Disconnection detection device and battery monitoring device

Abstract

The purpose of the present invention is to provide: a disconnection detection device that is capable of detecting a wire disconnection normally on the basis of cell voltage, even if each wire is provided with a CR low-pass filter and an electronic switch of a discharge circuit has a protection function; and a battery monitoring device.　The present invention provides a disconnection detection device comprising a voltage detection circuit that detects the cell voltage of a plurality of battery cells which are provided to a battery, which are connected to each other in series, and to which discharge circuits provided with an electronic switch are connected in parallel, CR low-pass filters that are respectively provided to a plurality of wires which connect the battery cells and the voltage detection circuit, and a control unit that causes the discharge circuits to perform balanced discharge and that detects a wire disconnection on the basis of cell voltage. The electronic switches have a protection function for prohibiting transition to an ON state. The control unit operates either one of a pair of electronic switches related to a pair of battery cells that are adjacent to each other, thereby discharging a charge stored in a CR low-pass filter, and detects a wire disconnection on the basis of cell voltage after the discharge.

Description

Disconnection detection device and battery monitoring device

[0001] The present invention relates to a wire break detection device and a battery monitoring device.

[0002] Patent Document 1 below discloses a cell balance control device. This cell balance control device includes a discharge circuit consisting of a series circuit of bypass resistors and switching elements and connected in parallel to each of multiple battery cells that make up a battery, a voltage detection circuit that detects the voltage of each battery cell, and a control unit that controls each switching element to equalize the voltage of each battery cell based on the voltage detection results of each battery cell obtained from the voltage detection circuit, and controls the switching elements of the discharge circuits connected to adjacent battery cells with different duty ratios, and detects breaks in the wiring drawn from both ends of each battery cell based on the potential difference between the adjacent battery cells.

[0003] In addition to detecting such wiring breaks, the cell balance control device also balances (equals) the charge amounts of multiple battery cells by forcibly discharging the battery cells using a discharge circuit. That is, when the cell voltage of a certain battery cell is higher than the cell voltage of an adjacent battery cell, the cell balance control device equalizes the charge amounts of each battery cell by forcibly discharging (equalizing discharge) using the discharge circuit connected to the adjacent battery cell.

[0004] Japanese Patent Application Publication No. 2013-085354

[0005] Although not described in Patent Document 1, some cell balance control devices include a CR low-pass filter on each wiring. This CR low-pass filter is an additional circuit that removes noise and other impinging noise from the wiring to more accurately detect cell voltages, and is provided on each wiring closer to the voltage detection circuit than the discharge circuit.

[0006] Furthermore, some cell balance control devices are equipped with a protection function to prevent overcurrent from flowing through the switching element (electronic switch) of the discharge circuit. When such a protection function is provided, if a wiring break occurs, a voltage twice the normal voltage may be applied to the electronic switch.

[0007] If each of these wirings is equipped with a CR low-pass filter and the electronic switch of the discharge circuit is provided with a protection function, if a break occurs in the low-potential side wiring connected to a certain battery cell during equalization discharge of that battery cell, the capacitor of the CR low-pass filter installed in the low-potential side wiring will be charged with a voltage twice the normally applied voltage.

[0008] However, this double voltage activates the protection function, preventing the electronic switch of the discharge circuit connected to the capacitor from being switched on, preventing the capacitor from discharging. If the capacitor remains charged, it will not be possible to properly detect an open circuit based on the cell voltage.

[0009] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a wire break detection device and a battery monitoring device that can correctly detect a wire break based on cell voltage, even when each wire is equipped with a CR low-pass filter and the electronic switch of the discharge circuit has a protection function.

[0010] A first aspect of the wire break detection device of the present disclosure is a wire break detection device for a battery having a plurality of battery cells connected in series with each other and each having a discharge circuit, each having an electronic switch, connected in parallel, the wire break detection device comprising: a voltage detection circuit that detects the cell voltages of the battery cells; CR low-pass filters provided on each of a plurality of wires connecting the battery cells to the voltage detection circuit; and a control unit that equalizes discharge of the discharge circuits and detects wire breaks in the wires based on the cell voltages, wherein the electronic switches have a protection function that prohibits transition to an ON state, and the control unit operates one of a pair of electronic switches associated with a pair of adjacent battery cells to neutralize the charge accumulated in the CR low-pass filters, and after the neutralization, detects wire breaks in the wires based on the cell voltages.

[0011] In the second aspect of the open circuit detection device of the present disclosure, when the control unit determines that the protection function of the electronic switch that is pre-set as the neutralization switch for the CR low-pass filter is activated, the control unit neutralizes the CR low-pass filter by setting the electronic switch that is paired with the electronic switch whose protection function has been activated to the ON state.

[0012] In the third aspect of the open circuit detection device of the present disclosure, the control unit distinguishes between an open circuit in the wiring and an abnormality in the battery cell based on the differential voltage and sum voltage of the cell voltages of a pair of the battery cells when at least one of the discharge circuits is discharged.

[0013] In the disconnection detection device according to a fourth aspect of the present disclosure, the discharge circuit is a series circuit of the electronic switch and a resistor.

