Super capacitor charging

• US 5,914,542 A
• Filed: 04/15/1997
• Issued: 06/22/1999
• Est. Priority Date: 04/15/1997
• Status: Expired due to Fees

• Current Assignee: United States Air Force
• Original Assignee: United States Of America As Represented By The Secretary Of The Air Force
• Inventors: Jordan, Brett A., Nguyen, Bick T., Kazimierczuk, Marian K., Weimer, Joseph A.
• Primary Examiner(s): Elms, Richard T.
• Assistant Examiner(s): KAPLAN, JONATHAN STUART
• Application Number:
  US08/843,406
• Time in Patent Office: 798 Days
• Field of Search: 307/43, 307/44, 307/45, 307/46, 307/64, 307/65, 307/66, 307/70, 307/80, 307/82, 307/84, 307/85, 307/86, 307/87, 307/18, 307/23, 323/222, 323/223, 323/224, 323/282-285
• US Class Current: 307/125
• CPC Class Codes: B64D 2221/00 Electric power distribution systems onboard aircraft
• CPC Class Codes: H02J 2310/44 for aircrafts
• CPC Class Codes: H02J 7/345 using capacitors as storage or buffering devices
• CPC Class Codes: Y02T 50/50 On board measures aiming to increase energy efficiency

Abstract

An aircraft electrical energy supply bus supplementing arrangement based on large capacitor or super capacitor storage of electrical energy for bus supplementation. Supplying 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 time constant apparatus energy losses.

Claims

1. Direct current aircraft electrical energy distribution apparatus comprising the combination of:

a source of direct current electrical energy located in a central portion of said aircraft;

an electrical bus having an array of electrical bus conductors, including an electrically insulated conductor, connected with said source of direct current electrical energy, extending throughout said aircraft including less central portions of said aircraft, and connected in energizing relationship with a plurality of aircraft electrical load devices disposed throughout said aircraft;

a plurality of electrical energy storage devices located at selected distributed locations disposed throughout said aircraft and connected locally to said array of electrical bus conductors at each said selected distributed location, said electrical energy storage devices including a super capacitor element and an energy coupling electronic circuit communicating a transient flow of electrical energy from said super capacitor to said electrical bus conductors;

said energy coupling electronic circuit including electrical switch element inclusive electrical voltage changing circuits disposed in an energy flow path intermediate said super capacitor element and said electrical bus conductors, said electrical switch element being electronic voltage regulator controlled;

a feedback controlled charging circuit connected in capacitor recharge energy supply relationship between said electrical bus conductors and said super capacitor element, said charging circuit including first and second selectable series connected and output voltage controlled charge current-limiting energy dissipating elements.

2. The direct current aircraft electrical energy distribution apparatus of claim 1 wherein said feedback controlled charging circuit includes first and second series connected controllable current limiting resistance elements connected in series with a super capacitor charging current path.

3. The direct current aircraft electrical energy distribution apparatus of claim 2 wherein said first controllable current limiting resistance element is comprised of a switching transistor shunted electrical resistance element and super capacitor voltage responsive binary driving circuitry connected to said switching transistor.

4. The direct current aircraft electrical energy distribution apparatus of claim 3 wherein said second controllable current limiting resistance element includes a charging current-conducting analog transistor and super capacitor voltage responsive analog driving circuitry connected to said analog transistor.

5. The direct current aircraft electrical energy distribution apparatus of claim 4 wherein said first current limiting resistance element is a passive electrical resistance element having electrical energy dissipation capability significantly greater than that of said charging current-conducting analog transistor.

6. The direct current aircraft electrical energy distribution apparatus of claim 5 wherein said super capacitor voltage responsive binary driving circuitry, said super capacitor voltage responsive analog driving circuitry, and said first current limiting resistance element include electrical sizes selected to achieve greatest super capacitor complete-charging energy dissipation in said first current limiting passive electrical resistance element.

