JP7097456B2 - Power storage system and charge control method - Google Patents

Description

The present invention relates to a power storage system and a charge control method, for example, a power storage system that controls charging of a lead storage battery, and a charge control method that controls charging of a lead storage battery.

Lead-acid batteries deteriorate in capacity due to repeated charging and discharging for a long period of time. In a power storage system using a lead-acid battery, uniform charging is performed to make the lead-acid battery fully charged in order to remove sulfation, which is one of the causes of deterioration of the lead-acid battery.

In recent years, due to the demand for larger capacity of lead-acid batteries, a single lead-acid battery cell (single battery) or a multi-parallel storage battery in which a plurality of storage battery rows (strings) in which a plurality of lead-acid battery cells are connected in series are connected in parallel is provided. Power storage systems are becoming widespread.

In a conventional power storage system equipped with a multi-parallel storage battery, uniform charging is managed for the entire multi-parallel storage battery. Therefore, due to the characteristics (internal resistance) and temperature of the lead-acid battery cell itself in each storage battery row, the charging current flowing between the storage battery rows varies during uniform charging, resulting in overcharging or insufficient charging. However, there is a problem that the deterioration of the multi-parallel storage battery progresses.

As a conventional technique for solving this problem, a charge / discharge control device (chopper) that controls the charge / discharge amount between an AC / DC converter (PCS: Power Conditioning System, hereinafter also referred to as “PCS”) and a storage battery row. Is known, and the charge / discharge control device connected to each storage battery row adjusts the charge / discharge amount of the corresponding storage battery row to prevent overcharging or insufficient charging during uniform charging. (See Patent Document 1).

Japanese Patent No. 6247039

However, in the prior art disclosed in Patent Document 1 described above, it is necessary to provide a charge / discharge control device for adjusting the charge / discharge amount of each storage battery row for each storage battery row, which causes a problem that the cost of the power storage system increases. There is.

The inventors of the present application have studied a new charge control method in order to solve the above-mentioned problems.

FIG. 9 is a diagram for explaining a charge control method examined by the inventors of the present application prior to the present application.

In this charge control method, in a power storage system 900 having a plurality of storage battery rows 90_1 to 90_1 connected in parallel, switches 92_1 to 92_10 are provided between each storage battery row 90_1 to 90_1 and PCS91, and uniform charging is completed. This is a method of preventing overcharging of each storage battery row 90_1 to 90_1 by disconnecting the rows 90_1 to 90_1 from the PCS91.

In the following description, when the storage battery rows 90_1 to 90_1 and the switches 92_1 to 92_1 are not particularly distinguished, the suffix of the reference numeral may be omitted and the term “storage battery row 90” or the like may be used.

For example, as shown in FIG. 9, in a power storage system having 10 sets of storage battery rows 90_1 to 90_1, switches 92_1 to 92_10 are arranged between each storage battery row 90_1 to 90_1 and PCS91, respectively. When performing uniform charging of the storage battery rows 90_1 to 90_1, first, all the switches 92_1 to 92_1 are turned on to charge all the storage battery rows 90_1 to 90_1. During charging, the charging state of each storage battery row 90_1 to 90_110 is monitored. Then, the switch 92 connected to the storage battery row 90 determined to have completed uniform charging is turned off, and the storage battery row 90 is disconnected from the PCS 91.

According to this method, it is possible to prevent overcharging of each storage battery row. However, it became clear that this method has the following new problems.

FIG. 10 is a diagram showing changes in the voltage of each storage battery row when uniform charging is controlled by the charging control method examined prior to the present application by the inventors of the present application.

In FIG. 10, in the power storage system 900 having 10 sets of storage battery rows 90_1 to 90_1 shown in FIG. 9, the storage battery rows 90_1 are controlled by controlling the switches 92_1 to 92_1 during constant voltage charging (CV charging) in uniform charging. The voltage waveforms of the storage battery rows 90_1 to 90_1 when the storage battery rows 90_9 are disconnected from the PCS91 at regular time intervals are shown. Reference numerals 901 to 909 represent the respective voltages of the storage battery rows 90_1 to 90_1 after disconnection, and reference numerals 910 represent the voltages of the remaining storage battery rows 90_1 to 90_1 connected to the PCS 91.

As can be seen from FIG. 10, when one storage battery row 90 is disconnected, the voltage of the remaining storage battery row 90 connected to the PCS 91 fluctuates and temporarily exceeds the upper limit voltage of the storage battery row 90 to overvoltage. Will be. Then, as the number of the storage battery rows 90 connected to the PCS 91 decreases, the fluctuation range of the voltage of the remaining storage battery rows 90 generated when the storage battery rows 90 is disconnected increases, and finally the upper limit voltage increases. It will exceed the overvoltage.

The inventors of the present application have considered that the cause of this phenomenon is that the impedance of the entire storage battery as seen from the PCS91 side changes before and after the disconnection of the storage battery row 90.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a simpler configuration in a power storage system including a multi-parallel storage battery, and to change the charging state between storage battery rows by uniform charging. The purpose is to suppress and realize more reliable uniform charging.

The power storage system according to a typical embodiment of the present invention is a multi-parallel storage battery in which a plurality of storage battery rows including at least one lead storage battery cell are connected in parallel, and an AC / DC conversion device that controls the transfer of power of the multi-parallel storage battery. A first switch, which is provided corresponding to each storage battery row and is connected in series between the corresponding storage battery row and the AC / DC conversion device, and a first switch corresponding to each storage battery row, corresponding to each other. An impedance circuit having a predetermined impedance connected in parallel with the first switch between the storage battery row and the AC / DC conversion device, and an impedance circuit provided corresponding to each storage battery row and connected in series with the impedance circuit. , The state of the second switch connected in parallel with the first switch together with the impedance circuit and the storage battery row is monitored for each storage battery row, and the on / off of the first switch and the second switch is controlled. The control device includes a control device, and the control device fills the storage battery row by turning on the first switch with the second switch turned off and supplying power from the AC / DC conversion device to the storage battery row. In addition to performing uniform charging to bring the battery into a charged state, it was determined for each storage battery row whether or not the uniform charging was completed, and the second switch of the storage battery row determined to be completed was turned on. It is characterized in that the first switch of the storage battery row is turned off in the state.

