Self-adaptive active equalization battery management system and new energy automobile

Abstract

The invention provides a self-adaptive active equalization battery management system and a new energy automobile, and the system is additionally provided with a bidirectional DC-DC module A, a bidirectional DC-DC module B, an equalization scheduling module and a self-adaptive control module, and through the equalization strategy of the self-adaptive control module, the flow of energy between battery cells is realized, and the energy utilization rate is improved. The internal balance of the battery PACK can be realized, the pressure difference of the whole cluster can be eliminated, and the flow of energy in the whole cluster is realized. According to the technical scheme provided by the invention, the problems of low efficiency, fixed strategy, low speed, poor reliability and the like in the traditional active equalization technology are solved, and the performance and the service life of the large energy storage system and the electric vehicle battery pack are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery management systems (BMS), and in particular to an adaptive active balancing battery management system and a new energy vehicle. Background Art

[0002] In large energy storage systems and electric vehicles, battery packs are usually composed of multiple cells connected in series and parallel. Due to manufacturing errors, temperature differences and different usage conditions, inconsistencies will occur between the individual cells, resulting in a decrease in the overall performance of the battery pack and a shortened service life.

[0003] Cell voltage is a direct measurement value and can be measured online in real time, which makes it a favorable condition for measuring the consistency level of system cells. In addition, in common BMS management strategies, the cell voltage value is used as a trigger condition for discharge termination conditions, charge termination conditions, etc.

[0004] The consistency between battery cells. For vehicle endurance, capacity is the most direct and important parameter, so consistency mainly refers to capacity. Capacity is a parameter that cannot be directly measured in a short time. According to experience, there is a one-to-one correspondence between the capacity of a single cell and its open circuit voltage. Therefore, the focus of examining the consistency of batteries in systems that have been installed and operated ultimately falls on the cell voltage.

[0005] If the cell voltage consistency is too different, it will directly limit the charging and discharging power of the battery pack. Based on this, people use the battery balancing method to solve the problem of large cell voltage differences in battery packs that are already in operation to increase the capacity of the battery pack. Therefore, it can be inferred that the balancing method extends the driving range and extends the battery life.

[0006] Traditional passive balancing methods achieve balancing by consuming excess power, resulting in low energy utilization. Active battery balancing extends system operation time and prevents battery cell damage by redistributing charge during charging and discharging. Compared with passive balancing, active balancing can improve charging efficiency and reduce heat generation. Active battery balancing extends system operation time and prevents battery cell damage by redistributing charge during charging and discharging.

[0007] Active balancing is an important means for the battery management system (BMS) to solve the voltage difference of battery cells. It can extend the battery life and improve the system capacity by cutting high and filling low or parallel balancing strategies. Common active balancing circuits include capacitive, inductive, transformer and parallel balancing, each with its own working principle and applicable scenarios. Under different battery capacity requirements, choosing the right balancing method is crucial to optimizing battery performance and life.

[0008] Although the existing active balancing technology can transfer energy between cells, it has the following problems:

[0009] 1) Only one battery pack can be balanced, and the voltage difference of the entire cluster cannot be eliminated;

[0010] 2) Low balancing efficiency, especially under high current conditions;

[0011] 3) The balancing speed is slow and it is difficult to meet the demand for fast charging and discharging;

[0012] 4) Switch arrays are often used for separate balancing, which results in complex circuits and low reliability.

[0013] 5) The balancing strategy is fixed and difficult to adapt to different working conditions;

[0014] 6) The number of charging and discharging circuits is limited to prevent the discharge amount from being greater than the charging amount, causing the balanced bus voltage to increase and damage the power supply.

[0015] Therefore, there is an urgent need to develop an efficient, flexible, fast and reliable active balancing technology.

[0016] In order to facilitate understanding of the technical solution of this application, the relevant technical terms are explained as follows:

[0017] 1. BMU is a battery management unit with multiple functions, including voltage monitoring, current monitoring, temperature monitoring, insulation monitoring and relay status monitoring.

[0018] It can detect the voltage, total current, total voltage, ambient temperature and other parameters of all single cells in the battery pack in real time. BMU is mainly composed of battery sampling management chip ltc680, which consists of main processor CPU, battery peripheral power supply and charging circuit, peripheral protection and filtering circuit.

[0019] 2. BCU usually refers to the Brake Control Unit. It is an important component of the vehicle's braking system, responsible for monitoring and adjusting the various functions of the braking system to ensure the safety and efficiency of the braking process. The BCU controls the distribution of brake pressure by receiving signals from the driver and other vehicle systems to prevent wheel lock and activate the emergency braking function when necessary.

[0020] 3. To obtain data of single battery, battery pack, battery cluster, battery stack, PCS and BMS, the following methods can be used:

[0021] Single battery: You can connect a single battery to a test device or instrument, such as a battery tester or battery management system, to obtain data such as the voltage, current, and temperature of the single battery.

[0022] Battery pack: A battery pack usually contains one or more single batteries, which can be connected to a BMS or test equipment to obtain data such as the overall voltage, current, SOC (State of Charge) and remaining battery capacity of the battery pack.

[0023] Battery cluster: A battery cluster is a whole formed by connecting multiple battery packs together. It can be connected to a BMS or test equipment to obtain the overall voltage, current, SOC and other data of the battery cluster.

[0024] Battery stack: A battery stack is a whole formed by connecting multiple battery clusters together. It can be connected to a BMS or test equipment to obtain the overall voltage, current, SOC and other data of the battery stack.

