U.S. patent application number 13/004793 was filed with the patent office on 2011-07-07 for high power wireless resonant energy transfer system.
Invention is credited to Laszlo Farkas.
Application Number | 20110163542 13/004793 |
Document ID | / |
Family ID | 39325207 |
Filed Date | 2011-07-07 |
United States Patent
Application |
20110163542 |
Kind Code |
A1 |
Farkas; Laszlo |
July 7, 2011 |
HIGH POWER WIRELESS RESONANT ENERGY TRANSFER SYSTEM
Abstract
A high power wireless resonant energy transfer system transfers
energy across an airgap.
Inventors: |
Farkas; Laszlo; (Ojai,
CA) |
Family ID: |
39325207 |
Appl. No.: |
13/004793 |
Filed: |
January 11, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11978000 |
Oct 25, 2007 |
7880337 |
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13004793 |
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60854673 |
Oct 25, 2006 |
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Current U.S.
Class: |
290/2 ;
180/65.21; 191/10; 307/104; 320/108; 320/109 |
Current CPC
Class: |
H02J 1/16 20130101; Y02T
10/7022 20130101; B60L 53/126 20190201; Y02T 90/163 20130101; H02J
50/90 20160201; B60L 2200/28 20130101; H02J 7/0042 20130101; Y02T
90/34 20130101; H02J 50/40 20160201; Y02E 60/00 20130101; B60L
50/30 20190201; H02J 50/70 20160201; Y02T 90/128 20130101; B60L
53/122 20190201; B60L 2200/26 20130101; Y02T 10/7094 20130101; H01F
38/14 20130101; Y02E 20/14 20130101; H02J 7/34 20130101; Y04S
10/126 20130101; B60L 53/63 20190201; Y02E 60/721 20130101; Y02T
90/40 20130101; B60L 2200/36 20130101; H02J 50/12 20160201; Y02T
90/121 20130101; Y02T 90/14 20130101; Y02T 90/12 20130101; Y02T
90/122 20130101; Y02T 90/16 20130101; H02J 7/025 20130101; B60L
58/40 20190201; H02J 5/005 20130101; B60L 50/40 20190201; Y02T
10/70 20130101; Y02T 10/7072 20130101 |
Class at
Publication: |
290/2 ; 320/108;
320/109; 307/104; 191/10; 180/65.21 |
International
Class: |
F01K 17/02 20060101
F01K017/02; H02J 7/00 20060101 H02J007/00; H01F 38/14 20060101
H01F038/14; B60L 9/00 20060101 B60L009/00 |
Claims
1. A method for wireless energy transfer, comprising: providing an
electrified surface comprising one or more energy transmission
systems adapted to wirelessly transfer energy across an airgap;
positioning an electrically chargeable vehicle comprising a energy
reception system within electromagnetic proximity of said
electrified surface; establishing a resonant inductive coupling
between said energy transmission system and said energy reception
system; establishing input unity power factor, maximum real power
transmission and low switching losses at an operating switching
frequency range of 17 kHz to at least 35 kHz; auto-adjusting an
energy transfer frequency to compensate for misalignment between
said electrified surface and said electrically chargeable vehicle;
regulating said wireless energy transfer to full power (10 kW-150
kW) based on the charge state or propulsion requirements of said
electrically chargeable vehicle transferring energy from said
electrified surface to said electrically chargeable vehicle.
2. The method of claim 1, wherein said one or more energy
transmission systems are arranged in a series array along a
center-line of said electrified surface.
3. The method of claim 2, wherein said one or more energy
transmission systems are on said electrified surface.
4. The method of claim 2, wherein said one or more energy
transmission systems are within said electrified surface.
5. The method of claim 1, wherein said one or more energy
transmission systems are above said electrified surface.
6. The method of claim 1, wherein said electrically chargeable
vehicle is adapted for wireless and/or wired energy transfer.
7. The method of claim 1 further comprising, establishing a natural
resonant frequency of the inductively coupled energy transmission
system and energy reception system.
8. The method of claim 7, wherein establishing said natural
resonant frequency comprises detecting a resonant frequency change
due to the coupling of said energy transmission system and said
energy reception system
9. The method of claim 1, wherein said one or more energy
transmission systems comprise at least one pair of primary coils,
with the coils of each pair arranged in a ferromagnetic or
diamagnetic core magnetic diverter and substantially coplanar with
each other.
10. The method of claim 1, wherein said energy reception system
comprises at least one pair of secondary coils, with the coils of
each pair arranged in a ferromagnetic or diamagnetic core magnetic
diverter and substantially coplanar with each other.
11. The method of claim 1, wherein said electrically chargeable
vehicle is stationary.
12. The method of claim 1, wherein said electrically chargeable
vehicle is in motion.
13. The method of claim 1, wherein said airgap between said energy
transmission system and said energy reception system is from 7 cm
to at least 18 cm.
