Active equalization circuit and energy storage device

Abstract

The invention discloses an active equalization circuit and an energy storage device, and relates to the technical field of battery equalization. The circuit comprises an energy supply module, an AC bus, an isolation conversion module and a plurality of equalization systems. Each equalization system is respectively connected with one isolation conversion module and one battery pack; the energy supply module is connected with the battery management system and is connected with each isolation conversion module through an alternating current bus; each equalization system comprises an equalization switch unit; the equalization switch units are respectively connected with the corresponding isolation conversion modules and the corresponding battery packs; the equalization switch unit is used for connecting or disconnecting 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. According to the active equalization circuit, the energy supply module, the alternating current bus, the isolation conversion module and the plurality of equalization systems are arranged, so that active equalization of each battery can be realized.

Description

Technical Field

[0001] The present application relates to the technical field of battery balancing, and in particular to an active balancing circuit and an energy storage device. Background Art

[0002] Balancing is a technical function that must be possessed by multiple batteries in series in a high-voltage battery pack. Currently, there are two types of balancing technologies: passive balancing technology and active balancing technology. Among them, passive balancing technology is widely used due to its simple principle, reliable operation and low cost. However, it has poor balancing ability and low efficiency.

[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 size. Summary of the invention

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

[0005] In order to solve the above technical problems, the embodiments of the present application disclose the following technical solutions: In a first aspect, an active balancing circuit is provided, which is applied to an energy storage device, wherein the energy storage device comprises at least a battery management system and a plurality of battery packs; the active balancing circuit comprises: an energy supply 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; 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; Each of the balancing systems at least comprises 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 turn on or off a 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.

[0006] In combination with the first aspect, each of the battery packs includes a plurality of batteries; each of the balancing systems also includes a DC bus and a plurality of balancing modules; 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; Each of the balancing modules is connected to a battery, and each of the balancing modules 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 also used to turn on or off a 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.

[0007] In combination with the first aspect, the balancing 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; Among them, the first end of the first switch is connected to the battery management system, the second end of the first switch is respectively connected to the first end of the first resistor and the first end of the second switch, the third end of the first switch is respectively connected to the first end of the second resistor and the first end of the third switch; the second end of the second switch is respectively connected to the second end of the first resistor and the corresponding isolation conversion module; the third end of the second switch is connected to the positive electrode of the corresponding battery; the second end of the third switch is respectively connected to the second end of the second resistor and the corresponding isolation conversion module, and the third end of the third switch is connected to the negative electrode of the corresponding battery.

[0008] In combination with the first aspect, the first resistor is an upper bias resistor, and the second resistor is a lower bias resistor.

[0009] In combination with the first aspect, the first switch is an NPN MOS transistor, the second switch is a PNP transistor, and the third switch is an NPN transistor.

[0010] In combination with the first aspect, the balancing 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 corresponding positive electrode of the battery, 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 corresponding negative electrode of the battery; 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.

[0011] In combination with the first aspect, the fourth switch is an NPN MOS transistor, the fifth switch is an NPN transistor, the sixth switch is a PNP transistor, and the seventh switch is an NPN transistor.

[0012] In combination 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 balancing system.

[0013] In combination with the first aspect, the energy providing module is a DC to AC converter.

[0014] In a second aspect, an energy storage device is provided, comprising the active balancing circuit described above.

[0015] One of the above technical solutions has the following advantages or beneficial effects: 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 turn on or off 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 realize active balancing of each battery pack in the energy storage device by setting an energy supply module, an AC bus, an isolation conversion module and multiple balancing systems. By setting an AC bus and an energy supply module, it is possible to realize that the balancing systems of each battery pack share the same active balancing energy, thereby simplifying the circuit structure and reducing the volume. In addition, by providing an energy supply module, an AC bus, an isolation conversion module, multiple balancing systems, and balancing switch units in each balancing system, it is possible to achieve targeted balancing of battery groups that need to be balanced separately without starting other unnecessary devices, thereby reducing power consumption and costs and reducing adverse factors caused by device temperature rise. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 It is a principle structural block diagram of an active equalization circuit provided in an embodiment of the present application; Figure 2 It is a principle structure block diagram of another active equalization circuit provided in an embodiment of the present application; Figure 3 is a structural schematic diagram of a balancing switch unit provided in an embodiment of the present application; Figure 4 is a structural schematic diagram of another balancing switch unit provided in an embodiment of the present application; Figure 5 It is a structural schematic diagram of an active equalization circuit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0019] In the description of the present application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are 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 cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are used only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more features. In the description of the present application, "multiple" means two or more, and at least one means one, two or more, unless otherwise clearly and specifically defined.

