JP2016153731A - Battery monitoring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To more accurately evaluate a contact resistance in a battery system.SOLUTION: A battery monitoring device for monitoring the state of a battery system in which the battery unit terminal and power transmission member of a battery are bolt-connected, and power is supplied via the power transmission member to the outside includes: voltage measurement means for successively measuring the voltage of the battery system; current measurement means for successively measuring currents flowing through the battery system; and contact resistance calculation means for calculating the contact resistance of a bolt connection part between the battery unit terminal and the power transmission member by using the measurement value of the voltage measurement means and the measurement value of the current measurement means calculated by excluding the measurement value of the voltage measurement means and the measurement value of the current measurement means in a period when currents smaller than a current threshold are measured.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a battery monitoring device.

  Patent Document 1 listed below describes a technique for early determination of tightening loosening (coupling loosening) by bolts in a battery system in which an assembled battery composed of a plurality of secondary batteries and a load are connected by bus bars and bolts. Yes. In this battery system, the voltage between the terminals of each secondary battery acquired by a plurality of voltmeters and the load current acquired by a single ammeter are input to a parameter detection unit to form a digital signal, and each digital signal is Inter-terminal voltage and current parameters are supplied to a BMU (Battery Management Unit), and the BMU calculates contact resistance at each bolt connection based on the inter-terminal voltage and current parameters to determine the occurrence of loose connection. doing.

JP 2012-19577 A

  By the way, accurately evaluating the contact resistance is an indispensable matter for accurately determining the occurrence of loose connection. However, in the above prior art, the contact resistance cannot be accurately evaluated because the difference between the voltage signal transmission time from the plurality of voltmeters to the BMU and the current signal transmission time from the ammeter to the BMU is not considered.

  That is, when the voltage signal transmission time and the current signal transmission time are different from each other by a predetermined time, the BMU calculates the contact resistance based on the voltage between the terminals and the load current measured at different times. When the voltage between terminals or the load current fluctuates in FIG. 2, it is impossible to calculate an accurate contact resistance.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to more accurately evaluate the contact resistance in a battery system than in the past.

  In order to achieve the above object, in the present invention, as a first solution, a battery unit terminal and a power transmission member are bolt-connected, and the state of a battery system that supplies power to the outside via the power transmission member is monitored. A voltage monitoring means for sequentially measuring the voltage of the battery system, a current measuring means for sequentially measuring a current flowing through the battery system, and a voltage during a period in which a current smaller than the current threshold is measured Contact that calculates the contact resistance of the bolt connection between the battery unit terminal and the power transmission member using the measured value of the voltage measuring means and the measured value of the current measuring means excluding the measured value of the measuring means and the measured value of the current measuring means A means for providing a resistance calculating means is employed.

  In the present invention, as the second solving means, in the first solving means, the contact resistance calculating means includes a measured value of the voltage measuring means in a period in which a current having a change rate larger than the change rate threshold is measured, and A means is used in which the contact resistance between the battery unit terminal and the power transmission member is calculated using the measurement value of the voltage measurement means excluding the measurement value of the current measurement means and the measurement value of the current measurement means.

  In the present invention, as a third solving means, in the first or second solving means, the contact resistance calculating means is a regression line relating to voltage and current based on the measured value of the voltage measuring means and the measured value of the current measuring means. And the contact resistance is determined based on the slope of the regression line.

  In the present invention, as the fourth solving means, in the third solving means, the contact resistance calculating means obtains a regression line as reference data based on the measured value of the voltage measuring means and the measured value of the current measuring means in advance, A means of determining looseness of the bolt connection portion based on comparison with the reference data is adopted.

  In the present invention, as the fifth solving means, in the fourth solving means, the contact resistance calculating means includes a voltage value obtained based on a measured value of the current measuring means and reference data, a measured value of the voltage measuring means, Are used, and a method of determining looseness of the bolt connection portion based on the comparison result is employed.

  In the present invention, as a sixth solving means, in the fourth solving means, the contact resistance calculating means obtains a regression line based on the measured value of the voltage measuring means and the measured value of the current measuring means, Then, a means of comparing the inclination with the reference data and determining looseness of the bolt connection portion based on the comparison result is adopted.

  In the present invention, as a seventh solving means, in the second solving means, the contact resistance calculating means performs a low-pass filter process on the measured value of the voltage measuring means and the measured value of the current measuring means. A measure that excludes the measurement value of the voltage measurement means and the measurement value of the current measurement means during a period in which a current having a change rate smaller than the change rate threshold is measured is employed.

  In the present invention, as an eighth solving means, in any one of the first to seventh solving means, the battery is formed by bolting battery unit terminals of a plurality of secondary battery units via a power transmission member. In this case, the voltage measuring means is provided with respect to the bolt connection portion by the battery unit terminal and is also provided with respect to the bolt connection portion by the battery unit terminal.

  In the present invention, as a ninth solving means, in any one of the first to eighth solving means, the voltage measuring means is provided for each bolt connection portion by the power transmission member, and the contact resistance calculating means is The means for calculating the contact resistance for each of the bolt connection portions is employed.

