JP6210552B2 - Secondary battery state detection device and secondary battery state detection method - Google Patents

Description

  The present invention relates to a secondary battery state detection device and a secondary battery state detection method.

  In Patent Document 1, the pure resistance component and the polarization resistance component of the secondary battery are calculated from the current and voltage at the time of starting the engine of the automobile, and the secondary battery is compared by comparing the pure resistance component and the polarization resistance component with a new one. A technique for determining the deterioration of an image is disclosed.

JP 2003-177164 A

  By the way, in order to accurately determine the SOC (State of Charge) or SOH (State of Health) of the secondary battery, it is necessary to perform correction based on the polarization voltage or polarization amount and the stratification voltage or stratification amount. The coefficient for performing such correction varies depending on the size (initial full charge capacity) of the secondary battery. In the conventional technology as shown in Patent Document 1, assuming that a secondary battery of a predetermined size is used, correction is performed using a correction coefficient corresponding to the secondary battery of the predetermined size. It was.

  For this reason, when the battery is replaced with a secondary battery having a size different from the predetermined size, the correction cannot be performed with high accuracy, so that the state of the secondary battery cannot be accurately detected. is there.

  An object of the present invention is to provide a secondary battery state detection device and a secondary battery state detection method capable of estimating an initial full charge capacity or size of a secondary battery.

In order to solve the above-described problems, the present invention provides a secondary battery state detection device for detecting a state of a secondary battery mounted on a vehicle, wherein a value of a current flowing through the secondary battery and a voltage of the secondary battery are determined. A detecting means for detecting a value, a voltage value and a current value before discharging of the secondary battery are detected by the detecting means, and a voltage value and a current value during discharging of the secondary battery are detected by the detecting means. , Based on these voltage value and current value, a obtaining means for obtaining a value relating to the reaction resistance of the secondary battery, a value relating to the reaction resistance obtained by the obtaining means, and the secondary battery And an estimation means for estimating the initial full charge capacity based on the correlation of the initial full charge capacity.
According to such a configuration, it is possible to estimate the initial full charge capacity or size of the secondary battery.

According to the present invention, the obtaining means detects the voltage value and current value before rotation of the starter motor for starting the engine of the vehicle by the detection means, and the secondary battery during rotation of the starter motor. A voltage value and a current value of the secondary battery are detected by the detection means, and a value relating to a reaction resistance of the secondary battery is obtained based on the voltage value and the current value.
According to such a configuration, it is possible to stably estimate the initial full charge capacity of the secondary battery by using the rotation of the starter motor in which a certain amount of current flows for a certain period of time.

Further, according to the present invention, the obtaining means obtains a voltage value of a difference between the voltage value before the discharge of the secondary battery and the voltage value during the discharge, and the current value before the discharge of the secondary battery and the discharge of the secondary battery. A current value of a difference between the current values is obtained, and a value obtained by dividing the voltage value of the difference by the current value of the difference is set as a value related to the reaction resistance.
According to such a configuration, the initial full charge capacity can be accurately obtained based on the voltage value and current value before and after discharging of the secondary battery.

Further, according to the present invention, the obtaining means obtains a voltage value of a difference between the voltage value before the discharge of the secondary battery and the voltage value immediately after the start of the discharge, and the current value and the discharge before the discharge of the secondary battery. The difference current value immediately after the start is obtained, the voltage value obtained by dividing the difference voltage value by the difference current value is defined as a first resistance value, and the secondary battery is discharged from the voltage value before discharging. Obtaining the voltage value of the difference between the voltage values after immediately after the start and obtaining the current value of the difference between the current value before the discharge of the secondary battery and the current value after immediately after the start of the discharge, and the voltage value of the difference The value obtained by dividing the current value by the difference is the second resistance value, and the value obtained by subtracting the first resistance value from the second resistance value is the value related to the reaction resistance. Features.
According to such a configuration, the initial full charge capacity can be obtained with higher accuracy by reducing the influence of the conductor resistance.

Further, according to the present invention, the estimation unit is configured to use the secondary function based on a linear function indicating a relationship between a value relating to the reaction resistance obtained by the obtaining unit and an initial full charge capacity value of the secondary battery. An initial full charge capacity value of the battery is estimated.
According to such a configuration, by using a linear function, the initial full charge capacity can be obtained with high accuracy with a simple calculation.

