JP2022141451A - Storage battery control device, power storage system, and storage battery control method - Google Patents

Abstract

To increase input/output for charging and discharging in a power storage system in which a plurality of storage batteries are connected in series.SOLUTION: A storage battery control device 100 controls a power storage system 1 that comprises a plurality of storage battery cells C1 to Cn connected in series and a plurality of bypass circuits B1 to Bn. The storage battery control device 100 controls disconnection and connection of the storage battery cells C1 to Cn by the bypass circuits B1 to Bn so that an input or output power of the storage battery cells C1 to Cn to be connected without disconnecting the cells by the bypass circuits B1 to Bn becomes larger compared with a case where all storage battery cells C1 to Cn are connected without disconnecting the cells by the bypass circuits B1 to Bn.SELECTED DRAWING: Figure 1

Description

The present invention relates to a storage battery control device, a power storage system, and a storage battery control method.

As a system for controlling the charging and discharging of a battery device in which a plurality of batteries are connected in series, the battery that avoids charging and discharging is selected based on the state of each battery, and the battery that avoids charging and discharging is bypassed from other batteries. A battery that charges and discharges is known (see Patent Documents 1 and 2, for example).

JP 2013-31247 A JP 2013-31249 A

In the above system, when charging a plurality of batteries (hereinafter referred to as storage batteries), it is assumed that all the storage batteries are connected in series for charging, and the fully charged storage battery is bypassed. However, if there is a difference in the state of charge of the multiple storage batteries due to differences in the state of deterioration of the multiple storage batteries, etc., the current limit values set for the multiple storage batteries will also differ according to the state of charge. is generated, and the plurality of storage batteries are charged with the minimum current among the current limit values set for the plurality of storage batteries. Here, the current limit value during charging is set smaller as the storage battery approaches full charge, and is set larger as the storage battery approaches full discharge. For this reason, when charging is performed while all the storage batteries are connected in series, charging may not be performed with the maximum charging power, and charging efficiency may be low.

In the above system, when discharging a plurality of storage batteries, it is assumed that all the storage batteries are connected in series and discharged, and the fully discharged storage battery is bypassed. However, if there is a difference in the state of charge of the multiple storage batteries due to differences in the state of deterioration of the multiple storage batteries, etc., there will be differences in the current limit values set for the multiple storage batteries. A plurality of storage batteries are discharged with the minimum current among the set current limit values. Here, the current limit value during discharging is set larger as the storage battery approaches full charge, and is set smaller as the storage battery approaches full discharge. For this reason, when all the storage batteries are connected in series and discharged, the maximum discharge power may not be discharged, and a high output may not be obtained.

In view of the above circumstances, it is an object of the present invention to provide a storage battery control device, a storage system, and a storage battery control method that can realize a larger input/output in a storage system in which a plurality of storage batteries are connected in series.

A storage battery control device of the present invention is a storage battery control device for controlling a storage battery system, wherein the storage battery system includes a plurality of storage batteries connected in series, each having a current limit value set therein, and a plurality of storage batteries each bypassing the storage battery. and a plurality of bypass circuits that cut off the storage batteries, and the storage battery control device is configured such that the input power or the output power of the storage batteries connected without being cut off by the bypass circuits allows all of the storage batteries to pass through the bypasses. The disconnection and connection of the storage battery by the bypass circuit is controlled so as to be larger than the case of connecting without disconnection by the circuit.

In addition, the power storage system of the present invention controls a plurality of storage batteries connected in series, a plurality of bypass circuits that cut off the storage batteries by bypassing the storage batteries, and the bypass circuits. a storage battery control device for setting a current limit value, wherein the storage battery control device is such that the input power or the output power of the storage battery connected without being cut off by the bypass circuit causes all of the storage batteries to be cut off by the bypass circuit. The disconnection and connection of the storage battery by the bypass circuit are controlled so as to be larger than the case of connection without connection.

Further, a storage battery control method of the present invention is a storage battery control method performed by using a storage battery control device for controlling a storage battery system, wherein the storage battery system is connected in series with a plurality of devices each having a current limit value set. A storage battery and a plurality of bypass circuits that bypass the storage battery to cut off the storage battery, and the input power or the output power of the storage battery connected without being cut off by the bypass circuit The disconnection and connection of the storage battery by the bypass circuit is controlled so as to be larger than the case of connecting without disconnecting by the bypass circuit.

