Electronic circuit for measuring series connected electrochemical cell voltages
First Claim
1. A voltage transfer circuit for measuring voltage signals in an energy storage device, comprising:
- a plurality of battery segments forming the energy storage device;
an amplifier circuit connected across one of the battery segments for converting a differential voltage to a reference current;
a sense resistor associated with the amplifier circuit to convert the reference current to a voltage signal which is proportional to the voltage across the battery segment; and
a voltage measurement node associated with the sensing resistor for measuring the voltage signal.
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Abstract
An electronic circuit for measuring voltage signals in an energy storage device is disclosed. The circuit includes a plurality of battery segments forming the energy storage device. An amplifier circuit is connected across one of the battery segments for converting a differential voltage to a reference current. A sense resistor is associated with the amplifier circuit to convert the reference current to a voltage signal which is proportional to the voltage across the battery segment. A voltage measurement node associated with the sensing resistor may be used for measuring the voltage signal. In one embodiment of the invention, a multiplexing and sampling circuit provides digitized voltage samples to a processor. The voltage level of each cell within the battery pack can then be monitored by the processor.
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Citations
18 Claims
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1. A voltage transfer circuit for measuring voltage signals in an energy storage device, comprising:
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a plurality of battery segments forming the energy storage device;
an amplifier circuit connected across one of the battery segments for converting a differential voltage to a reference current;
a sense resistor associated with the amplifier circuit to convert the reference current to a voltage signal which is proportional to the voltage across the battery segment; and
a voltage measurement node associated with the sensing resistor for measuring the voltage signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
the on-off control circuitry including an optical switch to disconnect the amplifier power pin from the energy storage device.
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7. The voltage transfer circuit of claim 5 wherein the on-off control circuitry includes a control switch in series with the sense resistor to limit leakage currents.
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8. The voltage transfer circuit of claim 1 wherein the voltage signal is sampled by an A/D converter for monitoring by a processor.
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9. The voltage transfer circuit of claim 2 wherein there is at least one more battery segment than amplifier circuit, the at least one more battery segment being coupled to a negative end of the energy storage device.
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10. A voltage transfer circuit for measuring voltage signals in an energy storage device, comprising:
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a plurality of energy storage segments forming the energy storage device, an amplifier circuit coupled across one of the energy storage segments for converting a differential voltage to a reference current;
a sense resistor associated with the amplifier circuit to convert the reference current to a voltage signal which is proportional to the voltage across the energy storage segment;
a voltage measurement node associated with the sensing resistor for measuring the voltage signal; and
a voltage divider circuit coupled across a negative terminal energy storage segment to measure a segment voltage, the negative terminal energy storage segment being coupled to a negative end of the energy storage device. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
the negative terminal energy storage segment provides an input offset voltage for one of the amplifier circuits.
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14. The voltage transfer circuit of claim 10 wherein the amplifier includes a buffer transistor to regulate the reference current.
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15. The voltage transfer circuit of claim 10 further including on-off control circuitry to minimize off mode leakage current.
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16. The voltage transfer circuit of claim 15 wherein the amplifier circuit has a power pin;
the on-off control circuitry including an optical switch to disconnect the amplifier power pin from the energy storage device.
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17. The voltage transfer circuit of claim 15 wherein the on-off control circuitry includes a control switch in series with the sense resistor to limit leakage currents.
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18. A voltage transfer circuit for measuring voltage signals in an energy storage device, the energy storage device including a plurality of energy storage segments, comprising:
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an amplifier circuit coupled across one of the energy storage segments for converting a differential voltage to a reference current, the amplifier circuit including a buffer switch to regulate the reference current;
a sense resistor coupled to the buffer transistor to convert the reference current to a voltage signal which is proportional to the voltage across the energy storage segment;
a voltage measurement node associated with the sensing resistor for measuring the voltage signal;
a voltage divider circuit coupled across another of the energy storage segments to measure a segment voltage; and
on-off control circuitry coupled to the amplifier circuit to minimize off mode leakage current.
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Specification