JP2020148566A - Lead acid battery state detector and lead acid battery state detection method - Google Patents

Abstract

To accurately estimate the state of a lead acid battery even when there exists a variation in the temperature between the cells of the lead acid battery.SOLUTION: Provided is a lead acid battery state detector comprising a processor and a memory for storing a program which, when executed by the processor, realizes the functions below, the lead acid battery state detector receiving a voltage signal from a voltage sensor that detects the terminal voltage of a lead acid battery, a current signal from a current sensor that detects a charge/discharge current of the lead acid battery and temperature signals from at least two temperature sensors that detect the temperatures of cells located at both ends of an electrolytic bath, calculating values of elements that constitute an equivalent circuit of the lead acid battery on the basis of the voltage and current signals of the lead acid battery during a discharge, correcting the values of elements that constitute the calculated equivalent circuit on the basis of a difference in the received temperatures of the cells located at both ends, detecting the state of the lead acid battery on the basis of the corrected values of the elements, and outputting the detected state of the lead acid battery.SELECTED DRAWING: Figure 1

Description

The present invention relates to a lead-acid battery state detection device and a lead-acid battery state detection method.

In Patent Document 1, when there is a usage history that induces variation among cells constituting the lead-acid battery, the deterioration closer to reality is made by correcting a predetermined function indicating the deterioration state of the lead-acid battery. Techniques for obtaining state are disclosed.

Japanese Unexamined Patent Publication No. 2017-181206

By the way, in an in-vehicle lead-acid battery, depending on the installation position and direction, heat from a prime mover such as an engine or a motor may raise the temperature of cells located close to these, resulting in temperature variation between cells. is there. In such a case, the value of internal resistance may differ between cells having different temperatures, or the deterioration of a cell having a high temperature may progress faster than that of other cells.

However, in the technique disclosed in Patent Document 1, since there is only one temperature sensor, it is not possible to detect the temperature variation as described above, so that there is a problem that the state of the lead storage battery cannot be accurately detected. is there.

The present invention has been made in view of the above circumstances, and lead can accurately estimate the state of a lead-acid battery even when there is a temperature variation between cells of the lead-acid battery. It is an object of the present invention to provide a storage battery state detection device and a lead storage battery state detection method.

In order to solve the above problems, the present invention is executed by a processor and the lead-acid battery state detection device for detecting the state of an in-vehicle lead-acid battery having electrolytic tanks divided into a plurality of cells. It has a memory for storing a program that realizes the following functions, a voltage signal from a voltage sensor that detects the terminal voltage of the lead-acid battery, and a current from a current sensor that detects the charge / discharge current of the lead-acid battery. A signal and a temperature signal from a temperature sensor that detects the temperature of a plurality of locations in the electrolytic tank are received, and an equivalent circuit of the lead-acid battery is configured based on the voltage signal and the current signal during discharge of the lead-acid battery. The value of the element to be calculated is calculated, and the value of the element constituting the equivalent circuit is corrected by correcting the value of the element based on the temperature signals indicating the temperatures of a plurality of locations in the electrolytic tank, and the value of the corrected element is corrected. Based on the above, the state of the lead-acid battery is detected, and the detected state of the lead-acid battery is output.
According to such a configuration, it is possible to accurately estimate the state of the lead-acid battery even when there is a temperature variation between the cells of the lead-acid battery.

Further, according to the present invention, the temperature sensor is arranged so as to be able to detect the temperature of cells located at both ends of the electrolytic cell, and detects a temperature rise due to heat generated from a vehicle prime mover of the cells located at both ends. It is a feature.
With such a configuration, it is possible to reduce the influence from the heat source and accurately estimate the state of the lead-acid battery.

Further, the present invention is characterized in that the temperature sensor is arranged so as to be able to detect the temperature of a plurality of cells in the electrolytic cell, and detects a temperature rise due to the progress of deterioration of the cells.
With such a configuration, it is possible to reduce the influence of the progress of deterioration and accurately estimate the state of the lead-acid battery.

Further, the present invention is characterized in that the value of the element of the equivalent circuit is corrected based on the value obtained by time-integrating the temperature signal from the temperature sensor.
According to such a configuration, it is possible to accurately correct the value of the element of the equivalent circuit based on the past history of temperature.

Further, the present invention is characterized in that the values of the elements of the equivalent circuit are distributed to each cell based on the values obtained by time-integrating the temperature signals.
According to such a configuration, it is possible to accurately obtain the value of the element possessed by each cell.

Further, the present invention is characterized in that the dischargeable capacity of each cell is corrected based on the value of the element distributed to each cell.
With such a configuration, it is possible to accurately determine the dischargeable capacity of each cell.

Further, the present invention receives the temperature signal from the temperature sensor arranged one by one for each cell, and corrects the value of the element of the equivalent circuit based on the temperature signal from each cell. It is characterized by.
According to such a configuration, it is possible to accurately obtain the value of the element possessed by each cell.

Further, the present invention receives the temperature signals from at least two temperature sensors arranged vertically apart from each other in the electrolytic cell, and determines the temperature difference in the vertical direction of the electrolytic cell based on the temperature signals. It is characterized in that it detects, detects the degree of stratification of the electrolytic solution based on the detected temperature difference, and corrects the value of the element based on the degree of stratification.
According to such a configuration, the state of the lead-acid battery can be accurately estimated in consideration of the influence of stratification.

