Improvement of Battery Balance

Abstract

To provide a device for active balancing of a battery which makes it possible to: reduce costs and / or complexity; avoid the need for galvanic isolation; and / or decrease the need for switches and / or cables.SOLUTION: The invention provides a device (200) for active balancing of a battery (B). The battery (B) comprises a plurality of units (U1-UN) connected in series at a plurality of nodes (N1-NN-1). The device comprises at least one DC / DC converter (210) configured to transfer charges between a first group of the plurality of units (U1-UN) and a second group of the plurality of units (U1-UN). At least one of the first and second groups comprises a plurality of the units (U1-UN).SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a method and an apparatus for balancing a battery stack based on dividing the battery stack into groups and moving charge between the groups.

Background Art

[0002] Battery packs for electric vehicles are becoming increasingly common, as are other types of battery packs used in a plurality of applications such as grid storage, home energy storage systems, and mobility light vehicles.

[0003] These battery packs are generally formed by a plurality of battery cells. A battery cell may include a single physical battery cell or a plurality of parallel cells. In the context of the present application, the reference to a cell can apply to both cases.

[0004] A battery pack is generally obtained by forming a high-voltage battery stack by connecting a plurality of cells in series. This connection is often necessary because a single cell battery usually has a low voltage. Typical values for lithium-ion batteries range, for example, from 3.3V to 3.8V depending on chemical characteristics. On the other hand, battery-powered devices generally require a higher voltage to avoid high current values. This is even more true in the case of high-power devices such as electric vehicles. For example, it is known that a battery pack for an electric vehicle is formed by a series connection of 96 such cells. These battery packs are usually called 400V batteries. Similarly, an 800V battery pack can be implemented by connecting 192 cells in series.

[0005] In order to connect a plurality of cells in series, it is necessary to keep these cells substantially equal, especially in terms of capacity and / or current transmission ability.

[0006] In fact, in a series connection, the weakest cell determines the performance of the entire pack. For example, when one cell is completely depleted, the discharge of the entire pack stops even though energy is available in the other cells. Similarly, during charging, when one cell reaches its full capacity, the charging process stops even though more energy can be stored in the other cells.

[0007] To avoid this problem, battery management systems, commonly referred to as BMS, generally use balancing techniques that can balance the cells to be in as similar a state as possible, particularly the same voltage level and / or the same state of charge (SoC). For this purpose, in balancing techniques, generally, the voltage of the cells and / or the current flowing through the cells are measured. Such measurements can control the flow of power, for example, to discharge the strongest cells more and reduce the discharge of the weakest cells. Balancing techniques are known to operate during both charging and discharging.

[0008] Balancing techniques according to the prior art generally operate in two known ways.

[0009] The first technique is known as passive balancing and generally functions by discharging the stronger cells to match the weakest cell. This is usually achieved by a passive load such as a resistor. The system becomes less efficient as excess energy is dissipated. For this reason, passive balancing generally functions only at a very low rate that maintains the balance of the pack on average over many charge and discharge cycles and is generally limited to applications where the load is applied intermittently and switched to long rest periods.

[0010] Another technique, known as active balancing, instead operates actively by moving energy from the stronger cells to the weakest. In this way, energy is moved from one cell to another without being wasted. Therefore, in active balancing, a DC-DC converter is generally used. Thus, the energy conversion ratio can be made very high so as to enable real-time balancing of the entire battery pack even during high-power charging or long-term output.

[0011] Conventional active balancing devices are known, for example, by Analog Devices' DC2100B-D, Linear Technology's LT8584, and Texas Instruments' EM1402EVM.

[0012] Figure 1 schematically shows a device for active balancing of a battery stack B including a plurality of cells C1 to C N .

[0013] This circuit includes, for example, a voltage detection unit which is connected to each cell C and includes detection means for detecting the voltages of various cells. Similarly, a switch matrix is connected to each cell C so as to be able to connect any two cells to a DC / DC converter. Based on the input from the detection means, the switch matrix and the DC / DC converter are operated to move charge from some cells to other cells as necessary. For example, if cell C N is determined to have the most charge and cell C1 is determined to have the least charge, the two cells are connected to the DC / DC converter and charge can be moved from cell C N to cell C1.

[0014] Thus, since it is necessary to individually detect the voltage of each cell and individually connect each cell to a DC / DC converter, the internal wiring of the battery pack becomes complicated. Furthermore, this wiring requires connectors, and the connectors reduce the robustness of the battery pack due to aging and mechanical vibration.

[0015] In addition, in order to independently connect several cells to a DC / DC converter, a large number of switches are required for the switch matrix. Generally, a known switch matrix requires at least two switches, one for the positive electrode and the other for the negative electrode, for each cell, which increases cost and complexity. Each of these switches requires wiring and a connector.

[0016] A further factor that complicates the wiring is generally that cells C1 to C are spaced apart from the detection means, the switch matrix, and the control module in which the DC / DC converter is usually arranged. Therefore, a power line - detection line wiring method is required, and in effect, the number of connections is doubled. N Furthermore, since each cell has a different voltage and all cells are connected in series, galvanic insulation (not shown) is often required to charge and discharge the cells with a DC / DC converter. As a solution to the above from the current technical situation, a transformer is implemented between the DC / DC converter and the cell. Such an implementation increases the component placement area.

[0017] All of these increase the cost, reduce the reliability, and any of these elements may become a failure point.

[0018] Therefore, it is necessary to provide a balancing system that overcomes the above disadvantages.

[0019] SUMMARY OF THE INVENTION SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0020] This requirement is solved by the teachings of the present invention defined by the independent claims. The dependent claims provide further advantageous features.

[0021] A preferred embodiment of the present invention makes it possible to obtain a device for active balancing of batteries that enables, in particular, reduction of cost and / or complexity, avoidance of the need for galvanic insulation, and / or reduction of the need for switches and / or wiring.

Means for Solving the Problems

[0022] Generally, the present invention is based on the concept that a battery stack can be divided into at least two groups and the balance of various cells can be achieved by performing charge transfer between one group and the other group. By appropriately controlling which cells are selected in each group and preferably repeating the charge transfer as needed, all cells can be converged.

