U.S. patent application number 14/146969 was filed with the patent office on 2014-05-01 for inductive power supply system with multiple coil primary.
This patent application is currently assigned to Access Business Group International LLC. The applicant listed for this patent is Access Business Group International LLC. Invention is credited to David W. Baarman, Scott A. Mollema, Joshua K. Schwannecke.
Application Number | 20140117760 14/146969 |
Document ID | / |
Family ID | 40561826 |
Filed Date | 2014-05-01 |
United States Patent
Application |
20140117760 |
Kind Code |
A1 |
Baarman; David W. ; et
al. |
May 1, 2014 |
INDUCTIVE POWER SUPPLY SYSTEM WITH MULTIPLE COIL PRIMARY
Abstract
An inductive power supply including multiple tank circuits and a
controller for selecting at least one of the tank circuits in order
to wirelessly transfer power based on received power demand
information. In addition, a magnet may be used to align multiple
remote devices with the inductive power supply. In one embodiment,
different communication systems are employed depending on which
coil is being used to transfer wireless power.
Inventors: |
Baarman; David W.;
(Fennville, MI) ; Mollema; Scott A.; (Rockford,
MI) ; Schwannecke; Joshua K.; (Grand Rapids,
MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Access Business Group International LLC |
Ada |
MI |
US |
|
|
Assignee: |
Access Business Group International
LLC
Ada
MI
|
Family ID: |
40561826 |
Appl. No.: |
14/146969 |
Filed: |
January 3, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13680427 |
Nov 19, 2012 |
8653698 |
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14146969 |
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12403045 |
Mar 12, 2009 |
8338990 |
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13680427 |
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61036459 |
Mar 13, 2008 |
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Current U.S.
Class: |
307/38 |
Current CPC
Class: |
H02J 50/005 20200101;
H01F 27/2871 20130101; H01F 38/14 20130101; H02J 50/12 20160201;
H04B 5/0037 20130101; H02J 50/70 20160201; H04B 5/0062 20130101;
H04B 5/0093 20130101; H02J 50/10 20160201; H02J 50/40 20160201;
H04B 5/0075 20130101 |
Class at
Publication: |
307/38 |
International
Class: |
H04B 5/00 20060101
H04B005/00 |
Claims
1. An inductive power supply for supplying wireless power to a
remote device including power demand information, said inductive
power supply comprising: a plurality of tank circuits, wherein each
tank circuit includes a primary and a capacitor electrically
connected in series, wherein each of said plurality of tank
circuits are capable of being energized to transfer power
wirelessly to the remote device; a receiver for receiving power
demand information from the remote device; and a controller in
electrical communication with said receiver and said plurality of
tank circuits, said controller programmed to select at least one of
said plurality of tank circuits to transfer power wirelessly to the
remote device, wherein said selection is determined as a function
of said power demand information received from the remote
device.
2. The inductive power supply of claim 1 wherein said plurality of
tank circuits includes a tank circuit with a low power primary
coil, a tank circuit with a medium power primary coil, and a tank
circuit with a high power primary coil.
3. The inductive power supply of claim 1 wherein said primary of
each of said plurality of tank circuits is a different gauge.
4. The inductive power supply of claim 1 wherein said receiver
includes at least one of a wireless communication system, at least
one of said tank circuits, or any combination thereof.
5. The inductive power supply of claim 1 including a coil selector
circuit for selectively energizing one or more of said plurality of
tank circuits.
6. The inductive power supply of claim 1 wherein said power demand
information includes a remote device ID, wherein said inductive
power supply includes a memory, wherein said memory includes a
look-up table, said look-up table maps remote device IDs to at
least one of said plurality of primaries.
7. An inductive power supply for supplying wireless power to a
remote device including power demand information, said inductive
power supply comprising: a first tank circuit including a plurality
of primaries, wherein each of said plurality of primaries is
capable of being energized to transfer power wirelessly to the
remote device; a receiver for receiving power demand information
from the remote device, wherein said power demand information
includes a power adjustment; and a controller in electrical
communication with said receiver and said tank circuit, said
controller programmed to select at least one of said plurality of
primaries of said tank circuit to transfer power wirelessly to the
remote device, wherein said selection is determined as a function
of said power adjustment received from the remote device.
8. The inductive power supply of claim 7 including a second tank
circuit and a third tank circuit, each including a plurality of
primaries, wherein each of said plurality of primaries of said
first and second tank circuits are capable of being energized to
transfer power wirelessly to the remote device, wherein said first
tank circuit includes a low power primary coil, said second tank
circuit includes a medium power primary coil, and said third tank
circuit includes a high power primary coil.
9. The inductive power supply of claim 8 wherein said first,
second, and third tank circuits are driven with a half bridge
driver.
10. The inductive power supply of claim 7 wherein said receiver
includes at least one of a wireless communication system, at least
one of said primaries, or any combination thereof.
11. The inductive power supply of claim 7 wherein said tank circuit
includes a coil selector circuit for selectively energizing one or
more of the plurality of primaries.
12. The inductive power supply of claim 7 wherein said controller
is programmed to determine an amount of power to be transmitted as
a function of said power adjustment received from said remote
device.
