JP2012205407A - Power storage device and voltage equalization method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce start-up time of a system connected to a power storage device while equalizing voltages among battery arrays by a simple structure.SOLUTION: A power storage device 1 includes: a battery unit 2 which is constituted by connecting a plurality of battery arrays in which a plurality of secondary batteries is connected in series in parallel; a voltage equalization circuit 3 for reducing voltage differences among the plurality of battery arrays; and contactors 21, 22 and 23 disposed between individual battery arrays 11, 12 and 13 and a load 10. In the power storage device 1, the voltage equalization circuit 3 is provided with: first resistors 24, 25 and 26 connected to the individual battery arrays 11, 12 and 13; a switching element 27 for electrically connecting and disconnecting a plurality of battery arrays 11, 12 and 13 through the first resistors 24, 25 and 26; and BMU1, BMU2 and BMU3 for controlling the switching element 27. The power storage device 1 causes the voltage equalization circuit 3 to reduce the voltage differences among the plurality of battery arrays by turning on the switching element 27 of the voltage equalization circuit 3 after a system is shut down.

Description

  The present invention relates to a power storage device and a voltage equalization method for the power storage device.

  2. Description of the Related Art Conventionally, there is known a power storage device that realizes a large capacity by connecting a plurality of secondary batteries (cells) in series to form a battery array, and further connecting the plurality of battery arrays in parallel. In such a power storage device, it is known that a voltage difference is generated between battery strings connected in parallel, and a technique for reducing this voltage difference has been proposed. That is, if the power storage device is connected to a load in a state where a voltage difference of a predetermined value or more is generated between the battery strings, current exceeding the allowable range may flow to the battery string or the load at the time of connection. There are concerns about damage to the columns and welding of the contactors connecting the power storage device and the system. Therefore, in order to prevent such a situation, a means for reducing the voltage difference generated between the battery arrays is required.

For example, in Patent Document 1, a power converter is provided corresponding to each battery row, and when voltage imbalance occurs between the battery rows, the power converter is activated to cause the battery rows. A technique for reducing the voltage difference is disclosed.
Patent Document 2 is provided with a balance circuit that is commonly connected in parallel to cells connected in the same order in each battery row and adjusts a voltage difference between cells of the same order included in the battery row. A technique for reducing a voltage difference between battery arrays by operating a circuit is disclosed.

JP 2010-141970 A JP 2007-12484 A

However, in the technique disclosed in Patent Document 1, a voltage converter must be provided for each battery row, which may increase the size of the device and increase the cost.
In general, the above-described voltage equalization operation of the battery array is performed when the system to which the power storage device is applied is started. For example, in the case of a power storage device mounted on a vehicle, voltage equalization processing is performed when an ignition key is turned on, and thus there is a problem that it takes time to start up the system. In particular, as disclosed in the above-mentioned Patent Document 2, when voltage equalization is performed by resistance, the current to be balanced becomes smaller as the voltage difference becomes smaller. There was a problem that.

  The present invention has been made in view of such circumstances, and it is possible to equalize the voltage between battery arrays with a simple configuration and to reduce the time required to start up the system to which the power storage device is connected. It is an object of the present invention to provide a power storage device that can be used and a voltage equalization method for the power storage device.

In order to solve the above problems, the present invention employs the following means.
The present invention is a power storage device for supplying power to a load, wherein a battery unit is formed by connecting a plurality of battery rows in which a plurality of secondary batteries are connected in series, and a voltage difference between the battery rows. Voltage equalizing means for reducing the voltage, and first switching means provided between each of the battery strings and the load, wherein the voltage equalizing means is a first resistance means connected to each of the battery strings. And a second switching means for electrically connecting and disconnecting the battery string via the first resistance means, and a control means for controlling the second switching means, after the system is stopped, Provided is a power storage device that reduces a voltage difference between the battery strings by turning on second switching means of voltage equalization means.

According to such a configuration, after the system is stopped, the second switching unit is turned on, so that each battery row is connected via the first resistor. As a result, a current flows from a battery string having a high terminal voltage to a battery string having a low terminal voltage, whereby a voltage difference between the battery strings is reduced, and voltage equalization between the battery strings is performed. Further, at this time, since the current flowing through each battery array is via the first resistor, an overcurrent that destroys the secondary battery does not flow.
As described above, by performing voltage equalization after the system is stopped, the time can be shortened even if the voltage equalization processing at the time of starting the system is unnecessary or is performed. Moreover, it becomes possible to achieve downsizing and the like of the apparatus by adopting a simple configuration in which each battery row is connected via the first resistance means.

