United States Patent (19)
`Weimer et al.
`
`54
`54 SUPER CAPACTOR CHARGING
`75 Inventors: Joseph A. Weimer, Springboro; Bick
`T. Nguyen, Miamisburg; Marian K.
`Kazimierczuk, Beavercreek; Brett A.
`Jordan, London, all of Ohio
`73 Assignee: The United States of America as
`represented by the Secretary of the
`Air Force, Washington, D.C.
`
`USOO59 14542A
`Patent Number:
`11
`(45) Date of Patent:
`
`5,914,542
`Jun. 22, 1999
`
`5,256,907 10/1993 Shimada et al. .......................... 307/82
`5,359,277 10/1994 Cowett, Jr. .........
`323/207
`5,373,195 12/1994 De Doncker et al. .................... 307/45
`5,602,464 2/1997 Linkowsky et al. ...
`323/272
`5,612,579 3/1997 Wisbey et al. ............................ 307/18
`
`Appl. No.: 08/843,406
`21
`1-1.
`22 Filed:
`Apr. 15, 1997
`6
`51) Int. Cl. ..................................................... H01H 47/00
`52 U.S. CI.
`307/125; 307/43; 307/64;
`307s5,30723. 307/82: 323/222, 323224
`58) Field of Search s
`s
`s
`307/43 44, 45
`307/46,64, 65,66,70 8O 82. 8 4. 85.
`86. 87, 18 33. 323222. 223 2.4 2s22ss
`s Y-
`s -- Y-9 a-1s
`s
`s
`s
`References Cited
`
`56)
`
`Primary Examiner Richard T. Elms
`Assistant Examiner Jonathan S Kaplan
`Attorney, Agent, or Firm-Gerald B. Hollins; Thomas L.
`Kundert
`ABSTRACT
`57
`An aircraft electrical energy Supply bus Supplementing
`arrangement based on large capacitor or Super capacitor
`Storage of electrical energv for buS Supplementation. Sup
`9.
`gy
`pp
`p
`plying of bus energy to the large capacitor is addressed in the
`invention. In this Supplying energy is removed from the
`aircraft bus during quiescent conditions under the control of
`a energy coupling circuit which has a plurality of different
`energy removal rates, rates which are Selected in response to
`the yet needed amount of capacitor charging and in a
`time-constant-controlled manner. Feedback control of this
`charging time constant Selection is employed along with
`passive electrical device dissipation of major fractions of the
`U.S. PATENT DOCUMENTS
`4.551,632 11/1985 Jourdan et al. ............................. so time constant apparatus energy losses.
`4,802,859 2/1989 Gouldy et al. ...
`... 439/74
`4,967,096 10/1990 Diemer et al. ............................ 307/19
`20 Claims, 7 Drawing Sheets
`
`
`
`Petitioner Intel Corp., Ex. 1032
`IPR2023-00783
`
`

`

`U.S. Patent
`
`Jun. 22, 1999
`
`Sheet 1 of 7
`
`5,914,542
`
`
`
`Petitioner Intel Corp., Ex. 1032
`IPR2023-00783
`
`Petitioner Intel Corp., Ex. 1032
`IPR2023-00783
`
`

`

`U.S. Patent
`
`Jun. 22, 1999
`
`Sheet 2 of 7
`
`5,914,542
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`
`
`218
`
`126 220
`212
`
`V=28V
`2O6
`
`2O
`
`218 - 204
`
`ow In
`
`V. C
`c
`
`Boo
`Convert
`
`20
`
`2 Tig. 26
`
`Petitioner Intel Corp., Ex. 1032
`IPR2023-00783
`
`

`

`U.S. Patent
`U.S. Patent
`
`Jun. 22, 1999
`Jun. 22, 1999
`
`Sheet 3 of 7
`Sheet 3 of 7
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`5,914,542
`5,914,542
`
`
`
`
`
`Petitioner Intel Corp., Ex. 1032
`IPR2023-00783
`
`Petitioner Intel Corp., Ex. 1032
`IPR2023-00783
`
`

`

`U.S. Patent
`U.S. Patent
`
`Jun. 22, 1999
`Jun. 22, 1999
`
`Sheet 4 of 7
`Sheet 4 of 7
`
`5,914,542
`5,914,542
`
`Ve
`
`V2
`
`24V
`
`V22
`
`/20V
`
`Fig. 4a
`
`oo Fig.4d
`
`Petitioner Intel Corp., Ex. 1032
`IPR2023-00783
`
`Petitioner Intel Corp., Ex. 1032
`IPR2023-00783
`
`