[0023] Accordingly, one embodiment of the present invention may relate to a device for active balancing of a battery including a plurality of units connected in series at a plurality of nodes. The device for active balancing of a battery may include at least one DC / DC converter configured to transfer charge between a first group of the plurality of units and a second group of the plurality of units. At least one of the first group and the second group includes a plurality of the units. The plurality of units in the first group are different from the plurality of units in the second group. The DC / DC converter is configured to transfer charge between the plurality of units in the first group and the plurality of units in the second group and further includes a plurality of detection means each configured to measure at least one characteristic of each of the plurality of units and output each of the measured plurality of characteristics, and further includes a control unit configured to control the operation of the DC / DC converter based on the measured plurality of characteristics, the control unit being configured to execute a balancing method for the plurality of units, the balancing method including: controlling the plurality of detection means to measure at least one characteristic of the plurality of units; calculating an error value for each of the plurality of nodes; identifying a maximum error among the plurality of error values; and moving a charge between a first group and a second group set based on a node associated with the maximum error by controlling the DC / DC converter .

[0024] With this configuration, it is advantageously possible to move charge between more than two units at a time. As a result, the circuit required for such charge movement requires fewer components than the circuit required to move charge between any single unit among a plurality of units and any other single unit, and thus is more efficient. Further, by moving charge between more than two units at a time, it is possible to converge in a faster and / or simpler manner than moving charge only between two units in a given period of time. Further, by further including a plurality of detection means each configured to measure at least one characteristic of each of the plurality of units and output each of the measured plurality of characteristics, at least one characteristic of various units can be advantageously obtained so that the first group and the second group can be set Further, by further including a control unit configured to control the operation of the DC / DC converter based on the measured plurality of characteristics, the operation of the DC / DC converter can be advantageously controlled to converge the units based on the input data provided from the plurality of detection means Further, the control unit is configured to execute a balancing method for the plurality of units, the balancing method including: controlling the plurality of detection means to measure at least one characteristic of the plurality of units; calculating an error value for each of the plurality of nodes; identifying a maximum error among the plurality of error values; and moving a charge between a first group and a second group set based on a node associated with the maximum error by controlling the DC / DC converter. By including this, two groups can be advantageously and clearly defined based on the calculation of the error values

[0025] In some embodiments, at least one of the plurality of units may correspond to a physical battery cell.

[0026] With this configuration, it is advantageously possible to apply the present invention to a known battery composed of a plurality of battery cells. This is particularly the case for batteries for high-voltage applications such as electric vehicle batteries.

[0027] In some embodiments, at least one of the plurality of units may correspond to a plurality of physical battery cells connected in parallel and / or in series with each other.

[0028] With this configuration, the present invention can be advantageously applied to units implemented by a group of battery cells, and the balance between the groups can be achieved.

[0031] In some embodiments, at least one characteristic voltage, current, state of charge, state of health, charge amount, temperature, or one or more of them.

[0032] With this configuration, the present invention can be advantageously applied based on various input data. Preferably, at least one characteristic can be a characteristic for balancing between units. Thereby, the present invention can advantageously achieve a balance of various characteristics.

[0033] In some embodiments, the plurality of detection means may be configured to wirelessly transmit the plurality of measured characteristics.

[0034] With this configuration, it is possible to advantageously reduce the amount of wiring, switches, and other components that cause factors such as increased susceptibility to failure and increased battery cost and complexity.

[0039] In some embodiments, the error value can be set so that the node can be identified by the maximum error, and the identified node is such that when the steps of measuring the characteristic, calculating the error value, identifying the maximum error, and moving the charge between the first group and the second group are repeatedly executed a plurality of times, the plurality of units converge to the equilibrium value, the plurality of units are divided into a first group and a second group.

[0040] With this configuration, as long as it is defined such that the units converge when these steps are repeated a plurality of times, the definition of the error can be advantageously implemented in various ways.

[0041] In some embodiments, the error value can be a function of the difference between the average of at least one characteristic of the second group and the average of at least one characteristic of the plurality of units. Alternatively, or in addition, the error value can be a function of the difference between the average of at least one characteristic of the second group and the average of at least one characteristic of the first group.

[0042] With this configuration, the error value can be advantageously defined by two simple methods.

[0043] In some embodiments, the step of charge movement can be performed for a predetermined time and then stopped.

[0044] With this configuration, by implementing a timer, the steps of detection, calculation, identification, and charge movement can be advantageously executed multiple times in a simple manner.

[0045] In some embodiments, the step of charge movement is performed until the maximum error becomes smaller than a predetermined value.

[0046] With this configuration, by implementing a comparator, the steps of detection, calculation, identification, and charge movement can be advantageously executed multiple times in a simple manner.

[0047] In some embodiments, the DC / DC converter may include a first terminal and a second terminal. The DC / DC converter may be configured to convert a first DC voltage supplied to the first terminal into a second DC voltage and supply it to the second terminal, and vice versa. Further, when the DC / DC converter is connected to a plurality of units, the first terminal may be connected to the positive terminal of the plurality of units, and the second terminal may be configured to be connectable to any of the plurality of nodes.

[0048] With this configuration, the DC / DC converter and each switch matrix can be advantageously implemented in a simple manner.

Brief Description of Drawings

[0049]

Figure 1

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Figure 8

[0050] Some embodiments in the present disclosure generally provide a plurality of circuits or other electrical devices. All references to the circuits and other electrical devices and the functionality provided by each are not intended to be limited to only those illustrated and described herein. While various circuits or other electrical devices described may be given specific labels, such labels are not intended to limit the operating scope of the circuits and other electrical devices. Such circuits and other electrical devices may be combined with and / or separated from each other in any manner based on the particular type of electrical implementation desired.

[0051] The circuits or other electrical devices disclosed herein may include any number of microcontrollers, integrated circuits, memory devices (e.g., FLASH, random access memory (RAM), read only memory (ROM), electrically programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), or other suitable variations thereof), and software that cooperate with each other to perform the operations disclosed herein. Further, any one or more of the electrical devices may be configured to execute program code embodied in a non-transitory computer-readable medium programmed to perform any number of the disclosed functions.

[0052] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood that the following description of the embodiments is not to be construed in a limiting sense. The scope of the present invention is not intended to be limited by the embodiments described below or by the drawings, which are merely illustrative.