Further, the present invention is characterized in that the temperature sensor is arranged in a cover accommodating the lead storage battery.
With such a configuration, it is possible to accurately estimate the state of the lead-acid battery while reducing the influence of an external heat source.

Further, the present invention relates to a voltage signal from a voltage sensor that detects the terminal voltage of the lead-acid battery in a lead-acid battery state detection method for detecting the state of an in-vehicle lead-acid battery having electrolytic tanks divided into a plurality of cells. , A current signal from a current sensor that detects the charge / discharge current of the lead-acid battery and a temperature signal from at least two temperature sensors that detect the temperature of cells located at both ends of the electrolytic tank are received by a system having a processor. Then, the value of the element constituting the equivalent circuit of the lead-acid battery is calculated by the system based on the voltage signal and the current signal during discharge of the lead-acid battery, and the calculated element constituting the equivalent circuit is calculated. The value of the element is corrected by the system based on the temperature difference between the cells located at both ends of the received value, and the state of the lead-acid battery is detected by the system based on the corrected value of the element. It is characterized in that the detected state of the lead-acid battery is output by the system.
According to such a method, the state of the lead-acid battery can be accurately estimated even when there is a temperature variation between the cells of the lead-acid battery.

According to the present invention, there is provided a lead-acid battery state detection device and a lead-acid battery state detection method capable of accurately estimating the state of a lead-acid battery even when there is a temperature variation between cells of the lead-acid battery. It becomes possible to do.

It is a figure which shows the structural example of the lead-acid battery state detection apparatus which concerns on embodiment of this invention. It is a figure which shows the structural example of the lead storage battery shown in FIG. It is a block diagram which shows the detailed configuration example of the control part of FIG. It is a figure which shows an example of the equivalent circuit of the lead storage battery shown in FIG. It is a figure which shows the relationship between the resistance between terminals in the conventional case, resistance value of each cell, and estimated capacitance. It is a figure which shows the relationship between the resistance between terminals in this embodiment, the resistance value of each cell, and estimated capacitance. It is a flowchart for demonstrating an example of the process which is executed when an engine is started in embodiment of this invention. It is a flowchart for demonstrating an example of the process which is executed when an engine is stopped in the Embodiment of this invention. It is a figure which shows the other arrangement example of a temperature sensor. It is a figure which shows the example of the contour line of the temperature of the lead storage battery. It is a figure which shows the other arrangement example of a temperature sensor. It is a figure which shows the other arrangement example of a temperature sensor. It is a figure which shows the other arrangement example of a temperature sensor. It is a figure which shows the example which arranges a temperature sensor on a cover.

Next, an embodiment of the present invention will be described.

(A) Explanation of Configuration of Embodiment of the Present Invention FIG. 1 is a diagram showing a power supply system of a vehicle having a lead-acid battery state detection device according to the embodiment of the present invention. In this figure, the lead-acid battery state detection device 1 has a control unit 10 as a main component, and a voltage sensor 11, a current sensor 12, temperature sensors 13-1, 13-2, and a discharge circuit 15 are connected to the outside. , The state of the lead storage battery 14 is detected. The control unit 10, the voltage sensor 11, the current sensor 12, the temperature sensors 13-1 and 13-2, and the discharge circuit 15 are not configured separately, but a part or all of them are integrated. May be good.

Here, the control unit 10 refers to the outputs from the voltage sensor 11, the current sensor 12, and the temperature sensors 13-1 and 13-2, detects the state of the lead-acid battery 14, and outputs the information of the detection result to the outside. The charge state of the lead-acid battery 14 is controlled by outputting and controlling the generated voltage of the alternator 16. The control unit 10 does not control the charging state of the lead-acid battery 14 by controlling the generated voltage of the alternator 16, but for example, an ECU (Electric Control Unit) (not shown) charges the lead-acid battery 14 based on information from the control unit 10. The state may be controlled.

The voltage sensor 11 detects the terminal voltage of the lead-acid battery 14 and supplies it to the control unit 10 as a voltage signal. The current sensor 12 detects the current flowing through the lead storage battery 14 and supplies it to the control unit 10 as a current signal.

The temperature sensors 13-1 and 13-2 detect the electrolytic solution of the lead-acid battery 14 or the ambient temperature (for example, absolute temperature) of the lead-acid battery 14, and supply the temperature signal to the control unit 10. As the temperature sensors 13-1 and 13-2, for example, a thermistor, a resistance temperature detector, a thermocouple, and an IC (Integrated Circuit) temperature sensor can be used. An infrared sensor that detects infrared rays may be used.

FIG. 2 shows a configuration example of the lead storage battery 14. As shown in FIG. 2, the lead-acid battery 14 has, for example, an electrolytic cell 140 partitioned into a plurality of cells 141 to 146. Inside the cells 141 to 146, a lead cathode, a separator, and a lead dioxide anode are laminated and arranged, and an electrolytic solution is filled. Temperature sensors 13-1 and 13-2 are arranged on the surfaces 14a and 14b of the cells 141 and 146 located at both ends of the electrolytic cell 140. The temperature sensors 13-1 and 13-2 detect the temperature of the cells 141 and 146 and output a temperature signal.

The discharge circuit 15 is composed of, for example, a semiconductor switch and a resistance element connected in series, and turns on / off the semiconductor switch according to the control of the control unit 10 to discharge the lead-acid battery 14 with a desired waveform. be able to.

