JP2004028861A - Method and detector for detecting voltage in batteries connected in parallel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To estimate a release voltage in each of unit cells connected in parallel. <P>SOLUTION: Cells of a parallel battery connected with n number of cells C11-C1n, a parallel battery connected with n number of cells C21-C2n, and batteries up to a parallel battery connected with n number of cells Cm1-Cmn are connected respectively in series to constitute a battery module BM. A current flowing in the each cell is detected by a current sensor 102, and a terminal voltage in each of the parallel batteries detected by a voltage sensor 103. Each detected value is transmitted from a cell controller 10 to a battery controller 20 to be accumulated in a memory 202 of the battery controller 20. A CPU 201 calculates an internal resistance value in the each cell using current values and voltage values accumulated in the memory 202 by the plurality of measurements. The CPU 201 calculates a release voltage value using the internal resistance value of the cell, the voltage under a load by the voltage sensor 103, and the current value in the cell by the current sensor 102. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a voltage detection method and a voltage detection device for batteries connected in parallel.
[0002]
[Prior art]
2. Description of the Related Art A technology for driving a load using a rechargeable secondary battery as a power source, such as an electric vehicle, is known. The battery repeatedly performs a discharging operation for driving the load and a charging operation for charging the battery. The open-circuit voltage at the time of discharging and the open-circuit voltage at the time of charging of such a battery are controlled so as to fall within a voltage range indicated by a lower voltage limit and an upper limit value when the battery is used. As a method of detecting the open voltage of a battery, a method of linearly regressing the IV characteristic based on a terminal voltage V and a discharge current I measured during discharging of the battery has been proposed (for example, Japanese Patent Application Laid-Open No. 2000-261901). Such). Generally, in a lithium ion battery or a nickel hydride battery, when the depth of discharge (DOD) of the battery is within a predetermined region (for example, 0 to 60%), the internal resistance at the time of charging and the internal resistance at the time of discharging substantially match, and Good linearity of IV characteristics. Therefore, the terminal voltage V measured during battery discharge is plotted on the vertical axis, and the discharge current I is plotted on the horizontal axis, and a regression line is obtained from the obtained IV characteristics. When this regression line is extended to the discharge-side region and the charge-side region, the V-axis intercept represents the open circuit voltage of the battery.
[0003]
[Problems to be solved by the invention]
There is a demand to use a battery in which a plurality of secondary cells are connected in parallel for the power supply. When batteries are connected in parallel, current flows from the battery with the higher voltage to the battery with the lower voltage. This current is called an adjustment current and flows so as to match the terminal voltage between the batteries. Therefore, even if the terminal voltages of the parallel cells in which the cells are connected in parallel are measured, the actual open voltage of each cell is not known, and it is difficult to obtain the open voltages of the individual cells by the conventional method.
[0004]
An object of the present invention is to detect a voltage by obtaining an open-circuit voltage for each unit cell connected in parallel.
[0005]
[Means for Solving the Problems]
The present invention relates to voltage detection of a battery in which a plurality of secondary cells are connected in parallel, and detects the voltage of a parallel battery and the current of each cell a plurality of times, respectively, and detects the internal voltage of each cell from the detected voltage and current. The resistance is calculated, and the open voltage of the cell is estimated and obtained using the calculated internal resistance, the voltage of the parallel cell, and the current of each cell.
[0006]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the open circuit voltage for every unit cell of a parallel connection battery can be obtained.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram of an assembled battery voltage monitoring system according to an embodiment of the present invention. The present system is mounted on an electric vehicle or the like using a battery pack as a power source. In FIG. 1, the voltage monitoring system has a voltage sensor 103, a current sensor 102, a cell controller 10, and a battery controller 20.
[0008]
In the battery module BM, n cells C11 to C1n, n cells C21 to C2n,..., N cells Cm1 to Cmn are respectively connected in parallel. A parallel battery composed of cells C11 to C1n is referred to as C (P1). Similarly, a parallel battery composed of cells C21 to C2n is represented as C (P2), and a parallel battery composed of cells Cm1 to Cmn is represented as C (Pm). The parallel batteries C (P1), C (P2),..., And C (Pm) are connected in series to form a battery module BM. The assembled battery is configured using a plurality of sets of the battery module BM described above. The number n of cells in the parallel battery and the number m of parallel batteries connected in series are appropriately set according to the specifications of the battery module BM. FIG. 1 is a diagram showing only one battery module BM among the battery modules BM constituting the battery pack.
