JP5825243B2 - Battery monitoring device - Google Patents

Description

  The present invention relates to a battery monitoring device applied to an assembled battery configured by connecting a plurality of battery cells in series.

  Conventionally, in a battery pack, when charging and discharging of each battery cell is repeated, the voltage of each battery cell may vary due to the influence of individual cell differences, environmental temperature, and the like. When such voltage variations occur, the actually usable power capacity of the assembled battery is greatly reduced.

  Therefore, a monitoring circuit connected to each battery cell via a wiring provided with a filter resistor has an equalization switch and a resistor for short-circuiting both terminals of each battery cell and discharging them. A battery monitoring device is known that equalizes the cell voltage variation (cell balance) of each battery cell by discharging a current from a high voltage battery cell through an equalization switch and discharging the resistor. (See, for example, Non-Patent Document 1).

  This non-patent document 1 discloses three types of circuit configurations having different characteristics such as a drain separation type, a discharge path separation type, and a drain-source separation type.

“Li-ion battery monitoring IC aiming at half the cost”, Nikkei Automotive Technology, July 2012, p.100-103

  As shown in FIG. 5, the drain separation type described in Non-Patent Document 1 has a circuit configuration in which an equalization switch SW is connected to a wiring provided with a filter resistor Rf (hereinafter referred to as an A-type circuit). ), The circuit configuration can be simplified.

  However, in the A-type circuit, when the equalizing switch SW is turned on, a discharge current flows through the filter resistor Rf as shown by the arrow in FIG. 5, so that the resistance value of the filter resistor Rf is There is a problem in that it cannot be arbitrarily set and the degree of freedom in designing the circuit configuration is greatly limited.

  Such a problem is not limited to the A-type circuit, but also to a circuit configuration (hereinafter referred to as a B-type circuit) in which the equalization switch SW is connected to the wiring provided with the filter resistor Rf shown in FIG. Arise.

  In contrast, as shown in FIG. 7, the discharge path separation type described in Non-Patent Document 1 has an equalizing resistor Rb and a wiring branched from a wiring provided with a filter resistor Rf. When the equalizing switch SW is connected and the equalizing switch SW is turned on, the circuit configuration (hereinafter referred to as a C-type circuit) is such that no discharge current flows through the filter resistor Rf.

  In this C-type circuit, for example, a discharge current when discharging adjacent battery cells simultaneously flows through two discharge resistors Rb (see solid lines in FIG. 7), and discharges a single battery cell. The discharge current during the flow also flows through the two discharging resistors Rb (see the broken line in FIG. 7).

  For this reason, although the C-type circuit has a high degree of design freedom in the circuit configuration, the discharge current when discharging adjacent battery cells simultaneously is several times the discharge current when discharging a single battery cell. It will increase. As a result, when discharging each adjacent battery cell, it is necessary to shift the discharge timing, and there is a problem that it takes a long time to equalize the cell voltage.

  Further, as shown in FIG. 8, the drain-source separation type described in Non-Patent Document 1 is provided with a wiring connecting the discharge resistor Rb and the equalization switch SW, and a filter resistor Rf. The circuit configuration (hereinafter referred to as a D-type circuit) is obtained by completely separating the wiring. According to this D-type circuit, adjacent battery cells can be discharged at the same time, and the design flexibility of the circuit configuration is increased, but the number of wirings connected to the monitoring circuit and the number of terminals provided on the monitoring circuit side are increased. There is a problem that the monitoring circuit becomes enlarged.

  An object of the present invention is to provide a battery monitoring device capable of simultaneously discharging adjacent cells while suppressing enlargement of the monitoring circuit and a decrease in the degree of design freedom of the circuit configuration.

  The present invention is directed to a battery monitoring device applied to an assembled battery (1) configured by connecting a plurality of battery cells (10) in series.

  To achieve the above object, according to the first aspect of the present invention, when the connection terminals of a plurality of battery cells are counted in order of potential, a plurality of odd lines connected to odd connection terminals and a plurality of batteries When the connection terminals of the cells are counted in the order of potential, a filter resistor (Rf) provided on one of the plurality of even lines, odd lines, and even lines connected to the even connection terminals. ), A plurality of branch lines (Ldiv) branched from between the filter resistor in one connection line and the connection terminal of the battery cell, and each of the plurality of battery cells A monitoring circuit (22) configured to include a plurality of equalization switches (221) provided as an equalization switch, and the equalization switch is an adjacent odd line and even line. A switch connected between the other connection line not provided with the filter resistor and the branch line, short-circuits the other connection line and the branch line, and discharges the corresponding battery cell. Each is characterized in that a current limiting resistor (Rb) for limiting the current flowing when the corresponding battery cell is discharged by the equalizing switch is provided.

