System and method for balancing ultracapacitors

Abstract

We provide a system for equipping ultracapacitors. [Solution] The system 100 includes a plurality of ultracapacitors 110, a balance capacitor 120, a plurality of switching devices 130, and a control circuit. The control circuit is communicatively coupled to each of the plurality of switching devices. The control circuit controls the operation of a first pair of switching devices 132, 134 to couple the balance capacitors across the first ultracapacitor 112 of the plurality of ultracapacitors in order to transfer charge from the first ultracapacitor 112 to the balance capacitor. The control circuit also controls the operation of a second pair of switching devices 136, 138, different from the first pair, to couple the balance capacitors across the second ultracapacitor of the plurality of ultracapacitors in order to transfer at least a portion of the charge from the balance capacitor to the second ultracapacitor 114.

Description

[Technical Field]

[0001] Priority Claim This application claims priority to U.S. Provisional Patent Application No. 63 / 045,887, filed on June 30, 2020, entitled "System and Method for Balancing Ultracapacitors," which is incorporated herein by reference. [Background technology]

[0002] Electrical energy storage cells are widely used to power electronic, electromechanical, electrochemical, and other useful devices. For example, a double-layer ultracapacitor contains carbon particles (e.g., activated carbon) impregnated with a liquid electrolyte. Paired polarizing electrodes can be used. Due to the effective surface area of ​​the particles and the small spacing between the electrodes, a large capacitance value can be achieved. Individual double-layer capacitors can be combined to form modules with increased output voltage or increased energy capacity. [Overview of the Initiative] [Means for solving the problem]

[0003] One aspect of this disclosure relates to a system for balancing an ultracapacitor. The system comprises a balancing capacitor and a plurality of switching devices. The system further includes a control circuit. The control circuit is communicatively coupled to each of a plurality of switching devices. The control circuit is configured to control the operation of a first pair of switching devices to couple a balance capacitor across a first ultracapacitor among the plurality of ultracapacitors in order to transfer charge from a first ultracapacitor to a balance capacitor. The control circuit is further configured to control the operation of a second pair of switching devices, distinct from the first pair, to couple a balance capacitor across a second ultracapacitor among the plurality of ultracapacitors in order to transfer at least a portion of the charge from the balance capacitor to a second ultracapacitor.

[0004] Another aspect of the present disclosure relates to a method for equipping an ultracapacitor. The method includes the step of controlling the operation of a first pair of switching devices to couple an equilibrium capacitor across a first ultracapacitor among a plurality of ultracapacitors. When the equilibrium capacitor is coupled across the first ultracapacitor via the first pair of switching devices, the method includes the step of discharging the first ultracapacitor to transfer charge from the first ultracapacitor to the equilibrium capacitor. Following the step of discharging the first ultracapacitor to transfer charge to the equilibrium capacitor, the method includes the step of controlling the operation of a second pair of switching devices, different from the first pair of switching devices, to couple an equilibrium capacitor across a second ultracapacitor among a plurality of ultracapacitors. When the equilibrium capacitor is coupled across the second ultracapacitor via the second pair of switching devices, the method includes the step of discharging the equilibrium capacitor to transfer at least a portion of the charge to the second ultracapacitor.

[0005] Other features and aspects of this disclosure are described in further detail below.

[0006] The full and possible disclosure of this disclosure, intended for those skilled in the art, including its best mode, is described in more detail in the remainder of this specification with reference to the accompanying drawings. [Brief explanation of the drawing]

[0007] [Figure 1] This is a block diagram of the components of a system for equipping an ultracapacitor according to an exemplary embodiment of the present disclosure. [Figure 2] This figure shows the equilibrium capacitors of a system for equilibriumizing ultracapacitors, separated from each of the ultracapacitors according to the exemplary embodiments of this disclosure. [Figure 3] This figure shows a balancing capacitor for a system to balance an ultracapacitor, coupled to both ends of a first ultracapacitor via a first pair of switching devices of the system according to an exemplary embodiment of the present disclosure. [Figure 4] This figure shows a balancing capacitor for a system to balance an ultracapacitor, coupled to both ends of a second ultracapacitor via a second pair of switching devices of the system according to an exemplary embodiment of the present disclosure. [Figure 5] This is a flowchart illustrating an exemplary method for equipping an ultracapacitor according to an exemplary embodiment of the present disclosure. [Modes for carrying out the invention]

[0008] The repeated use of reference numerals in this specification and drawings is intended to represent the same or similar forms or elements of the present disclosure.

[0009] Those skilled in the art will understand that this discussion is merely a description of exemplary embodiments and is not intended to limit broader embodiments of the disclosure, and that broader embodiments are embodied in exemplary configurations.

[0010] Exemplary aspects of this disclosure relate to a system for balancing an ultracapacitor. The system may include a balancing capacitor and a plurality of switching devices. The balancing capacitor can be selectively coupled to each of the plurality of ultracapacitors via different pairs of switching devices (e.g., a first pair, a second pair, etc.). For example, the balancing capacitor can be coupled to the ends of a first ultracapacitor among the plurality of ultracapacitors via a first pair of switching devices. Alternatively, the balancing capacitor can be coupled to the ends of a second ultracapacitor among the plurality of ultracapacitors via a second pair of switching devices different from the first pair.

[0011] In some embodiments, the equilibrium capacitor may be a supercapacitor separate from the multiple ultracapacitors. More specifically, the multiple ultracapacitors may be coupled in series with each other, and the equilibrium capacitor may be a supercapacitor selectively coupled in parallel with each of the multiple ultracapacitors. Alternatively or additionally, the capacitance of the equilibrium capacitor may be smaller than the capacitance of at least one of the multiple ultracapacitors. In an alternative embodiment, the capacitance of the equilibrium capacitor may be the same as the capacitance of at least one of the multiple ultracapacitors. For example, in some embodiments, the capacitance of the equilibrium capacitor may be the same as the capacitance of each of the multiple ultracapacitors.

[0012] The system may include a control circuit. The control circuit can be configured to acquire data indicating the voltage across each of a plurality of ultracapacitors. For example, in some embodiments, the control circuit can acquire a plurality of signals. In such embodiments, each of the plurality of signals may indicate the voltage across the corresponding ultracapacitor. For example, a first signal among the plurality of signals may indicate a first voltage across a first ultracapacitor. In addition, a second signal among the plurality of signals may indicate a second voltage across a second ultracapacitor. In some embodiments, the control circuit The circuit can determine that the first voltage across the first ultracapacitor and the second voltage across the second ultracapacitor correspond to the highest voltage and the lowest voltage among the multiple ultracapacitors, respectively. Furthermore, in such embodiments, the control circuit can be configured to determine that the first voltage across the first ultracapacitor (e.g., the highest voltage) and the second voltage across the second ultracapacitor (e.g., the lowest voltage) are not substantially the same (e.g., not within 10% of each other).

