JP2013078233A - Monitor for assembled battery, and battery pack with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a monitor for assembled battery that can avoid disconnecting an assembled battery as much as possible each time abnormality occurs by allowing a charging path and/or a discharging path for assembled battery to be disconnected until a predetermined number of unit cells become abnormal, and a battery pack with the monitor.SOLUTION: The monitor for assembled battery includes first voltage detection means and second voltage detection means which are doubled for common unit cells. The first and second voltage detection means detect unit cells being abnormal at mutually different levels. When the number of unit cells in light overcharging states exceeds a reference ratio, the charging path is disconnected. Namely, the charging path is allowed to be disconnected until a plurality of unit cells become abnormal. When at least one unit cell in a serious overcharging state is present, the charging path is speedily disconnected.

Description

  The present invention relates to an assembled battery configured by connecting a plurality of unit cells each including a secondary battery in series, and detects the voltage of each unit cell constituting the assembled battery to monitor the state of the cell. And a battery pack provided with the monitoring device.

  In recent years, an assembled battery in which a plurality of secondary batteries are electrically connected in series is known for driving an electric vehicle, a hybrid vehicle, or the like. As an example of this type of secondary battery, a lithium ion battery is known.

  Lithium ion batteries have the advantage of large capacity, but have the disadvantage of not being able to perform their functions in an overcharged or overdischarged state.

  Therefore, when using an assembled battery, it is necessary to monitor the charge state of each unit cell so as not to reach an overcharge state or an overdischarge state. Usually, a monitoring device for monitoring the state of each unit cell is connected to the assembled battery, and the voltage or current of each unit cell serving as an index is measured.

  Conventionally, as an example of a monitoring device, Patent Literature 1 discloses a monitoring device in which two battery blocks are connected in series via a fuse and a contactor is connected to the output side of a unit cell. When an overcurrent flows through the unit cell, the monitoring device blows the fuse to cut off the current of the unit cell, and further detects the overcurrent and switches the contactor off to cut off the current.

JP 2008-193776 A

  However, the assembled battery monitoring device disclosed in Patent Document 1 cuts off the current by blowing a fuse when an overcurrent flows through one unit cell, so that the entire assembled battery is cut off. If it will be in this state, electric vehicles, such as an electric vehicle and a hybrid vehicle, will not be able to run with a motor. Even if the unit cell state is abnormal, it should be avoided as much as possible to shut off the entire assembled battery every time it is abnormal as long as it is within the allowable range for the entire assembled battery.

  Therefore, the present invention has been made to solve such problems, and the object of the present invention is to charge and / or discharge an assembled battery until a plurality of abnormal unit cells occur. It is an object of the present invention to provide an assembled battery monitoring device that can avoid interruption of the entire assembled battery as much as possible by allowing the interruption of the battery, and a battery pack including the monitoring device.

  The assembled battery monitoring device of the present invention is configured by connecting a plurality of unit cells made of secondary batteries in series, and detects the voltage of each unit cell constituting the assembled battery with respect to the assembled battery having a charging circuit. Thus, the assembled battery monitoring device monitors the state of charge of the cell. The battery pack monitoring apparatus includes a voltage detection unit, a threshold setting unit, and a wiring interruption unit, wherein the first voltage threshold is set by the threshold setting unit, and further includes a monitoring unit. The monitoring unit includes the voltage detection unit. When a plurality of unit cells exceeding the first voltage threshold are detected by the above, the charging path is interrupted.

  According to this configuration, the charging path of the assembled battery can be blocked until a plurality of abnormal (a voltage exceeding the threshold voltage) unit cell occurs, so that it is possible to avoid blocking the entire assembled battery whenever possible. .

  Preferably, the monitoring device further has a second voltage threshold, and shuts off the charging path when at least one unit cell exceeding the second voltage threshold is detected by the voltage detection means.

  According to this structure, when it falls into the event which should cut off the whole assembled battery, the charging path of an assembled battery can be interrupted | blocked reliably.

  Preferably, the monitoring device calculates a ratio of the number of cells exceeding the first voltage threshold to the total number of assembled battery cells, and interrupts the charging path when the calculation result exceeds a predetermined reference ratio. Further, the reference ratio is a value selected from a range exceeding 50% and less than 100%.

  According to this configuration, the condition for blocking the charging path can be set more finely.

  More preferably, the voltage detection means includes a first voltage detection means and a second voltage detection means connected in parallel to the common unit cell, and the first voltage threshold value has a first voltage threshold value. The second voltage threshold is set in the second voltage detection means.