[0009]
The current sensor 102 and the voltage sensor 103 are provided corresponding to each battery module BM. The current sensor 102 detects a current flowing through each of the m × n cells constituting the battery module BM, and outputs a detection signal to the cell controller 10. The voltage sensor 103 detects the terminal voltages of the m sets of parallel batteries C (P1), C (P2),..., And C (Pm), and outputs a detection signal to the cell controller 10.
[0010]
The cell controllers 10 are provided corresponding to the respective battery modules BM. The cell controller 10 has a CPU 101 and a battery temperature sensor 104, and manages m × n cells in the module battery BM. The CPU 101 obtains the current value of each cell from the current detection signal from the current sensor 102, and sends current information for each cell to the battery controller 20. The CPU 101 further obtains a terminal voltage value of the parallel batteries from the voltage detection signal from the voltage sensor 103, and sends voltage information for each parallel battery to the battery controller 20. The battery temperature sensor 104 detects the temperature of a cell in the battery module BM, and sends a temperature detection signal to the CPU 101. The CPU 101 obtains the cell temperature based on the detection signal from the battery temperature sensor 104, and sends the cell temperature information to the battery controller 20.
[0011]
The cell controller 10 is managed by the battery controller 20. Battery controller 20 includes CPU 201, memory 202, and communication unit 203. The communication unit 203 communicates with each cell controller by serial communication. The battery controller 20 transmits a command to each cell controller by serial communication, receives voltage information, current information, and temperature information transmitted from each cell controller by serial communication, and manages each battery module based on the received information. I do.
[0012]
The CPU 201 of the battery controller 20 sequentially stores (accumulates) voltage information, current information, and temperature information from each cell controller input via the communication unit 203 in the memory 202. The CPU 201 calculates the discharge capacity, the charge capacity, and the like of the battery module BM using the information stored in the memory 202, and transmits the calculation result to a vehicle controller (not shown) as battery information. The battery information also includes an output / regeneration restriction request. When abnormal data is sent from the cell controller 10 to the battery controller 20, the CPU 201 performs a fail-safe operation such as output / regeneration restriction.
[0013]
Information indicating the deterioration characteristics of the battery is stored in the memory 202 in advance. The stored information includes, for example, a temperature correction coefficient A and a battery voltage correction coefficient B. The temperature correction coefficient A is a parameter indicating a change in the internal resistance of the battery depending on the temperature. Generally, the internal resistance of a battery decreases with increasing battery temperature. Therefore, the relationship between the temperature and the internal resistance is actually measured and tabulated, and a table reference value corresponding to the temperature is stored in the memory 202 as the temperature correction coefficient A. FIG. 2 is an example of a graph showing a correlation between a battery temperature and an internal resistance value.
[0014]
The battery voltage correction coefficient B is a parameter indicating a change in the internal resistance of the battery depending on the battery voltage. Generally, the internal resistance of a battery increases as the battery voltage decreases due to the discharge of the battery. Therefore, the relationship between the battery voltage and the internal resistance is actually measured and tabulated, and a table reference value corresponding to the battery voltage is stored in the memory 202 as the battery voltage correction coefficient B. FIG. 3 is an example of a graph showing a correlation between a battery voltage and an internal resistance value. In FIG. 3, the guaranteed voltage upper limit corresponds to the voltage when the battery is fully charged. The guaranteed voltage lower limit value corresponds to the discharge stop (end) voltage of the battery.
[0015]
The vehicle controller (not shown) transmits the battery information transmitted from the above-described battery controller 20 and the respective detection values obtained by the accelerator operation amount sensor (not shown), the brake operation amount sensor (not shown), and the vehicle speed sensor (not shown). Is used to control the running of the vehicle.
[0016]
The present invention has a feature in the calculation of battery information performed in the voltage monitoring system of the assembled battery, and particularly, the open-circuit voltage of each cell is estimated from the internal resistance value of each cell constituting the parallel battery. Things.