13. The inductive power supply of claim 12 including a memory,
wherein said memory includes a threshold, said controller is
programmed to select one of said plurality of primaries in response
to said amount of power to be transmitted being below said
threshold, and said controller is programmed to select a different
one of said plurality of primaries in response to said amount of
power to be transmitted being above said threshold.
14. The inductive power supply of claim 13 wherein said power
demand information includes at least one of a minimum power level
threshold, a maximum power level threshold, or a combination
thereof.
15. The inductive power supply of claim 14 wherein said controller
adjusts said threshold as a function of said at least one of said
minimum power level threshold, said maximum power level threshold,
or said combination thereof.
16. The inductive power supply of claim 7 wherein said remote
device includes a standby mode where it demands a lower amount of
power, said power demand information includes an indication that
said remote device is in standby mode, and said controller
selection is based at least in part on whether said remote device
is in said standby mode.
17. An inductive power supply for supplying wireless power to a
first remote device or a second remote device, said inductive power
supply comprising: a tank circuit including a first primary coil
and a second primary coil, wherein said first primary coil and said
second primary coil are arranged concentrically, wherein each of
said first primary coil and said second primary coil are capable of
being energizing to transfer power wirelessly; a magnet arranged
coaxially with said first primary coil and said second primary
coil, wherein said magnet provides a magnetic force to assist in
alignment, wherein said magnetic force of said magnet assists in
aligning the first remote device with said first primary coil and
wherein said magnetic force of said magnet assists in aligning the
second remote device with said second primary coil.
18. The inductive power supply of claim 17 for supplying wireless
power to at least one of a first remote device, a second remote
device, and a third remote device: wherein said tank circuit
includes a third primary coil, wherein said third primary coil is
arranged concentrically with said first and said second primary
coils, wherein said third primary coil is capable of being
energized to transfer power wirelessly; and wherein said magnet is
arranged coaxially with said first primary coil, said second
primary coil, and said third primary coil, wherein said magnetic
force of said magnet assists in aligning the third remote device
with the third primary coil.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to inductive coupling and more
particularly to systems and methods for providing multiple ranges
of inductive power.
[0002] Systems for providing wireless power using the principles of
electromagnetic inductive have been available for many years.
Conventional systems have met with limited success as a result of
practical limitations on pre-existing inductive technology. For
example, to provide reasonably efficient operation, conventional
inductive systems typically require close and precise alignment
between the primary coil and the secondary coil, as well as a high
degree of coordinated tuning between the electronics in the
inductive power supply and the electronics in the remote device.
These problems are complicated by the fact that different remote
devices may require vastly different amounts of power. For example,
a cell phone is likely to have different power requirements than a
laptop or a kitchen appliance.
[0003] Some advances have been made that allow an inductive power
supply to adjust and account for some differences between remote
devices. U.S. Pat. No. 6,825,620 to Kuennen et al discloses an
inductive power supply system that has the ability to adjust its
operation to correspond with the operating parameters of various
loads. U.S. Pat. No. 6,825,620 to Kuennen et al, which is entitled
"Inductively Coupled Ballast Circuit" and was issued on Nov. 30,
2004, and is incorporated herein by reference. U.S. patent
application Ser. No. 11/965,085 discloses an inductive power supply
system that has the ability to identify the remote device and its
operating parameters. U.S. patent application Ser. No. 11/965,085
to Baarman et al, which is entitled "Inductive Power Supply with
Device Identification" and was filed on Dec. 27, 2007, and is
incorporated herein by reference. Although these are marked
improvements over pre-existing systems, there is, in some
applications, a desire for even greater flexibility. In some
applications, there exists a desire for a single inductive power
supply that is capable of providing multiple ranges of power.
SUMMARY OF THE INVENTION
[0004] The present invention provides an inductive power supply
system and associated method that identifies a power class of a
remote device and provides inductive power as a function of that
power class. In order to provide power as a function of power
class, the inductive power supply includes a primary coil assembly
with multiple coils. Each coil is capable of being selectively
energized to produce a range of inductive power associated with a
different power class. The inductive power supply system provides
multiple ranges of power to remote devices without physical
electrical contact.
[0005] In one embodiment, the present invention includes an
inductive power supply having a controller, a coil selector circuit
and a coil assembly. In this embodiment, the coil assembly includes
a low power coil, a medium power coil and a high power coil. Each
remote device is categorized as a low power class, medium power
class or high power class device. The controller and coil selector
circuit operate to energize a selected coil. In general, the low
power coil is energized to power low power class devices, the
medium power coil is energized to power medium class devices and
the high power coil is energized to power high power class devices.
In some applications, the low power coil may be used for
authentication, identification or communication, even in medium
power class and high power class devices. The inductive power
supply may implement techniques for tuning the power provided by
the selected coil. For example, each coil may be adaptive and
capable of having its resonant frequency adjusted. Further, the
operating frequency or other operating characteristics of the
inductive power supply may vary.
