Battery management circuit and battery system
By introducing voltage clamping and active balancing circuits into the battery management circuit, the problem of contactor closure under load is solved, achieving safe closure and balancing of the battery branch and extending battery life.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SUZHOU INOSA UNITED POWER SYST CO LTD
- Filing Date
- 2025-04-11
- Publication Date
- 2026-05-19
AI Technical Summary
In existing battery management topologies, when a contactor closes under load, an electric arc is generated due to the voltage difference between branches, which affects the contactor's lifespan and leads to battery management failure and system malfunction.
The battery management circuit design employs multiple main switches, branch switch modules, precharge switch modules, and precharge resistors. A voltage clamping circuit is formed by connecting the branch switch modules in parallel to prevent the main switches from closing under load, and active balancing is achieved between battery packs through an active balancing circuit.
To prevent arcing in the main switch, extend the lifespan of components, ensure consistency in battery circuits, extend battery life, and ensure stable operation of the battery system.
Smart Images
Figure CN224264095U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of battery management technology, and in particular to a battery management circuit and battery system. Background Technology
[0002] In related technologies, the typical battery topology is that one battery pack corresponds to one battery branch, and the battery branches are short-circuited and connected in parallel to passively share current among the batteries. To achieve further battery management, a contactor is usually connected to each branch to isolate the batteries in each branch from the BMS (Battery Management System). When power is needed, the contactor can be closed directly. However, in this battery management topology, closing the contactor carries the risk of closing under load due to the voltage difference between the branches. The arc generated during this load-bearing closure can affect the contactor's lifespan, potentially leading to battery management failure or even battery system malfunction. Utility Model Content
[0003] The main purpose of this application is to provide a battery management circuit and battery system, which aims to solve the technical problem in the related art that the contactor of the battery branch needs to withstand the branch voltage difference to close under load, causing the contactor to arc when closing and affecting the contactor life.
[0004] To achieve the above objectives, this application proposes a battery management circuit connected between a battery pack and a power distribution circuit. The battery pack includes multiple battery packs, and the battery management circuit includes multiple main switches and multiple branch switch modules corresponding to the number of battery packs, as well as a precharge switch module and a precharge resistor.
[0005] The positive terminals of multiple battery packs are respectively connected to one end of multiple main switches and one end of multiple branch switch modules. The other end of each branch switch module is connected to one end of a precharge switch module. The other end of the precharge switch module is connected to one end of a precharge resistor. The other ends of multiple main switches and the other ends of the precharge resistor are respectively connected to the power distribution circuit.
[0006] Specifically, a voltage clamping circuit is formed by connecting each branch switch module in parallel to clamp the voltage at the front end of each corresponding main switch to the same potential; and an active balancing circuit is formed by the main switch, pre-charge resistor, pre-charge switch module, and each branch switch module to achieve active balancing between any at least two battery packs.
[0007] In one embodiment, the battery management circuit further includes a control module; the control terminals of multiple main switches, multiple branch switch modules, and / or the precharge switch module are respectively connected to the control module.
[0008] In one embodiment, each branch switch module includes a first power transistor and a second power transistor; the first end of the first power transistor is connected to the positive terminal of the battery pack, the second end of the first power transistor is connected to the second end of the second power transistor, the first end of the second power transistor is connected to one end of the precharge switch module, and the third ends of the first power transistor and the second power transistor are respectively connected to the control module.
[0009] In one embodiment, the first power transistor and the second power transistor are any one of a field-effect transistor, an insulated-gate bipolar transistor, or a power semiconductor switch.
[0010] In one embodiment, the precharge switch module includes a third power transistor and a fourth power transistor; the first end of the third power transistor is connected to the other end of a plurality of branch switch modules, the second end of the third power transistor is connected to the second end of the fourth power transistor, the first end of the fourth power transistor is connected to one end of the precharge resistor, and the third ends of the third power transistor and the third ends of the fourth power transistor are respectively connected to the control module.
[0011] In one embodiment, the main switch is a first contactor; one end of the first contactor is connected to the positive terminal of the battery pack, and the other end of the first contactor is connected to the power distribution circuit.
[0012] In one embodiment, each branch switch module includes a second contactor; one end of the second contactor is connected to the positive terminal of the battery pack, and the other end of the second contactor is connected to one end of the precharge switch module.