[0017]
FIG. 4 is a flowchart illustrating the flow of the cell monitoring process performed by the CPU 201. The process shown in FIG. 4 is repeatedly performed when the vehicle is running (when the battery module BM is discharged) and when the battery module BM is charged. In step S11 in FIG. 4, the CPU 201 calculates a deterioration rate of the battery characteristics. The CPU 201 uses the current value of each cell based on the current information stored in the memory 202, the terminal voltage value of each parallel battery based on the voltage information, the cell temperature based on the temperature information, and the information indicating the battery deterioration characteristics. The deterioration rate is calculated, and the calculation result is stored (accumulated) in the memory 202. After storing the calculation result in the memory 202, the CPU 201 proceeds to step S12. The details of the calculation of the battery characteristic deterioration rate will be described later.
[0018]
In step S12, the CPU 201 refers to the current value of each cell stored in the memory 202, the terminal voltage value of each parallel battery, the battery characteristic deterioration rate, and the table reference value previously stored in the memory 202. The internal resistance value of each cell is calculated, and the calculation result is stored (stored) in the memory 202. After storing the calculation result in the memory 202, the CPU 201 proceeds to step S13.
[0019]
The calculation of the internal resistance will be described. FIG. 5 is a diagram illustrating the voltage behavior at the time of discharging a single cell. In FIG. 5, the horizontal axis represents elapsed time (sec), and the vertical axis represents terminal voltage (V) of the cell. When the cell starts discharging, the load voltage V1 gradually decreases from the open voltage V0, and the rate of decrease changes near the broken line in FIG. Therefore, the CPU 201 uses the data after the rate of decrease of the load voltage among the current value of each cell and the terminal voltage value of each parallel battery stored in the memory 202 according to the following equation (1). Calculate the resistance value r.
(Equation 1)
V1 = V0−I × r (1)
Here, V1 is a load voltage value, V0 is an open voltage value, I is a current value flowing through the cell, and r is an internal resistance value of the cell. The open-circuit voltage value V0 is given as a detected voltage value when the current value I = 0.
[0020]
FIG. 6 is a diagram illustrating voltage behavior during charging of a single cell. In FIG. 6, the horizontal axis represents elapsed time (sec), and the vertical axis represents cell voltage (V). The load voltage V1 gradually increases from the open voltage V0 when the cell starts charging, and the rate of increase changes near the broken line in FIG. Therefore, the CPU 201 uses the data obtained after the rate of increase of the load voltage among the current values of each cell and the terminal voltage value of each parallel battery stored in the memory 202 according to the above equation (1). Calculate the resistance value r.
[0021]
The CPU 201 corrects the calculated internal resistance value r of each cell with reference to the battery characteristic deterioration rate stored in the memory 202 and the above-mentioned table reference value stored in the memory 202, and calculates the corrected internal resistance value. The value rc is stored in the memory 202.
[0022]
In step S13, the CPU 201 determines the open-circuit voltage for each cell using the corrected internal resistance value rc for each cell, the current value for each cell, and the terminal voltage value for each parallel battery stored in the memory 202. Each is calculated, and the calculation result is stored (stored) in the memory 202. After storing the calculation result in the memory 202, the CPU 201 proceeds to step S14.
[0023]
In step S14, the CPU 201 performs monitoring processing so that the open-circuit voltage of each cell stored in the memory 202 does not deviate from the operating temperature range (guaranteed temperature range) of the battery. The CPU 201 repeats the processing of steps S11 to S14 when the vehicle runs and when the battery is charged. The details of the open voltage monitoring process will be described later.
[0024]
Next, details of the calculation of the battery characteristic deterioration rate in step S11 in FIG. 4 will be described with reference to the flowchart in FIG. In step S21 of FIG. 7, the CPU 201 uses the current value of each cell based on the current information stored in the memory 202, the voltage value of each parallel battery based on the voltage information, and the cell temperature based on the temperature information to determine the cycle deterioration rate. Is calculated, and the calculation result is stored (stored) in the memory 202.