[0020] The applicant has found through research that balancing is a technical function that multiple batteries in series in a high-voltage battery pack must have. Self-discharge is an inherent property of the battery cell. Different batteries have different self-discharge rates due to production consistency and process differences. The high-voltage battery pack composed of multiple batteries in series is consistent during the charging and discharging process of the entire pack. In this way, due to the different self-discharge rates of each battery cell in the entire pack, the voltage of the battery cell with large self-discharge will become lower and lower over time, and the pressure difference of the entire pack will become larger and larger. As the pressure difference increases, the effective amount of electricity used by the entire pack will become smaller and smaller, until the effective amount of electricity used by the entire pack is zero and cannot be used.

[0021] In order to solve the voltage difference caused by the different self-discharge of the cells, it is necessary to balance these cells to make the cell voltage consistent. This technology that can connect multiple cells in series and adjust the voltage difference caused by the different self-discharge of the cells is called cell balancing technology. At present, there are two types of balancing technologies: one is passive balancing technology and the other is active balancing technology. Among them, passive balancing technology is currently widely used. Its principle is: when there is a voltage difference in the battery pack, the lowest battery voltage is used as the balancing target, and the battery with high voltage is discharged until the voltage of the entire pack is adjusted to be consistent through discharge. Passive balancing has many advantages, such as simple principle, reliable operation and low cost. However, there are also many disadvantages, such as poor balancing ability (mainly refers to small balancing current, within 200mA), all balancing currents flow through the acquisition chip (balanced inside the acquisition chip), resulting in chip temperature rise, which will lead to chip over-temperature protection, increase balancing time, low efficiency, and shorten the vehicle's driving range.

[0022] Among them, active balancing technology has not been applied in large quantities to power battery packs due to technical, cost, reliability, volume and space reasons. Its working principle is: using isolated bidirectional switching power supply technology to achieve flexible energy movement between the entire pack of batteries and achieve battery voltage balancing effect. Its advantages are strong balancing ability (large balancing current) and high efficiency. However, it also has many disadvantages, such as complex structure, high cost, and large volume and space.

[0023] To this end, 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, thereby achieving active balancing of the battery.

[0024] Figure 1 is a principle structure block diagram of an active equalization circuit provided in an embodiment of the present application. Figure 1The active balancing circuit is applied to an energy storage device, which at least includes a battery management system 10 and a plurality of battery packs; the active balancing circuit includes: an energy supply module 100, an AC bus LAC, an isolation conversion module and a plurality of 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 turn on or off the loop formed by the energy supply 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.

[0025] Among them, the battery management system (Battery Management System, BMS) 10 is provided with a battery management system main control single-chip computer (Battery Management Unit, BMU), through which it is possible to determine whether each battery pack and / or each battery needs to be actively balanced, receive various battery status information, and send various control commands (such as commands to turn on or off switches), etc. These are conventional technologies in this field and are not further explained here.

[0026] The AC bus LAC may be a general wiring harness or a twisted pair, etc., and may be specifically configured according to actual conditions, and is not specifically limited here.

[0027] The energy source of the energy providing module 100 may be a 12V low voltage or a PACK battery high voltage.

[0028] Among them, an electric switch can be set in the energy supply module 100. When the BMS detects that a battery needs to be actively charged, the electric 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 is adjusted to the voltage or current required by the charged battery. Among them, the electric 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 by the BMS or BMU. These are conventional technologies in the field and are not further explained here.

[0029] Wherein, the energy storage device includes a plurality of battery packs. Figure 1 The energy storage device includes a first battery group 21, a second battery group 22, ..., an Nth battery group 23.

[0030] The active balancing circuit includes multiple balancing systems, and each balancing system is connected to an isolation conversion module and a battery pack. Each isolation conversion module is connected in parallel to the AC bus LAC. Each balancing system includes at least a balancing switch unit; each balancing switch unit is connected to a corresponding isolation conversion module and a corresponding battery pack. For example, see 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. 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.

