JP5520580B2 - Storage battery cell short-circuit detection method and detection device - Google Patents

Description

  The present invention relates to a storage battery cell short-circuit detection method and a detection device for detecting a short circuit occurring in a storage battery cell configured by combining a plurality of cells.

  Storage batteries used in automobiles, storage batteries used for power leveling and storage in combination with power generation using natural energy such as solar power generation and wind power generation, storage batteries as backup power sources during power outages, etc. In order to obtain a voltage, it is configured by combining a plurality of cells. For example, a lead storage battery mounted on an automobile has a voltage of about 2 V per cell, and six of them are connected in series to have a voltage of about 12 V. Getting voltage. An example of a lead storage battery is shown in FIG. 12A is an external view of the lead storage battery 900, and FIG. 12B is a schematic configuration diagram of a cell 901 built in the lead storage battery 900. One cell 901 has a voltage of about 2 V, and the voltage of the lead storage battery 900 is set to about 12 V by connecting six cells in series.

  The cell 901 is configured by alternately combining a plurality of negative electrodes 902 made of a negative electrode active material and a plurality of positive electrodes 903 made of a positive electrode active material, and a separator 904 is disposed between the negative electrode 902 and the positive electrode 903. Yes. In addition, a plurality of negative electrodes 902 are electrically connected to provide a negative electrode terminal 905, and a plurality of positive electrodes 903 are electrically connected to provide a positive electrode terminal 906. A plurality of negative electrodes 902 and positive electrodes 903 having such a structure are immersed in the electrolytic solution 908 in the cell container 907 and stored.

  As described above, in a storage battery configured by combining a plurality of cells, various changes occur in each cell by repeating charge and discharge, and as a result, a short circuit may occur between the cells. Hereinafter, various changes occurring in the cell will be described with reference to FIG. Here, in the cell 901 shown in FIG. 12B, one negative electrode 902, one positive electrode 903, and a separator 904 disposed therebetween are schematically shown.

  FIG. 13A shows a state in which no change has occurred in the cell 901 before the storage battery 900 is used, for example. When the use of the storage battery 900 is started and charging / discharging is repeated, as shown in FIG. 13B, the electrode plate of the negative electrode 902 expands and comes into contact with the separator 904, or a part of the electrode plate peels off, and the lower part of the electrode plate. Will begin to settle. When charging and discharging are further repeated, as shown in FIG. 13C, the expansion of the electrode plate not only compresses and deforms the separator 904, but also increases the deposit 909 below the electrode plate. Due to the convection, a deposit 910 is also generated on the upper part of the electrode plate.

  If charging / discharging is further repeated from the state of FIG. 13C, various short-circuit phenomena may occur between the electrode plate of the negative electrode 902 and the electrode plate of the positive electrode 903, as shown in FIG. 13D. come. First, as a first short-circuit event, when the deposit 909 increases to an amount sufficient to connect between the electrode plate of the negative electrode 902 and the electrode plate of the positive electrode 903, the charge is changed to lead metal by charging. Cause a short circuit. As a second short-circuit event, as with deposit 909, when deposit 910 increases to an amount sufficient to connect between the plates of negative electrode 902 and positive electrode 903, the deposit becomes metallic due to charging. A short circuit occurs when it changes to lead.

  Further, as a third short-circuit event, when the distance between the negative electrode 902 and the positive electrode 903 becomes smaller due to expansion of the electrode plate, the dendrite 911 generated from the positive electrode 903 and the sulfation (not shown) generated on the surface of the negative electrode 902 Contact is likely to occur, and a short circuit may occur at some timing. FIG. 13 schematically shows the change in the cell 901 when only the electrode plate of the negative electrode 902 expands. However, in reality, the same expansion or the like occurs in the positive electrode 903, and both electrode plates have the same expansion. The short circuit may occur due to expansion or the like.

  If any one of the short-circuits described above occurs, the short-circuited cell does not function as a storage battery. For example, when a short-circuit occurs in one cell, the original output 12V is reduced to 10V. As a result, since the storage battery cannot be used normally, it is strongly desired to quickly detect this when a cell short circuit occurs.

  Therefore, for the purpose of quickly detecting a cell short circuit, Patent Document 1 provides a judgment positive electrode and a judgment negative electrode on the upper part of the electrode in the battery, and a short circuit occurs between the judgment positive electrode and the judgment negative electrode. Techniques for vehicle control devices configured to monitor the occurrence are disclosed.

  Further, Patent Document 2 discloses a lead storage battery having a structure in which a pressure sensor is disposed on a short-circuit prevention plate inserted between an upper portion of a separator and a negative electrode strap. When the positive electrode plate expands and the short-circuit prevention plate is pressed against the lower surface of the negative electrode strap, the pressure sensor is pressed and the electrical resistance value decreases rapidly, so detecting this will end the life of the lead-acid battery. It is configured to notify that there is.

  Furthermore, in Patent Document 3, a measurement electrode is brought into contact with each electrolyte solution of two adjacent cells, and a potential difference between the two electrodes is measured. Based on this, a potential difference data string between each adjacent cell is measured. And a method for inspecting a lead storage battery that detects a short circuit inside the cell from these values is disclosed. The measurement electrode is inserted into the battery through a hole such as a liquid port provided in the lead storage battery.

JP 2009-097496 A Japanese Patent Laid-Open No. 2006-185707 Japanese Patent Laid-Open No. 2007-103112

  However, in the vehicle control device described in Patent Document 1, it is possible to monitor a short circuit due to the deposit (the deposit 910 shown in FIG. 13C) generated on the upper part of the electrode plate by the convection of the electrolytic solution. The short circuit due to the precipitate 909 shown in FIG. 13C and the short circuit due to the dendrite generated between the negative electrode and the positive electrode cannot be detected.