Further, the present invention provides a detection step of detecting a value of a current flowing through the secondary battery and a voltage value of the secondary battery in a secondary battery state detection method for detecting a state of a secondary battery mounted on a vehicle. And detecting the voltage value and current value before discharging of the secondary battery in the detecting step, and detecting the voltage value and current value during discharging of the secondary battery in the detecting step. Based on the current value, a obtaining step for obtaining a value relating to the reaction resistance of the secondary battery, a value relating to the reaction resistance obtained in the obtaining step, an initial full charge capacity of the secondary battery, And an estimation step for estimating the initial full charge capacity based on the correlation of the first full charge capacity.
According to such a method, it is possible to estimate the initial full charge capacity or size of the secondary battery.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the secondary battery state detection apparatus and secondary battery state detection method which can detect the initial full charge capacity or size of a secondary battery.

It is a figure which shows the structural example of the secondary battery state detection apparatus which concerns on 1st Embodiment of this invention. It is a block diagram which shows the detailed structural example of the control part of FIG. It is a figure which shows the time change of resistance at the time of discharging a secondary battery. It is a figure which shows the time change of the electric current when rotating a starter motor. It is a figure which shows the relationship between reaction resistance and initial stage full charge capacity. It is a figure which shows the relationship between the estimated value of SOH by 1st Embodiment, and an actual value. It is a flowchart for demonstrating an example of the process performed in 1st Embodiment. It is a figure which shows the time change of resistance at the time of discharging a secondary battery. It is a flowchart for demonstrating an example of the process performed in 2nd Embodiment. It is a figure which shows the relationship between reaction resistance and initial stage full charge capacity. It is a flowchart for demonstrating an example of the process performed in deformation | transformation embodiment.

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

(A) Description of Configuration of First Embodiment FIG. 1 is a diagram showing a power supply system of a vehicle having a secondary battery state detection device according to the first embodiment of the present invention. In this figure, the secondary battery state detection device 1 includes a control unit 10, a voltage sensor 11, a current sensor 12, a temperature sensor 13, and a discharge circuit 15 as main components, and detects the state of the secondary battery 14. To do. Here, the control unit 10 refers to outputs from the voltage sensor 11, the current sensor 12, and the temperature sensor 13 to detect the state of the secondary battery 14. The voltage sensor 11 detects the terminal voltage of the secondary battery 14 and notifies the control unit 10 of it. The current sensor 12 detects the current flowing through the secondary battery 14 and notifies the control unit 10 of the current. The temperature sensor 13 detects the secondary battery 14 itself or the surrounding environmental temperature, and notifies the control unit 10 of it. The discharge circuit 15 is configured by, for example, a semiconductor switch and a resistance element connected in series, and the secondary battery 14 is intermittently discharged when the control unit 10 performs on / off control of the semiconductor switch.

  The secondary battery 14 is composed of, for example, a lead storage battery, a nickel cadmium battery, a nickel hydrogen battery, or a lithium ion battery, and is charged by the alternator 16 to drive the starter motor 18 to start the engine and load 19 To supply power. The alternator 16 is driven by the engine 17 to generate AC power, convert it into DC power by a rectifier circuit, and charge the secondary battery 14.

  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. Drive to generate power. The starter motor 18 is constituted by, for example, a DC motor, generates a rotational force by the electric power supplied from the secondary battery 14, and starts the engine 17. The load 19 is configured by, for example, an electric steering motor, a defogger, an ignition coil, a car audio, a car navigation, and the like, and operates with electric power from the secondary battery 14. An electric motor may be used instead of the engine 17.

  FIG. 2 is a diagram illustrating a detailed configuration example of the control unit 10 illustrated in FIG. 1. As shown in this figure, the control unit 10 includes a CPU (Central Processing Unit) 10a, a ROM (Read Only Memory) 10b, a RAM (Random Access Memory) 10c, a communication unit 10d, and an I / F (Interface) 10e. ing. Here, the CPU 10a controls each unit based on the program 10ba stored in the ROM 10b. The ROM 10b is configured by a semiconductor memory or the like, and stores a program 10ba or the like. The RAM 10c is configured by a semiconductor memory or the like, and stores data generated when the program ba is executed, and a parameter 10ca such as a table or a mathematical expression described later. The communication unit 10d communicates with an ECU (Electronic Control Unit) that is a host device and notifies the host device of the detected information. The I / F 10e converts the signal supplied from the voltage sensor 11, the current sensor 12, and the temperature sensor 13 into a digital signal and takes it in, and supplies a driving current to the discharge circuit 15 to control it.

