USOO8749334B2
`
`(12) United States Patent
`Boys et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 8,749,334 B2
`Jun. 10, 2014
`
`(54) MULTI POWER SOURCED ELECTRIC
`VEHICLE
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`(*) Notice:
`
`(75) Inventors: John Talbot Boys, Auckland (NZ);
`Grant Anthony Covic, Auckland (NZ)
`(73) Assignee: Auckland Uniservices Ltd., Auckland
`(NZ)
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 782 days.
`12/451,436
`May 9, 2008
`PCT/NZ2O08/OOO 103
`
`(21) Appl. No.:
`(22) PCT Filed:
`(86). PCT No.:
`S371 (c)(1),
`Jan. 13, 2010
`(2), (4) Date:
`(87) PCT Pub. No.: WO2008/140333
`PCT Pub. Date: Nov. 20, 2008
`
`(65)
`
`(30)
`
`Prior Publication Data
`US 2010/O1096O4A1
`May 6, 2010
`Foreign Application Priority Data
`
`May 10, 2007 (NZ) ........................................ 555128
`Jul. 20, 2007 (NZ) ........................................ 556646
`(51) Int. Cl.
`HOIF 27/32
`(52) U.S. Cl.
`USPC ........................................................ 336/84 C
`(58) Field of Classification Search
`USPC ....................... 336/84 R, 84 C, 200, 212, 232
`See application file for complete search history.
`
`(2006.01)
`
`
`
`4,873,677 A 10, 1989 Sakamoto et al.
`5,469,036 A 11, 1995 Eto
`5,528, 113 A
`6/1996 Boys et al.
`5,710,502 A
`1/1998 Poumey
`5,821,638 A 10/1998 Boys et al.
`6,501,364 B1
`12/2002 Hui et al.
`6,906,495 B2
`6/2005 Cheng et al.
`6,934,167 B2
`8/2005 Jang et al.
`
`FOREIGN PATENT DOCUMENTS
`
`JP
`JP
`JP
`JP
`JP
`JP
`
`10, 1991
`O3-239136
`9, 1994
`O6-64393
`9, 1994
`6-662O6
`10, 1994
`06-277358
`12/1994
`6-86321
`9, 1996
`8-238326
`(Continued)
`OTHER PUBLICATIONS
`
`Notice of Reasons for Rejection in corresponding Japanese applica
`tion p2010-507347 (Original and English Translation).
`
`Primary Examiner — Tuyen Nguyen
`(74) Attorney, Agent, or Firm — Law Office of Richard F.
`Jaworski, PC
`
`ABSTRACT
`(57)
`An inductive power transfer (IPT) pad and system for the
`charging of electric and hybid electric vehicles. The batter of
`Such a vehicle can be selectively coupled to a high power
`electrical Supply for fast charging or a lower power electrical
`supply for charging using IPT. The batteries of the vehicles
`are used in a system to control the load demand in an elec
`tricity network through variations of the frequency of power
`Supplied.
`
`35 Claims, 5 Drawing Sheets
`
`Momentum Dynamics Corporation
`Exhibit 1008
`Page 001
`
`

`

`US 8,749,334 B2
`Page 2
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`(56)
`
`References Cited
`
`FOREIGN PATENT DOCUMENTS
`
`JP
`JP
`
`11-097263
`2000-200725
`
`4f1999
`T 2000
`
`JP
`JP
`JP
`JP
`WO
`WO
`WO
`
`2002-231545
`2002-343655
`2004-477O1
`T2007-505480
`WO2005O2486.5
`WO2006 1.01285
`WO2O08051611
`
`8, 2002
`11, 2002
`2, 2004
`3, 2007
`3, 2005
`9, 2006
`5, 2008
`
`Momentum Dynamics Corporation
`Exhibit 1008
`Page 002
`
`

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`U.S. Patent
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`Jun. 10, 2014
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`Sheet 1 of 5
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`US 8,749,334 B2
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`FIGURE 1
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`kix :
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`Momentum Dynamics Corporation
`Exhibit 1008
`Page 003
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`

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`U.S. Patent
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`Jun. 10, 2014
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`Sheet 2 of 5
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`US 8,749,334 B2
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`Momentum Dynamics Corporation
`Exhibit 1008
`Page 004
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`

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`U.S. Patent
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`Jun. 10, 2014
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`Sheet 3 of 5
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`US 8,749,334 B2
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`Momentum Dynamics Corporation
`Exhibit 1008
`Page 005
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`

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`U.S. Patent
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`Jun. 10, 2014
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`Sheet 4 of 5
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`US 8,749,334 B2
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`Momentum Dynamics Corporation
`Exhibit 1008
`Page 006
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`

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`U.S. Patent
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`Jun. 10, 2014
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`Sheet 5 of 5
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`US 8,749,334 B2
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`Momentum Dynamics Corporation
`Exhibit 1008
`Page 007
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`

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`US 8,749,334 B2
`
`1.
