Method, circuit and system for driving and balancing a battery pack in a BMS

Abstract

A circuit for driving and balancing a battery pack in a power management system is provided, comprising: a signal acquisition module for acquiring the voltage and temperature of the battery pack; a control module for selecting active balancing and / or passive balancing of the battery pack based on whether the acquired voltage and temperature meet preset conditions, and generating a corresponding balancing drive signal; and a balancing module for actively balancing and / or passively balancing the battery assembly based on the balancing drive signal. Furthermore, a method and system for driving and balancing a battery pack in a power management system are provided. The dual-coupling balancing circuit control strategy of the present invention can realize free switching between active and passive balancing, allowing the battery pack to operate in an optimal temperature range, overcoming the potential risk caused by increased capacity differences of the cells due to temperature differences, enhancing battery utilization, and increasing the service life of the overall battery pack.

Description

Technical Field

[0001] The present invention relates to the field of intelligent control, and more particularly to a method, circuit and system for driving and balancing a battery pack in a battery management system (BMS). Background Art

[0002] Energy crises and environmental pollution have become major challenges facing the world and are key factors hindering global economic development. The development of automobiles has led to significant energy consumption, and vehicle exhaust emissions are a major source of air pollution and a key contributor to widespread smog across the country. Therefore, developing pure electric vehicles is the preferred solution for achieving the current "zero emissions" goal. However, onboard power batteries are not only a technical bottleneck restricting the large-scale development of electric vehicles but also a key factor in their high prices. The development of high-performance battery management systems can more efficiently utilize battery energy and extend battery life.

[0003] Pure electric vehicle power battery packs are composed of hundreds of battery cells. When used in groups, batteries are prone to overcharging and over-discharging, resulting in a decrease in battery capacity and service life. The battery state of charge (SOC) is related to voltage. By monitoring the cell voltage of the battery pack, the battery state of charge can be estimated. During charging and discharging, the battery voltage and temperature within the battery pack must be monitored. Based on the collected data, appropriate control strategies are implemented to maintain voltage consistency across the entire battery pack.

[0004] Compared to many other energy storage systems, lithium-ion batteries offer advantages such as high energy density, long lifespan, and ease of use. They are becoming an increasingly essential energy storage medium in many fields. However, with current lithium-ion battery manufacturing capabilities and processes, subtle differences can occur between individual cells during the production process, creating a consistency issue. These inconsistencies primarily manifest in cell capacity, internal resistance, self-discharge rate, and charge / discharge efficiency. These inconsistencies are transmitted to the battery pack, inevitably leading to a loss in capacity and, consequently, a reduction in battery life.

[0005] Lithium-ion battery packs based on active balancing technology can actively balance the differences between lithium-ion battery cells within the pack, regardless of whether the pack is charging, discharging, or stored. This eliminates various inconsistencies that arise from the pack itself and during use. Therefore, a solution for driving and balancing the battery pack in a battery management system is needed, which can automatically detect and balance the battery voltage while maintaining the temperature within the battery pack within a reasonable range.

[0006] The above information disclosed in this Background section is only for further understanding of the background of the invention and therefore it may contain information that does not constitute the prior art that is already known to a person of ordinary skill in the art. Summary of the Invention

[0007] The present invention provides a method, circuit, and system for driving and balancing a battery pack in a BMS, which solves the potential risk caused by increased capacity differences among cells due to temperature differences, enhances battery utilization, and increases the service life of the entire battery pack.

[0008] To solve the above problems in the prior art, the present invention provides a method, circuit and system for driving and balancing a battery pack in a BMS.

[0009] The first aspect of the present invention provides a circuit for driving and balancing a battery pack in a power management system, comprising: a signal acquisition module for collecting the voltage and temperature of the battery pack; a control module for selecting active balancing and / or passive balancing of the battery pack based on whether the collected voltage and temperature meet preset conditions, and generating a corresponding balancing drive signal; and a balancing module for actively balancing and / or passively balancing the battery assembly based on the balancing drive signal.

[0010] According to an embodiment of the present invention, a single power supply is used to power the circuit.

[0011] According to an embodiment of the present invention, the active balancing and passive balancing are applied to single cells in the battery pack.

