Active balancing circuit and energy storage device

Abstract

The present application discloses an active balancing circuit and an energy storage device, relating to the technical field of battery balancing. The circuit includes an energy providing module, an AC bus, an isolation conversion module, and a plurality of balancing systems; each balancing system is respectively connected to an isolation conversion module and a battery pack; the energy providing module is connected to a battery management system and is connected to each isolation conversion module through the AC bus; each balancing system includes a balancing switch unit; the balancing switch unit is respectively connected to the corresponding isolation conversion module and the corresponding battery pack; the balancing switch unit is used to conduct or disconnect the loop formed by the energy providing module, the AC bus, the isolation conversion module corresponding to the balancing switch unit, the balancing system corresponding to the balancing switch unit, and the battery pack corresponding to the balancing switch unit. The active balancing circuit can achieve active balancing of each battery by setting the energy providing module, the AC bus, the isolation conversion module, and a plurality of balancing systems.

Description

Technical Field

[0001] This application relates to the technical field of battery balancing, and particularly to an active balancing circuit and an energy storage device. Background Art

[0002] Balancing is a technical function that must be possessed by multi-cell series connection in a high-voltage battery pack. Currently, balancing technologies are divided into two types: one is passive balancing technology, and the other is active balancing technology. Among them, passive balancing technology is widely used because of its simple principle, reliable operation, and low cost. However, its balancing ability is poor and the efficiency is low.

[0003] Among them, active balancing technology has strong balancing ability and high efficiency, but the existing active balancing structure is complex, costly, and large in volume and space. Summary of the Invention

[0004] Embodiments of this application provide an active balancing circuit and an energy storage device to achieve active balancing of batteries, and the circuit structure is simple, small in volume, and low in cost.

[0005] To solve the above technical problems, embodiments of this application disclose the following technical solutions:

[0006] In a first aspect, an active balancing circuit is provided, which is applied to an energy storage device. The energy storage device at least includes a battery management system and a plurality of battery packs; the active balancing circuit includes: an energy providing module, an AC bus, an isolation conversion module, and a plurality of balancing systems; wherein, each of the balancing systems is respectively connected to one of the isolation conversion modules and one of the battery packs;

[0007] Among them, the energy providing module is connected to the battery management system and is connected to each of the isolation conversion modules through the AC bus;

[0008] Among them, each of the balancing systems at least includes a balancing switch unit; the balancing switch unit is respectively connected to the corresponding isolation conversion module and the corresponding battery pack;

[0009] The balancing switch unit is configured to conduct or disconnect a loop formed by the energy providing module, the AC bus, the isolation conversion module corresponding to the balancing switch unit, the balancing system corresponding to the balancing switch unit, and the battery pack corresponding to the balancing switch unit.

[0010] Combined with the first aspect, each of the battery packs includes a plurality of batteries; each of the balancing systems further includes a DC bus and a plurality of balancing modules;

[0011] Each of the DC buses is connected to the corresponding isolation conversion module; each of the balancing modules is connected in parallel to the corresponding DC bus;

[0012] Each of the equalization modules is connected to one of the batteries, and each of the equalization modules includes an equalization switch unit; the equalization switch units are respectively connected to the corresponding DC bus and the corresponding battery;

[0013] The equalization switch unit is further configured to conduct or disconnect a loop formed by the energy supply module, the AC bus, the isolation conversion module corresponding to the equalization switch unit, the equalization module corresponding to the equalization switch unit, and the battery corresponding to the equalization switch unit.

[0014] In combination with the first aspect, the equalization switch unit includes: a first switch, a second switch, a third switch, a first resistor, a second resistor, and a first analog front-end acquisition unit; wherein, the first switch is integrated inside the first analog front-end acquisition unit;

[0015] Wherein, a first end of the first switch is connected to the battery management system, a second end of the first switch is respectively connected to a first end of the first resistor and a first end of the second switch, and a third end of the first switch is respectively connected to a first end of the second resistor and a first end of the third switch; a second end of the second switch is respectively connected to a second end of the first resistor and the corresponding isolation conversion module; a third end of the second switch is connected to a positive electrode of the corresponding battery; a second end of the third switch is respectively connected to a second end of the second resistor and the corresponding isolation conversion module, and a third end of the third switch is connected to a negative electrode of the corresponding battery.

[0016] In combination with the first aspect, the first resistor is an upper bias resistor, and the second resistor is a lower bias resistor.

[0017] In combination with the first aspect, the first switch is an NPN-type MOS transistor, the second switch is a PNP-type triode, and the third switch is an NPN-type triode.

[0018] In combination with the first aspect, the equalization switch unit includes: a fourth switch, a fifth switch, a sixth switch, a seventh switch, a third resistor, a fourth resistor, a fifth resistor, and a second analog front-end acquisition unit; wherein, the fourth switch is integrated inside the second analog front-end acquisition unit;

[0019] Wherein, a first end of the fourth switch is connected to the battery management system, a second end of the fourth switch is respectively connected to a second end of the sixth switch and a positive electrode of the corresponding battery, and a third end of the fourth switch is respectively connected to a first end of the fifth switch, a second end of the seventh switch, and a negative electrode of the corresponding battery;

[0020] The second terminal of the fifth switch is respectively connected to the first terminal of the third resistor and the first terminal of the sixth switch, and the third terminal of the fifth switch is respectively connected to the first terminal of the fourth resistor and the second terminal of the seventh switch;

[0021] The third terminal of the sixth switch is respectively connected to the second terminal of the third resistor and the corresponding isolation conversion module; the first terminal of the seventh switch is respectively connected to the second terminal of the fourth resistor and the first terminal of the fifth resistor, and the third terminal of the seventh switch is respectively connected to the second terminal of the fifth resistor and the corresponding isolation conversion module.

[0022] Combined with the first aspect, the fourth switch is an NPN type MOS transistor, the fifth switch is an NPN type triode, the sixth switch is a PNP type triode, and the seventh switch is an NPN type triode.

[0023] Combined with the first aspect, the isolation conversion module includes an isolation transformer and a rectifier circuit. The isolation transformer is connected in parallel to the AC bus, and the rectifier circuit is respectively connected to the corresponding isolation transformer and the corresponding equalization system.

