JP7125911B2 - Method for estimating internal short-circuit current and method for estimating short-circuit cell capacity - Google Patents

Description

The present invention relates to a method for estimating an internal short circuit current and a method for estimating a short circuit cell capacity.

Conventionally, there is known a method of calculating the electrical resistance of a short-circuited portion at the time of an internal short-circuit using a test device assuming a battery or the like (see, for example, Patent Document 1). In this calculation method, first, the internal resistance at the time of the short circuit is acquired from the correspondence relationship between the AC impedance measured at the time of the internal short circuit of the test device and the frequency. Next, the short-circuit current is calculated by Ohm's law from the internal resistance and the voltage drop measured at the time of short-circuit. Next, the electrical resistance of the short-circuited portion is calculated by Ohm's law from the short-circuit current and the voltage measured at the time of short-circuiting.

JP-A-2006-10648

By the way, according to the calculation method according to the conventional technology, the internal resistance is obtained based on the AC impedance. However, a sudden change in internal resistance due to heat generation due to an internal short circuit, damage, or the like is not considered, and it is difficult to obtain an appropriate internal resistance. As a result, there is a possibility that the short-circuit current and the electrical resistance of the short-circuited portion cannot be calculated properly.
Further, according to the calculation method according to the conventional technology, the maximum value of the electrical resistance of the constituent members of the test device is approximated to the electrical resistance of the short-circuited portion. However, the size (cross-sectional area, length, etc.) of the short-circuited portion changes irregularly due to heat generation or damage caused by an internal short-circuit. may not be able to be calculated properly.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for estimating an internal short-circuit current and a method for estimating a short-circuited cell capacity, which are capable of properly calculating the short-circuit current and capacity during an internal short-circuit. do.

In order to solve the above problems and achieve the object, the present invention employs the following aspects.
(1) A method for estimating an internal short-circuit current according to one aspect of the present invention is a cell (for example, a battery 11 in an embodiment, a cell 19) detected in a closed circuit comprising data of the change over time of the voltage drop detected in and the cell and an external resistor (e.g., external resistor 32 in the embodiment) connected to the cell The internal short-circuit resistance value of the cell (for example, A step of acquiring an internal short-circuit resistance value Rs in the embodiment (for example, step S01 in the embodiment), and the following formula (1) based on the electromotive force E of the cell, the internal resistance value Ri, and the internal short-circuit resistance value Rs and calculating the internal short-circuit current I that flows when the cell is internally short-circuited (for example, step S02 in the embodiment).

(2) A method for estimating a short-circuited cell capacity according to one aspect of the present invention is a deactivated capacity (eg, deactivated capacity Qdead ) and the discharge capacity associated with the discharge of the cell (for example, the discharge capacity (Is×t) in the embodiment) is subtracted from the initial capacity of the cell to obtain the remaining capacity at the time of internal short circuit of the cell (for example, in the embodiment including a short-circuited cell capacity calculation step (for example, step S04 in the embodiment) of calculating the remaining capacity Q).

(3) The method for estimating the short-circuited cell capacity described in (2) above is such that when calculating the remaining capacity sequentially when the internal short circuit of the cell occurs, the previous value Q _n−1 of the remaining capacity and the remaining capacity Based on the following formula (2) based on the deactivation capacity Qdead _n associated with the deactivation of the cell over the period from the previous calculation to the current calculation and the discharge capacity Qdis _n associated with the discharge of the cell over the period may be used to calculate the current value _Qn of the remaining capacity.

(4) The method for estimating the short-circuited cell capacity described in (3) above is a cylindrical body (for example, The cylindrical body 40 in the cell) is divided into a plurality of concentric cylindrical body regions (for example, the short-circuit region 41 and the plurality of cylindrical bodies 42 (1), ..., 42 (m) in the embodiment), and the cell A temperature for acquiring temperature data of changes in the temperature of each of the cylindrical regions over time during an internal short-circuit based on a temperature detection value output from a temperature sensor provided on a short-circuit member that internally short-circuits the cell. a data acquisition step (for example, step S04 in the embodiment); and regarding, among the plurality of cylindrical body regions, the cylindrical body region in which the temperature has reached a predetermined temperature or higher as deactivation based on the temperature data. and a deactivation capacity calculation step (for example, step S04 in the embodiment) of calculating the deactivation capacity.

(5) In the method for estimating the short-circuited cell capacity described in (4) above, the temperature data acquiring step includes: A heat transfer model may be used to obtain a change in temperature of each of the cylindrical regions over time when the cell is internally short-circuited.

(6) The short-circuited cell capacity estimation method according to any one of (2) to (5) above includes a discharge capacity calculation step (for example, Step S04) in the embodiment may be included.

(7) The method for estimating the short-circuited cell capacity according to (6), which is dependent on (5) above, is calculated by a map of the correspondence relationship between the internal resistance, temperature, and capacity of the cell, and the short-circuited cell capacity calculation step. An internal resistance value obtaining step (for example, in the embodiment step S06).