  Moreover, in the lead storage battery described in Patent Document 2, the fact that the positive electrode plate has been expanded is used for the determination of the life of the lead storage battery. In such a method, any of the first to third short-circuit events described above is accurate. It cannot be detected well, and there is a possibility that a cell short circuit may occur before the lifetime can be determined. In order to prevent cell short circuit, an insulating plate is provided to prevent cell short circuit. However, since the life cannot be determined by electrode plate expansion, a pressure sensor is provided. By taking such a complicated configuration, inherently the factors that inhibit the movement of ions between the electrode plates are increased. Since this changes the charge / discharge characteristics of the battery, there is a problem that the performance and configuration of the battery are all remade by introducing a short-circuit system.

  Furthermore, in the test method for the lead storage battery described in Patent Document 3, when using the lead storage battery for a trial, it is necessary to attach monitoring electrodes to all the cells. The monitoring system configuration becomes complicated and the cost increases. Although a method of sequentially inserting measurement electrodes into each cell in the battery manually is conceivable, the management cost increases and it is difficult to apply the sensor system.

  The present invention has been made to solve these problems, and an object of the present invention is to provide a cell short-circuit detection method and a detection device for a storage battery capable of reliably detecting a cell short-circuit.

  1st aspect of the cell short circuit detection method of the storage battery of this invention is a cell short circuit detection method of the storage battery which detects the cell short circuit which generate | occur | produces in the storage battery which contains one or more cells, Comprising: The voltage between the terminals of the said storage battery, and electric current And determining whether the storage battery is charging / discharging or stopping charging / discharging based on the current, and determining that the storage battery is charging / discharging, compare the voltage between the terminals with a predetermined voltage tolerance, When it is determined that the voltage between the terminals is lower than the allowable voltage value, predetermined voltage drop information is stored. On the other hand, when the storage battery is determined to be in charge / discharge stop, an elapsed time t from charge / discharge stop is obtained, and a stable open-circuit voltage is obtained. The degree of deterioration of the storage battery is estimated using a relaxation function F (t) that calculates the amount of change in the open-circuit voltage (OCV), which is the amount of change in the voltage between the terminals at the elapsed time t from (stable OCV), and the deterioration The degree of deterioration allowed When the degree of deterioration is determined to exceed the allowable deterioration value, the predetermined excess deterioration information is stored, and when either the voltage drop information or the deterioration excess information is stored, the other is already It is determined whether or not it is stored, and when it is determined that both the voltage drop information and the excess deterioration information are stored, the cell short circuit is detected.

  In another aspect of the battery short-circuit detection method of the storage battery of the present invention, when the storage battery is determined to be charging / discharging, the current is further compared with a predetermined current determination value for determining the magnitude of the discharge current, The terminal voltage is compared with the voltage allowable value only when the current is determined to be higher than the current determination value (discharge current is negative).

  In another aspect of the battery short-circuit detection method for a storage battery according to the present invention, when the storage battery is determined to be in a charge / discharge stop state, the inter-terminal voltage is further compared with the allowable voltage value, and the inter-terminal voltage is the allowable voltage value. If it is determined that the value is lower than the value, the voltage drop information is stored.

  Another aspect of the battery short-circuit detection method for a storage battery according to the present invention is characterized in that when the storage battery is determined to be in a charge / discharge stop state, the inter-terminal voltage is estimated using a predetermined voltage estimation formula.

According to another aspect of the battery short-circuit detection method of the storage battery of the present invention, when the voltage estimation formula is Vnow (t), the measured value Vm of the terminal voltage until the elapsed time t reaches the first time ta. Using,
Vnow (t) = Vm
And until the elapsed time t exceeds the first time ta and reaches the second time Tb,
Vnow (t) = Vnow (ta) -dV1 * (t-ta)
dV1 = (Vnow (0) −Vnow (ta)) / ta
When the elapsed time t exceeds the second time tb, Vnow (t) = Vnow (tb) −dV2 * (t−tb) using a predetermined voltage change rate dV2.
It is characterized by.

  A first aspect of the battery short-circuit detection device for a storage battery according to the present invention is a cell short-circuit detection device for a storage battery that detects a cell short-circuit generated in a storage battery containing one or more cells, and the inter-terminal voltage and current of the storage battery. A storage means for measuring the storage battery, a voltage between the terminals of the storage battery and a current from the measurement means, and determining whether the storage battery is charging / discharging or stopping charging / discharging based on the current, Is determined to be charging / discharging, the voltage between the terminals is compared with a predetermined allowable voltage value, and when it is determined that the voltage between the terminals is lower than the allowable voltage value, predetermined voltage drop information is stored in the memory, while When it is determined that the storage battery is in a charge / discharge stop, an elapsed time t from the charge / discharge stop is obtained, and an open end voltage (OCV) that is a change amount of the inter-terminal voltage in the elapsed time t from the stable open end voltage (stable OCV). Strange When the deterioration degree of the storage battery is estimated using a relaxation function F (t) for calculating the amount, the deterioration degree is compared with a predetermined allowable deterioration value, and it is determined that the deterioration degree exceeds the allowable deterioration value. Predetermined over-degradation information is stored in the memory, and when one of the voltage drop information and the over-deterioration information is stored in the memory, it is determined whether the other is already stored in the memory, A state detection unit that detects the cell short circuit when it is determined that both the voltage drop information and the excess deterioration information are stored in the memory.

  According to the present invention, a cell short-circuit of a storage battery that can reliably detect a cell short-circuit by determining the occurrence of a cell short-circuit when the voltage between terminals decreases and the degree of deterioration increases. A detection method and a detection apparatus can be provided.

