JP6979896B2 - Rechargeable battery status detector and rechargeable battery status detection method - Google Patents

Description

The present invention relates to a rechargeable battery state detecting device and a rechargeable battery state detecting method.

As a technique for detecting the polarization voltage of a rechargeable battery, for example, there is a technique disclosed in Patent Document 1.

In the technique disclosed in Patent Document 1, the voltage change due to the influence of polarization after the end of charge / discharge greatly differs depending on the charge / discharge history immediately before the end of charge / discharge, but after a predetermined time has elapsed from the end of charge / discharge, the voltage change rate and the voltage change rate. Since there is a predetermined correlation with the voltage correction value for obtaining a stable voltage, the voltage correction value is estimated with high accuracy using this correlation. The stable voltage can be obtained with high accuracy from the estimated voltage correction value, and the charge rate can be estimated to detect the state.

Japanese Unexamined Patent Publication No. 2010-014636

By the way, in the technique disclosed in Patent Document 1, since the voltage after charging / discharging is completed is used, there is a problem that the opportunity to estimate the polarization voltage is limited. Further, since the polarization voltage changes with the passage of time, there is a problem that the estimation accuracy deteriorates when the time elapses from the estimation.

The present invention has been made in view of the above situations, and is a rechargeable battery state detection device capable of estimating a polarization voltage at an arbitrary timing and suppressing a decrease in estimation accuracy even when time has passed since the estimation. And it is intended to provide a method for detecting the state of a rechargeable battery.

In order to solve the above problems, the present invention presents a rechargeable battery state detecting device for detecting the state of a rechargeable battery, in which a discharging means for pulse-discharging the rechargeable battery and a pulse discharging by the discharging means or the same thereof. Values of a measuring means for measuring the voltage and current values before and after, and a predetermined circuit element constituting the equivalent circuit of the rechargeable battery by the first calculation method based on the voltage and current values measured by the measuring means. A predetermined circuit constituting the equivalent circuit of the rechargeable battery by a first calculation means for calculating the above and a second calculation method different from the first calculation method based on the voltage value and the current value measured by the measuring means. Applying the difference, ratio, or circuit element value between the second calculation means for calculating the element value and the circuit element values calculated by the first calculation means and the second calculation means to a predetermined function. It is characterized by having a calculation means for calculating the polarization voltage of the rechargeable battery based on the obtained value.
According to such a configuration, the polarization voltage can be estimated at an arbitrary timing, and the deterioration of the estimation accuracy can be suppressed even when a time has passed from the estimation.

Further, the present invention, the circuit elements of the first calculating means and the second computing means is a calculation target is characterized by a counter-応抵anti.
According to such a configuration, the estimation accuracy can be further improved by using a circuit element having a high correlation with the polarization voltage.

Further, in the present invention, the first calculation means and the second calculation means (1) divide the voltage value during discharge when the rechargeable battery is discharged by a rectangular pulse having a pulse width of T1 by the current value. The value obtained by subtracting the value obtained by dividing the voltage value during discharge when discharging by a rectangular pulse having a pulse width of T2 (<T1) by the current value is subtracted from the value obtained in the reaction resistance. Calculation method to use as a value, (2) After correction of the voltage value and current value during discharge when the rechargeable battery is discharged by a rectangular pulse with a pulse width of T1, corrected by the voltage value and current value before and after discharge, respectively. From the value obtained by dividing the voltage value by the corrected current value, the voltage value and current value during discharge when discharged by a rectangular pulse with a pulse width of T2 (<T1) are the voltage value and current value before and after discharge. A calculation method in which the value obtained by subtracting the value obtained by dividing the corrected voltage value corrected by A predetermined formula including reaction resistance and conductor resistance / liquid resistance as a coefficient is fitted by a plurality of values obtained by dividing the voltage drop value during discharge from before the start of discharge by the current value, and the reaction resistance is obtained from the value of the coefficient. It is characterized by having a calculation method for obtaining the value of (1) to (3), and using any two of the calculation methods (1) to (3).
According to such a configuration, the polarization voltage can be accurately obtained by a simple calculation.

Further, the present invention is characterized in that the first calculation means and the second calculation means use the calculation method of (1) and the calculation method of (2), respectively.
With such a configuration, the polarization voltage can be obtained with higher accuracy.

Further, in the present invention, the first calculation means and the second calculation means discharge the rechargeable battery by a rectangular pulse having a pulse width of T1 in the calculation method (1) and the calculation method (2). From the value obtained by dividing the discharging voltage value when discharged by the current value, the discharging voltage value when discharging by a rectangular pulse having a pulse width of T2 (<T1) is divided by the current value. Instead of the obtained values, the reaction resistance values are obtained by subtracting the conductor resistance and liquid resistance values obtained by the calculation method (3) above.
According to such a configuration, the value of the reaction resistance can be obtained with high accuracy.

