A Wireless Power Transfer System for Electric Vehicle in Charge While Driving

8/16/2019 A Wireless Power Transfer System for Electric Vehicle in Charge While Driving

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A Wireless Power Transfer system for

electric vehicle in Charge While Driving

Author: Vincenzo Cirimele ID 21712 – First year PhD student

Tutor: Professor Fabio Freschi

Collaborators in the research: Prof. Paolo Guglielmi, Prof.Maurizio Repetto, Ing. Luca Giaccone


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Attended classes

Wireless Power Transfer system for electric vehicle in Charge While Driving December 4th 2014

2

Course CFU Date

Metodi di ottimizzazione per problemi ingegneristici 6 03/06/2014

Valutazione di impatto ambientale di campi magnetici edelettrici a frequenza industriale

4 10/06/2014

Corso breve “Electromagnetic Compatibility (EMC) forEngineers – Scuola Nazionale Dottorandi di Elettrotecnica

“Ferdinando Gasparini”

1 18/06/2014

EPS-SIF International School on EnergyCOURSE II “Energy: basic concepts and forefront ideas”

6 17/07/2014

Propulsione di veicoli elettrici e ibridi (Second level) 8 19/09/2014

Programmazione in LabView: parte 1 e parte 2 8 22/09/2014

Sistemi elettronici di potenza per la generazionedistribuita dell’energia elettrica

4 Not yetregistered

Aspetti fisico-matematici dell’elettromagnetismo 4 Ongoing


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Research context and motivation

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Electric vehicle market is shyly growing up in these years, but there areseveral factors that are preventing its expansion related to technologicaland psychological aspects that influence the common perception about

electric vehicles for private transport.On the other way, electric mobility is considered a good technology to

reduce dependence on fossil fuels and resulting greenhouse gasemissions.

The main critical object is represented by batteries: high costs, highvolumes, low power density compared with classic fossil fuels, necessity

of frequent stops and long time for the recharge and not well predictable

behavior during the travel, are the principal obstacles to the customerapproval.

My research activity is focused on the development of a DynamicInductive Power Transfer system able to transfer energy to the battery of

the vehicle during the motion, allowing the reduction of on-board batterycapacity and the reduction of stops for the battery recharge.

Differently from developed solutions based on the public transports sector

and fixed tracks, my research is oriented towards the private transport.This activity is seeing the cooperation with several universities, researchcenters and manufacturers and could provide important indications about

the possibility to realize new concepts of road and city infrastructuresaddressed to the development of a full electric mobility.



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Addressed research questions/problems

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The Wireless Power Transfer is based on an inductive coupling between a transmittingcoil (fixed) and a receiving coil (mobile) usually capacitive compensated. For this reasonthese systems are resonant. This research activity is oriented to solve and improve the following aspects:

•# individuation of proper circuit topologies for the compensation and the matching with

power electronics structure;

•# analysis of the rules that govern the system and allow its control;

•# design of the magnetic structure considering aspects related to the mechanical integration (on board and on vehicle), electromagnetic compatibility and protection of people against the magnetic field exposure.



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Novel contributions

5 Wireless Power Transfer system for electric vehicle in Charge While Driving

December 4th 2014

Here a brief list of principal issues in which there was a novel contribution:

In the next slides only a few of these points are going to be explained in detail according to the limited space ofthe presentation.

• Introduction of a new topology for the compensation of the primary side called “hybrid” which enables decoupling the

two aspects of magnetic design and impedance matching with the power electronic supply (ref. [2]).

• Development of precise rules for down-scaling of the inductive power transfer structures for constant frequency (ref.[2]).

• Formulation of an algorithm for the design of the magnetic structure using standard compensation topologies inpresence of a constant voltage power electronic supply.

• Building of a down-scale prototype for testing of models, circuital arrangements and control techniques with overallefficiency of 86% @100 W

• Study of a novel structure for the improvement of the coupling and the tolerance against misalignment accordingwith limit for human exposure dictated by ICNIRP (ref. [3],[4]).

• Development of a protocol for the management of the power electronics during the operation of wireless powertransfer in charge while driving (ref. [4]). Developed within the eCo-FEV project FP7 314411 of 7th FrameworkProgramme for Research of European Union.

• Development of a 20 kW prototype and contribution in the development of a test site in which to test futuredeveloped functionalities of the charge while driving (ref. [4]). Developed within the eCo-FEV project FP7 314411 of7th Framework Programme for Research of European Union.

• Design of a new kind of PCB capacitor for compensation in constant voltage structure. Developed inside theFABRIC project FP7 605405 of 7th Framework Programme for Research of European Union.


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Novel contributions: design algorithm for the magnetic structure

VSI inverter system

A key point of the proposed solution is aimposed high voltage power transmissionwith relative low value of current at theinverter output differently from previousworks designed with an imposedconstant current whose value is chosenas the main design parameter.

The design of the magnetic structure hasto face with the impedance matchingrespect to the power electronics.