`

`U.S. Patent
`
`Jun. 22, 1999
`
`Sheet 5 of 7
`
`5,914,542
`
`O
`
`O
`
`t
`
`fity. 4e
`
`> Fig. 4f
`
`Petitioner Intel Corp., Ex. 1032
`IPR2023-00783
`
`

`

`U.S. Patent
`U.S. Patent
`
`Jun. 22, 1999
`Jun. 22, 1999
`
`Sheet 6 of 7
`Sheet 6 of 7
`
`5,914,542
`5,914,542
`
`
`
`
`
`Petitioner Intel Corp., Ex. 1032
`IPR2023-00783
`
`Petitioner Intel Corp., Ex. 1032
`IPR2023-00783
`
`

`

`U.S. Patent
`U.S. Patent
`
`Jun. 22, 1999
`Jun. 22, 1999
`
`Sheet 7 of 7
`Sheet 7 of 7
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`5,914,542
`5,914,542
`
`Rs - 304
`DS2
`Rg-304
`
`
`
`202
`
`rpse
`
`Petitioner Intel Corp., Ex. 1032
`IPR2023-00783
`
`Petitioner Intel Corp., Ex. 1032
`IPR2023-00783
`
`

`

`1
`SUPER CAPACTOR CHARGING
`
`5,914,542
`
`CROSS REFERENCE TO RELATED PATENT
`DOCUMENTS
`The present document is Somewhat related to the copend
`ing and commonly assigned patent documents "Feedfoward
`Control of Aircraft Bus DC Boost Converter', AFD 00129,
`Ser. No. 08/843,428; and “Super Capacitor Battery Clone”
`AFD 00102, Ser. No. 08/843,408, now U.S. Pat. No. 5,850,
`113; which are filed of even date herewith. The contents of
`these related two
`
`RIGHTS OF THE GOVERNMENT
`The invention described herein may be manufactured and
`used by or for the Government of the United States for all
`governmental purposes without the payment of any royalty.
`applications are hereby incorporated by reference herein.
`
`15
`
`BACKGROUND OF THE INVENTION
`This invention relates to the charging of electrical energy
`Storage components, and more particularly to a charger
`uSable with the Super capacitor energy Storage elements of
`an aircraft electrical energy Supply augmentation apparatus.
`Batteries are widely used to Store electrical energy.
`However, the use of batteries encounters numerous
`problems, problems largely relating to the electrochemical
`nature of an electrical battery, problems which include
`Severe energy density limitations, environmental hazards,
`Safety problems, maintenance costs, charging rate
`limitations, finite number of possible charge cycles and
`battery life, memory problems in Some batteries Such as the
`popular NiCd device, complicated charging circuits, and
`need for continuous replacement.
`Future aircraft electrical energy Supply Systems in addi
`tion may involve the widespread use of a higher Voltage
`direct current electrical energy distribution bus, a distribu
`tion involving energization by the rectified output of a
`polyphase alternator and Voltages above the level of one
`hundred Volts, for example. In addition to greater levels of
`energy availability and reduced weight of conductor metal
`which is possible in Such distribution Systems, the use of
`higher Voltage distribution in these future aircraft is seen to
`offer advantages in the area of lower bus current levels,
`Smaller bus, conductor Space requirements, and better elec
`trical transient control or filtering, particularly as to filter
`weight reduction. These advantages are considered to out
`weigh the obvious complications of conventional battery
`exclusion from the bus (e.g., because of the large number of
`individual battery cells required), absence of bus
`accomplished Stand alone or Static engine Start capability,
`increased hazard to perSonnel, and increased electrical insu
`lation requirements. The F-22 tactical aircraft is perhaps one
`of the first aircraft with bus energization of this higher
`Voltage direct current type to be considered for widespread
`use by the United States Air Force. Additional discussion
`regarding the energy bus arrangements under consideration
`for future aircraft and the criticality of Some loads Supplied
`from these bus arrangements is to be found in the technical
`paper “Power Management and Distribution for the More
`Electric Aircraft' by Joseph A. Weimer, presented at the
`InterSociety Energy Conservation Engineering Conference
`(IECEC) as paper No. AP-385, ASME 1995.
`AS an improvement to both these future high Voltage
`aircraft Systems, and to present-day lower Voltage direct
`current bus distribution Systems as well, the use of energy