`MULTIPOWER SOURCED ELECTRIC
`VEHICLE
`
`This application is a 371 of PCT/ZN2008/000103 filed
`May 9, 2008.
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`5
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`FIELD OF THE INVENTION
`
`The present invention relates to an Inductive Power Trans
`fer (IPT) pad, a system, method and means for charging a
`battery of an electric vehicle using multiple power sources
`and an electric vehicle powered by said battery. More particu
`larly, the invention relates to charging the battery for an elec
`tric vehicle selectively using a high power source for charging
`at a high rate or a lower power source for charging at a lower
`rate.
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`For these reasons conventional pure electric vehicles have
`not metall of the modern requirements for a passenger trans
`port vehicle.
`Inductive Power Transfer (IPT) provides a useful alterna
`tive to more conventional charging. A charger using IPT is
`described in New Zealand Patent Application No. 545664,
`entitled “Single Phase Power Supply for Inductively Coupled
`Power Transfer Systems’” and is incorporated herein by ref
`erence. This charger provides many advantages in that it will
`operate from a standard single phase Supply typically avail
`able in the home, has an excellent power factor and very low
`harmonics. As a result of this, it would be possible to operate
`with several thousand of these connected to a utility network
`without the quality of Supply being degraded. Moreover, the
`use of IPT obviates the need for a user to manually connecta
`cable to the battery.
`
`BACKGROUND
`
`SUMMARY OF THE INVENTION
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`In the development of pure electric vehicles (i.e., those 2O
`powered solely by electricity as opposed to hybrid vehicles),
`there are a number of problems to be solved before these
`vehicles can gain widespread acceptance. These include the
`limited range compared with more conventionally fuelled 25
`vehicles, the inconvenience of having to remember to
`recharge a vehicle (even if it is possible to do so at the user's
`premises or home) and the severe restrictions that occur
`should the vehicle not be charged. These problems have been
`Subjected to greater consideration in recent times due to 30
`heightened concerns about global warming. Pure electric
`vehicles may have a role to play in reducing the effects of
`global warming as they are clearly the lowest polluters of all
`vehicle types and are capable of operating with a lower car
`bon footprint than vehicles powered by more widespread
`and conventional means.
`Many problems with electric vehicles stem directly from
`the battery used to store energy to power the vehicle. Virtually
`all battery types must be charged at a rate that is less than the
`allowable discharge rate, they have a limited capacity, and
`their cycle life is not great. Thus, it takes quite a long time to
`charge a vehicle, the time between charges is shorter than
`ideal, and the functionality of the battery declines rapidly
`with age.
`In use, electric vehicles are however very convenient and
`make ideal shopping baskets and short trip commuter
`vehicles. Other tasks such as dropping off children at schools
`and running errands are also well Suited. If the accumulated
`distance traveled in a day is within the range of the vehicle, 50
`then the battery may be recharged over-night, with service
`capable of being resumed the next day. This is an ideal sce
`nario. However, if the available range is exceeded or the
`battery has not been Sufficiently charged, the driver and pas
`sengers may be left stranded, there will likely be a recovery 55
`fee, the battery will need to be fully charged over a longer
`period of time than a conventional charge cycle and, when
`using conventional batteries, these will almost certainly be
`degraded Such that their available capacity is permanently
`reduced from what it was previously. Opportunity charging 60
`can help to eliminate this problem and involves partially
`charging the vehicle wheneveran opportunity presents itself.
`In perhaps a more serious situation where circumstances
`call for the vehicle to be taken on a long trip, there is little that
`can be done. Here hybrid vehicles may be a good solution as 65
`they can travel great distances on fossil fuels and refuel at
`conventional petrol stations.