  According to this configuration, the abnormality of the unit cells at different levels can be detected by the first voltage detection unit and the second voltage detection unit that are duplicated with respect to the unit cell. Further, even if one of the first voltage detection means and the second voltage detection means fails, the remaining voltage detection means can continue to detect the unit cell voltage.

  More preferably, one of the first voltage detection means and the second voltage detection means is constituted by a circuit including a microcomputer, and the other voltage detection means is constituted by a circuit not including the microcomputer. The

  When all voltage detection means are configured by a circuit including a microcomputer, when the number of unit cells connected in series increases, an increase in circuit scale and an increase in power consumption are proportional to each other in a circuit mainly composed of a microcomputer. Therefore, although the battery capacity does not increase, there arises a problem that the power consumption increases. According to this configuration, the power consumption can be suppressed as much as possible even if the number of unit cells connected in series increases. In addition, since the microcomputer may run away due to factors such as external noise, detection and determination of the occurrence of abnormalities in the unit cell in the voltage detection means compared to the case where all the voltage detection means are configured with a circuit including a microcomputer. Certainty is guaranteed.

  The assembled battery monitoring device of the present invention is configured by connecting a plurality of unit cells made of secondary batteries in series, and detects the voltage of each unit cell constituting the assembled battery with respect to the assembled battery having a discharge circuit. Thus, the battery pack monitoring device monitors the discharge state of the cell. The assembled battery monitoring device includes a voltage detection unit, a threshold setting unit, and a wiring interruption unit, a third voltage threshold is set by the threshold setting unit, and further includes a monitoring unit. When a plurality of unit cells lower than the third voltage threshold are detected by the detection means, the discharge path is interrupted. According to this configuration, since the interruption of the discharge path of the assembled battery can be allowed until a plurality of abnormal cells (in a state exceeding the voltage threshold) are generated, it is possible to avoid the interruption of the entire assembled battery whenever possible.

  Preferably, the monitoring device further has a fourth voltage threshold value, and shuts off the discharge path when at least one unit cell lower than the fourth voltage threshold value is detected by the voltage detection means. According to this configuration, when the entire assembled battery falls into an event that should be blocked, the discharge path of the assembled battery can be reliably blocked.

  Preferably, the monitoring device calculates a ratio of the number of cells below the third voltage threshold to the total number of cells in the assembled battery, and interrupts the discharge path when the calculation result exceeds a predetermined reference ratio. According to this configuration, the condition for interrupting the discharge path can be set more finely.

  More preferably, the voltage detection means includes a third voltage detection means and a fourth voltage detection means connected in parallel to the common unit cell, and the third voltage detection means has a third voltage threshold value. The fourth voltage threshold is set in the fourth voltage detection means. According to this configuration, the abnormality of the unit cells at different levels can be detected by the third voltage detection unit and the fourth voltage detection unit that are duplicated with respect to the unit cell. Further, even if one of the third voltage detection means and the fourth voltage detection means fails, the remaining voltage detection means can continue to detect the unit cell voltage.

  More preferably, one of the third voltage detection means and the fourth voltage detection means is constituted by a circuit including a microcomputer, and the other voltage detection means is constituted by a circuit not including the microcomputer. The The third voltage detection means is the first voltage detection means, and the fourth voltage detection means is the second voltage detection means. When all voltage detection means are configured by a circuit including a microcomputer, when the number of unit cells connected in series increases, an increase in circuit scale and an increase in power consumption are proportional to each other in a circuit mainly composed of a microcomputer. Therefore, although the battery capacity does not increase, there arises a problem that the power consumption increases. According to this configuration, the power consumption can be suppressed as much as possible even if the number of unit cells connected in series increases. In addition, since the voltage detection means does not include a microcomputer, the detection of the abnormality of the unit cell in the voltage detection means and the certainty of determination can be made as compared with the case where all the voltage detection means are configured by a circuit including a microcomputer. Secured.

  More preferably, the third voltage detection means is the first voltage detection means, and the fourth voltage detection means is the second voltage detection means. According to this configuration, it is not necessary to newly provide a voltage detection means, and the monitoring device main body can be reduced in size.