According to the power storage system having multiple parallel storage batteries according to the present invention, it is possible to realize more reliable uniform charging while suppressing the variation in the charging state between the storage battery rows due to uniform charging with a simpler configuration. Become.

It is a figure which shows the structure of the power storage system which concerns on one Embodiment of this invention. It is a figure which shows an example of the structure of an impedance circuit. It is a figure which shows another example of the structure of an impedance circuit. It is a flow diagram which shows the flow of the charge control method at the time of equal charge in the power storage system which concerns on embodiment. It is a figure for demonstrating the charge control method at the time of equal charge in the power storage system which concerns on embodiment. It is a figure for demonstrating the charge control method at the time of equal charge in the power storage system which concerns on embodiment. It is a figure for demonstrating the charge control method at the time of equal charge in the power storage system which concerns on embodiment. It is a figure for demonstrating the charge control method at the time of equal charge in the power storage system which concerns on embodiment. It is a timing chart which shows the charge current and the discharge current of the storage battery row (lead-acid battery) at the time of equal charge. It is a figure which shows the relationship between the charge current of a storage battery row and a charge state (SOC) in a constant voltage charge period at the time of uniform charge by a constant voltage-constant current charge system or constant power-constant current charge system. It is a figure which shows an example of the temporal change of the charge current flowing through each storage battery row at the time of equal charge by a constant current-constant voltage charging method. It is a figure which shows the time-dependent change of the internal impedance of one storage battery row at the time of constant voltage charge in uniform charge. It is a figure for demonstrating the charge control method which the inventors of this application examined prior to this application. It is a figure which shows the change of the voltage of each storage battery row when the uniform charge is controlled by the charge control method which the inventors of this application examined prior to this application.

1. 1. Outline of Embodiment First, an outline of a typical embodiment of the invention disclosed in the present application will be described. In the following description, as an example, reference numerals on the drawings corresponding to the components of the invention are described in parentheses.

[1] The power storage system (100) according to a typical embodiment of the present invention is a multi-parallel connection in which a plurality of storage battery rows (20,20_1 to 20_n) including at least one lead storage battery cell (200) are connected in parallel. The storage battery (2), the AC / DC conversion device (3) that controls the transfer of power of the multi-parallel storage battery, and the AC / DC conversion device that is provided corresponding to each storage battery row and corresponds between the storage battery row and the AC / DC conversion device. The first switch (4A_1 to 4A_n) connected in series is provided corresponding to each storage battery row, and is connected in parallel with the first switch between the corresponding storage battery row and the AC / DC conversion device. An impedance circuit (5,5-1 to 5_n) having a predetermined impedance is provided corresponding to each storage battery row, is connected in series with the impedance circuit, and is connected in parallel with the first switch together with the impedance circuit. The second switch (4B_1 to 4B_n) and a control device (1) for monitoring the state of the storage battery row for each storage battery row and controlling the on / off of the first switch and the second switch are provided. The control device is evenly charged to fully charge the storage battery row by turning on the first switch with the second switch turned off and supplying power from the AC / DC conversion device to the storage battery row. At the same time, it is determined for each storage battery row whether or not the uniform charging is completed, and the second switch of the storage battery row determined that the uniform charging is completed is turned on. A power storage system characterized by turning off one switch.

[2] In the power storage system, the impedance circuit may include resistances (R, R1, R2).

[3] In the power storage system, the impedance circuit may include a capacitor (C).

[4] The charge control method according to a typical embodiment of the present invention includes a multi-parallel storage battery (2) in which a plurality of storage battery rows (20_1 to 20_n) including at least one lead storage battery cell (200) are connected in parallel. An AC / DC conversion device (3) that controls the transfer of power of the multi-parallel storage battery, and an AC / DC conversion device (3) provided corresponding to each storage battery row, connected in series between the corresponding storage battery row and the AC / DC conversion device. The first switch (4A_1 to 4A_n) and the storage battery row are provided corresponding to each other, and have a predetermined impedance connected in parallel with the first switch between the corresponding storage battery row and the AC / DC conversion device. A second switch (4B_1) provided corresponding to each of the storage battery rows and the impedance circuit (5.5_1 to 5_n), connected in series with the impedance circuit, and connected in parallel with the first switch together with the impedance circuit. ~ 4B_n) and the multi-parallel in a power storage system including a control device (1) that monitors the state of the storage battery row for each storage battery row and controls the on / off of the first switch and the second switch. This is a charging control method for storage batteries. In this charge control method, the control device fully charges the storage battery row by turning on the first switch with the second switch turned off and supplying power from the AC / DC conversion device to the storage battery row. The first step (S1) for starting uniform charging for the state, the second step (S2) for the control device to determine whether or not the uniform charging is completed for each storage battery row, and the control. The apparatus is characterized by including a third step (S3, S4) of turning off the first switch with the second switch of the storage battery row determined to have completed the uniform charging turned on.

[5] In the charge control method, the impedance circuit may include resistances (R, R1, R2).

[6] In the charge control method, the impedance circuit may include a capacitor (C).

2. 2. Specific Examples of Embodiments Hereinafter, specific examples of embodiments of the present invention will be described with reference to the drawings. In the following description, the same reference numerals will be given to the components common to each embodiment, and the repeated description will be omitted. In addition, it should be noted that the drawings are schematic, and the relationship between the dimensions of each element, the ratio of each element, etc. may differ from the reality. Even between the drawings, there may be parts where the relationship and ratio of the dimensions are different from each other.