It is a flowchart which shows the outline of the cell short circuit detection method of the storage battery of 1st Embodiment. It is a block diagram of the cell short circuit detector of a 1st embodiment. It is a graph which shows the change of the voltage between terminals when charging / discharging is repeatedly performed by predetermined | prescribed capacity | capacitance change amount ((DELTA) SOC = 5%). It is a graph which shows the change of the voltage between terminals at the time of discharge when the number of discharge cycles differs. It is a graph which shows an example of OCV variation | change_quantity (DELTA) V after a charging / discharging stop. It is a flowchart for demonstrating the method of estimating degradation degree SOH using the relaxation function F (t). It is a flowchart which shows the cell short circuit detection method of the storage battery of 2nd Embodiment (* 8). It is a graph which shows typically change of the voltage between terminals of a storage battery at the time of engine start of a car, and current. It is a flowchart which shows the cell short circuit detection method of the storage battery of 3rd Embodiment. It is a graph which shows an example of the change of the voltage between terminals in charging / discharging stop. It is a flowchart which shows the cell short circuit detection method of the storage battery of 4th Embodiment. It is the external view which shows an example of a lead acid battery, and the schematic block diagram of a cell. It is explanatory drawing which shows typically the change which arises in the cell of a lead acid battery.

  A cell short-circuit detection method and a detection device for a storage battery according to a preferred embodiment of the present invention will be described in detail with reference to the drawings. In addition, about each structural part which has the same function, the same code | symbol is attached | subjected and shown for simplification of illustration and description. The battery short-circuit detection method and the detection device of the storage battery according to the present invention are used as a storage battery mounted on an automobile, a storage battery used in combination with power generation by natural energy such as solar power generation or wind power generation, and a backup power source in the event of a power failure. It can be used for storage batteries.

  In a storage battery containing two or more cells or a battery pack connected in series, if a cell short circuit occurs between adjacent cells or one or more of the batteries, the voltage between the terminals of the storage battery is greatly reduced. A method of monitoring the voltage and detecting the occurrence of a cell short circuit is conceivable. However, with this method, there is a possibility that the occurrence of a cell short circuit may be erroneously detected or overlooked. An example of erroneous detection of a cell short circuit and an example where it cannot be detected will be described with reference to FIG. FIG. 3 shows a change in the voltage between the terminals when charging and discharging are repeatedly performed at a predetermined capacity change amount (ΔSOC = 5%).

  FIG. 3 shows an example in which the voltage between the terminals is greatly reduced at time t1 after repeated charging and discharging. When the cell short circuit is determined only by monitoring the voltage between the terminals, if a significant voltage drop as shown in FIG. 3 occurs, it is determined that a cell short circuit has occurred. However, even if a large current is temporarily discharged to the load, such a decrease in the voltage between the terminals occurs. Therefore, only by monitoring the voltage between the terminals, a voltage drop due to a cell short-circuit and a large current discharge to the load It cannot be distinguished from the voltage drop due to.

  Therefore, if the occurrence of a cell short circuit is determined only by the fact that the inter-terminal voltage has fallen below a predetermined voltage allowable value, there is a risk of erroneous detection. In order to avoid this, for example, a method of determining the cause of the voltage change based on the gradient of the voltage change at the time of charging / discharging can be considered, but the discharge capacity and charging efficiency change depending on the deterioration state of the storage battery, It is difficult to accurately grasp the cause of the voltage change only by monitoring the voltage change during charging and discharging.

  In addition, in storage batteries for automobiles, for example, discharge other than normal usage such as leaving the light on may be considered, and in that case, the battery voltage decreases and the storage battery does not cause a cell short circuit. Will lead to deterioration. If only the voltage between the terminals is monitored, there is a risk of erroneous detection that a cell short circuit has occurred in such a case.

  On the other hand, even when the significant decrease in the inter-terminal voltage is due to the occurrence of a cell short circuit, when the battery is subsequently charged, the inter-terminal voltage returns to the normal range voltage value. Therefore, if a voltage drop is not detected between the occurrence of a cell short-circuit and the start of charging, the occurrence of a cell short-circuit will be overlooked at least temporarily. This means that it could not be detected early.

  Therefore, in the storage battery cell short-circuit detection method and detection device of the present invention, in order to reliably detect a cell short-circuit that occurs between adjacent cells, the deterioration degree (SOH) of the storage battery is monitored in addition to monitoring the voltage between terminals. When a significant drop in the voltage between the terminals is detected in a state where the deterioration of the storage battery is progressing, it is determined that a cell short circuit has occurred. Here, for monitoring the degree of deterioration of the storage battery, it is preferable to use a method that can appropriately detect the slow-degradation that leads to a cell short circuit.

  As a method for detecting deterioration of a storage battery, the state of the storage battery is detected using a relaxation function F (t) that calculates an open-circuit voltage (OCV) change amount (denoted as ΔV) at an elapsed time t from the stop of charge / discharge of the storage battery. (Japanese Patent Application No. 2008-103925). Here, the OCV change amount ΔV is given as a change amount of the inter-terminal voltage from the stable OCV when charging / discharging is stopped.

In this storage battery state detection method, when the storage battery is in a predetermined state (represented by h), ΔV change (F (t)) after stopping charging / discharging, SOC and SOH are used as reference data (respectively F ^{ref (h)} (T), SOC ^{ref (h)} , SOH ^{ref (h)))} . Here, the predetermined state h is a state selected in advance, such as a state where the storage battery is not used (new), a state where it has been used to some extent, or a state where deterioration has progressed due to use. F (t) is optimized using ΔV calculated from the voltage measurement value, and F ^{ref (h)} (t) closest to F (t) from the reference data, and SOC ^{ref (h)} , SOH at that time Select ^{ref (h)} . Then, SOH is estimated using the selected F ^{ref (h)} (t), SOC ^{ref (h)} , SOH ^{ref (h)} and F (t). This state detection method will be described below.

The relaxation function F (t) is a function such as the following equation consisting of the sum of a plurality of relaxation functions fi (i = 1 to m) for each reaction rate so that changes in events with different reaction rates can be accurately approximated. .
ΔV = F ⁿ (t) = f ^{1 n} (t) + f 2 ⁿ (t) +... + Fm ⁿ (t) (1)
Here, n indicates a relaxation function after the nth charge / discharge.

