JP2021158717A - Voltage detection device - Google Patents

Abstract

To provide a voltage detection device by which power supply from a battery is allowed even in a case where an abnormality is detected in any one of battery cells.SOLUTION: A voltage detection device A includes: a detection unit D that detects respective voltages of a plurality of battery cells C1 to C3 connected in series; bypass circuits By1 to By3 connecting positive terminals and negative terminals of the battery cells and each including a switching element 11; and a microcomputer M including a determination unit 14 that determines the presence/absence of an abnormality in the battery cells, and a control unit 15 that performs control to allow a current flow in the switching element of a bypass circuit that is connected to a battery cell in which an abnormality has been detected by the determination unit.SELECTED DRAWING: Figure 1

Description

The present invention relates to a voltage detector.

For example, Patent Document 1 discloses a battery having a plurality of battery cells and having a fuse connected in series to the battery cells. In such a battery, when a large current flows through the fuse due to an abnormality such as overcharging of the battery cell, the fuse is blown and the abnormal battery cell is disconnected.

Japanese Unexamined Patent Publication No. 2012-157217

The battery disclosed in Patent Document 1 includes a plurality of battery cells connected in parallel to one battery subunit. However, in general, the battery generally adopts a configuration in which all battery cells are connected in series. In a battery in which a plurality of battery cells are connected in series, if an abnormality occurs in one of the battery cells and the battery cells are disconnected, the power transmission line in the battery is cut off, and power is supplied from the battery. become unable. In electric vehicles and the like, it is necessary to be able to run for a certain period of time even if some abnormality occurs in the battery. Therefore, even if an abnormality occurs in any of the battery cells of the battery, it is desirable to enable power supply from the battery for at least a certain period of time.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to enable power supply from a battery even when an abnormality is detected in any of the battery cells.

The present invention employs the following configuration as a means for solving the above problems.

The first invention is a voltage detection device, in which a detection unit that detects the voltage of each of a plurality of battery cells connected in series is connected to at least one of the positive terminals and negative terminals of the battery cells. A bypass circuit including a switching element, a determination unit for determining the presence or absence of an abnormality in the battery cell to which the bypass circuit is connected, and the bypass circuit connected to the battery cell in which an abnormality is detected by the determination unit. A configuration is adopted in which a control unit is provided to control the switching element of the above so that the switching element can be energized.

In the second invention, in the first invention, the determination unit adopts a configuration in which the determination unit determines that the battery cell has an abnormality when the battery cell is overcharged.

In the third invention, in the second invention, when the determination unit elapses the voltage of the battery cell for a certain period of time based on the detection result of the detection unit, the battery cell Is determined to be overcharged.

In the fourth invention, in the first invention, when the determination unit detects a thermal abnormality in the battery cell, it determines that the battery cell has an abnormality.

A fifth invention comprises, in any one of the first to fourth inventions, a discharge circuit having a discharge resistor and a discharge switching element connected in parallel and in series with the bypass circuit. adopt.

The sixth invention adopts the configuration in which the resistance value of the bypass circuit is smaller than the resistance value of the discharge circuit in the fifth invention.

According to the present invention, when an abnormality is detected in the battery cell, the switching element of the bypass circuit connected to the battery cell in which the abnormality is detected is set to be energized, and the battery cell in which the abnormality is detected is bypassed. Therefore, energization can be performed via a bypass circuit. Therefore, even if the battery cell in which the abnormality is detected is disconnected, it is possible to output power from the battery provided with the battery cell. Therefore, according to the present invention, power can be supplied from the battery even when an abnormality is detected in any of the battery cells.

It is a circuit diagram which shows the schematic structure of the voltage detection apparatus in 1st Embodiment of this invention. It is a flowchart for demonstrating operation of the voltage detection apparatus in 1st Embodiment of this invention. It is a circuit diagram for demonstrating the operation of the voltage detection apparatus in 1st Embodiment of this invention. It is a flowchart for demonstrating operation of the voltage detection apparatus in 2nd Embodiment of this invention. It is a circuit diagram which shows the schematic structure of the voltage detection apparatus in 3rd Embodiment of this invention.