[0013] In one embodiment, the precharge switch module includes a third contactor; one end of the third contactor is connected to the other end of a plurality of branch switch modules, and the other end of the third contactor is connected to one end of a precharge resistor.
[0014] In one embodiment, the power distribution circuit includes a power distribution unit, a battery energy distribution unit, or an all-in-one controller.
[0015] To achieve the above objectives, this application also proposes a battery system including a battery pack, a battery management circuit as described above, and a power distribution circuit, wherein the battery management circuit is connected between the battery pack and the power distribution circuit.
[0016] One or more technical solutions proposed in this application have at least the following technical effects:
[0017] A battery management circuit is proposed, comprising multiple main switches and multiple branch switch modules corresponding to the number of battery packs, as well as a precharge switch module and a precharge resistor. The positive terminals of the multiple battery packs are connected to one end of each of the main switches and one end of each of the branch switch modules. The other end of each branch switch module is connected to one end of the precharge switch module, and the other end of the precharge switch module is connected to one end of the precharge resistor. The other ends of the main switches and the precharge resistor are connected to the power distribution circuit, forming the circuit topology. When the system is powered on, the parallel connection of the branch switch modules forms a voltage clamping loop, clamping the voltage at the front end of each corresponding main switch to the same potential. This avoids main switch closure under load due to branch voltage differences, prevents arcing during main switch closure, and increases device lifespan. Furthermore, the main switches, precharge resistor, precharge switch module, and branch switch modules form an active balancing loop, achieving active balancing between any two battery packs. This enables small-current balancing, ensures consistency across battery branches, and extends battery life. Attached Figure Description
[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.
[0019] To more clearly illustrate the technical solutions in the embodiments or related technologies of this application, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.
[0020] Figure 1 This refers to the battery management topology in related technologies;
[0021] Figure 2 This is a connection diagram of an embodiment of the battery management circuit of this application;
[0022] Figure 3 This is a schematic diagram of the circuit topology of another embodiment of the battery management circuit of this application;
[0023] Figure 4 This is a schematic diagram of the circuit topology of another embodiment of the battery management circuit of this application.
[0024] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation
[0025] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.
[0026] It should be noted that if the embodiments of this application involve directional indications (such as up, down, left, right, front, back, etc.), these directional indications are only used to explain the relative positional relationships and movement of the components in a specific posture. If the specific posture changes, the directional indications will also change accordingly. Furthermore, if the embodiments of this application involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined with "first" or "second" can explicitly or implicitly include at least one of those features. Additionally, if "and / or" or "and / or" appears throughout the text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or a solution where A and B are simultaneously satisfied. Furthermore, the technical solutions of the various embodiments can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed in this application.
[0027] In related technologies, the battery topology typically involves one battery pack (BP) corresponding to one battery branch. These battery branches are directly connected in parallel to the BMS (Battery Management System), or each battery branch is individually connected to the BMS, and then short-circuited and connected in parallel within the BMS to passively share current among the batteries. The problem with this battery topology is:
[0028] 1. During operation, the battery pack is continuously passively shared, and the internal cells are continuously in working condition, which will affect battery life and battery consistency.
[0029] 2. The cells in different battery packs are usually not completely identical. In multiple battery branches, if the total voltage of branch A is higher and the voltage of a single cell in branch B is higher, under passive current sharing, if branch A discharges to branch B, it will cause overvoltage of a single cell in branch B.
[0030] 3. As the number of battery branches increases, the overall number of failure points increases. If a single cell fails, the entire battery will fail, causing the vehicle to be unable to continue driving.
[0031] Building upon this, to achieve further battery management, a contactor is typically connected to each branch, such as... Figure 1 The diagram shows a battery management topology in related technologies. Four battery packs, BP1, BP2, BP3, and BP4, are each connected to a contactor, namely KM1, KM2, KM3, and KM4, and then connected in parallel to the BMS. In this topology, the contactors isolate the batteries in each branch from the BMS, and the contactors can be directly closed when power is needed. However, in this battery management topology, when closing the contactors, due to the voltage difference between the branches, there is a risk of the contactors closing under load. The electric arc generated at the moment of closing under load can affect the service life of the contactors.
[0032] To address the aforementioned problems, this application provides a battery management circuit and a battery system. The application and its embodiments will be described below with reference to the accompanying drawings.
