JP7452370B2 - Secondary battery system - Google Patents

Description

The present invention relates to a secondary battery system in which a plurality of secondary batteries are connected in series or in parallel.

The secondary battery system includes a plurality of first output switches, each of which has one terminal connected to the positive terminal of each secondary battery, and each other terminal of which is connected to each other; a plurality of second output section switches connected to the negative terminal and whose other terminals are connected to each other; and a negative terminal of one of the adjacent secondary batteries and a positive terminal of the other secondary battery. Some devices include a plurality of series connection elements connected between the two. In the above secondary battery system, when connecting the secondary batteries in series, each first output section switch and each second output section switch are cut off, and each series connection element is made conductive, so that each secondary battery is connected to each other in series. When connecting in parallel, each first output section switch and each second output section switch are made conductive, and each series connection element is cut off. A related technique is Patent Document 1.

However, in the above-mentioned secondary battery system, if each first output section switch and each second output section switch are made conductive in a state where at least one series connection element has a short circuit failure, a short circuit failure occurs. Since both ends of each secondary battery are short-circuited through the series connection element and a relatively large current flows through each secondary battery, each secondary battery may fail or the fuses connected to each secondary battery in series may melt. There is a risk that this may occur.

Therefore, in the above-mentioned secondary battery system, when connecting the secondary batteries in parallel with each other, the series connection element that is short-circuited is identified, and the first output section switch and the first output section switch that are not connected to the series connection element are identified. Only the 2-output switch needs to be conductive.

Japanese Patent Application Publication No. 2019-054677

An object of one aspect of the present invention is to provide a secondary battery system in which a plurality of secondary batteries are connected in series or in parallel to each other, among a plurality of series connection elements respectively connected between adjacent secondary batteries. The purpose is to identify the series connection element that is experiencing a short-circuit failure.

A secondary battery system according to one embodiment of the present invention includes a plurality of secondary batteries, and a plurality of secondary batteries each having one terminal connected to a positive terminal of the plurality of secondary batteries and the other terminals of each of the secondary batteries connected to each other. a first output section switch, a plurality of second output section switches, each of which has one terminal connected to the negative terminal of the plurality of secondary batteries, and whose other terminals are connected to each other, and the adjacent secondary batteries. When the plurality of series connection elements are respectively connected between the negative terminal of one of the secondary batteries and the positive terminal of the other secondary battery, and the plurality of secondary batteries are connected in series with each other, the When the plurality of first output section switches and the plurality of second output section switches are cut off and the plurality of series connection elements are made conductive, and the plurality of secondary batteries are connected in parallel with each other, the plurality of first outputs and a control section that makes the plurality of second output section switches conductive and cuts off the plurality of series connection elements.

The control unit is connected to one of the adjacent first output switches and one of the adjacent first output switches when the adjacent first output switches are electrically connected. A current flows through a first failure check path including a series-connected element to be checked for failure and a secondary battery connected to the other of the adjacent first output switches. When the voltage is equal to or higher than the first threshold value, or when the adjacent second output switches are conductive, one of the adjacent second output switches and the adjacent second output switches A second failure that includes a series connection element to be checked for failure that is connected to a second output switch and a secondary battery that is connected to the other of the adjacent second output switches. If the current flowing through the check path is equal to or higher than the second threshold value, it is determined that the series-connected element to be checked for failure has a short-circuit failure.

As a result, by making all series-connected elements subject to failure checking, it is possible to identify the series-connected element in which a short-circuit failure has occurred.

Furthermore, a fuse may be connected in series to each of the plurality of secondary batteries.

As a result, when the series-connected elements are short-circuited and the adjacent first output switches or adjacent second output switches are made conductive, the relatively large current flowing through the failure check path will cause the fuse to melt. Since it is possible to prevent a relatively large current from flowing through the secondary battery, failure of the secondary battery can be suppressed.

Further, when the control unit determines that the series connection element to be checked for failure has a short-circuit failure, the control unit performs the first failure check before a fuse included in the first failure check path blows out. A first output section included in the path is cut off, or a second output section switch included in the second fault check path is cut off before a fuse included in the second fault check path is blown. It may be configured as follows.

This can prevent the fuse from blowing out if the series-connected elements are short-circuited.

Further, when the control unit determines that the series connection element targeted for failure check has a short-circuit failure, the control unit transmits information to the secondary battery system to the effect that the series connection element targeted for failure check has a short circuit failure. The system may be configured to notify the user of the industrial vehicle in which the system is installed.

Thereby, it is possible to prompt the user to replace the series connection element that is short-circuited.

When shifting the connection state of the plurality of secondary batteries from a series connection state to a parallel connection state, the control unit determines whether a current flowing through the first failure check path is equal to or greater than the first threshold value. Alternatively, it may be configured to determine whether the current flowing through the second failure check path is equal to or higher than the second threshold value.

As a result, when each secondary battery is connected in parallel with each other, the first output section switch and the second output section switch connected to both ends of the secondary battery connected to the series connection element that is short-circuited are cut off. As a result, it is possible to prevent a relatively large current from flowing to each secondary battery through a series connection element that has a short-circuit failure, and prevent each secondary battery from failing or causing each secondary battery to It is possible to prevent fuses connected in series from melting.

According to the present invention, in a secondary battery system in which a plurality of secondary batteries are connected in series or in parallel with each other, a short-circuit failure occurs in a plurality of series connection elements connected between adjacent secondary batteries. It is possible to specify the series-connected elements.

