JP6647662B1 - Battery pack unit and cell balance adjustment method - Google Patents

Abstract

An object of the present invention is to provide a battery pack unit and a cell balance adjusting method capable of performing maintenance while suppressing a decrease in battery life. A battery pack unit according to the present invention includes a battery pack including a battery cell group consisting of first to nth (n is an integer of 2 or more) battery cells connected in series, When the total voltage obtained by combining the cell voltages, which are the voltages of the first to n-th battery cells, is higher than a predetermined balance voltage, an instruction is given to discharge the battery cell group until the total voltage falls below the balance voltage. A discharge processing unit that outputs a discharge control signal, which is a signal to perform the operation, and a difference between the cell voltages of the first to nth battery cells after the total voltage falls below the balance voltage due to the discharge of the battery cell group by the discharge processing unit. A charge processing unit that outputs a charge control signal that is a signal for instructing the battery pack to be charged by applying a balance voltage until the battery pack becomes smaller than the tolerance. [Selection] Figure 2

Description

  The present invention relates to a battery pack unit including a plurality of battery cells, and a cell balance adjustment method for equalizing the voltage of each battery cell.

  At present, a battery pack unit including a plurality of battery packs connected in series has been commercialized as a power supply for a motor mounted on an electric vehicle, a hybrid vehicle, an electric assist bicycle, or the like. Each battery pack has a structure in which rechargeable secondary batteries such as a lead storage battery, a nickel hydride battery, and a lithium ion battery are connected in series.

  By the way, it is known that the performance of a secondary battery is deteriorated by using or leaving it for a long time, and the progress of the deterioration is not uniform. Therefore, the deterioration state of a plurality of battery packs connected in series becomes uneven due to long-term use. Therefore, when a plurality of battery packs in such a state are charged, some of the battery packs are in a fully charged state, and other battery packs are in an overdischarged or overcharged state, and may not be usable. was there. In addition, when charging one battery pack, some cells in the battery pack are fully charged, other cells are in an overdischarged or overcharged state, and the battery pack becomes unusable. There was a risk of becoming.

  Therefore, a reproduction processing method has been proposed in which a plurality of battery modules (corresponding to a battery pack) in such a state are restored to the state at the time of shipment (for example, see Patent Document 1).

  In the regeneration process, the discharge voltage of each battery module is temporarily adjusted to be equal to or lower than the discharge completion voltage value by forcibly discharging the plurality of battery modules until the respective discharge voltages become equal to or lower than the predetermined discharge completion voltage value. Thereafter, the battery is charged to reach a fully charged state.

No. 2017/046900

  By the way, in the maintenance of the battery by the above-described regeneration processing, the voltage of each of the battery modules can be once adjusted to a predetermined voltage value or less by discharging a plurality of battery modules. However, when there is a large variation in the voltage of each battery module immediately before the discharge is performed, a large difference occurs in the voltage of each battery module after the discharge is completed. Therefore, if the battery modules are charged to reach a fully charged state after the end of the discharge, some of the battery modules may be overcharged or overdischarged, which may shorten the battery life. was there.

  Therefore, an object of the present invention is to provide a battery pack unit and a cell balance adjustment method that can perform maintenance while suppressing a decrease in battery life, for example.

  A battery pack unit according to the present invention includes: a battery pack including a battery cell group including first to nth (n is an integer of 2 or more) battery cells connected in series; When the total voltage obtained by combining the cell voltages, which are the voltages of the nth battery cells, is greater than a predetermined balance voltage, an instruction is given to discharge the battery cell group until the total voltage falls below the balance voltage. A discharge processing unit that outputs a discharge control signal that is a signal to perform, after the total voltage falls below the balance voltage due to discharge of the battery cell group by the discharge processing unit, the first to n-th battery cells Until the difference between the cell voltages becomes smaller than the tolerance, a charge processing unit that outputs a charge control signal that is a signal that instructs the battery pack to be charged by applying the balance voltage, Including.

Further, the cell balance adjusting method according to the present invention may be configured such that each of the battery cells of the battery pack includes a battery cell group including first to nth (n is an integer of 2 or more) battery cells connected in series. A cell balance adjusting method for adjusting a voltage, wherein the total voltage obtained by combining cell voltages that are voltages of the first to nth battery cells of the battery cell group is lower than a predetermined balance voltage. A discharging step of discharging the battery cell group, and charging the battery pack by applying the balance voltage until the difference between the cell voltages becomes smaller than an allowable difference after the total voltage falls below the balance voltage. Charging step.

  In short, in the battery pack unit and the cell balance adjusting method described above, the following discharge process and charge process are sequentially performed as maintenance of the battery pack unit, so that the cell voltage of each battery cell in a battery cell group including a plurality of battery cells is adjusted. Adjust the cell balance to equalize.

