Battery active equalization circuit and power supply

Abstract

The invention discloses a battery active equalization circuit and a power supply, through a plurality of battery pack equalization modules in a cascade relationship, when a battery pack has a target battery monomer with energy lower than or higher than a preset energy threshold value, a matrix switch and a bipolar bidirectional isolation DC / DC converter work cooperatively, so that the battery active equalization circuit is realized. An energy transmission channel for transmitting energy between a target battery monomer and the battery pack is established, and the bipolar bidirectional isolation DC / DC converter transmits the energy in another battery pack to the target battery monomer through the energy transmission channel or transmits the energy of the battery monomer to another battery pack; accurate energy compensation among different battery packs is realized, and the equalization effect of the batteries is improved. In addition, according to the circuit structure, the equalization speed and the equalization effect are improved, meanwhile, the control logic is simplified, and the overall cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply, and in particular to a battery active balancing circuit and a power supply. Background Art

[0002] In modern battery applications, the balance of battery cells is critical to the performance and safety of the battery pack. Battery packs are usually composed of multiple battery cells connected in series or in parallel and then in series. However, due to differences in the manufacturing process of battery cells, uneven operating temperatures, aging processes, and changes in internal resistance, the performance differences between battery cells will gradually appear, resulting in imbalance in the battery pack. This phenomenon is particularly evident in batteries that have been used for a period of time or retired batteries.

[0003] When there is an imbalance in the battery cells within a battery pack, it will cause the "short board effect", that is, the total discharge of the battery pack is limited by the battery cell with the smallest power. This situation not only significantly shortens the battery life of the battery pack, but may also cause irreversible damage to the battery cell with the smallest power due to over-discharge or over-charge, and even bring potential safety hazards. Therefore, in order to ensure the performance and safety of the battery pack, it is necessary to balance the battery cells.

[0004] At present, according to the different ways of handling mismatch energy, battery balancing technology is mainly divided into two categories: passive balancing (energy consumption balancing) and active balancing (non-energy consumption balancing). Passive balancing technology balances the power between battery cells by consuming energy. Although it has a simple structure, its energy utilization efficiency is low. In contrast, active balancing technology can effectively utilize the entire power and capacity of the battery pack. It has high overall efficiency and strong balancing ability, but often has a large number of switch tubes, and can only balance one battery cell at a time, and it is difficult to achieve inter-group balancing control, resulting in high cost and slow balancing speed, that is, there is a poor balancing effect. Summary of the invention

[0005] The main purpose of the present invention is to provide a battery active balancing circuit and a power supply, aiming to at least solve the technical problem of poor balancing effect existing in the battery balancing method in the related art.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] According to a first aspect of the present invention, there is provided a battery active balancing circuit, the battery active balancing circuit comprising a plurality of battery group balancing modules in a cascade relationship; each of the battery group balancing modules comprises a battery group, a matrix switch, and a bipolar bidirectional isolated DC / DC converter, the battery group comprises a plurality of battery cells in a series relationship and forming series nodes at both ends respectively; the first series node of each battery cell is electrically connected to one end of a bidirectional switch in the matrix switch, the second series node of each battery cell is electrically connected to one end of another bidirectional switch in the matrix switch, the other end of one bidirectional switch is simultaneously connected to the first end of the low-voltage side port of the first matrix switch bus and the bipolar bidirectional isolated DC / DC converter, the other end of the other bidirectional switch is electrically connected to the second end of the low-voltage side port of the second matrix switch bus and the bipolar bidirectional isolated DC / DC converter, and the high-voltage side port of the bipolar bidirectional isolated DC / DC converter is electrically connected to both ends of the next battery group;

[0008] Wherein, when there is a target battery cell with energy lower than a preset energy threshold in one of the battery packs in the battery active balancing circuit, the matrix switch is used to perform a corresponding on or off state according to the received balancing control signal to establish an energy transmission channel, and the bipolar bidirectional isolated DC / DC converter is used to transmit the energy of the battery cell in another battery pack to the target battery cell through the energy transmission channel;

[0009] When a target battery cell with energy higher than a preset energy threshold exists in one of the battery packs in the battery active balancing circuit, the bipolar bidirectional isolated DC / DC converter is used to transfer the energy of the target battery cell to another battery pack through the energy transmission channel.

[0010] A second aspect of the present invention provides a power supply, comprising a device body and the battery active balancing circuit as described in the first aspect.