(B) Description of Operation Principle of First Embodiment Next, the operation principle of the first embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a diagram showing temporal changes in the resistance value of the secondary battery 14 when the secondary battery 14 is discharged. In FIG. 3, the horizontal axis represents time (s), and the vertical axis represents resistance (Ω). A solid line curve indicates a temporal change in the resistance value of the secondary battery. When the discharge is started at the timing t0, as shown in FIG. 3, the resistance value of the secondary battery 14 increases as time passes, and becomes constant when a predetermined time elapses. Here, the resistance during discharge of the secondary battery 14 has a reaction resistance which is a resistance component resulting from a chemical reaction, and this reaction resistance is between the size of the secondary battery (initial full charge capacity). It has been clarified by experiments of the present inventor that it has a high correlation. Therefore, in the present embodiment, a resistance value (Z shown in FIG. 3) at the time of discharging the secondary battery 14 is obtained, and the size of the secondary battery 14 is estimated from the obtained resistance value. And the state (for example, SOC or SOH) of the secondary battery 14 can be estimated with higher accuracy by referring to the estimated size and selecting an optimal correction coefficient. In the first embodiment, the “value relating to the reaction resistance” indicates a resistance value when the secondary battery 14 is discharged.

  Next, a more detailed operation of the embodiment of the present invention will be described. For example, when the secondary battery 14 is replaced with a new one by the user or the like, the CPU 10a of the control unit 10 controls the discharge circuit 15 to pulse discharge the secondary battery 14 at a predetermined cycle, and the voltage at that time The current and the temperature are detected by the voltage sensor 11, the current sensor 12, and the temperature sensor 13, and the SOC of the secondary battery 14 is calculated based on the detected values.

  Then, the CPU 10a refers to the calculated SOC, and executes the following process when the secondary battery 14 is in a fully charged state (SOC = 100%), and otherwise, the secondary battery. Wait until 14 is fully charged. The reason for waiting until the battery is fully charged is that the measurement accuracy is higher when the measurement is performed under the same SOC condition. Of course, the measurement may be performed based on a predetermined SOC (for example, 90%).

  When the secondary battery 14 is fully charged, the process waits until the secondary battery 14 is discharged. For example, it waits until the starter motor 18 is rotated, and if the user turns on the ignition, it determines that the starter motor 18 is rotated after that, and the control unit 10 determines that the secondary battery is discharged before discharging. 14 detects a current Ib flowing through the secondary battery 14 and a voltage Vb of the secondary battery 14.

  FIG. 4 is a diagram showing temporal changes in the current flowing through the secondary battery 14 when cranking by the starter motor 18 is executed. In FIG. 4, the ignition is turned on in the vicinity of −0.5 (s), and a weak current (for example, a current of less than 1 A) is supplied from the secondary battery 14 to the ignition coil or the like. When the supply of power to the starter motor 18 is started at 0 (s), an inrush current flows, the starter motor 18 starts rotating, and the engine 17 is cranked. When the starter motor 18 starts rotating, a small peak current flows at a timing when a piston (not shown) of the engine 17 reaches top dead center, the engine 17 increases in speed and the discharge current value decreases, and the engine 17 is completed. When an explosion occurs, the supply of power to the starter motor 18 is stopped. In the present embodiment, the voltage and current of the secondary battery 14 immediately before the starter motor 18 is rotated are measured, and these are set as the voltage Vb and the current Ib. Then, at a timing when a predetermined time has elapsed from the start of discharge and the resistance value shown in FIG. 3 becomes a constant value (for example, timing after t1), the voltage and current of the secondary battery 14 are again set to a predetermined sampling period. These are measured as V (tn) and I (tn). Note that tn is a variable indicating an elapsed time from the start of supply of electric power to the engine 17.