  An example of how the change in the voltage between the terminals during discharge changes with the number of discharge cycles is shown in FIG. Here, the larger the number of discharge cycles, the more the change in inter-terminal voltage in a storage battery that has deteriorated. The voltage between terminals at the time of discharge increases as the amount of voltage drop at the end of discharge progresses as the deterioration progresses, and when the deterioration further progresses, a cell short-circuit occurs and an abrupt voltage drop occurs. FIG. 5 shows an example of the OCV change amount ΔV after the charge / discharge stop. FIG. 5 shows the change in the OCV change amount ΔV by comparing the case where the storage battery is close to a new product and the case where the deterioration has progressed. The change rate of the OCV change amount decreases as the deterioration of the storage battery progresses, and the deterioration state of the storage battery is accurately determined by optimizing this with the relaxation function F (t) composed of the relaxation function fi for each reaction speed. It becomes possible to do.

In the storage battery state detection method described in Japanese Patent Application No. 2008-103925, the OCV change amount ΔV in a representative state of the storage battery as shown in FIG. 5 is obtained together with the SOC and SOH in each state by reference data (respectively F ^{ref ( h)} (t), SOC ^{ref (h)} , SOH ^{ref (h)} ). As reference data, for example, data in a new state immediately before the start of use of the storage battery, data when the storage battery has deteriorated to some extent, data when the deterioration has greatly advanced, etc. are measured and stored in advance. Good.

When the voltage measurement value at the elapsed time t from the charge / discharge stop is Vm and the stable OCV is OCVs,
ΔV = Vm (t) −OCVs (2)
Given in. As the OCVs, for example, a voltage measurement value Vm (t = 20 hr) when 20 hours have passed since the charge / discharge stop can be used (assuming OCV _{20 hr} ). Further, OCV _20hr is stored in advance as reference data OCV _20hr ^{ref (h)} together with F ^{ref (h)} (t) and the like, and used in OCVs when t <20 hr in the calculation of equation (2). it can.

The relaxation function fi for each reaction rate can be determined by optimally approximating F ⁿ (t) in the equation (1) using the result of ΔV in the equation (2) calculated from the voltage measurement value Vm (t). . F ⁿ (t) that is optimally approximated is compared with F ^{ref (h)} (t) of the reference data, and the closest reference data is selected. From the optimally approximated F ⁿ (t) and the selected reference data, the degradation degree SOH after the nth charge / discharge can be estimated by the following equation.
^{SOHi n = {fi n (t} ) / fi ref (t)} * SOHi ref (3)
^{SOH n = A * SOH1 n +} B * SOH2 n + ··· + M * SOHm n
= A * {f1 ⁿ (t) / f1 ^ref (t)} SOH1 ^ref +
^{B * {f2 n (t)} / f2 ref (t)} SOH2 ref + ··· +
M * {fm ⁿ (t) / fm ^ref (t)} SOHm ^ref
Here, the coefficients A to M are parameters set in advance.

As an example, the case where the relaxation function F (t) is given by four relaxation functions fi for each reaction rate as in the following equation will be described in more detail.
F (t) = ffast (t) + fslow (t)
= {Ffast1 (t) + ffast2 (t)} + {fslow1 (t) + fslow2 (t)}
The relaxation function for each reaction rate in the above equation is set so as to be dominant in each time zone divided by four reference times (referred to as t1, t2, t3, and t4). As examples of the reference times t1, t2, t3, and t4, they can be set to 10 s, 1000 s, 36000 s, and 72000 s, respectively.

The relaxation function F (t) is t <t1
F ⁿ (t) = ffast1 ⁿ⁻¹ (t) + ffast2 ⁿ⁻¹ (t) +
fslow1 ^n-1 (t) + fslow2 ^n-1 (t)}
For t1 ≦ t <t2,
F ⁿ (t) = ffast1 ⁿ (t) + ffast2 ⁿ⁻¹ (t) +
fslow1 ^n-1 (t) + fslow2 ^n-1 (t)}
For t2 ≦ t <t3,
F ⁿ (t) = ffast1 ⁿ (t) + ffast2 ⁿ (t) +
fslow1 ^n-1 (t) + fslow2 ^n-1 (t)}
For t3 ≦ t <t4,
F ⁿ (t) = ffast1 ⁿ (t) + ffast2 ⁿ (t) +
fslow1 ⁿ (t) + fslow2 ⁿ⁻¹ (t)}
For t4 ≦ t,
F ⁿ (t) = ffast1 ⁿ (t) + ffast2 ⁿ (t) +
fslow1 ⁿ (t) + fslow2 ⁿ (t)}
It can be like this.

Using any of F ⁿ (t) in the above equation, for example, SOH (referred to as SOH 1) due to the stratification degree of the slow reaction rate can be estimated by the following equation.
SOH1 ⁿ = fslow ⁿ (t) / fslow ^ref (t) * SOH1 ^{ref
= {Fslow1 n (t) +} fslow2 n (t)} /
^{{Fslow1 ref (t) + fslow2} ref (t)} * SOH1 ref

(First embodiment)
A battery short-circuit detection method and a detection apparatus for a storage battery according to a first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a flowchart showing a schematic process flow of a cell short-circuit detection method for a storage battery according to this embodiment, and FIG. 2 is a block diagram of the cell short-circuit detection apparatus according to this embodiment. In FIG. 2, the storage battery 10 is configured to supply (discharge) current to the load 20 or to be charged from the charger 30. The cell short circuit detection apparatus 100 of this embodiment inputs the voltage and current between terminals from the storage battery 10, and monitors whether the cell short circuit generate | occur | produced in the storage battery 10 based on this.

  The cell short circuit detection device 100 includes a state detection unit 110, a measurement unit 120, a memory 130, and a display unit 140. The measuring means 120 measures the voltage and current between the terminals of the storage battery 10 and outputs them to the state detection unit 110. The state detection unit 110 performs different processes depending on whether the storage battery 10 is being charged or discharged and when charging or discharging is stopped. That is, during charging / discharging, the measured voltage between the terminals is compared with a predetermined allowable voltage value (Vlim), and when it is determined that the voltage between the terminals is lower than the allowable voltage value Vlim, the predetermined voltage drop information is stored in the memory 130. save. Then, it is checked whether both the voltage drop information and the deterioration excess information described later are stored in the memory 130, and it is determined that a cell short circuit has occurred when both are stored.

