U.S. patent application number 16/262086 was filed with the patent office on 2020-07-30 for high power direct current/alternating current inverter.
The applicant listed for this patent is U.S. GOVERNMENT AS REPRESENTED BY THE SECRETARY OF THE ARMY. Invention is credited to Alexander M. Soles.
Application Number | 20200244178 16/262086 |
Document ID | 20200244178 / US20200244178 |
Family ID | 1000004954581 |
Filed Date | 2020-07-30 |
Patent Application | download [pdf] |
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United States Patent
Application |
20200244178 |
Kind Code |
A1 |
Soles; Alexander M. |
July 30, 2020 |
High Power Direct Current/Alternating Current Inverter
Abstract
One example is an inverter assembly for converting direct
current (DC) to alternating current (AC). A DC connector on the
inverter assembly is connected to an upper DC bus. A silicon
carbide (SiC) heat sink is mounted above the upper DC bus and at
least one capacitor is mounted above the SiC heat sink. A lower DC
bus is connected to the upper DC bus and a liquid cooled cold-plate
cooling unit is positioned between the upper and lower DC busses.
SiC half-bridge units are located between the upper DC bus and the
cold-plate and between the lower DC bus and the cold-plate. A gate
driver unit is located on the upper DC bus above one converter
heatsink and another driver located on the lower DC bus below the
other converter heatsink. An AC output connector connects the
converters to the AC output connecter.
Inventors: |
Soles; Alexander M.;
(Warren, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
U.S. GOVERNMENT AS REPRESENTED BY THE SECRETARY OF THE
ARMY |
Washington |
DC |
US |
|
|
Family ID: |
1000004954581 |
Appl. No.: |
16/262086 |
Filed: |
January 30, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H02M 1/08 20130101; H02M
7/5387 20130101; H05K 7/20927 20130101; H05K 7/20872 20130101; B60R
16/02 20130101; H05K 7/20254 20130101; H02M 1/44 20130101; H02M
7/003 20130101 |
International
Class: |
H02M 7/00 20060101
H02M007/00; H02M 7/5387 20060101 H02M007/5387; H02M 1/08 20060101
H02M001/08; H05K 7/20 20060101 H05K007/20; H02M 1/44 20060101
H02M001/44; B60R 16/02 20060101 B60R016/02 |
Goverment Interests
GOVERNMENT INTEREST
[0001] The inventions described herein may be made, used, and/or
licensed by or for the U.S. Government for U.S. Government
purposes.
Claims
1. An inverter assembly comprising: a direct current (DC) connector
on a front side of the inverter assembly, wherein the inverter
assembly has the front side, a backside, a left side, and a right
side; an upper DC bus connected to the DC connector; at least one
capacitor mounted below the upper DC bus near a corner formed by
the left side and front side of the inverter assembly, wherein the
at least one capacitor is connected to the upper DC bus to filter a
DC signal on the upper DC bus; a lower DC bus connected to the
upper DC bus; a liquid cooled cold-plate cooling unit positioned
between the upper DC bus and the lower DC bus; a first silicon
carbide (SiC) half-bridge unit located between the upper DC bus and
the cold-plate cooling unit; a second SiC half-bridge unit located
between the lower DC bus and the cold-plate cooling unit; a first
gate driver located on the upper DC bus above the first SiC
half-bridge unit configured to, in combination with the first SiC
half-bridge unit, convert a DC signal into an AC signal; a second
gate driver located below the lower DC bus and below the second SiC
half-bridge unit, wherein the second gate driver is configured to,
in combination with the second half-bridge unit, convert the DC
signal into an AC signal; an AC output connector on the backside of
the inverter assembly; and at least one AC bus segment with a first
end and a second end; wherein the first end is connected to the
first SiC half-bridge unit and to the second SiC half-bridge unit,
and wherein the second end of the AC bus segment is connected to
the AC output connecter, wherein the AC output connector is
configured to provide the AC signal as an output signal.
2. The inverter assembly of claim 1 wherein the upper DC bus is
L-shaped when viewed from above the inverter assembly.
3. The inverter assembly of claim 1 further comprising: a digital
signal processor (DSP) configured to receive feedback from at least
the first SiC half-bridge unit and to control the first gate driver
and the first SiC half-bridge unit to produce a AC signal based, at
least in part, on the feedback.
4. The inverter assembly of claim 1 wherein the inverter assembly
is capable of 200 kW or more in an ultra-compact arrangement with
power densities of 27 kW/liter or more at the power stage and 16
kW/L overall with connectors and enclosure included, and wherein,
the inverter assembly is a rectangular box shape with dimensions of
approximately but not limited to 301 mm.times.228 mm.times.110
mm.
5. The inverter assembly of claim 1 wherein twelve upper gate
driver units are located on the upper DC bus above one or more SiC
half-bridge units, wherein twelve lower gate driver units are
located below the lower DC bus below one or more SiC half-bridge
units.
6. The inverter assembly of claim 1 wherein the first SiC
half-bridge unit and the second SiC half-bridge unit each further
comprise: a Hall-effect sensor.
7. The inverter assembly of claim 1 wherein the at least one
capacitor has a combined value of between 200 uF and 400 uF.
8-9. (canceled)
10. A flow-through power inverter bus of a power inverter
comprising: a first flow-through bus segment having a first end and
a second end for transmitting a first DC voltage received at the
first end of the first flow-through bus segment from a direct
current (DC) input connector; a second flow-through bus segment
having a first end and a second end for transmitting a second DC
voltage, wherein the first end of the second flow-through bus
segment is configured to receive the second DC voltage from the DC
input connector that is a lower voltage than the first DC voltage;
a third flow-through bus segment having a first end and a second
end for transmitting an AC voltage; wherein the power inverter has
a front side, a backside, a left side, and a right side; wherein
one or more high power capacitors are configured to be mounted near
the front side of the power inverter with a first terminal of the
one or more high power capacitors connected to the first
flow-through bus segment and a second terminal of the one or more
high power capacitors connected to the second flow-through bus
segment; an SiC half-bridge unit formed below a bottom side of the
first flow-through bus segment and adjacent the backside of the
power inverter; one or more driver units mounted above a top side
of the first flow-through bus segment opposite the SiC half-bridge
unit with the second end of the second flow-through bus segment
connected to the SiC half-bridge units; a cooling plate mounted
adjacent a bottom side of the SiC half-bridge unit with the second
flow-through bus segment attached to the SiC half-bridge unit,
wherein the first end of the third flow-through bus segment is
configured to connect to an output of the SiC half-bridge unit and
the second end of the third flow-through bus segment is configured
to deliver an alternating current (AC) to an AC output
connector.
