Voltage detection device and battery monitoring apparatus

Abstract

To detect an open fault in a branch connection line in a short period of time.SOLUTION: There is provided a voltage detection device in which electrode voltages of n battery cells are input to n+1 actual input terminals via connection lines, and an unused input terminal which is not connected to the connection line is connected to a branch connection line. The voltage detection device comprises: a discharge circuit that individually discharges the battery cells; noise removal filters connected to the respective input terminals; a first voltage detection unit that detects first electrode voltages by acquiring electrode voltages input to the input terminals via the noise removal filters; a second voltage detection unit that detects second electrode voltages by acquiring the electrode voltages input to the input terminals without passing through the noise removal filters; a cell voltage calculation unit that calculates the inter-electrode voltage of the battery cell as a cell voltage on the basis of the first electrode voltages associated with the actual input terminals; and a branch line diagnosis unit that diagnoses an open fault in a branch connection line on the basis of the first electrode voltage and the second electrode voltage when every other battery cell is forcibly discharged.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a voltage detection device and a battery monitoring device. [Background technology]

[0002] The following Patent Document 1 discloses an integrated circuit and a battery monitoring device that can suppress an increase in manufacturing costs. This integrated circuit and battery monitoring device performs dead pin processing for a free input terminal of a battery monitoring IC by connecting the free input terminal to a ground terminal via a resistive element. With such an integrated circuit and battery monitoring device, even if a free input terminal occurs in the battery monitoring IC, it is not necessary to provide an element or wiring pattern on the board to connect to the free terminal, so that an increase in manufacturing costs can be suppressed.

[0003] Furthermore, the following Patent Document 2 discloses a battery monitoring device that can reduce power loss by shortening the switch short-circuit time required to perform a disconnection diagnosis of a voltage detection line. This battery monitoring device detects voltage and disconnection after a waiting time following a balancing process. The disconnection detection in Patent Document 2 utilizes the fact that the voltage between the adjustment lines when the balancing switch is on is different between when the voltage detection line is normal and when it is disconnected, and measures the voltage between a pair of adjustment lines when the balancing switch is on as a disconnection diagnosis voltage, and performs a disconnection diagnosis of the voltage detection line based on the measured voltage value to determine whether the voltage detection line is disconnected. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7152933 [Patent Document 2] Patent No. 6192588 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, as another method of processing dead pins of an input terminal as described in Patent Document 1, there is a method of inputting the same cell voltage as the cell voltage input to the adjacent input terminal to the empty input terminal by branching the input connection line of the adjacent cell voltage. However, this method of processing dead pins has a problem that if an open fault such as a break occurs in the branch connection line that branches off from the input connection line and connects to the empty input terminal, the dead pin processing of the input terminal becomes insufficient, which may cause an obstacle to the detection of the cell voltage.

[0006] In addition, the disconnection detection in Patent Document 2 involves performing a balancing process by setting a balancing switch to an on state, and detecting a disconnection based on the voltage after a predetermined waiting time has elapsed since the balancing process. Therefore, this type of disconnection detection method has the problem that it takes a relatively long time to detect a disconnection.

[0007] The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide a voltage detection device and a battery monitoring device that are capable of detecting an open fault in a branch connection line in a shorter time than conventional devices. [Means for solving the problem]

[0008] In order to achieve the above object, the present invention provides a voltage detection device as a solution relating to a voltage detection device, which takes in the electrode voltages of n (n: natural number) battery cells connected in series to n+1 real input terminals out of m (m>n+2 natural number) input terminals via n+1 connection lines, and connects a vacant input terminal to which no connection line is connected to a branch connection line branching off from the connection lines, and includes at least n discharge circuits that individually discharge the n battery cells, m noise reduction filters connected to the m input terminals, and the electrode voltages input to the m input terminals are taken in through the noise reduction filters. a first voltage detection unit that detects each of the n+1 first electrode voltages by taking in the electrode voltages input to the m input terminals without passing through the noise removal filter; a second voltage detection unit that detects each of the n+1 second electrode voltages by taking in the electrode voltages input to the m input terminals without passing through the noise removal filter; a cell voltage calculation unit that calculates inter-electrode voltages of the n battery cells as cell voltages based on the first electrode voltages related to the actual input terminals; and a branch line diagnosis unit that diagnoses an open fault in the branch connection line based on the first electrode voltages and the second electrode voltages when every other one of the n battery cells is forcibly discharged by the discharge circuit. Effect of the Invention