[0031] The first isolation conversion module 210 is connected in parallel to the AC bus LAC, and the first balancing system 310 is connected to the first isolation conversion module 210 and the first battery pack 21, respectively. The first balancing switch unit 301 is arranged in the first balancing system 310, and is connected to the first isolation conversion module 210 and the first battery pack 21, respectively. The first balancing switch unit 301 is used to turn on or off the loop formed by the energy supply module 100, the AC bus LAC, the first isolation conversion module 210 corresponding to the first balancing switch unit 301, the first balancing system 310 corresponding to the first balancing switch unit 301, and the first battery pack 21 corresponding to the first balancing switch unit 301. The on or off control of the first balancing switch unit 301 can be controlled by the BMS or BMU by sending a corresponding on or off control instruction in a manner such as daisy chain serial communication. For example, when the BMS or BMU determines that the first battery group 21 needs to be actively charged (i.e., active balancing is required), the first balancing switch unit 301 is turned on by sending a control instruction 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 balancing switch unit 301, the first balancing system 310 corresponding to the first balancing switch unit 301, and the first battery group 21 corresponding to the first balancing switch unit 301 is turned on, so that the charging current provided by the energy supply module can be used to actively charge the first battery group 21, thereby achieving the balancing of the energy storage device. When the BMS or BMU determines that the active charging of the first battery group 21 is completed, the first balancing switch unit 301 is turned off by sending a control instruction 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 balancing switch unit 301, the first balancing system 310 corresponding to the first balancing switch unit 301, and the first battery group 21 corresponding to the first balancing switch unit 301 is disconnected.

[0032] The second isolation conversion module 220 is connected in parallel to the AC bus LAC, and the second balancing system 320 is connected to the second isolation conversion module 220 and the second battery pack 22, respectively. The second balancing switch unit 302 is arranged in the second balancing system 320, and is connected to the second isolation conversion module 220 and the second battery pack 22, respectively. The second balancing switch unit 302 is used to turn on or off the loop formed by the energy supply module 100, the AC bus LAC, the second isolation conversion module 220 corresponding to the second balancing switch unit 302, the second balancing system 320 corresponding to the second balancing switch unit 302, and the second battery pack 22 corresponding to the second balancing switch unit 302. The on or off control of the second balancing switch unit 302 can be controlled by the BMS or BMU by sending a corresponding on or off control instruction in a manner 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 balancing is required), the second balancing switch unit 302 is turned on by sending a control instruction 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 corresponding to the second balancing switch unit 302, the second balancing system 320 corresponding to the second balancing switch unit 302, and the second battery pack 22 corresponding to the second balancing switch unit 302 is turned on, so that the charging current provided by the energy supply module can be used to actively charge the second battery pack 22, thereby achieving the balancing of the energy storage device. When the BMS or BMU determines that the active charging of the second battery pack 22 is completed, the second balancing switch unit 302 is turned off by sending a control instruction 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 balancing switch unit 302, the second balancing system 320 corresponding to the second balancing switch unit 302, and the second battery pack 22 corresponding to the second balancing switch unit 302 is disconnected.

[0033] Similarly, the connection relationship between the Nth isolation conversion module 230, the Nth balancing system 330, the Nth balancing switch unit 303 and the Nth battery group 23 and the corresponding Nth battery group 23 balancing control implementation principle are the same as the principles of the first battery group and the second battery group mentioned above, and will not be repeated here.

[0034] 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 active charging current for the battery group or battery corresponding to the corresponding balancing system. For example, assuming that the BMU determines that the second battery group 22 needs to be actively balanced, the BMU controls the power switch of the energy supply module 100 to turn on, and adjusts the current output by it to the active charging current required by the second battery group 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 is output to the corresponding second balancing system 320 after isolation and rectification by the second isolation conversion module 220, providing charging current for active balancing of the second battery group 22.