  That is, first, the battery cell group is forcibly discharged until the total voltage obtained by combining the cell voltages of the plurality of battery cells falls below the predetermined balance voltage (discharge processing). Then, the battery cell group is charged with the above-mentioned balance voltage until the difference between the cell voltages of the battery cells included in the battery cell group becomes smaller than the tolerance (charging process).

  Therefore, according to the battery pack unit and the cell balance adjustment described above, the cell voltages of the plurality of battery cells included in the battery pack are equalized by only the discharging process performed on the battery pack. Can be reduced. This reduces the number of overcharged battery cells and the duration of the overcharged state during charging to reach the fully charged state of the battery pack, which is performed after the cell balance adjustment is completed. Therefore, it is possible to suppress a decrease in battery life.

  In addition, a battery pack unit according to the present invention includes a battery pack including a battery cell group including first to nth (n is an integer of 2 or more) battery cells connected in series; When the total voltage obtained by combining the cell voltages, which are the voltages of the first to n-th battery cells, is greater than a predetermined balance voltage, a discharge that discharges the battery cell group until the total voltage falls below the balance voltage. A processing unit, and when the total voltage falls below the balance voltage due to the discharge of the battery cell group by the discharge processing unit, the balance is applied to the battery pack until the difference between the cell voltages becomes smaller than an allowable difference. A charge processing unit that outputs a charge control signal that is a signal for instructing charging by applying a voltage.

  According to such a battery pack unit, when sequentially performing the above-described discharge processing and charging processing, in this discharge processing, the electronic cell group is discharged by the discharge processing unit included in the battery pack unit. Therefore, it is not necessary to use an electronic load device or the like that discharges the electronic cell group at the time of maintenance work of the battery pack unit, so that maintenance can be performed with an inexpensive system configuration.

  Still another battery pack unit according to the present invention includes first to nth battery cell units each including a battery cell group including first to nth (n is an integer of 2 or more) battery cells connected in series. r (r is an integer of 2 or more) and a voltage obtained by combining voltages generated by the first to r-th battery packs is output as a total voltage, and the first to r-th batteries are output. An external power supply terminal for receiving a voltage for charging the pack, and if the total voltage is greater than a predetermined balance voltage, the battery pack is included in the first to r-th battery packs until the total voltage falls below the balance voltage. A discharge processing unit that outputs a discharge control signal that is a signal instructing to discharge all the battery cell groups to be discharged, and after the total voltage falls below the balance voltage due to the discharge of the battery cell group by the discharge processing unit. And said A signal indicating that the balance voltage is applied to the external power supply terminal and charged until the difference between the cell voltages of all the battery cells included in the first to r-th battery packs becomes smaller than an allowable difference. And a charge processing unit that outputs a charge control signal.

  In short, in such a battery pack unit, at the time of its own maintenance, by performing the following discharging process and charging process in order, the cell balance adjustment for equalizing the cell voltage of each battery cell included in the plurality of battery packs is performed. Do.

  That is, first, the plurality of battery packs are forcibly discharged until the total voltage obtained by combining the cell voltages of the battery cells included in the plurality of battery packs falls below the predetermined balance voltage (discharge processing). Then, until the difference between the cell voltages of the battery cells included in the plurality of battery packs becomes smaller than the tolerance, the plurality of battery packs are charged with the above-described balance voltage via the external power supply terminal (charging process). .

  According to this battery pack unit, it is possible to reduce the difference between the cell voltages of the battery cells included in each battery pack, as compared with the case where the voltage is equalized in each battery pack only by performing the discharge process performed on the plurality of battery packs. . This allows the number of battery cells to be in an overcharged state, and the period during which the overcharged state is maintained, at the time of charging each battery pack to be fully charged, which is performed after the cell balance adjustment is completed. Since it can be reduced, it is possible to suppress a decrease in battery life.

FIG. 2 is a block diagram showing a configuration of a battery pack unit 100 according to the present invention. FIG. 3 is a circuit diagram showing an internal configuration of a CU1 extracted from the cell controllers CU1 to CUr. FIG. 2 is a block diagram illustrating an example of a system configuration constructed when performing maintenance on the battery pack unit. 5 is a flowchart illustrating a procedure of a maintenance process performed by a CPU 20. It is a flowchart which shows an example of the procedure of a cell balance adjustment process. It is a figure showing an example of the discharge characteristic of a battery cell. It is a figure showing an example of the state of the cell voltage of each battery cell B1-Bn contained in each battery pack immediately before performing the balance adjustment processing. It is a figure showing an example of the state of each cell voltage of each battery cell B1-Bn contained in each battery pack immediately after the end of discharge. It is a figure showing an example of the state of each cell voltage of battery cells B1-Bn contained in each battery pack when the difference between Vmax and Vmin is smaller than VAL. FIG. 9 is a block diagram showing another example of a system configuration constructed when performing maintenance on the battery pack unit 100. It is a flowchart which shows another example of the procedure of a cell balance adjustment process.

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

  FIG. 1 is a block diagram showing a configuration of a battery pack unit 100 according to the present invention.