[0014] A battery monitoring device according to a first aspect of the present disclosure includes a wire break detection device according to any one of the first to fourth aspects, and controls connection of the battery to a load based on a wire break detection result of the wire break detection device.

[0015] According to the present disclosure, it is possible to provide a wire break detection device and a battery monitoring device that can normally detect a wire break based on the cell voltage, even when each wire is equipped with a CR low-pass filter and the electronic switch of the discharge circuit has a protection function.

[0016] 1 is a block diagram showing a configuration of a battery monitoring device A according to an embodiment of the present disclosure; FIG. 2 is a flowchart showing an operation of the battery monitoring device A according to an embodiment of the present disclosure; FIG. 3 is a timing chart showing an operation of the battery monitoring device A according to an embodiment of the present disclosure; FIG. 4 is a first circuit diagram showing an operation of the battery monitoring device A according to an embodiment of the present disclosure; FIG. 5 is a first characteristic diagram showing an operation of the battery monitoring device A according to an embodiment of the present disclosure; and FIG. 6 is a second characteristic diagram showing an operation of the battery monitoring device A according to an embodiment of the present disclosure.

[0017] An embodiment of the present invention will be described below with reference to the drawings. First, the functional configuration of a battery monitoring device A according to this embodiment will be described with reference to FIG.

[0018] This battery monitoring device A is mounted on an electric vehicle such as an electric car or a hybrid car, and monitors a battery B such as a lithium-ion battery or a fuel cell. The battery monitoring device A controls the connection of battery B to a load based on the monitoring results of battery B (disconnection detection results).

[0019] In FIG. 1, a pair of adjacent battery cells B ｎ , B ｎ＋１ However, the battery B actually consists of multiple, i.e., (n+1) battery cells B １ , ..., B ｎ , B ｎ＋１ In other words, the battery B is made up of the first to (n+1)th battery cells B １ ~B ｎ＋１ The output voltage of the first to n+1th cell voltages V １ ~V ｎ＋１ The sum of these voltages is defined as the battery voltage. Note that n is an arbitrary natural number.

[0020] 1st to (n+1)th battery cells B １ ~B ｎ＋１ As shown in the figure, each electrode is connected to a plurality of (n+1) wirings VH １ , ..., VH ｎ , V.H. ｎ＋１ Each input terminal T of the battery monitoring device A １ , ..., T ｎ , T ｎ＋１ For example, the nth battery cell B ｎ The negative electrode of the first wiring VH ｎ－１ The n-1th input terminal T of the battery monitoring device A is ｎ－１ That is, the first wiring VH ｎ－１ One end of the nth battery cell B ｎ The other end is connected to the (n-1)th input terminal T of the battery monitoring device A. ｎ－１ is connected to.

[0021] nth battery cell B ｎ and the positive electrode of the n+1 battery cell B ｎ＋１ The negative electrode of the nth wiring VH ｎ The n-th input terminal T of the battery monitoring device A isｎ That is, the n-th wiring VH ｎ One end of the nth battery cell B ｎ and the positive electrode of the n+1 battery cell B ｎ＋１ The other end is connected to the n-th input terminal T of the battery monitoring device A. ｎ is connected to.

[0022] Battery cell B ｎ＋１ The positive electrode of the (n+1)th wiring VH ｎ＋１ The n+1 input terminal T of the battery monitoring device A is ｎ＋１ That is, the (n+1)th wiring VH ｎ＋１ One end of the battery cell B ｎ＋１ The other end is connected to the n+1-th input terminal T of the battery monitoring device A. ｎ＋１ is connected to.

[0023] That is, the battery monitoring device A according to this embodiment has (n+1) wirings VH １ , ..., VH ｎ , V.H. ｎ＋１ This battery monitoring device A is connected to the battery B via the first to (n+1)th wirings VH １ ~VH ｎ＋１ If a break occurs in any of the first to n+1th battery cells B １ ~B ｎ＋１ The inter-electrode voltages, that is, the first to (n+1)th cell voltages V1 to V ｎ＋１ Therefore, the battery B cannot be monitored properly.

[0024] For this reason, the battery monitoring device A has the first to (n+1)th wirings VH １ ~VH ｎ＋１ The battery monitoring device A according to this embodiment is provided with a disconnection detection function that detects disconnection of any of the first to (n+1)th cell voltages V １ ~V ｎ＋１ Based on this, the first to (n+1)th wirings VH １ ~VH ｎ＋１ The present invention relates to a disconnection detection device for detecting a disconnection in any of the above.

[0025] As shown in the figure, the battery monitoring device A has the first to (n+1)th input terminals T １ ~T ｎ＋１ In addition, (n+1) first resistors R1 １ ~R1 ｎ＋１ , (n+1) second resistors R2 １ ~R2 ｎ＋１ , (n+1) third resistors R3 １ ~R3 ｎ＋１ , (n+1) first capacitors C1 １ ~C1 ｎ＋１ , (n+1) second capacitors C21 to C2 ｎ＋１ , (n+1) electronic switches D1 to D ｎ＋１ , (n+1) differential amplifiers E １ ~E ｎ＋１ , (n+1) control circuits F １ ~F ｎ＋１ , (n+1) voltage amplifiers G １ ~G ｎ＋１ and an MPU 1.

