Battery packs and their anomaly monitoring methods

Abstract

Even if the microcomputer in the charging circuit malfunctions, abnormal charging will not occur. The battery pack (100) includes: a current detection unit (4) for detecting the charging current to the secondary battery (1); a drive circuit (10) for driving the charging switch unit (2) based on the charging current detected by the current detection unit (4); a charging control unit (20) for controlling the operation of the charging switch unit (2) based on the drive circuit (10); a monitoring unit (30) for monitoring the operation of the charging control unit (20); and a determination unit (40) for indicating whether the operation of the charging switch unit (2) can be performed based on the charging control unit (20) and the monitoring unit (30). The charging control unit (20) is configured to generate a charging signal for charging the charging switch unit (2). The charging control unit (20) outputs a monitoring signal to the monitoring unit (30). The monitoring unit (30) monitors the monitoring signal and outputs a determination signal as a determination result of whether the monitoring signal is normal or abnormal. The determination unit (40) indicates whether charging can be performed by the charging switch unit (2) based on the charging signal from the charging control unit (20) and the determination signal from the monitoring unit (30).

Description

Technical Field

[0001] This invention relates to battery packs and methods for monitoring their anomalies. Background Technology

[0002] Secondary batteries are used as power sources for battery-powered devices such as mobile devices, electric bicycles, power tools, electric cleaners, and electric scooters. These secondary batteries are charged via battery packs, such as chargers. These battery packs widely utilize charging and discharging control devices equipped with microcomputers known as battery management systems. These battery management systems are configured to perform various controls, including protection actions, based on information such as the voltage, temperature, and current of the secondary batteries. Furthermore, the battery pack includes a charging circuit that can input voltage and current that convert commercial power to more suitable values ​​to charge the secondary batteries (e.g., Patent Documents 1 and 2).

[0003] Battery management systems (BMS) include microcomputers and charging FETs. However, if the microcomputer malfunctions, it cannot charge correctly, which can sometimes reduce safety. Therefore, methods have been considered, such as dual-computer operation for mutual checks, or charging via the other in case of one malfunction, so that charging can still proceed correctly even if the microcomputer malfunctions. However, these methods suffer from increased structural complexity and higher costs.

[0004] Furthermore, Patent Document 1 proposes a method in which a watchdog timer IC for monitoring microcomputer malfunctions is installed in the battery pack connected to the charger. The watchdog timer IC monitors the microcomputer's operating state based on watchdog pulses output from the microcomputer at regular intervals. Moreover, when an abnormal operation of the microcomputer is detected, a reset signal is output to the microcomputer and also to the charging enable / stop circuit, thereby forcibly stopping charging regardless of the content of the signal output from the microcomputer to the charging enable / stop circuit.

[0005] Here, the general reset signal generated by the watchdog timer IC, upon detecting a malfunction in the microcomputer, outputs a low level for a certain period to reset the microcomputer, and then switches the signal to a high level. Therefore, when this signal is used for both microcomputer reset and forced charging stop based on the charging enable / stop circuit, the forced charging stop is lifted before the microcomputer reset is complete and normal operation resumes, regardless of whether the battery pack is in an abnormal state.

[0006] Prior art literature

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent No. 5284672

[0009] Patent Document 2: Japanese Patent Application Publication No. 7-141066 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] One of the objectives of this invention is to provide a battery pack and its anomaly monitoring method, which prevents abnormal charging even if the microcomputer of the battery management system malfunctions, thereby improving reliability.

[0012] Methods for solving problems

[0013] One embodiment of the present invention relates to a battery pack comprising: a charging switch unit connected in series with a secondary battery and adjusting the charging current for charging the secondary battery; a current detection unit for detecting the charging current to the secondary battery; a drive circuit for driving the charging switch unit based on the charging current detected by the current detection unit; a charging control unit for controlling the operation of the charging switch unit in the drive circuit; a monitoring unit for monitoring the operation of the charging control unit; and a determination unit for indicating whether the operation of the charging switch unit can be performed based on the charging control unit and the monitoring unit. The charging control unit is configured to generate a charging signal for charging the charging switch unit, output a monitoring signal to the monitoring unit, monitor the monitoring signal, output a determination signal as a determination of whether the monitoring signal is normal or abnormal, and indicate whether the charging switch unit can be charged based on the charging signal from the charging control unit and the determination signal from the monitoring unit.