(8) The method for estimating the short-circuited cell capacity according to (6) or (7), which is dependent on (5) above, is calculated by a map of the correspondence relationship between the electromotive force and the capacity of the cell and the short-circuited cell capacity calculation step. An electromotive force obtaining step (for example, step S06 in the embodiment) of obtaining an electromotive force (for example, the electromotive force E in the embodiment) at the time of internal short circuit of the cell may be included based on the obtained remaining capacity.

(9) The method for estimating the short-circuited cell capacity according to (8), which is dependent on (7) above, includes data on the change in voltage drop over time detected in the internally shorted cell, and the cell and A change over time in the voltage drop of the external resistor detected in a closed circuit comprising an external resistor (eg, the external resistor 32 in the embodiment) connected to the cell and the resistance value of the external resistor (eg, , resistance value R in the embodiment) and an internal short-circuit resistance value obtaining step (for example, Step S01) in the embodiment, the electromotive force E obtained by the electromotive force obtaining step, the internal resistance value Ri obtained by the internal resistance value obtaining step, and the internal short circuit obtained by the internal short circuit resistance value obtaining step An internal short-circuit current calculation step (for example, step S02 in the embodiment) of calculating the internal short-circuit current I based on the following formula (3) based on the resistance value Rs may also be included.

(10) In the short-circuited cell capacity estimation method described in (9) above, when calculating the remaining capacity sequentially by the shorted-circuited cell capacity calculating step when the cell is internally short-circuited, the deactivating capacity calculating step includes: The deactivated capacity is calculated by the cylindrical body region considered to be deactivated over the period from the previous calculation of the remaining capacity to the current calculation, and the discharge capacity calculating step is performed on the previous value of the remaining capacity. calculated by the internal short-circuit current calculating step using the electromotive force obtained by the electromotive force obtaining step based on the internal resistance value obtained by the internal resistance value obtaining step and the previous value of the remaining capacity. The discharge capacity may be calculated by time-integrating the internal short-circuit current obtained over the period.

According to the above (1), based on the fact that the equivalent circuit is the same for the internal short circuit and the external short circuit, a map of the correspondence relationship between the voltage drop of the external resistance and the resistance value obtained in advance by storage or measurement is referred to. to obtain the internal short circuit resistance value corresponding to the voltage drop detected at the time of internal short circuit. As a result, even if it is not possible to directly detect the appropriate internal resistance value and internal short-circuit resistance value at the time of an internal short circuit, irregular internal An appropriate internal short circuit resistance value can be indirectly obtained based on the voltage behavior including the change of state.
In addition, the Joule heat at the time of the internal short circuit can be calculated using the internal short circuit current calculated based on the internal short circuit resistance value. As a result, in the total amount of heat generated at the time of an internal short circuit, Joule heat can be grasped separately from reaction heat such as heat generated due to internal combustion and decomposition, for example.

According to (2) above, the remaining capacity is calculated based on the deactivation capacity and the discharge capacity at the time of the internal short circuit. As a result, it is possible to improve the calculation accuracy of the appropriate remaining capacity.

Furthermore, in the case of (3) above, since the remaining capacity is sequentially calculated based on the deactivation capacity and the discharge capacity at the time of internal short circuit, it is possible to improve the calculation accuracy of the appropriate remaining capacity.

Furthermore, in the case of (4) above, the temperature of each cylindrical body region can be obtained with high accuracy based on the temperature detection value of the temperature sensor provided in the short-circuit member, and the calculation accuracy of the deactivation capacity can be improved. can.

Further, in the case of (5) above, by regarding the region of the cell above a predetermined temperature as deactivation, the deactivation capacity accompanying damage to the cell due to heat generation at the time of an internal short circuit can be properly calculated, and the remaining capacity can be reduced. Calculation accuracy can be improved.

Furthermore, in the case of (6) above, it is possible to accurately calculate the discharge capacity based on the internal short-circuit current that locally flows in the cell when an internal short circuit occurs.

Furthermore, in the case of (7) above, since the internal resistance value is acquired based on the remaining capacity in consideration of deactivation and discharge during an internal short circuit, the accuracy of the internal resistance value can be improved.

Furthermore, in the case of (8) above, the electromotive force is obtained based on the remaining capacity in consideration of the deactivation and discharge at the time of the internal short circuit, so the accuracy of the electromotive force can be improved.

Furthermore, in the case of (9) above, it is possible to improve the accuracy of calculating the internal short-circuit current by using the internal resistance value and the electromotive force based on the remaining capacity in consideration of the deactivation and discharge at the time of the internal short-circuit.

Furthermore, in the case of (10) above, the quantitative evaluation accuracy of the short-circuit characteristics and short-circuit behavior can be improved by successively calculating the remaining capacity of the cell at the time of internal short-circuit.