FIG. 1 is a diagram showing an example of a secondary battery system according to an embodiment. 5 is a flowchart illustrating an example of the operation of the control unit. It is a figure which shows the modification of the secondary battery system of embodiment.

Embodiments will be described in detail below based on the drawings.

FIG. 1 is a diagram showing an example of a secondary battery system according to an embodiment.

A secondary battery system 1 shown in FIG. 1 is mounted on an industrial vehicle Ve such as a forklift or a towing tractor. Note that, in addition to the secondary battery system 1, the industrial vehicle Ve includes a load Lo such as a driving motor.

Further, the secondary battery system 1 supplies power to the load Lo, and is supplied with power from an external charger Ch. Note that the charger Ch may be provided inside the industrial vehicle Ve.

The secondary battery system 1 also includes secondary batteries B1 to B3, a positive charging terminal Tip, a negative charging terminal Tin, a positive discharging terminal Top, a negative discharging terminal Ton, and a first output switch. S11 to S13, second output section switches S21 to S23, series connection elements S31 and S32, fuses F1 to F3, ammeters Si1 to Si3, and a control section 2.

Further, if the secondary batteries B1 to B3 are not particularly distinguished, they will simply be referred to as secondary battery B. Further, if the first output section switches S11 to S13 are not particularly distinguished, they will simply be referred to as the first output section switch S1. Further, if the second output section switches S21 to S23 are not particularly distinguished, they will simply be referred to as the second output section switch S2. Moreover, when the series connection elements S31 and S32 are not particularly distinguished, they are simply referred to as the series connection element S3. Further, if the fuses F1 to F3 are not particularly distinguished, they will simply be referred to as fuse F.

Further, the number of each of the secondary battery B, the first output section switch S1, and the second output section switch S2 is not limited to three. Furthermore, the number of series-connected elements S3 is not limited to two. For example, when the number of each of the secondary battery B, the first output section switch S1, and the second output section switch S2 is two, and the number of series connection elements S3 is one, the secondary battery system 1 It includes batteries B1 and B2, first output switches S11 and S12, second output switches S21 and S22, and a series connection element S31. In this configuration, the negative side charging terminal Tin is connected to the negative terminal of the secondary battery B2 and also to the second output switch S22.

The secondary battery B is composed of one or more chargeable and dischargeable batteries (modules) such as a lithium ion battery or a nickel metal hydride battery.

The first output switch S1, the second output switch S2, and the series connection element S3 are each composed of a semiconductor switch such as a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) or a mechanical switch (electromagnetic relay). . Note that the series connection element S3 may be configured by a diode.

The fuse F1 blows when the current flowing through the secondary battery B1 becomes larger than the rated current, and prevents a current exceeding the allowable current from flowing into the secondary battery B1. Further, the fuse F2 is blown when the current flowing through the secondary battery B2 becomes larger than the rated current, and prevents a current exceeding the allowable current from flowing into the secondary battery B2. Further, the fuse F3 is blown when the current flowing through the secondary battery B3 becomes larger than the rated current, and prevents a current exceeding the allowable current from flowing into the secondary battery B3.

Ammeter Si1 detects the current flowing through secondary battery B1, and sends the detected current to control section 2. Further, the ammeter Si2 detects the current flowing through the secondary battery B2, and sends the detected current to the control unit 2. Further, the ammeter Si3 detects the current flowing through the secondary battery B3, and sends the detected current to the control unit 2.

That is, one terminal of the first output section switch S11 is connected to the positive terminal of the secondary battery B1, and also connected to the positive terminal of the charger Ch via the positive side charging terminal Tip, and one terminal of the first output section switch S12 is connected to the positive terminal of the charger Ch via the positive side charging terminal Tip. One terminal is connected to the positive terminal of the secondary battery B2, and one terminal of the first output section switch S13 is connected to the positive terminal of the secondary battery B3. Further, the other terminals of the first output switches S11 to S13 are connected to each other and to the positive terminal of the load Lo via the positive discharge terminal Top. Further, one terminal of the second output switch S21 is connected to the negative terminal of the secondary battery B1 via the fuse F1 and the ammeter Si1, and one terminal of the second output switch S22 is connected to the negative terminal of the secondary battery B1 via the fuse F2 and the ammeter Si2. is connected to the negative terminal of the secondary battery B2, and one terminal of the second output switch S23 is connected to the negative terminal of the secondary battery B3 via a fuse F3 and an ammeter Si3. Further, the other terminals of the second output switches S21 to S23 are connected to each other and to the negative terminal of the load Lo via the negative discharge terminal Ton. Further, one terminal of the series connection element S31 is connected to the positive terminal of the secondary battery B2 of the adjacent secondary batteries B1 and B2, and the other terminal of the series connection element S31 is connected to the positive terminal of the secondary battery B2 of the adjacent secondary batteries B1 and B2. and is connected to the negative terminal of the secondary battery B1. Further, one terminal of the series connection element S32 is connected to the positive terminal of the secondary battery B3 of the adjacent secondary batteries B2 and B3, and the other terminal of the series connection element S32 is connected to the positive terminal of the secondary battery B3 of the adjacent secondary batteries B2 and B3. and is connected to the negative terminal of secondary battery B2. Note that when the series connection elements S31 and S32 are configured by diodes, one terminal of each of the series connection elements S31 and S32 corresponds to a cathode terminal, and the other terminal of each of the series connection elements S31 and S32 corresponds to an anode terminal. corresponds to