The alternator 16 is driven by the engine 17, generates AC power, converts it into DC power by a rectifier circuit, and charges the lead-acid battery 14. The alternator 16 is controlled by the control unit 10 so that the generated voltage can be adjusted.

The engine 17 is composed of, for example, a reciprocating engine such as a gasoline engine and a diesel engine, a rotary engine, or the like, is started by a starter motor 18, drives drive wheels via a transmission, gives propulsion to a vehicle, and is an alternator 16. To generate power. The starter motor 18 is composed of, for example, a DC motor, generates rotational force by electric power supplied from the lead storage battery 14, and starts the engine 17. An electric motor may be used instead of the engine 17.

The load 19 is composed of, for example, an electric steering motor, a defogger, a seat heater, an ignition coil, a car audio, a car navigation system, and the like, and is operated by electric power supplied from the lead storage battery 14. In the example of FIG. 1, only the engine 17 outputs the driving force, but for example, a hybrid vehicle provided with an electric motor that assists the engine 17 may be used. In the case of a hybrid vehicle, the lead-acid battery 14 activates a high-pressure system (a system for driving an electric motor) composed of a lithium battery or the like, and the high-pressure system starts the engine 17.

FIG. 3 is a diagram showing a detailed configuration example of the control unit 10 shown in FIG. As shown in this figure, the control unit 10 includes a CPU (Central Processing Unit) 10a as a processor, a ROM (Read Only Memory) 10b, a RAM (Random Access Memory) 10c, a communication unit 10d, and an I / F (Interface) 10e. , And a bus 10f. Here, the CPU 10a controls each unit based on the program 10ba stored in the ROM 10b. The ROM 10b is composed of a semiconductor memory or the like and stores the program 10ba or the like. The RAM 10c is composed of a semiconductor memory or the like, and stores data generated when the program 10ba is executed and data 10ca such as a table. The communication unit 10d communicates with an ECU (Electronic Control Unit) or the like, which is a higher-level device, and notifies the higher-level device of the detected information or control information. The I / F10e converts the voltage signal, the current signal, and the temperature signal supplied from the voltage sensor 11, the current sensor 12, and the temperature sensors 13-1 and 13-2 into digital signals and captures them, and also discharges the circuit. A drive current is supplied to the 15, alternator 16, starter motor 18, and the like to control them. The bus 10f is a group of signal lines for connecting the CPU 10a, the ROM 10b, the RAM 10c, the communication unit 10d, and the I / F 10e to each other and enabling information exchange between them.

In the example of FIG. 3, one CPU 10a is provided, but the distributed processing may be executed by a plurality of CPUs. Further, instead of the CPU 10a, it may be configured by a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), or the like. Alternatively, the processing may be performed on the computer on the server by a general-purpose processor or cloud computing that executes a function by loading a software program. Further, in FIG. 3, the ROM 10b and the RAM 10c are provided, but for example, a storage device other than these (for example, an HDD (Hard Disk Drive) which is a magnetic storage device) may be used.

(B) Description of Operation of Embodiment of the Present Invention Next, the operation of the embodiment of the present invention will be described. In the following, after explaining the operation of the embodiment of the present invention, the processing of the flowchart for realizing such an operation will be described.

First, the outline of the operation of the embodiment of the present invention will be described. When the engine 17 of the vehicle is started by operating an ignition switch (not shown) by the user, the CPU 10a of the control unit 10 outputs the temperature output from the temperature sensors 13-1 and 13-2 via the I / F 10e. Input the signal.

Here, the temperature sensor 13-1 detects the temperature of the cell 141 of the electrolytic cell 140, and the temperature sensor 13-2 detects and outputs the temperature of the cell 146 of the electrolytic cell 140. The CPU 10a acquires the temperature θ1 indicated by the temperature signal supplied from the temperature sensor 13-1, and also acquires the temperature θ2 indicated by the temperature signal supplied from the temperature sensor 13-2.

Next, the CPU 10a integrates the temperatures θ1 and θ2 with time. For example, when the temperatures θ1 and θ2 are acquired in a predetermined period (ΔT), the calculation result of θ1 × ΔT is cumulatively added to the variable C1 (C1 ← C1 + θ1 × ΔT is calculated), and the variable C2 is calculated. On the other hand, the calculation result of θ2 × ΔT is cumulatively added (C2 ← C2 + θ2 × ΔT is calculated). Then, the CPU 10a stores the obtained values of C1 and C2 in the RAM 10c as data 10ca.

The above operation is repeatedly executed until the engine 17 is stopped or the temperatures of the temperature sensors 13-1 and 13-2 reach a predetermined temperature (for example, the same as the outside air temperature).

When a predetermined time (for example, several hours) has elapsed since the engine 17 was stopped, the CPU 10a supplies a control signal to the discharge circuit 15 via the I / F 10e to discharge the lead-acid battery 14, for example, in a pulsed manner. , Receives voltage and current signals from the voltage sensor 11 and the current sensor 12. Instead of being discharged by the discharge circuit 15, the voltage signal and the current signal may be acquired, for example, when the engine 17 is started by the starter motor 18 or when a current flows through the load 19.