[0024] Combined with the first aspect, the energy providing module is a DC-AC converter.

[0025] In a second aspect, an energy storage device is provided, including the active equalization circuit described above.

[0026] One of the technical solutions in the above technical solutions has the following advantages or beneficial effects:

[0027] Compared with the prior art, an active balancing circuit of the present application includes: an energy supply module, an AC bus, an isolation conversion module, and multiple balancing systems; wherein, each balancing system is respectively connected to an isolation conversion module and a battery pack; wherein, the energy supply module is connected to the battery management system and is connected to each isolation conversion module through the AC bus; wherein, each balancing system includes at least a balancing switch unit; the balancing switch unit is respectively connected to the corresponding isolation conversion module and the corresponding battery pack; the balancing switch unit is used to conduct or disconnect the loop formed by the energy supply module, the AC bus, the isolation conversion module corresponding to the balancing switch unit, the balancing system corresponding to the balancing switch unit, and the battery pack corresponding to the balancing switch unit. The active balancing circuit provided by the present application can achieve active balancing of each battery pack in the energy storage device by setting the energy supply module, the AC bus, the isolation conversion module, and multiple balancing systems. By setting the AC bus and the energy supply module, it is possible to share the same active balancing energy for the balancing systems of each battery pack, thereby simplifying the circuit structure and reducing the volume. And by setting the energy supply module, the AC bus, the isolation conversion module, multiple balancing systems, and the balancing switch unit in each balancing system, it is also possible to achieve targeted individual balancing of the battery packs that need to be balanced without starting other unnecessary devices, thus reducing power consumption and cost and reducing the adverse factors brought by device temperature rise. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present application. For those skilled in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0029] Figure 1 is a schematic diagram of the principle structure of an active balancing circuit provided in an embodiment of the present application;

[0030] Figure 2 is a schematic diagram of the principle structure of another active balancing circuit provided in an embodiment of the present application;

[0031] Figure 3 is a schematic diagram of the structure of a balancing switch unit provided in an embodiment of the present application;

[0032] Figure 4 is a schematic diagram of the structure of another balancing switch unit provided in an embodiment of the present application;

[0033] Figure 5 is a schematic diagram of the structure of an active balancing circuit provided in an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments in the present application without creative efforts belong to the scope of protection of the present application.

[0035] In the description of the present application, it should be understood that in the description of the present application, the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more features. In the description of the present application, "a plurality of" means two or more, and at least one means one, two or more, unless otherwise specifically defined.

[0036] After research by the applicant, it is found that balancing is a technical function that must be possessed by the series connection of multiple batteries in a high-voltage battery pack. Self-discharge is an inherent property of the battery cells. Due to production consistency and process differences, the self-discharge of each battery cell will be different. However, the series connection of multiple battery cells to form a high-voltage battery pack is consistent during the charging and discharging process of the entire pack. In this way, due to the different self-discharges of each battery cell in the entire pack of battery cells, over time, the voltage of the battery cell with a large self-discharge will become lower and lower, the voltage difference of the entire pack will become larger and larger, and the effective power used by the entire pack will become smaller and smaller as the voltage difference increases, until the effective power used by the entire pack is zero and it cannot be used.

[0037] To solve the voltage difference caused by different self-discharges of battery cells, these battery cells need to be balanced to make their voltages consistent. The technology that can adjust the voltage difference caused by different self-discharges of multiple series-connected battery cells is called battery cell balancing technology. Currently, the balancing technology is divided into two types: one is passive balancing technology, and the other is active balancing technology. Among them, passive balancing technology is currently widely used. Its principle is that when there is a voltage difference in the battery pack, taking the lowest battery voltage as the balancing target, the battery with a higher voltage is discharged until the voltage of the entire battery pack is adjusted to be consistent through discharging. Passive balancing has many advantages. For example, the principle is simple, the operation is reliable, and the cost is low. However, it also has many disadvantages. For example, the balancing ability is poor (mainly referring to the small balancing current, within 200 mA), all the balancing currents flow through the inside of the acquisition chip (internal balancing in the acquisition chip), resulting in a high chip temperature, which will cause over-temperature protection of the chip, increase the balancing time, low efficiency, and shorten the driving range of the whole vehicle.

[0038] Among them, due to reasons such as technology, cost, reliability, and volume space, the active balancing technology has not been applied in batches to power battery packs. Its working principle is to use isolated bidirectional switch power supply technology to realize flexible energy movement between the entire battery pack and achieve the effect of battery voltage balance. Its advantages are strong balancing ability (large balancing current) and high efficiency. However, it also has many disadvantages. For example, the structure is complex, the cost is high, and the volume space is large.

[0039] Therefore, the embodiments of the present application provide an active balancing circuit and an energy storage device to provide an active balancing solution with a simple structure and easy implementation, so as to achieve active balancing of the battery.

[0040] Figure 1 It is a schematic structural block diagram of an active balancing circuit provided in the embodiments of the present application. Please refer to Figure 1 , this active balancing circuit is applied to an energy storage device. The energy storage device at least includes a battery management system 10 and multiple battery packs; the active balancing circuit includes: an energy providing module 100, an AC bus LAC, an isolation conversion module, and multiple balancing systems; among them, each balancing system is respectively connected to an isolation conversion module and a battery pack; among them, the energy providing module is connected to the battery management system and is connected to each isolation conversion module through the AC bus; among them, each balancing system at least includes a balancing switch unit; the balancing switch unit is respectively connected to the corresponding isolation conversion module and the corresponding battery pack; the balancing switch unit is used to conduct or disconnect the loop formed by the energy providing module 100, the AC bus, the isolation conversion module corresponding to the LAC balancing switch unit, the balancing system corresponding to the balancing switch unit, and the battery pack corresponding to the balancing switch unit.

[0041] Among them, a Battery Management Unit (BMU) is provided in the Battery Management System (BMS) 10. Through the BMU, it is possible to determine whether each battery pack and / or each battery needs to perform active balancing, receive various battery status information, and send various control commands (such as commands to turn on or off switches), etc. These are all conventional technologies in the art and will not be elaborated further here.