[0014] Furthermore, another aspect of the present invention relates to a secondary battery charging method that uses a battery pack to charge the secondary battery. The battery pack includes: a charging switch connected in series with the secondary battery; a current detection unit that detects the charging current to the secondary battery; a drive circuit that drives the charging switch based on the charging current detected by the current detection unit; a charging control unit that controls the operation of the charging switch in the drive circuit; a monitoring unit that monitors the operation of the charging control unit; and a determination unit that, based on the charging control unit and the monitoring unit, indicates whether the operation of the charging switch can be performed. The secondary battery charging method includes the following steps: the charging control unit outputs a monitoring signal to the monitoring unit; the monitoring unit monitors the monitoring signal and outputs a determination signal indicating whether the monitoring signal is normal or abnormal; and the determination unit, based on the charging signal from the charging control unit and the determination signal from the monitoring unit, indicates whether charging of the charging switch can be performed.

[0015] Invention Effects

[0016] According to one aspect of the present invention, a battery pack and its anomaly monitoring method determine whether charging can proceed based not only on the charging signal from the charging control unit but also on a determination signal from a monitoring unit that monitors the charging control unit. Therefore, even if an anomaly occurs in the charging control unit, and the charging control unit continues to output a charging signal, the charging switch can be reliably cut off via the determination signal from the monitoring unit. Furthermore, when the charging control unit is restarted, since a charging signal is output based on confirmation that no abnormal conditions have occurred, the reliability and safety of charging the battery pack are improved. Attached Figure Description

[0017] Figure 1 This is a block diagram illustrating the battery pack involved in the embodiment.

[0018] Figure 2 This is a table showing the on / off operation of the charging switch section.

[0019] Figure 3 This is a diagram showing an example of the watchdog pulse when the charging control unit is functioning normally.

[0020] Figures 4A-4B This is a diagram illustrating an example of a watchdog pulse when the charging control unit malfunctions.

[0021] Figure 5A This is a timing diagram showing the reset signal from the monitoring unit. Figure 5B This is a timing diagram showing the reset signal inside the charging control unit. Figure 5C This is a timing diagram showing the clock operation inside the charging control unit. Figure 5D This is a timing diagram showing the charging signals from the charging control unit. Figure 5E This is a timing diagram showing the operation of the charging switch section. Detailed Implementation

[0022] In addition to the structure described above, the battery pack of one embodiment of the present invention may also be configured as follows.

[0023] According to one embodiment of the present invention, a battery pack can be configured such that the monitoring unit outputs the determination signal to the charging control unit, and the charging control unit resets itself in the event of an abnormal determination signal. Based on this configuration, if the monitoring unit detects an abnormality in the charging control unit, it can reset the charging control unit to eliminate the abnormal state.

[0024] Furthermore, in other embodiments of the present invention, the battery pack can be configured such that, after the charging control unit is reset according to the determination signal, it performs fault diagnosis while stably outputting the monitoring signal, and outputs the charging signal if no abnormality is detected. Examples of fault diagnosis include confirming a short-circuit fault in the charging FET and confirming an anomaly in the ROM containing the program inside the microcomputer. According to the above structure, since fault diagnosis is performed in a stable state after the charging control unit is reset, the charging signal is output based on the confirmation that no various abnormalities of the battery pack have occurred, thus resulting in a more reliable fault diagnosis.

[0025] Furthermore, in other embodiments of the present invention, the battery pack can be configured such that the determination signal is a reset signal that is high under normal conditions and low under abnormal conditions, and the charging control unit resets itself when the reset signal is low. According to the above structure, the determination signal of the monitoring unit can be shared as the reset signal of the charging control unit, which facilitates recovery from abnormal situations in the charging control unit.

[0026] Furthermore, in other embodiments of the battery pack according to the present invention, the monitoring unit is a watchdog timer IC, and the monitoring signal is a watchdog pulse. Based on the above structure, a watchdog timer can be used to determine abnormalities in the charging control unit.

