U.S. patent application number 15/644882 was filed with the patent office on 2018-05-24 for method and apparatus for controlling heat in power conversion systems.
This patent application is currently assigned to FINsix Corporation. The applicant listed for this patent is FINsix Corporation. Invention is credited to Vanessa Green, Anthony Sagneri.
Application Number | 20180146571 15/644882 |
Document ID | / |
Family ID | 50625155 |
Filed Date | 2018-05-24 |
United States Patent
Application |
20180146571 |
Kind Code |
A1 |
Sagneri; Anthony ; et
al. |
May 24, 2018 |
METHOD AND APPARATUS FOR CONTROLLING HEAT IN POWER CONVERSION
SYSTEMS
Abstract
A power conversion module, such as a power adapter, includes a
heat removal system such as an active heat removal system, a
passive heat removal system or a hybrid heat removal system. A
small-size power conversion module having a heat removal system is
described.
Inventors: |
Sagneri; Anthony; (Palo
Alto, CA) ; Green; Vanessa; (San Francisco,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FINsix Corporation |
Menlo Park |
CA |
US |
|
|
Assignee: |
FINsix Corporation
Menlo Park
CA
|
Family ID: |
50625155 |
Appl. No.: |
15/644882 |
Filed: |
July 10, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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14210859 |
Mar 14, 2014 |
9861015 |
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15644882 |
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61794633 |
Mar 15, 2013 |
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61862390 |
Aug 5, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H05K 7/20918 20130101;
H05K 7/209 20130101; G06F 1/26 20130101; H01L 23/4275 20130101;
H05K 7/2039 20130101 |
International
Class: |
H05K 7/20 20060101
H05K007/20 |
Claims
1. A power adapter, comprising: a housing; an AC/DC converter in
the housing, the AC/DC converter being configured to convert an AC
input signal into a DC output signal; and at least one compartment
in the housing, the at least one compartment comprising a phase
change material having a transition temperature between 25.degree.
C. and 85.degree. C.
2. The power adapter of claim 1, wherein the phase change material
has a transition temperature between 30.degree. C. and 50.degree.
C.
3. The power adapter of claim 1, further comprising: a second
material having a thermal conductivity higher than that of the
phase change material, the second material being between first and
second regions of the phase change material.
4. The power adapter of claim 3, wherein the second material
comprises a metal.
5. The power adapter of claim 1, wherein the power adapter has a
volume no greater than 3 cubic inches.
6. The power adapter of claim 5, wherein the phase change material
is of a volume and configuration such that a temperature of an
exterior surface of the housing remains below a temperature of
40.degree. C. when the power adapter delivers an average power of
at least 45 W for a period of 30 minutes.
7. The power adapter of claim 6, wherein the phase change material
is of a volume and configuration such that a temperature of the
exterior surface of the housing remains below a temperature of
40.degree. C. when the power adapter delivers an average power of
at least 45 W for a period of 2 hours.
8. A power adapter, comprising: a housing; an AC/DC converter in
the housing, the AC/DC converter being configured to convert an AC
input signal into a DC output signal; and a heat removal system
comprising an opening in the housing and/or a heat absorbing
material; wherein the power adapter has a volume no greater than 4
cubic inches, wherein the power adapter is configured to deliver an
output power of at least 40 watts.
9. The power adapter of claim 8, wherein the heat removal system
comprises a heat absorbing material and the heat absorbing material
comprises a phase change material having a transition temperature
such that the phase change material changes phase during operation
of the power adapter.
10. The power adapter of claim 9, wherein the transition
temperature is between 25.degree. C. and 85.degree. C.
11. The power adapter of claim 8, wherein the housing comprises an
outer enclosure and an inner enclosure, wherein a plenum separates
the outer enclosure from the inner enclosure, the outer enclosure
having the opening to allow airflow between the plenum and an
exterior of the power adapter.
12. The power adapter of claim 8, further comprising an actuated
heat removal device within the housing.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 14/210,859, titled "METHOD AND APPARATUS FOR CONTROLLING HEAT
IN POWER CONVERSION SYSTEMS," filed Mar. 14, 2014, which claims
priority under 35 U.S.C. 119(e) to U.S. provisional application
Ser. Nos. 61/794,633, titled "METHOD AND APPARATUS FOR CONTROLLING
HEAT IN POWER CONVERSION SYSTEMS," filed Mar. 15, 2013, and
61/862,390, titled "METHOD AND APPARATUS FOR CONTROLLING HEAT IN
POWER CONVERSION SYSTEMS," filed Aug. 5, 2013, each of which is
hereby incorporated by reference in its entirety.
DISCUSSION OF RELATED ART
[0002] Power adapters are widely used for powering and charging
electronics, including consumer electronic devices such as cellular
telephones and laptop computers, by way of example. A standard
AC/DC power adapter converts the AC line voltage provided by a
standard electrical outlet into a DC voltage accepted by an
electronic device. A typical AC/DC power adapter for a laptop
computer has a brick-shaped power conversion module with the
necessary electronics for performing AC/DC power conversion. The
power conversion module is attached to one cord with a plug that
can be plugged into a standard electrical outlet and another cord
with a connector that can be plugged into a laptop computer to
power the laptop computer and/or charge its battery. A power
adapter can provide voltage regulation, electrical isolation and
protection from line surges.
[0003] Power adapters for consumer electronic devices tend to be
large and heavy. In particular, power adapters for portable
electronic devices that draw a larger amount of power (e.g.,
greater than 40 W), such as laptop computers, for example, are
relatively large and heavy. Some power adapters for laptop
computers can be more than 20% of the weight of the laptop computer
itself. For a mobile device, such as a laptop computer, having a
large and heavy power adapter can be particularly cumbersome, as
the user may need to carry around such an adapter when the user
expects to be away from a power outlet for any significant period
of time.
SUMMARY
[0004] Some embodiments relate to a power adapter. The power
adapter includes a housing comprising an outer enclosure and an
inner enclosure. A plenum separates the outer enclosure from the
inner enclosure. The outer enclosure has at least one opening to
allow airflow between the plenum and an exterior of the power
adapter. The power adapter also includes AC/DC converter within the
inner enclosure. The AC/DC converter is configured to convert an AC
input signal into a DC output signal.
