JP2008098056A - Battery pack, and control method of battery pack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To balance correctness of information stored in a memory incorporated in a battery pack with reduction of storage capacity. <P>SOLUTION: The battery pack is formed into a structure provided with: a battery cell; a charge/discharge control switch controlling charge or discharge of the battery cell; a protection mechanism part prohibiting the charge or discharge of the battery cell; the memory storing information required for control of the charge or discharge of the battery cell; and a control part controlling the charge/discharge control switch. The control part updates stored information of the memory, executes true or false determination for specific partial information within the information stored in the memory, and causes the protection mechanism part to prohibit charge or discharge when an error is detected in the true or false determination. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a battery pack including a battery cell such as a secondary battery, which is used as a driving power source for various electronic devices, and a method for controlling the battery pack, and more particularly to a battery pack including a memory in the battery pack. Regarding technology.

  Conventionally, a secondary battery such as a lithium ion secondary battery requires appropriate control and protection for charging and discharging, and a protection circuit is built in a battery pack together with a battery cell. In this case, a battery, in particular, a non-volatile memory is built in the battery pack, and information such as characteristics of the battery cell is stored and used for control of charging and discharging. For example, a battery that stores information such as the charging characteristics and discharging characteristics of the battery cells in the battery pack or the number of times of charging and discharging has been put into practical use. When such a battery pack is attached to an electronic device, the memory information can be sent from the battery pack side to the electronic device side, and the life of the battery pack can be displayed on the electronic device side. Usability of equipment used as a power source is improved.

Patent Document 1 describes an example of a configuration in which a nonvolatile memory is built in a battery pack and control such as charging is performed.
JP 2005-65429 A

  By the way, the non-volatile memory built in the battery pack is used for the purpose of controlling the charging or discharging of the battery. The model number of the mounted battery cell, the charging current / voltage, the discharging current / voltage, etc. The information about the use state such as the characteristic value and the number of times of charging and discharging is stored, and a non-volatile memory having a large capacity is not used. It is not preferable to use a non-volatile memory having a large capacity because the manufacturing cost of the battery pack increases.

On the other hand, it is important that the information stored in the nonvolatile memory built in the battery pack is accurate. However, the possibility that erroneous information is stored for some reason is very low, but is not. For example, there may be a case where there is a defect in data retention capability due to a defect in the nonvolatile memory itself, or a case where stored data changes due to some noise coming from the outside.
If information is stored in the memory by mistake, there is a possibility that the control state of charging or discharging of the battery cell may be incorrect, which is not preferable.
In order to prevent such an error in the stored information in the memory, for example, it is possible to prevent the error in the information by increasing the redundancy of the information to be stored. However, if the redundancy in the stored information in the memory is simply increased, The amount of information to be stored in the memory increases, and the memory capacity required for the battery pack increases. As described above, the manufacturing cost of the battery pack increases, which is not preferable.

  In view of the above, an object of the present invention is to achieve both accuracy of information stored in a memory built in a battery pack and reduction in storage capacity.

  In order to solve such problems, the battery pack of the present invention includes a battery cell, a charge / discharge control switch that controls charging or discharging of the battery cell, a protection mechanism that prohibits charging or discharging of the battery cell, and charging of the battery cell. Or it is set as the structure provided with the memory which memorize | stores information required for control of discharge, and the control part which controls a charging / discharging control switch. The control unit updates the stored information in the memory, makes a correct / incorrect determination on a part of the information stored in the memory, and when the error is detected in the correct / incorrect determination, the control unit charges or It was set as the structure which prohibits discharge.

  The battery pack control method of the present invention is a battery pack control method comprising a memory for storing battery cell control information. Among the information necessary for controlling the charging or discharging of the battery cells stored in the memory, The correctness / incorrectness of information on a specific part is determined. And when it was judged that it was incorrect information based on the right / wrong judgment result, the restriction | limiting process which prohibits charge and discharge to a battery cell was performed.