[0027] Furthermore, in other embodiments of the present invention, the battery pack can be configured such that the determination unit permits charging of the charging switch unit only when the charging signal of the charging control unit is high and the reset signal of the monitoring unit is high. According to the above structure, by using not only the charging signal of the charging control unit but also the determination signal from the monitoring unit of other components for determination, it is possible to respond to abnormalities in the power receiving control unit, thereby further improving safety and reliability.

[0028] Furthermore, in other embodiments of the present invention, the determination unit is a NAND circuit.

[0029] Furthermore, the battery pack according to other embodiments of the present invention also includes: a switching unit connected between the output side of the determination unit and the charging switch unit, which forcibly cuts off the charging operation of the charging switch unit when the determination unit prohibits the charging of the charging switch unit.

[0030] Furthermore, in other embodiments of the present invention, the battery pack may be configured to further include: a discharge switch unit connected in series with a secondary battery, adjusting the discharge current for discharging the secondary battery; a drive circuit driving the discharge switch unit based on the discharge current detected by the current detection unit; a charging control unit configured to output a discharge signal to the discharge switch unit; and a determination unit indicating whether the discharge switch unit can discharge based on a charging signal from the charging control unit and a determination signal from the monitoring unit. According to this structure, the battery pack monitors the charging control unit not only during charging of the secondary battery but also during discharging, thereby preventing abnormal discharge currents in abnormal situations and improving safety during discharge.

[0031] Furthermore, in other embodiments of the charging method according to the present invention, the step of the monitoring unit outputting the determination signal includes the step of outputting the determination signal to the charging control unit. The charging method for the secondary battery also includes the step of the charging control unit resetting the charging control unit in the event of an abnormal determination signal. Thus, if the monitoring unit detects an abnormality in the charging control unit, it can reset the charging control unit to eliminate the abnormal state.

[0032] Furthermore, the charging method according to other embodiments of the present invention further includes the following steps: immediately following a reset of the charging control unit, the charging control unit performs fault diagnosis while being able to stably output the monitoring signal, and outputs the charging signal if no abnormality is detected. Therefore, since the charging signal is output based on the confirmation that no abnormalities have occurred in the battery pack, more reliable fault diagnosis is expected.

[0033] Hereinafter, embodiments of the present invention will be described based on the accompanying drawings. However, the embodiments shown below exemplify a battery pack used to embody the technical concept of the present invention, and the present invention does not specifically designate the battery pack as described below. Furthermore, this specification does not specifically designate the components shown in the claims as components of the embodiments. In particular, the dimensions, materials, shapes, and relative arrangements of the structural components described in the embodiments are not intended to limit the scope of the present invention unless specifically stated otherwise, and are merely illustrative examples. In addition, the size and positional relationships of the components shown in the accompanying drawings are sometimes exaggerated for clarity of explanation. Furthermore, in the following description, detailed descriptions of the same names and reference numerals, which denote the same or homogeneous components, are appropriately omitted. Furthermore, the elements constituting the present invention can be configured such that multiple elements are constituted by the same component, and one component can serve as multiple elements; conversely, multiple components can share the function of one component.

[0034] The battery pack of this invention is primarily used as a power source. For example, it can be used as a power source for electric devices driven by electric motors, such as electric cleaners, power tools, electric-assisted bicycles, electric motorcycles, electric wheelchairs, electric tricycles, and electric trolleys. However, this invention does not specifically specify the application of the battery pack; it can also be used as a power source for various electrical devices used indoors and outdoors, such as wireless devices and lighting fixtures, as well as for powering mobile units and providing auxiliary power.

[0035] [Implementation Method 1]

[0036] The battery pack 100 according to Embodiment 1 of the present invention is shown in Figure 1 The battery pack 100 shown in the figure includes: a secondary battery 1; a charging switch 2, a discharging switch 3, a current detection unit 4, and an external terminal 5 connected in series with the secondary battery 1; a temperature detection unit 6; a voltage detection unit 7; a drive circuit 10; a charging control unit 20; a monitoring unit 30; a determination unit 40; and a switching unit 50.

