WO2014067393A1

WO2014067393A1 - Circuit, method, device, and energy storage system for balancing battery energy

Info

Publication number: WO2014067393A1
Application number: PCT/CN2013/085368
Authority: WO
Inventors: 冯汉春; 尹博; 戴翔; 陆卫平
Original assignee: 恩力能源科技（南通）有限公司
Priority date: 2012-10-30
Filing date: 2013-10-17
Publication date: 2014-05-08
Also published as: CN103795094A

Abstract

A circuit for balancing battery energy comprising a charging branch (201) that is parallel-connected to each battery of an energy storage battery pack. Each charging branch (201) comprises: a first end of the charging branch (201) that is connected to a first output end of a charger (2011), a second output end of the charger (2011) that is connected to a second end of the charging branch (201) via a switch (K1), a first input end of the charger (2011) that is connected to a first end (A1) of the energy storage battery pack, and a second input end of the charger (2011) that is connected to a second end (A2) of the energy storage battery pack. The charger (2011) charges the battery corresponding to the charging branch (201) when the switch (K1) in the charging branch (201) is closed. The circuit allows for increased efficiency in utilizing the energy of the energy storage battery pack.

Description

The invention can be submitted to the Chinese Patent Office on October 30, 2012, the application number is 201210424782.2, and the invention name is "battery energy equalization circuit, method, device and energy storage system". Priority of the Chinese Patent Application, the entire contents of which is incorporated herein by reference. TECHNICAL FIELD The present invention relates to the field of circuits, and in particular, to a battery energy equalization circuit, method, device, and energy storage system. Background technique

An energy storage system is a system that stores electrical energy into an energy storage component and releases it when needed. The source of electrical energy can be electrical energy obtained from the grid, or energy generated by solar energy, wind energy, and the like. The energy storage system is connected to the electrical equipment to supply power to the electrical equipment. In particular, the energy storage system can be used as a backup power source for the electrical equipment, that is, when the power grid is normal, the power grid supplies power to the power equipment, and when the grid power supply is insufficient or the power is cut off, the energy storage system is powered. The device is powered.

The energy storage system is mainly composed of a storage battery pack and a battery management system. The energy storage battery pack is used to store energy, and the battery management system is used to control the energy storage battery pack. For example, the voltage, current and temperature of the energy storage battery pack can be monitored to perform charging and discharging control of the energy storage battery pack. ; Perform overvoltage, overcurrent and overtemperature protection of the energy storage battery pack. In addition, since the energy storage battery pack generally consists of a plurality of batteries, it is also necessary to balance the energy of the battery in the energy storage battery pack to ensure that the battery has uniform characteristics.

The energy storage battery pack is composed of several battery cells, and the energy is stored in the battery. As shown in Fig. 1, a plurality of battery cells are combined in series and in parallel to form the energy storage battery pack. The total voltage supplied by the energy storage battery pack is equal to the sum of the voltages of the individual cells connected in series, and the total current of the energy storage battery pack is equal to the sum of the currents of several battery cells connected in parallel. For example, the energy storage battery pack in FIG. 1 includes B groups of parallel batteries, each group of batteries includes a Y-cell battery, the voltage of the single-cell battery is X, and the total voltage supplied by the energy storage battery pack is X*Y. The current of each battery is Α, and the total current supplied by the Β battery in parallel is Α*Β. * indicates multiplication.

When charging the energy storage battery pack, there will be a certain difference in the characteristics of each battery, which will result in unequal battery energy in each series. The high energy battery will charge the low energy battery, thus accelerating the battery. Aging, reducing the life of the energy storage battery pack. Therefore, in the energy storage system, the battery power must be Balance, so that each battery is equal in energy, thus extending the overall life of the energy storage battery pack and the energy storage system. An existing battery energy equalization method is shown in FIG. 1A, in which a resistor is connected in parallel to each battery in the energy storage battery pack, and a battery voltage detector (not shown) is provided for the energy storage battery pack. The detector is configured to detect the voltage of each battery in the energy storage battery pack, and provide the voltage of each battery to the controller (not shown). When the controller determines that the voltage of one battery is higher than the voltage of the other battery, Turn on the path of the battery and the parallel resistor, let the current of the battery flow through the resistor connected in parallel with it, and the excess energy of the battery is consumed by the heat of the resistor until the voltage of the battery and other batteries are equal.