[0042] Among them, the AC bus LAC can be a general wiring harness or a twisted pair, etc., and can be specifically set according to the actual situation, and no specific limitation is made here.

[0043] Among them, the energy source of the energy supply module 100 can be 12V low voltage or PACK battery high voltage.

[0044] Among them, an electrical switch can be set in the energy supply module 100. When the BMS detects that a battery needs to be actively charged, the electrical switch in the energy supply module 100 can be turned on through a control instruction, and the voltage or current of the energy supply module 100 can be adjusted to the voltage or current required by the battery to be charged. Among them, the electrical switch can be a switch circuit or structure composed of a triode, a MOS switch tube, etc., and the opening or closing of the switch can be controlled by sending a control instruction through the BMS or BMU. These are all conventional technologies in the art and will not be elaborated further here.

[0045] Among them, the energy storage device includes a plurality of battery packs. Exemplarily, refer to Figure 1 , the energy storage device includes a first battery pack 21, a second battery pack 22,..., an Nth battery pack 23.

[0046] Among them, the active balancing circuit includes a plurality of balancing systems, and each balancing system is respectively connected to an isolation conversion module and a battery pack. Each isolation conversion module is connected in parallel with the AC bus LAC. Among them, each balancing system includes at least a balancing switch unit; each balancing switch unit is respectively connected to the corresponding isolation conversion module and the corresponding battery pack. Exemplarily, refer to Figure 1 , assuming that the active balancing circuit includes a first balancing system 310, a second balancing system 320,..., an Nth balancing system 330, and a first isolation conversion module 210, a second isolation conversion module 220,..., an Nth isolation conversion module 230. Among them, the first balancing system 310 includes a first balancing switch unit 301, the second balancing system 320 includes a second balancing switch unit 302, and the Nth balancing system 330 includes an Nth balancing switch unit 303.

[0047] Among them, the first isolation conversion module 210 is connected in parallel to the AC bus LAC, and the first equalization system 310 is respectively connected to the first isolation conversion module 210 and the first battery pack 21. The first equalization switch unit 301 is arranged in the first equalization system 310 and is respectively connected to the first isolation conversion module 210 and the first battery pack 21. The first equalization switch unit 301 is used to conduct or disconnect the loop formed by the energy supply module 100, the AC bus LAC, the first isolation conversion module 210 corresponding to the first equalization switch unit 301, the first equalization system 310 corresponding to the first equalization switch unit 301, and the first battery pack 21 corresponding to the first equalization switch unit 301. Among them, the conduction or disconnection control of the first equalization switch unit 301 can be controlled by the BMS or BMU to send corresponding opening or closing control instructions through a method such as daisy-chain serial communication. For example, when the BMS or BMU determines that the first battery pack 21 needs to be actively charged (i.e., active equalization is required), it sends an opening control instruction for the first equalization switch unit 301 to control its opening, so that the loop formed by the energy supply module 100, the AC bus LAC, the first isolation conversion module 210 corresponding to the first equalization switch unit 301, the first equalization system 310 corresponding to the first equalization switch unit 301, and the first battery pack 21 corresponding to the first equalization switch unit 301 is conducted, so that the charging current provided by the energy supply module can actively charge the first battery pack 21, thereby realizing the equalization of the energy storage device. When the BMS or BMU determines that the active charging of the first battery pack 21 is completed, it sends a closing control instruction for the first equalization switch unit 301 to control its disconnection, so that the loop formed by the energy supply module 100, the AC bus LAC, the first isolation conversion module 210 corresponding to the first equalization switch unit 301, the first equalization system 310 corresponding to the first equalization switch unit 301, and the first battery pack 21 corresponding to the first equalization switch unit 301 is disconnected.

[0048] Among them, the second isolation conversion module 220 is connected in parallel to the AC bus LAC, and the second equalization system 320 is respectively connected to the second isolation conversion module 220 and the second battery pack 22. The second equalization switch unit 302 is disposed within the second equalization system 320 and is respectively connected to the second isolation conversion module 220 and the second battery pack 22. The second equalization switch unit 302 is used to conduct or disconnect the loop formed by the energy supply module 100, the AC bus LAC, the second isolation conversion module 220 corresponding to the second equalization switch unit 302, the second equalization system 320 corresponding to the second equalization switch unit 302, and the second battery pack 22 corresponding to the second equalization switch unit 302. Among them, the conduction or cutoff control of the second equalization switch unit 302 can be controlled by the BMS or BMU sending corresponding on or off control commands through a method such as daisy-chain serial communication. For example, when the BMS or BMU determines that the second battery pack 22 needs to be actively charged (i.e., active equalization is required), it sends an on control command for the second equalization switch unit 302 to control its conduction, so that the loop formed by the energy supply module 100, the AC bus LAC, the second isolation conversion module 220 corresponding to the second equalization switch unit 302, the second equalization system 320 corresponding to the second equalization switch unit 302, and the second battery pack 22 corresponding to the second equalization switch unit 302 is conducted, so that the charging current provided by the energy supply module can actively charge the second battery pack 22, thereby achieving the equalization of the energy storage device. When the BMS or BMU determines that the active charging of the second battery pack 22 is completed, it sends an off control command for the second equalization switch unit 302 to control its disconnection, so that the loop formed by the energy supply module 100, the AC bus LAC, the second isolation conversion module 220 corresponding to the second equalization switch unit 302, the second equalization system 320 corresponding to the second equalization switch unit 302, and the second battery pack 22 corresponding to the second equalization switch unit 302 is disconnected.

[0049] Similarly, the connection relationship among the Nth isolation conversion module 230, the Nth equalization system 330, the Nth equalization switch unit 303, and the Nth battery pack 23, and the implementation principle of the equalization control of the corresponding Nth battery pack 23 are the same as those of the first battery pack and the second battery pack described above, and will not be elaborated here.