[0025] PCS: PCS is responsible for the energy conversion and control of the battery stack. The input voltage, output voltage, power, efficiency and other data of the PCS can be obtained by connecting to the monitoring system or interface of the PCS.

[0026] BMS: BMS is usually embedded in the battery pack. The monitoring system or interface connected to the BMS can be used to obtain data such as battery status, battery temperature, battery health status, charge and discharge control, etc. provided by the BMS.

[0027] It should be noted that the specific data acquisition methods and interfaces may vary for different systems and devices. In actual operation, you can select the appropriate method and interface to obtain the required data according to the specifications and documentation of the device and system. Summary of the invention

[0028] The purpose of the present invention is to overcome the above technical deficiencies and provide an adaptive active balancing battery management system and a new energy vehicle, so as to at least solve the problem that the related art can only perform balancing within a PACK and cannot eliminate the pressure difference of the entire cluster.

[0029] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0030] According to a first aspect of the present invention, there is provided an adaptive active balancing battery management system, which is applicable to a single battery cluster and includes:

[0031] Multiple bidirectional DC-DC modules A are integrated in multiple channels on the BMU slave control unit, and each bidirectional DC-DC module A corresponds to one battery cell;

[0032] A bidirectional DC-DC module B, whose primary side is connected to the positive and negative terminals of the battery cluster respectively, and whose secondary side is connected to the primary sides of each bidirectional DC-DC module A through a common balancing bus, and whose secondary side is connected to the corresponding battery cell;

[0033] The bidirectional DC-DC module A in the whole cluster performs internal energy transfer in advance. When the internal transferred energy is insufficient, that is, the energy required by the bidirectional DC-DC module A when working in the charging mode is greater than the energy provided when working in the discharging mode, the bidirectional DC-DC module B provides the energy. If the transferred energy in the whole cluster is surplus, that is, the energy provided by the bidirectional DC-DC module A when working in the discharging mode is greater than the energy required when working in the charging mode, the surplus energy is transferred to the bidirectional DC-DC module B.

[0034] The battery status monitoring module is integrated in the BMU slave control unit and communicates with all BMU slave control units through the CAN bus to monitor the voltage, current and temperature of each battery cell in real time;

[0035] The adaptive control module is integrated in the BCU main control unit and is used to predict the optimal balancing path based on the current and historical monitoring data of the battery;

[0036] The balancing scheduling module is integrated in the BMU slave control unit and is used to adopt a distributed control strategy, communicate with the BCU master control unit through the CAN bus, receive the balancing instructions sent by the adaptive control module, and coordinate the working status of each DC-DC module A.

[0037] Preferably, the bidirectional DC-DC module A adopts transformer primary winding sampling to implement a voltage-stabilized flyback converter, thereby realizing bidirectional energy transmission between the bidirectional DC-DC modules A in the entire cluster;

[0038] The bidirectional DC-DC module B adopts a dual-path synchronous Buck / Boost circuit and a bidirectional full-bridge resonant converter DAB-LLC to achieve bidirectional energy transmission between a common balancing bus and a battery cluster end.

[0039] 3. The system according to claim 2, characterized in that each of the bidirectional DC-DC modules A has the same structure, including: an internal circuit and connected to the internal circuit:

[0040] The VIN+ pin and the GND_P pin are connected to the positive line and the ground line of the common balanced bus respectively;

[0041] The CELL+ pin and CELL- pin are connected to the positive and negative electrodes of the single cell respectively;

[0042] The enable pin EN and the charge and discharge control pin CD are connected to the balancing scheduling module.

[0043] Preferably, the internal circuit comprises:

[0044] A transformer T1, a current mode PWM controller U1 connected to the primary side of the transformer T1, and a dedicated converter U2 connected to the secondary side of the transformer T1;

[0045] Among them, U1 achieves voltage stabilization by sampling the primary winding of transformer T1;

[0046] The RIN pin of U1 is connected to the VIN+ pin through the bias resistor R11. Whether the function of the RIN pin of U1 is turned on is controlled by the voltage of the OUP pin of U1.

[0047] The FB pin of U1 is connected between the series-connected resistors R3 and R4; one end of the series-connected resistors R3 and R4 is externally connected to a switching power supply, and the other end is grounded; the switching power supply is also connected to the VDD pin of U1 through the series-connected resistor R8 and the diode D1;

[0048] By adjusting the resistance values ​​of resistors R3 and R4, the output voltage value of DC-DC module A is changed. The output voltage formula in charging mode is as follows:

[0049]

[0050] Among them, Ns and Na are the turns of the secondary output winding and the primary auxiliary winding of transformer T1 respectively;

[0051] R3 and R4 are sampling resistors of the auxiliary winding; Vref is the internal reference voltage, which is 2V;

[0052] VF is the junction voltage drop of the output diode, which is 0.3V.

[0053] Preferably, U2 switches the charge and discharge mode through the enable pin EN and the charge and discharge control pin CD to realize the function of the bidirectional converter;

[0054] A sampling resistor R19 is connected between the RFB pin and the DRN pin of U2, a diode D4 is connected between the DRN pin and the ground, and the EN pin is grounded through a capacitor C11 and a resistor R20 connected in parallel;

[0055] In the demagnetization stage, the RFB pin voltage is clamped to the voltage value VIN of the common balanced bus, so that the voltage across the resistor R19 in the demagnetization stage is equal to the voltage difference across the primary main winding of the transformer T1; the output voltage formula in the discharge mode is as follows:

[0056]

[0057] Among them, Np and Ns are the number of turns of the primary main winding and the secondary output winding of transformer T1 respectively;

[0058] R19 is the sampling resistor value between the RFB pin and the DRN pin;

[0059] VF is the junction voltage drop of the output diode D4, which is 0.3V;

[0060] When the EN pin is connected to a low level through R20, U2 selects the synchronous rectification function.