[0037] The secondary battery 1 can appropriately utilize rechargeable batteries, such as lithium-ion batteries. However, it can also utilize secondary batteries other than lithium-ion batteries, such as nickel-metal hydride batteries and nickel-cadmium batteries. By combining the secondary battery 1 with multiple batteries in series or parallel, high capacity and high output can be achieved. In addition to using cylindrical batteries with a cylindrical shape, square batteries with a rectangular shape and flat batteries can also be used. Furthermore, the secondary battery 1 does not necessarily have to be included in the battery pack 100. For example, the secondary battery 1 can be detachable or replaceable relative to the battery pack 100.

[0038] External terminal 5 is a connection terminal for receiving power from an external source to charge the secondary battery 1. This external terminal 5 is connected, for example, to a charger. In this case, the secondary battery 1 is charged via the charging switch 2 after the voltage and current, converted from commercial power, are input through the charger connected to external terminal 5. Furthermore, when the battery pack 100 is built into a driven device powered by the secondary battery 1, it is connected to the power supply terminal inside the driven device. In this case, the conversion of voltage and current values ​​can be appropriately omitted. Examples of battery-powered devices powered by the secondary battery 1 include mobile devices, electric bicycles, power tools, electric cleaners, and electric scooters.

[0039] The charging switch unit 2 is connected in series with the secondary battery 1 to adjust the charging current for charging the secondary battery 1. The charging switch unit 2 can be, for example, a charging FET.

[0040] Similarly, the discharge switch 3 is also connected in series with the secondary battery 1 to adjust the discharge current of the secondary battery 1. The discharge switch 3 can be, for example, a discharge FET.

[0041] The current detection unit 4 is connected in series with the secondary battery 1 to detect the charging and discharging current of the secondary battery 1. The current detection unit 4 can appropriately utilize a current detection resistor.

[0042] The voltage detection unit 7 detects the voltage of the secondary battery 1. When the secondary battery 1 is a series connection of a large number of secondary batteries, the voltage detection unit 7 can also be configured to detect the voltage of each secondary battery.

[0043] Temperature detection unit 6 detects the temperature of secondary battery 1. This temperature detection unit 6 can utilize a thermistor or similar device. Furthermore, when a large number of secondary batteries are connected, the temperature detection unit 6 can also detect the temperature of each individual secondary battery.

[0044] (Driver Circuit 10)

[0045] The outputs of the current detection unit 4, temperature detection unit 6, and voltage detection unit 7 are connected to the drive circuit 10. The drive circuit 10 acquires the charging and discharging current detected by the current detection unit 4, the temperature detected by the temperature detection unit 6, and the voltage of each battery in the series-connected secondary battery detected by the voltage detection unit 7. The drive circuit 10 includes the following: a charging control circuit 12 that controls the operation of the charging switch unit 2; a discharging control circuit 13 that controls the operation of the discharging switch unit 3; an AD converter 14 that performs A / D conversion on the output of the current detection unit 4, the voltage of the voltage detection unit 7, and the temperature of the temperature detection unit 6; and a low-voltage power supply circuit 15 that supplies power to the charging control unit 20 and the monitoring unit 30. Furthermore, after transmitting the detected charging and discharging current, temperature, and battery voltage to the charging control unit 20 via communication or the like, the drive circuit 10 controls the switching on / off of the charging switch unit 2 and the discharging switch unit 3 according to the instructions of the charging control unit 20.

[0046] (Charging Control Unit 20)

[0047] The charging control unit 20 controls the operation of the charging switch unit 2 in the drive circuit 10. Furthermore, the charging control unit 20 outputs a charging signal to charge the charging switch unit 2. The charging signal is either high-level or low-level, such as... Figure 2 As shown in the table, the decision to enable charging of the charging switch 2 is made by combining the signal with the control signal. This charging control unit 20 can be appropriately powered by a programmable microcomputer or similar device.

[0048] Furthermore, the charging control unit 20 outputs a monitoring signal to the monitoring unit 30. The monitoring signal is, for example, a watchdog pulse. When the microcomputer of the charging control unit 20 is functioning normally, the watchdog pulse... Figure 3 The output is performed for a given period T. On the other hand, in case of microcomputer malfunctions, such as... Figure 4A As shown, the period becomes longer (T+α), or as... Figure 4B As shown, the period becomes shorter (T-β).