[0025]
The cycle deterioration rate indicates a change in the internal resistance of the battery caused by the charge / discharge cycle of the battery. Generally, the internal resistance of a battery increases as the number of charge / discharge cycles of the battery increases. Therefore, the CPU 201 calculates the number of charge / discharge cycles from the current value and the voltage value stored in the memory 202, and calculates the relationship of the number of charge / discharge cycles-the amount of increase in internal resistance, that is, the cycle deterioration rate. Current flowing out of the battery indicates battery discharge. The current flowing into the battery indicates the charging of the battery. When the voltage decrease due to the battery discharge and the voltage increase due to the battery charge are counted as one cycle, the number of charge / discharge cycles can be obtained. Since the internal resistance value of the battery differs depending on the temperature of the battery where charging and discharging are repeated, the internal resistance value r is corrected using the detected cell temperature. The temperature correction is performed with reference to the temperature correction coefficient A. After accumulating the calculation result of the cycle deterioration rate in the memory 202, the CPU 201 proceeds to step S22. FIG. 8 is an example of a graph showing a correlation between the calculated number of charge / discharge cycles and the increase in internal resistance.
[0026]
In step S22, the CPU 201 calculates the storage deterioration rate using the voltage value and the cell temperature of each parallel battery detected at the start of charging or at the start of discharging (vehicle running), and stores the calculation result in the memory 202. ).
[0027]
The storage deterioration rate indicates a change in the internal resistance of the battery due to the length of time the battery has not been charged or discharged. In general, the internal resistance of a battery increases as the standing time of the battery increases. Therefore, the CPU 201 obtains the storage period (number of days) from the voltage value and the temperature detected after the battery is left, and calculates the relationship between the storage period and the increase in the internal resistance, that is, the storage deterioration rate. The battery voltage when the battery is left has a predetermined rate of change depending on the battery voltage depending on the state of charge (SOC) of the battery and the battery temperature when the battery is left. Can be calculated from the battery voltage and the temperature at the time when the operation is started). After accumulating the calculation result of the storage deterioration rate in the memory 202, the CPU 201 proceeds to step S23. FIG. 9 is an example of a graph showing a correlation between the calculated storage period (number of days) and the amount of increase in internal resistance. Instead of detecting the cell temperature after the battery is left, the cell temperature may be detected at predetermined time intervals while the battery is left using a timer circuit (not shown) in the CPU 201. In this case, the standing time of the battery can be calculated in consideration of the temperature fluctuation during the standing.
[0028]
In step S23, the CPU 201 calculates the characteristic deterioration rate using the cycle deterioration rate and the storage deterioration rate stored in the memory 202. The characteristic deterioration rate is expressed as a relationship between the battery usage days and the internal resistance increase amount by integrating the internal resistance increase amount of the battery due to both the cycle deterioration rate and the storage deterioration rate. For example, when the number of charge / discharge cycles is 10 and the internal resistance increases by 1Ω, and when the storage period increases by 10Ω and the internal resistance increases by 1Ω, the conversion rate is calculated as 10 cycles = 10 days. Used. FIG. 10 is an example of a graph showing the correlation between the number of days of battery usage after conversion and the amount of increase in internal resistance.
[0029]
Details of the open-circuit voltage monitoring process will be described with reference to the flowchart in FIG. The CPU 201 receives the voltage information (the voltage value when the parallel battery is loaded) input via the communication unit 203, and proceeds to step S42. In step S42, the CPU 201 determines whether the on-load voltage value V1 is within the first allowable voltage range. The first allowable voltage range is stored in the memory 202 in advance. When the on-load voltage value V1 is within the first allowable voltage range, the CPU 201 makes an affirmative determination in step S42 and proceeds to step S43. When the on-load voltage value V1 is outside the first allowable voltage range, the CPU 201 proceeds to step S43. A negative determination is made in S42, and the process proceeds to step S49.
[0030]
In step S43, the CPU 201 reads the corrected internal resistance value rc of each cell stored in the memory 202, and proceeds to step S44. In step S44, the CPU 201 calculates the theoretical current value It for each cell using the read internal resistance value rc and the load voltage V1 using the following equation (2), and proceeds to step S45.