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`Storage accomplished in a replacement or a Supplement to
`the commonly encountered electrical battery, e.g., the lead
`acid or nickel-cadmium battery, is envisioned. Moreover, the
`use of Such energy Storage capability disposed at Several
`distributed locations along the physical extent of an electri
`cal bus or disposed within particular bus load devices (Such
`as avionics or other electronic System housings) is a part of
`this improved aircraft bus thinking. Such energy Storage
`capability may take the form of one or more Storage ele
`ments which can float on the bus with little energy demand
`or current flow during normal operating conditions, employ
`relatively low current and long duration recharging times
`and then be capable of rapidly Supplying energy to accom
`modate brief intervals of heavy bus demand or transient
`loading or bus Source interruption. Such arrangements
`could, for example, enable further reductions in bus metal
`mass and cross-sectional area and improve Voltage regula
`tion along the bus, i.e., could enhance the tradeoff between
`bus size and bus Voltage regulation.
`The configuration of Such energy Storage elements used at
`distributed locations along a bus for this heavy demand or
`transient loading improvement is now considered to reason
`ably include large capacitance capacitors, i.e., capacitors of
`the multiple farad electrical size or "Super capacitor' type;
`Such capacitors are also known as double-layer capacitors in
`the art. In this configuration it is notable that the capacitor
`is employed as an energy Storage element rather than for its
`low alternating current impedance or other characteristics.
`Indeed, a Super capacitor may not provide the lowest alter
`nating current impedance available in a capacitor. Such
`“Super capacitors' are, however, considered preferable to a
`battery for present energy Storage uses for reasons of Size,
`weight, reliability and decreased maintenance requirements,
`and are now readily available as commercial products.
`Capacitors of this nature are, however, most readily fabri
`cated as units of large electrical size having moderate
`operating Voltage capability. AS noted below herein sizes
`Such as an integral number of farads of electrical capacitance
`and a few tens of operating volts capability are now con
`Veniently provided. Capacitors of this electrical rating may
`of course be combined in appropriate Series and parallel
`combinations for use in the present invention.
`By way of additional background it may be interesting to
`consider that the Super capacitor element itself was first
`investigated by Helmholtz in 1879. According to one Super
`capacitor arrangement, one electrode of the device is made
`of carbon and the other is made of a liquid electrolyte. When
`a Voltage is applied to the carbon layer with respect to the
`liquid electrolyte, a thin dielectric layer is established adja
`cent the carbon layer particles. The effective Surface area of
`the dielectric layer and the carbon particles is, however,
`extremely large. Surface areas on the order of 1000 Square
`meters per gram of carbon material can be achieved with
`Such electrode arrangements because of the porous Surface
`of the carbon and the small carbon particle size. The
`thickness of the dielectric layer on the other hand can be
`extremely Small-on the order of 1 nanometer. As a result,
`a high ratio of Surface area to dielectric thickness can be
`obtained and Surprising capacitances per unit of capacitor
`volume are obtainable, therefore desirable volumetric effi
`ciency is obtained for Such a capacitor. AS may be Surmised
`from a consideration of Such structural details, however,
`questions of permissible operating voltage (i.e., the dielec
`tric strength of the thin dielectric layer), tolerable current
`flow rates and resulting temperature rise, energy losses,
`liquid electrolyte inconvenience and physical Stability of this
`type of Super capacitor require Special consideration in the
`capacitor's design and fabrication Sequences.
`
`Petitioner Intel Corp., Ex. 1032
`IPR2023-00783
`
`