Further, in the present invention, the value of the reaction resistance obtained by the first calculation means and the second calculation means is based on at least one of temperature, charge rate (SOC), and open circuit voltage (OCV). It is characterized by correcting to a value in a state.
With such a configuration, the polarization voltage can be accurately obtained regardless of the temperature, charge rate, and open circuit voltage.

Further, according to the present invention, in the rechargeable battery state detecting method for detecting the state of the rechargeable battery, a discharge step for pulse-discharging the rechargeable battery and a voltage value and a current at the time of or before and after the pulse discharge in the discharge step. The first calculation for calculating the value of a predetermined circuit element constituting the equivalent circuit of the rechargeable battery by the first calculation method based on the measurement step for measuring the value and the voltage value and the current value measured in the measurement step. Based on the step and the voltage value and the current value measured in the measurement step, a predetermined circuit element constituting the value of the equivalent circuit of the rechargeable battery is calculated by a second calculation method different from the first calculation method. Based on the difference, ratio, or value obtained by applying the value of the circuit element to the predetermined function, or the difference between the values of the circuit elements calculated in the second calculation step and the first calculation step and the second calculation step. It is characterized by having a calculation step of calculating the polarization voltage of the rechargeable battery.
According to such a method, the polarization voltage can be estimated at an arbitrary timing, and the deterioration of the estimation accuracy can be suppressed even when a time has passed from the estimation.

According to the present invention, a rechargeable battery state detecting device and a rechargeable battery state detecting method capable of estimating a polarization voltage at an arbitrary timing and suppressing a decrease in estimation accuracy even when time has passed from the estimation are provided. It will be possible to provide.

It is a figure which shows the structural example of the rechargeable battery state detection apparatus which concerns on embodiment of this invention. It is a block diagram which shows the detailed configuration example of the control part of FIG. It is a figure which shows the mode of measurement of voltage and current at the time of pulse discharge. It is a figure which shows the relationship between the SOC change at the time of charge, and the polarization voltage. It is a flowchart for demonstrating an example of the process executed in Embodiment of this invention. It is a figure which shows the result of fitting to a plurality of rechargeable batteries of different sizes. It is a figure which shows the relationship between Rct1-2-Rct1-1, and the SOC change amount at the time of charging before Rct measurement. It is a figure which shows the relationship between Rct1-2 / Rct1_1 and the SOC change amount at the time of charging before Rct measurement. (Rct1-2-Rct1_1) -Rohm is a diagram showing the relationship between ROHM and the amount of SOC change during charging before Rct measurement. It is a figure which shows the relationship between Rct1_3 / Rct1_1 and the SOC change amount at the time of charging before Rct measurement. It is a figure which shows the relationship between Ratio_Rct1_1, Ratio_Rct1_3 and the SOC change amount at the time of charging before Rct measurement. It is a figure which shows the relationship between ΔRatio_Rct1_1 and the SOC change amount at the time of charging before Rct measurement.

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

(A) Explanation of the configuration of the embodiment of the present invention FIG. 1 is a diagram showing a power supply system of a vehicle having a rechargeable battery state detecting device according to the embodiment of the present invention. In this figure, the rechargeable battery state detection device 1 has 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 rechargeable battery 14. do. The control unit 10, the voltage sensor 11, the current sensor 12, the temperature sensor 13, and the discharge circuit 15 may not be configured separately, but may be partially or all of them collectively.

Here, the control unit 10 refers to the outputs from the voltage sensor 11, the current sensor 12, and the temperature sensor 13, detects the state of the rechargeable battery 14, and controls the generated voltage of the alternator 16 to charge the battery. The charge state of the possible battery 14 is controlled. The voltage sensor 11 detects the terminal voltage of the rechargeable battery 14 and notifies the control unit 10. The current sensor 12 detects the current flowing through the rechargeable battery 14 and notifies the control unit 10. The temperature sensor 13 detects the electrolytic solution of the rechargeable battery 14 or the ambient temperature of the rechargeable battery 14, and notifies the control unit 10. It should be noted that the control unit 10 does not control the charge state of the rechargeable battery 14 by controlling the generated voltage of the alternator 16, but for example, even if an ECU (Electric Control Unit) (not shown) controls the charge state. good.

The rechargeable battery 14 is composed of a rechargeable battery having an electrolytic solution, for example, a lead storage battery, a nickel cadmium battery, a nickel hydrogen battery, or the like, and is charged by an alternator 16 to drive a starter motor 18 to start an engine. At the same time, power is supplied to the load 19. The rechargeable battery 14 is configured by connecting a plurality of cells in series.

The discharge circuit 15 is composed of, for example, a semiconductor switch and a resistance element connected in series, and turns the semiconductor switch on / off according to the control of the control unit 10 to discharge the rechargeable battery 14 with a predetermined current. ..

