JP7331543B2 - BUILD BATTERY MONITORING SYSTEM AND BATTERY FAILURE DETERMINATION METHOD - Google Patents

Description

The present invention relates to a system for detecting and monitoring the voltage of each battery cell in an assembled battery configured by connecting a plurality of battery cells in series in multiple stages, and to a failure determination method for the assembled battery.

In general, a discharge switch is connected in parallel to each battery cell that constitutes an assembled battery in order to equalize terminal voltages. Then, as shown in FIG. 10, the sequence for diagnosing the failure of the discharge switches is to measure the voltages of all the cells while only the odd-numbered discharge switches are turned on at the same time. The procedure is to measure the voltages of all the cells while simultaneously turning on only the located discharge switches.

Assuming that the voltage of the battery cell is Vcell, turning on the discharge switch halves the voltage Vcell by the two discharge resistors. Therefore, by measuring Vcell/2 for odd-numbered and even-numbered battery cells in each case, it is confirmed that each discharge switch is healthy.

By the way, in Patent Literature 1, the applicant has proposed a novel connection form for RC filters and discharge resistors provided corresponding to each battery cell constituting an assembled battery.

JP 2017-112677 A

As shown in FIG. 11, in the connection configuration of Patent Document 1, when the odd-numbered discharge switch is turned on, the voltage of the terminal S2 becomes Vcell/2. The voltage between them is (3·Vcell/2). In this case, the input voltage to the voltage detection device becomes excessive.

The present invention has been made in view of the above circumstances, and its object is to prevent the input voltage to the voltage detection device from becoming excessive even in a measurement system that employs a specific RC filter and discharge resistor connection configuration. It is an object of the present invention to provide an assembled battery monitoring system and an assembled battery failure determination method capable of performing failure determination while avoiding failures.

According to the assembled battery monitoring system of claim 1, the first to third terminals provided corresponding to one battery cell are connected to the voltage detection device via connection switches. The second and third terminals are used to sense the voltage of the battery cell through the output terminals of an RC filter connected in parallel with the battery cell. The discharge resistance element is connected between the positive and negative terminals of the battery cell and the first and third terminals, respectively, and the discharge switch is connected between the first and third terminals. As a result, when the discharge switch is turned on, a battery cell discharge path is formed via the two discharge resistance elements. For two battery cells having a common negative terminal and positive terminal, the third terminal of the upper cell becomes the first terminal of the lower cell.

When the terminal voltage of each battery cell is detected and the discharge switches of the even-numbered and odd-numbered discharge switches are simultaneously turned on, the control device detects the terminal voltage of the corresponding battery cell. The failure of the discharge switch is determined by comparing the voltage difference between the two voltages with a threshold value . Further, by comparing the voltage detected for the corresponding battery cell with a threshold value, failure determination of the harness connected to the RC filter is performed. With this configuration, if the voltage of the battery cell is Vcell, the voltage of Vcell/2 is detected for the even-numbered and odd-numbered battery cells in each case, thereby confirming that the measurement system is normal. can. At this time, the control device may control the connection switch so that the second and third terminals corresponding to the battery cell to be measured are sequentially connected to the input terminal of the voltage detection device. As a result, it is possible to prevent an excessive voltage from being input to the voltage detection device.

Furthermore , it is possible to detect short-circuit failures and open-circuit failures of the discharge switch, open-circuit failures of the discharge resistance element, open-circuit failures of the second and third terminals, and the like.

