US4575679A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic load shed control for spacecraft power system
Assignee: Lockheed Martin Corp
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Filing: 1983-05-10
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Granted: 1986-03-11
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Expires: 2003-05-10
Abstract
Abstract An automatic load shed control for a spacecraft power system employs a selectable one of a plurality of charging gains to approximate a state of charge in a secondary battery system. An ampere hour meter is initialized when the battery system is known to be fully charged and the inefficiencies of the charging system are lumped into a charging gain parameter. An output of the ampere hour meter is compared with a load shed threshold to determine the time for load shedding. The charging gain can be remotely changed as required to a value which causes the output of the ampere hour meter to track the true state of charge of the battery system closely enough for system satisfactory operation of load shedding. The charging gain may be a constant or may be a variable in dependence on the state of charge of the battery system. Charge which is delivered at a rate below a predetermined threshold is ignored by the ampere hour meter.
Inventors
- 👤 Albert S. Chung
- 👤 Carl F. Mazzocco
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 06:15
CPC Classifications
H; H02; H02J; H02J7/00; H02J7/34; H02J7/35; G; G01; G01R; G01R19/00; G01R19/165; G01R19/16533; G01R19/16538; G01R19/16542; G01R31/00; G01R31/36; G01R31/382; G01R31/3842; H02J1/00; H02J1/14; H02J1/16; H02J7/90; H02J7/94; Y; Y10; Y10S; Y10S323/00; Y10S323/906
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
152 words
Apparatus for calculating a state of charge of batteries in a battery system of the type having at least one of a variable source capacity and a variable load, comprising: means for measuring a charging current and a discharging current of said batteries; means having a first gain for accumulating a first value related to said charging current; means having a second gain for calculating a second value related to said discharging current; means for differencing said first and second values to produce a calculated state of charge of said battery system; means for initializing said means for differencing to a known value of said state of charge of said battery system; and means for selecting a value of at least one of said first and second gains effective to produce an output of said means for differencing which is an approximation of a variable state of charge of said battery system.
Claim 2
Dependent Claim
152 words
Apparatus for calculating a state of charge of batteries in a battery system of the type having at least one of a variable source capacity and a variable load, comprising: means for measuring a charging current and a discharging current of said batteries; means having a first gain for accumulating a first value related to said charging current; means having a second gain for calculating a second value related to said discharging current; means for differencing said first and second values to produce a calculated state of charge of said battery system; means for initializing said means for differencing to a known value of said state of charge of said battery system; and means for selecting a value of at least one of said first and second gains effective to produce an output of said means for differencing which is an approximation of a variable state of charge of said battery system.
Claim 3
Dependent Claim
25 words
Apparatus for calculating a state of charge of a battery system according to claim 1 wherein said known value is a state of full charge.
Claim 4
Dependent Claim
46 words
Apparatus for calculating a state of charge of a battery system according to claim 1 wherein said battery system includes at least first and second batteries and said known value is a state of full charge in at least one of said first and second batteries.
Claim 5
Dependent Claim
43 words
Apparatus for calculating a state of charge of a battery system according to claim 3 wherein said known value is a state of full charge in one of said first and second batteries and a state of full discharge in the other thereof.
Claim 6
Dependent Claim
35 words
Apparatus for calculating a state of charge of a battery system according to claim 3 wherein said known value is a state of full charge in all of said at least first and second batteries.
Claim 7
Dependent Claim
38 words
Apparatus for calculating a state of charge of a battery system according to claim 1 wherein said means for selecting a value includes means for selecting one of a family of charging efficiency curves of said battery system.
Claim 8
Dependent Claim
37 words
Apparatus for calculating a state of charge of a battery system according to claim 6 further comprising means for controlling said first gain according to said charging efficiency curve and said output of said means for differencing.
Claim 9
Dependent Claim
29 words
Apparatus for calculating a state of charge of a battery system according to claim 6 wherein said means for selecting a value includes remote means for selecting a value.
Claim 10
Dependent Claim
23 words
Apparatus for calculating a state of charge of a battery system according to claim 8 wherein said remote means includes a telemetry system.
Claim 11
Dependent Claim
37 words
Apparatus for calculating a state of charge of a battery system according to claim 1 wherein said means for selecting a value includes means for selecting one of a plurality of fixed values of said first gain.
Claim 12
Dependent Claim
29 words
Apparatus for calculating a state of charge of a battery system according to claim 10 wherein said means for selecting a value includes remote means for selecting said value.
Claim 13
Dependent Claim
26 words
Apparatus for calculating a state of charge of a battery system according to claim 11 wherein said means for selecting a value includes a telemetry system.
Claim 14
Dependent Claim
102 words
Apparatus for calculating a state of charge of a battery system according to claim 1 wherein said variable load includes an interruptible load and an uninterruptible load, said apparatus further comprises a load shed relay effective for shedding said interruptible load, a threshold generator effective to generate a threshold voltage related to a condition of said battery system at which said shedding should occur, and a comparator responsive to said threshold voltage and said approximation for producing a load shed command signal, said load shed command signal being effective to actuate said load shed relay and to thereby shed said interruptible load.
Claim 15
Dependent Claim
50 words
Apparatus for calculating a state of charge of a battery system according to claim 13 wherein said battery system includes at least first and second batteries and said threshold generator is responsive to a number of said at least first and second batteries which are active in said battery system.