11. The flow-through bus of claim 10, wherein the third segment of
the flow-through bus further comprises: three separate phase
segments connected to separate SiC half-bridge units that each are
configured to generate, at least a portion, of one of three phases
of an AC signal.
12. The flow-through bus of claim 10 wherein the SiC half-bridge
unit is configured to attach to a top surface of the cooling
plate.
13. The flow-through bus of claim 10 wherein the cooling plate is
configured to be liquid cooled.
14. flow-through bus of claim 10 wherein the SiC half-bridge unit
is formed below a bottom side of the second flow-through bus
segment, and wherein a voltage difference between the first
flow-through bus segment and the second flow-through bus segment is
greater than 450 volts.
15. The flow-through bus of claim 10 wherein the SiC half-bridge is
configured to connect to a digital signal processor (DSP) and
provide feedback to A DSP.
16. The flow-through bus of claim 10 wherein the driver unit is
configured to include a Hall-effect sensor.
17. The flow-through bus of claim 10 wherein the power inverter is
configured to be capable of 200 kW or more in an ultra-compact
arrangement, with power densities of 27 kW/liter or more at the
power stage and not limited to 16 kW/L overall with connectors and
enclosure included.
18. A method of converting high power direct current (DC) voltage
to high power alternating current (AC) voltage, comprising:
receiving the DC voltage onto an upper DC bus; filtering the DC
voltage on the upper DC bus with capacitance to remove EMI;
generating the AC voltage by rectifying the DC voltage using DC to
AC converters, wherein the DC to AC converters comprise a gate
driver above an SiC rectifier, wherein a cooling unit is adjacent
and below the SiC rectifier, and wherein a DC bus carrying the DC
voltage is adjacent the gate driver and the SiC rectifier; and
receiving the AC voltage at an AC output connector, wherein the AC
voltage is ready to power a high power AC voltage device.
19. The method of claim 19 wherein the cooling unit is a cold-plate
cooling unit and further comprising: cooling the DC to AC
converters by pumping cooling liquid through the cold-plate cooling
unit.
20. The method of claim 18 wherein the SiC converter comprises a
half-bridge rectifier.
21. The method of claim 18 wherein the SiC converter comprises a
half-bridge rectifier. A DC to AC converter comprising: an upper DC
bus with a top surface and a bottom surface configured to receive a
DC signal; at least one large power capacitor configured to filter
the DC signal; a lower DC bus with a top surface and a bottom
surface, wherein the lower DC bus is connected to the upper DC bus;
a cold-plate cooling unit with a top surface and a bottom surface;
a first SiC half-bridge unit with a top surface and a bottom
surface; a second SiC half-bridge unit with a top surface and a
bottom surface; a first gate driver unit; and a second gate driver
unit, wherein the top surface of the first SiC half-bridge unit is
located beneath the bottom surface of the upper DC bus and above
the top surface of the cold-plate cooling unit, wherein the second
SiC half-bridge unit is located above the top surface of the lower
DC bus and beneath the bottom surface of the cold-plate cooling
unit, wherein the first driver unit is located above the top
surface of the upper DC bus and above the top surface of the first
SiC half-bridge unit; wherein the second driver unit is located
under the bottom surface of the lower DC bus below the bottom
surface of the second SiC half-bridge unit; and wherein the first
half-bridge unit and the second half-bridge unit are configured to
convert the DC signal into an AC signal.
22. The DC to AC converter of claim 21 wherein the cold-plate
cooling unit is cooled by pumping an engine coolant through the
cold-plate cooling unit, wherein the power inverter is configured
to be mounted on a vehicle that is to pump the engine coolant.
Description
TECHNICAL FIELD
[0002] A high power bi-directional direct current/alternating
current (DC/AC) inverter utilizes a "flow-through" DC bus design
that has minimal length and minimal turns/rotations to flow current
from its input DC connector to its output AC connector with low
power loss. The inverter uses silicon-carbide for high power
applications as well as a unique cold-plate and converter power
electronics cooling structure. In particular, the inverter relates
generally to a flow-through bus utilizing silicon-carbide
components that is compact in physical dimensions for high power,
elevated temperature applications.
BACKGROUND
[0003] A power inverter, or inverter, is an electronic device
and/or circuitry that changes direct current (DC) into alternating
current (AC). Some inverters also have the capability of converting
AC into DC, and vice versa. The input voltage, output voltage and
frequency, and overall power handling depends, in part, on the
design of the specific device/circuitry. The inverter does not
produce power. Instead, the power is provided by an AC or a DC
source. A power inverter are entirely electronic but historically
have been a combination of mechanical effects (such as a rotary
apparatus) and electronic circuitry. Static (electronic) inverters
do not use moving parts in the conversion process. For example,
digital signal processors (DSPs) can perform the functions of
generating an AC signal that were once performed by mechanical
devices.
SUMMARY
[0004] The following presents a simplified summary of the disclosed
subject matter to provide a basic understanding of some aspects of
the various embodiments. This summary is not an extensive overview
of the various embodiments. It is intended neither to identify key
or critical elements of the various embodiments nor to delineate
the scope of the various embodiments. Its sole purpose is to
present some concepts of the disclosure in a streamlined form as a
prelude to the more detailed description that is presented
later.
[0005] One example embodiment is an inverter assembly. The inverter
assembly has a front side, a backside, a left side, and a right
side. The inverter assembly further has one or more direct current
(DC) connectors on the front side and an upper DC bus is connected
to the DC connector. One or more capacitor(s) may be mounted below
the upper DC bus near the front of the inverter assembly. A lower
DC bus is connected to the upper DC bus and a liquid cooled
cold-plate cooling unit is positioned between the upper DC bus and
the lower DC bus. A first SiC half-bridge unit is located between
the upper DC bus and the cold-plate cooling unit and a second SiC
half-bridge unit is located between the lower DC bus and the
cold-plate cooling unit. A first driver unit is located on the
upper DC bus above the first SiC half-bridge unit to drive the DC
signal to the first SiC half-bridge unit. A second driver unit is
located beneath the lower DC bus and below the second SiC
half-bridge unit to also convert the DC signal into an AC signal.
An AC output connector is located on the backside of the inverter
assembly. An AC bus segment with three phase first ends and a
second ends has its first ends connected to the first and second
SiC half-bridge units and its second ends connected to the AC
output connecter.