[0026] 1st to (n+1)th input terminals T １ ~T ｎ＋１ Among them, the n-1th input terminal T ｎ－１ As shown in the figure, the (n-1)th wiring VH ｎ－１ The other end of the second resistor R2 ｎ and one end of the third resistor R3 ｎ The n-th input terminal T ｎ is the nth wiring VH ｎ The other end of the first resistor R1 ｎ One end of the second resistor R2 ｎ and one end of the third resistor R3 ｎ＋１ The n+1-th input terminal T ｎ＋１ is the first resistor R1 ｎ＋１ and one end of the second resistor R2 ｎ＋１ are connected to one end of each.

[0027] (n+1) first resistors R1 １ ~R1 ｎ＋１ , (n+1) second resistors R2 １ ~R2 ｎ＋１ , (n+1) third resistors R3 １ ~R3ｎ＋１ Among these, the first resistor R1 ｎ－１ has one end connected to the n-1th input terminal T ｎ－１ and the third resistor R3 ｎ The other end is connected to one end of the first capacitor C1 ｎ－１ and one end of the nth voltage amplifier G ｎ is connected to one input terminal of the

[0028] First resistor R1 ｎ has one end connected to the n-th input terminal T ｎ , second resistor R2 ｎ and the first resistor R1 ｎ＋１ and the other end is connected to the first capacitor C1 ｎ One end of the nth voltage amplifier G ｎ the other input terminal of the n+1 voltage amplifier G ｎ＋１ is connected to one input terminal of the

[0029] Second resistor R2 ｎ has one end connected to the n-th input terminal T ｎ , first resistor R1 ｎ and one end of the third resistor R3 ｎ＋１ and the other end is connected to one end of the n-th electronic switch D ｎ One end of the second capacitor C2 ｎ and one end of the nth differential amplifier E ｎ is connected to one input terminal of the

[0030] Third resistor R3 ｎ has one end connected to the n-1th input terminal T ｎ－１ and the first resistor R1 ｎ－１ The other end is connected to the other end of the n-th electronic switch Dn, and the second capacitor C2 ｎ and the other end of the nth differential amplifier E ｎ is connected to the other input terminal of the

[0031] First resistor R1 ｎ＋１ has one end connected to the n+1th input terminal T ｎ＋１ and the second resistor R2 ｎ＋１ The other end is connected to one end of the first capacitor C1 ｎ＋１ and one end of the n+1 voltage amplifier G ｎ＋１ is connected to the other input terminal of the

[0032] Second resistor R2 ｎ＋１ has one end connected to the n+1th input terminal T ｎ＋１ and the first resistor R1 ｎ＋１ and the other end is connected to one end of the n+1th electronic switch D ｎ＋１ One end of the second capacitor C2 ｎ＋１ and one end of the n+1 differential amplifier E ｎ＋１ is connected to one input terminal of the

[0033] Third resistor R3 ｎ＋１ has one end connected to the n-th input terminal T ｎ , first resistor R1 ｎ and one end of the second resistor R2 ｎ and the other end is connected to one end of the n+1th electronic switch D ｎ＋１ The other end of the second capacitor C2 ｎ＋１ and the other end of the n+1 differential amplifier E ｎ＋１ is connected to the other input terminal of the

[0034] (n+1) first capacitors C1 １ ~C1 ｎ＋１ , (n+1) second capacitors C21 to C2 ｎ＋１ Among these, the first capacitor C1 ｎ－１ One end of the resistor R1 ｎ－１ and the other end of the nth voltage amplifier G ｎ The first capacitor C1 is connected to one input terminal of the first capacitor C1 and the other terminal of the first capacitor C1 is grounded. ｎ－１ and the first resistor R1 ｎ－１ and form the (n-1)th CR low-pass filter.

[0035] Second capacitor C1 ｎ One end of the resistor R1 ｎ The other end of the nth voltage amplifier G ｎ and one input terminal of the n+1 voltage amplifier G ｎ＋１ The first capacitor C1 is connected to one input terminal of the first capacitor C1 and the other terminal of the first capacitor C1 is grounded. ｎ and the first resistor R1 ｎ and form the n-th CR low-pass filter.

[0036] Third capacitor C2 ｎ is connected to the second resistor R2 ｎThe other end of the nth electronic switch D ｎ and one end of the nth differential amplifier E ｎ and the other end is connected to a third resistor R3 ｎ The other end of the nth electronic switch D ｎ and the other end of the nth differential amplifier E ｎ is connected to the other input terminal of the

[0037] First capacitor C1 ｎ＋１ One end of the resistor R1 ｎ＋１ and the other end of the n+1 voltage amplifier G ｎ＋１ The first capacitor C1 is connected to the other input terminal of the first capacitor C1, and the other terminal is grounded. ｎ＋１ and the first resistor R1 ｎ＋１ and form the (n+1)th CR low-pass filter.