The figure which shows typically the structure of the short-circuit testing apparatus which concerns on embodiment of this invention. FIG. 4 is a diagram showing an equivalent circuit that is the same for an internal short circuit and an external short circuit of a battery in the method for estimating an internal short circuit current according to the embodiment of the present invention; FIG. 4 is a graph showing an example of the correspondence relationship between the time change of the voltage drop in the external resistance of the battery and the resistance value of the external resistance obtained by the method for estimating the internal short-circuit current according to the embodiment of the present invention. A graph showing an example of a correspondence relationship between a voltage drop rate in an external resistance of a short-circuited divided body and a resistance value of the external resistance, which is obtained by the method for estimating an internal short-circuit current according to the embodiment of the present invention. FIG. 4 is a cross-sectional view showing a short-circuit member and a plurality of cylindrical body regions of a cylindrical heat transfer model in the short-circuited cell capacity estimation method according to the embodiment of the present invention; FIG. 4 is a graph showing an example of temperature data (temperature change data of a plurality of cylindrical regions) acquired by a cylindrical heat transfer model in the short-circuited cell capacity estimation method according to the embodiment of the present invention; FIG. 2 is a graph showing an example of a correspondence relationship between discharge capacity and test temperature obtained by a battery discharge test in the method for estimating short-circuited cell capacity according to the embodiment of the present invention. FIG. 2 is a graph showing an example of the correspondence relationship among internal resistance, temperature, and capacity of a battery in the short-circuited cell capacity estimation method according to the embodiment of the present invention. FIG. 2 is a graph showing an example of the correspondence relationship between the electromotive force and the capacity of the battery in the method for estimating the short-circuited cell capacity according to the embodiment of the present invention; 4 is a flow chart of a method for estimating an internal short-circuit current and a method for estimating a short-circuited cell capacity according to an embodiment of the present invention;

An embodiment of the method for estimating the internal short-circuit current and the method for estimating the short-circuited cell capacity of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a diagram schematically showing the configuration of a short-circuit testing device 10 according to an embodiment.
As shown in FIG. 1 , the short-circuit testing apparatus 10 includes a battery 11 , a voltage sensor 13 , a heat quantity sensor 14 , a short circuit member 15 , a heat insulating member 16 and a processing device 17 .

The battery 11 comprises one or more cells 19 arranged in a stack, for example. The cell 19 is, for example, a laminate cell. The cell 19 accommodates therein, for example, an electrolyte layer composed of a separator and an electrolytic solution, a positive electrode plate and a negative electrode plate sandwiching the electrolyte layer from both sides in the thickness direction, and a laminate composed of the electrolyte layer, the positive electrode plate and the negative electrode plate. and a case made of a laminate film. A plurality of stacked cells 19 are electrically connected in series or in parallel.
Voltage sensor 13 detects terminal voltage V of battery 11 .
The heat sensor 14 is a heat flow sensor including, for example, a thermopile or a Peltier element. The calorific value sensor 14 is a relatively high temperature calorimeter including, for example, a Peltier element, and is arranged on the installation bottom side of the battery 11 .
The short-circuiting member 15 is, for example, a rod-shaped member (for example, a nail-shaped member with a tapered tip or a rounded tip) that penetrates the battery 11 in the thickness direction (that is, the stacking direction of the plurality of cells 19) to internally short-circuit the battery 11. rod-shaped member at the tip, etc.). The short circuit member 15 includes a temperature sensor 15a such as a thermocouple.
The heat insulating member 16 maintains the battery 11 in a heat insulating state. For example, the heat insulating member 16 is arranged on the upper surface side of the battery 11 .

The processing device 17 functions when a predetermined program is executed by a processor such as a CPU (Central Processing Unit). The processing device 17 includes a processor such as a CPU (Central Processing Unit), a ROM (Read Only Memory) for storing programs, a RAM (Random Access Memory) for temporarily storing data, and electronic circuits such as a timer. At least part of the processing device 17 may be an integrated circuit such as LSI (Large Scale Integration).
The processing device 17 executes a method for estimating an internal short-circuit current and a method for estimating a short-circuited cell capacity, which will be described later, based on the detection value signals output from the voltage sensor 13 and the temperature sensor 15a. Alternatively, the processing device 17 may drive and control the short-circuit member 15 by controlling an appropriate drive mechanism.

<Acquisition of internal short-circuit resistance value Rs>
A method of obtaining the internal short-circuit resistance value Rs of the battery 11 short-circuited by the short-circuit member 15 (the resistance value Rs of the internal short-circuit resistance 31) will be described below.
FIG. 2 is a diagram showing an equivalent circuit that is the same for an internal short circuit and an external short circuit of the battery 11 in the method for estimating the internal short circuit current according to the embodiment. FIG. 3 is a graph showing an example of the correspondence relationship between the change in voltage drop over time in the external resistor 32 of the battery 11 and the resistance value R of the external resistor 32 obtained by the method for estimating the internal short-circuit current according to the embodiment. . FIG. 4 is a graph showing an example of the correspondence relationship between the voltage drop speed in the external resistor 32 of the battery 11 and the resistance value R of the external resistor 32 obtained by the method for estimating the internal short-circuit current according to the embodiment.

The internal short-circuit resistance value Rs of the battery 11 internally short-circuited by the short-circuit member 15 changes according to, for example, the temperature, area and contact resistance of the short-circuited portion. The processing device 17 acquires the internal short-circuit resistance value Rs of the battery 11 internally short-circuited by the short-circuit member 15 based on the terminal voltage V of the battery 11 detected by the voltage sensor 13 . The processing device 17 acquires the internal short-circuit resistance value Rs based on the data on the time change of the voltage drop due to the terminal voltage V of the battery 11 and referring to a pre-stored map of the short-circuit resistance value and the voltage drop. The map of the short-circuit resistance value and the voltage drop stored in advance is a map of the correspondence relationship between the resistance value R of the external resistor 32 connected to the battery 11 and the change of the voltage drop in the external resistor 32 according to the elapsed time. be.