[0013] The control circuit can be configured to control the operation of multiple switching devices in response to the determination that the voltage across a first ultracapacitor is different from the voltage across a second ultracapacitor. For example, the control circuit can be configured to provide one or more control signals to each switching device in a first pair of switching devices (e.g., the first switching device and the second switching device) in response to the determination that a first voltage across a first ultracapacitor is different from a second voltage across a second ultracapacitor. More specifically, one or more control signals may relate to coupling a balanced capacitor across the first ultracapacitor.

[0014] When the balanced capacitor is coupled across the first ultracapacitor via a first pair of switching devices, the first ultracapacitor can supply a discharge current to the balanced capacitor. The discharge current can be associated with the transfer of charge from the first ultracapacitor to the balanced capacitor. In this way, when the balanced capacitor is coupled across the first ultracapacitor via a first pair of switching devices, the first ultracapacitor can charge the balanced capacitor.

[0015] In some embodiments, the amount of charge transferred from the first ultracapacitor to the equilibrium capacitor can correspond to the amount of charge required to make the first voltage across the first ultracapacitor substantially the same as the second voltage across the second ultracapacitor. As used herein, the term “substantially the same” means that the first voltage and the second voltage are within 10% of each other. In such embodiments, the control circuit can be configured to control the operation of a first pair of switching devices to disconnect the equilibrium capacitor from the first ultracapacitor when the amount of charge transferred from the first ultracapacitor to the equilibrium capacitor corresponds to the amount of charge required to make the first voltage across the first ultracapacitor substantially the same as the second voltage across the second ultracapacitor. One or more control signals may be associated with disconnecting the equilibrium capacitor from the first ultracapacitor.

[0016] After the balancing capacitor is charged through the first ultra-capacitor, the control circuit can be configured to provide one or more control signals related to coupling the balancing capacitor across the second ultra-capacitor through a second pair of switching devices. For example, the control circuit can provide one or more control signals to each switching device (e.g., a third switching device and a fourth switching device) in the second pair of switching devices. The one or more control signals can be related to coupling the balancing capacitor across the second ultra-capacitor.

[0017] When the balancing capacitor is coupled across the second ultra-capacitor through the second pair of switching devices, the balancing capacitor can supply a discharge current to the second ultra-capacitor. The discharge current can be related to transferring at least a portion of the charge from the balancing capacitor to the second ultra-capacitor. In this way, the balancing cap acitor can charge the second ultra-capacitor when the balancing capacitor is coupled to the second ultra-capacitor through the second pair of switching devices.

[0018] In some embodiments, the amount of charge transferred from the balanced capacitor to the second ultracapacitor can correspond to the amount of charge required to increase the second voltage across the second ultracapacitor so that the first voltage across the first ultracapacitor and the second voltage across the second ultracapacitor are substantially the same. In such embodiments, the control circuit can be configured to control the operation of a second pair of switching devices to disconnect the balanced capacitor from the second ultracapacitor when the amount of charge transferred from the balanced capacitor to the second ultracapacitor corresponds to the amount required to make the first and second voltages substantially the same. For example, the control circuit can provide one or more control signals to each switching device in the second pair of switching devices. One or more control signals may be associated with disconnecting the balanced capacitor from the second ultracapacitor.

[0019] The systems illustrated in the embodiments of this disclosure offer a great many technical advantages and benefits. For example, a balancing capacitor can transfer charge (e.g., electrical energy) from a first ultracapacitor to a second ultracapacitor as needed to balance multiple ultracapacitors. Furthermore, since the balancing capacitor generates less heat compared to the discharge resistors used in conventional ultracapacitor balancing systems, it can reduce the heat associated with ultracapacitor balancing.

[0020] Next, referring to the figures, FIG. 1 shows a system 100 for equalizing a plurality of ultracapacitors 110 according to an exemplary embodiment of the present disclosure. The plurality of ultracapacitors 110 can be coupled to a power source 102 (e.g., direct current). In this way, each of the plurality of ultracapacitors 110 can receive power (e.g., direct current power) from the power source 102. Further, as shown, the plurality of ultracapacitors 110 can include at least a first ultracapacitor 112 and a second ultracapacitor 114. In alternative embodiments, the plurality of ultracapacitors 110 can include more than two ultracapacitors. For example, in some embodiments, the plurality of ultracapacitors 110 can include three or more ultracapacitors.

[0021] The system 100 can include an equalizing capacitor 120. In some embodiments, the equalizing capacitor 120 can be a supercapacitor separate from the plurality of ultracapacitors 110. More specifically, the plurality of ultracapacitors 110 can be coupled in series with each other, while the equalizing capacitor 120 can be a supercapacitor selectively coupled in parallel to each of the plurality of ultracapacitors 110. Alternatively or additionally, the capacitance of the equalizing capacitor 120 can be made smaller than the capacitance of at least one of the plurality of ultracapacitors 110. In alternative embodiments, the capacitance of the equalizing capacitor 120 can be made the same as the capacitance of at least one of the plurality of ultracapacitors 110. For example, in some embodiments, the capacitance of the equalizing capacitor and the capacitance of each of the plurality of ultracapacitors can be made the same.

[0022] System 100 may include a plurality of switching devices 130. A balanced capacitor 120 can be selectively coupled to each of the plurality of ultracapacitors 110 via different pairs of switching devices 130 (e.g., a first pair, a second pair, etc.). For example, a balanced capacitor 120 can be selectively coupled to each of the first ultracapacitors 112 via a first pair of switching devices 130 (e.g., a first switching device and a second switching device). Alternatively, balanced Capacitor 120 can be selectively coupled to both ends of the second ultracapacitor 114 via a second pair of switching devices 130 (e.g., a third switching device and a fourth switching device) that are different from the first pair.

[0023] It should be understood that the switching device 130 may include any device configured to electrically couple the balanced capacitor 120 to the ultracapacitor 110. For example, in some embodiments, one or more of the switching devices 130 may be transistors. Examples of transistors may include, but are not limited to, bipolar junction transistors (BJTs) and field-effect transistors (FETs). Alternatively or additionally, one or more of the switching devices 130 may be mechanical switches (e.g., relays, unipolar, single-throw). It should also be understood that the total number of switching devices in multiple switching devices 130 is greater than the total number of ultracapacitors in multiple ultracapacitors 110. More specifically, the total number of switching devices in multiple switching devices 130 may be twice the total number of ultracapacitors in multiple ultracapacitors 110.

[0024] As shown in the figure, system 100 may include a control circuit 140. In some embodiments, the control circuit 140 may include a processing circuit (not shown). As used herein, the terms “processor” or “processing circuit” refer not only to integrated circuits as they are included in computers as referred to in the art, but also to controllers, microcontrollers, microcomputers, programmable logic controllers (PLCs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), and other programmable circuits.

