JP2010081777A - Controlling apparatus and method of battery cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform discharging control of battery cells at a low cost. <P>SOLUTION: A battery cell controlling apparatus 3 has battery cells CL connected in series with each other and discharging circuits 6 connected with the battery cells CL, and performs discharging control so as to make the voltages of the battery cells CL uniform in each battery cell. The discharging circuit 6 has a resistance R<SB>j</SB>provided for each adjacent battery cells CL<SB>i</SB>, CL<SB>i+1</SB>, and the resistance R<SB>j</SB>is constituted so as to be selectively connected in parallel with each of the two battery cells CL<SB>i</SB>, CL<SB>i+1</SB>. The battery-cell controlling apparatus 3 is constituted so that discharging control is performed to the battery cell CL<SB>i</SB>by connecting the resistance R<SB>j</SB>in parallel with one battery cell CL<SB>i</SB>of the battery cells, and then discharging control is performed to the other battery cell CL<SB>i+1</SB>by connecting the resistance R<SB>j</SB>with the other battery cell CL<SB>i+1</SB>. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a battery cell control apparatus and a control method for performing discharge control so that the voltage of each battery cell is uniform among a plurality of battery cells connected in series.

  In recent years, electric vehicles and hybrid electric vehicles have become widespread, and in such vehicles, a battery cell unit configured by connecting a plurality of battery cells in series is used as a power source for an electric motor.

  In such battery cell units, there are variations in the temperature characteristics and capacities of the battery cells due to variations in manufacturing and variations over time. As described above, when discharging and charging are repeated in a state where the temperature characteristics and capacities of the battery cells vary, the voltage of each battery cell also varies. And if discharge and charge are repeated while the voltage for every battery cell varies, overdischarge and overcharge may occur depending on the battery cell. In order to prevent such overdischarge and overcharge, it is necessary to equalize the voltage of each battery cell.

As a method for equalizing the voltage of the battery cell, a configuration in which a discharge circuit is provided for each battery cell is known. For example, Patent Document 1 discloses a configuration in which a discharge circuit configured by connecting a pair of a switch and a resistor connected in series to a battery cell in parallel is provided for each battery cell. That is, by discharging a current through a resistor connected to the battery cell, the SOC (State of charge) of the battery cell is adjusted to adjust the voltage of the battery cell. By performing such discharge control for each battery cell, the voltage for each battery cell can be made uniform.
JP 2007-244058 A

  However, in the discharge circuit according to Patent Document 1, it is necessary to provide a resistance for each battery cell, which increases the cost.

  This invention is made | formed in view of this point, The place made into the objective is to perform discharge control of a battery cell at low cost.

  In the present invention, a discharging resistor is shared between adjacent battery cells.

  Specifically, the first invention includes a plurality of battery cells connected in series, and a discharge circuit connected to the battery cell for discharging the battery cell, and controlling the discharge circuit. Thus, the battery cell control device that performs discharge control so that the voltage of each battery cell becomes uniform is an object. The discharge circuit has a resistor provided for every two adjacent battery cells, and is configured to selectively connect the resistor to each of the two battery cells in parallel. The discharge control of one of the battery cells is performed by connecting the resistor in parallel to one of the battery cells, and then the resistor of the other battery cell is connected in parallel to the other battery cell. It is configured to perform discharge control.

  In the case of the above configuration, the resistor is shared by two adjacent battery cells. In this way, even if the resistor is shared by two adjacent battery cells, the resistor is adjacent by switching between a state in which the resistor is connected in parallel to one battery cell and a state in which the resistor is connected in parallel to the other battery cell. The discharge control of the two battery cells can be performed respectively.

  According to a second invention, in the first invention, the plurality of battery cells are sorted into a battery cell having a relatively large capacity and a battery cell having a relatively small capacity, and the two adjacent battery cells are It is assumed that the battery cell has a combination of a battery cell having a relatively large capacity and a battery cell having a relatively small capacity.

  In the case of the above configuration, two adjacent battery cells sharing the resistor are a combination of a battery cell having a relatively large capacity and a battery cell having a relatively small capacity. By adopting such a combination, the discharge control as a whole of the plurality of battery cells can be performed efficiently, that is, as quickly as possible.

  Explaining in detail, for example, even when charging or discharging is performed uniformly from a state in which the voltage, that is, SOC, is balanced between a plurality of battery cells, and the amount of electricity is increased or decreased uniformly for each battery cell. The larger the capacity of the battery cell, the smaller the change amount of the SOC with respect to the increase or decrease of the amount of electricity.

  In addition, even if each battery cell is discharged from a state where the voltage, that is, the SOC, varies for each battery cell and the SOC of each battery is set to a predetermined value, if the capacity of the battery cell is different, the change in the SOC The amount of discharge corresponding to the amount is also different. For example, the amount of discharge for changing the SOC by 1% increases as the capacity of the battery cell increases.

  Thus, the amount of change in voltage when charging / discharging differs depending on the capacity of the battery cell, and the amount of discharge required for adjusting the voltage, that is, the discharge time, also differs.

  And each capacity | capacitance of a some battery cell does not necessarily correspond. Even if a plurality of battery cells are configured with battery cells having the same rated capacity, the capacity of each battery cell is slightly different due to a manufacturing error or the like, and as a result, the time required for discharge control is also different.

  Here, in order to shorten the time required for discharge control as a set of battery cells, it is preferable to combine battery cells having a short time required for discharge control. However, which of the battery cell having a relatively large capacity and the battery cell having a relatively small capacity has a short time required for the discharge control differs depending on the use situation as described later. Therefore, for example, when battery cells having relatively small capacities are combined, the time required for the discharge control may be shortened in a certain use situation, but the time required for the turnover and the discharge control may be shortened in another use situation. May be longer. In addition, when battery cells having a short time required for discharge control are combined, a combination of battery cells having a long time required for discharge control is inevitably generated when viewed as a whole of a plurality of battery cells. Then, even if a certain battery cell set requires a short time for discharge control, another battery cell set always increases the time required for discharge control. Here, the time required for the discharge control as a whole of the plurality of battery cells is determined by the time required for the battery cell group having the slowest discharge control. Therefore, if there is even one battery cell set that requires a long time for discharge control, the time required for discharge control as a whole of the plurality of battery cells becomes long.

  On the other hand, in the above-described configuration, a plurality of battery cells are sorted into battery cells having a relatively large capacity and battery cells having a relatively small capacity, and the capacity of the battery cell having a relatively large capacity is relatively large. The discharge circuit is connected as a set of small battery cells. By doing so, the time required for the discharge control of one battery cell is always shortened regardless of the usage state of the battery cell, and the time required for the discharge control of the other battery cell is always increased in any pair. Therefore, the dispersion | variation in the time which discharge control for every group of battery cells requires can be suppressed. As a result, since the discharge control of each set of battery cells is completed at substantially the same timing, the discharge control can be performed efficiently for each set of battery cells, and the time required to equalize the voltages of all the battery cells. Can be shortened.

  A third invention includes a plurality of battery cells connected in series, and a discharge circuit connected to the battery cell for discharging the battery cell, and controlling each of the battery cells by controlling the discharge circuit. The battery cell control device that performs discharge control so that the voltage of the battery becomes uniform is an object. The discharge circuit includes first and second resistors provided for each two adjacent battery cells, and the first resistor is selectively connected in parallel to each of the two adjacent battery cells. And the second resistor is selectively connected in parallel to each of the two adjacent battery cells, the first resistor is connected in parallel to one of the battery cells, and After the second resistor is connected in parallel to the other battery cell, the discharge control of the two battery cells is performed separately, and after the discharge control of one of the two battery cells is completed It is assumed that the discharge control of the battery cell is performed by connecting the first and second resistors in parallel to the battery cell for which the discharge control has not been completed.

  In the case of the above-described configuration, first, two adjacent battery cells are separately controlled for discharge by the first and second resistors, respectively. Since the capacities of the respective battery cells are different, the discharge control of the two battery cells is not completed at the same time, and either one is completed first. Thus, when the discharge control of one of the battery cells is completed, the first and second resistors are connected in parallel to the battery cell for which the discharge control has not been completed, and the discharge control is performed. As a result, the battery cell whose discharge control has not been completed is rapidly discharged as compared with the case where only one resistor is connected in parallel, and the discharge control can be completed quickly.

  That is, in the apparatus according to Patent Document 1, since the resistors are fixedly assigned to each battery cell in a one-to-one relationship, the battery cells in which the discharge control is completed early have a surplus of resistors. .