[0009] According to the present invention, it is possible to provide a voltage detection device and a battery monitoring device that are capable of detecting an open fault in a branch connection line in a shorter time than conventional devices. [Brief description of the drawings]

[0010] [Figure 1] 1 is a block diagram showing a functional configuration of a battery management device A according to an embodiment of the present invention. [Diagram 2] 1 is a block diagram showing a functional configuration of a voltage detection device according to an embodiment of the present invention; [Diagram 3] FIG. 4 is a block diagram showing a current path during disconnection diagnosis in one embodiment of the present invention. [Figure 4] FIG. 4 is a characteristic diagram showing a first inter-electrode voltage and a second inter-electrode voltage in one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The battery monitoring device A of this embodiment is installed in an electric vehicle, such as an electric car or a hybrid car, which runs by driving a motor with battery power, and manages a battery B that constitutes the vehicle running power system shown in Figure 1.

[0012] As shown in the figure, the vehicle running power system includes, in addition to a battery B, contactors 1 and 2, a current sensor 3, a voltage detection unit 4, a battery ECU 5, and a load 6. Of these components, the current sensor 3, the voltage detection IC 4, and the battery ECU 5 constitute a battery monitoring device A according to this embodiment.

[0013] Battery B is an assembled battery consisting of n (n = natural number) battery cells b1 to bn connected in series. The positive terminal of battery B is the positive terminal of battery cell bn located at the top of the series connection. The negative terminal of battery B is the negative terminal of battery cell b1 located at the bottom of the series connection.

[0014] The contactor 1 has a pair of contacts whose connection relationship is turned on / off, one of which is connected to the positive terminal of the battery B and the other of which is connected to a first input terminal of the load 6. The ON / OFF state of the pair of contacts of the contactor 1 is controlled by the battery ECU 5, thereby switching between connection / disconnection between the positive terminal of the battery B and the first input terminal of the load 6.

[0015] The contactor 2 has a pair of contacts whose connection relationship is turned ON / OFF, one of which is connected to the negative terminal of the battery B and the other of which is connected to the second input terminal of the load 6. The ON / OFF state of the pair of contacts of the contactor 2 is controlled by the battery ECU 5, thereby switching between connection / disconnection between the negative terminal of the battery B and the second input terminal of the load 6.

[0016] The current sensor 3 is a galvanometer that detects a battery current supplied from the battery B to the load 6. The current sensor 3 outputs the battery current to the battery ECU 5.

[0017] As shown in the figure, the voltage detection IC4 has m (m>n+2, a natural number) input terminals IN1-INm. That is, the voltage detection IC4 has input terminals whose number is three or more greater than the number n of the battery cells b1-bn in the battery B. The electrodes of each of the battery cells b1-bn are connected to one of the m input terminals IN1-INm by n+1 connection lines L1-Ln+1 as shown in the figure. The input terminals of the voltage detection IC4 to which the connection lines L1-Ln+1 are connected are actual input terminals in this embodiment.

[0018] In the voltage detection IC4, since the number m of input terminals IN1 to INm is greater than the number n of battery cells b1 to bn, there are input terminals to which connection lines L1 to Ln+1 are not connected. Such input terminals to which connection lines L1 to Ln+1 are not connected are vacant input terminals in this embodiment. Although details will be described later, the vacant input terminals are connected to branch connection lines branching off from adjacent connection lines.