  Battery pack unit 100 includes battery packs BC1 to BCr (r is an integer of 2 or more) connected in series, external power supply terminals T0 and T1, cell controllers CU1 to CUr, and battery protection unit BMU.

  Each of the battery packs BC1 to BCr includes a battery cell B1 to Bn (n is an integer of 2 or more), each of which generates a DC voltage (hereinafter, referred to as a cell voltage) and is connected in series with each other. ing. The battery cells B1 to Bn are rechargeable secondary batteries such as a lead storage battery, a nickel hydride battery, and a lithium ion battery.

  In each of the battery packs BC1 to BCr, the positive terminal of the battery cell B1 included therein is a positive power terminal, and the negative terminal of the battery cell Bn is a negative power terminal. Each battery pack outputs a voltage obtained by combining voltages generated in the battery cells B1 to Bn included in the battery pack as a battery pack voltage through its own positive power supply terminal and negative power supply terminal. I do.

  In addition, as shown in FIG. 1, the power supply terminal on the positive electrode side of BC1 of the battery packs BC1 to BCr is connected to the external power supply terminal T0, and the power supply terminal on the negative electrode side of BC1r is connected to the external power supply terminal T1. ing.

  With the above-described configuration, the battery pack unit 100 outputs a voltage obtained by combining the battery pack voltages generated in each of the battery packs BC1 to BCr as a battery voltage via the external power supply terminals T0 and T1. The battery pack unit 100 is shipped, for example, in a charged state such that the voltage value of the battery voltage becomes a specified rated voltage value.

  As shown in FIG. 1, cell controllers CU1 to CUr are connected to the battery packs BC1 to BCr, respectively. For example, the positive and negative terminals of each of the battery cells B1 to Bn included in the battery pack BC1 are connected to the cell controller CU1, and the positive and negative terminals of each of the battery cells B1 to Bn included in the battery pack BC2. The negative terminal is connected to the cell controller CU2. That is, the cell controller CU (k) (k is an integer of 1 to r) is connected to the positive terminal and the negative terminal of each of the battery cells B1 to Bn included in the battery pack BC (k).

  The cell controllers CU1-CUr individually determine the voltage (referred to as cell voltage) of each of the battery cells B1-Bn included in each of the battery packs BC1-BCr, the current flowing therethrough, the temperature of the battery pack BC (k), and the like. And generates measurement information indicating the measurement result. Further, the cell controllers CU1 to CUr supply the above-described measurement information to the battery protection unit BMU or force any battery cell among the battery cells B1 to Bn in response to various control signals from the battery protection unit BMU. A discharge process for electrically discharging is performed.

  FIG. 2 is a block diagram showing a part of the internal configuration of CU1 extracted from the cell controllers CU1 to CUr.

  In FIG. 2, voltage sensors CS1 to CSn individually measure cell voltages generated in each of the battery cells B1 to Bn, and provide cell voltage signals V1 to Vn representing the measured cell voltages for each battery cell. To the BMU.

  The discharge switches SW1 to SWn and the resistors R1 to Rn are a discharge circuit that selectively discharges each of the battery cells B1 to Bn according to the discharge control signals P1 to Pn supplied from the battery protection unit BMU. Each of the discharge switches SW1 to Wn is a switch element including, for example, a MOS (Metal Oxide Semiconductor) type or a bipolar type transistor.

  That is, the discharge switch SW (t) (t is an integer of 1 to n) is turned off when the discharge control signal P (t) indicates, for example, a logical level 0 for instructing the discharge to stop, and the discharge control signal P ( When t) indicates, for example, a logic level 1 for instructing execution of discharge, the transistor is turned on. When the discharge switch SW (t) is turned on, the positive terminal and the negative terminal of the battery cell B (t) are electrically connected via the resistor R (t), and the battery cell B (t) is discharged. At this time, the discharge current flows into the resistor R (t) and is consumed, so that the battery capacity of the battery cell B (t) decreases. On the other hand, while the discharge switch SW (t) is in the off state, one end of the resistor R (t) is opened, so that the above-described discharge does not occur.

  The battery protection unit BMU performs a battery protection process for preventing the battery packs BC1 to BCr from being overcharged or overdischarged. That is, the battery protection unit BMU monitors the state of overcharge or overdischarge of the battery packs BC1 to BCr based on the measurement information acquired from the cell controllers CU1 to CUr. Then, based on the monitoring result, the battery protection unit BMU performs various controls for preventing the battery packs BC1 to BCr from being overcharged or overdischarged to the cell controllers CU1 to CUr.

  Further, when receiving the maintenance execution signal MEX prompting the maintenance process of the battery, the battery protection unit BMU performs a maintenance process described below, and outputs a charge control signal CGS or a discharge control signal DCS in the process.

  The battery protection unit BMU includes a ROM (Read Only Memory) 10 in which a program representing a procedure of the battery protection process and the maintenance process described above is stored, and a CPU 20 that executes a program stored in the ROM 10.