[0025] The control circuit 140 can be configured to acquire data indicating the voltage across each of the multiple ultracapacitors 110. For example, in some embodiments, the control circuit 140 can acquire a plurality of signals 150. In such embodiments, each of the plurality of signals may indicate the voltage across a corresponding ultracapacitor among the plurality of ultracapacitors 110. For example, a first signal among the plurality of signals 150 may indicate the voltage across a first ultracapacitor 112 among the plurality of ultracapacitors 110. In addition, a second signal among the plurality of signals 150 may indicate the voltage across a second ultracapacitor 114 among the plurality of ultracapacitors 110.

[0026] The control circuit 140 can be configured to determine whether the ultracapacitors 110 are balanced based at least in part on a plurality of signals 150. More specifically, the control circuit 140 can be configured to determine whether the voltages across each of the plurality of ultracapacitors 110 are substantially the same. As will be discussed below, when the control circuit 140 determines that the plurality of ultracapacitors 110 are unbalanced (i.e., the voltages across each ultracapacitor are not substantially the same), the control circuit 140 can provide one or more control signals 160 related to controlling the operation of the switching device 130 in order to facilitate the transfer of charge from one ultracapacitor (e.g., the first ultracapacitor 112) to another ultracapacitor (e.g., the second ultracapacitor 114) via the balanced capacitor 120. In this way, electrical energy can be transferred as needed to rebalance the ultracapacitors 110.

[0027] Next, referring to Figures 2 to 4, an embodiment of the system 100 according to an exemplary embodiment of the present disclosure is provided. As shown, the plurality of switching devices 130 may include a first pair of switching devices and a second pair of switching devices. The first pair of switching devices may include a first switching device 132 and a second switching device 134. The second pair of switching devices may include a third switching device 136 and a fourth switching device 138. The balanced capacitor 120 can be selectively coupled to both ends of the first ultracapacitor 112 and the second ultracapacitor 114 via the first pair of switching devices (e.g., the first switching device 132 and the second switching device 134) and the second pair of switching devices (e.g., the third switching device 136 and the fourth switching device 138), respectively.

[0028] If the control circuit 140 (shown in Figure 1) determines that a first voltage V1 across the first ultracapacitor 112 is different (e.g., substantially different) from a second voltage V2 across the second ultracapacitor 114, the control circuit 140 can be configured to control the operation of a first pair of switching devices. For example, in some embodiments, the control circuit 140 can determine that the first voltage V1 across the first ultracapacitor 112 and the second voltage V2 across the second ultracapacitor 114 correspond to the highest voltage and the lowest voltage among the multiple ultracapacitors 110, respectively. Furthermore, in such embodiments, the control circuit 140 can be configured to determine that the first voltage V1 across the first ultracapacitor 112 (e.g., the highest voltage) and the second voltage V1 across the second ultracapacitor 114 (e.g., the lowest voltage) are substantially different (e.g., not within 10% of each other).

[0029] The control circuit 140 may be configured to provide one or more control signals 160 (shown in Figure 1) to each switching device in a first pair of switching devices (e.g., the first switching device 132 and the second switching device 134) in response to the determination that the first voltage V1 across the first ultracapacitor 112 is different (e.g., substantially different) from the second voltage V2 across the second ultracapacitor 114. More specifically, one or more control signals 160 (shown in Figure 1) may relate to coupling the balanced capacitor 120 across the first ultracapacitor 112.

[0030] When the balanced capacitor 120 is coupled across the first ultracapacitor 112 via a first pair of switching devices (e.g., a first switching device 132 and a second switching device 134) as shown in Figure 3, the first ultracapacitor 112 can supply a discharge current to the balanced capacitor 120. The discharge current can be associated with transferring charge from the first ultracapacitor 112 to the balanced capacitor 120. In this way, when the balanced capacitor 120 is coupled across the first ultracapacitor 112 via a first pair of switching devices, the first ultracapacitor 112 can charge the balanced capacitor 120.

[0031] In some embodiments, the amount of charge transferred from the first ultracapacitor 112 to the balanced capacitor 120 can correspond to the amount required to make the first voltage V1 across the first ultracapacitor 112 substantially equal to the second voltage V2 across the second ultracapacitor 114. In such embodiments, the control circuit 140 (shown in Figure 1) is configured to control the operation of a first pair of switching devices (e.g., a first switching device 132 and a second switching device 134) to disconnect the balanced capacitor 120 from the first ultracapacitor 112 when the amount of charge transferred from the first ultracapacitor 112 to the balanced capacitor 120 corresponds to the amount of charge required to make the first voltage V1 across the first ultracapacitor 112 substantially equal to the second voltage V2 across the second ultracapacitor 114. This is possible. One or more control signals 160 (shown in Figure 1) may be associated with disconnecting the balanced capacitor 120 from the first ultracapacitor 112.

[0032] After the balanced capacitor 120 is charged via the first ultracapacitor 112, the control circuit 140 (shown in Figure 1) may be configured to provide one or more control signals 160 (also shown in Figure 1) related to coupling the balanced capacitor 120 across the second ultracapacitor 114 via a second pair of switching devices (e.g., a third switching device 136 and a fourth switching device 138). For example, the control circuit 140 may provide one or more control signals 160 (shown in Figure 1) to each switching device in the second pair of switching devices (e.g., a third switching device 136 and a fourth switching device 138). One or more control signals 160 may be related to coupling the balanced capacitor 120 across the second ultracapacitor 114.

[0033] When the balanced capacitor 120 is coupled across the second ultracapacitor 114 via a second pair of switching devices (e.g., a third switching device 136 and a fourth switching device 138), the balanced capacitor 120 can supply a discharge current to the second ultracapacitor 114. The discharge current can be associated with transferring at least a portion of the charge from the balanced capacitor 120 to the second ultracapacitor 114. In this way, the balanced capacitor 120 can charge the second ultracapacitor 114 when the balanced capacitor 120 is coupled to the second ultracapacitor 114 via a second pair of switching devices (e.g., a third switching device 136 and a fourth switching device 138).

[0034] In some embodiments, the amount of charge transferred from the balanced capacitor 120 to the second ultracapacitor 114 can correspond to the amount of charge required to make the first voltage V1 across the first ultracapacitor 112 substantially the same as the second voltage V2 across the second ultracapacitor 114. In such embodiments, the control circuit 140 (shown in Figure 1) can be configured to control the operation of a second pair of switching devices (e.g., a third switching device 136 and a fourth switching device 138) to disconnect the balanced capacitor 120 from the second ultracapacitor 114 when the amount of charge transferred from the balanced capacitor 120 to the second ultracapacitor 114 corresponds to the amount required to make the first voltage V1 across the first ultracapacitor 112 substantially the same as the second voltage V2 across the second ultracapacitor 114. For example, the control circuit 140 can provide one or more control signals 160 (shown in Figure 1) to each switching device in the second pair of switching devices. One or more control signals 160 may be associated with disconnecting the balanced capacitor from the second ultracapacitor.