  On the other hand, in the above-described configuration, the discharge control of the other battery cell is performed by connecting in parallel with the other battery cell adjacent to the other battery cell, which has been previously held in excess, the discharge control completed first. Can be done quickly. Thus, with the above-described configuration, rapid discharge control can be realized with an inexpensive configuration without increasing the number of resistors from the conventional configuration.

  In a fourth aspect based on the third aspect, the plurality of battery cells are sorted into a battery cell having a relatively large capacity and a battery cell having a relatively small capacity, and the two adjacent battery cells are It is assumed that the battery cell has a combination of a battery cell having a relatively large capacity and a battery cell having a relatively small capacity.

  In the case of the above configuration, the two adjacent battery cells are a combination of a battery cell having a relatively large capacity and a battery cell having a relatively small capacity. By adopting such a combination, the discharge control as a whole of the plurality of battery cells can be performed efficiently, that is, as quickly as possible.

  That is, as described above, a plurality of battery cells are sorted into battery cells having relatively large capacity and battery cells having relatively small capacity, and battery cells having relatively large capacity and battery cells having relatively small capacity. By connecting the discharge circuit as a set, the time required for the discharge control of one battery cell is always shortened regardless of the usage status of the battery cell, and in any set, the other battery cell Since the time required for the discharge control becomes longer, it is possible to suppress variations in the time required for the discharge control for each set of battery cells. As a result, since the discharge control of each set of battery cells is completed at substantially the same timing, the discharge control can be performed efficiently for each set of battery cells, and the time required to equalize the voltages of all the battery cells. Can be shortened.

  In addition, in the above configuration, the two battery cells are separately controlled by the first and second resistors, and when the discharge control of one of the battery cells is completed, the other battery cell is controlled by the first and second resistors. Since the discharge control is performed by both of the second resistors, even if the discharge circuit is connected by combining a battery cell having a relatively large capacity and a battery cell having a relatively small capacity, Can be done quickly.

  That is, when a battery cell having a relatively large capacity and a battery cell having a relatively small capacity are combined, one of the two battery cells has a short time required for discharge control. Even if discharge control is separately performed with two resistors, the discharge control of one of the battery cells is completed early. As a result, it is possible to shorten the time for performing the discharge control separately in the first and second resistors, and to quickly shift to the discharge control in which the other battery cell is discharged by both the first and second resistors. it can. The other battery cell of the two battery cells is inherently long in discharge control, but since it is discharged by both the first and second resistors from the middle, the first and second resistors The discharge control can be completed early using both of the devices. As described above, the first and second resistors are used to shorten the time for performing the discharge control separately in the first and second resistors as much as possible, and for the battery cell that originally takes a long time for the discharge control. By performing discharge control at a high speed using both of these, the time required for discharge control as a set of two battery cells can be shortened.

  The fifth invention is directed to a battery cell control method in which discharge control is performed so that the voltage of each battery cell is uniform among a plurality of battery cells connected in series. Then, a step of performing discharge control of one of the battery cells by connecting a resistor provided for each two adjacent battery cells in parallel to one of the battery cells, and discharging control of one of the battery cells is performed. A step of performing discharge control of the other battery cell by connecting the resistor in parallel to the other battery cell after completion.

  In the case of the above configuration, the resistor is shared by two adjacent battery cells. Thus, even if the resistor is shared by two adjacent battery cells, the step of connecting the resistor in parallel to one battery cell and the step of connecting the resistor in parallel to the other battery cell are performed by switching. The discharge control of two adjacent battery cells can be performed respectively.

  In a sixth aspect based on the fifth aspect, the plurality of battery cells are sorted into battery cells having a relatively large capacity and battery cells having a relatively small capacity, and the two adjacent battery cells are It is assumed that the battery cell has a combination of a battery cell having a relatively large capacity and a battery cell having a relatively small capacity.

  In the case of the above configuration, two adjacent battery cells sharing the resistor are a combination of a battery cell having a relatively large capacity and a battery cell having a relatively small capacity. By adopting such a combination, the discharge control as a whole of the plurality of battery cells can be performed efficiently, that is, as quickly as possible.

  That is, as described above, a plurality of battery cells are sorted into battery cells having relatively large capacity and battery cells having relatively small capacity, and battery cells having relatively large capacity and battery cells having relatively small capacity. By connecting the discharge circuit as a set, the time required for the discharge control of one battery cell is always shortened regardless of the usage status of the battery cell, and in any set, the other battery cell Since the time required for the discharge control becomes longer, it is possible to suppress variations in the time required for the discharge control for each set of battery cells. As a result, since the discharge control of each set of battery cells is completed at substantially the same timing, the discharge control can be performed efficiently for each set of battery cells, and the time required to equalize the voltages of all the battery cells. Can be shortened.

  The seventh invention is directed to a battery cell control method in which discharge control is performed so that the voltage of each battery cell is uniform among a plurality of battery cells connected in series. Of the first and second resistors provided for each two adjacent battery cells, the first resistor is connected in parallel to one of the battery cells, and the second resistor is connected to the other battery cell. A step of separately controlling the discharge of the two battery cells by connecting them in parallel, and after completing the discharge control of one of the two battery cells, both of the first and second resistors are connected. A step of performing discharge control of the battery cell by connecting in parallel to the battery cell for which discharge control has not been completed.

  In the case of the above-described configuration, first, two adjacent battery cells are separately controlled for discharge by the first and second resistors, respectively. Since the capacities of the respective battery cells are different, the discharge control of the two battery cells is not completed at the same time, and either one is completed first. Thus, when the discharge control of one of the battery cells is completed, the first and second resistors are connected in parallel to the battery cell for which the discharge control has not been completed, and the discharge control is performed. As a result, the battery cell whose discharge control has not been completed is rapidly discharged as compared with the case where only one resistor is connected in parallel, and the discharge control can be completed quickly.

  That is, in the apparatus according to Patent Document 1, since the resistors are fixedly assigned to each battery cell in a one-to-one relationship, the battery cells in which the discharge control is completed early have a surplus of resistors. .

  On the other hand, in the above-described configuration, the discharge control of the other battery cell is performed by connecting in parallel with the other battery cell adjacent to the other battery cell, which has been previously held in excess, the discharge control completed first. Can be done quickly. Thus, with the above-described configuration, rapid discharge control can be realized with an inexpensive configuration without increasing the number of resistors from the conventional configuration.

  In an eighth aspect based on the seventh aspect, the plurality of battery cells are sorted into battery cells having a relatively large capacity and battery cells having a relatively small capacity, and the two adjacent battery cells are It is assumed that the battery cell has a combination of a battery cell having a relatively large capacity and a battery cell having a relatively small capacity.

  In the case of the above configuration, the two adjacent battery cells are a combination of a battery cell having a relatively large capacity and a battery cell having a relatively small capacity. By adopting such a combination, the discharge control as a whole of the plurality of battery cells can be performed efficiently, that is, as quickly as possible.

  That is, as described above, a plurality of battery cells are sorted into battery cells having relatively large capacity and battery cells having relatively small capacity, and battery cells having relatively large capacity and battery cells having relatively small capacity. By connecting the discharge circuit as a set, the time required for the discharge control of one battery cell is always shortened regardless of the usage status of the battery cell, and in any set, the other battery cell Since the time required for the discharge control becomes longer, it is possible to suppress variations in the time required for the discharge control for each set of battery cells. As a result, since the discharge control of each set of battery cells is completed at substantially the same timing, the discharge control can be performed efficiently for each set of battery cells, and the time required to equalize the voltages of all the battery cells. Can be shortened.

  According to the present invention, a resistor is provided for every two adjacent battery cells, the resistor is connected in parallel to one battery cell, and the discharge control of the one battery cell is performed. By connecting the other battery cell in parallel and performing discharge control of the other battery cell, it is possible to perform discharge control while reducing the number of resistors compared to the conventional configuration, and as a result, discharge control Can be done inexpensively.

  According to the second invention, the two battery cells to which the discharge circuit is connected are configured by a combination of a battery cell having a relatively large capacity and a battery cell having a relatively small capacity. Variations in the time required for the discharge control for each set can be suppressed, and as a result, the time required for the discharge control as a whole of the plurality of battery cells can be shortened.

  According to the third aspect of the invention, the first and second resistors are provided for each two adjacent battery cells, and the first resistor is connected in parallel to one of the battery cells, thereby discharging the one battery cell. The second resistor is connected in parallel to the other battery cell to perform discharge control of the other battery cell, and after the discharge control of any battery cell is completed, the first and second resistors Discharge control of the battery cells by connecting them in parallel to the battery cells for which discharge control has not been completed, and thereby controlling the discharge at high speed without increasing the number of resistors compared to the conventional configuration As a result, high-speed discharge control can be performed at low cost.