  In the following, for example, when the cumulative use period of the battery pack unit 100 approaches the recommended period or the battery duration is shortened, the maintenance operation of the battery pack unit 100 performed at a factory or the like that undertakes maintenance of the battery pack unit 100 will be described. explain.

  FIG. 3 is a block diagram showing a system configuration constructed for maintaining the battery pack unit 100.

  As shown in FIG. 3, an electronic load device 200 and a power supply device 300 are connected to external power supply terminals T0 and T1 of the battery pack unit 100 to be maintained.

  When receiving the discharge control signal DCS output from the battery pack unit 100, the electronic load device 200 forcibly disconnects the battery packs BC1 to BCr included in the battery pack unit 100 via the external power supply terminals T0 and T1. Discharge.

  When receiving the charge control signal CDS output from the battery pack unit 100, the power supply device 300 applies the charging voltage indicated by the charge control signal CDS to the external power supply terminals T0 and T1 of the battery pack unit 100. To charge the battery packs BC1 to BCr.

  In the system configuration shown in FIG. 3, when the battery pack unit 100 receives the maintenance execution signal MEX, the CPU 20 executes the maintenance process shown in FIG.

  That is, first, the CPU 20 executes a cell balance adjustment process for equalizing the cell voltages of the battery cells B1 to Bm included in the battery packs BC1 to BCr, respectively (step S100).

  FIG. 5 is a flowchart illustrating the procedure of the cell balance adjustment process.

  In FIG. 5, the CPU 20 supplies the cell controllers CU1-CUr with discharge control signals P1-Pn for instructing all the discharge switches SW1-SWn included in the cell controllers CU1-CUr to be turned off. (Step S11).

  Next, the CPU 20 takes in the cell voltage signals V1 to Vn from the cell controllers CU1 to CUr (step S12).

  Next, the CPU 20 calculates, as the total voltage Vsum, a voltage obtained by combining the cell voltages of the battery cells included in the battery packs BC1 to BCr based on the cell voltage signals V1 to Vn taken from the cell controllers CU1 to CUr. (Step S13). The total voltage Vsum corresponds to the battery voltage output from the external power terminals T0 and T1 of the battery pack unit 100 described above.

  Next, the CPU 20 determines whether or not the total voltage Vsum is lower than a balance voltage BV described below (Step S14).

  The balance voltage BV is a fixed voltage that is a target when the cell voltages of all the battery cells are equalized, and is based on a discharge characteristic as shown in FIG. Ask like.

  That is, first, based on the discharge characteristics, a voltage lower than the discharge voltage corresponding to the battery capacity at a change point at which the rate of decrease of the discharge voltage that decreases as the battery capacity greatly changes, that is, the voltage at the end of discharge, One basic balance voltage FV is used.

  For example, according to the discharge characteristics when the battery cell is a lithium ion battery as shown in FIG. 6, the rate of decrease in the discharge voltage with respect to the decrease in the battery capacity sharply starts at about 10% of the battery capacity when fully charged. Has increased. Therefore, in the example shown in FIG. 6, the discharge voltage at the end of discharge, which is a voltage lower than the discharge voltage V0 at 10% of the battery capacity at full charge, is determined as the basic balance voltage FV per battery cell. Then, a voltage obtained by multiplying the basic balance voltage FV by (n · r), which is the number of battery cells in series by the battery packs BC1 to BCr, is defined as a balance voltage BV.

  If it is determined in step S14 that the total voltage Vsum is not lower than the balance voltage BV, the CPU 20 supplies a discharge control signal DCS for forcibly discharging the battery packs BC1 to BCr to the electronic load device 200 (step S15). At this time, the electronic load device 200 discharges all the battery cells included in the battery packs BC1 to BCr according to the discharge control signal DCS.

  After the execution of step S15, the CPU 20 returns to the execution of step S14, and executes the above-described operation again.

  During this time, if it is determined in step S14 that the total voltage Vsum is lower than the balance voltage BV, the CPU 20 supplies a discharge control signal DCS for instructing to stop discharging to the electronic load device 200 (step S16). As a result, the electronic load device 200 stops the forced discharge for all the battery cells included in the battery packs BC1 to BCr.

  By executing the above steps S14 to S16, the CPU 20 outputs the discharge control signal DCS instructing to discharge all the battery cells included in the battery packs BC1 to BCr until the total voltage Vsum falls below the balance voltage BV. Then, the electronic load device 200 forcibly discharges all battery cells included in the battery packs BC1 to BCr according to the discharge control signal DCS. As a result, the cell voltage of each battery cell gradually decreases with time, and accordingly, the total voltage Vsum also decreases, and the voltage value falls below the balance voltage BV.

  After the execution of step S16, the CPU 20 supplies a charge control signal CGS for instructing the battery packs BC1 to BCr to be charged with the balance voltage BV to the power supply device 300 (step S17). The power supply device 300 generates the balance voltage BV according to the charge control signal CGS, and charges the battery packs BC1 to BCr by applying the balance voltage BV to the external power supply terminals T0 and T1 of the battery pack unit 100. .

