Pulse tail end voltage simulation method and device, equipment and storage medium

Abstract

The invention discloses a pulse end voltage simulation method, device and equipment and a storage medium, and belongs to the technical field of battery simulation. The method comprises the following steps: acquiring battery cell test data and thermal parameters; fitting an equivalent RC circuit according to the battery cell test data to obtain an equivalent electric model; according to the thermal parameters of the target battery pack, performing fitting to obtain a convective heat transfer coefficient of the target battery pack, and constructing an equivalent thermal model of the target battery pack based on the convective heat transfer coefficient; and coupling the equivalent thermal model and the equivalent electric model of the target battery pack to simulate the tail end voltage under the pulse working condition to obtain a simulation result. According to the scheme, the terminal voltage under different pulse working conditions can be simulated, and the simulation efficiency is improved on the basis of ensuring the simulation accuracy.

Description

Technical Field

[0001] This invention relates to the field of battery simulation technology, and in particular to a method, apparatus, device, and storage medium for simulating pulse end voltage. Background Technology

[0002] With the rapid development of new energy vehicles and energy storage systems, the charge-discharge performance, thermal characteristics, and safety of power batteries have become crucial for battery system design and control. Furthermore, in the production and design process of power batteries, accurate prediction of the terminal voltage is necessary to evaluate the power output capability of the battery pack and design the vehicle's energy management strategy.

[0003] During battery operation, the terminal voltage is influenced by a variety of factors, including the battery's state of charge (SOC), current, temperature, internal resistance, and polarization effects. To simulate the terminal voltage, a corresponding electrical and thermal model of the battery is typically established, tightly coupled to comprehensively describe the battery's electrochemical behavior and thermal characteristics. However, in real-world operating conditions, power batteries are not always in a continuous, steady-state state. Transient conditions such as kinetic energy recovery, high-rate charging, or rapid acceleration can cause short-duration charge-discharge pulses within the battery. Under these pulsed conditions, the transient accumulation and distribution of heat within the battery become more complex.

[0004] Therefore, under the above-mentioned pulsed operating conditions, the thermal model is extremely complex. If the traditional electrothermal coupling simulation method is still used, the amount of computation will increase significantly, resulting in a decrease in simulation efficiency. Summary of the Invention

[0005] Therefore, it is necessary to provide a method, apparatus, device, and storage medium for simulating pulse terminal voltage to address the above problems, thereby improving the simulation efficiency of pulse terminal voltage.

[0006] On the one hand, this application provides a method for simulating pulse terminal voltage, the method comprising: Acquire cell test data and thermal parameters; the cell test data includes the voltage-current relationship of the cells in the target battery pack under various operating conditions; and at least one of the SOC and temperature of the target battery pack is different in two different operating conditions; the thermal parameters include the specific heat capacity and thermal conductivity of the cells in the target battery pack; An equivalent RC circuit is fitted based on the cell test data to obtain an equivalent electrical model; Based on the thermal parameters of the target battery pack, the convective heat transfer coefficient of the target battery pack is obtained by fitting, and an equivalent thermal model of the target battery pack is constructed based on the convective heat transfer coefficient. The equivalent thermal model and equivalent electrical model of the target battery pack are coupled to simulate the terminal voltage under pulsed operating conditions and obtain simulation results.

[0007] In one optional implementation, the step of fitting the convective heat transfer coefficient of the target battery pack based on its thermal parameters includes: A heat conduction equation is constructed based on the specific heat capacity and thermal conductivity. Based on the heat conduction equation and the spatial structure of the target battery pack, calculate the predicted temperature response curves of the target battery pack under different convective heat transfer coefficients. The convective heat transfer coefficient of the target battery pack is determined by comparing the predicted temperature response curve with the actual temperature response curve of the target battery pack.

[0008] In one optional implementation, the equivalent thermal model includes a heat transfer term, a thermal power term, and a temperature change term, wherein the temperature change term is equal to the difference between the thermal power term and the heat transfer term. The heat transfer term is the ratio of the temperature difference between the target battery pack and the environment to the convective heat transfer coefficient; the thermal power term is used to characterize the electrothermal power of the target battery pack; and the temperature change term is used to characterize the product of the temperature change rate of the target battery pack and its heat capacity.