  According to the present invention, the contact resistance calculation means includes the measurement value and current of the voltage measurement means during a period in which a current smaller than the current threshold is measured among the measurement value of the voltage measurement means and the measurement value of the current measurement means. Since the contact resistance of the bolt connection portion is calculated excluding the measurement value of the measuring means, it is possible to evaluate the contact resistance in the battery system more accurately than in the past. That is, since the measured value of the voltage measuring means and the measured value of the current measuring means in the period in which the current smaller than the current threshold is measured are small, the measured values from the voltage measuring means to the contact resistance calculating means When there is a discrepancy between the transmission time and the transmission time of the measured value from the current measurement means to the contact resistance calculation means, the influence on the contact resistance determination is greater than when the current is greater than the current threshold value. large. In addition, the measurement value of the voltage measurement unit and the measurement value of the current measurement unit during a period in which a current smaller than the current threshold is measured have a small value, so that the influence of the measurement error is large. Therefore, according to the present invention, it is possible to accurately evaluate the contact resistance in the battery system as compared with the conventional technique in which the contact resistance is calculated using all measured values regardless of the magnitude of the current.

It is a functional block diagram of the battery system in one embodiment of the present invention. It is a flowchart which shows operation | movement of the battery monitoring apparatus which concerns on one Embodiment of this invention. It is a figure which shows the waveform (a) which shows the whole electric current value at the time of charge in one Embodiment of this invention, and a linear regression line (b). It is a flowchart which shows operation | movement of the battery monitoring apparatus which concerns on one Embodiment of this invention. It is a flowchart which shows operation | movement of the battery monitoring apparatus which concerns on one Embodiment of this invention. It is a figure which shows operation | movement of the battery monitoring apparatus which concerns on one Embodiment of this invention. It is a figure which shows operation | movement of the battery monitoring apparatus which concerns on one Embodiment of this invention. It is a flowchart which shows operation | movement of the battery monitoring apparatus which concerns on one Embodiment of this invention. It is a functional block diagram which shows the modification of the structure of the battery system in one Embodiment of this invention. It is a functional block diagram which shows the modification of the structure of the battery system in one Embodiment of this invention.

Embodiments of the present invention will be described below with reference to the drawings.
The battery system A in the present embodiment is mounted on a ship, for example, discharge processing to various loads Ld mounted on the ship via the power converter Dc, and power supplied from a generator or a charger (not shown). Perform the charging process.

  As shown in FIG. 1, the battery system A includes battery modules M1, M2, and M3, a current sensor Y (current measurement means), a voltage sensor D (voltage measurement means), bus bars Bs1 to Bs4, and a data processing unit Ks. The bus bar Bs1 and the bus bar Bs4 are power transmission members in the present embodiment. Bus bar Bs2 and bus bar Bs3 are the 2nd electric power transmission members in this embodiment.

  The battery modules M1, M2, and M3 detect the voltages of the battery cells b11 to b13, b21 to b23, and b31 to b33 constituting the secondary battery units U1, U2, and U3, and output cell voltage data indicating the voltages. To do. Since the battery modules M1, M2, and M3 have the same configuration, the detailed description is given for the battery module M1, and the battery modules M2 and M3 are omitted.

  The battery module M1 includes a pair of battery unit terminals T11 and T12, a secondary battery unit U1, a cell voltage measurement unit Sk1 (voltage measurement unit), and a communication processing unit Ts1. The pair of battery unit terminals T11 and T12 are terminals for outputting the power of the battery cells b11 to b13 to the outside of the secondary battery unit U1. Battery unit terminal T11 is connected to battery terminal DT1 of power converter Dc via bus bar Bs1. On the other hand, the battery unit terminal T12 is connected to the battery unit terminal T21 of the battery module M2 via the bus bar Bs2.

  The secondary battery unit U1 includes three battery cells b11, b12, and b13 that are secondary batteries such as a lithium ion battery and a lead storage battery, and the battery cells b11, b12, and b13 are connected in series. . The cell voltage measurement unit Sk1 detects the voltage of each of the battery cells b11 to b13, converts the detection result to digital, and outputs cell voltage data indicating the voltage of each of the battery cells b11 to b13 to the communication processing unit Ts1. The communication processing unit Ts1 is connected to the communication processing unit Ts2 provided in the battery module M2, and outputs the cell voltage data input from the cell voltage measurement unit Sk1 to the communication processing unit Ts2. In the present embodiment, the cell voltage measurement unit Sk1 that detects individual voltages of the battery cells b11 to b13 is used. However, the unit voltage that detects the voltage of the secondary battery unit U1 instead of the cell voltage measurement unit Sk1. A measuring unit may be used.

  In the battery module M2, the communication processing unit Ts2 receives the cell voltage data input from the communication processing unit Ts1 and the cell voltage measurement unit Sk2 provided in the battery module M2 and the battery cell of the secondary battery unit U2. The cell voltage data indicating the respective voltages b21 to b23 is output to the communication processing unit Ts3 provided in the battery module M3.