  More preferably, the unit cell is a lithium ion battery, and the assembled battery is a power source for driving an electric vehicle or a hybrid vehicle. The assembled battery having a plurality of unit cells each including a secondary battery connected in series and having the charging path and / or the discharging path, and any one of claims 1 to 14. The battery pack monitoring device is provided. According to this configuration, the lithium ion battery is configured as a unit cell with a lithium ion battery that has a high energy density but requires more strict overcharge or overdischarge countermeasures, so that the state of the lithium ion battery can be monitored and controlled safely In addition, the performance of the battery can be sufficiently extracted. In addition, since the assembled battery is used for driving an electric vehicle and a hybrid vehicle, it is possible to improve the use efficiency of a driving power source configured by connecting a large number of unit cells in series in order to obtain a high output voltage. Furthermore, since the interruption of the charging path and / or the discharging path of the assembled battery can be allowed until a plurality of abnormal unit cells occur, it is possible to provide a battery pack that can avoid interruption of the entire assembled battery whenever possible.

  According to the present invention, an assembled battery capable of avoiding shutting down the entire assembled battery whenever an abnormality occurs by allowing the charging circuit or discharging circuit of the assembled battery to be interrupted until a plurality of abnormal unit cells occur. A monitoring device and a battery pack including the monitoring device can be provided.

It is a block diagram which shows the whole structure of the monitoring apparatus of the assembled battery which concerns on this Embodiment. It is a figure explaining the structure of a 1st voltage detection means and a 2nd voltage detection means. It is a figure explaining the procedure in which the voltage data of a unit cell are processed by the threshold value setting part and the monitoring means. It is a flowchart explaining abnormality determination and interruption | blocking control by the assembled battery monitoring apparatus which concerns on this Embodiment. It is a flowchart explaining abnormality determination and interruption | blocking control by the assembled battery monitoring apparatus which concerns on this Embodiment.

  Hereinafter, an assembled battery monitoring apparatus according to an embodiment of the present invention will be described with reference to the accompanying drawings. In the following embodiments, an assembled battery monitoring device used mainly for driving an electric vehicle such as an electric vehicle or a hybrid vehicle will be described. However, the present invention similarly applies to an assembled battery used for driving an electric motorcycle, for example. Can be adopted.

  In the following description, terms (for example, “rear stage”) representing directions and positions are used for convenience, but these are for facilitating understanding of the invention, and the technical meaning of the present invention depends on the meaning of these terms. The range is not limited. Further, the following description is merely illustrative in nature, and is not intended to limit the present invention, its application, or its use.

  As shown in FIG. 1, an assembled battery monitoring device 1 (hereinafter simply referred to as “monitoring device 1”) is a series in which N unit cells (N is an integer of 2 or more) are connected in series. The voltage of each unit cell of the connection body is detected, and the state of each unit cell is monitored. As shown in the figure, the monitoring device 1 includes an assembled battery 2, voltage detection means 3, and monitoring means (BMU [Battery Management Unit]) 4. In the figure, reference numeral 5 denotes a host CPU that controls the entire electric vehicle, and is connected to the monitoring means 4 via a communication line (not shown).

  The assembled battery 2 is used as a driving power source for a traveling motor mounted on an electric vehicle such as an electric vehicle or a hybrid vehicle. As the secondary battery constituting the assembled battery 2, for example, a lithium ion battery is used. In addition, in FIG. 1, although some unit cells 20-1, 20-2, and 20-3 of the serial connection body of the unit cell which comprises the assembled battery 2 are described, in fact, it is several hundred volts In order to output a high voltage, the assembled battery 2 is composed of a series connection body of several tens to several hundreds of unit cells.

  As shown in the drawing, a charging path 6 and a discharging path 7 are connected to the positive terminal and the negative terminal at both ends of the assembled battery 2, respectively.

  The charging path 6 includes a power supply line 60 drawn from the positive terminal and the negative terminal at both ends of the assembled battery 2, and a circuit breaker connected to the positive terminal side and the negative terminal side of the assembled battery 2 in the power supply line 60, respectively. 62a, 62b (wiring blocking means). When charging the assembled battery 2, a charger 64 is connected between the circuit breakers 62a and 62b. The interruption of the charging power from the charger 64 to the assembled battery 2 is electrically executed by the opening operation of the circuit breakers 62a and 62b.

  Similarly, the discharge path 7 is connected to the power supply line 70 drawn from the positive electrode terminal and the negative electrode terminal at both ends of the assembled battery 2, respectively, and to the positive electrode terminal side and the negative electrode terminal side of the assembled battery 2 in the power supply line 70, respectively. Circuit breakers 72a and 72b (wiring block means). A load composed of a traveling motor 74 or the like is connected between the circuit breakers 72a and 72b via an inverter. The interruption of the electric power from the assembled battery 2 to the load is electrically executed by the opening operation of the circuit breakers 72a and 72b.