  In the above power storage device, the control unit may perform the second switching when a maximum voltage difference between the battery rows is equal to or greater than a first threshold determined by an allowable current value of the first switching unit or the secondary battery. A plurality of battery rows are electrically connected via the first resistance means by turning on the means, and the maximum voltage difference between the battery rows is set to a value smaller than the first threshold value or less. In this case, the plurality of battery rows may be electrically disconnected by turning off the second switching means.

  According to such a configuration, when the maximum voltage difference between the battery rows is equal to or greater than the first threshold value determined by the first switching means or the allowable current value of the secondary battery, the second switching means is turned on. Equalizes the voltage between battery rows. Then, when the maximum voltage difference between the battery rows is equal to or less than the second threshold value which is smaller than the first threshold value, it is determined that the potentials between the battery rows are substantially equal, and the second switching means is turned off to turn off each battery. Detach the column. Thus, since the start and end of voltage equalization are determined based on the first threshold value determined by the allowable current value of the first switching means or the secondary battery and the second threshold value smaller than the first threshold value, the first When the switching means is turned on, the current flowing through the secondary battery and the first switching means can be reliably made smaller than the allowable current value, and damage to these elements can be avoided.

  In the above power storage device, the voltage equalization means electrically connects a plurality of second resistance means provided corresponding to each of the secondary batteries, and each of the secondary batteries and each of the second resistance means. A plurality of third switching means for connecting and disconnecting, and the control means may control the second switching means and the third switching means to reduce a voltage difference between the battery arrays. .

  According to such a configuration, in addition to the voltage equalization by the first resistance means, the voltage equalization can be promoted by discharging each secondary battery by the second resistance means. Thereby, the time required for voltage equalization can be shortened.

  In the above power storage device, the control unit may perform the second switching when a maximum voltage difference between the battery rows is equal to or greater than a first threshold determined by an allowable current value of the first switching unit or the secondary battery. The battery array is electrically connected via the first resistance means, and a maximum voltage difference between the battery arrays is set to a value smaller than the first threshold value or less than a third threshold value. The third switching means of the battery row having a terminal voltage higher than the reference terminal voltage determined by the terminal voltage of each battery row is turned on, and each secondary battery and each of the second battery in the battery row is turned on. And the second switching means and the third switching when the maximum voltage difference between the battery arrays is equal to or less than a second threshold value set to a value smaller than the third threshold value. It is also possible to turn off the stage.

As described above, when the voltage equalization process is performed in two stages and the maximum voltage difference between the battery strings is equal to or greater than the first threshold value, first, the first switching means is turned on to perform voltage equalization by the first resistance means. Do. As a result, the voltage difference between the battery strings gradually decreases, and when the maximum voltage difference between the battery strings is equal to or smaller than the third threshold value which is smaller than the first threshold value, the reference terminal determined by the terminal voltage of each battery string next The third switching means of the battery string having a higher terminal voltage than the voltage is turned on to connect each secondary battery and each second resistance means in the battery string having a higher terminal voltage to discharge the secondary battery. Thereby, the discharge in a battery row | line with a high terminal voltage can be accelerated | stimulated, and it becomes possible to make a voltage difference with a battery row | line | column with a low terminal voltage small in a short time. Then, when the maximum voltage difference between the battery rows is equal to or less than the second threshold value smaller than the third threshold value, it is determined that the terminal voltages between the battery rows are substantially equal, and the second switching means and the third switching device The voltage equalization is completed by turning off the switching means. Thus, by performing voltage equalization using the first resistance means and the second resistance means, the time required for voltage equalization can be shortened.
In particular, when voltage equalization is performed using only the first resistance means, the power loss is small because only the charged power is exchanged between the battery strings, but the voltage difference between the battery strings is small. As a result, the current flowing between the battery arrays decreases, and it takes time until the voltages are equalized. In this way, the first resistance means with a small power loss is equalized at first, and in the region where the current flowing between the battery rows is small with only the first resistance means, the power loss increases but the equalization speed is fast. By discharging the secondary battery using the resistance means, the voltages can be effectively equalized.