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`It is an object of the invention to provide an improved
`Inductive Power Transfer (IPT) pad.
`It is an object of the invention to provide means for charg
`ing a vehicle which mitigates the aforementioned problems
`associated with conventional electric Vehicles.
`An alternative object of the invention is to provide a system
`for charging an electric Vehicle.
`An alternative object of the invention is to provide a
`method of charging an electric Vehicle.
`Alternatively, it is an object of the invention to at least
`provide a useful choice.
`According to a first aspect of the invention, there is pro
`vided an inductive power transfer (IPT) pad comprising a coil
`having at least one turn of a conductor; one or more ferro
`magnetic slabs; and a shield member arranged around both
`said coil and said ferromagnetic slabs for channelling elec
`tromagnetic flux when in use.
`Preferably, the conductor is litz wire.
`Preferably, the coil comprises a plurality of turns of wire.
`Preferably, the ferromagnetic slabs are monolithic slabs.
`Preferably, the ferromagnetic slabs are ferrite slabs.
`Preferably, each ferromagnetic slab is arranged in Substan
`tially the same plane.
`Preferably, each ferromagnetic slab is arranged such that
`its length extends radially from a common point but spaced
`apart therefrom.
`Preferably, each ferromagnetic slab is spaced apart from
`adjacent slabs by Substantially the same angle.
`According to a preferred embodiment, the IPT pad com
`prises eight ferromagnetic slabs each spaced apart from adja
`cent slabs by approximately 45°. Other configurations may be
`selected depending on system requirements.
`Alternatively, in another embodiment, the IPT pad com
`prises a plurality of ferromagnetic slabs whereby a subset of
`the ferromagnetic slabs extend radially from a common point
`but are spaced apart therefrom, a further subset of the ferro
`magnetic slabs extend radially from a different common point
`but are spaced apart therefrom, and a still further subset of the
`ferromagnetic slabs are aligned perpendicularly to the direc
`tion of animaginary straight line connecting the said common
`points, whereby the still further subset of ferromagnetic slabs
`are positioned equidistantly from the imaginary line but
`spaced equally along its length and equally on each side of the
`imaginary line.
`Preferably, the coil is arranged in a plane substantially
`parallel to that of the ferromagnetic slabs.
`
`Momentum Dynamics Corporation
`Exhibit 1008
`Page 008
`
`

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`US 8,749,334 B2
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`Preferably, the coil is positioned to wind around the com
`mon point Such that it passes each slab at approximately the
`centre of the length of each slab.
`Preferably, the IPT pad comprises a substantially rigid
`backplate.
`Preferably, the backplate is substantially planar,
`Preferably, the plane of the backplate is substantially par
`allel to the planes of the ferromagnetic slabs and the coil, with
`the plane of the slabs located between the planes of the back
`plate and the coil.
`Preferably, each ferromagnetic slab is spaced apart from
`the backplate by a thermally conductive and mechanically
`insulating material so as to allow the transfer of heat there
`between and protect the slab from mechanical shock. Accord
`ing to one embodiment, each slab may be spaced apart from
`the backplate using foam or rubber pads. The material making
`up the slabs is brittle and Such steps serve to prevent cracking
`in the slabs caused by rapid temperature changes and also due
`to mechanical stresses exerted on the IPT pad.
`According to preferred embodiments, the backplane is
`formed from a material which substantially inhibits the pas
`sage of magnetic flux therethrough. In one embodiment, this
`material is aluminium.
`Preferably, the shield member is formed from a strip of
`material with the ends thereof joined to form a ring.
`25
`Preferably, the shield member is formed from aluminium.
`Preferably, the shield member is coupled to the backplane.
`Preferably, the IPT pad comprises a member having spaces
`formed therein for holding the ferromagnetic slabs in position
`and having a channel for accommodating the coil.
`Preferably, the member is formed from a material which
`does not significantly affect magnetic flux. In one embodi
`ment, foam or rubber is used.
`Preferably, the member is formed by a moulding process.
`Preferably, the IPT pad comprises a cover plate formed
`from a material that is Substantially transparent to magnetic
`flux. In one embodiment this material is a non-toxic plastic.