  Every time sampling is performed, the control unit 10 calculates Z (tn) based on the following equation (1), and increments the value of count_tn by 1 (count_tn = count_tn + 1). Here, in the equation (1), the value obtained by subtracting the voltage V (tn) during discharge from the voltage Vb before discharge is subtracted from the current I (tn) during discharge from the current Ib before discharge. By dividing by the obtained value, Z (tn) is obtained. Note that count_tn is used in equation (2) described later.

・・・（１）

... (1)

  Moreover, the control part 10 calculates | requires Z (tn_ave) which is an average value of Z (tn) obtained by Formula (1) mentioned above for every sampling based on the following formula | equation (2).

・・・（２）

... (2)

  And the control part 10 calculates | requires initial full charge capacity SOH0 based on the following formula | equation (3). Note that f (Z (tn_ave)) represents a predetermined function. For example, f (Z (tn_ave)) = Z (tn_ave) can be set. Α and β are parameters, and can be obtained in advance by actual measurement.

・・・（３）

... (3)

FIG. 5 is a diagram showing the relationship between the resistance values (Z (tn_ave)) of 83 new secondary batteries 14 and the initial full charge capacity SOH0. As shown in FIG. 5, as the resistance value in the discharge is small, in the initial full charge capacity SOH0 increases tendency contribution R ² with respect to the initial full charge capacity SOH0 resistance value is 0.8953, It can be seen that there is a strong correlation between them.

FIG. 6 is a diagram showing the relationship between the initial full charge capacity SOH0 estimated by the above-described method and the actually measured initial full charge capacity SOH0. As shown in FIG. 6, the estimated initial full charge capacity SOH0 and the actually measured initial full charge capacity SOH0 are arranged on or near the straight line with the slope indicated by the broken line “1”, and the estimation is accurate. It is shown that it is. Further, an estimated initial full charge capacity SOH0, contribution R ² between the actually measured initial full charge capacity SOH0 is 0.91, it can be seen that between them there is a strong correlation.

  As described above, according to the first embodiment of the present invention, the resistance value is obtained from the voltage value and the current value before and after the discharge of the secondary battery 14, and the initial full charge capacity of the secondary battery 14 is obtained from the resistance value. Therefore, the initial full charge capacity of the secondary battery 14 can be obtained with high accuracy based on the high correlation between the resistance value and the initial full charge capacity. Further, the state of the secondary battery 14 can be detected with higher accuracy by selecting various correction coefficients with reference to the initial full charge capacity thus obtained.

  Next, an example of detailed processing executed in the control unit 10 will be described with reference to FIG. FIG. 7 is a flowchart illustrating an example of processing executed in the control unit 10. This process is performed when a new secondary battery 14 is mounted on the vehicle and the secondary battery 14 is fully charged (SOC = 100%), and when the starter motor 18 is rotated. It is repeatedly executed at regular intervals (for example, intervals of several ms to several hundred ms). When the flowchart shown in FIG. 7 is started, the following steps are executed.

  In step S10, the CPU 10a determines whether or not the elapsed time tn from the start of power supply to the starter motor 18 is within a predetermined range (ta ≦ tn ≦ tb), and determines that it is within the predetermined range. If so (step S10: Yes), the process proceeds to step S11. Otherwise (step S10: No), the process ends. In the example of FIG. 4, for example, a range between 0.4 [s] and 0.6 [s] can be used as a predetermined range (ta ≦ tn ≦ tb). The reason why the voltage and current after a lapse of a certain time since the starter motor 18 starts rotating is to measure the range in which the resistance value is constant as shown in FIG. .

  In step S11, the CPU 10a calculates Z (tn) based on the above-described equation (1). Vb and Ib are the voltage and current before the secondary battery 14 starts discharging. More specifically, for example, a voltage and current between −0.4 [s] and 0 [s] shown in FIG. 4 can be used.

  In step S12, the CPU 10a increments the value of the variable count_tn by “1”. As a result, the value of the variable count_tn is incremented by 1 according to the number of processes.

  In step S13, the CPU 10a calculates Z (tn_ave) based on the above-described equation (2). More specifically, Z (tn) is a resistance value obtained by the first measurement, and Z (tn + m) is a resistance value obtained by the (m + 1) th measurement. Therefore, the average value of the resistances obtained by the first to (m + 1) th measurements is calculated by the equation (2).