14. A wireless resonant energy transfer system, comprising: an
electrified surface comprising a energy transmission system adapted
to wirelessly transfer energy across an airgap; and an E-Pod,
comprising: a wheel assembly removably attached to a vehicle, said
wheel assembly comprising at least one pair of tires; a wireless
energy reception system arranged on said wheel assembly and adapted
to receive wirelessly transmitted energy from said energy
transmission system; a propulsion system comprising an electric
motor arranged on said wheel assembly; and an electronic controller
interface system arranged to electrically connect said wheel
assembly with said vehicle to control said propulsion system from
said vehicle.
15. The system of claim 14, wherein said energy transmission system
comprises at least one pair of primary resonant circuits, each one
of said at least one pair arranged to inductively couple with
another of said at least one pair.
16. The system of claim 14, wherein said energy transmission system
comprises at least one pair of primary coils, said coils of each
pair arranged in a ferromagnetic or diamagnetic core magnetic
diverter and substantially coplanar with each other.
17. The system of claim 16, wherein said at least one pair of
primary coils comprises laminated, multistrand, or Litz-wire.
18. The system of claim 14, wherein said energy reception system
comprises at least one pair of secondary resonant circuits, each
one of said at least one pair arranged to inductively couple with
another of said at least one pair.
19. The system of claim 14, wherein said energy reception system
comprises at least one pair of secondary coils, said coils of each
pair arranged in a ferromagnetic or diamagnetic core magnetic
diverter and substantially coplanar with each other.
20. The system of claim 19, wherein said at least one pair of
secondary coils comprises laminated, multistrand, or Litz-wire.
21. The system of claim 14, wherein said wheel assembly is adapted
to be lowered when said E-pod is in electromagnetic proximity of
said an electrified surface, such that said at least one pair of
tires contact a roadway surface.
22. The system of claim 21, wherein said propulsion system is
adapted to provide most of the propulsion energy for said
vehicle.
23. The system of claim 14, wherein said propulsion system is
powered by said wirelessly transmitted energy to propel said
vehicle.
24. The system of claim 14, wherein said vehicle is electric or
plug-in electric.
25. The system of claim 14, wherein said vehicle is a
hybrid-electric and plug-in electric extended range propulsion
vehicle.
26. The system of claim 14, wherein said vehicle is an electric or
electrically aided cargo vehicle.
27. The system of claim 14, wherein said airgap between said energy
transmission system and said energy reception system is from 7 cm
to at least 18 cm.
28. A method for wireless energy transfer, comprising: providing an
electrified surface comprising one or more energy transmission
systems adapted to wirelessly transfer energy across an airgap;
providing a vehicle comprising an E-Pod, wherein said E-Pod
comprises an energy reception system adapted to receive wireless
energy from said one or more energy transmission systems;
positioning said vehicle within electromagnetic proximity of said
electrified surface; establishing a resonant inductive coupling
between said energy transmission system and said energy reception
system; auto-adjusting an energy transfer frequency to compensate
for misalignment between said electrified surface and said E-Pod;
lowering a wheel assembly of said E-Pod such that at least one pair
of tires of said wheel assembly contact a roadway surface;
providing power to a propulsion system of said E-Pod from said
energy transmission system such that said propulsion system
provides most of the propulsion energy for said vehicle.
29. A method for combined heat and power generation and wireless
resonant energy transfer, comprising: providing a local energy
generation system arranged to generate, store and provide energy
for a local site and for an electrically chargeable vehicle in
electromagnetic proximity to said local site; providing energy to
said local energy generation system from one or more sources;
capturing any heat generated from said one or more sources
providing energy to said local energy generation system; storing
energy produced by said local energy generation system in an energy
storage unit; distributing energy produced by said local energy
generation system to one or more outputs; determining which of said
one or more outputs to distribute energy to based on the load of
said one or more outputs to said local energy generation
system.
30. The method of claim 29, wherein said local energy generation
system comprises an energy transmission system comprising at least
one pair of primary coils arranged to form a common resonant
circuit and adapted to provide wireless energy to said electrically
chargeable vehicle.
31. The method of claim 30, wherein said electrically chargeable
vehicle comprises an energy reception system adapted to receive
wireless energy transmitted from said energy transmission system
due to a resonant inductive coupling between said energy
transmission system and said energy reception system.
32. The method of claim 31, wherein said energy reception system
comprises at least one pair of secondary coils.
33. The method of claim 31, wherein said local energy generation
system comprises a controller for transferring stored energy back
from said power reception system to said power transmission
system.
34. The method of claim 29, wherein said one or more sources
providing energy to said local energy generation system comprises
said energy storage unit, an alternative energy source, a renewable
energy source, or a bio-municipal waste-to-energy source.
35. The method of claim 29, wherein said electrically chargeable
vehicle is in electromagnetic proximity to said local energy
generation system for an extended period of time, such that the
load to said local energy generation system is low.
36. The method of claim 29, wherein said local energy generation
system comprises a multi-directional converter for controlling the
energy distribution to said one or more outputs.
37. The method of claim 29, wherein said one or more outputs
comprises said local site, said energy storage unit, said energy
transmission system, or a microgrid.
