JP3514103B2 - Battery pack failure diagnosis device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery pack, and more particularly to a battery pack failure diagnosis device .

[0002]

2. Description of the Related Art In recent years, the market for secondary batteries has been expanding rapidly, and among them, non-aqueous secondary batteries, such as lithium-ion secondary batteries, are batteries for portable electronic equipment such as laptop computers and mobile phones. Became widely used as.

A lithium ion secondary battery, which is used as a battery pack by being constructed as a single battery or an assembled battery, is deteriorated in safety and deteriorated in quality due to overcharging and overdischarging, so that safety and reliability are maintained. Therefore, a control circuit for preventing overcharge and overdischarge is generally mounted on a BMU (battery management unit) to manage the battery voltage and the like.

A conventional BMU has an overcharge protection function, which detects a battery voltage and a battery current, and turns off the MOSFET provided in the charging path when an overvoltage or an overcurrent is detected. Is to forcibly stop charging. When it is detected that the battery voltage and the battery current have returned to the normal values, the MOSFET is turned off and charging is started again.

[0005]

However, in the above-mentioned conventional configuration, even if the cause of the overvoltage or the overcurrent is not removed, when the battery voltage decreases, the FET
Is turned on and charging is repeated. Also MOSFET
Is a component that is liable to cause junction breakdown due to temporary heat generation, etc., and if overcharge protection does not work because the defective MOSFET does not work, etc., there is a problem that charging can be continued without being stopped. Was.

When the BMU shuts down, it has no means for recording the fact that the BMU shuts down. Therefore, it is impossible to know whether the battery pack is abnormal or not. Even if the battery pack is abnormal and charging is not appropriate, it is charged again. Had the problem of being started.

The present invention solves such a conventional problem. In addition to the conventional overcharge protection, the FET failure diagnosis, the overcharge control circuit diagnosis, and the shutdown function diagnosis are performed.
An object of the present invention is to provide a BMU having a function of disconnecting and retaining failure information and not performing recharging.

[0008]

In order to achieve the above object, the battery pack failure diagnosis apparatus of the present invention is provided with an FE during charging.
A self-diagnosis means for performing FET failure diagnosis by forcibly turning off T and diagnosing whether or not the charging current becomes less than a specified value, and a non-volatile information holding means for holding this information. It is equipped with.

With this configuration, the safety of the battery pack can be maintained and the failure information is retained even if the MOSFET fails due to a process defect or thermal breakdown .
Battery pack that has detected an abnormality by recharging.
It can be lost.

Further, the battery pack failure diagnosis device of the present invention is
Self means Toko charging current during overcharge detection performs a diagnosis of the overcharge control circuit by diagnosing whether to stop
The non-volatile information holding means for holding the diagnostic information of 1 .

[0011] With this arrangement, since when there is an abnormality in the overcharge control circuit can detect it, fault information held by the terms of capable of maintaining the safety of the battery pack holds fault information It is possible to prevent recharging of the battery pack in which the abnormality is detected.

Further, the battery pack failure diagnosis device of the present invention is
Holds this diagnostic information and self-diagnostic means for diagnosing whether the detected value of the battery voltage is higher than the BMU shutdown voltage
The information holding means is provided.

With this configuration, the shutdown function is different.
When there is a normal condition, it can be detected, so the safety of the battery pack can be maintained, and by holding the failure information, the stored failure information can be read, and the battery pack that has detected an abnormality can be re-read. You can turn off charging.

Further , the battery pack failure diagnosis device is a FET
Fault diagnosis function, overcharge control circuit diagnosis function, voltage detection
It is also possible to have a configuration having a self-diagnosis means having both the output and the shutdown circuit diagnostic function .

With this configuration, it is possible to provide a highly reliable battery pack failure diagnosis device at a lower cost.

Such a battery pack failure diagnosing device is provided with F
A fault diagnosis function of ET, the overcharge control circuit diagnostics, shea
The diagnostic function of the shutdown function and the information holding means can be housed in the same IC package.