  According to the present invention, the correctness / incorrectness determination is performed only for a specific part of the information for battery control stored in the memory. For example, only important information for controlling important charging is stored. If correct / incorrect determination is performed, good control can be performed.

  According to the present invention, it is only necessary to make a correct / incorrect determination only for a specific part of the battery control information stored in the memory. For example, information important for controlling important charging. If only the data is stored and the correct / incorrect determination is made, it is possible to control charging or discharging satisfactorily with a small memory capacity.

Hereinafter, an example of an embodiment of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a block diagram showing a configuration example of the battery pack of this example. In the battery pack 10, a plurality of (here, two) secondary battery cells 51 and 52 are incorporated. Here, lithium ion secondary batteries are used as the secondary battery cells 51 and 52. Further, in FIG. 1, the cell configuration is such that two cells are connected in series, but the number of cells to be incorporated is not limited to two, and the connection state is not limited to series connection.

  The positive electrode terminal 11 and the negative electrode terminal 12 of the battery pack 10 are connected to the terminals 21 and 22 of the circuit board 20 in the battery pack 10. The terminal 21 is connected to a battery terminal 27 on the positive electrode side through charge / discharge control field effect transistors (FETs) 23 and 24 and a fuse 30 with a heating temperature resistor. The two field effect transistors 23 and 24 for charge / discharge control have connection directions opposite to each other. One transistor 23 controls discharge and the other transistor 24 controls charging. The fuse 30 with a heating temperature resistor is a protection means for preventing the secondary battery cells 51 and 52 from being used in an emergency.

  That is, two fuses 31 and 32 are connected in series between the field effect transistor 24 and the battery terminal 27, and heating resistors 33 and 34 are arranged in the vicinity of the two fuses 31 and 32. is there. The heat generating resistors 33 and 34 are energized under the control of the charge / discharge control unit 25 described later to generate heat. When the heat generating resistors 33 and 34 generate heat, the fuses 31 and 32 are melted, and the positive electrode side of the secondary battery cell 51 in the battery pack 10 is disconnected from the positive electrode terminal 11 of the battery pack 10.

  The positive terminal of the battery cell 51 is connected to the battery terminal 27 of the circuit board 20. The negative electrode of the battery cell 51 is connected to the positive electrode of another battery cell 52, and the connection point between both battery cells 51 and 52 is connected to the battery terminal 28 of the circuit board 20. The battery terminal 28 is a terminal for measuring the cell voltage of each battery cell 51, 52. The negative electrode of the battery cell 52 is connected to the battery terminal 29 on the negative electrode side of the circuit board 20. The battery terminal 29 on the negative side of the circuit board 20 is connected to the negative terminal 12 of the battery pack 10 via the terminal 22 of the circuit board 20.

  A charge / discharge control unit 25 composed of an MPU (Micro Processing Unit) is prepared on the circuit board 20, and the charge / discharge control unit 25 controls charging and discharging of the battery cells 51 and 52. As a configuration. The charge / discharge control unit 25 is connected to a nonvolatile memory 40 that stores information necessary for control, and the storage information in the nonvolatile memory 40 can be rewritten by the control of the charge / discharge control unit 25.

  As a control configuration by the charge / discharge control unit 25, the charge / discharge control unit 25 controls the gate potential of the field effect transistors 23, 24 to control the switching state of both the field effect transistors 23, 24. . Specifically, the field effect transistors 23 and 24 are turned on during charging. By doing so, a current path from the positive electrode terminal 11 of the battery pack 10 to the positive electrode of the battery cell 51 is configured via the field effect transistor 23 and the transistor 23, and the positive electrode terminal 11 of the battery pack 10 is formed. The battery cells 51 and 52 are charged with the charging current obtained as described above. When the charging is stopped, the field effect transistor 24 is turned off.