[0049] (Surveillance Department 30)

[0050] The monitoring unit 30 monitors the monitoring signal, determines whether the monitoring signal is normal or abnormal, and outputs the determination result as a determination signal. The monitoring unit 30 is, for example, a watchdog timer IC that monitors watchdog pulses, and determines whether... Figure 3 The signal shown is a normal watchdog pulse, or... Figure 4A , Figure 4B The abnormal watchdog pulse shown is used to detect an anomaly in the charging control unit 20. Thus, the watchdog timer IC can be used to determine any anomalies in the charging control unit 20.

[0051] (Judgment Section 40)

[0052] The determination unit 40, based on the outputs of the charging control unit 20 and the monitoring unit 30, indicates whether the charging switch unit 2 can be operated. This determination unit 40 can appropriately utilize NAND circuitry. Figure 1 The determination circuit, composed of NAND flash memory, receives the charging signal from the charging control unit 20 and the determination signal from the monitoring unit 30. When any input is low, the determination circuit outputs a high level, forcibly turning the charging switch unit 2 off.

[0053] (Reset signal)

[0054] The monitoring unit 30 may also output a determination signal to the charging control unit 20. In this case, the determination signal can be set as a reset signal to reset the charging control unit 20. The charging control unit 20 resets itself if the determination signal is abnormal. Therefore, if the monitoring unit 30 detects an abnormality in the charging control unit 20, it can reset the charging control unit 20 to eliminate the abnormal state. Furthermore, by using the determination signal of the monitoring unit 30 as the reset signal of the charging control unit 20, it becomes easier to recover from abnormalities in the charging control unit 20.

[0055] When the determination signal is set as a reset signal, it can be configured to be high under normal conditions and low under abnormal conditions. In this case, the charging control unit 20 resets itself when the reset signal is low.

[0056] Furthermore, such as Figure 2As shown, the determination unit 40 can be configured to allow charging of the charging switch unit 2 only when the charging signal of the charging control unit 20 is high and the reset signal of the monitoring unit 30 is high. Therefore, by using not only the charging signal of the charging control unit 20 but also the determination signal from the monitoring unit 30 of other components for determination, it is possible to respond to abnormalities in the charging control unit, thereby further improving safety and reliability.

[0057] Furthermore, after being reset by the judgment signal, the charging control unit 20 performs fault diagnosis while maintaining a stable output of the monitoring signal. If no abnormality is detected, it outputs a charging signal. This method, which outputs a charging signal only after confirming that no abnormalities have occurred in the battery pack, is expected to provide more reliable fault diagnosis. Examples of fault diagnoses performed by the charging control unit 20 include confirming short-circuit faults in the charging switch unit 2 and checking for abnormalities in the ROM storing the program within the microcomputer.

[0058] (Switching unit 50)

[0059] The switching unit 50 is connected between the output side of the determination unit 40 and the charging switch unit 2. When the determination unit 40 prohibits the charging of the charging switch unit 2, the switching unit 50 forcibly cuts off the charging operation of the charging switch unit 2.

[0060] Figure 1 The switching unit 50 receives inputs as the voltage Vbat of the secondary battery 1 and the output of the drive circuit 10, and switches between them based on the determination output from the determination unit 40. Figure 1 In this example, when the determination output of the determination unit 40 is low, the switching unit 50 outputs the drive circuit 10 as is. On the other hand, when the determination output of the determination unit 40 is high, it outputs a Vbat voltage. This Vbat voltage becomes a forced disconnect signal for the charging FET, thereby forcibly disconnecting the charging switch unit 2. In this way, the charging operation of the charging FET can be disconnected in hardware, and the charging path can be safely cut off until the battery pack 100 resumes normal operation, as described later.