By packaging as an IC in one package, it is possible to reduce the scale and cost of the battery pack failure diagnosis device. Needless to say, this also makes it possible to reduce the scale and cost of the battery pack itself.

An abnormality in the battery pack may lead to a secondary disaster such as damage to an electronic device in which the battery pack is incorporated. Therefore, it is important to take thorough safety measures for the battery pack to ensure the safety and reliability of the electronic device. It will also increase.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a battery pack showing a configuration example in an embodiment of the present invention. The battery pack shown in the figure includes a BMU 1 (battery management unit, battery management device) including the battery pack failure diagnosis device of the present invention and other control devices, and a secondary battery 2 configured as a single or assembled battery. It is composed of a positive electrode terminal 3 and a negative electrode terminal 4 connected to an electronic device, and an information terminal 5 for outputting information. In the present embodiment, a lithium ion secondary battery will be described as an example of the secondary battery 2, but the battery system of the secondary battery 2 is not limited, and a nickel-hydrogen storage battery, a lithium polymer secondary battery, or the like may be used. The present invention can be appropriately modified and applied even when the type of battery is used.

The battery pack failure diagnosing device of the present invention incorporated in the BMU 1 has a current detection resistor 10, a current detection means 11, a self-diagnosis means 12, a voltage detection means 13, a communication means 14, an FET control section 15, and charging. It is comprised by FET16 for discharge and FET17 for discharge.

In the present embodiment, the current detection resistor 10, the charging FET 16 and the discharging FET 17 are arranged on the negative electrode side, but even if they are arranged on the positive electrode side, they have substantially the same functions.

The operation of each component will be described below. In the present embodiment, the current detection resistor 10 arranged on the negative electrode side detects the charging / discharging current flowing in the secondary battery 2.
The current detection means 11 always receives the signal from the current detection resistor 10, and outputs the signal of the charging / discharging current flowing through the secondary battery 2 to the self-diagnosis means 12 as appropriate. The signal output from the current detection means 11 to the self-diagnosis means 12 may be always performed, or may be performed every several seconds, for example.

The voltage detecting means 13 detects the voltage of the secondary battery 2 and outputs a signal to the self-diagnosing means 12 as appropriate. At this time, the voltage signal output to the self-diagnosis means 12 is
If the secondary battery 2 is a single battery, there is no problem because it only outputs the voltage of the single battery as a voltage signal.
When the secondary battery 2 is an assembled battery, the voltage detecting means 13
May detect the voltage for each unit cell and output the voltage signal for each unit cell as it is, or may output the sum of some or all unit cells. Alternatively, the sum of the battery voltages of the assembled battery may be simply detected and the voltage signal may be output.
When the detection is performed for each unit cell, it is possible to detect and eliminate the variation, which is preferable, but it goes without saying that a preferable method may be selected in consideration of cost and the like.

The self-diagnosis means 12 receives a signal input from the current detection means 11 and the voltage detection means 13 to detect an overvoltage,
Diagnosis is made by comparing whether it is an overcurrent with a reference value.

In the present embodiment, the BMU 1 is integrated into an IC. However, if the IC is not integrated, in order to perform this function of the self-diagnosis means 12, the output of the comparison result by the comparator is simply transmitted to the communication means 14 and It may be configured to output to the FET control unit 15.

If the self-diagnosis means 12 does not detect overvoltage or overcurrent, the communication means 14 outputs a signal indicating that the battery pack is normal, and the FE
The T control unit 15 outputs a signal for holding the charge / discharge FETs 16 and 17 on.

In the diagnosis result of the self-diagnosis means 12, if an overvoltage is detected, a signal indicating that the battery pack is overvoltage is output to the communication means 14, and the FET control section 15 is charged if the battery is being charged. Turning off the FET 16 for
If discharging, a signal for turning off the discharging FET 17 is output.