[0035] Next, referring to Figure 5, a method 200 for balancing an ultracapacitor according to an exemplary embodiment of the present disclosure is provided. Method 200 can be carried out, for example, using the system 100 shown in Figures 1 to 4. Figure 5 shows the steps performed in a specific order for illustrative and discussion purposes. Those skilled in the art will understand, by using the disclosure provided herein, that any various steps of any of the methods disclosed herein can be omitted, rearranged, performed simultaneously, extended, modified, and / or adapted in various ways without departing from the scope of the present disclosure.

[0036] In (202), the method 200 may include the step of acquiring data indicating the voltage across each of the multiple ultracapacitors. For example, in some embodiments, the step of acquiring data indicating the voltage across each of the multiple ultracapacitors is used to control The circuit may include the step of acquiring multiple signals. Each of the multiple signals may represent the voltage across the corresponding ultracapacitor among the multiple ultracapacitors.

[0037] In (204), the method 200 may include the step of determining, at least in part, based on the data acquired in (202), that a first voltage across a first ultracapacitor among a plurality of ultracapacitors is different from a second voltage across a second ultracapacitor among a plurality of ultracapacitors. For example, in some embodiments, the step of determining that the first voltage is different from the second voltage may include, via a control circuit, determining that the first voltage and the second voltage correspond to the highest voltage and the lowest voltage among the plurality of ultracapacitors, respectively. More specifically, in such embodiments, the control circuit may be configured to determine that the highest voltage and the second voltage are not substantially the same (e.g., not within 10% of each other).

[0038] In (206), the method 200 may include the step of controlling the operation of a first pair of switching devices to couple a balanced capacitor across a first ultracapacitor among a plurality of ultracapacitors. For example, the step of controlling the operation of a first pair of switching devices may include providing one or more control signals to each switching device in the first pair of switching devices via a control circuit. One or more control signals may relate to controlling the operation of each switching device in the first pair of switching devices to couple a balanced capacitor to the first ultracapacitor.

[0039] In (208), method 200 may include the step of discharging the first ultracapacitor to transfer charge from the first ultracapacitor to the equilibrium capacitor when the equilibrium capacitor is coupled across the first ultracapacitor via a first pair of switching devices. In some embodiments, the amount of charge transferred from the first ultracapacitor to the equilibrium capacitor may correspond to the amount required to make the first voltage across the first ultracapacitor substantially the same as the second voltage across the second ultracapacitor.

[0040] In (210), the method 200 may include the step of controlling the operation of a first pair of switching devices to disconnect the equilibrium capacitor from the first ultracapacitor in response to the discharge of the first ultracapacitor in (208) to transfer charge to the equilibrium capacitor. For example, in some embodiments, the control circuit may provide one or more control signals to each switching device in the first pair of switching devices (e.g., the first switching device and the second switching device). One or more control signals may be related to controlling the operation of the first pair of switches to disconnect the equilibrium capacitor from the first ultracapacitor.

[0041] In (212), the method 200 may include the step of controlling the operation of a second pair of switching devices to couple a balanced capacitor across the second ultracapacitor. For example, in some embodiments, the control circuit may provide one or more control signals to each switching device in the second pair of switching devices (e.g., a third switching device and a fourth switching device). One or more control signals may be related to controlling the operation of the second pair of switches to couple a balanced capacitor across the second ultracapacitor.

[0042] In (214), the method 200 may include the step of discharging the equilibrium capacitor to transfer at least a portion of the charge to the second ultracapacitor when the equilibrium capacitor is coupled to the second ultracapacitor via a second pair of switching devices, while the equilibrium capacitor is coupled to the second ultracapacitor via a second pair of switches. In some embodiments, the amount of charge transferred from the equilibrium capacitor to the second ultracapacitor may correspond to the amount required to make the first voltage across the first ultracapacitor substantially the same as the second voltage across the second ultracapacitor.

[0043] In (216), the method 200 may include the step of controlling the operation of a second pair of switching devices to isolate the balanced capacitor from the second ultracapacitor. For example, in some embodiments, the control circuit may provide one or more control signals to each switching device in the second pair of switching devices (e.g., a third switching device and a fourth switching device). One or more control signals may be related to controlling the operation of the second pair of switches to isolate the balanced capacitor from the second ultracapacitor.

[0044] Any of the various different individual ultracapacitors can typically be used in modules according to the exemplary embodiments of this disclosure. However, in some embodiments, the ultracapacitor includes an electrode assembly and an electrolyte contained within a housing and optionally hermetically sealed. The electrode assembly may include, for example, a first electrode comprising a first carbonaceous coating (e.g., activated carbon particles) electrically coupled to a first current collector, and a second electrode comprising a second carbonaceous coating (e.g., activated carbon particles) electrically coupled to a second current collector. It should be understood that additional current collectors may be used if desired, particularly if the ultracapacitor comprises a large number of energy storage cells. The current collectors may be formed from the same or different materials. Nevertheless, each current collector is typically formed from a substrate comprising conductive metals, such as aluminum, stainless steel, nickel, silver, palladium, and alloys thereof. Aluminum and aluminum alloys are particularly preferred for use in this disclosure. The substrate may be in the form of foil, sheet, plate, mesh, etc. The substrate can also have a relatively small thickness, for example, about 200 micrometers or less, about 1 to about 100 micrometers in some embodiments, about 5 to about 80 micrometers in some embodiments, and about 10 to about 50 micrometers in some embodiments. Although not required, the surface of the substrate may optionally be roughened by washing, etching, blasting, etc.

[0045] In some embodiments, at least one, preferably both, of the first and second current collectors may further include a plurality of fiber-like whiskers protruding outward from the substrate. While not limited by theory, these whiskers are thought to effectively increase the surface area of ​​the current collector and, furthermore, improve the adhesion of the current collector to the corresponding electrode. This can allow for the use of relatively low binder content in the first and / or second electrodes, which can improve charge transfer, reduce interfacial resistance, and consequently result in a very low ESR value. Whiskers are typically formed from a material containing carbon and / or reaction products of carbon with a conductive metal. In one embodiment, for example, the material may include a carbide of a conductive metal such as aluminum carbide (Al4C3). Generally, a plurality of whiskers protrude outward from the substrate. Optionally, if desired, the whiskers may protrude from seed portions embedded within the substrate. Similar to whiskers, the seed portion can also be formed from a material containing carbon and / or reaction products of carbon with a conductive metal, such as a carbide of a conductive metal (e.g., aluminum carbide).