[0033] This application proposes a battery management circuit.
[0034] In one embodiment of the battery management circuit, refer to Figure 2 , Figure 2 This is a connection diagram for this embodiment. The battery management circuit can be connected between the battery pack and the power distribution circuit. The battery pack includes multiple battery packs. The battery management circuit can include multiple main switches and multiple branch switch modules corresponding to the number of multiple battery packs, as well as a precharge switch module and a precharge resistor.
[0035] The positive terminals of multiple battery packs are respectively connected to one end of multiple main switches and one end of multiple branch switch modules. The other end of each branch switch module is connected to one end of a precharge switch module. The other end of the precharge switch module is connected to one end of a precharge resistor. The other ends of the multiple main switches and the other ends of the precharge resistor are respectively connected to the power distribution circuit.
[0036] Specifically, a voltage clamping circuit is formed by connecting each branch switch module in parallel to clamp the voltage at the front end of each corresponding main switch to the same potential; and an active balancing circuit is formed by the main switch, pre-charge resistor, pre-charge switch module, and each branch switch module to achieve active balancing between any at least two battery packs.
[0037] It should be noted that this battery management circuit can be applied to a battery system, which can be the system corresponding to the high-voltage battery in a new energy vehicle. The battery pack can be a high-voltage battery pack comprising multiple battery packs, each of which can include multiple individual cells connected in series. Each battery pack has a corresponding battery branch, specifically including one main branch and one additional branch. The main branch includes a main switch, and the additional branch includes a branch switch module. One end of the main switch and one end of the branch switch module are connected in parallel, serving as an input terminal of the battery management circuit. Each input terminal is connected to the positive terminal of each battery pack. The other ends of the main switches in each main branch are connected in parallel, and the other ends of the branch switch modules in each additional branch are also connected in parallel. The parallel connection points of the other ends of all branch switch modules are connected to the parallel connection points of the other ends of all main switches through a pre-charge switch module and a pre-charge resistor, serving as the output terminal of the battery management circuit, connected to the subsequent power distribution circuit. The number of main switches and the number of branch switch modules correspond to the number of battery packs in the battery pack, specifically, they can be greater than or equal to two. Figure 2 As shown, n (n≥2) battery packs are equipped with n main switches and n branch switch modules.
[0038] Additionally, it should be noted that the main switch, branch switch module, and precharge switch module can be manually controlled to turn on or off by the user, or automatically controlled to turn on or off by an external control board or a separate control module within the circuit. Clamping refers to a measure that limits the potential at a certain point to a specified potential; active balancing refers to a technology that ensures battery pack consistency by actively adjusting the charge levels of each battery pack.
[0039] In the specific implementation process, during the system power-on process, specifically before the main switch is turned on, each branch switch module can be turned on, so that each branch switch module is connected in parallel to form a voltage clamping circuit. Through this voltage clamping circuit, the voltage at the front end of each corresponding main switch can be clamped to the same potential. Therefore, when the main switch is closed after pre-charging, there will be no branch voltage difference problem, ensuring the safe closing of the main switch. When the system requires active balancing, such as when two battery packs with different total voltages need to be actively balanced, assuming the high-capacity battery pack is the balancing battery pack and the low-capacity battery pack is the target battery pack, the main switch in the battery branch corresponding to the balancing battery pack and the branch switch module in the battery branch corresponding to the target battery pack can be activated. This allows the main switch, pre-charge resistor, pre-charge switch module of the balancing battery pack, and the branch switch module of the target battery pack to form an active balancing loop. Through this active balancing loop, excess energy from the high-capacity battery pack can be transferred to the low-capacity battery pack, thus achieving active balancing between the balancing battery pack and the target battery pack. Optionally, there can be multiple target battery packs. An active balancing loop can be formed by the main switch, pre-charge resistor, pre-charge switch module of the balancing battery pack, and the branch switch modules of each target battery pack. This active balancing loop can achieve active balancing between the balancing battery pack and multiple target battery packs, ensuring consistency among the multiple battery packs.