  In step S14, the CPU 10a determines whether or not tn ≧ tb and SOH0CE_flg = 0 is satisfied. If both are satisfied (step S14: Yes), the process proceeds to step S15, and otherwise ( In step S14: No), the process ends. SOH0CE_flg is a flag whose initial value is “0” and whose value is changed to “1” when the calculation shown in step S15 is executed. For this reason, in the range of ta ≦ tn <tb, the condition of tn ≧ tb is not satisfied. Therefore, it is determined No and the process is terminated. If tn = tb, the determination is Yes and the process proceeds to step S15. Then, SOH0CE is calculated, and SOH0CE_flag is set to “1” in step S16, so that it is determined No in step S14 in the subsequent processing (tn> tb), and the processing ends. That is, when tn = tb, the processes of step S15 and step S16 are executed only once.

  In step S15, the CPU 10a calculates an initial full charge capacity SOH0 based on the above-described equation (3). As α and β, values obtained in advance by actual measurement or the like are stored in the ROM 10b, and these values can be read and used.

  In step S16, the CPU 10a sets SOH0CE_flg to “1” and ends the process.

  According to the above processing, when the engine 17 is started by the starter motor 18, the voltage Vb and current Ib of the secondary battery 14 are measured immediately before the start of power supply to the starter motor 18, and the starter motor 18. When the power supply to is started, the voltage V (tn) and the current I (tn) are measured after a certain period of time, and Z (tn) is calculated based on the equation (1). An average value Z (tn_ave) is obtained from Z (tn) thus obtained, and the initial full charge capacity SOH0 can be obtained by substituting this Z (tn_ave) into equation (3).

  By using SOH0 obtained in this way, for example, accurate correction according to the polarization voltage or polarization amount and the stratification voltage or stratification amount can be performed, so that the state of the secondary battery 14 can be more accurately determined. It becomes possible to estimate. For example, when SOH0 is 40 Ah, a correction coefficient corresponding to 40 Ah is selected, and the polarization voltage or polarization amount and the stratification voltage or stratification amount can be corrected based on this correction coefficient.

(C) Description of Configuration of Second Embodiment Next, a second embodiment of the present invention will be described. The configuration of the second embodiment of the present invention is the same as that of FIGS. 1 and 2, but the processing executed in the control unit 10 is different from that of the first embodiment. Therefore, description of the configuration of the second embodiment is omitted, and the operation of the second embodiment will be described.

(D) Description of Operation of Second Embodiment Next, the operation of the second embodiment of the present invention will be described. FIG. 8 is a diagram for explaining the operation principle of the second embodiment. In the first embodiment, as shown in FIG. 3, the initial full charge capacity is obtained based on the resistance value during discharge of the secondary battery 14. However, as shown in FIG. 8, reaction resistance Zct and conductor resistance Zcn exist as resistance components during discharge of the secondary battery 14. Here, the conductor resistance Zcn has a different value depending on, for example, the shape and size of the electrode. More specifically, a secondary battery for use in “idling stop”, which is a technology for stopping the engine when idling to improve fuel efficiency, even when using a secondary battery of the same size, is compared to a normal secondary battery. Designed to reduce conductor resistance. On the other hand, the reaction resistance Zct is a resistance according to the movement of electric charge due to a chemical reaction, and is a resistance component having a high correlation with the size of the secondary battery (initial full charge capacity). Therefore, in the second embodiment, the reaction resistance Zct component is extracted by dividing the conductor resistance Zcn from the obtained resistance component, and the initial full charge capacity of the secondary battery 14 is estimated based on this component. In the second embodiment, the “value relating to the reaction resistance” indicates the value of the reaction resistance Zct when the secondary battery 14 is discharged.

  Next, the detailed operation of the second embodiment will be described with reference to FIG. FIG. 9 is a flowchart for explaining an example of processing executed in the second embodiment. The flowchart shown in FIG. 9 is repeatedly executed at regular intervals (for example, intervals of several ms to several hundred ms) when the rotation of the starter motor 18 is started. When this flowchart is started, the following steps are executed.