`According to preferred embodiments, the cover plate and
`the backplate provide front and rear walls of a housing for the
`IPT pad, with side walls provided by the shield member, the
`shield member preferably being configured to extend from
`the backplate to the cover plate.
`The IPT pad according to the first aspect provides for
`improved performance in use by channelling the flow of flux
`from the charging pad. More particularly, the backplate and
`the shield member serve to direct flux upwards from the plane
`of the backplate with less splay of flux in and parallel to the
`plane of the backplate. This not only improves the inductive
`coupling but also reduces the chance that any undesired
`objects will be subjected to the induced fields during use. It is
`important to note that if this leakage is not controlled, it can
`lead to damage of such objects. For example, in the case of an
`electric vehicle, such leakage may result in the wheel bear
`ings eroding.
`The IPT pad of the present invention is also beneficial in
`that it is relatively slimline compared to more conventional
`IPT pickups. This is particularly important where pickup pads
`are coupled to the underside of an electric vehicle since it is
`important that ground clearance is maintained.
`According to a second aspect, there is provided an induc
`tive power transfer system comprising two inductive power
`transfer pads, wherein the two inductive power transfer pads
`are used in combination, one of the pads being used as a
`pickup pad and the other pad as a charging pad.
`Preferably, the charging pad is coupleable to a power Sup
`ply and inductively transfers power to the pickup pad, which
`is coupleable to a load. Such as a battery.
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`According to a third aspect, there is provided an apparatus
`for charging a battery of an electric or a hybrid electric
`vehicle, the apparatus comprising first means for selectively
`coupling the battery to a high power electrical Supply; and
`second means for selectively coupling the battery to a lower
`power electrical Supply wherein the second means for cou
`pling comprises a pickup pad electrically coupled to the bat
`tery, wherein power is transferred to the pickup pad from a
`charging pad by inductive power transfer.
`Preferably, the first means for coupling comprises a socket
`electrically coupled to the battery, wherein power is trans
`ferred by plugging a cable connected to the high power elec
`trical Supply into the Socket. Thus, electrical energy may be
`rapidly transferred to the battery using the first means for
`coupling, resulting in rapid charging.
`As would be apparent to one of skill in the art, alternatively,
`the first means for coupling comprises a plug electrically
`coupled to the battery, wherein power is transferred by plug
`ging the plug into a socket connected to the cable connected
`to the high power electrical Supply.
`Preferably, the second means for coupling comprises a
`pickup pad according to the first aspect of the invention.
`The use of IPT avoids the need for a user to plug in a cable
`for opportunity charging, including when a vehicle is parked
`overnight. Additionally or alternatively, a second socket may
`be provided or the first socket adapted, if required, so that the
`battery may be connected to a lower power Supply using a
`cable. Again, in the alternative, the second socket may be
`Substituted by a plug configured to mate with a socket con
`nected to the lower power supply. Such embodiments provide
`for improved flexibility in that, where provided and where
`time permits, the battery may be charged using IPT. If rapid
`charging is required and a high power Supply is available, the
`battery may be connected thereto. However, there remains the
`possibility that a battery will require charging where neither
`an IPT charging pad or a high power Supply is available. A
`user could, perhaps, put the charging pad inside the vehicle
`when in transit so that, as required, it could be removed from
`the vehicle, appropriately positioned and used for charging.
`This is possible because embodiments of the invention
`involving IPT preferably work to widely available household
`Voltages but this is inconvenient.
`Thus, the second socket may be provided, preferably on an
`outer surface of the vehicle, to enable the battery to be con
`nected, via a cable, to a lower power Supply. Such as via a
`conventional household Socket. According to preferred
`embodiments, the Socket used for coupling to the high power
`Supply may also be used to couple to a lower power Supply. It
`is therefore possible to charge a battery via most household
`circuits, with only a cable needing to be carried in the vehicle.
`Thus, depending on requirements and which types of
`power Supply and forms of transfer are available, a user may
`selectively couple the battery to a high power Supply or a
`lower power electrical supply, preferably using IPT for trans
`ferring power from the lower power Supply.
`Preferably, the high power Supply has a transfer rating
`between 10 kW and 500 kW.
`Preferably, the lower power supply has a transfer rating
`between 0.5 kW and 2.5 kW so that it may be provided by
`conventional household wiring. More preferably, the lower
`power supply is between 1.0 kW and 2.2 kW.