[0053] The drawings are considered to be schematic representations and elements illustrated in the drawings are not necessarily shown to scale. Rather, the various elements are represented so as to make their function and general purpose apparent to those skilled in the art. Any connection or coupling between the functional blocks, devices, components, or other physical or functional units shown in the drawings or described herein may be implemented by an indirect connection or coupling. The coupling between components may be established via a wireless connection. The functional blocks may be implemented by hardware, firmware, software, or a combination thereof.

[0054] FIG. 2(A) schematically shows an apparatus 200 for active balancing of battery B.

[0055] As shown in FIG. 2(A), battery B has a plurality of nodes N1 to N N-1In which a plurality of units U1 to U are connected in series N may be included. The plurality of units U1 to U N may include at least a first unit U1 and a second unit U2.

[0056] Generally, each of the plurality of units U1 to U N can be understood to include or be implemented by one or more physical units capable of storing charge. If there are a plurality of physical units for each of the units U1 to U N , the plurality of physical units can be connected to each other in series and / or in parallel. In a preferred embodiment, the plurality of units U1 to U N are of a single type. That is, each of the plurality of units U1 to U N is preferably implemented in the same way and has the same nominal characteristics.

[0057] It will be apparent to those skilled in the art that a single unit can be implemented in a plurality of ways.

[0058] In particular, in some embodiments, as shown in FIG. 2(B), at least one of the plurality of units U1 to U N , preferably most of the plurality of units U1 to U N , more preferably all of the plurality of units U1 to U N may include or correspond to a single physical battery cell C, such as any of a pouch cell, a prismatic cell, and a cylindrical cell.

[0059] Alternatively, or in addition, in some embodiments, as shown in FIG. 2(C), at least one of the plurality of units U1 to U N , preferably most of the plurality of units U1 to U N , more preferably most of the plurality of units U1 to U NAll of which may include, or correspond to, a plurality of physical battery cells C1 to C2 connected in series with each other. Although only two cells are illustrated in FIG. 2(C), it will be apparent that the present invention is not limited thereto and may be implemented with any number of cells. As will be apparent to those skilled in the art, this embodiment only enables balancing of the units and remains unrestricted as to whether and how to balance the cells within the unit. In some embodiments, such cells within a single unit may simply be left unbalanced if permitted by the application. Alternatively, or in addition, known balancing methods may be implemented for the cells within the unit. Further alternatively, or in addition, the cells C1 to C2 within a given unit U may be balanced in the same manner as described for the units U1 to U N within a given battery B. That is, the approaches described by various embodiments of the present invention may be applied to the cells connected in series within a unit in substantially the same manner as applied to the units connected in series of the battery.

[0060] Further alternatively, or in addition, in some embodiments, as shown in FIG. 2(D), at least one of the plurality of units U1 to U N , preferably a majority of the plurality of units U1 to U N , more preferably all of the plurality of units U1 to U N may include, or correspond to, a plurality of physical battery cells C1 to C2 connected in parallel with each other. Although only two cells are illustrated in FIG. 2(D), it will be apparent that the present invention is not limited thereto and may be implemented with any number of cells.

[0061] Further alternatively, or in addition, in some embodiments, at least one of the plurality of units U1 to U N , preferably a majority of the plurality of units U1 to U N , more preferably all of the plurality of units U1 to UN All of which may include, or correspond to, a plurality of physical battery cells C1 to C2 that are connected in series with each other to form a first group connected in parallel to one or more similar groups. Further alternatively, or in addition, in some embodiments, a plurality of units U1 to U N At least one of, preferably a plurality of units U1 to U N Most of, more preferably a plurality of units U1 to U N All of which may include, or correspond to, a plurality of physical battery cells C1 to C2 that are connected in parallel with each other to form a first group connected in series to one or more similar groups.

[0062] A plurality of units U1 to U N From among which, groups G1 and G2 of at least two units may be defined. This is shown, for example, in FIG. 6. Preferably, in some embodiments, only two groups including all of the units U1 to U N May be defined.

[0063] Hereinafter, for clarity of explanation, group G1 is referred to as the first group and group G2 is referred to as the second group. It will be apparent to those skilled in the art that embodiments of the present invention are also operable in the reverse definition, i.e., when G1 is the second group and G2 is the first group.

[0064] Hereinafter, a general description of how a group may be configured is provided, followed by more specific examples. The present invention is not limited to these specific examples, and in particular, the methods described in relation to these examples may, in some cases, be applied to other definitions of groups by adapting the method in a manner apparent to those skilled in the art based on the following description.

[0065] Thus, generally, in some embodiments, the first group G1 may include several units from one terminal of the battery to a given node N k up to. For example, as shown in FIG. 6, the first group G1 may include the units from node N k to the positive terminal, that is, the units U k+1 to U N . The second group G2 may be composed of the number of several units from the opposite terminal of the battery to the same given node N k up to. For example, as shown in FIG. 6, the second group G2 may include the units from the negative terminal to node N k up to, that is, the units U1 to U k .

[0066] Alternatively, or in addition, the first group G1 may include at least one, preferably at least two, of the units U1 to U N , and the second group G2 may include at least one, preferably at least two, units different from those of the first group among the units U1 to U N .

[0067] Alternatively, or in addition, the second group G2 may include all the units U1 to U N not included in the first group G1.

[0068] Alternatively, or in addition, either the first group G1 or the second group G2 may include one or more units. When a plurality of units are included, they may be connected in series with each other. That is, in the case of a plurality of units, all the units of a given group may be connected in series to form a series connection group.

[0069] Alternatively, or in addition, the groups G1 and G2 may be defined with reference to the terminals 611 to 613 and the DC / DC converter 610 as described below.

[0070] That is, in some embodiments, the first group G1 may include a unit connected between the terminal 612 and the positive terminal 611 of the DC / DC converter 610. Alternatively, or in addition, the second group G2 may include several units connected between the negative terminal 613 and the terminal 612 of the DC / DC converter 610. In some embodiments, as will be described below, the terminal 612 of the DC / DC converter 610 is included between the negative terminal 613 and the node connected to the positive terminal 611, but is different from the node connected to the negative terminal 613 and the positive terminal 611, a given node N of the battery B k may be connected to. Here, the expression included between means that the node N k is understood to be connected along a series connection between the nodes respectively connected to the terminals 613 and 611.