[0011] The battery active balancing circuit and power supply of the present invention, through the cascaded battery pack balancing module, when a battery pack has a target battery cell with energy lower than or higher than a preset energy threshold, combines the coordinated work of the matrix switch and the bipolar bidirectional isolated DC / DC converter to establish an energy transmission channel for transmitting energy to the target battery cell, and the bipolar bidirectional isolated DC / DC converter transmits the energy of the battery cell in another battery pack to the target battery cell through the energy transmission channel, and transmits the energy of the target battery cell to another battery pack through the energy transmission channel. Thereby, accurate energy compensation between different battery pack balancing modules is achieved, and the active balancing effect on the battery is improved. In addition, while improving the balancing speed and balancing effect, the circuit structure omits the polarity switching unit, simplifies the control logic, and reduces the overall cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0013] Figure 1 A circuit connection diagram of an active equalization circuit in the related art;

[0014] Figure 2 A circuit connection diagram of an active equalization circuit in the related art;

[0015] Figure 3 A circuit connection diagram of a battery pack balancing module in the battery active balancing circuit provided in an embodiment of the present application;

[0016] Figure 4 A circuit connection diagram of a battery active balancing circuit provided in an embodiment of the present application;

[0017] Figure 5 A circuit connection diagram of a bipolar bidirectional isolated DC / DC converter in an embodiment of the present application;

[0018] Figure 6 A circuit connection diagram of a bipolar bidirectional isolated DC / DC converter in an embodiment of the present application;

[0019] Figure 7 A circuit connection diagram of a bipolar bidirectional isolated DC / DC converter in an embodiment of the present application;

[0020] Figure 8A circuit connection diagram of a bipolar bidirectional isolated DC / DC converter in an embodiment of the present application;

[0021] Fig. 9 A circuit connection diagram of a bipolar bidirectional isolated DC / DC converter in an embodiment of the present application;

[0022] Fig.10 A circuit connection diagram of a bipolar bidirectional isolated DC / DC converter in an embodiment of the present application;

[0023] Fig.11 A circuit connection diagram of a bipolar bidirectional isolated DC / DC converter in an embodiment of the present application;

[0024] Fig.12 A circuit connection diagram of a battery active balancing circuit in an embodiment of the present application;

[0025] Fig.13 A circuit connection diagram of a bipolar bidirectional isolated DC / DC converter in an embodiment of the present application;

[0026] Fig.14 A circuit connection diagram of a battery active balancing circuit in an embodiment of the present application.

[0027] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0028] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0029] It should be noted that related terms such as "first", "second", etc. can be used to describe various components, but these terms do not limit the components. These terms are only used to distinguish one component from another component. For example, without departing from the scope of the present invention, a first component can be referred to as a second component, and the second component can also be referred to as a first component similarly. The term "and / or" refers to any one or more combinations of related items and description items.

[0030] See also Figure 1 , which shows an active balancing circuit in the related art, in which each battery requires a pair of bidirectional switches, which increases the number of devices, cost and volume; and in order to realize the conversion between the battery cell energy and the entire group of batteries, the entire string of batteries reuses the same bidirectional DC-DC module, and only a single battery can be balanced at a time.

[0031] See also Figure 2, which shows an active balancing circuit in the related art, in which a polarity switching unit is added between the bidirectional isolated DC conversion circuit and the matrix switch to realize the conversion between the battery cell energy and the entire battery group, and the entire string of batteries reuses the same bidirectional DC-DC module, and can only achieve balancing of a single battery at a time.

[0032] It can be seen that the active balancing circuit in the related art has many switch devices and can only achieve balancing of a single battery at a time, resulting in poor balancing effect.

[0033] To solve the above technical problems, please refer to Figure 3 and Figure 4 An embodiment of the present application provides a battery active balancing circuit, which includes a plurality of battery group balancing modules 10 in a cascade relationship (the number may be n, where n is a positive integer greater than or equal to 2).

[0034] Each battery pack balancing module 10 includes a battery pack 101, a matrix switch 102, a bipolar bidirectional isolated DC / DC converter 103 with bipolar input and a matrix switch bus (301, 302), and the battery pack 101 includes a plurality of battery cells 1013 that are in a series relationship and form series nodes (1012, 1014) at both ends. In each battery pack, the number of bidirectional switches is the number of battery cells plus 1.