[0006] In operation, the remote device communicates power demand
information with the inductive power supply, such as the remote
device power class. In one embodiment, the low power coil, when
driven, produces a time varying magnetic field. When the secondary
circuit is moved in proximity to the driven low power coil, the
secondary circuit forms a mutual inductance with the low power
coil. The low power coil's magnetic field passes through and
energizes the secondary coil. This provides power to the secondary
allowing a power class signal to be transmitted and authenticated
starting the power control sequence at the appropriate range of
power by selecting the appropriate coil.
[0007] One benefit of an inductive power supply having a coil
assembly with multiple coils is that a single hot spot may deliver
low, medium and high power to a remote device. This reduces the
need to have an inductive power supply that powers low power
devices, a separate inductive power supply to power medium power
devices and a separate inductive power supply that power high power
devices. Further, energy savings may result because higher power
devices may use a lower power coil during lower power consumption
periods. Additionally, lower power devices may draw power from a
higher power coil in order to gain spatial freedom.
[0008] These and other objects, advantages, and features of the
invention will be readily understood and appreciated by reference
to the detailed description of the current embodiment and the
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a block diagram of an inductive power supply
system in accordance with an embodiment of the present
invention.
[0010] FIG. 2 is a block diagram of a primary circuit of one
embodiment.
[0011] FIG. 3 is a block diagram of a secondary circuit of one
embodiment.
[0012] FIG. 4 is a schematic diagram of a tank circuit of one
embodiment.
[0013] FIG. 5 is a schematic diagram of an inductive power supply
system of one embodiment.
[0014] FIG. 6 is a schematic diagram of a tank circuit of one
embodiment.
[0015] FIG. 7 is a schematic diagram of an inductive power supply
system of one embodiment.
[0016] FIG. 8 is a circuit diagram of a switching circuit and tank
circuit of one embodiment.
[0017] FIG. 9 is a flowchart showing the general steps of a method
for powering a remote device.
[0018] FIG. 10 is a functional block diagram of a primary circuit
of one embodiment.
[0019] FIG. 11 is a functional block diagram of a secondary circuit
of one embodiment.
[0020] FIG. 12 is a functional block diagram of a primary circuit
of one embodiment.
[0021] FIG. 13 is a functional block diagram of a secondary circuit
of one embodiment.
[0022] FIG. 14 is a schematic diagram of an inductive power supply
system of one embodiment.
[0023] FIG. 15 shows a cross section of litz wire.
DESCRIPTION OF THE CURRENT EMBODIMENT
[0024] I. Overview
[0025] In an exemplary embodiment of the inductive power supply
system of the present invention depicted in FIG. 1 and designated
100, the inductive power supply system includes an inductive power
supply 102 and a remote device 104. The inductive power supply
includes a primary circuit 103 having a primary coil assembly 101
capable of generating multiple ranges of power. The remote device
104 includes a secondary circuit 105 having a load 106. The
secondary circuit 105 of the remote device includes power demand
information that may include a power class. The power demand
information may be transmitted to the inductive power supply 102 in
order to facilitate power transfer at an appropriate range of
power. In response to the power demand information, the primary
circuit 103 selects an appropriate coil of the primary coil
assembly 101 over which to transfer power to the remote device 104.
In one embodiment, the coil is selected at least in part as a
function of the power class of the remote device. The ability to
select different ranges of power with a single inductive power
supply allows power transfer to devices with vastly different power
demands.
[0026] The invention is described in the context of a coil assembly
101 with three coils that provide three different ranges of power
that correspond respectively to three power classes. However, in
some embodiments, the coil assembly may include additional or fewer
coils, thereby respectively increasing or decreasing the number of
different ranges of power, and therefore number of power classes,
that may be provided. That is, in the described embodiments, there
is a one to one mapping between the number of ranges of power and
the number of power classes. However, that need not be the case. In
scenarios where there are more power classes than there are coils,
multiple power classes may be mapped to the same coil. And vice
versa when there are more coils than power classes. In some
embodiments, there may be some overlap between power classes or the
ranges of power provided b the different coils.
[0027] In some applications, devices may demand different amounts
of power at different times. An example of this is demonstrated
during a method of transferring power. The primary circuit 103 of
the inductive power supply 102 periodically transmits power using a
lower power coil. A remote device 104 that receives that power uses
it to transmit power demand information to the inductive power
supply 102. The inductive power supply uses the power demand
information to select the appropriate coil of the coil assembly 101
for power transfer, which may be a different coil than the one used
during the initialization procedure.
[0028] II. Inductive Power Supply System
[0029] One embodiment of an inductive power supply system in
accordance with the present invention is pictured in FIG. 5, and
generally designated 500. The inductive power supply system 500
depicts an inductive power supply 503 and a remote device 504.
Although depicted generically, the remote device 504 could be
essentially any type of device that is capable of communicating,
including allowing the inductive power supply to detect, power
demand information, such as the power class of the remote
device.
[0030] The inductive power supply 503 may be contained within a
housing 501, such as a dedicated housing having a surface 506 on
which to place the remote device 504. The size, shape and
configuration of the housing 501 and surface 506 may vary. Further,
the location of the primary coils 512, 514, 516 of the coil
assembly 502 may also vary with respect to the surface 506 and with
respect to each other. In the FIG. 5 embodiment, the coils 512,
514, 516 are arranged in a planar, concentric configuration under
surface 506.