<< Embodiment 1 >>
FIG. 1 is a diagram showing a configuration of a power storage system according to an embodiment of the present invention.
The power storage system 100 shown in the figure is, for example, a power storage system including a lead storage battery for cycle use. For example, the power storage system 100 supplies power to the load 6 from the power supply unit 7 (commercial power supply) during normal operation, and supplies power to the load 6 from the lead storage battery for power supply backup when a power failure occurs.

The power supply unit 7 is a functional unit that supplies electric power to the power storage system 100 and the load 6. The power supply unit 7 is, for example, a commercial power source. In addition to the commercial power source, the power supply unit 7 may have a power generation facility that generates electric power based on renewable energy such as photovoltaic power generation (PV: Photovoltaics).

The power storage system 100 includes a storage battery module 2, an AC / DC conversion device 3, switches 4A_1 to 4A_n (n is an integer of 2 or more), switches 4B_1 to 4B_n, impedance circuits 5_1 to 5_n, and a control device 1.

Hereinafter, when the switches 4A_1 to 4A_n, the switches 4B_1 to 4B_n, the impedance circuits 5_1 to 5_n, and the like are not particularly distinguished, the suffix of the reference code may be omitted and referred to as "switch 4A" or the like.

The storage battery module 2 includes a lead storage battery configured to be able to charge and discharge electric power. The storage battery module 2 is a multi-parallel storage battery in which a plurality of storage battery rows including at least one lead storage battery cell are connected in parallel.

Specifically, as shown in FIG. 1, the storage battery module 2 has a structure in which a plurality of storage battery rows 20_1 to 20_n in which m (m is an integer of 1 or more) lead storage battery cells 200 are connected in series are connected in parallel. have. Hereinafter, the storage battery module 2 is also referred to as a “multi-parallel storage battery 2”.

Further, the storage battery module 2 includes a voltage sensor 201 that measures the output voltage (storage voltage) of each storage battery row 20_1 to 20_n, and a current sensor 202 that measures the charge current and the discharge current of each storage battery row 20_1 to 20_n. It has every row 20_1 to 20_n.

The AC / DC converter (hereinafter, also referred to as “PCS (Power Conditioning System)”) 3 is controlled by a control device 1 described later, and converts power between the power supply unit 7, the storage battery module 2, and the load 6. It is a power conversion unit that controls the transfer of electric power between the power supply unit 7, the storage battery module 2, and the load 6.

For example, the PCS 3 converts alternating current power (AC) from the power supply unit 7 into direct current power (DC) and supplies it to the storage battery module 2. The PCS3 includes, for example, a DC / DC converter, an AC / DC converter (AC / DC), a switch circuit, and the like.

The switches 4A_1 to 4A_n (first switch) are components for switching connection and disconnection between the PCS 3 and the multi-parallel storage battery 2. As shown in FIG. 1, the switches 4A_1 to 4A_n are provided corresponding to each of the storage battery rows 20_1 to 20_n, and are connected in series between the corresponding storage battery rows 20_1 to 20_n and the PCS3. The switches 4A_1 to 4A_n are, for example, electromagnetic switches (relays).

The switches 4B_1 to 4B_n (second switch) are components for switching the connection and disconnection of the impedance circuit 5 between the PCS 3 and the multi-parallel storage battery 2.
As shown in FIG. 1, the switches 4B_1 to 4B_n are provided corresponding to each of the storage battery rows 20_1 to 20_n, and are connected in series between the corresponding storage battery rows 20_1 to 20_n and the PCS3. Specifically, the switches 4B_1 to 4B_n are connected in series with the corresponding impedance circuits 5_1 to 5_n, and are connected in parallel with the corresponding switches 4A_1 to switches 4A_n together with the corresponding impedance circuits 5_1 to 5_n. The switches 4B_1 to 4B_n are, for example, electromagnetic switches (relays).

Impedance circuits 5_1 to 5_n are circuits having a predetermined impedance. Impedance circuits 5_1 to 5_n are provided corresponding to each of the storage battery rows 20_1 to 20_n. The impedance circuits 5_1 to 5_n are connected in series with the corresponding switches 4B_1 to 4B_n between the corresponding storage battery rows 20_1 to 20_n and the PCS3, and are connected in parallel with the switches 4A_1 to 4A_n together with the switches 4B_1 to 4B_n. ..

The impedance circuit 5 is not particularly limited as long as it is a circuit having a predetermined impedance. For example, the impedance circuit 5 may include at least one of a resistor, a capacitor, and an inductor, and may be designed so that the impedance of the entire impedance circuit 5 becomes a predetermined value.

2A and 2B are diagrams showing an example of the configuration of the impedance circuit 5.
As shown in FIG. 2A, the impedance circuit 5 may be composed of a resistor (element) R, or may include a resistor and at least one capacitor as shown in FIG. 2B. Here, the capacitor is connected in parallel with the resistor. For example, FIG. 2B shows an impedance circuit 5 having a resistor R1, a capacitor C connected in parallel to the resistor R1, and a resistor R1 and a resistor R2 connected in series with the capacitor C.

The control device 1 is a device that comprehensively controls the entire power storage system 100. The control device 1 monitors the state of each storage battery row 20_1 to 20_n for each storage battery row 20_1 to 20_n, and can individually control the on / off of the switches 4A_1 to 4A_n and the switches 4B_1 to 4B_n.

As shown in FIG. 1, the control device 1 includes a monitoring unit 11, a storage battery management unit 12, and a switch control unit 13.

The monitoring unit 11 is a data processing device that sequentially acquires physical quantities measured by the voltage sensor 201 and the current sensor 202 of the multi-parallel storage battery 2 and monitors the state of the multi-parallel storage battery 2 based on the physical quantities. The monitoring unit 11 is, for example, a BMU (Battery Management Unit).