Next, the CPU 10a calculates the values of the elements constituting the equivalent circuit of the lead-acid battery 14. More specifically, as the equivalent circuit of the lead storage battery 14, for example, there is an equivalent circuit shown in FIG. In the example of FIG. 4, the equivalent circuit consists of Rohm, which is a resistance component corresponding to the conductor element and electrolyte resistance inside the lead-acid battery 14, and Rct1 and Rct2, which are resistance components corresponding to the reaction resistance of the active material reaction of the electrode. It has Cd1 and Cd2 which are capacitive components corresponding to the electric double layer at the interface between the electrode and the electrolytic solution. The CPU 10a finds the equivalent circuit of the lead-acid battery 14 shown in FIG. 4 by a learning process or a fitting process, and calculates the values of the elements constituting the equivalent circuit.

Next, the CPU 10a acquires C1 and C2 calculated during the operation of the engine 17 from the RAM 10C. Then, for example, it is determined whether or not C1 and C2 are different by a predetermined threshold value or more.

Here, C1 and C2 are different, for example, when the lead-acid battery 14 is arranged in a place where the heat from the engine 17 is received, so that one of the cells 141 and 146 is close to the engine 17. It is when it is placed.

More specifically, for example, when the cell 141 is arranged so as to be closer to the engine 17 than the cell 146, the temperature of the cell 141 becomes higher than that of the cell 146 during the operation of the engine 17. It's time.

In such a case, the lead-acid battery 14 deteriorates faster in the cell having a high temperature than in the cell having a low temperature. Specifically, according to the Arrhenius equation, the life is halved when the temperature rises by 10 ° C.

It is known that the internal resistance of the lead-acid battery 14 increases as the deterioration of the cell electrodes progresses. Further, in the lead-acid battery 14 having a plurality of cells 141 to 146, the capacity of the most deteriorated cell determines the capacity of all cells. That is, when the capacity of one cell with the most deteriorated deterioration is 40 Ah and the capacities of the other cells are all 50 Ah, the discharge becomes impossible when the discharge of 40 Ah is completed. Therefore, 40 Ah is regarded as all cells. It becomes the capacity.

By the way, conventionally, as shown in the upper part of FIG. 5, when the resistance between terminals of the lead-acid battery 14 is measured as 6Y [Ω], it is assumed that the internal resistance of each cell is equal, and in the middle part of FIG. As shown, the internal resistance of all cells was estimated to be Y [Ω] (6Y / 6). Further, as shown in the lower part of FIG. 5, the capacity of each cell was also set to X [Ah] on the assumption that they were all equal.

However, in the lead-acid battery 14 shown in the upper part of FIG. 6, when the cell on the left side of the figure is arranged so as to be closer to the engine 17 than the cell on the right side, and the deterioration progresses, As shown in the middle part of FIG. 6, the value of the internal resistance of each cell may decrease from left to right. That is, the cell on the left is deteriorated and the resistance value is increased. Further, in this case, as shown in the lower part of FIG. 6, the capacity is smaller toward the left cell. Specifically, the capacity of the leftmost cell is X / 2 [Ah], and the capacity of the rightmost cell is X / 0.4 [Ah].

In the case of FIG. 6, since the capacity of the cell having the smallest capacity is the capacity of the entire cell, X / 2 [Ah] is the capacity of the entire cell.

When the temperature difference between the cells is small (for example, when the lead-acid battery 14 is arranged at a position sufficiently distant from the engine 17 or when it is arranged near the engine 17, all the cells are used. When are arranged so as to have substantially the same temperature distribution), as shown in FIG. 5, the temperatures of all the cells are substantially the same, and the deterioration due to the temperature progresses evenly. In such a case, the internal resistance and capacity of the cell can be determined by the same method as before.

By comparing C1 and C2, if they do not differ by more than a predetermined threshold value, for example, ABS () is a function for obtaining the absolute value in parentheses, and when the threshold value is Th, ABS (1-C1 / C2). When <Th (for example, Th = 0.1) is satisfied, it is determined that the difference is not more than a predetermined threshold value, and the temperature between the cells is determined to be substantially constant. In this case, when the internal resistance of the entire cell is 6Y, the internal resistance of each cell is determined to be Y.

On the other hand, when it is determined that the temperature between cells is not constant (there is a variation in temperature) and the internal resistance of the entire cell is 6Y, if the internal resistance of cells 141 to 146 is R1 to R6, the inside The resistances R1 to R6 can be obtained by the following formula. Note that f1 (C1, C2) to f6 (C1, C2) are predetermined functions with C1 and C2 as variables. More specifically, f1 () to f6 () become f1 () = f2 () = f3 () = f4 () = f5 () = f6 () = 1/6 when C1 = C2. In the case of C1> C2, f1 ()> f2 ()> f3 ()> f4 ()> f5 ()> f6 (), and in the case of C1 <C2, f1 () <f2 () <f3 () It is a function such that <f4 () <f5 () <f6 (). Note that these functions can be obtained, for example, by actual measurement. Alternatively, it can be obtained using a thermal equivalent circuit of the lead-acid battery 14 (a circuit in which an object is modeled by thermal resistance and heat capacity).

R1 = 6Y × f1 (C1, C2) ... (1)
R2 = 6Y × f2 (C1, C2) ・ ・ ・ (2)
R3 = 6Y × f3 (C1, C2) ・ ・ ・ (3)
R4 = 6Y × f4 (C1, C2) ・ ・ ・ (4)
R5 = 6Y x f5 (C1, C2) ... (5)
R6 = 6Y × f6 (C1, C2) ・ ・ ・ (6)

Next, the CPU 10a selects the one having the largest value from R1 to R6, estimates the cell capacity based on the selected internal resistance value, and uses the cell capacity as the capacity of the lead-acid battery 14. presume. For example, the OCV (Open Circuit Voltage) for each cell can be calculated based on the internal resistance for each cell, and the capacity (SOC: State of Charge) for each cell can be obtained from the OCV.