Claim 16
Dependent Claim
54 words
Apparatus for calculating a state of charge of a battery system according to claim 14 wherein said number of said at least first and second batteries which are active includes all of said at least first and second batteries and said known value is a full state of charge in all of said batteries.
Claim 17
Dependent Claim
69 words
Apparatus for calculating a state of charge of a battery system according to claim 14 wherein said number of said at least first and second batteries which are active includes all of said at least first and second batteries and said known value is a full state of charge in at least one of said batteries and a full state of discharge in at least another of said batteries.
Claim 18
Dependent Claim
52 words
Apparatus for calculating a state of charge of a battery system according to claim 1 wherein said means having a first gain includes means for setting said first gain to zero for charging currents less than a predetermined value, said predetermined value being dependent upon a number of said batteries being charged.
Claim 19
Dependent Claim
96 words
Apparatus for calculating a state of charge of a battery system according to claim 1 wherein said means for differencing includes a voltage-to-frequency converter responsive to said first and second values for producing a variable frequency, an up-down counter effective for counting up and down in response to said variable frequency, gating means responsive to said first value for applying said variable frequency to one of an up and a down input of said up-down counter and responsive to said second value for applying said variable frequency to the other of said up and down inputs.
Claim 20
Dependent Claim
38 words
Apparatus for calculating a state of charge of a battery system according to claim 18 wherein said means for differencing includes a digital-to-analog converter effective to convert a count in said up-down counter to a related analog voltage.
Claim 21
Independent Claim
137 words
A method for calculating a state of charge of batteries in a battery system of the type having at least one of a variable source capacity and a variable load, comprising: measuring a charging current and a discharging current of said batteries; calculating a first value related to said charging current at a first gain; calculating a second value related to said discharging current at a second gain; differencing said first and second values to produce a calculated state of charge of said battery system; initializing said differencing to a known value of said state of charge of said battery system; and selecting a value of at least one of said first and second gains effective to produce an output of said differencing which is an approximation of a variable state of charge of said battery system.
Claim 22
Independent Claim
137 words
A method for calculating a state of charge of batteries in a battery system of the type having at least one of a variable source capacity and a variable load, comprising: measuring a charging current and a discharging current of said batteries; calculating a first value related to said charging current at a first gain; calculating a second value related to said discharging current at a second gain; differencing said first and second values to produce a calculated state of charge of said battery system; initializing said differencing to a known value of said state of charge of said battery system; and selecting a value of at least one of said first and second gains effective to produce an output of said differencing which is an approximation of a variable state of charge of said battery system.
Claim 23
Dependent Claim
190 words
An automatic load shedding apparatus for a battery power system of the type having at least one battery and at least one of a variable source capacity and a variable load, said load including an interruptible load and an uninterruptible load, comprising: means for producing a first signal at a first gain responsive to a charging current in said battery; means for producing a second signal at a second gain responsive to a discharge current in said battery; means for differencing said first and second signal to produce a state of charge signal; means for initializing said state of charge signal to a predetermined fixed value; means for selecting at least one of said first and second gains effective for making said state of charge signal representative of a variable state of charge of said at least one battery; means for producing a load shed reference signal; means for producing a load shed command signal in response to a predetermined relationship of said state of charge signal and said load shed reference signal; and a load shed relay responsive to said load shed command signal for shedding said interruptible load.
Claim 24
Dependent Claim
190 words
An automatic load shedding apparatus for a battery power system of the type having at least one battery and at least one of a variable source capacity and a variable load, said load including an interruptible load and an uninterruptible load, comprising: means for producing a first signal at a first gain responsive to a charging current in said battery; means for producing a second signal at a second gain responsive to a discharge current in said battery; means for differencing said first and second signal to produce a state of charge signal; means for initializing said state of charge signal to a predetermined fixed value; means for selecting at least one of said first and second gains effective for making said state of charge signal representative of a variable state of charge of said at least one battery; means for producing a load shed reference signal; means for producing a load shed command signal in response to a predetermined relationship of said state of charge signal and said load shed reference signal; and a load shed relay responsive to said load shed command signal for shedding said interruptible load.
Claim 25
Dependent Claim
30 words
An automatic load shedding apparatus according to claim 21 wherein said predetermined fixed value includes a state of full charge in at least one of said at least one battery.
Claim 26
Dependent Claim
43 words
An automatic load shedding apparatus according to claim 22 wherein said at least one battery includes at least first and second batteries and said predetermined fixed value includes a full state of charge in all of said at least first and second batteries.
Claim 27
Dependent Claim
47 words
An automatic load shedding apparatus according to claim 22 wherein said at least one battery includes at least first and second batteries and said predetermined fixed value includes a full state of charge in said first battery and a state of full discharge in said second battery.
References Cited (Backward Citations)
US3600599A
Cited
US3617850A
Cited
US3740636A
Cited
US3971980A
Cited
US4194146A
Cited
US4247812A
Cited
US4307330A
Cited
US4281278A
Cited
US4376267A
Cited
US4383211A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-03-10 | 1989-09-09 | 1990-03-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-03-10 | 1993-09-09 | 1994-03-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-03-10 | 1997-09-09 | 1998-03-11 | $7700.00 | Window Closed / Lapsed |