US20130207663A1 - Arrangement for Measuring a Single Cell in a Rechargeable Battery Pack and Rechargeable Battery Pack Comprising such an Arrangement - Google Patents
Arrangement for Measuring a Single Cell in a Rechargeable Battery Pack and Rechargeable Battery Pack Comprising such an Arrangement Download PDFInfo
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- US20130207663A1 US20130207663A1 US13/698,711 US201113698711A US2013207663A1 US 20130207663 A1 US20130207663 A1 US 20130207663A1 US 201113698711 A US201113698711 A US 201113698711A US 2013207663 A1 US2013207663 A1 US 2013207663A1
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- arrangement
- measuring
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- cells
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- G01R31/3606—
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
- G01R31/396—Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
- G01R19/16533—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values characterised by the application
- G01R19/16538—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values characterised by the application in AC or DC supplies
- G01R19/16542—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values characterised by the application in AC or DC supplies for batteries
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
- G01R31/382—Arrangements for monitoring battery or accumulator variables, e.g. SoC
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/44—Methods for charging or discharging
- H01M10/441—Methods for charging or discharging for several batteries or cells simultaneously or sequentially
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/48—Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte
- H01M10/482—Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte for several batteries or cells simultaneously or sequentially
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Definitions
- the invention relates to an arrangement for measuring a single cell in a rechargeable battery pack, and wherein the rechargeable battery pack comprises a series circuit composed of a plurality of cells, and wherein further two adjacent cells are electrically connected to one another by means of a connecting branch, and wherein the arrangement has a measuring device and which further comprises a switching device, and which is equipped to selectively connect exactly one connecting branch to a measuring input of the measuring device.
- the invention also relates to a rechargeable battery pack which has such an arrangement.
- An arrangement for measuring a single cell having a switching device and a measuring device is generally known.
- the measuring device is equipped for measuring an electrical potential relative to a minus pole of a series circuit of the cells.
- the switching device successively connects the plus poles of the individual cells of the rechargeable battery pack to a measuring input of the measuring device. In this way, the electrical potential on the plus pole of the individual cells can be measured successively.
- the mean measuring current varies from cell to cell.
- a different electrical charge is taken from each cell. Over the course of time, this causes the individual cells to become differently charged as a result of the measuring cycles, which can lead to a debalancing of the charge state of the individual cells.
- the present invention is therefore based on the object of specifying an arrangement for measuring a single cell, or a rechargeable battery pack in which such an arrangement is integrated, with which the debalancing of the charge state of the individual cells as a result of the measurements by means of the measuring device is at least substantially prevented.
- an arrangement for measuring cells of the kind mentioned in the introduction which is characterized in that the arrangement has at least one load arranged between two connecting branches.
- the load can selectively be brought into an activated operating state or into a deactivated operating state by means of a control signal such that electric charge can be taken from at least one cell during the activated operating state by means of the load.
- the arrangement has a control device which is equipped to generate the control signal for activating and deactivating at least one load, so that a non-uniform discharge of the cells as a result of a measuring current at the measuring input is at least substantially prevented when different connecting branches are successively connected to the measuring input.
- the control device can have a microcontroller with at least one digital output, for example, and wherein the digital output is connected to a drive input of the load.
- the at least one load is connected in parallel with exactly one cell.
- the load can therefore be connected to two adjacent connecting branches, and wherein the two adjacent connecting branches are connected to the plus pole and the minus pole respectively of the same cell.
- the measuring device is equipped for measuring a voltage between the measuring input and a reference point within the series circuit, and wherein the reference point is electrically connected to a terminal of the measuring device.
- all cells of the rechargeable battery pack belong to the series circuit and/or an outer end of the series circuit, and preferably a minus pole of an outer cell of the series circuit, forms the reference point.
- the reference point can therefore be a ground conductor of the arrangement, for example.
- the ground conductor can be connected to the minus pole of that cell of the series circuit whose minus pole is not connected to another cell. This ensures that the ground potential is the lowest potential within the series circuit, and the measuring device normally only has to measure positive potentials with respect to the ground potential.
- a load is only associated with those cells which are indirectly connected to the reference point. In other words, no load is associated with that cell whose minus pole or plus pole is connected directly to the reference point, for example the ground conductor.
- the load has at least one switching element which is electrically closed when the load is activated and electrically open when the load is deactivated, and wherein one of these switching elements simultaneously forms a switching element of the switching device.
- the at least one switching element can be a semiconductor switch, and preferably a bipolar transistor or a unipolar transistor. As one of the switching elements is used simultaneously for activating and deactivating the load and connecting a particular connecting branch to the measuring input, the number of components, and in particular transistors, which are required for building the arrangement for measuring cells, is kept low.
- the load can be realized particularly easily in that the load has a series circuit comprising a semiconductor switch, such as a transistor for example, and a resistor.
- the resistor can be an adjustable resistor or a fixed resistor.
- the series circuit also has a semiconductor diode which is connected upstream or downstream of the resistor.
- a rechargeable battery pack having an arrangement for measuring a single cell
- the rechargeable battery pack comprises a series circuit composed of a plurality of cells, and wherein two adjacent cells are in each case electrically connected to one another by means of a connecting branch
- the arrangement has a measuring device and further comprises a switching device, which is equipped to selectively connect exactly one connecting branch to a measuring input of the measuring device.
- This rechargeable battery pack is characterized in that the arrangement has at least one load arranged between two connecting branches, and wherein the load can selectively be brought into an activated operating state or into a deactivated operating state by means of a control signal such that electric charge can be taken from at least one cell during the activated operating state by means of the load.