The alternator 16 is driven by the engine 17, generates AC power, converts it into DC power by a rectifier circuit, and charges the rechargeable battery 14. The alternator 16 is controlled by the control unit 10 and is capable of adjusting the generated voltage.

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, and generates a rotational force by the electric power supplied from the rechargeable battery 14 to start 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 rechargeable battery 14. In the example of FIG. 1, only the engine 17 outputs the driving force, but for example, a hybrid vehicle equipped with an electric motor that assists the engine 17 may be used. In the case of a hybrid vehicle, the rechargeable 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. 2 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, a ROM (Read Only Memory) 10b, a RAM (Random Access Memory) 10c, a communication unit 10d, an I / F (Interface) 10e, and a control unit 10. It has 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 described later. 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 / F 10e converts the signals supplied from the voltage sensor 11, the current sensor 12, and the temperature sensor 13 into digital signals and captures them, and also transfers the drive current to the discharge circuit 15, the alternator 16, the starter motor 18, and the like. Supply and control these. The bus 10f is a signal line group 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.

(B) Explanation of the operation of the 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 with reference to FIG.

First, the operation of the embodiment of the present invention will be described. First, the CPU 10a of the control unit 10 controls the discharge circuit 15 to discharge the rechargeable battery 14 at least once by, for example, a rectangular wave-shaped pulse as shown in the lower side of FIG. The width of the rectangular wave is, for example, 10 ms or more. In FIG. 3, the lower figure shows a current, and a constant current flows during pulse discharge. Further, the upper side shows a voltage, and during pulse discharge, the voltage decreases with the passage of time.

At this time, as shown in FIG. 3, the CPU 10a of the rechargeable battery 14 has a predetermined sampling interval t_smp during a predetermined time before the pulse discharge, during the pulse discharge, and after the pulse discharge. The voltage and current are measured (sampled) by the voltage sensor 11 and the current sensor 12.

As a result, Vb (tn) (tn = tb1 to tbN) and Ib (tn) (tn = tb1 to tbN) were obtained as the voltage and current before the pulse discharge, and V (tn) was obtained as the voltage and current during the pulse discharge. (Tn = t1 to tN) and I (tn) (tn = t1 to tN) are obtained, and the voltage and current after pulse discharge are Va (tn) (tn = ta1 to taN) and Ia (tn) (tn =). ta1 to taN) are obtained.

Next, the CPU 10a calculates the voltage difference value V_diff and the current difference value I_diff before and after the pulse discharge by the following equations (1) and (2).

・・・（１）

... (1)

・・・（２）

... (2)

Next, the CPU 10a corrects the voltage V (tun) and the current I (tun) during the pulse discharge based on the following equations (3) and (4).

・・・（３）

... (3)

・・・（４）

... (4)

The CPU 10a calculates the internal impedance Z of the rechargeable battery 14 by the following equation (5) using the voltage V (tn) and the current I (tun) corrected by the equations (3) and (4).

・・・（５）

... (5)

Next, the CPU 10a controls the discharge circuit 15 to discharge the rechargeable battery 14 at least once by, for example, a pulse wave having a rectangular wave shape as shown in FIG. At this time, the width of the rectangular wave is, for example, 3 ms or less. The CPU 10a applies the voltage and current of the rechargeable battery 14 to the voltage sensor 11 and the current sensor at a predetermined sampling interval t_smp for a predetermined time before the pulse discharge, during the pulse discharge, and after the pulse discharge. Measured according to No. 12, Vb (tn) (tn = tb1 to tbN) and Ib (tn) (tn = tb1 to tbN) were obtained as the voltage and current before the pulse discharge as in the above case, and the pulse was discharged. V (tn) (tn = t1 to tN) and I (tn) (tn = t1 to tN) are obtained as the voltage and current of, and Va (tn) (tn = ta1 to taN) are obtained as the voltage and current after pulse discharge. ) And Ia (tn) (tn = ta1 to taN).

Next, the CPU 10a calculates the voltage difference value V_diff and the current difference value I_diff before and after the pulse discharge by the above-mentioned equations (1) and (2). Then, the CPU 10a calculates the internal impedance Z of the rechargeable battery 14 by the above-mentioned equation (5) using the voltage V (tun) and the current I (tun) corrected by the equations (3) and (4). The internal impedance Z is referred to as Rohm_1 as a conductor resistance and a liquid resistance (hereinafter referred to as “conductor resistance / liquid resistance”).

Then, the CPU 10a obtains the reaction resistance (or charge transfer resistance) Rct1_1 by subtracting the conductor resistance / liquid resistance Rohm_1 from the internal impedance Z measured at 10 ms or more as the width of the rectangular wave. The reaction resistance Rct1_1 may be obtained by subtracting Rohm_3 calculated by the formula (9) described later from the internal impedance Z measured at a width of a rectangular wave of 10 ms or more.