[0006] Another configuration includes a bi-directional DC to AC and
AC to DC converter that may be used in high power inverters. The DC
to AC converter includes an upper DC bus with a top surface and a
bottom surface for receiving a DC signal, a lower DC bus with a top
surface and a bottom surface, cold-plate cooling unit with a top
surface and a bottom surface, a first SiC half-bridge unit with a
top surface and a bottom surface, a second SiC half-bridge unit
with a top surface and a bottom surface, and first and second
driver units. The lower DC bus is connected to the upper DC bus so
that they are at the same DC voltage potential. The upper surface
of the first SiC half-bridge unit is located beneath the lower
surface of the upper DC bus and above the upper surface of the
cold-plate cooling unit. The second SiC half-bridge unit is located
above the upper surface of the lower DC bus and beneath the lower
surface of the cold-plate cooling unit. The first driver unit is
located on the upper surface of the upper DC bus and above the
upper surface of the first SiC half-bridge unit and the second
driver unit is located under the lower surface of the lower DC bus
and below the bottom surface of the second SiC half-bridge unit.
The first driver unit/first SiC half-bridge unit and the second
driver unit/second SiC half-bridge unit convert the DC signal into
an AC signal.
[0007] Another configuration is "flow-through" power inverter bus
for use in a power inverter. The flow-through power inverter bus
includes a first flow-through bus segment having a first end and a
second end for transmitting a first DC voltage, a second
flow-through bus segment having a first end and a second end for
transmitting a second DC voltage, and a third flow-through bus
segment having a first end and a second end. The power inverter has
a front side, a backside, a left side, and a right side. The first
end of the first flow-through bus segment receives the first DC
voltage from a DC input connector and the first end of the second
flow-through bus segment receives the second DC voltage from the DC
input connector. The second end of the third flow-through bus
segment delivers an AC current to an AC output connector.
[0008] One or more high power capacitors are configured to be
mounted near the front side of the power inverter with a first
terminal of the one or more high power capacitors connected to the
first flow-through bus segment and a second terminal of the one or
more high power capacitors connected to the second flow-through bus
segment. A first SiC half-bridge unit is configured to be formed on
a bottom side of the first flow-through bus segment and to be
formed adjacent the backside of the power inverter. One or more
upper driver units are configured to be mounted above a top side of
the first flow-through bus segment opposite the first SiC
half-bridge unit below the bottom side of the first flow-through
bus segment. The first end of the third flow-through bus segment is
configured to connect to the first SiC half-bridge unit. The first
flow-through bus segment is configured to be connected to the upper
gate drivers. A cooling plate is configured to be attached to the
first SiC half-bridge unit. The first end of the third flow-through
bus segment is configured to be connected to outputs of the first
SiC half-bridge unit and the second end of the third flow-through
bus segment is configured to be connected to the AC output
connector.
[0009] Another example is a method of converting high power direct
current (DC) voltage to high power alternating current (AC) and
vice versa, using a flow-through bus. A DC voltage is received onto
an upper DC bus. The DC voltage is then filtered on the upper DC
bus with capacitance to remove electromagnetic interference (EMI).
The method next generates the AC voltage by rectifying the DC
voltage using DC to AC converters. The AC voltage is then received
at an AC output connector. The AC voltage may then power a high
power AC voltage device.
[0010] The following description and the annexed drawings set forth
in detail certain illustrative aspects of the subject matter.
However, these aspects are indicative of some of the numerous ways
in which the principles of the subject matter can be employed.
Other aspects, advantages, and novel features of the disclosed
subject matter will become apparent from the following detailed
description when considered in conjunction with the drawings. It
will also be appreciated that the detailed description may include
additional or alternative embodiments beyond those described in
this summary.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] One or more preferred embodiments that illustrate the best
mode(s) are set forth in the drawings and in the following
description. The appended claims particularly and distinctly point
out and set forth the invention.
[0012] The accompanying drawings, which are incorporated in and
constitute a part of the specification, illustrate various example
embodiments and other example methods of various aspects of the
invention. It will be appreciated that the illustrated element
boundaries (e.g., boxes, groups of boxes, or other shapes) in the
figures represent one example of the boundaries. One of ordinary
skill in the art will appreciate that in some examples, one element
may be designed as multiple elements or that multiple elements may
be designed as one element. In some examples, an element shown as
an internal component of another element may be implemented as an
external component and vice versa. Furthermore, elements may not be
drawn to scale.
[0013] FIG. 1 illustrates a first example left side view of an
embodiment of power inverter that utilizes silicon carbide (SiC)
half-bridges.
[0014] FIG. 2 illustrates an example top view of the example
embodiment of the power inverter of FIG. 1.
[0015] FIG. 3 illustrates an example backside, right side, and top
perspective view of another embodiment of a power inverter
utilizing SiC half-bridges.
[0016] FIG. 4 illustrates an example bottom, right side, and
backside perspective view of the embodiment of a power inverter of
FIG. 3.
[0017] FIG. 5 illustrates an example front side, left side, and top
perspective view of the embodiment of a power inverter of FIG. 3
showing the SiC half-bridges.
[0018] FIG. 6 illustrates an example front side, left side, and top
perspective view of the embodiment of a power inverter of FIG. 3
showing the AC phase busses within the SiC half-bridges.
[0019] FIG. 7 illustrates an example front side, left side, and top
perspective view of the embodiment of a power inverter of FIG. 3
showing the DC to AC converters.
[0020] FIG. 8 illustrates an example front side and top perspective
view of the embodiment of a power inverter of FIG. 3 showing detail
of the DC bus.
[0021] FIG. 9 illustrates an example backside perspective view of
the embodiment of a power inverter of FIG. 3 showing detail of the
AC bus.
[0022] FIG. 10 illustrates an example side view of an example
configuration of a DC to AC converter.
[0023] FIG. 11 illustrates an example electrical schematic view of
an embodiment of a power inverter.
[0024] FIG. 12 illustrates an example side view of an embodiment of
a flow-through power inverter bus.
[0025] FIG. 13 illustrates an example top view of the embodiment of
the flow-through power inverter bus of FIG. 12.
[0026] FIG. 14 illustrates an example left, top perspective view of
the embodiment of the flow-through power inverter bus with
capacitor cooling.
[0027] FIG. 15 illustrates an example left, top, backside
perspective view of the embodiment of the flow-through power
inverter bus of FIG. 14.
[0028] FIG. 16 illustrates an example left side view of the
embodiment of the flow-through power inverter bus of FIG. 14.
[0029] FIG. 17 illustrates an example top, right side, backside
view of the embodiment of the flow-through power inverter bus of
FIG. 14.