  In the battery module M3, the communication processing unit Ts3 includes the cell voltage data input from the communication processing unit Ts2 and the battery cell b31 of the secondary battery unit U3 input from the cell voltage measurement unit Sk3 provided in the battery module M3. The cell voltage data indicating each voltage of .about.b33 is output to the data processing unit Ks. That is, the communication processing unit Ts3 sequentially outputs cell voltage data indicating the voltages of the battery cells b11 to b13, b21 to b23, and b31 to b33 to the data processing unit Ks. Moreover, battery cell b11-b13, b21-b23, b31-b33 are connected in series.

  Further, in the battery module M2, of the pair of battery unit terminals T21 and T22, the battery unit terminal T21 is connected to the battery unit terminal T12 of the battery module M1 via the bus bar Bs2. On the other hand, the battery unit terminal T22 is connected to the battery unit terminal 31 of the battery module M3 via the bus bar Bs3. Further, in the battery module M3, of the pair of battery unit terminals T31 and T32, the battery unit terminal T31 is connected to the battery unit terminal T22 of the battery module M2 via the bus bar Bs3 as described above. On the other hand, the battery unit terminal T32 is connected to the battery terminal DT2 of the pair of battery terminals DT1 and DT2 of the power converter Dc via the bus bar Bs4.

  One end of the bus bar Bs1 (power transmission member) is connected to the battery unit terminal T11 of the battery module M1, and the other end is connected to the battery terminal DT1 of the power converter Dc. One end of the bus bar Bs2 (second power transmission member) is connected to the battery unit terminal T12 of the battery module M1, and the other end is connected to the battery unit terminal T21 of the battery module M2. One end of the bus bar Bs3 (second power transmission member) is connected to the battery unit terminal T22 of the battery module M2, and the other end is connected to the battery unit terminal T31 of the battery module M3. One end of the bus bar Bs4 (power transmission member) is connected to the battery unit terminal T32 of the battery module M3, and the other end is connected to the battery terminal DT2 of the power converter Dc. The battery unit terminals T11 and T12, the battery unit terminals T21 and T22, the battery unit terminals T31 and T32, the battery terminals DT1 and DT2, and the bus bars Bs1 to Bs4 are connected by bolts.

  The current sensor Y sequentially detects the currents of the battery cells b11 to b13, b21 to b23, and b31 to b33 input to the power converter Dc via the battery terminals DT1 and DT2, with a time interval, and detects the detected current. The current detection signal shown is output to the data processing unit Ks. The voltage sensor D sequentially detects the voltages of the battery cells b11 to b13, b21 to b23, and b31 to b33 inputted to the power converter Dc via the battery terminals DT1 and DT2, with a time interval, and detects the detected voltage. The voltage detection signal shown is output to the data processing unit Ks.

  The data processing unit Ks includes an analog input unit Ak, a digital input unit Dk, a digital output unit Ds, and a calculation processing unit Mc (contact resistance calculation means). The analog input unit Ak digitally converts the current detection signal input from the current sensor Y and the voltage detection signal input from the voltage sensor D, and outputs the result to the arithmetic processing unit Mc. The digital input unit Dk receives cell voltage data input from the communication processing unit Ts3 and outputs the cell voltage data to the arithmetic processing unit Mc. The digital output unit Ds outputs the calculation result data input from the calculation processing unit Mc to an external monitoring device, a data storage device, or the like.

  The arithmetic processing unit Mc includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an interface circuit, and the like. The interface circuit is electrically connected to the analog input section Ak, the digital input section Dk, and the digital output section Ds. The arithmetic processing unit Mc executes predetermined arithmetic processing based on the current detection signal and voltage detection signal input from the analog input unit Ak and the cell voltage data input from the digital input unit Dk, and is obtained by the arithmetic processing. The calculated operation result data is output to the digital output unit Ds. The battery monitoring device according to the present embodiment includes the above-described cell voltage measuring units Sk1, Sk2, Sk3, current sensor Y, voltage sensor D, data processing unit Ks, and communication processing units Ts1, Ts2, Ts3.

Next, the operation of the data processing unit Ks configured as described above will be described with reference to FIGS.
The data processing unit Ks detects the loose connection between the battery unit terminals T11 and T12, the battery unit terminals T21 and T22, the battery unit terminals T31 and T32, the battery terminals DT1 and DT2, and the bus bars Bs1 to Bs4. The following various operations are executed.

  For example, when the battery system A is manufactured, the data processing unit Ks performs a first sampling operation for acquiring reference data for detecting loose connection. That is, in the data processing unit Ks, the arithmetic processing unit Mc performs data (total voltage value, total voltage value) for each combination of the charging rate pattern and the charging current and discharging current pattern of the secondary battery units U1, U2, and U3. And the total current value).

  In addition, the said voltage whole value is a voltage shown by the output voltage of the whole system of the battery system A, ie, a voltage detection signal. Moreover, the said voltage total value is the value which totaled each voltage value of battery cell b11-b13, b21-b23, b31-b33 shown by cell voltage data. The total current value is an output current of the entire battery system A, that is, a current indicated by a current detection signal. The total voltage value is calculated by the arithmetic processing unit Mc based on the cell voltage data.

  For example, the worker adjusts the charging rates of the secondary battery units U1, U2, and U3 as the above-described charging rate patterns and switches them to three patterns of 95%, 50%, and 5%, and for each charging rate pattern. In addition, the discharge current pattern is switched to 10 patterns of 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100% of the maximum discharge current. That is, the operator creates the operation states of 30 types of secondary battery units U1, U2, U3 that combine the patterns by various operations.