[0005] Some embodiments relate to a power module. The power module
includes a housing comprising an outer enclosure and an inner
enclosure. A plenum separates the outer enclosure from the inner
enclosure. The outer enclosure has at least one opening to allow
airflow between the plenum and an exterior of the power adapter.
The power module also includes an AC/DC converter within the inner
enclosure. The AC/DC converter is configured to convert an AC input
signal into a DC output signal.
[0006] Some embodiments relate to a power adapter. The power
adapter includes a housing and an AC/DC converter in the housing.
The AC/DC converter is configured to convert an AC input signal
into a DC output signal. The power adapter also includes at least
one compartment in the housing. The at least one compartment
includes a phase change material having a transition temperature
between 25.degree. C. and 85.degree. C.
[0007] Some embodiments relate to a power adapter. The power
adapter includes a housing and an AC/DC converter in the housing.
The AC/DC converter is configured to convert an AC input signal
into a DC output signal. The power adapter also includes a heat
removal system comprising an opening in the housing and/or a heat
absorbing material. The power adapter has a volume no greater than
4 cubic inches. The power adapter is configured to deliver an
output power of at least 40 watts.
[0008] Some embodiments relate to power adapter. The power adapter
includes a housing and an AC/DC converter within the housing. The
AC/DC converter is configured to convert an AC input signal into a
DC output signal. The power adapter also includes an actuated heat
removal device. The actuated heat removal device is configured to
remove heat produced by the AC/DC converter from the housing. The
volume of the power adapter is no more than 3 cubic inches. The
power adapter is configured to deliver an output power of at least
30 watts.
[0009] Some embodiments relate to power adapter. The power adapter
includes a housing and an AC/DC converter within the housing. The
AC/DC converter is configured to convert an AC input signal into a
DC output signal. The power adapter also includes a sensor
configured to detect proximity or touch of a human and an indicator
device configured to produce an audible or visual output. The power
adapter also includes a controller configured to control the at
least one indicator device to produce the audible or visual output
in response to the sensor detecting proximity or touch of a
human.
[0010] Some embodiments relate to a power module. The power module
includes a housing and an AC/DC converter within the housing. The
AC/DC converter is configured to convert an AC input signal into a
DC output signal. The volume of the power module is no more than 3
cubic inches. The power module is configured to deliver an output
power of at least 30 watts.
[0011] Some embodiments relate to method. The method includes
converting an AC input signal into a DC output signal using an
AC/DC converter. The method also includes cooling the AC/DC
converter by driving air through an enclosure for a power
conversion module comprising the AC/DC converter. The volume of the
power conversion module is no more than 3 cubic inches. The method
also includes delivering, by the power conversion module, an output
power of at least 30 watts. The foregoing summary is provided by
way of illustration, and is not intended to be limiting.
BRIEF DESCRIPTION OF DRAWINGS
[0012] In the drawings, each identical or nearly identical
component that is illustrated in various figures is represented by
a like reference character. For purposes of clarity, not every
component may be labeled in every drawing. The drawings are not
necessarily drawn to scale, with emphasis instead being placed on
illustrating various aspects of the techniques described
herein.
[0013] FIG. 1 shows a power adapter having an active heat removal
system, according to some embodiments.
[0014] FIG. 2 shows a cross-sectional view of the power adapter of
FIG. 1.
[0015] FIG. 3 shows a cutaway side view of the power adapter of
FIG. 1.
[0016] FIG. 4A shows a cross-sectional view of a power adapter of
FIG. 4B having a passive heat removal system with a plurality of
enclosures.
[0017] FIG. 4B shows a perspective view of a power adapter having a
passive heat removal system with a plurality of enclosures.
[0018] FIG. 5A shows a cross-sectional view of a power adapter of
FIG. 5B having a passive heat removal system with thermally
insulating caps.
[0019] FIG. 5B shows a side view of a power adapter having a
passive heat removal system with thermally insulating caps.
[0020] FIG. 6A shows a cutaway side view of a power adapter having
a passive heat removal system with regions of high thermal
mass.
[0021] FIG. 6B shows a cross-sectional view of the power adapter of
FIG. 6A along the line B-B'.
[0022] FIG. 6C shows a cross-sectional view of the power adapter of
FIG. 6A along the line C-C'.
[0023] FIG. 7A shows a cutaway side view of a power adapter having
a passive heat removal system with regions of high thermal
conductivity and regions of high thermal mass.
[0024] FIG. 7B shows a cross-sectional view of the power adapter of
FIG. 7A.
[0025] FIG. 8 shows a block diagram illustrating power and control
circuitry 206, as well as optional sensors and an indicator
device.
[0026] FIG. 9 shows a power adapter having a plurality of DC output
connection ports.
DETAILED DESCRIPTION
[0027] Some embodiments relate to power conversion modules, such as
power adapters, having AC/DC converters that are designed to
convert a standard AC mains voltage into a DC voltage to provide
power to an electronic device.
[0028] As mentioned above, power adapters for portable electronic
devices that consume a substantial amount of power (e.g., greater
than 40 W), such as laptop computers, for example, tend to be large
and bulky. The present inventors have appreciated that there are
two key limitations, either of which may prevent reducing the size
of such a power adapter.
[0029] One limitation is the minimum size of the passive components
(e.g., inductors and capacitors) used for power conversion. If the
power conversion electronics utilizes a switched mode power
converter that switches at typical power converter switching
frequencies, the passive components needed for such a power
converter may need to be prohibitively large to provide a
sufficient amount of amount of energy storage during the switching
intervals. When such a limitation applies, the size of the power
adapter cannot be reduced, as the ability to reduce the size of the
power adapter is limited by the size of the passive components.
[0030] Using a high frequency switching power converter can allow
reducing the size of the passive components, thereby allowing the
size of the power adapter to be reduced.