  In step S30, the CPU 10a determines whether or not the value of the variable tn indicating the elapsed time from the start of power supply to the starter motor 18 is tn = t0. If tn = t0 (step S30: If yes, the process proceeds to step S31. Otherwise (step S30: No), the process proceeds to step S32. For example, if the time when the process of step S30 is executed is the timing (t0 shown in FIG. 8 or time “0” shown in FIG. 4) when the power supply to the starter motor 18 is started, the determination is Yes and the step Proceed to S31. Otherwise, it is determined No and the process proceeds to Step S32.

  In step S31, the CPU 10a calculates Z (t0) based on the following equation (4). Z (t0) represents the resistance of the secondary battery 14 at t0.

・・・（４）

... (4)

  In step S32, the CPU 10a determines whether or not the elapsed time tn from the start of power supply to the starter motor 18 is within a predetermined range (ta ≦ tn ≦ tb), and is within the predetermined range. When it determines with having entered (step S32: Yes), it progresses to step S33, and when that is not right (step S32: No), it progresses to step S38. In the example of FIG. 4, for example, a range of 0.4 [s] to 0.6 [s] can be used. The reason why the voltage and current after the elapse of a predetermined time since the starter motor 18 starts rotating is measured in order to measure the range in which the resistance value of the secondary battery 14 is constant as described above. It is.

  In step S33, the CPU 10a calculates Z (tn) based on the above-described equation (1). Vb and Ib are the voltage and current before the secondary battery 14 starts discharging. More specifically, the voltage and current in the range of −0.4 [s] to 0 [s] shown in FIG. 4 (a range in which a current of about 1 A flows through the ignition coil) can be used.

  In step S34, the CPU 10a increments the value of the variable count_tn for counting the number of processes by “1”. As a result, the value of the variable count_tn is incremented by 1 according to the number of processes.

  In step S35, the CPU 10a subtracts Z (t0) obtained in step S31 from Z (tn) obtained in step S33, and sets the obtained value as Zct (tn). Here, Z (t0) is a resistance value at t0 shown in FIG. 8, and is a value corresponding to Zcn. Z (tn) is a value corresponding to Zct + Zcn shown in FIG. Therefore, a value corresponding to the reaction resistance Zct shown in FIG. 8 can be obtained by Zct (tn) −Z (t0).

  In step S36, the CPU 10a calculates Z (tn_ave) based on the above-described equation (2). As described above, Z (tn) is a resistance value obtained by the first measurement, and Z (tn + m) is a resistance value obtained by the (m + 1) th measurement. Therefore, in Equation (2), the average value of the resistances obtained by the first to (m + 1) th measurements is calculated.

  In step S37, the CPU 10a calculates Zct (tn_ave) based on the following equation (5). Here, Zct (tn) is a value of reaction resistance obtained by the first measurement, and Zct (tn + m) is a value of reaction resistance obtained by the (m + 1) th measurement. Therefore, in the equation (5), the average value of the reaction resistance obtained by the first to (m + 1) th measurements is calculated.

・・・（５）

... (5)

  In step S38, the CPU 10a determines whether or not tn ≧ tb and SOH0CE_flg = 0 is satisfied, and if both are satisfied (step S38: Yes), the process proceeds to step S39, and otherwise ( In step S38: No), the process ends. SOH0CE_flg is a flag whose initial value is “0” and whose value is set to “1” after the calculation shown in step S39. For this reason, in the range of ta ≦ tn <tb, the condition of tn ≧ tb is not satisfied. Therefore, the determination is No and the process is terminated. If tn = tb, the determination is Yes and the process proceeds to step S39. Then, SOH0 is calculated, and SOH0CE_flag is set to “1” in step S40. Therefore, in the subsequent processing (tn> tb), it is determined No in step S38 and the processing is terminated. That is, when tn = tb, the processes of step S39 and step S40 are executed only once.

  In step S39, the CPU 10a calculates an initial full charge capacity SOH0 based on the following equation (6). As α, β, and γ, values obtained in advance by actual measurement are stored in the ROM 10b, and these values can be read and used.

・・・（６）

... (6)

  In step S40, the CPU 10a sets SOH0CE_flg to “1” and ends the process.