[0009] In one optional implementation, the equivalent RC circuit includes a series ohmic internal resistance and an RC circuit structure. The step of fitting an equivalent RC circuit based on the cell test data to obtain an equivalent electrical model includes: Construct an initial electrical model corresponding to the equivalent RC circuit; the initial electrical model includes an open-circuit voltage term, a terminal voltage term, an ohmic resistance term represented by the ohmic internal resistance, and a polarization resistance term represented by the RC circuit structure; the open-circuit voltage term is equal to the sum of the terminal voltage term, the ohmic resistance term, and the polarization resistance term; Based on the cell test data, voltage drop curves under various operating conditions are generated; By fitting the voltage drop curves under each operating condition to the initial electrical model, the ohmic resistance value of the initial electrical model under different operating conditions and the component parameters in the RC circuit structure are obtained to generate the equivalent electrical model.

[0010] In one optional implementation, the RC parameters of the initial electrical model under different operating conditions are obtained, and the voltage drop curves under each operating condition are fitted to generate the equivalent electrical model, including: Based on the ohmic resistance values ​​of the initial electrical model under different operating conditions and the component parameters in the RC circuit structure, an equivalent model of the battery cell is constructed. Obtain the electrical components in the target battery pack; the electrical components are all electronic devices in the target battery pack other than the battery cells; the internal resistance of the electrical components is a constant value; Based on the circuit connection relationship between electrical components and battery cells, the equivalent model of the battery cell is transformed into the equivalent electrical model.

[0011] In one alternative implementation, the equivalent RC circuit is a second-order RC circuit.

[0012] In one optional implementation, simulating the terminal voltage under pulsed operating conditions and obtaining simulation results includes: Obtain the simulated operating conditions of the target battery pack; Based on the simulated operating conditions of the target battery pack, the operating parameters of the target battery pack are determined; the operating parameters include whether the target battery pack is charging / discharging and the current ratio of the target battery pack. The operating parameters of the target battery pack are input into the coupled model of the equivalent thermal model and the equivalent electrical model to obtain the terminal voltage variation curve of the target battery pack under the pulse condition.

[0013] In another aspect, a pulse-end voltage simulation device is provided, the device comprising: The data acquisition module is used to acquire cell test data and thermal parameters; the cell test data includes the voltage-current relationship of the cells in the target battery pack under various operating conditions; and at least one of the SOC and temperature of the target battery pack is different in two different operating conditions; the thermal parameters include the specific heat capacity and thermal conductivity of the cells in the target battery pack. An electrical model acquisition module is used to fit an equivalent RC circuit based on the cell test data to obtain an equivalent electrical model; The thermal model acquisition module is used to fit the convective heat transfer coefficient of the target battery pack according to the thermal parameters of the target battery pack, and to construct an equivalent thermal model of the target battery pack based on the convective heat transfer coefficient. The simulation module is used to couple the equivalent thermal model and the equivalent electrical model of the target battery pack to simulate the terminal voltage under pulsed operating conditions and obtain simulation results.

[0014] On the other hand, an electronic device is provided, comprising: The system includes a memory and a processor, which are interconnected. The memory stores computer instructions, and the processor executes these computer instructions to perform the aforementioned pulse-end voltage simulation method.

[0015] In another aspect, a computer-readable storage medium is provided, on which computer instructions are stored, the computer instructions being used to cause a computer to execute the above-described pulse-end voltage simulation method.

[0016] Compared with the prior art, the technical solution provided in this application has the following advantages: In simulating the terminal voltage under pulse conditions, this application first acquires cell test data and thermal parameters. The cell test data includes the voltage-current relationship of the cells in the target battery pack under various operating conditions, while the thermal parameters include the specific heat capacity and thermal conductivity of the cells. Then, an equivalent RC circuit is fitted based on the cell test data to characterize the complex polarization resistance in the target battery pack, thus obtaining an equivalent electrical model. Next, based on the thermal parameters of the target battery pack, a convective heat transfer coefficient is fitted to construct an equivalent thermal model of the target battery pack. The equivalent thermal model and the equivalent electrical model are then coupled to simulate the terminal voltage under pulse conditions, yielding simulation results. This approach uses an equivalent thermal model to characterize the terminal voltage at different SOCs and temperatures, and then fits a simple equivalent thermal model using the convective heat transfer coefficient. Coupling these two models allows for the simulation of terminal voltages under different pulse conditions, improving simulation efficiency while ensuring accuracy. Attached Figure Description