[0031] However, when a high frequency switching power converter is
used, the ability to reduce the size of the power adapter is no
longer limited by the size of the passive components, but by the
capability of removing heat from the power adapter. Power
conversion circuitry, no matter how well designed to maximize
efficiency, is less than 100% efficient, and the power that is lost
is converted into heat. The smaller a power adapter is made, the
more challenging it becomes to remove the heat that is produced by
its power conversion electronics. Failing to remove the heat
adequately can cause a rise in temperature that may reduce
component lifetimes and/or cause the temperature of the power
adapter to exceed acceptable standards for consumer electronic
devices. For example, a power adapter with a plastic housing
designed for consumer electronics applications may be required to
maintain an outside surface temperature of less than 85 .degree. C.
to meet IEC and UL standards. Standard power adapters are not
designed to remove a significant amount of heat produced in a small
volume.
[0032] In accordance with some embodiments, techniques are
described herein that enable forming power adapters of relatively
small size that are capable of providing a significant amount of
power to one or more electronic devices. The techniques described
herein enable reliably removing heat from a power converter of
small size. Heat removal systems are described including active
heat removal systems, passive heat removal systems and hybrid heat
removal systems.
[0033] In some embodiments, a power adapter includes an actuated
heat removal device, such as a fan, for example, that removes heat
produced by the power adapter to enable keeping the temperature of
the power adapter within an acceptable operating range. In some
embodiments, one or more openings are provided in the housing of
the power adapter to enable the ingress of cooler air from outside
the housing and the egress of heated air. Such opening(s) may be
provided on more than one side of the housing to provide redundancy
in case opening(s) on one or more sides of the power adapter are
blocked.
[0034] FIG. 1 shows a perspective view of an example of a power
adapter 1, according to some embodiments. Power adapter 1 includes
a housing 100 which may be formed of plastic or any other suitable
material. As shown in FIG. 1, the housing 100 may have
substantially a rectangular cuboid shape with a rectangular (e.g.,
square) cross-section. In some embodiments, the edges of the
housing may be rounded or chamfered. However, the techniques
described herein are not limited a rectangular cuboid shape, as
housing 100 may have any suitable shape, such as a round shape.
Alternatively, in some embodiments, the housing may be
substantially flat (e.g., less than a half inch or a quarter inch
in height along the vertical direction of FIG. 1).
[0035] A plug 102 is provided at one end of the power adapter 1. In
the embodiment of FIG. 1, plug 102 is attached to an end cap 110
which may be affixed to the housing 100. Plug 102 may be shaped to
plug into a standard electrical outlet. For example, plug 102 may
be shaped to plug into a standard U.S. electrical outlet that
provides an AC voltage of about 120V RMS. However, the techniques
described herein are not limited in this respect, as power adapter
1 may be provided with a plug shaped to plug into any suitable
electrical outlet. Further, the techniques described herein are not
limited as to a plug 102 being disposed on the end of the power
adapter 1, as in some embodiments a cord may be provided that is
attached to the end of power adapter 1, and the cord may include a
suitable plug.
[0036] The power adapter 1 may be connected to a cord 104 to enable
connecting the power adapter to an electronic device using
connector 106. Connector 106 may have any of a variety of shapes
suitable for connecting to a DC power input of a consumer
electronic device.
[0037] FIG. 1 shows that the housing 100 may include one or more
openings 108, 112 for allowing airflow into and/or out of the
housing 100. In some embodiments, the power adapter may include an
actuated heat removal device 202 (see, e.g., FIG. 3). The actuated
heat removal device 202 may be a fan, for example, or another
device capable of forcing airflow through the housing 100. If
actuated heat removal device 202 includes a fan, any suitable type
of fan may be used, such as a piezoelectric fan or an electrostatic
fan, for example. In some embodiments, the fan is configured to
draw cold air directly over the fan motor, thereby extending the
fan's lifespan. Another suitable type of actuated heat removal
device used in some embodiments is an electromechanical air pump
(e.g., a bellows). An electromechanical air pump may drive puffs of
air into and out of the housing. In some embodiments, if an
electromechanical air pump is used, a portion of the housing may be
operable as an actuatable member to drive the movement of air
within the housing. The actuatable member may be a flexible
membrane, in some embodiments. The actuatable member may be
positioned in any location forming a contiguous space with the
plenum.
[0038] In some embodiments, an actuated heat removal device may
drive the flow of air toward or away from the power conversion
circuitry of the power adapter 1. As mentioned above, FIG. 1 shows
that one or more openings 112 and 108 may be provided on the
housing 100 for enabling the flow of air into or out of the
housing. In some embodiments, openings 112 may act as inlets to
enable the flow of air into the housing 100 and openings 108 may
act as outlets to enable the flow of air out of the housing 100. In
some embodiments, one or more openings may be provided on each side
of the housing 100 disposed along the longitudinal axis of the
power adapter 1. In the embodiment of FIG. 1, the housing has four
sides disposed along the longitudinal axis of the power adapter,
each of which includes an opening 112 (e.g., an inlet) and an
opening 108 (e.g., an outlet). FIG. 2 shows a cross section of the
power adapter of FIG. 1 along the dashed lines A-A'. As shown in
FIG. 2, the power adapter may have four sides along the cross
section defined by the dashed lines A-A'.
[0039] The inventors have appreciated that one or more sides of the
power adapter may rest against one or more object(s) that may
obstruct the flow of air through the openings 108 and/or 112, such
as a floor, a wall, furniture, a blanket, etc. Accordingly, it may
be desirable to provide openings to enable the flow of air through
the housing on more than one side of the power adapter in case the
flow of air through is obstructed by an object on one or more sides
of the power adapter. By providing openings on more than one side
of the power adapter, if a first side of the power adapter rests
against an air-blocking object, airflow through the housing 100 may
be provided through opening(s) on another side of the power
adapter. In the embodiments of FIGS. 1-3, openings are provided on
four sides of the power adapter, so that even if airflow on three
sides of the power adapter is blocked, cooling may be provided by
airflow through one or more openings on a fourth side of the power
adapter. However the techniques described herein are not limited in
this respect, as some embodiments are not limited as to the number
of sides of the power adapter on which openings are disposed.
[0040] In some embodiments, if airflow through all of the openings
in housing 100 is blocked, a controller of the power adapter may
control the amount of power delivered by the power adapter to be
reduced. The power adapter may include a temperature sensor to
sense the internal temperature of the power adapter at the power
conversion electronics or another location. When the temperature
sensed by the temperature sensor exceeds a threshold, the
controller may control the power conversion electronics such that
the amount of power delivered at the output is reduced, or the
delivery of power is ceased. When the power adapter cools and the
temperature of the power adapter reaches a suitable operating
point, the controller may control the power conversion electronics
such that power delivery is be resumed and/or increased.