`Use of the word “battery' throughout the specification is
`not used in a limiting, way and may include one or any
`number of cells or batteries, or Super capacitors.
`Preferably, the apparatus comprises an indication means
`for indicating alignment between the charging pad and the
`pickup pad.
`
`Momentum Dynamics Corporation
`Exhibit 1008
`Page 009
`
`

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`US 8,749,334 B2
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`5
`Preferably, the apparatus comprises an indication means
`for indicating when the battery is being charged.
`According to a fourth aspect of the invention, there is
`provided an electric vehicle comprising a rechargeable bat
`tery and the apparatus of the third aspect for charging said
`battery.
`The electric vehicle may be a “pure electric vehicle' in that
`it may be powered only by electrical energy. However, the
`invention is not limited thereto and may be applied to hybrid
`vehicles which may be powered by electrical energy and at
`least one other energy source. Such as a combustible fuel.
`Thus, references to “electric vehicles' herein include both
`pure electric vehicles and hybrid vehicles having electrical
`energy as one source of power.
`According to a fifth aspect of the invention, there is pro
`vided a method of charging a battery of an electric or a hybrid
`electric vehicle, the method comprising selectively coupling
`the battery to a high power Supply or a lower power Supply,
`wherein said coupling the battery to a lower power Supply
`comprises positioning an inductive powertransfer pickup pad
`electrically coupled to the battery in close proximity to an
`inductive power transfer charging pad.
`Preferably, the step of connecting the battery to the high
`power Supply comprises mating a plug with a socket, wherein
`the plug is associated with one of the battery and the high
`power Supply, and the Socket is associated with the other one
`of the battery and the high power supply.
`More preferably, the pickup pad is coupled to the underside
`of the vehicle and the charging pad is provided on the ground,
`wherein said selectively coupling the battery to the lower
`power Supply comprises driving the vehicle into a position
`such that the pickup pad is positioned above, or operably
`adjacent to, the charging pad.
`Preferably, the charging and pickup pads can be variably
`distanced from each other. The charging pad may be raised
`and lowered from the ground by a raising and lowering
`means. Alternatively, the pickup pad may be raised and low
`ered from the underside of the vehicle by a raising and low
`ering means.
`Preferably, the method comprises indicating alignment
`between the charging pad and the pickup pad.
`Preferably, the method comprises indicating when the bat
`tery is being charged.
`Placement of an IPT pickup pad on the underside of a
`vehicle is preferred for aesthetic reasons, because this
`arrangement provides no physical obstacle to those moving
`around the vehicle while it is being charged, and because it is
`improbable that people or other foreign objects will be sub
`jected to the induced fields during charging. However, the
`invention is not limited to Such placement. A pickup pad may
`belocated essentially anywhere on the vehicle with the charg
`ing pad being mounted so that IPT transfer is enabled when
`the vehicle is parked in position. For example, a pickup pad
`may be provided on the front or rear surface of the vehicle
`with the charging pad being mounted on a wall in a garage so
`that they inductively couple when the vehicle is parked. While
`not preferred due to the requirement for user intervention, the
`invention does not preclude the mounting of the pickup pad
`and/or the charging pad on a moveable mounting or armature,
`whereby, following parking of a vehicle, a user may move one
`or both of the pads so that IPT transfer is enabled. While
`having the drawback of requiring greater user intervention,
`Such embodiments do allow for greater tolerances in the
`parking position of the vehicle.
`According to a sixth aspect, there is provided a system for
`charging a battery of an electric or a hybrid electric Vehicle,
`the system comprising an electricity network or subnetwork
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`having at least one generator, cabling for transferring energy
`generated by the at least one generator around the network;
`IPT coupling means for coupling the network to the battery;
`and control means for controlling the power transfer from the
`at least one generator to the battery.
`Preferably, the network is coupled to a plurality of batteries
`of a corresponding plurality of electric or hybrid electric
`vehicles.
`Any energy source may be used by the generator(s) to
`generate electrical energy. However, according to preferred
`embodiments, a renewable energy source is used. Through
`use of the control means, it is possible to overcome problems
`associated with the fluctuable nature of power generated from
`renewable sources and enhance the stability of the network by
`varying the power supplied to the battery so that the power
`demand on the network better matches the available power.