  The present invention is a power storage device for supplying power to a load, wherein a battery unit is formed by connecting a plurality of battery rows in which a plurality of secondary batteries are connected in series, and a voltage difference between the battery rows. Voltage equalizing means, and first switching means provided between each battery row and the load, wherein the voltage equalizing means is provided corresponding to each of the secondary batteries. The second resistance means, third switching means for electrically connecting and disconnecting each secondary battery and each resistance means, and control means for controlling the third switching means. Is stopped, a battery string having a terminal voltage higher than a reference terminal voltage determined by the terminal voltage of each battery string is to be discharged, and by turning on the second switching means of the battery string to be discharged, Battery Providing a power storage device to reduce the voltage difference between.

  According to such a configuration, after the system is stopped, the secondary battery is discharged by turning on the third switching means in the battery train having a high terminal voltage. Thereby, the terminal voltage of a battery row | line can be reduced and the voltage difference between battery rows can be reduced. As described above, by performing voltage equalization after the system is stopped, the time can be shortened even if the voltage equalization processing at the time of starting the system is unnecessary or is performed. In general, the second resistance unit and the third switching unit are often provided in advance in the power storage device in order to adjust the cell balance. By diverting such an existing cell balance circuit and performing voltage equalization between battery arrays, it is possible to avoid an increase in the size of the device without the need for an additional device configuration, which is advantageous in terms of cost. Become.

  In the power storage device, when the maximum voltage difference between the battery strings is equal to or greater than a first threshold value determined by an allowable current value of the first switching means or the secondary battery, the control means The third switching means of the column is turned on, and the third switching unit is turned off when the maximum voltage difference between the battery columns is equal to or less than a second threshold value set to a value smaller than the first threshold value. It is good as well.

  According to such a configuration, when the maximum voltage difference between the battery arrays is equal to or greater than the first threshold value determined by the first switching means or the allowable current value of the secondary battery, the third battery array to be discharged is third. The switching means is turned on to equalize the voltage between the battery rows. Then, when the maximum voltage difference between the battery strings is equal to or less than the second threshold value which is smaller than the first threshold value, it is determined that the potentials between the battery strings are substantially equal, and the third switching unit is turned off to The equalization process ends. Thus, since the start and end of voltage equalization are determined based on the first threshold value determined by the allowable current value of the first switching means or the secondary battery and the second threshold value smaller than the first threshold value, the first When the switching means is turned on, the current flowing through the secondary battery and the first switching means can be reliably made smaller than the allowable current value, and damage to these elements can be avoided.

  The present invention provides a battery unit in which a plurality of battery rows in which a plurality of secondary batteries are connected in series are connected in parallel, and supplies power to a system load, and between each of the battery rows and the load. A voltage equalizing method for a power storage device having a first switching means provided on the battery, wherein first resistance means is provided corresponding to each of the battery rows, and a plurality of the battery rows are connected to the first resistance means. A method for equalizing a voltage of a power storage device, comprising: a second switching unit that is electrically connected and disconnected via a power supply; and turning on the second switching unit to reduce a voltage difference between the battery strings after the system is stopped I will provide a.

  The present invention provides a battery unit in which a plurality of battery rows in which a plurality of secondary batteries are connected in series are connected in parallel, and supplies power to a system load, and between each of the battery rows and the load. A voltage equalizing method for a power storage device having a first switching means provided on the secondary battery, wherein second secondary means are provided corresponding to each secondary battery, and each secondary battery and each resistance means are provided. And a third switching means for electrically connecting and disconnecting, and after the system is stopped, a battery string having a terminal voltage higher than a reference terminal voltage determined by a terminal voltage of each of the battery strings is to be discharged, There is provided a voltage equalizing method for a power storage device that reduces a voltage difference between the battery strings by turning on the second switching means of the battery string to be discharged.

  According to the present invention, it is possible to equalize the voltages between the battery strings with a simple configuration and to shorten the time required for starting the system to which the power storage device is connected.

It is the figure which showed the whole schematic structure of the electrical storage apparatus which concerns on 1st Embodiment of this invention. It is the figure which showed the internal schematic structure of CMU in the electrical storage apparatus which concerns on 2nd Embodiment of this invention.