[0050] Among them, the isolation conversion module is used to isolate and rectify the voltage or current provided by the energy supply module 100 through the AC bus LAC, so as to provide an active charging current for the battery pack or battery corresponding to the corresponding equalization system. For example, assuming that the BMU determines that the second battery pack 22 needs to perform active equalization, the BMU controls the electrical switch of the energy supply module 100 to turn on and adjusts the output current to the magnitude of the active charging current required by the second battery pack 22. The active charging current output by the energy supply module 100 is transmitted to the second isolation conversion module 220 through the AC bus LAC, and after being isolated and rectified by the second isolation conversion module 220, it is output to the corresponding second equalization system 320 to provide a charging current for the active equalization of the second battery pack 22.

[0051] Among them, an Analog Front-End (AFE) acquisition chip can be integrated in each equalization system. Through the AFE, the state information such as voltage, current, and SOC of each battery in each battery pack can be monitored and acquired in real time, and sent to the BMU through a communication method such as daisy-chain serial communication. The BMU judges whether active charging is required according to the state information of each battery pack or each battery. When the BMU determines that a certain battery pack or battery needs to perform active charging, a control instruction to turn on the corresponding equalization switch unit of the battery pack or battery is sent to the corresponding equalization switch unit through a communication method such as daisy-chain serial communication, and the magnitude of the active charging current required by the battery pack or battery is adjusted and output through the energy supply module 100 to provide an active charging current for the battery pack or battery, so as to achieve active equalization.

[0052] Among them, in each equalization system, the equalization switch unit of each equalization system is integrated with the corresponding acquisition chip AFE. On the one hand, it can realize the acquisition, information transmission, and instruction reception of battery state information during the battery active equalization process, which is beneficial to realizing active equalization. On the other hand, it can improve the integration degree, simplify the circuit structure, reduce the volume, and lower the cost.

[0053] In the technical solution of this embodiment, the implementation process of the active equalization circuit is as follows: Refer to Figure 1, Exemplarily, assume that the BMU determines that the second battery pack 22 needs to be actively charged. The BMU sends a switch-on command to the second balancing switch unit 302, and at the same time controls the energy supply module 100 to turn on and output the active charging current required by the second battery pack 22 to the AC bus LAC. After receiving the switch-on command, the second balancing switch unit 302 makes the loop formed by the energy supply module 100, the AC bus LAC, the second isolation conversion module 220, the second balancing system, and the second battery pack 22 conductive, thereby realizing the active charging of the second battery pack 22. During the charging process of the second battery pack 22, the AFE in the second balancing system 320 monitors information such as the current and voltage of the second battery pack 22 in real time and sends it to the BMU through daisy-chain serial communication. The BMU determines in real time whether the active charging of the second battery pack 22 is completed according to the voltage, current and other information of the second battery pack 22 obtained in real time. When it is determined that the charging of the second battery pack 22 is completed, a switch-off command is sent to the second balancing switch unit 302. After receiving the switch-off command, the second balancing switch unit 302 makes the loop formed by the energy supply module 100, the AC bus LAC, the second isolation conversion module 220, the second balancing system, and the second battery pack 22 disconnected, and the second battery pack 22 stops active charging. Similarly, the principle of active balancing of other battery packs is the same as that of the second battery pack, and will not be elaborated here. Thus, through the active balancing circuit provided by the present application, active balancing control of each battery pack can be realized, and by setting the AC bus and the energy supply module, the balancing systems of each battery pack can share the same active balancing energy, thereby simplifying the circuit structure and reducing the volume. And by setting the energy supply module, the AC bus, the isolation conversion module, multiple balancing systems, and setting balancing switch units in each balancing system, it is also possible to specifically balance the battery packs that need to be balanced individually without starting other unnecessary devices, so that the power consumption and cost can be reduced, and the adverse factors brought by the device temperature rise can be reduced.

[0054] Figure 2 is the principle structure block diagram of another active balancing circuit provided in the embodiment of the present application. On the basis of the above embodiment, please refer to Figure 2 , each battery pack includes a plurality of batteries; each balancing system further includes a DC bus and a plurality of balancing modules; each DC bus is connected to the corresponding isolation conversion module; each balancing module is connected in parallel to the corresponding DC bus; each balancing module is connected to a battery, and each balancing module includes a balancing switch unit; the balancing switch unit is respectively connected to the corresponding DC bus and the corresponding battery; the balancing switch unit is further configured to conduct or disconnect the loop formed by the energy supply module, the AC bus, the isolation conversion module corresponding to the balancing switch unit, the balancing module corresponding to the balancing switch unit, and the battery corresponding to the balancing switch unit.

[0055] Among them, the DC bus LDC can be a general wire harness or a printed copper foil within a Printed Circuit Board (PCB), and can be specifically set according to the actual situation, and no specific limitation is made here.

[0056] Among them, each battery pack includes a plurality of batteries, that is, the first battery pack 21, the second battery pack 22,..., the Nth battery pack 23 all include a plurality of batteries. Exemplarily, taking the second battery pack 22 as an example, the second battery pack 22 includes the first battery B1, the second battery B2,..., the nth battery Bn.

[0057] Among them, each balancing system further includes a DC bus and a plurality of balancing modules, and each DC bus is connected to the corresponding isolation conversion module. That is, the first balancing system 310, the second balancing system 320,..., the Nth balancing system 330 all include a DC bus and a plurality of balancing modules. Exemplarily, taking the second balancing system 320 as an example, the second balancing system 320 includes the DC bus LDC, the first balancing module 321, the second balancing module 322,..., the nth balancing module 323. Among them, the DC bus LDC is connected to the second isolation conversion module 220. The first balancing module 321 is connected to the first battery B1, the second balancing module 322 is connected to the second battery B2, and the nth balancing module 323 is connected to the nth battery Bn. Among them, the first balancing module 321 includes a balancing switch unit A 3211, the second balancing module 322 includes a balancing switch unit B 3221,..., and the nth balancing module 323 includes a balancing switch unit n 3231.