[0030] FIG. 18 illustrates an example backside view of the
embodiment of the flow-through power inverter bus of FIG. 14.
[0031] FIG. 19 illustrates an example view of a method of
converting high power direct current (DC) to high power alternating
current (AC).
[0032] FIG. 20 illustrates an example view of an embodiment of a
computer system.
DETAILED DESCRIPTION
[0033] Fundamentally, a power inverter, or assembly, is a device
that bi-directionally converts direct current (DC) into alternating
current (AC), and vise-versa using a series of electronic switches
and electronic feedback systems to facilitate stable conversion.
The inverter assembly (e.g., power inverter 100 of FIGS. 1-9 is
additionally significantly focused on power delivery unlike prior
art power inverters. The power inverter 100 of FIGS. 1-9 is a
compact, power dense, high temperature/operation power inverter 100
that utilizes silicon carbide (SiC) to significantly decrease heat
issues at key locations in the power inverter 100. To reduce heat
generation, this power inverter 100 utilizes SiC half-bridge
rectifiers when generating an AC signal from a DC signal. The power
inverter 100 of FIGS. 1-9 utilize a power stage that is a
"flow-through" architecture (busses generally flow from front to
back) in concert with SiC technology as well as specialized control
feedback electronics to implement an AC signal from a DC signal.
Flow-through bus-work design is unique because it's design allows
the electrical energy to flow-through from the DC stages to the AC
switch stages with minor restriction (e.g., generally straight
through without looping or reverse travel) thus minimizing
electrical bus area while yielding highest power delivery at lowest
possible power loss. This significantly lowers the electrical
impedance and inductance of the power path as well as lowers the
typically required DC link capacitor and AC switch snubber stage
size. This in turn improves thermal performance, serviceability,
and significantly reduces production/assembly time. This results in
the power inverter 100 with silicon carbide having a current
capability of 200 kW or more in an ultra-compact arrangement, with
power densities of up to 27 kW/L at the power stage and 16 kW/L
overall with connectors and enclosure included. Dimensions of less
than 100 mm.times.200 mm.times.300 mm, may operate with coolant
temperature exceeding 105 degrees Celsius and ambient temperatures
exceeding 125 degrees Celsius, for bi-directional power
capabilities (power can be converted from AC to DC). The power
inverter 100 is capable of driving/accepting power from a majority
of drive system motors/generators commercially available today with
a similar power rating as the power inverter 100.
[0034] Having a power inverter 100 operational at this elevated
temperature capability is useful in a variety of apparatus,
devices, systems, environments, and the like. The power inverter
100 of FIGS. 1-9 that uses SiC based half-bridge rectifiers as well
as a cold plate flowing cooling fluid drastically reduces the need
for a high cooling system envelope of hybrid-electric military
vehicles. One reason for this is because engine coolant can be used
in the cold plate to cool the power inverter 100, the SiC half
bridge rectifiers generate minimal heat compared to prior
rectifiers, and, also, the ultra-compact design frees up valuable
space for other critical systems and personnel. Its high power
capability allows for the use of advanced vehicle start/stop
technology, the use of pure electric or hybrid-electric drivetrains
enabling silent mobility, the use of electrified cooling systems,
the use of electric power steering, electric vehicle assist
componentry, advanced power weaponry, vehicle-to-electrical-grid as
a back-up power source, and the like. Traditional inverter systems
are not capable of delivering the performance required because of
fundamental limitations due to overall size, current power output,
and the requirement of lower temperature coolant for safe
operation. This results in having the ability to be use the power
inverter 100 in (but not limited to): advanced vehicle start/stop
technology hybrid-electric drivetrain, pure electric drivetrain,
electrified cooling systems, electric power steering, electric
assist component, advanced power weaponry,
vehicle-to-electrical-grid, alternative energy conversion, and
traditional permanent magnet AC (PMAC) motor drive systems.
[0035] The inverter assembly (power inverter) 100 of FIG. 1-9 is
now discussed in more detail. The inverter assembly 100 is roughly
rectangularly shaped and has a front side 102, a backside 104, a
left side 106, and a right side 108. In general, the inverter
assembly 100 includes a high voltage direct current (DC) connector
110, a fan voltage DC connector 112, an upper DC bus 114, a lower
DC bus 116, an AC output connector 118, at least one capacitor 120,
a liquid cooled cold-plate cooling unit 122, a first SiC half
bridge unit 130, a second SiC half-bridge unit 132, a first gate
driver unit 140, a second gate driver unit 142, and an AC bus
segment(s) 150.
[0036] The high voltage DC connector 110 is on the front side 102
of the inverter assembly 100 and the upper DC bus 114 is connected
to the high voltage DC connector 110. The capacitor(s) 120 is
mounted under the upper DC bus 114 near a corner formed by the left
side 106 and front side 102 of the inverter assembly 100 and are
connected between a high DC voltage and a low DC voltage input. The
at least one capacitor 120 has a combined value of between 200 and
400 uF. Analog simulations indicated that two capacitors 120
provide an optimal performance, but any number of capacitors may be
used to implement a desired capacitance value.
[0037] A DC to AC voltage transformation assembly 125 is now
discussed. Of course, when converting DC current/voltage to AC
current/voltage this assembly 125 would work in the reverse. Also,
and as discussed later with reference to FIG. 11, this assembly may
include AC to DC (or DC to AC when operated in reverse) converters
formed with a data driver 144, a half-bridge unit 146, and a
Hall-effect current sensor as generally seen in FIGS. 3, 4 and 7.
The voltage transformation assembly 125 is generally formed by a
portion of the upper DC bus 114, the lower DC bus 116 as well as
the liquid cooled cold-plate cooling unit 122, the first SiC
half-bridge unit 130, and that second SiC half-bridge unit 132. The
lower DC bus 116 is connected to the upper DC bus 114 so that they
are at the same DC voltage potential. The liquid cooled cold-plate
cooling unit 122 is positioned between the upper DC bus 114 and the
lower DC bus 116. The first SiC half-bridge unit 130 is located
between the upper DC bus 114 and a top of the cold-plate cooling
unit 122. The second SiC half-bridge unit 132 is located between
the lower DC bus 116 and a bottom of the cold-plate cooling unit
122. The first gate driver unit 140 is located on the upper DC bus
114 above the first SiC half-bridge unit 130 and drives the DC
signal to the first SiC half bridge unit 130. The second gate
driver unit 142 is located on the lower DC bus 116 below the second
SiC half-bridge unit 132 and similarly drives the DC signal to the
second SiC half bridge unit 132.