`

`3
`The large capacitance of Super capacitors nevertheless
`permits the Storage of relatively large amounts of energy. AS
`is well known in the electrical art, however, a change in the
`quantity of electrical energy Stored in a Super capacitor or
`any capacitor, unlike most battery types, involves a precisely
`related change in the capacitor's terminal Voltage; moreover,
`the capacitor's Stored energy quantity is a Square-law func
`tion of the capacitor's terminal Voltage. Therefore, in an
`energy Storage use of Such a capacitor there is a need for a
`power processing circuit capable of maintaining the output
`Voltage constant while the Voltage across the Super capacitor
`decreases due to its discharge. When viewed from a different
`perspective this decreasing Voltage relationship also dictates
`that the Storage of useful quantities of electrical energy in a
`capacitor of practical electrical and physical size requires the
`capacitor to operate under conditions of large terminal
`Voltage Swing. This characteristic is, however, poorly Suited
`to direct bus shunting use of Such capacitors in an aircraft or
`in other electrical bus Supplementing applications Since a
`bus is desirably operated with very limited changes in
`Voltage. Enormously sized capacitors are therefore required
`to Store meaningful quantities of usable energy under the
`conditions of little capacitor Voltage change.
`The use of an electronic coupling arrangement, i.e., a
`device Such as a direct current to direct current inverter
`Switching circuit, is seen as an answer to this Storage
`efficiency and other difficulties Such capacitor energy Stor
`age can encounter. With Such a coupling circuit providing
`energy transfer between a “Super capacitor Storage element
`and the aircraft bus, the capacitor Voltage can be allowed to
`Swing through a large range and thereby provide relatively
`efficient (and again voltage Square law-determined) energy
`Storage while the aircraft bus Voltage is held nearly constant.
`Such a coupling arrangement also allows a marriage of
`incompatible capacitor and bus Voltage ratings, allows for
`controlled or limited current recharging of the capacitor
`from the bus and other advantages. With respect to the
`marriage of incompatible capacitor and bus Voltage ratings
`in a bus Supplement apparatus, it is perhaps helpful to
`appreciate that presently available Super capacitors are
`capable of Several hundred farads of capacitance within a
`Single physical container and with an operating Voltage of
`3–20 volts. Such capacitors provide a Stored energy density
`of 10–20 joules per gram of capacitor weight.
`The present invention, and each of the above-identified
`companion inventions relating to the present invention,
`concern a different portion of an aircraft bus Supplementing
`energy Storage arrangement disposed generally according to
`this description. In the present invention a particular aspect
`of a capacitance charging electronic coupling between an
`aircraft Supply bus and a “Super capacitor', i.e., one aspect
`of a direct current charging arrangement for a Super capaci
`tor energy Storage element, is considered. The present inven
`tion provides an alternative for the Super capacitor charging
`disclosed in the above identified “Super Capacitor Battery
`Clone", AFD 00102, Ser. No. 08/843,408 patent application
`and particularly addresses one aspect of the difference
`encountered in use of a Voltage-responsive capacitance
`element rather than a fixed voltage battery element for
`Storing buS Supplement energy, a difference encountered in
`Supplying energy directly to the Super capacitor Storage
`element. Another of these patent application, the Feedfor
`ward Control of Aircraft Bus DC Boost Converter, AFD
`00129, Ser. No. 08/843,428, addresses an alternate control
`of the Super capacitor discharging operation.