[0061] Preferably, the bidirectional DC-DC module B comprises: a dual-path synchronous Buck / Boost circuit and a bidirectional full-bridge resonant converter DAB-LLC; wherein,

[0062] Inductor L1, field effect transistor S1, field effect transistor S4 form a Buck / Boost circuit, inductor L2, field effect transistor S3, field effect transistor S2 form a Buck / Boost circuit, two-phase staggered control, switching signals are staggered in time, and the phase difference is 180°;

[0063] The bidirectional full-bridge resonant converter DAB-LLC isolated by transformer Tr1 comprises: transformer Tr1, and a full-bridge rectifier composed of switch tubes S5-S8 connected to the primary side of transformer Tr1, and a full-bridge rectifier composed of switch tubes S9-S12 connected to the secondary side of transformer Tr1;

[0064] An inductor Lr1 and a capacitor Cr1 are added in series on the primary side of the transformer Tr1, and an inductor Lr1 and a capacitor Cr1 are added in series on the secondary side, so that the DAB-LLC has the same LLC resonant network when working in forward and reverse directions.

[0065] Preferably, the workflow of the adaptive control module includes:

[0066] Step S11, initializing the system: power on self-check to ensure that all modules are working properly; loading historical balancing data and current battery monitoring data;

[0067] Step S12, collecting battery status data: monitoring the voltage, current, and temperature of each battery cell; calculating the state of charge SOC and state of health SOH of each battery cell;

[0068] Step S13, determining whether balancing is required: determining whether there is inconsistency in the battery pack;

[0069] Step S14: If it is determined that balancing is required, calculate the battery pack SOC difference: take the difference between the maximum SOC and the minimum SOC as the battery pack SOC difference, and consider the standard deviation of the SOC distribution; if it is determined that balancing is not required, return to step S12;

[0070] Step S15, judging whether the SOC difference of the battery pack is greater than a threshold value, and if so, determining the balancing priority: sorting according to the SOC difference, while considering the health status and temperature of the battery cell;

[0071] Step S16: Select the optimal balancing path and activate the corresponding bidirectional DC-DC module A;

[0072] Step S17, executing energy transmission: monitoring the direction and magnitude of energy flow, and adjusting the working state of the bidirectional DC-DC module A in real time;

[0073] Step S18, determine whether the balancing target is achieved, if so, stop balancing and return to step S12; otherwise, adjust the balancing parameters and return to step S17.

[0074] Preferably, the step S12 further includes:

[0075] Determine whether the voltage, current, and temperature of each battery cell exceed their respective threshold ranges. If so, trigger the protection mechanism, stop balancing, and issue an alarm;

[0076] The optimal balanced path is selected in step S16, specifically:

[0077] Based on historical balancing data and current battery monitoring data, a deep learning algorithm is used to update the battery model to predict the optimal balancing path and obtain the first optimal balancing path;

[0078] The first optimal balancing path is compared with the second optimal balancing path corresponding to the minimum SOC difference value in step S15, and the optimal balancing path is selected.

[0079] Preferably, the balancing scheduling module realizes the switching of three working states of the bidirectional DC-DC module A through the enable pin EN and the charge and discharge control pin CD of the bidirectional DC-DC module A: the balancing module A is not working, the balancing module A is forward transmitting-charging, and the balancing module A is reverse transmitting-discharging;

[0080] If the charge and discharge control of N-way bidirectional DC-DC module A is realized, 2N-way control signals are required;

[0081] The balancing scheduling module realizes 2N control signal outputs by cascading multiple shift registers.

[0082] According to a second aspect of the present invention, there is provided a new energy vehicle, comprising:

[0083] It includes a battery cluster and the above-mentioned adaptive active balancing battery management system.

[0084] The technical solution provided by the embodiments of the present invention may have the following beneficial effects:

[0085] By adding bidirectional DC-DC module A, bidirectional DC-DC module B, balancing scheduling module and adaptive control module, and realizing the flow of energy between cells through the balancing strategy of the adaptive control module, not only the balance inside the battery PACK can be realized, but also the pressure difference of the whole cluster can be eliminated to realize the flow of energy within the whole cluster. The technical solution provided by the present invention solves the problems of low efficiency, fixed strategy, slow speed and poor reliability existing in traditional active balancing technology, and significantly improves the performance and life of large energy storage systems and electric vehicle battery packs. BRIEF DESCRIPTION OF THE DRAWINGS

[0086] Figure 1 is a schematic diagram of the overall structure of an adaptive active balancing battery management system according to an exemplary embodiment;

[0087] Figures 2A to 2D is a circuit schematic diagram of a bidirectional DC-DC module A according to an exemplary embodiment;

[0088] Figure 3A-3B is a circuit schematic diagram of a bidirectional DC-DC module B according to an exemplary embodiment;

[0089] Figure 4 is a flowchart of an adaptive control module according to an exemplary embodiment;

[0090] Figures 5A-5B is a circuit schematic diagram of a balanced scheduling module according to an exemplary embodiment. DETAILED DESCRIPTION

[0091] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present application.