Next, the CPU 10a sets the width of the rectangular wave to 10 ms or more by the same method as described above, and V (tn) (tn = t1 to tN) and I (tn) as the voltage and current during the pulse discharge. (Tn = t1 to tN) is obtained. Subsequently, the CPU 10a calculates the internal impedance Z when the width of the rectangular wave is 10 ms or more by the equation (5) without performing the correction by the equations (1) to (4). Next, the CPU 10a sets the width of the rectangular wave to 3 ms or less by the same method as described above, and V (tn) (tn = t1 to tN) and I (tn) as the voltage and current during the pulse discharge. (Tn = t1 to tN) is obtained. Subsequently, the CPU 10a calculates the internal impedance Z when the width of the rectangular wave is 3 ms or less by the equation (5) without performing the correction by the equations (1) to (4), and calculates the internal impedance Z. , Conductor resistance / liquid resistance Rohm_2. Then, the reaction resistance Rct1_2 is obtained by subtracting the conductor resistance / liquid resistance Rohm_2 from the internal impedance Z measured at 10 ms or more as the width of the rectangular wave. The reaction resistance Rct1_2 may be obtained by subtracting Rohm_3 calculated by the formula (9) described later from the internal impedance Z measured at a width of a rectangular wave of 10 ms or more.

Next, the CPU 10a corrects the two types of reaction resistance Rct1_1 and the reaction resistance Rct1_2 obtained by the above calculation to the values at the reference temperature (for example, 25 ° C.) and the reference SOC (for example, 100%). Subsequently, the CPU 10a applies the two types of reaction resistances Rct1_1 and Rct1_2 to the following formula (6) to obtain ΔRct1.

ΔRct1 = Rct1-2-Rct1_1 ... (6)

Here, since there is a correlation between the reaction resistance Rct and the charge rate SOC, the CPU 10a applies ΔRct1 obtained by the equation (6) to the following equation (7), and is the amount of change in the SOC. Calculate ΔSOC. Note that i () is a predetermined function with ΔRct1 as a variable, and can be obtained by actual measurement, for example.

ΔSOC = i (ΔRct1) ・ ・ ・ (7)

Next, the CPU 10a calculates the polarization voltage Vp from the ΔSOC obtained by the equation (7) based on the following equation (8). Note that j () is a predetermined function with ΔSOC as a variable, and can be obtained by actual measurement, for example.

Vp = j (ΔSOC) ・ ・ ・ (8)

That is, since there is a correlation between ΔSOC and the polarization voltage Vp as shown in FIG. 4, the polarization voltage Vp can be obtained by using the function j () corresponding to these correlations. .. In FIG. 4, the horizontal axis represents ΔSOC and the vertical axis represents the polarization voltage.

As described above, according to the embodiment of the present invention, the change amount ΔSOC of the charge rate and the polarization voltage Vp are obtained by pulse discharge, so that if the vehicle is in a stationary state, it is accurate at any timing. ΔSOC and Vp can be obtained.

Further, the estimated polarization voltage is used to correct the open circuit voltage (voltage when the terminal of the rechargeable battery 14 is opened (OCV: Open Circuit Voltage)), and the SOC is estimated from the corrected open circuit voltage OCV. Therefore, the estimation accuracy of SOC can be improved. Further, when calculating the value of the circuit element constituting the equivalent circuit model of the rechargeable battery 14, the value of the circuit element can be accurately obtained by correcting using the estimated polarization voltage.

In the above embodiment, the two types of reaction resistances Rct1_1 and Rct1_2 are obtained by individual pulse discharges, but they may be obtained by the same pulse discharge.

Next, with reference to FIG. 5, the details of the processing executed by the control unit 10 shown in FIG. 2 will be described. When the process shown in FIG. 5 is started, the following steps are executed.

In step S10, the CPU 10a of the control unit 10 determines whether or not the vehicle on which the rechargeable battery 14 is mounted is stopped (the engine 17 is stopped and the driver is getting off), and the vehicle is stopped. If it is determined (step S10: Y), the process proceeds to step S11, and in other cases (step S10: N), the process ends. For example, when the vehicle is parked in the parking lot, the engine 17 is stopped, the driver gets off, and a predetermined time has elapsed, it is determined as Y, and the process proceeds to step S11.

In step S11, the CPU 10a sets the pulse width of the pulse discharge to T1. For example, T1 is set to a predetermined value of 10 ms or more. At this time, the measurement time before and after the pulse discharge is also set. Note that 10 ms is an example, and other values may be used.

In step S12, the CPU 10a controls the discharge circuit 15 via the I / F 10e to discharge the rechargeable battery 14 at least once by a pulse waveform having a predetermined width of 10 ms or more. As a result, the rechargeable battery 14 is discharged by the pulse waveform as shown in FIG.

In step S13, the CPU 10a refers to the outputs of the voltage sensor 11 and the current sensor 12, measures the terminal voltage of the rechargeable battery 14 and the current flowing through the rechargeable battery 14 at a predetermined sampling cycle, and measures, for example, the RAM 10c. It is stored as data 10ca in. Regarding the current, the case of charging the rechargeable battery 14 can be positive, and the case of discharging can be negative.