  According to the fourth invention, the two battery cells to which the discharge circuit is connected are configured by a combination of a battery cell having a relatively large capacity and a battery cell having a relatively small capacity. Variations in the time required for the discharge control for each set can be suppressed, and as a result, the time required for the discharge control as a whole of the plurality of battery cells can be shortened. In addition, the first and second resistors are shortened as much as possible for the first and second resistors to separately control discharge, and the first and second resistors are used for battery cells that originally require a long discharge control time. Both can be used to perform discharge control at high speed, and as a result, the time required for discharge control as a set of two battery cells can be shortened.

  According to the fifth invention, a resistor is provided for every two adjacent battery cells, the resistor is connected in parallel to one battery cell, and the discharge control of the one battery cell is performed. By connecting the battery to the other battery cell in parallel and performing discharge control of the other battery cell, it is possible to perform discharge control while reducing the number of resistors compared to the conventional configuration. Discharge control can be performed at low cost.

  According to the sixth invention, the two battery cells to which the discharge circuit is connected are composed of a combination of a battery cell having a relatively large capacity and a battery cell having a relatively small capacity. Variations in the time required for the discharge control for each set can be suppressed, and as a result, the time required for the discharge control as a whole of the plurality of battery cells can be shortened.

  According to the seventh invention, the first and second resistors are provided for every two adjacent battery cells, and the first resistor is connected in parallel to one of the battery cells, thereby discharging the one battery cell. The second resistor is connected in parallel to the other battery cell to perform discharge control of the other battery cell, and after the discharge control of any battery cell is completed, the first and second resistors Discharge control of the battery cells by connecting them in parallel to the battery cells for which discharge control has not been completed, and thereby controlling the discharge at high speed without increasing the number of resistors compared to the conventional configuration As a result, high-speed discharge control can be performed at low cost.

  According to the eighth invention, the two battery cells to which the discharge circuit is connected are configured by a combination of a battery cell having a relatively large capacity and a battery cell having a relatively small capacity. Variations in the time required for the discharge control for each set can be suppressed, and as a result, the time required for the discharge control as a whole of the plurality of battery cells can be shortened. In addition, the first and second resistors are shortened as much as possible for the first and second resistors to separately control discharge, and the first and second resistors are used for battery cells that originally require a long discharge control time. Both can be used to perform discharge control at high speed, and as a result, the time required for discharge control as a set of two battery cells can be shortened.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Embodiment 1 of the Invention
FIG. 2 is a circuit diagram schematically showing a part of an electric system of a hybrid electric vehicle including a battery cell control device according to an embodiment of the present invention.

  The hybrid electric vehicle includes an electric motor 11 as a drive source and a plurality of battery cells CL, CL,..., A battery cell unit 2 as a battery that is a power source of the electric motor 11, and the electric motor 11. An inverter 12 interposed between the battery cell unit 2, a battery cell control device 3 that performs voltage measurement of the battery cells CL, CL,... And voltage balance control described later, the electric motor 11, the inverter 12, and the battery And an HEV controller 10 that controls the cell control device 3.

  During the operation of the hybrid electric vehicle, the electric motor 11 is supplied with electric power from the battery cell unit 2 via the inverter 12 and functions as a drive source. On the other hand, during the deceleration of the hybrid electric vehicle, the electric motor 11 functions as a generator and charges the battery cell unit 2 via the inverter 12.

  The HEV controller 10 is configured to switch the drive source between the electric motor 11 and the engine (not shown) according to the running state, and to control the inverter 12 accordingly. The HEV controller 10 also controls the battery cell control device 3.

  The battery cell unit 2 is configured by connecting a plurality of battery cells CL, CL,... In series. Specifically, the battery cell unit 2 is configured by connecting m battery modules M, M,... Configured by connecting n battery cells CL, CL,. That is, the battery cell unit 2 is configured by connecting N (= n × m) battery cells CL, CL,... In series. In the present embodiment, the number of battery cells CL included in one battery module M is the same for each battery module M, but is not limited thereto.

Hereinafter, when the battery cell CL is referred to by distinguishing the arrangement position, the one end side of the series connection (the upper side in FIGS. 1 and 2) is the first, like “CL ₁ ”, and from the one end side of the series connection after “CL”. Named with a number. When the arrangement positions of the battery cells CL are not distinguished, they are simply referred to as “CL”. The battery module M is also referred to similarly.

The battery cell unit 2 configured in this way includes a positive electrode of the _first battery cell CL1 located on one end side in series connection, and a negative electrode of the _Nth battery cell CLN located on the other end side in series connection. Is connected to the inverter 12 so that the inverter 12 is connected in parallel.

  The battery cell control device 3 measures the measurement units 4, 4,... Provided for each battery module M, and the discharge circuits 6, 6,. .. And a control unit 5 connected to the discharge circuits 6, 6,. The measurement units 4, 4,... Are not essential as the battery cell control device 3 and may be provided separately from the battery cell control device 3.

  Here, the configuration of the measurement unit 4 will be described in detail with reference to FIG. FIG. 3 shows a circuit diagram of the measurement unit 4.

  The measurement unit 4 includes a capacitor C as a so-called flying capacitor, a voltage measurement circuit 45 for measuring the voltage of the capacitor C, a first switch circuit 41 for connecting the capacitor C and each battery cell CL, and the capacitor A second switch circuit 42 for connecting C and the voltage measurement circuit 45 and a third switch circuit 43 for discharging the capacitor C are provided.

The first switch circuit 41 functions as a sampling switch, and switches connection and disconnection between the battery cell CL to be measured and the capacitor C from the battery cells CL ₁ ,..., CL _n. . The first switch circuit 41 has an odd-side connection line La whose one end is connected to the positive electrodes of the odd-numbered battery cells CL ₁ , CL ₃ ,... (Or the negative electrodes of the even-numbered battery cells CL ₂ , CL ₄ ,. ₁ , La ₃ ,..., And even-numbered connection lines La having one ends connected to the positive electrodes of the even-numbered battery cells CL ₂ , CL ₄ ,... (Or the negative electrodes of odd-numbered battery cells CL ₁ , CL ₃ ,. _2, La _4, ... and odd-side connection lines _La 1, La _3, ... and odd-numbered common lines La + which is connected to one terminal of the capacitor C and the other end is connected to the even-side connection line _La 2, La _4, ... and the negative side common line La- other end of which is connected to the other terminal of the capacitor C is connected to the odd-side connection lines _La 1, La _3, ... and the even-side connection line _La 2, La ₄ For each of ... It has switches SWa ₁ , SWa ₂ ,... Provided.

Here, the subscript following “La” of the connection line and “SWa” of the switch corresponds to the subscript of the battery cell CL to which the positive electrode is connected. Note that the connection line and the switch connected to the negative electrode of the _nth battery cell CLn are referred to as “La _{n + 1} ” and “SWa _{n + 1} ”, respectively. That is, only n + 1 connection lines La and switches SWa are provided for n battery cells CL, CL,.

Each switch _SWa 1, SWa ₂ of the first switch circuit 41 thus configured, by switching a ... ON / OFF of the battery cell _CL 1, ..., a cell CL to be measured from the CL _n Connect to the capacitor C in parallel. For example, when the battery cell CL ₁ and the measurement object, the switch _SWa 1, SWa ₂ and ON, other switches _SWa 3, SWa _4, the ... to OFF. Further, for example, when the battery cell CL _{2 is} to be measured, the switches SWa ₂ and SWa ₃ are turned on, and the other switches SWa ₁ , SWa ₄ ,.

The odd-numbered battery cells CL ₁ , CL ₃ ,... Are connected in parallel to the capacitor C, and the even-numbered battery cells CL ₂ , CL ₄ ,. The sign of both terminals will be reversed.

The second switch circuit 42 functions as a transfer switch, and switches connection and disconnection between both terminals of the capacitor C and the two input terminals of the voltage measurement circuit 45. Specifically, a first connection line Lb ₁ that connects one terminal of the capacitor C and one input terminal of the voltage measurement circuit 45, and a first connection line Lb ₁ that connects the other terminal of the capacitor C and the other input terminal of the voltage measurement circuit 45. a second connection line Lb _2, has a first switch SWb ₁ provided on the first connection line Lb _1, a second and a switch SWb ₂ that is provided in the second connection line Lb _2. These first and second switch _SWb 1, while connecting the capacitor C and the voltage measurement circuit 45 by turning ON the SWb _2, the capacitor C and the voltage by turning OFF the first and second switch _SWb 1, SWb ₂ The connection with the measurement circuit 45 is disconnected.