[0031] In alternative embodiments, such as the embodiment
illustrated in FIG. 7, the coils 712, 714, 716 may be arranged in
vertical alignment and embedded within the side wall 702 of a
housing 701 that is shaped as a container with a surface 706 on
which to place the remote device 704. FIGS. 5 and 7 are merely
examples of how the housing, surface and coils may be arranged.
Many other configurations are possible.
[0032] Similarities between the remote device secondary coil and
the active primary coil promote efficient power transfer. For
example, the secondary coil 509 and low power coil 512 are similar
in size, shape, number of turns, length and gauge. These
similarities make better alignment possible, which facilitates
efficient power transfer. Similarly, medium and high power class
devices may have a secondary with characteristics similar to the
medium and high power coils respectively, which facilitates better
power transfer when energizing those coils.
[0033] The size of the remote device or secondary coil may help
align the remote device in the FIG. 7 embodiment as well. Although
not true in every case, low power class devices tend to be
physically smaller, while high power class devices tend to be
physically larger in comparison. This means that where the coils
are arranged vertically, as in the FIG. 7 embodiment, a smaller
device has a tendency to align better with the low power coil 712
while a larger device has a tendency to align better with the high
power coil 716.
[0034] Alignment of the remote device and active primary may be
further facilitated by magnetic positioning. In some applications,
the inductive power supply system 500 may incorporate a magnet 510
in the inductive power supply and a magnet 508 in the remote device
to provide magnetic positioning. The inductive power supply system
500 may incorporate essentially any of the features from U.S.
Provisional Patent Application 61/030,586 filed on Feb. 22, 2008
and titled "Magnetic Positioning for Inductive Coupling," which is
herein incorporated by reference. The magnet may be for use with
any combination of low, medium and high power class remote devices.
Magnetic positioning may be used in some, all or no remote devices.
The magnets are optional and need not be provided in the inductive
power supply or remote device.
[0035] In some applications, multiple devices may be powered
simultaneously by the inductive power supply, perhaps as best seen
in FIG. 14. One simple scenario is where a higher power coil is
used to power multiple lower power class devices. Because the
higher power coil exhibits a larger inductive field that covers
more area, there is more space for the devices to be positioned
within. That is, because power efficiency does not substantially
limit the amount of power a lower power device may receive during
charging from a higher power coil, the lower power devices gain
spatial freedom.
[0036] It should also be noted that more forgiving loads and
devices may use a coil with a power class higher than the remote
device power class in order to obtain benefits in spatial freedom.
The devices are powered using a higher power coil, but at lower
powers based on device classifications and other criteria. In the
illustrated embodiment, such benefits may be obtained by using the
medium power coil 514 or high power coil 516 with low power remote
devices. One example of a forgiving load is a remote control.
Typically, a forgiving load can be charged at different rates or
with different amounts of power without its performance being
substantially impaired.
[0037] Just as higher power coils can be used with lower power
devices in some situations, so can lower power coils be used with
higher power devices in some situations. Some higher power devices
may have standby options that consume less power. In one
embodiment, if a higher powered device indicates that it needs less
power, because, for example, it is entering stand-by mode, then the
lower power coil may be used to provide that power. Essentially,
although a device may have a general power class, there may be
situations where it is beneficial to provide more or less power,
and those situations may be accommodated using a coil assembly with
multiple coils. This also may result in energy savings.
[0038] III. Inductive Power Supply
[0039] The present invention is suitable for use with essentially
any inductive power supply that includes a primary circuit 103 that
has a primary coil assembly 101 with multiple coils. Accordingly,
the circuitry unrelated to the primary coil assembly 101 in an
inductive power supply 102 will not be described in detail. The
primary circuit 103 may include essentially any circuitry capable
of supplying alternating current at the desired frequency or
frequencies. For example, the power supply circuit 103 may include
the resonant seeking circuit of the inductive power supply system
disclosed in U.S. Pat. No. 6,825,620, which is entitled
"Inductively Coupled Ballast Circuit" and issued Nov. 30, 2004, to
Kuennen et al; the adaptive inductive power supply of U.S. Pat. No.
7,212,414, which is entitled "Adaptive Inductive Power Supply" and
issued May 1, 2007, to Baarman; the inductive power supply with
communication of U.S. Ser. No. 10/689,148, which is entitled
"Adaptive Inductive Power Supply with Communication" and filed on
Oct. 20, 2003 to Baarman; the inductive power supply for wirelessly
charging a LI-ION battery of U.S. Ser. No. 11/855,710, which is
entitled "System and Method for Charging a Battery" and filed on
Sep. 14, 2007 by Baarman; the inductive power supply with device
identification of U.S. Ser. No. 11/965,085, which is entitled
"Inductive Power Supply with Device Identification" and filed on
Dec. 27, 2007 by Baarman et al; or the inductive power supply with
duty cycle control of U.S. Ser. No. 61/019,411, which is entitled
"Inductive Power Supply with Duty Cycle Control" and filed on Jan.