[0038] Second capacitor C2 ｎ＋１ is connected to the second resistor R2 ｎ＋１ The other end of the n+1th electronic switch D ｎ＋１ and one end of the n+1 differential amplifier E ｎ＋１ and the other end is connected to a third resistor R3 ｎ＋１ The other end of the n+1th electronic switch D ｎ＋１ and the other end of the n+1 differential amplifier E ｎ＋１ is connected to the other input terminal of the

[0039] (n+1) electronic switches D1 to D ｎ＋１ Among them, the n-th electronic switch D ｎ is connected to the second resistor R2 ｎ The other end of the second capacitor C2 ｎ and one end of the nth differential amplifier E ｎ and the other end is connected to a third resistor R3 ｎ The other end of the second capacitor C2 ｎ and the other end of the nth differential amplifier E ｎ is connected to the other input terminal of the

[0040] n-th electronic switch D ｎ The n-th electronic switch D is provided with a pair of input terminals. ｎ One of the pair of input terminals is connected to the nth control circuit Fｎ The other input terminal is connected to one of a pair of output terminals of the MPU 1.

[0041] n+1th electronic switch D ｎ＋１ is connected to the second resistor R2 ｎ＋１ The other end of the second capacitor C2 ｎ＋１ and one end of the n+1 differential amplifier E ｎ＋１ and the other end is connected to a third resistor R3 ｎ＋１ The other end of the second capacitor C2 ｎ＋１ and the other end of the n+1 differential amplifier E ｎ＋１ is connected to the other input terminal of the

[0042] n+1th electronic switch D ｎ＋１ The n+1th electronic switch D ｎ＋１ One of the pair of input terminals is connected to the n+1th control circuit F ｎ＋１ The n-th electronic switch D ｎ and the n+1th electronic switch D ｎ＋１ are electronic switches that are adjacent to each other and form a pair.

[0043] Here, the second resistor R2 ｎ , third resistor R3 ｎ and nth electronic switch D ｎ constitutes the nth series circuit. ｎ That is, the nth discharge circuit is an nth discharge circuit connected in parallel to the nth electronic switch D ｎ When the nth battery cell B ｎ The charge stored in the second resistor R2 ｎ and the third resistor R3 ｎ is used as a discharge resistor to forcibly discharge the

[0044] Also, the second resistor R2 ｎ＋１ , third resistor R3 ｎ＋１ and n+1 electronic switches D ｎ＋１constitutes the (n+1)th series circuit. The (n+1)th series circuit is ｎ＋１ That is, the n+1th discharge circuit is an n+1th electronic switch D ｎ＋１ When the n+1th battery cell B ｎ＋１ The charge stored in the second resistor R2 ｎ＋１ , third resistor R3 ｎ＋１ is used as a discharge resistor to forcibly discharge the

[0045] (n+1) differential amplifiers E １ ~E ｎ＋１ Among them, the n-th differential amplifier E ｎ has one input terminal connected to the second resistor R2 ｎ The other end of the nth electronic switch D ｎ One end of the second capacitor C2 ｎ and the other input terminal is connected to the third resistor R3 ｎ The other end of the nth electronic switch D ｎ the other end of the second capacitor C2 ｎ and the output terminal is connected to the other end of the n-th differential amplifier E ｎ is connected to the input terminal of

[0046] That is, the n-th differential amplifier E ｎ is the nth electronic switch D ｎ The n-th differential amplifier E amplifies the voltage between the terminals. ｎ The voltage between the terminals is used as the nth detection voltage, and the nth control circuit F ｎ Output to.

[0047] (n+1)th differential amplifier E ｎ＋１ has one input terminal connected to the second resistor R2 ｎ＋１ The other end of the n+1th electronic switch D ｎ＋１ One end of the second capacitor C2 ｎ＋１ and the other input terminal is connected to the third resistor R3 ｎ＋１ The other end of the n+1th electronic switch D ｎ＋１ the other end of the second capacitor C2 ｎ＋１ and the output terminal is connected to the other terminal of the (n+1)th differential amplifier E ｎ＋１ is connected to the input terminal of

[0048] (n+1)th differential amplifier E ｎ＋１ is the n+1th electronic switch D ｎ＋１ The n+1-th differential amplifier E amplifies the voltage between the terminals of ｎ＋１ The voltage between the terminals is used as the (n+1)th detection voltage and the (n+1)th control circuit F ｎ＋１ Output to.

[0049] (n+1) control circuits F １ ~F ｎ＋１ Among them, the nth control circuit F ｎ The input terminal of the n-th differential amplifier E ｎ The output terminal is connected to the output terminal of the n-th electronic switch D ｎ The n-th control circuit F ｎ is the n-th differential amplifier E ｎ The nth electronic switch D ｎ Controls the open / close state of the

[0050] n+1th control circuit F ｎ＋１ The input terminal is the (n+1)th differential amplifier E ｎ＋１ The output terminal is connected to the output terminal of the n+1th electronic switch D ｎ＋１ The n+1th control circuit F ｎ＋１ is the (n+1)th differential amplifier E ｎ＋１ The n+1th electronic switch D ｎ＋１ Controls the open / close state of the

[0051] Here, (n+1) differential amplifiers E １ ~E ｎ＋１ and (n+1) control circuits F １ ~F ｎ＋１ are the first to (n+1)th electronic switches D １ ~D ｎ＋１ The n-th electronic switch D ｎ The n-th differential amplifier E ｎ and n control circuit F ｎ is attached, and the n+1th electronic switch D ｎ＋１ The n+1th differential amplifier E ｎ＋１ and n+1 control circuit F ｎ＋１ is attached.

