charging and driving wireless: an inductive solutioncharging and driving wireless: an inductive...

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Charging and Driving Wireless: An Inductive Solution

Venugopal Prasanth, PhD Researcher, Prof. Pavol Bauer

Co-Supervisor, Promoter: Prof. Braham Ferreira

6/25/2014


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


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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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


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” .


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


Circuit Theory of Air-Cored Transformer

M v2v1

L1-M L2-Mi1 i2

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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”.


Basic Compensation Topologies-SS, PP, SP, PS

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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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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’’


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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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.


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.


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.


Higher Operating Frequency Trend

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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.


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.


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


Longitudinal Misalignment – Novel Effect

O

A B

θ1

θ2=90

θ1

P

a a

2L

L

i

i

θ2=90

A B

O


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


Edge Effect

P

Longitudinal Section

a

2L

Vertical

Section 2a

i1

(N1 -1)turns end

N1 turns end


Experimental studies

Lateral (L)

Longitudinal (R)


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


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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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


Questions??

6/25/2014

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