7. The direct current aircraft electrical energy distribution apparatus of claim 6 wherein said super capacitor voltage responsive binary driving circuitry, said super capacitor voltage responsive analog driving circuitry, and said first current limiting resistance element include electrical sizes achieving in excess of one-half of said super capacitor complete-charging energy flow through said first current limiting passive electrical resistance element.

8. The direct current aircraft electrical energy distribution apparatus of claim 6 wherein said aircraft electrical bus has an operating potential of 28 volts direct current, said super capacitor voltage responsive binary driving circuitry has an operating voltage threshold of 20 volts direct current and said super capacitor voltage responsive analog driving circuitry has a soft operating threshold centered about a super capacitor direct current voltage of 20 volts.

9. The direct current aircraft electrical energy distribution apparatus of claim 4 further including means for enabling dissipation in said first controllable current limiting resistance element in response to a low super capacitor terminal voltage and means for shunting disablement of dissipation in said first controllable current limiting resistance element in response to a selected greater super capacitor terminal voltage.

10. Direct current aircraft electrical energy distribution apparatus comprising the combination of:

a rotating dynamoelectric machine source of direct current electrical energy located in a central portion of said aircraft;

an electrical bus having an array of electrical bus conductors, including an electrically insulated conductor, connected with said dynamoelectric machine source of direct current electrical energy, extending throughout said aircraft including less central portions of said aircraft, and 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 said aircraft;

a plurality of electrical energy storage devices located at selected distributed locations disposed throughout said aircraft and connected locally to said array of electrical bus conductors at each said selected distributed location, said electrical energy storage devices including a super capacitor element and an energy coupling electronic circuit communicating a bus voltage-supplementing transient flow of electrical energy from said super capacitor to said electrical bus conductors;

said energy coupling electronic circuit comprising an electrical inductance element connected with said super capacitor and in series with said flow of electrical energy from said super capacitor to said electrical bus conductors, an electrical switching element connected with said electrical inductance element and generating electrical current undulations in said inductance element, and an output electrical voltage regulator controller of pulse width time parameters in said electrical inductance element electrical current undulations;

a feedback controlled super capacitor charging circuit connected in energy supply relationship between said electrical bus conductors and said super capacitor element;

said feedback controlled super capacitor charging circuit including first and second series connected controllable current limiting resistance elements connected in series with a super capacitor charging current path;

said first controllable current limiting resistance element comprising a MOSFET switching transistor shunted passive electrical resistance element and first zener diode referenced super capacitor voltage responsive saturating operational amplifier binary driving circuitry connected to said MOSFET switching transistor;

said second controllable current limiting resistance element comprising a charging current-conducting MOSFET analog transistor and second zener diode referenced super capacitor voltage responsive operational amplifier analog driving circuitry connected to said MOSFET analog transistor;

said switching MOSFET transistor shunted passive electrical resistance element comprising an electrical resistance element having electrical energy dissipation capability significantly greater than that of said charging current-conducting MOSFET analog transistor.

11. The method of supplying direct current electrical energy of reduced interruption and transient voltage content to electrical loads located along an energy source-fed aircraft energy supply bus, said method comprising the steps of:

supplementing electrical energy supplied from said source via said aircraft energy supply bus to said electrical loads with electrical energy previously removed from said bus at a controlled removal rate and held in storage more proximate said electrical loads than said bus energy source;

storing said previously removed electrical energy in an electrical super capacitor storage element disposed in said more proximate location;

operating said electrical capacitance storage element over a change of voltage range characteristic of removing and replacing at least one half of energy stored in said electrical capacitance storage element, a range exceeding electrical voltage transient amplitudes acceptable on said aircraft energy supply bus;

coupling energy from said electrical capacitance storage element to said energy supply bus of lesser voltage transient range via an electronic switching circuit-modulated electrical inductive element of variable coupling ratio, an element also located more proximate said electrical transient-generating load;

supplying capacitor charging energy from said bus to said electrical capacitance storage element at a first time constant-characterized rate during a low capacitor voltage initial portion of a capacitor charging cycle;

adding capacitor charging energy to said electrical capacitance storage element from said bus at a second time constant-characterized rate during a higher capacitor voltage later portion of said capacitor charging cycle;

regulating a final steady state highest capacitor voltage at said second time constantcharacterized charging rate during intervals between capacitor charging and bus supplementing events.