The CPU 10a adjusts the generated voltage of the alternator 16 based on the cell capacity calculated in this way, and controls the lead-acid battery 14 so that it is fully charged or close to it. Alternatively, the CPU 10a notifies the ECU (not shown) of the cell capacity calculated in this way via the communication unit 10d, and the ECU adjusts the generated voltage of the alternator 16 with reference to the cell capacity. , The lead storage battery 14 is controlled so as to be fully charged or close to it.

As a result, even when the progress of deterioration differs between cells due to the difference in temperature between the cells of the lead-acid battery 14, the state of the cells can be known and the variation between cells is taken into consideration. Therefore, the charge / discharge control of the lead storage battery 14 can be performed. As a result, it is possible to prevent the capacity of the lead storage battery 14 from decreasing and the engine 17 from being unable to start. Further, if the capacity of the lead storage battery 14 continues to be low, it is possible to suppress the progress of deterioration.

Next, an example of the processing executed in the embodiment of the present invention will be described with reference to FIGS. 7 and 8.

FIG. 7 is a flowchart executed when the engine 17 is started. When the processing of the flowchart shown in FIG. 7 is started, the following steps are executed.

In step S10, the CPU 10a determines, for example, whether or not the ignition key is operated by the user to start the engine 17, and if it is determined that the engine 17 has been started (step S10: Y), the process proceeds to step S11. , In other cases (step S10: N), the process ends.

In step S11, the CPU 10a receives the temperature signal output from the temperature sensor 13-1 via the I / F 10e and acquires the temperature θ1. For example, the temperature θ1 of the cell 141 is acquired from the temperature sensor 13-1 shown in FIG.

In step S12, the CPU 10a receives the temperature signal output from the temperature sensor 13-2 via the I / F 10e and acquires the temperature θ2. For example, the temperature θ2 of the cell 146 is acquired from the temperature sensor 13-2 shown in FIG.

In step S13, the CPU 10a obtains the product (θ1 × ΔT) of the temperature θ1 acquired in step S11 and the temperature sampling period ΔT, and cumulatively adds it to the variable C1 (calculates C1 ← C1 + θ1 × ΔT). As a result, the values corresponding to the time integration of the temperature θ1 are sequentially stored in the variable C1.

In step S14, the CPU 10a obtains the product (θ2 × ΔT) of the temperature θ2 acquired in step S12 and the temperature sampling period ΔT, and cumulatively adds it to the variable C2 (calculates C2 ← C2 + θ2 × ΔT). As a result, the values corresponding to the time integration of the temperature θ2 are sequentially stored in the variable C2.

In step S15, the CPU 10a stores the values of C1 and C2 obtained in steps S13 and S14 in the RAM 10c as data 10ca.

In step S16, the CPU 10a determines whether or not the sampling time ΔT has elapsed, and if it determines that ΔT has elapsed (step S16: Y), the process proceeds to step S17, and in other cases (step S16). : N) repeats the same process.

In step S17, for example, the CPU 10a determines whether or not the ignition key is operated by the user to stop the engine 17, and if it is determined that the engine 17 has been stopped (step S17: Y), the process ends. In other cases (step S17: N), the process returns to step S11 and the same process as described above is repeated. The process is not terminated when the engine 17 is stopped, but is performed when the temperature of the engine 17 becomes equal to the ambient temperature or when the difference from the ambient temperature becomes equal to or less than a predetermined threshold value. It may be terminated.

Next, an example of processing executed after the engine is stopped will be described with reference to FIG. When the processing of the flowchart shown in FIG. 8 is started, the following steps are executed.

In step S30, for example, the CPU 10a determines whether or not the ignition key is operated by the user to stop the engine 17, and if it is determined that the engine 17 has been stopped (step S30: Y), the process proceeds to step S31. , In other cases (step S30: N), the process ends.

In step S31, the CPU 10a determines whether or not a predetermined time (for example, several hours in which the stratification of the lead storage battery 14 is eliminated) has elapsed since the engine 17 was stopped, and the predetermined time has elapsed. If it is determined (step S31: Y), the process proceeds to step S32, and in other cases (step S31: N), the same process is repeated.

In step S32, the CPU 10a supplies a control signal to the discharge circuit 15 to start pulse discharge of the lead-acid battery 14. Instead of being discharged by the discharge circuit 15, for example, the discharge by the starter motor 18 or the load 19 may be used.

In step S33, the CPU 10a receives a voltage signal from the voltage sensor 11 and detects the terminal voltage V of the lead-acid battery 14.

In step S34, the CPU 10a receives the current signal from the current sensor 12 and detects the current I flowing through the lead-acid battery 14.

In step S35, the CPU 10a determines whether or not a predetermined time (for example, 100 ms to several seconds) has elapsed, and if it is determined that a predetermined time has elapsed (step S35: Y), the process proceeds to step S36. In other cases (step S35: N), the process returns to step S33 and the same process is repeated. By repeating steps S33 to S35, the lead-acid battery 14 is repeatedly pulse-discharged, and the voltage and current at that time are measured.

In step S36, the CPU 10a supplies a control signal to the discharge circuit 15 to end the pulse discharge of the lead-acid battery 14.