[0041] FIG. 3 shows a cutaway side view illustrating the interior
of the power adapter 1. As shown in FIG. 3, the power adapter 1
includes power and control circuitry 206 which includes power
electronics and control circuitry for converting the AC input
signal (e.g., received at plug 102) into a DC output signal (e.g.,
provided via cord 104 to an external electronic device).
[0042] In some embodiments, power and control circuitry 206 may be
disposed on a heat sink 204. The heat sink 204 may have protrusions
205 that provide a high surface area, enabling the heat produced by
power and control circuitry 206 to be dissipated in a plenum within
the housing. Protrusions 205 may also produce turbulent airflow
within the cavity, thereby facilitating the expulsion of heat from
the surface of the heat sink 204. The protrusions 205 of heat sink
204 are also illustrated in FIG. 2.
[0043] As discussed above, the actuated heat removal device 202 may
be a fan that blows air toward or away from the heat sink 204. In
one embodiment, illustrated in FIG. 3, the actuated heat removal
device 202 is configured to force air from one or more inlet
openings 112 (shown in dashed lines) toward the heat sink 204 and
out through one or more outlet openings 108 (also shown in dashed
lines). However, the techniques described herein are not limited in
this respect, as in some embodiments the actuated heat removal
device 202 may be configured to drive airflow in the opposite
direction.
[0044] In some embodiments, power and control circuitry 206 may be
enclosed in an airtight enclosure (and optionally potted). Sealing
the power and control circuitry 206 in an airtight enclosure can
isolate power and control circuitry 206 from the plenum through
which air passes, which can protect the power and control circuitry
206 from foreign substances such as liquid spills, dirt, dust, etc.
In the event of failure of a component within the power and control
circuitry 206, the use of an airtight enclosure to seal the power
and control circuitry 206 can prevent the release of odorous
gasses, which can facilitate compliance with FAA regulations, for
example.
[0045] The actuated heat removal device may be controlled by power
and control circuitry 206 through a suitable control connection
(not shown) within the housing 100. Similarly, conductors (not
shown) may be provided within the housing 100 to provide a
connection between the plug 102 and the power and control circuitry
206.
[0046] Described above is an embodiment in which one or more
openings in the housing 100 are provided on the sides of the power
adapter 1. However, the techniques described herein are not limited
to providing openings in the housing 100 on the sides of the power
adapter 1, as in some embodiments one or more openings may be
provided at the end(s) of the adapter. For example, if a plug 102
is included, an opening may be provided between the prongs of the
plug to allow air to flow into and/or out of the power adapter 1.
In some embodiments, one or more spacers may be included on the end
cap 110 to ensure separation between the end cap 110 and the
electrical socket, thereby creating a plenum.
[0047] In some embodiments, a passive heat removal system may be
provided for reliability, cost, and noise considerations. A passive
heat removal system may remove heat without the use of an actuated
heat removal device.
[0048] Existing power adapters have a minimum external surface area
set by the power dissipated in the adapter under peak load. The
power dissipated Pdiss corresponds to the difference in adapter
input power and output power as determined by the adapter
efficiency, .eta., and is equal to: Pdiss=((1-.eta.)/.eta.)*Pout.
The magnitude of Pdiss determines the total heat flux to be carried
to the adapter's surface to ensure the internal components do not
overheat. In turn, the surface area over which the heat flux
spreads (the surface area of the adapter system) affects the
temperature of the external surface of the housing. When the
surface of the housing is directly accessible (e.g., can be
contacted by a person or other object), it may be maintained below
a safety temperature. For plastic cases the safety temperature may
be 85.degree. C.; for metal cases it may be 75.degree. C. In
addition to surface area, other factors affect the skin temperature
including its emissivity, shape factor, orientation, surrounding
ambient, and in the case of an adapter which may be used in a
variety of environments, whether it is in contact with another
surface (such as a rug, a tabletop, or a sofa cushion). The
operating temperature of external surfaces may be kept below the
safety temperature, and it may be desirable to keep the temperature
of the external surface of the housing even lower, such as lower
than 50.degree. C. or lower than 60.degree. C., so that users do
not find the device uncomfortable to touch or perceive a
malfunction.
[0049] The result of the relationship between power dissipated,
surface area, skin temperature and certain dimension limits on
conventional power electronic components present in a power adapter
(such as the main power converter) is to set a minimum volume
(e.g., a bounding-box) of the power adapter for a given power
adapter efficiency. A power adapter may not be made smaller than
the bounding box volume without exceeding the desired external
surface temperature. The general industry understanding is that in
order for present, passively cooled adapters to be smaller, they
need to be made more efficient.
[0050] Dramatically reducing the size of the power electronics with
respect to power electronics of standard power adapters introduces
an additional degree of freedom to the design space. In some
embodiments, power electronics having a relatively high switching
frequency of 1 MHz or greater may enable reducing the size of the
power electronics by as much as a factor of ten, or even greater.
In some embodiments, the power electronics may have a switching
frequency in the VHF range (30 MHz to 300 MHz), and may utilize
resonant switching techniques and/or soft switching techniques to
maximize efficiency. An example of suitable power conversion
circuitry is described in PCT application WO 2012/024542
(PCT/US2011/048326), which is hereby incorporated by reference in
its entirety. Since the size of the power electronics may be
reduced dramatically, additional options are made possible for
passive heat removal, even at comparable efficiencies to present
levels.
[0051] As discussed above, the heat generated by the power
electronics may need to be dissipated through the bounding surface
of the power adapter housing. If efficiency is not increased, the
same heat flux may need to be expelled to maintain the internal
adapter components at a temperature within their operating limits,
and to maintain the outer surface within an acceptable temperature
range. In contrast to conventional power adapters, in which nearly
all of the space within the power adapter housing may be taken up
by the power electronics, power electronics that switches at a high
switching frequency may be made much smaller, and may consume a
smaller fraction of the volume of the power adapter housing.