The third switch circuit 43 functions as a reset switch and switches connection and disconnection of both terminals of the capacitor C. Specifically, the third switch circuit 43 includes first connection line Lb ₁ and the connected connection line Lc and a second connection line Lb _2, and a reset switch SWc provided on the connecting line Lc . By turning on the reset switch SWc, both terminals of the capacitor C are connected, and by turning off the reset switch SWc, the connection between both terminals of the capacitor C is disconnected.

The voltage measurement circuit 45 measures the voltage of the capacitor C and outputs a digital signal corresponding to the voltage. Specifically, the voltage measurement circuit 45 includes an operational amplifier OA and an A / D converter AD. One terminal and the other terminal of the capacitor C are connected to the two input terminals of the operational amplifier OA through connection lines Lb ₁ and Lb ₂ , respectively. The operational amplifier OA constitutes an operational amplifier circuit that amplifies and outputs the voltage of the capacitor C. The A / D converter AD converts the analog signal output from the operational amplifier OA into a digital signal and outputs it. An output terminal of the A / D converter AD that is an output terminal of the voltage measurement circuit 45 is connected to the control unit 5.

  Next, the configuration of the discharge circuit 6 will be described in detail with reference to FIG. FIG. 1 shows a circuit diagram of a discharge circuit.

  The discharge circuit 6 is for adjusting the voltage of the battery cell CL by discharging the battery cell CL. One discharge circuit 6 is provided for every two adjacent battery cells CL and CL.

As shown in FIG. 1, the discharge circuit 6 includes two switches SWe _i and SWe _{i + 1} connected in series with each other and connected in parallel to adjacent battery cells CL _i and CL _{i + 1} , and a battery having one end adjacent to each other. The resistor R _j is connected to a connection point between the cell CL _i and the battery cell CL _{i + 1} and the other end is connected to a connection point between the two switches SWe _i and Swe _{i + 1} . In other words, the discharge circuit 6 includes one resistor R _j provided for the adjacent battery cells CL _i and CL _{i + 1} and a connection state in which the resistor R _j is connected in parallel to one battery cell CL _i . connection state and the resistance R _j the one of the battery cells CL _i, CL i + ₁ switchable switch to the connection state not connected in parallel with respect to parallel connection of the resistor R _j with respect to the other battery cell CL i _{+ 1} and SWe _i and SWe _{i + 1} . That is, the switches SWe _i and SWe _{i + 1} constitute a switching unit that selectively connects the resistor R _j to each of the two adjacent battery cells CL _i and CL _{i + 1} in parallel.

When the switch SWe _i is ON and the switch SWe _{i + 1} is OFF, the discharge circuit 6 configured as described above causes the current of one battery cell CL _i to flow through the resistor R _j , whereby the one battery cell CL _i is discharged. The discharge circuit 6, and the switch SWe _i is in OFF, when the switch _{SWe i + 1} is ON, by flowing the other battery cell _{CL i + 1} of the current to the resistor _{R j,} to discharge the battery cell _{CL i + 1} of said other . Furthermore, when both the switches SWe _i and SWe _{i + 1} are OFF, the discharge circuit 6 does not cause the current of any battery cell CL _i or CL _{i + 1} to flow through the resistor R _j . In this manner, the discharge circuit 6 selectively discharges the battery cells CL _i and CL _{i + 1} by switching the switches SWe _i and SWe _{i + 1 on} and off. Switching of the switches SWe _i and SWe _{i + 1} is performed by the control unit 5.

Here, the battery cells CL ₁ , CL ₂ ,..., CL _N included in the battery cell unit 2 are basically battery cells having the same rated capacity. There is variation. In the present embodiment, the battery cells CL ₁ , CL ₂ ,..., CL _N are sorted into a group of battery cells having a relatively large capacity and a group of battery cells having a relatively small capacity. A battery cell CL having a relatively large capacity and a battery cell CL having a relatively small capacity are connected in series as a set. That is, a plurality of sets in which battery cells CL having relatively large capacity and battery cells CL having relatively small capacity are connected in series are connected in series to form the battery cell unit 2. One discharge circuit 6 is connected to each set of a battery cell CL having a relatively large capacity and a battery cell CL having a relatively small capacity. In the present embodiment, odd-numbered battery cells CL ₁ , CL ₃ ,... Are battery cells having a relatively large capacity, and even-numbered battery cells CL ₂ , CL ₄ ,. It is.

  The control unit 5 includes a CPU 51, a ROM 52, a RAM 53, and an I / F (interface) 54. The CPU 51 executes the control program stored in the ROM 52 and controls each measurement unit 4. The RAM 53 stores temporary data. For example, the measurement result of the voltage of each battery cell CL is stored for each battery cell CL. The ROM 52 and RAM 53 may be other storage means. The first to third switch circuits 41 to 43, the voltage measurement circuit 45, and the discharge circuits 6, 6,... Are connected to the I / F 54, and the CPU 51 controls them, and from the A / D converter AD. Get the output measurement result.

  The battery cell control device 3 configured as described above measures and monitors the voltage of each battery cell CL in order to prevent overdischarge and overcharge of each battery cell CL. Further, the battery cell control device 3 performs voltage balance control in order to discharge the battery cells CL, CL,... And make the voltages of the battery cells CL, CL,. Below, the measurement operation and voltage balance control of the voltage of the battery cell CL by the battery cell control device 3 will be described.

-Voltage measurement operation-
First, the control unit 5 controls the first switch circuit 41 to selectively turn on _{one of} the switches SWa ₁ , SWa ₂ ,..., And parallel one capacitor cell CL to be measured to the capacitor C. Connect to. Then, the capacitor C is charged by the battery cell CL for a predetermined charging time. This charging time is set to a time that is estimated that the capacitor C is fully charged when the capacitor C is charged by the battery cell CL via the first switch circuit 41.

Thus, after the capacitor C is charged by the battery cell CL to be measured for a predetermined charging time, the control unit 5 controls the first switch circuit 41 to disconnect the connection between the battery cell CL and the capacitor C. . Thereafter, the control unit 5 controls the second switch circuit 42 to turn on the first and second switches SWb ₁ and SWb _2, thereby connecting the capacitor C to the voltage measurement circuit 45. At this time, the reset switch SWc of the third switch circuit 43 is OFF. As a result, an analog signal corresponding to the voltage of the capacitor C is output from the operational amplifier OA of the voltage measurement circuit 45, and the A / D converter AD converts this into a digital signal and outputs it to the control unit 5. Thus, the voltage of the battery cell CL is measured through the capacitor C.

Thus, after measuring the voltage of the capacitor C, the control unit 5 controls the second switch circuit 42 to turn off the first and second switches SWb ₁ and SWb _2, thereby causing the capacitor C and the voltage measurement circuit 45 to be turned off. Disconnect from the. Subsequently, the control unit 5 discharges the electric charge accumulated in the capacitor C by controlling the third switch circuit 43 to turn on the reset switch SWc. Thereafter, the control unit 5 controls the third switch circuit 43 to turn off the reset switch SWc.

  Thereafter, the control unit 5 changes the battery cell CL to be measured, and sequentially measures the voltage of each battery cell CL by the same procedure.

-Voltage balance control-
Next, voltage balance control will be described with reference to FIGS. 4 shows a main flowchart of voltage balance control, FIG. 5 shows a flowchart of a discharge control subroutine during voltage balance control, and FIG. 6 shows a timing chart of discharge control. This voltage balance control is performed during parking, for example.

First, the control unit 5, in step Sa1, all the battery cells _{CL 1,} CL 2, ..., and measure the voltage CL _N. Then, the control unit 5, in step Sa2, the measured voltage value measured _{V 1,} V 2, and calculates an average voltage value _{V c} is an average value of ... _{V N.}

Next, the control unit 5, in step Sa3, the battery cell _{CL 1,} CL 2, ..., for each of the CL _N, (i-is 1~N integer) measured voltage value _V i the average of the voltage values _{V c} It is determined whether or not the absolute value of the difference is greater than a predetermined threshold value α. That is, it is determined whether or not there is a battery cell CL _{i in} which the measured voltage value V _i is greatly separated from the average voltage value V _c . In any battery cell CL _i , when the absolute value of the difference between the measured voltage value V _i and the average voltage value V _c is less than the threshold value α, the voltage of each battery cell CL does not vary so much. 5 ends the voltage balance control. On the other hand, when there is even one battery cell CL _i whose absolute value of the difference between the measured voltage value V _i and the average voltage value V _c is larger than the threshold value α, the control unit 5 proceeds to step Sa4 and executes discharge control. To do.