  Next, the CPU 20 takes in the cell voltage signals V1 to Vn from each of the cell controllers CU1 to CUr (step S18). Then, based on the captured cell voltage signal group, the CPU 20 determines the maximum cell voltage among the cell voltages of all the battery cells included in the battery packs BC1 to BCr as the cell voltage Vmax and the minimum cell voltage as the cell voltage Vmax. It is detected as the voltage Vmin (step S19).

  Next, the CPU 20 determines whether or not the difference between the cell voltage Vmax and the cell voltage Vmin is smaller than a predetermined allowable voltage difference VAL (Step S20). That is, by executing step S20, the CPU 20 determines that each cell voltage has a value such that the difference between the maximum cell voltage Vmax and the minimum cell voltage Vmin among the cell voltages of all the battery cells becomes smaller than the allowable voltage difference VAL. It is determined whether or not the voltage values have become uniform.

  If it is determined in step S20 that the difference between the cell voltage Vmax and the cell voltage Vmin is not smaller than VAL, the CPU 20 sets all the discharge switches corresponding to each of the battery cells other than the battery cell that generated the cell voltage Vmin. The discharge control signals P1 to Pn for instructing to turn on are supplied to the cell controllers CU1 to CUr (step S21). As a result, among the discharge switches SW1 to SWn included in each cell controller, the discharge switch designated to be on by the discharge control signals P1 to Pn is turned on, and the battery cell connected to the discharge switch is forcibly turned on. Is discharged.

  After the execution of step S21, the CPU 20 returns to the execution of step S18, and executes the operations of steps S18 to S21 again.

  By executing the above-described steps S17 to S21, the CPU 20 performs the following processing after the total voltage Vsum falls below the balance voltage BV by the above-described discharge processing (S14 to S16).

  That is, the CPU 20 instructs the battery packs BC1 to BCr to be charged by applying the balance voltage BV until the difference between Vmax and Vmin, that is, the difference between the cell voltages of all the battery cells is smaller than the allowable voltage difference VAL. The charge control signal CGS is output. In response to the charge control signal CGS, the power supply device 300 generates the balance voltage BV and applies the balance voltage BV to the battery packs BC1 to BCr via the external power supply terminals T0 and T1, thereby charging the battery packs BC1 to BCr. I do.

  During this time, if it is determined in step S20 that the difference between the cell voltage Vmax and the cell voltage Vmin is smaller than the allowable voltage difference VAL, the CPU 20 exits the cell balance adjustment processing S100 and proceeds to the next charging processing (step S200). Move on to execution.

  In the charging process, the CPU 20 fetches the cell voltage signals V1 to Vn from each of the cell controllers CU1 to CUr, and calculates the total voltage Vsum based on the fetched cell voltage signal group in the same manner as in step S13. Then, the CPU 20 controls charging to instruct the external power supply terminals T0 and T1 of the battery pack unit 100 to apply a charging voltage until the voltage value of the total voltage Vsum becomes equal to the rated voltage value of the battery pack unit 100. The signal CGS is supplied to the power supply device 200.

  Here, when the voltage value of total voltage Vsum becomes equal to the rated voltage value, COU 20 determines that battery packs BC1 to BCr are fully charged, and ends the maintenance process shown in FIG.

  Hereinafter, uniformization of the cell voltage achieved by executing the cell balance adjustment processing shown in FIG. 5 in the system configuration shown in FIG. 3 will be described.

  FIG. 7 is a diagram illustrating an example of the state of the cell voltages of the battery cells B1 to Bn included in each of the battery packs BC1 to BCr immediately before the execution of the balance adjustment process. In the example shown in FIG. 7, the cell voltages of the battery cells vary, and the total voltage Vsum obtained by combining the cell voltages of all the battery cells included in the battery packs BC1 to BCr is the balance voltage BV. (= FV · n · r).

  Therefore, when the battery pack unit 100 receives the maintenance execution signal MEX, first, all the battery cells included in the battery packs BC1 to BCr are forcibly discharged until the total voltage Vsum becomes lower than the balance voltage BV. (S14, S15). Then, when the total voltage Vsum becomes smaller than the balance voltage BV, this discharge is stopped (S16).

  FIG. 8 is a diagram illustrating an example of the state of the cell voltage of each of the battery cells B1 to Bn included in each of the battery packs BC1 to BCr immediately after the stop of the discharge.

  That is, due to the above-described forced discharge (S14, S15), as shown in FIG. 8, the cell voltage of each of the battery cells B1 to Bn included in each battery pack BC decreases to near the basic balance voltage FV.

  After stopping the forced discharge (S16), the balance voltage BV is applied to the external power supply terminals T0 and T1 of the battery pack unit, and the battery packs BC1 to BCr are charged by the balance voltage BV (S17). .