(Equation 2)
It = V1 / rc (2)
[0031]
In step S45, the CPU 201 receives current information (actual current value Ir of each cell) input via the communication unit 203, and proceeds to step S46. In step S46, the CPU 201 determines whether or not the theoretical current value It and the actual current value Ir have the same sign. The CPU 201 makes an affirmative determination in step S46 when the two current values have the same sign (the flowing directions are the same) and ends the processing in FIG. 11, and ends the processing in step S46 when the both current values have the different signs (the flowing directions are opposite). Is determined negatively and the process proceeds to step S47.
[0032]
When the two current values have the same sign, all the cells constituting the parallel battery are discharged when the parallel battery is discharged, or all the cells constituting the parallel battery are charged when the parallel battery is charged. is there. At this time, the CPU 201 regards the cell as normal. On the other hand, when the two current values have opposite signs, one of the cells constituting the parallel battery is charged at the time of discharging the parallel battery, or one of the cells constituting the parallel battery is charged at the time of charging the parallel battery. This is the case of discharging. At this time, the CPU 201 proceeds to step S47 to check the open-circuit voltage value of the cell.
[0033]
In step S47, the CPU 201 estimates the open-circuit voltage value V0e by substituting the internal resistance value rc and the actual current value Ir into the above equation (1) for the cell for which the sign of the current value is determined to be the opposite sign. Proceed to. In step S48, the CPU 201 determines whether or not the estimated open circuit voltage value V0e is within the second allowable voltage range. The second allowable voltage range is represented by an upper limit value and a lower limit value of the guaranteed voltage when the battery is used, and is stored in the memory 202 in advance. When the estimated open-circuit voltage value V0e is within the second allowable voltage range, the CPU 201 makes an affirmative determination in step S48 and ends the process in FIG. 11, and the estimated open-circuit voltage value V0e is out of the second allowable voltage range. In this case, a negative determination is made in step S48, and the process proceeds to step S49.
[0034]
When the estimated open-circuit voltage value V0e is within the second allowable voltage range, the CPU 201 regards the cell as normal. On the other hand, when the estimated open-circuit voltage value V0e is out of the second allowable voltage range, the CPU 201 regards the cell as abnormal and performs a process when an abnormality occurs in step S49. In step S49, the CPU 201 issues a command to display a cell abnormality on a display device (not shown), and ends the processing in FIG.
[0035]
The embodiments described above are summarized.
(1) A parallel battery C (P1) in which the single cells C11 to C1n are connected in parallel, a parallel battery C (P2) in which the single cells C21 to C2n are connected in parallel,..., The single cells Cm1 to Cmn are connected in parallel The parallel battery C (Pm) is connected in series to form a battery module BM.
(2) The current flowing through each single cell is detected by the current sensor 102, and the terminal voltage of each parallel battery is detected by the voltage sensor 103. Each detected value is sent from the cell controller 10 to the battery controller 20 and stored in the memory 202 of the battery controller 20. The CPU 201 of the battery controller 20 calculates the internal resistance value r of each cell using the current value and the voltage value of each cell stored in the memory 202 by a plurality of measurements. Since the current flowing through each cell is detected by the current sensor 102, the internal resistance value r of each cell can be calculated.
[0036]
(3) The CPU 201 corrects the calculated internal resistance value r of each cell by referring to the battery characteristic deterioration rate stored in the memory 202 and the table reference value stored in advance in the memory 202, and Is stored in the memory 202. The battery characteristic deterioration rate is obtained by integrating the amount of increase in the internal resistance of the battery caused by the number of charge / discharge cycles of the battery and the amount of increase in the internal resistance of the battery caused by the time (days) of the battery. The table reference value corrects a change in the battery internal resistance depending on the battery temperature and a change in the battery internal resistance depending on the battery voltage. By correcting the internal resistance value r calculated in the above (2), it is possible to obtain the internal resistance value rc from which the variation of the internal resistance value due to the use state of the battery is removed.