[0038] In one example embodiment, the first and second half-bridge
units 130, 132 may, for example be manufacture by Cree. For
example, the half-bridge units may have characteristics of: 1200V,
325 A, Silicon Carbide High-Performance 62 mm Half-Bridge Module,
similar to Cree's SKU: CAS325M12HM2. The technical features of the
first and second half-bridge units 130, 132 may include one or more
of: ultra-low loss, low inductance, high-efficiency operation,
high-frequency, ultra-fast switching operation, zero
reverse-recovery current from diode, zero turn-off tail current
from MOSFET, normally-off, fail-safe device operation, ease of
paralleling, an AISiC baseplate and Si.sub.3N.sub.4 AMB insulator,
enhancing ruggedness with respect to thermal cycling, and/or other
features as desired.
[0039] In some configurations, twelve upper gate driver units 140
(separated into high and low side drivers, two per gate driver
circuit card to support SiC half-bridge topology), or some other
desired number of drivers are located on the upper DC bus 114 above
one or more SiC half-bridge units 130. Similarly, twelve lower gate
driver units 142 are located below the lower DC bus 116 below one
or more SiC half-bridge units 132. The SiC half-bridge units 130,
132, with the gate driver units 140, 142 are configured to
simultaneously convert the DC signal into a three-phase AC signal.
In some configurations, the first and second gate driver units 140,
142 are each additionally formed with transistors, and/or other
components as desired.
[0040] The AC output connector 118 is located on the backside of
the inverter assembly 100. The AC bus segment 150 has three
portions 150A-C for the three phases of electrical power with each
portion each having a first end and a second end. The first ends
are connected to the SiC half-bridge units 130, 132 and the second
ends are connected to the AC output connecter 118. The power
inverter 100 of FIGS. 1-9 utilizes a power stage with associated
busses that is "flow-through" architecture in concert with high
power SiC half-bridge technology and as well as specialized control
feedback electronics.
[0041] As previously mentioned, flow-through bus-work design is
unique because it allows the electrical energy to flow-through from
the DC stages to the AC switch stage, or vice versa, with minor
restriction (e.g., generally straight through without looping or
reverse travel). For example, as illustrated in FIGS. 1 and 2, the
upper DC bus 114 and lower DC bus 116 simply travel from the front
side 102 to the backside 104 in one continuous flow with only
minimal deflection of current as indicated by arrows "A" in FIG. 1
and arrows "B" in FIG. 2. Note that those of ordinary skill in the
art will appreciate that this inverter is bi-directional so that
current flows in the opposite direction of arrows "A" when
converting AC current to DC current.
[0042] The rather direct "flow through path" lowers the impedance
and inductance of the power path as well as lowers the typically
required DC link capacitor stage size. This in turn improves
thermal performance, serviceability, and significantly reduces
production/assembly time. As mentioned earlier, the power inverter
100 with silicon carbide (SiC) is currently capable of 200 kW or
more in an ultra-compact arrangement, with power densities of up to
27 kW/L. The inverter assembly 100 is capable of 200 kW or more in
an ultra-compact arrangement with power densities of 27 kW/liter or
more at the power stage and 16 kW/L overall with connectors and
enclosure included. Due, in part, to the flow-through path of the
upper DC bus, the inverter assembly 100 may generally be a
small/compact rectangular box shape with rectangular dimensions
less than 301 mm.times.228 mm.times.110 mm.
[0043] In some embodiments, the upper DC bus 114 is connected to a
first DC voltage at the DC connector 110, as previously mentioned.
However, a second DC voltage bus is connected at one end to a
different second DC voltage at the DC connector 110 and is used as
a chassis ground.
[0044] In some other embodiments, the half-bridge units (i.e.,
rectifiers, switches) 130, 132 may be switched at any application
specific frequency, typically 1-50 kHz for motor/generator
applications, by a DSP 170 or another micro-controller (discussed
further below) to produce a three-phase output Other embodiments
may switch the half-bridge rectifiers 130, 132 at another suitable
frequency to produce an adequate three phase output. In some
embodiments, the AC output signal may have peak values of 1200
volts at 600 amps and nominal values of 600 volts at 325 amps. At
these values, the three-phase system generated by the inverter
assembly 100 may operate at a relatively high coolant temperature
of about 105 degrees Celsius through the cold-plate cooling unit
and nominally convert about 200 kW of power. An inverter
constructed similar to the inverter assembly 100 illustrated in
FIGS. 1-9 has been prototyped and successfully tested to at least
the nominal values over a 45-minute time frame considered to be
continuous operation. Because the DC to AC converters 140, 142 are
mounted adjacent the SiC half-bridge Units 130, 132, which are
adjacent the cold plate cooling unit 122, heat is readily
dissipated to allow for high power operation of the inverter
assembly 100. Based on the initial performance of the inverter
assembly of FIGS. 1-9, when a vehicle is operated using the
inverter assembly 100 and is flowing standard engine coolant of the
vehicle through the liquid cooled cold-plate cooling unit 122, the
inverter assembly 100 is operational at 105 degrees C. and 200
kW.
[0045] In another embodiment, the high-power inverter assembly 100
includes the digital signal processor (DSP) 170, first mentioned
above. The DSP 170 receives feedback from the DC to AC voltage
transformation assembly 125. For example, the feedback may be
sensor feedback associated with a shape of an AC signal that the DC
to AC voltage transformation assembly 125 is generating and
outputting. In essence, this feedback generally indicates to
processor (DSP controller) 170 how the AC signals are actually
formed. The DSP 170 may then adjust controls to the DC to AC
voltage transformation assembly 125 to produce a desired AC signal
based, at least in part, on the feedback.
[0046] "Processor" and "Logic", as used herein, includes but is not
limited to hardware, firmware, software and/or combinations of each
to perform a function(s) or an action(s), and/or to cause a
function or action from another logic, method, and/or system. For
example, based on a desired application or needs, logic and/or
processor may include a software-controlled microprocessor,
discrete logic, an application specific integrated circuit (ASIC),
a programmed logic device, a memory device containing instructions
or the like. Logic and/or processor may include one or more gates,
combinations of gates, or other circuit components. Logic and/or a
processor may also be fully embodied as software. Where multiple
logics and/or processors are described, it may be possible to
incorporate the multiple logics and/or processors into one physical
logic (or processor). Similarly, where a single logic and/or
processor is described, it may be possible to distribute that
single logic and/or processor between multiple physical logics
and/or processors.