[0058] Among them, the equalization switch unit A 3211 is respectively connected to the DC bus LDC, the second isolation conversion module 220, and the first battery B1. The equalization switch unit A 3211 is used to conduct or disconnect the loop formed by the energy supply module 100, the AC bus LAC, the second isolation conversion module 220, the first equalization module 321, and the first battery B1. Among them, the conduction or cutoff control of the equalization switch unit A 3211 can be controlled by the BMS or BMU sending corresponding opening or closing control instructions through a method such as daisy-chain serial communication. For example, when the BMS or BMU determines that the first battery B1 needs to be actively charged (i.e., active equalization is required), it sends an opening control instruction for the equalization switch unit A 3211 to control its opening, so that the loop formed by the energy supply module 100, the AC bus LAC, the second isolation conversion module 220, the first equalization module 321, and the first battery B1 corresponding to the equalization switch unit A 3211 is conducted, so that the charging current provided by the energy supply module can actively charge the first battery B1, thereby realizing the equalization of the energy storage device. When the BMS or BMU determines that the active charging of the first battery B1 is completed, it sends a closing control instruction for the equalization switch unit A 3211 to control its disconnection, so that the loop formed by the energy supply module 100, the AC bus LAC, the second isolation conversion module 220, the first equalization module 321, and the first battery B1 corresponding to the equalization switch unit A 3211 is disconnected.

[0059] Among them, the equalization switch unit B 3221 is respectively connected to the DC bus LDC, the second isolation conversion module 220, and the second battery B2. The equalization switch unit B 3221 is used to conduct or disconnect the loop formed by the energy supply module 100, the AC bus LAC, the second isolation conversion module 220, the second equalization module 322, and the second battery B2. Among them, the conduction or cutoff control of the equalization switch unit B 3221 can be controlled by the BMS or BMU to send corresponding opening or closing control instructions through a method such as daisy-chain serial communication. For example, when the BMS or BMU determines that the second battery B2 needs to be actively charged (i.e., active equalization is required), it sends an opening control instruction for the equalization switch unit B 3221 to control its opening, so that the loop formed by the energy supply module 100, the AC bus LAC, the second isolation conversion module 220, the second equalization module 322, and the second battery B2 corresponding to the equalization switch unit B 3221 is conducted, so that the charging current provided by the energy supply module can actively charge the second battery B2, thereby realizing the equalization of the energy storage device. When the BMS or BMU determines that the active charging of the second battery B2 is completed, it sends a closing control instruction for the equalization switch unit B 3221 to control its disconnection, so that the loop formed by the energy supply module 100, the AC bus LAC, the second isolation conversion module 220, the second equalization module 322, and the second battery B2 corresponding to the equalization switch unit B 3221 is disconnected.

[0060] Similarly, the connection relationship among the nth equalization module 323, the equalization switch unit n, the DC bus LDC, the second isolation conversion module 220, and the nth battery Bn and the implementation principle of the equalization control of the nth battery Bn are the same as those of the first battery and the second battery described above, and will not be elaborated here.

[0061] Among them, in each equalization module, the equalization switch unit of each equalization module is integrated with the corresponding acquisition chip AFE. On the one hand, it can realize the acquisition, information transmission, and instruction reception of the battery state information during the active equalization process of the battery, which is beneficial to realizing active equalization. On the other hand, it can improve the integration degree, simplify the circuit structure, reduce the volume, and lower the cost.

[0062] In some embodiments, the isolation conversion module includes an isolation transformer and a rectifier circuit. The isolation transformer is connected in parallel to the AC bus, and the rectifier circuit is respectively connected to the corresponding isolation transformer and the corresponding equalization system.

[0063] Among them, the first isolation conversion module 210, the second isolation conversion module 220,..., the Nth isolation conversion module 230 all include an isolation transformer and a rectifier circuit. Exemplarily, taking the second isolation conversion module 220 as an example, refer to Figure 2, the second isolation conversion module 220 includes an isolation transformer 221 and a rectification circuit 222. Among them, the isolation transformer 221 is used to isolate the active charging voltage or current provided by the energy supply module 100 through the AC bus LAC. Among them, the rectification circuit 222 is used to rectify the isolated active charging voltage or current and output it to the corresponding equalization module to actively charge the corresponding battery. For example, the isolated and rectified active charging current is output to the first equalization module 321 to provide the active charging current for the first battery B1.

[0064] Among them, the rectification circuit can be a rectifier bridge, a full-wave rectification, a half-wave rectification composed of fast recovery diodes, and a general rectification structure composed of filter capacitors, etc., which can be specifically set according to the actual situation and will not be specifically limited here.

[0065] In some embodiments, the energy supply module is a DC-AC converter.

[0066] In the technical solution of this embodiment, the implementation process of the active equalization circuit is as follows: Refer to Figure 2, Exemplarily, assume that the BMU determines that the second battery B2 needs to be actively charged. The BMU sends a switch-on command to the equalization switch unit B 3221, and at the same time controls the energy supply module 100 to turn on and output the active charging current required by the second battery B2 to the AC bus LAC. After receiving the switch-on command, the equalization switch unit B 3221 makes the loop formed by the energy supply module 100, the AC bus LAC, the second isolation conversion module 220, the second equalization module 322, and the second battery B2 conductive, so as to realize the active charging of the second battery B2. During the charging process of the second battery B2, the AFE in the second equalization module 322 monitors the current, voltage and other information of the second battery B2 in real time and sends it to the BMU through daisy-chain serial communication. The BMU determines in real time whether the active charging of the second battery B2 is completed according to the voltage, current and other information of the second battery B2 obtained in real time. When it is determined that the charging of the second battery B2 is completed, a switch-off command is sent to the equalization switch unit B 3221. After receiving the switch-off command, the equalization switch unit B 3221 makes the loop formed by the energy supply module 100, the AC bus LAC, the second isolation conversion module 220, the second equalization module 322, and the second battery B2 disconnected, and the second battery B2 stops active charging. Similarly, the principle of active equalization of other batteries is the same as that of the second battery and will not be elaborated here. Thus, through the active equalization circuit provided by the present application, active equalization control of each battery can be realized, and by setting the AC bus and the energy supply module, the equalization modules of each battery can share the same active equalization energy, thereby simplifying the circuit structure and reducing the volume. And by setting the energy supply module, the AC bus, the isolation conversion module, multiple equalization systems, multiple equalization modules in each equalization system, and equalization switch units in each equalization module, it is possible to realize targeted active charging of the batteries that need to be equalized alone without starting other unnecessary devices, so that the power consumption and cost can be reduced, and the adverse factors brought by the temperature rise of the devices can be reduced.