7, 2008 by Baarman--all of which are incorporated herein by
reference in their entirety.
[0040] One embodiment of a primary circuit of an inductive power
supply 102 is illustrated in FIG. 2, and generally designated 200.
The primary circuit 200 of the illustrated embodiment generally
includes a primary controller 202, a driver circuit 204, a
switching circuit 206, a tank circuit 208, a wireless receiver 212
and a current sensor circuit 210.
[0041] Primary controller 202 controls the driver circuit 204,
switching circuit 206 and tank circuit 208. The primary controller
202 is capable of processing information, such as power demand
information, received from the remote device 104. The primary
controller 202 may include internal memory, access external memory
or a combination thereof. The power demand information may be used
to determine which coil of the primary coil assembly 222 should be
energized. In one embodiment, the power demand information provided
by the remote device identifies whether the device is a low power
class, medium power class or high power class. In an alternative
embodiment, the power demand information provided by the remote
device identifies an amount of power (or a power adjustment) the
remote device would like to receive and the controller 202
processes that information to determine which coil to energize. If
the power adjustment crosses a power class threshold, a different
coil will be energized. In yet another alternative embodiment, the
power demand information identifies the remote device and the
primary controller uses a look-up table to determine which coil to
energize.
[0042] In one embodiment, the power demand information includes
information regarding minimum, maximum, or both power levels for
specific coil selections. The thresholds used to determine which
coil to energize may vary as a function of the power demand
information. For example, for one remote device, the low power coil
threshold minimum and maximum may be one value, but for a different
remote device, the low power coil threshold minimum and maximum may
be different values. There may be situations where for one remote
device it is appropriate to use the low power coil to transmit a
certain amount of power and for another remote device it is
appropriate to use a medium power coil to transmit that same amount
of power. The power demand information stored in the remote device
may be based on capabilities and design expectations among other
things.
[0043] The primary controller 202 may be programmed with additional
features. For example, in one embodiment, the primary controller
202 is programmed to identify remote devices using the inventive
principles described in U.S. Ser. No. 11/965,085, which was
previously incorporated by reference. For example, the remote
device ID may include power demand information. Alternatively,
power demand information may be accessed using the remote device ID
as a key to a look up table on the inductive power supply 102.
[0044] Essentially any type of driver 204 and switching circuit 206
may be used. The switching circuit 206 in the current embodiment is
implemented as a pair of switches that form an inverter that
converts DC to AC.
[0045] The tank circuit 208 of FIG. 2 includes a coil selector
circuit 220 and a primary coil assembly 222 with multiple coils.
The coil selector circuit 220 is capable of energizing one or more
of the multiple coils of the coil assembly 222. FIG. 4 illustrates
selecting between multiple separate coils, FIG. 6 illustrates
selecting between multiple taps of a single coil, and FIG. 15
illustrates selecting between multiple segments of a single coil.
The illustrated embodiments are merely examples, any combinations
of separate coils, multiple taps, and multiple segments may be used
to provide a variety of different multiple coil configuration
options. In one embodiment, the controller 202 instructs the coil
selector circuit 220 on which coil to energize. In the illustrated
embodiment, the primary coil assembly 222 includes three coils: a
low power coil, a medium power coil and a high power coil. In
alternative embodiments, the primary coil assembly 222 includes
additional or fewer coils. In some applications, the coils of the
primary coil assembly 222 may be made of Litz wire. In other
embodiments, the coils may be any combination of copper, LITZ,
PLITZ, FLITZ, conductive ink or any other materials that have coil
properties. The characteristics of each of the coils may vary from
application to application and coil to coil. For example, the
number of turns, size, length, gauge, shape and configuration of
each coil may vary. In one embodiment, the low power coil has
approximately 10 strands of LITZ wire, the medium power coil has
approximately 50 strands of LITZ wire and the high power coil has
approximately 138 strands of LITZ wire. In one embodiment, the sole
difference between the low, medium, and high power coils are the
respective gauges of the coil. Although described in connection
with coils, the primary coil assembly 222 may alternatively be
essentially any structure capable of selectively generating
multiple ranges of power using electromagnetic fields. In one
embodiment, the primary coil assembly 222 may be implemented as
multiple printed circuit board coils, such as a printed circuit
board coil incorporating the inventive principles of U.S. Ser. No.
60/975,953, which is entitled "Printed Circuit Board Coil" and
filed on Sep. 28, 2007 by Baarman et al, and which is incorporated
herein by reference in its entirety.
[0046] The circuit diagram of FIG. 8 illustrates an exemplary
switching circuit 802 and tank circuit 804. The switching circuit
includes two field effect transistor switches 810, 812. However,
essentially any type of switches may be used. The switches 810, 812
convert DC power to AC power. The AC power is fed in parallel to
three switched LC circuits. In the current embodiment, each LC
circuit includes a variable capacitor 814, 816, 818 that sets the
starting resonance for each coil. In an alternative embodiment, the
variable capacitors 814, 816, 818 may be deleted or replaced with
non-variable capacitors. The variable capacitors 814, 816, 818 may
be controlled my controller 202 during operation or manually at the
time of manufacture. In the illustrated embodiment, the primary
coil assembly includes a low power coil, 832, a medium power coil
834 and a high power coil 836. However, as previously discussed,
different configurations and different numbers of coils may be
implemented. Switches 820, 822, 824, 826, 828, 830 control which
coil 832, 834, 836 receives power and therefore, which coil or
coils are energized. In the current embodiment, the controller 302
activates one pair of switches 820-822, 824-826, 828-830 at a time.