The storage battery management unit 12 is a device that controls the overall control of each component of the power storage system 100. The storage battery management unit 12 is, for example, an EMS (Energy Management System).
Specifically, the storage battery management unit 12 controls charge / discharge of the multi-parallel storage battery 2 by driving the PCS 3. For example, the storage battery management unit 12 uses various charging methods such as a constant current-constant voltage charging (CCCV) method and a constant power-constant voltage charging method based on the monitoring result of the multi-parallel storage battery 2 by the monitoring unit 11. Perform equal charge of 2.

Here, in the constant current-constant voltage charging (CCCV) method, charging of the storage battery rows 20_1 to 20_n is started by a constant current, and after the voltage of the storage battery rows 20_1 to 20_n reaches a predetermined voltage, the storage battery rows are charged by a constant voltage. It is a charging method for charging 20_1 to 20_n.

Further, in the constant power --- constant voltage charging method, charging of the storage battery rows 20_1 to 20_n is started by constant power, and after the voltage of the storage battery rows 20_1 to 20_n reaches a predetermined voltage, the storage battery rows 20_1 to 20_n are charged by the constant voltage. It is a charging method to charge.

The switch control unit 13 is a functional unit that switches on / off of the switches 4A_1 to 4A_n and the switches 4B_1 to 4B_n in response to an instruction from the monitoring unit 11 or the storage battery management unit 12.
For example, when the switches 4A_1 to 4A_n and the switches 4B_1 to 4B_n are relays, the switch control unit 13 generates a drive signal for switching on / off of the relay according to an instruction from the monitoring unit 11 or the storage battery management unit 12. It is a signal generation circuit.

The monitoring unit 11 and the storage battery management unit 12 include, for example, a processor such as a CPU (Central Processing Unit), a storage device such as a RAM (Random Access Memory) or a ROM (Read Only Memory), and an I / F as hardware resources. In a data processing device (computer) having peripheral circuits such as circuits, the processor executes various operations according to a program stored in the storage device to control peripheral circuits and the like.

The control device 1 periodically executes uniform charging to fully charge the storage battery rows 20_1 to 20_n of the multi-parallel storage battery 2 in order to prevent deterioration of the lead storage batteries constituting the multi-parallel storage battery 2.

The control device 1 turns on the switches 4A_1 to 4A_n with the switches 4B_1 to 4B_n turned off to supply electric power from the PCS 3 to the storage battery rows 20_1 to 20_n to fully charge the storage battery rows 20_1 to 20_n. The storage battery is charged evenly, and it is determined whether or not the equal charging is completed for each of the storage battery rows 20_1 to 20_n. The switches 4A_1 to 4A_n in columns 20_1 to 20_n are turned off.

Hereinafter, the charge control method at the time of uniform charge in the power storage system 100 will be described in detail with reference to the drawings.

FIG. 3 is a flow chart showing a flow of a charge control method at the time of uniform charge in the power storage system 100. 4A to 4D are diagrams for explaining a charge control method at the time of uniform charging in the power storage system 100.

Here, as shown in FIGS. 4A to 4D, the multi-parallel storage battery 2 in the power storage system 100 has three storage battery rows 20_1 to 20_3 having four (m = 4) lead storage battery cells 200 connected in series. The case of having a structure connected in parallel will be described as an example.

Further, in FIGS. 4A to 4D, the charging currents of the storage battery rows 20_1 to 20_3 during uniform charging are set to I1, I2, and I3, respectively, and I2> I1> I3 due to variations in the characteristics of the storage battery rows 20_1 to 20___. Suppose there is. In FIGS. 4A to 4D, the voltage sensor 201 and the current sensor 202 are not shown.

First, as shown in FIG. 4A, the control device 1 controls the switches 4A_1 to 4A_3 and the switches 4B_1 to 4B_3 to supply electric power from the PCS3 to the storage battery rows 20_1 to 20___ to uniformly charge the storage battery rows 20_1 to 20_3. Is started (step S1).

For example, the monitoring unit 11 requests the storage battery management unit 12 to execute uniform charging. The storage battery management unit 12 first turns off (or confirms that the switches 4B_1 to 4B_3) the switches 4B_1 to 4B_3 via the switch control unit 13 in response to a request from the monitoring unit 11. Next, the storage battery management unit 12 turns on (or confirms that the switches 4A_1 to 4A_3) the switches 4A_1 to 4A_3 via the switch control unit 13. Then, the storage battery management unit 12 drives the PCS3 so as to perform uniform charging by a predetermined charging method (for example, constant current-constant voltage charging method), and starts supplying power to the storage battery rows 20_1 to 20___.

Next, the control device 1 determines whether or not there are storage battery rows 20_1 to 20_3 for which uniform charging has been completed (step S2). Specifically, the monitoring unit 11 measures the voltage (output voltage) and current of each storage battery row 20_1 to 20_1 acquired from the voltage sensor 201 and the current sensor 202 of each storage battery row 20_1 to 20_3, based on the measurement result of the storage battery row. It is determined whether or not the uniform charging of 20_1 to 20_1 is completed. The specific determination method will be described later.

In step S2, when the storage battery rows 20_1 to 20_3 for which uniform charging has been completed do not exist, the control device 1 continues equal charging of each storage battery row 20_1 to 20_3.

On the other hand, in step S2, when the storage battery rows 20_1 to 20_3 for which uniform charging has been completed exists, the control device 1 turns on the switches 4B_1 to 4B_3 of the storage battery rows 20_1 to 20_3 for which uniform charging has been completed (step S3). ..

For example, in the case of the above example, since the charging currents of the storage battery rows 20_1 to 20_3 during uniform charging are in the relationship of I2> I1> I3, the storage battery row 20_2 having the largest charging current I2 is first fully charged and is evenly charged. Charging is complete. When the monitoring unit 11 determines that the uniform charging of the storage battery row 20_2 is completed, the monitoring unit 11 notifies the storage battery management unit 12 of that fact. Upon receiving the notification, the storage battery management unit 12 instructs the switch control unit 13 to close control (ON) the switch 4B_2, and as shown in FIG. 4B, the switch control unit 13 closes and controls the switch 4B_2. The impedance circuit 5 is connected between the storage battery row 20_2 and the PCS3.