[0046] The method by which such whiskers are formed on the substrate may vary as desired. In one embodiment, for example, a conductive metal of the substrate is reacted with a hydrocarbon compound. Examples of such hydrocarbon compounds include paraffinic hydrocarbon compounds such as methane, ethane, propane, n-butane, isobutane, and pentane; olefinic hydrocarbon compounds such as ethylene, propylene, butene, and butadiene; acetylene hydrocarbon compounds such as acetylene; and any derivative or combination thereof. Generally, it is desirable that the hydrocarbon compound be in gaseous form during the reaction. Therefore, it may be desirable to use hydrocarbon compounds such as methane, ethane, and propane, which are in gaseous form when heated. Although not always necessary, the hydrocarbon compound is typically used in amounts ranging from about 0.1 parts by weight to about 50 parts by weight, based on 100 parts by weight of the substrate. In some embodiments, the amount used ranges from about 0.5 parts by weight to about 30 parts by weight. To initiate the reaction with hydrocarbons and conductive metals, the substrate is generally heated in an atmosphere at a temperature of about 300°C or higher, in some embodiments 400°C or higher, and in some embodiments from about 500°C to about 650°C. The heating time depends on the exact temperature selected, but is typically in the range of about 1 hour to about 100 hours. The atmosphere typically contains a relatively small amount of oxygen to minimize the formation of dielectric films on the surface of the substrate. For example, the oxygen content of the atmosphere can be about 1% by volume or less.

[0047] The first and second carbonaceous coatings are further electrically coupled to the first and second electron collectors, respectively. They may be formed from the same or different types of materials and may consist of one or more layers, but each carbonaceous coating typically includes at least one layer containing activated particles. In one embodiment, for example, the activated carbon layer may be directly positioned on the electron collector, or optionally, it may be just one layer of the carbonaceous coating. Examples of suitable activated carbon particles include, for example, coconut shell-based activated carbon, petroleum coke-based activated carbon, pitch-based activated carbon, polyvinylidene chloride-based activated carbon, phenol resin-based activated carbon, polyacrylonitrile-based activated carbon, and activated carbon from natural sources such as coal, charcoal, or other natural organic sources.

[0048] In some embodiments, it may be desirable to selectively control certain aspects of activated carbon particles, such as particle size distribution, surface area, and pore size distribution, to help improve the ion mobility of a certain type of electrolyte after being subjected to one or more charge-discharge cycles. For example, at least 50 volume percent of the particles (D50 size) may have a size ranging from about 0.01 to about 30 micrometers, in some embodiments from about 0.1 to about 20 micrometers, and in some embodiments from about 0.5 to about 10 micrometers. Similarly, at least 90 volume percent of the particles (D90 size) may have a size ranging from about 2 to about 40 micrometers, in some embodiments from about 5 to about 30 micrometers, and in some embodiments from about 6 to about 15 micrometers. The BET surface is about 900 m 2 From / g to approximately 3000m 2 / g, in some embodiments approximately 1000m 2 From / g to approximately 2500m 2 / g, in some embodiments approximately 1100m 2 From / g to approximately 1800m 2 It can also extend to / g.

[0049] In addition to having a specific size and surface area, activated carbon particles may further contain pores with a specific size distribution. For example, the amount of pores with a size of less than approximately 2 nanometers (i.e., "micropores") may be less than or equal to approximately 50% of the total pore volume. In some embodiments, the pore volume can be defined as about 30 volume% or less, and in some embodiments, as 0.1 volume% to 15 volume%. Similarly, the amount of pores between about 2 nanometers and about 50 nanometers in size (i.e., "mesopores") can be about 20 volume% to about 80 volume%, in some embodiments, about 25 volume% to about 75 volume%, and in some embodiments, about 35 volume% to about 65 volume%. Finally, the amount of pores larger than about 50 nanometers in size (i.e., "macropores") is It can be from about 1% to about 50% by volume, in some embodiments from about 5% to about 40% by volume, and in some embodiments from about 10% to about 35% by volume. The total pore volume of the carbon particles is about 0.2 cm 3 / g to about 1.5 cm 3 / g, and in some embodiments from about 0.4 cm 3 / g to about 1.0 cm 3 / g, and the median pore width can be about 8 nanometers or less, in some embodiments from about 1 to about 5 nanometers, and in some embodiments from about 2 to about 4 nanometers. The pore size and total pore volume may be measured using nitrogen adsorption and analyzed by the Barrett-Joyner-Halenda (「BJH」) technique.

[0050] If desired, the binder may be present in the first and / or second carbonaceous coating in an amount of about 60 parts or less per 100 parts of carbon, 40 parts or less in some embodiments, and about 1 to about 25 parts in some embodiments. The binder may constitute, for example, about 15% by weight or less of the total weight of the carbonaceous coating, about 10% by weight or less in some embodiments, and about 0.5% to about 5% by weight in some embodiments. Any of the various suitable binders may be used for the electrode. For example, water-insoluble organic binders, such as styrene-butadiene copolymer, polyvinyl acetate homopolymer, vinyl acetate-ethylene copolymer, vinyl acetate-acrylic copolymer, ethylene-vinyl chloride copolymer, ethylene-vinyl chloride-vinyl acetate terpolymer, acrylic polyvinyl chloride polymer, acrylic polymer, nitrile polymer, fluoropolymer such as polytetrafluoroethylene or polyvinylidene fluoride, polyolefins, and mixtures thereof, may be used in some embodiments. Water-soluble organic binders, such as polysaccharides and their derivatives, may also be used. In one particular embodiment, the polysaccharide may be a nonionic cellulose ether, e.g., alkyl cellulose ether (e.g., methylcellulose and ethylcellulose); hydroxyalkyl cellulose ether (e.g., hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylhydroxybutylcellulose, hydroxyethylhydroxypropylcellulose, hydroxyethylhydroxybutylcellulose, hydroxyethylhydroxypropylhydroxybutylcellulose, etc.); alkylhydroxyalkyl cellulose ether (e.g., methylhydroxyethylcellulose, methylhydroxypropylcellulose, ethylhydroxyethylcellulose, ethylhydroxypropylcellulose, methylethylhydroxyethylcellulose, and methylethylhydroxypropylcellulose); carboxyalkyl cellulose ether (e.g., carboxymethylcellulose); and similar, as well as any of the aforementioned protonated salts such as sodium carboxymethylcellulose.

[0051] Other materials may be used further within the activated carbon layers of the first and / or second carbonaceous coating, and / or within other layers of the first and / or second carbonaceous coating. For example, in some embodiments, conductivity can be further increased using conductivity enhancers. Exemplary conductivity enhancers may include, for example, carbon black, graphite (natural or artificial), graphite, carbon nanotubes, nanowires or nanotubes, metal fibers, graphene, and mixtures thereof. Carbon black is particularly preferred. When used, the conductivity enhancer typically constitutes about 60 parts or less per 100 parts of activated carbon particles in the carbonaceous coating, 40 parts or less in some embodiments, and about 1 to about 25 parts in some embodiments. The conductivity enhancer may constitute, for example, about 15% by weight or less of the total weight of the carbonaceous coating, about 10% by weight or less in some embodiments, and about 0.5% to about 5% by weight in some embodiments. Similarly, activated carbon particles typically constitute 85% or more by weight of the carbonaceous coating, about 90% or more by weight in some embodiments, and about 95% to about 99.5% by weight in some embodiments.