[0071] This embodiment enables the DC / DC converter 610 to operate with the two terminals 613 and 611 fixedly connected to the units U1 and U N , or the two terminals of the battery B, respectively, and at the same time enables the terminal 612 to be connected to a given node N by the switch matrix 640 k , which is particularly advantageous. Nevertheless, it will be apparent to those skilled in the art that alternative embodiments are feasible.

[0072] Referring again to FIG. 2(A), the apparatus 200 includes at least one DC / DC converter 210 configured to move charge between the first group G1 and the second group G2.

[0073] In the following description, various examples in which charge is moved from the first group G1 to the second group G2 are described. However, it will be apparent that the present invention can also act in the reverse direction. However, for the sake of clarity and brevity of the description, the present invention is described with reference to an embodiment that operates in the former manner. It will be apparent to those skilled in the art that mirror operation is possible if necessary.

[0074] With this configuration, the DC / DC converter 210 can transfer charge, for example, from some more charged units such as units U of the first group G1 to some less charged units such as units U1 to U of the second group G2. k+1 from U N to U k of the second group G2.

[0075] More generally, the expression "more charged" can be understood to mean that the value of a physical characteristic of the battery, such as voltage, current, absolute charge amount, or SoC, is higher in the "more charged" group than in the "less charged" group. Hereinafter, for the sake of clarity and brevity of the description, the terms "more charged" and "less charged" are used, but it should be understood that these can be replaced by "having a higher value for the characteristic" and "having a lower value for the characteristic", respectively.

[0076] Furthermore, it should be noted that, as will become apparent from the following examples, the expressions "more charged" and "less charged" are not necessarily related to each individual unit in the group. That is, assuming that the units of the first group are more charged and the units of the second group are less charged, it is not necessary that each unit in the first group is more charged than each unit in the second group. On the contrary, as will become apparent from the following description, it is sufficient if the average charge of the first group is higher than the average charge of the second group. Therefore, the terms "more charged" and "less charged" can be replaced by "having a higher average value for the characteristic" and "having a lower average value for the characteristic", respectively.

[0077] That is, instead of focusing on the state of each specific unit, the present invention operates from the perspective of a group of units and balances the units by taking the balance of the group. This approach enables the units to converge to a balanced state, especially when repeated multiple times.

[0078] In other words, for example, based on the charge amount as a characteristic of the battery to be balanced, even when the balancing is completed, there may be a unit U k with a lower charge amount like this, and a unit U N with a higher charge amount like this.

[0079] In the prior art, this is achieved by moving charge from, in particular, U N to U k through a DC / DC converter.

[0080] On the other hand, in some embodiments of the present invention, the second group G2 can be defined to include, for example, units U1 to U k in the group so as to include unit U k . At the same time, the first group G1 can be defined to include, for example, units U k+1 to U N in the group so as to include unit U N . As a result, charge is moved from all the units in the first group G1 including U N to all the units in the second group G2 including U k . As a result, as intended, unit U k is charged and unit U N is discharged.

[0081] In this way, the remaining units of the second group are similarly charged, and the remaining units of the first group are similarly discharged. Nevertheless, by repeating the process with appropriate calculation of the groups, all units can converge to a balanced state. Preferably, in some embodiments, the control unit is configured such that not only during charge transfer but also as a result, none of the units are overcharged or overdischarged.

[0082] That is, as will become even more apparent from the following description, instead of performing charging / discharging by connecting a single unit to another single unit, embodiments of the present invention can transfer charge between groups. Eventually, as a result, at least one unit is discharged and at least one unit is charged, but it can be implemented with less hardware than in the prior art.

[0083] It will be apparent to those skilled in the art that several types of DC / DC converters can be implemented to obtain this characteristic. In the following description, several specific embodiments that are particularly advantageous will be described. However, the present invention should not be limited to such specific embodiments and can be implemented in principle by any type of DC / DC converter capable of performing the functions described above.

[0084] As further shown in FIG. 2(A), this apparatus 200 may further include a plurality of detection means 230 shown as S1 to S N Each of the plurality of detection means 230 may be configured to measure at least one characteristic of each of the plurality of units U1 to U N Therefore, the plurality of detection means 230 can output the respective measured characteristics.

[0085] The detection means may alternatively be a plurality of nodes N1 to N N-1 or nodes N1 to N NIt will be apparent to those skilled in the art that it can be configured to measure at least one characteristic at each of the respective nodes. That is, the detection means can measure the characteristics in one or more units or in one or more nodes. It will be apparent to those skilled in the art that these two measurements can be converted into each other. For example, the voltage of node N k can be measured directly or determined from the sum of the voltages of units U1 to U k . In some preferred embodiments, the measurement is preferably performed in each single unit because it enables measurement of lower voltages and simplifies the required components. Furthermore, this allows the characteristics of the units to be measured directly, simplifying the determination of which one or more units need to receive charge and which one or more units can be used to supply charge. For example, referring to FIG. 2(A), the detection means S1 can measure at least one characteristic of unit U1, and the detection means S N can measure at least one characteristic of unit U N , and so on. In a preferred embodiment, the number of detection means 230 is equal to or greater than the number of units U1 to U N . N

[0086] In some embodiments, each single detection means may include a plurality of detection devices. For example, if the detection means measures two characteristics of each unit such as temperature and voltage, it may include two devices such as a thermometer and a voltage sensor.

[0087] In a preferred embodiment, at least one characteristic includes voltage, current, state of charge, state of health, charge amount, temperature, or one or more of them.

[0088] ​It will be apparent that there are cases where characteristics cannot be directly measured, such as the state of health (SoH) of a unit. In such cases, the detection means 230 measures one or more characteristics of the unit that can actually be directly measured, such as voltage, current, temperature, etc., and can derive the characteristics that cannot be directly measured by appropriate algorithms and / or calculations in a method known per se.

[0089] As shown in FIG. 2(A), in some embodiments, the plurality of detection means 230 may be configured to transmit the plurality of measured characteristics to the control unit 220.