38. The method of claim 29, wherein said energy storage unit
comprises a battery, a capacitor bank or a flywheel.
39. The method of claim 29, wherein said electrically chargeable
vehicle is electric or plug-in electric.
Description
[0001] This continuation application claims the benefit of
application Ser. No. 11/978,000, filed Oct. 25, 2007, which claims
the benefit of provisional application No. 60/854,673 to Farkas
filed on Oct. 25, 2006.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to a high power wireless resonant
energy transfer system.
[0004] 2. Description of the Related Art
[0005] Traditional electrical energy sources used to power vehicles
and buildings typically rely on centralized production and a
long-distance redistribution network of transmission lines to
provide electrical energy to consumers. The centralized production
of energy itself can be both inefficient (with only .about.30-35%
efficiency) and highly polluting. Additionally, most of the fossil
fuels used for electric power generation produce waste heat at the
power plants and in the transmission lines. This heat can lost to
the environment.
[0006] Although electric vehicles may help offset some of this
pollution, as well as pollution caused by their gasoline
counterparts, such vehicles must typically recharge their onboard
batteries on a regular basis by physically plugging into an
electrical source. Mass transit vehicles, such as electrically
powered busses, vans and other higher occupancy vehicles, run
continuously for extended periods of time, and hence require
multiple recharges over shorter periods of time.
SUMMARY OF THE INVENTION
[0007] One aspect of the invention provides a high power wireless
resonant energy transfer system, comprising an energy transmission
system that is arranged to wirelessly transfer energy across an
airgap. An energy reception system is positioned to receive the
transferred energy across the airgap through a resonant inductive
coupling between the transmission and reception system. The energy
transmission system is arranged to automatically and electronically
vary the spatial direction of the resonant inductive coupling with
the alignment between the transmission and reception system, such
that energy transfer occurs at a desired location, frequency and
power level.
[0008] Another aspect of the invention provides a combined heat and
power generation, comprising a local energy generation system that
is arranged to generate and provide electrical energy for a local
site and for an electrically chargeable vehicle in proximity to the
local site, used in conjunction with the previously described high
power wireless resonant energy transfer system.
[0009] Another aspect of the invention provides a method to
wireless energy transfer that includes positioning an electrically
chargeable vehicle within electromagnetic proximity of a
transmitter, modulating a phase angle of an input signal to a
transmitter to locate an optimal electromagnetic field distribution
for energy transfer and auto-adjusting an energy transfer frequency
based on a position of the energy receiver. Auto-adjusting of an
energy transfer power is accomplished by modulating a pulse width
of an input signal to the transmitter. The transmitter transfers
energy to the receiver.
[0010] Another aspect of the invention provides a detachable E-pod,
comprising a wheel assembly that is removably attached to a
vehicle. A wireless energy reception system is arranged on the
wheel assembly to receive wirelessly transmitted energy from an
energy transmission system. A propulsion system comprising an
electric motor is arranged on the wheel assembly and fueled by the
wirelessly transmitted energy to move the vehicle. An electronic
controller interface system is arranged to electrically connect the
wheel assembly with the vehicle to control the propulsion system
from the vehicle.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a diagram illustrating one embodiment of a high
power wireless resonant energy transfer system that uses a roadside
and pickup array to wirelessly transfer energy.
[0012] FIG. 2 is a schematic diagram showing a dual coil assembly
array.
[0013] FIG. 3(a) is a perspective view and FIG. 3(b) is a
cross-sectional view showing one arrangement of a roadside and
pick-up array.
[0014] FIG. 4 is a schematic diagram illustrating resonantly
inductive roadside and pick-up arrays.
[0015] FIGS. 5(a) and 5(b) are diagrams showing an example of the
magnetic flux performance of a wireless energy transfer magnetic
structure.
[0016] FIGS. 6(a), 6(b), and 6(c) are diagrams showing the magnetic
flux lines and directional gradient of an energy transmission
system.
[0017] FIG. 7(a) is a graphical representation of the voltage and
current outputs of a multi-phase converter. FIG. 7(b) is a graph
presentation illustrating some typical vehicle charging power
parameters during operation generated from actual test data
obtained from a 100 kW energy transfer Test-Stand.
[0018] FIGS. 8(a), 8(b), and 8(c) are diagrams showing magnetic
field density vector gradients.
[0019] FIG. 9 is a schematic diagram showing a wireless energy
transfer with multiple roadside arrays.
[0020] FIG. 10 is a schematic diagram showing a local energy
generation system that can be used in conjunction with a wireless
energy transfer system.
[0021] FIG. 11 is a schematic diagram showing an electrified
highway lane wireless energy transfer power equivalent circuit.
[0022] FIGS. 12(a) and 12(b) are perspective views showing an
electrified highway roadway array.
[0023] FIG. 13 is a diagram showing a cargo truck operating on an
electrified highway.
[0024] FIG. 14 is a perspective view showing an E-pod.
