Battery monitoring device and battery monitoring method

Abstract

This battery monitoring device (70) is connected to a plurality of battery cells. The battery monitoring device is provided with: a battery monitoring IC (40) that monitors the plurality of battery cells; and a circuit board (50) that connects the battery monitoring IC and the battery cells. The battery monitoring circuit has: a plurality of first ADCs (41) each connected to a positive electrode terminal and a negative electrode terminal of each of the battery cells and outputting an electric signal for measuring a complex impedance of each of the battery cells; and a plurality of second ADCs (42) each connected to the positive electrode terminal and the negative electrode terminal of each of the battery cells and outputting an electric signal for detecting the state of each of the battery cells. The circuit board has a first ADC and a plurality of terminal pairs connected to a target cell that is a battery cell corresponding to the first ADC. The terminal pairs are individually provided for the first ADC.

Description

Battery monitoring device and battery monitoring circuit CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Patent Application No. 2023-193176 filed in Japan on November 13, 2023, and the contents of the original application are incorporated by reference in their entirety.

[0002] The present disclosure relates to a battery monitoring device and a battery monitoring circuit.

[0003] As disclosed in Patent Document 1, there is a battery monitoring device that monitors a battery having a plurality of battery cells.

[0004] JP 2023-95746 A

[0005] A battery monitoring device may have a configuration in which two conversion circuits that convert analog signals to digital signals are connected to each battery cell. The conversion circuits are connected to the positive and negative terminals of the battery cell via wiring. One of the two conversion circuits outputs an electrical signal for measuring the complex impedance of the battery cell.

[0006] In such a configuration, the battery monitoring device may be connected to adjacent battery cells through common wiring in the conversion circuits corresponding to the adjacent battery cells. In this case, it is difficult to use differential pair wiring. Therefore, the battery monitoring device may output an electrical signal for complex impedance measurement that is affected by noise.

[0007] One disclosed object is to provide a battery monitoring device and a battery monitoring circuit that can reduce the influence of noise.

[0008] The battery monitoring device disclosed herein is a battery monitoring device connected to a plurality of battery cells, and comprises a battery monitoring circuit that monitors the plurality of battery cells, and a circuit board that connects the battery monitoring circuit to the battery cells, wherein the battery monitoring circuit comprises: a plurality of first conversion circuits connected to the positive and negative terminals of each battery cell, converting analog signals to digital signals and outputting electrical signals for measuring the complex impedance of each battery cell; and a plurality of second conversion circuits connected to the positive and negative terminals of each battery cell, converting analog signals to digital signals and outputting electrical signals for detecting the state of each battery cell, wherein the first conversion circuit and the second conversion circuit are connected in pairs to each battery cell, and the circuit board comprises: a plurality of terminal pairs connected to the first conversion circuit and a target cell that is a battery cell corresponding to the first conversion circuit, and the terminal pairs are provided individually for the first conversion circuit.

[0009] In this way, the battery monitoring device includes a plurality of first conversion circuits that output battery voltages for measuring the complex impedance of each battery cell. A terminal pair connected to each first conversion circuit and the target cell is individually provided for each first conversion circuit. This facilitates wiring between the battery monitoring device and the plurality of battery cells using differential pair wiring. Therefore, the battery monitoring device can output a battery voltage for state detection from the second conversion circuit and a battery voltage for complex impedance measurement with reduced noise influence from the first conversion circuit.

[0010] The battery monitoring circuit disclosed herein is a battery monitoring circuit that is connected to a plurality of battery cells via a circuit board and monitors the battery cells, and includes: a plurality of first conversion circuits that are connected to the positive and negative terminals of each battery cell, converting analog signals into digital signals and outputting electrical signals for measuring the complex impedance of each battery cell; a plurality of second conversion circuits that are connected to the positive and negative terminals of each battery cell, converting analog signals into digital signals and outputting electrical signals for detecting the state of each battery cell; and circuit terminal pairs that are connected to each first conversion circuit and a target cell that is a battery cell corresponding to each first conversion circuit, and the first conversion circuit and second conversion circuit are connected in pairs to each battery cell, and the circuit terminal pairs are provided individually for each first conversion circuit.

[0011] In this way, the battery monitoring circuit includes multiple first conversion circuits that output battery voltages for measuring the complex impedance of each battery cell. Furthermore, circuit terminal pairs connected to each first conversion circuit and the target cell are individually provided for each first conversion circuit. This makes it easy to connect the battery monitoring circuit to multiple battery cells using differential pair wiring. Therefore, the battery monitoring circuit can output a battery voltage for state detection from the second conversion circuit and a battery voltage for complex impedance measurement with reduced noise influence from the first conversion circuit.

[0012] The various aspects disclosed in this specification employ different technical means to achieve their respective objectives. The reference numerals in parentheses in the claims and in this section are intended to exemplify correspondences with the following embodiments and are not intended to limit the technical scope. The objectives, features, and advantages disclosed in this specification will become more apparent by reference to the following detailed description and the accompanying drawings.

[0013] 1 is a diagram showing a schematic configuration of a battery device in a first embodiment. It is a cross-sectional view taken along line II-II in FIG. 1. It is a cross-sectional view taken along line III-III in FIG. 1. It is a cross-sectional view taken along line IV-IV in FIG. 1. It is a cross-sectional view taken along line VV in FIG. 1. It is a diagram showing a schematic configuration of a battery monitoring device and a flexible substrate in a first embodiment. It is a diagram showing a schematic configuration of a battery device in a second embodiment. It is a cross-sectional view taken along line VIII-VIII in FIG. 7. It is a cross-sectional view taken along line IX-IX in FIG. 7. It is a cross-sectional view taken along line XX in FIG. 7. It is a diagram showing a schematic configuration of a battery device in a third embodiment. It is a cross-sectional view taken along line XII-XII in FIG. 11. It is a cross-sectional view taken along line XIII-XIII in FIG. 11. It is a cross-sectional view taken along line XIV-XIV in FIG. 11. It is a diagram showing a schematic configuration of a battery device in a fourth embodiment. It is a cross-sectional view taken along line XVI-XVI in FIG. 11. It is a cross-sectional view taken along line XVII-XVII in FIG. 11. It is a cross-sectional view taken along line XVIII-XVIII in FIG. 11. 10A to 10C are diagrams showing the schematic configurations of a battery monitoring device and a flexible substrate according to a fifth embodiment, a sixth embodiment, and a seventh embodiment, respectively;

[0014] Hereinafter, several embodiments for carrying out the present disclosure will be described with reference to the drawings. In each embodiment, parts corresponding to matters described in the preceding embodiment may be assigned the same reference numerals, and duplicated explanations may be omitted. In each embodiment, when only a part of the configuration is described, the other parts of the configuration may be applied by referring to the other embodiment described previously.