[0052] In some embodiments, a power adapter housing may have an
inner enclosure and an outer enclosure. The inner enclosure
enclosing the power electronics may have a higher temperature than
that of the outer enclosure. The outer enclosure may have an outer
surface that does not exceed a temperature range (e.g., below a
safety temperature and/or within a range that is comfortable to the
touch). The higher-temperature internal enclosure facilitates the
removal of heat from the adapter electronics by convection.
[0053] Convection is enabled by means of a plenum between inner
enclosure and the outer enclosure. The internal enclosure of higher
temperature helps to drive stronger convection currents and allow
effective heat removal with a smaller total surface area. The
external lower-temperature enclosure carries away some heat, but
maintains a temperature that may not exceed a temperature range
(e.g., below a safety temperature and/or within a range that is
comfortable to the touch).
[0054] FIG. 4A shows a cross section of a power adapter 601 having
an inner enclosure 604 and an outer enclosure 602 separated by a
plenum 603, according to some embodiments. FIG. 4B shows a
perspective view of the power adapter 601 with inner enclosure 604
shown in dashed lines. As shown in FIG. 4A, power and control
circuitry 206 may be enclosed within (e.g., sealed within) inner
enclosure 604.
[0055] Inner enclosure 604 may have protrusions 606 extending
therefrom to increase the surface area of inner enclosure 604 in
the plenum 603 and improve convection. Protrusions 606 may include
fins, heat pipes, or a combination of fins and heat pipes, or other
structures. The air volume between the inner enclosure 604 and the
outer enclosure 602 forms the plenum 603 where heat is transferred
to convectively-driven air currents that may flow through openings
605 in the outer enclosure 602. Openings 605 may have any suitable
shape. The total volume of the power adapter can be made smaller
than existing adapters of the same efficiency and power level at
least in part because of the increased temperature of the inner
enclosure 604 and the smaller power electronics. The peak
temperature of the inner enclosure 604 can be limited by the total
volume allocated for the plenum 603, the shape and surface area of
the protrusions 606, the emissivity of the outer surface of inner
enclosure 604, and other factors.
[0056] In some embodiments, inner enclosure 604 may have a higher
thermal conductivity than outer enclosure 602. The inner enclosure
604 and/or protrusions 606 may be formed of a material with a high
thermal conductivity, such as a metal, for example, or any other
suitable material. The outer enclosure 602 may be formed of a
material with a lower thermal conductivity suitable for a user to
touch, such as plastic, for example. The outer enclosure 602 may be
formed of a thermally insulating material in order to keep the
external touch temperature at an acceptably low level. If so, the
convection currents driven through the plenum 603 by the heating of
the inner enclosure 604 may carry more of the heat flux from the
inner enclosure 604 to the exterior of the power adapter.
[0057] The inner enclosure 604 may be sealed, and may protect the
adapter electronics from contaminants such as liquids and dirt. If
inner enclosure 604 is formed of an electrically conductive
material, such as metal, for example, inner enclosure 604 may form
a galvanic barrier that prevents electric shock, should the user
insert a conductive object into a hole in the outer skin. If inner
enclosure 604 is formed of an electrically conductive material, the
inner enclosure 604 may provide an effective electromagnetic
interference (EMI) barrier.
[0058] The inner enclosure 604 may be designed such that convection
currents can be supported regardless of the adapter orientation
relative to the earth's surface. For instance, a structure having
symmetry around the theta and phi axes of a spherical coordinate
system can have such a behavior.
[0059] The outer enclosure 602 may have a unitary construction, as
illustrated in FIGS. 4A and 4B. However, the techniques described
herein are not limited in this respect, as outer enclosure 602 may
have a non-unitary construction with a plurality of components
forming the outer enclosure 602 in a way that can prevent the user
from coming in contact with the higher temperature inner enclosure
604.
[0060] For example, as shown in the cross-sectional view of FIG. 5A
and side view of FIG. 5B, the inner enclosure 604 of a power
adapter 701 may include a number of protrusions 606 which may be
heat-conducting spines. Protrusions 606 may inscribe a
parallelepiped or other geometrical volume such as a rectangular
cuboid. A thermally insulating cap may tip each of the protrusions
606. Collectively, the thermally insulating caps may form an outer
enclosure 602 that prevents the user from direct contact with inner
enclosure 604 and/or protrusions 606, and provides a lower touch
temperature. The thermally insulating caps need not necessarily
contact one another, although optionally may do so. The density of
protrusions 606 need not be designed to prevent touch access by the
user, as properly sized caps can prevent touch access by the user.
The spacing of the protrusions 606 may be adjusted to maximize
convective heat transfer and safety. The protrusions 606 may have
any suitable shapes such as a cylindrical shape, a fin shape, or
may have arbitrarily curved or straight surfaces.
[0061] In some embodiments, a power adapter may have a hybrid heat
removal system that utilizes passive cooling a portion of the time
and used active cooling at other times.
[0062] For example, a hybrid heat removal system may have an
actuated heat removal device that is turned off when it is not
needed but is turned on to actively remove heat as needed. For
example, the temperature of the power adapter may be sensed and a
controller of the power adapter may turn on actuated heat removal
device when the temperature exceeds a threshold. In some
embodiments, a hybrid heat removal system may avoid a need to
increase adapter size to handle worst-case heat loads in a passive
heat removal system. In some embodiments, a hybrid heat removal
system may be more reliable than an active heat removal system
where the cooling actuator runs a larger portion of the time (e.g.,
continuously). A hybrid heat removal system may enable using a
smaller actuated heat removal device than in a purely active heat
removal system. A hybrid heat removal system that intermittently
operates in an active mode can reduce wear on the moving
components, reduce noise, and/or reduce problems such as the
collection of dirt or dust. In some embodiments, a hybrid heat
removal system may have a housing with a plurality of enclosures,
as shown in FIG. 4 or 5, for example, as well as an actuated heat
removal device 202 (e.g., as illustrated in FIG. 3). In some
embodiments, a hybrid heat removal system may have an actuated heat
removal device 202 and a material with a high thermal mass. A
passive heat removal system using a material with a high thermal
mass will be discussed in connection with FIGS. 6 and 7.
