Equalizer system and method for series connected energy storing devices

A voltage equalization apparatus coupled to a charging unit that provides a charge current, the voltage equalization apparatus comprising:

• 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.

A voltage regulating apparatus coupled to a charging unit that provides a charge current, the voltage regulating apparatus comprising:

• 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.

A method of charging series connected thin-film electrochemical cell devices, comprising:

• 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.

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:

• 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.