[0040] The battery management circuit provided in this embodiment includes multiple main switches and multiple branch switch modules corresponding to the number of battery packs, as well as a precharge switch module and a precharge resistor. The positive terminals of the multiple battery packs are respectively connected to one end of each of the main switches and one end of each of the branch switch modules. The other end of each branch switch module is connected to one end of the precharge switch module, and the other end of the precharge switch module is connected to one end of the precharge resistor. The other ends of the main switches and the precharge resistor are respectively connected to the power distribution circuit, forming a circuit topology. When the system is powered on, the parallel connection of the branch switch modules forms a voltage clamping loop, clamping the voltage at the front end of each corresponding main switch to the same potential. This avoids main switch closure under load caused by branch voltage differences, prevents arcing during main switch closure, and increases device lifespan. Furthermore, the main switches, precharge resistor, precharge switch module, and branch switch modules form an active balancing loop, achieving active balancing between any two battery packs. This enables small-current balancing, ensures consistency across battery branches, and extends battery life.
[0041] In one feasible implementation, the battery management circuit may further include a control module; the control terminals of multiple main switches, multiple branch switch modules, and / or the control terminal of the precharge switch module are respectively connected to the control module.
[0042] It should be noted that the control module can be an independently set controller or a controller in the back-end power distribution circuit, in order to simplify the circuit structure and save hardware size. The control module's on / off control of the main switch, branch switch module, and precharge switch module can be configured according to the specific device selection of the above modules. For example, when the switching device is a high- or low-level driven switching transistor, the control module outputs a high- or low-level signal; when the switching device is a pulse signal driven power transistor, the control module outputs a corresponding pulse control signal. In practical applications, the appropriate method can be selected as needed, and no specific limitation is made here.
[0043] In this embodiment, the control module automatically controls the on / off state of the main switch, branch switch module and precharge switch module. It can specifically implement battery management according to the instructions issued by the vehicle's main control, including switching between different working states or different working stages in each working state, thereby realizing a specific control process according to actual needs.
[0044] In one feasible implementation, the main switch is a first contactor; one end of the first contactor is connected to the positive terminal of the battery pack, and the other end of the first contactor is connected to the power distribution circuit.
[0045] It should be noted that the main switch uses a contactor, which can be manually controlled or automatically controlled by the control module; no specific limitation is made here. In each battery branch, the first contactor serves as the switching device of the main branch. One end is connected to the positive terminal of the corresponding battery pack, and the other end is connected in parallel with the other end of the first contactor in other battery branches, and in parallel with the other end of the pre-charge resistor. Together, they serve as the output terminal of the battery management circuit, which is connected to the subsequent power distribution circuit.
[0046] In this embodiment, the battery pack is isolated from the power distribution circuit by the first contactor, and when the battery pack needs to be powered on, the first contactor enables rapid conduction, connecting the main branch in the battery branch of the battery pack. After the battery pack provides the corresponding working voltage, the power distribution circuit performs subsequent power distribution control.
[0047] In one feasible implementation, the power distribution circuit includes a power distribution unit, a battery energy distribution unit, or an all-in-one controller.
[0048] It should be noted that the power distribution circuit may include a power distribution unit (PDU), a battery energy distribution unit (BDU), or a multi-functional controller. In practical applications, the appropriate option can be selected as needed; no specific limitation is made here. Preferably, the control module can be integrated with the controller within the power distribution circuit to save control board size and avoid the circuit occupying too much battery space.
[0049] In another embodiment of the battery management circuit, refer to Figure 3 , Figure 3 The circuit topology diagram of this embodiment is shown. Each branch switch module may include a first power transistor and a second power transistor. The first end of the first power transistor is connected to the positive terminal of the battery pack, the second end of the first power transistor is connected to the second end of the second power transistor, the first end of the second power transistor is connected to one end of the precharge switch module, and the third ends of the first power transistor and the second power transistor are respectively connected to the control module.
[0050] The first power transistor and the second power transistor can be any one of a field-effect transistor, an insulated-gate bipolar transistor, or a power semiconductor switch.
[0051] For example, field-effect transistors such as MOS (Metal-Oxide-Semiconductor Field-Effect Transistor) and JFET (Junction Field-Effect Transistor) can be used, as well as power devices with body diodes such as IGBT (Insulated Gate Bipolar Transistor) or power semiconductor switches (such as gallium nitride power semiconductors, silicon carbide power devices, etc.). The appropriate device can be selected according to the needs of the application, and no specific limitation is made here.