  At the time of discharging, the field effect transistors 23 and 24 are turned on. By doing so, a current path from the positive electrode of the battery cell 51 to the positive electrode terminal 11 of the battery pack 10 is formed via the field effect transistor 24 and the transistor 23, and the battery cell 51, 52 is externally connected. A discharge path to the battery pack 10 is configured, and discharge to the electronic device to which the battery pack 10 is connected becomes possible. When the discharge is stopped, the field effect transistor 23 is turned off.

  In addition, the charge / discharge control unit 25 is configured to detect the voltages of the battery terminals 27, 28, and 29 and monitor the individual cell voltages of the battery cells 51 and 52. Furthermore, the charge / discharge control unit 25 is configured to control the conduction of the fuse control switching element 26 so that the two fuses 31 and 32 are blown in an emergency. In addition, it is good also as a structure which connects the resistance for charge / discharge current measurement in series with the battery cells 51 and 52, and the charge / discharge control unit 25 monitors charge / discharge current from the voltage of the both ends of the resistance. Moreover, as a structure provided with the terminal for communication as an external terminal with which the battery pack 10 is provided, the charge / discharge control unit 25 in the battery pack 10 may be configured to communicate with the control unit on the device side to which the battery pack is connected. Good.

  Next, the nonvolatile memory 40 connected to the charge / discharge control unit 25 will be described with reference to FIG. As shown in FIG. 2, the nonvolatile memory 40 of the present example has a configuration in which a variable value storage area 41, a first fixed value storage area 42, and a second fixed value storage area 43 are provided as shown in FIG. is there. The variable value storage area 41 stores (records) different values for each pack, such as the number of times the battery pack is charged, the number of discharges, the date of manufacture of the battery pack, and the serial number of the battery pack. The values stored in these variable value storage areas 41 are information that is not directly related to charge / discharge battery control. The number of times the battery pack is charged and discharged is updated under the control of the charge / discharge control unit 25 every time charging or discharging is performed, and is mainly used for determining the battery life.

  The same information is stored twice for the first fixed value storage area 42 and the second fixed value storage area 43. The stored information is relatively important information for performing battery control, such as battery characteristic data, overcharge prohibition voltage, overdischarge prohibition voltage, abnormality detection temperature, and fuse blowing conditions. The information stored in the first and second fixed value storage areas 42 and 43 is a fixed value storage area in which the same information is stored as long as the types of the battery pack and the battery cell are the same. .

Further, as shown in FIG. 2, for the first fixed value storage area 42 and the second fixed value storage area 43, checksum storage areas 42a and 43a are provided, respectively. In the checksum storage area 42a, the error detection code of the information stored in the first fixed value storage area 42 is stored. In the checksum storage area 43a, the error detection code of the information stored in the second fixed value storage area 43 is stored. Since the information stored in the fixed value storage areas 42 and 43 is not basically updated, an error detection code prepared in advance is stored when the battery pack is manufactured.
As information to be stored in the respective checksum storage areas 42a and 43a, a CRC (Cyclic Redundancy Check) code capable of detecting an error may be stored instead of the error detection code.

  The charge / discharge control unit 25 included in the battery pack 10 configured as described above is configured to perform comparison processing of the fixed value storage areas 42 and 43 of the nonvolatile memory 40 as needed. This comparison process is executed at any time at a predetermined timing, for example, whenever charging is performed or discharging is performed.

  The flowchart of FIG. 3 is a diagram illustrating a processing example when the charge / discharge control unit 25 performs the comparison processing of the fixed value storage areas 42 and 43 of the nonvolatile memory 40. 3 will be described below. First, the charge / discharge control unit 25 reads information stored in the first fixed value storage area 42 (step S11), and then continues to the second fixed value storage area 43. Is read (step S12). Then, it is determined whether or not the information stored in the first fixed value storage area 42 matches the information stored in the second fixed value storage area 43 (step S13).