[0025] FIG. 15 is a perspective view illustrating an E-pod attached
to a cargo truck.
[0026] FIG. 16 is a perspective view showing a Bumper-Charger
mounted to a bus.
[0027] FIG. 17 is a schematic diagram showing a co-resonant
inductive array circuit equivalent.
[0028] FIG. 18(a) is a graph illustration showing the magnetic
field strength of a co-resonant array. FIG. 18(b) is a perspective
view of a co-resonant wireless energy transmission system.
[0029] FIG. 19 is a perspective view of a vehicle using a
co-resonant energy transmission system.
[0030] FIG. 20 is a flow diagram showing a method for wireless
energy transfer.
DETAILED DESCRIPTION OF THE INVENTION
[0031] FIG. 1 illustrates one embodiment of a high power wireless
resonant energy transfer system. This embodiment includes an energy
transmission system 105 for wirelessly transmitting energy to an
energy reception system 106 when the transfer system is
activated.
[0032] The energy transmission system 105 is preferably disposed
beneath a roadway surface, although transmission systems disposed
on the surface are contemplated as well. The energy reception
system 106 is preferably disposed on the undercarriage of a vehicle
101, which uses the transferred electrical power to either charge
an onboard energy storage device unit 115 or for propulsion/use
directly. The storage unit 115 typically includes a set of
batteries and/or capacitors which store the energy until it is
needed by the vehicle for propulsion. This storage and use is
typically controlled by onboard power electronics 110. Although
FIG. 1 shows a particular arrangement of this embodiment, other
arrangements are also possible. For example, the energy
transmission system 105 can be located above vehicle 101, rather
than beneath a roadway surface, and the energy reception system 106
can be disposed on the top of vehicle 101. Additionally, the energy
storage system 115 and onboard power electronics 110 may be
disposed anywhere in or on the vehicle.
[0033] FIG. 2 illustrates an energy transmission system with a
single flat magnetic assembly that includes ridge 309 that divides
the single magnetic assembly into sections 305 and 306.
Alternatively, two separate magnetic assemblies can be arranged
adjacently to form sections 305 and 306 and ridge 309. The magnetic
assembly is preferably a ferrite core magnetic diverter, and can be
alternatively referred to as a magnetic core. Conductive coil
windings 202 and 201 are preferably arranged within each section
such that the top of the coil structure is preferably flush with
the top surface of its respective magnetic assembly, although this
is not required. Each coil structure 201 and 202 include input
leads 308 and 307, respectively, for receiving input current. The
magnetic assembly and pair of coil-windings together form a
roadside array, or transmission array.
[0034] FIGS. 3(a) and 3(b) show one arrangement of the energy
reception system 106, used in conjunction with the energy
transmission system 105 of FIG. 2. Like the energy transmission
system 105, the reception system 106 preferably has a flat magnetic
assembly with ridge 309 that creates sections 405 and 406, as well
as coils 203 and 204 arranged in each section 405 and 406. The
reception system 106 is also known as a pick-up array, or
reception/receiver array.
[0035] For both the transmission system 105 and the reception
system 106, the coil windings are preferably multi-turn Litz-wire,
which can help reduce any skin effects that can occur at the
typical 20-30 kHz operational frequency. The Litz-wire coils are
preferably wound flat into a composite material case, and are
typically secured on the case of the magnetic cores 305 and 306 as
one single assembly, though other assemblies are contemplated as
well.
[0036] The magnetic cores are preferably tile-shaped low loss power
ferrites with material composition optimized for 10-50 kHz power
transformer application. The magnetic ridge between the coils sets
the coupling coefficient between the adjacent coils. The pole face
in the center of the coils improves the coupling coefficient
between the transmitter and receiver magnetic assemblies. The
assembly is preferably a `flat magnetics` construction with less
than 1'' overall thickness for ease of roadway and vehicle
installation.
[0037] During operation, the transmission system 105 and reception
system 106 are preferably arranged such that the coils 201 and 202
of transmission system 105 face the coils 203 and 204 of the
reception system 106 as shown in FIG. 3(a) and FIG. 3(b). FIG. 3(b)
shows a cross section of the energy transmission and reception
system in one arrangement used during operation. An airgap between
transmission system 105 and reception system 106 separates the
receiver and roadside arrays. This airgap may not be even, and the
transmission and reception systems may not be aligned during
typical operation. Despite the airgap and any potential
misalignment, energy transfer from the transmission system 105 to
the reception system 106 occurs due to resonant inductive coupling
between the roadside and pick-up arrays.
[0038] FIG. 4 shows one example of a simplified circuit schematic
that produces the resonant inductive coupling effects. Various
other circuit details and elements are assumed, and not shown. The
energy transmission system includes at least one roadside array,
which comprises primary magnetic core windings Lp1 and Lp2. Lp1
includes coil winding 202 arranged in section 305 of a magnetic
core, and Lp2 includes coil winding 201 arranged in section 306 of
the same or adjacent magnetic core used in Lp1, as previously
described. Lp1 and Lp2 are each also known as "primaries", "primary
coils" or "primary windings".