[First Embodiment]
Hereinafter, a power storage device and a voltage equalization method for the power storage device according to a first embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram illustrating an overall schematic configuration of the power storage device according to the present embodiment. As shown in FIG. 1, the power storage device 1 is applied to a system having a load 10 and supplies power to the load 10. The power storage device 1 includes a battery unit 2 formed by connecting a plurality of battery rows 11, 12, and 13 connected in series with a plurality of secondary batteries (hereinafter referred to as “cells”) in series, and a voltage difference between the battery rows. Voltage equalization circuit 3, and contactors (first switching means) 21, 22, 23 provided between each battery row 11, 12, 13 and load 10. ON / OFF of the contactors 21, 22, and 23 is controlled by BMU1, BMU2, and BMU3, which will be described later.

  Examples of a system to which the power storage device 1 is applied include an electric vehicle and a forklift. When applied to an electric vehicle, for example, the load 10 is a travel motor. The power storage device 1 is discharged when the traveling motor is powered and charged during regeneration. In this case, a bidirectional inverter that can convert the DC voltage output from the power storage device 1 into a three-phase AC voltage and convert the three-phase AC voltage output from the traveling motor into a DC voltage. Power converters (not shown) are provided between the contactors 21, 22 and 23 and the load 10.

  When applied to a forklift, the load 10 is a cargo handling motor. The power storage device 1 supplies power when the cargo handling motor is powered. Also in this case, a power conversion device such as an inverter that converts power between the power storage device 1 and the cargo handling motor is required.

In the battery unit 2 in FIG. 1, each of the battery rows 11, 12, and 13 is composed of six cells. Six cells are made into three battery modules, and each battery module is provided with a battery monitoring circuit, here, a CMU (Cell Monitoring Unit). The CMU detects the terminal voltage of each cell constituting the corresponding battery module, the terminal voltage of the battery module, and the like, and the detected information is provided for each of the battery rows 11, 12, and 13, respectively. Here, it outputs to BMU (Battery Management Unit). Specifically, BMU 1 is provided corresponding to battery row 11, BMU 2 is provided corresponding to battery row 12, and BMU 3 is provided corresponding to battery row 13.
BMU1, BMU2, and BMU3 are, for example, microcontrollers and are configured to be able to communicate with each other. BMU1, BMU2, and BMU3 calculate the terminal voltages of the corresponding battery arrays 11, 12, and 13 based on information from the CMU, and exchange the calculated terminal voltage information of the battery arrays 11, 12, and 13 with each other. Thereby, each BMU1, BMU2, BMU3 can grasp the voltage difference which has arisen between battery rows.

  In addition, the voltage equalization circuit 3 connects the first resistors 41, 25, and 26 connected to the battery rows 11, 12, and 13 and the battery rows 11, 12, and 13 via the first resistors 24, 25, and 26, respectively. And a switching element (second switching means) 27 that is electrically connected and disconnected. In addition, the switching of the switching element 27 is controlled by the BMU 1, BMU 2, BMU 3 (control means), and the BMU 1, BMU 2, BMU 3 operate as a part of the voltage equalization circuit 3. Further, a fuse for protecting the cell when an overcurrent flows is connected between each battery row 11, 12, 13 and the corresponding first resistor 24, 25, 26.

  Next, the operation of the voltage equalization circuit 3 will be described in detail. In the following description, a case where the power storage device 1 is mounted on an electric vehicle and the load 10 is a travel motor will be described as an example.

  First, when the electric vehicle is stopped and the ignition key is turned off, the voltage equalization circuit 3 performs the following operation in order to reduce the voltage difference generated between the battery rows. Here, when the ignition key is in the off state, the contactors 21, 22, and 23 are opened, and the battery rows 11, 12, and 13 are electrically disconnected from the load 10. In the normal state, since the switching element 27 is in the off state, the battery rows 11, 12, and 13 are electrically disconnected from each other.

In such a state, the information of the battery module, for example, the terminal voltage of the battery module and the terminal voltage of each cell are output to the corresponding BMU1, BMU2, and BMU3 by the CMU provided in each of the battery rows 11, 12, and 13, respectively. Is done.
BMU1, BMU2, and BMU3 calculate terminal voltages of the corresponding battery arrays 11, 12, and 13 based on information received from the CMU, and exchange the information with each other. Thereby, BMU1, BMU2, and BMU3 can grasp the terminal voltages of the battery rows 11, 12, and 13.