The control unit 2 is composed of a CPU (Central Processing Unit) or a programmable device (FPGA (Field Programmable Gate Array) or PLD (Programmable Logic Device)), and according to charging or discharging of the secondary batteries B1 to B3, The respective operations of the first output section switches S11 to S13, the second output section switches S21 to S23, and the series connection elements S31 and S32 are controlled. When the series connection elements S31 and S32 are composed of diodes, the operation of the series connection elements S31 and S32 is controlled more than when the series connection elements S31 and S32 are composed of semiconductor switches or mechanical switches. Since this is not necessary, the load on the control unit 2 can be reduced.

<When charging secondary batteries B1 to B3>
Note that it is assumed that the first output section switch S1, the second output section switch S2, and the series connection element S3 are not out of order. Further, it is assumed that fuse F is not blown.

The control unit 2 turns off the first output switches S11 to S13 and the second output switches S21 to S23, and makes the series connection elements S31 and S32 conductive. Thereby, the secondary batteries B1 to B3 can be connected in series with each other. When power is supplied from the charger Ch to the secondary battery system 1, the positive terminal of the charger Ch is connected to the positive charging terminal Tip, the secondary battery B1, the ammeter Si1, the fuse F1, the series connection element S31, Current flows to the negative terminal of the charger Ch via the secondary battery B2, ammeter Si2, fuse F2, series connection element S32, secondary battery B3, ammeter Si3, fuse F3, and negative side charging terminal Tin, Secondary batteries B1 to B3 are charged. In this way, when charging the secondary batteries B1 to B3, by connecting the secondary batteries B1 to B3 in series, the voltage applied to the entire secondary batteries B1 to B3 can be made relatively high. The current flowing through the secondary batteries B1 to B3 can be reduced. Therefore, since the charging cable that connects the charger Ch and the industrial vehicle Ve can be downsized, charging workability can be improved.

<When charging some secondary batteries B among secondary batteries B1 to B3>
It is assumed that the first output switch S1, the second output switch S2, and the series connection element 3 are not in failure. Further, it is assumed that fuse F is not blown.

When charging the secondary battery B1 and not charging the secondary batteries B2 and B3, the control unit 2 shuts off the first output switches S11 to S13, the second output switch S22, and the series connection elements S31 and S32. At the same time, the second output section switches S21 and S23 are made conductive. When power is supplied from the charger Ch to the secondary battery system 1, the positive terminal of the charger Ch is connected to the positive charging terminal Tip, the secondary battery B1, the ammeter Si1, the fuse F1, and the second output switch S21. A current flows to the negative terminal of the charger Ch via the second output section switch S23 and the negative charging terminal Tin. As a result, only the secondary battery B1 is charged.

When charging the secondary battery B2 and not charging the secondary batteries B1 and B3, the control unit 2 shuts off the first output switch S13, the second output switch S21, and the series connection elements S31 and S32. The first output switches S11 and S12 and the second output switches S22 and S23 are made conductive. When power is supplied from the charger Ch to the secondary battery system 1, the positive terminal of the charger Ch is connected to the positive charging terminal Tip, the first output section switch S11, the first output section switch S12, and the secondary battery B2. , current flows to the negative terminal of the charger Ch via the ammeter Si2, the fuse F2, the second output switch S22, the second output switch S23, and the negative charging terminal Tin, and only the secondary battery B2 is charged. Ru.

When charging the secondary battery B3 and not charging the secondary batteries B1 and B2, the control unit 2 shuts off the first output switch S12, the second output switches S21 to S23, and the series connection elements S31 and S32. At the same time, the first output section switches S11 and S13 are made conductive. When power is supplied from the charger Ch to the secondary battery system 1, the positive terminal of the charger Ch is connected to the positive charging terminal Tip, the first output switch S11, the first output switch S13, and the secondary battery B3. A current flows to the negative terminal of the charger Ch via the ammeter Si3, the fuse F3, and the negative charging terminal Tin, and only the secondary battery B3 is charged.

Further, when charging the secondary batteries B1 and B2 and not charging the secondary battery B3, the control unit 2 shuts off the first output switches S11 to S13, the second output switch S21, and the series connection element S32. At the same time, the second output section switches S22 and S23 and the series connection element S31 are made conductive. Thereby, secondary batteries B1 and B2 can be connected in series with each other. When power is supplied from the charger Ch to the secondary battery system 1, the positive terminal of the charger Ch is connected to the positive charging terminal Tip, the secondary battery B1, the ammeter Si1, the fuse F1, the series connection element S31, A current flows to the negative terminal of the charger Ch via the secondary battery B2, ammeter Si2, fuse F2, second output switch S22, second output switch S23, and negative charging terminal Tin, and the secondary battery B1 , B2 are charged.

Further, when charging the secondary batteries B2 and B3 and not charging the secondary battery B1, the control unit 2 shuts off the first output switch S13, the second output switches S21 to S23, and the series connection element S31. At the same time, the first output section switches S11 and S12 and the series connection element S32 are made conductive. Thereby, secondary batteries B2 and B3 can be connected in series with each other. When power is supplied from the charger Ch to the secondary battery system 1, the positive terminal of the charger Ch is connected to the positive charging terminal Tip, the first output section switch S11, the first output section switch S12, and the secondary battery B2. , ammeter Si2, fuse F2, series connection element S32, secondary battery B3, ammeter Si3, fuse F3, and negative electrode side charging terminal Tin. , B3 are charged.