Pbattery Ibattery

V dc link I DC/AC (I1)

Frequency

J1, J2-> S1, S2

Geometry

Optimization algorithm

END

V1 = rms value of 1st

harmonic of square wave



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Novel contributions: optimization process and prototype construction

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Problem variables = 13 Objectives :

•# maximize coupling (k) •# minimize power losses in the

shields

Obj. function : min((1-k) + Ploss/Pmax)

Differential Evolutionary Strategyoptimization algorithm

Taking into account problems of EMC andICNIRP limit for human exposure @100 kHz

(Bmax = 27µT)

Shielding



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Novel contributions: prototype and test site developing

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Receiving structure

Transmitting coils On-road supply andcommunication

A dedicated power plant was

designed using a stabilized DCdistribution line to supply morecharging zones composed by six

transmitting coils.



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Novel contributions: prototype data

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DC/AC converter (transmitter supply)

Parameter

Value

Rated power 20 kW

Rated DC link voltage level 650 V

Rated output current 34 A

Rated switching frequency 100 kHz

Frequency range (regulation) 20 -200 kHz

Efficiency(10%-100% rated load)

97%

Expected efficiency of the overall system > 85%

Transmitting section

Parameter Value

Number of transmitting coils 6

Length of single coil 1.5 m

Width of the single coil 0.5 m


Receiving section

Parameter Value

Rated air gap 20 cm

Rated coupling k = 0.15

Rated current 66 A


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Novel contributions: design of a PCB capacitor for MV


December 4th 2014

Capacitor data

Parameter Value

Rated capacitance 7 nF

Max peak voltage 10 kV

Rated current 40 A

Proper resonance frequency 400 MHz

Series resonant system causes highelectrical stresses over the capacitor.In particular, series resonance, forhigh frequency, is related to a hugevoltage drop over the capacitor.

Common commercial capacitors (ex.

inductive welding) are not able totolerate medium-voltage stresses sothis means to use a series-parallelcombination of more capacitors.

The designed capacitor allows tosustain very high voltage using asingle component for each coil throughthe use of a multi- layer PCB

technology.


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Adopted methodologies: mutual coupled inductors, reflected

impedance and total impedance


December 4th 2014

Time-domain Frequency-domain

Coupling coefficient

Equivalent resistance

Extracting the current I2 from the second equation and substituting it in the first one, it is possible to findthe equivalent impedance seen by the source called total impedance (ZT). The part related to the

receiving side is called reflected impedance (ZR)

V 1

I 1= (R1 + jωL1) +

ω2M 2

R2 + jωL2 + RL= Z T


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Adopted methodologies: pros of resonance on both sides

Additional info (title, place,...) 12

P 2 ∝ V ocI 2 = V ocV oc

q R2L + (ωL2)2

•#

On the receiving side:

maximize power transfer capability

•# On the transmitting side: minimize the VA rating of the converter (cost)

•# On the efficiency side: adopt a resonant converter and have the possibility to

reduce ideally to zero the switching losses (ZCS/ZVS)

S1 > P1$ P2 S1 = P1$ P2

Model of thereceiving side


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Adopted methodologies: frequency response and control

Additional info (title, place,...) 13

RL= 0.1 !

RL

= 100 !

RL

= 20 !

Constant couplingk = 0.1

Differently from single resonant circuits, the coupling of two resonant circuits introducesthe presence of two minima in the total impedance value that vary in magnitude andfrequency depending on the coupling but also on the value of the load. This aspect is

critical for the control of the power electronics and the possibility of regulation throughthe variation of frequency.


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Submitted and published conference/journal papers

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[1] Davide Bavastro, Aldo Canova, Vincenzo Cirimele, Fabio Freschi, Luca Giaccone, Paolo

Guglielmi, Maurizio Repetto, “Design of Wireless Power Transmission for a Charge While DrivingSystem”, IEEE Transaction on Magnetics, vol. 50 n. 2, pp. 965-968, February 2014.

[2] Vincenzo Cirimele, Fabio Freschi, Paolo Guglielmi, “Wireless Power Transfer Structure Design forElectric Vehicle in Charge While Driving”, Proceedings of XXIth International Conference onElectrical Machines (ICEM 2014), September 2-5 2014, Berlin.

[3] Vincenzo Cirimele, Fabio Freschi, “Design of a magnetic structure for inductive power transfer forelectric vehicle charge during the motion”, Short paper proceedings of 13th International Workshopon 1&2 Dimensional Magnetic Measurement and Testing (2dm), September 10-12 2014, Turin.

[4] Vincenzo Cirimele, Michela Diana, Nadim El Sayed, Fabio Freschi, Paolo Guglielmi, GiovanniPiccoli, “An innovative next generation E-mobility infrastructure: the eCo-FEV project”, IEEEInternational Electric Vehicle Conference (IEVC 2014), December 17-19 2014, Florence

[5] Vincenzo Cirimele, Michela Diana, Paolo Guglielmi, Giovanni Piccoli, “Multi-n-phase ElectricDrivers for traction Applications”, IEEE International Electric Vehicle Conference (IEVC 2014),December 17-19 2014, Florence



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Future work

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Research efforts will be oriented in thedirection of the research of the controltechniques for the optimization of thepower electronic operations in order toobtain an efficient transmission and the

capability to quickly react against the

possible faults that could occur duringthe recharge process. To provide this analysis, a laboratoryprototype is under construction. It will be used also for the testing of

shielding solution and the behavior ofthe new designed components.


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A Wireless Power Transfer System for Electric Vehicle in Charge While Driving