[0035] Specifically, the first series node 1012 of each battery cell 1013 is electrically connected to one end of a bidirectional switch 1022 in the matrix switch 102, the second series node 1014 of each battery cell 1013 is electrically connected to one end of another bidirectional switch 1021 in the matrix switch 102, the other end of one bidirectional switch 1022 is simultaneously connected to the first matrix switch bus 301 and the first end 103B of the low-voltage side port of the bipolar bidirectional isolation DC / DC converter 103, the other end of another bidirectional switch 1021 is electrically connected to the second matrix switch bus 302 and the second end 103A of the low-voltage side port of the bipolar bidirectional isolation DC / DC converter 103, and the high-voltage side port (103C, 103D) of the bipolar bidirectional isolation DC / DC converter 103 is electrically connected to the two ends of the next battery group. The first series node of the corresponding adjacent battery cell is electrically connected to one end of another bidirectional switch in the matrix switch, thereby ensuring that the polarities of the adjacent battery cells on the matrix switch bus are opposite.

[0036] It should be noted that the first matrix switch bus 301 and the second matrix switch bus 302 serve together as a channel for the low-voltage side battery to converge or distribute, and the voltage between the two wires may change with the position of the battery. In addition, the second end 103A of the low-voltage side port is used to connect to the second matrix switch bus 302, and the first end 103B of the low-voltage side port is used to connect to the first matrix switch bus 301.

[0037] In addition, it should be noted that multiple "series nodes" are formed between adjacent battery cells in each battery pack balancing module 10. The "first series node" and "second series node" described in the above embodiment belong to the same "series node". Their different names are used to indicate their different electrical connection relationships, rather than specifically including only two numbers or two types of series nodes. (That is, the number of series nodes is related to the number of battery cells, and the electrical connection relationship between some series nodes and other series nodes in the series nodes is different)

[0038] In each battery pack balancing module 10, the functions of each component are as follows: the battery pack 101 forms an overall voltage output through multiple battery cells 1013 connected in series, and the matrix switch 102 flexibly controls each transmission channel corresponding to each battery cell 1013 through multiple bidirectional switches in parallel, and selectively uses battery cells 1013 with too much energy or too little energy as target battery cells (the battery with too much energy needs to transfer energy to another battery pack or the battery with too little energy needs to be compensated by the energy of another battery pack), that is, energy is transmitted between the battery cells of this group and the entire battery pack of another group, thereby realizing the balancing function.

[0039] Thus, when a target battery cell with energy lower than a preset energy threshold exists in a battery pack in the battery active balancing circuit, the matrix switch is used to perform a corresponding on or off state according to the received balancing control signal, so as to form an energy transmission channel adapted to the target battery cell, so that the bipolar bidirectional isolated DC / DC converter can transmit the energy in another battery pack to the target battery cell through the energy transmission channel. And, when a target battery cell with energy higher than a preset energy threshold exists in a battery pack in the battery active balancing circuit, the matrix switch is used to perform a corresponding on or off state according to the received balancing control signal, so as to form an energy transmission channel adapted to the target battery cell, so that the bipolar bidirectional isolated DC / DC converter can transmit the energy of the target battery cell to another battery pack through the energy transmission channel.

[0040] It should also be noted that the low-voltage side of the bipolar bidirectional isolated DC / DC converter is used to receive voltage signals of both positive and negative polarities, and the high-voltage side is used to receive voltage signals of positive polarity, and realize bidirectional energy transmission to reduce polarity conversion circuits. When the target battery cell needs to transmit excess energy, the path of the energy transmission channel is: the excess energy is transmitted from the target battery cell to the first end 103B and the second end 103A of the low-voltage side port (103A and 103B together constitute the first port as the battery voltage input / output port) through the matrix switch and the matrix switch bus connected thereto, and the bipolar bidirectional isolated DC / DC converter processes the excess energy and converts it into high-voltage energy and outputs it to the other battery group through the high-voltage side ports 103C and 103D (as the connection port for the voltage at both ends of another group of batteries). When the target battery cell needs energy compensation, the high-voltage side port of the bipolar bidirectional isolated DC / DC converter receives the compensation energy transmitted from another group of batteries, and processes the compensation energy to form low-voltage energy. The low-voltage energy reaches the target battery cell (to replenish its energy) through the low-voltage side port, the matrix switch bus, and the matrix switch.

[0041] The energy threshold can be adjusted according to the actual capacity of the battery pack, which will not be described in detail here.

[0042] In addition, the battery active balancing circuit forms a complete system capable of dynamically balancing the voltage of battery cells through the cascade design of multiple battery pack balancing modules 10. In the system, each module is interconnected with the adjacent module through a bipolar bidirectional isolated DC / DC converter 103 to achieve hierarchical energy transfer, thereby enhancing the overall balancing capability of the system.