[0052] That is, the nth electronic switch D ｎ is the n-th differential amplifier E ｎ and n control circuit F ｎ The nth overcurrent protection function is provided based on the n+1th electronic switch D ｎ＋１ The n+1th differential amplifier E ｎ＋１ and n+1 control circuit F ｎ＋１ The n+1th overcurrent protection function based on the above formula is provided.

[0053] The n-th overcurrent protection function is the n-th electronic switch D ｎ When an overvoltage is applied between one end and the other end, i.e., between the terminals, the n-th electronic switch D ｎ The nth electronic switch D ｎ The (n+1)th overcurrent protection function inhibits the (n+1)th electronic switch D ｎ＋１ When an overvoltage is applied between one end and the other end of the n+1th electronic switch D ｎ＋１ The n+1th electronic switch D ｎ＋１ is prohibited from transitioning to the ON state.

[0054] (n+1) voltage amplifiers G １ ~G ｎ＋１ is the first to n+1th battery cells B １ ~B ｎ＋１ The first to (n+1)th cell voltages V1 to V ｎ＋１ The voltage amplifier G １ ~G ｎ＋１ Among them, the n-th voltage amplifier G ｎ One input terminal is connected to the first resistor R1 ｎ－１ the other end of the first capacitor C1 ｎ－１ The other input terminal is connected to one end of the first resistor R1 ｎ The other end of the first capacitor C1 ｎ and one end of the n+1 voltage amplifier G ｎ＋１ and its output terminal is connected to the n-th input terminal of the MPU 1.

[0055] nth voltage amplifier G ｎ is the (n-1)th wiring VHｎ－１ and the n-th battery cell B via the n-1CR low-pass filter ｎ The n-1th battery potential applied from the negative electrode of the ｎ and the nth battery cell B via the nth CR low-pass filter ｎ The difference between the n-th battery potential applied from the positive electrode and the n-th battery potential is amplified. ｎ is the nth battery cell B ｎ The inter-electrode voltage for the nth cell voltage V ｎ and outputs it to the n-th input terminal of the MPU 1.

[0056] (n+1)th voltage amplifier G ｎ＋１ One input terminal is connected to the first resistor R1 ｎ The other end of the first capacitor C1 ｎ and one end of the nth voltage amplifier G ｎ The other input terminal is connected to the first resistor R1 ｎ＋１ the other end of the first capacitor C1 ｎ＋１ , and the output terminal is connected to the (n+1)th input terminal of the MPU1.

[0057] (n+1)th voltage amplifier G ｎ＋１ is the nth wiring VH ｎ and the nth battery cell B via the nth CR low-pass filter ｎ and the positive electrode of the n+1 battery cell B ｎ＋１ The nth battery potential applied from the negative electrode of the ｎ＋１ and the n+1th battery cell B via the n+1th CR low-pass filter ｎ＋１ The difference between the potential of the n+1th battery and the potential of the n+1th battery applied from the positive electrode of the n+1th battery is amplified. ｎ＋１ is the n+1th battery cell B ｎ＋１ The inter-electrode voltage for the n+1 cell is V ｎ＋１ and outputs it to the (n+1)th input terminal of the MPU1.

[0058] The MPU 1 has at least (n+1) input terminals and (n+1) output terminals. Of the (n+1) input terminals, the nth input terminal is connected to the nth voltage amplifier G ｎ and the n+1th input terminal is connected to the output terminal of the n+1th voltage amplifier Gｎ＋１ The n-th output terminal is connected to the n-th electronic switch D ｎ and the n+1th output terminal is connected to the other input terminal of the n+1th electronic switch D ｎ＋１ is connected to the other input terminal of the

[0059] Such an MPU 1 includes a memory circuit that stores at least a predetermined monitoring program, an arithmetic circuit that executes the monitoring program, and (n+1) electronic switches D1 to D ｎ＋１ and (n+1) voltage amplifiers G １ ~G ｎ＋１ The MPU 1 executes the monitoring program in the memory circuit in the arithmetic circuit to control the first to (n+1)th electronic switches D １ ~D ｎ＋１ That is, the control unit controls the operation of the first to (n+1)th discharge circuits.

[0060] That is, the MPU 1 controls the first to (n+1)th voltage amplifiers G １ ~G ｎ＋１ The first to (n+1)th cell voltages V １ ~V ｎ＋１ The MPU 1 generates the first to (n+1)th switching signals based on the first to (n+1)th switching signals. １ ~D ｎ＋１ The first to (n+1)th electronic switches D １ ~D ｎ＋１ That is, it controls the operation of the first to (n+1)th discharge circuits.