In step S14, the CPU 10a determines whether or not the measurement is completed, and if it is determined that the measurement is completed (step S14: Y), the process proceeds to step S15, and in other cases (step S14: N). Returns to step S13 and repeats the same process. By the processing of steps S12 to S14, the measurement processing including the measurement time before and after the pulse shown in FIG. 3 is executed.

In step S15, the CPU 10a sets the pulse width of the pulse discharge to T2. For example, T2 is set to a predetermined value of 3 ms or less. Note that 3 ms is an example, and other values may be used.

In step S16, the CPU 10a controls the discharge circuit 15 via the I / F 10e to discharge the rechargeable battery 14 at least once by a pulse waveform having a predetermined width of 3 ms or less. As a result, the rechargeable battery 14 is discharged by the pulse waveform as shown in FIG.

In step S17, the CPU 10a refers to the outputs of the voltage sensor 11 and the current sensor 12, measures the terminal voltage of the rechargeable battery 14 and the current flowing through the rechargeable battery 14 at a predetermined sampling cycle, and measures, for example, the RAM 10c. It is stored as data 10ca in.

In step S18, the CPU 10a determines whether or not the measurement is completed, and if it is determined that the measurement is completed (step S18: Y), the process proceeds to step S19, and in other cases (step S18: N). Returns to step S17 and repeats the same process. By the processing of steps S16 to S18, the measurement processing including the measurement time before and after the pulse shown in FIG. 3 is executed.

In step S19, the CPU 10a calculates the reaction resistance Rct1_1 based on the measurement result by the pulse discharge. More specifically, the voltage and current obtained by the measurement by the discharge having a pulse width of T1 are corrected by the equations (1) to (4), and the measured voltage and the current in the time before and after the pulse discharge are corrected and corrected. The subsequent voltage and current are applied to Eq. (5) to obtain the internal impedance Z. Next, the voltage and current obtained by the measurement due to the discharge having a pulse width of T2 are corrected by the equations (1) to (4) for the measured voltage and current in the time before and after the pulse discharge, and the corrected voltage and current are corrected. The voltage and current are applied to the equation (5) to obtain Rohm_1. Then, the value of the reaction resistance Rct1_1 is obtained by subtracting the conductor resistance / liquid resistance Rohm_1 from the internal impedance Z.

In step S20, the CPU 10a calculates the reaction resistance Rct1_2 based on the measurement result by the pulse discharge. More specifically, the voltage and current obtained by the measurement due to the discharge with a pulse width of T1 (without correcting the measured voltage and current in the time before and after the pulse by equations (1) to (4)). , The internal impedance Z is obtained by applying to the equation (5). Next, the voltage and current obtained by the measurement due to the discharge of the pulse width T2 (without correcting the measured voltage and current in the time before and after the pulse by the equations (1) to (4)), the equation. Apply to (5) to obtain Rohm_2. Then, the value of the reaction resistance Rct1_2 is obtained by subtracting the conductor resistance / liquid resistance Rohm_2 from the internal impedance Z.

In step S21, the CPU 10a corrects the reaction resistance Rct1_1 and the reaction resistance Rct1_2 obtained in steps S19 and S20 by the temperature. More specifically, the CPU 10a refers to the output of the temperature sensor 13, measures the external temperature of the rechargeable battery 14, and applies the external temperature to the heat equivalent model of the rechargeable battery 14 to recharge the rechargeable battery. Estimate the electrolyte temperature of 14. Then, referring to a table showing the correspondence between the electrolytic solution temperature and the reaction resistance (for example, the table stored in the ROM 10b), the reaction resistance Rct1-1 and the reaction resistance are set so as to be the values at the reference temperature (for example, 25 ° C.). Correct the value of Rct1_2.

In step S22, the CPU 10a corrects the reaction resistance Rct1_1 and the reaction resistance Rct1_2 obtained in steps S19 and S20 by SOC. More specifically, the CPU 10a obtains the SOC at that time from the relationship between the OCV and the SOC, for example. Then, referring to a table showing the correspondence between the SOC and the reaction resistance (for example, the table stored in the ROM 10b), the reaction resistance Rct1-1 and the reaction resistance Rct1_2 are set so as to have the values at the reference SOC (for example, 100%). Correct the value.

In step S23, the CPU 10a applies the values of the reaction resistances Rct1_1 and the reaction resistance Rct1-22 corrected by temperature and SOC in the above-mentioned equation (6) to the above-mentioned equation (6) to obtain ΔRct1.

In step S24, the CPU 10a obtains the value of ΔSOC by applying the value of ΔRct1 obtained in step S23 to the above-mentioned equation (7).