  The following discharge control is performed simultaneously in each of the discharge circuits 6, 6,.

Specifically, when the discharge control start timing arrives (t _{1 in} FIG. 6A), the control unit 5 determines from the measured voltage value V _i of each battery cell CL _i measured in step Sa1 in step Sb1. The minimum voltage value V _min is found, and in step Sb2, the switch SWe _i is turned on (t _{1 in} FIG. 6B). At this time, the switch SWe _{i + 1} is OFF (t _{1 in} FIG. 6C). Thus, when the switch SWe _i is turned on, the resistor R _j is connected to the battery cell CL _i in parallel, and the current of the battery cell CL _i flows to the resistor R _j . As a result, the SOC of the battery cell CL _i decreases (t _{1 in} FIG. 6D), and the voltage decreases accordingly.

At this time, the control unit 5 measures the voltage of the battery cell CL _i via the voltage measurement circuit 45, and the measured voltage value V _i of the battery cell CL _i is equal to the minimum voltage value V _min detected in step Sb1. It is determined whether or not (step Sb3). The control unit 5 repeats step Sb3 until the measured voltage value V _i matches the minimum voltage value V _min . On the other hand, when the measured voltage value V _i matches the minimum voltage value V _min (t _{2 in} FIG. 6D), the control unit 5 proceeds to step Sb4 and turns off the switch SWe _i (FIG. 6B). T ₂ ). That is, the control unit 5 discharges the battery cell CL _i until the measured voltage value V _i matches the minimum voltage value V _min .

In step Sb4, the control unit 5 further turns on the switch SWe _{i + 1} (t _{2 in} FIG. 6C). Thus, by the switch _{SWe i + 1} is ON, the result in the resistance _{R j} the battery cell _{CL i + 1} are connected in parallel, the current of the battery cell _{CL i + 1} flows to the resistor _{R j.} As a result, the SOC of the battery cell CL _{i + 1} decreases (t _{2 in} FIG. 6E), and the voltage decreases accordingly.

At this time, the control unit 5 measures the voltage of the battery cell CL _{i + 1} via the voltage measurement circuit 45, and the measured voltage value V _{i + 1 of} the battery cell CL _i is equal to the minimum voltage value V _min detected in step Sb1. It is determined whether or not (step Sb5). The control unit 5 repeats step Sb5 until the measured voltage value V _{i + 1} matches the minimum voltage value V _min . On the other hand, when the measured voltage value V _{i + 1} matches the minimum voltage value V _min (t _{3 in} FIG. 6E), the control unit 5 proceeds to step Sb6 and turns off the switch SWe _{i + 1} (FIG. 6C). T ₃ ). That is, the control unit 5 discharges the battery cell CL _{i + 1} until the measured voltage value V _{i + 1} matches the minimum voltage value V _min . Thereafter, the control unit 5 ends the discharge control (t _{3 in} FIG. 6A) and returns to the main flow.

In this way, the voltage of the two adjacent battery cells CL _i and CL _{i + 1} is adjusted to be the lowest voltage value V _min . The discharge control, the discharge circuit 6 is provided, the two adjacent battery cells _CL i, by performing for each _{CL i + 1,} all the battery cells _{CL 1,} CL 2, ..., voltage minimum voltage value of CL _N V _min is equalized.

In the present embodiment, the battery cell CL _i (CL _{i + 1} ) is discharged until the measured voltage value V _i (V _{i + 1} ) matches the minimum voltage value V _min , but the measured voltage value V _i (V _{i + 1} ). The battery cell CL _i (CL _{i + 1} ) may be discharged until the absolute value of the difference between the voltage and the minimum voltage value V _min is less than a predetermined threshold value.

Here, the two battery cells CL _i , CL _{i + 1} connected to the discharge circuit 6 have all the battery cells CL ₁ , CL ₂ ,..., CL _N included in the battery cell unit 2 having a relatively large capacity. Battery cells CL _i included in a group having a relatively large capacity and battery cells CL _{i + 1} included in a group having a relatively small capacity. Therefore, the time required for the discharge control differs between the battery cells CL _i and CL _{i + 1} .

That is, when the two battery cells CL _i and CL _{i + 1} are discharged from a state in which the voltage is balanced, that is, in a state in which the SOC is balanced, the SOCs of both the battery cells CL _i and CL _{i + 1} are reduced. because but small amount of change in SOC is for increasing or decreasing the same electrical quantity towards the relatively large battery cell CL _i, as a result, I found the following SOC of the capacitor is relatively large cell CL _i, capacity is relatively It becomes higher than the SOC of the small battery cell CL _{i + 1} .

In this state, when the discharge control is performed so that the voltages of the two battery cells CL _i and CL _{i + 1} become the minimum voltage value V _min , the SOC of the battery cell CL _i having a relatively large capacity is higher, and thus the decrease. The amount of voltage change to be performed (that is, the deviation between the measured voltage value V _i and the minimum voltage value V _min ) is larger in the battery cell CL _i having a relatively large capacity. In addition, since the battery cell CL _i having a relatively large capacity has a smaller SOC change amount with respect to the same increase / decrease in the amount of electricity, even if the voltage change amount to be reduced is the same, the capacity is relatively it is more amount of discharge to large cell CL _i, i.e., requires a longer discharge time. As a result, the time required for the discharge control is longer in the battery cell CL _i having a relatively large capacity than in the battery cell CL _{i + 1} having a relatively small capacity.

On the other hand, when the two battery cells CL _i and CL _{i + 1} are charged from a state in which the voltage is balanced, that is, from the state in which the SOC is balanced, the SOCs of both the battery cells CL _i and CL _{i + 1} are increased. The battery cell CL _i having a relatively large capacity has a smaller amount of change in the SOC with respect to the same increase / decrease in the amount of electricity. As a result, the SOC of the battery cell CL _{i + 1} having a relatively small capacity has a relative capacity. It is higher than the SOC of the large battery cell CL _i on.

From this state, when the discharge control is performed so that the voltages of the two battery cells CL _i and CL _{i + 1} become the minimum voltage value V _min , the SOC of the battery cell CL _{i + 1} having a relatively small capacity is higher, and thus the decrease. The amount of voltage change to be performed (that is, the deviation between the measured voltage value V _i and the minimum voltage value V _min ) is also larger in the battery cell CL _{i + 1} having a relatively small capacity. On the other hand, the battery cell CL _i having a relatively large capacity has a smaller change amount of the SOC with respect to the same increase / decrease in the amount of electricity, and therefore, when the change amount of the voltage to be reduced is the same, the capacity is reduced. it is more discharge of relatively large cell CL _i, i.e., requires a longer discharge time. In other words, the amount of change and the battery cell CL i of the voltage to be _reduced, CL i + by the difference in capacitance between _1, capacitance is relatively than larger cell CL battery it is capacity is relatively small _i cell CL i _{+ 1} the time required for the discharge control becomes long, volume the time required for discharge control than relatively small cell CL i _{+ 1} towards capacity is relatively large cell CL _i becomes longer.

Thus, the time required for the discharge control varies depending on the capacity of the battery cell. However, between the battery cell CL _i having a relatively large capacity and the battery cell CL _{i + 1} having a relatively small capacity, which one takes a longer time for discharge control depends on the usage situation (after discharge or after charge, etc. ) Depends on.

  Here, in order to shorten the time required for discharge control as a set of battery cells, it is preferable to combine battery cells having a short time required for discharge control. However, which of the battery cell having a relatively large capacity and the battery cell having a relatively small capacity has a short time required for the discharge control differs depending on the use situation. Therefore, for example, when battery cells having relatively small capacities are combined, the time required for the discharge control may be shortened in a certain use situation, but the time required for the turnover and the discharge control may be shortened in another use situation. May be longer. Moreover, when battery cells having a short time required for discharge control are combined, a combination of battery cells having a long time required for discharge control always occurs in the battery cell unit 2. Then, even if a certain battery cell set requires a short time for discharge control, another battery cell set always increases the time required for discharge control. Here, the time required for the discharge control of the battery cell unit 2 as a whole is determined by the time required for the battery cell set with the slowest discharge control. Therefore, if there is even one battery cell set that requires a long time for discharge control, the time required for the discharge control of the battery cell unit 2 as a whole becomes long.