[0039] The two primaries are connected to H-Bridge converters 440
and 441 of Multi-Phase Converter ("MPC") 130 through capacitors
CR-1 and CR-2, as shown in FIG. 4. The combination of each primary
winding and its capacitor forms a single resonant circuit. Because
the coil winding 201 installed on core 306 and winding 202
installed on core 305 are coplanar and arranged next to each other,
Lp1 and Lp2 inductively couple. Due to this coupling between the
two primaries, the two series resonant circuits resonate at a
common frequency when the primaries are simultaneously supplied
with current by the MPC 130.
[0040] FIG. 4 also illustrates the energy reception system 106 that
includes at least one pick-up array comprising magnetic core
windings Ls1 and Ls2. Ls1 includes coil winding 204 arranged in
section 405 of a magnetic core, and Ls2 includes coil winding 203
arranged in section 406 of the same or adjacent magnetic core used
in Ls1. Ls1 and Ls2 are also coupled to each other in the same
manner as the primaries. Ls1 and Ls2 are also known as
"secondaries", "secondary coils", or "secondary windings".
[0041] When the secondary coils are brought within proximity of an
energized set of primary coils, several coupling effects influence
the overall flux coupling and hence the peak power of the energy
transferred across the airgap. One coupling effect involves the
secondary coils inductively coupling to the primary coils, thereby
introducing an additional complex load to the otherwise undamped
(high Q) series-resonant circuits formed by Lp1 and Lp2 and their
corresponding capacitors. This additional complex load is typically
caused by various elements connected to energy reception system
106, typically including the energy storage battery 451 and/or
capacitor 450 of the vehicle, as well as other elements. Due to
coupling between the secondary and primary coils, the resonant
circuit of the energy transmission system experiences this complex
impedance, and thus the circuit resonant frequency and quality
factor (Q) change. The frequency change is detected by an
auto-frequency tracking regulator which is part of the PWM
electronics 442 that are part of Multi-Phase Converter 130. The
auto-frequency tracking regulator is configured to synchronize the
input H-Bridge 440 and 441 to switch relative to the zero-crossing
time instances of the measured resonant current signal. Thus, the
switching frequency is locked to the natural resonant frequency of
the entire primary, secondary and load circuit. As the natural
resonant frequency measured by the resonant current signal changes
due to the load and airgap size variations, the input switching
frequency is preferably locked to the natural frequency. The
coupling distance is defined by the airgap between the energy
transmission system 105 and the energy reception system 106. The
natural resonant frequency typically varies by a few kHz due to the
load and airgap. Thus, the peak power transferred over the airgap
is affected. The power variation is regulated by the same PWM
electronics which change the pulse width of the switching devices
in H-bridge 440 and 441. In this manner, the peak power transferred
is automatically adjusted to compensate for the size of the airgap
and the secondary circuit's load.
[0042] Another coupling effect that influences the peak power
transfer is that which occurs between each of the primary coils and
between each of the secondary coils. These couplings assure a
common system resonant frequency for the pair of resonant circuits.
The couplings also keep the relative current change in the
primaries identical during directional phase-control. For example,
as shown in FIG. 7(b), Current A increases and Current B decrease
symmetrically during relative phase-control mode. The relative
phase control between the pair primary resonant circuits is
preferably accomplished by the PWM electronics.
[0043] Additionally, each of the primary coils cross-couples with
each secondary coil, thereby contributing to the total inductance
and to the coupling coefficient between the roadside and pickup
arrays.
[0044] The described coupling effects combine to influence coupling
coefficients between the different inductive elements and hence
define the system's common resonance frequency and overall energy
transfer capability. For large airgaps (7''-9''), the net coupling
coefficient can be smaller (in the range of K.sub.c=0.6-0.7), than
in equivalent power transformers. Transferring energy over large
airgaps in resonant mode may also require significant reactive/real
power ratio in the resonant circuit, which can lower power
transmission efficiency. Transmission of 100 kW power can be
achieved over 7'' airgap at 85% efficiency. Operating resonant
frequency for this performance can be typically between 20-30 kHz.
However, other airgap sizes, amount of power and frequency ranges
are also contemplated.
[0045] The desired location of the energy transfer itself is
preferably along the central plane between energy transmission
system 105 and energy reception system 106 shown in FIG. 3(b), or
at least limited to the area between the transmission and reception
systems. The currents supplied to the primary coils preferably flow
in the same direction, as shown in FIG. 2, thereby causing the
electromagnetic flux density to concentrate along the center axis
of the roadside and pick-up arrays as shown in FIG. 5(a). As shown
in FIGS. 5(a) and 5(b), the field density and location of energy
transfer can concentrate beneath a vehicle center line and taper
off along the edges. Residual stray field outside the envelope of
the vehicle can thus be minimized.