[0061] (Uncontrolled monitoring function)

[0062] exist Figure 1In the battery pack 100, abnormalities in the charging control unit 20 can be detected to ensure charging safety. In conventional battery packs, if the program of the microcomputer constituting the charging control unit 20 malfunctions, there is a concern that charging cannot be stopped even if the charging voltage increases. To prevent this, it has been considered to install another microcomputer for duplication, but this method increases structural complexity and cost. Therefore, in this embodiment, by adding a cheaper and simpler monitoring unit 30, charging can be reliably stopped when an abnormality occurs in the charging control unit 20. Furthermore, in other conventional battery packs, after the microcomputer is reset, before the microcomputer starts normally and begins appropriate control and protection actions, the reset signal of the watchdog timer IC switches from a low level to a high level, thereby releasing the forced stop of the charging permission / stop circuit. There is a concern that charging may resume regardless of whether an abnormality occurs. However, by using the NAND circuit output (determination unit) of the determination signal and the charging signal, the operation of the battery pack can begin only after confirming that the operation of the charging control unit is stable and no abnormalities have occurred.

[0063] based on Figures 5A-5E A timing diagram is used to illustrate a specific step using an example. For example... Figure 5C As shown, the microcomputer of the charging control unit 20 operates according to a given clock generated internally. Here, the charging control unit 20 outputs a monitoring signal to the monitoring unit 30. As described above, the monitoring signal can be a watchdog pulse. When the microcomputer of the charging control unit 20 is operating normally, the watchdog pulse... Figure 3 The output is shown for a given period T. On the other hand, in the event of a microcomputer malfunction, for example, ... Figure 4A As shown, the period becomes longer (T+α), or as... Figure 4B As shown, the time is shortened (T-β). The monitoring unit 30 is a watchdog timer IC (WDTIC) that monitors the watchdog pulse, which serves as the monitoring signal. The WDTIC determines whether the monitoring signal is normal or abnormal and outputs the determination result as a determination signal. That is, it determines whether the signal is normal or abnormal. Figure 3 The signal shown is a normal watchdog pulse, or... Figure 4A , Figure 4B The abnormal watchdog pulse is shown. Then, the determination unit 40 indicates whether charging can be performed by the charging switch unit 2 based on the charging signal from the charging control unit 20 and the determination signal from the monitoring unit 30.

[0064] Now, as Figure 5AAs shown, the monitoring unit 30 (WDTIC) detects a malfunction in the program of the microcomputer, i.e., the charging control unit 20, and outputs a reset signal. That is, the reset signal, which serves as the determination signal, changes from a high level during normal operation to a low level. Upon receiving this change, the charging control unit 20 resets the microcomputer according to the reset signal, i.e., restarts it. Here, as... Figure 5B As shown, after a slight delay, the reset signal changes from a high level to a low level. Therefore, as... Figure 5C As shown, the clock signal of the microcomputer, which is periodically generated during normal operation, disappears. Similarly, the charging signal emitted by the microcomputer switches from a high level (charging enable) to a low level (charging disable) during normal operation. On the other hand, the charging FET, which serves as the charging switch unit 2, receives... Figure 5A The change of the reset signal from high level to low level, such as Figure 2 The second line indicates that charging is disabled, i.e., disconnected. Previously, this would have meant a failure to receive the charging signal from the microcomputer. Figure 5D Charging is prohibited, but charging is immediately stopped upon receiving the judgment result from the monitoring unit 30 without waiting for the charging signal to fail, which can further speed up the response and improve safety.

[0065] Then, after a given period, the reset is released, as follows: Figure 5A As shown, the reset signal recovers from a low level during the abnormal event to a high level during normal operation. On the other hand, the reset microcomputer restarts after a given time, as... Figure 5B As shown, the reset signal inside the microcomputer changes from a low level during the abnormal event back to a high level during normal operation. Similarly, as... Figure 5C As shown, the clock operation inside the microcomputer is also restarted. On the other hand, before restarting the charging signal from the microcomputer, a fault diagnosis is performed during the oscillation accuracy stabilization period. As described above, short-circuit fault determination of the charging FET and ROM checks inside the microcomputer are performed. If no fault is found, then... Figure 5D As shown, the charging signal changes from a low level during an abnormal event to a high level during normal operation. Upon receiving this change, due to... Figure 2 The first row shows the charging permission signal ( Figure 5D ) and decision signal ( Figure 5A All of these become high level, and the NAND circuit's determination unit 40 switches the determination output from the high level during an abnormal situation to the low level during normal operation. Figure 5EAs shown, the charging FET is turned on, and charging begins. Thus, if the microcomputer's operation is stable and fault-free after a reset, charging of the secondary battery 1 is restarted. Furthermore, in conventional structures without the monitoring unit 30 and the determination unit 40, charging is immediately restarted upon microcomputer restart, thus failing to guarantee safety in case of a fault. However, in the battery pack 100 of the secondary battery 1 according to this embodiment, as described above, the charging FET is turned on only after the microcomputer's operation is stable and a fault diagnosis has been obtained, thereby further ensuring safety.