In addition, when charging the secondary batteries B1 and B3 and not charging the secondary battery B2, the first output section switch S11, the second output section switches S21 to S23, and the series connection element S32 are cut off, and the first output section The section switches S12 and S13 and the series connection element S31 are made conductive. Thereby, secondary batteries B1 and B3 can be connected in series with each other. When power is supplied from the charger Ch to the secondary battery system 1, the positive terminal of the charger Ch is connected to the positive charging terminal Tip, the secondary battery B1, the ammeter Si1, the fuse F1, the series connection element S31, A current flows to the negative terminal of the charger Ch via the first output switch S12, the first output switch S13, the secondary battery B3, the ammeter Si3, the fuse F3, and the negative charging terminal Tin, and the secondary battery B1 , B3 are charged.

Alternatively, when charging the secondary batteries B1 and B3 and not charging the secondary battery B2, the first output section switches S11 to S13, the second output section switch S23, and the series connection element S31 are cut off, and the second output section The section switches S21 and S22 and the series connection element S32 are made conductive. Thereby, secondary batteries B1 and B3 can be connected in series with each other. When power is supplied from the charger Ch to the secondary battery system 1, the positive terminal of the charger Ch is connected to the positive charging terminal Tip, the secondary battery B1, the ammeter Si1, the fuse F1, and the second output switch S21. , the second output section switch S22, the series connection element S32, the secondary battery B3, the ammeter Si3, the fuse F3, and the negative terminal of the charger Ch. , B3 are charged.

<When discharging secondary batteries B1 to B3>
Note that it is assumed that the first output section switch S1, the second output section switch S2, and the series connection element S3 are not out of order. Further, it is assumed that fuse F is not blown.

The control unit 2 turns off the series connection elements S31 and S32, and turns on the first output switches S11 to S13 and the second output switches S21 to S23. Thereby, the secondary batteries B1 to B3 can be connected in parallel with each other. The load is then connected from the negative terminal of the load Lo to the negative discharge terminal Ton, the second output switch S21, the fuse F1, the ammeter Si1, the secondary battery B1, the first output switch S11, and the positive discharge terminal Top. Current flows through the positive terminal of Lo. In addition, the load is connected from the negative terminal of the load Lo to the negative discharge terminal Ton, the second output switch S22, the fuse F2, the ammeter Si2, the secondary battery B2, the first output switch S12, and the positive discharge terminal Top. Current flows through the positive terminal of Lo. In addition, the load is connected from the negative terminal of the load Lo to the negative discharge terminal Ton, the second output switch S23, the fuse F3, the ammeter Si3, the secondary battery B3, the first output switch S13, and the positive discharge terminal Top. Current flows through the positive terminal of Lo. As a result, secondary batteries B1 to B3 are discharged. In this manner, when discharging the secondary batteries B1 to B3, the overall capacity of the secondary batteries B1 to B3 can be increased by connecting the secondary batteries B1 to B3 in parallel.

<When forming a failure check route>
When selecting the series connection element S31 as the series connection element S3 to be checked for failure, the control unit 2 selects the first output switch S13, the second output switches S21 to S23, and the series connection elements S31 and S32. By shutting off the circuit and making the first output section switches S11 and S12 conductive, the first output section switches S11 and S12, the series connection element S31, the secondary battery B1, the ammeter Si1, and the fuse F1 are connected. A failure check path L11 (first failure check path) including the above is formed. It is assumed that when the series connection element S31 has a short circuit failure, a relatively large current flows through the failure check path L11. Moreover, a short circuit failure is defined as a state in which both ends of the series connection element S3 are connected to each other. Alternatively, when selecting the series connection element S31 as the series connection element S3 to be checked for failure, the control unit 2 selects the first output section switches S11 to S13, the second output section switch S23, and the series connection element S31. , S32 are cut off and the second output switches S21 and S22 are made conductive, thereby connecting the second output switches S21 and S22, the series connection element S31, the secondary battery B2, the ammeter Si2, and the fuse F2. A failure check route L21 (second failure check route) including the following is formed. It is assumed that when the series connection element S31 has a short-circuit failure, a relatively large current flows through the failure check path L21.

Further, when selecting the series connection element S32 as the series connection element S3 to be checked for failure, the control unit 2 selects the first output section switch S11, the second output section switches S21 to S23, and the series connection element S31. , S32 are cut off and the first output switches S12 and S13 are made conductive, thereby connecting the first output switches S12 and S13, the series connection element S32, the secondary battery B2, the ammeter Si2, and the fuse F2. A failure check route L12 (first failure check route) including the following is formed. It is assumed that when the series connection element S32 has a short-circuit failure, a relatively large current flows through the failure check path L12. Alternatively, when selecting the series connection element S32 as the series connection element S3 to be checked for failure, the control unit 2 selects the first output section switches S11 to S13, the second output section switch S21, and the series connection element S31. , S32 are cut off and the second output switches S22 and S23 are made conductive, thereby connecting the second output switches S22 and S23, the series connection element S32, the secondary battery B3, the ammeter Si3, and the fuse F3. A failure check path L22 (second failure check path) including the following is formed. It is assumed that when the series connection element S32 has a short-circuit failure, a relatively large current flows through the failure check path L22.