  On the other hand, during charging / discharging stop, the elapsed time t from charging / discharging stop is calculated | required, and the deterioration degree of the storage battery 10 at that time is estimated like Formula (3) using the relaxation function F (t). The estimated deterioration degree is compared with a predetermined deterioration allowable value (referred to as SOHlim), and when it is determined that the deterioration degree exceeds the deterioration allowable value SOHlim, predetermined excess deterioration information is stored in the memory 130. . Then, it is checked whether both the voltage drop information and the deterioration excess information are stored in the memory 130, and when both are stored, it is determined that a cell short-circuit has occurred.

  The cell short circuit detection method of the storage battery of this embodiment is demonstrated still in detail using FIG. The cell short circuit detection method of this embodiment is performed in the state detection unit 110 at a predetermined cycle. When the state detection unit 110 reaches a predetermined period, first, the voltage Vm between the terminals of the storage battery 10 and the current Im are measured using the measuring unit 120 (step S1). In the next step S2, it is determined whether the storage battery 10 is being charged or discharged. In the determination of charge / discharge, when the current Im measured in step S1 is almost zero, charge / discharge is stopped, and the other is charged / discharged.

  If it is determined in step S2 that charging / discharging is being performed, it is determined in step S3 whether or not the inter-terminal voltage Vm is lower than the allowable voltage value Vlim. The allowable voltage value Vlim is set to a suitable value equal to or lower than the minimum voltage required for the load 20 in consideration of a voltage drop amount due to a cell short circuit. If it is determined in step S3 that the inter-terminal voltage Vm is lower than the allowable voltage value Vlim, in step S4, voltage drop information indicating that the inter-terminal voltage Vm is lower than the allowable voltage value Vlim is stored in the memory 130. . Or you may make it preserve | save the voltage Vm between terminals at this time. On the other hand, if it is determined in step S3 that the inter-terminal voltage Vm is equal to or greater than the voltage allowable value Vlim, the process is terminated as no cell short-circuit has occurred (step S5).

  When the voltage drop information is stored in the memory 130 in step S4, it is determined in step S6 whether the excess deterioration information has been stored in the memory 130 so far. As a result, when the deterioration excess information is already stored in the memory 130, a process when a cell short-circuit has occurred is performed in step S7. That is, a process for notifying that a cell short-circuit has occurred is performed, and a message for notifying the occurrence of a cell short-circuit is displayed on the display means 140 in the next step S8. On the other hand, if it is determined in step S6 that the excess deterioration information is not stored in the memory 130, the process is terminated because no cell short-circuit has occurred (step S5).

  On the other hand, when it is determined in step S2 that charging / discharging is not being performed (charging / discharging is stopped), the deterioration degree SOH of the storage battery 10 is estimated using the relaxation function F (t) in step S9. In the next step S10, it is determined whether or not the estimated deterioration degree SOH exceeds the allowable deterioration value SOHlim. The allowable deterioration value SOHlim is also set in advance based on the use conditions of the storage battery 10 and the like.

  If it is determined in step S10 that the deterioration degree SOH exceeds the allowable deterioration value SOHlim, the deterioration excess information indicating that the deterioration degree SOH exceeds the allowable deterioration value SOHlim is stored in the memory 130 in step S11. To do. Alternatively, the deterioration degree SOH at this time may be stored. On the other hand, if it is determined in step S10 that the deterioration degree SOH is equal to or less than the allowable deterioration value SOHlim, the process is terminated as no cell short-circuit has occurred (step S5).

  When the excess deterioration information is stored in the memory 130 in step S11, it is determined in step S12 whether the voltage drop information has been stored in the memory 130 so far. As a result, when the voltage drop information is already stored in the memory 130, the process proceeds to steps S7 and S8 to perform the process when the cell short circuit occurs. On the other hand, if it is determined in step S12 that the voltage drop information is not stored in the memory 130, it is determined that no cell short-circuit has occurred (step S5).

  Next, a method of estimating the deterioration degree SOH of the storage battery 10 using the relaxation function F (t) in step S9 will be described in more detail with reference to FIG. FIG. 6 is a flowchart for explaining a method of estimating the deterioration degree SOH using the relaxation function F (t). First, in step S21, the inter-terminal voltage Vm measured in step S1 is input as the inter-terminal voltage (open-end voltage) of the storage battery 10 that is stopped in charge and discharge. In the next step S22, the OCV variation ΔV is calculated from the inter-terminal voltage Vm and the appropriately selected OCVs.

In step S23, the relaxation function F (t) is optimized so that the relaxation function F (t) accurately approximates the OCV change amount ΔV calculated in step S23. In step S24, the reference data F ^{ref (h)} (t) closest to the optimized relaxation function F (t) is selected. In step S25, the degree of degradation SOH is calculated based on the equation (3) using the optimized F (t), the reference data F ^{ref (h)} (t), and SOH ^{ref (h)} .

  According to the cell short-circuit detection method and the detection device of the storage battery of the present embodiment, since it is determined that a cell short-circuit has occurred when it is detected that the voltage between terminals is reduced and the degree of deterioration is increasing, A cell short circuit can be reliably detected, and erroneous detection can be avoided. Thereby, the storage battery provided with the cell short-circuit detection device of the present embodiment can supply power of a stable voltage to the load, and can improve reliability as a backup of vehicle operation or auxiliary equipment.

  In a conventional storage battery that does not include the cell short-circuit detection device according to the present embodiment, replacement is performed with a calendar life from the time of shipment in order to prevent a cell short-circuit. On the other hand, in the storage battery using the cell short-circuit detection method and the detection device of the present embodiment, cell short-circuit is determined based on the use history for each storage battery, so that the accuracy of the life diagnosis of the storage battery is improved and the storage battery is It can be used efficiently until the end of its life, and cost can be reduced.