[0067] Exemplarily, the equalization switch unit has two structures, one is a two-transistor switch structure, and the other is a three-transistor switch structure.

[0068] Figure 3 is a schematic structural diagram of an equalization switch unit provided in an embodiment of the present application. Exemplarily, for the structure of the equalization switch unit with a two-transistor switch structure, please refer to Figure 3, the balancing switch unit includes: a first switch Q1, a second switch Q2, a third switch Q3, a first resistor R1, a second resistor R2, and a first analog front-end acquisition unit 30; wherein, the first switch Q1 is integrated inside the first analog front-end acquisition unit 30; wherein, the first end of the first switch Q1 is connected to the battery management system BMS, the second end of the first switch Q1 is respectively connected to the first end of the first resistor R1 and the first end of the second switch Q2, and the third end of the first switch Q1 is respectively connected to the first end of the second resistor R2 and the first end of the third switch Q3; the second end of the second switch Q2 is respectively connected to the second end of the first resistor R1 and the corresponding isolation conversion module; the third end of the second switch Q2 is connected to the positive electrode of the corresponding battery; the second end of the third switch Q3 is respectively connected to the second end of the second resistor R2 and the corresponding isolation conversion module, and the third end of the third switch Q3 is connected to the negative electrode of the corresponding battery.

[0069] Wherein, the first analog front-end acquisition unit 30 is used to collect information such as the voltage, current, SOC, temperature, etc. of the corresponding battery in real time. Wherein, the first analog front-end acquisition unit 30 can be an acquisition chip AFE. Wherein, the first switch Q1 is integrated inside the acquisition chip AFE. Wherein, the acquisition chip AFE can communicate with the BMU or BMS through daisy-chain serial communication.

[0070] In some embodiments, the first resistor R1 is an upper bias resistor, and the second resistor R2 is a lower bias resistor.

[0071] Wherein, the specific resistance values of the first resistor R1 and the second resistor R2 can be set according to actual situations and are not specifically limited herein.

[0072] In some embodiments, the first switch is an NPN-type MOS transistor, the second switch is a PNP-type triode, and the third switch is an NPN-type triode.

[0073] In the technical solution of this embodiment, the implementation process of the equalization switch unit is as follows: Exemplarily, assume that the equalization switch unit is connected to the first battery B1. The second end (i.e., the emitter e) of the second switch Q2 is connected to the DC + of the DC bus of the corresponding equalization module, and the third end (i.e., the collector c) of the second switch Q2 is connected to the positive electrode of the first battery B1. The first end (i.e., the base b1) of the second switch Q2 is connected to the emitter e of the second switch Q2 through the first resistor R1. At the same time, the first end of the second switch Q2 is connected to the second end (i.e., the drain D) of the first switch Q1. The third end (i.e., the source S) of the first switch Q1 is connected to the first end (i.e., the base b2) of the third switch Q3. The first end of the third switch Q3 is simultaneously connected to the second end (i.e., the emitter e) of the third switch Q3 through the second resistor R2, and they are jointly connected to the DC - of the DC bus. The third end (i.e., the collector c) of the third switch Q3 is connected to the negative electrode of the first battery B1. The BMU collects information such as the voltage and current of all batteries in the battery pack. Assume that when the BMU determines that the first battery B1 needs to be actively charged, the BMU sends a charging command to the acquisition chip AFE where the first battery B1 is located through the daisy chain. The AFE selects the equalization channel corresponding to the first battery B1 according to the BMU command, and turns on the equalization MOS switch tube corresponding to this channel, that is, the first switch Q1, through software. At the same time, the BMU controls the energy supply module to output the current required for the active charging of the first battery B1. Thus, the active charging current output by the energy supply module is output to the DC bus corresponding to the equalization system or equalization module where the first battery B1 is located after isolation and rectification, and passes through the first resistor R1, the first switch Q1, and the second resistor R2 in sequence through the power supply of the DC + of the DC bus and is output to the DC - of the corresponding DC bus, forming a current path or loop, thereby turning on the second switch Q2 and the third switch Q3, enabling the active charging current to charge the first battery B1, and realizing the active equalization of the first battery B1. Since the sampling circuit of the AFE samples continuously during the charging process, the AFE sends the battery voltage to the BMU through the daisy chain, and the BMU determines whether the voltage requirement for charging is met. When the BMU determines that the charging is completed, it turns off the first switch Q1, thereby turning off the second switch Q2 and the third switch Q3, and finally turns off the energy supply module to stop charging the first battery B1.

[0074] Figure 4 It is a schematic structural diagram of another equalization switch unit provided in the embodiment of the present application. Exemplarily, for the structural diagram of the equalization switch unit with a three - transistor switch structure, please refer to Figure 4, the balancing switch unit includes: a fourth switch Q4, a fifth switch Q5, a sixth switch Q6, a seventh switch Q7, a third resistor R3, a fourth resistor R4, a fifth resistor R5, and a second analog front-end acquisition unit 40; wherein, the fourth switch Q4 is integrated inside the second analog front-end acquisition unit 40; wherein, the first terminal of the fourth switch Q4 is connected to the battery management system BMS, the second terminal of the fourth switch Q4 is respectively connected to the second terminal of the sixth switch Q6 and the positive electrode of the corresponding battery, and the third terminal of the fourth switch Q4 is respectively connected to the first terminal of the fifth switch Q5, the second terminal of the seventh switch Q7, and the negative electrode of the corresponding battery; the second terminal of the fifth switch Q5 is respectively connected to the first terminal of the third resistor R3 and the first terminal of the sixth switch Q6, and the third terminal of the fifth switch Q5 is respectively connected to the first terminal of the fourth resistor R4 and the second terminal of the seventh switch Q7; the third terminal of the sixth switch Q6 is respectively connected to the second terminal of the third resistor R3 and the corresponding isolation conversion module; the first terminal of the seventh switch Q7 is respectively connected to the second terminal of the fourth resistor R4 and the first terminal of the fifth resistor R5, and the third terminal of the seventh switch Q7 is respectively connected to the second terminal of the fifth resistor R5 and the corresponding isolation conversion module.