  Next, the BMU1, BMU2, and BMU3 determine, for example, whether or not the maximum voltage difference between the battery arrays is equal to or greater than a preset first threshold value. An on control signal for turning on is output. Here, the first threshold value is a threshold value for determining that voltage equalization is necessary. For example, the first threshold value is based on the allowable current value of the cells constituting the contactors 21, 22, 23 or the battery rows 11, 12, 13. Determined. More specifically, the first threshold value is a cell in which the current flowing through the corresponding battery row when the contactor 21, 22, 23 is turned on constitutes the contactor 21, 22, 23 or the battery row 11, 12, 13 Is set to a value that is less than or equal to the allowable current value. Here, when the contactors 21, 22, and 23 are turned on, the current flowing through the corresponding battery row is, for example, the terminal voltage of each battery row, the internal resistance of each battery row, and the resistance of the wiring set in advance. Determined based on. Therefore, the voltage difference of the terminal voltage is calculated from these values so that the current is less than or equal to the allowable current value of the contactor or cell, and the value or a value having a predetermined margin is set as the first threshold value. That's fine.

  In this way, when an on control signal is output from at least one of the BMU1, BMU2, and BMU3, the switching element 27 is turned on, and the battery trains 11, 12, and 13 pass through the first resistors 24, 25, and 26. Are electrically connected. As a result, a current flows from a battery string having a high potential toward a battery string having a low potential, and a voltage difference between the battery strings is reduced. In addition, since the current flowing through each battery row at this time is routed through the first resistors 24, 25, and 26, there is no possibility that an overcurrent that destroys the secondary battery or the like flows.

  Then, BMU1, BMU2, and BMU3 output an off control signal for turning off the switching element 27 when the maximum voltage difference between the battery arrays is equal to or smaller than a second threshold value that is smaller than the first threshold value. Here, the second threshold value is determined as follows. That is, in this embodiment, when the ignition key is turned off, voltage equalization is performed. Therefore, a long time elapses until the ignition key is turned on next, and the terminal voltage of each battery row changes due to natural discharge. It is possible. Even in such a case, the second threshold value is set to a value that considers the voltage change due to natural discharge, that is, the voltage difference does not exceed the first threshold value even when the voltage changes due to natural discharge. Thus, even when the voltage difference between the battery strings when the ignition key is turned on next time is equal to or less than the first threshold value or equal to or greater than the first threshold value, the difference can be reduced. As a result, voltage equalization processing at the time of system startup can be suppressed to a short time even when unnecessary or necessary.

  Since the signal for operating the switching element 27 is the logical sum of the control signals output from BMU1, BMU2, and BMU3 as described above, all the control signals output from BMU1, BMU2, and BMU3 are turned off. In this case, the switching element 27 is turned off. Thereby, each battery row | line | column 11,12,13 will be in the state disconnected electrically, and a voltage equalization process will be complete | finished. Then, when the voltage equalization process ends, power supply to the BMU1, BMU2, BMU3, and each CMU is stopped.

  As described above, according to the power storage device 1 and the voltage equalization method for the power storage device according to the present embodiment, when the system is stopped (in the above example, when the ignition key is turned off), the battery train Since the voltage equalization process is performed to reduce the voltage difference between the two, the voltage equalization process at the next system startup (when the ignition key is turned on in the above example) is unnecessary or even if it is performed Can be shortened. As a result, the time required to start the system can be shortened, and the system can be started as quickly as possible. Further, the voltage is generated by a simple and inexpensive circuit including the second resistors 24, 25, and 26 connected to the battery rows 11, 12, and 13 and the switching elements 27 that connect the battery rows to each other via the second resistors. Since equalization is realized, it is possible to reduce the size and cost of the apparatus.

[Second Embodiment]
Next, regarding the power storage device and the voltage equalization method for the power storage device according to the second embodiment of the present invention, description of points that are the same as those in the first embodiment described above will be omitted, and differences will be mainly described.

  FIG. 2 is a diagram showing an internal schematic configuration of the CMU corresponding to the battery array 11 in the power storage device shown in FIG. As shown in FIG. 2, the CMU includes a cell balance circuit 50. The cell balance circuit 50 is provided corresponding to each cell 40, and a third resistor (third resistor means) 41 connected to the cell 40, and a switching element (connecting and disconnecting the cell 40 and the third resistor 41). 3rd switching means) 42.