  Control of the circuit breakers 62a and 62b in the charging path 6 and the circuit breakers 72a and 72b in the discharging path 7 will be described later.

  The voltage detection means 3 is composed of two voltage detection circuits connected in parallel to a common unit cell. As shown in the figure, the voltage detection means 3 includes a first voltage detection circuit (first voltage detection means or third voltage detection means) 30a for detecting the voltage of the unit cell 20-1 and a second voltage detection circuit. (Second voltage detection means or fourth voltage detection means) 32a. Similarly, a first voltage detection circuit 30c that has a first voltage detection circuit 30b and a second voltage detection circuit 32b that detect the voltage of the unit cell 20-2 and detects the voltage of the unit cell 20-3. And a second voltage detection circuit 32c.

  Between the first voltage detection circuits 30a, 30b, 30c and the second voltage detection circuits 32a, 32b, 32c and the monitoring means 4, the first voltage detection circuits 30a, 30b, 30c, and Redundant circuits 35a, 35b, and 35c for outputting the voltage data of the unit cells 20-1, 20-2, and 20-3 detected by the second voltage detection circuits 32a, 32b, and 32c to the monitoring unit 4 are provided. .

  Further, the configuration of the first voltage detection circuit 30a will be described with reference to FIG. Since the first voltage detection circuits 30b and 30c have the same configuration, the description thereof is omitted. As illustrated, the first voltage detection circuit 30a includes a first switching circuit 300, an analog-digital conversion circuit 310 (hereinafter simply referred to as “AD conversion circuit 310”), and a microcomputer 312 (hereinafter referred to as “AD conversion circuit 310”). Simply called “microcomputer 312”).

  The first switching circuit 300 includes voltage detection lines 303 and 304 that connect between the potential detection points 301 a and 302 a on the positive terminal side and the negative terminal side of the unit cell 20-1 and the AD conversion circuit 310.

  A field effect transistor 305 (switching element) is interposed in the voltage detection line 303. A switching circuit 306 for turning on / off the field effect transistor 305 at a predetermined cycle is connected to the gate side of the field effect transistor 305.

  Between the potential detection point 301a on the positive terminal side of the unit cell 20-1 and the drain of the field effect transistor 305, and between the potential detection point 302a on the negative terminal side of the unit cell 20-1 and the AD conversion circuit 310, Protection resistors R1 and R2 are connected. Further, a capacitor 307 is connected between the source of the field effect transistor 305 and the AD conversion circuit 310 and between the voltage detection lines 303 and 304. With such a configuration, when the field effect transistor 305 is turned on, a potential that changes between the protective resistors R1 and R2 (that is, between the connection points of the capacitor 307) is accumulated in the capacitor 307.

  When the field effect transistor 305 is turned off, the AD conversion circuit 310 takes in the potential stored in the capacitor 307 (that is, voltage data of the unit cell 20-1), converts the analog signal into a digital signal, and converts the digital signal into the digital signal. The data is output to the microcomputer 312 at the subsequent stage.

  The microcomputer 312 has a CPU that functions as a central processing unit, a ROM that stores programs and program data, a RAM that functions as a buffer that temporarily stores operation areas of the CPU and voltage data (both not shown). . The microcomputer 312 operates by receiving power supply from a power supply source (not shown).

  A first threshold value setting unit (threshold value setting means) (not shown) for detecting the state of the unit cell 20-1 is set in the microcomputer 312. The first threshold value setting unit includes a first determination. A threshold value and a third determination threshold value (first and third voltage threshold values) are set. The first and third determination thresholds will be described later.

  As illustrated, the first voltage detection circuit 30a includes a first watchdog timer WDT1 for detecting abnormal operation or runaway of the microcomputer 312. When an abnormality occurs in the microcomputer 312, an abnormal operation or runaway of the microcomputer 312 is prevented by applying a reset by the watchdog timer WDT 1. The monitoring information of the microcomputer 312 by the first watchdog timer WDT1 is output to the host CPU 5 via the monitoring means 4.

  Next, the configuration of the second voltage detection circuit 32a will be described. As shown in FIG. 2, the second voltage detection circuit 32a includes a second switching circuit 320, an AD conversion circuit 330, and a second threshold setting unit 340 (threshold setting means). Since the second voltage detection circuits 32b and 32c have the same configuration, the description thereof is omitted. In the figure, the configurations of the second switching circuit 320 and the AD conversion circuit 330 are the same as those of the first switching circuit 300 and the AD conversion circuit 310 of the first voltage detection circuit 30a except for the reference numerals. is there.