`These benefits are more marked according to embodiments of
`the system in which the network is coupled to a plurality of
`batteries of a corresponding plurality of electric or hybrid
`electric vehicles.
`Preferably, the control means is configured to vary the
`power transfer so as to optimise the load factor. Thus, a
`network controller (e.g. a utility company) may vary the
`power transfer to batteries connected to their network to bet
`ter match Supply and demand.
`According to one embodiment, the batteries in the vehicles
`are owned by a network controller which operates the net
`work and are leased to the owners of the vehicles,
`The system of the sixth aspect preferably comprises at least
`one IPT pad according to the first aspect and/or at least one
`apparatus for charging according to the third aspect and/or at
`least one electric vehicle according to the fourth aspect.
`Preferably, the control means is controlled by way of a
`communications channel.
`According to a seventh aspect of the invention, there is
`provided a method of charging a battery of an electric or a
`hybrid electric vehicle, the method comprising the steps of
`coupling the battery to an electricity network or subnetwork
`using inductive power transfer, transferring electrical energy
`to the battery via the network; and varying the power transfer
`according to at least one predetermined criteria.
`Preferably, the at least one predetermined criteria may
`comprise one or more of: a time of day; the level of demand
`on the network; the level of available supply in the network,
`which is particularly relevant where the energy source for the
`network is fluctuable.
`Preferably, the method further comprises the steps of cou
`pling batteries of a plurality of electric vehicles to the network
`and selectively transferring power to all or a subset thereof.
`Preferably, the method further comprises the steps of cou
`pling batteries of a plurality of electric vehicles to the net
`work; and selectively transferring power to all batteries or a
`subset thereof.
`Preferably, the method comprises the step of varying the
`electricity mains frequency to determine the battery load on
`the network.
`According to an eighth aspect of the invention there is
`provided a system for Supplying power to an electricity net
`work, the system comprising: an electricity network or Sub
`network having at least one generator, a plurality of batteries
`of a plurality of electric or electric hybrid vehicles; cabling for
`transferring energy stored in the plurality of batteries; IPT
`coupling means for coupling the batteries to the network; and
`control means for controlling the power transfer from the
`plurality of batteries to the network.
`According to a ninth aspect of the invention there is pro
`vided a method of Supplying power to an electricity network,
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`Momentum Dynamics Corporation
`Exhibit 1008
`Page 010
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`7
`the method comprising the steps of coupling a plurality of
`batteries of a plurality of electric or hybrid electric vehicles to
`the network using inductive power transfer, transferring elec
`trical energy to the network from the battery; and varying the
`power transfer according to at least one predetermined crite
`ria.
`According to a tenth aspect of the invention there is pro
`vided a system for controlling load demand in an electricity
`network, the system comprising: an electricity network hav
`ing at least one generator, the frequency of power Supplied by
`the network being allowed to vary; at least one load connected
`to the network; and control means to monitor the frequency of
`power Supplied by the network, the control means increasing
`or reducing power consumed by the load dependent on the
`frequency.
`According to an eleventh aspect of the invention there is
`provided a method of controlling load demand on an electric
`ity network, the method comprising: allowing the frequency
`of power Supplied by the network to vary; monitoring the
`frequency of power Supplied by the network; and increasing
`or reducing the power consumed by the load dependent on the
`frequency.
`Further aspects of the invention, which should be consid
`ered in all its novel aspects, will become apparent to those
`skilled in the art upon reading the following description
`which provides at least one example of a practical application
`of the invention.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
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`disadvantage of requiring a cable to be plugged in. More
`particularly, according to preferred embodiments, a charging
`pad is preferably provided on the floor where the vehicle is
`usually parked, such as in the floor of a user's garage. While
`the vehicle is parked, the charging pad transfers energy to the
`vehicle's battery by Inductive Power Transfer (IPT) via a
`pickup provided on the underside of the vehicle. With nothing
`to plug in there is nothing to remember and the battery will be
`fully charged dependent only on the time available.
`The charging pad provided on the floor is energised by a
`power Supply and the magnetic field produced thereby
`couples power into the pickup attached to the vehicle and
`charges the on-board battery. Power transfer rates of up to
`around 2.2 kW are compatible with household outputs on
`most utility networks. The control of this power flow may be
`achieved using the technique described in U.S. Pat. No.