Hereinafter, an embodiment of the voltage detection device according to the present invention will be described with reference to the drawings.

(First Embodiment)
FIG. 1 is a circuit diagram showing a schematic configuration of the voltage detection device A of the first embodiment. The voltage detection device A of the present embodiment is a device that detects the voltage (cell voltage) of a plurality of (n) battery cells C1 to Cn constituting the battery X, and is mounted on a printed circuit board of a predetermined size. (N) bypass circuits By1 to Byn, a plurality of (n + 1) transmission lines S1 to Sn + 1, a plurality of (n + 1) CR filters F1 to Fn + 1, a detection unit D, and a microcomputer M (determination unit and control unit). ing. The above "n" is a natural number of 2 or more.

In FIG. 1, due to the limitation of drawing space, n (plural) battery cells C1 to Cn, n fuses Fu1 to Fun, n bypass circuits By1 to Byn, and n + 1 transmission lines S1 to Sn + 1 and n + 1 Of the three CR filters F1 to Fn + 1, three battery cells C1 to C3, three fuses Fu1 to Fu3, three bypass circuits By1 to By3, four transmission lines S1 to S4, and four CR filters. Only F1 to F4 are shown.

The n battery cells C1 to Cn are connected in series in a row, the positive terminal of the battery cell C1 is the positive terminal of the battery X, and the negative terminal of the battery cell Cn is the negative terminal of the battery X. That is, the n battery cells C1 to Cn are connected in series in the order of battery cell C1 → battery cell C2 → battery cell C3 → (omitted) → battery cell Cn, and the total cell voltage of each battery cell C1 to Cn. The value becomes the output voltage of the battery X.

Further, fuses Fu1 to Fun are connected in series to the positive terminals of the respective battery cells C1 to Cn. The fuse Fu1 is connected to the positive terminal of the battery cell C1, the fuse Fu2 is connected to the positive terminal of the battery cell C2, the fuse Fu3 is connected to the positive terminal of the battery cell C3 (omitted), and the positive terminal of the battery cell Cn. The fuse Fun is connected to. These fuses Fu1 to Fun operate when a large current (fusing current described later) flows and are blown, and disconnect the battery cells C1 to Cn connected to the positive terminal themselves from the conductive path.

The n bypass circuits By1 to Byn are connected in parallel to the n battery cells C1 to Cn, and each is a series circuit of the bypass resistor 10 and the switching element 11. These bypass circuits By1 to Byn are in a state where they can be energized when the switching element 11 is turned on, and are in a non-energized state when the switching element 11 is turned off. That is, the bypass circuit By1 is connected in parallel to the battery cell C1, the bypass circuit By2 is connected in parallel to the battery cell C2, the bypass circuit By3 is connected in parallel to the battery cell C3 (omitted), and the bypass circuit Byn is connected to the battery cell Cn. It is connected in parallel. For example, the resistance value of these bypass circuits By1 to Byn when the switching element 11 is on is, for example, about several mΩ.

The n + 1 transmission lines S1 to Sn + 1 are wirings for transmitting the terminal voltage of each terminal of the n battery cells C1 to Cn to the detection unit D, and each terminal of the n battery cells C1 to Cn (total n + 1). ) And the input end of the detection unit D are connected to each other.

That is, the transmission line S1 connects the positive terminal of the battery cell C1 and the detection unit D, and the transmission line S2 connects the connection point between the negative terminal of the battery cell C1 and the positive terminal of the battery cell C2 and the detection unit D. .. Further, the transmission line S3 connects the connection point between the negative terminal of the battery cell C2 and the positive terminal of the battery cell C3 and the detection unit D, and the transmission line S4 is the negative terminal of the battery cell C3 and the positive terminal of the battery cell C4. The connection point with the terminal and the detection unit D are connected. (Omitted). The transmission line Sn connects the positive terminal of the battery cell Cn and the detection unit D, and the transmission line Sn + 1 connects the negative terminal of the battery cell Cn and the detection unit D.