- the arrangement for measuring a single cell of the rechargeable battery pack is in the form of an arrangement according to the invention as claimed in one of the claims as provided herewith. This enables the advantages of the arrangement according to the invention for measuring a single cell to be also realized for the rechargeable battery pack according to the invention. Further characteristics and advantages of the invention can be seen from the following description in which exemplary embodiments of the invention are described in more detail with reference to the drawings.
- FIG. 1 shows a block circuit diagram of an electrical device with an arrangement for measuring a single cell according to a first preferred embodiment
- FIG. 2 shows a block circuit diagram of a detail of an arrangement for measuring a single cell according to a second preferred embodiment
- FIG. 3 shows an electrical device with a known arrangement for measuring a single cell.
- the known electrical device 11 which is shown in FIG. 3 has a series circuit 13 composed of a plurality of cells 14 as an energy source.
- ten cells 14 which are connected in series, are provided.
- the number of cells 14 can, however, be varied as required.
- the minus pole of a first outer cell 14 a which is shown at the bottom of FIG. 3 , is connected to a ground conductor 17 of the electrical device 11 .
- the plus pole of a second outer cell 14 b of the series circuit 13 , is connected to a supply voltage conductor 18 of the electrical device 11 .
- the individual cells 14 , 14 a , and 14 b are connected to one another by means of connecting branches 20 , and wherein in each case, a connecting branch 20 connects the plus pole of a cell 14 , and 14 a to the minus pole of the respectively adjacent cell 14 , and 14 b .
- the cells 14 are lithium ion rechargeable battery cells which have a nominal voltage of 4.1 V, so that the overall series circuit 13 has a nominal voltage of about 41 V.
- the electrical potential on the individual plus poles of the cells 14 is specified relative to a ground potential denoted by GND on the ground conductor 17 .
- each cell 14 , 14 a , and 14 b is connected to a common measuring conductor 21 by means of a separate switching element 19 , and a separate resistor RI, R 2 , R 3 , . . . , R 10 .
- the measuring conductor 21 is also connected to the ground conductor 17 by means of a resistor R 11 .
- the measuring conductor 21 is connected to a measuring input 22 of an analog-digital converter 23 of a control device 27 which is made integral with the electrical device 11 .
- An output of the analog-digital converter 23 is connected by means of an input to a microcontroller 25 of the control device 27 .
- the control device 27 is designed so that the microcontroller 25 can activate and deactivate the individual switching elements 19 , so that the appropriate plus poles of the individual cells 14 , 14 a , and 14 b can be selectively connected via the corresponding resistors RI, R 2 , R 3 , . . . , R 10 to the measuring conductor 21 , or alternatively, electrically isolated from the measuring conductor 21 , respectively.
- the switching elements 19 therefore, belong to a switching device for selectively connecting exactly one connecting branch 20 to the measuring input 22 .
- An output of the control device 27 is connected to a control input of a power output stage 29 of the electrical device 11 in such a way that the microcontroller 25 is able to drive the power output stage 29 .
- the power output stage 29 has a power switching element in the form of a semiconductor switch, for example, a MOSFET.
- a first terminal 31 of the power output stage 29 is connected to the ground conductor 17 .
- a consumer of the electrical device 11 for example, an electric motor 35 , is arranged between the supply voltage conductor 18 , and a second terminal 33 of the power output stage 29 , so that the consumer, that is to say the electric motor 35 , can either be connected to the series circuit 13 , or electrically isolated therefrom by means of the power switching element.
- the control device 27 regularly checks the state of the individual cells 14 , 14 a , and 14 b by driving the switching elements 19 so that they are electrically activated individually in succession, that is to say, the plus poles of the individual cells 14 , 14 a , and 14 b are connected successively to the measuring conductor 21 via the appropriate resistors RI, R 2 , R 3 , . . . , R 10 .
- R 10 which are electrically connected to the activated switching element 19 , and the resistor R 11 , form a voltage divider, and wherein the center tap of which is connected to the measuring input 22 of the analog-digital converter 23 .
- a voltage relative to the ground conductor 17 which is measured by the analog-digital converter 23 therefore, characterizes the potential on the plus pole of the particular cell 14 , 14 a , and 14 b .
- the microcontroller 25 Based upon the values measured by means of the analog-digital converter 23 , the microcontroller 25 , therefore, determines the potentials on the plus poles of the cells 14 , 14 a , and 14 b , and from these calculates the voltages on the individual cells 14 , 14 a , and 14 b by subtracting the electrical potentials on the plus poles of adjacent cells 14 , 14 a , and 14 b .
- the electrical potential on the plus pole of the first outer cell 14 a corresponds to its cell voltage, so that the aforementioned subtraction for calculating this cell voltage is not required.
- control device 27 carries out periodic measuring cycles for checking the individual cells 14 , 14 a , and 14 b at regular intervals.
- the control device 27 first electrically activates the switching element 19 which is connected to the resistor R 1 in order to measure the electrical potential on the plus pole of the first outer cell 14 a as shown at the bottom in FIG. 3 .
- the control device then electrically opens the switching element 19 once more and closes that switching element 19 which is connected to the plus pole of the adjacent cell 14 , and which has not yet been activated in the measuring cycle under consideration.
- the switching elements 19 are therefore activated successively in turn.
- time t meas corresponds to a measuring duration, that is to say, the time for which one of the switching elements 19 is electrically activated.
- the measured current, I meas corresponds to the current which flows through the respective switching element 19 . Consequently, the mean value of a current through a particular cell i is:
- the index i designates the individual cells 14 , 14 a , and 14 b .
- the measuring cycles are carried out periodically at intervals of once per second, this results in a non-uniform electrical discharge of the individual cells, which can lead to a debalancing of the charge state of the individual cells 14 , 14 a , and 14 b.