  In this way, if the equalizing switch has a circuit configuration that short-circuits between the branch line and the connection line not provided with the filter resistor, the discharge current when the battery cell is discharged by the equalizing switch is filtered. The resistance value of the filter resistor can be set arbitrarily.

  In addition, the discharge current when each adjacent battery cell is discharged by the equalizing switch flows through two branch lines (two current limiting resistors), and a single battery cell is discharged by the equalizing switch. The discharge current when discharged flows through one branch line (one current limiting resistor). Therefore, the discharge current when each adjacent battery cell is discharged by the equalization switch is the same as the discharge current when a single battery cell is discharged by the equalization switch, and the adjacent battery It becomes possible to equalize cells at the same time.

  Furthermore, since a circuit configuration in which three wires such as an odd line, an even line, and a branch line are connected to the monitoring circuit per single battery cell, a wire for connecting the equalizing switch and a wire for providing a filter resistor are provided. Compared to a completely separated circuit configuration, the number of wires connected to the monitoring circuit and the number of terminals provided on the monitoring circuit side can be reduced.

  Therefore, according to the invention described in claim 1 of the present application, it is possible to discharge adjacent battery cells simultaneously while enlarging the monitoring circuit and suppressing a decrease in the degree of design freedom of the circuit configuration.

  In addition, the code | symbol in the parenthesis of each means described in this column and the claim shows an example of a correspondence relationship with the specific means described in the embodiment described later.

1 is an overall configuration diagram of a battery monitoring device according to an embodiment. It is a circuit diagram which shows the flow of the discharge current at the time of discharge of a single battery cell. It is a circuit diagram which shows the flow of the discharge current at the time of discharge of an adjacent battery cell. It is explanatory drawing for demonstrating the characteristic of the battery monitoring apparatus which concerns on embodiment. It is a circuit block diagram of the conventional A type circuit. It is a circuit block diagram of the conventional B-type circuit. It is a circuit block diagram of the conventional C-type circuit. It is a circuit block diagram of the conventional D type circuit.

  An embodiment of the present invention will be described with reference to the drawings. In this embodiment, the battery monitoring device 2 of the present invention is applied to the assembled battery 1 mounted in a hybrid vehicle or an electric vehicle.

  The assembled battery 1 is a power source that mainly supplies a traveling electric motor (not shown) to power various electric loads mounted on the vehicle. The assembled battery 1 of this embodiment is comprised as a serial connection body which connected the battery cell 10 which consists of secondary batteries, such as a lithium ion battery, in series, as shown in the whole block diagram of FIG. For convenience of explanation, FIG. 1 illustrates representative four battery cells BCi to BCi + 3 (i is a positive integer) among the plurality of battery cells 10 constituting the assembled battery 1.

  The battery monitoring device 2 is a device that monitors the state of the assembled battery 1, and includes a connection line L, a filter circuit 21, and a monitoring circuit that are connected to connection terminals (terminals that connect the battery cells 10) P of each battery cell 10. 22. It is comprised by the control apparatus etc. which are not shown in figure.

The connection line L is a wiring that connects the connection terminal P of each battery cell 10 and the terminal C provided in the monitoring circuit 22. In the connection line L of the present embodiment, when the connection terminals of the battery cells BCi to BCi + 3 are counted in order of potential (in this embodiment, in order of decreasing potential), the connection terminals P _2m−1 and P _{2m + 1} that are odd-numbered. , P _{2m + 3} (m is a positive integer), odd lines L _2m−1 , L _{2m + 1} , L _{2m + 3} , and even lines L connected to even-numbered connection terminals P _2m , P _{2m + 2} , P _{2m + 4 2m} , _{L2m + 2} , and _{L2m + 4} .

Each odd line L _2m−1 , L _{2m + 1} , L _{2m + 3} and each even line L _2m , L _{2m + 2} , L _{2m + 4} are connected to the monitoring circuit 22 via terminals C _{2m−1 to} C _{2m + 4} provided in the monitoring circuit 22. A built-in voltage detector 223 is connected.