In step S37, the CPU 10a calculates, for example, the values of the elements constituting the equivalent circuit of the lead-acid battery 14 shown in FIG. For example, the CPU 10a finds the equivalent circuit of the lead-acid battery 14 shown in FIG. 4 by learning processing or fitting processing, calculates the value of the element of the equivalent circuit, and optimizes it. As an optimization method, for example, as described in Japanese Patent No. 4532416, the optimum state vector X is estimated by the extended Kalman filter operation, and the adjustment parameter (component) of the equivalent circuit is obtained from the estimated state vector X. Update to the optimal one. More specifically, based on an equivalent circuit using the adjustment parameters obtained from the state vector X in a certain state, the voltage drop ΔV when the secondary battery is discharged with a predetermined current pattern is calculated, and this approaches the measured value. The state vector X is updated as follows. Then, the optimum adjustment parameter is calculated from the state vector X optimized by the update. Alternatively, as described in WO2014 / 136593, at the time of pulse discharge of the lead-acid battery 14, the time change of the voltage value is acquired, and the obtained change of the voltage value is fitted by a predetermined function with time as a variable. Therefore, the parameters of the predetermined function can be calculated, and the components of the equivalent circuit of the lead-acid battery 14 can be obtained based on the calculated parameters of the predetermined function. Of course, methods other than these may be used.

In step S38, the CPU 10a reads out the values of C1 and C2 stored in the RAM 10c by the process shown in FIG. 7.

In step S39, the CPU 10a executes a process of correcting the internal resistance of each cell based on C1 and C2 read in step S38. For example, the value (6Y) of the internal resistance as the total value of Rohm, Rct1, and Rct2 shown in FIG. 4 is corrected for each cell based on C1 and C2 by the formulas (1) to (6). ..

In step S40, the CPU 10a calculates SOC and SOH based on the corrected internal resistance value for each cell. More specifically, the OCV for each cell can be calculated based on the internal resistance for each cell, and the SOC for each cell can be obtained from the OCV. Further, the SOH for each cell can be obtained by referring to the formula or table showing the relationship between the value of the internal resistance for each cell and the deterioration characteristic. Of course, SOC and SOH may be obtained by a method other than these. The SOF (State of Function) indicating the starting performance of the engine 17 may be calculated based on the internal resistance.

In step S41, the CPU 10a executes control based on the SOC and SOH for each cell obtained in step S40. For example, by executing charge control based on the minimum SOC, the charge state can be maintained properly. Further, by determining the deterioration state based on the minimum SOH, it is possible to accurately notify the user of the replacement time of the lead storage battery 14. Further, by executing the charge control based on the minimum SOF, it is possible to prevent the engine 17 from being unable to restart. Note that step S41 is not executed by the CPU 10a, but the CPU 10a supplies the SOC and SOH for each cell obtained in step S40 to the upper control device (for example, ECU), and the upper control device supplies the SOC and SOH. Based on this, the above-described processing may be executed.

As described above, according to the embodiment of the present invention, the state of the lead-acid battery 14 can be accurately detected even when there is a temperature variation between the cells 141 to 146 of the lead-acid battery 14. Can be done. As a result, the charging / discharging of the lead storage battery 14 can be reliably controlled, so that the operation of the vehicle can be stabilized.

(C) Description of Modified Embodiment The above embodiment is an example, and it goes without saying that the present invention is not limited to the cases described above. For example, in the above embodiment, as shown in FIG. 2, two temperature sensors 13-1 and 13-2 are provided on the surfaces 14a and 14b of the electrolytic cell 140 of the lead-acid battery 14, respectively. As shown in FIG. 9, in addition to the two surfaces 14a and 14b, the surface 14c (front surface parallel to the YZ plane), the surface 14d (back surface parallel to the YZ plane), and the surface 14e (electrolysis). Temperature sensors indicated by circles may be provided at six locations on the upper surface of the tank 140 and the surface 14f (bottom surface of the electrolytic cell 140). In this way, when six temperature sensors are used, the direction in which the heat source exists can be predicted by referring to the temperatures of the opposing surfaces, so that the temperatures of cells 141 to 146 can be estimated more accurately. it can.

FIG. 10 is a diagram showing an example of heat distribution of the lead-acid battery 14 when heat sources are present in various directions. In addition, in FIG. 10, the line described in the lead storage battery 14 shows the contour line of heat. The thick line shows the highest temperature contour line closest to the heat source. Here, FIG. 10A shows contour lines when the heat source exists in the vicinity of the apex V1 of the electrolytic cell 140. Further, FIG. 10B shows a case where the heat source exists in the vicinity of the side S1 parallel to the X axis. Further, FIG. 10C shows a case where the heat source exists in the vicinity of the side S2 parallel to the Y axis. For example, by providing a plurality of sensors as shown in FIG. 9, the temperature of cells 141 to 146 can be estimated more accurately even when heat sources are present at various positions as shown in FIG. ..

FIG. 11 shows an embodiment in which a temperature sensor is provided for each of the cells 141 to 146. In the example of FIG. 11, a temperature sensor indicated by a circle is provided near the center of each of the cells 141 to 146 on the surface 14c in the Y-axis direction and near the center in the Z-axis direction. According to such an embodiment, the temperature of each cell can be detected, so that the temperature of the intermediate cells 142 to 145 is estimated from the temperatures of the cells 141 and 146 at both ends. The temperature of cells 142 to 145 can be accurately determined.