According to the present invention, the connection is made such that the input power or the output power of the storage battery connected without being cut off by the bypass circuit is larger than when all the storage batteries are connected without being cut off by the bypass circuit. Since the storage battery selected is selected, a larger input/output can be realized in a power storage system in which a plurality of storage batteries are connected in series.

FIG. 1 is a diagram showing an outline of a power storage system including a storage battery control device according to one embodiment of the present invention. FIG. 2 is a flowchart for explaining charging control by the storage battery control device shown in FIG. FIG. 3 is a flowchart for explaining discharge control by the storage battery control device shown in FIG. FIG. 4 is a flowchart for explaining a modification of charging control by the storage battery control device shown in FIG. FIG. 5 is a flowchart for explaining a modification of discharge control by the storage battery control device shown in FIG.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below along with preferred embodiments. It should be noted that the present invention is not limited to the embodiments described below, and can be modified as appropriate without departing from the gist of the present invention. In addition, in the embodiments shown below, there are places where illustrations and explanations of some configurations are omitted, but the details of the omitted technologies are provided within the scope that does not cause contradiction with the contents explained below. , Appropriately known or well-known techniques are applied.

FIG. 1 is a diagram showing an outline of a power storage system 1 including a storage battery control device 100 according to one embodiment of the present invention. As shown in this figure, the power storage system 1 includes a plurality of storage battery cells C1-Cn, a plurality of bypass circuits B1-Bn, and a storage battery control device 100. FIG. A plurality of storage battery cells C1 to Cn constitute a power supply system 10 for vehicle use or stationary use connected in series. Although not particularly limited, the storage battery cells C1 to Cn of the present embodiment are regenerated used batteries, and each storage battery cell C1 to Cn has a different degree of deterioration. The storage battery cells C1 to Cn are, for example, secondary batteries such as lithium ion batteries and lithium ion capacitors. supply.

The power storage system 1 includes a plurality of voltage measuring units 12 , a current measuring unit 13 , a battery temperature measuring unit 14 and a current limiting unit 15 . The voltage measuring unit 12 is connected between the positive and negative terminals of each of the storage battery cells C1-Cn. This voltage measuring unit 12 measures the voltage V between the terminals of each of the storage battery cells C1 to Cn.

The current measurement unit 13 is provided on the current path of the power supply system 10 . This current measurement unit 13 measures the charge/discharge current of the power supply system 10 . Also, the power supply system 10 is provided with a battery temperature measurement unit 14 . This battery temperature measurement unit 14 measures the temperature T of the power supply system 10 . Further, the current limiting unit 15 limits the input/output current of the power supply system 10 according to a control signal from the current control unit 104 which will be described later.

Each bypass circuit B1-Bn is provided for each of the storage battery cells C1-Cn. Bypass circuits B1 to Bn each include a bypass line BL and switches S1 and S2. A bypass line BL is a power line that bypasses each of the storage battery cells C1 to Cn. The switch S1 is provided on the bypass line BL. This switch S1 is, for example, a mechanical switch. The switch S2 is provided between the positive electrode of each of the storage battery cells C1 to Cn and one end of the bypass line BL. This switch S2 is, for example, a semiconductor switch.

The storage battery cell C1 at the beginning and the storage battery cell Cn at the end are connected to the external system ES. When the switches S1 are opened and the switches S2 are closed in all the bypass circuits B1-Bn, charging/discharging between all the storage battery cells C1-Cn and the external system ES becomes possible. On the other hand, when the switch S2 is opened and the switch S1 is closed in any of the bypass circuits B1-Bn, the storage battery cells C1-Cn corresponding to the bypass circuits B1-Bn are bypassed.

The storage battery control device 100 is connected to each storage battery cell C1 to Cn and each bypass circuit B1 to Bn, and performs monitoring and control of each storage battery cell C1 to Cn and switching control of each bypass circuit B1 to Bn. The storage battery control device 100 of this embodiment switches the bypass circuits B1 to Bn based on the voltage V of each storage battery cell C1 to Cn, the charging current limit value Ic, and the discharging current limit value Id.

The storage battery control device 100 includes a measured value acquisition section 101 , a current limit value calculation section 102 , a storage section 103 , a current control section 104 and a bypass control section 105 .

Measured value acquisition unit 101 is connected to voltage measurement unit 12 , current measurement unit 13 , and battery temperature measurement unit 14 . The measured value acquiring unit 101 acquires measured values from the voltage measuring unit 12 , the current measuring unit 13 and the battery temperature measuring unit 14 and stores them in the storage unit 103 .

