WO2013176085A1

WO2013176085A1 - Battery-state determination method, battery control device, and battery pack

Info

Publication number: WO2013176085A1
Application number: PCT/JP2013/063951
Authority: WO
Inventors: 博之野村; 守倉石; 宏昌吉澤; 隆広都竹; 正清松井
Original assignee: 株式会社豊田自動織機
Priority date: 2012-05-22
Filing date: 2013-05-20
Publication date: 2013-11-28
Also published as: JP5949147B2; JP2013243881A

Abstract

A battery pack has a battery assembly installed therein which is obtained by connecting, in series, a plurality of batteries equipped with a current-interrupting mechanism and a battery body. When a battery in which the current-interrupting mechanism is operating is present (Y at S1), a battery-control ECU calculates a time derivative (S2) by using a voltage value detected by a voltage sensor, and determines whether the absolute value of the time derivative is larger than a prescribed threshold (S3). When the absolute value is determined to be larger than the threshold (Y at S3), it is also determined whether the detected voltage value falls within a prescribed range (S4). As a result, when the time derivative is larger than the threshold and the detected voltage value falls within the prescribed range (Y at S4), the battery-control ECU determines the current-interrupting mechanism has stopped operating (S5).

Description

Battery state determination method, battery control device, and battery pack

The present invention relates to a technique for using a battery (cell) equipped with a current interruption mechanism.

Rechargeable batteries (secondary batteries) are now widely used. Actually, the voltage obtained between the terminals of one battery is relatively small. For this reason, in the battery which needs to generate a higher voltage, the structure which connected the some battery used as a component in series is employ | adopted.

In secondary batteries, deterioration of characteristics increases due to overdischarge and overcharge. The unbalanced battery capacity between the batteries leads to a decrease in the battery capacity of the entire assembled battery. For this reason, in an apparatus using an assembled battery in which batteries are connected in series, voltage monitoring is performed for each battery, and the monitoring result is reflected in each control of discharging and charging. The characteristic deterioration due to charging is suppressed.

Even if discharge and charge are controlled by voltage monitoring, there is a possibility that the control cannot be performed properly for some reason. For this reason, batteries are often equipped with a current interruption mechanism (CID: Current Interrupt Device).

The current interrupting mechanism is a safety device that operates, for example, due to an increase in pressure inside the battery, and interrupts the current due to an increase in internal pressure. For this reason, at a high temperature at which the internal pressure increases, for example, at the time of overcharging or when an overcurrent is generated, the supply of current to the battery and the supply of current from the battery can be interrupted by the current interruption mechanism. Thereby, when a battery equipped with a current interruption mechanism is used, higher safety can be ensured.

The charge control by voltage monitoring is usually performed so that the current interrupt mechanism does not operate, that is, the current is not interrupted. For this reason, there is a possibility that charge control cannot be performed properly in the operation of the current interrupt function. Accordingly, in a device equipped with a battery, when a current interrupting mechanism is activated, it is common to disconnect the path used for discharging from the battery and charging the battery.
The activated current interrupting mechanism is automatically deactivated, for example, when the internal pressure is lowered. By releasing the operation, the battery returns to a state in which a current can flow and can be used. In a device equipped with a battery, it is possible to remove a restriction (for example, a restriction that the device cannot be used) due to the operation of the current interrupt mechanism. From this, it seems important to detect the release of the operation of the current interruption mechanism with high accuracy.

JP-A-8-191544 Japanese Patent Laid-Open No. 10-270091 JP 2011-200071 A JP 2000-236247 A

An object of the present invention is to provide a technique for detecting (determining) the operation release of a current interrupt mechanism mounted on a battery with high accuracy.

One aspect of the present invention is a method for determining a state of a battery in which charging / discharging is performed by a computer, the computer detects a voltage value between terminals of the battery, and uses the detected voltage value, A time differential value of the voltage value is calculated, and based on the time differential value obtained by the calculation, it is determined as a state of the battery whether or not a current interrupting mechanism mounted on the battery has been deactivated.