(Second Embodiment)
A storage battery cell short-circuit detection method and detection apparatus according to a second embodiment of the present invention will be described below with reference to FIG. FIG. 7 is a flowchart showing a process flow of the cell short-circuit detection method of the storage battery of the present embodiment. In an automobile, an inrush current of about 1000 A is supplied from the storage battery to the motor when the engine is started, and then cranking of about 100 A is performed. An example of changes in voltage and current at this time is shown in FIG. FIG. 8 is a graph schematically showing changes in the inter-terminal voltage and current of the storage battery when the automobile engine is started.

  As shown in FIG. 8, a large current is discharged to the motor only for a short time, but the voltage between the terminals may momentarily fall below the allowable voltage value Vlim. However, such an instantaneous voltage drop has a small influence on the discharge capacity of the storage battery, and there is no possibility that an error may occur in the microcomputer or the like that is supplied with power from the storage battery. Therefore, it is necessary to prevent a temporary voltage drop due to such a normal usage form from being erroneously detected as a cell short circuit.

  Therefore, in the cell short-circuit detection method and the detection device of the storage battery according to the present embodiment, when the measured current value is a large discharge current equal to or less than a predetermined current determination value (the measured current is negative for discharge), the voltage between the terminals It is not determined whether or not the voltage is lower than the allowable voltage value. The cell short circuit detection method of the storage battery of this embodiment is demonstrated using the flowchart of the process shown in FIG.

  First, the inter-terminal voltage Vm and current Im of the storage battery 10 are measured in step S1, and if it is determined in step S2 that charging / discharging is in progress, it is determined in step S31 whether the current Im is higher than a predetermined current determination value Ist. To do. Here, the current determination value Ist is a value set based on a current value that may cause the inter-terminal voltage Vm to reach the voltage allowable value Vlim due to the discharge.

  If it is determined in step S31 that the current Im is higher than the current determination value Ist, the voltage drop is determined by the processing in step S3 and subsequent steps to detect the occurrence of a cell short circuit, as in the first embodiment. On the other hand, if it is determined in step S31 that the current Im is equal to or smaller than the current determination value Ist, the process proceeds to step S5 without detecting the cell short circuit and the process is terminated. In this case, it is determined that a large current has been discharged for a short time due to motor activation or the like, and the process of determining a voltage drop and detecting a cell short circuit is not performed. On the other hand, when it is determined in step S2 that charging / discharging is stopped, the occurrence of cell short-circuiting is detected by determining over-deterioration by the processing in step S9 and subsequent steps, as in the first embodiment.

  According to the storage battery cell short-circuit detection method and detection device of the present embodiment, it becomes possible to detect a cell short-circuit by distinguishing from an instantaneous voltage drop due to a short-time discharge of a large current, thereby preventing erroneous detection of a cell short-circuit. Thus, a highly reliable cell short circuit can be detected.

(Third embodiment)
In the cell short-circuit detection method and the detection device of the storage battery according to the first embodiment, only the detection of whether or not the deterioration degree SOH has exceeded the allowable value is performed while charging and discharging are stopped. However, since there is a possibility that the cell short-circuit may occur and the voltage between the terminals may be reduced even during the charge / discharge stop, in the present embodiment, the voltage drop is detected even during the charge / discharge stop. The cell short circuit detection method of the storage battery of this embodiment is demonstrated below using FIG. FIG. 9 is a flowchart showing a process flow of the cell short-circuit detection method of the storage battery of the present embodiment.

  In the present embodiment, when it is determined in step S2 that charging / discharging is being performed, a voltage drop is determined in the same manner as in the first embodiment to detect the occurrence of a cell short circuit. On the other hand, if it is determined in step S2 that charging / discharging is stopped, the processing of steps S40 to S44 is performed in addition to the processing of steps S9 to S12 of the first embodiment.

  The microcomputer used for the state detection unit 110 detects the state of the storage battery 10 at high speed in a short cycle during charging / discharging or immediately after stopping charging / discharging (high-speed response mode). In this case, the power consumption consumed by the storage battery state detection device is relatively large. In addition, when a certain amount of time has elapsed after stopping charging / discharging, the microcomputer shifts to a low-speed mode in which the processing cycle of the microcomputer is lengthened in order to reduce power consumption. Furthermore, when the elapsed time from the charge / discharge stop becomes longer, the mode shifts to the stop mode in which the processing of the microcomputer is stopped. In this case, power consumption becomes extremely small.

  In this embodiment, while charging / discharging of the storage battery 10 is stopped, the voltage of the storage battery is monitored and monitoring according to the operation mode of the microcomputer is performed. First, the terminal voltage Vm measured in step S40 is set to Vm_stop. In the next step S41, as in step S3, it is determined whether or not the inter-terminal voltage Vm_stop during the charge / discharge stop is lower than the allowable voltage value Vlim_stop. In step S41, if it is determined that the inter-terminal voltage Vm_stop during the charge / discharge stop is lower than the allowable voltage value Vlim_stop, voltage decrease information indicating that the inter-terminal voltage Vm_stop is lower than the allowable voltage value Vlim_stop in step S42. Save in the memory 130. On the other hand, if it is determined in step S41 that the inter-terminal voltage Vm_stop is greater than or equal to the allowable voltage value Vlim_stop, the process proceeds to step S9 to determine that excessive deterioration has occurred and detect the occurrence of a cell short-circuit as in the first embodiment. To do.