[0092] Embodiment 1

[0093] Figure 1 is a schematic diagram of the overall structure of an adaptive active balancing battery management system according to an exemplary embodiment. The system is applicable to a single battery cluster. Figure 1 , the system comprises:

[0094] Multiple bidirectional DC-DC modules A are integrated in multiple channels on the BMU slave control unit, and each bidirectional DC-DC module A corresponds to one battery cell;

[0095] A bidirectional DC-DC module B, whose primary side is connected to the positive and negative terminals of the battery cluster respectively, and whose secondary side is connected to the primary sides of each bidirectional DC-DC module A through a common balancing bus, and whose secondary side is connected to the corresponding battery cell;

[0096] The bidirectional DC-DC module A in the whole cluster performs internal energy transfer in advance. When the internal transferred energy is insufficient, that is, the energy required by the bidirectional DC-DC module A when working in the charging mode is greater than the energy provided when working in the discharging mode, the bidirectional DC-DC module B provides the energy. If the transferred energy in the whole cluster is surplus, that is, the energy provided by the bidirectional DC-DC module A when working in the discharging mode is greater than the energy required when working in the charging mode, the surplus energy is transferred to the bidirectional DC-DC module B.

[0097] The battery status monitoring module 101 is integrated in the BMU slave control unit and communicates with all BMU slave control units through the CAN bus to monitor the voltage, current and temperature of each battery cell in real time;

[0098] The adaptive control module 102 is integrated in the BCU main control unit and is used to predict the optimal balancing path based on the current monitoring data and historical monitoring data of the battery;

[0099] The balancing scheduling module 103 is integrated in the BMU slave control unit and is used to adopt a distributed control strategy, communicate with the BCU master control unit through the CAN bus, receive the balancing instructions sent by the adaptive control module, and coordinate the working status of each DC-DC module A.

[0100] It can be understood that the common balanced bus connects all DC-DC modules A and DC-DC modules B and serves as an intermediate medium for energy exchange.

[0101] It can be understood that the CAN communication bus connects all BMU slave control units and BCU master control units and serves as an intermediate medium for information exchange.

[0102] It is understandable that the technical solution provided in this embodiment, by adding a bidirectional DC-DC module A, a bidirectional DC-DC module B, a balancing scheduling module and an adaptive control module, and by using the balancing strategy of the adaptive control module, realizes the flow of energy between cells, which can not only achieve the balance inside the battery PACK, but also eliminate the pressure difference of the entire cluster and realize the flow of energy within the entire cluster. The technical solution provided in this embodiment solves the problems of low efficiency, fixed strategy, slow speed, poor reliability, etc. in traditional active balancing technology, and significantly improves the performance and life of large energy storage systems and electric vehicle battery packs.

[0103] Specifically, the technical solution provided by this embodiment has at least the following beneficial effects:

[0104] High efficiency: Each cell corresponds to a bidirectional DC-DC module A, which can be balanced at the same time and share a balancing bus to achieve rapid transfer of energy among cells in the entire cluster;

[0105] High flexibility: Due to the existence of bidirectional DC-DC module B, the working mode of bidirectional DC-DC module A can be switched freely, and energy transfer between bidirectional DC-DC modules A is prioritized. Insufficient or surplus energy is automatically absorbed or fed back to the battery cluster through bidirectional DC-DC module B;

[0106] High intelligence: Using machine learning algorithms, the optimal balancing path is predicted based on historical data and current status. The adaptive control strategy can dynamically adjust the balancing scheme of the entire cluster according to different working conditions to achieve balancing of the entire cluster.

[0107] High response speed: The distributed balanced scheduling strategy is adopted to improve the scalability, reliability and balancing speed of the system;

[0108] High reliability: Both software and hardware adopt modular design to enhance the flexibility and fault tolerance of the system.

[0109] Preferably, the bidirectional DC-DC module A adopts transformer primary winding sampling to implement a voltage-stabilized flyback converter, thereby realizing bidirectional energy transmission between the bidirectional DC-DC modules A in the entire cluster;

[0110] The bidirectional DC-DC module B adopts a dual-path synchronous Buck / Boost circuit and a bidirectional full-bridge resonant converter DAB-LLC to achieve bidirectional energy transmission between a common balancing bus and a battery cluster end.

[0111] See also Figure 2A to Figure 2D Each of the bidirectional DC-DC modules A has the same structure, including: an internal circuit and connected to the internal circuit:

[0112] The VIN+ pin and the GND_P pin are connected to the positive line and the ground line of the common balanced bus respectively;

[0113] The CELL+ pin and CELL- pin are connected to the positive and negative electrodes of the single cell respectively;

[0114] The enable pin EN and the charge and discharge control pin CD are connected to the balancing scheduling module.

[0115] See also Figure 2A to Figure 2D , the internal circuit comprises:

[0116] A transformer T1, a current mode PWM controller U1 connected to the primary side of the transformer T1, and a dedicated converter U2 connected to the secondary side of the transformer T1;

[0117] Among them, U1 achieves voltage stabilization by sampling the primary winding of transformer T1;

[0118] The RIN pin of U1 is connected to the VIN+ pin through the bias resistor R11. Whether the function of the RIN pin of U1 is turned on is controlled by the voltage of the OUP pin of U1.