[0017] Figure 1 A flowchart of a pulse-end voltage simulation method according to an embodiment of the present invention is shown; Figure 2 A flowchart illustrating a pulse end voltage simulation method provided in an embodiment of the present invention is shown. Figure 3 A schematic diagram of the equivalent model of the second-order RC circuit involved in the embodiments of this application is shown; Figure 4 A schematic diagram of the pressure drop curve involved in an embodiment of this application is shown; Figure 5 A schematic diagram of a thermal model according to an embodiment of this application is shown; Figure 6 The figure shown is a simulation result diagram of an end voltage according to an embodiment of this application; Figure 7 A structural block diagram of a pulse end voltage simulation device according to an embodiment of this application is shown; Figure 8 This is a schematic diagram of the structure of an electronic device provided in an optional embodiment of the present invention. Detailed Implementation

[0018] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0019] With the rapid development of new energy vehicles and energy storage systems, the charge-discharge performance, thermal characteristics, and safety of power batteries have become key factors in battery system design and control. Accurate prediction of the battery's terminal voltage is crucial for evaluating the power pack's power output capability and optimizing vehicle energy management strategies.

[0020] In a battery, the terminal voltage (also known as the output voltage) refers to the voltage measured at the end of the circuit, i.e., the load, which is the potential difference between the positive and negative terminals of the power supply.

[0021] Power batteries in electric vehicles and energy storage systems are frequently subjected to dynamic loads, such as acceleration, braking, and hill climbing. The terminal voltage directly reflects the interaction between the battery's instantaneous current and factors such as SOC (State of Charge) and temperature. Simulations can predict the battery's voltage response curves under different loads and ambient temperatures, allowing for assessment of whether the battery can meet high-power output demands. This avoids insufficient power due to low voltage or battery damage due to excessive voltage. Furthermore, terminal voltage prediction directly impacts SOC / SOH estimation, thermal management, and safety assurance.

[0022] As mentioned above, during battery operation, its terminal voltage is influenced by a variety of factors, including the battery's state of charge (SOC), operating current, temperature, internal resistance, and polarization effects. To achieve accurate simulation of the battery's terminal voltage, it is usually necessary to establish an electrical model and a thermal model of the battery and couple them together. This electrothermal coupling model comprehensively describes the battery's electrochemical behavior and thermal characteristics.

[0023] However, in actual operating conditions, power batteries are often not in a continuous, steady-state charging and discharging state. Transient conditions such as kinetic energy recovery, high-rate charging, or rapid acceleration can cause short-term charging and discharging pulses in the battery, resulting in drastic fluctuations in the terminal voltage. Under such pulsed conditions, the transient accumulation and distribution of heat inside the battery becomes more complex. If traditional electrothermal coupling simulation methods are still used, the computational load will increase significantly, leading to reduced simulation efficiency and making it difficult to meet real-time requirements.

[0024] To address the aforementioned problems, this application provides a method for simulating pulse end voltage. Figure 1A flowchart of a pulse-end voltage simulation method according to an embodiment of the present invention is shown, as follows: Figure 1 As shown, the pulse end voltage simulation method provided in this embodiment of the invention includes the following steps: Step 101: Obtain cell test data and thermal parameters.

[0025] The cell test data includes the voltage and current relationship of the cells in the target battery pack under various operating conditions; and at least one of the SOC and temperature of the target battery pack is different in two different operating conditions; the thermal parameters include the specific heat capacity and thermal conductivity of the cells in the target battery pack.

[0026] In this embodiment of the application, before performing the end voltage simulation under pulse conditions for the target battery pack, it is first necessary to obtain the data of each cell in the target battery pack, namely the cell test data and thermal parameters.

[0027] Among them, the cell test data can be obtained through something like DCR (Direct Current Internal Resistance). DC internal resistance refers to the resistance generated inside a battery or electronic component when a DC current passes through it. Simply put, it involves applying a constant DC current to the object under test and measuring the voltage across the measuring device to obtain its DC internal resistance value.

[0028] However, in this embodiment, each cell in the target battery pack is not necessarily under a constant DC operating condition during actual operation. Furthermore, in addition to the normal ohmic internal resistance, the cell also contains internal electrochemical polarization resistance. Therefore, in this embodiment, short-pulse currents can be applied to cells under different operating conditions during the traditional DCR process, and the terminal voltage of the cell under different operating conditions (i.e., different SOCs and different temperatures) can be recorded to reflect the dynamic voltage response characteristics of the cell under different SOCs and temperatures. In summary, the cell test data actually includes the voltage change curves of the cell under short-pulse currents of different magnitudes, thus comprehensively characterizing the electrical behavior of the cell under various operating states.