[0090] This can be implemented by one or more wirings. For example, each of the plurality of detection means 230 may be connected to the control unit 220. Alternatively, the plurality of detection means 230 may be connected to the control unit 220 by a single wiring such as a bus.

[0091] Alternatively, or in addition, the transmission of the plurality of measured characteristics to the control unit 220 can be implemented wirelessly. This eliminates the galvanic insulation required in the prior art. Furthermore, this significantly reduces the wiring required for the device 200, reducing complexity and cost. Furthermore, since each wiring is a potential failure point, this improves reliability. Preferred embodiments of the present invention can be implemented with BLE or Zigbee wireless standards, including but not limited to protocol stack and encryption variations, and can also be customized as required.

[0092] As further shown in FIG. 2(A), in some embodiments, the device 200 may further include a control unit 220 configured to control the operation of the DC / DC converter 210 based on the plurality of measured characteristics.

[0093] For example, as described above, the control unit 220 can identify two groups G1 and G2 based on one or more measured characteristics, and preferably, for one or more measured characteristics, the group G2 has a lower average value than the group G1. Next, the control unit can be operated to control the DC / DC converter so that charge can be transferred between the group G1 and the group G2.

[0094] In the case where the groups are defined such that G2 has less charge than G1, this method transfers charge from group G1 to group G2. By performing this multiple times, preferably by redefining groups G1 and G2 each time, the balance of the unit can be achieved.

[0095] It will be apparent to those skilled in the art that there may be multiple ways to ensure that the definition of the groups and the corresponding charge transfer are performed multiple times so that convergence is possible. FIGS. 3, 4, and 5 schematically show active balancing methods 300, 400, and 500 for the battery B, all of which ensure multiple repetitions of such methods. These methods can be particularly implemented by the control unit 220.

[0096] In particular, as shown in FIG. 3, the control unit 220 can be configured to execute the balancing method 300 for a plurality of units U1 to U N .

[0097] The balancing method 300 includes a step S310 of controlling a plurality of detection means 230 to measure at least one characteristic of a plurality of nodes N1 to N N-1 . In the following embodiments, the description will be based on the measured characteristics of the plurality of nodes N1 to N N-1 . It will be apparent to those skilled in the art that those measurements can be made directly or can be derived from the measured characteristics of the plurality of units U1 to U N as described above.

[0098] It will be apparent to those skilled in the art that it can be implemented by multiple methods. For example, the detection means can continuously or at a predetermined period measure at least one characteristic, and the measurement step S310 can be implemented by finally outputting available measurement data, preferably in response to a request from the control unit 220. Alternatively, or in addition, the detection means can start measuring in response to a request from the control unit 220 and then provide the corresponding output to the control unit. Generally, the purpose of the measurement step S310 is to enable the control unit to utilize a plurality of measured characteristics so that the control unit can evaluate whether it is necessary to balance the unit and which one or more units need to balance with which one or more other units.

[0099] The balancing method 300 may further include a step S320 of calculating an error value E for each of a plurality of nodes N1 to N N-1 Hereinafter, various aspects enabling the calculation of the error value will be defined. Generally, the purpose of the error value E is to enable the identification of the node N k Thereby enabling the definition of the first and second groups. That is, the first and second groups G1 and G2 can be defined as a function of a given node N k

[0100] In particular, in some embodiments, the error value can be set so that the node N MAX can be identified by the maximum error E among a plurality of error values, and this node can move charges between G1 and G2 so that the units U1 to U k converge to an equilibrium value, dividing the units U1 to U N into two groups G1 and G2. N

[0101] ​​As will be apparent to those skilled in the art, this general approach can be implemented in multiple ways and it is not possible to define all of them herein. Nevertheless, the following description provides two possible specific implementations that conform to this definition based on the calculation of the difference in average values.

[0102] In particular, the difference can be calculated between the average of at least one characteristic of the second group G2 and the average of at least one characteristic of the plurality of units U1 to U N Alternatively, or in addition, this difference can be calculated between the average of at least one characteristic of the second group G2 and the average of at least one characteristic of the first group G1. The error value can be calculated as a function of this difference.

[0103] Thus, more formally, the error E(k) for the node N k that distinguishes G1 and G2 can be defined as follows:

Equation

[0104] to U k+1 and the second group G2 includes the units U1 to U N to U k First, the former case will be described, and the latter case will be described later. The following description of the example is based on the configuration of FIG. 6, where the first group G1 includes the units U

[0105] In the former case, in some further embodiments, the error value E can be formally defined as follows.

Number

[0106] For example, as shown in FIG. 6, there is a tenth node N N on the positive electrode of unit U, and ten units U1 to U N connected in series at nine nodes N1 to N N-1 are assumed, and the following exemplary values are assumed for the characteristics of units U1 to U N and nodes N1 to N N : N-1 For the characteristics of units U1 to U and nodes N1 to N, assume the following exemplary values:

Table 1

[0107] Using the exemplary Phys_char(i) in the above unit, the error value E(1) can be calculated as follows.

Number

Number

Number

Number

Number

Table 2

[0108] As further shown in FIG. 3(A), the balancing method 300 may further include step S330 of identifying the maximum error E MAX in a plurality of error values, and the units and / or nodes associated with the maximum error E MAX .

[0109] In some embodiments, the maximum error E MAX may be defined as the error having the highest maximum absolute value. In the above numerical example, this corresponds to E1, indicating that the correction at node N1 can be advantageously applied. That is, node N1 may be identified as the node separating the two groups. If two nodes have the highest absolute value of equal magnitude, either of the two nodes may be regarded as the node having the maximum error E MAX .

[0110] Furthermore, in some embodiments, the sign of the maximum error E MAX may indicate the direction in which the charge is moved. That is, if the maximum error E MAX has one of the positive or negative signs, the charge is moved to one side of the first group G1 and the second group G2. Conversely, if the maximum error E MAX has the other of the positive or negative signs, the charge will be moved to the other side of the first group G1 and the second group G2. It will be apparent to those skilled in the art that a particular sign and a particular direction are functions in a particular definition of the error. In the above example, in the case of a positive sign, the charge is moved from the second group G2 to the first group G1. That is, in this specific numerical example, the first charge transfer is performed from unit U1 to units U2~U N .