The n + 1 CR filters F1 to Fn + 1 are low-pass filters for noise removal provided on each of the n + 1 transmission lines S1 to Sn + 1, and are composed of a filter resistor 12 and a filter capacitor 13. The filter resistor 12 is connected in series to each of the n + 1 transmission lines S1 to Sn + 1, and the filter capacitor 13 is connected to each of the n + 1 transmission lines S1 to Sn + 1 at one end and GND (grounded) at the other end. It is connected to the potential).

That is, the CR filter F1 is provided on the transmission line S1, the CR filter F2 is provided on the transmission line S2, the CR filter F3 is provided on the transmission line S3, and the CR filter F4 is provided on the transmission line S4. The CR filter Fn is provided on the transmission line Sn, and the CR filter Fn + 1 is provided on the transmission line Sn + 1.

The detection unit D detects the cell voltage based on the terminal voltage of the battery cells C1 to Cn input via the transmission lines S1 to Sn + 1 and the CR filters F1 to Fn + 1. The detection unit D detects the difference between the pair of terminal voltages of the battery cells C1 to Cn adjacent to each other as the cell voltage.

For example, the detection unit D detects the difference between the pair of terminal voltages input via the transmission line S1 and the transmission line S2 as the cell voltage of the battery cell C1. Further, the detection unit D detects the difference between the pair of terminal voltages input via the transmission line S2 and the transmission line S3 as the cell voltage of the battery cell C2. Further, the detection unit D detects the difference between the pair of terminal voltages input via the transmission line S3 and the transmission line S4 as the cell voltage of the battery cell C3. (Omitted). Further, the detection unit D detects the difference between the pair of terminal voltages input via the transmission line Sn and the transmission line Sn + 1 as the cell voltage of the battery cell Cn.

The microcomputer M is a so-called one-chip microcomputer in which a CPU (Central Processing Unit), a memory, an input / output interface, etc. are integrally incorporated, and a sample value is obtained by A / D converting the cell voltage input from the detection unit D. (Cell voltage data) is acquired, and the cell voltage data and the like are output to the battery ECU.

Further, the microcomputer M functions as a determination unit 14 for determining the presence or absence of an abnormality in the battery cell by processing the cell voltage based on a predetermined program. The determination unit 14 determines whether or not a state in which the cell voltage is equal to or higher than a predetermined threshold value has elapsed for a certain period of time, and if the cell voltage has passed the threshold value for a certain period of time, the battery indicated by the cell voltage. It is determined that cells C1 to Cn are overcharged. Further, when the determination unit 14 determines that any of the battery cells C1 to Cn is overcharged, the microcomputer M is a bypass circuit connected to the battery cells C1 to Cn determined to be overcharged. It functions as a control unit 15 that controls the switching elements 11 of By1 to Byn so that they can be energized.

FIG. 2 is a flowchart for explaining the operation of such a voltage detection device A. As shown in this figure, in the process of determining whether or not to operate the bypass circuit By1, the cell voltage of the battery cell C1 is first acquired (step S1). Here, the detection unit D acquires the cell voltage of the battery cell C1.

Subsequently, it is determined whether or not the cell voltage acquired in step S1 is equal to or higher than the threshold value stored in advance (step S2). The threshold value is set to a value that exceeds the rated voltage of the battery cell C1. Here, the determination unit 14 determines whether or not the cell voltage is equal to or higher than the threshold value by comparing the cell voltage of the battery cell C1 acquired in step S1 with the threshold value stored in advance.

