Equalizer system and method for series connected energy storing devices
First Claim
1. A method of charging series connected thin-film electrochemical cells, comprising:
- supplying a charge current to the thin-film electrochemical cells to cause a voltage to increase in each of the series connected electrochemical cells; and
controlling, in response to the voltage of a particular series connected electrochemical cell reaching a voltage limit, the charge current through the particular electrochemical cell without interrupting the charge current supplied to other ones of the electrochemical cells.
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Accused Products
Abstract
An apparatus and method for regulating the charge voltage of a number of electrochemical cells connected in series is disclosed. Equalization circuitry is provided to control the amount of charge current supplied to individual electrochemical cells included within the series string of electrochemical cells without interrupting the flow of charge current through the series string. The equalization circuitry balances the potential of each of the electrochemical cells to within a pre-determined voltage setpoint tolerance during charging, and, if necessary, prior to initiating charging. Equalization of cell potentials may be effected toward the end of a charge cycle or throughout the charge cycle. Overcharge protection is also provided for each of the electrochemical cells coupled to the series connection. During a discharge mode of operation in accordance with one embodiment, the equalization circuitry is substantially non-conductive with respect to the flow of discharge current from the series string of electrochemical cells. In accordance with another embodiment, equalization of the series string of cells is effected during a discharge cycle.
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Citations
54 Claims
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1. A method of charging series connected thin-film electrochemical cells, comprising:
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supplying a charge current to the thin-film electrochemical cells to cause a voltage to increase in each of the series connected electrochemical cells; and controlling, in response to the voltage of a particular series connected electrochemical cell reaching a voltage limit, the charge current through the particular electrochemical cell without interrupting the charge current supplied to other ones of the electrochemical cells. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A voltage equalization apparatus coupled to a charging unit that provides a charge current, the voltage equalization apparatus comprising:
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a plurality of thin-film electrochemical cells connected in series; a plurality of equalizer devices, each of the equalizer devices being coupled to one of the plurality of electrochemical cells and comprising; a detector coupled to a corresponding one of the electrochemical cells that senses a voltage of the corresponding electrochemical cell, the detector producing an output signal related to the magnitude of the sense voltage; a signal generator coupled to the detector that produces a control signal in response to the detector output signal; and a bypass circuit coupled to the corresponding electrochemical cell and the signal generator, the bypass circuit, in response to the control signal, conducting at least a portion of the charge current so as to bypass the corresponding electrochemical cell without interrupting the charge current provided to other ones of the plurality of electrochemical cells. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A voltage regulating apparatus coupled to a charging unit that provides a charge current, the voltage regulating apparatus comprising:
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a plurality of thin-film electrochemical cells connected in series; a plurality of regulating circuits, each of the regulating circuits being coupled to one of the plurality of electrochemical cells and comprising; a sensor that senses a voltage of a corresponding one of the electrochemical cells, the sensor producing an output signal related to the magnitude of the sense voltage of the corresponding electrochemical cell; a processor coupled to the sensor that determines a voltage difference between the sense voltage and a reference voltage, the processor producing a difference signal related to the magnitude of the voltage difference; a signal generator coupled to the processor that produces a digital control signal in response to the difference signal; and a bypass circuit coupled to the signal generator and the corresponding electrochemical cell, the bypass circuit, in response to the digital control signal, diverting at least a portion of the charge current to other ones of the plurality of electrochemical cells. - View Dependent Claims (28, 29, 30, 31)
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32. A voltage regulating apparatus coupled to a charging unit that provides a charge current, the voltage regulating apparatus comprising:
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a plurality of energy storing devices connected in series; and a plurality of regulating circuits, each of the regulating circuits being coupled to one of the plurality of energy storing devices and comprising a frequency modulated switching circuit or a pulse modulated switching circuit, a particular one of the regulating circuits shunting at least a portion of the charge current from a corresponding energy storing device to other ones of the plurality of energy storing devices in response to the corresponding energy storing device reaching a voltage setpoint. - View Dependent Claims (33, 34, 35, 36, 37)
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38. A method of charging series connected energy storing devices, comprising:
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supplying a charge current to the energy storing devices to cause a voltage to increase in each of the series connected energy storing devices; and in response to the voltage of a particular series connected energy storing device reaching a voltage limit, modulating, using either a phase modulation technique or a frequency modulation technique, a switch connected in parallel with the particular energy storing device to direct the charge current between the particular energy storing device and a bypass current path in parallel with the particular energy storing device. - View Dependent Claims (39, 40)
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41. A method of charging series connected thin-film electrochemical cell devices, comprising:
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determining a voltage of each of the series connected thin-film electrochemical cell devices; computing a voltage difference between a maximum voltage and a minimum voltage of the thin-film electrochemical cell device voltages; applying, in response to the voltage difference exceeding a pre-established limit, a substantially constant charge voltage at a first voltage level equivalent to the maximum voltage across the thin-film electrochemical cell devices; supplying, subsequent to applying the substantially constant charge voltage at the first voltage level, a charge current at a substantially constant level to the thin-film electrochemical cell devices to cause a voltage to increase in each of the series connected thin-film electrochemical cell devices until the voltage of a particular series connected thin-film electrochemical cell device reaches a voltage limit; and applying, in response to the voltage of the particular thin-film electrochemical cell device reaching the voltage limit, a substantially constant charge voltage at a second voltage level across the thin-film electrochemical cell devices. - View Dependent Claims (42, 43)
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44. A voltage equalization apparatus for an energy storing system, the voltage equalization apparatus coupled to a charging source that provides a charge current, the voltage equalization apparatus comprising:
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a plurality of thin-film electrochemical cell devices connected in series; a plurality of equalizer devices, each of the equalizer devices being coupled to one of the plurality of thin-film electrochemical cell devices and operating autonomously with respect to other ones of the plurality of equalizer devices, each of the equalizer devices comprising; an analog monitor circuit including first and second voltage inputs coupled across a corresponding one of the thin-film electrochemical cell devices, the analog monitor circuit sensing a voltage of the corresponding thin-film electrochemical cell device; and a power transistor having a gate coupled to an output of the analog monitor circuit, and a collector and an emitter coupled across the corresponding thin-film electrochemical cell device so as to define a bypass current path, the analog monitor circuit, in response to the sensed voltage, controlling the gate of the power transistor so as to moderate a flow of current through the bypass current path; wherein power dissipated by the power transistor is linearly related to the sensed voltage of the corresponding thin-film electrochemical cell device and the charge current. - View Dependent Claims (45, 46, 47, 48, 49, 50, 51, 52, 53, 54)
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Specification