[0035] Among them, each balancing system may be integrated with an analog front-end acquisition chip (Analog Front-End, AFE), through which the voltage, current, SOC and other status information of each battery pack and each battery can be monitored and collected in real time, and sent to the BMU through a daisy chain serial communication method. The BMU determines whether active charging is required based on the status information of each battery pack or each battery. When the BMU determines that a battery pack or battery needs to be actively charged, the control instruction of the balancing switch unit corresponding to the battery pack or battery is sent to the corresponding balancing switch unit through a daisy chain serial communication method, and the active charging current required by the battery pack or battery is adjusted and output through the energy supply module 100 to provide the battery pack or battery with an active charging current to achieve active balancing.

[0036] Among them, in each balancing system, the balancing switch unit of each balancing system is integrated with the corresponding acquisition chip AFE, which can realize the collection of battery status information, information transmission and command reception during the active battery balancing process, which is conducive to the realization of active balancing. On the other hand, it can improve the integration, simplify the circuit structure, reduce the volume and reduce the cost.

[0037] In the technical solution of this embodiment, the implementation process of the active equalization circuit is as follows: Figure 1For example, assuming that the BMU determines that the second battery pack 22 needs to be actively charged, the BMU sends a switch-on instruction to the second balancing switch unit 302, and 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 instruction, 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 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 the current, voltage and other information 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 based on the voltage and 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 disconnection instruction is sent to the second balancing switch unit 302. After the second balancing switch unit 302 receives the switch disconnection instruction, 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 is disconnected, and the second battery pack 22 stops actively charging. Similarly, the active balancing principle of other battery packs is the same as that of the second battery pack, which will not be repeated here. Therefore, 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 system of each battery pack can share the same active balancing energy, thereby simplifying the circuit structure and reducing the volume. In addition, by providing an energy supply module, an AC bus, an isolation conversion module, multiple balancing systems, and balancing switch units in each balancing system, it is possible to achieve targeted balancing of battery groups that need to be balanced separately without starting other unnecessary devices, thereby reducing power consumption and costs and reducing adverse factors caused by device temperature rise.

[0038] Figure 2 is a principle structure block diagram of another active equalization circuit provided in the embodiment of the present application. Figure 2 Each battery pack includes multiple batteries; each balancing system also includes a DC bus and multiple balancing modules; each DC bus is connected to a 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 also used to turn on or off 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.

[0039] The DC bus LDC may be a general wiring harness or a printed copper foil in a printed circuit board (PCB). It may be specifically configured according to actual conditions and is not specifically limited here.

[0040] Each battery pack includes multiple batteries, that is, the first battery pack 21, the second battery pack 22, ..., and the Nth battery pack 23 all include multiple batteries. Exemplarily, taking the second battery pack 22 as an example, the second battery pack 22 includes a first battery B1, a second battery B2, ..., and an nth battery Bn.

[0041] Each balancing system further includes a DC bus and a plurality of balancing modules, and each DC bus is connected to a corresponding isolation conversion module. That is, the first balancing system 310, the second balancing system 320, ..., and 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 a DC bus LDC, a first balancing module 321, a second balancing module 322, ..., and an nth balancing module 323. 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. 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.

[0042] The balancing switch unit A 3211 is respectively connected to the DC bus LDC, the second isolation conversion module 220 and the first battery B1, and the balancing switch unit A 3211 is used to turn on or off the loop formed by the energy supply module 100, the AC bus LAC, the second isolation conversion module 220, the first balancing module 321 and the first battery B1. The on or off control of the balancing switch unit A 3211 can be controlled by the BMS or BMU sending a corresponding on or off control instruction in a manner 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 balancing is required), the balancing switch unit A 3211 is sent to control its on, so that the loop formed by the energy supply module 100, the AC bus LAC, the second isolation conversion module 220, the first balancing module 321 and the first battery B1 corresponding to the balancing switch unit A 3211 is turned on, so that the charging current provided by the energy supply module can be used to actively charge the first battery B1, thereby achieving the balancing 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 to the balancing 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 balancing module 321 and the first battery B1 corresponding to the balancing switch unit A 3211 is disconnected.