[0119] The FB pin of U1 is connected between the series-connected resistors R3 and R4; one end of the series-connected resistors R3 and R4 is externally connected to a switching power supply, and the other end is grounded; the switching power supply is also connected to the VDD pin of U1 through the series-connected resistor R8 and the diode D1;

[0120] By adjusting the resistance values ​​of resistors R3 and R4, the output voltage value of DC-DC module A is changed. The output voltage formula in charging mode is as follows:

[0121]

[0122] Among them, Ns and Na are the turns of the secondary output winding and primary auxiliary winding of transformer T1 respectively;

[0123] R3 and R4 are sampling resistors of the auxiliary winding; Vref is the internal reference voltage;

[0124] VF is the junction voltage drop of the output diode.

[0125] It should be noted that U1 of the bidirectional DC-DC module A is a current mode PWM controller with a built-in MOS tube. It achieves voltage regulation by sampling the primary winding of the transformer. It has simple peripherals and low cost. It can achieve PSR feedback at an operating frequency of hundreds of KHz. The built-in output voltage sampling circuit requires the time width of the sampling voltage to be as low as 400nS. Its input voltage is as low as 2.5V, which meets the application of single-cell battery voltage.

[0126] Resistor R11 can provide bias current for the internal startup tube of U1; secondly, program the shutdown speed of the internal power MOS tube of U1; thirdly, provide feedforward compensation function.

[0127] See also Figure 2A to Figure 2D , U2 switches the charge and discharge mode through the enable pin EN and the charge and discharge control pin CD to realize the function of the bidirectional converter;

[0128] A sampling resistor R19 is connected between the RFB pin and the DRN pin of U2, a diode D4 is connected between the DRN pin and the ground, and the EN pin is grounded through a capacitor C11 and a resistor R20 connected in parallel;

[0129] In the demagnetization stage, the RFB pin voltage is clamped to the voltage value VIN of the common balanced bus, so that the voltage across the resistor R19 in the demagnetization stage is equal to the voltage difference across the primary main winding of the transformer T1; the output voltage formula in the discharge mode is as follows:

[0130]

[0131] Among them, Np and Ns are the number of turns of the primary main winding and the secondary output winding of transformer T1 respectively;

[0132] R19 is the sampling resistor value between the RFB pin and the DRN pin;

[0133] VF is the junction voltage drop of the output diode D4, which is 0.3V;

[0134] When the EN pin is connected to a low level through R20, U2 selects the synchronous rectification function.

[0135] It should be noted that in practice, the above U1 and U2 are selected as specific product models according to needs, for example, one feasible selection method is that U1 is JR2606 and U2 is JR2633. However, this model is only an example and does not limit the specific models of U1 and U2.

[0136] It should be noted that U2 of the bidirectional DC-DC module A is a dedicated converter for bidirectional converters, with an integrated power MOS tube. It can be used in PWM working mode or synchronous rectification working mode. At this time, the power MOS tube is used as a synchronous rectifier tube, which supports both CCM and DCM working modes. It also takes power from the drain of the power tube to achieve self-power supply, without the need for auxiliary windings, simplifying transformer design and peripheral circuits. In the synchronous rectification working mode, the enable pin (EN) and the charge and discharge control pin (CD) are used to switch the charge and discharge mode to achieve the function of a bidirectional converter.

[0137] The sampling resistor R19 is connected between the RFB pin of U2 and DRN. During the demagnetization stage, the voltage of the RFB pin is clamped at VIN. Then, during the demagnetization stage, the voltage across the resistor R19 is equal to the voltage difference across the transformer main winding (the primary side pins 1 / 2 and 3 / 4). FB (The voltage drop across resistor R19) is differentially amplified with the reference voltage of 1.3V inside U2. The amplified output voltage is used to adjust the duty cycle of the power switch tube, and finally the inflection point voltage at the end of the sampling voltage demagnetization is stabilized at 1.3V. At this time, the current of resistor R19 is stabilized at 100uA.

[0138] When the EN pin of U2 is connected to a low level through R20, U2 selects the synchronous rectification function. DRNThe relative maximum voltage is used to determine the excitation stage of the converter. If the relative maximum voltage is detected, an enable signal EN is generated. DRN When it is less than the turn-on threshold Vth(on), the synchronous rectification switch tube inside U2 is turned on.

[0139] See also Figure 3A to Figure 3B The bidirectional DC-DC module B includes: a dual-channel synchronous Buck / Boost circuit and a bidirectional full-bridge resonant converter DAB-LLC; wherein,

[0140] Inductor L1, field effect transistor S1, field effect transistor S4 form a Buck / Boost circuit, inductor L2, field effect transistor S3, field effect transistor S2 form a Buck / Boost circuit, two-phase staggered control, switching signals are staggered in time, and the phase difference is 180°;

[0141] The bidirectional full-bridge resonant converter DAB-LLC isolated by transformer Tr1 comprises: transformer Tr1, and a full-bridge rectifier composed of switch tubes S5-S8 connected to the primary side of transformer Tr1, and a full-bridge rectifier composed of switch tubes S9-S12 connected to the secondary side of transformer Tr1;

[0142] An inductor Lr1 and a capacitor Cr1 are added in series on the primary side of the transformer Tr1, and an inductor Lr1 and a capacitor Cr1 are added in series on the secondary side, so that the DAB-LLC has the same LLC resonant network when working in forward and reverse directions.

[0143] It should be noted that the working principle of the bidirectional DC-DC module B is as follows:

[0144] 1. Two interleaved parallel Buck / Boost circuits, L1, S1, S4 in one path, L2, S3, S2 in another path, two-phase interleaved control, the switching signals are staggered in time, usually with a phase difference of 180°.