However, the circuit for equalizing the energy of the battery in the energy storage battery pack needs to consume more energy of the battery through the resistor, thereby causing additional loss of energy in the energy storage battery pack and reducing the energy utilization rate of the energy storage battery pack. Summary of the invention

In the embodiment of the present application, a charging circuit, a battery energy equalization method, a controller, and an energy storage system are provided, which can improve energy utilization efficiency of the energy storage battery pack.

The embodiment of the present application provides a battery energy equalization circuit, including:

Parallging a charging branch for each battery of the energy storage battery pack;

Each charging branch includes: a first end of the charging branch is connected to the first output end of the charger, and a second output end of the charger is connected to the second end of the charging branch through a switch; the charger The first input end is connected to the first end of the energy storage battery pack, and the second input end of the charger is connected to the second end of the energy storage battery pack; the charger is when the switch in the charging branch is closed The battery corresponding to the charging branch is charged.

The charger includes: a coupler and a rectifier; wherein

a first input of the coupler serves as a first input of the charger, and a second input of the coupler serves as a second input of the charger;

a first output of the coupler is coupled to the first input of the rectifier, and a second output of the coupler is coupled to the second input of the rectifier;

The first output of the rectifier acts as the first output of the charger and the second output of the rectifier acts as the second output of the charger.

The coupler is implemented by a coupling transformer.

The rectifier includes:

a first input end of the rectifier is connected to the first output end of the rectifier through the reversed first diode, and is also connected to the second output end of the rectifier through the second diode; A second input of the rectifier is coupled to the first output of the rectifier via a reversed third diode and to a second output of the rectifier via a fourth diode.

Also includes:

The second input of the charger in all of the charging branches is connected to the second end of the energy storage battery pack via a main switch. The embodiment of the present application further provides a battery energy equalization method, including:

Determining the battery to be charged according to the voltage of each battery in the energy storage battery pack;

The switch in the charging branch corresponding to the battery to be charged is controlled to be closed, so that the charger in the charging branch charges the battery that needs to be charged.

Determining the battery to be charged according to the voltage of each battery in the energy storage battery pack includes:

Calculating an average value of the battery voltage according to the voltage of each battery in the energy storage battery pack;

A battery having a voltage smaller than the average value is determined as a battery that needs to be charged.

Determining the voltage having the largest value from the voltages of the respective batteries of the energy storage battery pack;

All the batteries except the battery corresponding to the voltage having the largest value are determined as the batteries to be charged. Before determining the battery to be charged according to the voltage of each battery in the energy storage battery pack, the method further comprises: controlling the total switch to be closed when determining the energy balance of the battery according to the voltage of each battery in the energy storage battery pack.

According to the voltage of each battery, it is determined that the energy balance of the battery needs to be included:

Determining that the voltages of the individual batteries in the energy storage battery pack are not equal; or

It is determined that the voltage of at least one of the energy storage battery packs is not within a preset voltage interval.

The embodiment of the present application further provides a battery energy equalization device, including:

a determining unit, configured to determine, according to a voltage of each battery in the energy storage battery pack, a battery that needs to be charged; and a first control unit, configured to control a switch in a charging branch corresponding to the battery that needs to be charged to be closed. The determining unit includes:

And a calculating subunit, configured to calculate a battery voltage average value according to a voltage of each battery in the energy storage battery pack; and a first determining subunit, configured to determine a battery whose voltage is less than the average value as a battery that needs to be charged. The determining unit includes:

a second determining subunit, configured to determine a voltage having the largest value from the voltages of the respective batteries of the energy storage battery pack; and a third determining subunit, configured to determine, to charge all the batteries except the battery corresponding to the voltage with the largest value Battery.