The processing device 17 acquires a map of the short-circuit resistance value and the voltage drop in the battery 11, assuming that the internal short circuit and the external short circuit of the battery 11 have the same equivalent circuit.
As shown in FIG. 2 , the processing device 17 forms an equivalent circuit of the battery 11 internally short-circuited by the short-circuit member 15 by the electromotive force E of the battery 11 , internal short-circuit resistance 31 and internal resistance 33 . The processor 17 configures an equivalent circuit of the battery 11 externally short-circuited by the external resistor 32 by the electromotive force E of the battery 11, the external resistor 32, and the internal resistor 33. FIG. That is, the processor 17 considers the resistance value (internal short-circuit resistance value) Rs of the internal short-circuit resistance 31 and the resistance value R of the external resistance 32 to be the same.

The processing device 17 measures the voltage drop of the external resistor 32 based on the terminal voltage V detected by the voltage sensor 13 each time the resistance value R of the external resistor 32 is appropriately changed during measurement for map acquisition. do. As shown in FIG. 3, for example, as the resistance value R of the external resistor 32 increases from the first resistance value R1 to the third resistance value R2, the voltage drop speed of the external resistor 32 tends to decrease. As shown in FIG. 4, the processing device 17 acquires a map of the correspondence relationship between the short-circuit resistance value (resistance value R of the external resistor 32) and the voltage drop rate in the battery 11, and stores it in the ROM or the like.

The processing device 17 measures the voltage drop across the internal short-circuit resistor 31 based on the terminal voltage V detected by the voltage sensor 13 when measuring the voltage drop across the battery 11 internally short-circuited by the short-circuit member 15 . Based on the voltage drop data of the internal short-circuit resistor 31, the processing unit 17 refers to the map of the correspondence relationship between the short-circuit resistance value (resistance value R of the external resistor 32) and the voltage drop rate, and calculates the voltage of the internal short-circuit resistor 31. Get the short circuit resistance value corresponding to the drop. The processing device 17 sets the short-circuit resistance value acquired from the map as the internal short-circuit resistance value Rs.

<Calculation of internal short-circuit current Is>
A method of calculating the internal short-circuit current Is that locally flows through the battery 11 internally short-circuited by the short-circuit member 15 will be described below.
The processing device 17 calculates an internal short-circuit current Is flowing through the battery 11 internally short-circuited by the short-circuit member 15 based on the following formula (4). In the following formula (4), the internal short-circuit current Is is described by the electromotive force E of the battery 11, the internal resistance value Ri, and the internal short-circuit resistance value Rs. The electromotive force E at the time of the internal short circuit of the battery 11 is acquired based on the remaining capacity and temperature of the battery 11 as described later. The internal resistance value Ri of the battery 11 is obtained based on the remaining capacity and temperature of the battery 11 as described later.

For example, when sequentially calculating the internal short-circuit current Is, the processing device 17 uses the internal short-circuit resistance value _Rsn acquired in the current process and the current electromotive force E acquired in the previous process as described later. The current internal short-circuit current _{Isn is} calculated based on _n and the internal resistance Rin.

<Calculation of Dischargeable Capacity Qeff>
A method for calculating the dischargeable capacity Qeff of the battery 11 short-circuited by the short-circuit member 15 will be described below.
FIG. 5 is a cross-sectional view showing the short-circuit member 15 and a plurality of cylindrical body regions of the cylindrical heat transfer model in the short-circuited cell capacity estimation method according to the embodiment. FIG. 6 is a graph showing an example of temperature data (temperature change data of a plurality of cylindrical regions) acquired by a cylindrical heat transfer model in the short-circuited cell capacity estimation method according to the embodiment. FIG. 7 is a graph showing an example of the correspondence relationship between the discharge capacity and the test temperature obtained by the discharge test of the battery 11 in the method for estimating the short-circuited cell capacity according to the embodiment.

The processing device 17 acquires data (temperature data) of changes in internal temperature over time using a cylindrical heat transfer model for the battery 11 short-circuited by the short-circuit member 15 . As shown in FIG. 5, the cylindrical heat transfer model models the battery 11 short-circuited by the short-circuit member 15 as a cylindrical body 40 centered on the short-circuit member 15 . The volume of the cylindrical body 40 is the same as the volume of the battery 11 . The cylinder 40 is segmented into a plurality of concentric cylinder regions. The radial thickness H of each of the multiple cylindrical regions is the same. The plurality of cylindrical body regions include a short circuit region 41 in contact with the short circuit member 15 and a plurality of cylindrical bodies 42(1), . Prepare. Note that m is a predetermined natural number. The short-circuit region 41 generates heat due to the short-circuit. The heat generated in the short-circuit region 41 is transmitted to the short-circuit member 15 and the plurality of cylindrical bodies 42(1), . . . , 42(m).