  Further, during the charging, until the difference between the maximum cell voltage Vmax and the minimum cell voltage Vmin among the cell voltages of all the battery cells included in the battery packs BC1 to BCr becomes smaller than the allowable voltage difference VAL. Then, the battery cells other than the battery cell generating the minimum cell voltage Vmin are forcibly discharged (S20 to S21).

  For example, in the example shown in FIG. 8, the cell voltages of the battery cell B2 included in the battery pack BC1 and the battery cell B1 included in the battery pack BCr are the minimum. Therefore, the battery cell B2 included in the battery pack BC1 and the battery cell B1 included in the battery pack BCr are charged, and the respective cell voltages gradually increase. On the other hand, the discharge cells other than the battery cell B2 included in the battery pack BC1 and the battery cell B1 included in the battery pack BCr are connected to the respective discharge circuits (SW1 to SWn, R1 to R1). Rn), each cell is discharged, and each cell voltage gradually decreases.

  As a result, the difference between the cell voltage Vmax and the cell voltage Vmin is reduced, and the cell voltages of all the battery cells included in the battery packs BC1 to BCr are made uniform.

  FIG. 9 shows the state of the cell voltage of each of the battery cells B1 to Bn included in each of the battery packs BC1 to BCr when the difference between the cell voltage Vmax and the cell voltage Vmin is smaller than the allowable voltage difference VAL. It is a figure showing an example.

  As described above, according to the cell balance adjustment shown in FIG. 5, even if there is a relatively large voltage difference between the battery pack voltages of the respective battery packs, the cell voltages of the battery cells included in the respective battery packs are reduced. The voltage is equalized so that the difference between the voltages is smaller than the allowable voltage difference.

  Therefore, by performing the cell balance adjustment on the battery pack unit 100, the battery cells included in each battery pack are compared with the case where the voltage is equalized in each battery pack only by the discharge process performed on the plurality of battery packs. The difference between the cell voltages can be reduced. This allows the number of battery cells to be in an overcharged state, and the period during which the overcharged state is maintained, at the time of charging each battery pack to be fully charged, which is performed after the cell balance adjustment is completed. Since it can be reduced, it is possible to suppress a decrease in battery life.

  In the embodiment shown in FIG. 1, the cell controllers CU1-CUr and the battery protection unit BMU included in the battery pack unit 100 perform the discharging process in steps S11-S16 and the charging process in steps S17-S20 shown in FIG. , Has been implemented.

  In short, as the battery pack unit 100, the first to r-th battery cells each including a battery cell group including the first to n-th (n is an integer of 2 or more) battery cells (B1 to Bn) connected in series. In addition to the (r is an integer of 2 or more) battery packs (BC1 to BCr), the battery pack may include any of the following external power supply terminals, a discharge processing unit, and a charge processing unit.

  That is, the external power supply terminals (T0, T1) output a voltage obtained by combining the voltages generated in the first to r-th battery packs (BC1 to BCr) as a total voltage (Vsum), and It is provided to receive a voltage for charging the rth battery pack.

  When the total voltage (Vsum) is higher than a predetermined balance voltage (BV), the discharge processing units (CS1 to CSn, BMU) supply the first to r-th battery packs until the total voltage falls below the balance voltage. A discharge control signal (DCS) for instructing to discharge all the battery cell groups included is output.

  The charge processing units (CS1 to CSn, BMU) connect the cell voltages of all the battery cells included in the first to rth battery packs after the total voltage falls below the balance voltage due to the discharge of the battery cell group by the discharge processing unit. Until the difference becomes smaller than the allowable difference (VAL), a charge control signal (CGS) for instructing charging by applying a balance voltage to the external power supply terminals (T0, T1) is output.

  Further, in the above-described embodiment, a configuration including a plurality of battery packs (BC1 to BCr) has been described as an example of the battery pack unit 100, but it is sufficient that at least one battery pack is included.

  In short, as the battery pack unit 100, in addition to the battery pack (BC) including the battery cell groups (B1 to Bn) including the first to nth (n is an integer of 2 or more) battery cells connected in series, In addition, what is necessary is just to include the following discharge processing part and charge processing part.

  That is, the discharge processing unit (CS1 to CSn, BMU) sets the total voltage (Vsum) obtained by combining the cell voltages (V1 to Vn), which are the voltages of the first to nth battery cells, to a predetermined balance voltage (Vsum). If the total voltage is lower than the balance voltage, a discharge control signal (DCS) for instructing the battery cell groups (B1 to Bn) to be discharged is output.

  The charge processing units (CS1 to CSn, BMU) charge as follows after the total voltage (Vsum) falls below the balance voltage (BV) due to the discharge of the battery cell groups (B1 to Bn) by the discharge processing unit. It outputs a control signal (CGS). That is, the charge processing unit applies the balance voltage (BV) to the battery pack until the difference between the cell voltages of the first to nth battery cells (B1 to Bn) becomes smaller than the tolerance (VAL). A signal instructing charging is output as a charge control signal (CGS).

