_Time
STATE_11_1
SET: TSV4:=1SET: TSV3:=0SET: TSV2:=0SET: TSV1:=1
TRIANG1
AMPL=1FREQ=Carrier_Freq
SINE1
AMPL=Modulation_IndexFREQ=Frequency
ICA: FML_INIT1
Modulation_Index:=0Carrier_Freq:=20kFrequency:=20k
DC_Source:=400Dead_Time:=2u
~
3PHAS
~
~
A * sin (2 * pi * f * t + PHI + phi_u)
PHI = 0°
PHI = -120°
PHI = -240°
THREE_PHASE1D5
D6
D7
D8
D9
D10 Battery- +
LBATT_A1
D11
D12
D13
D14
C2
1uF
2.00 2.20 2.40 2.60 2.80 3.00Time [ms]
-150.00
-100.00
-50.00
0.00
50.00
100.00
150.00
Y1
[A]
Curve Info rmsWM1.I
TR 41.6165
WM2.ITR 34.8648
2.00 2.20 2.40 2.60 2.80 3.00Time [ms]
-800.00
-300.00
200.00
700.00
Y1
[V]
Curve Info rmsWM1.V
TR 281.0066
WM2.VTR 321.9453
2.900 2.925 2.950 2.975 3.000Time [ms]
-250.00
-125.00
0.00
125.00
250.00
Y1
[A]
-1000.00
-500.00
0.00
500.00
873.02
Y2
[V]
MX1: 2.9200MX2: 2.9811
-408.7847-315.0105-64.8250
-40.2840-377.1247-319.5653 -53.6971
-0.0037
0.0610
Curve Info Y Axis rmsWM1.I
TR Y1 38.9542
WM2.ITR Y1 34.1140
WM1.VTR Y2 276.0822
WM2.VTR Y2 316.6292
PWRProbe
PWR_Probe1
Current_1:srcCurrent_2:src
Current_1:snkCurrent_2:snk
PWRProbe
PWR_Probe2