`The prior art is known to contain numerous arrangements
`for Supplying energy to an electrical capacitance element. It
`
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`4
`is believed, however, that this prior art does not extend to a
`practical addressing of conditions encountered in Supplying
`energy to a particular type of capacitor, the Super capacitor,
`when this Super capacitor is embodied in aircraft buS Supple
`mentation apparatus.
`SUMMARY OF THE INVENTION
`The present invention provides controllable energy cou
`pling to an energy Storage element used in aircraft energy
`Supply bus Supplemental Service.
`It is an object of the present invention therefore to provide
`an aircraft direct current to direct current coupling arrange
`ment uSable to communicate energy to a bus Supplementing
`energy Storage element.
`It is another object of the invention to provide a multiple
`time constant controlled aircraft buS Supplement energy
`coupling arrangement.
`It is another object of the invention to provide an aircraft
`bus-Sourced energy Supplement arrangement in which
`energy losses occurring during direct energy Storage in a
`capacitor element are optimally divided between passive and
`active dissipating components.
`It is another object of the invention to provide an aircraft
`energy buS Supplement Storage arrangement in which the
`major fraction of energy Storage-related losses are relegated
`to Simple and Small passive circuit elements.
`Additional objects and features of the invention will be
`understood from the following description and claims and
`the accompanying drawings.
`The present invention involves a direct current aircraft
`electrical energy distribution apparatus wherein a rotating
`dynamoelectric machine Source of direct current electrical
`energy located in a central portion of the aircraft is coupled
`to an electrical bus having an array of electrical bus
`conductors, including an electrically insulated conductor,
`connected with the dynamoelectric machine Source of direct
`current electrical energy and extending throughout the air
`craft including less central portions of the aircraft and is
`connected in energizing relationship with a plurality of
`electrical Switch-controlled rotating machine, and electrical
`heat generating electrical load devices and with aircraft
`electronic load devices all disposed throughout the aircraft.
`The invention provides a plurality of electrical energy Stor
`age devices located at Selected distributed locations disposed
`throughout the aircraft and connected locally to the array of
`electrical bus conductors at each Selected distributed
`location, the electrical energy Storage devices including a
`Super capacitor element and an energy coupling electronic
`circuit communicating a bus Voltage-Supplementing tran
`Sient flow of electrical energy from the Super capacitor to the
`electrical bus conductors. The energy coupling electronic
`circuit comprises an electrical inductance element connected
`with the Super capacitor and in Series with the flow of
`electrical energy from the Super capacitor to the electrical
`buS conductors, an electrical Switching element connected
`with the electrical inductance element and generating elec
`trical current undulations in the inductance element, and an
`output electrical Voltage regulator controller of pulse width
`time parameters in the electrical inductance element elec
`trical current undulations. The invention also provides a
`feedback controlled Super capacitor charging circuit con
`nected in energy Supply relationship between the electrical
`buS conductors and the Super capacitor element with the
`feedback controlled Super capacitor charging circuit includ
`ing first and Second Series connected controllable current
`limiting resistance elements connected in Series with a Super
`
`Petitioner Intel Corp., Ex. 1032
`IPR2023-00783
`
`