[0012] According to one embodiment of the present invention, the balancing module includes: an active and passive balancing unit, a balancing path driving unit, a balancing transformer primary current sampling unit, and a secondary current sampling unit. The active and passive balancing unit is used to perform active and / or passive balancing of the battery pack; the balancing path driving circuit is used to select the battery balancing path in the battery pack according to the balancing drive signal; the balancing transformer primary current sampling unit and the secondary current sampling unit are used to determine the balancing time through current sampling.

[0013] According to one embodiment of the present invention, when balancing single cells in a battery pack, the active and passive balancing unit includes a self-driving unit, a single power driving unit, and a coupled dual balancing unit connected in sequence; the self-driving unit is used to provide a self-driving signal for the balancing module; the single-unit driving unit is used to select the balancing path and the charging and discharging selection in the battery pack; the coupled dual balancing unit is used to perform active balancing and / or passive balancing and battery pack charging and discharging selection according to the balancing driving signal of the control module.

[0014] According to one embodiment of the present invention, the self-driving unit is composed of two back-to-back MOS transistors to prevent misconduction, two protective resistors, two current-limiting resistors, and two triodes; the single-power drive portion includes four MOS transistors for direction selection, as well as protective resistors and voltage-divider resistors; and the coupled dual-balancing unit is composed of an active balancing circuit and a passive balancing circuit, the passive balancing circuit being composed of a discharge resistor and a MOS transistor in series, and the active balancing circuit being composed of a coupling circuit with filtering impact protection.

[0015] According to one embodiment of the present invention, the primary current sampling circuit is connected to a differential operational amplifier through an operational amplifier for isolation, and the output is then connected to a signal processor through the operational amplifier for primary current sampling; the secondary current sampling circuit is directly connected to a signal processor through an operational amplifier for secondary current sampling.

[0016] A second aspect of the present invention provides a method for driving and balancing a battery pack in a power management system, comprising: S1: determining a single cell in the battery pack that needs to be balanced, and comparing the temperature of the single cell with a preset first threshold; S2: when the temperature of the single cell is lower than the first threshold, performing passive balancing, otherwise performing active balancing; S3: when performing passive balancing, detecting the voltage and temperature of the single cell in real time, and when the temperature is higher than the preset first threshold, executing step S4; S4: when performing active balancing, detecting the voltage and temperature of the single cell in real time; S5: when the temperature of the single cell is higher than a second threshold, pausing the balancing operation and performing balanced heat dissipation on the single cell, the second threshold is greater than the first threshold, and when the temperature is between the first threshold and the second threshold, continuing to execute S4; S6: when the temperature of the single cell is not higher than the second threshold, if the voltage of the single cell meets the preset balancing completion condition, ending the balancing; if the voltage of the single cell does not meet the preset balancing completion condition, continuing to execute step S4.

[0017] According to an embodiment of the present invention, before step S1, the process further includes: S0: collecting the temperature and voltage of the single cells in the battery pack, and determining whether the single cells need to be balanced. If balancing is not required, the single cells perform normal charge and discharge operations. If balancing is required, step S1 is executed.

[0018] According to an embodiment of the present invention, step S3 further includes: when the temperature is not higher than a preset first threshold, if the single cell voltage meets a preset balancing completion condition, balancing is terminated; if the single cell voltage does not meet the preset balancing completion condition, step S3 is continued.

[0019] According to an embodiment of the present invention, step S6 further includes: when the temperature of the single battery is still higher than the second threshold after balanced heat dissipation, continuing to suspend the balancing operation and perform balanced heat dissipation on the single battery.

[0020] The third aspect of the present invention provides a system for driving and balancing a battery pack in a power management system, comprising: a signal acquisition circuit for collecting the voltage and temperature of the battery pack; a microcontroller connected to the signal acquisition circuit and the balancing circuit, the microcontroller being used to output a balancing drive signal according to the above-mentioned method for driving and balancing a battery pack in a power management system, and the balancing circuit being used to actively and / or passively balance the battery assembly according to the balancing drive signal.