[0061] Such a battery monitoring device A (disconnection detection device) detects the first to (n+1)th wirings VH １ ~VH ｎ＋１ and the first to (n+1)th electronic switches D in the first to (n+1)th discharge circuits. １ ~D ｎ＋１ are provided with first to (n+1)th overcurrent protection functions, respectively.

[0062] Next, the operation of the battery monitoring device A according to this embodiment will be described with reference to the flowchart shown in FIG.

[0063] In the following, adjacent battery cells B ｎ , B ｎ＋１ In this operation description, the disconnection detection for the n+1th battery cell B ｎ＋１ the own cell, the n+1th electronic switch D ｎ＋１ is called the own switch, and the nth battery cell B ｎ , the adjacent cell, the nth electronic switch D ｎ is called an adjacent switch.

[0064] First, the battery monitoring device A (disconnection detection device) according to this embodiment detects (n+1) battery cells B １ , ..., B ｎ , B ｎ＋１ In order to equalize the charge states of the battery cells, if a break occurs in the low-potential side wiring connected to a certain battery cell during equalization discharge of the battery cell, the capacitor of the CR low-pass filter provided in the low-potential side wiring is charged with a voltage approximately twice the normally applied voltage.

[0065] For example, as shown in FIG. 3, the (n+1)th electronic switch D ｎ＋１ (own switch) is set to ON state and the n+1th battery cell B ｎ＋１ In a state where the (own cell) is being equalized and discharged, the n-th wiring VH ｎ When the first capacitor C1 is broken, a current I shown by the broken line flows. ｎ The nth battery cell B ｎ Instead of the voltage of the positive terminal of the (adjacent cell), the n+1th battery cell B ｎ＋１ The voltage of the positive terminal of (own cell) is applied.

[0066] nth battery cell B ｎ (adjacent cell) and the n+1th battery cell B ｎ＋１ (own cell) is connected in series, and the nth battery cell B ｎ (adjacent cell) nth cell voltage V ｎ and the n+1th battery cell B ｎ＋１ (own cell) n+1th cell voltage V ｎ＋１ is almost the same, so the n+1th battery cell B ｎ＋１ The voltage at the positive terminal of the nth battery cell B ｎThis corresponds to approximately twice the voltage of the positive terminal of the adjacent cell. ｎ is charged by approximately twice this voltage, and the potential at one end is maintained at this approximately twice voltage.

[0067] As will be described in detail later, the MPU 1 of the battery monitoring device A includes first to (n+1)th voltage amplifiers G １ ~G ｎ＋１ The first to (n+1)th cell voltages V are calculated based on the first to (n+1)th differential voltages input from １ ~V ｎ＋１ and detects the first to (n+1)th cell voltages V １ ~V ｎ＋１ Using the first to (n+1)th wiring VH １ ~VH ｎ＋１ Detects broken wires.

[0068] However, the first capacitor C1 ｎ When the potential at one end of the n-th wiring VH ｎ When the line is broken, the nth and (n+1)th cell voltages V ｎ , V ｎ＋１ becomes an abnormal voltage value. That is, the nth cell voltage V ｎ is about twice the normal cell voltage. ｎ＋１ becomes a voltage value of approximately zero.

[0069] In this way, the nth wiring VH ｎ When the line is broken, the nth and (n+1)th cell voltages V ｎ , V ｎ＋１ becomes an abnormal voltage value, but the nth and (n+1)th cell voltages V ｎ , V ｎ＋１ The abnormal voltage value on the nth wiring VH ｎ Not only the disconnection of the nth battery cell B ｎ (adjacent cell) or the n+1th battery cell B ｎ＋１ This also occurs when an abnormality occurs in the nth wiring VH ｎ The break in the nth battery cell B ｎ (adjacent cell) or the n+1th battery cell B ｎ＋１ In order to distinguish and detect an abnormality in the nth battery cell B ｎ (adjacent cell) and n+1 battery cell Bｎ＋１ (own cell) nth and (n+1)th cell voltage V ｎ , V ｎ＋１ It is also necessary to evaluate the change trends of the differential voltage Vdiff and the sum voltage Vsum.

[0070] The MPU 1 detects the nth and (n+1)th cell voltages V ｎ , V ｎ＋１ When an abnormality is detected, the nth electronic switch D ｎ By setting the (own switch) to the ON state, the first capacitor C1 ｎ That is, the n+1th battery cell B ｎ＋１ During equalization discharge of the (own cell), the nth and (n+1)th cell voltages V ｎ , V ｎ＋１ Since the first capacitor C1 is abnormal, ｎ is discharged (neutralized), and then the nth and (n+1)th cell voltages V ｎ , V ｎ＋１ Redetect.

[0071] The MPU 1 has such a first capacitor C1 ｎ When neutralizing the n-th cell, it is determined whether or not the neutralization switch has been switched (step S1). ｎ exceeds a predetermined threshold, it is determined that "the static elimination switch has been switched on" and the n-th cell voltage V ｎ If the difference is equal to or less than the predetermined threshold value, it is determined that "no determination is required for switching the static elimination switch."