`

`S
`capacitor charging current path and with the first control
`lable current limiting resistance element. The first control
`lable current limiting resistance element comprises a MOS
`FET Switching transistor-shunted passive electrical
`resistance element and a first Zener diode referenced Super
`capacitor Voltage responsive Saturating operational amplifier
`binary driving circuitry connected to the MOSFET switch
`ing transistor. The Second controllable current limiting resis
`tance element comprises a charging current-conducting
`MOSFET analog transistor and second Zener diode refer
`enced Super capacitor Voltage responsive operational ampli
`fier analog driving circuitry connected to the MOSFET
`analog transistor. The Switching MOSFET transistor shunted
`passive electrical resistance element comprises an electrical
`resistance element having electrical energy dissipation capa
`bility significantly greater than that of the charging current
`conducting MOSFET analog transistor.
`
`15
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 shows a representative aircraft energy distribution
`bus with bus loads and bus Supplementing apparatus which
`may incorporate the present invention.
`FIG. 2a Shows a block diagram of a Super capacitor
`inclusive aircraft bus Supplement apparatus under one bus
`operating condition.
`FIG. 2b shows a block diagram of a Super capacitor
`inclusive aircraft bus Supplement apparatus under a Second
`bus operating condition.
`FIG.3 shows a Super capacitor element charging arrange
`ment according to the present invention.
`FIG. 4a shows a first operating waveform for the FIG. 3
`circuit.
`FIG. 4b shows another operating waveform for the FIG.
`3 circuit.
`FIG. 4c shows another operating waveform for the FIG.
`3 circuit.
`FIG. 4d shows another operating waveform for the FIG.
`3 circuit.
`FIG. 4e shows another operating waveform for the FIG.
`3 circuit.
`FIG. 4f shows another operating waveform for the FIG. 3
`circuit.
`FIG. 4g shows another operating waveform for the FIG.
`3 circuit.
`FIG. 5 shows an alternate and simplified arrangement of
`the FIG. 3 Super capacitor element charging arrangement.
`FIG. 6 shows another alternate arrangement of the present
`invention.
`FIG. 7a shows an equivalent circuits of the present
`invention for a first of three operating time intervals.
`FIG.7b shows an equivalent circuit of the present inven
`tion for a Second of three operating time intervals.
`FIG. 7c shows an equivalent circuit of the present inven
`tion for a third of three operating time intervals.
`
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`DETAILED DESCRIPTION
`Power losses in Super capacitor chargers can be much
`higher than those in conventional battery chargers. This is
`because the Voltage of the charger for a conventional battery
`is normally only slightly greater than that of the battery and
`the Voltage difference between the input and the output of
`the charger is therefore relatively Small-Since the conven
`tional battery has a generally fixed terminal Voltage-at least
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`5,914,542
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`once an initial forming charge or a charge from the “Stone
`dead” condition has occurred. On the other hand, the Voltage
`of a Super capacitor as used in the presently contemplated
`aircraft bus Supplementing Service may fall to Zero fre
`quently during a use cycle. Indeed the greatest Volumetric
`and weight efficiency for a bus Supplementing arrangement
`according to the present invention occurs when the Super
`capacitor is called upon to operate between terminal Volt
`ages of Zero and maximum rated capacitor Voltage-Since
`this change of Voltage represents the largest quantity of
`Stored energy a given Super capacitor of a given weight and
`Size and Voltage capability can provide.
`Because of this wide range of Super capacitor operating
`Voltage, a Voltage which may be identified as V, the charger
`for a Super capacitor must be capable of operating over a
`wide range of charger input to charger output Voltage
`difference, and also operate with a charging current capa
`bility which will meet System time requirements for recharg
`ing duration of the Super capacitor. In essence, these oper
`ating constraints require that Something in the Super
`capacitor charger, the charger's regulator circuit, be capable
`of dissipating the large Voltage difference between a fully
`discharged Super capacitor while passing the rated charging
`current (or an even greater initial charge current). This
`reasoning assumes a waveform chopping regulator is
`excluded for reasons involving electrical noise or other
`reasons. Therefore, the Super capacitor charger regulator
`must be capable of operating under frequent conditions of
`high power dissipation, dissipation of maximum Super
`capacitor Voltage at a current equaling the maximum attain
`able charging current. While this maximum condition miti
`gates with increasing Super capacitor Voltage in each charg
`ing cycle, the power loss in as large as the charger Voltage
`multiplied by the peak charging current during frequent
`intervals of time, i.e., when use of the Super capacitor bus
`voltage Supplementation is great (e.g., during intervals of
`frequent or long term and large magnitude transient loading
`of the aircraft bus). Hence, the power loss in a Super
`capacitor charger can be high. The present invention pro
`vides a reliable and Simple regulator arrangement which is
`capable of this high power loSS operation for any imposed
`operating condition.
`FIG. 1 in the drawings shows an aircraft electrical energy
`distribution System in which a Super capacitor charging
`apparatus according to the present invention may be used. In
`the FIG. 1 apparatus an aircraft 110 of the tactical or fighter
`type is shown to be provided with a direct current energy
`Supply bus 126 capable of conveying electrical energy
`between a plurality of energy Sourcing, Storing and using
`devices distributed throughout the aircraft 110. The bus 126
`may represent a plurality of electrically insulated conductors
`or a single electrically insulated conductor operating by way
`of a common ground path inclusive of the framework, skin
`metal and other parts of the aircraft 110. Some aircraft use
`buses generally of the type represented at 126 for distribut
`ing alternating current energy, often multiple phased alter
`nating current energy of Some few hundred volts electrical
`potential, while other aircraft, particularly currently active
`and older aircraft employ a lower Voltage direct current bus
`often of some 28 volts direct current potential.
`Connected to the energy supply bus 126 in FIG. 1 are a
`plurality of devices which cause the flow of electrical
`current in the bus conductors. These devices include an
`electrical generator or alternator and rectifier array which are
`represented at 104 in FIG. 1 and an electrical battery
`represented at 128 in FIG. 1; these devices act as sources of
`the electrical energy distributed by the energy Supply bus
`
`Petitioner Intel Corp., Ex. 1032
`IPR2023-00783
`
`