- FIG. 1 shows the block circuit diagram of an electrical device 11 , for example, an electric tool, with which the non-uniform discharge of the rechargeable battery cells 14 , 14 a , and 14 b is at least substantially prevented.
- the same reference numerals are used for the same elements as seen in FIG. 3 , and these elements are therefore not explained in significant detail, again.
- the electrical device 11 as shown in FIG. 1 includes a load 37 , which the control device 27 can selectively electrically activate and deactivate, and which is further associated with each cell 14 , and 14 b , with the exception of the first cell 14 a .
- the load 37 is connected to two adjacent connecting branches 20 , that is to say, it is arranged in parallel with the appropriate cell 14 , and 14 b .
- Each load 37 is, therefore, arranged between the minus pole of the appropriate cell 14 , and 14 b , and a connecting point between the switching elements 19 , and the respective resistor R 1 and R 2 , . . . R 10 .
- Each load 37 has a further switching element 39 , and a load resistor R v which is connected in series therewith.
- the electrical device 11 is equipped so that exactly when a particular switching element 19 is electrically activated, the further switching element 39 associated with the same cell 14 , and 14 b is also activated.
- the control device 27 therefore, and at least substantially simultaneously electrically activates, and deactivates, the switching elements 19 , 39 .
- the elements 19 , R 1 , . . . , R 10 , R v , 39 , 21 , R 11 and 27 form an arrangement 41 , for checking the individual cells 14 a , 14 , and 14 b , for example, by measuring voltages on the individual cells 14 a , 14 , and 14 b .
- the load resistors R v can be adjustable resistors, for example, which are calibrated before the electrical device 11 is used for the first time. As an alternative to this, appropriately sized fixed resistors can also be provided for the load resistors R v .
- the second outer cell 14 b In order to achieve a uniform discharge of the individual cells 14 , 14 a , and 14 b as a result of the measuring cycles, the second outer cell 14 b must be loaded with a relatively large additional electrical current I 110 , and whereas the first outer cell 14 a does not have to be loaded with an additional electrical current.
- the arrangement 41 is part of a rechargeable battery pack 43 , which, apart from the arrangement 41 , also contains the series circuit 13 of the cells 14 a , 14 , and 14 b .
- the control device 27 with the analog-digital converter 23 , and the microcontroller 25 , can also be integrated in the rechargeable battery pack 43 .
- a further control device (not shown) for driving the power output stage 29 can be provided in the electrical device 11 , but outside the rechargeable battery pack 43 .
- FIG. 2 shows a block circuit diagram of a portion of the arrangement 41 for measuring a single cell according to a further embodiment.
- the switching element 19 is in the form of a semiconductor switching element with bipolar transistors T 1 and T 2 .
- the emitter of the PNP transistor T 1 is connected to the plus pole of the appropriate cell 14 .
- a collector of this transistor T 1 is electrically connected to the measuring conductor 21 via the resistor R 2 , . . . , R 10 .
- a base-emitter resistor 45 is arranged between the base and emitter of the transistor T 1 .
- the base of the transistor T 1 is also connected via a base resistor 47 to the collector of a drive transistor T 2 and which is in the form of an NPN transistor.
- An emitter terminal of the drive transistor T 2 is electrically connected to the ground conductor 17 .
- the base of the drive transistor T 2 is electrically connected to a digital output of the microcontroller 25 via a series resistor 49 .
- a switching element in the form of the transistor T 1 , and the associated drive circuit in the form of the transistor T 2 , and the resistors 45 , 47 , and 49 is associated with each cell 14 , 14 b , with the exception of the first outer cell 14 a .
- the microcontroller 25 has a digital output which is electrically connected to the series resistor 49 of exactly one transistor T 2 , so that the microcontroller 25 can drive the transistors T 2 separately from one another.
- the load 37 has a series circuit composed of a semiconductor diode 51 , and the load resistor R v .
- the transistor T 1 is not only used to electrically connect connecting branches 20 to the measuring conductor 21 which is shown at the top of FIG. 2 , but also is used to electrically activate and deactivate the load 37 . That is to say, the transistor T 1 not only forms the switching element 19 of the switching device, but at the same time is a switching element of the activatable and deactivatable load 37 .
- the load 37 is only associated with the cells 14 , and 14 b , and not with the first outer cell 14 a . Furthermore, in the embodiment of the invention which is shown in FIG. 2 , a damping capacitor C 1 is electrically connected in parallel with the resistor R 11 .
- the control signal s i is a digital signal, which can assume two stable states, namely a low level (low), and a high level (high).
- the switching element 19 is activated exactly when the control signal si is at the high level.
- the resistors R 1 , . . . , R 10 , R 11 are preferably designed so that an electrical potential which is not greater than the electrical potential on the plus pole of the second cell 14 that is to say, on that cell 14 which is adjacent to the first outer cell 14 a is established at the measuring input 22 , plus a forward voltage of that diode 51 , which is associated with the second cell 14 . This prevents transverse currents between the plus poles of the individual cells 14 , 14 b .
- the resistors R 1 , . . . , R 10 , R 11 are sized so that the potential on the measuring input 22 is approximately 0 V to 5 V with respect to GND.
- the present invention provides the arrangement 41 for measuring a single cell or the rechargeable battery pack 43 , and which substantially prevents a non-uniform discharge, and therefore a debalancing of the charge state of the individual cells 14 , 14 a , and 14 b as a result of the measurements on the individual cells 14 a , 14 , and 14 b .