The processor 17 calculates the amount of heat Pp transferred from the short-circuit region 41 to the short-circuit member 15 based on the temperature Tp of the short-circuit member 15 detected by the temperature sensor 15a and the following formula (5). In the following formula (5), the temperature Tp of the short-circuit member 15 is the amount of heat Pp transferred from the short-circuit region 41 to the short-circuit member 15, the time interval Δt, the specific heat Cp of the short-circuit member 15, and the weight of the short-circuit member 15. Mp.

The processing device 17 calculates the temperature Ts of the short-circuit region 41 based on the calculated amount of heat Pp and the following formula (6). In the following formula (6), the amount of heat Pp transferred from the short-circuit region 41 to the short-circuit member 15 is a predetermined natural number m, the thermal conductivity λs of the short-circuit region 41, the temperature Ts, the radial thickness H, and the radius Ls. , and the radius Lp of the short-circuit member 15 .

The processor 17 describes the amount of heat P1 transferred from the short circuit region 41 to the first cylindrical body 42( ₁ ) as shown in the following formula (7). In the following formula (7), the heat quantity P1 is _a predetermined natural number m, the thermal conductivity λs of the short circuit region 41, the temperature Ts, the radial thickness H and the radius Ls, and the first cylindrical body 42(1) is described by the temperature T ₁ , radial thickness H and radius Ls ₁ of the second cylinder 42(2) and the temperature T ₂ and radius Ls ₂ of the second cylinder 42(2).

The processor 17 describes the amount of heat _Pk transferred from the short-circuit region 41 to the k-th cylindrical body 42(k) as shown in the following formula (8). Note that k is an arbitrary natural number equal to or greater than 2 and equal to or less than (m−1). In the following formula (8), the heat quantity P _k is a predetermined natural number m, the thermal conductivity λs of the short-circuit region 41, the temperature T _k-1 of the k-1-th cylindrical body 42 (k-1), and the radius Ls _k−1 , the temperature T _k , the radial thickness H and the radius Lsk of the _kth cylinder 42(k), and the temperature Tk ₊₁ and the radius Lsk _{+1 of the k+} 1th cylinder 42(k+1). ing.

The processor 17 describes the temperature Tj of the _j -th cylindrical body 42(j) as shown in the following formula (9). Note that j is an arbitrary natural number equal to or less than a predetermined natural number m. Note that, in the following formula (9), the temperature Tj is the amount of heat Pj transferred from the short-circuit region 41 to the _j -th cylindrical body 42( _j ), the time interval Δt, and the j-th cylindrical body 42(j). is described by the specific heat Cc and weight Ms of

The processing device 17 uses the above formulas (5) to (9), the temperature Tp of the short-circuiting member 15 detected by the temperature sensor 15a provided on the short-circuiting member 15, and the temperature Tp detected by the temperature sensor (not shown). The temperature Tj of the _j -th cylindrical body 42(j) is calculated sequentially from the inner peripheral side to the outer peripheral side of the cylindrical body 40 by using the detected value of the surface temperature of the battery 11.

Note that the processing device 17 uses the above formulas (7) to (9), the detected value of the surface temperature of the battery 11 detected by a temperature sensor (not shown), and the temperature sensor 15a provided on the short circuit member 15. The temperature Tj of the _j -th cylindrical body 42(j) may be calculated sequentially from the outer peripheral side toward the inner peripheral side of the cylindrical body 40 using the detected value of the temperature Tp of the short circuit member 15 .
In this case, first, the processing device 17 uses the detected value of the surface temperature of the battery 11 as the temperature _Tm of the m-th cylindrical body 42 (m), which is the outermost layer of the cylindrical body 40, in the above equation (9). Then, the amount of heat Pm transferred from the short-circuit region 41 to the m-th cylindrical body 42( _m ) is calculated.
Next, the processing device 17 _determines the temperature _{T m -1} is calculated. Then, based on the temperature T _m−1 and the above formula (9), the processing device 17 determines the heat amount P _{m− 1} is calculated.
Next, the processing device 17 determines the ( _{m -} 2)th cylindrical body 42 ( _m -2 ) is _calculated . Then, based on the temperature T _m−2 and the above formula (9), the processing device 17 determines the heat amount P _{m− 2} is calculated.
The processing device 17 repeats the same process as that for calculating the temperature Tm-2 of the (m-2)th cylindrical body 42(m-2), thereby calculating the temperature _Tm-2 of the (m-3)th cylindrical body 42(m-2). , T ₁ are calculated sequentially from 42(m _- 3) toward the first cylindrical body 42(1).

As shown in FIG. 6, the processing device 17 acquires temperature data of changes in the calculated temperatures Tp, Ts, T ₁ , . . . , _Tm over time. For example, in FIG. 6, the temperature Tp of the short circuit member 15 and the temperatures T ₁ , . . . , T ₄ of the first to fourth cylindrical bodies 42(1), . It is recognized that there is an increasing trend.
The processing device 17 puts a region exceeding a predetermined temperature Ta in the obtained temperature data into a deactivated state in which discharge is impossible. The predetermined temperature Ta is, for example, 120.degree. For example, as shown in FIG. 7, the predetermined temperature Ta is set based on test results obtained by measuring the discharge capacity of the battery 11 at various test temperatures. According to the test results shown in FIG. 7, it is recognized that the discharge capacity decreases toward zero in the temperature range exceeding the predetermined temperature Ta.
The processing device 17 calculates the deactivated capacity Qdead by converting the volume of the deactivated region in the cylindrical body 40 into a capacity. The processing device 17 calculates the dischargeable capacity Qeff by subtracting the deactivation capacity Qdead from the known initial capacity of the battery 11 . For example, when the processing device 17 sequentially calculates the dischargeable capacity Qeff, as shown in the following formula (10), the last remaining capacity Q _n-1 of the battery 11 until this time is newly deactivated. The current dischargeable capacity Qeff _n is calculated by subtracting the deactivation capacity Qdead _n . Note that n is an arbitrary natural number.

