charging and driving wireless: an inductive solutioncharging and driving wireless: an inductive...
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1 Challenge the future
Charging and Driving Wireless: An Inductive Solution
Venugopal Prasanth, PhD Researcher, Prof. Pavol Bauer
Co-Supervisor, Promoter: Prof. Braham Ferreira
6/25/2014
2 Challenge the future
Contents of the presentation
• Wireless Power Transfer Modes
• Inductive Power Transfer (IPT) Basics
• Performance Metrics of IPT Systems
• Loss Mechanism in IPT Systems
• E-mobility vision
• Current and Future Research at Delft
6/25/2014
3 Challenge the future
Wireless Power Transfer Modes
Kazmierkowski, M.P.; Moradewicz, A.J., "Unplugged But Connected: Review of Contactless Energy Transfer Systems," Industrial Electronics Magazine,
IEEE , vol.6, no.4, pp.47,55, Dec. 2012.
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4 Challenge the future
Inductive Power Transfer - Components
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M
DC
DC
DC
AC
DC /Rectified DC
i/p
VLF-LF Inverter Primary
Compensation
Secondary
Compensation
RectifierRegulator
Traction motor
Battery
Electric Vehicle
5 Challenge the future
Air-cored Transformer Essentials (Uncompensated IPT)
For a system of n-coupled inductors,
Condition for symmetry and energy equivalence:
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the primary voltages are :
b/w ith and jth coils
“A large air-gap transformer is characterized by large leakage fields in both primary and secondary and hence it demands large Q leading to poor pf and poor η” .
6 Challenge the future
Coefficient of Coupling and Mutual Inductance
In a general coupled inductor system, the primary and secondary can have different shapes, sizes and hence leakages
|k | =.01–0.5 (loosely coupled), |k | 1 (tightly coupled)
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V1 RL
i1 i2
e1 e2
k1
k2
7 Challenge the future
Circuit Theory of Air-Cored Transformer
M v2v1
L1-M L2-Mi1 i2
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8 Challenge the future
Need for Compensation
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The physics of IPT can be summed up as “The reactive power demand of the leakage fields in the large air-gap transformer are supplied by the reactive power produced by the compensation capacitors and the power supply source delivers only the real power, improving efficiency and pf”.
9 Challenge the future
Basic Compensation Topologies-SS, PP, SP, PS
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10 Challenge the future
Quantitative Analysis of Basic Compensation
Topology Equivalent circuit impedance (Zeq) Primary compensation capacitance (C1)
SS type
SP type
PS type
PP type
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Variation in the Parameters as a Function of Freq – SS, SP
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12 Challenge the future
Variation in the Parameters as a Function of Freq – PS, PP
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“The parallel resonant topologies need a current source input so as to transfer power effectively’’
13 Challenge the future
Result of Compensation
• The circuit impedance has shifted from an RL circuit to a R circuit.
• The power factor improves to unity.
• The current or voltage has amplified by a factor depending on Topology:
• Another popular topology: LCL ( from studies on induction cooking)
LCL resonant inverter drives a constant input current onto a parallel resonant ckt.
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14 Challenge the future
Comparison of Various Topologies Characteristic of the topology SS Topology SP Topology PS Topology PP Topology
Dependence of the primary
compensation capacitance on load
None None Dependent Dependent
Circuit equivalent impedance at
resonance
Minimum Minimum Maximum Maximum
Type of ac source to be applied so as to
transfer maximum power
Voltage
source
Voltage
source
Current source Current source
Power transferred at constant source
voltage (SS, SP)/ source current (PS,PP)
Lower Higher Lower Higher
Peak efficiency Higher Lower Higher Lower
Tolerance of efficiency to variable
frequency
Lower Higher Lower Higher
Tolerance of power factor to variable
frequency
Higher Lower Higher Lower
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Prasanth, V.; “Wireless Power Transfer for E-Mobility”, MSc. Thesis, TU Delft Institutional Repository, July 2012.
15 Challenge the future
Performance Metrics of IPT System
SS and PS topologies
SP and PP topologies
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The power transferred to the secondary and efficiency are related as:
*A Figure of Merit often used by considering the transformer loss factor *Waffenschmidt, E.; Staring, T., "Limitation of inductive power transfer for consumer applications," Power Electronics and Applications, 2009. EPE '09. 13th
European Conference on , vol., no., pp.1,10, 8-10 Sept. 2009.
16 Challenge the future
Losses in IPT Systems
• Conduction Losses • Copper Loss
Skin Effect : Use Litz wire with dia d<δ,
• Proximity Effect
• Iron Losses • Eddy current Losses
• Hysteresis Losses
• Switching and Conduction Losses in the converter
• Dielectric Losses of the capacitor
• Losses in Parasitic
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Sullivan, C.R., "Optimal choice for number of strands in a litz-wire transformer
winding," Power Electronics, IEEE Transactions on , vol.14, no.2, pp.283,291, Mar 1999.
