Voltage sensor for detecting cell voltages
First Claim
1. A voltage sensor for sensing the voltage across each of a plurality of series-connected cells, said voltage sensor comprising:
- a plurality of differential amplifiers, each one having a pair of input terminals coupled across a corresponding one of said plurality of cells and an output terminal; and
a network coupled to said output terminals of said plurality of differential amplifiers for providing a high cell voltage signal proportional to a relative highest voltage across one of said plurality of cells and a low cell voltage signal proportional to a relative lowest voltage across one of said plurality of cells.
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Accused Products
Abstract
A battery charger/monitor circuit for charging and/or monitoring a plurality of series-connected cells, including a voltage sensor for sensing the voltage across each of the cells to provide a high cell voltage signal proportional to the highest voltage across any of the cells and a low cell voltage signal proportional to the lowest voltage across any of the cells. The circuit is operable in a monitor mode or a charge mode. In the monitor mode, the cells are disconnected from a load if the low cell voltage signal decreases to a first predetermined level. The circuit includes a controller which provides a control signal in response to the high cell voltage signal, the low cell voltage signal and a current sense signal, for controlling the charging of the cells. In the charge mode, the cells receive a constant charge current until the high cell voltage signal reaches a second predetermined level, after which the voltage across the cell charged to the highest voltage is held substantially constant, causing the charge current to be reduced.
376 Citations
9 Claims
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1. A voltage sensor for sensing the voltage across each of a plurality of series-connected cells, said voltage sensor comprising:
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a plurality of differential amplifiers, each one having a pair of input terminals coupled across a corresponding one of said plurality of cells and an output terminal; and a network coupled to said output terminals of said plurality of differential amplifiers for providing a high cell voltage signal proportional to a relative highest voltage across one of said plurality of cells and a low cell voltage signal proportional to a relative lowest voltage across one of said plurality of cells. - View Dependent Claims (5, 6, 9)
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2. A voltage sensor for sensing the voltage across each of a plurality of series-connected cells, said voltage sensor comprising:
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a plurality of differential amplifiers, each one having a pair of input terminals coupled across a corresponding one of said plurality of cells and an output terminal; and a network coupled to said output terminals of said plurality of differential amplifiers for providing a high cell voltage signal proportional to a highest voltage across one of said plurality of cells and a low cell voltage signal proportional to a lowest voltage across one of said plurality of cells, wherein said network comprises; a first plurality of diodes, each one having an anode connected to said output terminal of a corresponding one of said plurality of differential amplifiers and a cathode connected to a high voltage circuit node at a voltage proportional to one diode drop below said high cell voltage signal; and a second plurality of diodes, each one having a cathode connected to said output terminal of a corresponding one of said plurality of differential amplifiers and an anode connected to a low voltage circuit node at a voltage proportional to one diode drop above said low cell voltage signal. - View Dependent Claims (3)
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4. A voltage sensor for sensing the voltage across each of a plurality of series-connected cells, said voltage sensor comprising:
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a plurality of differential amplifiers, each one having a pair of input terminals coupled across a corresponding one of said plurality of cells and an output terminal; and a network coupled to said output terminals of said plurality of differential amplifiers for providing a high cell voltage signal proportional to a highest voltage across one of said plurality of cells and a low cell voltage signal proportional to a lowest voltage across one of said plurality of cells, wherein said network comprises; a first plurality of diode compensation networks, each one comprising an operational amplifier and a diode connected in feedback relationship with said operational amplifier and having a cathode at which said high cell voltage signal is provided; and a second plurality of diode compensation networks, each one comprising an operational amplifier and a diode connected in feedback relationship with said operational amplifier and having an anode at which said low cell voltage signal is provided.
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7. A method of sensing the voltage across a plurality of series-connected cells comprising the steps of:
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sensing the voltage across each of said plurality of cells; providing a high cell voltage signal proportional to a voltage sensed across one of at least two of said plurality of cells having the highest voltage thereacross, and providing a low cell voltage signal proportional to a voltage sensed across one of at least two of said plurality of cells having the lowest voltage thereacross.
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8. A method of sensing the voltage across a plurality of series-connected cells comprising the steps of:
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sensing the voltage across each of said plurality of cells; providing a high cell voltage signal proportional to a highest voltage sensed across one of said plurality of cells; and providing a low cell voltage signal proportional to a lowest voltage sensed across one of said plurality of cells, wherein said voltage sensing step further comprises the steps of; connecting input terminals of a differential amplifier across each of said plurality of cells; interconnecting output terminals of said differential amplifiers with a first plurality of diodes to provide said high cell voltage signal, said first plurality of diodes having anodes connected to said output terminal of a respective differential amplifier; and interconnecting said output terminals of said differential amplifiers with a second plurality of diodes to provide said low cell voltage signal, said second plurality of diodes having cathodes connected to said output terminal of a respective differential amplifier.
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Specification