The current limit value calculator 102 calculates the charge current limit value Ic and the discharge current limit value Id of each of the storage battery cells C1 to Cn based on the measured values acquired by the measured value acquirer 101 . The charging current limit value Ic is an upper limit value of the charging current that is set from the viewpoint of suppressing deterioration of each storage battery cell C1 to Cn and preventing damage. Also, the discharge current limit value Id is the upper limit value of the discharge current set from the same viewpoint. The charging current limit value Ic is set to a smaller value as each of the storage battery cells C1 to Cn is closer to being fully charged, and is set to a larger value as each of the storage battery cells C1 to Cn is closer to being fully discharged. On the other hand, the discharge current limit value Id is set to a smaller value as each of the storage battery cells C1 to Cn is closer to being fully discharged, and is set to a larger value as each of the storage battery cells C1 to Cn is closer to being fully charged.

The current limit value calculator 102 calculates the charge current limit value Ic and the discharge current limit value Id of each of the storage battery cells C1 to Cn by various conventionally known methods. As a method of calculating the charging current limit value Ic, a method of calculating based on the following formula (1) can be exemplified, and as a method of calculating the discharging current limit value Id, a method of calculating based on the following formula (2) can be exemplified. can.
OCV+r·Ic=V _CE (1)
OCV-r·Id= _VDE (2)

OCV is the open circuit voltage of each storage battery cell C1 to Cn, and the current limit value calculation unit 102 calculates the voltage V, current value I, temperature T, etc. of each storage battery cell C1 to Cn by various conventionally known methods. It is a value calculated by Also, r is the internal resistance of each storage battery cell C1 to Cn, and the current limit value calculation unit 102 calculates various conventionally known values based on the voltage V, current value I, temperature T, etc. of each storage battery cell C1 to Cn. It is a value calculated by the method. Furthermore, V _CE is the end-of-charge voltage of each storage battery cell C1-Cn, and V-- _DE is the end-of-discharge voltage.

Current limit value calculation unit 102 calculates current open circuit voltage OCV and internal resistance r, and calculates charging current limit value Ic and discharge current limit value Id according to the calculated values according to (1) and (2) above. Calculated based on the formula. Note that the charging current limit value Ic and the discharging current limit value Id may be defined by the C rate. In addition, a table defining the correlation between the SOC (State of Charge) and the charging current limit value Ic and a table defining the correlation between the SOC and the discharge current limit value Id are created in advance and stored in the storage unit 103. Then, the charging current limit value Ic and the discharging current limit value Id corresponding to the current SOC may be derived from the table.

Here, if there are differences in the SOC, SOH (State of Health), internal resistance, temperature, etc. of the plurality of storage battery cells C1 to Cn, a difference occurs in the open circuit voltage OCV of the plurality of storage battery cells C1 to Cn, A difference occurs in the charging current limit value Ic and the discharging current limit value Id of the plurality of storage battery cells C1 to Cn. It is not possible to input a charging current exceeding the charging current limit value Ic or output a discharging current exceeding the discharging current limit value Id to any of the plurality of storage battery cells C1 to Cn. Therefore, the current control unit 104 sets the charging current of the storage battery cells C1 to Cn connected without being cut off by the bypass circuits B1 to Bn as the charging current limit value Ic of the storage battery cells C1 to Cn. Control below the minimum value among the values calculated by In addition, the current control unit 104 sets the discharge current of the storage battery cells C1 to Cn connected without interruption by the bypass circuits B1 to Bn to the current limit value calculation unit 102 as the discharge current limit value Id of the storage battery cells C1 to Cn. Control below the minimum value among the values calculated by

Here, there are many combinations of the storage battery cells C1 to Cn that are disconnected by the bypass circuits B1 to Bn and the storage battery cells C1 to Cn that are connected without being disconnected by the bypass circuits B1 to Bn. Bypass control unit 105 calculates charge power limit value Pc and discharge power limit value Pd for many combinations of storage battery cells C1 to Cn to be disconnected and storage battery cells C1 to Cn to be connected without disconnection. The charging power limit value Pc is the product of the minimum value among the charging current limit values Ic of the connected storage battery cells C1 to Cn and the sum of the voltages V of the connected storage battery cells C1 to Cn. The discharge power limit value Pd is the product of the minimum value among the discharge current limit values Id of the connected storage battery cells C1 to Cn and the sum of the voltages V of the connected storage battery cells C1 to Cn.