[0145] Buck mode (high pressure to low pressure):

[0146] The high-voltage side S1 and S3 act as active switches, and the body diodes of the low-voltage side S2 and S4 act as rectifier diodes. The output voltage is adjusted by controlling the duty cycle of the high-voltage side MOSFET.

[0147] Boost mode (low voltage to high voltage):

[0148] The low-voltage side S2 and S4 act as active switches, and the body diodes of the high-voltage side S1 and S3 act as rectifier diodes. The output voltage is adjusted by controlling the duty cycle of the low-voltage side MOSFET.

[0149] 2. Transformer-isolated bidirectional full-bridge resonant converter DAB-LLC, since Lm exists in the transformer in the actual circuit, the circuit structure is completely symmetrical. The working principle is as follows:

[0150] A. Full bridge generates high-frequency square wave: The full bridge converts the DC voltage into a high-frequency square wave by controlling the opening and closing of the switch tubes S5~S8 or S9~S12.

[0151] B. LLC resonance: A high-frequency square wave passes through the LLC resonant network to generate a sinusoidal current. This resonance effect can achieve soft switching and reduce switching losses.

[0152] During forward power transmission, the primary LLC network (Lr2 and Cr2) plays the main resonant role.

[0153] During reverse power transmission, the secondary side LLC network (Lr1 and Cr1) is the main resonant circuit.

[0154] The two LLC networks work together to ensure optimal soft-switching conditions in either direction of power flow.

[0155] C. Transformer isolation and voltage conversion: The resonant current passes through a high-frequency transformer to achieve electrical isolation and voltage conversion.

[0156] D. Secondary side rectification: The secondary side full-bridge circuit can operate in rectification mode or inverter mode to achieve bidirectional energy transmission.

[0157] E. Phase shift control: By adjusting the phase difference between the primary and secondary full bridges, the direction and magnitude of power transmission can be controlled.

[0158] DAB-LLC achieves zero voltage switching (ZVS) and / or zero current switching (ZCS) through the LLC resonant network, greatly reducing switching losses. Since both the primary and secondary sides are full-bridge structures, DAB-LLC can achieve bidirectional energy flow and is suitable for application scenarios that require bidirectional power transmission.

[0159] See also Figure 4 , the workflow of the adaptive control module includes:

[0160] Step S11, initializing the system: power on self-check to ensure that all modules are working properly; loading historical balancing data and current battery monitoring data;

[0161] Step S12, collecting battery status data: monitoring the voltage, current, and temperature of each battery cell; calculating the state of charge SOC and state of health SOH of each battery cell;

[0162] Step S13, determining whether balancing is required: determining whether there is inconsistency in the battery pack;

[0163] Specifically, whether there is inconsistency in the battery pack is determined based on a preset threshold, while taking factors such as the charge and discharge state and the ambient temperature into consideration.

[0164] Step S14: If it is determined that balancing is required, calculate the battery pack SOC difference: take the difference between the maximum SOC and the minimum SOC as the battery pack SOC difference, and consider the standard deviation of the SOC distribution; if it is determined that balancing is not required, return to step S12;

[0165] Step S15, judging whether the SOC difference of the battery pack is greater than a threshold value, and if so, determining the balancing priority: sorting according to the SOC difference, while considering the health status and temperature of the battery cell;

[0166] Step S16: Select the optimal balancing path and activate the corresponding bidirectional DC-DC module A;

[0167] Specifically, activating the corresponding bidirectional DC-DC module A includes: setting initial operating parameters (such as switching frequency, duty cycle, etc.).

[0168] Step S17, executing energy transmission: monitoring the direction and magnitude of energy flow, and adjusting the working state of the bidirectional DC-DC module A in real time;

[0169] Step S18, determine whether the balancing target is achieved, if so, stop balancing and return to step S12; otherwise, adjust the balancing parameters and return to step S17.

[0170] In specific practice, the step S18 determines whether the equilibrium target is achieved, including:

[0171] Check whether the SOC difference falls within the target range;

[0172] Evaluate balance effectiveness and efficiency.

[0173] In specific practice, adjusting the equalization parameters in step S18 includes:

[0174] Adjust energy transfer rate based on real-time feedback;

[0175] Optimize the working efficiency of bidirectional DC-DC module A.

[0176] Preferably, the step S12 further includes:

[0177] Determine whether the voltage, current, and temperature of each battery cell exceed their respective threshold ranges. If so, trigger the protection mechanism, stop balancing, and issue an alarm;

[0178] The optimal balanced path is selected in step S16, specifically:

[0179] Based on historical balancing data and current battery monitoring data, a deep learning algorithm is used to update the battery model to predict the optimal balancing path and obtain the first optimal balancing path;

[0180] The first optimal balancing path is compared with the second optimal balancing path corresponding to the minimum SOC difference value in step S15, and the optimal balancing path is selected by considering energy transmission efficiency and balancing speed.

[0181] It can be understood that the main advantages of the adaptive balancing strategy of the adaptive control module are:

[0182] 1. Strong adaptability: Ability to dynamically adjust balancing strategy based on battery status and historical data.

[0183] 2. High efficiency: Maximize energy utilization by selecting the optimal balanced path.

[0184] 3. Safe and reliable: Multiple safety monitoring mechanisms are integrated to ensure the safety of the balancing process.

[0185] 4. Good flexibility: The equalization parameters and targets can be adjusted according to different application scenarios.

[0186] Through this fine balancing control, the system can effectively extend the service life of the battery pack, improve overall performance, and adapt to various complex usage environments and working conditions.