That is, the coils are activated in a mutually exclusive fashion.
However, in alternative embodiments, multiple coils may be
activated simultaneously depending on the application. Further, in
other alternative embodiments, additional switches could be placed
between each coil for a matrix selection. In another alternative
embodiment, switches 822,826, 830 are deleted or shorted in order
to reduce the number of switches in the circuit.
[0047] In the current embodiment, the wireless IR receiver 212 and
current sensor circuit 210 are both used for communication with
remote devices. The current sensor 210 may be used to sense
reflected impedance from the remote device, which effectively
allows communication over the inductive coupling. The wireless IR
receiver may be used to communicate with the wireless IR
transmitter 320 in the secondary circuit 300. In an alternative
embodiment, a peak detector may replace or be used in conjunction
with the communication system already in place. One or both of
wireless IR receiver 212 and current sensor circuit 210 may be
replaced with a different communication system for communicating
with one or more remote devices. For example, any of WIFI,
infrared, Bluetooth, cellular or RFID communication systems may be
implemented in the primary circuit 200. In one embodiment, the
current sensor circuit receives power demand information relating
to remote devices with lower power classes and the wireless IR
receiver receives power demand information relating to devices with
higher power classes. Communicating using the current sensor
circuit can be inefficient where a higher amount of power is being
transferred. By using a different communication system during
higher power transfer, losses can be decreased.
[0048] In operation, the primary controller 202, driver circuit 204
and switching circuit 206 apply alternating current to the tank
circuit 208 to generate a source of electromagnetic inductive power
at a selected power range and frequency.
[0049] One embodiment of a tank circuit 208 is illustrated in FIG.
4, and generally designated 400. The tank circuit 208 includes a
coil selector circuit 420 and a primary coil assembly 408. The
primary coil assembly 408 includes an optional positioning magnet
420, a low power coil 410, a medium power coil 412 and a high power
coil 414. In the current embodiment, some of the coils share
electrical connections to the coil selector circuit. Specifically,
the low power coil 410 shares a lead with the medium power coil
412. The medium power coil 412 shares a different lead with the
high power coil 414.
[0050] The physical characteristics effect the power that is
transferred when the coil is energized. Examples of such
characteristics include geometry, length, gauge, and number of
turns. Essentially any of the physical characteristic of the coils
414, 412, 410 may vary. In the illustrated embodiment, the low
power coil 512 has a relatively short length and gauge compared to
the medium power coil 514, which in turn has a shorter length and
gauge than the high power coil 514. Further, the coils depicted in
FIG. 4 are generally circular. However, the coils may be
implemented using other shapes, such as oval, rectangular, square,
to list a few. In one embodiment, multidimensional coils are
implemented.
[0051] Other factors can also effect the power transferred when the
coil is energized. For example, one factor is the spacing between
the coils 410, 412, 414. In the embodiment illustrated in FIG. 4
there are gaps 416, 418 between the coils 410, 412, 414 that can
potentially reduce cross-talk or other interference. In the current
embodiment, these gaps 416, 418 are filled with air and serve to
provide some isolation between the coils 410, 412, 414. In an
alternative embodiment, the gaps 416, 418 may be filled with a
shielding material to provide additional isolation. In another
alternative embodiment, the gaps 416, 418 may be filled with
ferrite in order to direct the magnetic fields produced by coils
410, 412, 414. In the embodiment illustrated in FIG. 6, the spacing
between the coils 610, 612, 614 is limited. There are no gaps
between the coils, which allows the coils to be more compact while
maintaining their size. In the FIG. 6 embodiment, the coils share
some leads to the coil selector circuit 620. In alternative
embodiments, each coil 610, 612, 614 may include two separate leads
to the coil selector circuit 620.
[0052] IV. Remote Device
[0053] One embodiment of a secondary circuit is shown in FIG. 3,
and generally designated 300. In the embodiment illustrated in FIG.
3, the secondary circuit 300 generally includes a secondary 302,
rectifier 304 (or other components for converting AC power to DC),
a secondary controller 316, memory 322, a wireless IR transmitter
320, a signal resistor 318, and a load 306. Other circuitry may be
included. For example, in one alternative embodiment a low voltage
power supply may be included to scale the received power. In
another alternative embodiment, conditioning circuitry may be
included to filter or otherwise condition the received power.
[0054] The secondary coil 302 of the illustrated embodiment is a
coil of wire suitable for generating electricity when in the
presence of a varying electromagnetic field. Perhaps as shown best
in FIG. 5, the secondary coil 509 may correspond in size and shape
to one of the primary coils 512, 514, 516. For example, the two
coils may have substantially equal diameters. In some applications,
the secondary coil 509 may be a coil of Litz wire. As with the
primary coils, the characteristics of the secondary coil 509 may
vary from application to application. For example, the number of
turns, size, shape, configuration or other characteristics of the
secondary coil 509 may vary. Further, the characteristics of the
wire may vary, such as length, gauge and type of wire. Although
described in connection with a coil of wire, the secondary coil 509
may alternatively be essentially any structure capable of
generating sufficient electrical power in response to the intended
electromagnetic field.