Subsequently, when it is determined in step S2 that the cell voltage is equal to or higher than the threshold value, it is determined whether or not the time when the cell voltage is equal to or higher than the threshold value has elapsed a predetermined time stored in advance (step). S3). The above-mentioned fixed time is set to a time during which it can be determined that the cell voltage is in the overcharged state after a certain period of time elapses in the high cell voltage state. Here, the determination unit 14 determines whether or not a certain period of time has elapsed when the cell voltage is equal to or greater than the threshold value. If it is determined in step S2 that the cell voltage is not equal to or higher than the threshold value, the process returns to step S1 again.

Subsequently, when it is determined in step S3 that the time when the cell voltage is equal to or higher than the threshold value has elapsed for a certain period of time, the bypass circuit By1 is operated (step S4). Here, the control unit 15 turns on the switching element 11 of the bypass circuit By1 so that it can be energized. On the other hand, if it is determined in step S3 that the time when the cell voltage is equal to or higher than the threshold value has not elapsed for a certain period of time, the process returns to step S1 again.

The voltage detection device A performs the operations from step S1 to step S4 as described above for all the battery cells C1 to Cn. The operation of all the bypass circuits By1 to Byn is determined. FIG. 3 is a circuit diagram showing a state in which the battery cell C2 is determined to be overcharged and the bypass circuit By2 connected to the battery cell C2 is operated. As shown in this figure, when the bypass circuit By2 is operated, the switching element 11 of the bypass circuit By2 is turned on, and conduction through the bypass circuit By2 becomes possible.

When conduction via the bypass circuit By2 becomes possible in this way, the positive terminal and the negative terminal of the battery cell C2 are short-circuited, and a large current (fusing current) flows through the fuse Fu2 in a short time. As a result, the fuse Fu2 is blown and the battery cell C2 is disconnected from the conduction path of the battery X. That is, in the voltage detection device A of the present embodiment, when an abnormality is detected in any of the battery cells C1 to Cn, switching of the bypass circuits By1 to Byn connected to the battery cells C1 to Cn in which the abnormality is detected is switched. The element 11 is turned on, and a blown current having a large current density flows through the fuses Fu1 to Fun connected to the battery cells C1 to Cn in which an abnormality is detected, and the fuses Fu1 to Fun can be reliably blown in a short time. .. In this way, even if any of the battery cells C1 to Cn is overcharged, the fuses Fu1 to Fun connected to the overcharged battery cells C1 to Cn can be blown in a short time. It is possible to prevent a large load from being applied to a fuse (not shown) installed between the motor and the fuse.

Further, when the fuse Fu2 connected to the battery cell C2 is blown as described above, the battery cell C1 and the battery cell C3 cannot be electrically connected to each other via the battery cell C2. Therefore, the switching element 11 of the bypass circuit By2 is turned on even after the fuse Fu2 is blown. As a result, the battery cell C1 and the battery cell C3 are conducted through the bypass circuit By2. Therefore, the output from the battery X is continued.

In the voltage detection device A of the present embodiment as described above, the detection unit D for detecting the voltage of each of the plurality of battery cells C1 to Cn connected in series, and the positive and negative terminals of the battery cells C1 to Cn. Bypass circuits By1 to Byn including a switching element 11 and a determination unit 14 for determining the presence or absence of an abnormality in the battery cells C1 to Cn, and battery cells C1 to Cn in which an abnormality is detected by the determination unit 14 It includes a control unit 15 that controls the switching elements 11 of the connected bypass circuits By1 to Byn so that they can be energized.

According to the voltage detection device A of the present embodiment, when an abnormality is detected in the battery cells C1 to Cn, the switching element 11 of the bypass circuits By1 to Byn connected to the battery cells C1 to Cn in which the abnormality is detected is energized. It is possible to energize the battery cells C1 to Cn in which an abnormality is detected, bypassing the battery cells C1 to Cn, and passing through the bypass circuits By1 to Byn. Therefore, even if the battery cells C1 to Cn in which the abnormality is detected are disconnected, it is possible to output the electric power from the battery X provided with the battery cells C1 to Cn. Therefore, according to the voltage detection device A of the present embodiment, power can be supplied from the battery X even when an abnormality is detected in any of the battery cells C1 to Cn. As described above, according to the voltage detection device A of the present embodiment, even when an abnormality is detected in any of the battery cells C1 to Cn, power can be supplied from the battery X to the motor, and an appropriate limp home running can be performed. (Evacuation running) can be realized.