[0021] The solution of the present invention adopts a dual-coupling control strategy, which can realize the free switching of active and passive balancing, so that the battery pack operates in the optimal temperature range, solves the potential risk caused by the increase in the capacity difference of the single cell due to the temperature difference, enhances the utilization rate of the battery and increases the service life of the entire battery pack. In addition, the solution of the present invention adopts a single power supply design, which only requires one power supply to meet the overall balanced power supply needs, and does not require complex multiple driving power supplies for isolation, reducing the power supply needs and solving the problems of excessive transformer size and high cost caused by multiple isolated power supplies. In addition, the solution of the present invention adopts a self-driven balancing circuit design, which uses the chip's own driving signal to control the balancing of single cells, and does not require a digital processor to send a large number of driving signals for isolated balancing drive, reducing the use of digital processors and making the control more integrated. In addition, the passive balancing of the solution of the present invention is based on active balancing. Only one MOS tube and three resistors need to be added to complete the passive balancing design, which is convenient and simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solution of the present invention, the following is a brief introduction to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 The figure is a block diagram of a dual-coupling balancing structure of a circuit for driving and balancing a battery pack in a power management system according to an exemplary embodiment of the present invention.

[0024] Figure 2 1 is a structural block diagram of a dual-coupling balancing control system of a circuit for driving and balancing a battery pack in a power management system according to an exemplary embodiment of the present invention.

[0025] Figure 31 is a structural block diagram of a sampling circuit of a circuit for driving and balancing a battery pack in a power management system according to an exemplary embodiment of the present invention.

[0026] Figure 4 It is a schematic diagram of a dual-coupled BMS single power self-driving circuit balancing circuit of a circuit for driving and balancing a battery pack in a power management system according to an exemplary embodiment of the present invention.

[0027] Figure 5 The diagram is a block diagram of a primary current sampling circuit of a circuit for driving and balancing a battery pack in a power management system according to an exemplary embodiment of the present invention.

[0028] Figure 6 The diagram is a block diagram of a secondary-side current sampling circuit of a circuit for driving and balancing a battery pack in a power management system according to an exemplary embodiment of the present invention.

[0029] Figure 7 is a flowchart of a method for driving and balancing a battery pack in a power management system according to an exemplary embodiment of the present invention. Specific embodiments

[0030] As used herein, the words "first", "second", etc. may be used to describe elements in exemplary embodiments of the present invention. These words are only used to distinguish one element from another, and the inherent characteristics or order of the corresponding elements are not limited by the words. Unless otherwise defined, all terms used herein (including technical or scientific terms) have the same meaning as those commonly understood by those of ordinary skill in the art to which the present invention belongs. Terms such as those defined in commonly used dictionaries are interpreted as having the same meaning as the contextual meaning in the relevant technical field, and are not interpreted as having ideal or overly formal meanings, unless explicitly defined as having such meanings in the present invention.

[0031] Those skilled in the art will understand that the apparatus and methods of the present invention described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments, and that the scope of the present invention is defined solely by the claims. Features illustrated or described in conjunction with one exemplary embodiment may be combined with features of other embodiments. Such modifications and variations are within the scope of the present invention.

[0032] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the accompanying drawings, detailed descriptions of related known functions or configurations are omitted to avoid unnecessarily obscuring the technical key points of the present invention. Throughout the description, the same reference numerals will always refer to the same circuits, modules, or units, and for the sake of brevity, repeated descriptions of the same circuits, modules, or units will be omitted.

[0033] The present invention designs a dual-coupled BMS single-power self-driven circuit and control method for new energy electric vehicles. Under low-temperature conditions, the system activates a passive energy balancing circuit. The heat released during the balancing process allows the lithium battery pack to reach the operating window temperature more quickly. After the temperature reaches a set threshold, the system automatically switches to a more efficient active energy transfer balancing circuit, improving the charge and discharge characteristics. This allows the entire battery system to achieve maximum performance while avoiding the potential dangers caused by thermal runaway. At this point, the entire battery management system reaches an ideal state of balancing with less time, maximum efficiency, and maximum safety. During the balancing process, a single-power balancing self-driven solution is used for control, which enhances the system's integration, reduces the design of peripheral circuits, and reduces costs.

[0034] Figure 1 The figure is a block diagram of a dual-coupling balancing structure of a circuit for driving and balancing a battery pack in a power management system according to an exemplary embodiment of the present invention.

[0035] like Figure 1 As shown in FIG, the circuit structure of the dual-coupled equalizer mainly includes:

[0036] The battery pack (or battery group) of the battery management system, for example, can be composed of 12 strings of single cells connected in series. Due to factors such as material processing, the 12 strings of single cells have differences, resulting in energy imbalance during the charging and discharging process.