<When determining failure of series connection element S3>
When the current measured by the ammeter Si1 included in the failure check path L11 is equal to or higher than the threshold value Ith1 (first threshold value), the control unit 2 determines that the series connection element S31 has a short-circuit failure. Further, the threshold value Ith1 is the minimum value of the current flowing through the failure check path L11 when the first output section switches S11, S12 and the series connection element S31 are conductive. Further, the control unit 2 is configured to cut off at least one of the first output switches S11 and S12 before the fuse F1 blows out when the current measured by the ammeter Si1 is equal to or higher than the threshold value Ith1. You may. Thereby, when the series connection element S31 has a short-circuit failure, it is possible to prevent the fuse F1 from blowing out when forming the failure check path L11.

Further, when the current measured by the ammeter Si2 included in the failure check path L21 is equal to or higher than the threshold value Ith2 (second threshold value), the control unit 2 determines that the series connection element S31 has a short-circuit failure. . Note that the threshold value Ith2 is the minimum value of the current flowing through the failure check path L21 when the second output section switches S21 and S22 and the series connection element S31 are conductive. Further, the control unit 2 is configured to cut off at least one of the second output switches S21 and S22 before the fuse F2 blows out when the current measured by the ammeter Si2 is equal to or higher than the threshold value Ith2. You may. Thereby, when the series connection element S31 has a short-circuit failure, it is possible to prevent the fuse F2 from blowing out when forming the failure check path L21.

Further, when the current measured by the ammeter Si2 included in the failure check path L12 is equal to or higher than the threshold value Ith3 (first threshold value), the control unit 2 determines that the series connection element S32 has a short-circuit failure. . Note that the threshold value Ith3 is the minimum value of the current flowing through the failure check path L12 when the first output section switches S12, S13 and the series connection element S32 are cut off. Further, the control unit 2 is configured to cut off at least one of the first output switches S12 and S13 before the fuse F2 blows out when the current measured by the ammeter Si2 is equal to or higher than a threshold value Ith3. You may. Thereby, when the series connection element S32 has a short-circuit failure, it is possible to prevent the fuse F2 from blowing out when forming the failure check path L12.

Further, if the current measured by the ammeter Si3 included in the failure check path L22 is equal to or higher than the threshold Ith4 (second threshold), the control unit 2 determines that the series connection element S32 has a short-circuit failure. . Note that the threshold value Ith4 is the minimum value of the current flowing through the failure check path L22 when the second output section switches S22, S23 and the series connection element S32 are cut off. Further, the control unit 2 is configured to cut off at least one of the second output switches S22 and S23 before the fuse F3 blows out when the current measured by the ammeter Si3 is equal to or higher than a threshold value Ith4. You may. Thereby, when the series connection element S32 has a short-circuit failure, it is possible to prevent the fuse F3 from blowing out when forming the failure check path L22.

That is, the control unit 2 conducts the failure check when the two adjacent first output switches S1 or the two adjacent second output switches S2 are turned on and the series connection element S3 to be checked for failure is cut off. If the current flowing through the path is equal to or greater than the threshold value, it is determined that the series-connected element S3 targeted for failure check has a short-circuit failure.

<During discharge of secondary battery B when series connection element S3 is short-circuited>
Note that it is assumed that the first output section switch S1 and the second output section switch S2 are not out of order. Further, it is assumed that fuse F is not blown.

When the control unit 2 determines that the series connection element S31 is short-circuited, it shuts off the first output switch S11, the second output switch S21, and the series connection element S32, and also turns off the first output switch S12. , S13 and the second output switches S22, S23 are turned on, thereby connecting the secondary batteries B2, B3 in parallel to each other.

Alternatively, if the control unit 2 determines that the series connection element S31 is short-circuited, it shuts off the first output unit switch S12, the second output unit switch S22, and the series connection element S32, and The secondary batteries B1 and B3 are connected in parallel to each other by conducting the switches S11 and S13 and the second output section switches S21 and S23.

Further, when the control unit 2 determines that the series connection element S32 is short-circuited, it shuts off the first output unit switch S12, the second output unit switch S22, and the series connection element S31, and The secondary batteries B1 and B3 are connected in parallel to each other by conducting the switches S11 and S13 and the second output section switches S21 and S23.

Alternatively, if the control unit 2 determines that the series connection element S32 has a short-circuit failure, it shuts off the first output unit switch S13, the second output unit switch S23, and the series connection element S31, and The secondary batteries B1 and B2 are connected in parallel to each other by conducting the switches S11 and S12 and the second output section switches S21 and S22.

In this way, when the series connection element S3 has a short-circuit failure, the first output section switch S1 and the second output section switch S2 connected to the secondary battery B connected to the series connection element S3 are cut off. By doing so, even if the remaining secondary batteries B are connected in parallel with each other, both ends of the remaining secondary batteries B will not be short-circuited, and a relatively large current can be prevented from flowing through the remaining secondary batteries B. .

FIG. 2 is a flowchart showing an example of the operation of the control unit 2 during charging.

First, when changing the connection state of the secondary battery B from the series connection state to the parallel connection state (step S1: Yes), the control unit 2 forms a failure check path (step S2). For example, when the control unit 2 determines that charging of the secondary batteries B1 to B3 is completed, the control unit 2 changes the connection state of the secondary battery B from the series connection state to the parallel connection state.