[0019] That is, the battery monitoring device A of this embodiment receives n+1 electrode voltages V1 to Vn+1 of n battery cells b1 to bn connected in series via n+1 connection lines L1 to Ln+1 to n+1 actual input terminals among m input terminals IN1 to INm, and connects the empty input terminals to which the connection lines L1 to Ln+1 are not connected to a branch connection line branching off from an adjacent connection line.

[0020] The voltage detection IC4 sequentially detects the inter-electrode voltages of each of the battery cells b1-bn as cell voltages based on the n+1 electrode voltages V1-Vn+1, and sequentially detects the battery voltage, which is the sum of the cell voltages. The voltage detection IC4 sequentially outputs the cell voltages of each of the battery cells b1-bn and the battery voltage to the battery ECU 5. Such a voltage detection IC4 is the voltage detection device according to this embodiment.

[0021] The battery ECU 5 controls the operation of the contactors 1 and 2 described above based on an operational instruction from the vehicle driver (for example, turning the ignition switch "ON"), thereby controlling the supply of the output of the battery B (battery power) to the load 6.

[0022] The battery ECU 5 also monitors the state of the battery B by sequentially capturing the battery current input from the current sensor 3 and the cell voltages and battery voltage input from the voltage detection unit 4 at a predetermined time interval. When the battery ECU 5 detects an abnormality in the battery B based on the battery current, the cell voltages, and the battery voltage, it stops the power supply from the battery B to the load 6 by setting the contactors 1 and 2 to the OFF state.

[0023] The load 6 is an inverter and a driving motor. This load 6 generates driving power by converting battery power (DC power) input from battery B via contactors 1 and 2 into AC power using an inverter and supplying it to the driving motor. In other words, the load 6 is a power generator that generates driving power from battery power.

[0024] Next, the voltage detection IC4 in the battery monitoring device A, that is, the voltage detection device according to this embodiment, will be described in detail with reference to Fig. 2. For convenience, Fig. 2 shows a detailed configuration corresponding to a portion of the n battery cells b1 to bn, that is, three battery cells b13 to b15 adjacent to each other in a series connection. Fig. 2 also shows a state in which the electrodes of the three battery cells b13 to b15 are connected to four input terminals IN14 to IN16, IN19 (actual input terminals) via four connection lines L13 to L16.

[0025] Furthermore, in Figure 2, of the two input terminals IN17, IN18 (empty input terminals) to which the four connection lines L13 to L16 are not connected, the input terminal IN17 adjacent to the input terminal IN16 is connected to the positive electrode of the battery cell b14 by a branch connection line L15a branching off from the connection line L15, and the input terminal IN18 adjacent to the input terminal IN17 is connected to the positive electrode of the battery cell b14 by a branch connection line L15b also branching off from the connection line L15.

[0026] As shown in FIG. 2, the voltage detection IC 4 includes a plurality of discharge circuits 4a corresponding to the three battery cells b13 to b15, a plurality of voltage dividing capacitors 4b, a plurality of noise removal filters 4c, a plurality of first voltage detection units 4d, a plurality of second voltage detection units 4e, and a calculation unit 4f.

[0027] Each of the multiple discharge circuits 4a is a series circuit (two-terminal circuit) of a discharge resistor and an open / close switch. Each discharge circuit 4a is connected between two adjacent input terminals among the six input terminals IN14 to IN19. That is, the discharge circuits 4a are provided between the input terminals IN14 and IN15, between the input terminals IN15 and IN16, between the input terminals IN16 and IN17, between the input terminals IN17 and IN18, and between the input terminals IN18 and IN19.

[0028] Such multiple discharge circuits 4a forcibly discharge the three battery cells b13 to b15 individually. That is, the discharge circuit 4a provided between the input terminals IN14 and IN15 forcibly discharges the battery cell b13 via the discharge resistor and the open / close switch when the open / close switch is set to the closed state.

[0029] In addition, the discharge circuit 4a provided between the input terminals IN15 and IN16 forcibly discharges the battery cell b14 via a discharge resistor and an on-off switch when the on-off switch is set to the closed state. The discharge circuit 4a provided between the input terminals IN18 and IN19 forcibly discharges the battery cell b15 via a discharge resistor and an on-off switch when the on-off switch is set to the closed state.