[0029] In addition, in this embodiment, the thermal parameters include the specific heat capacity and thermal conductivity of the battery cell. Specific heat capacity describes the temperature change characteristics of the battery per unit mass, while thermal conductivity describes the efficiency of heat transfer within the battery. Optionally, these thermal parameters can be obtained by temperature testing of the battery cell.

[0030] Step 102: Fit an equivalent RC circuit based on the cell test data to obtain an equivalent electrical model; the equivalent electrical model is used to characterize the terminal voltage of the target battery pack under different operating conditions.

[0031] As can be seen from the above steps, the cell test data includes the voltage-time curves of the cell under different short-pulse currents. If a circuit model is constructed such that the voltage-time relationship under different short-pulse currents satisfies the cell test data, then the circuit model can be considered to characterize the physical properties of the cell under specific operating conditions.

[0032] In this embodiment, considering that the voltage response of a battery is a process with multiple time constants, simply put, a cell can exhibit a specific open-circuit voltage under a specific state of charge and temperature. This open-circuit voltage cannot be completely converted into a terminal voltage to provide load operation; it is also affected by ohmic voltage drop and polarization voltage drop. Ohmic voltage drop can be considered as pure resistive loss caused by the electrolyte, electrode materials, etc.; while polarization voltage drop is caused by electrochemical polarization and concentration polarization. Ohmic voltage drop is generally a fixed value that does not change with time, while polarization voltage drop generally decays over time. Therefore, an RC circuit is suitable for fitting the polarization voltage drop.

[0033] In the embodiments of this application, since the polarization voltage drop includes electrochemical voltage drop and concentration voltage drop, and the time decay characteristics of the two voltage drops are different, generally the voltage drop caused by rapid charge transfer polarization decays faster (e.g., at the millisecond level), while the voltage drop decay caused by concentration polarization is usually slower (e.g., at the second level), the two need to be characterized by different RC circuit terms. Therefore, in the embodiments of this application, the equivalent RC circuit can be a second-order RC circuit.

[0034] Specifically, the RC circuit in this application embodiment may include an open-circuit voltage source OCV, an ohmic resistor R1, a response resistor and a response capacitor in at least one RC module, and the ohmic resistor R1 and at least one RC module are connected in series between the positive and negative terminals of the open-circuit voltage source OCV; wherein the open-circuit voltage source is used to characterize the open-circuit voltage provided by the cell under a specific state of charge and temperature, while the ohmic resistor R1 is used to fit the ohmic internal resistance of the cell, and at least one RC module can be used to simulate polarization effect and transient effect.

[0035] After constructing the corresponding RC circuit, the open-circuit voltage of the open-circuit voltage source OCV, the ohmic internal resistance R1, and the electrical response relationship between at least one RC module can be obtained based on the circuit structure. Then, based on the cell test data obtained above, the resistance and capacitance values ​​in the RC circuit can be assigned (e.g., using the least squares method) to fit the optimal response resistance and response capacitance, thereby obtaining the equivalent RC circuit corresponding to the cell.

[0036] After obtaining the equivalent RC circuit corresponding to the battery cell, the equivalent electrical model of the target battery pack can be obtained based on the connection relationship between the battery cells and the connection relationship between the battery cells and other electronic components in the target battery pack.

[0037] Optionally, in the embodiments of this application, the electrical response of the above-mentioned battery cell may be inconsistent under different SOC states or different temperature states. Therefore, for different SOC states or different temperature states, it is necessary to fit different equivalent RC circuits. That is, the equivalent electrical model of the target battery pack includes several sub-models corresponding to different SOC state ranges and different temperature ranges.

[0038] Step 103: Based on the thermal parameters of the target battery pack, the convective heat transfer coefficient of the target battery pack is obtained by fitting, and an equivalent thermal model of the target battery pack is constructed based on the convective heat transfer coefficient.

[0039] In this embodiment, the thermal parameters of the target battery pack include the specific heat capacity and thermal conductivity of the cells within the battery pack. Specific heat capacity describes the temperature change characteristics of the battery per unit mass, while thermal conductivity describes the efficiency of heat transfer within the battery. Since the target battery pack is composed of individual cells, obtaining the specific heat capacity and thermal conductivity of each cell, and then considering the current and voltage conditions of each cell under different operating conditions, allows for the determination of the heat generation of each cell. Combining this with the spatial relationships between the cells, a three-dimensional thermal management model of the target battery pack can be established, enabling the calculation of the temperature distribution and thermal field variation patterns under different operating conditions.