12. The method of supplying direct current electrical energy of claim 11 further including the step of controlling said first time constant-characterized rate using series-connected first and second electrical resistance elements.

13. The method of supplying direct current electrical energy of claim 12 further including the step of shunting said first electrical resistance element to achieve said second time constant-characterized capacitor charging rate.

14. The method of supplying direct current electrical energy of claim 13 wherein said step of shunting said first electrical resistance element to achieve said second time constantcharacterized capacitor charging rate includes the step of driving a transistor shunting said first electrical resistance element into a conducting state.

15. The method of supplying direct current electrical energy of claim 14 further including the step of controlling said first time constant-characterized rate and said second electrical resistance element magnitude via changing conductivity of a transistor element.

16. The method of supplying direct current electrical energy of claim 15 further including the step of changing said conductivity of a transistor element by changing a carrier flow quantity in a field-effect transistor channel region.

17. The method of supplying direct current electrical energy of claim 15 further including the step of changing said conductivity of a transistor element by changing a carrier flow quantity in a bipolar transistor base region.

18. The method of energizing a combination of electrical transient-generating and transient-intolerant direct current electrical loads located at electrical inductance and electrical resistance source-decoupled points along an aircraft energy supply bus with electrical energy of attenuated electrical transient voltage variation, said method comprising the steps of:

supplementing electrical energy supplied via said aircraft energy supply bus to said electrical inductance and electrical resistance source-decoupled electrical transient-generating load with additional electrical energy previously removed from said bus at a selected slow and controlled low current removal rate and held in storage adjacent one of said electrical transientgenerating load and said transient-intolerant electrical loads;

storing said previously removed electrical energy in an electrical super capacitance storage element located adjacent one of said electrical transient-generating load and said transient-intolerant electrical load;

operating said electrical capacitance storage element over a super capacitance change of voltage range capable of exchanging at least one-half of an energy quantity storable in said electrical super capacitance storage element, a range exceeding electrical voltage transient amplitudes acceptable at said transient-intolerant electrical load;

coupling energy from said electrical super capacitance storage element to said energy supply bus with an electronic switching circuit-modulated electrical inductive element of controllable coupling characteristics, an element also located adjacent one of said electrical transient-generating load and said transient-intolerant electrical load;

controlling said electrical capacitance storage element to aircraft energy supply bus controllable coupling characteristics according to an aircraft energy supply bus transientattenuating open loop control algorithm, an algorithm determinative of pulse width time parameters of said electrical inductive element modulation;

said open loop control algorithm generating longer inductive element energy-increasing closure times of a shunt connected transistor switch in response to transients of larger energy demand from said aircraft energy supply bus;

disconnecting said inductive element from said aircraft energy supply bus during said inductive element energy-increasing closure times of said shunt connected transistor switch in an operating cycle of said electronic switching circuit modulation.

19. The method of energizing a combination of electrical transient-generating and transient-intolerant direct current electrical loads of claim 18 wherein said step of storing said previously removed electrical energy in an electrical super capacitance storage element includes the step of supplying at least one-half of an electrical energy quantity storable in said super capacitor element through a passive electrical resistance element connecting said super capacitor element with said aircraft electrical energy supply bus.

20. The method of energizing a combination of electrical transient-generating and transient-intolerant direct current electrical loads of claim 18 wherein said step of storing said previously removed electrical energy in an electrical super capacitance storage element includes the step of supplying an initial super capacitor charge portion from said aircraft energy supply bus at a first time constant rate, a second super capacitor charge portion from said aircraft energy supply bus at a second time constant rate, and a third super capacitor charge portion from said aircraft energy supply bus at a third super capacitor leakage current-compensating time constant rate.