1 is a diagram showing a configuration of an assembled battery monitoring system according to an embodiment; FIG. Diagram showing the failure diagnosis sequence of the discharge switch Diagram showing the measurement state of "Normal detection" A diagram showing the measurement state of "discharge switch diagnosis even number" Diagram showing the measurement state of "discharge switch diagnosis odd number" Timing chart showing fault diagnosis sequence in normal condition The figure which shows the ON fixation state of the switch for discharge. FIG. 4 is a diagram showing an open state of a harness connecting an output terminal of an RC filter and a terminal V2; The figure which shows the OFF fixation state of the switch for discharge. A diagram showing a short-circuit state of a capacitor in an RC filter Timing chart showing a fault diagnosis sequence corresponding to the case of FIG. 5A Timing chart showing a fault diagnosis sequence corresponding to the case of FIG. 5B Timing chart showing a fault diagnosis sequence corresponding to the case of FIG. 5C Timing chart showing a fault diagnosis sequence corresponding to the case of FIG. 5D Diagram showing a typical fault diagnosis sequence A diagram for explaining the voltage measured on the battery cell side one level higher when the odd-numbered discharge switch is turned on.

An embodiment will be described below. As shown in FIG. 1, the assembled battery 1 is configured by connecting a plurality of battery cells 2 (1, 2, 3, . . . ), which are secondary batteries, in series in multiple stages. The voltage monitoring IC 3 has connection terminals 9 and 4 corresponding to the positive and negative terminals of each battery cell 2, and the connection terminal 4 is connected to the negative terminal of the corresponding battery cell 2 via a discharge resistance element 5. connected to each other. The voltage monitoring IC 3 corresponds to a voltage monitoring device.

A series circuit of a resistance element 6 and a capacitor 7 is connected to the positive terminal and negative terminal of each battery cell 2 , and these constitute an RC filter 8 . A connection terminal 9 is connected to an output terminal of an RC filter 8 which is a common connection point of the resistance element 6 and the capacitor 7 . A discharge switch 10 composed of an N-channel MOSFET is connected between the connection terminal 4 of the corresponding battery cell 2 and the connection terminal 4 of the battery cell 2 located one step above, inside the voltage monitoring IC 3 . ing. Since the negative terminal of the battery cell 2 one level above is shared with the positive terminal of the battery cell 2 below it, the discharge switch 10 connects between the positive and negative terminals of the corresponding battery cell 2, respectively. They are connected via a discharge resistance element 5 .

The voltage monitoring IC 3 has a control device 11 and a voltage detection device 12 . The voltage detection device 12 is, for example, an A/D converter. The connection terminals 9 and 4 corresponding to each battery cell 2 are commonly connected to each input terminal of the voltage detection device 12 via connection switches 13 and 14, respectively. The control device 11 controls ON/OFF of the connection switches 13 and 14 to cause the voltage detection device 12 to detect the voltage of each battery cell 2 individually. The detection result is input to the control device 11 . The control device 11 also controls ON/OFF of the discharge switch 10 to perform voltage equalization processing of each battery cell 2 . The above constitutes the assembled battery monitoring system 15 .

Here, for the battery cell 2(1), for example, the connection terminals 4(2), 9(1) and 4(1) correspond to the first, second and third terminals, respectively. Also, when looking at the battery cell 2(2), the connection terminals 4(3), 9(2) and 4(2) correspond to the first, second and third terminals, respectively. For these terminals, in order to clarify the voltage to be measured, connection terminals 9(1) and 4(1) are referred to as terminals V1 and S1, respectively, and connection terminals 9(2) and 4(2) are referred to as terminals V1 and S1, respectively. are sometimes referred to as terminals V2 and S2, respectively.

Next, the operation of this embodiment will be described. As shown in FIG. 2, the diagnostic sequence of this embodiment first performs "normal detection" for detecting the voltage of each battery cell 2. FIG. This corresponds to the first step. The corresponding detection state is shown in FIG. 3A. The detection result is stored in a normal register inside the control device 11 . Next, the “discharge SW diagnosis even number” is performed to turn ON only the discharge switches 10 arranged in the even-numbered order. This corresponds to the second step. At this time, the connection switches 13 and 14 are sequentially turned on and off to detect the voltages of the even-numbered battery cells 2 , and the detection results are stored in the diagnostic register (even number) inside the control device 11 . The corresponding detection state is shown in FIG. 3B.