[0055] In some alternative embodiments the remote device may have
multiple secondary coils. For example, the remote device may have a
separate low power coil for low power applications and separate
medium and high power coils for medium and high power applications.
In another alternative embodiment, the remote device has multiple
secondary coils to give the remote device orientation and spatial
freedom.
[0056] In one embodiment, multiple secondary coils receiving power
of different phases can be used to reduce the ripple voltage. This
is referenced in Application 60/976,137, entitled "Multiphase
Inductive Power Supply System" filed Sep. 9, 2007 to Baarman et al,
which is herein incorporated by reference. Multiple coil assemblies
each with multiple coils may be desired to transmit power at
different phases in such an embodiment.
[0057] In operation, the rectifier 304 converts the AC power
generated in the secondary coil 302 to DC power. In some
applications the rectifier may be deleted. For example, if the load
306 accepts AC power.
[0058] The secondary controller 316 may be essentially any type of
microcontroller that is capable of operating the communication
system to communicate power demand information to the inductive
power supply. In some embodiments the secondary controller 316
includes memory. In the illustrated embodiment, the secondary
circuit includes external memory 322. The memory generally includes
power demand information and may include additional information
about the remote device. The power demand information may include a
power class that categorizes how much power the remote device
desires.
[0059] In one embodiment, there are three power classes: the low
power class, the medium power class and the high power class. The
low power class is defined as devices that desire between 0 and 5
watts of power. The medium power class is defined as devices that
desire between 5 and 110 watts of power. The high power class is
defined as devices that desire more than 110 watts of power.
Examples of devices categorized as low power class devices under
this power class scheme include cell phones, MP3 players and
personal digital assistants (PDA). Example of devices with a medium
power class include laptop computers and other medium power
applications. Examples of high power devices include kitchen
appliances, such as a blender or frying pan. In alternative
embodiments, with different power class schemes the definitions of
the power classes may vary.
[0060] In one embodiment, signal resistor 318 may be used to send
information to the primary controller 202. The use of a signal
resistor 318 to provide communication from the secondary circuit
103 to the primary circuit 105 was discussed in U.S. patent
application Ser. No. 11/855,710, which was previously incorporated
by reference. The signal resistor 318, when shunted, sends a
communication signal that signifies an over-current or over-voltage
state. When the resistor is shunted, the current or peak detector
on the primary circuit 103 is able to sense the
over-voltage/over-current condition and act accordingly. The signal
resistor 318 of the present invention may be shunted systematically
to communicate additional data to the primary controller 202. For
example, a stream of data could represent power demand information
or provide other information about the remote device.
Alternatively, the signal resistor 318 could be replaced with a
different communication system entirely. For example, wireless
transmitter 320 may be used in conjunction with or in lieu of
signal resistor 318 to wirelessly communicate with the wireless
receiver 212 of the primary circuit 200. In an alternative
embodiment, one or both of wireless IR transmitter 320 and signal
resistor 318 may be replaced with a different communication system
for communicating with the inductive power supply. For example, any
of WIFI, infrared, Bluetooth, cellular or RFID communication
systems may be implemented in the remote device 104.
[0061] Use of a wireless transmitter or transceiver was previously
described in U.S. Patent Application Publication US 2004/130915A1
to Baarman, which was previously incorporated by reference.
Specifically, the use of WIFI, infrared, Bluetooth, cellular or
RFID were previously discussed as ways to wirelessly communicate
data between a remote device to an inductive power supply. Further,
communication using the induction coils and a power line
communication protocol was discussed. Any of these methods of
transmitting data could be implemented in the present invention in
order to transfer the desired data from the remote device to the
inductive power supply.
[0062] The remote device load 306 may essentially any suitable
load. In some embodiments, the load 306 may be a rechargeable
battery and the secondary circuit may include additional charging
circuitry. In other embodiments the load 306 may relate to the
function of the remote device.
[0063] V. Method
[0064] A method for authentication and power transfer control is
illustrated in the flowchart of FIG. 9, and generally designated
900. The method includes periodically transmitting ping messages
902, authenticating any messages received in response 904, in
response to an authentic message, determining the control
identification class (CIDC) and primary power class (PPC) and
initiating power transfer based on the determined CIDC and PPC 906.
During active power transfer mode 908, the presence of the device
and the status of the control point is continually checked 910 in a
feedback loop with control feedback packets from the remote device
912.
[0065] In one embodiment, the inductive power supply is in one of
several modes: pinging or active power transfer. The ping mode
actively determines if a qualified device is present. Power
transfer only takes place when a device identification class is
recognized and validated.