If an overcurrent is detected in the diagnosis result of the self-diagnosis means 12, a signal indicating that the battery pack is overcurrent is output to the communication means 14, and the FET is also used.
A signal for turning off the charge / discharge FETs 16 and 17 is output to the control unit 15.

In the BMU 1 which performs the safety control as described above, the FET is responsible for turning off the charge and discharge, and when the FET is out of order, the battery pack and the electronic device in which the FET is mounted are used. The equipment may be damaged.

In order to prevent this, the FET failure diagnosis as shown in the flowchart of FIG. 2 is performed. First, during charging of the secondary battery 2, a signal is output from the self-diagnosis means to forcibly turn off the charging FET 16. As a result, during normal operation, almost no charging current flows through the charging path.
For example, 100 mA can be used as this reference value. When the charging FET 16 is abnormal, the charging current detected by the current detecting means 11 does not fall below 100 mA. If, for example, 4 seconds elapses in this state, the charging F
The ET 16 diagnoses that there is an abnormality, and the self-diagnosis means 12 outputs a signal indicating that the battery pack is abnormal, a signal for stopping charging, or both signals to the electronic device through the communication means 14.

Further, the overcharge control circuit is diagnosed when overcharge is detected as shown in the flowchart of FIG. First, when an overcurrent is detected by the current detection unit 11 during charging / discharging of the secondary battery 2, the self-diagnosis unit 12 outputs a signal for turning off the charging / discharging FETs 16 and 17 through the FET control unit 15. If the charging current is still detected for 4 seconds or more in that state, either the overcharge control circuit or the charging / discharging FE is used.
T16, 17 is diagnosed as abnormal, and self-diagnosis means 1
2 outputs a signal indicating that the battery pack is abnormal, a signal for stopping charging, or both signals to the electronic device through the communication means 14.

Further, as shown in the flow chart of FIG.
Diagnose the shutdown function . First, the shutdown function will be described. In recent battery packs, a microcomputer (BMU) is built into the battery pack itself, and information such as voltage, capacity, and temperature is internally notified to the electronic device to reduce the burden on the electronic device. Some built-in microcomputers cut the electric circuit of the microcomputers themselves to protect the secondary battery 2 from over-discharging when the voltage drops considerably. This is called shutdown. In this case, since the information held by the microcomputer is once erased, it is inconvenient if there is useful information that has been stored up to now, and in general, control is performed so that it will not be shut down except in an emergency.

Usually, the voltage of the secondary battery 2 is the voltage detecting means 1
3 is detected and the detected total voltage is, for example, 5 V or less, the battery pack is configured to shut down because the voltage is abnormally low. Therefore, even if the total voltage detected is 5 V or less, if the shutdown is not performed, the shutdown function is diagnosed as abnormal, and the self-diagnosis unit 12 notifies the electronic device through the communication unit 14 that the battery pack is abnormal. Alternatively, it outputs a signal to stop charging or both signals.
As a result, the risk of over-discharging the secondary battery 2 can be more reliably avoided.

The EEPRO provided in the BMU1
M18 is a memory as an information holding unit that holds a history of abnormalities and holds that charging is impossible. As a result, in the case of a battery pack with an abnormality, the history of the abnormality remains, so
The self-diagnosis means 12 reads the information from the EEPROM 18 before the battery pack is connected to the electronic device and starts charging, so that charging is not started in the case of a battery pack having a history of abnormality. As a result, various inconveniences caused by charging an abnormal battery pack can be avoided in advance.

The FET failure diagnosis function, overcharge control circuit and overcharge control circuit diagnosis function, shutdown circuit, shutdown function diagnosis function, and EEPRO.
M18 is a self-diagnosis means 12 controlled by microcomputer software.
Included inside, integrated into an IC and stored in one package.

[0036]

As is apparent from the above-described embodiments, according to the present invention, the FET failure diagnosis, the overcharge control circuit diagnosis, and the shutdown function diagnosis are performed to realize the dual protection of the battery pack. Since it is possible to perform the role and quickly detect the abnormality when the battery voltage is low, it is possible to prevent inconvenience such as overcharging.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a battery pack failure diagnosis device of the present invention.