[0030] 2, discharge circuits 4a are also provided between input terminals IN16 and IN17 and between input terminals IN17 and IN18, but these two discharge circuits 4a may be omitted because they are not involved in the forced discharge of battery cell b14. In other words, it is sufficient that the number of discharge circuits 4a provided is at least the same as the number of battery cells.

[0031] The voltage dividing capacitors 4b are two-terminal elements having a predetermined capacitance. Like the discharge circuits 4a described above, each voltage dividing capacitor 4b is connected between two adjacent input terminals among the six input terminals IN14 to IN19. That is, the voltage dividing capacitors 4b are provided between the input terminals IN14 and IN15, between the input terminals IN15 and IN16, between the input terminals IN16 and IN17, between the input terminals IN17 and IN18, and between the input terminals IN18 and IN19.

[0032] The plurality of noise elimination filters 4c are low-pass filters whose input terminals are connected to any one of the six input terminals IN14 to IN19 and whose output terminals are connected to any one of the plurality of first voltage detection units 4d. That is, the noise elimination filters 4c are provided between the six input terminals IN14 to IN19 and the plurality of first voltage detection units 4d, respectively.

[0033] The input terminals of the first voltage detection units 4d are connected to one of the noise removal filters 4c, and the output terminals of the first voltage detection units 4d are connected to one of the input terminals provided in the calculation unit 4f. That is, the first voltage detection units 4d are provided between the noise removal filters 4c and the input terminals in the calculation unit 4f.

[0034] The plurality of first voltage detection units 4d detect six first electrode voltages C14-C19 by receiving six electrode voltages V13-V16 input to six input terminals IN14-IN19 via a noise removal filter 4c. The plurality of first voltage detection units 4d output the six first electrode voltages C14-C19 to a calculation unit 4f.

[0035] The second voltage detection units 4e each have an input terminal connected to one of the six input terminals IN14-IN19, and an output terminal connected to one of the input terminals provided in the calculation unit 4f. That is, the second voltage detection units 4e are each provided between the six input terminals IN14-IN19 and the input terminals in the calculation unit 4f.

[0036] The plurality of second voltage detection units 4e detect six second electrode voltages CB14-CB19 by receiving six electrode voltages V13-V16 input to six input terminals IN14-IN19, respectively, without passing through the noise removal filter 4c. The plurality of second voltage detection units 4e output these six second electrode voltages CB14-CB19 to the calculation unit 4f.

[0037] Here, the second electrode voltages CB14-CB19 are not passed through the noise elimination filter 4c (low-pass filter), and therefore are voltages with better response than the first electrode voltages C14-C19. That is, the noise elimination filter 4c has a predetermined time constant, and therefore a predetermined delay time occurs between the input / output voltage and the output voltage. The second electrode voltages CB14-CB19 are not affected by such delay time, and therefore are better responsive than the first electrode voltages C14-C19.

[0038] The calculation unit 4f calculates inter-electrode voltages of the three battery cells b13-b15 as cell voltages E13-E15 based on the first electrode voltages C14-C19 input from the multiple first voltage detection units 4d. The calculation unit 4f also diagnoses an open fault (disconnection) in the branch connection lines L15a, L15b based on the first electrode voltages C14-C19 input from the multiple first voltage detection units 4d and the second electrode voltages CB14-CB19 input from the second voltage detection unit 4e. The calculation unit 4f functions as a cell voltage calculation unit and a branch line diagnosis unit in this embodiment.

[0039] Next, the operation of the battery monitoring device A according to this embodiment, in particular the operation of diagnosing an open fault in the branch connection lines L15a, L15b, will be described in detail with reference to FIGS.