[0037] The acquisition module (or circuit) is used to collect the voltage and temperature of the battery pack in real time. The acquisition module can usually be implemented using the LTC 6811-2 chip. This chip can realize the information collection and drive output of the battery pack, and the load collects the voltage and temperature of the single battery in the battery pack or battery pack. The chip can also realize the issuance of the balanced drive signal. The internal communication interface can realize the two-way information transmission with the control module;

[0038] A control module (or circuit) is used to select active balancing and / or passive balancing of the battery pack based on whether the collected voltage and temperature meet preset conditions, and to generate corresponding balancing drive signals. The control module is usually implemented using an MCU and is used to implement balancing control of the battery pack based on the operation of an internal program;

[0039] The balancing module (or circuit) includes an active balancing circuit and a passive balancing circuit, and is used to actively balance and / or passively balance the battery assembly according to the balancing drive signal.

[0040] According to one or more embodiments of the present invention, using a lithium-ion battery pack as an example, active balancing refers to the use of an energy transfer device in a lithium-ion battery to replenish the power of a high-energy lithium-ion battery cell to a low-energy lithium-ion battery cell. This essentially utilizes the unidirectional and bidirectional energy transfer capabilities of the lithium-ion battery pack to perform energy conversion within the lithium-ion battery pack, thereby improving the variability of the lithium-ion battery cells within the pack. The active and passive balancing of the present invention can also be applied to battery packs in other battery management systems.

[0041] Figure 2 1 is a structural block diagram of a dual-coupling balancing control system of a circuit for driving and balancing a battery pack in a power management system according to an exemplary embodiment of the present invention.

[0042] like Figure 2 As shown, the system includes a battery pack, an LTC6811-2 sampling chip, active / passive balancing circuits, a communication isolation circuit, a bidirectional communication chip LTC6820, a main control chip MCU, a balancing path driver circuit, a balancing transformer, and primary and secondary current sampling circuits. The communication isolation circuit isolates and transmits communication signals between different power sources to prevent interference. The bidirectional communication chip LTC6820 enables bidirectional SPI communication. The main control MCU controls active and / or passive balancing of the battery pack. The active / passive balancing circuit performs active and passive balancing of the battery pack based on the drive control signals output by the main control MCU. The balancing path driver circuit selects the balancing path and the cell to be balanced, and also drives the corresponding switches to conduct. The drive signal voltage from the MCU is too low to ensure normal conduction of the switch, requiring the driver circuit to increase the voltage to meet the driving conditions. The balancing transformer and the primary and secondary current sampling circuits determine the balancing moment through current sampling. For example, when the current reaches 2A, the switch tube is disconnected, and when 0A is detected, the switch tube is closed. The input and output are both analog voltage signals. The current signal can be represented by the voltage signal through proportional operation.

[0043] Among them, the battery pack signal collection of the present invention can be implemented by LTC6811-2, which is a multi-cell battery pack monitor used for collecting battery voltage and temperature during battery balancing, and issuing balancing drive signals. It can measure the voltage of up to 12 series-connected batteries with a total measurement error of less than 1.2mV.

[0044] Figure 3 1 is a structural block diagram of a sampling circuit of a circuit for driving and balancing a battery pack in a power management system according to an exemplary embodiment of the present invention.

[0045] like Figure 3 As shown, the LTC6811-2 samples the voltage of the battery pack's individual cells and generates corresponding equalization signals. The IPA and IMA interfaces are SPI communication interfaces, connected to the LTC6820 isolated communication interface via an isolation communication module. Ultimately, they connect to the MCU for bidirectional communication. The communication isolation module isolates communication information, preventing interference and ensuring safety. The LTC6820 provides bidirectional SPI communication between the two isolated components via a single twisted-pair cable. The NTC resistor module is connected to the LTC6811-2 via a wire to collect the temperature of the battery pack's individual cells.

[0046] like Figure 3 As shown in the figure, the C0-C12 pins of the LTC6811-2 are connected to the positive and negative poles of 12 strings of single cells, sampling the voltage of the single cells in real time and simultaneously sampling the temperature through an external NTC resistor. The cells are connected to the MCU via SPI isolated communication, and the information is transmitted bidirectionally through the LTC6820. After processing the information, the MCU issues a judgment instruction for balancing selection and sends a drive signal to complete the selection of the corresponding balancing path. The LTC6811-2 also balances the drive signal to complete the entire balancing process.