Another aspect of the present invention is a battery control apparatus that controls a plurality of batteries to be charged / discharged and connected to each of the first batteries each having a current interrupting mechanism. Voltage value acquisition means for acquiring a voltage value between the terminals of the battery, calculation means for calculating a time differential value of the voltage value using the voltage value acquired by the voltage value acquisition means, and calculation by the calculation means State determination means for determining whether or not the current interrupting mechanism of the first battery is released based on the time differential value.

Still another embodiment of the present invention is a battery pack including a plurality of batteries to be charged / discharged and connected to each of the first batteries each having a current interrupting mechanism. A voltage value detecting means for detecting a voltage value between terminals of the battery, a calculating means for calculating a time differential value of the voltage value using the voltage value detected by the voltage value detecting means, and the calculating means State determining means for determining whether or not the current interrupting mechanism of the first battery is released based on the time differential value.

In the present invention, it is possible to detect (determine) the assembled battery or the release of the operation of the current interruption mechanism mounted on the battery with high accuracy.

It is a figure explaining the structural example of the battery pack by this embodiment. It is a figure explaining the time change of the voltage value accompanying an action | operation of an electric current interruption | blocking mechanism, and action | operation cancellation | release, and an electric current value. It is a flowchart of a CID operation release determination process.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram illustrating a configuration example of a battery pack according to the present embodiment.

The battery pack 1 is assumed to be mounted on a vehicle such as an electric vehicle (EV) or a plug-in hybrid vehicle (PHV). As shown in FIG. 1, the battery pack 1 includes a battery control ECU (Electronic Control Unit) 11, a plurality of batteries 120, a battery pack 12 connected in series, an SMR (System Main Relay) 13, a current sensor 14, and a temperature. A sensor 15 is provided.

The vehicle on which the battery pack 1 is mounted is provided with an ECU (noted as “HV / PHV ECU” in FIG. 1; hereinafter referred to as “vehicle ECU”) 2 that controls the entire vehicle system. . When the battery pack 1 is mounted on a vehicle, the battery control ECU 11 of the battery pack 1 becomes communicable with the vehicle ECU 2, and power is supplied to the battery control ECU 11 from, for example, the power supply 3 of the vehicle body. With this power supply, the battery control ECU 11 becomes operable and performs an operation in accordance with an instruction from the vehicle ECU 2. The power supply to the battery control ECU 11 may be performed from one or more than the power source 3. The type and number of power supplies that supply power to the battery control ECU 11 are not particularly limited.

The battery control ECU 11 is, for example, a computer (data processing apparatus) including a CPU (Central Processing Unit), a memory, a recording medium storing a program (firmware) executed by the CPU, and a plurality of interfaces. The battery control device according to the present embodiment is realized by being mounted on the battery control ECU 11. The battery state determination method according to the present embodiment is also executed by the battery control ECU 11.

As shown in FIG. 1, each battery 120 constituting the assembled battery 12 includes a battery main body 121 and a current interrupt mechanism (CID) 122. The current interruption mechanism 122 is a safety device that forcibly disconnects the electrical connection due to, for example, an increase in the internal pressure of the battery body 121. The internal pressure increases as the temperature increases. The temperature rises due to heating by heat transfer from the heating element, overcharge, overdischarge, or overcurrent generation (for example, short circuit). The current interruption mechanism 122 suppresses a decrease in safety due to such a cause.

Each battery 120 is provided with a voltage sensor 16 for detecting a voltage value between its terminals. This voltage sensor 16 is a voltage value detection means for detecting the voltage value between the terminals of each battery 120. In addition to the determination of the release of the operation of the current interrupt mechanism 122, the overdischarge and overcharge are further prevented. Is also used for balancing battery capacity among batteries 120.

In the present embodiment, the assembled battery 12 has a configuration in which a plurality of batteries 120 including the current interrupting mechanism 122 are connected in series, but may have a different configuration. That is, the assembled battery 12 may have a configuration in which, for example, a plurality of batteries 120 including the current interrupting mechanism 122 and a plurality of battery modules connected in series are connected in parallel. In the case where the arrangement of the battery 120 that is difficult to deteriorate in characteristics is known in advance, the battery 120 that does not include the current interruption mechanism 122 may be used as the battery 120. For this reason, the assembled battery 12 mounted on the battery pack 1 is not limited to the one shown in FIG.