The voltage equalization process in the power storage device having such a configuration is performed as follows.
First, as in the first embodiment described above, when the system is stopped, information on each battery cell is performed between the BMUs, and the second switching is performed when the maximum voltage difference between the battery strings is equal to or greater than the first threshold value. An on control signal for turning on the element 27 is output. As a result, the second switching element 27 is turned on, and the battery trains 11, 12, and 13 are electrically connected via the first resistors 24, 25, and 26, and the terminal voltage is received from the battery train having a high terminal voltage. Current flows toward the lower battery row, and the voltage difference between the battery rows is reduced.

  BMU1, BMU2, and BMU3 are cell balance circuits for battery rows to be discharged when the maximum voltage difference between the battery rows is equal to or less than a third threshold value set between the first threshold value and the second threshold value. 50 is operated to discharge each cell 40. For the battery array to be discharged, for example, the average of the terminal voltages of the battery arrays 11, 12, and 13 is calculated, and the battery array having a terminal voltage higher than this average is specified as the discharge target.

  The BMU corresponding to the battery array to be discharged outputs a control signal for turning on the switching element 42 of the cell balance circuit 50 to each corresponding CMU. The CMU that has received this control signal starts discharge of each cell 40 by turning on all the switching elements 42 of the cell balance circuit 50 included in the CMU. As a result, the voltage of the cell 40 gradually decreases.

In this way, when the terminal voltage drop is promoted in the battery string having a high terminal voltage and the maximum voltage difference between the battery strings is equal to or less than the second threshold value, each of the BMU1, BMU2, An off control signal for turning off the switching element 27 is output from the BMU 3, and a control signal for turning off the switching element 42 is output to the corresponding CMU for the BMU of the battery array to be discharged.
As a result, the switching element 27 and all the switching elements 42 are turned off, and the voltage equalization process ends.

  As described above, according to the power storage device and the voltage equalization method for the power storage device according to this embodiment, the voltage equalization processing is divided into two stages, and the switching element 27 shown in FIG. Thus, by connecting the battery rows 11, 12, and 13 to each other via the resistors 24, 25, and 26, voltage equalization is performed, and when the voltage difference between the two becomes small to some extent, the terminal voltage is large. Only with respect to the battery array, each cell 40 and the third resistor 41 are connected to discharge the cell 40. Thereby, voltage equalization processing can be further promoted. As a result, the time required for the voltage equalization process can be shortened compared to the first embodiment.

[Third Embodiment]
Next, a power storage device and a voltage equalization method for the power storage device according to the third embodiment of the present invention will be described.
In this embodiment, the voltage difference between the battery rows is reduced using only the cell balance circuit 50 described in the second embodiment without performing the voltage equalization process by the switching element 27 shown in FIG. Specifically, when the system is stopped, BMU1, BMU2, and BMU3 exchange information on the terminal voltages of the battery strings, and if the maximum voltage difference between the battery strings is equal to or greater than the first threshold value, the voltages are equalized. The battery array to be discharged is determined by the same method as in the second embodiment described above.

  And in the battery row | line | column determined as discharge object, the control signal which operates the cell balance circuit 50 from BMU to CMU is output, and all the switching elements 42 of each cell balance circuit 50 are turned ON by CMU. Thereby, about the battery row | line | column of discharge object, in all the cells 40 which comprise the battery row | line, the discharge using the 3rd resistance 41 is started, and the terminal voltage of the battery row | line | column of discharge object falls gradually. Then, when the voltage difference between the battery strings becomes equal to or less than the second threshold value, the BMU outputs a control signal for turning off the cell balance circuit 50 to the CMU, and ends the voltage equalization process.

  As described above, according to the power storage device and the voltage equalization method for the power storage device according to the present embodiment, the generally provided cell balance circuit 50 is also used in the voltage equalization processing between the battery arrays. The voltage difference between the battery arrays can be reduced simply by changing the control logic. As a result, the apparatus configuration can be simplified and further cost reduction can be achieved.