[0075] Wherein, the second analog front-end acquisition unit 40 is used to collect information such as the voltage, current, SOC, temperature, etc. of the corresponding battery in real time. Wherein, the second analog front-end acquisition unit 40 can be an acquisition chip AFE. Wherein, the fourth switch Q4 is integrated inside the acquisition chip AFE. Wherein, the acquisition chip AFE can communicate with the BMU or BMS through daisy-chain serial communication.

[0076] Wherein, the third resistor R3 is an upper bias resistor, and the fifth resistor R5 is a lower bias resistor.

[0077] Wherein, the specific resistance values of the third resistor R3, the fourth resistor R4, and the fifth resistor R5 can be set according to the actual situation, and no specific limitation is made here.

[0078] In some embodiments, the fourth switch is an NPN-type MOS transistor, the fifth switch is an NPN-type triode, the sixth switch is a PNP-type triode, and the seventh switch is an NPN-type triode.

[0079] In addition, referring to Figure 4 , the balancing switch unit further includes a sixth resistor R6, a seventh resistor R7, and a first diode D1. Wherein, the first diode D1 is used for reverse protection.

[0080] In the technical solution of the embodiment of the present application, the balancing switch unit of the three-switch structure is different from that of the two-switch structure in order to set different structures for the different two-battery three-balancing lead-out lines and two-balancing lead-out lines. However, the working principles of the two structures are the same. In the technical solution of this embodiment, the implementation process of the balancing switch unit is as follows: Exemplarily, assume that the balancing switch unit is connected to the nth battery Bn, and the BMU collects information such as the voltage and current of all batteries in the battery pack. Assume that when the BMU determines that the nth battery Bn needs to be actively charged, the BMU sends a charging command to the acquisition chip AFE where the nth battery Bn is located through the daisy chain. The AFE selects the balancing channel corresponding to the nth battery Bn according to the BMU command, and turns on the balancing MOS switch tube corresponding to this channel, that is, the fourth switch Q4, through software. At the same time, the BMU controls the energy supply module to output the current required for the active charging of the nth battery Bn. Thus, the active charging current output by the energy supply module is output to the DC bus corresponding to the balancing system or balancing module where the nth battery Bn is located after isolation and rectification, and the power supply of the DC DC+ of the DC bus passes through the third resistor R3, the fifth switch Q5, the fourth resistor R4, and the fifth resistor R5 in sequence and is output to the DC DC- of the corresponding DC bus, forming a current path or loop, thereby turning on the sixth switch Q6 and the seventh switch Q7, so that the active charging current charges the nth battery Bn, realizing the active balancing of the nth battery Bn. Since the sampling circuit of the AFE samples all the time during the charging process, the AFE sends the battery voltage to the BMU through the daisy chain, and the BMU judges whether the voltage requirement for charging is met. When the BMU judges that the charging is completed, the fourth switch Q4 is turned off, thereby turning off the sixth switch Q6 and the seventh switch Q7, and finally turning off the energy supply module to stop charging the nth battery Bn.

[0081] Figure 5 It is a schematic structural diagram of an active balancing circuit provided in the embodiment of the present application. Exemplarily, Figure 5 In it, the balancing switch unit adopts Figure 3 The structure shown is taken as an example for illustration. The implementation process of this active balancing circuit is as follows: Exemplarily, refer to Figure 5, assuming that the BMU determines that the first battery B1 needs to be actively charged, the BMU sends a charging command to the acquisition chip AFE where the first battery B1 is located through daisy chain transmission. The AFE selects the balancing channel corresponding to the first battery B1 according to the BMU command, and turns on the balancing MOS switch tube corresponding to this channel, that is, the first switch Q1, through software. At the same time, the BMU controls the energy supply module 100 to turn on and output the active charging current required by the first battery B1 to the AC bus LAC. After the first switch Q1 is turned on, the active charging current output by the energy supply module is isolated by the isolation transformer and rectified by the rectifier bridge 2, and then output to the DC bus corresponding to the balancing system or balancing module where the first battery B1 is located. The power supply of the DC DC+ of the DC bus passes through the first resistor R1, the first switch Q1, and the second resistor R2 in sequence and is output to the DC DC- of the corresponding DC bus, forming a current path or loop, thereby turning on the second switch Q2 and the third switch Q3, so that the active charging current charges the first battery B1, realizing the active balancing of the first battery B1. Since the sampling circuit of the AFE samples all the time during the charging process, the AFE sends the battery voltage to the BMU through daisy chain, and the BMU judges whether the voltage requirement for charging is met. When it is judged that the charging of the first battery B1 is completed, a switch-off command is sent to the first switch Q1. After the first switch Q1 is turned off, the second switch Q2 and the third switch Q3 are turned off, and the active charging of the first battery B1 is turned off. Similarly, the principle of active balancing of other batteries is the same as that of the first battery, and will not be elaborated here. Thus, through the active balancing circuit provided by this application, the active balancing control of each battery can be realized, and by setting the AC bus and the energy supply module, the balancing modules of each battery can share the same active balancing energy, thereby simplifying the circuit structure and reducing the volume. And by setting the energy supply module, the AC bus, the isolation conversion module, multiple balancing systems, setting multiple balancing modules in each balancing system, and setting balancing switch units in each balancing module, it is possible to actively charge the batteries that need to be balanced separately in a targeted manner without starting other unnecessary devices, so the power consumption and cost can be reduced, and the adverse factors brought by the temperature rise of the devices can be reduced.

[0082] Correspondingly, the embodiment of this application also provides an energy storage device, and this energy storage device includes the active balancing circuit described in any embodiment of this application.