[0043] The battery active balancing circuit and power supply of the present invention, through the cascaded battery pack balancing module, when a battery pack has a target battery cell with energy lower than or higher than a preset energy threshold, combined with the coordinated work of the matrix switch and the bipolar bidirectional isolated DC / DC converter, the bipolar bidirectional isolated DC / DC converter transmits the energy of another battery pack to the target battery cell, or transmits the energy of the target single battery cell to another battery pack, thereby realizing accurate energy compensation (inter-group balancing) between different battery pack balancing modules, that is, energy is transmitted between the battery cell of the present group (where the target battery cell exists) and the entire group of another battery pack, thereby improving the active balancing effect of the battery. It can be seen that the bipolar bidirectional isolated DC / DC converter of the present invention can handle positive and negative polarity voltages, reduce the number of matrix switch tubes, avoid the use of polarity switching circuits, and reduce system costs; and, it only needs to reasonably switch the high and low frequency states of the low-voltage side switch tube, and adopt the same set of control algorithms, so the control is simple.

[0044] In an optional implementation of this embodiment, the number of battery strings is positively correlated with the number of battery groups. The battery string can be divided into multiple battery groups in series according to demand, and the number of groups can be reasonably weighed according to the total number of cells that actually need to be balanced in the battery string, the circuit complexity of a single battery group, the cost, and the balancing speed. The more battery groups there are, the smaller the complexity of a single module, the more modules that can be balanced at the same time, and the faster the balancing speed, but the overall cost is also higher. Among them, a battery string is divided into multiple battery modules, and the balancing circuit in each battery module can operate independently, that is, the battery cells in multiple different units can be balanced at the same time, thereby improving the balancing efficiency.

[0045] In an optional implementation of this embodiment, the bidirectional switch can be a common source MOS tube, a common drain MOS tube, a relay, etc. Specifically, the specific selection of the bidirectional switch should comprehensively consider the power requirements, switching frequency, cost, and reliability requirements of the circuit. For example: in a high frequency, low power scenario, a common source or common drain MOS tube can be preferred. In a low frequency, high power scenario, a relay can be preferred. Through the above-mentioned multiple selection methods, the bidirectional switch in this embodiment can meet different application requirements and ensure the flexibility and applicability of the battery balancing circuit.

[0046] In an optional implementation of this embodiment, two adjacent battery group balancing modules may be electrically connected in series, which is suitable for increasing the total output voltage of the system. Alternatively, multiple independent battery groups may be used, each of which works independently, and energy balancing management within or across groups is achieved through a bidirectional isolated DC / DC converter.

[0047] In an optional implementation of this embodiment, the battery active balancing circuit further includes a first wire 201 and a second wire 202, which are used to connect the output end of the last battery pack balancing module in all battery pack balancing modules to the two ends of the battery pack of the first battery pack balancing module, forming a ring network energy transmission path, reducing the transmission path between the battery pack balancing modules at both ends. That is, through the energy transmission ring formed by the first wire 201 and the second wire 202, the balancing path when the voltage of the battery packs at both ends is unbalanced is shortened, thereby improving the balancing efficiency.

[0048] For example, the output of the bipolar bidirectional isolated DC / DC converter of the battery pack balancing module A is connected to both ends of the battery pack of the battery pack balancing module B, and the output of the bipolar bidirectional isolated DC / DC converter of the battery pack balancing module B is connected to both ends of the battery pack of the battery pack balancing module C. The first wire and the second wire are used to connect the output of the bipolar bidirectional isolated DC / DC converter of the battery pack balancing module C to both ends of the battery pack of the battery pack balancing module A, so that direct energy transmission between the battery pack balancing module A and the battery pack balancing module C can be realized. When there is no first wire and second wire, energy transmission can also be realized from A to B and then to C, but the number of transmission levels increases.

[0049] See also Figure 5 The bipolar bidirectional isolated DC / DC converter can be a resonant type converter, specifically including a transformer, a low-voltage side bipolar bridge circuit, and a high-voltage side unipolar bridge circuit. The input end of the transformer is electrically connected to the low-voltage side bipolar bridge circuit and the common bus, and the output end of the transformer is electrically connected to the two ends of the next battery pack via the high-voltage side unipolar bridge circuit.

[0050] In an optional embodiment, it may also include a first LC network and a second LC network, that is, the input end of the transformer is electrically connected to the common bus via the first LC network and the low-voltage side bipolar bridge circuit in sequence, and the output end of the transformer is electrically connected to the two ends of the next battery pack via the second LC network and the high-voltage side unipolar bridge circuit in sequence.