FIG. 10 is a diagram showing the relationship between the value of Zct (tn_ave) of 83 new secondary batteries measured by the process of FIG. 9 and the initial full charge capacity SOH0. As shown in FIG. 10, the smaller the value of Zct (tn_ave), in the initial full charge capacity SOH0 increases tendency contribution ^{R 2} with respect to the initial full charge capacity SOH0 of Zct (tn_ave) is 0.8445 It can be seen that there is a strong correlation between them.

  According to the above processing, it is possible to accurately estimate the initial full charge capacity of the secondary battery 14 based on changes in voltage and current when the engine 17 is started. By using SOH0 obtained in this way, for example, accurate correction according to the polarization voltage or polarization amount and the stratification voltage or stratification amount can be performed, so that the state of the secondary battery 14 can be more accurately determined. It becomes possible to estimate.

(D) Description of Modified Embodiment The above embodiment is an example, and it is needless to say that the present invention is not limited to the case described above. For example, in each of the above embodiments, the purpose is to calculate the initial full charge capacity SOH0. However, as shown in FIG. 11, for example, the size of the secondary battery 14 is based on the calculated initial full charge capacity SOH0. You may make it determine the thickness. In FIG. 11, compared with FIG. 7, processing of steps S50 to S54 is added. Other than that is the same as FIG. 7, and therefore, Steps S50 to S54 will be described below. SOH0 is calculated by the process of step S15, and after SOH0CE_flg is set to “1” by the process of step S16, the process proceeds to step S50. In step S50, it is determined whether or not SOH0 calculated in step S15 satisfies the condition of SOH_small ≦ SOH0 ≦ SOH_large. If satisfied (step S50: Yes), the process proceeds to step S51, and Battery_size = middle is determined. In other cases (step S50: No), the process proceeds to step S52. In step S52, it is determined whether or not SOH0 <SOH_small is satisfied. If satisfied (step S52: Yes), the process proceeds to step S53, and it is determined that Battery_size = small, and the process ends. Otherwise (step S52). : No), the process proceeds to step S54, and Battery_size = lage is determined and the process is terminated. According to the above processing, by appropriately setting the determination threshold values SOH_small, SOH_middle, SOH_large, the size of the secondary battery 14 is classified into small, middle, large based on the estimated initial full charge capacity SOH0. be able to. In FIG. 11, the size is classified into three sizes, but may be classified into two or four or more sizes.

  Further, in each of the above embodiments, the voltage Vb and the current Ib before rotating the starter motor 18 are measured only once. For example, the average value is measured by measuring a plurality of times. Also good. Further, while the starter motor 18 is rotating, the voltage V (tn) and the current I (tn) are measured a plurality of times, and an average value Z (tn_ave) or Zct (tn_ave) is calculated based on the measurement results of the plurality of times. However, for example, these may be calculated using a single measurement result. That is, the voltage Vb and the current Ib, and the voltage V (tn) and the current I (tn) may be selected either once or a plurality of times.

  In each of the above embodiments, all the voltages and currents measured during the period from ta to tb are used. However, according to the actual measurement results, the accuracy of estimation is higher when the voltage and current at the inflection point (the point at which the piston of the engine 17 reaches the top dead center or the bottom dead center) shown in FIG. 4 are not used. Therefore, the voltage and current near the inflection point may be excluded from the measurement target or calculation target. Specifically, the current obtained by sampling is differentiated with respect to time, and when the obtained value is close to “0”, it is determined as an inflection point. Can be excluded.

  Further, in each of the above embodiments, the case where a current flows through the starter motor 18 has been described as a measurement target. However, if a certain amount of current flows through the secondary battery 14 for a predetermined time, the measurement target is used. Can do. For example, when the steering is operated when the vehicle is stopped (so-called “still-off”), a certain amount of current (for example, about 100 amps) flows to the steering motor for a certain period of time. Can be targeted.

  Further, in each of the above embodiments, the equations (3) and (6) are used as the equations for obtaining SOH0. However, these are merely examples, and equations other than these can be used. For example, in the above description, for f (Z (tn)) and f (Zct (tn)), f (Z (tn)) = Z (tn) and f (Zct (tn)) = Zct (tn) However, for example, a higher-order expression or an exponential function having a second or higher order, or a polynomial may be used.

