WO2007072988A1

WO2007072988A1 - Secondary cell degradation judging device and degradation judging method

Info

Publication number: WO2007072988A1
Application number: PCT/JP2006/325997
Authority: WO
Inventors: Junichi Matsumoto
Original assignee: Toyota Jidosha Kabushiki Kaisha
Priority date: 2005-12-21
Filing date: 2006-12-20
Publication date: 2007-06-28
Also published as: JP2007170953A

Abstract

An ECU executes a program including: a step (S102) counting up until a predetermined wait time elapses when an ignition key is turned off (Yes in S100); a step (S106) for executing discharge process; a step (S108) for counting up the judging time until a voltage change is stabled; a step (S112) for storing the judging time; and a step (S114) for estimating the degradation degree.

Description

Technical field

The present invention relates to a deterioration determination device and a deterioration determination method for determining the degree of deterioration of a secondary battery, and more particularly to determination of the degree of deterioration with high accuracy. Background art

The secondary battery undergoes deterioration in battery performance, represented by full charge capacity (battery capacity after full charge) in the course of its use, and its performance changes in a time-series manner. In particular, if the input / output of electric power exceeds the battery performance, deterioration will be accelerated rapidly, and if it is significant, it may lead to failure. In order to deal with such problems, a technique for quantitatively grasping the degree of deterioration at the present time and detecting the limit amount of the performance of the secondary battery is known.

Japanese Patent Application Laid-Open No. 5_2 8 1 3 0 9 discloses a deterioration determination device that accurately determines the deterioration of a sealed lead-acid battery in a very short time. This deterioration judgment device consists of a switch unit and a load circuit unit for discharging a constant current to a lead storage battery to be tested for a short time, a voltage detection unit or a voltage detection unit for detecting the battery voltage of the lead storage battery, and a lead. A current detector for detecting the current flowing in the storage battery, and a voltage or difference of a difference between the detected battery voltage after the lapse of lmsec or less from the start of discharge and the detected battery voltage before the start of discharge. Calculate the internal resistance from the voltage and the detected current flowing in the lead-acid battery, and then calculate the difference voltage or internal resistance in the regression equation of the difference voltage and battery capacity obtained in advance or the regression equation of the internal resistance and battery capacity. , A memory calculation unit that estimates the current battery capacity, a display unit that displays the differential voltage or internal resistance, or the estimated battery capacity, at least the switch unit, Parts, comprising a, an operation unit for operating orderly storage operation unit.

According to the deterioration judging device disclosed in the above-mentioned publication, the test is completed in a very short time, so the burden on the maintenance person is extremely reduced and the test time is less than lmsec. Therefore, even if the connection between the deterioration judgment device and the battery is disconnected due to a mistake by the maintenance personnel, the discharge is terminated at that time, and there is no risk of sparks. Deterioration determination with extremely high accuracy can be realized.

However, in the case where the deterioration determination is performed based on the voltage polarization characteristics of the secondary battery, as in the deterioration determination device disclosed in the above-mentioned publication, an appropriate deterioration determination can be performed because it depends on the accuracy of the measuring instrument. There is no possibility. The voltage polarization characteristics of secondary batteries depend on the current and temperature and are affected by the charge / discharge history. Therefore, in order to obtain accurate voltage polarization characteristics, it is necessary to accurately acquire not only the voltage but also the absolute values of current and temperature. There is a problem that the cost increases when trying to improve the accuracy of each measuring instrument for detecting voltage, current and temperature.

In the deterioration determination device disclosed in the above-mentioned publication, since the measurement accuracy at the time of obtaining the voltage polarization characteristic of the secondary battery is not considered at all, the above-described problem cannot be solved. Disclosure of the invention