Of the odd lines L _2m−1 , L _{2m + 1} , L _{2m + 3} and the even lines L _2m , L _{2m + 2} , L _{2m + 4} , one connection line is provided with a filter resistor Rf constituting the filter circuit 21, and for the filter A pair of branch lines Ldiv branched from the resistor Rf and the connection terminals P _2m , P _{2m + 2} , and P _{2m + 4} are connected.

Each odd-numbered line L _2m−1 , L _{2m + 1} , L _{2m + 3} of the present embodiment is provided with a filter resistor Rf, and a pair between the filter resistor Rf and the connection terminals P _2m , P _{2m + 2} , P _{2m + 4.} Branch line Ldiv is connected. Note that the even-numbered lines L _2m , L _{2m + 2} , and L _{2m + 4 of} this embodiment are not provided with the filter resistor Rf.

  Each branch line Ldiv is provided with a current limiting resistor Rb for limiting the current. As the current limiting resistors Rb, resistors having the same resistance value are employed. Each branch line Ldiv is connected to an equalization switch 221 built in the monitoring circuit 22 via a branching terminal Cdiv provided in the monitoring circuit 22, and when the equalization switch 221 described later is turned on, The discharge current flowing through the branch line Ldiv is limited by the current limiting resistor Rb.

The filter circuit 21 is a circuit that removes noise during voltage detection. The filter circuit 21 of this embodiment, the odd line _{L 2m-1, L 2m +} 1, L 2m + 3 resistance filter provided on Rf, and adjacent odd line _{L 2m-1, L 2m +} 1, L 2m + 3 and even line _{L 2m} , L _{2m + 2} , L _{2m + 4} , and is composed of an RC circuit comprising a capacitor Cf.

  The monitoring circuit 22 is a circuit that detects the voltage of each battery cell 10 and equalizes variation in the cell voltage of each battery cell 10 by discharging the battery cell 10, and is a terminal that connects each connection line L. C has a branch terminal Cdiv for connecting each branch line.

  The monitoring circuit 22 of this embodiment is provided corresponding to each of the battery cells BCi to BCi + 3, and switches for switching on / off the equalization switches 221 (SWi to SWi + 3) for discharging the battery cells 10 and each of the equalization switches 221. The circuit 222 includes a voltage detector 223 that detects the voltage of each battery cell 10.

  The equalization switch 221 short-circuits both terminals of the battery cells that are at high voltage among the battery cells BCi to BCi + 3, and discharges the battery cell 10 that is at high voltage, whereby the cell voltage of each of the battery cells BCi to BCi + 3. It functions as an equalizing means for equalizing variation.

The equalization switch 221 of this embodiment branches from the even lines L _2m , L _{2m + 2} , L _{2m + 4} and the odd lines L _2m−1 , L _{2m + 1} , L _{2m + 3} connected to the connection terminal P of the corresponding battery cell 10. It is connected between the branch line Ldiv. In the present embodiment, the equalization switch 221 is configured by a MOSFET that is a semiconductor switch.

  The switch switching circuit 222 is a switch switching unit that switches each equalization switch 221 on and off, and turns on the equalization switch 221 corresponding to a predetermined battery cell 10 in accordance with an output signal from the control device.

The voltage detector 223 is connected to each odd line L _2m−1 , L _{2m + 1} , L _{2m + 3} and each even line L _2m , L _{2m + 2} , L _{2m + 4} , and at least 2 of the lines L _{2m−1 to} L _{2m + 4.} The cell voltage (inter-terminal voltage) of the battery cells BCi to BCi + 3 is detected from the potential difference between the two lines.

The voltage detection unit 223 of the present embodiment is a detection unit that detects a potential difference and outputs it to the control device, and a multiplexer that selects at least two lines from the lines L _{2m−1 to} L _{2m + 4} and connects to the detection unit. It is configured. This multiplexer functions as a switching means for switching the battery cell 10 as a voltage detection target, and is controlled according to an output signal from the control device.

  The control device is composed of a CPU, a microcomputer composed of various memories constituting storage means, and peripheral devices thereof, and is configured to execute various processes according to a control program stored in the storage means.

  In the control device of the present embodiment, the voltage detection unit 223 performs a voltage detection process for detecting the cell voltage of each battery cell 10 and an equalization process for equalizing variation in the cell voltage of each battery cell 10.