Also includes: The second control unit is configured to control the main switch to be closed when determining the energy equalization of the battery according to the voltage of each battery before determining the battery to be charged according to the voltage of each battery in the energy storage battery pack.

The second control unit is specifically configured to: when determining that the voltages of the respective batteries in the energy storage battery group are not equal, controlling the total switch to be closed; or determining that the voltage of at least one battery in the energy storage battery group is not in a preset voltage interval, Control the main switch to close.

The embodiment of the present application further provides an energy storage system, including an energy storage battery pack, and further comprising: the foregoing battery energy equalization circuit.

Also included: a battery voltage detector and a microprocessor;

The input end of each pair of battery voltage detectors is connected with the two ends of each battery in the energy storage battery pack; the output end of the battery voltage detector is connected to the input end of the microprocessor; the output ends of the microprocessor are respectively Corresponding to the control end of the switch connected in each charging branch;

a battery voltage detector for detecting a voltage of each battery in the energy storage battery pack;

And a microprocessor, configured to determine a battery to be charged according to a voltage of each battery in the energy storage battery pack, and control a switch in a charging branch corresponding to the battery to be charged to be closed.

In the embodiment of the present application, a charging branch is connected in parallel for each battery of the energy storage battery pack; each charging branch includes: a first end of the charging branch is connected to the first output end of the charger, and the charger is The second output terminal is connected to the second end of the charging branch through a switch; the first input end of the charger is connected to the first end of the energy storage battery pack, and the second input end of the charger is connected to the energy storage battery The second end of the group is connected; the charger charges the battery corresponding to the charging branch when the switch in the charging branch is closed. Therefore, the charger in each charging branch charges the corresponding battery through the energy of the energy storage battery pack. Compared with the prior art, no resistance additionally consumes energy in the energy storage battery pack, thereby reducing energy storage. The energy consumption in the battery pack improves the energy utilization efficiency of the energy storage battery pack. BRIEF DESCRIPTION OF THE DRAWINGS In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings to be used in the embodiments will be briefly described below. Obviously, the drawings in the following description are only Some of the embodiments of the application can be obtained by those of ordinary skill in the art in view of these drawings without additional effort.

1 is a schematic structural view of an energy storage battery pack;

1A is a structural diagram of a battery energy equalization circuit in the prior art;

2 is a schematic diagram of a first embodiment of a battery energy equalization circuit of the present application; 2A is a schematic diagram of a second embodiment of a battery energy equalization circuit of the present application;

3 is a schematic structural view of a charger of the present application;

FIG. 3A is a structural example of implementing a charger of the present application; FIG.

4 is a schematic diagram of a first embodiment of a battery energy equalization method of the present application;

4A is a schematic diagram of a second embodiment of a battery energy equalization method according to the present application;

5 is a schematic diagram of a first embodiment of a battery energy equalization device of the present application;

5A is a schematic diagram of a second embodiment of a battery energy equalization device of the present application;

6 is a schematic structural diagram of an energy storage system of the present application;

6A is a connection example of a battery voltage detector and a microprocessor of the present application;

6B is a schematic diagram of a connection structure between a microprocessor and a battery energy equalization circuit of the present application;

6C is an example of an implementation structure of a battery voltage detector of the present application. The technical solutions in the embodiments of the present application are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present application. It is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. example. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present application without departing from the scope of the invention are within the scope of the present application.

2 is a schematic diagram of a first embodiment of a battery energy equalization circuit of the present application. The battery energy equalization circuit can be applied to an energy storage battery pack to balance battery energy in the energy storage battery pack. As shown in FIG. 2, the battery energy equalization circuit includes:

A charging branch 201 is connected in parallel to each battery of the energy storage battery pack. Specifically, the first end of the charging branch 201 is connected to the first end of the charging branch 201 corresponding to the battery, and the second end of the charging branch 201 is connected to the second end of the charging branch 201. The charging branch 201 corresponds to the second end of the battery.