[0111] As described above, the characteristic to be considered may be any of the plurality of characteristics described above.

[0112] Therefore, in a preferred embodiment, in order to balance the voltage between units, an error value E can be calculated by using the measured characteristic as the voltage value V. Using the same formula as above, this can be implemented as follows.

Number

[0113] Alternatively, or in addition, in a more preferred embodiment, in order to balance the SoC (State of Charge) between units, an error value E can be calculated by using the measured characteristic as the state of charge (SoC).

Number

[0114] Furthermore alternatively, or in addition, in an even more preferred embodiment, in order to balance the charge between units, an error value E can be calculated by using the measured characteristic as the available charge amount Q(i).

Number

[0115] In the above embodiment, the definition of the error was described as follows.

Number

Number

Number

Table 3

[0116] Using the Phys_char(i) of the unit, the error value E(1) can be calculated as follows.

Number

Number

Table 4

[0117] In this case, by selecting the one with the largest absolute value as the maximum error E MAX it is possible to identify the maximum error E MAX as E(6). Although this is different from the maximum error E MAX identified previously, the present invention can proceed as described above, and nevertheless, as a result, it will converge among all units after a plurality of cycles.

[0118] Thus, it has been shown that there are multiple ways to indicate the node for the maximum error E MAX , and all of them enable the movement of charges that ultimately converge the units. That is, the node N MAX identified based on the maximum error E k preferably moves charges between the first group G1 and the second group G2 when the maximum error E MAXBy executing the calculation of and the subsequent movement of each charge a plurality of times, a plurality of units U1 to U N are divided into a first group G1 and a second group G2 so that they converge to an equilibrium value. N

[0119] Similar to the above, the sign of the maximum error E MAX can be used to identify in which direction the charge is moved. In this case, according to a specific definition of the error, a negative sign indicates that the charge is moved from the first group G1 to the second group G2.

[0120] Generally, in this way, in the balancing method 300, how the step S350 of moving charge between the first and second groups G1, G2 identified by the identification of a given node N k can be included has been described. As shown in FIG. 3(A), in some embodiments, the execution of step S350 can be conditioned on the result of any step S340 that determines whether the maximum error E MAX is greater than a predetermined threshold.

[0121] Referring to FIG. 6, it is clear how step S350 can be executed. In particular, the battery B can pass a current I BATTERY through the electrodes. A part of this current, I IN can flow towards the DC / DC converter by connecting the positive terminal of the battery to terminal 611 of the DC / DC converter, whereby a current I BATTERY -I IN flows through one or more units of the first group G1.

[0122] The current I IN can be input to the DC / DC converter, and as a result, an output current I BAL is obtained. It will be apparent that the DC / DC converter can apply a given conversion between I IN and I BAL .

[0123] ​ The switch matrix 640 can be controlled to connect the terminal 612 to any one of the battery nodes, particularly from the battery node N1 to N N-1 of any one. From this, it is already clear that even if the number of switches is small, that is, even if it is the same number as N - 1, it is sufficient to operate the present invention as compared with the prior art.

[0124] More specifically, the switch matrix 640 can be controlled such that the terminal 612 is connected to a given node N k Thereby, the current I output at the terminal 612 BAL is supplied to the second group G2, and the current I BATTERY -I IN +I BAL will flow.

[0125] Following the numerical example described above, when charge is moved from G1 to G2, as a result, I IN becomes a positive value. Also, although the present invention is not limited to this, for simplicity, when I BATTERY is equal to zero, as a result, the units U of the first group k+1 ~U N are discharged by the current I IN and the units U1 to U of the second group k are charged by the current I IN +I BAL will be charged.

[0126] In other words, by connecting the DC / DC converter to a given node N k it is possible to move charge between the groups G1 and G2.

[0127] As shown in FIG. 3(A), after step S350, the movement of charge can be stopped and the method 300 can be started again. This leads to the convergence of the units. In particular, the repeated execution of steps S310, S320, S330, and S350 brings about the convergence of the units regardless of their initial configuration.

[0128] This is generally understandable from the above description. By moving charge from a group of units with a higher average charge to a group of units with a lower average charge, the method ultimately converges the units.

[0129] Figure 8 shows BAT1 , V BAT2 , V BAT3 , V BAT4 An exemplary configuration with four units starting from different voltages, namely V

[0130] In particular, in this example, it is clear that in the first cycle, energy is first transferred from the three units with the highest voltage to the unit with the lowest voltage. At about 300 ms, the change in the node with the maximum error E MAX changes the definition of the group, and accordingly, the charge transfer changes to move from the unit with the highest charge to the three units with lower charges until convergence. It should be noted that this depends on the specific numerical values used as an example and is only one of many possible developments in the values of the units. The purpose of Figure 8 is only to show how the definition of the group can change over time and how the above method can lead to convergence.

[0131] Figure 8 further schematically shows an exemplary embodiment of step S340, in which the charge transfer is stopped when the maximum error falls below a threshold value, indicating that a state where it is considered to have converged sufficiently has been reached.

[0132] In the description of the above method 300, it was assumed that step S350 is performed for a given period and / or a given amount of charge transfer. How this can be implemented will be apparent to those skilled in the art. As also shown in Figure 8, it can be clearly recognized that the charge transfer is controlled step by step.

[0133] As an example of a possible embodiment for implementing this, methods 400 and 500 are referred to.

[0134] In particular, as shown in FIG. 4, method 400 can be more generally configured such that, before method 400 including measuring characteristics in step S310 and calculating a new set of error values in step S320 is restarted, step S350 of moving charge is executed for a predetermined time and then stopped.

[0135] It will be apparent to those skilled in the art that the time limit up to step S350 can be obtained in a plurality of manners, generally based on an instruction given by a timer. In the embodiment of FIG. 4, this is achieved by starting the timer in step S460 at any point before step S350, preferably at a point between steps S340 and S350. Thereafter, corrections can be executed during the execution of the timer, and in step S470, it can be confirmed whether the timer has reached a predetermined value. In that case, in step S480, the corrections can be stopped and preferably the timer can be reset. Otherwise, the corrections can be continued until the timer reaches a predetermined value.