[0040] The above method can calculate the temperature change of the target battery pack under different operating conditions. The temperature change of the target battery pack is related to the working state of each cell in the target battery pack. Therefore, by coupling the two, the temperature and voltage changes of the target battery pack under various conditions can be accurately analyzed.

[0041] However, when using the aforementioned thermal model to calculate the temperature change of the target battery pack under pulsed operating conditions, the current, being a pulsed signal, changes drastically over a short period. Therefore, under pulsed operating conditions, the transient current leads to a dramatic change in heating power over time, requiring a recalculation of the spatiotemporal response of the temperature field. This, in turn, necessitates correcting the response capacitance, response resistance, and open-circuit voltage in the equivalent electrical model. Furthermore, the aforementioned thermal model is a three-dimensional thermal management model, which typically requires extremely complex algorithms such as finite element analysis to analyze temperature changes. Therefore, coupling the three-dimensional thermal management model with the equivalent electrical model results in a massive computational burden.

[0042] Therefore, in this embodiment, the three-dimensional thermal management model is fitted with the convective heat transfer coefficient, which is a parameter that measures the heat transfer capacity between a fluid and a solid surface. It is defined as the amount of heat transferred per unit time per unit area when the temperature difference is 1℃. In other words, by using the convective heat transfer coefficient, this embodiment simplifies the discretized cell heat transfer state into a simple heat transfer process between the target battery pack and the outside world. While ensuring that the equivalent thermal model obtained by fitting the convective heat transfer coefficient can basically characterize the temperature change of the target battery pack, the computational complexity is significantly reduced, and the real-time performance and feasibility of electrothermal coupling simulation are improved.

[0043] Step 104: Couple the equivalent thermal model and equivalent electrical model of the target battery pack to simulate the terminal voltage under pulsed operating conditions and obtain simulation results.

[0044] Once the equivalent thermal model and equivalent electrical model of the target battery pack are obtained, the equivalent electrical model outputs transient current and terminal voltage, while the equivalent thermal model updates the cell temperature based on the Joule heat and polarization heat generated by the current. Furthermore, the temperature change affects the electrical model parameters such as resistance and capacitance, thus achieving electrothermal coupling feedback.

[0045] Therefore, in this embodiment of the application, when it is necessary to simulate the target battery pack under pulsed operating conditions, the initial state of the target battery pack (e.g., the initial SOC and initial temperature) can be determined first, and then the pulsed current sequence (e.g., the current waveform under acceleration / braking conditions) can be input. Then, the electrothermal coupling model obtained by coupling the equivalent thermal model and the equivalent electrical model can be used to calculate the terminal voltage of each time step. Finally, the simulation results can be output, where the simulation results may include the terminal voltage of each cell, the overall terminal voltage of the battery pack, and the cell temperature change curve, etc.

[0046] In summary, this application, when simulating the terminal voltage under pulse conditions, first acquires cell test data and thermal parameters. The cell test data includes the voltage-current relationship of the cells in the target battery pack under various operating conditions, with at least one of the SOC and temperature of the target battery pack differing between two different operating conditions. The thermal parameters include the specific heat capacity and thermal conductivity of the cells in the target battery pack. Then, an equivalent RC circuit is fitted based on the cell test data to characterize the complex polarization resistance in the target battery pack, thus obtaining an equivalent electrical model. Next, based on the thermal parameters of the target battery pack, a convective heat transfer coefficient is fitted to construct an equivalent thermal model of the target battery pack. The equivalent thermal model and the equivalent electrical model of the target battery pack are then coupled to simulate the terminal voltage under pulse conditions, yielding simulation results. This approach uses an equivalent thermal model to characterize the terminal voltage under different SOCs and temperatures, and then fits a simple equivalent thermal model using the convective heat transfer coefficient. Coupling these two models allows for the simulation of terminal voltages under different pulse conditions, improving simulation efficiency while ensuring accuracy.

[0047] Figure 2 A schematic flowchart of a pulse end voltage simulation method according to an embodiment of the present invention is shown. Figure 2 As shown, the method includes: Step 201: Obtain cell test data and thermal parameters.