Each charging branch 201 may include: a first end of the charging branch 201 is connected to the first output end of the charger 2011, and a second output end of the charger 2011 passes through the switch K1 and the second end of the charging branch 201 End connection; the first input end of the charger 2011 is connected to the first end A1 of the energy storage battery pack, and the second input end of the charger 2011 is connected to the second end A2 of the energy storage battery pack; The device 2011 is used to charge the battery corresponding to the charging branch 201 when the switch K1 in the charging branch 201 is closed.

In FIG. 2, only three batteries in the energy storage battery pack are shown, and three batteries are connected in series, FIG. 2 is only an example, the specific number of batteries in the energy storage battery pack and the battery pack and structure in the energy storage battery pack. The application is not limited; and, in FIG. 2, only the charging branch structure in which three batteries are connected in parallel, and the charging circuit junction of other batteries in parallel are shown. The structure is the same as this, and will not be described here.

Wherein, when the first end of the battery is a positive end, the first end of the charging branch 201 is an output positive end, the first output end of the charger 2011 is an output positive end; when the second end of the battery is a negative end, charging The second end of the branch 201 is an output negative end, and the second output end of the charger 2011 is an output negative end; or

When the first end of the battery is the negative end, the first end of the charging branch 201 and the first output end of the charger 2011 are the output negative end, and when the second end of the battery is the positive end, the second of the charging branch 201 The second end of the terminal and charger 2011 is the output positive terminal.

Similarly, when the first end of the energy storage battery pack is a positive end, the first input end of the charger 2011 is an input positive end, the second end of the energy storage battery pack is a negative end, and the second input end of the charger 2011 For inputting the negative terminal; or, when the first end of the energy storage battery pack is the negative terminal, the first input end of the charger 2011 is the input negative end, and the second end of the energy storage battery pack is the positive end, the charger 2011 The second input is the input positive terminal.

Since the first input end of the charger 2011 is connected to the first end of the energy storage battery pack, the second input end of the charger 2011 is connected to the second end of the energy storage battery pack; thus, the charger 2011 is a battery The charged electrical energy comes from the energy storage battery pack.

Under the battery energy equalization circuit, when the voltage of the battery is lower than other battery voltages, the switch corresponding to the charging branch of the battery is turned on, the battery is charged by the charger in the charging branch, and the charger uses the energy storage battery. The total energy of the group is charged at a low voltage in the energy storage battery pack, thereby achieving battery energy equalization within the energy storage battery pack.

Moreover, the energy of the energy storage battery pack is not consumed in the whole process, and the battery energy balance is used in comparison with the prior art, the energy consumption of the energy storage battery pack is reduced, and the energy utilization efficiency of the energy storage battery pack is improved.

In addition, each battery in the energy storage battery pack has an independent charging branch, and the charging branch of one battery is damaged, which does not affect other charging branches, and thus does not affect the energy balance of other batteries.

Moreover, each of the batteries in the energy storage battery pack has an independent charging branch, so that the charging branches of the plurality of batteries or even all the batteries in the energy storage battery pack can be controlled to simultaneously charge the battery for energy equalization, thereby energy of the battery. The time required for equalization is shorter, which improves the energy balance efficiency of the battery; moreover, the battery energy equalization circuit is especially suitable for scenarios requiring fast equalization. Preferably, as shown in FIG. 2A, a total switch K can be set for the battery energy equalization circuit of the embodiment of the present application, and whether the battery energy equalization circuit is controlled by the main switch , can be set, and the total switch Κ can be set in the first charger 2011. Between the two input terminals and the second end of the energy storage battery pack, that is, the second input end of the charger 2011 in all the charging branches 201 is connected to the second end of the energy storage battery pack through the main switch Κ. 3 is a schematic diagram of an implementation structure of a charger in the battery energy equalization circuit shown in FIG. 2 and FIG. 2A, the charger includes: a coupler 301 and a rectifier 302;