[0052] Specific methods for applying carbonaceous coatings to current collectors include printing (e.g., web gravure), spraying, slot-die coating, drop coating, and dipping coating. The method of application may vary. Regardless of the application method, the resulting electrodes are typically dried at temperatures of about 100°C or higher, about 200°C or higher in some embodiments, and about 300°C to about 500°C in some embodiments, etc., to remove moisture from the coating. The electrodes may also be compressed (e.g., calendered) to optimize the volumetric efficiency of the ultracapacitor. After any optional compression, the thickness of each carbonaceous coating may typically vary based on the desired electrical performance and operating range of the ultracapacitor. However, typically, the coating thickness is about 20 to about 200 micrometers, 30 to about 150 micrometers, and about 40 to about 100 micrometers in some embodiments. The coating may be present on one or both sides of the current collector. Nevertheless, the thickness of the entire electrode (including the current collector and carbonaceous coating after optional compression) is typically in the range of about 20 to about 350 micrometers, about 30 to about 300 micrometers in some embodiments, and about 50 to about 250 micrometers in some embodiments.

[0053] The electrode assembly further typically includes a separator positioned between the first electrode and the second electrode. If desired, additional separators may be used in the electrode assembly. For example, one or more separators may be positioned on the first electrode, the second electrode, or both. The separator can help prevent electrical short circuits by electrically isolating one electrode from the other, while still allowing ion transport between the two electrodes. In some embodiments, the separator may include, for example, cellulose fiber materials (e.g., airlaid paper web, wet paper web), nonwoven fiber materials (e.g., polyolefin nonwoven web), woven fabrics, films (e.g., polyolefin film), etc. Cellulose fiber materials, including natural fibers and synthetic fibers, are particularly suitable for use in ultracapacitors. Specific examples of cellulose fibers suitable for use in separators include, for example, hardwood pulp fibers, softwood pulp fibers, rayon fibers, and regenerated cellulose fibers. Regardless of the specific material used, the separator typically has a thickness of about 5 to about 150 micrometers, about 10 to about 100 micrometers in some embodiments, and about 20 to about 80 micrometers in some embodiments.

[0054] The way in which the components of an electrode assembly are put together can vary. For example, the electrodes and separators may first be folded, rolled up, stacked, or otherwise brought into contact together to form the electrode assembly. In one particular embodiment, the electrodes, separators, and an optional electrolyte may be rolled up into an electrode assembly having a "jelly roll" configuration.

[0055] To form an ultracapacitor, the electrolyte is positioned in ionic contact with the first and second electrodes before, during, and / or after the electrodes and separators are assembled to form the electrode assembly. The electrolyte is typically non-aqueous in nature and therefore contains at least one non-aqueous solvent. To help extend the operating temperature range of the ultracapacitor, it is typically desirable that the non-aqueous solvent has a relatively high boiling point, e.g., about 150°C or higher, about 200°C or higher in some embodiments, and about 220°C to about 300°C in some embodiments. Particularly preferred high-boiling point solvents may include cyclic carbonate solvents such as ethylene carbonate, propylene carbonate, butylene carbonate, and vinylene carbonate. Of course, other non-aqueous solvents may also be used alone or in combination with cyclic carbonate solvents. Examples of such solvents include, for example, open-chain carbonates (e.g., dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, etc.), aliphatic monocarboxylates (e.g., methyl acetate, methyl propionate, etc.), lactone solvents (e.g., butyrolactone, valerolactone, etc.), and nitriles (e.g., acetonitrile, glutaronitrile). This may include adiponitrile, methoxyacetonitrile, 3-methoxypropionitrile, etc., amides (e.g., N,N-dimethylformamide, N,N-diethylacetamide, N-methylpyrrolidinone), alkanes (e.g., nitromethane, nitroethane, etc.), sulfur compounds (e.g., sulfolane, dimethyl sulfoxide, etc.); and similar compounds.

[0056] The electrolyte may further contain at least one ionic liquid dissolved in a non-aqueous solvent. The concentration of the ionic liquid can be varied, but typically, it is desirable for the ionic liquid to be present at a relatively high concentration. For example, the ionic liquid may be present in an amount of about 0.8 moles (M) or more per liter of electrolyte, about 1.0 M or more in some embodiments, about 1.2 M or more in some embodiments, and about 1.3 to about 1.8 M in some embodiments.

[0057] Ionic liquids are typically salts having relatively low melting temperatures, e.g., below about 400°C, below about 350°C in some embodiments, from about 1°C to about 100°C in some embodiments, and from about 5°C to about 50°C in some embodiments. Salts contain cationic species and counterions. Cationic species include compounds having at least one heteroatom (e.g., nitrogen or phosphorus) as a "cationic center". Examples of such heteroatom compounds include, for example, unsubstituted or substituted organic quaternary ammonium compounds, e.g., ammonium (e.g., trimethylammonium, tetraethylammonium, etc.), pyridinium, pyridazinium, pyramidinium, pyrazinium, imidazolium, pyrazorium, oxazolium, triazolium, thiazolium, quinolinium, piperidinium, pyrrolidinium, quaternary ammonium spiro compounds in which two or more rings are joined together by a spiroatom (e.g., carbon, heteroatom, etc.), quaternary ammonium condensed ring structures (e.g., quinolinium, isoquinolinium, etc.), and similar compounds. In one particular embodiment, for example, the cation species may be an N-spironicyclic compound, such as a symmetric or asymmetric N-spironicyclic compound having a cyclic ring. One example of such a compound is the following structure

[0058] [ka] It has, Here, m and n are independently numbers from 3 to 7, and in some embodiments, 4 to 5 (e.g., pyrrolidinium or piperidinium).

[0059] Similarly, suitable counterions for cationic species include halogens (e.g., chlorides, bromides, iodides); sulfates or sulfonates (e.g., methyl sulfate, ethyl sulfate, butyl sulfate, hexyl sulfate, octyl sulfate, hydrogen sulfate, methane sulfonate, dodecylbenzene sulfonate, dodecyl sulfate, trifluoromethane sulfonate, heptadecafluorooctanesulfonate, sodium dodecylethoxysulfate, etc.); sulfosuccinates; amides (e.g., dicyanamide); imides (e.g., bis(pentafluoroethyl-sulfonyl)imide, bis(trifluoromethylsulfonyl)imide, bis(trifluoromethyl)imide, etc.); borates (e.g., tetrafluoroborate, tetracyanoborate). This may include: tris(pentafluoroethyl) phosphates, bis[oxalato]borate, bis[salicylate]borate, etc.); phosphates or phosphinates (e.g., hexafluorophosphate, diethyl phosphate, bis(pentafluoroethyl) phosphinate, tris(pentafluoroethyl)-trifluorophosphate, tris(nonafluorobutyl)trifluorophosphate, etc.); antimonates (e.g., hexafluoroantimonate); aluminates (e.g., tetrachloroaluminate); fatty acid carboxylates (e.g., oleate, isostearate, pentadecafluorooctanoate, etc.); cyanates; acetates; and similar substances, as well as any combination thereof.