[0051] Specifically, the first LC network and the second LC network are auxiliary function circuits added as needed, which can be inductors, capacitors or a combination of the two. The two can be added to the circuit at the same time, or only one of them can be added to the circuit. The inductor of the LC network can be an independent inductor or a transformer leakage inductor. Of course, the resonant capacitor can also be combined with the capacitor voltage divider half bridge to realize the resonant function.

[0052] In an optional implementation manner of this embodiment, the bipolar bidirectional isolated DC / DC converter may also be a resonant converter of other input bipolar half-bridge, full-bridge, or half-bridge + full-bridge type, or may be one of various non-resonant half-bridge, full-bridge, or half-bridge + full-bridge isolation converters, as described below. Figures 6 to 11 , each non-resonant type converter is described accordingly:

[0053] Please read first Figure 6 The bipolar bidirectional isolated DC / DC converter can be a half-bridge type converter, which at least includes a transformer, a high-voltage side half-bridge unit (S H1 , S H2 , C H1 , C H2 ) and low voltage side half bridge unit (S L1 , SL2 , S L3 , S L4 , C L1 , C L2 ) and a magnetic device Ls, the primary winding of the transformer is electrically connected to the low-voltage side half-bridge unit via the magnetic device, and the secondary winding of the transformer is electrically connected to the high-voltage side half-bridge unit.

[0054] The following is an explanation of the specific circuit connections of each component:

[0055] The high-side half-bridge unit includes a first high-side switch S H1 , the second high-voltage side switch S H2 , the first high voltage side capacitor C H1 And the second high voltage side capacitor C H2 , the first high-voltage side switch S H1 The drain of the first high-voltage side capacitor C H1 One end of the battery pack is electrically connected to the other battery pack, and the first high-voltage side switch S H1 The source of the second high-side switch S H2 The drain of the transformer is electrically connected to one end of the secondary winding of the transformer, and the second high-voltage side switch S H2 The source of the second high-voltage side capacitor C H2 One end of the first high voltage side capacitor C H1 The other end of the transformer is connected to the other end of the secondary winding of the transformer and the second high-voltage side capacitor C H2 The other end is electrically connected.

[0056] The low-voltage side half-bridge unit includes a first low-voltage side switch S L1 , the second low voltage side switch S L2 , the third low voltage side switch S L3 , the fourth low voltage side switch S L4 , the first low voltage side capacitor C L1 And the second low voltage side capacitor C L2 , the first low voltage side switch S L1 The source of the second low voltage side switch S L2 The drain of the first low-voltage side switch S L1 The drain and the first low voltage side capacitor C L1 One end of the first low-voltage side capacitor C is electrically connected to the second matrix switch bus 302. L1 The other end is connected to the magnetic device and the second low voltage side capacitor C L2 One end of the second low voltage side capacitor C L2 The other end is connected to the first matrix switch bus 301 and the fourth low-voltage side switch S L4 The source of the fourth low voltage side switch S L4 The drain of the third low-voltage side switch SL3 The drain of the third low-voltage side switch S L3 The source is electrically connected to the magnetic device.

[0057] One end of the magnetic device Ls is connected to the first low voltage side capacitor C L1 The other end of the second low voltage side capacitor C L2 The other end of the magnetic device Ls is electrically connected to one end of the primary winding of the transformer, and the other end of the primary winding of the transformer is electrically connected to the second low-voltage side switch S L2 The drain of the third low-voltage side switch S L3 In addition, Ls can also be realized by the leakage inductance of the transformer.

[0058] The working principle of the half-bridge non-resonant converter is: through the coordinated work of the high and low voltage side half-bridge units and the transformer, high-frequency switching technology and magnetic devices are used to achieve efficient and flexible bidirectional energy transfer. Its main function is to complete the flow of electric energy from the low voltage side port to the high voltage side port and from the high voltage side port to the low voltage side port, combined with the electrical isolation characteristics, so as to realize the energy transmission between the balancing modules of different groups of battery packs and provide the voltage balancing function for the battery cells.

[0059] In an optional implementation of this embodiment, the low-voltage side bidirectional switch (S L1 and S L2 Composed of one, S L3 and S L4 The low-voltage side bidirectional switch can be realized by a common source MOS tube or a common drain MOS tube. The specific implementation of the low-voltage side bidirectional switch needs to be considered in combination with the actual voltage and current requirements and application scenarios. In addition, when a common source MOS tube or a common drain MOS tube is used, one pair of tubes can be constantly turned on to reduce switching losses.