[0052] In this embodiment, the collector of the first power transistor is connected to the positive terminal of the battery pack, the emitter of the first power transistor is connected to the emitter of the second power transistor, the collector of the second power transistor is connected to one end of the precharge switch module, and the gates of the first power transistor and the second power transistor are respectively connected to the control module.
[0053] It should be noted that both the first and second power transistors are power devices with body diodes. By utilizing the unidirectional flow characteristics of the power devices and the body diodes, the current in the newly added branch where the branch switch module formed by the symmetrical connection of the two power transistors is located can flow bidirectionally, or the current flow direction can be selected according to actual needs. This enables the branch switch module to have a voltage clamping function, thereby eliminating the voltage difference at the front end of the main switch in the corresponding battery branch of each battery pack and preventing the main switch from closing under load.
[0054] Understandably, before the main switch closes, the voltage at the front end of the main switch can be clamped to the same potential through the new branch formed by the first and second power transistors, solving the problem of the main switch closing under load. Simultaneously, this new branch can actively balance the voltage between branches after charging is complete and in the system's non-operating state, ensuring the consistency of the battery branches. Furthermore, since the battery branches corresponding to each battery pack are relatively independent, if the main branch or the new branch of a single battery branch fails, only the failed battery branch can be disconnected, including disconnecting both the main branch and the new branch. At this time, the remaining battery packs and their corresponding battery branches can operate normally, thus ensuring that the vehicle can continue to be driven to a repair shop, reducing fault handling costs. Moreover, when the battery needs active balancing, this battery management circuit can actively perform small-current balancing across multiple branches, ensuring the consistency of each battery branch and extending battery life.
[0055] In one feasible implementation, such as Figure 3 As shown, the precharge switch module may include a third contactor; one end of the third contactor is connected to the other end of the multiple branch switch modules, and the other end of the third contactor is connected to one end of the precharge resistor.
[0056] It should be noted that the precharge switch module uses a contactor, which can be manually controlled or automatically controlled by the control module; no specific limitation is made here. One end of the third contactor is connected in parallel to the other end of the branch switch module in the newly added branch corresponding to multiple battery packs, and the other end is connected to one end of the precharge resistor.
[0057] In another feasible implementation, the precharge switch module may include a third power transistor and a fourth power transistor; the first end of the third power transistor is connected to the other end of a plurality of branch switch modules, the second end of the third power transistor is connected to the second end of the fourth power transistor, the first end of the fourth power transistor is connected to one end of the precharge resistor, and the third ends of the third power transistor and the third ends of the fourth power transistor are respectively connected to the control module. A detailed description of this implementation can be found in subsequent embodiments, and will not be described in detail here.
[0058] For example, the collector of the third power transistor is connected to the other end of the multiple branch switch modules, the emitter of the third power transistor is connected to the emitter of the fourth power transistor, the collector of the fourth power transistor is connected to one end of the pre-charge resistor, and the gates of the third power transistor and the fourth power transistor are respectively connected to the control module.
[0059] To better illustrate the specific working process of this battery management circuit, a concrete application example is provided below, such as... Figure 3As shown, the battery pack includes four battery packs BP1-BP4. Battery branch 1 of battery pack BP1 includes a main switch 1 and a branch switch module 1. The main switch 1 includes a contactor KM11, and the branch switch module 1 includes IGBTs Q11 and Q12. The positive terminal BP1+ of battery pack BP1 is connected to one end of KM11 and the collector of Q11, and the emitter of Q11 is connected to the emitter of Q12. Battery branch 2 of battery pack BP2 includes a contactor KM12 and IGBTs Q21 and Q22. Battery branch 3 of battery pack BP3 includes a contactor KM13 and IGBTs Q31 and Q32. Battery branch 4 of battery pack BP4 includes a contactor KM14 and IGBTs Q41 and Q42. The specific connection relationship is similar to that of battery branch 1, and will not be described again here. The precharge switch module includes contactor KM20. The collectors of Q12, Q22, Q32 and Q42 are all connected to one end of KM20. The other end of KM20 is connected to one end of the precharge resistor R1. The other ends of KM11-KM14 and the other end of R1 are connected to the power distribution circuit, which uses a BDU.