[0136] The value of the timer can be a predetermined value. In a preferred embodiment, the predetermined value can be at least 1 ms, preferably at least 10 ms. Alternatively, or in addition, the predetermined value can be at most 1 s, preferably at most 100 ms. The inventors have found that these values are particularly advantageous in that they enable the reliability of the unit and rapid convergence, while ensuring that the movement of charge does not lead to overcharging or undercharging of the unit.

[0137] Alternatively, the value of the timer can be calculated as a function of the maximum error E MAX and / or as a function of the correction value. Preferably, in some embodiments, the predetermined value of the timer is the maximum error E MAXand / or a bijective correspondence with the correction value. Even more preferably, the maximum error E MAX and / or as the correction value increases, the predetermined value of the timer increases, and / or the maximum error E MAX and / or as the correction value decreases, the predetermined value of the timer may decrease.

[0138] The presence of the timer ensures that the method is repeated multiple times, and the balance of the unit converges. In particular, the execution of the repetition of method 400 will result in the repeated calculation of the error, which may be different for each cycle. Thus, this may result in different corrections being made for each cycle, but as will be explained below, the unit converges to a balanced state. This also applies to the other methods described, particularly methods 300 and 500.

[0139] Alternatively, or in addition, as shown in FIG. 5, the step S350 of moving the charge may be executed until the value of the maximum error E MAX is lower than a predetermined value. In particular, in step S570, a check may be performed to determine whether the value of the maximum error E MAX is lower than a predetermined value. In that case, the method may proceed to step S480 where the correction is stopped.

[0140] It will be apparent to those skilled in the art that the method of the present invention may include both steps S470 and S570. In a preferred embodiment, these two checks may be performed since both need to be satisfied before the method reaches step S480. Alternatively, in some embodiments, these two checks may be performed such that only one of them needs to be satisfied before the method reaches step S480.

[0141] In a specific exemplary embodiment, with reference to the above definition of the error E, preferably when the error E is calculated based on voltage, correction can be performed by balancing the voltage. In this case, the DC / DC converter 210 can be controlled to apply a voltage or current to a given node such that the voltage error at a given unit or node is kept lower than a predetermined threshold and / or over a predetermined time.

[0142] In a more specific exemplary embodiment, with reference to the above definition of the error E, preferably when the error E is calculated based on the SoC, correction can be performed by balancing the SoC. In this case, the DC / DC converter 210 can be controlled to apply a voltage or current to a given node such that the SoC error at a given unit or node is kept lower than a predetermined threshold and / or over a predetermined time.

[0143] In a still more specific exemplary embodiment, with reference to the above definition of the error E, preferably when the error E is calculated based on the absolute value of charge, correction can be performed by taking an absolute charge balance. In this case, the DC / DC converter 210 can be controlled to apply a voltage or current to a given node such that the charge error at a given unit or node is kept lower than a predetermined threshold and / or over a predetermined time.

[0144] It will be appreciated that in all cases, methods 300, 400, 500 can be repeated a plurality of times, advantageously leading to convergence of unit balancing.

[0145] In the above embodiments, the DC / DC converter is generally shown to move charge from one group to another. The amount of charge moved per unit time and / or the total amount of charge moved, i.e., the current I IN and I BALThe value of can be controlled in various ways by a DC / DC converter. For example, the DC / DC converter can be controlled to move a predetermined amount of charge every cycle, that is, every application of step S350.

[0146] Alternatively, or in addition, in some embodiments, as shown in FIG. 3(B), step S350 may also include a step S351 of calculating a correction coefficient and a step S352 of configuring the DC / DC converter to perform charge transfer based on the correction coefficient.

[0147] In particular, in some embodiments, the correction coefficient can be calculated based on the maximum error value E MAX . Preferably, the correction coefficient can be expressed as f(E MAX ). Here, f can be a bijective function, more preferably a monotonic bijective function. Even more preferably, as the maximum error value E MAX increases, the correction coefficient can increase, and vice versa.

[0148] Once calculated, the correction coefficient can be used to determine the value of I BAL and / or to determine the duration of the timers in steps S460 and S470.

[0149] In particular, in some embodiments, the value of I BAL can be expressed as f(correction coefficient). Here, f can be a bijective function, even more preferably a monotonic bijective function. Even more preferably, as the correction coefficient increases, the value of I BAL can increase, and vice versa.

[0150] Similarly, in some embodiments, the duration of the timer can be expressed as f(correction coefficient). Here, f can be a bijective function, even more preferably a monotonic bijective function. Even more preferably, as the correction coefficient increases, the duration of the timer can increase, and vice versa.

[0151] In the description of the above embodiment, the DC / DC converter is generally described as a bidirectional DC / DC converter including two terminals 611 and 613 that act as a first input or output according to the operation direction of conversion, and two terminals 612 and 613 that act as a second output or input, respectively.

[0152] Terminals 611 and 613 are preferably fixedly connected to the battery, preferably to the positive terminal and the negative terminal, respectively. On the other hand, terminal 612 can be connected to any node N between the positive terminal and the negative terminal via the switch matrix 640. k It can be connected.

[0153] It will be apparent to those skilled in the art that several configurations can be selected to implement the DC / DC converter 210. FIG. 7 schematically shows a possible implementation 710 of the DC / DC converter.

[0154] In this implementation, the DC / DC converter 710 includes two switching means 714 and 715, which are two transistors connected in series at a common node. At this common node, the DC / DC converter 710 includes a connection to the inductor 716. The operation of the DC / DC converter 710 can be based on the indicated value of the current flowing through the switching means 714 shown as I, and / or can be based on the indicated value of the current flowing through the inductor 716 shown as I, in a method known per se. In the embodiment, these indicated values are respectively provided to the control unit 220 as I, and I, via two respective detection means 717 and 718. However, it is obvious that alternative implementations are possible by those skilled in the art. IN and can be based on the indicated value of the current flowing through the switching means 714 shown as I, and / or BAL and can be based on the indicated value of the current flowing through the inductor 716 shown as I. IN_SENSE and, BAL_SENSE and are respectively provided to the control unit 220 as I. However, it is obvious that alternative implementations are possible by those skilled in the art.