`5,293,308, which is incorporated herein by reference. Other
`methods are also within the scope of the invention.
`FIG. 1 shows a preferred relative positioning of charging
`pad 20 and vehicle 10 during charging. The pickup pad (not
`shown) is preferably of the same shape and configuration of
`charging pad 20 and is positioned on the underside of vehicle
`10 so that it is substantially directly above charging pad 20
`when vehicle 10 is parked. The magnetic flux produced by
`charging pad 20 links the two pads. There is no functional
`requirement for the pickup pad to be positioned underneath
`the vehicle but this is preferred for aesthetic reasons and
`relative ease of installation for retrofitted vehicles.
`FIGS. 2 to 5 show alternative perspective views of charging
`pad 20 according to preferred embodiments of the invention.
`More particularly, FIG. 2 shows the outer housing of the pad,
`FIG.3 shows the pad with a portion of the outer housing cut
`away to show interior detail, FIG. 4 corresponds to the view of
`FIG.3 with exterior features shown as see-through to provide
`additional detail of the internal arrangement of the compo
`nents, and FIG. 5 shows the pad with the top cover removed.
`Note that the pickup pad is of the same configuration as
`charging pad 20 and description of charging pad 20 also
`applies to the pickup pad, except that charging pad 20 is
`coupled to an electrical Supply (e.g. the mains electricity
`Supply) and the pickup pad is attached to a load (i.e., the
`vehicle battery to be charged).
`Pads 20 are preferably placed an object formed from a
`material which Substantially limits the passage of magnetic
`flux, such as a metallic backplate 21 (which is formed from
`aluminium in a preferred embodiment) with 8 ferrite bars 22
`displaced at 45 degrees with respect to each other. Bars 22 are
`held in position by rubbery moulding 23. A coil of litz wire 27
`(see FIG. 5) is linked by the magnetic flux passing through
`ferrite bars 22. Preferably, the coil of litz wire 27 is located on
`ferrite bars 22 in region 24 of pad 20 so that the coils wind
`round the generally circular body of the pad approximately
`halfway along the lengths of bars 22. Aluminium strip 25 is
`coupled or formed integral to backplate 21 to assist in con
`trolling the pattern of the flux generated. Cover 28 is coupled
`to the top of the main circular body of the pad. Cover 28 is
`formed from a material, such as PVC, or preferably a non
`toxic plastic, which does not obstruct the passage of flux
`therethrough. The particular configuration shown enables the
`pads to be relatively slim-line which is particularly important
`for the pickup pad when retrofitted to existing vehicles So as
`to maintain ground clearance.
`More particularly, backplate 21 and strip 25 are appropri
`ately coupled to work together to direct flux generated by the
`charging pad through cover 28 in a generally perpendicular
`direction to backplate 21, thereby providing for improved
`coupling between a charging pad and a pickup pad since there
`
`One or more embodiments of the invention will be
`described below by way of example only and without intend
`ing to be limiting with reference to the following drawings, in
`which:
`FIG. 1 is a perspective view showing a preferred relative
`positioning of an IPT charging pad and an electric Vehicle
`during charging;
`FIG. 2 is a perspective view of a preferred embodiment of
`an IPT pad;
`FIGS. 3 to 5 are alternative perspective views of the
`embodiment of the IPT pad of FIG. 2, with portions removed
`in FIGS. 3 and 5, and portions shown in ghost outline in FIG.
`4 so as to show internal detail;
`FIG. 5A is a view of an alternative embodiment of an IPT
`pad configuration;
`FIG. 5B is a plan view of the alternative embodiment of the
`IPT pad of FIG. 5A;
`FIG. 6 is a schematic representation of an electric vehicle
`being charged according to an embodiment of the invention;
`and
`FIG. 7 is a schematic representation of an embodiment of a
`system according to the invention.
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`DETAILED DESCRIPTION OF PREFERRED
`EMBODIMENTS
`
`Embodiments of the invention provide for a multi-source
`electric vehicle that is able to operate in most situations that
`may occur in terms of types, length and frequency of trips.
`References to “multi-source electric vehicles' are used to
`refer to electric Vehicles embodying or capable of operating
`with embodiments of the present invention where the batter
`ies and/or cells used to power the vehicle may be charged
`using various electrical power sources. Embodiment