[0048] In this embodiment of the application, the cell test data includes the voltage-current relationship of the cells in the target battery pack under various operating conditions; and at least one of the SOC and temperature of the target battery pack is different in two different operating conditions; the thermal parameters include the specific heat capacity and thermal conductivity of the cells in the target battery pack.

[0049] Optionally, the thermal parameters in this embodiment can be obtained by testing the battery cell using an Accelerating Rate Calorimeter (ARC). Simply put, the battery cell can be placed in an insulated cavity. When the battery cell generates heat (such as during charging, discharging, or thermal abuse), the ARC system automatically controls the temperature rise to maintain the cavity and battery cell at the same temperature, thus ensuring that the heat released by the battery cell is not carried away by the outside. By recording the temperature change over time, the temperature rise rate per unit time can be measured, thereby calculating parameters such as the battery cell's heat release power, specific heat capacity, thermal conductivity, and thermal runaway initiation temperature.

[0050] Optionally, in this embodiment of the application, the thermal parameter also includes the cell mass in the target battery pack.

[0051] Furthermore, in this embodiment of the application, it is also necessary to obtain in advance the electronic device structure distribution in the target battery pack, such as the number and distribution of the battery cells in the target battery pack, as well as the number and distribution of other electronic devices (such as relays, shunts, etc.) constituting the target battery pack.

[0052] Step 202: Construct the initial electrical model corresponding to the equivalent RC circuit.

[0053] In this embodiment, the initial electrical model is a mathematical model of an equivalent RC circuit. The equivalent RC circuit includes a series-connected ohmic internal resistance and an RC circuit structure.

[0054] In simple terms, this equivalent RC circuit can fit the impedance in the battery cell as a series of ohmic internal resistance and polarization internal resistance; whereby the polarization internal resistance can be characterized by at least one RC circuit structure.

[0055] At this point, the initial electrical model includes an open-circuit voltage term, a terminal voltage term, an ohmic resistance term, and a polarization resistance term. The open-circuit voltage term is equal to the sum of the terminal voltage term, the ohmic resistance term represented by the ohmic internal resistance, and the polarization resistance term represented by the RC circuit structure. The ohmic resistance term is used to characterize the voltage across the ohmic resistance of the battery cell. The polarization resistance term is used to characterize the dynamic polarization voltage of the RC branch in the equivalent RC circuit.

[0056] Specifically, if the RC circuit structure includes two-order RC branches, the mathematical representation of the initial electrical model is as follows:

[0057]

[0058]

[0059]

[0060] in, This is the end voltage term, used to characterize the end voltage of the battery cell; This is the open-circuit voltage term, used to characterize the open-circuit voltage of the battery cell at a specific temperature and SOC state; For ohmic resistance; and For the polarization resistance term, where The dynamic polarization voltage on the first-order RC branch; This refers to the dynamic polarization voltage on the second-order RC branch; For input current; It is an ohmic resistor; The response resistance of the first-order RC branch; The response resistance of the second-order RC branch; and It is a time constant; = ; = ;and The response capacitance of the first-order RC branch; It is the response capacitance of the second-order RC branch.

[0061] If the initial current I(0) = 0, then the above terminal voltage can be simplified as follows:

[0062] Figure 3 A schematic diagram of the equivalent model of a second-order RC circuit involved in an embodiment of this application is shown.

[0063] like Figure 3 As shown, the battery cell can provide open-circuit voltage at a specific temperature and under a specific SOC state. The internal resistance of the battery cell can be replaced by a fixed resistor. This indicates that the polarization resistance term in the battery cell can be characterized by a two-RC branch structure, by... and Setting it to an appropriate size allows the first-order RC branch to characterize a rapidly changing electrochemical voltage drop; by... and Setting it to an appropriate value allows the second-order RC branch to characterize the concentration voltage drop with a relatively slow rate of change; while the open-circuit voltage, after successively passing through the ohmic voltage drop, electrochemical voltage drop, and concentration voltage drop, can characterize the terminal voltage to the outside world. .

[0064] It should be noted that since the above model is calculated based on the parameters of the battery cell, the terminal voltage... It actually refers to the terminal voltage exhibited by a single cell in the target battery pack.

[0065] Step 203: Generate voltage drop curves under various operating conditions based on the cell test data.

[0066] Please refer to Figure 4 The diagram illustrates a pressure drop curve related to an embodiment of this application. Figure 4 As shown, during cell testing, when the circuit is not conducting, the measured terminal voltage of the cell is the open-circuit voltage. The voltage is approximately 3.3V. During cell testing, a short pulse current can be sent to the cell at a specific time point, at which point the ohmic internal resistance... A corresponding voltage drop will be generated instantaneously, and then the polarization internal resistance will gradually change over time, causing the measured terminal voltage of the cell to change over time.