  In addition, the operator adjusts the charging rate to switch to three patterns of 95%, 50%, and 5%, and for each charging rate pattern, the charging current is 10%, 20%, 30%, Charging is performed by switching to 10 patterns of 40%, 50%, 60%, 70%, 80%, 90%, and 100%. That is, the operator creates 30 operation states of the secondary battery units U1, U2, U3 by various operations (step S1).

  The arithmetic processing unit Mc acquires the total voltage value, the total voltage value, and the total current value for each of the 60 combinations in total. Here, the arithmetic processing unit Mc monitors the total current value indicated by the current detection signal when acquiring the total voltage value, the total voltage value, and the total current value. The arithmetic processing unit Mc acquires the overall voltage value, the total voltage value, and the overall current value after the overall current value becomes stable. For example, at the time of charging, the arithmetic processing unit Mc changes the overall current value as shown in FIG. 3A, and acquires the overall current value after reaching the stable state shown in FIG. 3A (step S2). .

  When the rate of change of the overall current value is smaller than the change rate threshold value or the current value of the overall current value is higher than the current threshold value, the arithmetic processing unit Mc sets the overall current value to a stable state. Judge that it became. Note that the arithmetic processing unit Mc may determine that the overall current value is in a stable state when both conditions of the change rate of the overall current value and the current value of the overall current value are satisfied. Then, when the overall current value becomes stable, the arithmetic processing unit Mc then acquires the overall voltage value and the total voltage value in addition to the overall current value.

  Further, the arithmetic processing unit Mc may acquire the entire current value, the entire voltage value, and the total voltage value on the assumption that the entire current value is in a stable state based on an acquisition instruction from the operator. For example, during charging, the entire current value becomes stable in about 1 second from the start of discharging. When the entire current value becomes stable, the worker inputs an acquisition instruction to the arithmetic processing unit Mc. When the acquisition instruction is input, the arithmetic processing unit Mc acquires the entire current value, the entire voltage value, and the total voltage value. The acquisition instruction from the worker may be input to the arithmetic processing unit Mc via a predetermined operation unit or communication. As a result, the arithmetic processing unit Mc allows the overall current value, the overall voltage value, The total voltage value can be acquired.

  Then, the arithmetic processing unit Mc performs a linear regression line “y = αx + β” based on the total voltage value, the total voltage value, and the total current value acquired in accordance with the total of 60 combinations described above (see FIG. 3B). Is obtained (step S3). In this linear regression line “y = αx + β”, “x” is the “total current value”. “Y” is “total voltage value−total voltage value”. Further, “α” (inclination) is a value indicating the contact resistance caused by loose connection or the line resistance of the bus bars Bs1 to Bs4. “Β” (intercept) is a value indicating a measurement error by the voltage sensor D or the cell voltage measurement unit Sk1. The arithmetic processing unit Mc stores the linear regression line “y = αx + β” as reference data. The arithmetic processing unit Mc completes the first sampling operation by executing the processes of steps S1 to S3.

  In addition, after the battery system A is mounted on the ship that is actually operated and the data processing unit Ks removes and retightens the bolts by replacing the battery cells b11 to b13, b21 to b23, b31 to b33, etc. Then, the second sampling operation for re-acquiring the reference data is executed. That is, when the second data collection instruction is input to the predetermined operation unit during the operation of the ship, the arithmetic processing unit Mc acquires the data (total voltage value, total voltage value, and total current value) a predetermined number of times. Note that, during the operation of the ship, the secondary battery units U1, U2, and U3 are discharged and charged in accordance with the operation.

  In addition, the arithmetic processing unit Mc acquires data when the secondary battery units U1, U2, and U3 are discharged in the predetermined number of times (step S11), while acquiring data for the remaining half during charging (step S11). Step S12). Therefore, it is desirable that the predetermined number of times is an even number. For example, when the predetermined number of times is 100, the arithmetic processing unit Mc acquires data 50 times during discharging, and acquires data 50 times during charging.

  Here, when acquiring the overall voltage value, the total voltage value, and the overall current value, the arithmetic processing unit Mc monitors the overall current value indicated by the current detection signal as in the process of step S2 of the first sampling operation. That is, the arithmetic processing unit Mc acquires the overall voltage value, the total voltage value, and the overall current value after the overall current value becomes stable as in the first sampling operation.

  Then, after acquiring the data a predetermined number of times, the arithmetic processing unit Mc generates a linear regression line “y = αx + β” based on the acquired voltage overall value, voltage total value, and current overall value, as in the first sampling operation. Obtained (step S13). The arithmetic processing unit Mc stores the linear regression line “y = αx + β” as reference data. The arithmetic processing unit Mc completes the second sampling operation by executing the processes of steps S11 to S13.