In the example of FIG. 11, when the values obtained by time-integrating the temperatures of cells 141 to 146 are C1 to C6, the above-mentioned equations (1) to (6) are, for example, the following equations ( 7) can be replaced with the formula (12). In the case of C1 = C2 = C3 = C4 = C5 = C6, f11 () to f16 () become f11 () to f16 () = 1/6, depending on the relative magnitude relationship of C1 to C6. It is a function whose value changes (for example, when C1 is relatively larger than C2 to C6, the value of f11 () is relatively larger than the values of f12 () to f16 ()).

R1 = 6Y × f11 (C1, C2, C3, C4, C5, C6) ... (7)
R2 = 6Y × f12 (C1, C2, C3, C4, C5, C6) ... (8)
R3 = 6Y × f13 (C1, C2, C3, C4, C5, C6) ... (9)
R4 = 6Y × f14 (C1, C2, C3, C4, C5, C6) ... (10)
R5 = 6Y × f15 (C1, C2, C3, C4, C5, C6) ... (11)
R6 = 6Y × f16 (C1, C2, C3, C4, C5, C6) ... (12)

Further, in the above embodiment, the case where the cell temperature rises due to the heat from the heat source existing outside the lead storage battery 14 has been described as an example, but the cell temperature is generated by the heat generated by the lead storage battery 14 itself. May rise. More specifically, there are two types of heat generated by the lead-acid battery 14. One is Joule heat generated by passing an electric current through the internal resistance, and the other is heat generated by an electrochemical reaction. Here, since the value of the internal resistance of the cell increases as the deterioration progresses, the Joule heat is generated more as the cell deteriorates.

When the temperature of a cell rises due to heat from an external heat source, the temperature of the cell at the end close to the heat source is generally the highest because the heat is transferred from the cell close to the heat source and the temperature rises. However, in the case of heat generated from the lead-acid battery 14 itself, especially for Joule heat, the amount of heat generated differs depending on the deterioration, so that the temperature of the cells other than the end portion may be the highest.

In the embodiment shown in FIG. 2, heat is transferred from an external heat source to one cell at both ends, and heat is transferred to the other cell at both ends. Therefore, when the heat generation of the intermediate cell is relatively larger than that of the other cells, it becomes difficult to accurately determine the temperature of each cell.

On the other hand, in the case of the embodiment shown in FIG. 11, the temperature of each cell can be accurately measured even when the cells generate heat. For example, even when the deterioration of cell 143, which is an intermediate cell, progresses and the amount of heat generated by cell 143 is the largest, the temperature of cell 143 is required to be high, and the other cells 141 to 142, 144 to The temperature of 146 can also be accurately determined. In the example shown in FIG. 11, the temperature sensor is provided only on the surface 14c, but the temperature sensor is provided on each cell on the back surface 14d as well as the surface 14c. You may. According to such a configuration, the temperature of the cell can be detected more accurately by obtaining the temperature with two temperature sensors for each cell and obtaining the average value of the obtained temperatures.

FIG. 12 shows an embodiment in which the temperature sensor is further increased. In the example of FIG. 12, three temperature sensors are juxtaposed in the Z-axis direction with respect to the cells of the surfaces 14c and 14d. Further, three sensors are juxtaposed in the X-axis direction and three sensors in the Z-axis direction with respect to the surfaces 14a and 14b.

By arranging a large number of temperature sensors in this way, for example, it becomes possible to accurately detect the temperature distribution as shown in FIG. Further, by arranging a plurality of temperature sensors in the vertical direction (Z-axis direction), stratification can be detected. That is, when stratification occurs, the electrolytic solution (sulfuric acid) having a high concentration is accumulated in the lower part in the Z-axis direction, so that the heat of chemical reaction is generated relatively in this portion. Therefore, the stratified state can be detected by detecting and comparing the temperatures in the vertical direction. Then, by correcting the value of the internal resistance for each cell (the value of R1 to R6 obtained by the formulas (7) to (12)) in consideration of the stratified state, a more accurate value of the internal resistance is obtained. Can be obtained.

In FIG. 12, the temperature sensors are provided on all the surfaces 14a, 14b, 14c, 14d, but they may be provided on only one of the opposing surfaces 14a, 14b and 14c, 14d. Further, it may not be provided on the surfaces 14a and 14b. Further, one temperature sensor may be provided only at the lowermost portion (a portion where the influence of stratification is likely to appear) in one cell.

FIG. 13 shows another embodiment. In the example shown in FIG. 13, one temperature sensor is arranged at the center of the surface 14c and the surface 14b, and four temperature sensors are arranged near the four corners of the surface.

In the embodiment shown in FIG. 13, two temperature sensors are arranged in the vertical direction of the cells 141 and 146 on the surface 14c, and five temperature sensors are arranged on the surface 14a and 14b to provide an external heat source. The temperatures of the cells 141 and 146 at both ends, which are susceptible to the above, can be accurately detected. Further, by arranging two temperature sensors in the vertical direction of the cells 141 and 146 at both ends and arranging two temperature sensors in the vertical direction on the surface 14a and the surface 14b, it is possible to accurately detect stratification. it can. Further, since the temperature sensor is arranged near the center of the surface 14c, it is possible to detect the temperature of the intermediate cells 143 and 144 and know whether or not an influence other than the external heat source is occurring.