  In the second threshold setting unit 340, a second determination threshold and a fourth determination threshold (second and fourth voltage thresholds) are set. The second and fourth determination thresholds will be described later together with the first and third determination thresholds.

  As described above, the voltage detection function of the second voltage detection circuit 32a is realized only by a hardware circuit without performing software processing using a CPU (microcomputer). As a result, the reliability with respect to failure and malfunction is increased. Further, power consumption can be reduced as compared with the case where all the voltage detection circuits are configured by a circuit including a microcomputer.

  The redundant circuit 35a has a function of outputting the voltage data of the unit cell 20-1 obtained by the first voltage detection circuit 30a and the second voltage detection circuit 32a to the monitoring means 4, as well as abnormal operation of the microcomputer 312. Has a function to detect runaway.

  Specifically, a second watchdog timer WDT2 is provided in the redundancy circuit 35a, and the microcomputers 312 are mutually monitored in cooperation with the first watchdog timer WDT1. Similarly, monitoring information of the microcomputer 312 by the second watchdog timer WDT2 is also output to the host CPU 5 via the monitoring means 4.

  Next, the first threshold value setting unit 315 (first and third determination threshold values) and the second threshold value setting unit 340 (second and fourth determination threshold values) set in the microcomputer 312 are shown in FIG. This will be described with reference to FIG.

  The unit cells 20-1, 20-2, and 20-3 used in the present embodiment are designed to operate the electric vehicle normally in a range of 2.7V to 4.15V, for example. The first and third determination thresholds and the second and fourth determination thresholds are set to detect unit cells that deviate from this voltage range. Each determination threshold value can be appropriately set according to the type and characteristics of the secondary battery.

  More specifically, the first determination threshold is a threshold voltage for detecting a slight overcharge for each of the unit cells 20-1, 20-2, 20-3, and is set to, for example, 4.2V. . The third determination threshold is a threshold voltage for detecting a slight overdischarge for each unit cell 20-1, 20-2, 20-3, and is set to, for example, 2.7V.

  On the other hand, the second determination threshold is a threshold voltage for detecting severe overcharge for each unit cell 20-1, 20-2, 20-3, for example, 4.25V. The fourth determination threshold is a threshold voltage for detecting severe overdischarge for each unit cell 20-1, 20-2, 20-3, and is set to 2.65V, for example.

  By configuring as described above, the unit cells 20-1, 20- are formed by the voltage detection means 3 which is duplicated by the first voltage detection circuits 30a, 30b, 30c and the second voltage detection circuits 32a, 32b, 32c. Different levels of abnormality can be detected for 2 and 20-3.

  Next, the monitoring unit 4 will be described. As shown in FIG. 3, the monitoring unit 4 includes a first comparison / determination circuit 40 (first comparison / determination unit), a second comparison / determination circuit 42 (second comparison / determination unit), and a cutoff circuit 44.

  The first comparison / determination circuit 40 has the number of cells exceeding the first determination threshold for the voltages of the battery cells 20-1, 20-2, 20-3,. This is a circuit for calculating the ratio of the number of cells below the determination threshold to the total number of cells and determining whether the calculation result of the ratio exceeds a predetermined reference ratio. In this embodiment, when the ratio calculation result exceeds, for example, the reference ratio 55%, the determination result is output to the cutoff circuit 44. Note that the reference ratio is selected from a range that is acceptable for the assembled battery 2 as a whole even if the state of the predetermined unit cell is abnormal (for example, more than 50% and less than 100% depending on the characteristics of the secondary battery, etc. Can be set appropriately.

  The second comparison / determination circuit 42 is a circuit that determines whether there is a unit cell that exceeds the second determination threshold or a unit cell that exceeds the fourth determination threshold. In the present embodiment, the second comparison / determination circuit 42 causes the unit cell to exceed the second determination threshold (severe overcharge state) or the unit cell below the fourth determination threshold (severe overdischarge state). When it is determined that at least one exists, the determination result is output to the cutoff circuit 44.

  The interruption circuit 44 (wiring interruption means) is based on information indicating the states of the unit cells 20-1, 20-2, and 20-3 output from the first comparison determination circuit 40 and the second comparison determination circuit 42. This is a circuit for interrupting the circuit breakers 62a and 62b in the charging path 6 or the circuit breakers 72a and 72b in the discharging path 7.