[0072] That is, the MPU 1 detects the n-th cell voltage V ｎ exceeds a predetermined threshold value, the n-th electronic switch D ｎ It is determined that the n-th overcurrent protection function of the (adjacent switch) is activated, and the n-th cell voltage V ｎ If the n-th electronic switch D ｎ If the determination in step S1 is "No," that is, if the n-th electronic switch D ｎ If it is determined that the n-th overcurrent protection function of the (adjacent switch) does not operate, the n-th electronic switch D ｎ (adjacent switch) is set as the charge removal switch (step S2).

[0073] On the other hand, if the determination in step S1 is "Yes", that is, if the n-th electronic switch D ｎ When it is determined that the n-th overcurrent protection function is activated, the n+1-th electronic switch D ｎ＋１ Then, the MPU 1 activates the static elimination switch (sets it to the ON state) to charge the first capacitor C1 ｎ Then, static elimination is carried out (step S4).

[0074] n-th electronic switch D ｎ When the adjacent switch is set as the static elimination switch, the first capacitor C1 ｎ The charge stored in the first resistor R1 ｎ →Second resistor R1 ｎ →nth electronic switch D ｎ (Adjacent switch) → Third resistor R3 ｎ →First resistor R1 ｎ－１ →First capacitor C1 ｎ－１ The static electricity is removed via

[0075] n+1th electronic switch D ｎ＋１ When the switch (own switch) is set as the static elimination switch, the first capacitor C1 ｎ The charge stored in the first resistor R1 ｎ →Third resistor R3 ｎ＋１ →n+1th electronic switch D ｎ＋１ (Own switch) → First resistor R3 ｎ＋１ →First resistor R1 ｎ＋１ →First capacitor C1 ｎ＋１ The static electricity is removed via

[0076] That is, the discharge switch is switched over in a time series manner depending on the operating state of the n-th overcurrent protection function, as shown in Fig. 4. Therefore, a situation will not occur in which the charge accumulated in the first capacitor C1n cannot be discharged due to the discharge switch being fixed.

[0077] In this way, the first capacitor C1 ｎ When the neutralization of the nth battery cell B is completed, the MPU 1 ｎ (adjacent cell) and n+1 battery cell Bｎ＋１ (own cell) nth and (n+1)th cell voltage V ｎ , V ｎ＋１ Then, the MPU 1 acquires the (n+1)th battery cell B ｎ＋１ (own cell) n+1th cell voltage V ｎ＋１ It is determined whether or not the voltage exceeds the voltage threshold Vth (step S6).

[0078] If the determination in step S6 is "Yes," the MPU 1 switches the static elimination switch (step S7). That is, if the n-th electronic switch Dn (adjacent switch) was set as the static elimination switch in step S2, the MPU 1 changes the static elimination switch to the (n+1)-th electronic switch Dn+1 (own switch).

[0079] On the other hand, if the MPU 1 sets the (n+1)th electronic switch Dn+1 (its own switch) as the static elimination switch in step S3, it changes the static elimination switch to the nth electronic switch Dn (adjacent switch). After switching the static elimination switch in this way, the MPU 1 performs a wire break determination (step S8) and ends the wire break evaluation process.

[0080] The above-mentioned disconnection determination is performed by determining whether the n-th battery cell B ｎ (adjacent cell) and n+1 battery cell B ｎ＋１ (own cell) nth and (n+1)th cell voltage V ｎ , V ｎ＋１ , nth cell voltage V ｎ and the n+1 cell voltage V ｎ＋１ The difference voltage Vdiff between the nth cell and the nth cell voltage V ｎ and the n+1 cell voltage V ｎ＋１ This utilizes the tendency of change in the sum voltage Vsum.

[0081] By turning on / off either the nth discharge circuit or the (n+1)th discharge circuit, for example, the nth discharge circuit, at a predetermined duty ratio, the nth battery cell B ｎ When the n+1 cell voltage V ｎ＋１ is the nth wiring VH ｎ Even if a disconnection occurs, the nth cell voltage V ｎ is the nth wiring VH ｎThe voltage gradually decreases due to a break in the wire.

[0082] In this case, the differential voltage Vdiff gradually increases due to the disconnection of the n-th wiring VHn. ｎ That is, the n-th wiring VH ｎ When a break occurs, the change tendency (gradient) of the differential voltage Vdiff and the sum voltage Vsum is completely different.

[0083] On the other hand, the nth battery cell B is discharged by turning the nth discharge circuit ON / OFF at a predetermined duty ratio. ｎ When the nth battery cell B is gradually discharged, ｎ When a voltage abnormality (battery abnormality) occurs in the n-th cell (adjacent cell), the n-th cell voltage V ｎ and the n+1 cell voltage V ｎ＋１ Both of these gradually decrease.

[0084] The differential voltage Vdiff is the voltage difference between the nth battery cell B ｎ When a voltage abnormality (battery abnormality) occurs in the nth battery cell B (adjacent cell), the sum voltage Vsum gradually increases. ｎ When a voltage abnormality (battery abnormality) occurs in the nth battery cell B ｎ When a voltage abnormality (battery abnormality) occurs in the adjacent cell, the differential voltage Vdiff and the sum voltage Vsum have different directions of change tendency (gradient) but have the same absolute value.