- the reliable operation of the individual cells 14 , 14 a , and 14 b , or the rechargeable battery pack 43 is ensured, particularly when the cells 14 , 14 a , and 14 b are neither electrically charged, nor discharged over a longer period, but are merely monitored by the arrangement 41 .
Abstract
An arrangement for measuring a single cell in a rechargeable battery pack is described, and which includes a plurality of cells coupled in a series circuit, and wherein adjacent cells are electrically coupled to a connecting branch, and a measuring device comprising a switch is provided, and which selectively electrically connects one connecting branch to a measuring input of the measuring device.
Description
- The present application claims priority from German Application Serial No. 10 2010 021 176.1 and which was filed on May 21, 2010; and PCT Application Serial No. PCT/EP2011/058138 and which was filed on May 19, 2011.
- The invention relates to an arrangement for measuring a single cell in a rechargeable battery pack, and wherein the rechargeable battery pack comprises a series circuit composed of a plurality of cells, and wherein further two adjacent cells are electrically connected to one another by means of a connecting branch, and wherein the arrangement has a measuring device and which further comprises a switching device, and which is equipped to selectively connect exactly one connecting branch to a measuring input of the measuring device. The invention also relates to a rechargeable battery pack which has such an arrangement.
- An arrangement for measuring a single cell having a switching device and a measuring device is generally known. With this arrangement, the measuring device is equipped for measuring an electrical potential relative to a minus pole of a series circuit of the cells. During a measuring cycle, the switching device successively connects the plus poles of the individual cells of the rechargeable battery pack to a measuring input of the measuring device. In this way, the electrical potential on the plus pole of the individual cells can be measured successively.
- Every time the electrical potential on a particular plus pole is measured, a certain subset of the cells of the rechargeable battery pack is loaded with a certain measuring current. With the known arrangement, the mean measuring current varies from cell to cell. Within a measuring cycle, in which the electrical potential on the plus pole of each cell is measured, a different electrical charge is taken from each cell. Over the course of time, this causes the individual cells to become differently charged as a result of the measuring cycles, which can lead to a debalancing of the charge state of the individual cells. Particularly, and in the case where the rechargeable battery pack is neither discharged by a working load, such as an electric motor of an electrical device for example, nor charged by means of a charging circuit, this results in the fact that, due to the debalancing of the charge state of the individual cell as a result of the monitoring, a separate charging process is required to match the charging states of the individual cells to one another once more. This in turn leads to an increased number of charging cycles and therefore to increased wear of the individual cells of the rechargeable battery pack.
- The present invention is therefore based on the object of specifying an arrangement for measuring a single cell, or a rechargeable battery pack in which such an arrangement is integrated, with which the debalancing of the charge state of the individual cells as a result of the measurements by means of the measuring device is at least substantially prevented.
- The foregoing stated object is achieved by an arrangement for measuring cells of the kind mentioned in the introduction which is characterized in that the arrangement has at least one load arranged between two connecting branches. The load can selectively be brought into an activated operating state or into a deactivated operating state by means of a control signal such that electric charge can be taken from at least one cell during the activated operating state by means of the load.
- In doing so, it can be provided that the arrangement has a control device which is equipped to generate the control signal for activating and deactivating at least one load, so that a non-uniform discharge of the cells as a result of a measuring current at the measuring input is at least substantially prevented when different connecting branches are successively connected to the measuring input. The control device can have a microcontroller with at least one digital output, for example, and wherein the digital output is connected to a drive input of the load.
- It is particularly preferred that the at least one load is connected in parallel with exactly one cell. The load can therefore be connected to two adjacent connecting branches, and wherein the two adjacent connecting branches are connected to the plus pole and the minus pole respectively of the same cell.
- In order to achieve a simple design of the arrangement, it is preferred that the measuring device is equipped for measuring a voltage between the measuring input and a reference point within the series circuit, and wherein the reference point is electrically connected to a terminal of the measuring device.
- Further, it is preferred that all cells of the rechargeable battery pack belong to the series circuit and/or an outer end of the series circuit, and preferably a minus pole of an outer cell of the series circuit, forms the reference point. The reference point can therefore be a ground conductor of the arrangement, for example. The ground conductor can be connected to the minus pole of that cell of the series circuit whose minus pole is not connected to another cell. This ensures that the ground potential is the lowest potential within the series circuit, and the measuring device normally only has to measure positive potentials with respect to the ground potential.
- In order to reduce the circuit complexity for the arrangement, it can be provided that a load is only associated with those cells which are indirectly connected to the reference point. In other words, no load is associated with that cell whose minus pole or plus pole is connected directly to the reference point, for example the ground conductor.
- It is preferred that the load has at least one switching element which is electrically closed when the load is activated and electrically open when the load is deactivated, and wherein one of these switching elements simultaneously forms a switching element of the switching device. The at least one switching element can be a semiconductor switch, and preferably a bipolar transistor or a unipolar transistor. As one of the switching elements is used simultaneously for activating and deactivating the load and connecting a particular connecting branch to the measuring input, the number of components, and in particular transistors, which are required for building the arrangement for measuring cells, is kept low.
- The load can be realized particularly easily in that the load has a series circuit comprising a semiconductor switch, such as a transistor for example, and a resistor. The resistor can be an adjustable resistor or a fixed resistor.
- At the same time, it can be provided that the series circuit also has a semiconductor diode which is connected upstream or downstream of the resistor.