Next, the control device 1 turns off the switches 4A_1 to 4A_3 of the storage battery rows 20_1 to 20_3 for which uniform charging is completed (step S4). For example, in the case of the above example, after confirming that the switch 4B_2 is in the ON state, the storage battery management unit 12 instructs the switch control unit 13 to open-control (turn off) the switch 4A_2, and FIG. 4B As shown in the above, the switch control unit 13 opens and controls the switch 4A_2.

At this time, since the storage battery row 20_2 is connected to the PCS3 via the impedance circuit 5_2, the impedance value of the storage battery row 20_2 seen from the PCS3 side is higher than the impedance values of the other storage battery rows 20_1 and 20___. Therefore, by setting the impedance of the impedance circuit 5_2 to an appropriate value, it is possible to suppress the current I2 flowing in the storage battery row 20_2 to almost 0 A. That is, it is possible to stop charging the storage battery row 20_2.

Further, the parameters (impedance) of the entire storage battery (multi-parallel storage battery 2) seen from the PCS3 at this time are compared with the case where the storage battery row 20_2 is completely separated from the PCS3 as in the above-mentioned prior study example (see FIG. 9). It doesn't change much. That is, by setting the impedance of the impedance circuit 5_2 to an appropriate value, it is possible to suppress the change in the impedance of the entire storage battery as seen from the PCS3 before and after the disconnection of the storage battery row 20_2 (before and after the switching of the switches 4A_2 and 4B_2). This makes it possible to satisfactorily adjust the voltage and current of the remaining storage battery rows 20_1 and 20_3 that have not been fully charged during uniform charging.

Next, the control device 1 determines whether or not uniform charging of all the storage battery rows 20_1 to 20_3 is completed (step S5). If the uniform charging of all the storage battery rows 20_1 to 20_3 is not completed, the process returns to step S2, and the above-mentioned processes from step S2 to step S5 are executed again.

For example, after the uniform charging of the storage battery row 20_2 is completed and the storage battery row 20_2 is disconnected from the PCS3, the charging currents of the storage battery rows 20_1 and 20_3 during uniform charging are in the relationship of I1> I3. Therefore, the storage battery row 20_1 is fully charged next to the storage battery row 20_1. When the monitoring unit 11 determines that the uniform charging of the storage battery row 20_1 is completed, the monitoring unit 11 notifies the storage battery management unit 12 of that fact. Upon receiving the notification, the storage battery management unit 12 instructs the switch control unit 13 to close (turn on) the switch 4B_1, and as shown in FIG. 4C, the switch control unit 13 that receives the instruction switches. 4B_1 is closed and controlled, and the impedance circuit 5_1 is connected between the storage battery row 20_1 and the PCS3.

Next, after confirming that the switch 4B_1 is in the ON state, the storage battery management unit 12 instructs the switch control unit 13 to open-control (turn off) the switch 4A_1, and as shown in FIG. 4C, The switch control unit 13 opens and controls the switch 4A_1.

At this time, since the storage battery row 20_1 is connected to the PCS3 via the impedance circuit 5_1, the impedance of the storage battery row 20_1 seen from the PCS3 side is that of the other storage battery row 20_1, as in the case of the storage battery row 20_1 described above. It is higher than the impedance, and the change in the impedance of the entire storage battery as seen from the PCS3 can be suppressed before and after the disconnection of the storage battery row 20_1 (before and after the switching of the switches 4A_1 and 4B_1).

Therefore, by setting the impedance of the impedance circuit 5_1 to an appropriate value, it is possible to suppress the current I1 flowing through the storage battery row 20_1 to almost 0 A to prevent overcharging of the storage battery row 20_1, and the charge is not fully charged. It becomes possible to satisfactorily control the voltage and current at the time of equal charge of the remaining storage battery rows 20_3.
Immediately after this, even charging of the storage battery row 20_3 is still continued, so the process returns to step S2 again.

When the storage battery row 20_3 is fully charged, the monitoring unit 11 notifies the storage battery management unit 12 that the uniform charging of the storage battery row 20_3 is completed. Upon receiving the notification, the storage battery management unit 12 instructs the switch control unit 13 to close control (ON) the switch 4B_3, and as shown in FIG. 4D, the switch control unit 13 closes and controls the switch 4B_3. Then, the impedance circuit 5_3 is connected between the storage battery row 20_3 and the PCS3.

Next, after confirming that the switch 4B_3 is in the ON state, the storage battery management unit 12 instructs the switch control unit 13 to open-control (turn off) the switch 4A_3, and as shown in FIG. 4D, the storage battery management unit 12 instructs the switch control unit 13 to open control (OFF). The switch control unit 13 opens and controls the switch 4A_3 to disconnect the storage battery row 20_3 from the PCS3.
As a result, uniform charging of all the storage battery rows 20_1 to 20_3 is completed.

In step S5, when the control device 1 determines that the uniform charging of all the storage battery rows 20_1 to 20_3 is completed, the control device 1 ends the control for equal charging of the multi-parallel storage battery 2 (step S6).

As described above, in the power storage system 100 according to the present embodiment, the multi-parallel storage battery 2 is uniformly charged by the above procedure. After the uniform charging is completed, the control device 1 closes (turns on) the switches 4A_1 to 4A_3 of each storage battery row 20_1 to 20___, and then opens (turns off) the switches 4B_1 to 4B_3 of each storage battery row 20_1 to 20___. Control is performed to return the power storage system 100 to the original state.

Next, a method for determining the completion of uniform charging will be described.
Two examples are shown below as a method for determining the completion of uniform charging according to the present embodiment.

