Uninterruptable power supply
First Claim
1. An uninterruptable power supply (UPS) producing a DC output coupled to a load having a controller, said power supply comprising:
- a mains-derived power converter having an AC input connected to a mains voltage, and a converter DC output;
a battery having a battery voltage;
a multiplexer having a battery input coupled to said battery voltage, a converter input coupled to said converter DC output, a battery test input, a battery active output, and a multiplexer output which is coupled to said battery input when said battery test input is asserted and said battery input exceeds a first voltage threshold, and said multiplexer output is coupled to said converter input at all other times, said battery active asserted when said multiplexer output is selecting said battery;
said load coupled to said multiplexer output, said load controller having a battery test output coupled to said multiplexer battery test input, and said load controller having a battery active input coupled to said multiplexer battery active output.
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Accused Products
Abstract
An uninterruptable power supply for use with an Internet Telephone or Internet Telephone Cable Modem comprises a power supply and a load. The power supply has an AC/DC converter for producing converter DC, and also a rechargeable battery. A DC output multiplexer selects one of such DC sources and furnishes it to the load. The multiplexer has an input control signal for switching the DC source to a battery, and an output indicator indicating when the battery is acting as the DC source. The load includes a controller which generates this test signal at times when it is useful to test the battery, and accepts the indicator signal to know when the battery is providing this current. The controller includes a test function for measuring the reserve charge of the battery by measuring the temporal voltage drop and time of this temporal voltage drop with the use of an A/D converter. Additionally, the controller measures the charge and discharge intervals of the battery. The controller includes NVRAM which stores the test state, and an internet connection for the passage of messages to and from the internet.
145 Citations
27 Claims
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1. An uninterruptable power supply (UPS) producing a DC output coupled to a load having a controller, said power supply comprising:
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a mains-derived power converter having an AC input connected to a mains voltage, and a converter DC output;
a battery having a battery voltage;
a multiplexer having a battery input coupled to said battery voltage, a converter input coupled to said converter DC output, a battery test input, a battery active output, and a multiplexer output which is coupled to said battery input when said battery test input is asserted and said battery input exceeds a first voltage threshold, and said multiplexer output is coupled to said converter input at all other times, said battery active asserted when said multiplexer output is selecting said battery;
said load coupled to said multiplexer output, said load controller having a battery test output coupled to said multiplexer battery test input, and said load controller having a battery active input coupled to said multiplexer battery active output. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
a switch having said battery input, said converter input, and said multiplexer output, said switch controlled by a select input;
said select input and said battery active output formed by gating said battery test with a comparison result formed by comparing said battery voltage to said first voltage threshold.
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5. The UPS of claim 1 wherein said load controller includes:
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said battery test output;
said battery active input;
non-volatile storage;
a first A/D converter coupled to said multiplexer DC output;
a second A/D converter coupled to a measurement of the current consumed by said load;
an optional network link to an external network.
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6. The controller of claim 1 wherein said battery test signal is BAT_TEST_L.
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7. The controller of claim 1 wherein said battery active signal is BAT_ON_L.
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8. The controller of claim 5 wherein said non-volatile storage includes a Status variable, said Status variable set to TEST at the beginning of a load test, and set to COMPLETE at the completion of a load test.
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9. The controller of claim 8 wherein said non-volatile storage includes a Test_Interval timer, said timer set to regulate the interval between testing said battery for Reserve_Capacity.
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10. The controller of claim 9 wherein said Test_Interval timer enables testing during times of minimum telephone usage according to locally stored information.
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11. The controller of claim 9 wherein said controller network link is used to send usage information to an external server, said server responding to said usage information by sending information which updates said Test_Interval timer to enable testing during times of minimum telephone usage according to information sent from a network server.
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12. The controller of claim 8 wherein said first A/D controller samples said battery voltage from a first point when said battery active is enabled until a second point.
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13. The controller of claim 12 wherein said second point is determined by a change in the slope of said voltage samples with respect to time, where said A/D controller samples are uniformly spaced in time.
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14. The controller of claim 13 wherein said second point is determined by measuring a ratio of slopes of said voltage with respect to time before said second point to the slope of said voltage with respect to time after said second point, said ratio greater than 2.
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15. The controller of claim 14 wherein the reserve charge of said battery is estimated by subtracting said battery voltage from said second point from said battery voltage at said first point and comparing this result to a battery discharge characteristic stored in said non-volatile memory.
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16. The controller of claim 14 wherein the reserve charge of said battery is estimated by subtracting said second point from said first point and comparing this result to a battery discharge characteristic stored in said non-volatile memory.
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17. The controller of claim 14 wherein the reserve charge of said battery is estimated by measuring the current drawn by said load when said battery active is asserted, computing a depth of discharge from said current measurement and said duration of discharge, and storing the number of incidences of said discharges according to said duration.
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18. The controller of claim 16 wherein said Reserve_Capacity is computed by examining said duration of discharge, said depth of discharge, and the number of said discharges at each discharge depth.
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19. A method for measuring the reserve capacity in a battery, said method comprising the steps:
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providing a trickle charge to said battery until a first point in time;
providing a load across said battery and measuring the voltage of said battery until the first derivative of voltage versus time falls to ½
or less of its initial value, such time denoting a second point in time, said difference in time between said second point in time and said first point in time forming a discharge time;
comparing said measured discharge time with a known characteristic of said discharge time versus reserve charge and producing said reserve charge.
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20. A method for measuring the reserve capacity in a battery, said method comprising the steps:
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providing a trickle charge to said battery until a first point in time;
providing a load across said battery and measuring the voltage of said battery until the first derivative of said battery voltage versus time changes to ½
or less of its initial value, such time denoting a second point in time, said second point in time having a second battery voltage, the difference between said second battery voltage and said initial battery voltage forming a discharge voltage change;
comparing said measured discharge voltage change with a known characteristic of said discharge voltage change versus reserve charge.
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21. A method for estimating the reserve capacity of a battery comprising the steps:
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initializing a non-volatile variable State to TEST;
performing a battery test on an internal battery using said measurement device as said load;
setting said variable State to COMPLETE when finished;
checking to see if said Status is TEST when said test is not being performed, and sending a replace battery message over a network link when said Status is found to be TEST.
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22. An internet telephone comprising:
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a power supply having a mains input and a dc output;
a rechargeable battery;
a multiplexer having a power supply input coupled to said dc output, a battery input coupled to said rechargeable battery, and a multiplexer output coupled to a load, said multiplexer including a battery test input for connecting said battery to said multiplexer output, said multiplexer including a battery enable output for indicating when said battery input is coupled to said multiplexer output, said multiplexer connecting said battery input to said multiplexer output only when said battery test input is active and said battery is determined to be capable of operating said load;
said load including a controller having a network link, said link sending usage patterns of said internet telephone to a remote power server, said remote power server monitoring said usage patterns of a plurality of internet telephones, and sending battery test information to each said internet telephone. - View Dependent Claims (23, 24, 25, 26, 27)
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Specification