  If they match in the determination in step S13, it is determined that the stored values in the fixed value storage areas 42 and 43 are normal (step S14). When it is determined that this is normal, charging and discharging of the battery cell are controlled using the fixed value information read from the fixed value storage area 42 or 43. On the other hand, if they do not coincide with each other in step S13, an abnormal recovery process is performed for the fixed value storage area (step S15).

  The flowchart of FIG. 4 is a diagram showing an example of an abnormal recovery process for the fixed value storage area. In the following, referring to FIG. 4, an error detection code is generated from the fixed value information read from the first fixed value storage area 42 by calculation in the charge / discharge control unit 25 (step S21). Then, the error detection code stored in the checksum storage area 42a is read (step S22), and the error detection code generated by the operation is compared with the read error detection code (step S23). In the comparison, when both codes match, it is determined that the information stored in the first fixed value storage area 42 is correct information (step S24), and the information is read from the first fixed value storage area 42. Control of charging and discharging of the battery cell is performed using the fixed value information (step S25).

  If the two codes do not match in the comparison in step S23, an error detection code is generated from the fixed value information read from the second fixed value storage area 43 by calculation in the charge / discharge control unit 25 ( Step S26). Then, the error detection code stored in the checksum storage area 43a is read (step S27), and the error detection code generated by the operation is compared with the read error detection code (step S28). In the comparison, if both codes match, it is determined that the information stored in the second fixed value storage area 43 is correct information (step S29), and is read from the second fixed value storage area 43. Control of charging and discharging of the battery cell is performed using the fixed value information (step S30).

If the two codes do not match in the comparison in step S28, it is determined that the storage information in any fixed storage area is abnormal, and an abnormality in the control information is detected (step S11). When this control information abnormality is detected, for example, the fuse control switching element 26 is turned on to blow the two fuses 31 and 32 so that the battery pack 10 cannot be used. Alternatively, the charge / discharge control field effect transistors 23 and 24 may be left in an off state, and a process in which neither charge nor discharge can be performed may be performed.
If it is determined in step S24 that the storage information in the first fixed value storage area 42 is correct, and if it is determined in step S29 that the storage information in the second fixed value storage area 43 is correct, these determinations are made. Information may be written in the variable value storage area 41 of the nonvolatile memory 40. In this way, at the time of subsequent battery control, at least the fixed value area comparison process shown in the flowchart of FIG. 3 is not performed, and the first fixed value storage area 42 or the second fixed value storage area 43 is directly used. It is possible to read the stored information and make a determination using the checksum.

As described above, according to the battery pack of this example, the storage area of the nonvolatile memory 40 is divided into the variable value storage area and the fixed value storage area. Since the same information is stored multiple times, a fixed value, which is particularly important information for charge and discharge control, can be surely stored in the memory 40. Also, if the stored information in any one of the fixed value storage areas becomes incorrect, it can be determined by the collation process of the two stored information, and the battery pack will not continue to be used using the incorrect information.
In addition, for each of the two fixed value storage areas, a checksum storage unit is provided to store the error detection code, so whether the stored information is correct for each fixed value storage area. Even if an error occurs in a part of the stored information in the memory, it is possible to cope with it, and it is possible to continue the control of charging and discharging correctly.

  In the case of this example, only fixed value information (specific information), which is particularly important information for charge and discharge control, among information stored in the nonvolatile memory 40 is stored in a multiplex manner. As a result, the storage capacity of the nonvolatile memory 40 can be greatly reduced as compared with the case where all the storage information is stored in a multiplex manner, and the storage capacity of the conventional battery pack is slightly increased. Well, there is almost no increase in cost by realizing the configuration of this example. The error detection code stored in the checksum storage unit also has a much smaller data amount than the fixed value information, and can suppress an increase in the storage capacity of the memory. Therefore, according to the battery pack of this example, it is possible to achieve both the accuracy of the information stored in the memory built in the battery pack and the reduction of the storage capacity.