[0066] A safe ping frequency may be determined using the
characteristics of the hardware in the inductive power supply
system. The primary attempts communication with a secondary by
energizing the low power (or other) coil at a specified ping
frequency and waits for a response. If a secondary is present
within the charging zone, it may be powered sufficiently by the
energy sent during the ping operation to initialize itself and send
an identification message that may contain power demand information
to the inductive power supply.
[0067] If the primary fails to detect a device in the charging
field during the ping operation, the coil power is removed until
the next attempt for detection. If a device is detected during the
ping operation, the primary reverts to the established initial
operating frequency in an attempt to begin power transfer. The
power delivered to the secondary during transfer may be controlled
based upon communications received from the secondary.
[0068] The control identification classes may identify different
control methods for the inductive power supply to use to charge or
power the remote device. Examples of control identification classes
include charging set point control, charging error control, power
supply set point control, power supply error control and power
supply direct control.
[0069] The primary power class determines the range of power of a
specific coil of the inductive power supply. The primary power
class also may impact the coil geometry and parametric
specifications. In an alternative embodiment, the primary power
class includes information about the entire range of power provided
by the inductive power supply. The remote device may include a
remote device power class in the power demand information
transmitted to the inductive power supply. The remote device power
class and the primary power class may be one in the same, or they
may be different.
[0070] In one embodiment, the power class is a portion of the
information communicated from the remote device to inductive power
supply. In one embodiment information may be provided to the
primary circuit about the maximum amount of power the remote device
can be expected to require. For example, a cell phone may fall
under a 3.5 W maximum power level. Its power class byte would be
0000 0111b.
[0071] The following chart describes how a power class byte may be
constructed. The power class may be encoded in essentially any
manner, this chart merely represents one possible embodiment.
TABLE-US-00001 TABLE 1 Power Class Power Class Power Levels Bits
[7:6] Multiplier Bits [5:0] (W) 00 1 00000-11111 0-32 W, 0.5 W
Increments 01 10 00000-11111 0-320 W, 5 W Increments 10 100
00000-11111 0-3200 W, 50. W Increments 11 1000 00000-11111 0-32000
W, 500 W Increments
[0072] FIG. 10 illustrates a functional block diagram for providing
power in accordance with one embodiment of the present invention.
FIG. 11 illustrates a functional block diagram for receiving power
in accordance with one embodiment of the present invention. FIG. 12
illustrates a functional block diagram for providing power in
accordance with another embodiment of the present invention. FIG.
13 illustrates a functional block diagram for receiving power in
accordance with one embodiment of the present invention.
[0073] The functional block diagrams of FIGS. 10 and 11 are
directed to inductively charging a load in a remote device. The
functional block diagrams of FIGS. 12 and 13 are directed to
inductively charging a rechargeable battery in a remote device.
[0074] In FIG. 10 and FIG. 12, each of the coils may represent a
primary coil assembly with multiple coils as described above.
Alternatively, each of the coils may represent one coil of a
primary coil assembly.
[0075] Above, several embodiments of multiple coil inductive power
supplies have been described. Specifically, examples have been
provided of multiple coil inductive power supplies that use
multiple coils configured in a multi-tap configuration and multiple
coil inductive power supplies that use a separate coil
configuration. Other configurations that provide variable
inductance may also be provided. For example, a segmented primary,
such as the Litz wire coil shown in FIG. 15, may provide multiple
strands that can be connected and energized in various
configurations to provide a variable amount of inductance. The
various configurations of the segmented primary allow the inductive
power supply to better match secondary power and coupling
requirements from high power to low power levels using the same
primary. In the current embodiment, the combination of taps and
segment configurations provides a wide range of inductance values
and wire gauges. In some embodiments, some of the segments may be
disconnected, allowing an even wider range.
[0076] Depending on how the strands are connected, different
configurations may be created. The table below describes a number
of examples of various coil selection circuit segment options.
TABLE-US-00002 TABLE 2 nitial Realized Realized Turns Segments Awg.
Configuration Turns 0 4 X 4- 10 Parallel 0 4 X/2 2- 20 Parallel
& 2- Series 0 4 X/4 4- 40 Series
[0077] FIG. 15 shows a cross section of litz wire that has been
segmented into four sections. In the illustrated embodiment, each
section may be energized individually. In an alternative
embodiment, the sections may be divided differently, or each strand
may be energized separately. Further, in the current embodiment,
the coil selector circuit connects to each segment separately at
each tap so that the segments can be arranged in parallel or series
depending on how the coil selector circuit connects the various
segments together.
[0078] Although FIG. 15 illustrates three coils 610, 612, 614 of
varying gauges. In an alternative embodiment, each coil may be the
same gauge, and the gauge may be controlled by the coil selector
circuit choosing which segments or individual strands to
energize.
[0079] As described above in connection with the other inductive
power supply embodiments, the coil selector circuit may be
controlled according to a program residing in memory in the
controller 202. The coil selector circuit may change the
configuration of the segmented primary during operation to adjust
based on power demand information provided from the remote device.
The ability to dynamically change the gauge of the wire, and other
characteristics, is useful to better match the secondary power and
coupling requirements.
[0080] The above description is that of the current embodiment of
the invention. Various alterations and changes can be made without
departing from the spirit and broader aspects of the invention.
* * * * *