[0037]
(4) The CPU 201 determines whether or not the on-load voltage value V1 of the parallel battery is within the first allowable voltage range (step S42). It was determined whether or not the direction of the actual current flowing through each cell coincided with the direction of the theoretical current value (step S46). The theoretical current value is obtained by dividing the on-load voltage value V1 of the parallel battery by the internal resistance value rc. Thereby, it is possible to detect a case where any of the cells constituting the parallel battery is charged when the parallel battery is discharged, or a case where any of the cells constituting the parallel battery is discharged when the parallel battery is charged ( A negative determination is made in step S46).
[0038]
(5) For the cell corresponding to the negative determination in step S46 in the above (4), the CPU 201 estimates the open-circuit voltage value calculated using the load voltage V1, the internal resistance value rc of the cell, and the current value Ir of the cell. It is determined whether or not V0e is within the second allowable voltage range. If the estimated open-circuit voltage V0e deviates from the upper limit value and the lower limit value of the guaranteed voltage when the battery is used, this is detected and an abnormality is determined (step S49). As a result, the batteries can be used in an appropriate region so that the open-circuit voltage falls within the guaranteed voltage range for all the cells constituting the parallel battery, and the deterioration of the batteries can be prevented.
[0039]
The above (5) will be supplementarily described. FIG. 12 is a diagram illustrating a parallel battery in which two single cells C1 and two single cells C2 are connected in parallel. When a load is connected to the parallel battery, the parallel battery passes a current I to the load. The voltage sensor 103 in FIG. 1 detects a terminal voltage V under load. In a state where the SOC (charging state) of the single cell C1 is higher than the SOC of the single cell C2 and a capacity adjustment current flows from the single cell C1 to the single cell C2, a part of the current I1 of the single cell C1 flows to the single cell C2. Flows. When the adjustment current flows from the battery with the higher voltage to the battery with the lower voltage due to the variation in the voltage of the single cells in the parallel batteries, the open voltages of the two single cells take different values.
[0040]
FIG. 13 is a diagram showing the terminal voltage detected by the voltage sensor 103 over time and the open voltage of each single cell. In FIG. 13, the horizontal axis represents time, and the vertical axis represents voltage. The curve V indicates the terminal voltage (load voltage) of the parallel battery, the broken line V01 indicates the open voltage of the single cell C1, and the broken line V02 indicates the open voltage of the single cell C2. The internal resistance of the single cell C1 is r1, and the internal resistance of the single cell C2 is r2. FIG. 13 shows that the open-circuit voltage V02 of the single cell C2 may be lower than the guaranteed voltage lower limit even when the load voltage V of the parallel battery does not fall below the guaranteed voltage lower limit when the battery is used. The present invention monitors the open-circuit voltage of each cell so that the open-circuit voltage of a single cell having a lower cell voltage among the parallel batteries does not fall below the lower limit.
[0041]
Correspondence between each component in the claims and each component in the embodiment of the invention will be described. For example, cells C11 to Cmn correspond to the secondary cells. The parallel batteries include, for example, a parallel battery C (P1) in which cells C11 to C1n are connected in parallel, a parallel battery C (P2) in which cells C21 to C2n are connected in parallel,..., A parallel battery in which cells Cm1 to Cmn are connected in parallel. Battery C (Pm) corresponds. The information indicating the change in the internal resistance of the battery depending on the temperature corresponds to, for example, a table reference value of the temperature correction coefficient A. The information indicating the change in the internal resistance of the battery depending on the battery voltage corresponds to, for example, a table reference value of the battery voltage correction coefficient B. The voltage sensor corresponds to the voltage sensor 103, the current sensor corresponds to the current sensor 102, and the internal resistance calculator and the open-circuit voltage estimator correspond to the CPU 201. Note that each component is not limited to the above configuration as long as the characteristic functions of the present invention are not impaired.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an assembled battery voltage monitoring system that detects the assembled battery voltage by the method according to the present invention.
FIG. 2 is a diagram illustrating an example of a correlation between a battery temperature and an internal resistance value.
FIG. 3 is a diagram showing an example of a correlation between a battery voltage and an internal resistance value.
FIG. 4 is a flowchart illustrating a flow of a cell monitoring process performed by a CPU.
FIG. 5 is a diagram illustrating a voltage behavior during discharging of a single cell.