  In the embodiment shown in FIG. 11, the size of the secondary battery 14 is classified into three, large, medium, and small. For example, the secondary battery 14 is classified into two or four or more. You may make it do. Further, instead of classifying the sizes, Ah that is a unit of the initial full charge capacity may be estimated and displayed.

  Further, in each of the embodiments described above, the measurement of the secondary battery 14 is performed after the fully charged state. However, for example, the measurement may be performed when the fully charged state is not achieved. In this case, the parameters α, β, and γ in the equations (3) and (6) are prepared according to the SOC for each SOC of the secondary battery 14, and the parameters according to the SOC value are read out. Thus, SOH0 may be calculated.

DESCRIPTION OF SYMBOLS 1 Secondary battery state detection apparatus 10 Control part (sending means, estimation means)
10a CPU
10b ROM
10c RAM
10d Display unit 10e I / F
11 Voltage sensor (detection means)
12 Current sensor (detection means)
13 Temperature Sensor 14 Secondary Battery 15 Discharge Circuit 16 Alternator 17 Engine 18 Starter Motor 19 Load

Claims (6)

In a secondary battery state detection device that detects the state of a secondary battery mounted on a vehicle,
Detecting means for detecting a value of a current flowing through the secondary battery and a voltage value of the secondary battery;
The voltage value and current value before discharge of the secondary battery are detected by the detection means, and the voltage value and current value during discharge of the secondary battery are detected by the detection means, and these voltage value and current value are detected. And obtaining means for obtaining a value related to the reaction resistance of the secondary battery,
Estimating means for estimating the initial full charge capacity based on a correlation between the value relating to the reaction resistance obtained by the obtaining means and the initial full charge capacity of the secondary battery;
A secondary battery state detection device comprising:   The obtaining means detects the voltage value and current value before rotation of the starter motor that starts the engine of the vehicle by the detection means, and the voltage value and current value of the secondary battery during rotation of the starter motor. 2. The secondary battery state detection device according to claim 1, wherein a value related to a reaction resistance of the secondary battery is obtained based on the voltage value and the current value.   The obtaining means obtains a voltage value of a difference between a voltage value before discharging of the secondary battery and a voltage value during discharging, and calculates a difference between a current value before discharging of the secondary battery and a current value during discharging. 3. The secondary battery state according to claim 1, wherein a current value is obtained, and a value obtained by dividing the voltage value of the difference by the current value of the difference is a value related to the reaction resistance. Detection device.   The obtaining means obtains a voltage value of a difference between a voltage value before discharge of the secondary battery and a voltage value immediately after the start of discharge, and calculates a current value before discharge of the secondary battery and a current value immediately after start of discharge. A difference current is obtained, and a value obtained by dividing the difference voltage value by the difference current value is defined as a first resistance value, and the secondary battery has a voltage value before discharge and immediately after the start of discharge. Obtaining the voltage value of the difference between the voltage values, obtaining the current value of the difference between the current value before the discharge of the secondary battery and the current value immediately after the start of the discharge, and obtaining the voltage value of the difference as the current value of the difference 2. The value obtained by dividing by 2 is used as a second resistance value, and a value obtained by subtracting the first resistance value from the second resistance value is set as a value related to the reaction resistance. Or the secondary battery state detection device according to 2;   The estimation means includes an initial full charge capacity of the secondary battery based on a linear function indicating a relationship between a value related to the reaction resistance obtained by the seek means and an initial full charge capacity value of the secondary battery. The secondary battery state detection device according to claim 1, wherein a value is estimated. In a secondary battery state detection method for detecting a state of a secondary battery mounted on a vehicle,
A detection step of detecting a value of a current flowing through the secondary battery and a voltage value of the secondary battery;
The voltage value and current value before discharging of the secondary battery are detected in the detecting step, and the voltage value and current value during discharging of the secondary battery are detected in the detecting step, and these voltage value and current value are detected. And obtaining a value relating to a reaction resistance of the secondary battery based on
An estimation step of estimating the initial full charge capacity based on a correlation between a value related to the reaction resistance obtained in the obtaining step and an initial full charge capacity of the secondary battery;
A secondary battery state detection method comprising:

Images