Next, if the current flowing through the failure check path is equal to or higher than the threshold value Ith (step S3: Yes), the control unit 2 determines that the series connection element S3 to be checked for failure has a short-circuit failure (step S4). , notifies the user of the industrial vehicle Ve that the series connection element S3 is out of order (step S5). For example, if the control unit 2 determines that the series connection element S3 to be checked for failure has a short-circuit failure, it lights up a lamp near a meter mounted on the industrial vehicle Ve or sounds a buzzer. Thereby, the user can be prompted to replace the failed series connection element S3. Note that even if the configuration is such that fuse F included in the failure check path is blown after the current flowing through the failure check path exceeds the threshold value Ith, the secondary battery B included in the failure check path is connected to the secondary battery system. 1, so even if the remaining secondary batteries B are connected in parallel with each other, both ends of the remaining secondary batteries B will not be short-circuited, and a relatively large current will not flow through the remaining secondary batteries B. be able to.

On the other hand, if the current flowing through the failure check path is smaller than the threshold value Ith (step S3: No), the control unit 2 proceeds to the process of step S6.

Next, when the control unit 2 determines that all the series connection elements S3 have not been checked for failure (step S6: No), the control unit 2 selects the next series connection element S3 that has not been checked for failure. After doing so (step S7), the process returns to step S2, and a failure check path including the series connection element S3 to be failed checked selected in the process of step S7 is formed.

On the other hand, when the control unit 2 determines that all the series connection elements S3 have been checked for failure (step S6: Yes), the Batteries B are connected in parallel (step S8).

In this way, in the secondary battery system 1 of the embodiment, the two adjacent first output switches S1 or the two adjacent second output switches S2 are made conductive, and the series connection element S3 to be checked for failure is cut off. If the current flowing through the failure check path is equal to or higher than the threshold value Ith while the current is running, it can be determined that the series connection element S3 to be checked for failure has a short-circuit failure. By selecting it as a failure check target, it is possible to specify the series connection element S3 which has a short-circuit failure.

In addition, in the secondary battery system 1 of the embodiment, since it is possible to identify the series connection element S3 that has a short circuit failure, the secondary battery B connected to the series connection element S3 that has a short circuit failure can be identified. The remaining secondary batteries B can be connected in parallel. Therefore, it is possible to prevent both ends of the remaining secondary battery B from being short-circuited through the series connection element S3 which has a short-circuit failure, and a relatively large current from flowing to the remaining secondary battery B. It is possible to prevent the secondary battery B from breaking down and the fuse F connected in series to the remaining secondary batteries B from melting. Thereby, even if the series connection element S3 fails, all the secondary batteries B will not become unusable, so that the secondary battery system 1 can continue to supply power to the load Lo.

Furthermore, in the secondary battery system 1 of the embodiment, there is no need to provide a new failure detection circuit in order to identify the series connection element S3 that has a short-circuit failure, so an increase in manufacturing costs can be reduced. .

Note that the present invention is not limited to the above-described embodiments, and various improvements and changes can be made without departing from the gist of the present invention.

<Modified example>
FIG. 3 is a diagram showing a modification of the secondary battery system of the embodiment. In the secondary battery system 1 shown in FIG. 3, the same components as those shown in FIG.

The secondary battery system 1 shown in FIG. 3 differs from the secondary battery system 1 shown in FIG. 1 in that the positive charging terminal Tip is connected to the connection point of the other terminal of each of the first output switches S11 to S13. The switch S41 is connected between the connection point of the other terminal of each of the second output switches S21 to S23 and the negative charging terminal Tin, and the switch S42 is connected to the second output switch S21. This is a point connected between the connection point of the other terminal of each of ~S23 and the negative electrode side discharge terminal Ton. Note that the switches S41 and S42 are constituted by semiconductor switches or mechanical switches. Furthermore, the method for forming a failure check path and the short-circuit failure check method in the secondary battery system 1 shown in FIG. 3 are equivalent to the method for forming a failure check path and the short-circuit failure check method in the secondary battery system 1 shown in FIG. Therefore, its explanation will be omitted.

<When charging secondary batteries B1 to B3>
Note that it is assumed that the first output switch S1, the second output switch S2, the series connection element S3, and the switches S41 and S42 are not out of order. Further, it is assumed that fuse F is not blown.

The control unit 2 shuts off the first output switches S12, S13, the second output switches S21, S22, and the switch S42, and also switches the first output switch S11, the second output switch S23, the series connection element S31, S32 and switch S41 are made conductive. Thereby, the secondary batteries B1 to B3 can be connected in series with each other. When power is supplied from the charger Ch to the secondary battery system 1, the positive terminal of the charger Ch is connected to the positive charging terminal Tip, the first output switch S11, the secondary battery B1, the ammeter Si1, and the fuse F1. , series connection element S31, secondary battery B2, ammeter Si2, fuse F2, series connection element S32, secondary battery B3, ammeter Si3, fuse F3, second output section switch S23, switch S41, and negative electrode side A current flows to the negative terminal of the charger Ch via the charging terminal Tin, and the secondary batteries B1 to B3 are charged.