[0046] As shown in FIGS. 6(a), 6(b) and 6(c), the wireless transfer
system can also automatically compensate for horizontal
misalignment between the energy transmission system 105 and
reception system by adjusting the spatial direction of the energy
transfer. MPC 130 can perform this spatial direction adjustment by
varying the relative phase angle between the input currents
provided to the roadside array's primary coils 201 and 202 by
switchmode single phase converters 440 and 441 (shown in FIG. 4).
The phase converters generate a square wave bipolar output that can
be used to excite the energy transmission system 105. The phase
converters can be synchronized to the zero crossing of the resonant
current, so that the excitation frequency trails the resonant
frequency. When the resonant frequency changes due to a load
introduced by the presence of secondary coils, these converters can
follow the resonant frequency and thus maintain a high power factor
for efficient real power transfer. For example, FIG. 7(a) shows an
input PWM voltage and resonant current I-1 and I-2. The relative
phase-angle between the driving voltages V-1 and V-2 can change the
relative magnitudes of I-1 and I-2, which can produce the field
gradient shift shown in FIGS. 6(a), 6(b) and 6(c) and FIGS. 8(a),
8(b) and 8(c). The gradient vector tilt can also produce the
current magnitude variation in the outputs, causing the transferred
power to also vary between the pair of receiver coils 203 and 204.
However, the total power transferred preferably remains constant.
Power in excess of 100 kW can be transferred over large air-gaps
(7-9'') at a frequency ranging from 20-30 khz. However, other
airgap sizes, amount of power, and frequency ranges are also
contemplated.
[0047] In another embodiment of the wireless transfer system,
multiple roadside arrays can be arranged to provide an energy
transfer system that can be used for larger vehicles. FIG. 9 shows
one implementation of this embodiment, where an additional roadside
array 505 can be added to increase the size of the energy transfer
system. Directional control can be enhanced, since the
electromagnetic field of each array can be spatially directed
independently. Additionally, multiple pick-up arrays can be used to
receive wireless energy transfer ("WET") to power multiple loads
independently. Roadside arrays 505 and 105 can both be connected to
a multi-phase converter to receive current, which is preferably
supplied so that the generated electromagnetic flux combines to
transfer energy in the same direction.
[0048] FIG. 10 shows another embodiment of the high power wireless
resonant energy transfer system. This embodiment provides a local
energy source that can power buildings and equipment at the local
site and/or wirelessly transmit the generated energy to an
electrically chargeable vehicle using the same or similar energy
transmission 105 and reception system 106 discussed for the first
embodiment.
[0049] In this embodiment, a Power Mixing Converter (PMC) 135 can
receive energy from one or more sources, and can coordinate the
distribution of that energy to one or more outputs. One source of
energy includes one or more microturbine generator(s) 150, which
can convert fuel from one or more fuel sources into energy. These
fuel sources can include, but are not limited to, a methane source
153, natural gas source 152, and/or hydrogen source 156. The fuel
sources are preferably stored on-site for convenience, but can also
be transported in through pipe or by other means. Heat generated by
the microturbine 150 can be captured in a heat exchanger 160, and
can be used for heating and cooling needs at the site, such as
warming water, or driving a turbine to provide additional
electrical power to the site.
[0050] Other energy sources for the PMC 135 can include energy from
renewable sources 134, such as solar and wind power. PMC 135 can
also receive energy from other sites connected through microgrid
136 and from the standard utility grid 139, as well as one or more
on-site energy storage units, such as flywheel(s) 137, and/or one
or more battery banks 138. The PMC 135 can select its energy
source(s) based on a variety of factors, including, but not limited
to source availability, storage capacity and real-time costs of
each of the energy sources.
[0051] In addition to receiving energy from one or more sources,
the PMC 135 can also distribute energy to one or more outputs.
These outputs include, but are not limited to, the site facility
power distribution system 132 for powering the site itself, one or
more flywheel storage banks 137 and battery banks 138 for load
leveling and backup power, the microgrid 136 for powering other
sites, the standard utility grid 139, and the MPC 130 for
wirelessly transferring the energy to an electrically chargeable
vehicle through arrays 105 and 107. The PMC 135 can also calculate
which output to send the energy to. For example, during low load
periods, the PMC 135 may choose to output energy to the fly-wheel
storage 137 or battery bank 138 for storage. During peak load
periods, the PMC 135 can draw power from the fly-wheel storage 137
and/or battery banks 138 to provide load-leveling. PMC 135 can
determine its energy source and outputs either in real-time or by
using past data. Thus, the PMC 135 can optionally calculate energy
trends over a period of time, and even optionally anticipate and
adjust for energy supply and demand. Typical PMC 135 energy
transfers can involve between 250 kW to 2 MW of power.
[0052] Another embodiment of the high power wireless resonant
energy transfer system includes providing an electric vehicle with
the transmission reception system 106 of the previous embodiment,
onboard power electronics (OPE) 110, and onboard energy storage
device (OSD) 115, as shown in FIG. 4. The OPE 110 preferably can
rectify an input AC voltage from the wireless reception system 106,
and can supply the output DC current to the OSD 115. The OSD 115
comprises a battery bank 451 preferably capable of storing at least
five miles of propulsion energy (typically 10 kWh for a 40' bus)
and a mega-capacitor (MegaCap) 450 capable of providing sufficient
energy to accelerate the vehicle and receiving the initial charging
current surge from the wireless transmission system. A steering
inverter (not shown) within the OPE can be arranged to control the
power flow into and out of battery bank 451 and mega-capacitor 450.
