Contactor monitor for charging stations
First Claim
1. An apparatus for monitoring a voltage drop across a contactor which has both a power input and a power output, wherein the monitoring circuit comprises:
- (a) an input sense circuit connected to said power input of said contactor, across which a voltage of at least X volts must be applied before substantial current flows;
(b) an output sense circuit connected to said power output of said contactor, across which a voltage of at least Y volts must be applied before substantial current flows, wherein voltage X is greater than voltage Y; and
(c) a sense threshold circuit which generates an electrical signal responsive to the voltage drop across said contactor, wherein said sense threshold circuit is connected to at least one of said sense circuits such that the contactor voltage drop is determined by the difference in current being conducted through said input sense circuit and said output sense circuit.
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Accused Products
Abstract
A monitoring device for sensing the voltage drop across a contactor in an electrical circuit. Voltage drop across the contactor is sensed by providing alternate current paths from either side of the contactor through a threshold sense circuit. The alternate current paths contain non-resistive voltage dropping components such that the relative amount of conduction through each path is determined largely by the voltage drop across the contactor. A signal is provided by the threshold sense circuit according to the relative currents which represents the voltage drop across the contactor. In this way, an increased voltage drop across the contacts of the contactor can be determined before dangerous amounts of heat are dissipated in high current switching circuits.
19 Citations
19 Claims
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1. An apparatus for monitoring a voltage drop across a contactor which has both a power input and a power output, wherein the monitoring circuit comprises:
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(a) an input sense circuit connected to said power input of said contactor, across which a voltage of at least X volts must be applied before substantial current flows; (b) an output sense circuit connected to said power output of said contactor, across which a voltage of at least Y volts must be applied before substantial current flows, wherein voltage X is greater than voltage Y; and (c) a sense threshold circuit which generates an electrical signal responsive to the voltage drop across said contactor, wherein said sense threshold circuit is connected to at least one of said sense circuits such that the contactor voltage drop is determined by the difference in current being conducted through said input sense circuit and said output sense circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A battery charging apparatus, comprising:
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(a) a contactor with a power input and a power output, wherein upon application of a charging voltage, the contactor is capable of conducting current between said power input and said power output, said contactor being capable of at least two conduction states; (b) an input sense circuit connected to said power input of said contactor, through which a significant current W begins flowing as the voltage across the input sense circuit rises above a predetermined threshold voltage X; (c) an output sense circuit connected to said power output of said contactor through which a significant current W begins flowing as the voltage across the output sense circuit rises above a predetermined threshold voltage Y, wherein X is greater than Y; and (d) a sense threshold circuit connected to both the input sense circuit, and the output sense circuit, and to a power return path for said charging voltage, wherein the sense threshold circuit generates an electrical signal in relation to the voltage drop across said contactor which is determined by the difference in current being conducted through said input sense circuit and said output sense circuit.
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14. A method of monitoring the voltage drop across a contactor which has both a power input and a power output, comprising the steps of:
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(a) allowing current to flow through an input sense circuit exhibiting a non-resistive voltage drop X; (b) allowing current to flow through an output sense circuit when the voltage drop across said contactor is below a predetermined threshold, wherein a non-resistive voltage drop Y is produced within said output circuit, wherein X is greater than Y; and (c) sensing the relative current flows between the input and output sense circuits within a sense threshold circuit which provides an output signal as a function of the relative current flows. - View Dependent Claims (15)
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16. An apparatus for monitoring a voltage drop across a contactor of the type having an input and an output, comprising:
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(a) an input sense circuit across which a voltage of at least X volts must be applied before substantial current flows; (b) an output sense circuit across which a voltage of at least Y volts must be applied before substantial current flows, wherein voltage X is greater than voltage Y; and (c) a sense threshold circuit connected to at least one of said sense circuits, wherein said sense threshold circuit generates an electrical signal responsive to a differential in current conducted through said input sense circuit and said output sense circuit.
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17. An apparatus for monitoring excessive resistance in a contactor having input and output contacts, comprising:
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(a) means for sensing a voltage drop across said input and output contacts; and (b) means for generating an output signal responsive to said voltage drop. - View Dependent Claims (18, 19)
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Specification