- As a further solution which relates to the object specified, above, a rechargeable battery pack having an arrangement for measuring a single cell is proposed, and wherein the rechargeable battery pack comprises a series circuit composed of a plurality of cells, and wherein two adjacent cells are in each case electrically connected to one another by means of a connecting branch, and wherein the arrangement has a measuring device and further comprises a switching device, which is equipped to selectively connect exactly one connecting branch to a measuring input of the measuring device. This rechargeable battery pack according to the teachings of the present invention is characterized in that the arrangement has at least one load arranged between two connecting branches, and wherein the load can selectively be brought into an activated operating state or into a deactivated operating state by means of a control signal such that electric charge can be taken from at least one cell during the activated operating state by means of the load.
- It is preferred that the arrangement for measuring a single cell of the rechargeable battery pack is in the form of an arrangement according to the invention as claimed in one of the claims as provided herewith. This enables the advantages of the arrangement according to the invention for measuring a single cell to be also realized for the rechargeable battery pack according to the invention. Further characteristics and advantages of the invention can be seen from the following description in which exemplary embodiments of the invention are described in more detail with reference to the drawings. In the drawings:
-
FIG. 1 shows a block circuit diagram of an electrical device with an arrangement for measuring a single cell according to a first preferred embodiment; -
FIG. 2 shows a block circuit diagram of a detail of an arrangement for measuring a single cell according to a second preferred embodiment; and -
FIG. 3 shows an electrical device with a known arrangement for measuring a single cell. - The known
electrical device 11 which is shown inFIG. 3 has aseries circuit 13 composed of a plurality ofcells 14 as an energy source. In the example as shown, tencells 14 which are connected in series, are provided. The number ofcells 14 can, however, be varied as required. The minus pole of a firstouter cell 14 a, which is shown at the bottom ofFIG. 3 , is connected to aground conductor 17 of theelectrical device 11. The plus pole of a secondouter cell 14 b, of theseries circuit 13, is connected to asupply voltage conductor 18 of theelectrical device 11. Theindividual cells branches 20, and wherein in each case, a connectingbranch 20 connects the plus pole of acell adjacent cell cells 14 are lithium ion rechargeable battery cells which have a nominal voltage of 4.1 V, so that theoverall series circuit 13 has a nominal voltage of about 41 V. InFIG. 3 , the electrical potential on the individual plus poles of thecells 14 is specified relative to a ground potential denoted by GND on theground conductor 17. - The plus pole of each
cell common measuring conductor 21 by means of aseparate switching element 19, and a separate resistor RI, R2, R3, . . . , R10. Themeasuring conductor 21 is also connected to theground conductor 17 by means of a resistor R11. Furthermore, themeasuring conductor 21 is connected to ameasuring input 22 of an analog-digital converter 23 of acontrol device 27 which is made integral with theelectrical device 11. An output of the analog-digital converter 23 is connected by means of an input to amicrocontroller 25 of thecontrol device 27. Thecontrol device 27 is designed so that themicrocontroller 25 can activate and deactivate theindividual switching elements 19, so that the appropriate plus poles of theindividual cells measuring conductor 21, or alternatively, electrically isolated from themeasuring conductor 21, respectively. Theswitching elements 19, therefore, belong to a switching device for selectively connecting exactly one connectingbranch 20 to themeasuring input 22. - An output of the
control device 27 is connected to a control input of a power output stage 29 of theelectrical device 11 in such a way that themicrocontroller 25 is able to drive the power output stage 29. The power output stage 29 has a power switching element in the form of a semiconductor switch, for example, a MOSFET. Afirst terminal 31 of the power output stage 29 is connected to theground conductor 17. A consumer of theelectrical device 11, for example, anelectric motor 35, is arranged between thesupply voltage conductor 18, and asecond terminal 33 of the power output stage 29, so that the consumer, that is to say theelectric motor 35, can either be connected to theseries circuit 13, or electrically isolated therefrom by means of the power switching element. - When the
electrical device 11 is operating, thecontrol device 27 regularly checks the state of theindividual cells switching elements 19 so that they are electrically activated individually in succession, that is to say, the plus poles of theindividual cells measuring conductor 21 via the appropriate resistors RI, R2, R3, . . . , R10. The resistors RI, R2, R3, . . . , R10 which are electrically connected to the activated switchingelement 19, and the resistor R11, form a voltage divider, and wherein the center tap of which is connected to the measuringinput 22 of the analog-digital converter 23. A voltage relative to theground conductor 17 which is measured by the analog-digital converter 23, therefore, characterizes the potential on the plus pole of theparticular cell digital converter 23, themicrocontroller 25, therefore, determines the potentials on the plus poles of thecells individual cells adjacent cells outer cell 14 a corresponds to its cell voltage, so that the aforementioned subtraction for calculating this cell voltage is not required. - In detail, the
control device 27 carries out periodic measuring cycles for checking theindividual cells control device 27 first electrically activates the switchingelement 19 which is connected to the resistor R1 in order to measure the electrical potential on the plus pole of the firstouter cell 14 a as shown at the bottom inFIG. 3 . The control device then electrically opens the switchingelement 19 once more and closes that switchingelement 19 which is connected to the plus pole of theadjacent cell 14, and which has not yet been activated in the measuring cycle under consideration. The switchingelements 19 are therefore activated successively in turn. - In the course of the measuring cycle, this results successively in the measured currents Im1, Im2, Im3, . . . , Im10 which flow through the respective resistors R1, . . . , R10. As each switching