[0066] In this way, by determining whether charging can proceed not only based on the charging signal from the charging control unit 20, but also based on the judgment signal from the monitoring unit 30 that monitors the charging control unit 20, even in the event of an anomaly in the charging control unit 20, the charging switch 2 can be reliably shut off via the judgment signal from the monitoring unit 30, even if the charging control unit 20 is continuously outputting a charging signal. This improves the reliability and safety of charging the secondary battery 1. Furthermore, in the event of a program malfunction within the microcomputer, the charging path can be reliably cut off until the power supply is restarted.

[0067] In particular, safety is ensured from the time the watchdog timer IC is reset until the microcomputer stabilizes. Furthermore, safety is further enhanced by diagnosing any faults within the battery pack 100 before restarting operation. Conversely, in conventional battery packs, the charging path is disconnected simultaneously with the reset, thus anticipating potential charging problems should a fault exist. In contrast, by also considering safety after the microcomputer is reset, the battery pack can be used more safely.

[0068] Furthermore, in the above examples, the method for controlling the operation of the charging switch unit 2 during the charging and discharging of the secondary battery 1 has been described. However, the present invention is not limited to a structure that monitors during charging; it can also be configured to monitor both the charging and discharging of the secondary battery. In particular, during charging, safety measures are more required in case of an abnormality in the secondary battery 1 compared to during discharging, so the abnormality monitoring function of the secondary battery of the present invention can be appropriately utilized. In addition, in a battery pack that monitors the charging and discharging of the secondary battery, a charge-discharge control unit can be used instead of a charging control unit. Of course, the charging control unit can also have the function of controlling the discharge current, regardless of its name.

[0069] Industrial availability

[0070] The battery pack and its anomaly monitoring method disclosed in this invention can be appropriately applied to battery packs for driving power tools, electric bicycles, electric motorcycles, electric tricycles, electric wheelchairs, electric trolleys, electric cleaners, electric blowers, etc., as well as battery management systems assembled in these devices, and chargers prepared as other components. Furthermore, it can also be used as a power source for electrical devices other than those driven by electric motors, such as wireless devices, lighting fixtures, and various electrical devices used indoors and outdoors, as well as as a power source for mobile units and as an auxiliary power source.