For example, when three storage battery cells C1 to C3 are connected in series, the voltages V of the storage battery cells C1, C2, and C3 are 3 V, 3 V, and 4 V, respectively, and the charging of the storage battery cells C1, C2, and C3 is Suppose the current limits Ic were 10A, 10A and 1A respectively. In this case, when all the storage battery cells C1 to C3 are connected, the charging power limit value Pc is the sum of the minimum value (1 A) of the charging current limit value Ic of the storage battery cells C1 to C3 and the voltage V of the storage battery cells C1 to C3 ( 10V) and the product (10W). On the other hand, when the storage battery cell C3 is cut off by the bypass circuit B3 and the storage battery cells C1 and C2 are connected, the charging power limit value Pc is the minimum value (10 A) of the charging current limit value Ic of the storage battery cells C1 and C2 and the storage battery It is the product (60 W) of the sum of the voltages V of the cells C1 and C2 (6 V). That is, the charging power limit value Pc when disconnecting the storage battery cell C3 with the smallest charging current limit value Ic is greater than the charging power limit value Pc when all the storage battery cells C1 to C3 are connected. The same applies to the discharge power limit value Pd.

Therefore, when the power supply system 10 is charged, the bypass control unit 105 calculates the charging power limit value Pc for the combination of the large number of storage battery cells C1 to Cn, and selects the combination that maximizes the calculated charging power limit value Pc. It selects and controls disconnection and connection of the storage battery cells C1 to Cn by the bypass circuits B1 to Bn so that the selected combination of storage battery cells C1 to Cn are connected. Further, when the power supply system 10 is discharged, the bypass control unit 105 calculates the discharge power limit value Pd for the combination of the large number of storage battery cells C1 to Cn, and selects the combination that maximizes the calculated discharge power limit value Pd. It selects and controls disconnection and connection of the storage battery cells C1 to Cn by the bypass circuits B1 to Bn so that the selected combination of storage battery cells C1 to Cn are connected.

Here, when selecting the storage battery cells C1 to Cn to be connected, it is not essential to select the combination of the storage battery cells C1 to Cn that maximizes the charging power limit value Pc, and all the storage battery cells C1 to Cn are connected. A combination of the storage battery cells C1 to Cn in which the charging power limit value Pc is greater than that of . For example, in the case where the combination of storage battery cells C1 to Cn with the maximum charge power limit value Pc includes a storage battery cell Cx with a large degree of deterioration, the storage battery cell Cx is excluded, and the combination is It is also possible to select a combination of the storage battery cells C1 to Cn that subsequently increases the charging power limit value Pc.

Further, when selecting the storage battery cells C1 to Cn to be connected, it is not essential to select a combination of the storage battery cells C1 to Cn that maximizes the discharge power limit value Pd. A combination of the storage battery cells C1 to Cn with which the discharge power limit value Pd is relatively large may be selected. For example, when the combination of storage battery cells C1 to Cn with the maximum discharge power limit value Pd includes a storage battery cell Cy with a large degree of deterioration, the storage battery cell Cy is excluded, and the combination is It is also possible to select a combination of the storage battery cells C1 to Cn that subsequently increases the discharge power limit value Pd.

FIG. 2 is a flowchart for explaining charging control by the storage battery control device 100 shown in FIG. The process shown in this flowchart is started when the power storage system 1 is set to the charging mode, and the process proceeds to step 1 .

At step 1, the bypass control unit 105 turns off the switches S1 and S2 of all the bypass circuits B1 to Bn. Next, in step 2, the current limit value calculator 102 calculates the charging current limit values Ic for all the storage battery cells C1 to Cn.

Next, in step 3, the bypass control unit 105 calculates the charging current limit values Ic of all the storage battery cells C1 to Cn calculated by the current limit value calculation unit 102, and the charging current limit values Ic of all the storage battery cells measured by the voltage measurement unit 12. Based on the voltages V of C1 to Cn, the charge power limit value Pc for the combination of the large number of storage battery cells C1 to Cn is calculated. Next, in step 4, the bypass control unit 105 selects the combination of the storage battery cells C1 to Cn that maximizes the charging power limit value Pc from among many combinations of the storage battery cells C1 to Cn.

Next, in step 5, the bypass control unit 105 determines whether or not the selected storage battery cells C1 to Cn include the storage battery cells C1 to Cn to be excluded. When the storage battery cells C1 to Cn to be excluded are included, the process proceeds to step 6, and when the storage battery cells C1 to Cn to be excluded are not included, the process proceeds to step 7.

In step 6, bypass control unit 105 selects a combination of storage battery cells C1 to Cn having the next largest charge power limit value Pc after the selected combination of storage battery cells C1 to Cn. Go from step 6 to step 5.