[0063] The techniques described herein for controlling heat in a
power adapter may be particularly useful in a power adapter having
a relatively small volume. As discussed above, such techniques may
include actively removing heat from the power adapter using an
actuated heat removal device, such as a fan or bellows, to expel
heated air from the power adapter housing. Such techniques may
include passively removing heat from the power adapter using a
housing having an inner enclosure and an outer enclosure having one
or more openings. However, has been appreciated that it may be
desirable to control heat in a power adapter without the use of
openings in the power adapter housing, as such openings may have
disadvantages. For example, openings in the power adapter housing
may enable the ingress of dirt, dust, or moisture, which may reduce
the lifespan of the power adapter. Openings in the power adapter
housing may become blocked, thereby reducing heat removal
efficiency. Some manufacturers and consumers may prefer a fully
enclosed power adapter for reasons of product appearance and/or
compliance with safety regulations.
[0064] In some embodiments, consideration of the manner in which a
power adapter is to be used can allow designing a power adapter
that operates with a suitable operating temperature yet which does
not require openings in the housing to remove heat. An exemplary
use for a power adapter is powering an electronic device, such as a
laptop computer. The largest amount of power may be drawn by a
laptop when the battery of the laptop is being charged. A typical
laptop battery may take about 1.5-2.5 hours to fully charge from an
uncharged state. During this time, a significant amount of power
(greater than 40 W or 60 W) may be continually provided to the
laptop battery via the power adapter. Once the battery reaches
approximately 80% charge, the amount of power that is drawn may be
reduced. Charging the battery consumes much more power than simply
powering the laptop itself. Even if the processor of a laptop
computer is running at full utilization, the maximum power draw
from the processor may be no more than thermal design power which
may be as low as 13 W for ultrabooks, which is far less than the
amount of power needed to charge the battery. Thus, in a typical
use case where a laptop with a drained battery is plugged into a
power adapter, the power adapter will supply a significant amount
of power for about 1.5-2.5 hours, then, once the battery is
charged, the power demand drops to a lower level.
[0065] The present inventors have recognized and appreciated that
the heat in a power adapter can be managed by increasing the
thermal mass of the power adapter so that the temperature on the
exterior surface of the power adapter does not rise above maximum
(e.g. 30-40.degree. C.) for the time period of about 1.5-2.5 hours
while the power adapter provides power to charge a laptop battery.
In the lifecycle of the typical laptop power adapter, the power
delivery requirements typically drop at that point, allowing the
power adapter time to dissipate the accumulated heat.
[0066] In some circumstances, a user may decide to use the power
adapter in a way that does not follow the typical usage pattern for
power adapter. For example, a user may decide to charge a battery,
then remove the battery and charge a second battery immediately
thereafter. However such a use case is relatively rare, and can be
handled by reducing the amount of power provided by the power
adapter in such a circumstance, or designing the power adapter to
have an increased thermal mass to account for this scenario.
[0067] As discussed above, it is desirable to produce a power
adapter having a relatively small volume. However, decreasing the
mass of the power adapter conflicts with increasing the thermal
mass of the power adapter, as there is less space to accommodate
material that can absorb heat.
[0068] In some embodiments, a power adapter may include a material
with a relatively high thermal mass, or capability of absorbing
heat. By including a material with a high thermal mass, the power
adapter may have a high ratio of thermal mass to volume. The
thermal mass of the power adapter may be increased to a point where
the power adapter is capable of charging a laptop battery for
1.5-2.5 hours (e.g., at a power of greater than 40 W or 60 W)
without increasing the surface temperature of the power adapter
housing above a desired level. In some embodiments, the material
with a relatively high thermal mass may be a phase change material
that absorbs heat by producing a phase change in the material. For
example, a phase change material may change from a solid material
to a liquid material at a transition temperature. Phase change
materials can be designed that have different transition
temperatures. In some embodiments, a phase change material may be
selected that has a transition temperature suitable for absorbing
heat in a power adapter and limiting the surface temperature of the
power adapter to a desired operating range (e.g., below about
30-40.degree. C.). A phase change material may be selected with a
transition temperature close to the desired operating range. For
example, in some embodiments a phase change material may be
selected that has a transition temperature of approximately
30-40.degree. C. However, this is merely by example, and other
transition temperatures may be used. A suitable amount of phase
change material may be included to prevent the surface of the power
adapter from rising above a selected temperature during a time
interval, such as the time needed for charging a laptop battery, as
discussed above.
[0069] In some embodiments, the power adapter may include one or
more compartments to contain phase change material. Such
compartments may be sealed, to prevent the phase change material
from leaking therefrom in a liquid state. In some embodiments, the
phase change material may be provided in compartments around the
exterior of the power adapter. Since in the solid state phase
change material may have a relatively low thermal conductivity, the
compartments of phase change material may be arranged in such a way
that they can absorb heat generated in the power adapter without
unduly blocking the conduction of heat to the surface of the power
adapter. In other words, the power adapter may be designed such
that the phase change material does not overly block flux of heat
from the interior to the exterior of the power adapter. In some
embodiments, the power adapter may include a material with a high
thermal conductivity to provide a path of high thermal conductivity
for heat to flow from the interior of the power adapter to the
exterior. Any suitable material with a high thermal conductivity
may be used, such as a metal (e.g., aluminum). By providing
high-thermal-conductivity paths from the interior to the exterior
of the power adapter, heat can be more readily removed from the
phase change material. This can reduce the amount of time needed to
remove heat from the power adapter. so that the reset time is not
overly high.
[0070] The phase change material may only absorb a fraction of the
heat generated by the adapter. The rest of the heat may leave
through the outer surface of the adapter housing. The ratio of
absorption to convective removal depends upon the temperature the
outer skin is allowed to reach (which is in turn a function of the
transition temperature of the phase change material and the ratio
of high-thermal-conductivity paths from the power converter to the
external surface vs. the paths through the phase change
material).