[0040] First, the calculation unit 4f obtains the cell voltage E13 of the battery cell b13 by calculating the difference voltage between the first electrode voltage C15 and the first electrode voltage C14. The calculation unit 4f also obtains the cell voltage E14 of the battery cell b14 by calculating the difference voltage between the first electrode voltage C16 and the first electrode voltage C15. Furthermore, the calculation unit 4f obtains the cell voltage E15 of the battery cell b15 by calculating the difference voltage between the first electrode voltage C19 and the first electrode voltage C18. Such cell voltages E13 to E15 can be obtained regardless of the presence or absence of breaks in the two branch connection lines L15a and L15b.

[0041] Here, of the two branch connection lines L15a, L15b, one of the branch connection lines L15a connected to the input terminal IN17 is supplied with the same electrode voltage V15 as the two input terminals IN16, IN18 adjacent to the input terminal IN17 from the positive electrode of the battery cell b14 (the negative electrode of the battery cell b15), and therefore a break in the line cannot be detected by the method of Patent Document 2 described above.

[0042] In contrast, the other branch connection line L15b connected to the input terminal IN18 has the electrode voltage V15 applied to it from the branch connection line L15a connected to the adjacent input terminal IN17, while the electrode voltage V16 is supplied to the other adjacent input terminal IN19 from the positive electrode of the battery cell b15, so that the break can be detected by using the method of Patent Document 2.

[0043] As part of the diagnosis of the branch connection line L15a, the calculation unit 4f operates the discharge circuits 4a of the battery cells corresponding to the odd-numbered or even-numbered stages of the series connection among the n battery cells b1-bn. That is, by turning on the open / close switches of the discharge circuits 4a connected in parallel to every other battery cell among the n battery cells b1-bn connected in series, the battery cells are forcibly discharged via the discharge resistors.

[0044] 3 shows an example of a discharge current when a discharge circuit 4a connected in parallel to a battery cell b14 corresponding to an even-numbered stage in a series connection is operated. In this case, the discharge current flows from the positive electrode to the negative electrode of the battery cell b14 through a current path via the discharge circuit 4a, as shown by the dashed arrow in FIG. 3.

[0045] In this case, the second inter-electrode voltages DB1 to DB4 based on the second electrode voltages CB14 to C19 based on the first electrode voltages C14 to C19 have values ​​as shown in FIG. 4 when the branch connection line L15a is and is not disconnected, and when the discharge circuit 4a connected in parallel to the battery cell b14 is turned ON / OFF.

[0046] That is, when the branch connection line L15a is not broken, the second inter-electrode voltage DB2 is about 0V (volts), and the second inter-electrode voltage DB3 is half the voltage of E14. In contrast, when the branch connection line L15a is broken, the second inter-electrode voltages DB2 and DB3 are both 1 / 4 the voltage of E14. The second inter-electrode voltages DB2 and DB3 show clearly different voltage values ​​when the branch connection line L15a is not broken and when it is broken.

[0047] The calculation unit 4f detects whether or not the branch connection line L15a is broken by utilizing the characteristics of the first inter-electrode voltage D1 when the discharge circuit 4a is set to the OFF state and the second inter-electrode voltages DB2, DB3 when the discharge circuit 4a is set to the ON state.

[0048] [Detection condition R1] DB3>D1 / 3 (1) D1-DB2>D1 / 3 (2) [Detection condition R2] DB3≦D1 / 3 (3) D1-DB2≦D1 / 3 (4)

[0049] That is, the calculation unit 4f determines that the branch connection line L15a is not broken when both formulas (1) and (2) are satisfied. On the other hand, the calculation unit 4f determines that the branch connection line L15a is broken when both formulas (3) and (4) are satisfied.

[0050] According to this embodiment, the presence or absence of a break in the branch connection line L15a is detected not only based on the first electrode voltages C14 to C19 obtained via the noise removal filter 4c, but also based on the second electrode voltages CB14 to CB19 obtained without passing through the noise removal filter 4c, so it is possible to provide a voltage detection IC4 (voltage detection device) and a battery monitoring device A that can detect an open fault (break) in the branch connection line L15a in a shorter time than conventional methods.