In step S25, the CPU 10a obtains the value of the polarization voltage Vp by applying the value of ΔSOC obtained in step S24 to the above-mentioned equation (8).

According to the above processing, the polarization voltage Vp can be accurately obtained. Further, according to the above processing, if the engine 17 is stopped, the polarization voltage can be estimated at an arbitrary timing.

(C) Description of Modified Embodiment It goes without saying that the above embodiment is an example and the present invention is not limited to the above-mentioned case. For example, in the above embodiment, the reaction resistance Rct1_1 obtained by correcting the voltage and current during the pulse discharge by the equations (1) to (4) based on the voltage and current before and after the pulse discharge, and the equation ( 1) The polarization voltage is obtained based on the reaction resistance Rct1_2 obtained without correction by the equation (4), but for example, the polarization voltage may be obtained based on the following method.

More specifically, the rechargeable battery 14 is pulse-discharged by the discharge circuit 15, the voltage drop from the voltage before the start of discharge is measured, and this voltage drop is divided by the current to obtain the value of the internal resistance. Then, the coefficient is calculated by fitting the obtained internal resistance value with the function shown in the equation (9).

R (tn) = Rct1_3 × (1-exp (−τ / tun)) + Rohm_3 ... (9)

In equation (9), Rct1_3 is a reaction resistance, Rohm_3 is a conductor resistance / liquid resistance, τ is a time constant, and exp () is an exponential function indicating the power of the base e of the natural logarithm.

FIG. 6 is a diagram showing the result of fitting according to the equation (9). In FIG. 6, the horizontal axis represents the elapsed time from the start of pulse discharge, and the vertical axis represents R (tn) of the equation (9). Further, in FIG. 6, the curve (fitted) shows the fitting result by the equation (9), and the rectangle, the triangle, the circle, the rice mark, etc. (meas) show the measurement result. In FIG. 6, various types of batteries were actually measured, and the fitting results and the measurement results are in good agreement.

Next, ΔRct2 is obtained by the following equation (10).

ΔRct2 = Rct1_3-Rct1_1 ... (10)

Subsequently, ΔRct2 obtained by the equation (10) is applied to the following equation (11) to calculate ΔSOC, which is the amount of change in SOC. Note that j () is a predetermined function with ΔRct2 as a variable, and can be obtained by actual measurement, for example.

ΔSOC = k (ΔRct2) ・ ・ ・ (11)

Next, the CPU 10a calculates the polarization voltage Vp from the ΔSOC obtained by the equation (11) based on the following equation (12). Note that m () is a predetermined function with ΔSOC as a variable, and can be obtained by actual measurement, for example.

Vp = m (ΔSOC) ・ ・ ・ (12)

In the above, ΔRct2 is obtained based on the difference value between the reaction resistance Rct1_3 and the reaction resistance Rct1_1 shown in the formula (10), but ΔRct2 is obtained based on these ratios (for example, Rct1_3 / Rct1_1). You may. Similarly, in the above-mentioned equation (6), ΔRct1 is obtained based on the difference value between the reaction resistance Rct1_2 and the reaction resistance Rct1_1, but ΔRct1 is obtained based on these ratios (for example, Rct1_2 / Rct1_1). You may do it. Further, the ratio of the difference value between the reaction resistance Rct1_1 and the reaction resistance Rct1_2 to the conductor resistance / liquid resistance Rohm_1 (for example, (Rct1-2-Rct1_1) / Rohm_1) is set to ΔRct1, and ΔSOC is obtained based on this ΔRct1. good.

Further, in the above, ΔRct is obtained by the combination of Rct1_1 and Rct1-2 and Rct1_1 and Rct1_3, but the difference or ratio by any two combinations of Rct1_1, Rct1_2, and Rct1_3 may be obtained. good. Alternatively, it is obtained by using a predetermined function (for example, ΔRct = f (Rct1_1, Rct1_2) in the case of two combinations of Rct1_1 and Rct1-2) by any two combinations of Rct1_1, Rct1_2, and Rct1_3. You may do so.

FIG. 7 is a diagram showing the relationship between the difference value between the reaction resistance Rct1_2 and the reaction resistance Rct1_1 and the amount of SOC change during charging before Rct measurement. As shown in FIG. 7, it can be seen that there is a substantially linear relationship between the difference value between the reaction resistance Rct1_2 and the reaction resistance Rct1-1 and the amount of change in SOC during charging before Rct measurement.

FIG. 8 is a diagram showing the relationship between the ratio of the reaction resistance Rct1-2 and the reaction resistance Rct1_1 and the amount of SOC change during charging before Rct measurement. As shown in FIG. 8, it can be seen that there is a substantially linear relationship between the ratio of the reaction resistance Rct1-2 and the reaction resistance Rct1-1 and the amount of change in SOC during charging before Rct measurement.