[0047] Figure 4 It is a schematic diagram of a dual-coupled BMS single power self-driving circuit balancing circuit of a circuit for driving and balancing a battery pack in a power management system according to an exemplary embodiment of the present invention.

[0048] like Figure 4 As shown, when balancing the single cells in the battery pack, the active and passive balancing unit includes a self-driving unit, a single power driving unit and a coupled dual balancing unit connected in sequence; the self-driving unit is used to provide a self-driving signal to the balancing module; the single-cell driving unit is used to select the balancing path and the charging and discharging selection in the battery pack; the coupled dual balancing unit is used to perform active balancing and / or passive balancing and battery pack charging and discharging selection according to the balancing driving signal of the control module.

[0049] In addition, if Figure 4As shown in the figure, the balancing process for a single cell is explained in detail. It primarily consists of three parts: a self-driven section, a single-power-supply driving section, and a coupled dual-balancing section. In the circuit diagram, the primary power source is a single cell, and the secondary side is a 24V DC-DC power source. The self-driven section primarily consists of two back-to-back MOSFETs (D1, D2, D3, and D4) to prevent mis-conduction, protection resistors (R1 and R4), current-limiting resistors (R2 and R3), and two transistors (D3 and D4). Sn represents the drive signal from the LTC6811, and Cn represents a cell with a voltage higher than the cell voltage in the example. Sn and Cn are used to select the cell to be balanced. The single-power-supply driving section primarily consists of four MOSFETs (D1, D2, D3, and D4) for direction selection, protection resistors (R6, R8, R9, and R10), and voltage divider resistors (R5 and R7). This section primarily selects the balancing path and selectively connects the battery to charge or discharge. R11, R12, D11, and R13 in the coupled dual-balancing part constitute the passive balancing part, and the remaining circuits constitute the active balancing part. As shown in the figure, the active balancing circuit is composed of a coupling circuit with anti-filtering impact, and the active and passive balancing and charging and discharging are selected according to the instructions issued by the system. Figure 4 In the diagram, the symbol R stands for resistor, C stands for capacitor, D stands for diode, and T stands for transformer.

[0050] Figure 5 It is a primary current sampling circuit. The sampling circuit is connected to a differential op amp through an op amp for isolation, and the output is connected to a DSP (signal processor) through an op amp for primary current sampling.

[0051] Figure 6 This is a secondary-side current sampling circuit. The secondary-side current shares a common ground with the DC-DC 24V. No differential isolation is required and it can be connected to the DSP simply through an op amp.

[0052] Figure 7 is a flowchart of a method for driving and balancing a battery pack in a power management system according to an exemplary embodiment of the present invention.

[0053] like Figure 7 As shown:

[0054] At step S0: when the system is running, the temperature and voltage of the lithium battery are collected, and the collected voltage is used to determine whether the single battery needs to be balanced. If not, the balancing is not turned on and the single battery is charged and discharged normally. If it is necessary, step S1 is performed;

[0055] In step S1: determine which single battery cell needs to be balanced and perform temperature determination at the same time.

[0056] At step S2: if the temperature is lower than a first threshold, then step S3 is performed to turn on passive balancing, otherwise step S4 is performed to turn on active balancing. For example, the first threshold can be selected as 10°C.

[0057] In step S3, passive balancing is activated, and the voltage and temperature during the balancing process are collected. By fully utilizing the heat generated during the energy loss balancing process, the temperature of the lithium battery pack is raised and quickly enters the lithium battery operating window temperature range, achieving maximum charge and discharge efficiency while avoiding energy waste. After the battery management system has been running for a period of time, the battery pack temperature gradually rises. The temperature is checked to see if it reaches a first threshold preset by the system. If so, the controller issues a command to switch the balancing circuit, which is transmitted via the SPI communication bus to the control switch to activate active energy balancing and proceed to step S4. If not, the system proceeds according to the balancing conditions and determines whether further balancing is required. If so, it proceeds to step S3; otherwise, it proceeds to step S0.