  When the cutoff circuit 44 receives information indicating that the charging path 6 or the discharging path 7 should be blocked from the first comparison determination circuit 40, the cutoff circuit 44 outputs the information to the upper CPU 5 and is returned from the upper CPU 5. In response to the interruption permission signal for the charging path 6 or the discharging path 7, the circuit breakers 62 a and 62 b for the charging path 6 or the breakers 72 a and 72 b for the discharging path 7 are blocked. That is, the interruption of the charging path 6 or the discharging path 7 is allowed until a plurality of abnormal unit cells are generated.

  Further, when the interruption circuit 44 receives information indicating that the charging path 6 or the discharging path 7 should be interrupted from the second comparison determination circuit 42, the interruption circuit 44 outputs the information to the host CPU 5 without outputting the information. 6 circuit breakers 62a and 62b or circuit breakers 72a and 72b in the discharge path 7 are directly disconnected. That is, the charging path 6 or the discharging path 7 is blocked when at least one abnormal unit cell is detected.

  Next, the operation of the monitoring apparatus 1 configured as described above will be described with reference to FIGS. 3, 4, and 5. In this description of the operation, the operation will be described focusing on the operation of cutting off the charging path 6 or the discharging path 7 based on the voltage data of the unit cells 20-1, 20-2, 20-3. FIG. 4 shows an operation based on the voltage data of the unit cells 20-1, 20-2, 20-3 detected by the first voltage detection circuits 30a, 30b, 30c, and FIG. 5 shows the second voltage. An operation based on the voltage data of the unit cells 20-1, 20-2, and 20-3 detected by the detection circuits 32a, 32b, and 32c is shown.

  The monitoring of the assembled battery 2 by the monitoring device 1 is performed, for example, when the ignition of the electric vehicle is turned on or when the electric vehicle is traveling. The voltages of the unit cells 20-1, 20-2, 20-3 constituting the assembled battery 2 are detected by the first voltage detection circuits 30a, 30b, 30c and the second voltage detection circuits 32a, 32b, 32c. .

  As shown in FIGS. 3 and 4, the voltage data of each unit cell 20-1, 20-2, 20-3 is taken into the first threshold value setting unit 315 (first and second determination threshold values). Then, the presence / absence of a unit cell exceeding the first determination threshold value or the third determination threshold value is detected for each of the fetched voltage data (step S1).

  In the first comparison / determination circuit 40, regarding the voltages of the unit cells 20-1, 20-2, 20-3 constituting the assembled battery 2, the number of cells exceeding the first determination threshold or the third determination threshold is set. Calculation is performed for the ratio of the number of cells below the total number of cells (step S2).

  Whether the ratio of the number of cells exceeding the first determination threshold or the number of cells below the third determination threshold with respect to the calculation result of the ratio in the first comparison determination circuit 40 exceeds 55%. (Whether or not the reference ratio exceeds 55%) is determined (step S3).

  If the determination result in step S3 is YES, the assembled battery 2 is in a state where the charging path 6 or the discharging path 7 should be cut off, and the process proceeds to step S4.

  In step S <b> 4, when the cutoff circuit 44 receives information indicating that the charging path 6 or the discharging path 7 should be blocked from the first comparison determination circuit 40, the cutoff circuit 44 outputs the information to the host CPU 5. Then, the host CPU 5 returns a cutoff permission signal for the charging path 6 or the discharging path 7 to the cutoff circuit 44.

  On the other hand, if the determination result in step S3 is NO, step S1 to step S3 are performed until the ratio of unit cells exceeding the reference ratio of the first and third determination thresholds is 55% or more of the total number of cells. The loop is repeated.

  When the interruption circuit 44 receives the interruption permission signal for the charging path 6 or the discharging path 7 sent back from the host CPU 5, the interruption circuit 62a, 62b for the charging path 6 or the breakers 72a, 72b for the discharging path 7 are interrupted. That is, if the ratio of the number of cells exceeding the first determination threshold to the total number of cells exceeds 55%, the charging path 6 is blocked by the control of the upper CPU 5, and the ratio of the number of cells below the third determination threshold to the total number of cells. Exceeds 55%, the discharge path 7 is blocked by the control of the host CPU 5 (step S5). Thus, the interruption of the charging path 6 or the discharging path 7 is allowed until a plurality of abnormal unit cells occur.