[0187] See also Figures 5A-5B The balancing scheduling module realizes the switching of three working states of the bidirectional DC-DC module A through the enable pin EN and the charge and discharge control pin CD of the bidirectional DC-DC module A: the balancing module A is not working, the balancing module A is forward transmitting-charging, and the balancing module A is reverse transmitting-discharging;

[0188] If the charge and discharge control of N-way bidirectional DC-DC module A is realized, 2N-way control signals are required;

[0189] The balancing scheduling module realizes 2N control signal outputs by cascading multiple shift registers.

[0190] Figures 5A-5B Taking the balanced scheduling module scheduling 16-way bidirectional DC-DC module A as an example, as shown in Figure 2, the bidirectional DC-DC module A has two control pins: an enable pin (EN) and a charge and discharge control pin (CD). The enable logic is shown in Table 1 below:

[0191] EN pin status CD Pin Status describe 0 0 Balance module A does not work 1 0 Balancing module A forward transmission-charging 1 1 Balance module A reverse transmission-discharge

[0192] Table 1

[0193] It can be seen that 32 control signals are required to realize the charge and discharge control of the 16-channel bidirectional DC-DC module A. Figures 5A-5B By cascading four 74HC595 shift registers (UC1~UC4), 32-bit data SDI is input one by one through the SER (serial input) pin. With each rising edge of the SRCLK (shift register clock) pulse, the data is shifted one bit to the right and stored in the internal shift register. The data is latched into the output register at the rising edge of the RCLK (storage register clock). Thus, serial input and parallel output are realized, and the driving capability is enhanced through the ULN2803 Darlington transistor (UL1~UL4) array to control the charging and discharging of the 16-way bidirectional DC-DC module A.

[0194] Embodiment 2

[0195] According to an exemplary embodiment, a new energy vehicle includes:

[0196] It includes a battery cluster and the above-mentioned adaptive active balancing battery management system.

[0197] It is understandable that the technical solution provided by this embodiment includes the above-mentioned adaptive active balancing battery management system, and the system realizes the flow of energy between cells by adding bidirectional DC-DC module A, bidirectional DC-DC module B, balancing scheduling module and adaptive control module, and realizes the flow of energy between cells through the balancing strategy of the adaptive control module, which can not only realize the balance inside the battery PACK, but also eliminate the pressure difference of the whole cluster and realize the flow of energy within the whole cluster. The technical solution provided by this embodiment solves the problems of low efficiency, fixed strategy, slow speed and poor reliability existing in traditional active balancing technology, and significantly improves the performance and life of large energy storage systems and electric vehicle battery packs.

[0198] The serial numbers of the above-mentioned embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0199] If the integrated units in the above embodiments are implemented in the form of software functional units and sold or used as independent products, they can be stored in the above computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for enabling one or more computer devices (which may be personal computers, servers, or network devices, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present application.

[0200] In the above embodiments of the present application, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, please refer to the relevant description of other embodiments.

[0201] In the several embodiments provided in the present application, it should be understood that the disclosed client can be implemented in other ways. Among them, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0202] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0203] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0204] The above is only a preferred implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. An adaptive active balancing battery management system, suitable for a single battery cluster, characterized in that: include: Multiple bidirectional DC-DC modules A are integrated in multiple channels on the BMU slave control unit, and each bidirectional DC-DC module A corresponds to one battery cell; A bidirectional DC-DC module B, whose primary side is connected to the positive and negative terminals of the battery cluster respectively, and whose secondary side is connected to the primary sides of each bidirectional DC-DC module A through a common balancing bus, and whose secondary side is connected to the corresponding battery cell; The bidirectional DC-DC module A in the whole cluster performs internal energy transfer in advance. When the internal transfer energy is insufficient, the bidirectional DC-DC module B provides it. If the transfer energy in the whole cluster is surplus, the surplus energy is transferred to the bidirectional DC-DC module B. The battery status monitoring module is integrated in the BMU slave control unit and communicates with all BMU slave control units through the CAN bus to monitor the voltage, current and temperature of each battery cell in real time; The adaptive control module is integrated in the BCU main control unit and is used to predict the optimal balancing path based on the current and historical monitoring data of the battery; The balancing scheduling module is integrated in the BMU slave control unit and is used to adopt a distributed control strategy, communicate with the BCU master control unit through the CAN bus, receive the balancing instructions sent by the adaptive control module, and coordinate the working status of each DC-DC module A.

2. The system according to claim 1, characterized in that The bidirectional DC-DC module A adopts transformer primary winding sampling to realize a voltage-stabilized flyback converter, thereby realizing bidirectional energy transmission between bidirectional DC-DC modules A in the entire cluster; The bidirectional DC-DC module B adopts a dual-path synchronous Buck / Boost circuit and a bidirectional full-bridge resonant converter DAB-LLC to achieve bidirectional energy transmission between a common balancing bus and a battery cluster end.

3. The system according to claim 2, characterized in that Each of the bidirectional DC-DC modules A has the same structure, including: an internal circuit and connected to the internal circuit: The VIN+ pin and the GND_P pin are connected to the positive line and the ground line of the common balanced bus respectively; The CELL+ pin and CELL- pin are connected to the positive and negative electrodes of the single cell respectively; The enable pin EN and the charge and discharge control pin CD are connected to the balancing scheduling module.