[0043] The balancing switch unit B 3221 is connected to the DC bus LDC, the second isolation conversion module 220 and the second battery B2 respectively, and the balancing switch unit B 3221 is used to turn on or off the loop formed by the energy supply module 100, the AC bus LAC, the second isolation conversion module 220, the second balancing module 322 and the second battery B2. The on or off control of the balancing switch unit B 3221 can be controlled by the BMS or BMU sending a corresponding on or off control instruction in a manner 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 balancing is required), the balancing switch unit B 3221 is sent to turn on the control instruction, so that the loop formed by the energy supply module 100, the AC bus LAC, the second isolation conversion module 220, the second balancing module 322 and the second battery B2 corresponding to the balancing switch unit B 3221 is turned on, so that the charging current provided by the energy supply module can be used to actively charge the second battery B2, thereby achieving the balancing 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 to the balancing 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 balancing module 322 and the second battery B2 corresponding to the balancing switch unit B 3221 is disconnected.

[0044] Similarly, the connection relationship between the nth balancing module 323, the balancing switch unit n, the DC bus LDC, the second isolation conversion module 220 and the nth battery Bn and the principle of balancing control of the nth battery Bn are the same as those of the first battery and the second battery, and will not be repeated here.

[0045] Among them, in each balancing module, the balancing switch unit of each balancing module is integrated with the corresponding acquisition chip AFE, which can realize the collection of battery status information, information transmission and command reception during the battery active balancing process, which is conducive to the realization of active balancing. On the other hand, it can improve the integration, simplify the circuit structure, reduce the volume and reduce the cost.

[0046] 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 connected to the corresponding isolation transformer and the corresponding balancing system respectively.

[0047] The first isolation conversion module 210, the second isolation conversion module 220, ..., and the Nth isolation conversion module 230 all include an isolation transformer and a rectifier circuit. Figure 2, the second isolation conversion module 220 includes an isolation transformer 221 and a rectifier circuit 222. The isolation transformer 221 is used to isolate the active charging voltage or current provided by the energy providing module 100 through the AC bus LAC. The rectifier circuit 222 is used to rectify the isolated active charging voltage or current and output it to the corresponding balancing module to actively charge the corresponding battery. For example, the active charging current is isolated and rectified and then output to the first balancing module 321 to provide the first battery B1 with an active charging current.

[0048] Among them, the rectifier circuit can be a full-wave rectifier composed of a rectifier bridge and a fast recovery diode, a half-wave rectifier, and a general rectifier structure composed of a filter capacitor, etc., which can be specifically set according to actual conditions and is not specifically limited here.

[0049] In some embodiments, the energy providing module is a DC to AC converter.

[0050] In the technical solution of this embodiment, the implementation process of the active equalization circuit is as follows: Figure 2For example, assuming that the BMU determines that the second battery B2 needs to be actively charged, the BMU sends a switch-on instruction to the balancing switch unit B 3221, and 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 instruction, the balancing 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 balancing module 322 and the second battery B2 conductive, thereby realizing active charging of the second battery B2. During the charging process of the second battery B2, the AFE in the second balancing 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 based on the voltage and 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 disconnection instruction is sent to the balancing switch unit B 3221. After receiving the switch disconnection instruction, the balancing switch unit B 3221 disconnects the loop formed by the energy supply module 100, the AC bus LAC, the second isolation conversion module 220, the second balancing module 322 and the second battery B2, and the second battery B2 stops actively charging. Similarly, the active balancing principle of other batteries is the same as that of the second battery, which will not be repeated here. Therefore, through the active balancing circuit provided by the present application, 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. Furthermore, by providing an energy supply module, an AC bus, an isolation conversion module, multiple balancing systems, multiple balancing modules in each balancing system, and a balancing switch unit in each balancing module, it is possible to actively charge the batteries that need to be balanced individually without starting other unnecessary devices, thereby reducing power consumption and cost and reducing the adverse factors caused by device temperature rise.

[0051] Exemplarily, the balancing switch unit has two structures, one is a two-tube switch structure, and the other is a three-tube switch structure.

[0052] Figure 3 is a schematic diagram of a structure of a balancing switch unit provided in an embodiment of the present application. For example, the structure of a balancing switch unit with a two-tube switch structure can be found in Figure 3The 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.

[0053] The first analog front-end acquisition unit 30 is used to collect information such as voltage, current, SOC, temperature, etc. of the corresponding battery in real time. The first analog front-end acquisition unit 30 may be an acquisition chip AFE. The first switch Q1 is integrated inside the acquisition chip AFE. The acquisition chip AFE may communicate with the BMU or BMS via daisy chain serial communication.