[0060] At the same time, the battery active balancing circuit controls the direction and size of energy transfer by adjusting the switching frequency, duty cycle or phase shift angle to achieve battery balancing power control. For example, in the half-bridge example 1 ( Figure 6 ), when the input polarity is positive, the second low-voltage side switch S L2 and the fourth low voltage side switch S L4 Constant conduction, the first low-voltage side switch S L1 and the third low voltage side switch S L3 is a high-frequency switch, wherein the first low-voltage side switch S L1 For high-voltage and third low-voltage side switches S L3 When the input polarity is negative, the first low-voltage side switch S L1 and the third low voltage side switch S L3 Constant conduction, the second low-voltage side switch S L2 and the fourth low voltage side switch SL4 is a high-frequency switch, wherein the fourth low-voltage side switch S L4 For high-voltage and second low-voltage side switches S L2 In this way, no matter what the input polarity is, the working state of both ends of the transformer can be guaranteed to be the same, so that the same set of control parameters can be used to achieve the balance goal.

[0061] See also Figure 7 The bipolar bidirectional isolated DC / DC converter can be a full-bridge type converter, with the low voltage side connected via S L1 To S L8 Four sets of bidirectional switches form a full-bridge structure connected to the matrix switch busbar, and realize energy transfer through Ls and the low-voltage side winding of the transformer. H1 To S H4 Two groups of unipolar switches form a full-bridge switch connected to the other two ends of the battery pack and coupled to the high-voltage side winding of the transformer, thereby realizing bidirectional power flow through switch switching control. Specifically, the full-bridge type converter includes a transformer, a high-voltage side full-bridge unit and a low-voltage side full-bridge unit, the primary winding of the transformer is electrically connected to the low-voltage side full-bridge unit, and the secondary winding of the transformer is electrically connected to the high-voltage side full-bridge unit.

[0062] See also Figure 8 and Fig. 9 The bipolar bidirectional isolated DC / DC converter can be a half-bridge combined with a full-bridge type converter. Figure 8 When the left side is a half bridge and the right side is a full bridge, that is, the low-voltage side adopts a half-bridge structure, S L1 To S L4 With the voltage divider capacitor (C L1 , C L2 ) is connected to the low-voltage side winding of the transformer. The high-voltage side adopts a full-bridge structure, S H1 To S H4 Control the energy transfer of the high voltage side of the transformer and connect it to the other two ends of the battery pack. Fig. 9 When the left side is a full bridge and the right side is a half bridge, the low voltage side adopts a full bridge structure, S L1 To S L8 Control the energy transfer on the low-voltage side of the transformer, and use a half-bridge structure on the high-voltage side. H1 To S H2 With the voltage divider capacitor (C H1 , C H2 The half-bridge combined with full-bridge converter of this embodiment combines the half-bridge with the full-bridge to adapt to different voltage levels and power requirements, and optimizes system performance by combining the low loss of the half-bridge with the high power capability of the full-bridge.

[0063] See also Fig.10The low-voltage side switch in the bipolar bidirectional isolated DC / DC converter can adopt a common-drain bidirectional switch structure, and can also have a half-bridge structure, a full-bridge structure, and a half-bridge and full-bridge combination structure.

[0064] See also Fig.11 The bipolar bidirectional isolated DC / DC converter can be a resonant type converter, and the low voltage side adopts a full-bridge structure, which consists of a switch S L1 To S L8 Composition, connect the resonant capacitor C S 、Magnetic device L s The resonant circuit is between the low voltage side and the transformer, and the series resonant capacitor C S With magnetic device L s The high voltage side uses a full bridge structure, which consists of switch S H1 To S H4 The structure is to connect the high-voltage voltage-dividing capacitor and realize power reception and regulation through the high-voltage side winding of the transformer. The resonant type converter of this embodiment uses a resonant circuit to realize zero voltage switching or zero current switching, significantly reducing switching losses and improving efficiency, and the resonant waveform reduces switching noise and electromagnetic interference, improving the electromagnetic compatibility of the system. In addition, the resonant network can also be distributed on the high-voltage side or on both sides of the transformer at the same time, which will not be repeated here.

[0065] See also Fig.12 In each battery pack balancing module, the number of matrix switches 102 can be two, and they are electrically connected to the series nodes in each battery pack 101 to achieve direct single-to-single energy conversion. At this time, the two sides of the bipolar bidirectional isolated DC / DC converter are consistent with the previous low-voltage side circuit, and can also be easily expanded to full-bridge, resonant and other circuits.