DESCRIPTION OF SYMBOLS 1 Power storage device 2 Battery unit 3 Voltage equalization circuit 10 Load 11, 12, 13 Battery row | line | column 21, 22, 23 Contactor 24, 25, 26 1st resistance 27 Switching element 40 Secondary battery (cell)
41 Second resistor 42 Switching element 50 Cell balance circuit

Claims (8)

A power storage device that supplies power to a load,
A battery unit formed by connecting in parallel a plurality of battery rows in which a plurality of secondary batteries are connected in series;
Voltage equalizing means for reducing a voltage difference between the battery rows;
First switching means provided between each of the battery rows and the load;
The voltage equalizing means includes
First resistance means connected to each of the battery rows;
Second switching means for electrically connecting and disconnecting the battery string via the first resistance means;
Control means for controlling the second switching means,
A power storage device that reduces a voltage difference between the battery strings by turning on the second switching means of the voltage equalizing means after the system is stopped. The control means turns on the second switching means when the maximum voltage difference between the battery rows is equal to or greater than a first threshold value determined by an allowable current value of the first switching means or the secondary battery. Electrically connecting the plurality of battery rows via the first resistance means;
When the maximum voltage difference between the battery rows is equal to or smaller than a second threshold value set to a value smaller than the first threshold value, the second switching means is turned off to electrically disconnect the plurality of battery rows. The power storage device according to claim 1. The voltage equalizing means includes
A plurality of second resistance means provided corresponding to each of the secondary batteries;
A plurality of third switching means for electrically connecting and disconnecting each secondary battery and each of the second resistance means;
The power storage device according to claim 1, wherein the control unit controls the second switching unit and the third switching unit to reduce a voltage difference between the battery strings. The control means includes
When the maximum voltage difference between the battery trains is equal to or greater than a first threshold value determined by an allowable current value of the first switching device or the secondary battery, the plurality of battery trains are turned on by turning on the second switching device. Are electrically connected via the first resistance means,
When the maximum voltage difference between the battery strings is equal to or less than a third threshold value set to a value smaller than the first threshold value, the terminal voltage is higher than the reference terminal voltage determined by the terminal voltage of each battery string. Turning on the third switching means of the high battery row, and connecting each secondary battery and each second resistance means in the battery row;
The third switching means and the third switching means are turned off when the maximum voltage difference between the battery strings becomes equal to or smaller than a second threshold value set to a value smaller than the third threshold value. The power storage device described. A power storage device that supplies power to a load,
A battery unit formed by connecting in parallel a plurality of battery rows in which a plurality of secondary batteries are connected in series;
Voltage equalizing means for reducing a voltage difference between the battery rows;
First switching means provided between each of the battery rows and the load;
The voltage equalizing means includes
Second resistance means provided corresponding to each of the secondary batteries,
Third switching means for electrically connecting and disconnecting each secondary battery and each resistance means;
Control means for controlling the third switching means,
After the system is stopped, a battery string having a terminal voltage higher than a reference terminal voltage determined by a terminal voltage of each battery string is set as a discharge target, and the third switching unit of the discharge target battery string is turned on. A power storage device that reduces a voltage difference between the battery rows. When the maximum voltage difference between the battery strings is equal to or greater than a first threshold value determined by an allowable current value of the first switching means or the secondary battery, the control means is configured to perform the third of the battery strings to be discharged. Turn on the switching means,
6. The power storage device according to claim 5, wherein the third switching unit is turned off when a maximum voltage difference between the battery rows is equal to or less than a second threshold value set to a value smaller than the first threshold value. A battery unit in which a plurality of secondary batteries connected in series are connected in parallel, and a battery unit that supplies power to a system load is provided between each of the battery arrays and the load. A voltage equalizing method for a power storage device having first switching means,
Providing first resistance means corresponding to each of the battery rows, and providing second switching means for electrically connecting and disconnecting the plurality of battery rows via the first resistance means;
A method for equalizing a voltage of a power storage device, wherein after the system is stopped, the second switching unit is turned on to reduce a voltage difference between the battery strings. A battery unit in which a plurality of secondary batteries connected in series are connected in parallel, and a battery unit that supplies power to a system load is provided between each of the battery arrays and the load. A voltage equalizing method for a power storage device having first switching means,
A second resistance means is provided corresponding to each of the secondary batteries, and a third switching means for electrically connecting and disconnecting each of the secondary batteries and each of the resistance means is provided,
After the system is stopped, a battery string having a terminal voltage higher than a reference terminal voltage determined by a terminal voltage of each battery string is set as a discharge target, and the third switching unit of the discharge target battery string is turned on. A voltage equalizing method for a power storage device that reduces a voltage difference between the battery rows.

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