[0015] (First embodiment) <Battery device> A battery device of this embodiment will be described using Figures 1 to 6. As shown in Figure 1, the battery device mainly includes a battery pack 10, a flexible substrate 30, a battery monitoring device 70, and the like. The battery device is configured to be mountable on, for example, a mobile object. Examples of mobile objects include vehicles, aircraft, ships, construction machinery, and agricultural machinery. The battery device can also be considered a battery system. In this embodiment, as an example, a battery device is employed that includes a battery pack 10 that includes multiple battery cells 11 to 18. However, it is sufficient for the battery device to include multiple battery cells 11 to 18. In other words, the multiple battery cells 11 to 18 do not have to be divided into units called battery packs 10.

[0016] The battery pack 10 has a plurality of battery cells 11 to 18 arranged side by side. The battery pack 10 has the plurality of battery cells 11 to 18 connected in series. A flexible substrate 30 is connected to each of the battery cells 11 to 18. The flexible substrate 30 is also connected to a battery monitoring device 70. The battery pack 10 is then connected to the battery monitoring device 70 via the flexible substrate 30. The battery device monitors each of the battery cells 11 to 18 using the battery monitoring device 70. Note that, as an example, the present embodiment employs one battery pack 10 and one battery monitoring device 70 corresponding to that battery pack 10. However, the present disclosure is not limited to this. The battery device may include a plurality of battery packs 10 and a plurality of battery monitoring devices 70 corresponding to each battery pack 10. The battery device may also include a plurality of battery packs 10 and a battery monitoring device 70 provided in common to the plurality of battery packs 10. The battery device may also include a microcomputer connected to the battery monitoring device 70. In this case, the flexible substrate 30 may be provided in common to the plurality of assembled batteries 10 and the plurality of battery monitoring devices 70. Alternatively, the flexible substrate 30 may be provided in common to the plurality of assembled batteries 10 and one battery monitoring device 70.

[0017] <Battery Pack> Each of the battery cells 11 to 18 can be, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery. In this embodiment, as an example, the battery pack 10 includes eight battery cells 11 to 18. However, the battery pack 10 may include any number of battery cells.

[0018] As shown in FIG. 1 , each battery cell 11-18 has a positive terminal 11p-18p and a negative terminal 11n-18n at both ends in the longitudinal direction. Specifically, the first battery cell 11 has a first positive terminal 11p and a first negative terminal 11n. The second battery cell 12 has a second positive terminal 12p and a second negative terminal 12n. The third battery cell 13 has a third positive terminal 13p and a third negative terminal 13n. The fourth battery cell 14 has a fourth positive terminal 14p and a fourth negative terminal 14n. The fifth battery cell 15 has a fifth positive terminal 15p and a fifth negative terminal 15n. The sixth battery cell 16 has a sixth positive terminal 16p and a sixth negative terminal 16n. The seventh battery cell 17 has a seventh positive terminal 17p and a seventh negative terminal 17n. The eighth battery cell 18 has an eighth positive terminal 18p and an eighth negative terminal 18n.

[0019] Bus bars 21 to 29 are connected to the terminals 11p to 18p and 11n to 18n. The first bus bar 21 is connected to the first negative terminal 11n. The second bus bar 22 is connected to the first positive terminal 11p and the second negative terminal 12n. The third bus bar 23 is connected to the second positive terminal 12p and the third negative terminal 13n. The fourth bus bar 24 is connected to the third positive terminal 13p and the fourth negative terminal 14n. The fifth bus bar 25 is connected to the fourth positive terminal 14p and the fifth negative terminal 15n. The sixth bus bar 26 is connected to the fifth positive terminal 15p and the sixth negative terminal 16n. The seventh bus bar 27 is connected to the sixth positive terminal 16p and the seventh negative terminal 17n. The eighth bus bar 28 is connected to the seventh positive terminal 17p and the eighth negative terminal 18n. The ninth bus bar 29 is connected to the eighth positive terminal 18p. In this manner, the plurality of battery cells 11 to 18 are connected in series via the bus bars 22 to 28.

[0020] <Flexible Substrate> A flexible substrate 30 will be described with reference to Figures 1 to 5. In Figure 1, to make the drawing easier to understand, upper layer wiring 31 is shown by solid lines and lower layer wiring 32 is shown by dotted lines. Similarly, vias 33 are shown by cross marks (cross lines).

[0021] The flexible substrate 30 is connected to the positive electrode terminals 11p to 18p and the negative electrode terminals 11n to 18 of the multiple battery cells 11 to 18. The flexible substrate 30 is a substrate for connecting the battery monitoring device 70 and the assembled battery 10. The flexible substrate 30 corresponds to a wiring substrate. In this embodiment, a flexible substrate is used as an example of a wiring substrate. However, a rigid substrate can also be used as the wiring substrate. Note that the flexible substrate 30 only needs to be connected to the multiple battery cells 11 to 18, and does not have to correspond to the unit of the assembled battery 10.

[0022] 2 to 5, the flexible substrate 30 includes an electrically insulating substrate 34 and wiring 3 provided on the substrate 34. The wiring 3 includes upper layer wiring 31 and lower layer wiring 32 stacked via the substrate 34, and vias 33 that electrically connect the upper layer wiring 31 and lower layer wiring 32 of different layers. The wiring 3 is covered by the substrate 34 with its ends exposed. The ends of the wiring 3 are connection portions with the bus bars 21 to 29 and the circuit board 50.

[0023] The vias 33 are mainly made of a conductive material such as copper or silver, and connect the upper layer wiring 31 and the lower layer wiring 32. The vias 33 correspond to interlayer connection members.

[0024] The upper layer wiring 31 and the lower layer wiring 32 are mainly composed of conductive materials such as aluminum and copper. The upper layer wiring 31 and the lower layer wiring 32 are formed by patterning conductive thin films. The upper layer wiring 31 and the lower layer wiring 32 are stacked in the thickness direction of the substrate 34. The upper layer wiring 31 and the lower layer wiring 32 correspond to pattern wiring. The upper layer wiring 31 and the lower layer wiring 32 can also be called layer wiring.

[0025] 1 and other figures, the wiring 3 has a plurality of wiring sections 301 to 309 that are individually connected to the bus bars 21 to 29. Each of the wiring sections 301 to 309 is composed of an upper layer wiring 31, a via 33, and a lower layer wiring 32. Each of the wiring sections 301 to 309 has one end connected to the bus bars 21 to 29 and the other end connected to the circuit board 50.

[0026] Specifically, the first wiring portion 301 is connected to the first bus bar 21. The second wiring portion 302 is connected to the second bus bar 22. The third wiring portion 303 is connected to the third bus bar 23. The fourth wiring portion 304 is connected to the fourth bus bar 24. The fifth wiring portion 305 is connected to the fifth bus bar 25. The sixth wiring portion 306 is connected to the sixth bus bar 26. The seventh wiring portion 307 is connected to the seventh bus bar 27. The eighth wiring portion 308 is connected to the eighth bus bar 28. The ninth wiring portion 309 is connected to the ninth bus bar 29.