[0071] Explanation of reference numerals in the attached figures

[0072] 100: Battery pack

[0073] 1: Secondary battery

[0074] 2: Charging switch section

[0075] 3: Discharge switch section

[0076] 4: Current Detection Unit

[0077] 5: External terminal

[0078] 6: Temperature Detection Department

[0079] 7: Voltage Detection Section

[0080] 10: Drive circuit

[0081] 12: Charging control circuit

[0082] 13: Discharge control circuit

[0083] 14: AD Conversion Section

[0084] 15: Power supply circuit

[0085] 20: Charging Control Department

[0086] 30: Surveillance Department

[0087] 40: Judgment Department

[0088] 50: Switching Unit

Claims

1. A battery pack capable of charging a secondary battery, comprising: The charging switch is connected in series with the secondary battery to adjust the charging current for charging the secondary battery. The current detection unit detects the charging current to the secondary battery; The driving circuit drives the charging switch unit based on the charging current detected by the current detection unit; The charging control unit controls the operation of the charging switch unit of the drive circuit; The monitoring unit monitors the operation of the charging control unit; The determination unit, based on the charging control unit and the monitoring unit, indicates whether the charging switch unit can be operated. as well as A switching unit, connected between the output side of the determination unit and the charging switch unit, receives the voltage of the secondary battery and the output of the drive circuit as input, and switches between them based on the determination output from the determination unit. The charging control unit is configured to generate a charging signal that controls the charging switch unit to charge the secondary battery. The charging control unit outputs a monitoring signal to the monitoring unit. The monitoring unit monitors the monitoring signal, outputs the normal or abnormal determination result of the monitoring signal as a determination signal, and outputs the determination signal to the charging control unit. The charging control unit is reset when the determination signal is abnormal. After the determination signal switches from abnormal to normal, and the monitoring signal is stably output, it performs fault diagnosis, including checking for short circuit faults in the charging switch unit. If no abnormality is detected, it outputs the charging signal. The determination unit determines whether the secondary battery can be charged by the operation control of the charging switch unit based on both the charging signal from the charging control unit and the determination signal from the monitoring unit. The charging switch is controlled to prohibit charging of the secondary battery based on a determination signal from the monitoring unit indicating an anomaly, and is also controlled to start charging of the secondary battery based on a charging signal from the charging control unit. When the determination unit prohibits the charging of the charging switch unit, the switching unit forcibly cuts off the charging operation of the secondary battery by outputting the voltage of the secondary battery to the charging switch unit.

2. The battery pack according to claim 1, wherein, The determination signal is a reset signal that is high under normal conditions and low under abnormal conditions. The charging control unit resets itself when the reset signal is low.

3. The battery pack according to claim 2, wherein, The monitoring unit is a watchdog timer IC. The monitoring signal is a watchdog pulse.

4. The battery pack according to claim 3, wherein, The determination unit permits charging of the charging switch unit only when the charging signal of the charging control unit is high and the reset signal of the monitoring unit is high.

5. The battery pack according to any one of claims 1 to 4, wherein, The determination unit is a NAND circuit.

6. The battery pack according to any one of claims 1 to 4, wherein, The battery pack also includes a discharge switch unit connected in series with the secondary battery to adjust the discharge current of the secondary battery. The driving circuit drives the discharge switch based on the discharge current detected by the current detection unit. Furthermore, the charging control unit is configured to output a discharge signal that causes the discharge switch unit to discharge to the discharge switch unit. The determination unit, based on the charging signal from the charging control unit and the determination signal from the monitoring unit, indicates whether the secondary battery can be discharged by controlling the operation of the discharge switch unit.

7. The battery pack according to any one of claims 1 to 4, wherein, The battery pack also features: A voltage detection unit detects the voltage of the secondary battery; and The temperature detection unit detects the temperature of the secondary battery. The drive circuit outputs the charging current detected by the current detection unit, the voltage detected by the voltage detection unit, and the battery temperature detected by the temperature detection unit to the charging control unit to drive the charging switch unit.

8. A method for monitoring abnormalities in a battery pack. The battery pack includes: The charging switch is connected in series with the secondary battery; The current detection unit detects the charging current to the secondary battery; The driving circuit drives the charging switch unit based on the charging current detected by the current detection unit; The charging control unit controls the operation of the charging switch unit of the drive circuit; The monitoring unit monitors the operation of the charging control unit; The determination unit, based on the charging control unit and the monitoring unit, indicates whether the charging switch unit can be operated. as well as A switching unit, connected between the output side of the determination unit and the charging switch unit, receives the voltage of the secondary battery and the output of the drive circuit as input, and switches between them based on the determination output from the determination unit. The abnormal monitoring method for the battery pack includes the following steps: The charging control unit outputs a monitoring signal to the monitoring unit; The monitoring unit monitors the monitoring signal, outputs the normal or abnormal determination result of the monitoring signal as a determination signal, and outputs the determination signal to the charging control unit. The charging control unit is reset when the determination signal is abnormal. After the determination signal switches from abnormal to normal, it performs fault diagnosis, including checking whether there is a short circuit fault in the charging switch unit, while being able to stably output the monitoring signal. If no abnormality is detected, it outputs a charging signal. The determination unit determines whether the secondary battery can be charged by the operation control of the charging switch unit based on both the charging signal from the charging control unit and the determination signal from the monitoring unit. The charging switch is controlled to prohibit charging of the secondary battery based on the determination signal of the abnormality determination result from the monitoring unit, and is controlled to start charging of the secondary battery based on the charging signal from the charging control unit. as well as When the determination unit prohibits the charging of the charging switch unit, the switching unit forcibly cuts off the charging operation of the secondary battery by outputting the voltage of the secondary battery to the charging switch unit.

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