[0054] In some embodiments, the first resistor R1 is an upper bias resistor, and the second resistor R2 is a lower bias resistor.

[0055] The specific resistance values ​​of the first resistor R1 and the second resistor R2 can be set according to actual conditions and are not specifically limited here.

[0056] In some embodiments, the first switch is an NPN MOS transistor, the second switch is a PNP transistor, and the third switch is an NPN transistor.

[0057] In the technical solution of this embodiment, the implementation process of the balancing switch unit is as follows: illustratively, the balancing 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 balancing 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 is connected to the DC- of the DC bus, and 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. 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 via a daisy chain. 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 the channel, namely 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. As a result, 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 first battery B1 is located after isolation and rectification, and the DC power supply of the DC bus is output to the DC- of the corresponding DC bus through the first resistor R1, the first switch Q1, and the second resistor R2 in sequence, 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, and realizes active balancing of the first battery B1. Since the sampling circuit of AFE keeps sampling during the charging process, AFE sends the battery voltage to BMU via daisy chain, and BMU determines whether the charging voltage requirement is met. When BMU determines that 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.

[0058] Figure 4 is a schematic diagram of the structure of another balancing switch unit provided in an embodiment of the present application. For example, the structure of the balancing switch unit with a three-tube switch structure can be found in Figure 4The 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 end of the fourth switch Q4 is connected to the battery management system BMS, the second end of the fourth switch Q4 is respectively connected to the second end of the sixth switch Q6 and the positive electrode of the corresponding battery, and the third end of the fourth switch Q4 is respectively connected to the first end of the fifth switch Q5 and the second end of the seventh switch Q7 and the negative electrode of the corresponding battery; the second end of the fifth switch Q5 is respectively connected to the first end of the third resistor R3 and the first end of the sixth switch Q6, and the third end of the fifth switch Q5 is respectively connected to the first end of the fourth resistor R4 and the second end of the seventh switch Q7; the third end of the sixth switch Q6 is respectively connected to the second end of the third resistor R3 and the corresponding isolation conversion module; the first end of the seventh switch Q7 is respectively connected to the second end of the fourth resistor R4 and the first end of the fifth resistor R5, and the third end of the seventh switch Q7 is respectively connected to the second end of the fifth resistor R5 and the corresponding isolation conversion module.

[0059] The second analog front-end acquisition unit 40 is used to collect information such as voltage, current, SOC, temperature, etc. of the corresponding battery in real time. The second analog front-end acquisition unit 40 may be an acquisition chip AFE. The fourth switch Q4 is integrated inside the acquisition chip AFE. The acquisition chip AFE may communicate with the BMU or BMS via daisy chain serial communication.

[0060] The third resistor R3 is an upper bias resistor, and the fifth resistor R5 is a lower bias resistor.

[0061] The specific resistance values ​​of the third resistor R3 , the fourth resistor R4 and the fifth resistor R5 can be set according to actual conditions and are not specifically limited here.

[0062] In some embodiments, the fourth switch is an NPN MOS transistor, the fifth switch is an NPN transistor, the sixth switch is a PNP transistor, and the seventh switch is an NPN transistor.

[0063] In addition, see Figure 4 The balancing switch unit further includes a sixth resistor R6, a seventh resistor R7 and a first diode D1. The first diode D1 is used for reverse protection.

[0064] In the technical solution of the embodiment of the present application, the difference between the balancing switch unit of the three-tube switch structure and the two-tube switch structure is that different structures are set according to the difference between the three balancing lead wires of two batteries and the two balancing lead wires, but 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: For example, the balancing switch unit is connected to the nth battery Bn, and the BMU collects the voltage, current and other information of all batteries in the battery pack. Assuming 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 via a 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 the 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 equalization system or equalization module where the nth battery Bn is located after isolation and rectification, and the DC+ power supply of the DC bus is sequentially output to the DC- of the corresponding DC bus through the third resistor R3, the fifth switch Q5, the fourth resistor R4, and the fifth resistor R5, forming a current path or loop, thereby opening the sixth switch Q6 and the seventh switch Q7, so that the active charging current charges the nth battery Bn, and realizes the active equalization of the nth battery Bn. Since the sampling circuit of the AFE is always sampling during the charging process, the AFE sends the battery voltage to the BMU via the daisy chain, and the BMU determines whether the charging voltage requirement is met. When the BMU determines that the charging is completed, the fourth switch Q4 is closed, thereby closing the sixth switch Q6 and the seventh switch Q7, and finally the energy supply module is closed to stop charging the nth battery Bn.