  Further, the data processing unit Ks uses the reference data to execute a first looseness determination operation for determining connection looseness. For example, the arithmetic processing unit Mc periodically performs the first looseness determination operation during the operation of the ship. First, the arithmetic processing unit Mc acquires data (total voltage value, total voltage value, and total current value) for determining loose connection for a predetermined number of times during charging (step S21). Here, the arithmetic processing unit Mc acquires data (total voltage value, total voltage value, and total current value) a predetermined number of times during one charging operation. Therefore, each of the acquired total voltage value, total voltage value, and total current value is an approximate value. Therefore, the points indicated by the data are clustered as shown in FIG.

  Further, when acquiring the overall voltage value, the total voltage value, and the overall current value, the arithmetic processing unit Mc monitors the overall current value indicated by the current detection signal as in the first sampling operation. That is, the arithmetic processing unit Mc acquires the overall voltage value, the total voltage value, and the overall current value after the overall current value becomes stable as in the first sampling operation.

Subsequently, when the data acquisition is completed a predetermined number of times, the arithmetic processing unit Mc calculates a sample average Vavg using “total voltage value−total voltage value” of each acquired data as a sample based on the following equation (1). (Step S22). Note that the value “n” in the following equation (1) is the same as the number of data, that is, the predetermined number of times.
Vavg = Σ (total voltage value−total voltage value) / n (1)
Then, the arithmetic processing unit Mc calculates the unbiased variance S ^ 2 by substituting the sample average Vavg into the following formula (2) (step S23).
S ^ 2 = Σ {(total voltage value−total voltage value) −Vavg)} ^ 2 / (n−1) (2)

Then, the arithmetic processing unit Mc obtains a confidence interval shown in the following equation (3) based on the sample average Vavg and the unbiased variance S ^ 2, that is, a population average confidence interval of the population including the sample. (Step S24).
Vavg−k × S ^ 2 / √n ≦ population mean ≦ Vavg + k × S ^ 2 / √n (3)
In the first looseness determination operation, since the number of samples is small, that is, the number of acquired data is small, the variable “k” is determined from the t distribution based on the reliability (95%, 99%, etc.). .

  Subsequently, the arithmetic processing unit Mc substitutes the average value of the entire current value acquired in the process of step S21 for “x” of the reference data “y = αx + β”, and thereby the reference voltage value that is the value of “y”. To get. Then, the arithmetic processing unit Mc determines whether or not the reference voltage value is included in the confidence interval (step S25). When the reference voltage value is included in the confidence interval (in the case of YES), the arithmetic processing unit Mc determines that there is no loose connection (step S26). On the other hand, when the reference voltage value is not included in the confidence interval (in the case of NO), the arithmetic processing unit Mc determines whether or not the confidence interval exists on the negative side with respect to the reference voltage value (step S27).

  The fact that the confidence interval exists on the negative side with respect to the reference voltage value (see FIG. 6B) indicates that the contact resistance due to loose connection is increased and the overall voltage value is increased. . That is, the arithmetic processing unit Mc determines whether or not the confidence interval exists on the negative side with respect to the reference voltage value by increasing the overall voltage value due to loose connection or the like. If the confidence interval exists on the negative side with respect to the reference voltage value (in the case of YES), the arithmetic processing unit Mc determines that there is a loose connection (step S28).

  On the other hand, when the confidence interval does not exist on the negative side with respect to the reference voltage value (in the case of NO), the arithmetic processing unit Mc determines that there is no loose connection in the process of step S26. Then, the arithmetic processing unit Mc outputs the determination result of the presence or absence of the loose connection to an external monitoring device or data storage device. The arithmetic processing unit Mc executes the processes of steps S21 to S28 to complete the first looseness determination operation.

  In the first looseness determination operation, data is acquired at the time of charging in the processing of step S21. However, data may be acquired at the time of discharging instead of at the time of charging. In this case, the arithmetic processing unit Mc determines whether or not the confidence interval exists on the positive side with respect to the reference voltage value in the processing of step S27, and the confidence interval exists on the positive side with respect to the reference voltage value. In the case (see FIG. 6C), it is determined that there is loose connection in the process of step S28.

  Further, after the bolts are removed and retightened by replacement of the battery cells b11 to b13, b21 to b23, b31 to b33, etc., before the second sampling operation for reacquiring the reference data, for example, the first A bolt retightening determination may be performed by performing a looseness determination operation. At that time, even if the connection is loosened, the connection looseness may be determined by charging or discharging a low current that is unlikely to ignite and performing the first looseness determination operation.

Further, in the first looseness determination operation, the presence / absence of connection looseness is determined based on whether or not the confidence interval exists on the negative side with respect to the reference voltage. Also good. For example, the arithmetic processing unit Mc may determine whether or not there is a loose connection based on the following equation (11).
Vavg ≦ reference voltage value−Verror (11)

The Verror is a value obtained based on a test or the like that has been performed in advance. That is, the arithmetic processing unit Mc determines whether “Vavg (sample average)” is equal to or less than “reference voltage value−Verror”. The fact that “Vavg” is equal to or less than “reference voltage value−Verror” (see FIG. 7) indicates that the contact resistance due to loose connection or the like increases and the overall voltage value increases. That is, the arithmetic processing unit Mc determines whether or not “Vavg” is equal to or less than “reference voltage value−Verror” because the overall voltage value increases due to loose connection or the like. The arithmetic processing unit Mc determines that the connection is loose when “Vavg” is equal to or less than “reference voltage value−Verror”. On the other hand, if “Vavg” is not equal to or less than “reference voltage value−Verror”, the arithmetic processing unit Mc determines that there is no loose connection. Further, when data is acquired not at the time of charging but at the time of discharging, the presence or absence of loose connection may be determined based on the following equation (12).
Vavg ≧ reference voltage value + Verror (12)
That is, the arithmetic processing unit Mc determines that there is loose connection when “Vavg” is equal to or greater than “reference voltage value + Verror”.