In another embodiment, the OPE is configured to invert power back
to the roadside energy storage through providing PWM power to the
secondaries drawn from the OSD. The primary resonant circuit can
feed the resonant current back to the DC bus through the H-Bridge
converters operating in rectifier mode. In this embodiment the
vehicle can operate as an emergency or standby power source for
site equipment. Preferably, the battery bank 451 comprises
batteries made of NiMH or Li-Ion, but other types of energy storage
devices are contemplated as well.
[0053] Another embodiment of the high power wireless resonant
energy transfer system shown in FIG. 20 provides a method for
wireless energy transfer, comprising positioning an electrically
chargeable vehicle within electromagnetic proximity of a
transmitter. A beam-searching of the receiver can be performed by
modulating a phase angle of an input signal to a transmitter to
locate an optimal electromagnetic field distribution. Typical
beam-searching modulation is shown in FIG. 7(b), where Current A
(I-1) and Current B (I-2) symmetrically modulated in both
directions, and then return to the center position. An
auto-adjustment of an energy transfer frequency based on a position
of the energy receiver can be accomplished. An auto-adjusting of an
energy transfer power can be performed by modulating a pulse width
of an input signal to the transmitter. Energy can be transferred
from the transmitter to the receiver. Additionally, power can be
generated at a local site to power the site and the
transmitter.
[0054] Another embodiment of the wireless transfer system provides
for activating the energy transfer system shown in FIG. 1. This
embodiment uses the same wireless transmission and reception system
described in the first embodiment. As vehicle 101 approaches
transmission system 105, its onboard computers can send a signal to
activate the energy transmission system 105. This signal is
preferably sent automatically, and may be encrypted. As the vehicle
101 comes to a rest over transmission system 105, transmission
system 105 can transmit an electromagnetic beam to search for the
position of the reception system 106. Once transmission system 105
determines the location of the reception system using the
electromagnetic beam sweep, it automatically adjusts the location
of the energy transfer to maximize the transfer.
[0055] Another embodiment of the high power wireless resonant
energy transfer system provides an E-pod and an electric highway
for continuous electrical propulsion power for heavy highway
vehicles, such as cargo trucks and 40'-60' rapid transit buses. In
this embodiment, an energy reception system can be mounted to the
undercarriage of a vehicle to collect power from a series of
road-surface energy transmission systems that have transmission
arrays. The activated transmission arrays directly under the
vehicle can provide most of the vehicle's propulsion energy. Thus,
the vehicle needs only a small energy storage onboard. The roadway
transmission arrays are preferably active for the short period of
time required for the vehicle to pass over the array. Thus, the
output power transmitted can be high but the duty cycle is small.
The pickup coils of the moving vehicle, however, see a practically
continuous power-rail.
[0056] The equivalent circuit schematic diagram in FIG. 11 shows a
typical dual coil arrangement for the roadway magnetic pad. The
Dual-Phase Converter drives LP-1 and LP-2 coil segments such that
the currents oppose each other in the return path. The coils are
preferably on the top surface of the magnetic core, and the coaxial
returns are underneath with the Dual-Phase converter packaged into
the roadway assembly.
[0057] The roadway pad is shown in FIGS. 12(a) and 12(b). The
roadway pad can comprise a ferrite magnetic core 1001, the two
coils 1002 and 1003, and the Dual-Phase Inverter 1005. The coaxial
returns 1006 and 1007 connect the coils to the converter.
[0058] The roadway pads can be lined up in the middle of a highway
lane such that the vehicles activate the pads as they pass over
them. Otherwise the pads are deactivated. FIG. 13 shows one example
of an Electrified Highway Lane using the pads of FIG. 12. Vehicle
601--a cargo truck--passes over the row of roadway pads 801, and
the attachable E-Pod 701 collects the energy from the activated
pads.
[0059] The E-Pod shown in FIG. 14 is one embodiment of an
attachable wireless energy transfer module for large vehicles,
which has the effect of converting the diesel vehicle into a
hybrid-electric vehicle due to the attached E-pod. The E-Pod of
FIG. 14 comprises the pickup coils 705 and 706, the HF rectifiers
712, battery packs 710 and the electric motor drive 715. This E-Pod
has two sets of these components driving the front and back wheels
separately. Other variations are also possible.
[0060] In this cargo truck embodiment, the E-Pod 701 can be rolled
under and installed to the bottom frame of the cargo container
section 610 (shown in FIG. 13). FIG. 15 shows the E-Pod 701
installation under the cargo truck 601. The electronic interface to
the driver can be plugged in so that the Rig is operating in
dual-mode. When the vehicle travels over an electrified section of
the highway, the E-Pod can be hydraulically lowered so that the
wheels contact the roadway surface, and the electric drives can be
activated to take over most of the propulsion power from the diesel
tractor. During braking, the regenerated power can be fed back to
the E-Pod batteries.