4. The system according to claim 3, characterized in that The internal circuit comprises: A transformer T1, a current mode PWM controller U1 connected to the primary side of the transformer T1, and a dedicated converter U2 connected to the secondary side of the transformer T1; Among them, U1 achieves voltage stabilization by sampling the primary winding of transformer T1; The RIN pin of U1 is connected to the VIN+ pin through the bias resistor R11. Whether the function of the RIN pin of U1 is turned on is controlled by the voltage of the OUP pin of U1. The FB pin of U1 is connected between the series-connected resistors R3 and R4; one end of the series-connected resistors R3 and R4 is externally connected to a switching power supply, and the other end is grounded; the switching power supply is also connected to the VDD pin of U1 through the series-connected resistor R8 and the diode D1; By adjusting the resistance values ​​of resistors R3 and R4, the output voltage value of DC-DC module A is changed. The output voltage formula in charging mode is as follows: Among them, Ns and Na are the turns of the secondary output winding and the primary auxiliary winding of transformer T1 respectively; R3 and R4 are sampling resistors of the auxiliary winding; Vref is the internal reference voltage; VF is the junction voltage drop of the output diode.

5. The system according to claim 4, characterized in that U2 switches the charge and discharge mode through the enable pin EN and the charge and discharge control pin CD to realize the function of bidirectional converter; A sampling resistor R19 is connected between the RFB pin and the DRN pin of U2, a diode D4 is connected between the DRN pin and the ground, and the EN pin is grounded through a capacitor C11 and a resistor R20 connected in parallel; In the demagnetization stage, the RFB pin voltage is clamped to the voltage value VIN of the common balanced bus, so that the voltage across the resistor R19 in the demagnetization stage is equal to the voltage difference across the primary main winding of the transformer T1; the output voltage formula in the discharge mode is as follows: Among them, Np and Ns are the number of turns of the primary main winding and the secondary output winding of transformer T1 respectively; R19 is the sampling resistor value between the RFB pin and the DRN pin; VF is the junction voltage drop of the output diode D4, which is 0.3V; When the EN pin is connected to a low level through R20, U2 selects the synchronous rectification function.

6. The system according to claim 1, characterized in that The bidirectional DC-DC module B includes: a dual-path synchronous Buck / Boost circuit and a bidirectional full-bridge resonant converter DAB-LLC; wherein, Inductor L1, field effect transistor S1, field effect transistor S4 form a Buck / Boost circuit, inductor L2, field effect transistor S3, field effect transistor S2 form a Buck / Boost circuit, two-phase staggered control, switching signals are staggered in time, and the phase difference is 180°; The bidirectional full-bridge resonant converter DAB-LLC isolated by transformer Tr1 comprises: transformer Tr1, and a full-bridge rectifier composed of switch tubes S5-S8 connected to the primary side of transformer Tr1, and a full-bridge rectifier composed of switch tubes S9-S12 connected to the secondary side of transformer Tr1; An inductor Lr1 and a capacitor Cr1 are added in series on the primary side of the transformer Tr1, and an inductor Lr1 and a capacitor Cr1 are added in series on the secondary side, so that the DAB-LLC has the same LLC resonant network when working in forward and reverse directions.

7. The system according to claim 1, characterized in that The workflow of the adaptive control module includes: Step S11, initializing the system: power on self-check to ensure that all modules are working properly; loading historical balancing data and current battery monitoring data; Step S12, collecting battery status data: monitoring the voltage, current, and temperature of each battery cell; calculating the state of charge SOC and state of health SOH of each battery cell; Step S13, determining whether balancing is required: determining whether there is inconsistency in the battery pack; Step S14: If it is determined that balancing is required, calculate the battery pack SOC difference: take the difference between the maximum SOC and the minimum SOC as the battery pack SOC difference, and consider the standard deviation of the SOC distribution; if it is determined that balancing is not required, return to step S12; Step S15, judging whether the SOC difference of the battery pack is greater than a threshold value, and if so, determining the balancing priority: sorting according to the SOC difference, while considering the health status and temperature of the battery cell; Step S16: Select the optimal balancing path and activate the corresponding bidirectional DC-DC module A; Step S17, executing energy transmission: monitoring the direction and magnitude of energy flow, and adjusting the working state of the bidirectional DC-DC module A in real time; Step S18, determine whether the balancing target is achieved, if so, stop balancing and return to step S12; otherwise, adjust the balancing parameters and return to step S17.

8. The system according to claim 7, characterized in that After step S12, the following steps are also included: Determine whether the voltage, current, and temperature of each battery cell exceed their respective threshold ranges. If so, trigger the protection mechanism, stop balancing, and issue an alarm; The optimal balanced path is selected in step S16, specifically: Based on historical balancing data and current battery monitoring data, a deep learning algorithm is used to update the battery model to predict the optimal balancing path and obtain the first optimal balancing path; The first optimal balancing path is compared with the second optimal balancing path corresponding to the minimum SOC difference value in step S15, and the optimal balancing path is selected.

9. The system according to claim 3, characterized in that The balancing scheduling module realizes the switching of three working states of the bidirectional DC-DC module A through the enable pin EN and the charge and discharge control pin CD of the bidirectional DC-DC module A: the balancing module A is not working, the balancing module A is forward transmitting-charging, and the balancing module A is reverse transmitting-discharging; If the charge and discharge control of N-way bidirectional DC-DC module A is realized, 2N-way control signals are required; The balancing scheduling module realizes 2N control signal outputs by cascading multiple shift registers.

10. A new energy vehicle, characterized in that: include: It comprises a battery cluster and the adaptive active balancing battery management system as claimed in any one of claims 1 to 9.

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