  In addition, the data processing unit Ks may execute a second looseness determination operation different from the first looseness determination operation instead of the first looseness determination operation. For example, the arithmetic processing unit Mc periodically performs the second looseness determination operation during the operation of the ship.

  First, the arithmetic processing unit Mc acquires data (total voltage value, total voltage value, and total current value) for determining connection loosening a predetermined number of times during the operation of the ship. Note that, during the operation of the ship, the secondary battery units U1, U2, and U3 are discharged and charged in accordance with the operation.

  In addition, the arithmetic processing unit Mc acquires data when the secondary battery units U1, U2, and U3 are discharged in the predetermined number of times (step S31), and acquires data for the remaining half during charging (step S31). Step S32). Therefore, it is desirable that the predetermined number of times is an even number. For example, when the predetermined number of times is 100, the arithmetic processing unit Mc acquires data 50 times during discharging, and acquires data 50 times during charging.

  Here, when acquiring the overall voltage value, the total voltage value, and the overall current value, the arithmetic processing unit Mc monitors the overall current value indicated by the current detection signal as in the process of step S2 of the first sampling operation. That is, the arithmetic processing unit Mc acquires the overall voltage value, the total voltage value, and the overall current value after the overall current value becomes stable as in the first sampling operation. And the arithmetic processing part Mc repeats the process of said step S31 and step S32 predetermined predetermined times (step S33). That is, the arithmetic processing unit Mc repeats the operation of acquiring data a predetermined number of times by the processes in steps S31 to S33.

Subsequently, when the calculation processing unit Mc repeats the processes of step S31 and step S32 a predetermined number of times to complete the data acquisition, the linear regression line “y = Cx + E” is obtained from each acquired data based on the following equation (21). ”Is obtained, and the inclination“ C ”indicating the contact resistance caused by the loosening of the bolt or the like is obtained from the linear regression line (step S34). That is, since the linear regression line “y = Cx + E” acquires the linear regression line “y = Cx + E” as many times as the number of times that the processes in steps S31 and S32 are repeated, the slope “C” corresponding to the number of times can be acquired. .
Then, the arithmetic processing unit Mc calculates a sample average Cavg using “C” as a sample based on the following equation (21) (step S35). Note that the value “m” in the following equation (21) is the same as the number of data, that is, the predetermined number of times.
Cavg = ΣC / m (21)
Then, the arithmetic processing unit Mc calculates the unbiased variance S ^ 2 by substituting the sample average Cavg into the following equation (22) (step S36).
S ^ 2 = Σ {(C−Cavg)} ^ 2 / (m−1) (22)

Then, the arithmetic processing unit Mc calculates a confidence interval for the population average of the population including the sample shown in the following equation (23) based on the sample average Cavg and the unbiased variance S ^ 2. (Step S37).
Cavg−k × S ^ 2 / √m ≦ population average ≦ Cavg + k × S ^ 2 / √m (22)
In the second looseness determination operation, since the number of samples is small, that is, the number of acquired data is small, the variable “k” is determined from the t distribution based on the reliability (95%, 99%, etc.). .

  Subsequently, the arithmetic processing unit Mc determines whether or not the slope “α” of the reference data “y = αx + β” (that is, the contact resistance of the reference data) is included in the confidence interval (step S38). When the slope “α” is included in the confidence interval (in the case of YES), the arithmetic processing unit Mc determines that there is no loose connection (step S39). On the other hand, when the slope “α” is not included in the confidence interval (in the case of NO), the arithmetic processing unit Mc determines whether or not the confidence interval is present on the larger side of the slope “α” (step S40). .

  The fact that the confidence interval is on the larger side with respect to the slope “α” indicates that the contact resistance due to loose connection is increased. That is, the arithmetic processing unit Mc determines whether or not the confidence interval exists on the side where the confidence interval is larger with respect to the inclination “α” by increasing the contact resistance. The arithmetic processing unit Mc determines that the connection is loose when the confidence interval is on the larger side with respect to the inclination “α” (step S41).

  On the other hand, the arithmetic processing unit Mc determines that there is no loose connection when the confidence interval does not exist on the side where “α” is large. Then, the arithmetic processing unit Mc outputs the determination result of the presence or absence of the loose connection to an external monitoring device or data storage device. The arithmetic processing unit Mc completes the second looseness determination operation by executing the processes of steps S31 to S41.

  Further, after the bolts are removed and retightened by replacement of the battery cells b11 to b13, b21 to b23, b31 to b33, etc., before the second sampling operation for reacquiring the reference data, for example, the second A bolt retightening determination may be performed by performing a looseness determination operation. At that time, even if the connection is loosened, the connection looseness may be determined by charging or discharging a low current that is unlikely to ignite and performing the second looseness determination operation.