  If it is determined in step S11 that the deterioration has been exceeded, and if it is determined in step S12 that the voltage drop information is also stored, the process proceeds to step S7 in the same manner as in the first embodiment to notify that a cell short circuit has occurred. On the other hand, when it is determined in step S12 that the voltage drop information is not stored, in step S43, the state detection of the storage battery 10 is instructed at a predetermined cycle. This is because when the microcomputer is in the stop mode, the voltage Vm between the terminals is measured or the current voltage value Vnow is calculated from the voltage drop measured in advance as reference data in order to start the low speed mode and detect the state. It is to be estimated. Then, when there is a state detection instruction in step S43, it is determined whether or not the inter-terminal voltage Vm_stop at that time is lower than the voltage allowable value Vlim_stop, and if it is lower, the process proceeds to step S7. On the other hand, when the inter-terminal voltage Vm_stop is equal to or greater than the voltage allowable value Vlim_stop, the process returns to step S43, and the detection of the state of the storage battery 10 is instructed again at a predetermined cycle.

  According to the cell short-circuit detection method and the detection device of the storage battery of this embodiment, even when a cell short-circuit occurs during charge / discharge stop and the inter-terminal voltage is significantly reduced, this can be reliably detected. .

(Fourth embodiment)
In the battery short-circuit detection method and the detection device of the storage battery of the first embodiment, the terminal voltage Vm is measured and used to estimate the deterioration degree SOC even when charging / discharging is stopped. However, for example, in a storage battery mounted on an automobile, when the automobile is stopped for a long time, in order to reduce the power consumption of the storage battery 10, the driving power supplied to the sensor such as the measuring means 120 is reduced to reduce the power consumption. May be stopped. In that case, the inter-terminal voltage Vm cannot be measured by the measuring means 120. As a countermeasure, it is possible to continue using the terminal voltage Vm measured last by the measuring means 120, but the error of the terminal voltage Vm increases as the stoppage period becomes longer.

  Therefore, as a result of examining the change in the voltage between the terminals when charging / discharging was stopped for a long time, after about 100 hours or more have elapsed from the stopping of charging / discharging, the voltage change can be substantially the same regardless of the initial state of the storage battery. It became clear. An example of the change in the voltage between the terminals while charging / discharging is stopped is shown in FIG. Here, taking into account that a minute current is supplied to the sensor or the like even when the vehicle is stopped, a change in the voltage between the terminals when there is a discharge current of 10 mA is shown. Moreover, the change of each terminal voltage shown to the figure has shown the case where initial values, such as SOC when charge / discharge stop is started, differ. As shown in the figure, it can be seen that when about 100 hours or more have elapsed from the stop of charging / discharging, the change in voltage becomes substantially the same (parallel) regardless of the initial state of the storage battery.

  Reflecting the characteristics of the change in the voltage between the terminals while charging / discharging is stopped, in the cell short-circuit detection method of the storage battery according to the present embodiment, a voltage estimation formula or the like prepared in advance for the voltage between terminals when charging / discharging is stopped is used. To be estimated. In the following, in order to distinguish the terminal voltage (hereinafter referred to as the current terminal voltage) when the time t has elapsed since charging / discharging was stopped from the measured value Vm, the current terminal voltage is expressed as Vnow ( t). An estimation formula for estimating the current inter-terminal voltage Vnow (t) when charging / discharging is stopped will be described below.

First, until the time ta elapses after charging / discharging is stopped (for example, ta = 10 hours), the measurement voltage Vm can be used during the measurement if the measurement unit 120 can measure the voltage between the terminals.
Vnow (t) = Vm (4)
0 ≦ t ≦ ta

Next, until the elapsed time t from the charge / discharge stop exceeds the time ta and reaches the time tb (for example, ta = 100 hours), when the change in the voltage between the terminals is different depending on the initial state of the storage battery 10, the measuring means Using the terminal voltage Vnow (ta) last measured at 120, the current terminal voltage Vnow (t) can be calculated by the following equation.
Vnow (t) = Vnow (ta) -dV1 * (t-ta) (5)
dV1 = (Vnow (0) −Vnow (ta)) / ta
ta <t ≦ tb

  Here, dV1 is a change rate of the inter-terminal voltage calculated using the measured value of the inter-terminal voltage in the measurable period, and the inter-terminal voltage Vnow (0) when the charge / discharge stop is started (t = 0). ) And the inter-terminal voltage Vnow (ta) when the time ta has elapsed. As shown in FIG. 10, the rate of change of the voltage between terminals gradually decreases with time, so that the voltage between terminals is estimated on the safe side (low voltage side) by using the above dV1. It will be.

  Further, if the measuring unit 120 cannot be used, the timer of the sensor cannot be used, and there is a possibility that the elapsed time t from the stop of charging / discharging cannot be obtained. In that case, the time can be acquired from a timer or counter in a system (such as an automobile) other than the sensor, or can be acquired by communication means (GPS, VICS, etc.) with the outside.

Furthermore, since the change in the voltage between the terminals becomes substantially constant when time tb or more has elapsed since the charge / discharge stop, the change rate dV2 at this time is obtained in advance. The change rate dV2 can be calculated and used, for example, from the difference between the terminal voltage at the time tb shown in FIG. 10 and the terminal voltage when a predetermined time (for example, 1000 hours) has passed. At this time, the inter-terminal voltage Vnow (t) is given by the following equation using dV2.
Vnow (t) = Vnow (tb) −dV2 * (t−tb) (6)
tb <t

  The cell short-circuit detection method of the storage battery of this embodiment using the above-described estimation formula of the inter-terminal voltage during charge / discharge stop will be described with reference to FIG. FIG. 11 is a flowchart for explaining the processing flow of the cell short-circuit detection method for a storage battery of this embodiment. When determining whether or not charging / discharging is being performed in step S2 in FIG. 11A, if the measurement value of the current Im cannot be obtained because the measuring unit 120 has stopped, the charging / discharging is stopped by detecting that the current Im cannot be measured. Let me judge it as medium.

  In the cell short-circuit detection method of this embodiment when it is determined that charging / discharging is stopped, the terminal voltage Vnow (t) is first calculated in step S50. The processing after acquiring the inter-terminal voltage is the same as in the first embodiment or the third embodiment. However, after step S9 or step S40, Vnow (t) is used as the inter-terminal voltage instead of the measured value Vm.