  Next, the operation of the battery monitoring device 2 of this embodiment will be described. First, voltage detection processing executed by the control device of this embodiment will be described.

  In the voltage detection process, the control device inputs a control signal instructing detection of the cell voltage of each battery cell 10 to the monitoring circuit 22, so that the voltage detection unit 223 of the monitoring circuit 22 detects the cell voltage of each battery cell 10. To do.

For example, when detecting the cell voltage of the battery cell BCi, the multiplexer connects the odd line L _2m-1 and the even line L _2m connected to the connection terminals P _2m-1 and P _2m of the battery cell BCi to the detection unit. To do. Then, the detection unit detects a potential difference between the odd line L _2m-1 and the even line L _2m as the cell voltage of the battery cell BCi.

Further, the adjacent battery cells BCi, when detecting the total voltage of the cell voltage of BCi + 1, the odd line multiplexer is connected to the connection terminals _{P 2m-1} of the battery cell BCi _{L 2m-1,} P battery cell BCi + 1 _The odd line L _{2m + 1} connected to _{2m + 2} is connected to the detection unit. Then, the detection unit detects a potential difference between the odd line L _2m−1 and the odd line L _{2m + 1} as a total voltage of the cell voltages of the battery cells BCi and BCi + 1.

  Next, the equalization process executed by the control device of this embodiment will be described. In the equalization detection process, the control device determines a battery cell 10 to be discharged from each battery cell 10 and inputs a control signal instructing discharge of the battery cell 10 to the monitoring circuit 22. The 22 switch switching circuits 222 switch on the equalization switch 221 corresponding to the battery cell 10 to be discharged.

For example, when the battery cell BCi is to be discharged, the switch switching circuit 222 switches on the equalization switch SWi corresponding to the battery cell BCi. Thereby, the even line L _2m connected to the connection terminal P _2m of the battery cell BCi and the branch line Ldiv branched from the odd line L _2m-1 connected to the connection terminal P _2m-1 of the battery cell BCi are short-circuited. Then, as shown by the arrow in FIG. 2, the battery cell BCi is discharged through the even line L _2m → equalization switch SWi → the branch line Ldiv (current limiting resistor Rb) → the odd line L _2m−1 .

At this time, the discharge current does not flow through the filter resistor Rf provided in the odd-numbered line L2m _-1 , but flows through the current limiting resistor Rb provided in the branch line Ldiv. For this reason, since the setting of the filter resistor Rf does not affect the equalization process, the setting of the filter resistor Rf can be arbitrarily set.

  Here, when other battery cells BCi + 1 to BCi + 3 other than the battery cell BCi are to be discharged, the switch switching circuit 222 switches on the equalization switches SWi + 1 to SWi + 3 corresponding to the battery cells BCi + 1 to BCi + 3. Cells BCi + 1 to BCi + 3 can be discharged. At this time, even when any of the battery cells BCi + 1 to BCi + 3 is discharged, the discharge current does not flow to the filter resistor Rf, and therefore the setting of the filter resistor Rf does not affect the equalization process.

  The discharge current when discharging a single battery cell 10 is determined by the voltage of the battery cell BCi and the resistance value of the current limiting resistor Rb provided on the branch line Ldiv.

  Further, for example, when adjacent battery cells BCi and BCi + 1 are to be discharged and the battery cells BCi and BCi + 1 are discharged at the same time, the switch switching circuit 222 has equalization switches SWi and SWi + 1 corresponding to the battery cells BCi and BCi + 1. Switch on.

Thereby, the even line L _2m connected to the connection terminal P _2m of the battery cell BCi and the branch line Ldiv branched from the odd line L _2m-1 connected to the connection terminal P _2m-1 of the battery cell BCi are short-circuited. To do. Also, the even line L _2m connected to the connection terminal P _2m of the battery cell BCi + 1 and the branch line Ldiv branched from the odd line L _{2m + 1} connected to the connection terminal P _{2m + 1} of the battery cell BCi + 1 are short-circuited.

In this case, as indicated by the arrow in FIG. 3, odd line L _{2m + 1} → branch line Ldiv (current limiting resistor Rb) → equalization switch SWi + 1 → equalization switch SWi → branch line Ldiv (current limiting resistor Rb) → odd number flowing through the line _{L 2m-1,} each battery cell BCi, BCi + 1 is discharged.