[0067] Step 204: Fit the voltage drop curves under various operating conditions using the initial electrical model to obtain the ohmic resistance value of the initial electrical model under different operating conditions and the component parameters in the RC circuit structure, so as to generate an equivalent electrical model.

[0068] In this embodiment, the initial electrical model is fitted with the voltage drop curves under various operating conditions to obtain the element parameters and resistance values ​​of the RC circuit structure under each operating condition. At this point, by setting different values ​​for the element parameters and resistance values ​​of the RC circuit structure, the initial electrical model can characterize the terminal voltage of the battery cell under different operating conditions. However, the target battery pack may contain multiple battery cells, and in addition to the battery cells, the target battery pack also includes many electrical components with internal resistance that can affect the overall terminal voltage of the target battery pack.

[0069] For example, components with internal resistance in the target battery pack may also include aluminum busbars, copper busbars, fuses, relays, shunts, mechanical fasteners (such as the connection impedance between bolts and copper busbars), and solder joints.

[0070] In one possible implementation, the equivalent electrical model can be obtained in the following way: Based on the ohmic resistance values ​​of the initial electrical model under different operating conditions and the component parameters in the RC circuit structure, an equivalent model of the battery cell is constructed; the electrical components in the target battery pack are obtained; the electrical components are all electronic components in the target battery pack other than the battery cell; the internal resistance of the electrical components is a constant value; based on the circuit connection relationship between the electrical components and the battery cell, the equivalent model of the battery cell is transformed into the equivalent electrical model.

[0071] In other words, in order to simplify calculations, the internal resistance of electrical components can be set to a fixed value in this embodiment of the application. For example, the welding internal resistance can be set to 0, the connection impedance between the bolt and the copper busbar can be set to 0.6mΩ, and the internal resistance of the relay, fuse and shunt can be set to 0.5mΩ. The specific setting value of the internal resistance of the electrical components can be set according to the size and number of electrical components in the target battery pack.

[0072] After determining the internal resistance of each electrical component and the initial electrical model of each cell, the two can be combined according to the circuit connection relationship in the target battery pack to obtain the equivalent electrical model of the target battery pack. Since the initial electrical model of each cell is based on a second-order RC circuit, the final equivalent RC circuit is also essentially a second-order RC circuit.

[0073] Step 205: Based on the thermal parameters of the target battery pack, the convective heat transfer coefficient of the target battery pack is obtained by fitting, and an equivalent thermal model of the target battery pack is constructed based on the convective heat transfer coefficient.

[0074] Figure 5 A schematic diagram of a thermal model according to an embodiment of this application is shown. Figure 5 As shown, for node This represents the temperature of the target battery pack. The output of the thermal model reflects the current temperature of the battery. represents the heat generation power inside the battery.

[0075] This represents the heat generation power inside the battery, caused by losses during the charging and discharging process, i.e., the heat generated by the current passing through the internal resistance of the battery.

[0076] It is the battery's heat capacity, determined by the battery's mass. and specific heat capacity Composition represents the energy required for a battery to change temperature.

[0077] and It is the resistance to thermal convection conduction between the battery and the environment, where, This refers to the heat exchange area of ​​the battery. The convective heat transfer coefficient describes the heat exchange capacity between the battery surface and the surrounding environment (such as air or coolant).

[0078] Ambient temperature affects the battery's temperature distribution and thermal management performance. Heat transfer between the battery and the external environment causes the battery temperature to approach the ambient temperature.

[0079] And for Figure 5 For the thermal model shown, it can follow the following formula:

[0080] This formula describes the change in battery temperature over time, and consists of two parts: 1. The heat generated inside the battery is characterized by: 2. The heat exchanged between the battery and the external environment through thermal convection (as determined by the convective heat transfer coefficient). Decide).

[0081] The heat generation power inside a battery can generally be considered to be caused by its internal resistance. In this embodiment, the heat generation power of the battery can be calculated using the total internal resistance obtained from a second-order RC model. The heat transfer area of ​​the battery, the ambient temperature, and the battery temperature can all be obtained through measurement or simulation. Therefore, the convective heat transfer coefficient of the target battery pack can be obtained by fitting these parameters. After obtaining the convective heat transfer coefficient of the target battery pack, the temperature change of the target battery pack can be predicted using the formula of the aforementioned thermal model.