Further, in the voltage detection device A of the present embodiment, the determination unit 14 determines that the battery cells C1 to Cn are abnormal when the battery cells C1 to Cn are overcharged. Therefore, when the battery cells C1 to Cn are overcharged, the overcharged battery cells C1 to Cn can be separated to bypass the overcharged battery cells C1 to Cn to form a transmission path.

Further, in the voltage detection device A of the present embodiment, when the determination unit 14 elapses the voltage of the battery cells C1 to Cn for a certain period of time based on the detection result of the detection unit D, the battery It is determined that cells C1 to Cn are overcharged. Therefore, when the voltage of the battery cells C1 to Cn temporarily exceeds the threshold value due to a detection error or the like, it is possible to prevent an erroneous determination of overcharging.

(Second Embodiment)
Next, the second embodiment of the present invention will be described with reference to the flowchart of FIG. In the description of the present embodiment, the description of the same parts as those of the first embodiment will be omitted or simplified.

FIG. 4 is a flowchart for explaining the operation of the voltage detection device of the present embodiment. As shown in this figure, the voltage detection device of the present embodiment determines whether or not the battery cells C1 to Cn have a thermal abnormality instead of the steps S2 and S3 of the first embodiment. Such a determination is made by the determination unit 14 (step S5). If it is determined in step S5 that the battery cells C1 to Cn have a thermal abnormality, the process proceeds to step S4, and the bypass circuits By1 to connected to the battery cells C1 to Cn determined to have a thermal abnormality are performed. Activate Byn. On the other hand, if it is determined in step S5 that there is no thermal abnormality in the battery cells C1 to Cn, the process returns to step S1 again.

In such a voltage detection device of the present embodiment, the determination unit 14 determines that the battery cells C1 to Cn have an abnormality when the battery cells C1 to Cn have a thermal abnormality. Therefore, when the battery cells C1 to Cn have a thermal abnormality, the battery cells C1 to Cn having a thermal abnormality can be separated to bypass the battery cells C1 to Cn having a thermal abnormality to form a transmission path. As described above, also in the voltage detection device of the present embodiment, as in the first embodiment, power can be supplied from the battery X to the motor even when an abnormality is detected in any of the battery cells C1 to Cn. Therefore, it is possible to realize an appropriate limp home running (evacuation running).

A thermal abnormality is a thermal runaway in which a single battery cell C1 to Cn exceeds the normal temperature and the temperature rises, and a plurality of battery cells C1 to Cn continuously exceed the normal temperature. Includes heat chains with rising temperatures, thermal runaways, or signs of heat chains.

(Third Embodiment)
Next, the third embodiment of the present invention will be described with reference to FIG. In the description of the third embodiment, the description of the same parts as those of the first embodiment will be omitted or simplified.

FIG. 5 is a circuit diagram showing a schematic configuration of the voltage detection device A1 of the third embodiment. As shown in this figure, the voltage detection device A1 of the present embodiment includes a plurality of (n) discharge circuits B1 to Bn.

Each of the n discharge circuits B1 to Bn is connected in parallel to the n battery cells C1 to Cn, and each is a series circuit of the discharge resistor 16 and the discharge switching element 17. These discharge circuits B1 to Bn are in a state where they can be energized when the discharge switching element 17 is turned on, and are in a non-energized state when the discharge switching element 17 is turned off. That is, the discharge circuit B1 is connected in parallel to the battery cell C1, the discharge circuit B2 is connected in parallel to the battery cell C2, the discharge circuit B3 is connected in parallel to the battery cell C3 (omitted), and the discharge circuit Bn is connected to the battery cell Cn. It is connected in parallel.