[0058] At step S4: active balancing is turned on, and the voltage and temperature of the balanced single cells are collected in real time;

[0059] At step S5: the voltage and temperature of the actively balanced battery are compared with a set second threshold. The temperature comparison is performed first. If the temperature is higher than the set second threshold, step S4 is performed; otherwise, step S5 is performed. The second threshold is greater than the first threshold. For example, the second threshold may be 50°C.

[0060] At step S5: when the temperature of the single cell is higher than the second threshold, the balancing operation is suspended and the single cell is subjected to balanced heat dissipation. When the temperature is between the first threshold and the second threshold (i.e. Figure 7 The temperature setting value in the setting in S4 is continued to be executed, the balancing operation is suspended, the heat dissipation is balanced, and it is determined whether the temperature reduction meets the balancing condition. If so, S4 is performed, and if not, S5 is continued;

[0061] S6: When the temperature of the single cell is not higher than the second threshold, if the voltage of the single cell meets the preset balancing completion condition, the balancing is ended and the process returns to step S0; if the voltage of the single cell does not meet the preset balancing completion condition, the process continues to step S4.

[0062] According to one or more embodiments of the present invention, the preset balancing condition may be that the voltage of a preset single cell meets a preset charging voltage threshold or a discharging voltage threshold. Figure 7 In the process of comparing the battery temperature with the set value, the temperature set value is a preset first and second threshold value, wherein the first threshold value is greater than the second threshold value, and the voltage set value is used to determine whether the balancing condition is met, that is, whether the balancing is completed, that is, the voltage of the single cell meets the preset charging voltage threshold or discharging voltage threshold.

[0063] According to one or more embodiments of the present invention, the present invention also provides a system for driving and balancing a battery pack in a power management system, comprising: a signal acquisition circuit for collecting the voltage and temperature of the battery pack; a microcontroller MCU connected to the signal acquisition circuit and the balancing circuit, the microcontroller being used for the above-mentioned driving and balancing method of the present invention to generate a balancing drive control signal; and a balancing circuit for actively and / or passively balancing the battery assembly according to the balancing drive signal.

[0064] Furthermore, it should be understood that one or more of the following methods or aspects thereof can be performed by at least one control unit or controller. The terms "control unit," "microcontroller," "control module," or "main control module" can refer to a hardware device including a memory and a processor. The memory or computer-readable storage medium is configured to store program instructions, while the processor is specifically configured to execute the program instructions to perform one or more processes described further below. Furthermore, it should be understood that, as will be appreciated by one of ordinary skill in the art, the following methods can be performed by including a processor in combination with one or more other components.

[0065] According to one or more embodiments of the present invention, the control logic of the method of the present invention can implement the processing of the above-described scheme of the present invention using encoded instructions (e.g., computer and / or machine readable instructions) stored on a non-transitory computer and / or machine readable medium (e.g., a hard drive, flash memory, read-only memory, optical disk, digital versatile disk, cache, random access memory and / or any other storage device or storage disk), in which information is stored for any period of time (e.g., an extended period of time, permanent, a transient instance, a temporary cache and / or an information cache). As used herein, the term "non-transitory computer readable medium" is expressly defined to include any type of computer readable storage device and / or storage disk, and to exclude propagating signals and to exclude transmission media.

[0066] According to one or more embodiments of the present invention, the circuits, (control logic, main control system or control module) of the present invention may include one or more processors, and may also include non-transitory computer-readable media internally. Specifically, the processor used to implement the functions of the present invention may be, but not limited to, one or more single-core or multi-core processors. (One or more) processors may include any combination of general-purpose processors and special-purpose processors (e.g., graphics processors, application processors, etc.). The processor may be coupled to and / or may include a memory / storage device, and may be configured to execute instructions stored in the memory / storage device to implement various applications and / or operating systems running on the controller in the present invention.