<When charging some secondary batteries B among secondary batteries B1 to B3>
Note that it is assumed that the first output switch S1, the second output switch S2, the series connection element S3, and the switches S41 and S42 are not out of order. Further, it is assumed that fuse F is not blown.

When charging the secondary battery B1 and not charging the secondary batteries B2 and B3, the control unit 2 controls the first output switches S12, S13, the second output switches S22, S23, the series connection elements S31, S32, Then, the switch S42 is cut off, and the first output switch S11, the second output switch S21, and the switch S41 are made conductive. When power is supplied from the charger Ch to the secondary battery system 1, the positive terminal of the charger Ch is connected to the positive charging terminal Tip, the first output switch S11, the secondary battery B1, the ammeter Si1, and the fuse F1. , a current flows to the negative terminal of the charger Ch via the second output section switch S21, the switch S41, and the negative side charging terminal Tin, and only the secondary battery B1 is charged.

When charging the secondary battery B2 and not charging the secondary batteries B1 and B3, the control unit 2 controls the first output switches S11, S13, the second output switches S21, S23, the series connection elements S31, S32, Then, the switch S42 is cut off, and the first output section switch S12, the second output section switch S22, and the switch S41 are made conductive. When power is supplied from the charger Ch to the secondary battery system 1, the positive terminal of the charger Ch is connected to the positive charging terminal Tip, the first output switch S12, the secondary battery B2, the ammeter Si2, and the fuse F2. A current flows to the negative terminal of the charger Ch via the second output section switch S22, the switch S41, and the negative charging terminal Tin, and only the secondary battery B2 is charged.

When charging the secondary battery B3 and not charging the secondary batteries B1 and B2, the control unit 2 controls the first output switches S11, S12, the second output switches S21, S22, the series connection elements S31, S32, Then, the switch S42 is cut off, and the first output switch S13, the second output switch S23, and the switch S41 are made conductive. When power is supplied from the charger Ch to the secondary battery system 1, the positive terminal of the charger Ch is connected to the positive charging terminal Tip, the first output switch S13, the secondary battery B3, the ammeter Si3, and the fuse F3. A current flows to the negative terminal of the charger Ch via the second output section switch S23, the switch S41, and the negative side charging terminal Tin, and only the secondary battery B3 is charged.

In addition, when the control unit 2 charges the secondary batteries B1 and B2 and does not charge the secondary battery B3, the control unit 2 includes the first output switches S12 and S13, the second output switches S21 and S23, the series connection element S32, Then, the switch S42 is cut off, and the first output switch S11, the second output switch S22, the series connection element S31, and the switch S41 are made conductive. Thereby, secondary batteries B1 and B2 can be connected in series with each other. When power is supplied from the charger Ch to the secondary battery system 1, the positive terminal of the charger Ch is connected to the positive charging terminal Tip, the first output switch S11, the secondary battery B1, the ammeter Si1, and the fuse F1. , a current flows to the negative terminal of the charger Ch via the series connection element S31, the secondary battery B2, the ammeter Si2, the fuse F2, the second output section switch S22, the switch S41, and the negative charging terminal Tin. Only the next batteries B1 and B2 are charged.

In addition, when charging the secondary batteries B2 and B3 and not charging the secondary battery B1, the control unit 2 also controls the first output switches S11 and S13, the second output switches S21 and S22, the series connection element S31, Then, the switch S42 is cut off, and the first output switch S12, the second output switch S23, the series connection element S32, and the switch S41 are made conductive. Thereby, secondary batteries B2 and B3 can be connected in series with each other. When power is supplied from the charger Ch to the secondary battery system 1, the positive terminal of the charger Ch is connected to the positive charging terminal Tip, the first output switch S12, the secondary battery B2, the ammeter Si2, and the fuse F2. , the series connection element S32, the secondary battery B3, the ammeter Si3, the fuse F3, the second output section switch S23, the switch S41, and the negative electrode side charging terminal Tin. Only the next batteries B2 and B3 are charged.

<When discharging secondary batteries B1 to B3>
It is assumed that the first output switch S1, the second output switch S2, and the switches S41 and S42 are not out of order. Further, it is assumed that fuse F is not blown.

The control unit 2 turns off the series connection elements S31, S32 and the switch S41, and turns on the first output switches S11 to S13, the second output switches S21 to S23, and the switch S42. Thereby, the secondary batteries B1 to B3 can be connected in parallel with each other. Then, from the negative terminal of the load Lo, the negative discharge terminal Ton, the switch S42, the second output switch S21, the fuse F1, the ammeter Si1, the secondary battery B1, the first output switch S11, and the positive discharge terminal Top are connected. A current flows through the positive terminal of the load Lo. In addition, from the negative terminal of the load Lo, the negative discharge terminal Ton, the switch S42, the second output switch S22, the fuse F2, the ammeter Si2, the secondary battery B2, the first output switch S12, and the positive discharge terminal Top are connected. A current flows through the positive terminal of the load Lo. In addition, from the negative terminal of the load Lo, the negative discharge terminal Ton, the switch S42, the second output switch S23, the fuse F3, the ammeter Si3, the secondary battery B3, the first output switch S13, and the positive discharge terminal Top are connected. A current flows through the positive terminal of the load Lo. As a result, secondary batteries B1 to B3 are discharged.

<During discharge of secondary battery B when series connection element S3 is short-circuited>
It is assumed that the first output switch S1, the second output switch S2, and the switches S41 and S42 are not out of order. Further, it is assumed that fuse F is not blown.