[0066] See also Fig.13 and Fig.14 , can be merged Fig.12Two groups of matrix switches in the same battery pack can also realize the direct cell balancing function between groups. At the same time, the battery cells to be balanced can be balanced by two adjacent bipolar bidirectional isolated DC / DC converters as needed. For example, when a cell B2 in battery pack 2 needs to be balanced, battery pack 1 can select a suitable cell B1 to charge and discharge B2 through bidirectional isolated DC / DC. At the same time, battery pack 3 can also select a suitable cell B3 to charge and discharge B2 through bidirectional isolated DC / DC. That is, the matrix switch control selects specific battery cells (such as B1, B2, B3) in the battery pack to be connected to the bipolar bidirectional isolated DC / DC converter, and dynamically selects the cells to be balanced or charged / discharged through the matrix switch, transfers the excess energy from the high-voltage cell to the low-voltage cell, completes the voltage balance within the module or between modules, and realizes the energy transfer between cells or modules.

[0067] A second aspect of the present invention provides a power supply, comprising a device body and the battery active balancing circuit as described in the first aspect.

[0068] The battery active balancing circuit and power supply of the present invention, through the cascaded battery pack balancing module, when a battery pack has a target battery cell with energy lower than or higher than a preset energy threshold, combines the coordinated work of the matrix switch and the bipolar bidirectional isolated DC / DC converter to establish an energy transmission channel adapted to the target battery cell, and the bipolar bidirectional isolated DC / DC converter transmits the energy in another battery pack to the target battery cell through the energy transmission channel, and transmits the energy of the target battery cell to the entire group of another battery pack through the energy transmission channel, thereby realizing accurate energy compensation of the target battery cell in the battery pack (inter-group balancing between battery pack balancing modules of different groups), and improving the active balancing effect of the battery. In addition, the bipolar bidirectional isolated DC / DC converter of the present invention can handle positive and negative polarity voltages, reduce the number of matrix switch tubes, avoid the use of polarity switching circuits, and reduce system costs; and, only the high and low frequency states of the low-voltage side switch tube need to be reasonably switched, and the same set of control algorithms are used, which is simple to control. It can be seen that the circuit structure simplifies the control logic and reduces the overall cost while improving the balancing speed and balancing effect.

[0069] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0070] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A battery active balancing circuit, characterized in that: The battery active balancing circuit includes a plurality of battery pack balancing modules in a cascade relationship; Each of the battery pack balancing modules includes a battery pack, a matrix switch and a bipolar bidirectional isolated DC / DC converter, wherein the battery pack includes a plurality of battery cells that are in a series relationship and form series nodes at both ends; The first series node of each battery cell is electrically connected to one end of a bidirectional switch in the matrix switch, the second series node of each battery cell is electrically connected to one end of another bidirectional switch in the matrix switch, the other end of one bidirectional switch is electrically connected to the first end of the low-voltage side port of the bipolar bidirectional isolated DC / DC converter and the first matrix switch bus at the same time, the other end of the other bidirectional switch is electrically connected to the second matrix switch bus and the second end of the low-voltage side port of the bipolar bidirectional isolated DC / DC converter, and the high-voltage side port of the bipolar bidirectional isolated DC / DC converter is electrically connected to two ends of the next battery pack; Wherein, when there is a target battery cell with energy lower than a preset energy threshold in one of the battery packs in the battery active balancing circuit, the matrix switch is used to perform a corresponding on or off state according to the received balancing control signal to establish an energy transmission channel, and the bipolar bidirectional isolated DC / DC converter is used to transmit the energy in another battery pack to the target battery cell through the energy transmission channel; When there is a target battery cell with energy higher than a preset energy threshold in one of the battery packs in the battery active balancing circuit, the energy of the target battery cell is transmitted to another battery pack through the energy transmission channel.

2. The battery active balancing circuit as claimed in claim 1, characterized in that: The bipolar bidirectional isolated DC / DC converter is one of a dual half-bridge type converter, a dual full-bridge type converter, a half-bridge combined with a full-bridge type converter, a resonant type converter, and a non-resonant type converter.

3. The battery active balancing circuit as claimed in claim 1, characterized in that: The low voltage side of the bipolar bidirectional isolated DC / DC converter is used to receive voltage signals of both positive and negative polarities, and the high voltage side is used to receive voltage signals of positive polarity, thereby realizing bidirectional energy transmission.