[0047] In other configurations, the inverter assembly 100 may
contain other useful components and features. In some embodiments,
a transient voltage suppressor (TVS) may be added to the upper DC
bus 114 to begin suppression of electromagnetic noise and may
include electromagnetic hardening, electromagnetic shielding walls,
and other interference suppression techniques may be implemented,
as desired. The inverter 100 may be small enough to be used in
commercial trucks, military vehicles, and other vehicles. While
operating in trucks, military vehicles and the like, the AC output
from the inverter assembly 100 may be used with a "pancake"
generator or another type of generator to generate electricity to
power government facilities, infrastructure, businesses and homes
after a disaster, power the vehicle in a stealth mode with
electrical power converted by the inverter assembly previously
stored in batteries, power electromagnetic weapons (lasers,
directed energy, rail-gun and etc.) with DC power stored in
batteries, as well as other operations requiring high AC power
and/or high DC power.
[0048] FIG. 10 illustrates an example configuration of a DC to AC
converter 1000. In general, the converter 1000 includes an upper DC
bus 1014 with a top surface 1014A and a bottom surface 1014B, a
lower DC bus 1016 with a top surface 1016A and a bottom surface
1016B, a liquid cooled cold-plate cooling unit 1022 with a top
surface 1022A and a bottom surface 1022B, a first SiC half-bridge
unit 1030 with a top surface 1030A and a bottom surface 1030B, a
second SiC half-bridge unit 1032 with a top surface 1032A and a
bottom surface 1032B, a first driver unit 1040, and a second driver
unit 1042.
[0049] The converter 1000 may have some similarities to the DC to
AC voltage transformation assembly 125 discussed above. The upper
DC bus 1014 may be connected to a high voltage DC connector (not
illustrated in FIG. 10). The lower DC bus 1016 is connected to the
upper DC bus 1014 so that they are at the same DC voltage
potential. The upper surface 1030A of the first SiC half-bridge
unit 1030 is located beneath the lower surface 1014B of the upper
DC bus 1014 and the upper surface 1022A of the cold-plate cooling
unit 1022. The second SiC half-bridge unit 1032 is located between
the upper surface 1016A of the lower DC bus 1016 and the lower
surface 1022B of the cold-plate cooling unit 1022. The first driver
unit 1040 is located on the upper surface 1014A of the upper DC bus
1014 above the upper surface 1030A of the first SiC half-bridge
unit 1030. The second driver Unit 1042 is located under the lower
surface 1016B of the lower DC 1016 bus and below the bottom surface
1032B of the second SiC half-bridge unit 1032. Both the first
driver unit 1040 and the second driver unit 1042 are configured to
drive the DC signal to the SiC half-bridge units 130, 132. In other
configurations, any a number of drivers 1040 may be located on the
upper surface 1014A of the upper DC bus 1014 above the upper
surface 1030A of the first SiC half-bridge units 1030 to achieve a
desired AC signal. Similarly, any number of lower gate driver units
1042 may located under the lower surface 1016B of the lower DC bus
1016 below the lower surface 1032B of the second SiC half-bridge
units 1032 to achieve a desired AC signal.
[0050] In some embodiments, the cold-plate cooling unit 1022 may be
liquid cooled. For example, the cold-plate cooling unit 1022 may be
cooled from a liquid coolant of a combustion engine that is
operating on a vehicle that the converter 1000 is associated with.
The cold-plate cooling unit 1022 may be cooled with oil or any
desirable liquid by pumping liquid into a first opening 1023 in the
cold-plate cooling unit 1022 and transferring the heated liquid
through the cold-plate from a second opening 1024 in the cold-plate
cooling unit 1022.
[0051] FIG. 11 illustrates one example of an electrical functional
diagram 1200 of the example embodiments of the previous figures.
The high voltage DC signals 1201 are received and initially pass
through overvoltage protection circuits 1202. The overvoltage
protection circuits 1202 may each include a Zener diode, a common
source module 1206, a gate driver 1208, and/or other circuits as
understood by one with ordinary skill in the art. These protected
signals are input to a DSP controller 1210. A direct current
voltage and ground fault interrupt (GFI) sensor 1212 may also be
attached to the DSP controller 1210 to remove noise from a power
signal. A pair of Hall-effect current sensors 1214 connected to the
high voltage inputs also generate signals input to the DSP
controller 1210 and a bank of capacitors 1221.
[0052] The DSP controller 1210 runs software instructions to aid in
the creation of the AC output signal(s) similar to what was
discussed above. The DSP controller 1210 is connected to low
voltage electronics 1216 with interconnects 1218 or other
connections. The low voltage electronics 1216 perform a variety of
functions including a processing control area network (CAN) bus
(CANBUS) secure protocol, processing motor resolve signals, and
performing other "housekeeping" and related functions not easily
performed in the DSP controller 1210, as understood by one of
ordinary skill in the art. A Peltier cooler 1220 may be used to
cool the DSP controller 1210 and/or the low voltage electronics
1216 to promote longer electronics lifespan.
[0053] Capacitors 1221 may be used to at least filter some noise
from the high DC signal received as inputs. The filtered high DC
voltage is input into six DC to AC (or AC to DC) converters 1230 so
that AC output signals 1236A-C (or DC signal 1201) may be
generated. Of course, in on other embodiments any desired number of
DC to AC converters 1230 may be used to generate the AC output
signals 1236A-C. As discussed above, the DC to AC (AC to DC)
converters 1230 may include a date driver 144, a half-bridge unit
146, and a Hall-effect current sensor 148 forming portions of each
of these converters 1230.
[0054] One example of a flow-through power inverter bus 1300 is
illustrated in example FIGS. 12-13. The flow-through power inverter
bus 1300 is part of a power inverter 1301 that has a front side
1302, a backside 1304, a left side 1306, and a right side 1308. The
flow-through power inverter bus 1300 has a first flow-through bus
segment 1312, a second flow-through bus segment 1314, and at least
one third flow-through bus segment 1316. In three phase AC power
configurations, there would be three of these third flow through
bus segments for each of the three phases, as understood by those
of ordinary skill in the art. The first flow-through bus segment
1312 has a first end 1312A and a second end 1312B and transmits a
first DC voltage. The second flow-through bus segment 1314 has a
first end 1314A and a second end 1314B and transmits the second DC
voltage. The third flow-through bus segment 1316 has a first end
1316A and a second end 1316B and transmits an AC voltage.
[0055] The first end 1312A of the first flow-through bus segment
1312 receives the first DC voltage from a direct current (DC) input
connector 1326 and the first end 1314A of the second flow-through
bus segment 1314 receives the second DC voltage from the DC input
connector 1326. The second ends 1316B of the third flow-through bus
segment 1316 delivers an alternating current (AC) from at least one
AC to DC converter 1324 (formed with the first gate driver unites
1325 and the second SiC half-bridge units 1324, 1336) to an AC
output connector 1328.