  In the embodiment described above, a secondary battery constituted by a lithium ion secondary battery is used as a cell incorporated in the battery pack. However, other secondary battery cells such as a nickel hydride secondary battery are used. The present invention can also be applied to a case where a nonvolatile memory is provided in a built-in battery pack and charging or discharging information is stored in the memory.

  Alternatively, in order to control the discharge of an alkaline manganese battery or the like configured as a primary battery, the present invention can be applied to a case where information for controlling discharge is stored in the memory as a configuration provided with a nonvolatile memory. . It is particularly suitable when a memory is provided for controlling discharge of a primary battery having a long life.

  In the above-described embodiment, a non-volatile memory in which stored information is held without a power supply is used as a memory. However, a volatile memory that needs a power supply to hold stored information may be used. The power required to hold the memory information in the memory is generally very low, and the memory information can be held by using only a part of the power source from the battery cell built in the battery pack. It is possible to hold stored information almost the same as when a nonvolatile memory is used.

In the above-described embodiment, the information in the fixed area of the information stored in the memory is divided into two, and the same information is duplicated in the first fixed area and the second storage area. Although the information is stored, the same information may be stored in a triple or more multiplex.
Alternatively, when the same information is stored twice in the first fixed area and the second storage area, the check code (checksum) is included in the information of one of the fixed areas. The check code may be shared so that the storage area of the memory can be reduced.

It is a block diagram which shows the structural example of the battery pack by the example of one embodiment of this invention. FIG. 2 is an explanatory diagram illustrating a configuration example of a memory of FIG. 1 example; It is a flowchart which shows the example of a comparison process of the fixed area | region by one embodiment of this invention. It is a flowchart which shows the restoration process example of the fixed area | region by one embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Battery pack, 11 ... Positive electrode terminal, 12 ... Negative electrode terminal, 20 ... Circuit board, 21, 22 ... Terminal, 23, 24 ... Field effect transistor (FET) for charge / discharge control, 25 ... Charge / discharge control unit (Micro Processing) Unit), 26 ... switching element for controlling the fuse, 27, 28, 29 ... battery connection terminal, 30 ... fuse with heating temperature resistor, 31, 32 ... fuse, 33, 34 ... heating resistor, 40 ... nonvolatile memory, 41 ... Variable value storage area, 42 ... first fixed value storage area, 43 ... second fixed value storage area, 42a, 43a ... checksum storage area

Claims (6)

A battery cell;
A charge / discharge control switch for controlling charging or discharging of the battery cell;
A protection mechanism for prohibiting charging or discharging of the battery cell;
A memory for storing information necessary for controlling charging or discharging of the battery cell;
The charge / discharge control switch is controlled, the information stored in the memory is updated, and correctness / incorrectness determination is performed for a part of the information stored in the memory, and an error is detected in the correctness / incorrectness determination. And a control unit that prohibits charging or discharging by the protection mechanism unit. The battery pack according to claim 1, wherein
As the memory,
A battery pack comprising: a first storage area that stores the specific part of information; and a second storage area that stores information other than the specific part of information. The battery pack according to claim 2,
As the memory,
A battery pack, wherein a checksum for correct / incorrect determination is added to the information of the specific information stored in the first storage area. The battery pack according to claim 2,
As the memory,
A first storage area for storing the specific partial information; and a second storage area for storing information other than the specific partial information;
The information of the specific partial information stored in the first storage area is duplicated and stored in a multiplex manner. The battery pack according to claim 2,
The specific part of information stored in the first storage area is fixed information written when the battery pack is manufactured,
Information updated by use of the battery pack is stored in the second storage area. In a battery pack control method comprising a memory for storing control information of battery cells,
Among the information necessary for controlling the charging or discharging of the battery cell to be stored in the memory, determine whether the information is specific or not,
A control method for a battery pack, wherein a restriction process for prohibiting charging and discharging of the battery cell is performed when it is determined that the information is incorrect based on the determination result.

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