Next, the “discharge SW diagnosis odd number” is performed to turn ON only the discharge switches 10 arranged in the odd-numbered order. This corresponds to the third step. Also at this time, the connection switches 13 and 14 are sequentially turned on and off to detect the voltages of the odd-numbered battery cells 2 , and the detection results are stored in the diagnostic register (odd number) inside the control device 11 . The corresponding detection state is shown in FIG. 3C. Then, the controller 11 compares each voltage value stored in the normal register and the diagnostic register to make a determination. These "normal register reading", "diagnostic register reading", and "comparison determination" correspond to the fourth step. Needless to say, the order of "discharge SW diagnosis even number" and "discharge SW diagnosis odd number" may be exchanged.

As shown in FIG. 4, if normal, the voltage Vcell of each battery cell 2 is detected in the "normal detection", and in the "discharge SW diagnosis even number" and "discharge SW diagnosis odd number", even-numbered cells and odd-numbered cells are detected, respectively. A voltage Vcell/2 is detected for the battery cell 2 of .

For example, as shown in FIG. 5A, if the discharge switch 10(2) is short-circuited, that is, stuck in the ON state, the potentials of the terminals S3 and S2 become Vcell/2. Therefore, as shown in FIG. 6, the measurement results of both "normal detection" and "discharge SW diagnosis even" are Vcell/2, so it is possible to determine the short failure of the discharge switch 10(2). In this case, in the "comparison judgment", the absolute value of the difference between the "normal register read" value multiplied by 0.5 and the "diagnostic register read" value is taken, and the result is set to a threshold value near zero. This is done by comparing with This is called "difference comparison".

For example, as shown in FIG. 5B, if the harness connecting between the output terminal of the RC filter 8 and the terminal V2 is disconnected and becomes open, no potential is generated at the terminal V2. Therefore, as shown in FIG. 7, both of the measurement results of "normal detection" and "discharge switch diagnosis even number" are zero, so disconnection of the harness can be determined. In this case, the "comparative determination" is performed by comparing the value of "diagnostic register read" with a threshold set near zero. This is called "absolute value comparison". Further, the difference between the measurement results of "normal detection" and "discharge switch diagnosis even number" may be compared with a threshold near zero to perform "difference comparison". The same result is obtained when a short failure occurs between the terminals V2 and S2.

For example, as shown in FIG. 5C, if the discharge switch 10(2) has an open failure, that is, stuck in the OFF state, the potentials of the terminals V2 and S2 do not change to Vcell/2. Therefore, as shown in FIG. 8, the measurement result of the "discharge SW diagnosis even number" is Vcell, so that the open failure of the discharge switch 10(2) can be determined. In this case, the "comparison determination" is performed by taking the absolute value of the difference between the "normal register read" value and the "diagnostic register read" value, and comparing the result with a threshold set near zero. This is also a "difference comparison". The same result is obtained when the harness connecting the discharge resistance element 5(3) and the terminal S3 is disconnected and becomes open.

Also, as shown in FIG. 5D, for example, when the capacitor 7(2) of the RC filter 8(2) short-circuits, the terminal V2 becomes the potential of the negative terminal of the battery cell 2. FIG. Therefore, as shown in FIG. 9, the measurement result of "normal detection" is zero. Also, the measurement result of the “discharge switch diagnosis even number” is −Vcell/2. This makes it possible to determine whether the capacitor 7(2) is short-circuited. In this case, the "comparative determination" is performed by comparing the value of the "diagnostic register read" with a threshold set to a negative value near zero. The same result is obtained when the output terminal of the resistance element 6(2) is short-circuited to the negative terminal of the battery cell 2. FIG.

As described above, according to the present embodiment, the connection terminals 9 and 4 provided corresponding to the battery cells 2 are connected to the voltage detection device 12 via the connection switches 13 and 14, respectively. Connection terminals 9 and 4 are used to detect the voltage of battery cell 2 via the output terminal of RC filter 8 . The discharge resistance element 5 is connected between the positive and negative terminals of the battery cell 2 and the connection terminals 9 and 4, respectively, and the discharge switch 10 is connected between the connection terminals 4(n+1) and 4(n). connected to n is a natural number.