[0056] Two high power capacitors 1332 are mounted near the front
side 1302 and the left side 1304 of the power inverter 1301 with a
first terminal of the high power capacitors 1332 connected to the
first flow-through bus segment 1312 and a second terminal of the
high power capacitors 1332 connected to the second flow-through bus
segment 1314. The first terminal may be at a higher DC voltage
value than the second terminal. In some configurations, and as best
seen in FIGS. 14-18, additional cooling may be added to the
capacitors 1318. For example, copper "heat pipes" 1317 may be used
to create thermal transfer (non-electrical) heat transfer in vapor
tubes. The heat pipes 1317 can be purchased commercially and may be
used similar to CPU heatsinks. These heat pipes 1317 transfer the
heat energy from, for example, peltier coolers located under the
capacitors 1332 to the one or more cold plates (not illustrated)
that may be attached to the cold plate 1340.
[0057] One or more first gate driver units 1325 (to control SiC
half-bridge units 1334, 1336) may be mounted on a top side of the
first flow-through bus segment 1312 opposite the first SiC
half-bridge unit 1334 on the bottom side of the first flow-through
bus segment 1312. Note, in some configurations, that the SiC
portion of the half-bridge units may act at least partially as a
heatsink and transfer heat to a cooling plate 1340. The second end
1312B of the first flow-through bus segment 1312 is configured to
connect to inputs of the one or more first gate driver unit(s)
1325. A cooling plate (cold-plate) 1340 may be attached to, or
located near, the first SiC half-bridge unit 1334. In some
embodiments, a second SiC half-bridge unit 1336 may, if desired, be
located under the cold-plate cooling unit 1340 as illustrated. The
first end 1314A of the second flow-through bus segment 1314 is
connected to the low DC input voltage at the DC input connector
1326 and the second end 1314B of the second flow-through bus
segment 1314 is configured to be connected to the SiC half-bridge
units 1334, 1336. The short, compact design of the "flow-through"
technology is indicated by example arrows "C" and "D" in FIGS. 12
and 13, respectively, wherein these arrows show that current flows
right to left without loop backs or drastic turns when converting
DC power to AC power. As understood by those of ordinary skill in
the art, current flows in reverse of arrows "C" and "D" when the
power inverter 1301 operates to convert AC power to DC power. The
compact and short bus route lowers the impedance and inductance of
the power path as well as lowers the typically required DC link
capacitor stage size. This in turn improves thermal performance,
serviceability, and significantly reduces production/assembly
time.
[0058] The first end 1316A of the third segment 1316 of the
flow-through bus is configured to connect to outputs of the twelve
separate driver units 1325. Each first gate driver unit 1325 is
configured to generate, at least a portion, of one of three phases
of an AC signal to flow onto three separate phase segments of the
third flow-through bus segment 1316. The seconds ends 1316B of the
third segment 1316 are connected the AC output connector 1328.
[0059] Other embodiments of FIGS. 12 and 13 may have other useful
features and/or components. For example, in some configurations,
the flow-through bus 1300 may be configured to interact with the
cooling plate 1340 configured to be liquid cooled. In other
configurations, the first half bridge unit 1334 may form a partial
heatsink. The flow-through bus may interact with the gate driver
units 1325 and the half-bridge units 1334, 1336 to connect to a
digital signal processor (DSP) and provide feedback to the DSP. A
power inverter implementing the flow through busses 1312, 1314,
1316 of FIGS. 12-13 may be capable of 200 kW or more with power
densities of 27 kW/liter or more at the power stage and 16 kW/L
overall with connectors and enclosure included in a compact
rectangular size.
[0060] Methods that can be implemented in accordance with the
disclosed subject matter, may be at least partially implemented
with reference to the following flow charts. While, for purposes of
simplicity of explanation, the methods are shown and described as a
series of blocks, it is to be understood and appreciated that the
disclosed aspects are not limited by the number or order of blocks,
as some blocks can occur in different orders and/or at
substantially the same time with other blocks from what is depicted
and described herein. Moreover, not all illustrated blocks can be
required to implement the disclosed methods. It is to be
appreciated that the functionality associated with the blocks can
be implemented by software, hardware, a combination thereof, or any
other suitable means (e.g. device, system, process, component, and
so forth). Additionally, it should be further appreciated that in
some embodiments the disclosed methods are capable of being stored
on an article of manufacture to facilitate transporting and
transferring such methods to various devices. Those skilled in the
art will understand and appreciate that the methods could
alternatively be represented as a series of interrelated states or
events, such as in a state diagram.
[0061] Thus, various embodiments can be implemented as a method,
apparatus, or article of manufacture using standard programming
and/or engineering techniques to produce software, firmware,
hardware, or any combination thereof to control a computer to
implement the disclosed subject matter. The term "article of
manufacture" as used herein is intended to encompass a computer
program accessible from any computer-readable device,
machine-readable device, computer-readable carrier,
computer-readable media, machine-readable media, computer-readable
(or machine-readable) storage/communication media. For example,
computer-readable media can comprise, but are not limited to, a
magnetic storage device, e.g., hard disk; floppy disk; magnetic
strip(s); an optical disk (e.g., compact disk (CD), a digital video
disc (DVD), a Blu-ray Disc.TM. (BD)); a smart card; a flash memory
device (e.g., card, stick, key drive); and/or a virtual device that
emulates a storage device and/or any of the above computer-readable
media. Of course, those skilled in the art will recognize many
modifications can be made to this configuration without departing
from the scope or spirit of the various embodiments
[0062] FIG. 19 illustrates some example actions of a method 1400 of
converting high power direct current (DC) voltage to high power
alternating current (AC). The method receives, at 1402, the DC
voltage onto an upper DC bus. As discussed above, this may be a
flow-through bus for very high-power transfer/low power loss on the
bus. The DC voltage is filtered, at 1404, on the upper DC bus with
capacitance to remove EMI. Other EMI or noise filtering may be
performed as needed or desired. The AC voltage is generated, at
1406, by rectifying the DC voltage using DC to AC converters. As
mentioned above, these converters may include half-bridges,
Hall-effect sensors (as part of the half-bridges), drivers, and
other components. In some configurations, the DC to AC converters
may be cooled by pumping cooling liquid through a cold-plate
adjacent the DC to AC converters. An AC output connector receives
the AC voltage, at 1408. This AC voltage is ready to convert power
or receive power one or more high power AC voltage devices such as
electric machinery mounted to a truck that may include motor(s)
and/or generator(s). As mentioned earlier, the power inverter 100
with silicon carbide (SiC) is currently capable of 200 kW or more
in an ultra-compact arrangement, with power densities of up to 27
kW/L or more at the power stage and 16 kW/L overall with connectors
and enclosure included. The method 1400 may provide for converting
high DC current to High AC current with an inverter at a power of
200 kW or more in an ultra-compact arrangement with power densities
of 27 kW/liter or more at the power stage and 16 kW/L overall with
connectors and enclosure included within a small/compact
rectangular shaped size with rectangular dimensions less than 301
mm.times.228 mm.times.110 mm
[0063] FIG. 20 illustrates an example computing device in which
example systems and methods described herein, and equivalents, may
operate. The example computing device may be a computer 2000 that
includes a processor 2002, a memory 2004, and input/output ports
2010 operably connected by a bus 2008. In one example, the computer
2000 may include a DSP logic 2030 configured to aid DC to AC
converters in the formation of a high-power AC signal as described
above. In different examples, the DSP logic 2030 may be implemented
in hardware, software, firmware, and/or combinations thereof. Thus,
the DSP logic 2030 may provide means (e.g., hardware, software,
firmware) for implementing DSP types of operations. While the DSP
logic 2030 is illustrated as a hardware component attached to the
bus 2008, it is to be appreciated that in one example, the logic
2030 could be implemented in the processor 2002.