The first input end of the coupler 301 serves as a first input end of the charger, and is connected to the first end of the energy storage battery pack, and the second input end of the coupler 301 serves as a second input end of the charger, and is connected to the energy storage battery pack. a second end of the coupler 301 is connected to the first input end of the rectifier 302, and a second output end of the coupler 301 is connected to the second input end of the rectifier 302;

The first output end of the rectifier 302 serves as a first output end of the charger, and the first end of the battery is connected to the charger, and the second output end of the rectifier 302 serves as a second output end of the charger, and the switch corresponds to the charger through the switch. The second end of the battery is connected.

The coupler 301 is configured to obtain energy for charging the battery from the energy storage battery pack, and transmit the acquired energy to the rectifier 302;

The rectifier 302 is operative to rectify the electrical energy transmitted by the coupler 301 into a stable direct current that is supplied to the battery to charge the battery.

Referring to FIG. 3A, the coupler 301 can be implemented by a coupling transformer;

The rectifier 302 can include:

The first input end of the rectifier 302 is connected to the first output end of the rectifier through the reversed first diode D1, and is also connected to the second output end of the rectifier 302 through the second diode D2;

The second input of the rectifier 302 is coupled to the first output of the rectifier 302 via a reversed third diode D3 and to the second output of the rectifier 302 via a fourth diode D4.

3 and 3A show only an implementation example of the charger. In practical applications, the charger can also be implemented by using other charging circuits as long as the battery can be charged by using the energy of the energy storage battery pack. The embodiment of the present application further provides a battery energy equalization method, which can implement control of the foregoing battery energy equalization circuit. Referring to FIG. 4, the method may include:

Step 401: Determine, according to the voltage of each battery in the energy storage battery pack, a battery that needs to be charged;

Step 402: Controlling that the switch in the charging branch corresponding to the battery that needs to be charged is closed.

Preferably, step 401 can include:

Alternatively, step 401 can include: Determining the voltage having the largest value from the voltages of the respective batteries of the energy storage battery pack;

All the batteries except the battery corresponding to the voltage having the largest value are determined as the batteries to be charged.

Of course, in the actual application, the step 401 can also be implemented by other methods, such as setting a voltage threshold in advance, and determining a battery whose voltage is less than the voltage threshold as a battery to be charged, etc., which is not limited herein.

When the battery energy equalization circuit is implemented by using the structure shown in FIG. 2A, referring to FIG. 4A, before step 401, the method further includes: Step 400: When determining the energy balance of the battery according to the voltage of each battery in the energy storage battery pack, the control station The main switch is closed.

Thus, the main switch is first controlled to be closed, and the battery energy equalization circuit is started to operate; thereafter, in steps 401 and 402, the battery to be charged can be charged by controlling the closing and opening of the switches in the respective charging branches.

Preferably, the determining, according to the voltage of each battery, that the energy balance needs to be performed on the battery may include: determining that the voltages of the respective batteries in the energy storage battery group are not equal; or

The equalization control method shown in Fig. 4 and Fig. 4A realizes the charging control of the battery in the energy storage battery pack by controlling the switches in the battery energy equalization circuit, so that the batteries in the energy storage battery pack are energy balanced. Corresponding to the above method, the embodiment of the present application further provides a battery energy equalizing device. Referring to FIG. 5, the device includes:

The determining unit 510 is configured to determine, according to the voltage of each battery in the energy storage battery pack, a battery that needs to be charged. The first control unit 520 is configured to control the opening and closing in the charging branch corresponding to the battery that needs to be charged.

Preferably, the determining unit 510 can include:

And a calculating subunit, configured to calculate a battery voltage average value according to a voltage of each battery in the energy storage battery pack; and a first determining subunit, configured to determine a battery whose voltage is less than the average value as a battery that needs to be charged. Alternatively, preferably, the determining unit 510 may include:

Preferably, referring to FIG. 5A, the apparatus may further include:

The second control unit 530 is configured to control the main switch to be closed when it is determined that the battery needs to be energy balanced according to the voltage of each battery before determining the battery to be charged according to the voltage of each battery in the energy storage battery pack. Preferably, the second control unit 530 is specifically configured to: when determining that the voltages of the respective batteries in the energy storage battery group are not equal, controlling the total switch to be closed; or determining that the voltage of at least one battery in the energy storage battery pack is not in the pre-predetermined state When the voltage interval is set, the control master switch is closed.

The equalization control device shown in Fig. 5 and Fig. 5A realizes the charging control of the battery in the energy storage battery pack by controlling the switches in the battery energy equalization circuit, so that the batteries in the energy storage battery pack are energy balanced.

Preferably, the equalization control method and the equalization control device can be implemented by a microprocessor.

Alternatively, the equalization control device may also be implemented by a hardware circuit. In addition, the embodiment of the present application further provides an energy storage system, as shown in FIG. 6, including the energy storage battery pack 610, and further includes: a battery energy equalization circuit 620. Preferably, battery voltage detector 630 and microprocessor 640 are also included.

Referring to FIG. 6A, the battery voltage detector 630 includes at least one pair of input terminals for voltage detection, and each pair of input terminals are respectively connected to two ends of the battery in the energy storage battery pack; thereby respectively detecting each battery in the energy storage battery pack. Voltage.

The output of the battery voltage detector 630 is connected to the input of the microprocessor 640, and the voltage of each battery detected is transmitted to the microprocessor 640;

Referring to FIG. 6B, each output end of the microprocessor 640 is respectively connected to the control end of the switch K1 in each charging branch; when the switch K2 is realized by a triode, the control end of the switch is the base of the triode, when the switch When implemented by a MOS transistor, the control terminal of the switch is the gate of the MOS transistor; or the switch can also be implemented by a controllable transistor with a control terminal.

Preferably, the battery voltage detector 630 can amplify the voltage of each battery in the energy storage battery pack, convert the amplified voltage into a digital signal and send it to the microprocessor 640; at this time, the battery voltage detector 630 can pass the map. 6C is an operational amplifier group and an analog-to-digital converter. For a specific implementation circuit, reference may be made to a battery voltage detecting circuit in the prior art, which is not described herein.

The microprocessor 640 is configured to determine a battery that needs to be charged according to a voltage of each battery in the energy storage battery pack; and control a switch in the charging branch corresponding to the battery that needs to be charged to be closed.

In the energy storage system shown in FIG. 6, a charger is separately provided for each battery, and when the voltage of the battery is lower than other battery voltages, the switch corresponding to the charging circuit of the battery is turned on, the battery is charged by the charger, and the charger is used. The total energy of the energy storage battery pack is charged at a low voltage in the energy storage battery pack, thereby achieving battery energy equalization within the energy storage battery pack.

Preferably, the microprocessor 640 can be implemented by the structure of the battery energy equalization device of FIGS. 5 and 5A. Moreover, the energy of the energy storage battery pack is not consumed in the whole process, and the energy balance of the battery is reduced compared with the prior art, thereby reducing the energy consumption of the energy storage battery pack and improving the energy utilization efficiency of the energy storage battery pack.

In addition, each battery in the energy storage battery pack has an independent charging branch, and the charging branch of one battery is damaged, which will not affect other charging branches, and thus will not affect the equalization effect of other batteries.

Moreover, each of the batteries in the energy storage battery pack has an independent charging branch, so that the charging branches of the plurality of batteries or even all the batteries in the energy storage battery pack can be controlled to simultaneously charge the battery for energy equalization, thereby energy of the battery. The time required for equalization is shorter, which improves the energy balance efficiency of the battery; moreover, the battery energy equalization circuit is especially suitable for scenarios requiring fast equalization. The various embodiments in the present specification are described in a progressive manner, and the same or similar parts between the various embodiments may be referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the description of the method embodiment.

The embodiments of the present application described above are not intended to limit the scope of the present application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application are intended to be included within the scope of this application.

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Claims

Rights request

A battery energy equalization circuit, comprising:

Each charging branch includes: a first end of the charging branch is connected to the first output end of the charger, and a second output end of the charger is connected to the second end of the charging branch through a switch; The first input end is connected to the first end of the energy storage battery pack, and the second input end of the charger is connected to the second end of the energy storage battery pack;

The charger charges the battery corresponding to the charging branch when the switch in the charging branch is closed.

2. The battery energy equalization circuit according to claim 1, wherein the charger comprises: a coupler and a rectifier; wherein

3. The battery energy equalization circuit according to claim 2, wherein the coupler is implemented by a coupling transformer.

4. The battery energy equalization circuit according to claim 2 or 3, wherein the rectifier comprises:

a first input end of the rectifier is connected to the first output end of the rectifier through the reversed first diode, and is also connected to the second output end of the rectifier through the second diode;

A second input of the rectifier is coupled to the first output of the rectifier via a reversed third diode and to a second output of the rectifier via a fourth diode.

The battery energy equalization circuit according to any one of claims 1 to 4, further comprising:

The second input of the charger in all charging branches is connected to the energy storage battery pack through the main switch One 3⁄4.

6. A battery energy equalization method, characterized by comprising:

7. The method according to claim 6, wherein the determining the battery to be charged according to the voltage of each battery in the energy storage battery pack comprises:

8. The method according to claim 6, wherein the determining the battery to be charged according to the voltage of each battery in the energy storage battery pack comprises:

The method according to any one of claims 6 to 8, wherein before determining the battery to be charged according to the voltage of each battery in the energy storage battery group, the method further includes:

The main switch is controlled to be closed when it is determined that the battery needs to be energy balanced according to the voltage of each battery in the energy storage battery pack.

10. The method according to claim 9, wherein determining the energy balance of the battery according to the voltage of each battery comprises:

11. A battery energy equalization device, comprising:

a determining unit, configured to determine a battery to be charged according to a voltage of each battery in the energy storage battery pack;

a first control unit, configured to control a switch in a charging branch corresponding to the battery that needs to be charged Closed.

The device according to claim 11, wherein the determining unit comprises: a calculating subunit, configured to calculate a battery voltage average value according to voltages of respective batteries in the energy storage battery pack;

The first determining subunit is configured to determine a battery whose voltage is less than the average value as a battery that needs to be charged.

The device according to claim 11, wherein the determining unit comprises: a second determining subunit, configured to determine a voltage having the largest value from voltages of the respective batteries of the energy storage battery;

The third determining subunit is configured to determine all the batteries except the battery corresponding to the voltage having the largest value as the battery to be charged.

The device according to any one of claims 11 to 13, further comprising: a second control unit, configured to determine, according to the voltage of each battery in the energy storage battery pack, a battery to be charged, according to each battery When the voltage is determined to require energy equalization of the battery, the control master switch is closed.

The device according to claim 14, wherein the second control unit is specifically configured to: when determining that the voltages of the batteries in the energy storage battery group are not equal, controlling the main switch to be closed; or determining the energy storage battery When the voltage of at least one battery in the group is not within the preset voltage interval, the control master switch is closed.

16. An energy storage system, comprising: an energy storage battery pack, further comprising:

The battery energy equalization circuit of any of 1 to 5.

The system according to claim 16, further comprising: a battery voltage detector and a microprocessor; wherein

The input end of each pair of battery voltage detectors is connected with the two ends of each battery in the energy storage battery pack; the output end of the battery voltage detector is connected to the input end of the microprocessor; the output ends of the microprocessor are respectively Corresponding to the control end of the switch connected in each charging branch; a battery voltage detector for detecting a voltage of each battery in the energy storage battery pack;

The system according to claim 17, wherein the microprocessor comprises the apparatus of any one of claims 11 to 15.