In step 7, the bypass control unit 105 controls the bypass circuits B1 to Bn so that the selected storage battery cells C1 to Cn are connected and the non-selected storage battery cells C1 to Cn are cut off. Next, in step 8, the current control unit 104 inputs a current equal to or lower than the minimum value among the charging current limit values Ic of the connected storage battery cells C1 to Cn to the connected storage battery cells C1 to Cn. .

Next, in step 9, the bypass control unit 105 determines whether or not there is a storage battery cell C1-Cn that has reached the charge cut-off voltage CCV (charging is completed) among all the storage battery cells C1-Cn. . If an affirmative determination is made in this step, the process proceeds to step 10, and if a negative determination is made in this step, the process proceeds to step 2.

At step 10, the bypass control unit 105 determines whether or not the voltages V of all the storage battery cells C1 to Cn have reached the charge termination voltage CCV (whether charging has been completed). If an affirmative determination is made in this step, the process proceeds to step 12, and if a negative determination is made in this step, the process proceeds to step 11.

At step 11, the bypass control unit 105 controls the corresponding bypass circuits B1 to Bn so that the fully charged storage battery cells C1 to Cn are cut off. Step 11 shifts to step 2.

On the other hand, in step 12, the current control section 104 stops charging. Next, in step 13, the bypass control section 105 turns off the switches S1 and S2 of all the bypass circuits B1 to Bn. Next, in step 14, the bypass control section 105 turns ON the switches S2 of all the bypass circuits B1 to Bn. With this, the processing shown in FIG. 2 ends.

Here, for example, when the external system ES has a photovoltaic power generation system and charges the storage battery cells C1 to Cn with the power generated by the photovoltaic power generation system, it is necessary to increase the amount of charge during the daytime. In such a case, it is necessary to increase the charging power limit value Pc as much as possible to improve charging efficiency. Therefore, in the power storage system 1 of the present embodiment, the charging power limit value Pc of the plurality of storage battery cells C1 to Cn connected without being cut off by the bypass circuits B1 to Bn is set to the value of the charging power limit Pc for all the storage battery cells C1 to Cn. The combination of the connected storage battery cells C1 to Cn is selected so as to be larger than the case where the cells C1 to Cn are connected without interruption by .about.Bn. Therefore, the charging power limit value Pc in the power storage system 1 can be made as large as possible, and highly efficient charging with a higher charging amount per unit time in the power storage system 1 can be realized.

In particular, in the power storage system 1 of the present embodiment, the charge power limit value Pc of the power supply system 10 is set to the maximum value of the charge power limit Pc of the power supply system 10, except for the case where there are storage battery cells C1 to Cn that should be disconnected from the power supply system 10 for reasons such as significant progress of deterioration. A combination of the storage battery cells C1 to Cn that are connected without being cut off by the bypass circuits B1 to Bn is selected so that the maximum is achieved. As a result, the charging power limit value Pc in the power storage system 1 can be maximized, and the efficiency of charging in the power storage system 1 can be maximized.

In addition, in the power storage system 1 of the present embodiment, the charging power limit value Pc of the storage battery cells C1 to Cn connected without interruption by the bypass circuits B1 to Bn is the charging current limit set for the connected storage battery cells C1 to Cn. It is the product of the minimum value among the values Ic and the sum of the voltages V of the connected storage battery cells C1 to Cn. Here, there is a tendency that the higher the voltage V of each of the storage battery cells C1-Cn, the lower the charging current limit value Ic of each of the storage battery cells C1-Cn. Therefore, when selecting the combination of the storage battery cells C1 to Cn to be connected based only on the voltage V of each of the storage battery cells C1 to Cn, the combination of the storage battery cells C1 to Cn that reduces the charge power limit value Pc may be selected. be. On the other hand, in the power storage system 1 of the present embodiment, based on the charging power limit value Pc, which is the product of the sum of the voltages V of the respective storage battery cells C1 to Cn and the charging current limit value Ic, the connected storage battery cells C1 to Since a combination of Cn is selected, it is possible to select a combination that maximizes the charging power limit value Pc.

FIG. 3 is a flowchart for explaining discharge control by the storage battery control device 100 shown in FIG. The process shown in this flowchart is started when the power storage system 1 is set to the discharge mode, and the process proceeds to step 101 .

At step 101, the bypass control unit 105 turns off the switches S1 and S2 of all the bypass circuits B1 to Bn. Next, in step 102, the current limit value calculator 102 calculates discharge current limit values Id for all the storage battery cells C1 to Cn.