An object of the present invention is to provide a secondary battery deterioration determination device and a deterioration determination method that accurately determine the degree of deterioration of a secondary battery while suppressing an increase in cost. A secondary battery deterioration determination device according to an aspect of the present invention determines a degree of deterioration of a secondary battery. The deterioration determination device includes a detection unit that detects a voltage of the secondary battery, a discharge unit that discharges the secondary battery until a predetermined time elapses, and an arithmetic unit connected to the detection unit and the discharge unit. Including. The arithmetic unit determines the degree of deterioration based on the determination time until the detected voltage change converges after the secondary battery is discharged. According to the present invention, the arithmetic unit determines the degree of deterioration based on the determination time until the detected voltage change converges after the secondary battery is discharged. When the secondary battery is discharged, the voltage drops, and after the discharge is finished, the voltage rises to approach the voltage before discharge. After the discharge is completed, the time until the voltage changes below the predetermined change and converges is a time that depends on the degree of deterioration. The longer it takes to converge, the greater the degree of degradation. Therefore, the degree of deterioration can be determined by measuring the determination time until convergence. If you do this, It is only necessary to improve the resolution for changes around the converging voltage, and it is not necessary to accurately measure the absolute values of the voltage, current and temperature of the secondary battery. Therefore, it is possible to provide a secondary battery deterioration determination device that accurately determines the degree of secondary battery deterioration while suppressing an increase in cost.

Preferably, the arithmetic unit determines that the degree of deterioration of the secondary battery is greater as the determination time is longer.

According to the present invention, the arithmetic unit determines that the degree of deterioration of the secondary battery is greater as the determination time is longer. As the secondary battery deteriorates, the voltage decreases more rapidly, and the time from when discharging ends until the voltage converges tends to be longer. Therefore, it can be determined that the longer the determination time, the greater the degree of deterioration of the secondary battery. More preferably, the arithmetic unit determines that the voltage change has converged when the detected voltage change amount is equal to or less than a predetermined change amount after the secondary battery is discharged.

According to the present invention, the arithmetic unit determines that the voltage change has converged when the detected voltage change amount is equal to or less than a predetermined change amount after the secondary battery is discharged. This makes it possible to accurately measure the determination time until the voltage converges to a substantially constant state from the end of discharge.

More preferably, the secondary battery deterioration determination device is mounted on a vehicle.

According to the present invention, by mounting the deterioration determination device on the vehicle, the degree of deterioration of the secondary battery mounted on the vehicle can be accurately determined. Brief Description of Drawings

FIG. 1 is a diagram showing a configuration of a secondary battery deterioration determination device according to the present embodiment.

Figures 2A and 2B are timing charts showing the voltage change during discharge. Fig. 3 is a timing chart showing the change in voltage according to the degree of deterioration. FIG. 4 is a flowchart showing a control structure of a program executed by ECU which is a secondary battery deterioration determining apparatus according to the present embodiment.

FIG. 5A to FIG. 5C are timing charts showing the operation of the ECU, which is the secondary battery deterioration determining apparatus according to the present embodiment. BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described below with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

As shown in FIG. 1, a vehicle equipped with the secondary battery deterioration determination device according to the present embodiment includes an electronic control unit (ECU) 10 0 0, a battery 2 0 0, a load

3, a discharge resistance device 4 0 0, a current sensor 5 0 0, and a voltage sensor 6 0 0 are provided. The secondary battery deterioration determination device according to the present embodiment is realized by E C U 100. The vehicle on which the secondary battery deterioration determination device according to the present embodiment is mounted is, for example, an electric vehicle using a rotating electrical machine as a drive source, but is particularly limited as long as the vehicle is mounted with a battery. Instead, for example, it may be a hybrid vehicle that uses an engine and a rotating electric machine as drive sources, or a vehicle that uses an engine equipped with an auxiliary battery as a drive source.

The load 300 is, for example, a rotating electrical machine connected via a converter and an inverter. In the present embodiment, the battery 200 is not particularly limited as long as it is a secondary battery, and is, for example, a nickel metal hydride battery or a lithium ion battery.

The discharging resistance device 400 is configured by, for example, a relay switch (hereinafter simply referred to as a relay) and a resistor connected in series. The discharging resistance device 400 is connected to the power supply line 20 02 connected to the + terminal of the battery 20 0 and the power supply line 204 connected to the − terminal. The discharging resistance device 400 is configured to switch the relay in accordance with the discharge control signal received from the ECU 100, thereby interposing the power line 2 0 2 and the power line 2 0 4 with a resistor. Set it to electrical connection or shut off. At this time, the power lines 2 0 2 and 2 0 4

Since the circuit including 4 0 0 and battery 2 0.0 is closed, a current flows and battery 2 0 0 is discharged. Note that the discharging resistance device 400 is electrically connected to or disconnected from the power supply line 20 2 and the power supply line 20 4 via a resistor in accordance with a control signal from the ECU 1 0 0. If the device is in a state The configuration is not limited to the configuration in which the relay switch and the resistor are connected in series.