First, a first example of a method for determining the completion of uniform charging by the power storage system 100 will be described.
As a first example, in the control device 1, the integrated value of the charging current of the storage battery row 20 since the last uniform charging is completed and the discharge current of the storage battery row 20 since the last uniform charging is completed. When the ratio with the integrated value becomes a predetermined value, it is determined that the uniform charging of the storage battery row 20 is completed.

FIG. 5 is a timing chart showing the charging current and the discharging current of the storage battery row 20 (lead-acid battery) at the time of uniform charging. In FIG. 5, the vertical axis represents current and the horizontal axis represents time. Further, reference numeral 302 represents a charging current of the storage battery row 20, and reference numeral 303 represents a discharging current of the storage battery row 20.

First, the monitoring unit 11 of the control device 1 starts integrating the charging current and the discharging current for each of the storage battery rows 20_1 to 20_n at the timing when the uniform charging is completed. For example, in FIG. 5, at the time t31 when uniform charging is completed, the monitoring unit 11 starts integrating the charging currents of the storage battery rows 20_1 to 20_n and also starts integrating the discharge currents of the storage battery rows 20_1 to 20_n. ..

Next, the monitoring unit 11 calculates the ratio between the integrated value of the charge current and the integrated value of the discharge current for each of the storage battery rows 20_1 to 20_n. Specifically, the ratio of the integrated value of the charge current to the integrated value of the discharge current is calculated.

Next, the monitoring unit 11 determines whether or not the calculated ratio has reached the ratio reference value for each of the storage battery rows 20_1 to 20_n.

Here, the ratio reference value is a value that serves as a reference for determining the end of the constant voltage charging period in uniform charging. In general, uniform charging is overcharged so as to be 100% or more (for example, 104%) with respect to the discharge capacity. Therefore, the ratio reference value is preferably set to a value exceeding 100%, for example, a value in the range of 101% to 104%.

When there is no storage battery row 20 whose ratio reaches the ratio reference value, the monitoring unit 11 continues to integrate the charge current and the discharge current for each of the storage battery rows 20_1 to 20_n. On the other hand, when there is a storage battery row 20 whose calculated ratio has reached the ratio reference value, the monitoring unit 11 determines that the uniform charging of the storage battery row 20 whose calculated ratio has reached the ratio reference value has been completed. The monitoring unit 11 repeatedly executes the above process until a determination result indicating that uniform charging is completed for all the storage battery rows 20_1 to 20_n is obtained.

By executing the data processing in the above procedure, it is possible to determine whether or not the uniform charging is completed for each of the storage battery rows 20_1 to 20_n.

Next, a second example of a method for determining the completion of uniform charging by the power storage system 100 will be described.
As a second example, in the control device 1, the storage battery row 20 is charged when the charging current of the storage battery row 20 decreases to a predetermined value during the constant voltage charging period in which the storage battery row 20 is charged by the constant voltage in uniform charging. It is determined that the uniform charging is completed.

FIG. 6 shows the charging current and the charging state (SOC: State of Charge) of the storage battery row 20 during the constant voltage charging period when uniform charging is performed by the constant voltage-constant current charging method or the constant power-constant current charging method. It is a figure which shows the relationship.

As shown in FIG. 6, when charging at a constant voltage, the storage battery tends to have a smaller charging current as it approaches full charge. Therefore, it is possible to detect the completion of uniform charging by monitoring the charging current for each storage battery row 20 during the constant voltage charging period in uniform charging. For example, the monitoring unit 11 determines that uniform charging is completed when the charging current of each storage battery row 20_1 to 20_n decreases and reaches a predetermined threshold value Is during the constant voltage charging period.

FIG. 7 is a diagram showing an example of a temporal change in the charging current flowing through each storage battery row when uniform charging is performed by the constant current-constant voltage charging method.
As described above, in the storage battery rows 20_1 to 20_3, the charging current at the time of constant current charging may vary depending on the temperature and the characteristics (internal resistance) of the lead storage battery cell 200 itself. For example, consider the case where I2>I1> I3 as in the above example.

The monitoring unit 11 of the control device 1 monitors the charging current of each storage battery row 20_1 to 20_3. In the case of the above example, since I2> I1> I3, the charging current I2 of the storage battery row 20_2 first reaches the threshold value Is. When the monitoring unit 11 detects that the charging current I2 of the storage battery row 20_2 has reached the threshold value Is, it determines that the uniform charging of the storage battery row 20_2 is completed.

Next, since I1> I3, the charging current I1 of the storage battery row 20_1 then reaches the threshold value Is. When the monitoring unit 11 detects that the charging current I1 of the storage battery row 20_1 has reached the threshold value Is, it determines that the uniform charging of the storage battery row 20_1 is completed.

Finally, the charging current I3 of the storage battery row 20_3 then reaches the threshold Is. When the monitoring unit 11 detects that the charging current I3 of the storage battery row 20_3 has reached the threshold value Is, it determines that the uniform charging of the storage battery row 20_3 is completed.

In this way, by monitoring the charging current in the constant voltage charging period at the time of uniform charging for each storage battery row 20, it is possible to determine whether or not equal charging is completed for each storage battery row 20.

In the case of the constant power-constant voltage charging method, it is possible to determine whether or not uniform charging is completed for each storage battery row 20 by the same method.

As described above, the power storage system 100 according to the present embodiment is provided corresponding to the multi-parallel storage battery 2 in which a plurality of storage battery rows 20_1 to 20_n including at least one lead storage battery cell 200 are connected in parallel, and the storage battery rows 20_1 to 20_n. The switches 4A_1 to 4A_n connected in series between the corresponding storage battery rows 20 and the PCS3 and the impedance circuits 5_1 to 5_n provided corresponding to each of the storage battery rows 20_1 to 20_n are connected in series to the impedance circuits. It includes switches 4B_1 to 4B_n connected in parallel with switches 4A_1 to 4A_n together with 5_1 to 5_n, and a control device 1. In the power storage system 100, the control device 1 turns on the switch 4A with the switch 4B turned off to perform uniform charging, and also turns on the switch 4A of the storage battery row 20 determined to have completed the uniform charging. Turn off.