element 19 is activated exactly once in the course of the measuring cycle, ten times the measured current Im1, . . . , Im10 flows through thecell 14 a shown at the bottom inFIG. 3 , and whereas only one times the measured current Im10 flows through the cell shown at the top inFIG. 3 . As a result, considerably more charge is taken from thecell 14 a, for example, during a measuring cycle as a result of the measurements than from thecell 14 b say, thus resulting in variations in charge state of theindividual cells individual cells series circuit 13. The risk of debalancing exists particularly when thecells series circuit 13 are not charged, or are only slightly charged, or are discharged, that is to say, when theelectrical device 11 is not operated for a longer period but the cells are still monitored. - If the resistors R1 to R10 are sized so that the measured currents Im1 to Im10 have at least substantially the same magnitude, Imeas=Im1= . . . =Im10, then the charge which is taken from the cell i=1, . . . , 10 during a measuring cycle is:
-
Q i=(11−i)*t meas *I meas, - and where the time tmeas corresponds to a measuring duration, that is to say, the time for which one of the switching
elements 19 is electrically activated. The measured current, Imeas, corresponds to the current which flows through therespective switching element 19. Consequently, the mean value of a current through a particular cell i is: -
I mean ,I=Qi/T, - and where the interval T, designates the duration of a whole measuring cycle. In both equations given, above, the index i designates the
individual cells outer cell 14 a which is shown at the bottom inFIG. 3 , and the index i=10 corresponds to the second,outer cell 14 b which is shown at the top inFIG. 3 . The further indices i=2, . . . , 9 designate thecells 14, and which lie between thecells FIG. 3 ). - If a measuring current Imeas=Im1= . . . =Im10=0.41 mA, and a measuring duration of tmeas=1 ms are assumed, then, in one measuring cycle, a charge of Q1=4.1 μAs is taken from the first
outer cell 14 a (i=1), and whereas only a charge of Q10=0.41 μAs is taken from the secondouter cell 14 b (i=10). If the measuring cycle is carried out once per second, then, as a result of the measurements, a charge of 354.24 mAs will be taken from the firstouter cell 14 a, and a charge of 35.42 mAs will be taken from the secondouter cell 14 b. - If the measuring cycles are carried out periodically at intervals of once per second, this results in a non-uniform electrical discharge of the individual cells, which can lead to a debalancing of the charge state of the
individual cells -
FIG. 1 shows the block circuit diagram of anelectrical device 11, for example, an electric tool, with which the non-uniform discharge of therechargeable battery cells FIG. 1 , the same reference numerals are used for the same elements as seen inFIG. 3 , and these elements are therefore not explained in significant detail, again. Unlike the knownelectrical device 11 as shown inFIG. 3 , theelectrical device 11 as shown inFIG. 1 , includes aload 37, which thecontrol device 27 can selectively electrically activate and deactivate, and which is further associated with eachcell first cell 14 a. Theload 37 is connected to two adjacent connectingbranches 20, that is to say, it is arranged in parallel with theappropriate cell load 37 is, therefore, arranged between the minus pole of theappropriate cell elements 19, and the respective resistor R1 and R2, . . . R10. - Each
load 37 has afurther switching element 39, and a load resistor Rv which is connected in series therewith. Theelectrical device 11 is equipped so that exactly when aparticular switching element 19 is electrically activated, the further switchingelement 39 associated with thesame cell control device 27 therefore, and at least substantially simultaneously electrically activates, and deactivates, the switchingelements - The
elements 19, R1, . . . , R10, Rv, 39, 21, R11 and 27 form anarrangement 41, for checking theindividual cells individual cells arrangement 41, theloads 37 cause an additional current I12, . . . , I110 to flow in addition to the actual measuring current Imeas=Im1, Im10 in all thecells first cell 14 a, so that theindividual cells cell electrical device 11 is used for the first time. As an alternative to this, appropriately sized fixed resistors can also be provided for the load resistors Rv. - In order to achieve a uniform discharge of the
individual cells outer cell 14 b must be loaded with a relatively large additional electrical current I110, and whereas the firstouter cell 14 a does not have to be loaded with an additional electrical current. The additional electrical currents must, therefore, have values which increase in the order of thecells series circuit 13 and which begin with the second cell (i=2), that is to say, I12< . . . <I110. Accordingly, the values of the load resistors, Rv, must have correspondingly decreasing values. - It should be understood that the
arrangement 41 is part of arechargeable battery pack 43, which, apart from thearrangement 41, also contains theseries circuit 13 of thecells control device 27, with the analog-digital converter 23, and themicrocontroller 25, can also be integrated in therechargeable battery pack 43. In this case, however, a further control device (not shown) for driving the power output stage 29 can be provided in theelectrical device 11, but outside therechargeable battery pack 43. -
FIG. 2 shows a block circuit diagram of a portion of thearrangement 41 for measuring a single cell according to a further embodiment. The switchingelement 19 is in the form of a semiconductor switching element with bipolar transistors T1 and T2. The emitter of the PNP transistor T1 is connected to the plus pole of theappropriate cell 14. A collector of this transistor T1 is electrically connected to the measuringconductor 21 via the resistor R2, . . . , R10. A base-emitter resistor 45 is arranged between the base and emitter of the transistor T1. The base of the transistor T1 is also connected via abase resistor 47 to the collector of a drive transistor T2 and which is in the form of an NPN transistor. An emitter terminal of the drive transistor T2 is electrically connected to theground conductor 17. - The base of the drive transistor T2 is electrically connected to a digital output of the