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Higher Operating Frequency Trend
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18 Challenge the future
IPT for Electric Mobility - Scenarios
Charge the vehicle in the parking lots :
Stationary Charging
Power the vehicle on the go : Dynamic Powering
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Vs
b)
Power Supply
Cabinet
Power Supply
Cabinet
Pad Pad Pad Pad Pad Pad Pad Pad
l = 100 m
a)
Power and
Control Unit
Common supply
cables
Control signal
IPT Track
RPEV with
Pickup
Distributed Switch
boxes
Power Supply Rail
Covic, G.A.; Boys, J.T., "Modern Trends in Inductive Power
Transfer for Transportation Applications," Emerging and
Selected Topics in Power Electronics, IEEE Journal of , vol.1,
no.1, pp.28,41, March 2013.
Huh, J.; Lee, S.W.; Lee, W.Y.; Cho, G.H.; Rim, C.T., "Narrow-
Width Inductive Power Transfer System for Online Electrical
Vehicles," Power Electronics, IEEE Transactions on , vol.26,
no.12, pp.3666,3679, Dec. 2011.
Budhia, M.; Covic, G.A.; Boys, J.T., "Design and optimisation of magnetic structures for
lumped Inductive Power Transfer systems," Energy Conversion Congress and
Exposition, 2009. ECCE 2009. IEEE , vol., no., pp.2081,2088, 20-24 Sept. 2009.
Prasanth, V.; Bauer, P., "Distributed IPT Systems for Dynamic
Powering: Misalignment Analysis," Industrial Electronics,
IEEE Transactions on , vol.61, no.11, pp.6013,6021, Nov.
2014.
19 Challenge the future
Study of Misalignment in Distributed Systems
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O
A B
θ1
θ2 θ2
θ1
dl
a a
2L
L
i
ir
θ
P
l
Locus of P for Longitudinal Misalignment
Lo
cus o
f P fo
r La
teral M
isalig
nm
ent
A B
O X, lateral
misalignment
Z, vertical
misalignment
Y, longitudinal
misalignment
Primary loops
Vertical flux
Cross-sectional view of pickup/secondary placed on top of the primary
b)
a)
Long rectangular loop based primary and the magnetic fields
Horizontal winding
Prasanth, V.; Bauer, P., "Distributed IPT Systems for Dynamic Powering: Misalignment
Analysis," Industrial Electronics, IEEE Transactions on , vol.61, no.11, pp.6013,6021, Nov. 2014.
20 Challenge the future
Biot-Savart Law to Misalignment Problem
O
A B
θ1
θ2 θ2
θ1
dl
a a
2L
L
i
i
rθ
P
l
Locus of P for Longitudinal Misalignment
Lo
cus o
f P fo
r La
teral M
isalig
nm
ent
A B
O X, lateral
misalignment
Z, vertical
misalignment
Y, longitudinal
misalignment
21 Challenge the future
Longitudinal Misalignment – Novel Effect
O
A B
θ1
θ2=90
θ1
P
a a
2L
L
i
i
θ2=90
A B
O
22 Challenge the future
Lateral Misalignment – Derivation
O
A B
θ1-σ
a1 2a-a1
2L
L
i
i
P
θ2-σ θ2+σ
θ1+σ
A B
O
23 Challenge the future
Edge Effect
P
Longitudinal Section
a
2L
Vertical
Section 2a
i1
(N1 -1)turns end
N1 turns end
24 Challenge the future
Experimental studies
Lateral (L)
Longitudinal (R)
25 Challenge the future
Current Research at Delft
Magnetic Design and PE solutions
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Pickup on an E core
Single turn inductor Double turn inductor Single turn unipolar inductor
Pickup on an E core
Double turn unipolar inductor 4 turn inductor 5 turn inductor
Lumped/ Concentrated IPT systems
Distributed IPT systems
26 Challenge the future
Current and Future Research at Delft
• Modelling of Polyphase IPT System and solution of interphase mutual inductance ( MSc. Vangelis Lanaras).
• Bidirectional SiC based IPT system ( MSc. Student Dionisis Voglitsis).
• Novel Charge Pad Design ( Prasanth and Idea implementation – MSc. Student Jose Ralino Prazeres).
• Modelling and controller design of distributed IPT for EVs (Prasanth).
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27 Challenge the future
Bidirectional SiC based IPT System
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P = 1 kW, f = 110 kHz
1 1
2 2
sin( )2
p s
resY p s
V VP M d
w L L
)cos(2 22
11d
LLw
VVMQ
spresY
sp
MSc. Student: Dionisis Voglitsis
28 Challenge the future
Questions??
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