  Next, an operation based on the voltage data of each unit cell 20-1, 20-2, 20-3 detected by the second voltage detection circuits 32a, 32b, 32c will be described. As shown in FIGS. 3 and 5, the voltage data of the unit cells 20-1, 20-2 and 20-3 is taken into the second threshold setting unit 340 (second and fourth determination thresholds). Then, the presence / absence of a unit cell exceeding the second determination threshold value or the fourth determination threshold value is detected for each acquired voltage data (step S10).

  Whether there is at least one unit cell in the second comparison determination circuit 42 that is above the second determination threshold (severe overcharge state) or below the fourth determination threshold (severe overdischarge state). It is determined whether or not (step S20).

  If the determination result in step S20 is YES, the interruption circuit 44 receives the information indicating that the charging path 6 or the discharging path 7 should be interrupted from the second comparison determination circuit 42. Without outputting to the host CPU 5, the circuit breakers 62a and 62b in the charging path 6 or the circuit breakers 72a and 72b in the discharging path 7 are directly disconnected. That is, when there is at least one unit cell exceeding the second determination threshold, the charging path 6 is shut off without being controlled by the host CPU 5, and when at least one unit cell lower than the fourth determination threshold is present, the discharge path 7 is shut off without being controlled by the host CPU 5 (step S30). As described above, the charging path 6 or the discharging path 7 is blocked when at least one abnormal unit cell is detected.

  On the other hand, if the determination result in step S20 is NO, the loop from step S10 to step S20 is repeated until a unit cell in a severe overcharge state or a severe overdischarge state is detected.

  As described above, according to the monitoring device 1 of the present embodiment, the charging path 6 or the discharging path 7 can be blocked until a plurality of abnormal unit cells are generated. To avoid doing as much as possible. Further, the first voltage detection circuits 30a, 30b, 30c and the second voltage detection circuits 32a, 32b, 32c, which are duplicated for the unit cells 20-1, 20-2, 20-3, have different levels. Anomalies in unit cells can be detected. Furthermore, power consumption can be suppressed as much as possible even if the number of unit cells connected in series increases, and the unit cells 20 in the voltage detection means can be compared with a case in which all voltage detection means are configured by a circuit including a microcomputer. −1, 20-2, 20-3... 20-n detection of abnormality and the certainty of determination are ensured.

  In the present embodiment, the voltage detection means 3 includes a first voltage detection circuit (first voltage detection means or third voltage detection means) 30a and a second voltage connected in parallel to a common unit cell. In the above description, the voltage detection circuit (second voltage detection means or fourth voltage detection means) 32a is described as an example. However, this is merely an example, and the present invention is not limited thereto. For example, when one voltage detection means and a threshold setting means are provided, a first voltage threshold is set inside, and when a plurality of unit cells exceeding the first voltage threshold are detected by the voltage detection means, the charging path 6 It may be a monitoring means for shutting off. Further, when at least one unit cell having the second voltage threshold and exceeding the second voltage threshold is detected by the voltage detection means, the charging path 6 may be cut off.

  Similarly, when one voltage detection means and a threshold setting means are provided, a third voltage threshold is set inside, and a plurality of unit cells below the third voltage threshold are detected by the voltage detection means, It may be monitoring means for blocking the discharge path 7. Further, when at least one unit cell having a fourth voltage threshold and lower than the fourth voltage threshold is detected by the voltage detection means, the discharge path 7 may be interrupted.

  In the present embodiment, the first threshold setting unit 315 stores a first determination threshold for detecting a slight overcharge and a third determination threshold for detecting a slight overdischarge. Although the example which stores the 2nd determination threshold value which detects heavy overcharge in the setting part 340, and the 4th determination threshold value which detects heavy overdischarge was demonstrated, this is only an illustration and is limited to this. It is not a thing. For example, a determination threshold value for detecting a slight overcharge is stored in the first threshold value setting unit 315, and a determination threshold value for detecting a heavy overcharge is stored in the third threshold value setting unit 340. An overcharge abnormality may be detected for 1, 20-2, and 20-3, and only the charging path 6 may be blocked. In addition, for example, a determination threshold value for detecting a slight overdischarge is stored in the first threshold value setting unit 315, and a determination threshold value for detecting a severe overdischarge is stored in the third threshold value setting unit 340. An overdischarge abnormality may be detected for 20-1, 20-2, and 20-3, and only the discharge path 7 may be blocked.