FIG. 14 shows another embodiment. In the example of FIG. 14, the temperature sensor is arranged inside the cover 20 (for example, the cover for protecting the lead storage battery 14 from high temperature / low temperature) accommodating the lead storage battery 14. More specifically, in the example of FIG. 14, six temperature sensors are arranged inside the cover 20 so as to correspond to the positions of cells 141 to 146. Further, three temperature sensors are arranged at positions corresponding to the surface 14a of the lead storage battery 14. By providing the temperature sensor inside the cover 20 in this way, it is possible to suppress heat transfer from the heat source and detect the state of each cell. In the example of FIG. 14, six temperature sensors are provided on the surface in contact with the surface 14c, and three temperature sensors are provided on the surface in contact with the surface 14a, but other numbers are arranged. May be good.

In the above embodiment, the equivalent circuit shown in FIG. 4 is used, but other equivalent circuits may be used. For example, Rct1, Cd1 and Rct2, Cd2 may be only one equivalent circuit, or may be three or more equivalent circuits. Further, it may be an equivalent circuit having only resistors Rohm, Rct1 and Rct2, or an equivalent circuit in which these three resistors are used as one resistor.

Further, in the above embodiment, the internal resistance is obtained by referring to the time integral value of the cell temperature, but the electric double layer capacitances Cd1 and Cd2 shown in FIG. 4 may be obtained. Further, the temperature detected by the temperature sensors 13-1 and 13-2 may be simply added instead of being time-integrated.

Further, the flowcharts shown in FIGS. 7 and 8 are examples, and the present invention is not limited to the processing of these flowcharts.

1 Lead-acid battery status detector 10 Control unit 10a CPU
10b ROM
10c RAM
10d communication unit 10e I / F
11 Voltage sensor 12 Current sensor 13-1, 13-2 Temperature sensor 14 Lead-acid battery 15 Discharge circuit 16 Alternator 17 Engine 18 Starter motor 19 Load

Claims (10)

In a lead-acid battery state detection device that detects the state of an in-vehicle lead-acid battery having electrolytic cells partitioned into a plurality of cells.
With the processor
It has a memory for storing a program that realizes the following functions when executed by the processor.
A voltage signal from a voltage sensor that detects the terminal voltage of the lead-acid battery, a current signal from the current sensor that detects the charge / discharge current of the lead-acid battery, and a temperature sensor that detects the temperature of a plurality of locations in the electrolytic tank. Receive the temperature signal,
The value of the element constituting the equivalent circuit of the lead-acid battery is calculated based on the voltage signal and the current signal during discharge of the lead-acid battery.
The calculated values of the elements constituting the equivalent circuit are corrected based on the temperature signals indicating the temperatures of the plurality of locations in the electrolytic cell.
Based on the corrected element value, the state of the lead-acid battery is detected.
Outputs the detected state of the lead-acid battery,
A lead-acid battery state detection device characterized by this. The temperature sensor is arranged so as to be able to detect the temperature of cells located at both ends of the electrolytic cell, and detects a temperature rise due to heat generated from a vehicle prime mover of the cells located at both ends. The lead-acid battery state detector according to. The lead-acid battery state according to claim 1 or 2, wherein the temperature sensor is arranged so as to be able to detect the temperature of a plurality of cells in the electrolytic cell, and detects a temperature rise due to the progress of deterioration of the cells. Detection device. The lead-acid battery state detection device according to any one of claims 1 to 3, wherein the value of an element of the equivalent circuit is corrected based on a value obtained by time-integrating a temperature signal from the temperature sensor. The lead-acid battery state detection device according to claim 4, wherein the values of the elements of the equivalent circuit are distributed to the respective cells based on the values obtained by integrating the temperature signals over time. The lead-acid battery state detection device according to claim 5, wherein the dischargeable capacity of each cell is corrected based on the value of the element distributed to each cell. The temperature signal from the temperature sensor arranged one by one for each cell is received, and the temperature signal is received.
The lead-acid battery state detection device according to any one of claims 1 to 6, wherein the value of an element of the equivalent circuit is corrected based on the temperature signal from each cell. Upon receiving the temperature signals from at least two temperature sensors arranged vertically spaced apart from the electrolytic cell,
The temperature difference in the vertical direction of the electrolytic cell is detected based on the temperature signal, the degree of stratification of the electrolytic solution is detected based on the detected temperature difference, and the value of the element is corrected based on the degree of stratification. The lead storage battery state detecting device according to any one of claims 1 to 7, wherein the lead storage battery state detecting device is characterized. The lead-acid battery state detecting device according to any one of claims 1 to 8, wherein the temperature sensor is arranged in a cover accommodating the lead-acid battery. In a lead-acid battery state detection method for detecting the state of an in-vehicle lead-acid battery having electrolytic cells partitioned into a plurality of cells.
At least the voltage signal from the voltage sensor that detects the terminal voltage of the lead-acid battery, the current signal from the current sensor that detects the charge / discharge current of the lead-acid battery, and the temperature of the cells located at both ends of the electrolytic tank. The temperature signals from the two temperature sensors are received by a system with a processor and
The system calculates the values of the elements constituting the equivalent circuit of the lead-acid battery based on the voltage signal and the current signal during discharge of the lead-acid battery.
The calculated value of the element constituting the equivalent circuit is corrected by the system based on the temperature difference between the cells located at both ends of the received element.
The state of the lead-acid battery is detected by the system based on the corrected element value.
The detected state of the lead-acid battery is output by the system.
A lead-acid battery state detection method characterized by this.

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