The assembled battery 12 is used to supply power to a motor (not shown). The rated voltage of the assembled battery 12 is lower than the rated voltage of the motor. For this reason, the electric power generated by the discharge from the assembled battery 12 is supplied to a boost converter (not shown) via the SMR 13.

The motor is a generator that generates electric power when charging. The electric power generated by the motor is stepped down by, for example, a step-up converter and supplied to the assembled battery 12 for charging via the SMR 13. Accordingly, the SMR 13 functions as a relay unit that can turn on / off a current provided on a path for discharging from the assembled battery 12 and charging the assembled battery 12. The battery control ECU 11 functions as a control unit that switches current on and off in the SMR 13 as necessary.

The current sensor 14 is a current value detection means for detecting a current value supplied to the assembled battery 12 or a current value supplied from the assembled battery 12. The temperature sensor 15 is temperature detection means for detecting the temperature in the battery pack 1. The current value detected by the current sensor 14 and the temperature detected by the temperature sensor 15 are input to the battery control ECU 11 and processed in the same manner as the voltage value detected by the voltage sensor 16 of each battery 120. Thereby, the battery control ECU 11 functions as current value acquisition means for acquiring the current value detected by the current sensor 14 and voltage value acquisition means for acquiring the voltage value detected by each voltage sensor 16.

The direction of the current flowing through the assembled battery 12 is different between discharging and charging. Thereby, the sign of the current value detected by the current sensor 14 changes depending on the direction of the current. When the current interrupting mechanism 122 is activated, no current flows through the battery pack 12, so that the current value detected by the current sensor 14 is 0 or a value close to 0. The increase in the internal pressure of the battery main body 121 that operates the current interrupting mechanism 122 is usually caused by the current flowing through the battery main body 121 unless it is heated by heat transfer from some heating element. The battery control ECU 11 can recognize a situation in which a current flows through the assembled battery 12 based on a notification or instruction from the vehicle ECU 2. From this, the battery control ECU 11 determines that the current interrupting mechanism 122 has been activated when the current value detected by the current sensor 14 becomes 0 or a value close to 0 when a current flows through the assembled battery 12. Then, the SMR 13 is turned off, that is, the connection by the SMR 13 is cut off, and the determination result is notified to the vehicle ECU 2.

When the SMR 13 is turned off, no current flows through the assembled battery 12 even if the current interrupt mechanism 122 is deactivated. In addition, the vehicle ECU 2 that is notified of the operation of the current interrupt mechanism 122 can perform control so that no current flows through the assembled battery 12. For this reason, in this embodiment, it is determined to cancel the operation of the current interrupt mechanism 122 using the voltage value detected by the voltage sensor 16 provided for each battery 120. Accordingly, the battery control ECU 11 functions as a state determination unit that determines whether to release the operation of the current interruption mechanism 122 of the assembled battery 12 (battery 120). A method for determining the release of the operation of the current interrupt mechanism 122 will be specifically described with reference to FIG.

FIG. 2 is a diagram for explaining the time change of the voltage value and the current value associated with the operation of the current interruption mechanism and the cancellation of the operation. (A) shows an example of the time change of the voltage value detected by the voltage sensor 16 of the battery 120 in which the current interrupting mechanism (CID) 122 is operated, and (b) shows the current value detected by the current sensor 14. An example of time change is shown. The current interrupting mechanism 122 was activated at time t1, and the operation was released at time t2. The release of the operation of the current interrupt mechanism 122 is described as “CID re-conduction”.

The voltage value detected by the voltage sensor 16 becomes indefinite after time t1 with the stop of the current flow accompanying the operation of the current interrupt mechanism 122. In other words, the value is not reliable. On the other hand, the current value detected by the current sensor 14 rapidly decreases from the previous value to 0 as the current flow is stopped due to the operation of the current interrupt mechanism 122.