[0060] Based on the specific application examples above, the operating states and corresponding working processes of this battery management circuit are as follows:
[0061] When the BDU is not in operation, KM11-KM14, Q11-Q41, and Q12-Q42 are all disconnected, physically disconnecting the four battery branches. This physical disconnection method prevents passive equalization between batteries, protecting the batteries from reduced lifespan due to continuous passive equalization. It also prevents the risk of fire caused by excessively high voltage in a single cell within a battery pack due to passive equalization between two battery branches. Furthermore, if a battery branch malfunctions, this method can be used to disconnect that branch and use the remaining battery branches and the corresponding battery pack to power the vehicle to a repair shop.
[0062] When the BDU receives the high-voltage command, it first closes Q11-Q41 and Q12-Q42, while KM20 and KM11-KM14 are open by default. At this time, the unidirectional flow characteristics of Q11-Q41 and Q12-Q42 and their body diodes can be used to clamp the voltage at the front end of KM11-KM14 to the same potential point. Then, KM20 is closed, and the current of each battery pack passes through the corresponding branch switch module and then through KM20 to precharge the pre-charge resistor R1 at the back end. After the pre-charge is completed, KM11-KM14 is closed. This closing action will not cause branch voltage difference problems. Finally, Q11-Q41, Q12-Q42 and KM20 are opened, and each battery pack is energized through the corresponding relay closed on the main branch, thereby completing the high-voltage connection of the system.
[0063] When the BDU receives an active balancing command, assuming that battery branch 1 needs to balance battery branch 2, firstly, Q11, Q12, and KM20 are closed. Then, the current of BP1+ flows through the body diodes of Q11 and Q12 and KM20 in sequence to precharge the pre-charge resistor R1. After the pre-charge is completed, KM11 in battery branch 1 is closed to power on battery branch 1. Then, Q11 and Q12 are opened, and Q21 and Q22 are closed, so that the current of BP1 flows through the body diodes of KM11, R1, KM20, Q22, and Q21 in sequence to slowly balance BP2. KM12 is opened by default.
[0064] The battery management circuit provided in this embodiment specifically offers a multi-branch battery clamping and active balancing circuit. A new branch is added to each battery branch, and clamping and active balancing are achieved through two symmetrically connected power transistors. Before the pre-charge resistor, a contactor or two symmetrically connected power transistors are used to control the pre-charge switch. This allows the battery management circuit to achieve normal operation and state switching under different working conditions, as well as normal operation and switching between different working stages under each working condition. This ensures the comprehensive functionality of the battery management circuit and can adapt to different scenario needs.
[0065] In yet another embodiment of the battery management circuit, refer to Figure 4 , Figure 4 The circuit topology diagram of this embodiment shows that each branch switch module may include a second contactor; one end of the second contactor is connected to the positive terminal of the battery pack, and the other end of the second contactor is connected to one end of the precharge switch module.
[0066] It should be noted that the second contactor can be an anti-adhesion contactor. When the contactor is closed, the current in the newly added branch where the branch switch module is located can flow bidirectionally, or the current flow direction can be selected according to actual needs, so that the branch switch module has a voltage clamping function, thereby eliminating the voltage difference at the front end of the main switch in the battery branch corresponding to each battery pack and preventing the main switch from closing under load.
[0067] Understandably, before the main switch is closed, the voltage at the front end of the main switch can be clamped to the same potential by the second contactor, thus solving the problem of the main switch closing under load. At the same time, the second contactor can actively balance the voltage between branches after charging is completed and when the system is not in operation, ensuring the consistency of the battery branches.
[0068] In one feasible implementation, such as Figure 4As shown, the precharge switch module may include a third power transistor and a fourth power transistor; the first end of the third power transistor is connected to the other end of multiple branch switch modules, the second end of the third power transistor is connected to the second end of the fourth power transistor, the first end of the fourth power transistor is connected to one end of the precharge resistor, and the third end of the third power transistor and the third end of the fourth power transistor are respectively connected to the control module.
[0069] The third and fourth power transistors can be any one of field-effect transistors, insulated-gate bipolar transistors, or power semiconductor switches.
[0070] For example, controllable switching transistors such as transistors, MOSFETs, JFETs, IGBTs, or power semiconductor switches (such as gallium nitride power semiconductors, silicon carbide power devices, etc.) can be used. In practical applications, the appropriate transistor can be selected as needed, and no specific limitation is made here.