FIG. 9 is a diagram showing the relationship between the value obtained by dividing the difference value between the reaction resistance Rct1_2 and the reaction resistance Rct1-11 by the conductor resistance / liquid resistance Rohm_1 and the amount of SOC change during charging before Rct measurement. As shown in FIG. 9, there is a substantially linear relationship between the value obtained by dividing the difference value between the reaction resistance Rct1_2 and the reaction resistance Rct1-11 by the conductor resistance / liquid resistance Rohm_1 and the amount of SOC change during charging before Rct measurement. You can see that.

FIG. 10 is a diagram showing the relationship between the ratio of the reaction resistance Rct1_3 and the reaction resistance Rct1_1 and the amount of SOC change during charging before Rct measurement. As shown in FIG. 10, it can be seen that there is a substantially linear relationship between the ratio of the reaction resistance Rct1_3 and the reaction resistance Rct1-1 and the amount of SOC change during charging before Rct measurement in a certain region.

Further, in the above embodiment, the polarization voltage Vp is calculated by performing pulse discharge while the vehicle is stopped. For example, pulse discharge is performed at the timing when the polarization of the rechargeable battery 14 is eliminated. The obtained reaction resistance value may be stored as a reference value, and the polarization voltage Vp may be obtained based on the difference value or ratio with the obtained reaction resistance value by performing pulse discharge at an arbitrary timing.

More specifically, at the timing when the polarization of the rechargeable battery 14 is eliminated (for example, the timing when the engine 17 is stopped and a predetermined time (a dozen hours) or more has elapsed), the reaction resistance is caused by pulse discharge by the above-mentioned method. Rct1_1, Rct1-2, Rct1_3, and conductor resistance / liquid resistance Rohm are obtained, and these are stored as Rct1_1r, Rct1-2r, Rct1_3r, and Rohmr.

Next, at an arbitrary timing, the reaction resistances Rct1_1, Rct1-2, Rct1_3, and the conductor resistance / liquid resistance Rohm are obtained by pulse discharge by the above-mentioned method, and these are stored as Rct1_1c, Rct1-2c, Rct1_3c, and Rohmc.

Next, ΔRatio_Rct1_1 is obtained based on the following equations (13) to (15).

Radio_Rct1_1 = Rct1_1c / Rct1_1r ... (13)
Radio_Rct1_3 = Rct1_3c / Rct1_3r ... (14)
ΔRatio_Rct1_1 = Radio_Rct1-1-1-Ratio_Rct1_3 ... (15)

FIG. 11 is a diagram showing the relationship between Rct1_3 (and Rct1_1) and the amount of SOC change during charging before Rct1 measurement. As shown by a solid line and a rectangle in FIG. 11, Rct1_3 increases substantially in proportion to the amount of SOC change ΔSOC during charging. Therefore, the amount of SOC change during charging can be estimated from the rate of increase of Rct1_3 based on the following equation (16). Note that n () is a predetermined function and can be obtained by actual measurement, for example.

ΔSOC = n (Rct1_3) ... (16)

As shown by the broken line and the circle in FIG. 11, Rct1_1 also increases, but it does not have a substantially proportional relationship as in Rct1_3, but changes depending on the amount of SOC change during charging. Therefore, the amount of SOC change during charging can be estimated from the rate of increase of Rct1_1 based on the following equation (17). Note that o () is a predetermined function and can be obtained by actual measurement, for example.

ΔSOC = o (Rct1_1) ・ ・ ・ (17)

FIG. 12 is a diagram showing the relationship between ΔRatio_Rct1_1 and the amount of SOC change during charging before Rct1 measurement. As shown in FIG. 12, there is a substantially proportional relationship between ΔRatio_Rct1_1 and the amount of SOC change during charging before Rct1 measurement from the vicinity where ΔRatio_Rct1_1 exceeds 10%. Therefore, from ΔRatio_Rct1_1 (see equation (15)), which is the difference between the relative values of Rct1, the amount of SOC change during charging can be estimated by the following equation (18). Note that p () is a predetermined function and can be obtained by actual measurement, for example.

ΔSOC = p (ΔRatio_Rct1_1) ... (18)

Further, the flowchart shown in FIG. 5 is an example, and the present invention is not limited to the processing of these flowcharts.

Further, in the above embodiment, the width of the pulse waveform is set to T1 = 10 ms and T2 = 3 ms, but the width may be set to other widths.

Further, in the above embodiment, the case where the pulse discharge is performed once has been described as an example, but the pulse discharge is performed twice or more, and the average value of the measured values in the pulse discharge two or more times is obtained. May be good.

Further, in the above embodiment, the polarization voltage of the rechargeable battery 14 is calculated based on the difference or ratio of the reaction resistances obtained by two different calculation methods. In addition to this, for example, the reaction resistance is calculated. By applying the value of to a predetermined function (for example, ΔRct1 = q (Rct1_2, Rct1_1): q () is a predetermined function having Rct1-2, Rct1_1 as a variable, and as an example, a linear function of two variables). , The polarization voltage may be obtained.