[0065] Figure 5 is a schematic diagram of the structure of an active equalization circuit provided in an embodiment of the present application. For example, Figure 5 The balanced switch unit is used Figure 3 The structure shown in FIG. 1 is used as an example to illustrate the implementation process of the active equalization circuit. For example, refer to FIG. 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 the daisy chain. 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 the channel, namely 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, and the DC power supply of the DC bus DC+ is sequentially output to the DC DC- of the corresponding DC bus through the first resistor R1, the first switch Q1, and the second resistor R2, 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, and realizes active balancing of the first battery B1. Since the sampling circuit of AFE is sampling all the time during the charging process, AFE sends the battery voltage to BMU via daisy chain, and BMU determines whether the charging voltage requirement is met. When it is determined that the charging of the first battery B1 is completed, a switch disconnection instruction 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 disconnected, and the active charging of the first battery B1 is turned off. Similarly, the active balancing principle of other batteries is the same as that of the first battery, which will not be repeated here. Therefore, through the active balancing circuit provided by the present application, active balancing control of each battery can be achieved, and by setting an AC bus and an 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 an energy supply module, an AC bus, an isolation conversion module, multiple balancing systems, multiple balancing modules in each balancing system, and a balancing switch unit in each balancing module, it is possible to achieve targeted active charging of the battery that needs to be balanced separately without starting other unnecessary devices, thereby reducing power consumption and cost, and reducing the adverse factors caused by the temperature rise of the device.

[0066] Correspondingly, an embodiment of the present application further provides an energy storage device, which includes the active balancing circuit described in any embodiment of the present application.

[0067] The above is a detailed introduction to an active balancing circuit and an energy storage device provided in the embodiments of the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solutions and core ideas of the present application. Ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An active equalization 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 balancing circuit includes: an energy supply 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; 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; Each of the balancing systems at least comprises 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 turn on or off a 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.

2. The active equalization circuit according to claim 1, characterized in that: Each of the battery packs includes a plurality of batteries; each of the balancing systems also includes a DC bus and a plurality of balancing modules; 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; Each of the balancing modules is connected to a battery, and each of the balancing modules 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 also used to turn on or off a 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.

3. The active equalization circuit according to claim 2, characterized in that: The balancing 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; Among them, the first end of the first switch is connected to the battery management system, the second end of the first switch is respectively connected to the first end of the first resistor and the first end of the second switch, the third end of the first switch is respectively connected to the first end of the second resistor and the first end of the third switch; the second end of the second switch is respectively connected to the second end of the first resistor and the corresponding isolation conversion module; the third end of the second switch is connected to the positive electrode of the corresponding battery; the second end of the third switch is respectively connected to the second end of the second resistor and the corresponding isolation conversion module, and the third end of the third switch is connected to the negative electrode of the corresponding battery.

4. The active equalization circuit according to claim 3, characterized in that: The first resistor is an upper bias resistor, and the second resistor is a lower bias resistor.

5. The active equalization circuit according to claim 3, characterized in that: The first switch is an NPN MOS transistor, the second switch is a PNP transistor, and the third switch is an NPN transistor.

6. The active equalization circuit according to claim 2, characterized in that: The balancing 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 corresponding positive electrode of the battery, 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 corresponding negative electrode of the battery; 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.

7. The active equalization circuit according to claim 6, characterized in that: The fourth switch is an NPN MOS transistor, the fifth switch is an NPN transistor, the sixth switch is a PNP transistor, and the seventh switch is an NPN transistor.

8. The active equalization circuit according to claim 1, characterized in that: The isolation conversion module includes an isolation transformer and a rectifier circuit. The isolation transformer is connected in parallel to the AC bus. The rectifier circuit is connected to the corresponding isolation transformer and the corresponding balancing system respectively.

9. The active equalization circuit according to claim 1, characterized in that: The energy providing module is a DC to AC converter.

10. An energy storage device, characterized in that: The invention comprises the active equalization circuit as claimed in any one of claims 1 to 9.

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