Further, in the second looseness determination operation, the presence / absence of looseness of connection is determined based on whether or not the confidence interval is present on the larger side with respect to the slope “α”, but may be determined by other methods. It may be. For example, the arithmetic processing unit Mc may determine whether or not there is a loose connection based on the following equation (31).
Cavg ≧ Cerror (31)

  The Cerror is a value obtained based on a test or the like performed in advance. That is, the arithmetic processing unit Mc determines whether “Cavg (sample average)” is equal to or greater than “Cerror”. “Cavg” equal to or higher than “Cerror” indicates that the contact resistance due to loose connection is increased. That is, the arithmetic processing unit Mc determines whether “Cavg” is equal to or higher than “Cerror” because the contact resistance increases due to loose connection or the like.

  The arithmetic processing unit Mc determines that the connection is loose when “Cavg” is equal to or greater than “Cerror”. On the other hand, if “Cavg” is not equal to or less than “Cerror”, the arithmetic processing unit Mc determines that there is no loose connection. In addition, data is acquired by repeating the processes of steps S31 and S32 a predetermined number of times, and “Cavg (sample average)” is obtained based on this data. However, the processes of steps S31 and S32 are performed once. The linear regression line “y = Cx + E” of the data obtained in step (C) may be compared with the slope “C” and “Cerror” to determine whether the connection is loose.

  According to the present embodiment, the arithmetic processing unit Mc includes the voltage sensor D, the current sensor Y, and the measured values of the cell voltage measuring units Sk1, Sk2, and Sk3 (the total voltage value, the total current value, and the cell voltage). The total voltage value, the total current value, and the cell voltage during the period when the current smaller than the predetermined current threshold is measured are excluded, that is, after the total current value becomes stable, the total voltage value and voltage Since the total value and the entire current value are obtained and a linear regression line is obtained (that is, contact resistance is obtained), it is possible to evaluate the contact resistance in the battery system A more accurately than in the past.

  That is, since the overall voltage value, the overall current value, and the cell voltage during a period in which a current smaller than the current threshold is measured are small, the cell voltage measuring units Sk1, Sk2, Sk3 to the arithmetic processing unit Mc When a deviation occurs between the transmission time of the data and the transmission time from the voltage sensor D and the current sensor Y to the arithmetic processing unit Mc, the influence on the determination of the contact resistance is greater than the current threshold value. Bigger than bigger. In addition, since the voltage overall value, the current overall value, and the cell voltage during a period in which a current smaller than the current threshold is measured have small values, the influence of measurement errors is also large.

  Therefore, according to the present embodiment, it is possible to accurately evaluate the contact resistance in the battery system A as compared with the conventional technique in which the contact resistance is calculated using all measured values regardless of the magnitude of the current. .

As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, For example, the following modifications can be considered.
(1) Although the said embodiment becomes a structure shown in FIG. 1, this invention is not limited to this. For example, as shown in FIG. 9, line voltage measuring units Rk1, Rk2, Rk3, Rk4 may be provided. The line voltage measuring units Rk1, Rk2, Rk3, and Rk4 are provided for the bolt connection portions of the bus bars Bs1 to Bs4, and are connected to the battery unit terminals T11, T12, T21, T22, T31, T32 and the battery terminals DT1, DT2. Then, the voltage of the power flowing through the bus bars Bs1 to Bs4 (that is, the voltage between both ends of the bus bars Bs1 to Bs4) is detected, the detection result is digitally converted, and the line voltage data is output to the communication processing units Ts1, Ts2, and Ts3. The line voltage data output to the communication processing units Ts1, Ts2, and Ts3 is output to the arithmetic processing unit Mc via the communication processing units Ts1, Ts2, and Ts3, similarly to the cell voltage data. The arithmetic processing unit Mc obtains the contact resistance in each bolt connection part and can identify the place where the connection is loosened. Further, as shown in FIG. 10, it may be possible to provide line voltage sensors sd1, sd2, sd3, and sd4 that output analog line voltage detection signals instead of the line voltage measurement units Rk1, Rk2, Rk3, and Rk4. The line voltage sensors sd1, sd2, sd3, and sd4 output a line voltage detection signal to the analog input unit Ak. The analog input unit Ak digitally converts the line voltage detection signal and outputs it to the arithmetic processing unit Mc. The arithmetic processing unit Mc obtains the contact resistance in each bolt connection part and can identify the place where the connection is loosened. In the above embodiment, the arithmetic processing unit Mc performs the above-described first sampling operation, second sampling operation, first slackness determination operation, and second slackness determination operation based on the voltage detection signal, current detection signal, and cell voltage data. However, the above-described operation is not performed, and the voltage detection signal, the current detection signal, and the cell voltage data are output to an external monitoring device, a data storage device, etc., and the above-described operation is executed externally. Good.