  Furthermore, the present invention includes a battery pack 2 having a charging path 6 and / or a discharging path 7 and electrically connecting unit cells 20-1, 20-2, 20-3,. The form of the battery pack provided with the monitoring device 1 described in the form can also be adopted.

DESCRIPTION OF SYMBOLS 1 Assembly battery monitoring apparatus 2 Assembly battery 3 Voltage detection means 4 Monitoring means 5 Host CPU
6 Charging path 7 Discharging path 20-1, 20-2, 20-3 Unit cell 30a, 30b, 30c First voltage detection circuit 32a, 32b, 32c Second voltage detection circuit 35a, 35b, 35c Redundant circuit 40 1 comparison determination circuit 42 second comparison determination circuit 44 interruption circuit 315 first threshold value setting unit 340 second threshold value setting unit

Claims (15)

A battery pack configured by connecting a plurality of unit cells composed of secondary batteries in series and having a charging path, and detecting the voltage of each unit cell constituting the battery pack to monitor the charge state of the cell A battery monitoring device,
Voltage detection means;
Threshold setting means;
Wiring cutoff means, a first voltage threshold is set by the threshold setting means,
The assembled battery monitoring device further comprising monitoring means, wherein the monitoring means shuts off the charging path when a plurality of unit cells exceeding the first voltage threshold are detected by the voltage detection means. The monitoring device further has a second voltage threshold,
2. The assembled battery monitoring device according to claim 1, wherein when at least one unit cell exceeding the second voltage threshold is detected by the voltage detection unit, the charging path is interrupted.   The monitoring device calculates a ratio of the number of cells exceeding the first voltage threshold to the total number of assembled battery cells, and shuts off the charging path when the calculation result exceeds a predetermined reference ratio. The monitoring apparatus of the assembled battery of Claim 1 or Claim 2.   The assembled battery monitoring device according to claim 3, wherein the reference ratio is a value selected from a range of more than 50% and less than 100%. The voltage detection means includes a first voltage detection means and a second voltage detection means connected in parallel to a common unit cell,
In the first voltage detection means, a first voltage threshold is set,
The assembled battery monitoring device according to any one of claims 2 to 4, wherein a second voltage threshold value is set in the second voltage detection means.   One of the first voltage detection means and the second voltage detection means is constituted by a circuit including a microcomputer, and the other voltage detection means is constituted by a circuit not including the microcomputer. Item 6. The assembled battery monitoring device according to Item 5. For a battery pack having a discharge path configured by connecting a plurality of unit cells each of which is a secondary battery, a set for detecting the voltage of each unit cell constituting the battery pack and monitoring the discharge state of the cell A battery monitoring device,
Voltage detection means;
Threshold setting means;
Wiring cutoff means, a third voltage threshold is set by the threshold setting means,
And further comprising monitoring means, the monitoring means comprising:
The assembled battery monitoring apparatus, wherein the discharge path is cut off when a plurality of unit cells lower than the third voltage threshold are detected by the voltage detection means. The monitoring device further has a fourth voltage threshold,
The assembled battery monitoring device according to claim 7, wherein the discharge path is interrupted when at least one unit cell that is lower than the fourth threshold is detected by the voltage detection unit.   The monitoring device calculates a ratio of the number of cells below the third voltage threshold to the total number of cells in the assembled battery, and shuts off the discharge path when the calculation result exceeds a predetermined reference ratio. The assembled battery monitoring device according to claim 7 or claim 8. The voltage detection means includes a third voltage detection means and a fourth voltage detection means connected in parallel to a common unit cell,
A third voltage threshold is set in the third voltage detection means,
The assembled battery monitoring device according to claim 8 or 9, wherein a fourth voltage threshold is set in the fourth voltage detection means.   One of the third voltage detection means and the fourth voltage detection means is constituted by a circuit including a microcomputer, and the other voltage detection means is constituted by a circuit not including the microcomputer. Item 15. The assembled battery monitoring device according to Item 10.   The assembled battery according to claim 10 or 11, wherein the third voltage detection means is the first voltage detection means, and the fourth voltage detection means is the second voltage detection means. Monitoring device.   The assembled battery monitoring device according to any one of claims 1 to 12, wherein the unit cell is a lithium ion battery.   The assembled battery monitoring device according to any one of claims 1 to 13, wherein the assembled battery is a power source for driving an electric vehicle or a hybrid vehicle. A plurality of unit cells composed of secondary batteries connected in series, the assembled battery having the charging path and / or the discharging path;
The battery pack provided with the monitoring apparatus of the assembled battery as described in any one of Claims 1-14.

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