  The discharge current at this time is determined by the total value of the voltages of the battery cells BCi and BCi + 1 and the total value of the resistance values of the current limiting resistors Rb provided on the branch lines Ldiv. That is, since the discharge current when discharging each of the adjacent battery cells BCi and BCi + 1 is determined by the two battery cells BCi and BCi + 1 and the two current limiting resistors Rb, the single battery cell 10 is discharged. It becomes the same as the discharge current at the time. This is the same for the case where other adjacent battery cells are simultaneously discharged.

  Next, features of the battery monitoring device 2 of the present embodiment will be described. According to the battery monitoring apparatus 2 of the present embodiment, as shown in FIG. 4, an A type circuit shown in FIG. 5, a B type circuit shown in FIG. 6, a C type circuit shown in FIG. 7, and a D type circuit shown in FIG. The matter which became a subject by the conventional circuit structure of such can be eliminated.

Specifically, in this embodiment, branch lines Ldiv branched from the odd lines L _2m−1 , L _{2m + 1} , and L _{2m + 3,} and even lines L _{2m−1 to} L _{2m + 4} not provided with the filter resistor Rf The equalization switch 221 is connected between the two.

  According to this, the discharge current when the predetermined battery cell 10 is discharged by the equalization switch 221 does not flow to the filter resistor Rf, and the setting of the filter resistor Rf does not affect the equalization process. The filter resistor Rf can be arbitrarily set, and the degree of freedom in designing the circuit configuration can be ensured.

  In addition, since the discharge current when the predetermined battery cell 10 is discharged by the equalization switch 221 does not flow to the filter resistor Rf, the voltage drop due to the discharge current does not affect the voltage detection. For this reason, even if the equalization process is executed at the time of voltage detection, the cell voltage of each battery cell 10 can be accurately detected, and the voltage detection process and the equalization process can be executed simultaneously.

  Further, in the circuit configuration of the present embodiment, the discharge current when each of the adjacent battery cells 10 is discharged by the equalization switch 221 flows through the two branch lines Ldiv (two current limiting resistors Rb). The discharge current when the single battery cell 10 is discharged by the equalization switch 221 flows through one branch line (one current limiting resistor Rb).

  For this reason, the discharge current when each adjacent battery cell 10 is discharged by the equalization switch 221 is the same as the discharge current when the single battery cell 10 is discharged by the equalization switch 221. Adjacent battery cells 10 can be equalized (simultaneously discharged) at the same time. As a result, the time required for the equalization process can be shortened.

Furthermore, in the present embodiment, the even lines L _{2m−1 to} L _{2m + 4} not provided with the current limiting resistor Rb have a circuit configuration that functions as a common wiring for equalization and voltage detection. For this reason, a simple circuit configuration in which three wires such as a connection line L (odd line and even line) and a branch line Ldiv are connected to the monitoring circuit 22 per single battery cell 10 is achieved. As described above, the number of wires connected to the monitoring circuit 22 and the number of terminals provided on the monitoring circuit 22 side are reduced as compared with the circuit configuration in which the wiring connecting the equalization switch SW and the wiring providing the filter resistor Rf are completely separated. Can do.

  Therefore, according to the configuration of the present embodiment, it is possible to discharge the adjacent battery cells 10 at the same time while enlarging the monitoring circuit 22 and suppressing a decrease in the degree of design freedom of the circuit configuration.

(Other embodiments)
As mentioned above, although embodiment of this invention was described, this invention is not limited to the above-mentioned embodiment, In the range described in the claim, it can change suitably. For example, various modifications are possible as follows.

(1) In the above-described embodiment, when the connection terminals P of each battery cell 10 are counted in order of increasing potential, the connection lines L connected to the odd-numbered connection terminals P are the odd lines L _2m−1 , L _{Although an example} in which the connection line L connected to the even-numbered connection terminal P is _{2m + 1} and L _{2m + 3} and the even lines L _2m , L _{2m + 2} and L _{2m + 4} has been described, the present invention is not limited to this. For example, when the connection terminals P of the battery cells 10 are counted in descending order of potential, the connection lines L connected to the odd connection terminals P are odd lines L _2m−1 , L _{2m + 1} , L _{2m + 3,} and even numbers The connection line L connected to the second connection terminal P may be the even lines L _2m , L _{2m + 2} , and L _{2m + 4} .