Current sensor 500 is connected in series with battery 200. Current sensor

500 detects the current value of the current flowing through the power supply line 204. The current sensor 500 transmits a signal representing the detected current value to the ECU 100.

Voltage sensor 600 is connected in parallel to battery 200. Voltage sensor

600 detects the voltage value of the battery 200. Voltage sensor 600 transmits a signal representing the detected voltage value to ECU 100.

The ECU 100 includes a CPU and a memory. The ECU 100 is provided with a force filter unit 102. The counter unit 102 measures time by increasing the count value every calculation cycle. The counter unit 102 may be realized by hardware, or may be realized by a program (software) executed by the ECU 100.

In the present embodiment, the ECU 100 controls the discharging resistance device 400 by executing a program stored in the memory based on the count value in the counter unit 102 and the signals received from the current sensor 500 and the voltage sensor 600. To do.

When the ignition key of the vehicle is turned off, the ECU 100 transmits a discharge control signal to the discharge resistance device 400 when a predetermined standby time has elapsed after the vehicle is turned off, and starts the deterioration determination process. The deterioration determination process is the end of the discharge of the battery 200 by switching the relay of the discharge resistance device 400 to the electrically connected state of the power supply lines 202 and 204 until a predetermined time elapses. This is a process for determining the degree of deterioration of the battery 200 based on the subsequent voltage change.

Figure 2A shows the change in discharge current when the horizontal axis is time and the vertical axis is discharge current. When the ignition key is turned off at time T (0), the counter 102 measures the time. Based on the discharge control signal received by the discharge resistance device 400 from the ECU 100 at time T (1) when a predetermined standby time elapses from time T (0), the power supply lines 202 and 204 are electrically connected. When this state is reached, the discharge current A (0) flows, and the battery 200 starts to be discharged. At this time, the counter unit 102 is reset, and the elapsed time after time (1) is measured. Figure 2B shows the change in the voltage of battery 200 when the horizontal axis is time and the vertical axis is voltage. After time T (1), the voltage value detected by voltage sensor 600 decreases from V (0) when discharge is started. When the measured time reaches time T (2) when a predetermined discharge time elapses from time T (1), power supply lines 202 and 204 are electrically connected based on the discharge control signal received from ECU 100. So that it will be in the shut-off state. At this time, the discharge current detected by the current sensor 500 is zero.

The voltage that had dropped to V (1) at time T (2) increases from time T. (2) so that it approaches the voltage V (0) before discharge. As shown in Fig. 3, the voltage drop tends to increase with deterioration. Therefore, the longer it takes for the voltage to converge after the end of discharge, the more it deteriorates.

Therefore, the present invention is characterized in that the ECU 100 which is a secondary battery deterioration determination device determines the degree of deterioration of the battery 200 based on the voltage change waveform after the battery 200 is discharged. In other words, information on the voltage change corresponding to the degree of deterioration is stored in advance in the memory of the ECU 100, and the degree of deterioration of the battery 200 is determined by comparison with the voltage change after discharge detected by the voltage sensor 600. To do. More specifically, the ECU 100 determines the degree of deterioration of the battery 200 based on the determination time until the detected voltage change converges after the battery 200 is discharged. Hereinafter, with reference to FIG. 4, a control structure of a program executed by the ECU 100 which is the secondary battery deterioration determination apparatus according to the present embodiment will be described.

In step (hereinafter, step is referred to as S) 100, ECU 100 determines whether or not the ignition key is turned off. When the ignition key is turned off (YES in S100), the process proceeds to S102. If not (NO at S100), the process returns to S100.

In step S102, the ECU 100 starts counting up the standby time using the counter unit 102. “Counting up” is performed by adding a predetermined force value for each calculation cycle to a predetermined initial value.