[0085] The MPU 1 detects the nth and (n+1)th cell voltages V ｎ , V ｎ＋１ , by utilizing the properties of the difference voltage Vdiff between the n-th cell voltage Vn and the (n+1)-th cell voltage Vn+1 and the sum voltage Vsum of the n-th cell voltage Vn and the (n+1)-th cell voltage Vn+1, ｎ The break in the nth battery cell B ｎ This is detected separately from voltage abnormalities (battery abnormalities) in the adjacent cells.

[0086] If the determination in step S6 is "No", the MPU 1 ｎ (adjacent cell) nth cell voltage V ｎexceeds the voltage threshold Vth (step S9). If the determination in step S9 is "Yes", the MPU 1 performs a wire break determination (step S10), and if the determination in step S9 is "No", the MPU 1 does not determine a wire break (step S11) and ends the wire break evaluation process.

[0087] According to this embodiment, the discharge switch (electronic switch) that discharges the capacitor of the CR low-pass filter that is charged with double the voltage can be changed without being fixed, so even if each wiring is equipped with a CR low-pass filter and the electronic switch of the discharge circuit has an overcurrent protection function, it is possible to correctly detect a broken wiring based on the cell voltage.

[0088] That is, according to this embodiment, the overcurrent protection function is activated by the double voltage applied to the capacitor of the CR low-pass filter, and the discharge switch (electronic switch) of the discharge circuit connected to the capacitor cannot be switched ON, preventing the charge in the capacitor from being discharged. As a result, according to this embodiment, it is possible to provide a battery monitoring device A (disconnection detection device) that can avoid a situation in which disconnection detection becomes impossible due to the capacitor being maintained in a charged state.

[0089] The present invention is not limited to the above embodiment, and the following modifications are possible: (1) In the above embodiment, the nth and (n+1)th adjacent cell voltages V ｎ , V ｎ＋１ , the nth wiring VH ｎ However, the present invention is not limited to this.

[0090] For example, as described in Japanese Patent Application Laid-Open No. 2017-158269, when a pair of adjacent battery cells are discharged at different duty ratios, the differential voltage Vdiff and sum voltage Vsum may be used to distinguish between a break in the transmission line and a voltage abnormality in the battery cell (battery abnormality).

[0091] (2) In the above embodiment, the detection of a disconnection in the battery B (battery pack) mounted on an electric vehicle has been described, but the present invention is not limited to this. The present invention can also be applied to batteries other than the vehicle-mounted battery B (battery pack).

[0092] The present disclosure can be used in a disconnection detection device and a battery monitoring device.

[0093] A Battery monitoring device B Battery B ｎ , B ｎ＋１ Battery cell C1 ｎ－１ , C1 ｎ , C1 ｎ＋１ First capacitor C2 ｎ , C2 ｎ＋１ Second capacitor D ｎ , D ｎ＋１ Electronic switch E ｎ , E ｎ＋１ Differential amplifier F ｎ , F ｎ＋１ Control circuit G ｎ , G ｎ＋１ Voltage amplifier R1 ｎ－１ , R1 ｎ , R1 ｎ＋１ First resistor R2 ｎ , R2 ｎ＋１ 1st resistor R3 ｎ , R3 ｎ＋１ 1st resistor T ｎ－１ , T ｎ , T ｎ＋１ Input terminal 1 MPU

Claims

1. A disconnection detection device for a battery having a plurality of battery cells connected in series with each other and each having a discharge circuit, each having an electronic switch, connected in parallel, the device comprising: a voltage detection circuit for detecting cell voltages of the battery cells; CR low-pass filters provided on a plurality of wiring lines connecting the battery cells and the voltage detection circuit; and a control unit for equalizing discharge of the discharge circuits and detecting disconnection of the wiring lines based on the cell voltages, The electronic switch has a protection function for prohibiting a transition to an ON state, The control unit is a disconnection detection device that eliminates the charge accumulated in the CR low-pass filter by operating one of a pair of electronic switches associated with an adjacent pair of battery cells, and detects a disconnection in the wiring based on the cell voltage after the charge is eliminated.

2. 2. The disconnection detection device according to claim 1, wherein, when the control unit determines that the protection function of the electronic switch that is preset as a discharge switch for the CR low-pass filter is activated, the control unit discharges the CR low-pass filter by setting to an ON state the electronic switch that is paired with the electronic switch whose protection function has been activated.

3. 3. The disconnection detection device according to claim 1, wherein the control unit distinguishes between a disconnection in the wiring and an abnormality in the battery cell based on a differential voltage and a sum voltage of cell voltages of a pair of the battery cells when at least one of the discharge circuits is discharged.

4. 3. The disconnection detection device according to claim 1, wherein the discharge circuit is a series circuit of the electronic switch and a resistor.

5. A wire breakage detection device according to claim 1 or 2 is provided, A battery monitoring device that controls connection of the battery to a load based on a result of the disconnection detection by the disconnection detection device.