  On the other hand, in this embodiment, a plurality of battery cells are grouped into those having a relatively large capacity and those having a relatively small capacity, and the capacities are relative to each other. A large battery cell and a battery cell having a relatively small capacity are combined into a set of two adjacent battery cells. By doing so, the time required for the discharge control of one battery cell is always shortened regardless of the use state of the battery cell, and the time required for the discharge control of the other battery cell is always increased. As a result, in the battery cell unit 2, the time required for the discharge control for each set of battery cells is made uniform. By doing so, it is possible to prevent the generation of a battery set that requires an extremely long time for the discharge control, and the discharge control can be completed at substantially the same timing for each battery cell set. Thus, by efficiently performing the discharge control for each set of battery cells, the time required for the discharge control of the battery cell unit 2 as a whole can be shortened.

  In addition, when looking at each set, when the time required for the discharge control of one battery cell is increased by combining a battery cell having a relatively large capacity and a battery cell having a relatively small capacity, Since the time required for the discharge control of the battery cells is shortened, the time required for the discharge control of the two adjacent battery cells can be shortened as compared with the combination in which the time required for the discharge control of both battery cells is increased. .

-Effect of Embodiment 1-
Therefore, according to the first embodiment, the resistor R _j is provided for each of the two adjacent battery cells CL _i and CL _{i + 1} , and the resistor R _j is connected in parallel to the one battery cell CL _i to be connected to the one battery cell. after discharge control of CL _i, by performing discharge control of the battery cell CL i _{+ 1} of said other by parallel connection of the resistor R _j to the other battery cell CL i _{+ 1,} as compared with the conventional configuration, the resistance Discharge control can be realized while reducing the number. That is, discharge control can be performed at low cost.

Further, the two battery cells CL _i and CL _{i + 1} to which the discharge circuit 6 is connected are constituted by a combination of a battery cell having a relatively large capacity and a battery cell having a relatively small capacity. Variation in time required for discharge control for each set of _i and CL _{i + 1} can be suppressed. As a result, although the discharge control of most battery cell sets is completed, the discharge control of some battery cell sets is not completed, so the discharge control of the battery cell unit 2 as a whole is long-term. Can be prevented, and the time required for the discharge control of the battery cell unit 2 as a whole can be shortened.

<< Embodiment 2 of the Invention >>
Subsequently, Embodiment 2 of the present invention will be described. The battery cell control device according to the second embodiment is different from the first embodiment in the configuration of the discharge circuit 206. Therefore, the same configurations as those of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted, and different portions will be mainly described.

Exemplary discharge circuit 206 according to Embodiment 2, as shown in FIG. 7, the battery cell _CL i adjacent and mutually connected in series, _{CL i + 1} 2 one first switch _SWe i connected in parallel with, _{SWe i + 1} Two second switches SWf _i , SWf _{i + 1} connected in series to each other and further connected in parallel to the battery cells CL _i , CL _{i + 1} , one end adjacent battery cell CL _i and battery cell CL _{i + 1.} A first resistor Ra _j that is connected to a connection point between the first switch SWe _i and the first switch SWe _{i + 1} , and has one end adjacent to the battery cell CL _i and the battery. A second resistor Rb _j connected to a connection point between the cells CL _{i + 1} and having the other end connected to a connection point between the second switch SWf _i and the second switch SWf _{i + 1.} The In other words, the discharge circuit 206 includes the first and second resistors Ra _j and Rb _j provided for the adjacent battery cells CL _i and CL _{i +} 1 and the first resistor Ra _j as one of the battery cells CL _i. And a connection state in which the first resistor Ra _j is connected in parallel to the other battery cell CL _{i + 1} and the first resistor Ra _j to any of the battery cells CL _i and CL _{i + 1} . The first switches SWe _i and SWe _{i + 1} that can be switched to a connection state that is not connected in parallel, and the connection state that connects the second resistor Rb _j to one battery cell CL _i in parallel and the second resistor Rb _j A second switch SWf _i that can be switched between a connection state in parallel connection to the other battery cell CL _{i + 1} and a connection state in which the first resistor Rb _j is not connected in parallel to any battery cell CL _i , CL _{i + 1} . S and f _{i + 1,} the has. That is, the first switch SWe _i , SWe _{i + 1} selectively connects the first resistor Ra _j to the two adjacent battery cells CL _i , CL _{i + 1} in parallel with the second switch SWf. _i and SWf _{i + 1} constitute a second switching unit that selectively connects the second resistor Rb _j to each of the two adjacent battery cells CL _i and CL _{i + 1} in parallel.

The first and second resistors Ra _j and Rb _j have the same resistance value. However, the first and second resistors Ra _j and Rb _j may have different resistance values.

When the first switch SWe _i is ON and the first switch SWe _{i + 1} is OFF, the discharge circuit 206 configured in this manner allows the current of one battery cell CL _i to flow through the first resistor Ra _j . discharging one of the battery cells CL _i said. In addition, when the first switch SWe _i is OFF and the first switch SWe _{i + 1} is ON, the discharge circuit 206 causes the current of the other battery cell CL _{i + 1} to flow through the first resistor Ra _j so that the other battery The cell CL _{i + 1} is discharged. Furthermore, when the first switches SWe _i and SWe _{i + 1} are both OFF, the discharge circuit 206 does not allow the current of any of the battery cells CL _i and CL _{i + 1} to flow through the first resistor Ra _j . In parallel with this, when the second switch SWf _i is ON and the second switch SWf _{i + 1} is OFF, the discharge circuit 206 causes the current of one battery cell CL _i to flow through the second resistor Rb _j , thereby discharging one of the battery cells CL _i. In addition, when the second switch SWf _i is OFF and the second switch SWf _{i + 1} is ON, the discharge circuit 206 causes the current of the other battery cell CL _{i + 1} to flow through the second resistor Rb _j , so that the other battery The cell CL _{i + 1} is discharged. Furthermore, when the second switches SWe _i and SWe _{i + 1} are both OFF, the discharge circuit 206 does not cause the current of any of the battery cells CL _i and CL _{i + 1} to flow through the second resistor Rb _j . Thus, the discharge circuit 206 discharges the battery cells CL _i and CL _{i + 1} by switching the first switches SWe _i and SWe _{i + 1} and the second switches SWf _i and SWf _{i + 1 on} and off. Switching of the first switches SWe _i and SWe _{i + 1} and the second switches SWf _i and SWf _{i + 1} is performed by the control unit 5.

Similarly to the first embodiment, the two battery cells CL and CL connected to the discharge circuit 206 have a relative capacity to all the battery cells CL ₁ , CL ₂ ,..., CL _N included in the battery cell unit 2. The battery cells CL included in the group having a relatively large capacity and the battery cells CL included in the group having a relatively small capacity are grouped into those having a relatively large capacity and those having a relatively small capacity. It is configured. In the present embodiment, odd-numbered battery cells CL ₁ , CL ₃ ,... Are battery cells having a relatively large capacity, and even-numbered battery cells CL ₂ , CL ₄ ,. It is.

The discharge control using the discharge circuit 206 configured as described above includes a normal mode in which the battery cells CL _i and CL _{i + 1} are separately controlled by the first and second resistors Ra _j and Rb _j , and any one of the battery cells. CL _i (CL _{i + 1} ) has a high-speed mode in which discharge control is performed by both the first and second resistors Ra _j and Rb _j . First, discharge control of the battery cells CL _i and CL _{i + 1} is performed in the normal mode. As soon as the discharge control of one of the battery cells CL _i (CL _{i + 1} ) is completed, the discharge control of the battery cell CL _{i + 1} (CL _i ) for which the discharge control is not completed is performed in the high-speed mode.

  Hereinafter, this discharge control will be described in detail with reference to FIGS. FIG. 8 shows a flowchart of a discharge control subroutine according to the second embodiment, and FIG. 9 shows a timing chart of the discharge control. This discharge control is performed simultaneously in each of the discharge circuits 206, 206,.

First, when the start timing of the discharge control arrives (t _{1 in} FIG. 9A), the control unit 5 selects from the measured voltage values V _i of the respective battery cells CL _i measured in the voltage measurement in step Sc1. The minimum voltage value V _min is found, and in step Sc2, the first switch SWe _i and the second switch SWf _{i + 1} are turned on (t _{1 in} FIGS. 9B and 9E). At this time, the first switch SWe _{i + 1} and the second switch SWf _i are OFF (t _{1 in} FIGS. 9C and 9D). Thus, by the first switch SWe _i is ON, the result in the first resistor Ra _j is connected in parallel to the battery cell CL _i, the current of the battery cell CL _i flows through the first resistor Ra _j together, since the second switch _{SWf i + 1} is oN, the second resistor Rb _j is to be connected in parallel to the battery cell _{CL i + 1,} the current of the battery cell _{CL i + 1} flows through the second resistor Rb _j . As a result, the SOC of the battery cell CL _i decreases (t _{1 in} FIG. 9F), and the voltage decreases accordingly, and the SOC of the battery cell CL _{i + 1} decreases (t _{1 in} FIG. 9G). ) The voltage will drop accordingly.