When the operation of the current interrupting mechanism 122 is not generated by heat transfer from the outside, the generation of Joule heat is stopped by interrupting the current, and the internal pressure of the battery main body 121 in which the current interrupting mechanism 122 is operated decreases. As a result, the activated current interrupting mechanism 122 is deactivated at time t2.

Even if the current interruption mechanism 122 is deactivated, the current value detected by the current sensor 14 remains 0 because the SMR 13 is off. However, the voltage value detected by the voltage sensor 16 is a value representing the voltage between the terminals of the battery 120 because a voltage is generated between the terminals of the battery 120 as the operation of the current interrupt mechanism 122 is released. For this reason, even if the voltage value detected by the voltage sensor 16 is an unreliable value due to the cessation of the current flow accompanying the operation of the current interruption mechanism 122, the voltage sensor 16 immediately before the operation of the current interruption mechanism 122 is released. As long as the voltage value detected by is not an appropriate value, a relatively large difference occurs in the voltage value detected by the voltage sensor 16 before and after the operation of the current interrupting mechanism 122 is released. This embodiment pays attention to this, and determines the release of the operation of the current interrupt mechanism 122.

The battery control ECU 11 determines a time differential value of the voltage value detected by the voltage sensor 16, for example, the voltage value detected last time by the voltage sensor 16 and the voltage value detected this time in order to determine the release of the operation of the current interrupt mechanism 122. Calculate the difference value. Thereby, battery control ECU11 functions as a calculating means which calculates a time differential value.

The battery control ECU 11 compares the absolute value of the calculated difference value with a predetermined threshold value, and if the absolute value is larger than the threshold value, it is considered that the current interrupting mechanism 122 may have been deactivated. The reason why the absolute value is compared with the threshold value is that the voltage value detected by the voltage sensor 16 becomes indefinite when the flow of current stops with the operation of the current interrupt mechanism 122. In FIG. 2A, the portion where the voltage value is indefinite is represented by changing from a solid line to a broken line. However, the change in the voltage value represented by the broken line is an example, and is detected during an indefinite period. The voltage value does not necessarily have a downward trend. Thereby, the sign of the difference value can be either positive or negative. The difference value (time differential value) is hereinafter referred to as “voltage change value”.

Note that the voltage value detected by the temperature sensor 16 of the battery 120 in which the current interruption mechanism 122 is activated is indefinite, and the battery 120 in which the current interruption mechanism 122 has been activated can be identified. The identification can be performed by extracting the battery 120 in which the voltage value detected by the voltage sensor 16 changes unnaturally. This is because, in a situation where no current flows through the assembled battery 12, it is unlikely that the detected voltage value will change relatively large other than the battery 120 in which the current interrupting mechanism 122 is operating. From this, the determination of the release of the operation of the current interrupt mechanism 122 may be performed only for the specified battery 120, that is, the battery 120 that may be considered to be operating the current interrupt mechanism 122. Since it is possible to identify the battery 120 that is considered to have the possibility that the current interrupting mechanism 122 is operating as described above, it is assumed that the battery 120 that should be determined to release the operation of the current interrupting mechanism 122 is known.

In the present embodiment, in order to determine the cancellation of the operation of the current interrupt mechanism 122 with higher accuracy, when the absolute value of the voltage change value is larger than the threshold value, it is confirmed whether or not the detected voltage value is within a predetermined range. Like to do. This range is, for example, a range from a voltage value at which discharge of the battery 120 is stopped (hereinafter referred to as “normal lower limit threshold”) to a rated voltage value of the battery 120 (hereinafter referred to as “normal upper limit threshold”). Thereby, the determination of the release of the operation of the current interruption mechanism 122 is performed when the absolute value of the voltage change value is larger than the threshold value and the detected voltage value is within the range.