[0067] While the invention has been described in connection with what are presently considered to be capable embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but on the contrary is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A circuit for driving and balancing a battery pack in a power management system, characterized in that: include: Signal acquisition module, used to collect the voltage and temperature of the battery pack; a control module, configured to select active balancing and / or passive balancing for the battery pack based on whether the collected voltage and temperature meet preset conditions, and generate a corresponding balancing drive signal, wherein passive balancing is performed when the temperature of the single battery cell is lower than a first threshold, and active balancing is performed otherwise; A balancing module, configured to perform active and / or passive balancing on the battery components according to a balancing drive signal; The balancing module includes an active and passive balancing unit, a balancing path driving unit, and a balancing transformer primary current sampling unit and a secondary current sampling unit. The active and passive balancing unit is used to perform active and / or passive balancing of the battery pack. The balancing path driving circuit is used to select a battery balancing path in the battery pack according to a balancing drive signal. The balancing transformer primary current sampling unit and the secondary current sampling unit are used to determine the balancing time through current sampling. The active and passive balancing unit includes a coupled dual balancing unit, which is used to perform active balancing and / or passive balancing and select battery pack charging and discharging according to the balancing drive signal of the control module. The coupled dual balancing unit is composed of an active balancing circuit and a passive balancing circuit. The passive balancing circuit is composed of a discharge resistor and a MOS tube in series, and the active balancing circuit is composed of a coupling circuit with anti-filtering impact.

2. The circuit of claim 1, wherein the circuit is powered by a single power supply.

3. The circuit of claim 1, wherein the active balancing and the passive balancing are applied to single cells in the battery pack.

4. The circuit according to claim 1, wherein When balancing the single cells in the battery pack, the active and passive balancing unit includes a self-driving unit, a single power driving unit and the coupled dual balancing unit connected in sequence; The self-driving unit is used to provide a self-driving signal for the balancing module; The single power drive unit is used for selecting a balancing path and selectively connecting charging and discharging in a battery pack.

5. The circuit according to claim 4, wherein: The self-driving unit is composed of two back-to-back MOS tubes to prevent misconduction, two protection resistors, two current-limiting resistors and two transistors; The single power supply driving part includes four MOS tubes for direction selection, a protection resistor and a voltage divider resistor.

6. The circuit according to claim 1, wherein the primary current sampling circuit is connected to a differential operational amplifier through an operational amplifier for isolation, and the output is then connected to a signal processor through the operational amplifier for primary current sampling; and the secondary current sampling circuit is directly connected to a signal processor through an operational amplifier for secondary current sampling.

7. A method for driving and balancing a battery pack in a power management system, characterized in that: The circuit for driving and balancing a battery pack in a power management system according to any one of claims 1 to 6, the method comprising: S1: Determine a single cell in the battery pack that needs to be balanced, and compare the temperature of the single cell with a preset first threshold; S2: When the temperature of the single battery is lower than the first threshold, passive balancing is performed; otherwise, active balancing is performed; S3: When performing passive balancing, the voltage and temperature of the single battery are detected in real time. When the temperature is higher than a preset first threshold, step S4 is executed; S4: When active balancing is performed, the voltage and temperature of the single battery are detected in real time; S5: When the temperature of the single battery cell is higher than a second threshold, suspending the balancing operation and performing balanced heat dissipation on the single battery cell, the second threshold being greater than the first threshold. When the temperature is between the first threshold and the second threshold, continuing with S4. S6: When the temperature of the single cell is not higher than the second threshold, if the voltage of the single cell meets the preset balancing completion condition, the balancing is ended; if the voltage of the single cell does not meet the preset balancing completion condition, the step S4 is continued.

8. The method according to claim 7, further comprising before step S1: S0: collecting the temperature and voltage of the single cells in the battery pack, and determining whether the single cells need to be balanced. If not, the single cells perform normal charge and discharge operations. If balancing is required, executing step S1.

9. The method according to claim 7, wherein said step S3 further comprises: When the temperature is not higher than a preset first threshold, if the single cell voltage meets a preset balancing completion condition, balancing is terminated; If the single cell voltage does not meet the preset balancing completion condition, proceed to step S3.

10. The method according to claim 7, wherein the step S6 further comprises: When the temperature of the single battery is still higher than the second threshold after balanced heat dissipation, the balancing operation is continued to be suspended and balanced heat dissipation is performed on the single battery.

11. A system for driving and balancing a battery pack in a power management system, characterized in that: include: Signal acquisition circuit, used to collect the voltage and temperature of the battery pack; A microcontroller is connected to the signal acquisition circuit and the equalization circuit, and the microcontroller is used to output a balanced drive signal according to the method according to any one of claims 7 to 10. The balancing circuit is used to actively balance and / or passively balance the battery components according to the balancing drive signal.

12. The system of claim 11, wherein the system is powered by a single power supply.

13. The system of claim 11, wherein the active balancing and the passive balancing are applied to single cells in the battery pack.

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