  Therefore, by performing the cell balance adjustment shown in FIG. 5 on the battery pack unit 100, compared with a case where the cell voltages of the plurality of battery cells included in the battery pack are made uniform only by the discharge process performed on the battery pack. Thus, the difference between cell voltages can be reduced. This reduces the number of overcharged battery cells and the duration of the overcharged state during charging to reach the fully charged state of the battery pack, which is performed after the cell balance adjustment is completed. Therefore, it is possible to suppress a decrease in battery life.

  In the cell balance adjustment shown in FIG. 5, as shown in FIGS. 8 and 9, each of the battery cells B <b> 1 to Bn included in each battery pack is targeted for the basic balance voltage FV which is the voltage at the end of discharge of the battery cells. Cell voltages are aligned. Here, in the last stage of the discharge when the battery capacity of the battery cell becomes about 10% or less, as shown in FIG. 6, the discharge voltage with respect to the decrease in the battery capacity is compared with the case where the battery capacity exceeds about 10%. The amount of decrease is large. As a result, the difference in the discharge voltage corresponding to the difference in the battery capacity between the battery cells is larger at the end of discharge than at the end of discharge.

  Therefore, the cell voltage of each of the battery cells B1 to Bn included in each battery pack can be accurately and uniformly set by using the basic balance voltage FV, which is the voltage at the end of discharge, as the target voltage for aligning the cell voltages. Becomes possible.

  In the above embodiment, as shown in FIG. 3, the electronic load device 200 is connected to the battery pack unit 100 to be maintained, and all the battery cells included in the battery packs BC1 to BCr are connected by the electronic load device 200. Discharge is performed all at once (S15).

  However, the simultaneous discharge of all the battery cells may be performed not by the electronic load device 200 but by the discharge circuits (R1 to Rn, SW1 to SWn) included in each of the cell controllers CU1 to CUr.

  FIG. 10 is a block diagram showing another example of a system configuration constructed when the maintenance of the battery pack unit 100 is performed in view of the above point.

  In the system configuration shown in FIG. 10, the electronic load device 200 is not used, and only the power supply device 300 for charging is connected to the external power supply terminals T0 and T1 of the battery pack unit 100.

  FIG. 11 is a flowchart illustrating a procedure of the cell balance adjustment process performed in step S100 illustrated in FIG. 4 when the system configuration illustrated in FIG. 10 is employed in performing the maintenance of the battery pack unit 100.

  Note that, in the flowchart shown in FIG. 11, the operations of steps S11 to S14 and S17 to S21 other than the point that steps S150 and S160 are adopted instead of steps S15 and S16 shown in FIG. 5 are shown in FIG. It is the same as the one. Therefore, only the operation of steps S150 and S160 will be described below.

  Step S150 is executed when the CPU 20 determines in step S14 shown in FIG. 11 that the balance voltage BV is not higher than the total voltage Vsum. In step S150, the CPU 20 supplies the cell controllers CU1 to CUr with the discharge control signals P1 to Pr for setting all the discharge switches SW1 to SWn included in the cell controllers CU1 to CUr to the ON state. After the execution of step S150, the CPU 20 returns to the execution of step S14, and executes the above-described operation again.

  During this time, if it is determined in step S14 that the balance voltage BV is higher than the total voltage Vsum, the CPU 20 executes step S160. In step S160, the CPU 20 supplies the cell controllers CU1 to CUr with the discharge control signals P1 to Pr for setting all the discharge switches SW1 to SWn included in the cell controllers CU1 to CUr to the off state. After execution of step S160, the CPU 20 proceeds to execution of step S17 described above.

  That is, by executing steps S14, S150 and S160, when the total voltage Vsum is higher than the balance voltage BV, the CPU 20 discharges all the battery cells included in the battery packs BC1 to BCr until the total voltage Vsum falls below the BV. . That is, at this time, the discharge circuits (R1 to Rn, SW1 to SWn) included in each of the cell controllers CU1 to CUr forcibly discharge all the battery cells included in the battery packs BC1 to BCr. .

  In short, when performing the cell balance adjustment process as shown in FIG. 11, the battery pack unit 100 includes a battery cell group including first to nth (n is an integer of 2 or more) battery cells connected in series. In addition to the battery pack (BC) including (B1 to Bn), any battery may be used as long as it includes the following discharge processing unit and charge processing unit.

  That is, the discharge processing units (CS1 to CSn, SW1 to SWn, R1 to Rn, and BMU) combine the cell voltages (V1 to Vn), which are the voltages of the first to nth battery cells, to a total voltage (Vsum). Is larger than a predetermined balance voltage (BV), the battery cell groups (B1 to Bn) are discharged until the total voltage falls below the balance voltage.

  When the total voltage (Vsum) falls below the balance voltage (BV) due to the discharge of the battery cell groups (B1 to Bn) by the discharge processing unit, the charge processing units (CS1 to CSn, BMU) determine the difference between the cell voltages. Until is smaller than the tolerance (VAL), a charge control signal (CGS) for instructing the battery pack to be charged by applying the balance voltage (BV) is output.