Further, in the above embodiment, the reaction resistance value is corrected by the temperature and SOC in the reference state, but the open circuit voltage (OCV) may be corrected to the reaction resistance value in the reference state. That is, it may be corrected to the value of the reaction resistance in at least one reference state of temperature, SOC, and OCV.

1 Rechargeable 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 Temperature sensor 14 Rechargeable battery 15 Discharge circuit 16 Alternator 17 Engine 18 Starter motor 19 Load

Claims (7)

In the rechargeable battery status detector that detects the status of the rechargeable battery,
A discharge means for pulse-discharging the rechargeable battery and
A measuring means for measuring a voltage value and a current value at the time of pulse discharging by the discharging means or before and after the pulse discharging, and a measuring means.
A first calculation means for calculating the value of a predetermined circuit element constituting the equivalent circuit of the rechargeable battery by the first calculation method based on the voltage value and the current value measured by the measuring means.
A second calculation for calculating the values of predetermined circuit elements constituting the equivalent circuit of the rechargeable battery by a second calculation method different from the first calculation method based on the voltage value and the current value measured by the measuring means. Means and
Polarization of the rechargeable battery based on the difference or ratio of the values of the circuit elements calculated by the first calculation means and the second calculation means, or the values obtained by applying the values of the circuit elements to a predetermined function. A calculation method for calculating voltage and
A rechargeable battery state detector characterized by having. Wherein said circuit element first calculating means and the second computing means is a calculation target is chargeable battery condition detecting apparatus according to claim 1, characterized in that the anti応抵anti. The first calculation means and the second calculation means are
(1) From the value obtained by dividing the discharging voltage value when the rechargeable battery is discharged by a rectangular pulse having a pulse width of T1 by the current value, by a rectangular pulse having a pulse width of T2 (<T1). A calculation method in which the value obtained by subtracting the value obtained by dividing the voltage value during discharge when discharged by the current value is used as the reaction resistance value.
(2) Corrected voltage value corrected by correcting the voltage value and current value during discharging when the rechargeable battery is discharged by a rectangular pulse having a pulse width of T1 according to the voltage value before and after discharging and the current value, respectively. After correction, the voltage value and current value during discharge when discharged by a rectangular pulse with a pulse width of T2 (<T1) are corrected by the voltage value and current value before and after discharge from the value obtained by dividing by the value. A calculation method in which the value obtained by subtracting the value obtained by dividing the voltage value by the corrected current value and using it as the reaction resistance value is used.
(3) Reaction resistance and conductor resistance / liquid resistance are included as coefficients by a plurality of values obtained by dividing the voltage drop value during discharging from before the start of discharging when the rechargeable battery is pulse-discharged by the current value. It has a calculation method, in which a predetermined formula is fitted and the value of the reaction resistance is obtained from the value of the coefficient.
Any two of the calculation methods (1) to (3) above are used.
The rechargeable battery state detecting device according to claim 1 or 2. The rechargeable battery state detecting device according to claim 3, wherein the first calculation means and the second calculation means use the calculation method of (1) and the calculation method of (2), respectively. The first calculation means and the second calculation means are being discharged when the rechargeable battery is discharged by a rectangular pulse having a pulse width of T1 in the calculation method (1) and the calculation method (2). From the value obtained by dividing the voltage value of the above by the current value, the value obtained by dividing the voltage value during discharge when discharged by a rectangular pulse having a pulse width of T2 (<T1) is replaced by the value obtained by dividing the value by the current value. , The reaction resistance values are obtained by subtracting the conductor resistance and liquid resistance values obtained by the calculation method of (3) above.
The rechargeable battery state detecting device according to claim 4. The value of the reaction resistance obtained by the first calculation means and the second calculation means is corrected to a value in which at least one of the temperature, the charge rate (SOC), and the open circuit voltage (OCV) is in a predetermined reference state. The rechargeable battery state detecting device according to any one of claims 1 to 5. In the rechargeable battery status detection method that detects the status of the rechargeable battery,
The discharge step of pulse-discharging the rechargeable battery and
A measurement step for measuring a voltage value and a current value at the time of pulse discharge or before and after the pulse discharge in the discharge step, and
A first calculation step of calculating the value of a predetermined circuit element constituting the equivalent circuit of the rechargeable battery by the first calculation method based on the voltage value and the current value measured in the measurement step.
A second calculation that calculates a predetermined circuit element constituting the value of the equivalent circuit of the rechargeable battery by a second calculation method different from the first calculation method based on the voltage value and the current value measured in the measurement step. Steps and
Polarization of the rechargeable battery based on the difference or ratio of the values of the circuit elements calculated in the first calculation step and the second calculation step, or the value obtained by applying the values of the circuit elements to a predetermined function. Calculation steps to calculate the voltage and
A rechargeable battery state detection method comprising.

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