[0064] Generally describing an example configuration of the
computer 2000, the processor 2002 may be a variety of various
processors including dual microprocessor and other multi-processor
architectures. The memory 2004 may include volatile memory and/or
non-volatile memory. Non-volatile memory may include, for example,
ROM, PROM, EPROM, and EEPROM. Volatile memory may include, for
example, RAM, synchronous RAM (SRAM), dynamic RAM (DRAM),
synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM),
direct RAM bus RAM (DRRAM) and the like.
[0065] A disk 2006 may be operably connected to the computer 2000
via, for example, an input/output interface (e.g., card, device)
2018 and an input/output port 2010. The disk 2006 may be, for
example, a magnetic disk drive, a solid state disk drive, a floppy
disk drive, a tape drive, a Zip drive, a flash memory card, and/or
a memory stick. Furthermore, the disk 2006 may be a CD-ROM, a CD
recordable drive (CD-R drive), a CD rewriteable drive (CD-RW
drive), and/or a digital video ROM drive (DVD ROM). The memory 2004
can store a process 2014 and/or a data 2016, for example. The disk
2006 and/or memory 2004 can store an operating system that controls
and allocates resources of computer 2000.
[0066] The bus 2008 may be a single internal bus interconnect
architecture and/or other bus or mesh architectures. While a single
bus is illustrated, it is to be appreciated that the computer 2000
may communicate with various devices, logics, and peripherals using
other busses (e.g., PCIE, SATA, Infiniband, 11384, Universal Serial
Bus, Serial Peripheral Bus (SPI), Inter-Integrated Circuit Bus
(I2C), Power Line Carrier bus, CAN bus, Ethemet). The bus 2008 can
be types including, for example, a memory bus, a memory controller,
a peripheral bus, an extemal bus, a crossbar switch, and/or a local
bus.
[0067] The computer 2000 may interact with input/output devices via
the input/output interfaces 2018 and the input/output ports 2010.
Input/output devices may be, for example, a keyboard, a microphone,
a pointing and selection device, cameras, video cards, displays,
the disk 2006, the network devices 2020, and so on. The
input/output ports 2010 may include, for example, serial ports,
parallel ports, USB ports and the like.
[0068] The computer 2000 can operate in a network environment and
thus may be connected to network devices 2020 via input/output
interfaces 2018, and/or the input/output ports 2010. Through the
network devices 2020, computer 2000 may interact with a network.
Through the network, the computer 2000 may be logically connected
to remote computers. Networks with which the computer 2000 may
interact include, but are not limited to, Serial Peripheral Bus
(SPI), Inter-Integrated Circuit Bus (I2C), a power line carrier bus
(PLC), a controller area bus (CAN), a local area network (LAN), a
wide area network (WAN), and other networks. The networks may be
wired and/or wireless networks.
[0069] In the foregoing description, certain terms have been used
for brevity, clearness, and understanding. No unnecessary
limitations are to be implied therefrom beyond the requirement of
the prior art because such terms are used for descriptive purposes
and are intended to be broadly construed. Therefore, the invention
is not limited to the specific details, the representative
embodiments, and illustrative examples shown and described. Thus,
this application is intended to embrace alterations, modifications,
and variations that fall within the scope of the appended claims.
Accordingly, the disclosure is intended to embrace all such
alterations, modifications, and variations that fall within the
scope of this application, including the appended claims.
[0070] Moreover, the description and illustration of the invention
is an example and the invention is not limited to the exact details
shown or described. References to "the preferred embodiment", "an
embodiment", "one example", "an example" and so on, indicate that
the embodiment(s) or example(s) so described may include a
particular feature, structure, characteristic, property, element,
or limitation, but that not every embodiment or example necessarily
includes that particular feature, structure, characteristic,
property, element, or limitation. Additionally, references to "the
preferred embodiment", "an embodiment", "one example", "an example"
and the like, are not to be construed as preferred or advantageous
over other embodiments or designs. Rather, use of the words "the
preferred embodiment", "an embodiment", "one example", "an example"
and the like are intended to present concepts in a concrete
fashion.
[0071] As used in this application, the term "or" is intended to
mean an inclusive "or" rather than an exclusive "or." That is,
unless specified otherwise or clear from context, "X employs A or
B" is intended to mean any of the natural inclusive permutations.
That is, if X employs A; X employs B; or X employs both A and B,
then "X employs A or B" is satisfied under any of the foregoing
instances. In addition, the articles "a" and "an" as used in this
application and the appended claims should generally be construed
to mean "one or more" unless specified otherwise or clear from
context to be directed to a singular form.
[0072] Reference throughout this specification to "one embodiment,"
or "an embodiment," means that a particular feature, structure, or
characteristic described in connection with the embodiment is
included in at least one embodiment. Thus, the appearances of the
phrase "in one embodiment," "in one aspect," or "in an embodiment,"
in various places throughout this specification are not necessarily
all referring to the same embodiment. Furthermore, the particular
features, structures, or characteristics can be combined in any
suitable manner in one or more embodiments.
* * * * *