  According to such a configuration, in performing the cell balance adjustment, the cell voltages of the battery cells B1 to Bn included in each battery pack BC are adjusted to the basic balance without using the electronic load device 200 as shown in FIG. It is possible to reduce the voltage to near the voltage FV.

REFERENCE SIGNS LIST 100 Battery pack unit 200 Electronic load device 300 Power supply devices B1 to Bn Battery cells BC1 to BCr Battery pack BMU Battery protection unit CU1 to CUR Cell controller
SW1-SWn discharge switch

Claims (9)

A battery pack including a battery cell group consisting of first to n-th (n is an integer of 2 or more) battery cells connected in series;
When the total voltage obtained by combining the cell voltages, which are the voltages of the first to n-th battery cells of the battery cell group, is greater than a predetermined balance voltage, the battery is operated until the total voltage falls below the balance voltage. A discharge processing unit that outputs a discharge control signal that is a signal instructing to discharge the cell group,
After the total voltage falls below the balance voltage due to the discharge of the battery cell group by the discharge processing unit, until the difference between the cell voltages of the first to nth battery cells becomes smaller than an allowable difference, A battery pack unit comprising: a charge processing unit that outputs a charge control signal that is a signal for instructing the battery pack to be charged by applying the balance voltage. The discharge processing unit,
By a discharge circuit capable of individually discharging the first to nth battery cells, a difference between the maximum cell voltage and the minimum cell voltage is reduced from the time when the total voltage falls below the balance voltage. over until smaller than the allowable voltage difference, claim 1, wherein the first through characterized by discharging the battery cells other than the cell that produces the minimum cell voltage among the battery cells of the n the battery pack unit according to. The charging processing unit,
A signal indicating that the battery pack is charged until the voltage value of the total voltage becomes equal to a rated voltage value when a difference between the maximum cell voltage and the minimum cell voltage is smaller than the tolerance. 3 is output as the charge control signal.   The balance voltage is a discharge voltage corresponding to the battery capacity at a change point where the rate of decrease of the discharge voltage that decreases as the battery capacity decreases changes in a discharge characteristic indicating a transition of the discharge voltage with respect to the battery capacity in the battery cell. The battery pack unit according to any one of claims 1 to 3, wherein the battery pack unit has a voltage value obtained by multiplying a predetermined voltage lower by n times. 5. The battery pack unit according to claim 4 , wherein the predetermined voltage is a discharge voltage of the battery cell at a final stage of discharge of the battery cell. 6. The battery cell is a lithium ion battery,
The battery pack unit according to claim 4, wherein the predetermined voltage is a discharge voltage corresponding to a battery capacity of 10% or less of a capacity of the battery cell when fully charged. A cell balance adjusting method for adjusting a voltage of each of the battery cells of a battery pack including a battery cell group including first to nth (n is an integer of 2 or more) battery cells connected in series,
A discharging step of discharging the battery cell group until a total voltage obtained by combining cell voltages that are voltages of the first to nth battery cells of the battery cell group falls below a predetermined balance voltage;
After the total voltage falls below the balance voltage, a charging step of applying the balance voltage to the battery pack and charging the battery pack until the difference between the cell voltages is smaller than a tolerance.
A cell balance adjusting method comprising: A battery pack including a battery cell group consisting of first to n-th (n is an integer of 2 or more) battery cells connected in series;
When the total voltage obtained by combining the cell voltages, which are the voltages of the first to n-th battery cells of the battery cell group, is greater than a predetermined balance voltage, the battery is operated until the total voltage falls below the balance voltage. A discharge processing unit for discharging the cell group;
When the total voltage falls below the balance voltage due to the discharge of the battery cell group by the discharge processing unit, the balance voltage is applied to the battery pack until the difference between the cell voltages becomes smaller than an allowable difference. A charge processing unit that outputs a charge control signal that is a signal instructing to charge the battery;
A battery pack unit comprising: First to r-th (r is an integer of 2 or more) battery packs each including a battery cell group including first to n-th (n is an integer of 2 or more) battery cells connected in series;
An external power supply terminal for receiving a voltage for charging the first to r-th battery packs, while outputting a voltage obtained by combining the voltages generated in the first to r-th battery packs as a total voltage,
When the total voltage is higher than a predetermined balance voltage, a signal indicating that all the battery cell groups included in the first to rth battery packs are discharged until the total voltage falls below the balance voltage. A discharge processing unit that outputs a discharge control signal that is
After the total voltage falls below the balance voltage due to the discharge of the battery cell group by the discharge processing unit, a difference between the cell voltages of all the battery cells included in the first to r-th battery packs is allowed. Until the difference is smaller than the difference, a charge processing unit that outputs a charge control signal that is a signal that instructs the external power supply terminal to apply the balance voltage and charge the battery,
A battery pack unit comprising:

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