4. The battery active balancing circuit as claimed in claim 1, characterized in that: The bipolar bidirectional isolated DC / DC converter comprises a bipolar bridge circuit on the low voltage side, a transformer and a unipolar bridge circuit on the high voltage side, the primary winding of the transformer is electrically connected to the midpoint of the bipolar bridge circuit on the low voltage side, and the secondary winding of the transformer is electrically connected to the midpoint of the unipolar bridge circuit on the high voltage side; The DC end of the bipolar bridge circuit on the low voltage side is electrically connected to the matrix switch bus, and the DC end of the unipolar bridge circuit on the high voltage side is electrically connected to two ends of another battery pack.

5. The battery active balancing circuit as claimed in claim 4, characterized in that: The bipolar bidirectional isolated DC / DC converter further includes a first LC network and a second LC network, the primary winding of the transformer is electrically connected to the midpoint of the low-voltage side bipolar bridge circuit via the first LC network, and the secondary winding of the transformer is electrically connected to the midpoint of the high-voltage side unipolar bridge circuit via the second LC network; The first LC network and the second LC network are respectively a single inductor, a single capacitor, or a combination of an inductor and a capacitor, and the inductor is an independent inductor or a transformer leakage inductor.

6. The battery active balancing circuit as claimed in claim 1, characterized in that: The bipolar bidirectional isolated DC / DC converter comprises a transformer, a high-voltage side half-bridge unit and a low-voltage side half-bridge unit, the primary winding of the transformer is electrically connected to the low-voltage side half-bridge unit, and the secondary winding of the transformer is electrically connected to the high-voltage side half-bridge unit; Alternatively, the bipolar bidirectional isolated DC / DC converter comprises a transformer, a high-voltage side full-bridge unit and a low-voltage side full-bridge unit, the primary winding of the transformer is electrically connected to the low-voltage side full-bridge unit, and the secondary winding of the transformer is electrically connected to the high-voltage side full-bridge unit; Alternatively, the bipolar bidirectional isolated DC / DC converter comprises a transformer, a high-voltage side full-bridge unit and a low-voltage side half-bridge unit, the primary winding of the transformer is electrically connected to the low-voltage side half-bridge unit, and the secondary winding of the transformer is electrically connected to the high-voltage side full-bridge unit; Alternatively, the bipolar bidirectional isolated DC / DC converter comprises a transformer, a high-voltage side half-bridge unit and a low-voltage side full-bridge unit, the primary winding of the transformer is electrically connected to the low-voltage side full-bridge unit, and the secondary winding of the transformer is electrically connected to the high-voltage side half-bridge unit; Alternatively, the bipolar bidirectional isolated DC / DC converter includes a transformer, a high-voltage side full-bridge unit, a low-voltage side full-bridge unit and a resonant capacitor, the primary winding of the transformer is electrically connected to the low-voltage side full-bridge unit via the resonant capacitor, and the secondary winding of the transformer is electrically connected to the high-voltage side full-bridge unit.

7. The battery active balancing circuit as claimed in claim 1, characterized in that: The battery active balancing circuit also includes a first wire and a second wire, and the first wire and the second wire are used to connect the output end of the last battery group balancing module in all battery group balancing modules to the two ends of the battery group of the first battery group balancing module to form a ring network energy transmission path.

8. The battery active balancing circuit as claimed in claim 1, characterized in that: The battery active balancing circuit controls the direction and size of energy transmission by adjusting the switching frequency, duty cycle or phase shift angle to achieve control of battery balancing power; Among them, if the bipolar bidirectional isolated DC / DC converter includes a transformer, a high-voltage side half-bridge unit and a low-voltage side half-bridge unit, when the low-voltage side matrix switch bus voltage is positive, the second low-voltage side switch SL2 and the fourth low-voltage side switch SL4 are constantly turned on, and the first low-voltage side switch SL1 and the third low-voltage side switch SL3 are complementarily turned on; when the low-voltage side matrix switch bus voltage is negative, the first low-voltage side switch SL1 and the third low-voltage side switch SL3 are constantly turned on, and the second low-voltage side switch SL2 and the fourth low-voltage side switch SL4 are complementarily turned on.

9. The battery active balancing circuit as claimed in claim 1, characterized in that: The bidirectional switch is one of a common source MOS tube, a common drain MOS tube, and a relay.

10. A power supply, characterized in that: The device comprises a device body and a battery active balancing circuit as claimed in any one of claims 1 to 9.

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