microcontroller 25 via aseries resistor 49. In each case, a switching element in the form of the transistor T1, and the associated drive circuit in the form of the transistor T2, and theresistors cell outer cell 14 a. Accordingly, for each drive transistor T2, themicrocontroller 25 has a digital output which is electrically connected to theseries resistor 49 of exactly one transistor T2, so that themicrocontroller 25 can drive the transistors T2 separately from one another. - In the embodiment as seen in
FIG. 2 , theload 37 has a series circuit composed of asemiconductor diode 51, and the load resistor Rv. The transistor T1 is not only used to electrically connect connectingbranches 20 to the measuringconductor 21 which is shown at the top ofFIG. 2 , but also is used to electrically activate and deactivate theload 37. That is to say, the transistor T1 not only forms the switchingelement 19 of the switching device, but at the same time is a switching element of the activatable and deactivatable load 37. - According to the embodiment of the invention as seen in
FIG. 1 , it is provided that theload 37 is only associated with thecells outer cell 14 a. Furthermore, in the embodiment of the invention which is shown inFIG. 2 , a damping capacitor C1 is electrically connected in parallel with the resistor R11. - When the arrangement, 41, is in operation, by means of the digital outputs, the
microcontroller 25 successively drives the individual drive transistors T2, so that they and the corresponding transistors T1 conduct, and a corresponding measuring current Im1, . . . , Im10 is established, to which is added the additional current I12, . . . , I110 through theload 37, where appropriate. In doing so, in each case themicrocontroller 25 outputs a control signal si, i=1, . . . , 10 via the digital outputs, by means of which the appropriate drive transistor T2, is driven. The control signal si is a digital signal, which can assume two stable states, namely a low level (low), and a high level (high). The switchingelement 19 is activated exactly when the control signal si is at the high level. - The resistors R1, . . . , R10, R11 are preferably designed so that an electrical potential which is not greater than the electrical potential on the plus pole of the
second cell 14 that is to say, on thatcell 14 which is adjacent to the firstouter cell 14 a is established at the measuringinput 22, plus a forward voltage of thatdiode 51, which is associated with thesecond cell 14. This prevents transverse currents between the plus poles of theindividual cells input 22 is approximately 0 V to 5 V with respect to GND. - All in all, the present invention provides the
arrangement 41 for measuring a single cell or therechargeable battery pack 43, and which substantially prevents a non-uniform discharge, and therefore a debalancing of the charge state of theindividual cells individual cells individual cells rechargeable battery pack 43 is ensured, particularly when thecells arrangement 41.
Claims (10)
1. An arrangement for measuring a cell in a rechargeable battery pack, comprising:
a series circuit composed of a plurality of cells, and wherein two adjacent cells are electrically connected to one another by means of a connecting branch, and wherein the arrangement has a measuring device and which further comprises a switching device, and which is equipped to selectively connect exactly one connecting branch to a measuring input of the measuring device and wherein the arrangement has at least one load arranged between two connecting branches, such that the load can selectively be brought into an activated operating state or into a deactivated operating state by means of a control signal(s) such that an electric charge can be taken from at least one cell during the activated operating state by means of the load.
2. The arrangement as claimed in claim 1 , and wherein the arrangement has a control device which is equipped to generate the control signal(s) for activating and deactivating at least one load, so that a non-uniform discharge of the cells as a result of a measuring current (Im1, . . . , Im10) at the measuring input is at least substantially prevented when different connecting branches are successively connected to the measuring input.
3. The arrangement as claimed in claim 2 , and wherein the at least one load is connected in parallel with exactly one cell.
4. The arrangement as claimed in claim 3 , and wherein the measuring device is equipped for measuring a voltage between the measuring input and a reference point within a series circuit, and wherein the reference point is electrically connected to a terminal of the measuring device.
5. The arrangement as claimed in claim 4 , and wherein all cells of the rechargeable battery pack belong to the series circuit which has an outer end and wherein a minus pole of an outer cell of the outer end of the series circuit, forms the reference point.
6. The arrangement as claimed in claim 5 , and wherein the load has at least one switching element which is electrically closed when the load is activated and electrically open when the load is deactivated, and wherein one of these switching elements simultaneously forms a switching element of the switching device.
7. The arrangement as claimed in claim 6 , and wherein the load has a series circuit comprising a semiconductor switch (T1) and a resistor (Rv).
8. The arrangement as claimed in claim 7 , and wherein the series circuit also has a semiconductor diode which is connected in series with the resistor (Rv).
9. A rechargeable battery pack with an arrangement for measuring a cell, comprising:
a series circuit composed of a plurality of cells, and wherein two adjacent cells are electrically connected to one another by means of a connecting branch, and wherein the arrangement has a measuring device which comprises a switching device, and which is equipped to selectively connect exactly one connecting branch to a measuring input of the measuring device, and wherein the arrangement has at least one load arranged between two connecting branches and wherein the load can selectively be brought into an activated operating state or into a deactivated operating state by means of a control signal(s) such that electric charge can be taken from at least one cell during the activated operating state by means of the load.