[0071] FIG. 6A illustrates a cutaway side view of a power adapter
having a relatively high thermal mass, according to some
embodiments. FIG. 6B shows a cross section of the power adapter of
FIG. 6A along the line B-B'. FIG. 6B shows a cross section of the
power adapter of FIG. 6A along the line C-C'. The power adapter of
FIGS. 6A-6C includes compartments of phase change material 704 that
alternate with regions of high thermal conductivity 702 e.g.,
metal. The material high thermal conductivity 702 may allow the
conduction of heat from the interior to the exterior the power
adapter, while the phase change material 704 may provide a high
thermal mass and enable absorbing a significant amount of heat. An
outer enclosure 706 may be formed around the periphery of the power
adapter and may be formed of a material of low thermal conductivity
(e.g., plastic) suitable to be touched by a user.
[0072] FIG. 7A shows a side view and FIG. 7B shows a
cross-sectional view along the line D-D' of a power adapter
according to another embodiment in which compartment(s) of phase
change material are distributed around the housing of the power
adapter. Regions of high thermal conductivity 802 (e.g., metal) may
be formed between the regions of high thermal mass 804 (e.g., which
may include phase change material). FIG. 7A illustrates that the
regions of high thermal conductivity 802 may be posts extending
from the interior to the exterior of the power adapter.
[0073] Increasing the thermal mass of the power adapter may enable
controlling heat without requiring forming openings in the power
adapter housing to allow heated air to be expelled. However, in
some embodiments, openings may be included in the housing to
facilitate convective heat transfer. In this respect, the technique
of increasing the thermal mass of the power adapter may be combined
with another passive heat removal concept, such as a housing having
inner and outer enclosures. Alternatively or additionally, the
technique of increasing the thermal mass of the power adapter may
be combined with an active heat removal concept, such as the use of
an actuated heat removal device.
[0074] In some embodiments, a power adapter may be configured to
"quick charge" an electronic device. Using conventional power
adapters, it may take 1-3 hours or longer to charge the battery of
a consumer electronic device such as a mobile phone, tablet
computer, or laptop computer. For example, a conventional power
adapter that delivers 15 W may take about an hour to charge the
battery of a tablet computer from a fully drained state. It can be
desirable to charge mobile devices more quickly, particularly where
limited time is available for battery charging. As an example, a
traveler may wish to charge the battery of a mobile phone or tablet
computer prior to boarding a flight. In some embodiments, a power
adapter may provide a higher amount of power to enable charging the
battery more quickly. For example, a power adapter may deliver 60
W, which may allow charging a mobile device or tablet computer in a
fraction of an hour (e.g., less than fifteen minutes), as compared
to taking 1 hour with a power adapter that delivers 15 W.
[0075] The present inventors have appreciated that a power adapter
designed for "quick charging" may require less capability of
absorbing heat than a power adapter designed to charge a laptop
battery for a period of hours, as a "quick charging" power adapter
may only deliver power for a relatively short time interval (e.g.,
less than an hour, such as 15-30 minutes or less). A "quick
charging" power adapter that includes material with a high thermal
mass (e.g., phase change material) may include less such material
than a power adapter designed to deliver power for a larger time
period. Alternatively or additionally, the heat removal device may
operate intermittently (e.g., with a lower duty ratio). In some
embodiments, a "quick charging" power adapter may be designed to be
smaller than a power adapter designed to deliver power for a longer
time period.
[0076] FIG. 8 shows a block diagram illustrating power and control
circuitry 206, as well as optional sensors and an indicator device,
according to some embodiments. As shown in FIG. 8, power and
control circuitry 206 is connected to receive an AC input voltage,
such as an AC line voltage. An AC to DC converter 402 is configured
to convert the AC input voltage into a DC output voltage. In some
embodiments, AC to DC converter 402 may include a rectifier
followed by a DC/DC converter. The DC/DC converter may operate at a
relatively high switching frequency, such as in the VHF range (30
MHz to 300 MHz), and may utilize resonant switching techniques
and/or soft switching techniques to maximize efficiency. Suitable
power conversion circuitry is described in PCT application WO
2012/024542 (PCT/US2011/048326), filed Aug. 18, 2011, which is
hereby incorporated by reference in its entirety. However, the
techniques described herein are not limited in this respect, as
other suitable types of AC/DC converters may be used.
[0077] Controller 404 may control the operation of AC/DC converter
402 and actuated heat removal device 202 using suitable control
signals provided thereto. In some embodiments, as discussed above,
controller 404 may receive a signal from temperature sensor 406,
and may control the AC/DC converter 402 to reduce the amount of
power that is delivered when the temperature exceeds a threshold.
In some embodiments, controller 404 may increase or decrease the
actuation of actuated heat removal device 202 (e.g., if a fan is
used, the speed of the fan may be changed) in response to the
temperature signal from temperature sensor 406.
[0078] In some embodiments, a power adapter may include a touch or
proximity sensor 408 to detect when a person (e.g., a hand, for
example) comes close to or touches the power adapter. In response
to a signal detected by the touch or proximity sensor 408, a
human-perceptible effect may be produced. For example, the power
adapter may include an indicator device 410, such as a lighting
device (e.g., an LED) to produce light, and/or a device that can
produce an audible sound. In response to a signal detected by the
touch or proximity sensor 408, the indicator device 410 may be
turned on. For example, a lighting device may illuminate, which may
assist a user in finding the power adapter in the dark. As another
example, an audible sound may be played, which may assist a user in
finding an adapter that is in a difficult to reach location (e.g.,
under or behind furniture, for example). In some embodiments, if an
indicator device 410 is included, the power adapter may include an
energy storage device such as a battery or ultracapacitor to
provide power to the indicator device.
[0079] In some embodiments, the controller 404 may be configured to
change the actuation of the actuated heat removal device 202 in
response to detecting touch or proximity of a person. For example,
in some embodiments the actuation of the actuated heat removal
device 202 may be reduced or stopped in response to detecting touch
or proximity of a human hand.
[0080] In some embodiments, controller 404 may measure an amount of
power provided to input of the power adapter and/or at the output
of the power adapter. The power adapter may have an interface, such
as a wired or wireless interface (e.g., a WiFi or Bluetooth
interface device) to enable communication with an external device.
The power adapter may send information regarding the measured power
and/or total energy to the external device (e.g., a laptop
computer, tablet computer, smartphone or server) so that a person
(e.g., a user) can view the information to find out how much power
is consumed by a device connected to the output of the power
adapter.