In S104, ECU 100 determines whether or not a predetermined standby time has elapsed since the ignition key was turned off. ECU 100 has a count value It is determined whether or not the count value is greater than or equal to a predetermined standby time. The “predetermined waiting time” is a waiting time until an environment with little temperature change is obtained, and is not particularly limited, and is adapted by experimentation. If a predetermined waiting time has elapsed (YES in S 104), the process proceeds to S106. If not (NO in S104), the process returns to S102.

In S 106, the ECU 100 executes a discharge process. In this cold example, “discharge treatment” means that the relays of the discharge resistance device 400 are switched to electrically connect the power lines 202 and 204 until a predetermined discharge time elapses after the standby time elapses. Refers to the process of making a connection state. Specifically, the ECU 100 controls the discharge resistance device 400 to electrically connect the power supply lines 202 and 2 4 and starts counting up the discharge time in the counter unit 102. At this time, the counter unit 102 resets the count value to a predetermined initial value, adds a predetermined count value for each calculation cycle, and counts up. Then, ECU 100 determines that the predetermined discharge time has elapsed when the count value reaches the count value corresponding to the predetermined discharge time. The ECU 100 switches the relay of the discharge resistance device 400 to electrically cut off the power supply lines 202 and 204. Note that the predetermined discharge time is a time that is adapted from experiments and is not particularly limited, but is preferably a short time that does not deteriorate the determination accuracy.

In step S108, the ECU 100 starts counting up the determination time using the counter unit 102. Specifically, the ECU 100 causes the counter unit 102 to reset the count value to an initial value and add a predetermined count value for each calculation cycle.

In S 110, ECU 100 determines whether or not the voltage of battery 200 has settled. In the present embodiment, the ECU 100 determines whether or not the voltage change has converged based on the voltage change amount input from the voltage sensor 600. The ECU 100 determines that the voltage has settled when the temporal change amount of the voltage input from the voltage sensor 600 is equal to or less than a predetermined change amount. The “predetermined amount of change” is a value that can be determined that the voltage change is in a substantially constant state, and is not particularly limited. It is not adapted and is adapted by experiment. If it is determined that the voltage of battery 200 has settled (YES in S 1 10), the process proceeds to S 1 1 2. If not (NO in S100), the process returns to S108.

In S 1 1 2, ECU 100 stores the count value corresponding to the measured determination time in the memory, assuming that the voltage polarization characteristics of battery 200 have been acquired. The ECU 100 may store the measured determination time in a memory.

In S 114, ECU 100 estimates the degree of deterioration (deterioration degree) of battery 200 based on the stored count value. For example, the ECU 100 may store a map indicating the relationship between the count value and the deterioration degree in advance in the memory, and estimate the deterioration degree from the stored force value and the map. A table or a function expression indicating the relationship between the count value and the degree of deterioration may be stored in advance, and the degree of deterioration may be estimated from the stored count value and the table or expression. Note that the ECU 100 may estimate the degree of deterioration from the determination time measured instead of the count value and a map, table, or function expression.

The operation of the ECU 100, which is the secondary battery deterioration determination device according to the present embodiment based on the above-described structure and flowchart, will be described with reference to FIGS. 5A to 5C.

As shown in FIG. 5A, when the ignition key is turned off at time T (3) (YES in S100), count-up is executed (S102). When the time T (4) at which the count value C a corresponding to the predetermined standby time Ta is reached (YES in S104), discharging is performed (S106). At this time, as shown in Fig. 5C, the voltage drops from V (0) as the discharge starts. At time T (4), after the count value is reset to the initial value, count-up is executed. When the time T (5) at which the count value C b corresponding to the predetermined discharge time T b is reached, the discharge resistance device 400 is controlled so that the power supply lines 202 and 204 are cut off, The discharge process ends. At time T (5), the count value is reset again to the initial value, and then counts up.

At time T (5), detected by voltage sensor 600 as shown in Figure 5C When the time variation of the voltage value is less than or equal to the predetermined variation, it is determined that the voltage variation has settled (YES at S 110), and the count value at time T (5) is C c Is stored in the memory. Then, based on the stored count value Cc or the determination time Tc corresponding to the count value Cc, the deterioration degree of the battery 200 is estimated from a map or the like (S 1 14).