`

`5,914,542
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`126. The battery 128 in FIG. 1 of course serves as a
`temporary repository for electrical energy which originates
`in the generator/alternator 104 or from ground based energy
`Sources during Some phases of aircraft operation. Electrical
`energy consuming devices represented in the FIG. 1 drawing
`include the aircraft wing flap positioning motorS 106 and
`108 and the electronic circuit devices 112 and 124 which are
`often mounted in remote locations of the aircraft 110-in
`Such regions as the illustrated nose and tail recesses. Elec
`trical resistance loads in the form of lamps and heating
`elements within the aircraft are also frequently encountered
`as bus loads. The FIG. 1 illustrated loads are intended to
`represent other motor and inductive element-inclusive loads
`and a variety of electronic loads which appear in modern day
`aircraft. The electronic circuit device 112 and electronic
`circuit device 124 loads, for examples, may be considered as
`typically representing a radar System and an avionics com
`puter System.
`The physical length of the energy Supply bus 126 repre
`Sented in FIG. 1, particularly the longer length portions of
`this bus as indicated at 129, inevitably introduces electrical
`resistance and electrical inductance components of electrical
`impedance into the aircraft's bus circuit. These components
`of course add to the impedance components already present
`in the generator/alternator 104 and the battery 128 to provide
`an effective bus impedance that is usually of Some low but
`certainly not Zero value. This effective impedance is of
`course greatest at remote locations of the buS Such as in the
`locations occupied by the electronic circuit devices 112 and
`124. This impedance although lower in central portions of
`the aircraft is nevertheless usually of Sufficient magnitude
`even there to provide transient and Steady State Voltage drops
`on the bus in response to the heavy current demands of loads
`such as the motors 106 and 108 or in response to what is
`usually the greatest load imposed on an aircraft bus, i.e.,
`current flow to the propulsion engine Starting motor. (Most
`commercial aircraft even when energized by a large ground
`power unit incur noticeable cabin light dimming with engine
`Starter energization.) Some electronic loads Such as a high
`energy laser or high energy radio frequency transmitter can
`also impose Severe and short or long duration transient
`loading on a bus of the type shown at 126.
`It is of course the overall intent of the present and the
`other two above identified patent documents in the present
`Series to minimize the effects of these non Zero bus
`impedances, i.e., to limit the transient and to Some degree the
`Steady State Voltage changes experienced at various points
`along the energy Supply bus 126. Although these Voltage
`changes are not usually significant with respect to operation
`of electromechanical devices Such as the motors 106 and
`108 or heating loads, Such Voltage changes can be quite a
`different matter to the typical electronic Systems represented
`by the devices 112 and 124. In some such loads system
`energy Supply transients can become coupled into low level
`Signal apparatus, provide false Signal data, alter latched or
`unlatched conditions and even result in component part
`failures. Practicality and Such factors as weight and cost
`considerations however limit the degree to which Such
`electronic Systems can be separately energized from elec
`tromechanical loads in the environment of an aircraft.
`Through the addition of energy Storing elements located
`close to heavy electromechanical loads and close to Sensitive
`loads Such as the electronic circuit devices 112 and 124 it is
`found that many of the harmful Voltage transients encoun
`tered on an aircraft bus can be either eliminated or reduced
`in magnitude or slowed in onset (i.e., high frequency energy
`content attenuated) to the point of reducing their effect on
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`45
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`50
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`55
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`60
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`65
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`Sensitive loads. These elimination, reducing and slowing
`effects may, for example, Significantly reduce the electro
`magnetic coupling of Such transients to Sensitive internal
`components of the electronic circuit device 112 and 124 or
`alternately bring the correction of Such transients within the
`capability of power Supply regulators usually incorporated
`in devices Such as these. The concepts of the present
`invention also extend to a Supplying of aircraft energy
`during brief periods of Source interruption or need for
`emergency power Sourcing Since these conditions are essen
`tially quantative extensions of the contemplated transient
`conditions, additional discussion of this capability appears
`in the above incorporated by reference Feedforward Control
`of Aircraft Bus DC Boost Converter', AFD 00129 Ser. No.
`08/843,428, patent application.
`In the present Series of patent documents, this correction
`of transients on the energy Supply buS 126 is based on the
`energy Storage capability of the large capacitors which have
`become known as Super capacitors. This correction is based
`not on the low electrical impedance Such capacitors may
`offer at their terminals but on the energy Storage ability Such
`capacitors can provide when operated over relatively large
`Swings of terminal voltage. (Use of the former capacitor low
`impedance characteristic results in Volumetric and weight
`efficiencies which are deemed too low for aircraft use Since
`much of the Super capacitors Voltage capability is wasted in
`Storing energy that is never accessed in this application, i.e.,
`in Coulombs of energy vested in capacitor Voltage lower
`than that which can be tolerated on the energy Supply bus
`126. Moreover, the Super capacitor element may not provide
`the lowest available impedance for Such a capacitor.) In the
`present of these patent documents one aspect of or one
`arrangement for communicating electrical energy from the
`buS being improved upon to the Super capacitor element for
`Storage and later bus transient-reduction use is addressed. In
`the FIG. 1 drawing the Super capacitor inclusive energy
`Storing elements which are located close to heavy electro
`mechanical loads and close to Sensitive loads are indicated
`at 116, 118, 120 and 122.
`By way of additional comparison of the Super capacitor
`with other energy Storage angements, battery charging has
`been indicated above to be commonly accomplished through
`a linear or Class A amplifier configured Voltage regulator. In
`general, the power loSS in Such battery charger linear regu
`lators i