[0060] Some examples of suitable ionic liquids include, for example, spiro-(1,1')-bipyrrolidinium tetrafluoroborate, triethylmethylammonium tetrafluoroborate, tetraethylammonium tetrafluoroborate, spiro-(1,1')-bipyrrolidinium iodide, triethylmethylammonium iodide, tetraethylammonium iodide, methyltriethylammonium tetrafluoroborate, tetrabutylammonium tetrafluoroborate, and tetraethylammonium hexafluorophosphate.

[0061] As described above, the ultracapacitor further includes a housing that holds the electrode assembly and electrolyte and is optionally hermetically sealed. The properties of the housing may vary as desired. In one embodiment, for example, the housing may include a metal container ("can") formed from tantalum, niobium, aluminum, nickel, hafnium, titanium, copper, silver, steel (e.g., stainless steel), alloys thereof, composites thereof (e.g., metals coated with conductive oxides), and the like. Aluminum is particularly preferred for use in this disclosure. The metal container may have any of a variety of different shapes, such as cylindrical or D-shaped. Cylindrical containers are particularly preferred.

[0062] In another embodiment, for example, the housing may take the form of a flexible package that encloses the components of the ultracapacitor. The package generally includes a substrate having edges that extend between two ends and where the ends and overlapping side portions are fixedly and tightly joined together (e.g., by thermal welding). In this way, the electrolyte can be held within the package. The substrate typically has a thickness ranging from about 20 micrometers to about 1000 micrometers, in some embodiments from about 50 micrometers to about 800 micrometers, and in some embodiments from about 100 micrometers to about 600 micrometers.

[0063] The substrate may include any number of layers desired to achieve a desired level of barrier properties, e.g., one or more, two or more in some embodiments, and two to four layers in some embodiments. Typically, the substrate includes a barrier layer which may include a metal such as aluminum, nickel, tantalum, titanium, or stainless steel. Such a barrier layer is generally impermeable to electrolytes so as to prevent electrolyte leakage, and is also generally impermeable to water and other contaminants. If desired, the substrate may further include an outer layer which serves as a protective layer for the package. In this way, the barrier layer is positioned between the outer layer and the electrode assembly. The outer layer may be formed from a polymer film, such as one formed from polyolefins (e.g., ethylene copolymer, propylene copolymer, propylene homopolymer, etc.), polyester, etc. Particularly preferred polyester films may include, for example, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, etc.

[0064] If desired, the substrate may further include an inner layer positioned between the electrode assembly and the barrier layer. In some embodiments, the inner layer may include a heat-sealable polymer. A suitable heat-sealable polymer is, for example, a vinyl chloride polymer. This can include vinyl chloridine polymers, ionomers, and combinations thereof. Ionomers are particularly preferred. In one embodiment, for example, the ionomer may be a copolymer comprising α-olefins and (meth)acrylic acid repeating units. Specific α-olefins may include ethylene, propylene, 1-butene; 3-methyl-1-butene; 3,3-dimethyl-1-butene; 1-pentene; 1-pentene with one or more methyl, ethyl, or propyl substituents; 1-hexene with one or more methyl, ethyl, or propyl substituents; 1-heptene with one or more methyl, ethyl, or propyl substituents; 1-octene with one or more methyl, ethyl, or propyl substituents; 1-nonene with one or more methyl, ethyl, or propyl substituents; ethyl, methyl, or dimethyl-substituted 1-decene; 1-dodecene; and styrene. Ethylene is particularly preferred. As described above, the copolymer can also be (meth)acrylic acid repeating units. As used herein, the term "(meth)acrylic" includes acrylic monomers and methacrylic monomers, as well as their salts or esters, such as acrylate monomers and methacrylate monomers.Examples of such (meth)acrylic monomers include methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, s-butyl acrylate, i-butyl acrylate, t-butyl acrylate, n-amyl acrylate, i-amyl acrylate, isobornyl acrylate, n-hexyl acrylate, 2-ethylbutyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, n-decyl acrylate, methylcyclohexyl acrylate, cyclopentyl acrylate, cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate This may include methacrylate, 2-hydroxyethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, i-propyl methacrylate, i-butyl methacrylate, n-amyl methacrylate, n-hexyl methacrylate, amyl methacrylate, s-butyl methacrylate, t-butyl methacrylate, 2-ethylbutyl methacrylate, methylcyclohexyl methacrylate, cinnamyl methacrylate, clotyl methacrylate, cyclohexyl methacrylate, cyclopentyl methacrylate, 2-ethoxyethyl methacrylate, isobornyl methacrylate, and combinations thereof. Typically, α-olefin / (meth)acrylic acid copolymers are at least partially neutralized with metal ions to form ionomers. Suitable metal ions may include, for example, alkali metals (e.g., lithium, sodium, potassium), alkaline earth metals (e.g., calcium, magnesium), transition metals (e.g., manganese, zinc), and combinations thereof. Metal ions can be provided by ionic compounds such as metal formates, acetates, nitrates, carbonates, bicarbonates, oxides, hydroxides, and alkoxides.

[0065] Within a module, there may be various ways in which ultracapacitors are connected. For example, ultracapacitors may be connected using interconnects that are attached to or connected to each terminal of the ultracapacitors. The interconnects may be made of a conductive material such as a conductive metal. In one embodiment, the interconnect may be relatively flat or may have an increased surface area. With regard to the latter, the interconnect may have protrusions / projections, or may further be formed from wires, braids, coils, etc. In this regard, the specific dimensions and configuration of the interconnect are not necessarily limited. Regardless of its form, any of a variety of different conductive materials may be used, such as copper, tin, nickel, aluminum, and alloys and / or coated metals. If desired, the conductive material may be optionally insulated with a sheath material.

[0066] Ultracapacitors can be electrically connected together in series or in parallel, depending on the desired specific properties. For example, in one particular embodiment, an ultracapacitor is connected in series or in parallel. Two ultracapacitors can be electrically connected in series such that a terminal of a specific polarity (e.g., positive) of one ultracapacitor is connected to a terminal of the opposite polarity (e.g., negative) of another ultracapacitor. For example, the positive terminal may extend from the top of the first ultracapacitor, and the negative terminal may extend from the bottom of the second ultracapacitor.