[0083] The above has introduced in detail an active balancing circuit and an energy storage device provided by the embodiments of the present application. Specific examples are used in this article to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the technical solution and its core idea of the present application; those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An active balancing circuit, characterized in that, Applied to an energy storage device, the energy storage device at least includes a battery management system and a plurality of battery packs; the active equalization circuit includes: an energy supply module, an AC bus, an isolation conversion module, and a plurality of equalization systems; wherein, each of the equalization systems is respectively connected to one of the isolation conversion modules and one of the battery packs; Wherein, the energy supply module is connected to the battery management system and is connected to each of the isolation conversion modules through the AC bus; Wherein, each of the equalization systems at least includes an equalization switch unit; the equalization switch unit is respectively connected to the corresponding isolation conversion module and the corresponding battery pack; The equalization switch unit is configured to conduct or disconnect a loop formed by the energy supply module, the AC bus, the isolation conversion module corresponding to the equalization switch unit, the equalization system corresponding to the equalization switch unit, and the battery pack corresponding to the equalization switch unit; the equalization switch unit includes: a first switch, a second switch, a third switch, a first resistor, a second resistor, and a first analog front-end acquisition unit; wherein, the first switch is integrated inside the first analog front-end acquisition unit; Wherein, a first end of the first switch is connected to the battery management system, a second end of the first switch is respectively connected to a first end of the first resistor and a first end of the second switch, and a third end of the first switch is respectively connected to a first end of the second resistor and a first end of the third switch; a second end of the second switch is respectively connected to a second end of the first resistor and the corresponding isolation conversion module; a third end of the second switch is connected to the positive electrode of the corresponding battery pack; a second end of the third switch is respectively connected to a second end of the second resistor and the corresponding isolation conversion module, and a third end of the third switch is connected to the negative electrode of the corresponding battery pack.

2. The active balancing circuit according to claim 1, wherein Each of the battery packs includes a plurality of batteries; each of the equalization systems further includes a DC bus and a plurality of equalization modules; Each of the DC buses is connected to the corresponding isolation conversion module; each of the equalization modules is connected in parallel to the corresponding DC bus; Each of the equalization modules is connected to one of the batteries, and each of the equalization modules includes one of the equalization switch units; the equalization switch unit is respectively connected to the corresponding DC bus and the corresponding battery; The equalization switch unit is further configured to conduct or disconnect a loop formed by the energy supply module, the AC bus, the isolation conversion module corresponding to the equalization switch unit, the equalization module corresponding to the equalization switch unit, and the battery corresponding to the equalization switch unit.

3. The active balancing circuit according to claim 1, wherein The first resistor is an upper bias resistor, and the second resistor is a lower bias resistor.

4. The active balancing circuit according to claim 1, characterized in that, The first switch is an NPN-type MOS transistor, the second switch is a PNP-type triode, and the third switch is an NPN-type triode.

5. An active balancing circuit, characterized in that, Applied to an energy storage device, the energy storage device at least includes a battery management system and a plurality of battery packs; the active equalization circuit includes: an energy supply module, an AC bus, an isolation conversion module, and a plurality of equalization systems; wherein, each of the equalization systems is respectively connected to one of the isolation conversion modules and one of the battery packs; Wherein, the energy supply module is connected to the battery management system and is connected to each of the isolation conversion modules through the AC bus; Wherein, each of the equalization systems at least includes an equalization switch unit; the equalization switch unit is respectively connected to the corresponding isolation conversion module and the corresponding battery pack; The equalization switch unit is used to conduct or disconnect the loop formed by the energy supply module, the AC bus, the isolation conversion module corresponding to the equalization switch unit, the equalization system corresponding to the equalization switch unit, and the battery pack corresponding to the equalization switch unit; The equalization switch unit includes: a fourth switch, a fifth switch, a sixth switch, a seventh switch, a third resistor, a fourth resistor, a fifth resistor, and a second analog front-end acquisition unit; wherein, the fourth switch is integrated inside the second analog front-end acquisition unit; Wherein, the first end of the fourth switch is connected to the battery management system, the second end of the fourth switch is respectively connected to the second end of the sixth switch and the positive electrode of the corresponding battery pack, and the third end of the fourth switch is respectively connected to the first end of the fifth switch, the second end of the seventh switch, and the negative electrode of the corresponding battery pack; The second end of the fifth switch is respectively connected to the first end of the third resistor and the first end of the sixth switch, and the third end of the fifth switch is respectively connected to the first end of the fourth resistor and the second end of the seventh switch; The third end of the sixth switch is respectively connected to the second end of the third resistor and the corresponding isolation conversion module; the first end of the seventh switch is respectively connected to the second end of the fourth resistor and the first end of the fifth resistor, and the third end of the seventh switch is respectively connected to the second end of the fifth resistor and the corresponding isolation conversion module.

6. The active balancing circuit according to claim 5, characterized in that, Each of the battery packs includes a plurality of batteries; each of the equalization systems further includes a DC bus and a plurality of equalization modules; Each of the DC buses is connected to the corresponding isolation conversion module; each of the equalization modules is connected in parallel to the corresponding DC bus; Each of the equalization modules is connected to one of the batteries, and each of the equalization modules includes one of the equalization switch units; the equalization switch unit is respectively connected to the corresponding DC bus and the corresponding battery; The equalization switch unit is also used to conduct or disconnect the loop formed by the energy supply module, the AC bus, the isolation conversion module corresponding to the equalization switch unit, the equalization module corresponding to the equalization switch unit, and the battery corresponding to the equalization switch unit.

7. The active balancing circuit according to claim 5, wherein The fourth switch is an NPN-type MOS transistor, the fifth switch is an NPN-type triode, the sixth switch is a PNP-type triode, and the seventh switch is an NPN-type triode.

8. The active balancing circuit according to claim 5, wherein The isolation conversion module includes an isolation transformer and a rectification circuit. The isolation transformer is connected in parallel to the AC bus, and the rectification circuit is respectively connected to the corresponding isolation transformer and the corresponding equalization system.

9. The active balancing circuit according to claim 5, wherein The energy supply module is a DC-AC converter.

10. A energy storage device, characterized in that, It includes the active equalization circuit according to any one of claims 1-4 or 5-9.

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