[0027] Each of the wiring portions 301 to 309 is configured such that the portion thereof that connects to each of the bus bars 21 to 29 is exposed from the substrate 34. Similarly, each of the wiring portions 301 to 309 is configured such that the portion thereof that connects to the circuit board 50 is exposed from the substrate 34. The portion that connects to the circuit board 50 is part of the connector portion 60.

[0028] As described above, the second bus bar 22 to the eighth bus bar 28 are connected to the terminals of two adjacent battery cells. Therefore, the second wiring portion 302 to the eighth wiring portion 308 are provided in common to the two adjacent battery cells. The second wiring portion 302 to the eighth wiring portion 308 correspond to common wiring.

[0029] Therefore, the second wiring portion 302 to the eighth wiring portion 308 are connected to the positive electrode terminal of one of the two battery cells 11 to 18, and are connected to the negative electrode terminal of the other battery cell. Furthermore, each of the second wiring portion 302 to the eighth wiring portion 308 is branched into a positive electrode wiring portion and a negative electrode wiring portion. In other words, each of the second wiring portion 302 to the eighth wiring portion 308 includes a positive electrode wiring portion and a negative electrode wiring portion. The positive electrode wiring portions 302p to 309p are also referred to as positive electrode wiring portions 3p. On the other hand, the negative electrode wiring portions 301n to 308n are also referred to as negative electrode wiring portions 3n.

[0030] Specifically, the second wiring portion 302 branches into a second positive wiring portion 302p and a second negative wiring portion 302n. The second positive wiring portion 302p functions as a wiring connected to the first positive terminal 11p. The second negative wiring portion 302n functions as a wiring connected to the second negative terminal 12n.

[0031] The third wiring portion 303 branches into a third positive wiring portion 303p and a third negative wiring portion 303n. The third positive wiring portion 303p functions as a wiring connected to the second positive terminal 12p. The third negative wiring portion 303n functions as a wiring connected to the third negative terminal 13n.

[0032] The fourth wiring portion 304 branches into a fourth positive wiring portion 304p and a fourth negative wiring portion 304n. The fourth positive wiring portion 304p functions as a wiring connected to the third positive terminal 13p. The fourth negative wiring portion 304n functions as a wiring connected to the fourth negative terminal 14n.

[0033] The fifth wiring portion 305 branches into a fifth positive wiring portion 305p and a fifth negative wiring portion 305n. The fifth positive wiring portion 305p functions as a wiring connected to the fourth positive terminal 14p. The fifth negative wiring portion 305n functions as a wiring connected to the fifth negative terminal 15n.

[0034] The sixth wiring portion 306 branches into a sixth positive wiring portion 306p and a sixth negative wiring portion 306n. The sixth positive wiring portion 306p functions as a wiring connected to the fifth positive terminal 15p. The sixth negative wiring portion 306n functions as a wiring connected to the sixth negative terminal 16n.

[0035] The seventh wiring portion 307 branches into a seventh positive wiring portion 307p and a seventh negative wiring portion 307n. The seventh positive wiring portion 307p functions as a wiring connected to the sixth positive terminal 16p. The seventh negative wiring portion 307n functions as a wiring connected to the seventh negative terminal 17n.

[0036] The eighth wiring portion 308 branches into an eighth positive wiring portion 308p and an eighth negative wiring portion 308n. The eighth positive wiring portion 308p functions as a wiring connected to the seventh positive terminal 17p. The eighth negative wiring portion 308n functions as a wiring connected to the eighth negative terminal 18n.

[0037] The first wiring portion 301 is connected to only the first negative electrode terminal 11n of one first battery cell 11 among the multiple terminals 11p to 18p and 11n to 18n. Therefore, the first wiring portion 301 is also referred to as the first negative electrode wiring portion 301n. Similarly, the ninth wiring portion 309 is connected to only the eighth positive electrode terminal 18p of one eighth battery cell 18 among the multiple terminals 11n to 18n and 11p to 18p. The ninth wiring portion 309 is also referred to as the ninth positive electrode wiring portion 309p.

[0038] Furthermore, as shown in Figures 2 and 4, the positive wiring portion 3p and the negative wiring portion 3n are configured as differential pair wiring. In other words, the flexible substrate 30 has a plurality of differential pair wirings, including positive wiring portions 302p to 309p connected to the positive terminals 11p to 18p of each of the battery cells 11 to 18 and negative wiring portions 301n to 308n connected to the negative terminals 11n to 18n of each of the battery cells 11 to 18. The flexible substrate 30 has a plurality of differential pair wirings corresponding to each of the battery cells 11 to 18. Each differential pair wiring is provided with a positive wiring portion and a negative wiring portion running parallel to each other. The differential pair wiring corresponds to a pair wiring portion. A differential pair wiring is wiring in which two wires are arranged in parallel, and electronic signals of the same magnitude but opposite polarity are transmitted through each wire.

[0039] Specifically, the flexible substrate 30 includes, as differential pair wirings, a first negative wiring portion 301n and a second positive wiring portion 302p, a second negative wiring portion 302n and a third positive wiring portion 303p, a third negative wiring portion 303n and a fourth positive wiring portion 304p, and a fourth negative wiring portion 304n and a fifth positive wiring portion 305p. The flexible substrate 30 also includes, as differential pair wirings, a fifth negative wiring portion 305n and a sixth positive wiring portion 306p, a sixth negative wiring portion 306n and a seventh positive wiring portion 307p, a seventh negative wiring portion 307n and an eighth positive wiring portion 308p, and an eighth negative wiring portion 308n and a ninth positive wiring portion 309p.

[0040] For example, the first negative wiring portion 301n and the second positive wiring portion 302p can be considered to be a differential pair wiring for the first battery cell 11. The second negative wiring portion 302n and the third positive wiring portion 303p can be considered to be a differential pair wiring for the second battery cell 12. Each of the second wiring portion 302 to the eighth wiring portion 308 can also be considered to be branched into a positive wiring portion and a negative wiring portion of a different differential pair wiring. The positive wiring portions 302p to 309 and the negative wiring portions 301n to 308n can also be considered to be parts of each differential pair wiring. In other words, a differential pair wiring can be considered to be made up of a part of the first negative wiring portion 301n and a part of the second positive wiring portion 302p.

[0041] 4, the differential pair wiring is configured such that the positive wiring portions 302p to 309p and the negative wiring portions 301n to 308n are provided in different layers via the substrate 34. In the present embodiment, as an example, an example is employed in which the positive wiring portions 302p to 309p are configured as upper layer wiring 31, and the negative wiring portions 301n to 308n are configured as lower layer wiring 32. However, the present disclosure is not limited to this.

[0042] 4, each differential pair wiring is arranged such that the positive wiring portions 302p to 309p and the negative wiring portions 301n to 308n face each other in the thickness direction of the substrate 34. That is, the positive wiring portion and the negative wiring portion constituting the differential pair wiring face each other in the thickness direction of the substrate 34 and run parallel to each other. For example, the first negative wiring portion 301n and the second positive wiring portion 302p connected to the first battery cell 11 are arranged such that they face each other in the thickness direction of the substrate 34 and run parallel to each other.