In this way, in this embodiment, the operation cancellation of the current interrupt mechanism 122 is determined through a two-stage comparison. Thereby, even if the voltage value detected by the voltage sensor 16 temporarily fluctuates relatively greatly, it is possible to suppress erroneous determination that the current interrupt mechanism 122 has been deactivated. For this reason, the operation release of the current interrupt mechanism 122 can be determined with higher accuracy. Since the voltage change value is used for the operation release determination of the current interrupt mechanism 122, the determination can be performed quickly.

By determining (detecting) the operation release of the current interrupt mechanism 122 with high accuracy, the use of the assembled battery 12 in a usable state can be restarted in a timely manner while ensuring safety. The battery control ECU 11 can shift to a state in which the battery pack 12 can be discharged or the battery pack 12 can be charged by switching the SMR 13 from off to on. When the vehicle ECU 2 has issued a warning or speed limit by notifying the operation of the current interrupting mechanism 122 from the battery control ECU 11, the vehicle ECU 2 cancels the operation by notifying the operation of the current interrupting mechanism 122 from the battery control ECU 11. be able to. For this reason, the user can use the vehicle more comfortably while ensuring safety.

It should be noted that the detected voltage value does not necessarily have to be used for determining whether to release the operation of the current interrupt mechanism 122. For example, in a situation where no current flows through the assembled battery 12, the voltage value of the battery 120 in which the current interruption mechanism 122 is activated is determined when the current interruption mechanism 122 is deactivated unless the temperature detected by the temperature sensor 15 is increased. It is unlikely that it is rising. This is because if the temperature detected by the temperature sensor 15 is not increased, the internal pressure of the battery main body 121 is considered to have decreased due to the temperature decrease. If the temperature is lowered, the voltage value between the terminals of the battery 120 is usually small. In addition, the voltage value detected by the voltage sensor 16 when the current is interrupted is unlikely to rapidly change in an increasing direction even if it is indefinite. Therefore, in consideration of the direction in which the voltage value detected by the voltage sensor 16 changes and the amount of the change, the operation of the current interrupting mechanism 122 is canceled when the voltage value changes relatively large in the increasing direction. May be determined. That is, two threshold values are prepared, and it may be determined that the current interrupt mechanism 122 is deactivated when it is confirmed that the voltage change value is larger than the larger threshold value. If the voltage change value is less than or equal to the larger threshold value and greater than the smaller threshold value, it may be determined whether or not the current interrupting mechanism 122 is further deactivated using the detected voltage value. .

FIG. 3 is a flowchart of the CID operation release determination process. This determination process is a process for the battery control ECU 11 to detect the release of the operation of the current interruption mechanism 122 operated by the battery 120. For example, a certain time determined from the sampling time for the voltage sensor 16 to sample the voltage value. It is executed every time. Next, the process executed by the battery control ECU 11 to determine the release of the operation of the current interrupt mechanism 122 as described above will be described in detail with reference to FIG.

As described above, the battery 120 that should be determined to release the operation of the current interrupt mechanism 122 can be specified in advance. The number of specified batteries 120 is not necessarily one. However, in FIG. 3, for the sake of convenience, it is assumed that the number of specified batteries 120 is only one, and the flow of processing is shown.

First, in S1, the battery control ECU 11 determines whether or not the current interruption mechanism 122 of any battery 120 is operating. When the battery control ECU 11 determines that the current interrupting mechanism 122 has been activated, the battery control ECU 11 saves this as a history in a memory (not shown), and identifies the battery 120 that may have the possibility of the current interrupting mechanism 122 being activated. Thus, identification information representing the specified battery 120 is stored in the memory. Recording to the memory that the current interruption mechanism 122 has been deactivated is performed when it is confirmed that the current interruption mechanism 122 has been deactivated in all of the batteries 120 represented by the stored identification information. From this, if the recording that the current interrupting mechanism 122 has been released is not recorded after the recording that the current interrupting mechanism 122 that was stored immediately before is activated, the determination of S1 is Y (Yes). To S2. When the recording that the operation of the current interrupting mechanism 122 has been released has been performed, the determination of S1 is N (No). In this case, since it is not necessary to determine whether to release the operation of the current interrupt mechanism 122, the CID operation release determination process ends here.