[0071] In this embodiment, the collector of the third power transistor is connected to the other end of the multiple branch switch modules, the emitter of the third power transistor is connected to the emitter of the fourth power transistor, the collector of the fourth power transistor is connected to one end of the pre-charge resistor, and the gates of the third power transistor and the fourth power transistor are respectively connected to the control module.
[0072] In another feasible embodiment, the precharge switch module may include a third contactor; one end of the third contactor is connected to the other end of the plurality of branch switch modules, and the other end of the third contactor is connected to one end of the precharge resistor. For a detailed description of this embodiment, please refer to the foregoing embodiments; for the sake of brevity, it will not be repeated here.
[0073] Understandably, compared to the previous embodiment, this embodiment selects a contactor to form the precharge switch module, which can further save on circuit structure and thus simplify the battery system design process; however, the previous embodiment selected two power transistors to form the precharge switch module, which resulted in lower device costs and saved on circuit costs.
[0074] For example, to better illustrate the specific operation of this battery management circuit, a specific application example is provided below, such as... Figure 4As shown, the battery pack includes four battery packs BP1-BP4. Battery branch 1 of battery pack BP1 includes a main switch 1 and a branch switch module 1. The main switch 1 includes a contactor KM11, and the branch switch module 1 includes a contactor KM21. The positive terminal BP1+ of battery pack BP1 is connected to one end of KM11 and one end of KM21. Battery branch 2 of battery pack BP2 includes contactors KM12 and KM22. Battery branch 3 of battery pack BP3 includes contactors KM13 and KM23. Battery branch 4 of battery pack BP4 includes contactors KM14 and KM24. The specific connection relationship is similar to that of battery branch 1, and will not be described again here. The precharge switch module includes IGBT transistors Q01 and Q02. The other ends of KM21-KM24 are all connected to the collector of Q01. The emitter of Q01 is connected to the emitter of Q02. The collector of Q02 is connected to one end of the precharge resistor R1. The other ends of KM11-KM14 and the other end of R1 are connected to the power distribution circuit, which uses a BDU.
[0075] Based on the specific application examples above, the operating states and corresponding working processes of this battery management circuit are as follows:
[0076] When the BDU is not working, KM11-KM14 and KM21-KM24 are all disconnected, physically disconnecting the four battery branches. This physical disconnection method has the same effect as the physical disconnection method in the specific application example provided in the previous embodiment, and will not be described again here.
[0077] When the BDU receives the high-voltage command, it first closes KM21-KM24, while Q01, Q02, and KM11-KM14 are all open by default. At this time, KM21-KM24 can be used to clamp the voltage at the front end of KM11-KM14 to the same potential point. Then, Q01 and Q02 are closed, and the current of each battery pack passes through the corresponding branch switch module and then through the body diodes of Q01 and Q02 to precharge the pre-charge resistor R1 at the back end. After the pre-charge is completed, KM11-KM14 is closed. This closing action will not cause branch voltage difference problems. Finally, KM21-KM24, Q01, and Q02 are opened, and each battery pack is powered on through the corresponding relay closed on the main branch, thereby completing the high-voltage connection of the system.
[0078] When the BDU receives an active balancing command, assuming that battery branch 1 needs to balance battery branch 2, firstly, KM21, Q01, and Q02 are closed. Then, the current of BP1+ flows through the body diodes of KM21, Q01, and Q2 in sequence to precharge the pre-charge resistor R1. After the pre-charge is completed, KM11 in battery branch 1 is closed to power on battery branch 1. Then, KM21 is opened and KM22 is closed, so that the current of BP1 flows through the body diodes of KM11, R1, Q02, and Q01 in sequence, and KM22 to slowly balance BP2. KM12 is opened by default.
[0079] The battery management circuit provided in this embodiment specifically offers another multi-branch battery clamping and active balancing circuit. A new branch is added to each battery branch, using a contactor to achieve clamping and active balancing. Before the pre-charge resistor, a contactor or two symmetrically connected power transistors are used to implement pre-charge switch control. This allows the battery management circuit to achieve normal operation and state switching under different operating conditions, as well as normal operation and switching between different stages within each operating state, ensuring the comprehensive functionality of the battery management circuit and adapting to different scenarios. Compared to the previous embodiment, this embodiment selects a contactor to construct the branch switch module, further saving circuit structure and simplifying the battery system design process; however, the previous embodiment selected two power transistors to construct the branch switch module, resulting in lower component costs and reduced circuit costs.