(2) In the above-described embodiment, the secondary battery units U1, U2, and U3 configured by the battery cells b11 to b13, b21 to b23, and b31 to b33 are connected to each other through the bus bar Bs2 and the bus bar Bs3. Although a battery is comprised and a battery cell b11-b13, b21-b23, b31-b33 each becomes a structure by which voltage is measured by cell voltage measurement part Sk1, Sk2, Sk3, this invention is not limited to this. For example, the cell voltage measurement units Sk1, Sk2, and Sk3 are not provided for one battery connected to the power converter Dc. On the other hand, the arithmetic processing unit Mc determines the voltage of the bus bar Bs1 or bus bar Bs4 based on the overall voltage value indicated by the voltage detection signal from the voltage sensor D and the overall voltage value indicated by the current detection signal from the current sensor Y. You may make it calculate the contact resistance of a connection part.

(3) In the above embodiment, the linear regression line is obtained based on the total voltage value, the total voltage value, and the total current value. This is obtained from the obtained data (total voltage value, total voltage value, and total current value). This is because there is variation. For example, the arithmetic processing unit Mc performs low-pass filtering on the overall voltage value, the total voltage value, and the overall current value, so that the current having a change rate that is smaller than the current threshold value and greater than the change rate threshold value. You may make it exclude the voltage whole value, voltage total value, and current whole value in the period when a whole value is measured. Since the variation in data is reduced by the low-pass filter processing, even when the contact resistance is obtained using the data subjected to the low-pass filter processing as it is, the error can be reduced.

(4) In the above embodiment, an example in which three battery cells b11 to b13, b21 to b23, b31 to b33 are provided for each of the three battery modules M1 to M3 has been described. The number of is not limited.

A battery system Ak analog input unit b11 to b13 battery cell b21 to b23 battery cell b31 to b33 battery cell Bs1 to Bs4 bus bar (power transmission member, second power transmission member)
D Voltage sensor (voltage measurement means)
Dc power converter Dk digital input unit Ds digital output unit DT1, DT2 battery terminal Ks data processing unit Ld load M1, M2, M3 battery module Mc calculation processing unit (contact resistance calculation means)
Rk1, Rk2, Rk3, Rk4 Line voltage measuring unit (voltage measuring means)
sd1, sd2, sd3, sd4 Line voltage sensor (voltage measuring means)
Sk1, Sk2, Sk3 Cell voltage measuring unit (voltage measuring means)
T11, T12 Battery unit terminal T21, T22 Battery unit terminal T31, T32 Battery unit terminal Ts1, Ts2, Ts3 Communication processing unit U1, U2, U3 Secondary battery unit Y Current sensor (current measuring means)

Claims (9)

A battery monitoring device for monitoring a state of a battery system in which a battery unit terminal and a power transmission member are bolt-connected and power is supplied to the outside through the power transmission member,
Voltage measuring means for sequentially measuring the voltage of the battery system;
Current measuring means for sequentially measuring the current flowing through the battery system;
Using the measured value of the voltage measuring means and the measured value of the voltage measuring means excluding the measured value of the current measuring means and the measured value of the current measuring means in a period in which the current smaller than the current threshold is measured And a contact resistance calculating means for calculating a contact resistance of a bolt connection portion between the battery unit terminal and the power transmission member.   The contact resistance calculating means measures the voltage measurement means excluding the measurement value of the voltage measurement means and the measurement value of the current measurement means during a period in which the current having a change rate larger than a change rate threshold is measured. The battery monitoring device according to claim 1, wherein a contact resistance between the battery unit terminal and the power transmission member is calculated using a value and a measured value of the current measuring unit.   The contact resistance calculation means obtains a regression line related to the voltage and the current based on the measurement value of the voltage measurement means and the measurement value of the current measurement means, and obtains the contact resistance based on the slope of the regression line. The battery monitoring apparatus according to claim 1 or 2, characterized in that:   The contact resistance calculation means obtains the regression line as reference data based on the measurement value of the voltage measurement means and the measurement value of the current measurement means in advance, and loosens the bolt connection portion based on the comparison with the reference data. The battery monitoring device according to claim 3, wherein the battery monitoring device is determined.   The contact resistance calculation means compares the voltage value obtained based on the measurement value of the current measurement means and the reference data with the measurement value of the voltage measurement means, and loosens the bolt connection portion based on the comparison result. The battery monitoring device according to claim 4, wherein the battery monitoring device is determined.   The contact resistance calculation means obtains a regression line based on the measurement value of the voltage measurement means and the measurement value of the current measurement means, compares the slope of the regression line and the reference data, and based on the comparison result The battery monitoring device according to claim 4, wherein looseness of the bolt connection portion is determined.   The contact resistance calculation unit is smaller than the current threshold and larger than the change rate threshold by low-pass filtering the measurement value of the voltage measurement unit and the measurement value of the current measurement unit. The battery monitoring device according to claim 2, wherein the measurement value of the voltage measurement unit and the measurement value of the current measurement unit in a period during which the current of the change rate is measured are excluded. When the battery system is a battery unit terminal of a plurality of secondary battery units that are bolt-connected through a power transmission member,
The voltage measuring means is provided with respect to a bolt connection portion by the battery unit terminal and is also provided with respect to a bolt connection portion by the battery unit terminal. The battery monitoring device described. The voltage measuring means is provided for each bolt connection portion by the power transmission member,
The battery monitoring device according to claim 1, wherein the contact resistance calculation unit calculates a contact resistance for each of the bolt connection portions.

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