[0067] Ultracapacitors and modules, including those described herein, can be used to store large amounts of electric charge. As a result, the modules and ultracapacitors of this disclosure can be used in a variety of applications. For example, they can be used in a variety of energy applications, including, but not limited to, wind turbines, solar turbines, solar panels, and fuel cells. In addition, they can be used in a variety of transportation applications, including, but not limited to, vehicles (e.g., battery-powered electric vehicles, buses, hybrid electric vehicles including engine starting, power, and brake recovery systems), trains and electric trains (e.g., maglev trains, track switching, starter systems), and aerospace (e.g., door actuators, escape chutes). They also have a variety of industrial applications, including automation (e.g., robotics), vehicles (e.g., forklifts, cranes, electric carts). They also have a variety of applications in consumer electronics (e.g., portable media players, handheld devices, GPS, digital cameras), computers (e.g., laptop computers, PDAs), and communication systems. Modules and ultracapacitors can also have various military applications (e.g., motor starting for tanks and submarines, phased array radar antennas, laser power supplies, radio communications, avionics display and instrumentation, GPS guidance, etc.) and medical applications (e.g., defibrillators, etc.).

[0068] These and other modifications and variations of the present invention may be practiced by those skilled in the art without departing from the spirit and scope of the invention. In addition, it should be understood that the aspects of the various embodiments may be interchangeable, either in whole or in part. Furthermore, those skilled in the art will recognize that the foregoing description is merely an example and is not intended to limit the invention as further described in the appended claims.

Claims

1. A system for balancing an ultracapacitor, wherein the system is A plurality of switching devices comprising a first pair of switching devices including a first switching device and a second switching device, and a second pair of switching devices including a third switching device and a fourth switching device, A balanced circuit comprising one balanced capacitor, which is directly connected to a first pair of switching devices and a second pair of switching devices, The system comprises a control circuit that is communicatively coupled to each of the plurality of switching devices, and the control circuit is The balanced capacitor is coupled to both ends of the first ultracapacitor of a plurality of ultracapacitors, and the operation of the first pair of switching devices is controlled in order to transfer charge from the first ultracapacitor to the balanced capacitor. The balanced capacitor is coupled to both ends of the second ultracapacitor of the plurality of ultracapacitors, and the operation of the second pair of switching devices, which is different from the first pair, is controlled in order to transfer at least a portion of the charge from the balanced capacitor to the second ultracapacitor. After charge has been transferred from the first ultracapacitor to the equilibrium capacitor, the operation of the first pair of switching devices is controlled to disconnect the equilibrium capacitor from the first ultracapacitor, and After at least a portion of the charge has been transferred from the equilibrium capacitor to the second ultracapacitor, the operation of the second pair of switching devices is controlled to disconnect the equilibrium capacitor from the second ultracapacitor. Before at least a portion of the charge is transferred from the equilibrium capacitor to the second ultracapacitor, the first ultracapacitor has a charge amount greater than the charge amount of the second ultracapacitor. The balanced capacitor is a system comprising an ultracapacitor separate from the plurality of ultracapacitors.

2. The system according to claim 1, wherein the plurality of ultracapacitors are connected in series with respect to each other.

3. The system according to claim 1, wherein the capacitance of the equilibrium capacitor is the same as the capacitance of at least one of the plurality of ultracapacitors.

4. The system according to claim 1, wherein the capacitance of the equilibrium capacitor is smaller than the capacitance of each of the plurality of ultracapacitors.

5. The system according to claim 1, wherein each of the plurality of switching devices comprises a transistor.

6. The system according to claim 1, wherein the total number of switching devices in the plurality of switching devices is greater than the total number of ultracapacitors in the plurality of ultracapacitors.

7. A method for equipping an ultracapacitor, wherein the method is A step of controlling the operation of a first pair of switching devices, including a first switching device and a second switching device, in order to couple a balanced circuit across a first ultracapacitor of a plurality of ultracapacitors, wherein the balanced circuit comprises one balanced capacitor and is directly connected to the first pair of switching devices and to a second pair of switching devices different from the first pair of switching devices; When the balanced capacitor is coupled to the first ultracapacitor via the first pair of switching devices, the first ultracapacitor is discharged and charge is transferred from the first ultracapacitor to the balanced capacitor. A step of controlling the operation of a second pair of switching devices after discharging the first ultracapacitor to transfer the charge to the equilibrium capacitor, wherein the second pair of switching devices includes a third switching device and a fourth switching device to couple the equilibrium capacitor to both ends of the second ultracapacitor of the plurality of ultracapacitors. When the equilibrium capacitor is coupled to both ends of the second ultracapacitor via a second pair of switching devices, the step of discharging the equilibrium capacitor to transfer at least a portion of the charge to the second ultracapacitor, The steps include controlling the operation of a first pair of switching devices to disconnect the equilibrium capacitor from the first ultracapacitor in response to discharging the first ultracapacitor in order to transfer the charge from the first ultracapacitor to the equilibrium capacitor, and A step of controlling the operation of a second pair of switching devices to disconnect the equilibrium capacitor from the second ultracapacitor in response to the discharge of the equilibrium capacitor, in order to transfer at least a portion of the charge from the equilibrium capacitor to the second ultracapacitor; Equipped with, Before at least a portion of the charge is transferred from the equilibrium capacitor to the second ultracapacitor, the first ultracapacitor has a larger charge than the second ultracapacitor. A method wherein the balanced capacitor comprises an ultracapacitor separate from the plurality of ultracapacitors.

8. The method according to claim 7, wherein the step of controlling the operation of a first pair of switching devices to couple the balanced capacitor to the first ultracapacitor is performed in response to the determination that the voltage across the first ultracapacitor is different from the voltage across the second ultracapacitor.

9. The first voltage across the first ultracapacitor corresponds to the highest voltage among the plurality of ultracapacitors. The method according to claim 7, wherein the second voltage across the second ultracapacitor corresponds to the lowest voltage among the plurality of ultracapacitors.

10. The step of controlling the operation of the first pair of switching devices to couple the balanced capacitor across the first ultracapacitor comprises providing one or more control signals to each switching device in the first pair of switching devices via a control circuit, wherein the one or more control signals relate to coupling the balanced capacitor across the first ultracapacitor. The method according to claim 7, wherein the step of controlling the operation of a second pair of switching devices to couple the balanced capacitor across the second ultracapacitor comprises providing one or more control signals to each switching device in the second pair of switching devices via the control circuit, the one or more control signals relating to coupling the balanced capacitor across the second ultracapacitor.

11. The method according to claim 7, wherein the plurality of ultracapacitors are connected in series with each other.

12. The method according to claim 7, wherein each switching device in the first pair of switching devices and the second pair of switching devices comprises a transistor.

13. The method according to claim 7, wherein the capacitance of the equilibrium capacitor is smaller than the capacitance of at least one of the first ultracapacitor or the second ultracapacitor.

14. The method according to claim 7, wherein the capacitance of the equilibrium capacitor is the same as the capacitance of at least one of the first ultracapacitor or the second ultracapacitor.

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