<Calculation of remaining capacity Q>
A method for calculating the remaining capacity Q of the battery 11 short-circuited by the short-circuit member 15 will be described below.
The processing device 17 calculates the remaining capacity Q by subtracting the discharge capacity from the dischargeable capacity Qeff. For example, when the processing device 17 sequentially calculates the remaining capacity Q, as shown in the following formula (11), the current dischargeable capacity Qeff _n of the battery 11 is newly discharged from the previous time to the current time. The current remaining capacity _Qn is calculated by subtracting the lost discharge capacity. A new discharge capacity from the previous time to the current time is calculated by time-integrating the current internal short-circuit current _Isn over the elapsed time t from the previous time to the current time.

<Acquisition of internal resistance value Ri and electromotive force E>
A method of obtaining the internal resistance value Ri and the electromotive force E of the battery 11 short-circuited by the short-circuit member 15 will be described below.
FIG. 8 is a graph showing an example of the correspondence relationship among the internal resistance value, temperature, and capacity of the battery 11 in the short-circuited cell capacity estimation method according to the embodiment. FIG. 9 is a graph showing an example of the correspondence relationship between the electromotive force and the capacity of the battery 11 in the short-circuited cell capacity estimation method according to the embodiment.

As shown in FIG. 8, the processing device 17 stores in advance a map of the correspondence between the internal resistance value, temperature, and remaining capacity of the battery 11 . The map shown in FIG. 8 shows the correspondence relationship between the internal resistance value and temperature in each of the plurality of different remaining capacities Q ₁ , . . . , Q ₈ . For example, in FIG. 8, it can be seen that the internal resistance values of the remaining capacities Q ₁ , . . . , Q ₈ tend to decrease as the temperature increases.
The processing device 17 determines the correspondence between the internal resistance value, the temperature, and the remaining capacity of the battery 11 based on the remaining capacity Q calculated for the battery 11 internally short-circuited by the short-circuit member 15 and the detected value of the surface temperature of the battery 11. , the internal resistance value Ri corresponding to the detected value of the remaining capacity Q and the surface temperature is obtained.
For example, when calculating the remaining capacity _Qn successively, the processing device 17 acquires the internal resistance value Rin ₊₁ until the next time based on the remaining capacity _Qn calculated this time.

As shown in FIG. 9, the processing device 17 stores in advance a map of the correspondence between the electromotive force, temperature, and remaining capacity of the battery 11 . The map shown in FIG. 9 shows the correspondence relationship between the electromotive force and the remaining capacity at an appropriate temperature (for example, 25° C.). For example, in FIG. 9, it can be seen that the electromotive force tends to increase as the remaining capacity increases.
The processing device 17 determines the correspondence between the electromotive force, the temperature, and the remaining capacity of the battery 11 based on the remaining capacity Q calculated for the battery 11 internally short-circuited by the short-circuit member 15 and the detected value of the surface temperature of the battery 11. By referring to the map, the remaining capacity Q and the electromotive force E corresponding to the detected surface temperature are obtained. When the temperature dependence of the electromotive force and the remaining capacity can be ignored, the processing device 17 calculates the electromotive force corresponding to the remaining capacity Q based on the map of the correspondence relationship between the electromotive force and the remaining capacity at an appropriate temperature. You can get E.
For example, when calculating the remaining capacity _Qn successively, the processing device 17 acquires the electromotive force _En+1 until the next time based on the remaining capacity _Qn calculated this time.

<Calculation of Joule heat>
A method for calculating Joule heat and chemical reaction heat of the battery 11 short-circuited by the short-circuit member 15 will be described below.
The processing device 17 calculates a predetermined work Wj obtained by integrating the internal short-circuit current Is calculated for the battery 11 internally short-circuited by the short-circuit member 15 and the terminal voltage V of the battery 11 detected by the voltage sensor 13. The Joule heat (∫Wj·dt) is calculated by time integration over time.
The processing device 17 calculates the amount of heat generation (∫Wc·dt) by time-integrating the amount of heat Wc of the battery 11 detected by the heat amount sensor 14 over a predetermined period of time.
The processing device 17 converts the Joule heat (∫Wj dt) from the calorific value (∫Wc dt) based on the Joule heat (∫Wj dt), the calorific value (∫Wc dt), and the following formula (12). The heat of chemical reaction (∫Wchem·dt) obtained by subtracting is calculated.