[0081] In some embodiments, a power adapter may include one or more
DC output connection ports that enable one or more cords to be
removably connected thereto. In some embodiments, one or more cords
may be provided having electrical connector(s) designed to connect
to the DC output connection port(s) of the power adapter. The
cord's connector may be held in place at the DC output connection
port using any suitable technique, such as a mechanical connection
and/or through magnetic attraction.
[0082] FIG. 9 shows that a power adapter may have a plurality of DC
output connection ports 501, 502 and 503. The side of the power
adapter shown in FIG. 9 may correspond to the end of the power
adapter to which cord 104 is connected (e.g., the left side of FIG.
1, for example). As shown in FIG. 9, cord 104 may have a connector
505 configured to removably connect to DC output connection port
501. Cord 104 may have a connector 106 for connecting to a first
type of electronic device (e.g., a laptop). Other cords may be
provided having the same type of connector 505 but different
connectors 106 for connecting to other types of electronic devices
(e.g., smart phones, tablet computers, etc.). Such cords may be
provided in a kit along with the power adapter, in some
embodiments. Accordingly, a user may select a suitable cord having
the appropriate connector 106 to connect to a device that the user
wishes to power and/or charge. Advantageously, power adapter may be
a universal power adapter that is capable of charging a plurality
of different devices (e.g., laptops, cellular telephones, tablet
computers, etc.). Accordingly, a user may travel with one small
universal power adapter that is capable of charging multiple
different devices, rather than carrying multiple power adapters
dedicated to each of the user's devices.
[0083] In some embodiments, each cord that may be connected to DC
output connection port 501 may be individually identifiable by the
power adapter when it is plugged in. For example, when a user plugs
in a particular type of cord to a DC output connection port, the
power adapter may determine the type of cord that is plugged in.
Such a determination may be made in any of a variety of ways. For
example, the cord may be designed to have a certain impedance when
measured, and the power adapter may perform an impedance
measurement on a cord when it is connected to identify it. As
another example, the cord may be provided with an integrated
circuit that identifies the cord. Such an integrated circuit may be
provided in connector 505 and/or connector 106, by way of example.
As another example, a cord may be identified based on time domain
reflectometry. Any suitable technique for identifying a cord may be
used.
[0084] The power adapter (e.g., controller 404) may determine a
suitable DC output voltage to be provided based on identification
of the cord. For example, when a first cord is plugged in, the
power adapter may identify the cord as being designed to provide a
5V DC output voltage. Accordingly, the controller 404 may control
the AC/DC converter 402 to provide a 5V DC output voltage to the
corresponding DC output port to which the cord is connected. If
another cord is plugged into the same DC output port, the power
adapter may identify the cord as being designed to provide a 9V DC
output voltage. Accordingly, the controller 404 may control the
AC/DC converter 402 to provide a 9V DC output voltage to the DC
output port.
[0085] In some embodiments, a power adapter is capable of powering
and/or charging a plurality of devices at the same time. For
example, a first connector of a first cord may plug into DC output
connection port 501 for powering a laptop, a second connector of a
second cord may plug into a DC output connection port 502 for
powering a cellular telephone, and/or a third cord may plug into DC
output connection port 503 for powering another device. In a power
adapter configured to power and/or charge a plurality of devices at
a time, the AC/DC converter may be configured to provide a
plurality of DC outputs of suitable output voltages to the
respective DC output connection ports. The output voltages of the
DC outputs may be different, to enable charging different types of
devices, or may be the same.
[0086] DC output connection ports 501, 502 and 503 may be the ports
of the same shape and type or ports of different shapes and/or
types to accept different types of connectors. In some non-limiting
embodiments, one or more of the DC output connection ports may be
USB ports (e.g., USB 3.0 ports). However, the techniques described
herein are not limited as to the particular types of connection
port(s) employed.
[0087] As discussed above, the power adapters described herein are
capable of providing significant output power in a small sized
housing. In some embodiments, the volume of the power adapter
(excluding cords) may be relatively small, such as 5 cubic inches
or less, 4 cubic inches or less, 3 cubic inches or less, or 2 cubic
inches or less. For example, in some embodiments the power adapter
may be about 2 inches in length or less, about 1 inch in width, or
less and about 1 inch in height or less. In some embodiments, the
output power provided by the power adapter is at least 30 W, such
as at least 40 W, at least 45 W at least 60 W, at least 80 W, or at
least 100 W or higher. In some embodiments, the power converter may
provide a power conversion density of 15 W/in.sup.3 or higher, 20
W/in.sup.3 or higher, 30 W/in.sup.3 or higher, 40 W/in.sup.3 or
higher, or 50 W/in.sup.3 or higher. The term "power conversion
density" refers to the maximum amount of power a power conversion
module (e.g., a power adapter) can deliver divided by the volume of
the power conversion module (i.e., as bounded by the housing of the
power adapter, and excluding cords).
[0088] Described above is a power adapter which may be used for
powering and/or charging consumer electronic devices. However, the
techniques described herein are not limited to power adapters for
consumer electronic devices. Some embodiments relate to a power
conversion module for other electronic devices, such as servers or
other devices in a data center, which may benefit from a reduction
in size of the power electronics. Other non-limiting examples of
applications include power electronics for industrial equipment and
electronics for automobiles, aircraft and ships.
[0089] Various aspects of the apparatus and techniques described
herein may be used alone, in combination, or in a variety of
arrangements not specifically discussed in the embodiments
described in the foregoing description and is therefore not limited
in its application to the details and arrangement of components set
forth in the foregoing description or illustrated in the drawings.
For example, aspects described in one embodiment may be combined in
any manner with aspects described in other embodiments.
[0090] Use of ordinal terms such as "first," "second," "third,"
etc., in the claims to modify a claim element does not by itself
connote any priority, precedence, or order of one claim element
over another or the temporal order in which acts of a method are
performed, but are used merely as labels to distinguish one claim
element having a certain name from another element having a same
name (but for use of the ordinal term) to distinguish the claim
elements.
[0091] Also, the phraseology and terminology used herein is for the
purpose of description and should not be regarded as limiting. The
use of "including," "comprising," or "having," "containing,"
"involving," and variations thereof herein, is meant to encompass
the items listed thereafter and equivalents thereof as well as
additional items.
* * * * *