In S2, the battery control ECU 11 takes in a voltage value from each voltage sensor 16, and calculates a voltage change value for each battery 120 in which the identification number is stored. The calculation of the voltage change value is performed by subtracting the previously acquired voltage value from the currently acquired voltage value. In FIG. 3, “voltage change value = d (voltage value) dt” is expressed as a formula for calculating the voltage change value.

In S3 following S2, the battery control ECU 11 determines whether or not the absolute value of the voltage change value is larger than a threshold value (denoted as “CID reconducting threshold value” in FIG. 3). If the voltage change value is larger than the threshold value, the determination in S3 is Y and the process proceeds to S4. If the voltage change value is less than or equal to the threshold value, the determination in S3 is N, and the CID operation release determination process ends here.

In S4, the battery control ECU 11 determines whether or not the voltage value acquired this time is within a range limited by the normal lower limit threshold and the normal upper limit threshold. If the acquired voltage value is equal to or lower than the normal lower limit threshold or equal to or higher than the normal upper limit threshold, the determination in S4 is N, and the CID operation release determination process ends here. On the other hand, if the acquired voltage value is greater than the normal lower limit threshold and less than the normal upper limit threshold, the determination in S4 is Y, and the process proceeds to S5.

In S5, the battery control ECU 11 records the fact as a history in the memory, and notifies the vehicle ECU 2 of the determination result, etc., assuming that the operated current interrupt mechanism 122 has been released. Thereafter, the CID operation release determination process ends.

As described above, when the vehicle ECU 2 has issued a warning or a speed limit by notifying the operation of the current interrupting mechanism 122 from the battery control ECU 11, the vehicle ECU 2 receives an operation canceling notification of the current interrupting mechanism 122 from the battery control ECU 11. Let them be lifted. Thereby, it is possible for the user to use the vehicle more comfortably while ensuring safety.

In the present embodiment, the battery control device 11 is mounted on the battery control ECU 11 in the battery pack 1, but the battery control device may be mounted on a data processing device outside the battery pack 1. Although the battery pack 1 is assumed to be mounted on a vehicle, the battery pack 1 may be mounted on a device other than the vehicle. In some cases, various modifications can be made.

Claims

A method for determining by a computer the state of a battery that is charged and discharged,
Detecting a voltage value between terminals of the battery;
Using the detected voltage value, the time differential value of the voltage value is calculated,
Based on the time differential value obtained by the calculation, as the state of the battery, it is determined whether or not the current interruption mechanism mounted on the battery has been released.
The battery state determination method characterized by the above-mentioned.
The determination that the current interrupting mechanism is released is performed when the absolute value of the time differential value is greater than a predetermined threshold value.
The battery state determination method according to claim 1.
The determination as to whether or not the current interrupt mechanism has been released is performed using the detected voltage value in addition to the time differential value.
The battery state determination method according to claim 2.
In a battery control apparatus that controls a plurality of batteries to be charged / discharged and connected assembled batteries,
Voltage value acquisition means for acquiring a voltage value between terminals of the first battery for each first battery that is a battery provided with a current interruption mechanism;
Using the voltage value acquired by the voltage value acquisition means, a calculation means for calculating a time differential value of the voltage value;
State determining means for determining whether or not the current interrupting mechanism of the first battery is released based on the time differential value calculated by the calculating means;
A battery control device comprising:
The state determination means determines whether or not the current interrupting mechanism has been deactivated using the time differential value and the voltage value acquired by the voltage value acquisition means.
The battery control device according to claim 4.
In a battery pack including a plurality of batteries to be charged / discharged and connected assembled batteries,
Voltage value detection means for detecting a voltage value between terminals of the first battery for each first battery which is a battery provided with a current interruption mechanism;
Using the voltage value detected by the voltage value detection means, a calculation means for calculating a time differential value of the voltage value;
State determining means for determining whether or not the current interrupting mechanism of the first battery is released based on the time differential value calculated by the calculating means;
A battery pack comprising: