CN115663978B

CN115663978B - Battery energy storage power supply system, and voltage balancing method and device of battery pack

Info

Publication number: CN115663978B
Application number: CN202211595671.8A
Authority: CN
Inventors: 邓志江; 王祥
Original assignee: Foxess Co Ltd
Current assignee: Foxess Co ltd
Priority date: 2022-12-13
Filing date: 2022-12-13
Publication date: 2023-04-07
Anticipated expiration: 2042-12-13
Also published as: CN115663978A

Abstract

The application discloses a battery energy storage and power supply system, and a voltage balancing method and device of a battery pack. The method comprises the following steps: the battery control unit acquires a voltage signal of each battery pack in a battery pack power supply structure; under the condition that the voltage difference value between any two battery packs is larger than or equal to a first preset value, determining a battery pack to be charged and a battery pack to be discharged; outputting a switch control signal to the selection switch unit, and respectively communicating the battery pack to be charged and the battery pack to be discharged with the second isolation DC/DC converter and the first isolation DC/DC converter; the first controller is used for controlling the first isolation DC/DC converter so that the battery pack to be discharged transmits energy to the direct current bus; and outputting a charging instruction through the second controller to control the second isolation DC/DC converter, so that the battery pack to be charged receives energy transmitted by the direct current bus. Through the application, the problems of low electric energy utilization rate and poor reliability in the process of balancing the voltage between the battery packs in the battery energy storage power supply system in the related technology are solved.

Description

Battery energy storage power supply system, and voltage balancing method and device of battery pack

Technical Field

The application relates to the field of power supplies, in particular to a battery energy storage power supply system, and a voltage balancing method and device of a battery pack.

Background

In the correlation technique, on the one hand, electric core brand and firm are more and more, and single electric core brand can not satisfy the product demand, and different brand electric cores are used with each other often, even for same brand, the capacity of electric core, stepping, batch probably are inconsistent again, and this all can lead to the voltage unbalance. To the inconsistent problem of capacity, stepping, batch of electric core, can make capacity, stepping, batch of electric core etc. all unanimous through improving the production management and control, but this will lead to warehouse management cost high, and bring very big limitation for electric core application. On the other hand, in practical application, with the increase of the electric devices, the current battery system of the user may not meet the requirement, and the battery system needs to be additionally expanded, that is, the number of the battery packs connected in series or the number of the battery clusters connected in parallel is increased.

When the battery system is charged, the battery pack with high voltage is charged quickly, and the battery pack with low voltage cannot be charged fully when the charging is stopped in advance; when discharging, the battery pack with low voltage discharges quickly, and discharges in advance to cut off, so that the battery pack with high voltage cannot discharge fully, and the usable energy of the whole energy storage battery system is greatly reduced, even cannot be used.

In the related technology, a switch resistance series branch connected with a battery cell series structure in parallel is added in each battery pack, when the voltage of one battery pack is too high, a switch tube in the switch resistance series branch in the battery pack is conducted, and the battery cell series structure discharges through the conducted switch tube and the conducted resistor, so that the voltage balance between the battery packs is achieved. However, the scheme consumes the electric energy in the form of heat energy, so that the electric energy utilization rate of the battery system is low, and the method is contrary to the social requirement of energy conservation and environmental protection.

In addition, the bidirectional DC/DC converter connected with the battery cell series structure in parallel is added in each battery pack, the charging and discharging working conditions of each battery cell series structure can be independently controlled by controlling the bidirectional DC/DC converter, and the voltage balance among all the battery packs is kept. However, the charge and discharge of the battery pack need to pass through the corresponding bidirectional DC/DC converter, and the rated power of the bidirectional DC/DC converter needs to be greater than or equal to the rated power of the battery pack, which not only results in high cost of the bidirectional DC/DC converter, but also results in high power consumption of the bidirectional DC/DC converter, low efficiency of the whole system, fast temperature rise of the battery pack, and influence on the service life of the whole battery system. In addition, the battery system often fails to detect the position and cause of the fault due to abnormal power supply of the controller, which brings great inconvenience to subsequent fault removal and causes low system reliability.

Aiming at the problems of low electric energy utilization rate and poor reliability when the voltages between the battery packs in the battery energy storage and power supply system are balanced in the related technology, an effective solution is not provided at present.

Disclosure of Invention

The main purpose of the present application is to provide a battery energy storage and power supply system, and a voltage balancing method and device for battery packs, so as to solve the problems of low electric energy utilization rate and poor reliability when balancing voltages between battery packs in the battery energy storage and power supply system in the related art.

To achieve the above object, according to one aspect of the present application, a battery energy storage power supply system is provided. The system comprises: the battery pack power supply structure comprises a plurality of battery packs, and the battery packs are sequentially connected in series to form a battery pack series connection structure; the first end of the selection switch unit is connected with each battery pack, and the second end of the selection switch unit is respectively connected with the first isolation DC/DC converter and the second isolation DC/DC converter and used for receiving switch control signals sent by the battery control unit and controlling different battery packs to be communicated with the first isolation DC/DC converter and the second isolation DC/DC converter according to the switch control signals; the first end of the first isolation DC/DC converter is connected with the second end of the selection switch unit, and the second end of the first isolation DC/DC converter is connected with the direct current bus; a first end of the second isolation DC/DC converter is connected with the second end of the selection switch unit, and a second end of the second isolation DC/DC converter is connected with the direct current bus; the first controller is connected with the first isolation DC/DC converter and used for receiving a discharge instruction sent by the battery control unit and controlling the first isolation DC/DC converter to transmit energy from the first end to the second end according to the discharge instruction; the second controller is connected with the second isolation DC/DC converter and used for receiving a charging instruction sent by the battery control unit and controlling the second isolation DC/DC converter to transmit energy from the second end to the first end according to the charging instruction; and the battery control unit receives the state signal of the battery pack power supply structure, outputs a discharging instruction to the first controller according to the state signal, outputs a charging instruction to the second controller and outputs a switch control signal to the selection switch unit.

Optionally, the selection switch unit includes a plurality of groups of switch tubes, each group of switch tubes is connected to a battery pack, and each group of switch tubes includes: the first end of the first switch tube is connected with the positive output end of the battery pack, and the second end of the first switch tube is connected with the positive voltage end of the first isolation DC/DC converter; a first end of the second switching tube is connected with the positive output end of the battery pack, and a second end of the second switching tube is connected with the positive voltage end of the first end of the second isolation DC/DC converter; a first end of the third switching tube is connected with the negative output end of the battery pack, and a second end of the third switching tube is connected with the negative voltage end of the first isolation DC/DC converter; and a first end of the fourth switch tube is connected with the negative output end of the battery pack, and a second end of the fourth switch tube is connected with the negative voltage end of the first end of the second isolation DC/DC converter.

Optionally, each battery pack comprises: the battery cell series structure comprises a plurality of battery cells connected in series, and two ends of the battery cell series structure form two ends of the battery pack; the battery sampling chips are connected in parallel at two ends of the battery cell series structure and used for acquiring state signals of the battery cell series structure and sending the state signals of the battery cell series structure to the battery pack management unit; and the battery pack management unit is used for receiving the state signal of the battery cell series structure sent by the battery sampling chip and sending the state signal of the battery cell series structure to the battery control unit.

Optionally, the battery energy storage power supply system further includes: the auxiliary DC/DC converter is used for converting the voltage of the direct current bus into power supply voltage and supplying power to the battery control unit, the battery pack management unit of each battery pack, the first controller, the second controller and the battery sampling chip.

Optionally, the battery energy storage power supply system further includes: and the input end of the load power supply converter is connected with the output end of the battery pack power supply structure, the output end of the load power supply converter is connected with the load and is used for converting the direct current provided by the battery pack power supply structure into direct current or alternating current required by the load, the load power supply converter is a DC/DC converter or a DC/AC converter, and the two ends of the battery pack series connection structure form the output end of the battery pack power supply structure.

In order to achieve the above object, according to one aspect of the present application, there is provided a voltage equalization method of a battery pack. The method comprises the following steps: the battery control unit acquires a voltage signal of each battery pack in a battery pack power supply structure to obtain a plurality of voltage signals; the battery control unit judges whether a voltage difference value between any two battery packs is larger than or equal to a first preset value or not; under the condition that the voltage difference value between any two battery packs is larger than or equal to a first preset value, the battery control unit determines a battery pack to be charged and a battery pack to be discharged from a battery pack power supply structure; the battery control unit outputs a switch control signal to the selection switch unit, controls the selection switch unit to act through the switch control signal, and communicates the battery pack to be charged with the second isolation DC/DC converter and communicates the battery pack to be discharged with the first isolation DC/DC converter; the battery control unit outputs a discharge instruction to the first controller, and controls the first isolation DC/DC converter to work through the discharge instruction so as to control the battery pack to be discharged to transfer energy to the direct current bus, wherein the first isolation DC/DC converter has a working mode of transferring energy from the first end to the second end; the battery control unit outputs a charging instruction to the second controller, and controls the second isolation DC/DC converter to work through the charging instruction so as to control the battery pack to be charged to receive the energy transmitted by the direct current bus, wherein the working mode of the second isolation DC/DC converter is to transmit the energy from the second end to the first end.

Optionally, the switch unit includes multiple groups of switch tubes, each group of switch tubes includes a first switch tube, a second switch tube, a third switch tube and a fourth switch tube, the switch unit is controlled by the switch control signal to operate, the battery pack to be charged is communicated with the second isolated DC/DC converter, and the battery pack to be discharged is communicated with the first isolated DC/DC converter, including: a second switching tube between the positive output end of each battery pack to be charged and the positive voltage end of the first end of the second isolation DC/DC converter, a fourth switching tube between the negative output end of each battery pack to be charged and the negative voltage end of the first end of the second isolation DC/DC converter are closed through a switch control signal, and a first switching tube between the positive output end of each battery pack to be charged and the positive voltage end of the first isolation DC/DC converter, and a third switching tube between the negative output end of each battery pack to be charged and the negative voltage end of the first isolation DC/DC converter are opened; and a first switching tube between the positive output end of each battery pack to be discharged and the positive voltage end of the first isolation DC/DC converter, a third switching tube between the negative output end of each battery pack to be discharged and the negative voltage end of the first isolation DC/DC converter are closed through a switching control signal, and a second switching tube between the positive output end of each battery pack to be discharged and the positive voltage end of the first end of the second isolation DC/DC converter, and a fourth switching tube between the negative output end of each battery pack to be discharged and the negative voltage end of the first end of the second isolation DC/DC converter are opened.

Optionally, the determining, by the battery control unit, the battery pack to be charged from the battery pack power supply structure includes: calculating a difference value between the voltage signal of each battery pack and a second preset value to obtain a plurality of difference values, and obtaining a positive number difference value from the plurality of difference values to obtain a plurality of positive number difference values, wherein the second preset value is at least one of the following values: the mean value of the plurality of voltage signals and the median of the plurality of voltage signals; determining a maximum positive difference value from the positive difference values, and judging whether a battery pack corresponding to the maximum positive difference value has a first battery pack string or not, wherein the first battery pack string is formed by a plurality of battery packs adjacent to the battery pack corresponding to the maximum positive difference value, and the difference value between a voltage signal of the battery pack in the first battery pack string and a second preset value is a positive number; under the condition that the battery pack corresponding to the maximum positive number difference value has a first battery pack string, determining the battery pack in the first battery pack string and the battery pack corresponding to the maximum positive number difference value as battery packs to be charged; and under the condition that the battery pack corresponding to the maximum positive number difference value does not have the first battery pack string, determining the battery pack corresponding to the maximum positive number difference value as a battery pack to be charged.

Optionally, the determining, by the battery control unit, the battery pack to be discharged from the battery pack power supply structure includes: calculating the difference between the voltage signal of each battery pack and a second preset value to obtain a plurality of differences, and obtaining a negative difference from the plurality of differences to obtain a plurality of negative differences, wherein the second preset value is at least one of the following values: the mean value of the plurality of voltage signals and the median of the plurality of voltage signals; determining a minimum negative difference value from the negative difference values, and judging whether a battery pack corresponding to the minimum negative difference value has a second battery pack string or not, wherein the second battery pack string is composed of a plurality of battery packs adjacent to the battery pack corresponding to the minimum negative difference value, and the difference value between the voltage signal of the battery pack in the second battery pack string and a second preset value is a negative number; under the condition that the battery pack corresponding to the minimum negative number difference value has a second battery pack string, determining the battery pack in the second battery pack string and the battery pack corresponding to the minimum negative number difference value as battery packs to be discharged; and under the condition that the battery pack corresponding to the minimum negative number difference value does not have the second battery pack string, determining the battery pack corresponding to the minimum negative number difference value as the battery pack to be discharged.

Optionally, after the battery control unit determines whether a voltage difference value between any two battery packs is greater than or equal to a first preset value, the method further includes: and under the condition that the voltage difference value is smaller than a first preset value, the battery control unit sends a preset discharge instruction to the first controller, wherein the preset discharge instruction is used for controlling the battery pack to discharge to the direct-current bus so as to supply power to the battery control unit, the first controller, the second controller, the battery pack management unit of each battery pack and the battery sampling chip through an auxiliary DC/DC converter connected with the direct-current bus.

In order to achieve the above object, according to another aspect of the present application, there is provided a voltage equalizing device of a battery pack. The device comprises: the acquisition unit is used for acquiring a voltage signal of each battery pack in the battery pack power supply structure through the battery control unit to obtain a plurality of voltage signals; the judging unit is used for judging whether a voltage difference value between any two battery packs is larger than or equal to a first preset value or not through the battery control unit; the battery control unit is used for determining a battery pack to be charged and a battery pack to be discharged from the battery pack power supply structure under the condition that the voltage difference value between any two battery packs is larger than or equal to a first preset value; the first control unit is used for outputting a switch control signal to the selection switch unit through the battery control unit, controlling the selection switch unit to act through the switch control signal, communicating the battery pack to be charged with the second isolation DC/DC converter and communicating the battery pack to be discharged with the first isolation DC/DC converter; the second control unit is used for outputting a discharging instruction to the first controller through the battery control unit and controlling the first isolation DC/DC converter to work through the discharging instruction so as to control the battery pack to be discharged to transfer energy to the direct current bus, wherein the first isolation DC/DC converter is used for transferring the energy from the first end to the second end in a working mode; and the third control unit is used for outputting a charging instruction to the second controller through the battery control unit, and controlling the second isolation DC/DC converter to work through the charging instruction so as to control the battery pack to be charged to receive the energy transmitted by the direct current bus, wherein the second isolation DC/DC converter has a working mode of transmitting the energy from the second end to the first end.

By the application, the following steps are adopted: the battery control unit acquires a voltage signal of each battery pack in a battery pack power supply structure to obtain a plurality of voltage signals; the battery control unit judges whether a voltage difference value between any two battery packs is larger than or equal to a first preset value or not; under the condition that the voltage difference value between any two battery packs is larger than or equal to a first preset value, the battery control unit determines a battery pack to be charged and a battery pack to be discharged from a battery pack power supply structure; the battery control unit outputs a switch control signal to the selection switch unit, controls the selection switch unit to act through the switch control signal, and communicates the battery pack to be charged with the second isolation DC/DC converter and communicates the battery pack to be discharged with the first isolation DC/DC converter; the battery control unit outputs a discharge instruction to the first controller, and controls the first isolation DC/DC converter to work through the discharge instruction so as to control the battery pack to be discharged to transfer energy to the direct current bus, wherein the first isolation DC/DC converter has a working mode of transferring energy from the first end to the second end; the battery control unit outputs a charging instruction to the second controller, and controls the second isolation DC/DC converter to work through the charging instruction so as to control the battery pack to be charged to receive energy transmitted by the direct current bus, wherein the second isolation DC/DC converter works in a mode of transmitting the energy from the second end to the first end, and the problems of low electric energy utilization rate and poor reliability in the process of balancing the voltage between the battery packs in the battery energy storage and power supply system in the related art are solved. The charging command is sent to the second controller, the discharging command is sent to the first controller, and the switch control signal is sent to the selection switch unit when the voltage is unbalanced, so that the first isolation DC/DC converter is controlled to discharge the battery pack to be discharged, the second isolation DC/DC converter is controlled to charge the battery pack to be charged, and the high electric energy utilization rate and the high reliability are achieved when the voltage among the battery packs is equalized.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the application and, together with the description, serve to explain the application and are not intended to limit the application. In the drawings:

fig. 1 is a schematic structural diagram of a battery energy storage power supply system provided according to an embodiment of the present application;

fig. 2 is a schematic structural diagram of a selection switch unit, a first isolation DC/DC converter and a second isolation DC/DC converter in a battery energy storage power supply system provided according to an embodiment of the present application;

fig. 3 is a schematic diagram of a converter circuit in an alternative battery energy storage power supply system according to an embodiment of the present application;

fig. 4 is a schematic structural diagram of an auxiliary DC/DC converter in a battery energy storage power supply system provided according to an embodiment of the present application;

fig. 5 is a flowchart of a voltage equalization method of a battery pack according to an embodiment of the present application;

fig. 6 is a schematic diagram of a voltage equalization apparatus of a battery pack provided according to an embodiment of the present application.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.

In order to make the technical solutions of the present application better understood by those skilled in the art, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only some embodiments of the present application, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It should be noted that the terms "first," "second," and the like in the description and claims of this application and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It should be understood that the data so used may be interchanged under appropriate circumstances such that embodiments of the application described herein may be used. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

The present invention is described below with reference to preferred implementation steps, and fig. 1 is a schematic structural diagram of a battery energy storage and power supply system provided in an embodiment of the present application, and as shown in fig. 1, the system includes:

the battery pack power supply structure 10 comprises a plurality of battery packs, and the battery packs are sequentially connected in series to form a battery pack series structure.

Optionally, in the battery energy storage and power supply system provided in the embodiment of the present application, each battery pack includes: the battery cell series structure 101 comprises a plurality of battery cells connected in series, and two ends of the battery cell series structure 101 form two ends of a battery pack; the battery sampling chip 102 is connected in parallel to two ends of the electrical core series structure 101, and is configured to collect a state signal of the electrical core series structure 101 and send the state signal of the electrical core series structure 101 to the battery pack management unit 103; the battery pack management unit 103 receives the state signal of the cell series structure 101 sent by the battery sampling chip 102, and sends the state signal of the cell series structure 101 to the battery control unit 70.

Specifically, as shown in fig. 1, each battery pack includes a battery cell series structure 101, a battery sampling chip 102, and a battery pack management unit 103. The electric core series structure 101 stores electric energy or releases electric energy through a plurality of electric cores connected in series, voltage balance among the electric cores in the electric core series structure 101 is realized through a Battery sampling chip 102 (AFE, analog Front End), and is responsible for acquiring a state signal of the electric core series structure 101, the acquired state signal is sent to a Battery pack Management Unit 103 (BMU), and the Battery pack Management Unit 103 sends the received state signal to the Battery control Unit 70.

Each of the battery cell series structures 101 includes a plurality of battery cells connected in series, and as shown in fig. 1, the first battery cell series structure 101 in the battery pack 1 until the nth battery cell series structure 101 in the battery pack n form a battery pack series structure, and each of the battery cell series structures 101 includes one of the battery cells 1 to x. The first cell series structure 101 to the nth cell series structure 101 in the plurality of battery packs are sequentially connected in series to form a positive output terminal BAT + and a negative output terminal BAT-of the battery pack power supply structure 10. Power is supplied to the load 90 through the positive output terminal BAT + and the negative output terminal BAT-, or power is stored to the battery pack power supply structure 10.

And a first end of the selection switch unit 20 is connected to each battery pack, and a second end of the selection switch unit 20 is connected to the first isolation DC/DC converter 30 and the second isolation DC/DC converter 40 respectively, and is configured to receive a switch control signal sent by the battery control unit 70, and control different battery packs to be communicated with the first isolation DC/DC converter 30 and the second isolation DC/DC converter 40 according to the switch control signal.

Specifically, the first terminal of the selection switch unit 20 may be one terminal close to the battery pack power supply structure 10, and the second terminal of the selection switch unit 20 may be one terminal close to the first and second isolation DC/

DC converters

30 and 40. The selection switch unit 20 includes a plurality of switch tubes, and each battery pack is connected to a group of 4 switch tubes. After receiving the switch control signal sent by the battery control unit 70, the switch tubes in the group of switch tubes corresponding to the battery pack to be charged or discharged are controlled to be turned on or off, so that the battery pack to be charged or discharged is communicated with the first isolated DC/DC converter 30 or the second isolated DC/DC converter 40 according to the switch control signal.

And a first end of the first isolation DC/DC converter 30 is connected with the second end of the selection switch unit 20, and a second end of the first isolation DC/DC converter 30 is connected with the direct current bus.

Specifically, the first isolation DC/DC converter 30 may be an isolation bidirectional DC/DC converter, the first terminal of the first isolation DC/DC converter 30 may be one terminal close to the selection switch unit 20, and the second terminal of the first isolation DC/DC converter 30 may be one terminal close to the first controller 50. The first isolated DC/DC converter 30 may be a bidirectional full-bridge converter, a push-pull converter, a half-bridge converter, or the like, and the specific structure thereof is not limited in this application. The second end of the first isolated DC/DC converter 30 is connected to the positive DC Bus + and the negative DC Bus-. The energy of the battery pack needing to be discharged is transmitted to the direct current bus through the first isolation DC/DC converter 30 under the condition that the corresponding switch tube is conducted, so that the battery pack to be discharged is discharged.

And a second isolation DC/DC converter 40, wherein a first end of the second isolation DC/DC converter 40 is connected to the second end of the selection switch unit 20, and a second end of the second isolation DC/DC converter 40 is connected to the DC bus.

Specifically, the second isolation DC/DC converter 40 may be an isolation bidirectional DC/DC converter, a first terminal of the second isolation DC/DC converter 40 may be one terminal near the selection switch unit 20, and a second terminal of the second isolation DC/DC converter 40 may be one terminal near the second controller 60. The second isolated DC/DC converter 40 may be a bidirectional full-bridge converter, a push-pull converter, a half-bridge converter, or the like, and the specific structure thereof is not limited in the present application. The second end of the second isolated DC/DC converter 40 is connected to the positive DC Bus + and the negative DC Bus-. The energy of the direct current bus is transferred to the battery pack needing to be charged under the condition that the corresponding switch tube is conducted through the second isolation DC/DC converter 40, so that the battery pack to be charged is charged.

It should be noted that the first isolation DC/DC converter 30 and the second isolation DC/DC converter 40 are connected between the battery pack and the DC bus, and the battery pack power supply structure 10 stores power and supplies power to a load through the positive output terminal BAT + and the negative output terminal BAT —, so that the storage and the supply of power to the load of the battery pack power supply structure 10 do not need to pass through the first isolation DC/DC converter 30 and the second isolation DC/DC converter 40, and the first isolation DC/DC converter 30 and the second isolation DC/DC converter 40 only relate to power which needs to be voltage-balanced and flows between the battery packs. The voltage of each battery pack is usually between 40V and 70V, and the unbalanced voltage between the battery packs is usually about 1V, so the rated power of the first isolation DC/DC converter 30 and the second isolation DC/DC converter 40 is very small, usually only 10% to 20% of the rated power of the battery packs, which greatly reduces the cost and the design difficulty of the first isolation DC/DC converter 30 and the second isolation DC/DC converter 40, and the power consumption of the first isolation DC/DC converter 30 and the second isolation DC/DC converter 40 is small, so that the power storage and discharge efficiency of the whole battery energy storage and supply system is high, and the service life of the whole battery energy storage and supply system is prolonged.

And the first controller 50 is connected with the first isolation DC/DC converter 30 and is used for receiving a discharge command sent by the battery control unit 70 and controlling the first isolation DC/DC converter 30 to transmit energy from the first end to the second end according to the discharge command.

Specifically, the first controller 50 is communicatively connected to the first isolation DC/DC converter 30, and the first controller 50 is responsible for an operating state of the first isolation DC/DC converter 30, and when the first controller 50 receives a discharge instruction, the first isolation DC/DC converter 30 is controlled to start operating, and when the first isolation DC/DC converter 30 operates and a switch tube corresponding to a battery pack to be discharged in the selection switch unit 20 is turned on, the first isolation DC/DC converter 30 is enabled to transmit energy from the first end to the second end.

And a second controller 60 connected to the second isolated DC/DC converter 40 for receiving a charging command from the battery control unit and controlling the second isolated DC/DC converter 40 to transfer energy from the second terminal to the first terminal according to the charging command.

Specifically, the second controller 60 is communicatively connected to the second isolation DC/DC converter 40, and the second controller 60 is responsible for the operating state of the second isolation DC/DC converter 40, and when the second controller 60 receives a charging instruction, the second isolation DC/DC converter 40 is controlled to start operating, and when the second isolation DC/DC converter 40 operates and the switch tube corresponding to the battery pack to be charged in the selection switch unit 20 is turned on, the second isolation DC/DC converter 40 is enabled to transfer energy from the second end to the first end.

The battery control unit 70 receives the status signal of the battery pack power supply structure 10, outputs a discharge command to the first controller 50, outputs a charge command to the second controller 60 according to the status signal, and outputs a switch control signal to the selection switch unit 20.

Specifically, the state signal S1 may be a voltage signal representing each cell series structure 101 in the battery pack power supply structure 10. The Battery Control Unit 70 (BCU, battery Control Unit) receives the state signal S1 collected from the Battery pack power supply structure 10, outputs a discharge instruction to the first controller 50, outputs a charge instruction to the second controller 60, and outputs a switch Control signal to the selection switch Unit 20 according to the state signal S1.

For example, when the status signal S1 indicates that the voltage difference between the battery packs in the battery pack power supply structure 10 is greater than or equal to the first preset value, which indicates that the voltages between the battery packs in the battery pack power supply structure 10 are unbalanced, the battery control unit 70 outputs a discharge instruction to the first controller 50, outputs a charge instruction to the second controller 60, and outputs a switch control signal to the selection switch unit 20, so as to recover the voltage balance by controlling energy transfer between the battery pack power supply structure 10 and the dc bus through the discharge instruction, the charge instruction, and the switch control signal.

The battery energy storage power supply system provided by the embodiment of the application comprises a plurality of battery packs through a battery pack power supply structure, wherein the plurality of battery packs are sequentially connected in series to form a battery pack series structure, and two ends of the battery pack series structure form the output end of the battery pack power supply structure; the first end of the selection switch unit is connected with each battery pack, and the second end of the selection switch unit is respectively connected with the first isolation DC/DC converter and the second isolation DC/DC converter and used for receiving switch control signals sent by the battery control unit and controlling different battery packs to be communicated with the first isolation DC/DC converter and the second isolation DC/DC converter according to the switch control signals; the first end of the first isolation DC/DC converter is connected with the second end of the selection switch unit, and the second end of the first isolation DC/DC converter is connected with the direct current bus; a first end of the second isolation DC/DC converter is connected with the second end of the selection switch unit, and a second end of the second isolation DC/DC converter is connected with the direct current bus; the first controller is connected with the first isolation DC/DC converter and used for receiving a discharge instruction sent by the battery control unit and controlling the first isolation DC/DC converter to transmit energy from the first end to the second end according to the discharge instruction; the second controller is connected with the second isolation DC/DC converter and used for receiving a charging instruction sent by the battery control unit and controlling the second isolation DC/DC converter to transmit energy from the second end to the first end according to the charging instruction; the battery control unit receives the state signal of the battery pack power supply structure, outputs a discharging instruction to the first controller, outputs a charging instruction to the second controller according to the state signal, and outputs a switch control signal to the selection switch unit, so that the problems of low electric energy utilization rate and poor reliability in the process of balancing the voltage between the battery packs in the battery energy storage power supply system in the related art are solved. The charging command is sent to the second controller, the discharging command is sent to the first controller, and the switch control signal is sent to the selection switch unit when the voltage is unbalanced, so that the first isolation DC/DC converter is controlled to discharge the battery pack to be discharged, the second isolation DC/DC converter is controlled to charge the battery pack to be charged, and the high electric energy utilization rate and the high reliability are achieved when the voltage among the battery packs is equalized.

Optionally, in the battery energy storage power supply system provided in the embodiment of the present application, the selection switch unit 20 includes multiple sets of switch tubes, each set of switch tubes is connected to one battery pack correspondingly, and each set of switch tubes includes: a first end of the first switch tube is connected to the positive output end of the battery pack, and a second end of the first switch tube is connected to the positive voltage end of the first isolated DC/DC converter 30; a first end of the second switching tube is connected with the positive output end of the battery pack, and a second end of the second switching tube is connected with the positive voltage end of the first end of the second isolation DC/DC converter 40; a first end of the third switching tube is connected with the negative output end of the battery pack, and a second end of the third switching tube is connected with the negative voltage end of the first isolated DC/DC converter 30; and a first end of the fourth switching tube is connected with the negative output end of the battery pack, and a second end of the fourth switching tube is connected with the negative voltage end of the first end of the second isolation DC/DC converter 40.

Specifically, fig. 2 is a schematic structural diagram of a selection switch unit, a first isolation DC/DC converter and a second isolation DC/DC converter in a battery energy storage power supply system provided according to an embodiment of the present application, and as shown in fig. 2, a first switch tube may be Q11, Q21 \ 8230, qn1, a second switch tube may be Q12, Q22 \ 8230, qn2, a third switch tube may be Q13, Q23 \ 8230, qn3, and a fourth switch tube may be Q14, Q24 \ 8230, qn4. The positive voltage terminal (C12 +) of the first terminal of the first isolated DC/DC converter 30 is connected to the positive output terminal of the first battery pack 1 through a first switching tube Q11, and the negative voltage terminal of the first isolated DC/DC converter 30 is connected to the negative output terminal of the first battery pack 1 through a third switching tube Q13. The positive voltage terminal of the first isolated DC/DC converter 30 is connected to the positive output terminal of the second pack battery pack 2 through a first switching tube Q21, the negative voltage terminal of the first isolated DC/DC converter 30 is connected to the negative output terminal of the second pack battery pack 2 through a third switching tube Q23, until the positive voltage end of the first isolated DC/DC converter 30 is connected to the positive output end of the nth battery pack n through the first switching tube Qn1, the negative voltage end of the first isolated DC/DC converter 30 is connected to the negative output end of the nth battery pack n through the third switching tube Qn 3.

The positive voltage end of the first end of the second isolation DC/DC converter 40 is connected to the positive output end of the first battery pack 1 through a second switching tube Q12, and the negative voltage end of the first end of the second isolation DC/DC converter 40 is connected to the negative output end of the first battery pack 1 through a fourth switching tube Q14. The positive voltage end of the first end of the second isolation DC/DC converter 40 is connected to the positive output end of the second battery pack 2 through a second switching tube Q22, the negative voltage end of the first end of the second isolation DC/DC converter 40 is connected to the negative output end of the second battery pack 2 through a fourth switching tube Q24, until the positive voltage end of the first end of the second isolation DC/DC converter 40 is connected to the positive output end of the nth battery pack n through a second switching tube Qn2, and the negative voltage end of the first end of the second isolation DC/DC converter 40 is connected to the negative output end of the nth battery pack n through a fourth switching tube Qn4. Each battery pack is connected with the first isolation DC/DC converter 30 and the second isolation DC/DC converter 40 through a first switch tube, a second switch tube, a third switch tube and a fourth switch tube. Thereby, the first isolated DC/DC converter 30 discharges one battery pack or battery pack string through the selection switch unit 20, and the second isolated DC/DC converter 40522 charges one battery pack or battery pack string through the selection switch unit 20516.

It should be noted that, as shown in fig. 2, the first isolation DC/DC converter 30 and the second isolation DC/DC converter 40 may be full-bridge converters, and the first isolation DC/DC converter 30 includes a primary side bridge switching unit formed by a switch Q35, a switch Q36, a switch Q37, and a switch Q38, a secondary side bridge switching unit formed by a switch Q31, a switch Q32, a switch Q33, and a switch Q34, a transformer TX1, an inductor L1, a primary side capacitor C12, and a secondary side capacitor C11. The second isolated DC/DC converter 40522 includes a primary side bridge switching unit formed by a switch Q41, a switch Q42, a switch 43, and a switch Q44, a secondary side bridge switching unit formed by a switch Q45, a switch Q46, a switch Q47, and a switch Q48, a transformer TX2, an inductor L2, a primary side capacitor C21, and a secondary side capacitor C22. As shown in fig. 2, the switches on the secondary side can be both diodes. The secondary side in fig. 2 is exemplified by full-wave rectification, which may be any rectifying unit in practice. The auxiliary DC/DC converter 600 is a buck converter, and includes a switching tube S11, a switching tube S22, an inductor L11, an input capacitor C33, and an output and capacitor C33.

Each controller in the battery energy storage power supply system is powered by the auxiliary DC/DC converter 80, and optionally, in the battery energy storage power supply system provided in the embodiment of the present application, the battery energy storage power supply system further includes: the auxiliary DC/DC converter 80 has an input end connected to the DC bus, and an output end connected to the battery control unit 70, the battery pack management unit 103 of each battery pack, the first controller 50, the second controller 60, and the battery sampling chip 102, respectively, and the auxiliary DC/DC converter 80 is configured to convert the voltage of the DC bus into a supply voltage to supply power to the battery control unit 70, the battery pack management unit 103 of each battery pack, the first controller 50, the second controller 60, and the battery sampling chip 102.

Specifically, fig. 3 is a schematic structural diagram of a converter circuit in an alternative battery energy storage and power supply system according to an embodiment of the present application, as shown in fig. 3, an auxiliary DC/DC converter 80 is connected, an input end of the auxiliary DC/DC converter is connected to a DC bus, an output end of the auxiliary DC/DC converter is connected to a battery control unit 70, a battery pack management unit 103 of each battery pack, a first controller 50, a second controller 60, and a battery sampling chip 102, the auxiliary DC/DC converter 80 converts a DC bus voltage into a supply voltage of the controller, and the controller includes the above units connected to an output end of the auxiliary DC/DC converter 80. The supply voltage of the controller is generally 12V or less, so the auxiliary DC/DC converter 80 may select any non-isolated step-down DC/DC converter, fig. 4 is a schematic structural diagram of the auxiliary DC/DC converter in the battery energy storage power supply system provided by the embodiment of the present application, and as shown in fig. 4, the auxiliary DC/DC converter 80 may be a step-down converter. The auxiliary DC/DC converter 80 supplies power to each controller, and normal operation of the battery energy storage and power supply system is guaranteed.

It should be noted that the battery energy storage power supply system may also not be provided with the auxiliary DC/DC converter 80, and in this case, the BCU, the BMU, the first controller 50, and the second controller 60 may be powered by an isolation converter, such as a flyback converter, connected to the output end of the battery pack power supply structure 10.

The battery energy storage power supply system supplies power to the load 90 through the load power supply converter 100, and optionally, in the battery energy storage power supply system provided in the embodiment of the present application, the battery energy storage power supply system further includes: the input end of the load power supply converter 100 is connected to the output end of the battery pack power supply structure 10, and the output end of the load power supply converter 100 is connected to the load 90, and is used for converting the direct current provided by the battery pack power supply structure 10 into direct current or alternating current required by the load 90, wherein the load power supply converter 100 is a DC/DC converter or a DC/AC converter, and two ends of the battery pack series structure 10 form the output end of the battery pack power supply structure.

Specifically, the load power supply converter 100 may be a DC/DC converter or a DC/AC converter, an input end of the load power supply converter 100 is connected to the positive output terminal BAT + and the negative output terminal BAT of the battery pack power supply structure 10, an output end of the load power supply converter 100 is connected to the load 90, the load power supply converter 100 converts the direct current provided by the battery pack power supply structure 10 into a direct current or an alternating current to supply power to the load 90, when the load power supply converter 100 is the DC/DC converter, the direct current provided by the battery pack power supply structure 10 is converted into a direct current required by the load 90, and when the load power supply converter 100 is the DC/AC converter, the direct current provided by the battery pack power supply structure 10 is converted into an alternating current required by the load 90.

According to another embodiment of the present application, fig. 5 is a flowchart of a voltage equalization method for a battery pack provided according to an embodiment of the present application, and as shown in fig. 5, the method includes the following steps:

step S501, the battery control unit obtains a voltage signal of each battery pack in the battery pack power supply structure to obtain a plurality of voltage signals.

Specifically, a battery pack management unit (BMU) in each battery pack receives a voltage signal collected by a battery sampling chip (AFE), and a battery control unit obtains the voltage signal of each battery pack by receiving the voltage signal sent by the BMU in each battery pack.

In step S502, the battery control unit determines whether a voltage difference between any two battery packs is greater than or equal to a first preset value.

Specifically, after the battery control unit obtains the voltage signal of each battery pack, the voltage difference between the battery packs may be compared one by one, for example, the battery pack 1 is compared with the battery pack 2, the voltage difference is calculated, the battery pack 1 is compared with the battery pack 3, the voltage difference is calculated, 8230, the battery pack 1 is compared with the battery pack n, the voltage difference is calculated, 8230, and the battery pack n-1 is compared with the battery pack n, and the voltage difference is calculated. And judging whether the voltage difference value between each pair of battery packs is greater than or equal to a first preset value or not.

In step S503, in the case that the voltage difference between any two battery packs is greater than or equal to the first preset value, the battery control unit determines the battery pack to be charged and the battery pack to be discharged from the battery pack power supply structure.

Specifically, when the voltage difference between the battery packs are compared one by one, as long as the voltage difference between the battery packs is greater than or equal to a first preset value, it indicates that the voltages between the battery packs are unbalanced, the remaining battery packs are stopped to be continuously compared, the battery control unit outputs a discharge instruction to the first controller, outputs a charge instruction to the second controller, and outputs a switch control signal to the selection switch unit to control the voltage balance between the battery packs. Before sending corresponding signals, determining which battery packs are to-be-charged battery packs and which battery packs are to-be-discharged battery packs when performing voltage equalization.

Step S504, the battery control unit outputs a switch control signal to the selection switch unit, the selection switch unit is controlled to act through the switch control signal, the battery pack to be charged is communicated with the second isolation DC/DC converter, and the battery pack to be discharged is communicated with the first isolation DC/DC converter.

Specifically, the switch control signal may be a signal indicating that a preset switch tube is turned on or off, the preset switch tube also includes each group of switch tubes corresponding to the battery pack to be charged and the battery pack to be discharged, the battery pack to be discharged is communicated with the first isolated DC/DC converter by controlling the first switch tube and the third switch tube corresponding to the battery pack to be discharged to be closed, and the battery pack to be charged is communicated with the second isolated DC/DC converter by controlling the second switch tube and the fourth switch tube corresponding to the battery pack to be charged to be closed.

It should be noted that, during the discharging period or the charging period of the battery pack, the corresponding switch tube in the selection switch unit is always in the conducting state, so the switch tube of the selection switch unit does not need to be switched at high frequency, which greatly reduces the loss of the switch tube. The switching tube in the selection switch unit may be a MOSFET (metal-oxide semiconductor field effect transistor). It may be any device that can be controlled to be turned on or off, such as an IGBT (insulated bipolar transistor electronic component). The switch for connecting the positive output terminal of each battery pack in the selection switch unit to the positive voltage terminal of the first isolated DC/DC converter and to the positive voltage terminal of the first terminal of the second isolated DC/DC converter may be a discrete switch tube as shown in fig. 2, or may be an integrated switch unit, as long as it can select between the first isolated DC/DC converter and the second isolated DC/DC converter, and may not electrically connect either. The same applies to the switching tube connecting the negative output terminal of each battery pack with the negative voltage terminal of the first isolated DC/DC converter and with the negative voltage terminal of the first terminal of the second isolated DC/DC converter. The same applies to the switching tube connecting each battery pack to the second isolated DC/DC converter.

Step S505, the battery control unit outputs a discharge instruction to the first controller, and controls the first isolation DC/DC converter to operate through the discharge instruction, so as to control the battery pack to be discharged to transfer energy to the DC bus, where the first isolation DC/DC converter operates in a mode of transferring energy from the first end to the second end.

Specifically, the BCU outputs a discharging instruction to the first controller, the discharging instruction instructs the first isolation DC/DC converter to start working, and the first isolation DC/DC converter transfers the electric energy of the battery pack to be discharged to the direct current bus under the condition that the selection switch unit closes the switch tube corresponding to the battery pack to be discharged.

In step S506, the battery control unit outputs a charging instruction to the second controller, and controls the second isolation DC/DC converter to operate according to the charging instruction, so as to control the battery pack to be charged to receive the energy transmitted by the DC bus, where the second isolation DC/DC converter operates in a mode of transmitting the energy from the second terminal to the first terminal.

Specifically, the BCU outputs a charging instruction to the second controller, the charging instruction instructs the second isolation DC/DC converter to start working, and the second isolation DC/DC converter transfers the electric energy of the direct current bus to the battery pack to be charged under the condition that the selection switch unit closes the switch tube corresponding to the battery pack to be charged.

According to the voltage balancing method for the battery pack, the voltage signal of each battery pack in the battery pack power supply structure is obtained through the battery control unit, and a plurality of voltage signals are obtained; the battery control unit judges whether a voltage difference value between any two battery packs is larger than or equal to a first preset value or not; under the condition that the voltage difference value between any two battery packs is larger than or equal to a first preset value, the battery control unit determines a battery pack to be charged and a battery pack to be discharged from a battery pack power supply structure; the battery control unit outputs a switch control signal to the selection switch unit, controls the selection switch unit to act through the switch control signal, and communicates the battery pack to be charged with the second isolation DC/DC converter and communicates the battery pack to be discharged with the first isolation DC/DC converter; the battery control unit outputs a discharge instruction to the first controller, and controls the first isolation DC/DC converter to work through the discharge instruction so as to control the battery pack to be discharged to transfer energy to the direct current bus, wherein the first isolation DC/DC converter has a working mode of transferring energy from the first end to the second end; the battery control unit outputs a charging instruction to the second controller, and controls the second isolation DC/DC converter to work through the charging instruction so as to control the battery pack to be charged to receive the energy transmitted by the direct current bus, wherein the second isolation DC/DC converter works in a mode of transmitting the energy from the second end to the first end, and the problems of low electric energy utilization rate and poor reliability in the process of balancing the voltage between the battery packs in the battery energy storage and power supply system in the related art are solved. The charging command is sent to the second controller, the discharging command is sent to the first controller, and the switch control signal is sent to the selection switch unit when the voltage is unbalanced, so that the first isolation DC/DC converter is controlled to discharge the battery pack to be discharged, the second isolation DC/DC converter is controlled to charge the battery pack to be charged, and the high electric energy utilization rate and the high reliability are achieved when the voltage among the battery packs is equalized.

Optionally, in the voltage balancing method for a battery pack provided in this embodiment of the present application, the switch unit includes multiple sets of switch tubes, each set of switch tube includes a first switch tube, a second switch tube, a third switch tube, and a fourth switch tube, and the selecting switch unit is controlled by the switch control signal to operate, so as to communicate the battery pack to be charged with the second isolated DC/DC converter, and communicate the battery pack to be discharged with the first isolated DC/DC converter includes: a second switching tube between the positive output end of each battery pack to be charged and the positive voltage end of the first end of the second isolation DC/DC converter, a fourth switching tube between the negative output end of each battery pack to be charged and the negative voltage end of the first end of the second isolation DC/DC converter are closed through a switch control signal, and a first switching tube between the positive output end of each battery pack to be charged and the positive voltage end of the first isolation DC/DC converter, and a third switching tube between the negative output end of each battery pack to be charged and the negative voltage end of the first isolation DC/DC converter are opened; and a first switching tube between the positive output end of each battery pack to be discharged and the positive voltage end of the first isolation DC/DC converter, a third switching tube between the negative output end of each battery pack to be discharged and the negative voltage end of the first isolation DC/DC converter are closed through a switching control signal, and a second switching tube between the positive output end of each battery pack to be discharged and the positive voltage end of the first end of the second isolation DC/DC converter, and a fourth switching tube between the negative output end of each battery pack to be discharged and the negative voltage end of the first end of the second isolation DC/DC converter are opened.

For example, as shown in fig. 2, when the state characterizing signal S1 indicates that the second battery pack 2 is a battery pack to be discharged, the selection switch control signal output by the BCU closes the first switch tube Q21 and the third switch tube Q23 corresponding to the battery pack 2, that is, the selection switch control signal output by the BCU makes the first end of the first isolation DC/DC converter communicate with both ends of the second battery pack 2, and at the same time, the first controller controls the first isolation DC/DC converter to operate through the discharge instruction output by the BCU, so as to discharge the energy of the second battery pack 2 to the DC bus through the selection switch unit and the first isolation DC/DC converter.

Further, if the state characterizing signal S1 indicates that the third battery pack 3 (not shown) to the fifth battery pack 5 (not shown) are battery packs to be charged, the selection switch control signal output by the BCU makes the second switch tube Q32 (not shown) and the fourth switch tube Q54 (not shown) closed, that is, the selection switch control signal output by the BCU makes the first end of the second isolation DC/DC converter communicate with the positive output end of the third battery pack 3 and the negative output end of the fifth battery pack 5, and the charging instruction output by the BCU makes the second controller control the second isolation DC/DC converter to work, so that the third battery pack 3 to the fifth battery pack 5 are charged through the selection switch unit and the second isolation DC/DC converter at the same time. That is, by controlling the on/off of the switch tube in the selection switch unit, the first isolation DC/DC converter can be made to discharge the battery pack string formed by any battery pack or a plurality of battery packs, and the second isolation DC/DC converter can be made to charge the battery pack string formed by any battery pack or a plurality of battery packs.

Optionally, in the voltage balancing method for a battery pack provided in the embodiment of the present application, the determining, by the battery control unit, the battery pack to be charged from the battery pack power supply structure includes: calculating a difference value between the voltage signal of each battery pack and a second preset value to obtain a plurality of difference values, and obtaining a positive number difference value from the plurality of difference values to obtain a plurality of positive number difference values, wherein the second preset value is at least one of the following values: the mean value of the plurality of voltage signals and the median of the plurality of voltage signals; determining a maximum positive difference value from the positive difference values, and judging whether a battery pack corresponding to the maximum positive difference value has a first battery pack string or not, wherein the first battery pack string is composed of a plurality of battery packs adjacent to the battery pack corresponding to the maximum positive difference value, and the difference between a voltage signal of the battery pack in the first battery pack string and a second preset value is a positive number; under the condition that the battery pack corresponding to the maximum positive number difference value has a first battery pack string, determining the battery pack in the first battery pack string and the battery pack corresponding to the maximum positive number difference value as battery packs to be charged; and under the condition that the battery pack corresponding to the maximum positive number difference value does not have the first battery pack string, determining the battery pack corresponding to the maximum positive number difference value as a battery pack to be charged.

Specifically, in order to ensure voltage equalization among the battery packs, the second preset value may be an average value, a median, and the like of voltage signals of all the battery packs, and a difference between the voltage signal of each battery pack and the second preset value is calculated, where the difference may be a positive difference, a negative difference, or a difference of 0, where a difference of 0 means that the battery pack does not need to be discharged or charged, a positive difference indicates that the battery pack needs to be discharged, and a negative difference indicates that the battery pack needs to be charged. Because the battery packs are connected in series, the non-adjacent battery packs cannot be charged or discharged simultaneously. Therefore, the minimum negative number difference value is determined from all the negative number difference values, that is, the battery pack most needing to be charged is found, if the battery pack adjacent to the battery pack most needing to be charged also belongs to the battery pack of which the difference value with the second preset value is the negative number difference value, the adjacent battery pack string can be charged simultaneously, each battery pack in the battery pack string is determined as the battery pack to be charged, and if the battery pack adjacent to the battery pack most needing to be charged all belongs to the battery pack of which the difference value with the second preset value is the positive number difference value, the adjacent battery packs cannot be charged simultaneously, so that only the battery pack most needing to be charged is determined as the battery pack to be charged. The charging mode has the effect that the voltage balance among the battery packs cannot be achieved at one time, and the battery packs to be charged can be determined for multiple times and charged for multiple times until the voltage balance among the battery packs is achieved.

Optionally, in the voltage balancing method for a battery pack provided in the embodiment of the present application, the determining, by the battery control unit, the battery pack to be discharged from the battery pack power supply structure includes: determining a minimum negative difference value from the negative difference values, and judging whether a battery pack corresponding to the minimum negative difference value has a second battery pack string or not, wherein the second battery pack string is composed of a plurality of battery packs adjacent to the battery pack corresponding to the minimum negative difference value, and the difference value between the voltage signal of the battery pack in the second battery pack string and a second preset value is a negative number; under the condition that the battery pack corresponding to the minimum negative number difference value has a second battery pack string, determining the battery pack in the second battery pack string and the battery pack corresponding to the minimum negative number difference value as battery packs to be discharged; and under the condition that the battery pack corresponding to the minimum negative number difference value does not have the second battery pack string, determining the battery pack corresponding to the minimum negative number difference value as the battery pack to be discharged.

Specifically, because the first isolation DC/DC converter and the second isolation DC/DC converter are independent from each other, the battery pack to be discharged may also be discharged while the battery pack to be charged is charged, the maximum positive difference value is determined from all the positive difference values, that is, the battery pack most needing to be discharged is found, if the battery pack adjacent to the battery pack most needing to be discharged also belongs to the battery pack whose difference value from the second preset value is the positive difference value, the adjacent battery pack string may be simultaneously discharged, each battery pack in the battery pack string is determined as the battery pack to be discharged, and if the battery pack adjacent to the battery pack most needing to be discharged all belongs to the battery pack whose difference value from the second preset value is the negative difference value, the adjacent battery packs cannot be simultaneously discharged, so only the battery pack most needing to be discharged is determined as the battery pack to be discharged. The discharging mode has the effect that the voltage balance among the battery packs cannot be achieved at one time, and the battery packs to be discharged can be determined for multiple times to be discharged for multiple times until the voltage balance among the battery packs is achieved.

Optionally, in the voltage balancing method for a battery pack provided in the embodiment of the present application, after the battery control unit determines whether a voltage difference between any two battery packs is greater than or equal to a first preset value, the method further includes: and under the condition that the voltage difference value is smaller than a first preset value, the battery control unit sends a preset discharge instruction to the first controller, wherein the preset discharge instruction is used for controlling the battery pack to discharge to the direct-current bus so as to supply power to the battery control unit, the first controller, the second controller, the battery pack management unit of each battery pack and the battery sampling chip through an auxiliary DC/DC converter connected with the direct-current bus.

Specifically, when all the battery packs are compared and the calculated voltage difference values are all smaller than the first preset value, it is indicated that the voltages between the battery packs are in a balanced state, and at this time, the battery packs do not need to be discharged or charged to ensure the voltage balance between the battery packs. However, since each control unit of the battery energy storage and power supply system needs energy to operate, the battery control unit sends a discharge instruction to the first controller, and the discharge instruction is used to control the battery pack to discharge to the DC bus, so that the auxiliary DC/DC converter converts the voltage in the DC bus into the voltage of the controller, and further supplies power to the battery control unit, the first controller, the second controller, the first isolation DC/DC converter, the second isolation DC/DC converter, the battery pack management unit of each battery pack, and the AFE. The battery pack is controlled to discharge to the direct current bus when the voltage difference value is smaller than the first preset value, power can be supplied to the auxiliary DC/DC converter, accordingly, energy recycling is achieved, and efficiency of the battery energy storage power supply system is improved.

It should be noted that, for the battery energy storage power supply system in the embodiment of the present application, the DC bus is supplied with power by n DC/DC converters connected to the electric core series structure, and as long as any battery pack in the battery pack power supply structure normally works and the DC bus has voltage, the auxiliary DC/DC converter may supply power to the controller in the battery energy storage power supply system, so that the battery energy storage power supply system can normally work.

When the battery energy storage power supply system has faults, the positions and reasons of the faults can be detected through the auxiliary DC/DC converter, great convenience is brought to follow-up fault removal, and the reliability of the whole battery energy storage power supply system is improved. When a battery pack has a fault, the whole battery pack power supply structure cannot supply power to the battery energy storage power supply system, at the moment, the electric energy on the direct current bus is supplied to the AFE of each battery pack through the auxiliary DC/DC converter, and the AFE can judge whether the battery pack has the fault through whether the voltage signal of the battery pack is collected or not, so that the fault position is judged.

It should be noted that, in all existing battery energy storage power supply systems, the power supply of the controller is implemented by converters connected to BAT + and BAT-of the battery pack power supply structure, the voltage of the battery pack power supply structure is usually between 40V and 500V, and the converters need to convert the high voltage of 40V to 500V into 12V, and the input voltage is high, and the voltage range is large, so that an isolation converter, such as a flyback converter, is required. The auxiliary DC/DC converter only needs a non-isolated buck converter, so that the cost and the design difficulty are greatly reduced. In the related art, because the input of the converter is the output end of the battery pack power supply structure, once any one of the battery cell series structures fails, the converter cannot supply power to the controller due to no input, so that the controller cannot detect the position and the reason of the failure, the difficulty in troubleshooting is high, and the system reliability is low. Therefore, the battery energy storage power supply system provided by the application has the advantages of high reliability, small volume and low cost.

It should be noted that the steps illustrated in the flowcharts of the figures may be performed in a computer system such as a set of computer-executable instructions and that, although a logical order is illustrated in the flowcharts, in some cases, the steps illustrated or described may be performed in an order different than presented herein.

The embodiment of the present application further provides a voltage balancing device for a battery pack, and it should be noted that the voltage balancing device for a battery pack according to the embodiment of the present application can be used to execute the voltage balancing method for a battery pack provided in the embodiment of the present application. The following describes a voltage equalization device of a battery pack provided in an embodiment of the present application.

Fig. 6 is a schematic diagram of a voltage equalization apparatus of a battery pack according to an embodiment of the present application. As shown in fig. 6, the apparatus includes:

the acquiring unit 601 is used for acquiring a voltage signal of each battery pack in the battery pack power supply structure through the battery control unit to obtain a plurality of voltage signals;

a determining unit 602, configured to determine whether a voltage difference between any two battery packs is greater than or equal to a first preset value through a battery control unit;

a determining unit 603, configured to determine, when there is a voltage difference between any two battery packs that is greater than or equal to a first preset value, a battery control unit determines a battery pack to be charged and a battery pack to be discharged from a battery pack power supply structure;

the first control unit 604 is configured to output a switch control signal to the selection switch unit through the battery control unit, control the selection switch unit to operate through the switch control signal, communicate the battery pack to be charged with the second isolation DC/DC converter, and communicate the battery pack to be discharged with the first isolation DC/DC converter;

the second control unit 605 is configured to output a discharge instruction to the first controller through the battery control unit, and control the first isolation DC/DC converter to operate through the discharge instruction, so as to control the battery pack to be discharged to transfer energy to the DC bus, where an operating mode of the first isolation DC/DC converter is to transfer energy from the first end to the second end;

and a third control unit 606, configured to output a charging instruction to the second controller through the battery control unit, and control the second isolation DC/DC converter to operate through the charging instruction, so as to control the battery pack to be charged to receive the energy transmitted by the direct current bus, where an operating mode of the second isolation DC/DC converter is to transmit the energy from the second end to the first end.

According to the voltage balancing device for the battery pack, provided by the embodiment of the application, the voltage signal of each battery pack in the power supply structure of the battery pack is acquired through the battery control unit by the acquisition unit 601, so that a plurality of voltage signals are obtained; the judging unit 602 judges whether a voltage difference value between any two battery packs is greater than or equal to a first preset value through the battery control unit; a determining unit 603, configured to determine, from the battery pack power supply structure, a battery pack to be charged and a battery pack to be discharged, when there is a voltage difference between any two battery packs greater than or equal to a first preset value; the first control unit 604 outputs a switch control signal to the selection switch unit through the battery control unit, controls the selection switch unit to act through the switch control signal, and communicates the battery pack to be charged with the second isolation DC/DC converter and communicates the battery pack to be discharged with the first isolation DC/DC converter; the second control unit 605 outputs a discharge instruction to the first controller through the battery control unit, and controls the first isolation DC/DC converter to work through the discharge instruction so as to control the battery pack to be discharged to transfer energy to the DC bus, wherein the first isolation DC/DC converter has a working mode of transferring energy from the first end to the second end; the third control unit 606 outputs a charging instruction to the second controller through the battery control unit, and controls the second isolation DC/DC converter to operate through the charging instruction, so as to control the battery pack to be charged to receive the energy transmitted by the DC bus, wherein the second isolation DC/DC converter operates in a mode of transmitting the energy from the second end to the first end, so as to solve the problems of low electric energy utilization rate and poor reliability in balancing the voltage between the battery packs in the battery energy storage and power supply system in the related art.

Optionally, in the voltage equalizing device for a battery pack provided in the embodiment of the present application, the switch unit includes multiple sets of switch tubes, each set of switch tubes includes a first switch tube, a second switch tube, a third switch tube, and a fourth switch tube, and the first control unit 604 includes: the first closing module is used for closing a second switching tube between the positive output end of each battery pack to be charged and the positive voltage end of the first end of the second isolation DC/DC converter and a fourth switching tube between the negative output end of each battery pack to be charged and the negative voltage end of the first end of the second isolation DC/DC converter through a switching control signal and opening a first switching tube between the positive output end of each battery pack to be charged and the positive voltage end of the first isolation DC/DC converter and a third switching tube between the negative output end of each battery pack to be charged and the negative voltage end of the first isolation DC/DC converter; and the second closing module is used for closing a first switching tube between the positive output end of each battery pack to be discharged and the positive voltage end of the first isolation DC/DC converter, a third switching tube between the negative output end of each battery pack to be discharged and the negative voltage end of the first isolation DC/DC converter through a switching control signal, and opening a second switching tube between the positive output end of each battery pack to be discharged and the positive voltage end of the first end of the second isolation DC/DC converter and a fourth switching tube between the negative output end of each battery pack to be discharged and the negative voltage end of the first end of the second isolation DC/DC converter.

Optionally, in the voltage balancing apparatus for a battery pack provided in the embodiment of the present application, the determining unit 603 includes: the calculating module is used for calculating a difference value between the voltage signal of each battery pack and a second preset value to obtain a plurality of difference values, and acquiring a positive number difference value from the plurality of difference values to obtain a plurality of positive number difference values, wherein the second preset value is at least one of the following values: the mean value of the plurality of voltage signals and the median of the plurality of voltage signals; the first determining module is used for determining the maximum positive number difference value from the positive number difference values and judging whether a first battery pack string exists in a battery pack corresponding to the maximum positive number difference value, wherein the first battery pack string is formed by a plurality of battery packs adjacent to the battery pack corresponding to the maximum positive number difference value, and the difference value between a voltage signal of the battery pack in the first battery pack string and a second preset value is a positive number; the second determining module is used for determining the battery pack in the first battery pack string and the battery pack corresponding to the maximum positive number difference value as the battery pack to be charged under the condition that the battery pack corresponding to the maximum positive number difference value has the first battery pack string; and the third determining module is used for determining the battery pack corresponding to the maximum positive number difference value as the battery pack to be charged under the condition that the battery pack corresponding to the maximum positive number difference value does not have the first battery pack string.

Optionally, in the voltage equalizing apparatus for a battery pack provided in the embodiment of the present application, the determining unit 603 includes: the fourth determining module is used for determining a minimum negative difference value from the negative difference values and judging whether a second battery pack string exists in the battery pack corresponding to the minimum negative difference value, wherein the second battery pack string is formed by a plurality of battery packs adjacent to the battery pack corresponding to the minimum negative difference value, and the difference value between the voltage signal of the battery pack in the second battery pack string and a second preset value is a negative number; the fifth determining module is used for determining the battery pack in the second battery pack string and the battery pack corresponding to the minimum negative number difference value as the battery pack to be discharged under the condition that the battery pack corresponding to the minimum negative number difference value has the second battery pack string; and the sixth determining module is used for determining the battery pack corresponding to the minimum negative number difference value as the battery pack to be discharged under the condition that the battery pack corresponding to the minimum negative number difference value does not have the second battery pack string.

Optionally, in the voltage equalizing device for a battery pack provided in an embodiment of the present application, the device includes: and the sending unit is used for sending a preset discharging instruction to the first controller by the battery control unit under the condition that the voltage difference value is smaller than a first preset value, wherein the preset discharging instruction is used for controlling the battery pack to discharge to the direct-current bus so as to supply power to the battery control unit, the first controller, the second controller, the battery pack management unit of each battery pack and the battery sampling chip through an auxiliary DC/DC converter connected with the direct-current bus.

The voltage balancing device of the battery pack comprises a processor and a memory, wherein the acquiring unit 601, the judging unit 602, the determining unit 603, the first control unit 604, the second control unit 605, the third control unit 606 and the like are stored in the memory as program units, and the processor executes the program units stored in the memory to realize corresponding functions.

The processor comprises a kernel, and the kernel calls the corresponding program unit from the memory. The core can be set to one or more than one, and the voltage between the battery packs is equalized by adjusting the parameters of the core.

The memory may include volatile memory in a computer readable medium, random Access Memory (RAM) and/or non-volatile memory, such as Read Only Memory (ROM) or flash memory (flash RAM), including at least one memory chip.

An embodiment of the present invention provides a computer-readable storage medium on which a program is stored, the program implementing a voltage equalization method of a battery pack when executed by a processor.

The embodiment of the invention provides a processor, which is used for running a program, wherein a voltage balancing method of a battery pack is executed when the program runs.

The embodiment of the invention provides electronic equipment, which comprises a processor, a memory and a program which is stored on the memory and can run on the processor, wherein the processor executes the program and realizes the following steps: a voltage equalization method for a battery pack. The device herein may be a server, a PC, a PAD, a mobile phone, etc.

The present application further provides a computer program product adapted to perform a program for initializing the following method steps when executed on a data processing device: a voltage equalization method for a battery pack.

As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

In a typical configuration, a computing device includes one or more processors (CPUs), input/output interfaces, network interfaces, and memory.

The memory may include forms of volatile memory in a computer readable medium, random Access Memory (RAM) and/or non-volatile memory, such as Read Only Memory (ROM) or flash memory (flash RAM). The memory is an example of a computer-readable medium.

Computer-readable media, including both permanent and non-permanent, removable and non-removable media, may implement the information storage by any method or technology. The information may be computer readable instructions, data structures, modules of a program, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static Random Access Memory (SRAM), dynamic Random Access Memory (DRAM), other types of Random Access Memory (RAM), read Only Memory (ROM), electrically Erasable Programmable Read Only Memory (EEPROM), flash memory or other memory technology, compact disc read only memory (CD-ROM), digital Versatile Discs (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information that can be accessed by a computing device. As defined herein, a computer readable medium does not include a transitory computer readable medium such as a modulated data signal and a carrier wave.

It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrases "comprising a," "8230," "8230," or "comprising" does not exclude the presence of additional identical elements in the process, method, article, or apparatus comprising the element.

As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and so forth) having computer-usable program code embodied therein.

The above are merely examples of the present application and are not intended to limit the present application. Various modifications and changes may occur to those skilled in the art to which the present application pertains. Any modification, equivalent replacement, improvement or the like made within the spirit and principle of the present application shall be included in the scope of the claims of the present application.

Claims

1. A battery energy storage power supply system, comprising:

the battery pack power supply structure comprises a plurality of battery packs, wherein the battery packs are sequentially connected in series to form a battery pack series structure;

a first end of the selective switch unit is connected with two ends of each battery pack, and a second end of the selective switch unit is respectively connected with the first isolation DC/DC converter and the second isolation DC/DC converter and used for receiving a switch control signal sent by the battery control unit and controlling different battery packs to be communicated with the first isolation DC/DC converter and the second isolation DC/DC converter according to the switch control signal;

the first end of the first isolation DC/DC converter is connected with the second end of the selection switch unit, and the second end of the first isolation DC/DC converter is connected with the direct current bus;

the first end of the second isolation DC/DC converter is connected with the second end of the selection switch unit, and the second end of the second isolation DC/DC converter is connected with the direct current bus;

the first controller is connected with the first isolation DC/DC converter and used for receiving a discharge instruction sent by a battery control unit and controlling the first isolation DC/DC converter to transmit energy from the first end to the second end according to the discharge instruction;

the second controller is connected with the second isolation DC/DC converter and used for receiving a charging instruction sent by the battery control unit and controlling the second isolation DC/DC converter to transfer energy from the second end to the first end according to the charging instruction;

the battery control unit is used for receiving a state signal of the battery pack power supply structure, outputting the discharge instruction to the first controller, outputting the charging instruction to the second controller according to the state signal and outputting the switch control signal to the selection switch unit;

the auxiliary DC/DC converter is used for converting the voltage of the direct-current bus into a power supply voltage and supplying power to the battery control unit, the first controller and the second controller;

wherein, the selection switch unit includes the multiunit switch tube, and every switch tube of group is connected with a battery package, and every switch tube of group includes:

a first switch tube, a first end of which is connected with a positive output end of a battery pack, and a second end of which is connected with a positive voltage end of a first end of the first isolation DC/DC converter;

a second switching tube, a first end of the second switching tube being connected to the positive output end of the battery pack, and a second end of the second switching tube being connected to the positive voltage end of the first end of the second isolated DC/DC converter;

a first end of the third switching tube is connected with a negative output end of a battery pack, and a second end of the third switching tube is connected with a negative voltage end of the first isolation DC/DC converter;

and the first end of the fourth switching tube is connected with the negative output end of the battery pack, and the second end of the fourth switching tube is connected with the negative voltage end of the first end of the second isolation DC/DC converter.

2. The battery energy storage and power supply system of claim 1, wherein each battery pack comprises:

the battery cell series structure comprises a plurality of battery cells connected in series, and two ends of the battery cell series structure form two ends of the battery pack;

the battery sampling chips are connected in parallel at two ends of the battery cell series structure and used for acquiring state signals of the battery cell series structure and sending the state signals of the battery cell series structure to the battery pack management unit;

and the battery pack management unit is used for receiving the state signal of the battery core series structure sent by the battery sampling chip and sending the state signal of the battery core series structure to the battery control unit.

3. The battery energy storage power supply system of claim 2,

the output end of the auxiliary DC/DC converter is respectively connected with the battery control unit, the battery pack management unit of each battery pack and the battery sampling chip, and the auxiliary DC/DC converter is used for converting the voltage of the direct-current bus into power supply voltage to supply power for the battery control unit, the battery pack management unit of each battery pack and the battery sampling chip.

4. The battery energy storage power supply system of claim 1, further comprising:

the input end of the load power supply converter is connected with the output end of the battery pack power supply structure, the output end of the load power supply converter is connected with a load, and the load power supply converter is used for converting direct current provided by the battery pack power supply structure into direct current or alternating current required by the load, wherein the load power supply converter is a DC/DC converter or a DC/AC converter, and the two ends of the battery pack series structure form the output end of the battery pack power supply structure.

5. A voltage equalization method of a battery pack is applied to the battery energy storage and power supply system of any one of claims 1 to 4, and is characterized by comprising the following steps:

the battery control unit acquires a voltage signal of each battery pack in a battery pack power supply structure to obtain a plurality of voltage signals;

the battery control unit judges whether a voltage difference value between any two battery packs is larger than or equal to a first preset value or not;

under the condition that the voltage difference value between any two battery packs is larger than or equal to the first preset value, the battery control unit determines a battery pack to be charged and a battery pack to be discharged from the battery pack power supply structure;

the battery control unit outputs a switch control signal to the selection switch unit, controls the selection switch unit to act through the switch control signal, and communicates the battery pack to be charged with the second isolation DC/DC converter and communicates the battery pack to be discharged with the first isolation DC/DC converter;

the battery control unit outputs a discharge instruction to a first controller, and controls the first isolation DC/DC converter to work through the discharge instruction so as to control the battery pack to be discharged to transfer energy to a direct current bus, wherein the first isolation DC/DC converter has a working mode of transferring the energy from a first end to a second end;

the battery control unit outputs a charging instruction to a second controller, and controls the second isolation DC/DC converter to work through the charging instruction so as to control the battery pack to be charged to receive energy transmitted by the direct current bus, wherein the second isolation DC/DC converter works in a mode of transmitting the energy from a second end to a first end;

wherein the battery control unit determining the battery pack to be charged from the battery pack power supply structure includes:

calculating a difference value between the voltage signal of each battery pack and a second preset value to obtain a plurality of difference values, and obtaining a positive number difference value from the plurality of difference values to obtain a plurality of positive number difference values, wherein the second preset value is at least one of the following values: a mean value of the plurality of voltage signals, a median of the plurality of voltage signals;

determining a maximum positive difference value from the plurality of positive difference values, and judging whether a battery packet corresponding to the maximum positive difference value has a first battery packet string, wherein the first battery packet string is formed by a plurality of battery packets adjacent to the battery packet corresponding to the maximum positive difference value, and the difference between a voltage signal of the battery packet in the first battery packet string and the second preset value is a positive number;

under the condition that the battery pack corresponding to the maximum positive number difference value exists in the first battery pack string, determining the battery pack in the first battery pack string and the battery pack corresponding to the maximum positive number difference value as the battery pack to be charged;

under the condition that the battery pack corresponding to the maximum positive number difference value does not have the first battery pack string, determining the battery pack corresponding to the maximum positive number difference value as the battery pack to be charged;

wherein the battery control unit determines the battery pack to be discharged from the battery pack power supply structure, and comprises:

calculating a difference value between the voltage signal of each battery pack and a second preset value to obtain a plurality of difference values, and obtaining a negative difference value from the plurality of difference values to obtain a plurality of negative difference values, wherein the second preset value is at least one of the following values: a mean value of the plurality of voltage signals, a median of the plurality of voltage signals;

determining a minimum negative number difference value from the negative number difference values, and judging whether a second battery pack string exists in a battery pack corresponding to the minimum negative number difference value, wherein the second battery pack string is formed by a plurality of battery packs adjacent to the battery pack corresponding to the minimum negative number difference value, and the difference value between a voltage signal of the battery pack in the second battery pack string and the second preset value is a negative number;

under the condition that the battery pack corresponding to the minimum negative number difference value exists in the second battery pack string, determining the battery pack in the second battery pack string and the battery pack corresponding to the minimum negative number difference value as the battery pack to be discharged;

and under the condition that the battery pack corresponding to the minimum negative number difference value does not have the second battery pack string, determining the battery pack corresponding to the minimum negative number difference value as the battery pack to be discharged.

6. The method of claim 5, wherein the switch unit comprises a plurality of groups of switch tubes, each group of switch tubes comprises a first switch tube, a second switch tube, a third switch tube and a fourth switch tube, and the step of controlling the action of the selection switch unit through the switch control signal to communicate the battery pack to be charged with the second isolated DC/DC converter and communicate the battery pack to be discharged with the first isolated DC/DC converter comprises the steps of:

closing a second switching tube between the positive output end of each battery pack to be charged and the positive voltage end of the first end of the second isolated DC/DC converter, a fourth switching tube between the negative output end of each battery pack to be charged and the negative voltage end of the first end of the second isolated DC/DC converter, and opening a first switching tube between the positive output end of each battery pack to be charged and the positive voltage end of the first isolated DC/DC converter, and a third switching tube between the negative output end of each battery pack to be charged and the negative voltage end of the first isolated DC/DC converter by the switching control signal;

and closing a first switching tube between the positive output end of each battery pack to be discharged and the positive voltage end of the first isolation DC/DC converter, a third switching tube between the negative output end of each battery pack to be discharged and the negative voltage end of the first isolation DC/DC converter through the switch control signal, and opening a second switching tube between the positive output end of each battery pack to be discharged and the positive voltage end of the first end of the second isolation DC/DC converter and a fourth switching tube between the negative output end of each battery pack to be discharged and the negative voltage end of the first end of the second isolation DC/DC converter.

7. The method of claim 5, wherein after the battery control unit determines whether the voltage difference between any two battery packs is greater than or equal to a first preset value, the method further comprises:

and under the condition that the voltage difference value is smaller than the first preset value, the battery control unit sends a preset discharge instruction to the first controller, wherein the preset discharge instruction is used for controlling a battery pack to discharge to the direct-current bus so as to supply power to the battery control unit, the first controller, the second controller, the battery pack management unit of each battery pack and a battery sampling chip through an auxiliary DC/DC converter connected with the direct-current bus.

8. A voltage equalizing device of a battery pack, which is applied to the battery energy storage and power supply system of any one of claims 1 to 4, and is characterized by comprising:

the battery pack power supply device comprises an acquisition unit, a battery control unit and a control unit, wherein the acquisition unit is used for acquiring a voltage signal of each battery pack in a battery pack power supply structure through the battery control unit to obtain a plurality of voltage signals;

the judging unit is used for judging whether a voltage difference value between any two battery packs is larger than or equal to a first preset value or not through the battery control unit;

the battery control unit is used for determining a battery pack to be charged and a battery pack to be discharged from the battery pack power supply structure under the condition that the voltage difference value between any two battery packs is greater than or equal to the first preset value;

the first control unit is used for outputting a switch control signal to the selection switch unit through the battery control unit, controlling the selection switch unit to act through the switch control signal, communicating the battery pack to be charged with the second isolation DC/DC converter and communicating the battery pack to be discharged with the first isolation DC/DC converter;

the second control unit is used for outputting a discharging instruction to the first controller through the battery control unit, and controlling the first isolation DC/DC converter to work through the discharging instruction so as to control the battery pack to be discharged to transfer energy to the direct current bus, wherein the first isolation DC/DC converter has a working mode of transferring the energy from the first end to the second end;

the third control unit is used for outputting a charging instruction to the second controller through the battery control unit, and controlling the second isolation DC/DC converter to work through the charging instruction so as to control the battery pack to be charged to receive energy transmitted by the direct current bus, wherein the second isolation DC/DC converter has a working mode of transmitting the energy from the second end to the first end;

wherein the determination unit includes:

the first calculation module is configured to calculate a difference between the voltage signal of each battery pack and a second preset value to obtain a plurality of differences, and obtain a positive difference from the plurality of differences to obtain a plurality of positive differences, where the second preset value is at least one of: a mean value of the plurality of voltage signals, a median of the plurality of voltage signals;

the first determining module is configured to determine a maximum positive difference value from the multiple positive difference values, and determine whether a first battery packet string exists in a battery packet corresponding to the maximum positive difference value, where the first battery packet string is formed by multiple battery packets adjacent to the battery packet corresponding to the maximum positive difference value, and a difference between a voltage signal of the battery packet in the first battery packet string and the second preset value is a positive number;

the second determining module is configured to determine, when the battery packet corresponding to the maximum positive difference value exists in the first battery packet string, a battery packet in the first battery packet string and a battery packet corresponding to the maximum positive difference value as the battery packet to be charged;

a third determining module, configured to determine, when the battery pack corresponding to the maximum positive number difference does not have the first battery pack string, the battery pack corresponding to the maximum positive number difference as the battery pack to be charged;

wherein the determining unit further includes:

the second calculation module is configured to calculate a difference between the voltage signal of each battery pack and a second preset value to obtain a plurality of differences, and obtain a negative difference from the plurality of differences to obtain a plurality of negative differences, where the second preset value is at least one of: a mean value of the plurality of voltage signals, a median of the plurality of voltage signals;

a fourth determining module, configured to determine a minimum negative difference value from the multiple negative difference values, and determine whether a second battery pack string exists in a battery pack corresponding to the minimum negative difference value, where the second battery pack string is formed by multiple battery packs adjacent to the battery pack corresponding to the minimum negative difference value, and a difference between a voltage signal of the battery pack in the second battery pack string and the second preset value is a negative number;

a fifth determining module, configured to determine, when the battery pack corresponding to the minimum negative number difference exists in the second battery pack string, a battery pack in the second battery pack string and a battery pack corresponding to the minimum negative number difference are the battery pack to be discharged;

and the sixth determining module is used for determining the battery pack corresponding to the minimum negative number difference value as the battery pack to be discharged under the condition that the battery pack corresponding to the minimum negative number difference value does not have the second battery pack string.

9. A processor, characterized in that the processor is configured to run a program, wherein the program is configured to execute the voltage equalization method of the battery pack according to any one of claims 5 to 7 when running.

10. An electronic device, comprising one or more processors and memory for storing one or more programs, wherein the one or more programs, when executed by the one or more processors, cause the one or more processors to implement the method of voltage balancing for battery packs of any of claims 5 to 7.