According to this, the power supply from the PCS 3 to each storage battery row 20_1 to 20_n at the time of uniform charging can be controlled for each storage battery row 20_1 to 20_n. That is, by turning on the switches 4A_1 to 4A_n with the switches 4B_1 to 4B_n turned off, power is supplied from the PCS 3 to the storage battery rows 20_1 to 20_n, so that the storage battery rows 20_1 to 20_n can be uniformly charged. .. On the other hand, when the switch 4B of the storage battery row 20 determined to be fully charged is turned on while the uniform charging is being performed, the switch 4A of the storage battery row 20 is turned off so that the storage battery row 20 becomes the impedance circuit 5_3. It is connected to PCS3 via. At this time, if the impedance of the impedance circuit 5_3 is set to an appropriate value, the current I3 flowing through the storage battery row 20_3 can be suppressed to almost 0A, so that the charging of the storage battery row 20 is substantially stopped. This makes it possible to prevent overcharging of the storage battery row 20 for which uniform charging has been completed.

Therefore, according to the power storage system 100 according to the present embodiment, due to the characteristics (internal resistance), temperature, etc. of the lead-acid battery cells 200 of each storage battery row 20_1 to 20_n, each storage battery row 20_1 to 20_n is charged at equal charge. Even when the charging current flowing through the battery varies, it is possible to make each of the storage battery rows 20_1 to 20_n fully charged and to stop the charging of the fully charged storage battery rows 20 individually. As a result, it is possible to prevent the generation of storage battery rows 20_1 to 20_n that cause overcharging or insufficient charging due to variations in the charging current during uniform charging, so that deterioration of the multi-parallel storage battery 2 can be suppressed. Become.

Further, since the power storage system 100 realizes switching between supply and cutoff of power from the PCS 3 to each storage battery row 20_1 to 20_n at the time of uniform charging by switches 4A_1 to 4A_n and switches 4B_1 to 4B_n, the above-mentioned Patent Document 1 Unlike the conventional technology, it is not necessary to separately install a complicated charge / discharge control device for each storage battery row to adjust the charge / discharge amount of each storage battery row, and the increase in the cost of the power storage system is suppressed as compared with the conventional technology. be able to.

Further, according to the power storage system 100 according to the present embodiment, when the charging of the storage battery row 20 for which uniform charging is completed is stopped, the switch 4A is turned off with the switch 4B of the storage battery row 20 turned on. , The storage battery row 20 is connected to the PCS 3 via the impedance circuit 5.

At this time, as described above, by setting the impedance of the impedance circuit 5 to an appropriate value, it is equalized after the storage battery row 20 for which uniform charging is completed is disconnected (after switching between the switch 4A and the switch 4B). It is possible to suppress the charging current flowing through the charged storage battery row to almost 0 A.

Further, by setting the impedance of the impedance circuit 5 to an appropriate value, the parameters (impedance) of the entire storage battery (multi-parallel storage battery 2) seen from the PCS3 side before and after the disconnection of the storage battery row 20 in which uniform charging is completed. It is possible to suppress the change of. This makes it possible for the PCS 3 to appropriately control the voltage and charging current of the storage battery row 20 during uniform charging. That is, it is possible to effectively suppress the fluctuation of the voltage generated when the storage battery row as shown in FIG. 10 is disconnected and control the voltage so as not to exceed the upper limit voltage.

Here, the impedance of the impedance circuit 5 is preferably set to a value based on the voltage value and the current value of the storage battery row 20 at the time of constant voltage charging in uniform charging. This will be described in detail below.

FIG. 8 is a diagram showing changes over time in the internal impedance of one storage battery row during constant voltage charging in uniform charging. In the figure, the value obtained by dividing the voltage value of one storage battery row at the time of constant voltage charging in uniform charging by the current value flowing in the storage battery row is taken as the value of the internal impedance of the storage battery row, and the time change of the internal impedance is taken as the value. It is indicated by reference numeral 800.

Generally, during constant voltage charging for uniform charging, when the storage battery row approaches a fully charged state with the passage of time, the charging current of the storage battery row decreases. Therefore, as shown in FIG. 8, the internal impedance of the storage battery row tends to increase with the passage of time.

Therefore, the value of the impedance of the impedance circuit 5 connected between the storage battery row determined to have completed uniform charging and the PCS is a value based on the voltage value and the current value of the storage battery row during constant voltage charging of uniform charging ( Set the voltage value divided by the current value).

For example, as shown in FIG. 8, the range of the internal impedance of the storage battery row 20 (Zs to In Ze), an appropriate value may be selected according to the control conditions of the PCS3, and the value may be set as the impedance of the impedance circuit 5. Alternatively, considering that the storage battery rows 20 are in multiple parallels, the value of the internal impedance of one storage battery row 20 at the start of constant voltage charging or one storage battery row just before the end of constant voltage charging (end of constant voltage charging). A value obtained by multiplying the value of the internal impedance of 20 by a coefficient may be set as the impedance of the impedance circuit 5.

By setting the impedance of the impedance circuit 5 to an appropriate value in this way, it is possible to suppress the charging current flowing through the storage battery row for which uniform charging is completed to almost 0A after switching the switches 4A and 4B. It is possible to appropriately control the voltage and current of the storage battery row during uniform charging by the PCS3 by suppressing the change in the impedance of the entire storage battery as seen from the PCS3 side before and after the disconnection of the storage battery row 20 (before and after the connection of the impedance circuit 5). It will be possible.