[0043] However, the present disclosure is not limited to this. The positive and negative wiring portions constituting the differential pair wiring may run side by side in the same layer. In other words, the positive and negative wiring portions constituting the differential pair wiring may be provided in parallel in the same layer.

[0044] Each differential pair wiring is connected to a respective terminal pair 60a of the circuit board 50. The terminal pair 60a is a pair of two terminals of the circuit board 50. Therefore, the circuit board 50 has a plurality of terminal pairs 60a. The plurality of terminal pairs 60a are included in the connector section 60. Each terminal pair 60a is individually connected to a respective first ADC 41. The circuit board 50 and the first ADC 41 will be described later.

[0045] 1, 3, and 5, the flexible substrate 30 has portions where pattern wirings on the same layer intersect. In this embodiment, the lower layer wiring 32 intersects. Therefore, the flexible substrate 30 has an escape wiring portion 35 to allow the intersecting lower layer wiring 32 to escape. The escape wiring portion 35 includes a via 33 and an upper layer wiring 31.

[0046] In this embodiment, wiring 3 is employed through which electrical signals for measuring the complex impedance of the battery cells 11 to 18 and for detecting the states of the battery cells 11 to 18 flow. However, the flexible substrate 30 may be provided with wiring 3 other than those described above.

[0047] <Battery Monitoring Device> The battery monitoring device 70 will be described using Figures 1 and 6. Figure 6 mainly illustrates the areas corresponding to some battery cells 10m-1, 10m, and 10m+1. Note that battery cells 10m-1 and 10m+1 are adjacent to battery cell 10m.

[0048] As shown in Figure 6, the battery monitoring device 70 is connected to a plurality of battery cells 11 to 18. The battery monitoring device 70 includes a battery monitoring IC 40 that monitors the plurality of battery cells 11 to 18, and a circuit board 50 that connects the battery monitoring IC 40 to the plurality of battery cells 11 to 18. More specifically, the circuit board 50 is connected to the plurality of battery cells 11 to 18 via a flexible substrate 30. The battery monitoring IC 40 corresponds to a battery monitoring circuit. Note that the battery monitoring device 70 only needs to be connected to the plurality of battery cells 11 to 18, and does not have to correspond to the unit of the assembled battery 10.

[0049] The flexible substrate 30 and the circuit board 50 are connected by a plurality of first terminal portions 81 and a plurality of second terminal portions 82. The first terminal portion 81 and the second terminal portion 82 indicate the portions where the connection terminals of the flexible substrate 30 and the circuit board 50 are connected. The first terminal portion 81 and the second terminal portion 82 are included in the connector portion 60. A pair of the first terminal portion 81 and the second terminal portion 82 comprises one terminal pair 60a. Therefore, it can be said that the flexible substrate 30 and the circuit board 50 include a plurality of pairs of the first terminal portion 81 and the second terminal portion 82. Furthermore, the connection terminals of the circuit board 50 with the flexible substrate 30 include a plurality of terminal pairs 60a.

[0050] The battery monitoring IC 40 and the circuit board 50 are connected by a plurality of third terminals 91 and a plurality of fourth terminals 92. The third terminals 91 and the fourth terminals 92 indicate the locations where the connection terminals of the battery monitoring IC 40 and the connection terminals of the circuit board 50 are connected.

[0051] The connection terminals of the battery monitoring IC 40 include a circuit terminal pair 40a. The circuit terminal pair 40a is a pair of two terminals of the battery monitoring IC 40. The battery monitoring IC 40 has a plurality of circuit terminal pairs 40a. The plurality of circuit terminal pairs 40a are individually connected to each first ADC 41. The plurality of circuit terminal pairs 40a are also individually connected to a plurality of terminal pairs 60a. Therefore, each differential pair wiring is connected to each circuit terminal pair 40a via each terminal pair 60a.

[0052] As shown in Figure 6, the battery monitoring IC 40 includes a first ADC 41, a second ADC 42, a complex impedance measurement circuit 43, a first voltage measurement circuit 44, a second voltage measurement circuit 45, an equalization circuit 46, an equalization switch 47, and a control circuit 48. In the drawing, the complex impedance measurement circuit 43 is designated ZC, the first voltage measurement circuit 44 is designated 1VC, the second voltage measurement circuit 45 is designated 2VC, the equalization circuit 46 is designated EC, and the control circuit 48 is designated CC. ADC is an abbreviation for Analog to Digital Converter. The first ADC 41 corresponds to the first conversion circuit. The second ADC 42 corresponds to the second conversion circuit.

[0053] The battery monitoring IC 40 has a circuit terminal pair 40a connected to each first ADC 41 and a target cell corresponding to each first ADC 41. The circuit terminal pair 40a is provided individually for each first ADC 41.

[0054] The first ADC 41, the second ADC 42, the complex impedance measuring circuit 43, the first voltage measuring circuit 44, and the second voltage measuring circuit 45 are provided corresponding to each of the plurality of battery cells 11 to 18. The equalization circuit 46 and the equalization switch 47 are provided corresponding to each of the plurality of battery cells 11 to 18. The control circuit 48 is provided in common to the plurality of battery cells 11 to 18.

[0055] As described above, the battery monitoring IC 40 is provided with two ADCs 41, 42 for each battery cell. Therefore, the battery monitoring IC 40 has a plurality of first ADCs 41 and a plurality of second ADCs 42. As an example, Fig. 6 illustrates the ADCs 41, 42 for the battery cell 10m-1, the ADCs 41, 42 for the battery cell 10m, the ADCs 41, 42 for the battery cell 10m+1, and the ADCs 41, 42 for the battery cell 10m+2.

[0056] The first ADC 41 for battery cell 10m-1 and the first ADC 41 for battery cell 10m+1 can also be considered conversion circuits adjacent to the first ADC 41 for battery cell 10m. The battery monitoring IC 40 includes a pair of second ADCs 42 connected to the same battery cell as each first ADC 41.

[0057] The ADCs 41 and 42 convert analog signals into digital signals (hereinafter referred to as AD conversion). The ADCs 41 and 42 receive instructions from the control circuit 48 about the start timing of the conversion period. The ADCs 41 and 42 convert the analog signals into digital signals for a predetermined period from the start timing. Below, the first ADC 41 and second ADC 42 corresponding to the same battery cell will be described as a set.

[0058] The input terminal of the first ADC 41 is connected to a third terminal 91 and a fourth terminal 92. The third terminal 91 is connected to the first terminal 81. Meanwhile, the fourth terminal 92 is connected to the second terminal 82. The first ADC 41 is connected to the positive terminal and the negative terminal of one battery cell via the third terminal 91 and the fourth terminal 92.