[0061] Preferably, the electrified lanes of the highway align the
Wireless Energy Transfer roadway assemblies such that the dual coil
pickup assemblies hover over the activated segments of the roadway.
Thus, full power transfer can be spread over a longer
distance--such as 16' to 24'--under the E-Pod. Through sequential
activation, the power availability wave remains just under the
E-Pod at all times, while the other segments under the Rig and on
the highway idle preferably without power.
[0062] The power system feeding an Electrified Highway Lane can
include a set of stationary Solid Oxide Fuel Cells (SOFC units) fed
by alternative fuel sources, and a network of interconnecting
microgrids described in a previous embodiment. Thus, the
Electrified Highway Lane can have its own distributed energy
generation system with combined heat capture and optional roadside
Hydrogen generation. Where utility power is available, inexpensive,
and environmentally acceptable, the microgrid can tap into the
utility grid system.
[0063] The E-Pod shown in this embodiment uses cargo trucks for
illustrative purposes only. Other types of vehicles, such as buses
and utility vehicles can also be fitted with an E-pod, and can
similarly use the Electrified Highway lanes for electric
propulsion.
[0064] In another embodiment of the high power wireless resonant
energy transfer system, electric or hybrid vehicles that are
regularly parked on the same location for extended period, such as
school buses and passenger cars, can use Bumper Chargers with
Wireless Energy Transfer ("WET") for replenishing their onboard
energy storage. FIG. 16 shows a school bus 901 being recharged from
an elevated Bumper Charger. The coils of the WET can be installed
in the bumper 905 of the vehicle, and on the parkway in the bumper
curb 903. The vehicle energy storage 910 can be recharged over a
few hours while the school bus is waiting. The required power is
small because of the long charging time available.
[0065] Hybrid and electric automobiles can use the WET installed in
parking lots and home driveways. An average automobile can require
about 0.3 kWh/ml for regular city cycles. Therefore, the recharge
power requirements can be modest in comparison the buses and trucks
(preferably 2.5 kWh/ml and 4 kWh/ml respectively). A medium power
alternative of the series resonant inductive coupling array can be
used to recharge power typically in the range of 5 to 15 kW. The
principle block diagram in FIG. 17 shows the co-resonant
inductively coupled phase-array technique, whose secondary
receiving circuits 1302 and 1304 are tuned to the same frequency as
the primary circuits 1308 and 1306. Although the primary circuits
are weakly coupled to the secondary circuits, the high quality
factor (Q) of the resonant circuits assures co-resonance at a
common frequency. The operating resonant frequency can be over 100
kHz. The tuned circuit comprises split coils 1050 and 1051 (Lp11
and Lp12) resonating with the coaxial capacitor 1052, which is
arranged near the middle of the LRC circuit as shown in FIG. 17.
The receiving secondary resonant circuit comprises inductors 1060
and 1061 arranged as shown with capacitor 1062. The second pair of
primary-secondary circuits 1306 and 1304, are substantially
identical. The coils preferably have an air-core, with ferrite
diverters preferably used only externally to shield residual flux
entering the vehicle. The Multi-Phase Converters 1055 and 1065 can
be integrated with the dual coil-capacitor field generators as
shown in FIG. 14. As described in a previous embodiment,
controlling the driving voltage phase angle between the primaries
generates field direction change for power optimization that
compensates for vehicle misalignment by shifting the location of
the transfer.
[0066] FIG. 18(a) shows one example of a B-vector field
distribution in a pair of primary-secondary coils. The
co-resonating primary and secondary B fields 1071 and 1072 are
dense in and around the coils, but the flux density is small in the
airgap between the roadside assembly and the vehicle.
[0067] Corresponding to FIG. 9, which shows the extended double
dual-coil configuration for the series-resonant inductive coupling
for large vehicles, FIG. 18(b) shows the equivalent four coil
configuration of the co-resonant inductive coupling for smaller
vehicles, having an MPC 1081 and coils 1082, 1083, 1084, and 1086
arranged as shown.
[0068] FIG. 19 shows a typical automobile 1010 which, once
electrified, can use the co-resonant inductive WET installed into
driveways and parking lots. WET installation under the roadway
surface preferably uses the double dual-coil phase-array 1020,
which can adjust and correct for large misalignment as described
earlier. The curb-charger variation of the WET 1015 has adjustment
for one direction. Due to the symmetry between the roadside and
onboard power conversion, the energy can flow in both directions.
Charging from the roadside can be reversed, and the energy stored
in the onboard energy storage can be fed back to the roadside. The
vehicle parked over the WET can be used as a non-contact emergency
power source.
[0069] While various implementations and embodiments of the high
power wireless resonant energy transfer system have been described,
it will be apparent to those of ordinary skill in the art that many
more are possible.
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