Next, in step 103, the bypass control unit 105 determines the discharge current limit values Id of all the storage battery cells C1 to Cn calculated by the current limit value calculation unit 102, and the discharge current limit values Id of all the storage battery cells measured by the voltage measurement unit 12. Based on the voltages V of C1 to Cn, the discharge power limit value Pd for the combination of the large number of storage battery cells C1 to Cn is calculated. Next, in step 104, the bypass control unit 105 selects the combination of the storage battery cells C1-Cn that maximizes the discharge power limit value Pd from among the large number of combinations of the storage battery cells C1-Cn.

Next, in step 105, the bypass control unit 105 determines whether or not the selected storage battery cells C1 to Cn include the storage battery cells C1 to Cn to be excluded. When the storage battery cells C1 to Cn to be excluded are included, the process proceeds to step 106, and when the storage battery cells C1 to Cn to be excluded are not included, the process proceeds to step 107.

At step 106, the bypass control unit 105 selects the combination of the storage battery cells C1 to Cn having the second largest discharge power limit value Pd after the combination of the selected storage battery cells C1 to Cn. Step 106 shifts to step 105 .

At step 107, the bypass control unit 105 controls the bypass circuits B1 to Bn so that the selected storage battery cells C1 to Cn are connected and the non-selected storage battery cells C1 to Cn are cut off. Next, in step 108, the current control unit 104 outputs a current equal to or lower than the minimum value among the discharge current limit values Id of the connected storage battery cells C1 to Cn from the connected storage battery cells C1 to Cn. .

Next, in step 109, the bypass control unit 105 determines whether or not there is a storage battery cell C1-Cn that has reached the discharge end voltage (discharge is completed) among all the storage battery cells C1-Cn. If an affirmative determination is made in this step, the process proceeds to step 110 , and if a negative determination is made in this step, the process proceeds to step 102 .

At step 110, the bypass control unit 105 determines whether or not the voltages V of all the storage battery cells C1 to Cn have reached the final discharge voltage (whether or not the discharge has been completed). If an affirmative determination is made in this step, the process proceeds to step 112 , and if a negative determination is made in this step, the process proceeds to step 111 .

At step 111, the bypass control unit 105 controls the bypass circuits B1 to Bn so that the discharged storage battery cells C1 to Cn are cut off. Step 111 shifts to step 102 .

On the other hand, at step 112, the current control section 104 stops discharging. Next, at step 113, the bypass control unit 105 turns off the switches S1 and S2 of all the bypass circuits B1 to Bn. Next, at step 114, the bypass control section 105 turns on the switches S2 of all the bypass circuits B1 to Bn. With this, the processing shown in FIG. 3 ends.

Here, for example, in an electric vehicle, when the required output of the external system ES (load) connected to the power storage system 1 is higher than the discharge power limit value Pd of the power storage system 1, the output limit mode is set. In such a case, it is necessary to increase the discharge power limit value Pd as much as possible to increase the output during discharge. Therefore, in the power storage system 1 of the present embodiment, the discharge power limit value Pd of the plurality of storage battery cells C1 to Cn that are connected without being cut off by the bypass circuits B1 to Bn is set to the value that all the storage battery cells C1 to Cn are connected to the bypass circuit B1. The combination of the connected storage battery cells C1 to Cn is selected so as to be larger than the case where the cells C1 to Cn are connected without interruption by .about.Bn. Therefore, the discharge power limit value Pd in the power storage system 1 can be made as large as possible, and high-output operation in which the amount of discharge per unit time in the power storage system 1 is large can be realized.

In particular, in the power storage system 1 of the present embodiment, except for the case where there are storage battery cells C1 to Cn that should be disconnected from the power supply system 10 for reasons such as significant progress of deterioration, the discharge power limit value Pd of the power supply system 10 is A combination of the storage battery cells C1 to Cn that are connected without being cut off by the bypass circuits B1 to Bn is selected so that the maximum is achieved. As a result, the discharge power limit value Pd in the power storage system 1 can be maximized, and the output of the power storage system 1 during discharging can be maximized.