[0059] It can be said that the first terminal 81 and the second terminal 82 connected to the first ADC 41 include the terminal pair 60a corresponding to the first ADC 41. For example, the first terminal 81 connected to the positive terminal of the battery cell 10m and the second terminal 82 connected to the negative terminal of the battery cell 10m include the terminal pair 60a corresponding to the first ADC 41 for the battery cell 10m. The first terminal 81 connected to the positive terminal of the battery cell 10m+1 and the second terminal 82 connected to the negative terminal of the battery cell 10m+1 include the terminal pair 60a corresponding to the first ADC 41 for the battery cell 10m+1.

[0060] The battery cell connected to the first ADC 41 corresponds to the target cell. As will be described later, the first ADC 41 outputs an electrical signal for measuring the complex impedance of the battery cell. Therefore, the target cell can also be called a measurement target cell.

[0061] The output terminal of the first ADC 41 is connected to the complex impedance measurement circuit 43. The first ADC 41 converts the voltage across the target cell into a digital signal and outputs it as an electrical signal for measuring the complex impedance of the target cell. The complex impedance measurement circuit 43 is a digital circuit that uses the electrical signal to calculate a complex voltage of a specific frequency. The complex voltage is a voltage for measuring the complex impedance. The control circuit 48 measures (calculates) the complex impedance of the target cell using the complex voltage output from the complex impedance measurement circuit 43. More specifically, the control circuit 48 is configured to acquire the complex current flowing through the battery pack 10. The control circuit 48 then calculates the complex impedance using the complex voltage and complex current.

[0062] In this embodiment, the control circuit 48 is used as an example of a control circuit that measures the complex impedance of the target cell. However, the present disclosure is not limited to this. The complex impedance of the target cell may be measured by a microcomputer. That is, the microcomputer may measure the complex impedance of battery cells in multiple assembled batteries 10. In this case, the microcomputer is configured to be able to acquire the complex current flowing through the assembled batteries 10 and to acquire the complex voltage from each assembled battery 10. Therefore, the microcomputer is included in the control circuit. The microcomputer may be configured to be able to acquire the complex voltage and complex current via a communication interface. The battery monitoring device 70 may include a microcomputer.

[0063] Furthermore, the output terminal of the first ADC 41 is connected to a first voltage measurement circuit 44. The first ADC 41 converts the voltage across the target cell into a digital signal and outputs it as an electrical signal for detecting the state of the target cell. In other words, the electrical signal output by the first ADC 41 is used for complex impedance measurement and state detection. The first voltage measurement circuit 44 is a digital circuit that measures the battery voltage of the target cell using the electrical signal output from the first ADC 41. The first voltage measurement circuit 44 can also be said to calculate the battery voltage for state detection. The first voltage measurement circuit 44 can be, for example, a low-pass filter. The second voltage measurement circuit 45, which will be described later, is similarly configured.

[0064] The input terminal of the second ADC 42 is connected to the third terminal unit 91 and the fourth terminal unit 92. The output terminal of the second ADC 42 is connected to the second voltage measurement circuit 45. The second ADC 42 converts the voltage across the target cell into a digital signal and outputs it as an electrical signal for detecting the state of the target cell.

[0065] The second voltage measurement circuit 45 is a digital circuit that measures the battery voltage of the target cell using the electrical signal output from the second ADC 42. The second voltage measurement circuit 45 can also be said to calculate a battery voltage for status detection. The second ADC 42 and the second voltage measurement circuit 45 are provided to monitor the status of the target cell for faults. The status of the target cell may also include the status of the path leading to the target cell.

[0066] The control circuit 48 monitors for faults by comparing the measurement results of the first voltage measurement circuit 44 and the second voltage measurement circuit 45. For example, the control circuit 48 determines that a fault has occurred if the two measurement results differ or if there is a discrepancy between the two measurement results of a predetermined value or more. The measurement result is the battery voltage of the target cell.

[0067] As described above, the paired ADCs 41 and 42 are connected to the third terminal 91 and the fourth terminal 92. However, the terminals 91 and 92 connected to the second ADC 42 are different from the terminals 91 and 92 connected to the input terminals of the paired first ADC 41. In other words, the second ADC 42 is connected to a terminal pair 60a connected to a first ADC 41 different from the first ADC 41 of the pair.

[0068] As an example, the ADCs 41 and 42 for the battery cell 10m will be used for explanation. The first ADC 41 is connected to the third terminal 91 and the fourth terminal 92, which are connected to the differential pair wiring for the battery cell 10m. Meanwhile, the second ADC 42 is connected to the fourth terminal 92, which is connected to one side of the differential pair wiring for the battery cell 10m+1, and the third terminal 91, which is connected to one side of the differential pair wiring for the battery cell 10m-1. In other words, the first ADC 41 is connected to the differential pair wiring for the target cell. Meanwhile, the second ADC 42 is connected to the differential pair wiring for the two battery cells adjacent to the target cell. In this way, the second ADC 42 can be said to be connected to the terminal pair 60a connected to the adjacent conversion circuit. The connected terminal pair 60a can also be said to be the corresponding terminal pair 60a.

[0069] The ADCs 41 and 42 may have the same or different conversion frequencies for AD conversion. Here, as an example, the ADCs 41 and 42 are used, each with a different conversion frequency. The first ADCs 41 include a first high-frequency circuit and a first low-frequency circuit, each with a different conversion frequency. Similarly, the second ADCs 42 include a second high-frequency circuit and a second low-frequency circuit, each with a different conversion frequency. The low-frequency and high-frequency are relative conversion frequencies. The low-frequency circuit has a lower conversion frequency than the high-frequency circuit.

[0070] The first high-frequency circuit and the second low-frequency circuit are configured as a pair and have the same target cell. The first low-frequency circuit and the second high-frequency circuit are configured as a pair and have the same target cell. For example, for the ADCs 41 and 42 corresponding to battery cell 10m+1, the first ADC 41 is the first low-frequency circuit and the second ADC 42 is the second high-frequency circuit. For the ADCs 41 and 42 corresponding to battery cell 10m, the first ADC 41 is the first high-frequency circuit and the second ADC 42 is the second low-frequency circuit. For the ADCs 41 and 42 corresponding to battery cell 10m-1, the first ADC 41 is the first low-frequency circuit and the second ADC 42 is the second high-frequency circuit.

[0071] The first high-frequency circuit and the second high-frequency circuit can also be considered as main ADCs. The first low-frequency circuit and the second low-frequency circuit can also be considered as sub-ADCs. Furthermore, the first voltage measurement circuit 44 connected to the first high-frequency circuit and the second voltage measurement circuit 45 connected to the second high-frequency circuit can also be considered as main voltage measurement circuits. On the other hand, the first voltage measurement circuit 44 connected to the first low-frequency circuit and the second voltage measurement circuit 45 connected to the second low-frequency circuit can also be considered as sub-voltage measurement circuits.

[0072] Furthermore, all of the first ADCs 41 may have a higher conversion frequency than all of the second ADCs 42. In this case, the first ADCs 41 have the same conversion frequency. Similarly, the first ADCs 41 have the same conversion frequency. Furthermore, the ADCs connected to the complex impedance measurement circuits 43 may be capable of AD conversion with higher accuracy than ADCs not connected to the complex impedance measurement circuits 43.