As described above, according to the power storage system 100 according to the present embodiment, it is possible to suppress the variation in the charging state between the storage battery rows due to uniform charging and suppress the deterioration of the multi-parallel storage battery by a simpler configuration. , It becomes possible to realize more reliable uniform charging.

Further, in the power storage system 100, the control device 1 has the integrated value of the charging currents of the storage battery rows 20_1 to 20_n since the last uniform charging was completed and the storage battery rows 20_1 to the storage battery rows 20_1 after the last uniform charging was completed. When the ratio to the integrated value of the discharge current of 20_n becomes a predetermined value, it may be determined that the uniform charging of the storage battery rows 20_1 to 20_n is completed.

According to this, regardless of the charging method of equal charging, it is possible to more accurately determine whether or not equal charging is completed for each storage battery row 20.

Further, in the power storage system 100, the control device 1 reduces the charging current of the storage battery rows 20_1 to 20_n to a predetermined value during the constant voltage charging period in which the storage battery rows 20_1 to 20_n are charged by the constant voltage in uniform charging. In addition, it may be determined that the uniform charging of the storage battery rows 20_1 to 20_n is completed.

According to this, in a power storage system that employs a uniform charging method that performs constant voltage charging just before the end of uniform charging, such as a constant current-constant voltage charging method and a constant power-constant voltage charging method, it is easier and more accurate. It is possible to determine whether or not uniform charging is completed for each storage battery row 20.

<< Expansion of embodiment >>
Although the invention made by the present inventors has been specifically described above based on the embodiments, it is needless to say that the present invention is not limited thereto and can be variously modified without departing from the gist thereof. stomach.

For example, in the above embodiment, the constant current-constant voltage charging method and the constant power-constant voltage charging method have been exemplified as the charging methods having a constant voltage charging period of uniform charging, but the present invention is not limited thereto.

For example, first constant current charging is performed, and after the storage battery voltage reaches a predetermined threshold, constant current charging at a current value lower than the previous current value is repeated multiple times, and finally, constant current charging is performed at a predetermined voltage. A multi-stage charging method may be used in which voltage charging is performed to restore the lead storage battery to a fully charged state.

For example, the control device 1 determines that uniform charging of the storage battery rows 20_1 to 20_n is completed when the charging current of the storage battery rows 20_1 to 20_n decreases to a predetermined value during the constant voltage charging period of the multi-stage charging method. By doing so, it is possible to more easily and accurately determine whether or not uniform charging is completed for each storage battery row 20 as in the case of the constant current-constant voltage charging method and the constant power-constant voltage charging method.

1 ... Control device, 2 ... Storage battery module (multi-parallel storage battery), 3 ... AC / DC conversion device (PCS), 4A_1 to 4A_n ... Switch (first switch), 4B_1 to 4B_n ... Switch (second switch), 5,5_1 to 5_n ... impedance circuit, 6 ... load, 7 ... power supply unit, 11 ... monitoring unit, 12 ... storage battery management unit, 13 ... switch control unit, 20,20_1 to 20_n ... storage battery row, 100 ... power storage system, 200 ... lead storage battery Cell, 201 ... Voltage sensor, 202 ... Current sensor, Is ... Threshold (predetermined value), R, R1, R2 ... Resistance (element), C ... Capacitor.

Claims (6)

A multi-parallel storage battery in which a plurality of storage battery rows including at least one lead storage battery cell are connected in parallel, and
An AC / DC converter that controls the transfer of power to the multi-parallel storage battery,
A first switch provided corresponding to each storage battery row and connected in series between the corresponding storage battery row and the AC / DC converter.
An impedance circuit having a predetermined impedance, which is provided corresponding to each storage battery row and is connected in parallel with the first switch between the corresponding storage battery row and the AC / DC conversion device.
A second switch, which is provided corresponding to each storage battery row, is connected in series with the impedance circuit, and is connected in parallel with the first switch together with the impedance circuit.
A control device that monitors the state of the storage battery row for each storage battery row and controls the on / off of the first switch and the second switch is provided.
The control device is equalized for fully charging the storage battery row by turning on the first switch with the second switch turned off and supplying power from the AC / DC conversion device to the storage battery row. While charging, it is determined for each storage battery row whether or not the uniform charging is completed, and the second switch of the storage battery row determined to have completed the uniform charging is turned on. A power storage system characterized by turning off the first switch. In the power storage system according to claim 1,
The impedance circuit is a power storage system characterized by including resistance. In the power storage system according to claim 1,
The impedance circuit is a power storage system including a capacitor. A multi-parallel storage battery in which a plurality of storage battery rows including at least one lead storage battery cell are connected in parallel, an AC / DC conversion device for controlling the transfer of power of the multi-parallel storage battery, and an AC / DC conversion device corresponding to each of the storage battery rows are provided and correspond to each other. The first switch connected in series between the storage battery row and the AC / DC conversion device, and the first switch provided corresponding to each storage battery row and between the corresponding storage battery row and the AC / DC conversion device. An impedance circuit having a predetermined impedance connected in parallel with the switch, provided corresponding to each storage battery row, connected in series with the impedance circuit, and connected in parallel with the first switch together with the impedance circuit. Charging of the multi-parallel storage battery in a power storage system including a second switch and a control device that monitors the state of the storage battery row for each storage battery row and controls the on / off of the first switch and the second switch. It ’s a control method,
When the control device turns on the first switch with the second switch turned off and supplies electric power from the AC / DC conversion device to the storage battery row, the storage battery row is uniformly charged. The first step to start charging and
A second step in which the control device determines whether or not the uniform charging is completed for each storage battery row,
A charging control method comprising the third step of turning off the first switch while the second switch of the storage battery row determined that the uniform charging is completed is turned on. In the charge control method according to claim 4,
The impedance circuit is a charge control method characterized by including resistance. In the charge control method according to claim 4,
The impedance circuit is a charge control method characterized by including a capacitor.

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