Further, in the power storage system 1 of the present embodiment, the discharge power limit value Pd of the storage battery cells C1 to Cn connected without interruption by the bypass circuits B1 to Bn is the discharge current limit set for the connected storage battery cells C1 to Cn. It is the product of the minimum value among the values Id and the sum of the voltages V of the connected storage battery cells C1 to Cn. Here, there is a tendency that the lower the voltage V of each of the storage battery cells C1-Cn, the lower the discharge current limit value Id of each of the storage battery cells C1-Cn. Therefore, when selecting a combination of connected storage battery cells C1 to Cn based only on the voltage V of each storage battery cell C1 to Cn, a combination with a small discharge power limit value Pd may be selected. On the other hand, in the power storage system 1 of the present embodiment, based on the discharge power limit value Pd, which is the product of the sum of the voltages V of the respective storage battery cells C1 to Cn and the discharge current limit value Id, the connected storage battery cells C1 to Since a combination of Cn is selected, it is possible to select a combination that maximizes the discharge power limit value Pd.

FIG. 4 is a flowchart for explaining a modification of charging control by the storage battery control device 100 shown in FIG. The process shown in this flowchart is started when the power storage system 1 is set to the charging mode, and the process proceeds to step 201 .

At step 201, the bypass control unit 105 turns off the switches S1 and S2 of all the bypass circuits B1 to Bn. Next, in step 202, the current limit value calculator 102 calculates the charging current limit values Ic for all the storage battery cells C1 to Cn.

Next, in step 203, the bypass control unit 105 excludes the storage battery cell Cmin having the smallest charging current limit value Ic from among the plurality of storage battery cells C1 to Cn, and selects the other storage battery cells C1 to Cn. . Step 203 shifts to step 204 .

At step 204, the bypass control unit 105 controls the bypass circuits B1 to Bn so that the selected storage battery cells C1 to Cn are connected and the storage battery cell Cmin with the smallest charging current limit value Ic is cut off. Next, in step 205, the current control unit 104 inputs a current equal to or lower than the minimum value among the charging current limit values Ic of the connected storage battery cells C1 to Cn to the connected storage battery cells C1 to Cn. .

Next, in step 206, the bypass control unit 105 determines whether or not there are any storage battery cells C1 to Cn that have reached the charge cut-off voltage CCV (charging is completed) among all the storage battery cells C1 to Cn. . If an affirmative determination is made in this step, the process proceeds to step 207 , and if a negative determination is made in this step, the process proceeds to step 202 .

At step 207, the bypass control unit 105 determines whether or not the voltages V of all the storage battery cells C1 to Cn have reached the charge termination voltage CCV (whether charging has been completed). If an affirmative determination is made in this step, the process proceeds to step 209 , and if a negative determination is made in this step, the process proceeds to step 208 .

At step 208, the bypass control unit 105 controls the corresponding bypass circuits B1 to Bn so that the fully charged storage battery cells C1 to Cn are cut off. Step 208 transfers to step 202 .

On the other hand, in step 209, current control section 104 stops charging. Next, at step 210, the bypass control section 105 turns off the switches S1 and S2 of all the bypass circuits B1 to Bn. Next, at step 211, the bypass control section 105 turns ON the switches S2 of all the bypass circuits B1 to Bn. Thus, the processing shown in FIG. 4 ends.

As described above, in the charging control of this modification, the storage battery cell Cmin having the smallest charging current limit value Ic among the plurality of storage battery cells C1 to Cn is bypassed, and the other storage battery cells C1 to Cn are connected in series. do. This makes it possible to increase the charging power limit value Pc in the storage system 1 compared to the case where all the storage battery cells C1 to Cn are connected in series.

FIG. 5 is a flowchart for explaining a modification of discharge control by the storage battery control device 100 shown in FIG. The process shown in this flowchart is started when the power storage system 1 is set to the discharge mode, and the process proceeds to step 301 .

At step 301, the bypass control unit 105 turns off the switches S1 and S2 of all the bypass circuits B1 to Bn. Next, in step 302, the current limit value calculator 102 calculates discharge current limit values Id for all the storage battery cells C1 to Cn.

Next, in step 303, the bypass control unit 105 excludes the storage battery cell Cmin having the minimum discharge current limit value Id from among the plurality of storage battery cells C1 to Cn, and selects the other storage battery cells C1 to Cn. . Step 303 moves to step 304 .

At step 304, the bypass control unit 105 controls the bypass circuits B1 to Bn so that the selected storage battery cells C1 to Cn are connected and the storage battery cell Cmin with the smallest discharge current limit value Id is cut off. Next, in step 305, the current control unit 104 outputs a current equal to or less than the minimum value among the discharge current limit values Id of the connected storage battery cells C1 to Cn from the connected storage battery cells C1 to Cn. .

Next, in step 306, the bypass control unit 105 determines whether or not there is a storage battery cell C1-Cn that has reached the discharge end voltage (discharge is completed) among all the storage battery cells C1-Cn. If an affirmative determination is made in this step, the process proceeds to step 307 , and if a negative determination is made in this step, the process proceeds to step 302 .