  The process in step S50 will be described with reference to FIG. First, in step S51, it is determined whether or not the elapsed time t from the charge / discharge stop is equal to or less than the time ta. When the elapsed time t is equal to or less than the time ta, the process proceeds to step S52, while the elapsed time t exceeds the time ta. If so, go to Step S53. In step S52, terminal voltage Vnow (t) is calculated using equation (4), and the process ends (proceed to step S9 in FIG. 11A), and so on.

  Next, in step S53, it is determined whether or not the elapsed time t is equal to or less than the time tb. When the elapsed time t is equal to or less than the time tb, the process proceeds to step S54, whereas when the elapsed time t exceeds the time tb, the step is performed. Proceed to S55. In step S54, terminal voltage Vnow (t) is calculated using equation (5), and the process ends. In step S55, the terminal voltage Vnow (t) is calculated using equation (6), and the process ends.

  As described above, in the storage battery cell short-circuit detection method and the detection device according to the present embodiment, an appropriate inter-terminal voltage can be obtained even when charge / discharge is stopped, and a cell short-circuit can be reliably detected.

  In addition, the description in this Embodiment shows an example of the cell short circuit detection method and detection apparatus of the storage battery which concern on this invention, and is not limited to this. The detailed configuration and detailed operation of the storage battery cell short-circuit detection method and the detection device in the present embodiment can be changed as appropriate without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 10, 900 Storage battery 20 Load 30 Charger 100 Cell short circuit detection apparatus 110 State detection part 120 Measurement means 130 Memory 140 Display means 901 Cell 902 Negative electrode 903 Positive electrode 904 Separator 905 Negative electrode terminal 906 Positive electrode terminal 907 Cell container 908 Electrolytic solution 909 Precipitate 910 Deposit 911 Dendrite

Claims (6)

A battery short-circuit detection method for a storage battery that detects a cell short-circuit that occurs in a storage battery containing one or more cells,
Obtaining the inter-terminal voltage and current of the storage battery, determining whether the storage battery is charging / discharging or stopping charging / discharging based on the current, and determining that the storage battery is charging / discharging, determine the inter-terminal voltage. When it is determined that the voltage between the terminals is lower than the allowable voltage value, the predetermined voltage drop information is stored.
If it determines with the said storage battery being charging / discharging stop, the elapsed time t from charging / discharging stop will be calculated | required, and the open end voltage (OCV) which is the variation | change_quantity of the said voltage between terminals in the elapsed time t from stable open end voltage (stable OCV). ) When the degree of deterioration of the storage battery is estimated using a relaxation function F (t) for calculating the amount of change, the degree of deterioration is compared with a predetermined allowable deterioration value, and the deterioration degree exceeds the allowable deterioration value When it is judged, the specified excess deterioration information is saved,
When one of the voltage drop information and the excess deterioration information is stored, it is determined whether the other is already stored, and it is determined that both the voltage drop information and the deterioration excess information are stored. A method for detecting a cell short circuit of a storage battery, characterized by detecting the cell short circuit. When it is determined that the storage battery is being charged / discharged, the current is further compared with a predetermined current determination value for determining the magnitude of the discharge current, and the current is higher than the current determination value (the discharge current is negative). 2. The storage battery cell short-circuit detection method according to claim 1, wherein a comparison between the voltage between the terminals and the voltage allowable value is performed only when it is determined. When it is determined that the storage battery is in charge / discharge stop, the inter-terminal voltage is further compared with the allowable voltage value, and when it is determined that the inter-terminal voltage is lower than the allowable voltage value, the voltage drop information is stored. The cell short-circuit detection method for a storage battery according to claim 1 or 2, characterized in that: 4. The cell short circuit of the storage battery according to claim 1, wherein when the storage battery is determined to be in a charge / discharge stop state, the inter-terminal voltage is estimated using a predetermined voltage estimation formula. 5. Detection method. When the voltage estimation formula is Vnow (t), the measured value Vm of the voltage between the terminals is used until the elapsed time t reaches the first time ta,
Vnow (t) = Vm
And until the elapsed time t exceeds the first time ta and reaches the second time tb ,
Vnow (t) = Vnow (ta) -dV1 * (t-ta)
dV1 = (Vnow (0) - Vnow (ta)) / ta
When the elapsed time t exceeds the second time tb, Vnow (t) = Vnow (tb) −dV2 * (t−tb) using a predetermined voltage change rate dV2.
The cell short-circuit detection method for a storage battery according to claim 4.

A cell short-circuit detection device for a storage battery that detects a cell short-circuit that occurs in a storage battery containing one or more cells,
Measuring means for measuring the voltage and current between the terminals of the storage battery;
Memory,
When the voltage and current between the terminals of the storage battery are acquired from the measuring means, it is determined whether the storage battery is charging / discharging or charging / discharging is stopped based on the current, and when the storage battery is determined to be charging / discharging, the terminal When the inter-voltage is compared with a predetermined voltage allowable value and when it is determined that the voltage between the terminals is lower than the voltage allowable value, the predetermined voltage drop information is stored in the memory, while when the storage battery is determined to be charging / discharging stopped, A relaxation function F (t) for obtaining an elapsed time t from the charge / discharge stop and calculating an open end voltage (OCV) change amount, which is a change amount of the inter-terminal voltage at the elapsed time t from the stable open end voltage (stable OCV). ) Is used to estimate the degree of deterioration of the storage battery, the degree of deterioration is compared with a predetermined allowable deterioration value, and when it is determined that the deterioration degree exceeds the allowable deterioration value, predetermined excess deterioration information is stored in the memory. Save the voltage When one of the lower information and the excess deterioration information is stored in the memory, it is determined whether the other is already stored in the memory, and both the voltage drop information and the excess deterioration information are stored in the memory. And a state detection unit that detects the cell short circuit when it is determined that the cell is short-circuited.

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