[0073] The equalization switch 47 is a switch for equalizing the variations in capacity among the plurality of battery cells 11 to 18. In other words, the equalization switch 47 is a switch for passing current to equalize the capacities of the plurality of battery cells 11 to 18. The equalization switch 47 is controlled to be turned on or off by the equalization circuit 46.

[0074] The first ADC 41 includes a connection conversion circuit to which the equalization switch 47 is connected and a non-connection conversion circuit to which the equalization switch 47 is not connected. The first ADC 41 for the battery cell 10m+1 and the first ADC 41 for the battery cell 10m-1 correspond to the connection conversion circuit. The first ADC 41 for the battery cell 10m corresponds to the non-connection conversion circuit.

[0075] The circuit board 50 includes an electrically insulating substrate and conductive wiring provided on the substrate. The circuit board 50 is a so-called printed circuit board.

[0076] The wiring of the circuit board 50 includes a portion connecting the first terminal portion 81 and the third terminal portion 91, and a portion connecting the second terminal portion 82 and the fourth terminal portion 92. The circuit board 50 includes, for example, a filter circuit including a resistor and a capacitor.

[0077] The battery monitoring IC 40 is mounted on the circuit board 50. The circuit board 50 has connection terminals to which a plurality of circuit terminal pairs 40a are connected. The connection terminals are connected to the wiring of the circuit board 50. The connection terminals can also be considered as part of the wiring of the circuit board 50.

[0078] The circuit board 50 also has terminal pairs 60a connected to each first ADC 41 and the target cell corresponding to each first ADC 41. The terminal pairs 60a are individually provided for each first ADC 41. Therefore, the circuit board 50 has a plurality of terminal pairs 60a. The plurality of terminal pairs 60a are connected to wiring on the circuit board 50. The plurality of terminal pairs 60a can also be considered as part of the wiring on the circuit board 50.

[0079] <Effects> As described above, the flexible substrate 30 includes the upper layer wiring 31, the lower layer wiring 32, and the wiring 3 having the via 33. Therefore, the flexible substrate 30 can improve the degree of freedom in routing the wiring 3 compared to a single-layer substrate in which the wiring 3 is in a single layer. Therefore, the flexible substrate 30 can prevent the gap between the positive wiring portion and the negative wiring portion of the differential pair wiring from becoming wide.

[0080] In other words, the flexible substrate 30 facilitates the formation of a differential pair of wiring between the positive and negative wiring portions by improving the degree of freedom in routing the wiring 3. Therefore, the flexible substrate 30 can reduce noise in the differential pair of wiring. More specifically, the flexible substrate 30 can reduce induced noise between the positive and negative wiring portions that constitute the differential pair of wiring. The main source of induced noise is excitation current.

[0081] In addition, the flexible substrate 30 can be said to reduce the area Z1 between the positive and negative wiring portions that make up the differential pair wiring. Therefore, the flexible substrate 30 can reduce noise in the differential pair wiring. The area Z1 can also be said to be the noise-affected area.

[0082] Furthermore, the flexible substrate 30 configures a differential pair of wirings with upper layer wiring 31 and lower layer wiring 32. Therefore, the distance between the positive and negative wiring portions of the differential pair of wirings can be determined by the thickness of the base material 34 disposed between the positive and negative wiring portions. Therefore, the flexible substrate 30 can narrow the distance between the positive and negative wiring portions of the differential pair of wirings compared to when the differential pair of wirings is configured with wirings on the same layer.

[0083] The battery monitoring device 70 includes a plurality of first ADCs 41 that output battery voltages for measuring the complex impedance of each of the battery cells 11 to 18. A terminal pair 60a connected to each of the first ADCs 41 and the cell under measurement is provided individually for each first ADC 41. This makes it easy to connect the battery monitoring device 70 to the plurality of battery cells 11 to 18 using differential pair wiring. As a result, the battery monitoring device 70 can output a battery voltage for state detection from the second ADC 42 and a battery voltage for complex impedance measurement with reduced noise influence from the first ADC 41.

[0084] Therefore, the battery monitoring device 70 can accurately measure the complex impedance of each battery cell 11 to 18. In other words, the battery monitoring device 70 can measure the complex impedance in a state where the influence of inductive noise entering between the positive and negative wiring portions that make up the differential pair wiring is reduced. Note that the battery monitoring device 70 can reduce the number of terminals between the battery monitoring IC 40 and the circuit board 50 compared to the configuration of the sixth embodiment, which will be described later.

[0085] The battery device also includes a flexible substrate 30 and a battery monitoring device 70. Therefore, the battery device can output a battery voltage for complex impedance measurement with reduced noise influence from the first ADC 41. The battery device can then accurately measure the complex impedance of each of the battery cells 11 to 18.

[0086] The preferred embodiments of the present disclosure have been described above. However, the present disclosure is not limited to the above embodiments, and various modifications are possible within the scope of the present disclosure. Below, the second to seventh embodiments will be described as other aspects of the present disclosure. The above embodiments and the second to seventh embodiments can be implemented independently, or can be implemented in appropriate combinations. The present disclosure is not limited to the combinations shown in the embodiments, and can be implemented in various combinations.

[0087] Second Embodiment A battery device according to a second embodiment will be described using Figures 7 to 10. In the second embodiment, differences from the first embodiment will be mainly described. The second embodiment differs from the first embodiment in the flexible substrate 30. The flexible substrate 30 in the second embodiment has the same components as the first embodiment, but differs from the first embodiment in the routing of the wiring 3. Figure 7 is a plan view corresponding to Figure 1. The battery monitoring device 70 is omitted from Figure 7.

[0088] 7, 8, and 9, the differential pair wirings have a partially reversed top-to-bottom relationship in the stacking direction between the positive and negative wiring portions. For example, the eighth negative wiring portion 308n includes an upper layer wiring 31 and a lower layer wiring 32. Similarly, the ninth positive wiring portion 309p includes an upper layer wiring 31 and a lower layer wiring 32.

[0089] In both wiring sections 308n and 309p, the upper layer wiring 31 and the lower layer wiring 32 are partially interchanged via vias 33 and escape wiring sections 35. In the eighth negative wiring section 308n, the upper layer wiring 32 is interchanged in the order of upper layer wiring 31, lower layer wiring 32, and upper layer wiring 31 from the eighth battery cell 18 side. In the ninth positive wiring section 309p, the upper layer wiring 31 is interchanged in the order of upper layer wiring 31, lower layer wiring 32, upper layer wiring 31, and lower layer wiring 32 from the eighth battery cell 18 side.

[0090] It is also preferable that the differential pair wirings be reversed in their up-down position every time they cross an even-numbered battery cell from the end, and that the differential pair wirings be reversed in their up-down position every two battery cells.