FIG. 2 is a flowchart showing the failure diagnosis of the FET of the present invention.

FIG. 3 is a flowchart showing diagnosis of the overcharge control circuit of the present invention.

FIG. 4 is a flowchart showing diagnosis of a shutdown function of the present invention.

[Explanation of symbols]

1 BMU 2 Secondary battery 3 Positive terminal 4 Negative electrode terminal 5 information terminals 10 Current detection resistor 11 Current detection means 12 Self-diagnosis means 13 Voltage detection means 14 Communication means 15 FET controller 16 Charging FET 17 Discharge FET 18 EEPROM

─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-9-312172 (JP, A) JP-A-7-45306 (JP, A) JP-A-8-98414 (JP, A) JP-A-8- 329986 (JP, A) JP-A-7-230829 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H02J ^7/ 00-7/12 H02J ⁷ /34-7/36

Claims (4)

(57) [Claims] 1. A self-diagnosis is performed by using voltage detection means for detecting a battery voltage of a secondary battery, current detection means for detecting a current flowing in a charging path, and outputs of the voltage detection means and the current detection means as inputs. Self-diagnosis means, non-volatile information holding means for holding information of the self-diagnosis, FET for charge / discharge control, FET control section for controlling the FET by inputting the output of the self-diagnosis means, And a communication unit that outputs information to an externally connected electronic device by using the output of the self-diagnosis unit as an input, and the self-diagnosis unit forcibly turns off the FET during charging, and the charging current is less than a specified value. performs fault diagnosis of the FET by diagnosing whether the said read information of non-volatile self-diagnosis, which is held in the information holding means, it the contents of less than the charge current specified value Not when
A battery pack failure diagnosing device, which outputs a signal for controlling the secondary battery to be unable to be charged to the electronic device when the abnormality is indicated. 2. A self-diagnosis is carried out by inputting voltage detection means for detecting a battery voltage of a secondary battery, current detection means for detecting a current flowing in a charging path, and outputs of the voltage detection means and the current detection means. Self-diagnosis means, non-volatile information holding means for holding information of the self-diagnosis, FET for charge / discharge control, FET control section for controlling the FET by inputting the output of the self-diagnosis means, The self-diagnosis means is provided with a communication means for inputting the output of the self-diagnosis means to output information to an electronic device connected to the outside, and the self-diagnosis means performs overcharge detection by diagnosing whether or not the charging current is stopped when overcharge is detected. While diagnosing the charge control circuit, the self-diagnosis information stored in the non-volatile information storage means is read, and the contents indicate that the charging current has stopped.
A battery pack failure diagnosing device, which outputs a signal for controlling the secondary battery to be unable to be charged to the electronic device when the abnormality indicates that the battery pack will not be stopped . 3. A self-diagnosis is performed by inputting voltage detection means for detecting a battery voltage of a secondary battery, current detection means for detecting a current flowing in a charging path, and outputs of the voltage detection means and the current detection means. Self-diagnosis means, non-volatile information holding means for holding information of the self-diagnosis, FET for charge / discharge control, FET control section for controlling the FET by inputting the output of the self-diagnosis means, And a communication unit that outputs information to an electronic device connected to the outside by using the output of the self-diagnosis unit as an input, and the self-diagnosis unit diagnoses whether or not a value detected by the voltage detection unit is larger than a shutdown voltage. performs diagnosis of the shutdown function by reading the information of the self-diagnosis, which is held in the non-volatile data holding means, detection value by the contents of the voltage detecting means Shut
A battery pack failure diagnosing device, which outputs a signal for controlling the secondary battery to be unable to be charged to the electronic device when the abnormality indicates that the voltage is equal to or lower than the down voltage. 4. A battery pack failure diagnosing device, characterized in that at least one self-diagnosing means according to claim 1 is housed in the same IC package as the information holding means. .