As described above, according to the secondary battery deterioration determination device according to the present embodiment, the time until the voltage changes below a predetermined amount of change after the discharge is completed is converged. The time depends on the degree of deterioration. The longer it takes to converge, the greater the degree of degradation. Therefore, the degree of deterioration can be determined by measuring the determination time. In this way, it is sufficient to improve the resolution for changes around the converging voltage, and it is not necessary to accurately measure the absolute values of the voltage, current, and temperature of the secondary battery. Therefore, it is possible to provide a secondary battery deterioration determination device and a deterioration determination method that accurately determine the degree of secondary battery deterioration while suppressing an increase in cost.

It should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

Claims

The scope of the claims

1. A deterioration determination device for determining the degree of deterioration of a secondary battery (200), comprising: a detection unit (600) for detecting a voltage of the secondary battery (200);

Discharge unit that discharges the secondary battery (200) until a predetermined time elapses

(400) and

An arithmetic unit (100) connected to the detection unit (600) and the discharge unit (400),

The arithmetic unit (100) is

A secondary battery deterioration determination device that determines the degree of deterioration based on a determination time until the detected change in voltage converges after the secondary battery (200) is discharged.

2. The secondary battery deterioration determination device according to claim 1, wherein the arithmetic unit (100) determines that the degree of deterioration of the secondary battery (200) is larger as the determination time is longer. .

3. After the secondary battery (200) is discharged, the arithmetic unit (100) determines that the change in voltage has converged when the detected change in voltage is less than or equal to a predetermined change. The apparatus for determining deterioration of a secondary battery according to claim 1, wherein:

4. The secondary battery deterioration determination device according to claim 1, wherein the deterioration determination device is mounted on a vehicle.

5. The secondary battery deterioration determination device according to any one of claims 1 to 4, wherein the secondary battery is a lithium ion battery.

6. A deterioration determination device for determining the degree of deterioration of the secondary battery (200), the detection means (600) for detecting the voltage of the secondary battery (200), and the elapse of a predetermined time Discharging means (400) for discharging the secondary battery (200) until

A secondary battery (200) including a deterioration determination means (100) for determining the degree of deterioration based on a determination time until the change in the detected voltage converges after the discharge of the secondary battery (200). Degradation judgment device.

7. The deterioration determining means (100) according to claim 6, further comprising means for determining that the degree of deterioration of the secondary battery (200) is larger as the determination time is longer. Secondary battery deterioration judgment device.

8. The deterioration determining means (100) converges the voltage change when the detected voltage change amount is equal to or less than a predetermined change amount after the secondary battery (200) is discharged. The deterioration determination device for a secondary battery according to claim 6, further comprising a convergence determination means for determining this.

9. The deterioration determination device for a secondary battery according to claim 6, wherein the deterioration determination device is mounted on a vehicle.

10. The secondary battery deterioration determination device according to any one of claims 6 to 9, wherein the secondary battery is a lithium ion battery.

1 1. A deterioration determination method for determining a degree of deterioration of a secondary battery (200), comprising: detecting a voltage of the secondary battery (200);

A step of discharging the secondary battery (200) until a predetermined time elapses;

A deterioration determination method for a secondary battery, comprising: a deterioration determination step for determining the degree of deterioration based on a determination time until the change in the detected voltage converges after the secondary battery (200) is discharged.

1. The secondary battery according to claim 11, wherein the deterioration determining step includes a step of determining that the degree of deterioration of the secondary battery (200) is larger as the determination time is longer. Degradation judgment method.

13. The deterioration determining step determines that the voltage change has converged when the detected voltage change amount is equal to or less than a predetermined change amount after the secondary battery (200) is discharged. The method for determining deterioration of a secondary battery according to claim 11, comprising a step.

14. The method for determining deterioration of a secondary battery according to claim 11, wherein the arithmetic unit (100) for realizing the method for determining deterioration is mounted on a vehicle.

15. The method for determining deterioration of a secondary battery according to any one of claims 11 to 14, wherein the secondary battery is a lithium ion battery.

16. A deterioration determination device for determining a degree of deterioration of the secondary battery (200), the voltage sensor (600) detecting the voltage of the secondary battery (200), and a predetermined time A discharging resistance device (400) for discharging the secondary battery (200);

An electronic control unit (100) for determining the degree of deterioration based on a determination time until the change in the detected voltage converges after the secondary battery (200) is discharged. Degradation judgment device.