At this time, the control unit 5, the battery cell _CL i via a voltage measuring circuit 45, _{CL i + 1} voltage is measured, the minimum voltage value V measured voltage value _{V i} of the battery cell CL _i is detected in step Sc1 It is determined whether or not it is equal to _min , or whether or not the measured voltage value V _{i + 1 of the} battery cell CL _{i + 1} is equal to the minimum voltage value V _min detected in step Sc1 (step Sc3). The control unit 5 repeats step Sc3 until either _one of the measured voltage values V _i and V _{i + 1} matches the minimum voltage value V _min . Then, the control unit 5, when the measured voltage value _{V i} matches the minimum voltage value _{V min} earlier, the process proceeds to step Sc4, the measured voltage value _{V i + 1} coincides with the minimum voltage value _{V min} earlier, to step Sc7 move on.

In step Sc4, the control unit 5 turns off the first switch SWe _i to end the discharge control of the battery cell CL _i (t _{2 in} FIG. 9B). In this way, the control unit 5 discharges the battery cell CL _i until the measured voltage value V _i matches the minimum voltage value V _min (t _{2 in} FIG. 9F). At the same time, the control unit 5 turns on the first switch SWe _{i + 1} in order to discharge the other battery cell CL _{i + 1} for which the discharge control has not been completed yet more quickly (t _{2 in} FIG. 9C). By doing so, not only the second resistor Rb _j but also the first resistor Ra _j is connected in parallel to the battery cell CL _{i + 1} . As a result, the more current flows from the battery cell CL i _{+ 1,} can be discharged faster cell CL i _{+ 1.} As a result, the SOC of the battery cell CL _{i + 1} rapidly decreases (t _{2 in} FIG. 9G), and the voltage also rapidly decreases accordingly.

Then, in step Sc5, the control unit 5 determines whether or not the measured voltage value V _{i + 1 of} the battery cell CL _{i + 1} measured via the voltage measuring circuit 45 is equal to the minimum voltage value V _min detected in step Sc1. To do. Control unit 5, while the measured voltage value _{V i + 1} is repeated steps Sc5 until it coincides with the minimum voltage value _{V min,} when the measured voltage value _{V i + 1} coincides with the minimum voltage value _{V min,} the process proceeds to step Sc6.

In step Sc6, the control unit 5 turns off the first switch SWe _{i + 1} and the second switch SWf _{i + 1} to end the discharge control of the battery cell CL _{i + 1} (t _{3 in} FIGS. 9C and 9E). ). As described above, the control unit 5 discharges the battery cell CL _{i + 1} until the measured voltage value V _{i + 1} matches the minimum voltage value V _min (t _{3 in} FIG. 9G). Thereafter, the control unit 5 ends the discharge control (t _{3 in} FIG. 9A) and returns to the main flow.

On the other hand, if the measured voltage value V _{i + 1} previously matches the minimum voltage value V _min in step Sc3, in step Sc7, the control unit 5 sets the second switch to end the discharge control of the battery cell CL _{i + 1.} Set SWf _{i + 1} to OFF. In this way, the control unit 5 discharges the battery cell CL _{i + 1} until the measured voltage value V _{i + 1} matches the minimum voltage value V _min . At the same time, the control unit 5, in order to discharge still discharge control is not completed other battery cell CL _i further quickly, to ON and the second switch SWf _i. By doing so, not only the first resistor Ra _j but also the second resistor Rb _j is connected in parallel to the battery cell CL _i . As a result, more current flows out from the battery cell CL _i , and the battery cell CL _i can be discharged faster. As a result, the SOC is rapidly reduced in the battery cell CL _i, accordingly, voltage rapidly decreases.

Then, in step Sc8, the control unit 5 determines whether or not the measured voltage value V _i of the battery cell CL _i measured via the voltage measuring circuit 45 is equal to the minimum voltage value V _min detected in step Sc1. To do. Control unit 5, while the measured voltage value _{V i} is repeated step Sc8 until it coincides with the minimum voltage value _{V min,} when the measured voltage value _{V i} matches the minimum voltage value _{V min,} the process proceeds to step Sc9.

In step Sc9, the control unit 5, in order to end the discharge control of the battery cell CL _i, the first switch SWe _i and the second switch SWf _i to OFF. In this way, the control unit 5 discharges the battery cell CL _i until the measured voltage value V _i matches the minimum voltage value V _min . Thereafter, the control unit 5 ends the discharge control and returns to the main flow.

In this way, the voltage of the two adjacent battery cells CL _i and CL _{i + 1} is adjusted to be the lowest voltage value V _min . The discharge control, the discharge circuit 206 is provided, adjacent two battery cells _CL i, by performing for each _{CL i + 1,} all the battery cells _{CL 1,} CL 2, ..., voltage minimum voltage value of CL _N V _min is equalized.

Here, the two battery cells CL _i , CL _{i + 1} connected to the discharge circuit 206 have all the battery cells CL ₁ , CL ₂ ,..., CL _N included in the battery cell unit 2 having a relatively large capacity. Battery cells CL _i included in a group having a relatively large capacity and battery cells CL _{i + 1} included in a group having a relatively small capacity. Therefore, the battery cell unit 2 as a whole can equalize the time required for the discharge control for each set of the battery cells CL _i and CL _{i + 1} , and can efficiently perform the discharge control. As a result, the time required for the discharge control as a whole of the battery cell unit 2, and hence the time required for the voltage balance control can be shortened.

That is, as described above, the battery cells CL ₁ , CL ₂ ,... Included in the battery cell unit 2 have different capacities, and the time required for the discharge control of each battery cell is affected by the capacity. The time required for discharge control differs for each battery cell CL. Here, in order to shorten the time required for discharge control as a set of battery cells, it is preferable to combine battery cells having a short time required for discharge control. However, which of the battery cell having a relatively large capacity and the battery cell having a relatively small capacity has a short time required for the discharge control differs depending on the use situation. Therefore, for example, when battery cells having relatively small capacities are combined, the time required for the discharge control may be shortened in a certain use situation, but the time required for the turnover and the discharge control may be shortened in another use situation. May be longer. Moreover, when battery cells having a short time required for discharge control are combined, a combination of battery cells having a long time required for discharge control always occurs in the battery cell unit 2. Then, even if a certain battery cell set requires a short time for discharge control, another battery cell set always increases the time required for discharge control. Here, the time required for the discharge control of the battery cell unit 2 as a whole is determined by the time required for the battery cell set with the slowest discharge control. Therefore, if there is even one battery cell set that requires a long time for discharge control, the time required for the discharge control of the battery cell unit 2 as a whole becomes long.

On the other hand, in this embodiment, a plurality of battery cells are grouped into those having a relatively large capacity and those having a relatively small capacity, and the capacity is relatively large. The battery cell and the battery cell having a relatively small capacity are combined to form a set of battery cells CL _i and CL _{i + 1} to which the discharge circuit 206 is connected. By doing so, the time required for the discharge control of one battery cell is always shortened regardless of the use state of the battery cell, and the time required for the discharge control of the other battery cell is always increased. As a result, in the battery cell unit 2, the time required for the discharge control for each set of battery cells is made uniform. By doing so, it is possible to prevent the generation of a battery set that requires an extremely long time for the discharge control, and the discharge control can be completed at substantially the same timing for each battery cell set. Thus, by efficiently performing the discharge control for each set of battery cells, the time required for the discharge control of the battery cell unit 2 as a whole can be shortened.

And, as described above, the discharge control using the discharge circuit 206 according to the present embodiment includes the normal mode in which the battery cells CL _i and CL _{i + 1} are separately controlled by the first and second resistors Ra _j and Rb _j , and Since the battery cell CL _i (CL _{i + 1} ) has a high-speed mode in which discharge control is performed by both the first and second resistors Ra _j and Rb _j , the battery cell having a relatively large capacity and the capacity Even in a configuration in which the discharge circuit 206 is connected in combination with relatively small battery cells, each set of discharge control can be performed quickly.

  That is, since either one of the two battery cells requires a short time for the discharge control, even if the discharge control is performed in the normal mode, the discharge control of either one of the battery cells is completed early. As a result, it is possible to shorten the time for executing the normal mode and quickly shift to the high speed mode in which the discharge control is performed at high speed. The other battery cell of the two battery cells is inherently long in discharge control, but since the discharge control is performed by switching from the normal mode to the high-speed mode from the middle, the high-speed mode is effective. The discharge control can be completed. In this way, the time of the normal mode is shortened as much as possible, and the battery cell that originally takes a long time for the discharge control is subjected to the discharge control in the high speed mode at a high speed, thereby combining the two battery cells. As a result, the time required for the discharge control can be shortened.