FIG. 6 is a diagram illustrating voltage behavior during charging of a single cell.
FIG. 7 is a flowchart illustrating details of calculation of a battery characteristic deterioration rate.
FIG. 8 is a diagram showing an example of a correlation between the number of charge / discharge cycles and the amount of increase in internal resistance.
FIG. 9 is a diagram showing an example of a correlation between the number of storage days and the amount of increase in internal resistance.
FIG. 10 is a diagram illustrating an example of a correlation between the number of days of battery use and the amount of increase in internal resistance.
FIG. 11 is a flowchart illustrating details of an open-circuit voltage monitoring process.
FIG. 12 is a diagram showing a parallel battery in which two single cells are connected in parallel.
FIG. 13 is a diagram showing a terminal voltage and an open-circuit voltage of each single cell detected over time.
[Explanation of symbols]
10: cell controller, 20: battery controller,
101, 201: CPU, 102: current sensor,
103: voltage sensor 104: battery temperature sensor
202: memory, 203: communication unit,
C11 to Cmn: cell, BM: battery module

Claims (8)

In a method of detecting a voltage of a battery in which a plurality of secondary cells are connected in parallel,
Detecting the voltage of the parallel battery,
Detecting the current of each cell,
Calculate the internal resistance of each of the single cells from the current and the voltage detected a plurality of times, respectively,
A voltage detection method for batteries connected in parallel, comprising estimating an open voltage of the cells using the internal resistance, the voltage of the cells in parallel, and the current of each cell. The method for detecting voltage of batteries connected in parallel according to claim 1,
Calculate the number of charge / discharge cycles of the parallel battery using the current detected multiple times and the voltage,
Calculating the correlation between the number of charge / discharge cycles and the increase in the internal resistance of the cell,
A method for detecting voltage of batteries connected in parallel, wherein the calculated internal resistance is corrected using a correlation between the number of charge / discharge cycles and the increase in internal resistance. The voltage detection method for batteries connected in parallel according to claim 1 or 2,
Further detecting the temperature of the parallel battery,
Using the voltage detected at the start of charging or at the start of discharging, and the temperature, calculate the idle period of the parallel battery,
Calculating the correlation between the leaving period and the increase in the internal resistance of the cell,
A voltage detection method for batteries connected in parallel, wherein the calculated internal resistance is corrected using a correlation between the idle period and the increase in the internal resistance. The voltage detection method for batteries connected in parallel according to claim 1 or 2,
Information indicating a change in the internal resistance of the cell depending on the temperature is stored in advance,
Further detecting the temperature of the parallel battery,
A method for detecting voltage of batteries connected in parallel, wherein the calculated internal resistance is corrected based on the stored temperature-dependent information indicating a change in internal resistance and the detected temperature. The method for detecting voltage of batteries connected in parallel according to claim 3,
Information indicating a change in the internal resistance of the cell depending on the temperature is stored in advance,
A method for detecting voltage of batteries connected in parallel, wherein the calculated internal resistance is corrected based on the stored temperature-dependent information indicating a change in internal resistance and the detected temperature. A voltage detecting method for batteries connected in parallel according to any one of claims 1 to 5,
Information indicating a change in the internal resistance of the cell depending on the battery voltage is stored in advance,
A voltage detection method for batteries connected in parallel, wherein the calculated internal resistance is corrected based on the stored information indicating the change in internal resistance depending on the battery voltage and the detected voltage. The voltage detection method for batteries connected in parallel according to any one of claims 1 to 6,
A method for detecting voltage of batteries connected in parallel, wherein the presence or absence of abnormality of the single battery is determined according to the estimated open circuit voltage. A parallel battery in which a plurality of secondary cells are connected in parallel;
Voltage detection means for detecting the voltage of the parallel battery,
Current detection means for detecting a current for each of the cells,
Based on the voltage and the current detected a plurality of times by the voltage detecting means and the current detecting means, an internal resistance calculating means for calculating an internal resistance for each unit cell,
Using the internal resistance, the voltage of the parallel battery, and the current of each cell, an open-circuit voltage estimating means for estimating the open-circuit voltage of the cell,
A voltage detecting device for a parallel-connected battery, comprising:

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