10. (canceled)
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE102010021176.1 | 2010-05-21 | ||
DE102010021176A DE102010021176A1 (en) | 2010-05-21 | 2010-05-21 | Arrangement for single cell measurement in a battery pack and a battery pack with such an arrangement |
PCT/EP2011/058138 WO2011144695A2 (en) | 2010-05-21 | 2011-05-19 | Arrangement for measuring a single cell in a rechargeable battery pack and rechargeable battery pack comprising such an arrangement |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
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PCT/EP2011/058138 A-371-Of-International WO2011144695A2 (en) | 2010-05-21 | 2011-05-19 | Arrangement for measuring a single cell in a rechargeable battery pack and rechargeable battery pack comprising such an arrangement |
Related Child Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US15/439,108 Continuation US9910098B2 (en) | 2010-05-21 | 2017-02-22 | Arrangement for measuring a single cell in a rechargeable battery pack and rechargeable battery pack comprising such an arrangement |
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US20130207663A1 true US20130207663A1 (en) | 2013-08-15 |
Family
ID=44626759
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
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US13/698,711 Abandoned US20130207663A1 (en) | 2010-05-21 | 2011-05-19 | Arrangement for Measuring a Single Cell in a Rechargeable Battery Pack and Rechargeable Battery Pack Comprising such an Arrangement |
US15/439,108 Active US9910098B2 (en) | 2010-05-21 | 2017-02-22 | Arrangement for measuring a single cell in a rechargeable battery pack and rechargeable battery pack comprising such an arrangement |
Family Applications After (1)
Application Number | Title | Priority Date | Filing Date |
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US15/439,108 Active US9910098B2 (en) | 2010-05-21 | 2017-02-22 | Arrangement for measuring a single cell in a rechargeable battery pack and rechargeable battery pack comprising such an arrangement |
Country Status (5)
Country | Link |
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US (2) | US20130207663A1 (en) |
EP (1) | EP2572208B1 (en) |
CN (1) | CN102906584B (en) |
DE (1) | DE102010021176A1 (en) |
WO (1) | WO2011144695A2 (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20150153415A1 (en) * | 2012-06-08 | 2015-06-04 | Robert Bosch Gmbh | Method for Determining the Internal OHMIC Resistance of a Battery Module, Battery Management System and Motor Vehicle |
US20170033415A1 (en) * | 2015-07-30 | 2017-02-02 | Yazaki Corporation | Secondary cell state detector |
WO2017063816A1 (en) * | 2015-10-13 | 2017-04-20 | Robert Bosch Gmbh | Device, assembly and electrically driveable transportation means for voltage monitoring of a plurality of electro-chemical cells of an energy storage means |
US11041911B2 (en) * | 2016-12-31 | 2021-06-22 | Huawei Technologies Co., Ltd. | Sampling circuit, equalization circuit, and system for single cell in series battery pack |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102010021176A1 (en) | 2010-05-21 | 2011-11-24 | Metabowerke Gmbh | Arrangement for single cell measurement in a battery pack and a battery pack with such an arrangement |
DE102010047378A1 (en) * | 2010-10-05 | 2012-04-05 | Hpf Gmbh | Method for monitoring e.g. temperature of battery cell in battery block in electrically operated motor car, involves converting negative current pulses into voltage pulses, where voltage pulses are digitally reprocessed |
DE102015110185A1 (en) | 2015-06-24 | 2016-12-29 | Phoenix Contact Gmbh & Co. Kg | Measuring arrangement for detecting a malfunction of an energy storage device |
CN109435775B (en) * | 2017-08-31 | 2020-08-25 | 比亚迪股份有限公司 | Battery equalization method, system, vehicle, storage medium and electronic device |
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JP5219652B2 (en) * | 2008-06-26 | 2013-06-26 | 三洋電機株式会社 | Power supply |
DE102010021176A1 (en) | 2010-05-21 | 2011-11-24 | Metabowerke Gmbh | Arrangement for single cell measurement in a battery pack and a battery pack with such an arrangement |
-
2010
- 2010-05-21 DE DE102010021176A patent/DE102010021176A1/en not_active Withdrawn
-
2011
- 2011-05-19 EP EP11723395.7A patent/EP2572208B1/en active Active
- 2011-05-19 US US13/698,711 patent/US20130207663A1/en not_active Abandoned
- 2011-05-19 CN CN201180025014.3A patent/CN102906584B/en active Active
- 2011-05-19 WO PCT/EP2011/058138 patent/WO2011144695A2/en active Application Filing
-
2017
- 2017-02-22 US US15/439,108 patent/US9910098B2/en active Active
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US5883495A (en) * | 1997-07-31 | 1999-03-16 | National Semiconductor Corporation | Bidirectional current control circuit suitable for controlling the charging and discharging of rechargeable battery cells |
US6169385B1 (en) * | 1998-12-17 | 2001-01-02 | Japan Storage Battery Co., Ltd. | Capacity leveling circuit for a battery group |
US20030044689A1 (en) * | 2001-08-29 | 2003-03-06 | Hideki Miyazaki | Battery apparatus for controlling plural batteries and control method of plural batteries |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
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US20150153415A1 (en) * | 2012-06-08 | 2015-06-04 | Robert Bosch Gmbh | Method for Determining the Internal OHMIC Resistance of a Battery Module, Battery Management System and Motor Vehicle |
US9753090B2 (en) * | 2012-06-08 | 2017-09-05 | Robert Bosch Gmbh | Method for determining the internal ohmic resistance of a battery module, battery management system and motor vehicle |
US20170033415A1 (en) * | 2015-07-30 | 2017-02-02 | Yazaki Corporation | Secondary cell state detector |
US10249914B2 (en) * | 2015-07-30 | 2019-04-02 | Yazaki Corporation | Secondary cell state detector |
WO2017063816A1 (en) * | 2015-10-13 | 2017-04-20 | Robert Bosch Gmbh | Device, assembly and electrically driveable transportation means for voltage monitoring of a plurality of electro-chemical cells of an energy storage means |
US11041911B2 (en) * | 2016-12-31 | 2021-06-22 | Huawei Technologies Co., Ltd. | Sampling circuit, equalization circuit, and system for single cell in series battery pack |
Also Published As
Publication number | Publication date |
---|---|
US20170160347A1 (en) | 2017-06-08 |
EP2572208A2 (en) | 2013-03-27 |
WO2011144695A2 (en) | 2011-11-24 |
DE102010021176A1 (en) | 2011-11-24 |
CN102906584B (en) | 2015-06-03 |
WO2011144695A3 (en) | 2012-07-05 |
US9910098B2 (en) | 2018-03-06 |
CN102906584A (en) | 2013-01-30 |
EP2572208B1 (en) | 2017-11-29 |
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