In such discharge circuits B1 to Bn, when the discharge switching element 17 is turned on under the control of the control unit 15, the electric power of the connected battery cells C1 to Cn is converted into heat by the discharge resistor 16. do. By controlling these discharge circuits B1 to Bn, the voltages of the battery cells C1 to Cn are made uniform.

The discharge resistance 16 of the discharge circuits B1 to Bn has a higher resistance value than the bypass resistance 10 of the bypass circuits By1 to Byn. That is, the resistance value of the bypass circuits By1 to Byn is set to be smaller than the resistance value of the discharge circuits B1 to Bn. Therefore, even if the bypass circuits By1 to Byn and the discharge circuits B1 to Bn connected to the same battery cells C1 to Cn are operated at the same time, the current can be passed through the bypass circuits By1 to Byn, and the battery cells C1 It is possible to prevent ~ Cn from being over-discharged, and to reliably disconnect the battery cells C1 to Cn in which the abnormality has occurred.

In this embodiment, as described above, the discharge circuits B1 to Bn make the voltages of the battery cells C1 to Cn uniform. However, it is also possible to make the voltage of the battery cells C1 to Cn uniform by using the bypass circuits By1 and Byn in the same manner as the discharge circuits B1 and Bn without providing the discharge circuits B1 and Bn.

In this way, also in the voltage detection device A1 of the present embodiment, as in the first embodiment, even if an abnormality is detected in any of the battery cells C1 to Cn, the battery X is transferred to the motor. Power can be supplied, and appropriate limp home running (evacuation running) can be realized.

Although the preferred embodiment of the present invention has been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to the above embodiment. The various shapes and combinations of the constituent members shown in the above-described embodiment are examples, and can be variously changed based on design requirements and the like within a range that does not deviate from the gist of the present invention.

For example, in the above embodiment, the configuration in which the microcomputer M functions as the determination unit 14 and the control unit 15 has been described. However, the present invention is not limited to this, and it is also possible to adopt a configuration in which the determination unit 14 and the control unit 15 are embodied by a semiconductor device different from the microcomputer M.

10 ... Bypass resistor, 11 ... Switching element, 12 ... Filter resistance, 13 ... Filter capacitor, 14 ... Judgment unit, 15 ... Control unit, 16 ... Discharge resistance, 17 ... Discharge switching element, A ... Voltage detector, A1 ... Voltage detector, B1-Bn ... Discharge circuit, By1-Byn ... Bypass circuit, C1-Cn ... Battery cell, D ... Detector, F1-Fn + 1 ... CR Filter, Fu1-Fun ... Hughes, M ... Microcomputer, S1-Sn + 1 ... Transmission line, X ... Battery

Claims (6)

A detector that detects the voltage of each of a plurality of battery cells connected in series,
A bypass circuit that connects the positive and negative terminals of at least one of the battery cells and includes a switching element.
A determination unit for determining the presence or absence of an abnormality in the battery cell to which the bypass circuit is connected,
A voltage detection device including a control unit that controls a switching element of the bypass circuit connected to the battery cell in which an abnormality is detected by the determination unit so as to be energized. The voltage detection device according to claim 1, wherein the determination unit determines that the battery cell has an abnormality when the battery cell is overcharged. The determination unit is characterized in that, based on the detection result of the detection unit, the battery cell is determined to be overcharged when the voltage of the battery cell elapses for a certain period of time from a preset threshold value. The voltage detection device according to claim 2. The voltage detection device according to claim 1, wherein when the determination unit detects a thermal abnormality in the battery cell, it determines that the battery cell has an abnormality. The voltage detection device according to any one of claims 1 to 4, further comprising a discharge circuit having a discharge resistor and a discharge switching element connected in parallel and connected in series with the bypass circuit. The voltage detection device according to claim 5, wherein the resistance value of the bypass circuit is smaller than the resistance value of the discharge circuit.

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