[0051] Furthermore, according to this embodiment, the presence or absence of a break in the branch connection line L15a is detected based on the first electrode voltages C14 to C19 and the second electrode voltages CB14 to CB19 obtained without performing balancing processing on the n battery cells b1 to bn. This also makes it possible to detect an open fault (break) in the branch connection line L15a in a shorter time than in the past.

[0052] The present invention is not limited to the above embodiment, and the following modifications are possible. For example, in the above embodiment, the disconnection detection of the branch connection line L15a is described as an example, but the present invention is not limited to this.

[0053] [Appendix 1] A voltage detection device which receives electrode voltages of n battery cells (n: natural number) connected in series via n+1 connection lines into n+1 real input terminals among m input terminals (m>n+2, a natural number), and which has no input terminals to which the connection lines are not connected, connected to branch connection lines branching off from the connection lines, At least n discharge circuits for individually discharging the n battery cells; m noise reduction filters respectively connected to the m input terminals; a first voltage detection unit that detects n+1 first electrode voltages by receiving the electrode voltages input to the m input terminals via the noise removal filter; a second voltage detection unit that detects n+1 second electrode voltages by receiving the electrode voltages input to the m input terminals without passing through the noise removal filter; a cell voltage calculation unit that calculates inter-electrode voltages of the n battery cells as cell voltages based on the first electrode voltages related to the actual input terminals; a branch line diagnosis unit that diagnoses an open circuit fault in the branch connection line based on the first electrode voltage and the second electrode voltage when the n battery cells are forcibly discharged every other one by the discharge circuit; A voltage detection device comprising:

[0054] [Appendix 2] The voltage detection device described in Appendix 1, wherein the branch line diagnosis unit diagnoses an open circuit fault in the branch connection line using the first electrode voltage before balancing of the n battery cells.

[0055] [Appendix 3] The voltage detection device described in Appendix 1, wherein the branch line diagnosis unit diagnoses an open circuit fault in the branch connection line using the second electrode voltage before balancing of the n battery cells.

[0056] [Appendix 4] A battery monitoring device comprising the voltage detection device according to any one of claims 1 to 3. [Explanation of symbols]

[0057] A Battery monitoring device B Battery 1, 2 Contactor 3 Current Sensor 4 Voltage detection section 4a discharge circuit 4b Voltage divider capacitor 4c Noise Reduction Filter 4d First voltage detection section 4e Second voltage detection section 4f Calculation section 5 Battery ECU

Claims

1. a voltage detection device which receives electrode voltages of n battery cells (n: natural number) connected in series via n+1 connection lines into n+1 real input terminals among m input terminals (m>n+2, a natural number), and which has no input terminals to which the connection lines are not connected, connected to branch connection lines branching off from the connection lines; At least n discharge circuits for individually discharging the n battery cells; m noise removal filters respectively connected to the m input terminals; a first voltage detection unit that detects n+1 first electrode voltages by receiving the electrode voltages input to the m input terminals via the noise removal filter; a second voltage detection unit that detects n+1 second electrode voltages by receiving the electrode voltages input to the m input terminals without passing through the noise removal filter; a cell voltage calculation unit that calculates inter-electrode voltages of the n battery cells as cell voltages based on the first electrode voltages related to the actual input terminals; a branch line diagnosis unit that diagnoses an open circuit fault in the branch connection line based on the first electrode voltage and the second electrode voltage when the n battery cells are forcibly discharged every other one by the discharge circuit; A voltage detection device comprising:

2. 2 . The voltage detection device according to claim 1 , wherein the branch line diagnosis unit diagnoses an open circuit fault in the branch connection line by using the first electrode voltage before a balancing process is performed on the n battery cells.

3. 2 . The voltage detection device according to claim 1 , wherein the branch line diagnosis unit diagnoses an open circuit fault in the branch connection line by using the second electrode voltage before balancing of the n battery cells.

4. A battery monitoring device comprising the voltage detection device according to any one of claims 1 to 3.

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