When the even-numbered discharge switches 10 and the odd-numbered discharge switches 10 are turned on at the same time, the control device 11 performs failure determination based on the voltage detected for the corresponding battery cells 2. . With this configuration, it can be confirmed that the measurement system is normal because the measurement results of the "discharge SW diagnosis even number" and the "discharge SW diagnosis odd number" are both Vcell/2. Thus, it is possible to avoid inputting an excessive voltage to the voltage detection device 12 .

Further, the control device performs failure determination based on the difference between the measurement result of "normal detection" and the measurement result of "discharge SW diagnosis even number" or "discharge SW diagnosis odd number". This makes it possible to detect a short-circuit failure or open failure of the discharge switch 10, an open failure of the discharge resistive element 5, an open failure of the connection terminals 9 and 4 or the harnesses corresponding to them, and the like.

(Other embodiments)
An inductor may be inserted between the positive terminal of each battery cell 2 and the RC filter 8 or the like, or a Zener diode or a smoothing capacitor may be connected in parallel with the battery cell 2 .
An element constituting each switch may be an FET, a bipolar transistor, an analog switch, or the like.
Although the present disclosure has been described with reference to examples, it is understood that the present disclosure is not limited to such examples or structures. The present disclosure also includes various modifications and modifications within the equivalent range. In addition, various combinations and configurations, as well as other combinations and configurations, including single elements, more, or less, are within the scope and spirit of this disclosure.

In the drawings, 1 is an assembled battery, 2 is a battery cell, 3 is a voltage monitoring IC, 4 is a connection terminal, 5 is a discharge resistance element, 6 is a resistance element, 7 is a capacitor, 8 is an RC filter, 9 is a connection terminal, 10 is a discharge switch, 11 is a control device, and 12 is a voltage detection device.

Claims (2)

A voltage detection device (12) for detecting the voltage of each battery cell in an assembled battery (1) configured by connecting a plurality of battery cells (2) in series in multiple stages;
a discharge resistance element (5) and an RC filter (8) respectively connected between each battery cell and the voltage detection device;
a discharge switch (10) disposed corresponding to each battery cell for discharging the corresponding battery cell;
A control device (11) for controlling on/off of the discharge switch,
the RC filters are connected in parallel to corresponding battery cells;
First to third terminals (9, 4) are provided corresponding to one battery cell,
The first to third terminals are connected to the voltage detection device via connection switches (13, 14), respectively,
The control device also controls on/off of the connection switch,
the second and third terminals are used to sense the voltage of the battery cell via the output terminal of the RC filter;
The discharge resistance element is connected between each of positive and negative terminals of the battery cell and the first and third terminals,
The discharge switch is connected between the first and third terminals,
When the result of detecting the terminal voltage of each battery cell and the even-numbered discharge switches and the odd-numbered discharge switches are turned on at the same time, the control device detects the corresponding battery cell. By comparing the difference from the detected voltage with a threshold value, the failure determination of the discharge switch is performed. Assembled battery monitoring system that judges the failure of the harness . Discharging resistance elements and RC filters respectively connected between each battery cell and first to third terminals corresponding to each battery cell in an assembled battery configured by connecting a plurality of battery cells in series in multiple stages ,
A discharge switch arranged corresponding to each battery cell and discharging the corresponding battery cell,
the RC filters are connected in parallel to corresponding battery cells;
using the second and third terminals to sense the voltage of the battery cell via the output terminal of the RC filter;
using the first and third terminals to form a discharge path for the battery cell when the discharge switch is turned on;
In a configuration in which the discharge resistive element is connected between each of the positive and negative terminals of the battery cell and the first and third terminals,
The result of detecting the terminal voltage of each battery cell, and the voltage detected for the corresponding battery cell when the even-numbered discharge switches and the odd-numbered discharge switches are turned on at the same time. Failure determination of the discharge switch is performed by comparing the difference with a threshold, and failure determination of the harness connected to the RC filter is performed by comparing the voltage detected for the corresponding battery cell with the threshold. A failure determination method for assembled batteries.

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