<Method for estimating internal short-circuit current and short-circuit cell capacity>
A method of sequentially measuring the internal short-circuit state quantity of the battery 11 short-circuited by the short-circuit member 15 will be described below.
FIG. 10 is a flow chart of a method for estimating an internal short-circuit current and a short-circuit cell capacity according to the embodiment. The processing device 17 repeatedly executes a series of processes from step S01 to step S06 at predetermined time intervals. The predetermined time is, for example, approximately 1 ms to 10 ms.
First, in step S01, the processing device 17 refers to a pre-stored map of the short-circuit resistance value and the voltage drop speed based on the data of the voltage drop speed due to the terminal voltage V of the battery 11 detected by the voltage sensor 13. to acquire the internal short-circuit resistance value _Rsn of the battery 11 in the current process.

Next, in step S02, the processing device 17 converts the electromotive force _En and the internal resistance value Rin of the battery 11 obtained in the previous process, the internal short-circuit resistance value _Rsn calculated in step _S01 , and the above formula (3 ), the internal short-circuit current _Isn in the current process is calculated.
Next, in step S03, based on the temperature data obtained by the cylindrical heat transfer model, the processing device 17 is in a deactivation state in which the cylindrical body 40 newly reaches a predetermined temperature Ta or higher from the previous processing to the current processing. get the area of The processing device 17 calculates the deactivated capacity Qdead _n of the battery 11 in the current process by converting the volume of the newly deactivated region into a capacity. The processing device 17 calculates the dischargeable capacity Qeff _n of the battery 11 in the current process by subtracting the current deactivation capacity Qdead _n from the remaining capacity Q _n−1 calculated in the previous process.

Next, in step S04, the processing device 17 calculates the discharge capacity by time-integrating the internal short-circuit current _Isn calculated in step S02 over the elapsed time t from the previous processing to the current processing. The processing device 17 calculates the current remaining capacity _Qn by subtracting the discharge capacity from the dischargeable capacity _Qeffn calculated in step S03.
Next, in step S05, the processing device 17 determines whether or not the remaining capacity Qn calculated in step _S04 is equal to or less than a predetermined capacity. The predetermined capacity is, for example, zero.
If the determination result is "YES", the processor 17 advances the process to the end. On the other hand, if the determination result is "NO", the processing device 17 advances the process to step S06.

Next, in step S06, the processing device 17 creates a map of the correspondence between the internal resistance value, temperature, and remaining capacity of the battery 11 based on the remaining capacity Qn calculated in step _S04 and the detected surface temperature of the battery 11. By referring to it, the internal resistance value Rin ₊₁ until the next processing is acquired. In addition, the processing device 17 refers to the map of the correspondence between the electromotive force, the temperature and the remaining capacity of the battery 11 based on the remaining capacity _Qn and the detected value of the surface temperature of the battery 11 calculated in step S04. Obtain the electromotive force _En+1 up to the processing of . Then, the processing device 17 returns the processing to step S01.

As described above, according to the method of estimating the internal short-circuit current and the method of estimating the short-circuited cell capacity of the present embodiment, based on the fact that the equivalent circuit is the same for the internal short-circuit and the external short-circuit of the battery 11, By referring to the map of the correspondence relationship between the voltage drop of the external resistor 32 and the resistance value R acquired by , the internal short-circuit resistance value Rs corresponding to the voltage drop detected at the time of the internal short-circuit is acquired. As a result, even if the proper internal resistance value Ri and internal short-circuit resistance value Rs at the time of an internal short circuit cannot be directly detected, an irregular resistance corresponding to heat generation at the time of an internal short circuit or damage due to generated gas can be detected. An appropriate internal short-circuit resistance value Rs can be obtained indirectly based on the voltage behavior including changes in internal states.
Also, using the internal short-circuit current Is calculated based on the internal short-circuit resistance value RS, the Joule heat at the time of the internal short-circuit can be calculated. As a result, in the total amount of heat generated at the time of an internal short circuit, Joule heat can be grasped by distinguishing it from chemical reaction heat such as heat generated due to internal combustion and decomposition, for example.

Also, the remaining capacity is calculated based on the deactivation capacity and discharge capacity at the time of internal short circuit. As a result, the calculation accuracy of the appropriate remaining capacity Q can be improved.
In addition, by regarding the region of the battery 11 above a predetermined temperature as deactivated, the deactivated capacity associated with damage to the cell 19 caused by heat generation during an internal short circuit can be properly calculated, and the remaining capacity calculation accuracy can be improved. be able to.
Further, the discharge capacity can be calculated with high accuracy based on the internal short-circuit current Is that locally flows in the battery 11 during an internal short-circuit.

Further, since the internal resistance value Ri is obtained based on the remaining capacity in consideration of the deactivation and discharge of the battery 11 at the time of internal short circuit, the accuracy of the internal resistance value Ri can be improved.
Further, since the electromotive force E is obtained based on the remaining capacity in consideration of the deactivation and discharge of the battery 11 at the time of internal short circuit, the accuracy of the electromotive force E can be improved.
Further, the calculation accuracy of the internal short-circuit current Is can be improved by the internal resistance value Ri and the electromotive force E based on the remaining capacity Q in consideration of the deactivation and discharge at the time of the internal short circuit.
Further, by successively calculating the remaining capacity _Qn of the battery 11 at the time of internal short circuit, it is possible to improve the quantitative evaluation accuracy of short circuit characteristics and short circuit behavior.