[0091] 10 , an example is adopted in which the differential pair wiring has positive wiring portions 303p to 309p configured with lower layer wiring 32 and negative wiring portions 302n to 308n configured with upper layer wiring 31 at the end portion on the circuit board 50 side. Furthermore, the positive wiring portion 302p is configured with upper layer wiring 31. The negative wiring portion 301n is configured with lower layer wiring 32. However, the flexible substrate 30 may have the positive wiring portion 302p configured with lower layer wiring 32 and the negative wiring portion 301n configured with upper layer wiring 31 at the end portion on the circuit board 50 side.

[0092] The second embodiment can achieve the same effects as the first embodiment. Furthermore, in the flexible substrate 30, each differential pair wiring forms a twisted pair wiring. Therefore, the flexible substrate 30 can further reduce noise in the differential pair wiring.

[0093] In other words, current flows between the positive and negative wiring sections that make up the differential pair wiring when magnetic flux passes between them. However, the direction of the current is reversed between adjacent wiring sections that are upside down. As a result, the currents cancel each other out. Therefore, the electrical signals flowing through the differential pair wiring are less susceptible to external influences.

[0094] Furthermore, the magnetic flux generated by the electrical signals flowing through the differential pair wiring is reversed between adjacent wirings that are upside down. As a result, the magnetic fluxes cancel each other out. Therefore, the flexible substrate 30 is less likely to emit noise to the outside due to the electrical signals flowing through the differential pair wiring.

[0095] The battery monitoring device 70 is connected to each of the battery cells 11 to 18 via the flexible substrate 30. Therefore, the battery monitoring device 70 can measure the complex impedance in a state where the influence of inductive noise entering between the positive electrode wiring portions 302p to 309p and the negative electrode wiring portions 301n to 308n is further reduced.

[0096] (Third embodiment) A battery device according to a third embodiment will be described using Figures 11 to 14. In the third embodiment, differences from the first embodiment will be mainly described. In the third embodiment, the flexible substrate 30 is different from the first embodiment. The flexible substrate 30 in the third embodiment has the same components as the first embodiment, but differs from the first embodiment in the routing of the wiring 3. Figure 11 is a plan view corresponding to Figure 1. The battery monitoring device 70 is omitted from Figure 11.

[0097] 11, 12, and 13, in the flexible substrate 30, the positive wiring portions 302p to 309p and the negative wiring portions 301n to 308n do not overlap in the stacking direction. That is, in the differential pair wiring, the positive wiring portions and the negative wiring portions are arranged in a positional relationship where they are offset in the width direction perpendicular to the thickness direction of the substrate 34. For example, the positive wiring portion 309p and the negative wiring portion 308n are in a positional relationship where they are offset in the width direction. Therefore, the positive wiring portion and the negative wiring portion that make up the differential pair wiring face each other and run parallel to each other in an oblique positional relationship.

[0098] As shown in FIG. 14, at the end of the differential pair wiring on the circuit board 50 side, the positive wiring portions 302p to 309p are configured by the upper layer wiring 31, and the negative wiring portions 301n to 308n are configured by the lower layer wiring 32.

[0099] The width direction coincides with the longitudinal direction of each of the battery cells 11 to 18. The width direction can also be said to be a direction perpendicular to the thickness direction of the substrate 34 and perpendicular to the arrangement direction of the multiple battery cells 11 to 18.

[0100] The third embodiment can achieve the same effects as the first embodiment.

[0101] (Fourth embodiment) A battery device according to a fourth embodiment will be described using Figures 15 to 18. In the fourth embodiment, differences from the second embodiment will be mainly described. The fourth embodiment differs from the second embodiment in the flexible substrate 30. The flexible substrate 30 in the fourth embodiment has the same components as the second embodiment, but differs from the second embodiment in the routing of the wiring 3. Figure 15 is a plan view corresponding to Figure 1. The battery monitoring device 70 is omitted from Figure 15.

[0102] 15, 16, and 17, the differential pair wirings are arranged such that the positive and negative wiring portions are offset from each other in the width direction perpendicular to the thickness direction of the substrate 34. Furthermore, the differential pair wirings are partially reversed in the up-down relationship in the stacking direction of the positive and negative wiring portions. In other words, the fourth embodiment can be said to be a combination of the second and third embodiments. Therefore, in the flexible substrate 30, each differential pair wiring forms a twisted pair wiring.

[0103] For example, the eighth negative wiring portion 308n includes upper layer wiring 31 and lower layer wiring 32. Similarly, the ninth positive wiring portion 309p includes upper layer wiring 31 and lower layer wiring 32. In the upper layer wiring 31, parts of the ninth positive wiring portion 309p and parts of the eighth negative wiring portion 308n are alternately arranged. In the lower layer wiring 32, parts of the ninth positive wiring portion 309p and parts of the eighth negative wiring portion 308n are alternately arranged.

[0104] 18 , the differential pair wiring is configured in the same manner as in the second embodiment at the end on the circuit board 50 side. However, the flexible substrate 30 may have the positive wiring portion 302p configured by the lower layer wiring 32 and the negative wiring portion 301n configured by the upper layer wiring 31 at the end on the circuit board 50 side.

[0105] The fourth embodiment can achieve the same effects as the second and third embodiments.

[0106] Fifth Embodiment A battery device according to a fifth embodiment will be described with reference to Fig. 19. In the fifth embodiment, differences from the first embodiment will be mainly described. The fifth embodiment differs from the first embodiment in the battery monitoring IC 40. Fig. 19 is a circuit diagram equivalent to Fig. 6.

[0107] The battery monitoring IC 40 has a common first ADC 41 for adjacent conversion circuits. That is, one first ADC 41 is provided for two adjacent battery cells. As in the first embodiment, the first ADC 41 is connected to a complex impedance measurement circuit 43 and a first voltage measurement circuit 44. On the other hand, the second ADC 42 is connected to a second voltage measurement circuit 45.

[0108] For example, one first ADC 41 corresponds to battery cell 10m and battery cell 10m+1. The target cells of this first ADC 41 are battery cell 10m and battery cell 10m+1. Furthermore, another first ADC 41 corresponds to battery cell 10m-1 and battery cell 10m-2. The target cells of this first ADC 41 are battery cell 10m-1 and battery cell 10m-2.

[0109] Therefore, the second ADC 42 and the first ADC 41 are connected to the battery cell 10m+1 and the battery cell 10m-1. When monitoring for a fault in the battery cell 10m+1 or the battery cell 10m-1, the control circuit 48 compares the measurement results of the first voltage measurement circuit 44 and the measurement results of the second voltage measurement circuit 45.

[0110] On the other hand, the battery cell 10m and the battery cell 10m-2 are connected to two first ADCs 41. When monitoring for a fault in the battery cell 10m or the battery cell 10m-2, the control circuit 48 compares the measurement result of one first voltage measurement circuit 44 with the measurement result of the other first voltage measurement circuit 44.

[0111] Note that, in this embodiment, ADCs 41, 42 with different conversion frequencies may also be used. For example, for the ADCs 41, 42 corresponding to battery cell 10m+1 and battery cell 10m-1, the first ADC 41 is the first low-frequency circuit and the second ADC 42 is the second high-frequency circuit. For the ADCs 41, 42 corresponding to battery cell 10m and battery cell 10m-2, the common first ADC 41 is the first low-frequency circuit and the other first ADC 41 is the first high-frequency circuit. However, the first ADC 41 and the second ADC 42 may have the same conversion frequency.