(2) In the above-described embodiment, the example in which the filter resistor Rf is provided for each odd line L _2m−1 , L _{2m + 1} , and L _{2m + 3} and the branch line Ldiv is connected has been described. However, the present invention is not limited to this. . For example, a filter resistor Rf may be provided for the even lines L _2m , L _{2m + 2} , and L _{2m + 4} , and the branch line Ldiv may be further connected. In this case, the odd lines L _2m−1 , L _{2m + 1} , and L _{2m + 3} that are not provided with the current limiting resistor Rb function as a common wiring for equalization and voltage detection.

  (3) In the above-described embodiment, the example in which the filter circuit 21 is configured by the RC circuit including the filter resistor Rf and the capacitor Cf has been described. However, the present invention is not limited thereto, and the filter resistor Rf is used and voltage detection is performed. Any filter circuit 21 that does not adversely affect the processing and equalization processing can be adopted as appropriate.

  (4) In the above-described embodiment, the example in which the equalization switch 221 is configured by a MOSFET has been described. However, the present invention is not limited thereto, and the equalization switch 221 may be configured by another semiconductor switch.

  (5) In the above-described embodiment, the example in which the switch switching circuit 222 for switching on / off of the equalization switch 221 is provided in the monitoring circuit 22 has been described, but the present invention is not limited thereto, and the switch switching circuit 222 is provided outside the monitoring circuit 22. It is good also as a structure.

  (6) In the above-described embodiment, the example in which the voltage detection unit 223 includes the detection unit and the multiplexer has been described. However, the present invention is not limited to this. For example, a plurality of detection units may be provided corresponding to each battery cell 10 and the voltage detection unit 223 may be configured by each detection unit.

  (7) In the above-described embodiment, the example in which the voltage detection unit 223 is provided in the monitoring circuit 22 has been described. However, the configuration is not limited thereto, and the voltage detection unit 223 may be provided outside the monitoring circuit 22.

  (8) In the above-described embodiment, an example in which the battery monitoring device 2 is applied to the assembled battery 1 mounted on a hybrid vehicle or an electric vehicle has been described. However, the battery monitoring device 2 is not limited to the on-board assembled battery 1 and is a stationary assembled battery. You may apply to 1 grade | etc.,.

  (9) In the above-described embodiment, elements constituting the embodiment are not necessarily essential unless explicitly stated as essential and clearly considered essential in principle. Needless to say.

  (10) In the above-described embodiment, when numerical values such as the number, numerical value, quantity, range, etc. of the constituent elements of the embodiment are mentioned, it is clearly indicated that it is particularly essential and clearly specified in principle. It is not limited to the specific number except in a limited case.

DESCRIPTION OF SYMBOLS 1 assembled battery 10 battery cell 22 monitoring circuit 221 equalization switch 223 voltage detection part L connection line Ldiv branch line Rf resistance for filter Rb resistance for current limitation

Claims (3)

A battery monitoring device applied to an assembled battery (1) configured by connecting a plurality of battery cells (10) in series,
When counting the connection terminals of the plurality of battery cells in order of potential, a plurality of odd lines connected to odd connection terminals,
When counting the connection terminals of the plurality of battery cells in order of potential, a plurality of even lines connected to the connection terminals that are even-numbered,
A filter circuit (21) configured to include a filter resistor (Rf) provided in one of the odd lines and the even lines;
A plurality of branch lines (Ldiv) branched from between the filter resistor and the battery cell connection terminal in the one connection line;
A monitoring circuit (22) configured to include a plurality of equalization switches (221) provided corresponding to each of the plurality of battery cells,
The equalization switch is connected between the other connection line not provided with the filter resistor and the branch line among the adjacent odd line and the even line, and the other connection line and the branch. A switch that short-circuits the line and discharges the corresponding battery cell;
Each of the plurality of branch lines is provided with a current limiting resistor (Rb) that limits a current that flows when the corresponding battery cell is discharged by the equalization switch. apparatus.   The monitoring circuit is connected to each of the plurality of odd lines and the plurality of even lines, and calculates a cell voltage of the battery cell from a potential difference between at least two lines of the plurality of odd lines and the plurality of even lines. The battery monitoring device according to claim 1, further comprising a voltage detection unit (223) for detection.   3. The filter circuit according to claim 1, wherein the filter circuit includes an RC circuit including the filter resistor and a capacitor (Cf) connected between the odd line and the even line adjacent to each other. The battery monitoring device described.

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