Modifications of the above embodiment will be described below.
In the embodiment described above, the battery 11 includes a plurality of cells 19, but is not limited to this and may include only a single cell 19. FIG.
In the above-described embodiments, the configuration of the short-circuit test device 10 is not limited to the above, and other configurations may be used.

Embodiments of the invention are provided by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, as well as the scope of the invention described in the claims and equivalents thereof.

DESCRIPTION OF SYMBOLS 10... Short circuit test apparatus 11... Battery (cell) 13... Voltage sensor 14... Heat sensor 15... Short circuit member 16... Thermal insulation member 17... Processing apparatus 19... Cell 31... Internal short circuit resistance 32... External resistance 33 Internal resistance 40 Cylindrical body 41 Short-circuit region (cylindrical region) 42 (1), 42 (m) Cylindrical body (cylindrical region) E Electromotive force Is Internal short-circuit current, R... Resistance value, Ri... Internal resistance value, Rs... Internal short-circuit resistance value, Qeff... Dischargeable capacity, Q... Remaining capacity

Claims (3)

data of changes in voltage drop over time detected in a cell internally shorted by a short tester; and the external resistance detected in a closed circuit comprising the cell and an external resistance connected to the cell. obtaining an internal short-circuit resistance value of the cell from a map of the correspondence relationship between changes in voltage drop over time and the resistance value of the external resistor;
and calculating an internal short-circuit current I that flows when the cell is internally short-circuited, based on the following formula (1) using the electromotive force E of the cell, the internal resistance value Ri, and the internal short-circuit resistance value Rs. Estimation method of internal short-circuit current.

a shorted cell capacity calculation step of calculating the remaining capacity of the cell at the time of the internal short circuit by subtracting the deactivated capacity due to the internal short circuit of the cell and the discharge capacity accompanying the discharge of the cell from the initial capacity of the cell; ,
When calculating the remaining capacity successively when the cell is internally short-circuited, the previous value Q _n-1 of the remaining capacity and the deactivation of the cell over the period from the previous calculation of the remaining capacity to the current calculation of the remaining capacity Calculate the current value Q _n of the remaining capacity based on the following formula (2) by the deactivation capacity Qdead _n accompanying the discharge of the cell over the period and the discharge capacity Qdis _n accompanying the discharge of the cell over the period,

Temperature data of changes in the temperature of each of the cylindrical regions over time when the cell is divided into a plurality of concentric cylindrical regions centered on the internal short-circuited portion of the cell. a temperature data acquisition step of acquiring based on a temperature detection value output from a temperature sensor provided in a short circuit member for internally short-circuiting the cell;
a deactivation capacity calculating step of calculating the deactivation capacity by regarding, based on the temperature data, the cylindrical body region in which the temperature reaches a predetermined temperature or higher among the plurality of cylindrical body regions as deactivation; including
In the temperature data acquisition step, the temperature of each of the cylindrical regions during the internal short circuit of the cell is determined by a cylindrical heat transfer model that models heat transfer from the internal short-circuit portion to each of the plurality of cylindrical regions. Get changes over time,
including a discharge capacity calculation step of calculating the discharge capacity by time integration of the internal short-circuit current of the cell;
An internal resistance value at the time of an internal short circuit of the cell based on a map of correspondence relationships among the internal resistance, temperature, and capacity of the cell, and the remaining capacity calculated by the short-circuited cell capacity calculating step and the temperature detected in the cell. including an internal resistance value acquisition step that acquires
an electromotive force acquisition step of acquiring an electromotive force at the time of an internal short circuit of the cell from a map of the correspondence relationship between the electromotive force and the capacity of the cell and the remaining capacity calculated by the shorted cell capacity calculating step;
data of changes over time in the voltage drop detected across the internally shorted cell and the voltage drop across the external resistor detected in a closed circuit comprising the cell and an external resistor connected to the cell an internal short-circuit resistance value acquisition step of acquiring an internal short-circuit resistance value of the cell based on a map of the correspondence relationship between the change over time and the resistance value of the external resistor;
The following formula (3) based on the electromotive force E obtained by the electromotive force obtaining step, the internal resistance value Ri obtained by the internal resistance value obtaining step, and the internal short-circuit resistance value Rs obtained by the internal short-circuit resistance value obtaining step and an internal short-circuit current calculating step of calculating an internal short-circuit current I based on.

When calculating the remaining capacity sequentially by the shorted cell capacity calculating step when the cell is internally short-circuited,
In the deactivation capacity calculation step, the deactivation capacity is calculated by the cylindrical region considered to be deactivated over a period from the previous calculation of the remaining capacity to the current calculation,
The discharge capacity calculating step includes the internal resistance value obtained by the internal resistance value obtaining step based on the previous value of the remaining capacity and the electromotive force obtaining step based on the previous value of the remaining capacity. 3. The short-circuited cell according to claim 2 , wherein the discharge capacity is calculated by time-integrating the internal short-circuit current calculated by the internal short-circuit current calculation step using the electromotive force over the period. Capacity estimation method.

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