[0112] As described above, the battery monitoring IC 40 includes a first ADC 41 that is provided in common to the two battery cells. Therefore, the common first ADC 41 is connected to the battery cells via a multiplexer (MUX) 49. The multiplexer 49 is controlled by the control circuit 48. Therefore, the common first ADC 41 is selectively connected to the two battery cells.

[0113] The third embodiment can achieve the same effects as the first embodiment. Furthermore, the third embodiment can reduce the number of first ADCs 41 compared to the first embodiment. Note that the fifth embodiment can be implemented in combination with the second to fourth embodiments and the seventh embodiment.

[0114] Sixth Embodiment A battery device according to a sixth embodiment will be described with reference to Fig. 20. In the sixth embodiment, differences from the first embodiment will be mainly described. The sixth embodiment differs from the first embodiment in the battery monitoring IC 40. Fig. 20 is a circuit diagram equivalent to Fig. 6.

[0115] The first ADC 41 has a higher conversion frequency than the second ADC 42. The first ADCs 41 have the same conversion frequency. Similarly, the first ADCs 41 have the same conversion frequency.

[0116] 20 , the battery monitoring device 70 includes a fifth terminal 93 in addition to the third terminal 91 and the fourth terminal 92. The fifth terminal 93 is a terminal that connects the battery monitoring IC 40 to the circuit board 50. The fifth terminal 93 is also a terminal for the second ADC 42.

[0117] Although the battery monitoring device 70 has a larger number of terminals than the first embodiment, it can output a battery voltage for complex impedance measurement with reduced influence of noise from the first ADC 41, just like the first embodiment. Note that the sixth embodiment can be implemented in combination with the second to fourth embodiments and the seventh embodiment.

[0118] Seventh Embodiment A battery device according to a seventh embodiment will be described with reference to Fig. 21. In the seventh embodiment, differences from the first embodiment will be mainly described. The seventh embodiment differs from the first embodiment in the flexible substrate 30. Fig. 21 is a circuit diagram corresponding to Fig. 4.

[0119] 21 , similar to the first embodiment, the multiple differential pair wirings are arranged side by side in the width direction perpendicular to the thickness direction of the substrate 34. The positive and negative wiring portions of adjacent differential pair wirings have different widths. For example, the differential pair wirings connected to even-numbered battery cells have a wider wiring width than the differential pair wirings connected to odd-numbered battery cells. Alternatively, the differential pair wirings connected to odd-numbered battery cells have a wider wiring width than the differential pair wirings connected to even-numbered battery cells.

[0120] The seventh embodiment can achieve the same effects as the first embodiment. Furthermore, the flexible substrate 30 has alternating wiring that carries current to equalize capacitance variations. Therefore, it is desirable to increase the allowable current and reduce resistance by widening the wiring width of the flexible substrate 30 as described above. The seventh embodiment can be implemented in combination with the second to fourth embodiments.

[0121] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and modifications within the scope of equivalents. In addition, although various combinations and forms are shown in the present disclosure, other combinations and forms including only one element, more, or less than one element are also within the scope and spirit of the present disclosure.

Claims

1. A battery monitoring device connected to a plurality of battery cells (11-18), comprising: a battery monitoring circuit (40) that monitors the plurality of battery cells; and a circuit board (50) that connects the battery monitoring circuit to the battery cells, wherein the battery monitoring circuit comprises: a plurality of first conversion circuits (41) connected to positive and negative terminals of each battery cell, converting analog signals to digital signals and outputting electrical signals for measuring the complex impedance of each battery cell; and a plurality of second conversion circuits (42) connected to positive and negative terminals of each battery cell, converting analog signals to digital signals and outputting electrical signals for detecting the state of each battery cell, wherein the first conversion circuit and the second conversion circuit are connected in pairs to each battery cell, and the circuit board comprises: a plurality of terminal pairs (60a) connected to the first conversion circuit and a target cell, which is the battery cell corresponding to the first conversion circuit, wherein the terminal pairs are provided individually for the first conversion circuit.

2. The battery monitoring device as described in claim 1, further comprising: a complex impedance measurement circuit (43) connected to each first conversion circuit and configured to calculate a complex voltage for complex impedance measurement based on an electrical signal output from the first conversion circuit; and a control circuit (48) configured to measure the complex impedance of the target cell based on the complex voltage.

3. The battery monitoring device of claim 2, wherein the plurality of first conversion circuits output electrical signals for complex impedance measurement and state detection, and the device comprises a first voltage measurement circuit (44) connected to each first conversion circuit and calculating a battery voltage for state detection based on the electrical signal output from the first conversion circuit, and a second voltage measurement circuit (45) connected to each second conversion circuit and calculating a battery voltage for state detection based on the electrical signal output from the second conversion circuit, and the control circuit detects the state of the target cell based on the battery voltages output from the first voltage measurement circuit and the second voltage measurement circuit connected to the pair of the first conversion circuit and the second conversion circuit.

4. A battery monitoring device as described in claim 3, wherein the plurality of first conversion circuits include a first high-frequency circuit and a first low-frequency circuit having different conversion frequencies, the plurality of second conversion circuits include a second high-frequency circuit and a second low-frequency circuit having different conversion frequencies, the first high-frequency circuit and the second low-frequency circuit are provided in pairs, and the first low-frequency circuit and the second high-frequency circuit are provided in pairs.

5. A battery monitoring device according to claim 3, wherein the first conversion circuit has a higher conversion frequency than the second conversion circuit.

6. A battery monitoring device according to any one of claims 1 to 5, wherein the second conversion circuit is connected to the terminal pair of a first conversion circuit other than the first conversion circuit that is paired with the second conversion circuit.

7. A battery monitoring device as described in any one of claims 2 to 5, further comprising an equalization switch (47) that equalizes the capacity variations of the plurality of battery cells, and the plurality of first conversion circuits include a connection conversion circuit to which the equalization switch is connected and a non-connection conversion circuit to which the equalization switch is not connected.

8. A battery monitoring circuit connected to a plurality of battery cells (11-18) via a circuit board (50) and monitoring the battery cells, comprising: a plurality of first conversion circuits (41) connected to positive and negative terminals of each battery cell, converting analog signals into digital signals and outputting electrical signals for measuring the complex impedance of each battery cell; a plurality of second conversion circuits (42) connected to positive and negative terminals of each battery cell, converting analog signals into digital signals and outputting electrical signals for detecting the state of each battery cell; and circuit terminal pairs (40a) connected to each of the first conversion circuits and a target cell which is the battery cell corresponding to each of the first conversion circuits, wherein the first conversion circuit and the second conversion circuit are connected in pairs to each battery cell, and the circuit terminal pairs are provided individually for each first conversion circuit.

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