[0080] This application also proposes a battery system.
[0081] In one embodiment of the battery system, the battery system may include a battery pack, a battery management circuit, and a power distribution circuit, with the battery management circuit connected between the battery pack and the power distribution circuit.
[0082] The battery pack includes multiple battery packs, and the power distribution circuit includes any one of a power distribution unit, a battery energy distribution unit, or an all-in-one controller.
[0083] It should be noted that the specific structure of the battery management circuit can be referred to the above embodiments. Since the battery system adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be elaborated here.
[0084] The above are only some embodiments of this application and do not limit the patent scope of this application. All equivalent structural transformations made under the technical concept of this application and using the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included in the patent protection scope of this application.
Claims
1. A battery management circuit, characterized in that, Connected between the battery pack and the power distribution circuit, the battery pack includes multiple battery packs, and the battery management circuit includes multiple main switches and multiple branch switch modules corresponding to the number of the multiple battery packs, as well as a precharge switch module and a precharge resistor; The positive terminals of the plurality of battery packs are respectively connected to one end of the plurality of main switches and one end of the plurality of branch switch modules. The other end of each of the plurality of branch switch modules is connected to one end of the precharge switch module. The other end of the precharge switch module is connected to one end of the precharge resistor. The other end of the plurality of main switches and the other end of the precharge resistor are respectively connected to the power distribution circuit. Specifically, a voltage clamping circuit is formed by connecting each of the branch switch modules in parallel to clamp the voltage at the front end of each of the corresponding main switches to the same potential; and an active balancing circuit is formed by the main switches, the pre-charge resistor, the pre-charge switch module, and each of the branch switch modules to achieve active balancing between any at least two battery packs.
2. The battery management circuit as described in claim 1, characterized in that, The battery management circuit also includes a control module; The control terminals of the multiple main switches, the multiple branch switch modules, and / or the precharge switch module are respectively connected to the control module.
3. The battery management circuit as described in claim 2, characterized in that, Each of the branch switch modules includes a first power transistor and a second power transistor; The first end of the first power transistor is connected to the positive terminal of the battery pack, the second end of the first power transistor is connected to the second end of the second power transistor, the first end of the second power transistor is connected to one end of the precharge switch module, and the third ends of the first power transistor and the third ends of the second power transistor are respectively connected to the control module.
4. The battery management circuit as described in claim 3, characterized in that, The first power transistor and the second power transistor are any one of field-effect transistors, insulated-gate bipolar transistors, or power semiconductor switches.
5. The battery management circuit as described in claim 2, characterized in that, The precharge switch module includes a third power transistor and a fourth power transistor; The first end of the third power transistor is connected to the other end of the plurality of branch switch modules, the second end of the third power transistor is connected to the second end of the fourth power transistor, the first end of the fourth power transistor is connected to one end of the pre-charge resistor, and the third ends of the third power transistor and the third ends of the fourth power transistor are respectively connected to the control module.
6. The battery management circuit as described in any one of claims 1 to 5, characterized in that, The main switch is a first contactor; One end of the first contactor is connected to the positive terminal of the battery pack, and the other end of the first contactor is connected to the power distribution circuit.
7. The battery management circuit as described in any one of claims 1 to 5, characterized in that, Each of the branch switch modules includes a second contactor; One end of the second contactor is connected to the positive terminal of the battery pack, and the other end of the second contactor is connected to one end of the precharge switch module.
8. The battery management circuit as described in any one of claims 1 to 5, characterized in that, The precharge switch module includes a third contactor; One end of the third contactor is connected to the other end of the plurality of branch switch modules, and the other end of the third contactor is connected to one end of the pre-charge resistor.
9. The battery management circuit as described in any one of claims 1 to 5, characterized in that, The power distribution circuit includes a power distribution unit, a battery energy distribution unit, or an all-in-one controller.
10. A battery system, characterized in that, It includes a battery pack, a battery management circuit as described in any one of claims 1 to 9, and a power distribution circuit, wherein the battery management circuit is connected between the battery pack and the power distribution circuit.