When the control unit 2 determines that the series connection element S31 is short-circuited, it shuts off the first output switch S11, the second output switch S21, the series connection element S32, and the switch S41, and also switches off the first output. The secondary batteries B2 and B3 are connected in parallel with each other by making the section switches S12 and S13, the second output section switches S22 and S23, and the switch S42 conductive.

Alternatively, if the control unit 2 determines that the series connection element S31 is short-circuited, it shuts off the first output switch S12, the second output switch S22, the series connection element S32, and the switch S41, and The secondary batteries B1 and B3 are connected in parallel to each other by conducting the first output section switches S11 and S13, the second output section switches S21 and S23, and the switch S42.

When the control unit 2 determines that the series connection element S32 is short-circuited, it shuts off the first output switch S12, the second output switch S22, the series connection element S32, and the switch S41, and turns off the first output. The secondary batteries B1 and B3 are connected in parallel with each other by making the section switches S11 and S13, the second output section switches S21 and S23, and the switch S42 conductive.

Alternatively, if the control unit 2 determines that the series connection element S32 is short-circuited, it shuts off the first output switch S13, the second output switch S23, the series connection element S32, and the switch S41, and The secondary batteries B1 and B2 are connected in parallel to each other by conducting the first output section switches S11 and S12, the second output section switches S21 and S22, and the switch S42.

In this way, also in the modified secondary battery system 1, by subjecting all the series connection elements S3 to the failure check, it is possible to specify the series connection element S3 having a short-circuit failure. Further, even if the series connection element S3 fails, all the secondary batteries B will not become unusable, so power can be continuously supplied from the secondary battery system 1 to the load Lo. Further, since there is no need to provide a new failure detection circuit to identify the series connection element S3 that is short-circuited, an increase in manufacturing costs can be reduced.

1 Secondary battery system 2 Control unit Tip Positive charging terminal Tin Negative charging terminal Top Positive discharging terminal Ton Negative discharging terminal S11 to S13 First output switch S21 to S23 Second output switch S31, S32 For series connection Elements S41, S42 Switches B1 to B3 Secondary battery Lo Load Ch Charger

Claims (5)

multiple secondary batteries,
a plurality of first output section switches, each of which has one terminal connected to the positive terminal of the plurality of secondary batteries and whose other terminals are connected to each other;
a plurality of second output section switches, each of which has one terminal connected to the negative terminal of the plurality of secondary batteries and whose other terminals are connected to each other;
a plurality of series connection elements each connected between a negative terminal of one of the adjacent secondary batteries and a positive terminal of the other secondary battery;
a positive side charging terminal connected to a connection point between a secondary battery at one end of the plurality of secondary batteries and the first output section switch connected to the secondary battery at one end;
a negative side charging terminal connected to a connection point between a secondary battery at the other end of the plurality of secondary batteries and the second output section switch connected to the secondary battery at the other end;
a positive discharge terminal connected to the other terminal of each of the plurality of first output switches;
a negative discharge terminal connected to the other terminal of each of the plurality of second output switches;
When the plurality of secondary batteries are connected in series, the plurality of first output section switches and the plurality of second output section switches are cut off, and the plurality of series connection elements are made conductive. When connecting the batteries in parallel to each other, a control unit that makes the plurality of first output section switches and the plurality of second output section switches conductive and cuts off the plurality of series connection elements;
Equipped with
The control unit conducts the adjacent first output switches and all the first output switches other than the adjacent first output switches, all the second output switches, and all the second output switches. When the series connection elements are controlled to be cut off , the failure check target is connected to the adjacent first output section switches and one of the first output section switches of the adjacent first output section switches. and a secondary battery connected to the other one of the adjacent first output switches, the current flowing through the first failure check path is equal to or higher than the first threshold value. or , all the first output switches, all the second output switches other than the adjacent second output switches, and all the second output switches are made conductive. When the series connection elements are controlled to be cut off , a failure check is performed between the adjacent second output switches and the second output switch connected to one of the adjacent second output switches. A current flowing through a second failure check path including the target series connection element and a secondary battery connected to the other of the adjacent second output switches is set to a second threshold. If the above is the case, it is determined that the series connection element to be checked for failure is short-circuited. The secondary battery system according to claim 1,
A secondary battery system, wherein a fuse is connected in series to each of the plurality of secondary batteries. The secondary battery system according to claim 2,
When the control unit determines that the series connection element to be checked for failure has a short-circuit failure, the control unit performs a short-circuit operation on the first failure check path before a fuse included in the first failure check path blows out. A first output section included in the first output section is cut off, or a second output section switch included in the second fault check path is cut off before a fuse included in the second fault check path is blown. A secondary battery system. The secondary battery system according to any one of claims 1 to 3,
When the control unit determines that the series connection element subject to the failure check has a short-circuit failure, the control unit controls the secondary battery system installed in the secondary battery system to indicate that the series connection element subject to the failure check has a short circuit failure. A secondary battery system characterized by notifying a user of an industrial vehicle that the vehicle is being used. The secondary battery system according to any one of claims 1 to 4,
When shifting the connection state of the plurality of secondary batteries from a series connection state to a parallel connection state, the control unit determines whether a current flowing through the first failure check path is equal to or greater than the first threshold value. or determining whether a current flowing through the second failure check path is equal to or higher than the second threshold value.

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