[0155] One advantage of this implementation is that only one inductor 716 is used, and when implemented with the configuration shown in FIG. 6, one switch SW for each given node N k eachk The switch matrix 640 having only [the relevant component] is used. Therefore, this implementation is particularly simple and cost-effective.

[0156] A further advantage is that the output current is controlled to apply a correction to a given node N. k This has the advantage that it is not necessary to physically detect the output voltage at node N, which may require additional detection wiring. k

[0157] Although several embodiments having various features have been discussed and / or illustrated, it will be apparent to those skilled in the art that the present invention is not limited to a particular combination of these features. Instead, further embodiments can be obtained by combining features, within the scope of the claims, separately from one or more embodiments.

Explanation of Signs

[0158] B Battery C1~C N Cell Device for active balancing of 200 batteries 210 DC / DC converter 220 Control unit 230, S1~S N Detection means U1~U N Battery unit 300 Active balancing method for batteries S310 Characteristic measurement step S320 Error value calculation step S330 Maximum error identification step S340 Maximum error confirmation step S350 Charge transfer step S351 Correction coefficient calculation step S352 Charge transfer step 400 Active balancing method for batteries S460 Timer start step S470 Timer confirmation step S480 Correction stop step 400 Active balancing method for battery S570 Correction confirmation step 610 DC / DC converter 611 Positive terminal 612 Terminal 613 Negative terminal 640 Switching means N1~N N Node G1~G N Group 710 DC / DC converter 714, 715 Switching means 716 Inductor 717, 718 Switching means

Claims

1. A device (200, 800) for active balancing of a battery (B) including a plurality of units (U 1 ~N N-1 ) connected in series in a plurality of nodes (N 1 ~U N ), At least one DC / DC converter (210, 610, 710, 810 1 ~U N ), of the plurality of units (U 1 ), is configured to transfer charge between a first group (G 1 ~U N ), of the plurality of units (U 2 ), and a second group (G 1 ~810 N ). Said first group (G 1 ) and at least one of said second group (G 2 ) includes a plurality of said units (U 1 to U N ), The said first group (G 1 ), the plurality of units (U 1 ~U N ), are different from the plurality of units (U 2 ) of the said second group (G 1 ~U N ). The DC / DC converters (210, 610, 710, 810 1 ~810 N ) are configured to transfer charges between the plurality of units (U 1 ~U 1 ) in the first group (G N ) and the plurality of units (U 2 ~U 1 ) in the second group (G N ). The apparatus further comprises a plurality of detection means (230, S1 to SN), each configured to measure at least one characteristic of each of the plurality of units (U1 to UN) and output each of the measured plurality of characteristics. The apparatus further comprises a control unit (220) configured to control the operation of the DC / DC converter (210, 610, 710, 8101 to 810N) based on the plurality of measured characteristics. The control unit (220) is configured to execute a balancing method (300, 400, 500) for the plurality of units. The balancing method (300, 400, 500) comprises: a step (S310) of controlling the plurality of detection means (230) to measure at least one of the characteristics of the plurality of units (U1 to UN); a step (S320) of calculating an error value for each of the plurality of nodes (N1 to NN-1); a step (S330) of identifying a maximum error (EMAX) among the plurality of error values; a step (S350) of moving charges between the first group (G1) and the second group (G2) set based on the node (Nk) related to the maximum error (EMAX) by controlling the DC / DC converter (210, 610, 710). The apparatus (200, 800) for active balancing of a battery (B) includes the above steps.

2. At least one of the plurality of units (U 1 ~U N ) is the apparatus (200, 800) for active balancing of the battery according to claim 1, which corresponds to a physical battery cell.

3. At least one of the plurality of units (U 1 ~U N ) corresponds to a plurality of physical battery cells connected in parallel and / or in series with each other, and is the apparatus (200, 800) for active balancing of the battery according to claim 1.

4. At least one of the characteristics includes voltage, current, state of charge, state of health, charge amount, temperature, or one or more of them. The apparatus (200, 800) for active balancing of a battery according to Claim 1.

5. The plurality of detection means (230, S 1 ~S N ) is configured to wirelessly transmit the plurality of measured characteristics, and the apparatus (200, 800) for active balancing of a battery according to claim 1.

6. The error value is set so that the node (N MAX ), is identifiable by the maximum error (E k ). The identified node (N k ) includes a step of measuring the characteristic (S310), a step of calculating the error value (S320), a step of identifying the maximum error (E MAX )(S330), and a step of moving the charge between the first group (G 1 ) and the second group (G 2 )(S350). When the above steps are executed multiple times, the plurality of units (U 1 to U N ) converge to an equilibrium value. The apparatus (200, 800) for active balancing of a battery according to claim 1, which divides the plurality of units (U 1 to U N ) into the first group (G 1 ) and the second group (G 2 ).

7. The error value is The average of at least one of the characteristics of the second group (G 2 ), and a function of the difference between the average of at least one of the characteristics of the plurality of units (U 1 to U N ), and / or The average of at least one of the characteristics of the second group (G 2 ), and a function of the difference between the average of at least one of the characteristics of the first group (G 1 ), the apparatus (200, 800) for active balancing of a battery according to claim 1.

8. The step (S350) of moving charges between the first group (G 1 ) and the second group (G 2 ) is stopped after being executed for a predetermined time. The apparatus (200, 800) for active balancing of a battery according to claim 1.

9. The step (S350) of moving charges between the first group (G 1 ) and the second group (G 2 ) is executed until the maximum error (E MAX ) becomes smaller than a predetermined value. The apparatus (200, 800) for active balancing of a battery according to claim 1.

10. The DC / DC converter (610, 710) includes a first terminal (611) and a second terminal (612). The DC / DC converters (610, 710, 810 1 ~810 N ) are configured to convert the first DC voltage supplied to the first terminal into a second DC voltage and supply it to the second terminal, and are similarly configured to perform the reverse operation. The DC / DC converters (610, 710, 810 1 ~810 N ) are configured such that when connected to the plurality of units (U 1 ~U N ), the first terminal (611) is connected to the positive terminal of the plurality of units (U 1 ~U N ), and the second terminal (612) is configured to be connectable to any one of the plurality of nodes (N 1 ~N N-1 ). The apparatus (200, 800) for active balancing of a battery according to any one of claims 1 to 3.

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