At step 307, the bypass control unit 105 determines whether or not the voltages V of all the storage battery cells C1 to Cn have reached the final discharge voltage (whether or not the discharge has been completed). If an affirmative determination is made in this step, the process proceeds to step 309 , and if a negative determination is made in this step, the process proceeds to step 308 .

At step 308, the bypass control unit 105 controls the bypass circuits B1 to Bn so that the discharged storage battery cells C1 to Cn are cut off. Step 308 transfers to step 302 .

On the other hand, in step 309, the current control section 104 stops discharging. Next, at step 310, the bypass control section 105 turns off the switches S1 and S2 of all the bypass circuits B1 to Bn. Next, in step 311, the bypass control section 105 turns ON the switches S2 of all the bypass circuits B1 to Bn. With this, the processing shown in FIG. 5 ends.

As described above, in the discharge control of this modification, the storage battery cell Cmin having the smallest discharge current limit value Id among the plurality of storage battery cells C1 to Cn is bypassed, and the other storage battery cells C1 to Cn are connected in series. do. As a result, it is possible to increase the charge/discharge power in the storage system 1 as compared to the case where all the storage battery cells C1 to Cn are connected in series.

As described above, the present invention has been described based on the embodiments, but the present invention is not limited to the above embodiments, and modifications may be made without departing from the scope of the present invention. may be combined.

For example, in the above embodiment, the present invention has been described by taking as an example the power storage system 1 including a single power supply system 10 having a bypass function. It is also applicable to systems.

Moreover, in the above embodiment, the discharge current is controlled to be equal to or less than the minimum value of the discharge current limit value Id during discharge, but this is not essential. For example, the discharge current is made to naturally decrease as the load becomes lighter. The discharge current may be controlled below the minimum value of the discharge current limit value Id.

1: Power storage system 100: Storage battery control devices B1 to Bn: Bypass circuits C1 to Cn: Storage battery cell Cmin: Storage battery cell Ic: Charging current limit value (current limit value)
Id: discharge current limit value (current limit value)
Pc: charging power (input power)
Pd: discharge power (output power)
V: Voltage

Claims (7)

A storage battery control device for controlling a power storage system,
The power storage system is
a plurality of storage batteries connected in series and each having a current limit set;
each comprising a plurality of bypass circuits that cut off the storage battery by bypassing the storage battery,
The storage battery control device is arranged such that input power or output power of the storage battery connected without interruption by the bypass circuit is larger than when all the storage batteries are connected without interruption by the bypass circuit. , a storage battery control device for controlling disconnection and connection of the storage battery by the bypass circuit; The storage battery control device according to claim 1, wherein disconnection and connection of the storage battery by the bypass circuit is controlled such that the input power or the output power of the storage battery connected without being disconnected by the bypass circuit is maximized. . The storage battery control device sets the input current or the output current of the storage battery connected without interruption by the bypass circuit to the minimum of the current limit values set for the storage battery connected without interruption by the bypass circuit. 3. The storage battery control device according to claim 1 or 2, wherein control is performed below a value. The input power or the output power of the storage battery connected without interruption by the bypass circuit is the minimum value among the current limit values set for the storage battery connected without interruption by the bypass circuit, and 4. The storage battery control device according to claim 3, wherein the product is the sum of the voltages of the storage batteries connected without being cut off by a bypass circuit. The input power or output power of the storage battery connected without being cut off by the bypass circuit is preferentially cut off by the bypass circuit to the storage battery whose current limit value is relatively small compared to the other storage batteries. 5 . a plurality of storage batteries connected in series;
a plurality of bypass circuits, each bypassing the storage battery to cut off the storage battery;
A storage battery control device that controls the bypass circuit and sets a current limit value for the storage battery,
The storage battery control device is arranged such that input power or output power of the storage battery connected without interruption by the bypass circuit is larger than when all the storage batteries are connected without interruption by the bypass circuit. , an electric storage system for controlling disconnection and connection of the storage battery by the bypass circuit; A storage battery control method using a storage battery control device that controls a storage battery system,
The power storage system is
a plurality of storage batteries connected in series and each having a current limit set;
each comprising a plurality of bypass circuits that cut off the storage battery by bypassing the storage battery,
The input power or the output power of the storage battery connected without interruption by the bypass circuit is increased compared to the case where all the storage batteries are connected without interruption by the bypass circuit. A storage battery control method for controlling disconnection and connection of a storage battery.

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