-Effect of Embodiment 2-
Therefore, according to the second embodiment, the first and second resistors Ra _j and Rb _j are provided for every two adjacent battery cells CL _i and CL _{i + 1} , and the first resistor Ra _{j is connected} to one of the battery cells CL _i. connected in parallel so it performs the discharge control of one of the battery cells CL _i said, the second resistance Rb _j by parallel connection to the other battery cells CL i _{+ 1} performs the discharge control of the battery cell CL i _{+ 1} of the other one of the, After the discharge control of any battery cell CL _i (CL _{i + 1} ) is completed, the first and second resistors Ra _j and Rb _j are transferred to the battery cell CL _{i + 1} (CL _i ) that has not completed the discharge control. by performing discharge control of each be connected in parallel battery cell _{CL i + 1 (CL i)} , conventionally one battery cell _{CL i (CL} i _{+ 1)} of the discharge control to complete and embarrassed have resistance _Ra j ( The b _j) by using the discharge control of the other battery cell _{CL i + 1 (CL i)} , can be performed without increasing the number of resistance than the conventional configuration, the discharge control at high speed. As a result, high-speed discharge control can be performed at low cost.

Further, the two battery cells CL _i and CL _{i + 1} to which the discharge circuit 206 is connected are constituted by a combination of a battery cell having a relatively large capacity and a battery cell having a relatively small capacity. Variation in time required for discharge control for each set of _i and CL _{i + 1} can be suppressed. As a result, although the discharge control of most battery cell sets is completed, the discharge control of some battery cell sets is not completed, so the discharge control of the battery cell unit 2 as a whole is long-term. Can be prevented, and the time required for the discharge control of the battery cell unit 2 as a whole can be shortened.

Furthermore, as described above, the discharge control using the discharge circuit 206 includes the normal mode in which the battery cells CL _i and CL _{i + 1} are separately controlled by the first and second resistors Ra _j and Rb _j , and any one of the battery cells. Since it has a high-speed mode in which discharge control of CL _i (CL _{i + 1} ) is performed by both the first and second resistors Ra _j and Rb _j, a battery cell having a relatively large capacity and a battery having a relatively small capacity Even when the discharge circuit 206 is connected in combination with cells, the normal mode time is shortened as much as possible, and discharge control is performed in a high speed mode for battery cells that originally require a long discharge control time. By performing at a high speed, each group of discharge control can be performed quickly.

<< Other Embodiments >>
The present invention may have the following configurations for the embodiments.

That is, in the first embodiment, by providing two switches SWe _i and SWe _{i + 1} , the resistor R _j is selectively connected in parallel to each of the two adjacent battery cells CL _i and CL _{i + 1.} However, it is not limited to this. For example, a first terminal provided at the other end of the resistor connected at one end to the connection point between the battery cell CL _i and the battery cell CL _{i + 1,} and a connection line connected at the one end to the positive electrode side of the battery cell CL _i A second terminal provided at the other end, a third terminal provided at the other end of the connection line connected at one end to the negative electrode side of the battery cell CL _{i + 1} , and connected to both the battery cells CL _i and CL _{i + 1} A fourth terminal that is not connected, a connection state that connects the first terminal and the second terminal, a connection state that connects the first terminal and the third terminal, and a connection between the first terminal and the fourth terminal. A switch that switches according to the connection state may be used. That is, any configuration can be adopted as long as the resistor R _j is selectively connected in parallel to each of the two adjacent battery cells CL _i and CL _{i + 1} .

Similarly, in the second embodiment, the first switch SWe _i , SWe _{i + 1} and the second switch SWf _i , SWf _{i + 1} are not limited, and the first resistor Ra _j is connected to two adjacent battery cells CL _i , CL. with selectively connected in parallel to each of the _{i + 1,} 2 one battery cell CL i adjacent the second resistor Rb _j, if selectively connected in parallel to configure for each CL i + _1, any configuration Can be adopted.

  In addition, the above embodiment is an essentially preferable illustration, Comprising: It does not intend restrict | limiting the range of this invention, its application thing, or its use.

  As described above, the present invention is useful for a battery cell control apparatus and a control method for performing discharge control so that the voltage of each battery cell is uniform among a plurality of battery cells connected in series.

It is a circuit diagram of the discharge circuit concerning Embodiment 1 of the present invention. It is a circuit diagram which shows a part of electric system of the hybrid vehicle carrying a battery cell control apparatus. It is a circuit diagram of a measurement unit. It is a flowchart of voltage balance control. It is a flowchart of discharge control. It is a timing chart of discharge control. 6 is a circuit diagram of a discharge circuit according to Embodiment 2. FIG. 6 is a flowchart of discharge control according to the second embodiment. 6 is a timing chart of discharge control according to the second embodiment.

Explanation of symbols

CL Battery cell R Resistance (resistor)
Ra first resistor (first resistor)
Rb second resistor (second resistor)
3 Battery cell control device 6 Discharge circuit 206 Discharge circuit

Claims (8)

A plurality of battery cells connected in series, and a discharge circuit connected to the battery cell for discharging the battery cell, the voltage for each battery cell is made uniform by controlling the discharge circuit A battery cell control device that performs discharge control as follows:
The discharge circuit has a resistor provided for every two adjacent battery cells, and is configured to selectively connect the resistor to each of the two battery cells in parallel.
The discharge control of one battery cell is performed by connecting the resistor to one battery cell in parallel, and then the discharge of the other battery cell is performed by connecting the resistor to the other battery cell in parallel. A control device for a battery cell, which is configured to perform control. The battery cell control device according to claim 1,
The plurality of battery cells are sorted into a battery cell having a relatively large capacity and a battery cell having a relatively small capacity,
The two adjacent battery cells are configured by a combination of a battery cell having a relatively large capacity and a battery cell having a relatively small capacity. A plurality of battery cells connected in series, and a discharge circuit connected to the battery cell for discharging the battery cell, the voltage for each battery cell is made uniform by controlling the discharge circuit A battery cell control device that performs discharge control as follows:
The discharge circuit includes first and second resistors provided for every two adjacent battery cells, and selectively connects the first resistor to each of the two adjacent battery cells in parallel. The second resistor is selectively connected in parallel to each of the two adjacent battery cells,
Discharge control of the two battery cells is performed separately by connecting the first resistor in parallel with one of the battery cells and connecting the second resistor in parallel with the other battery cell. After discharge control of one of the cells is completed, discharge control of the battery cell is performed by connecting the first and second resistors in parallel to the battery cell that has not completed discharge control. A control device for a battery cell, characterized by being configured to perform. In the battery cell control device according to claim 3,
The plurality of battery cells are sorted into a battery cell having a relatively large capacity and a battery cell having a relatively small capacity,
The two adjacent battery cells are configured by a combination of a battery cell having a relatively large capacity and a battery cell having a relatively small capacity. A battery cell control method for performing discharge control so that the voltage of each battery cell is uniform in a plurality of battery cells connected in series,
A step of performing discharge control of one of the battery cells by connecting a resistor provided for every two adjacent battery cells in parallel to one of the battery cells; and
A step of performing discharge control of the other battery cell by connecting the resistor in parallel to the other battery cell after the discharge control of the one battery cell is completed. Control method. In the battery cell control method according to claim 5,
The plurality of battery cells are sorted into a battery cell having a relatively large capacity and a battery cell having a relatively small capacity,
The two adjacent battery cells are configured by a combination of a battery cell having a relatively large capacity and a battery cell having a relatively small capacity. A battery cell control method for performing discharge control so that the voltage of each battery cell is uniform in a plurality of battery cells connected in series,
Of the first and second resistors provided for every two adjacent battery cells, the first resistor is connected in parallel to one of the battery cells, and the second resistor is connected in parallel to the other battery cell. Separately performing discharge control of the two battery cells by connecting;
After the discharge control of any one of the two battery cells is completed, both the first and second resistors are connected in parallel to the battery cell for which the discharge control has not been completed. And a step of controlling the discharge of the battery cell. In the battery cell control method according to claim 7,
The plurality of battery cells are sorted into a battery cell having a relatively large capacity and a battery cell having a relatively small capacity,
The two adjacent battery cells are configured by a combination of a battery cell having a relatively large capacity and a battery cell having a relatively small capacity.

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