[0082] Step 206: Couple the equivalent thermal model and equivalent electrical model of the target battery pack to simulate the terminal voltage under pulsed operating conditions and obtain simulation results.

[0083] Optionally, in this embodiment, the simulation conditions of the target battery pack can be obtained first; then, based on the simulation conditions of the target battery pack, the operating parameters of the target battery pack can be determined; the operating parameters include whether the target battery pack is charging / discharging and the current ratio of the target battery pack; finally, the operating parameters of the target battery pack are input into the coupled model of the equivalent thermal model and the equivalent electrical model to obtain the terminal voltage change curve of the target battery pack under the pulse condition.

[0084] In this embodiment of the application, after obtaining the equivalent thermal model and the equivalent electrical model of the target battery pack, since the temperature change of the battery in the equivalent thermal model is related to the thermal power of the battery, that is, related to the current, and the terminal voltage in the equivalent electrical model is also related to the temperature of the cell, the equivalent thermal model and the equivalent electrical model can be coupled according to the associated parameters to obtain an electrothermal coupling model.

[0085] Before performing simulations based on the electrothermal coupling model, it is first necessary to determine the operating parameters of the target battery under specific simulation conditions. This includes determining whether the target battery pack is in a charging or discharging state, the discharge rate (e.g., 1C or 3C), and whether it is a pulsed charging condition. Once the operating condition of the target battery pack is determined (taking 3C pulse charging as an example), the pulse current can be input into the equivalent electrical model to calculate the real-time changes in the terminal voltage, and the corresponding real-time heat term can be output. Then, the temperature change of the target battery pack is calculated in real-time using the equivalent thermal model, and this temperature change is fed back to the equivalent electrical model to update the parameters. Through this process, the curve of the terminal voltage of the target battery pack changing over time under pulsed conditions can be obtained, thus achieving the simulation of the terminal voltage under pulsed conditions.

[0086] Figure 6 A simulation result diagram of an end voltage according to an embodiment of this application is shown. Figure 6As shown, based on this simulation model, the simulated voltage and the measured voltage are compared at 25℃, 10s, 50%, 30%, and 10% SOC, respectively. The comparison shows that the simulation error of the pulse discharge end at room temperature is <3% using the scheme shown in the embodiments of this application.

[0087] In summary, this application, when simulating the terminal voltage under pulse conditions, first acquires cell test data and thermal parameters. The cell test data includes the voltage-current relationship of the cells in the target battery pack under various operating conditions, while the thermal parameters include the specific heat capacity and thermal conductivity of the cells in the target battery pack. Then, an equivalent RC circuit is fitted based on the cell test data to characterize the complex polarization resistance in the target battery pack, thereby obtaining an equivalent electrical model. Next, based on the thermal parameters of the target battery pack, the convective heat transfer coefficient is fitted to construct an equivalent thermal model of the target battery pack. At this point, the equivalent thermal model and the equivalent electrical model of the target battery pack are coupled to simulate the terminal voltage under pulse conditions, thus obtaining the simulation results. The above scheme uses an equivalent thermal model to characterize the terminal voltage at different SOCs and temperatures, and then fits a simple equivalent thermal model using the convective heat transfer coefficient. Coupled with the equivalent thermal model, the terminal voltage under different pulse conditions can be simulated, improving simulation efficiency while ensuring simulation accuracy.

[0088] Figure 7 A structural block diagram of a pulse-end voltage simulation device according to an embodiment of this application is shown. Figure 7 As shown, the device includes: The data acquisition module 701 is used to acquire cell test data and thermal parameters; the cell test data includes the voltage-current relationship of the cells in the target battery pack under various operating conditions; and at least one of the SOC and temperature of the target battery pack is different in two different operating conditions; the thermal parameters include the specific heat capacity and thermal conductivity of the cells in the target battery pack. The electrical model acquisition module 702 is used to fit an equivalent RC circuit based on the cell test data to obtain an equivalent electrical model. The thermal model acquisition module 703 is used to fit the convective heat transfer coefficient of the target battery pack according to the thermal parameters of the target battery pack, and to construct an equivalent thermal model of the target battery pack based on the convective heat transfer coefficient. The simulation module 704 is used to couple the equivalent thermal model and the equivalent electrical model of the target battery pack to simulate the terminal voltage under pulsed operating conditions and obtain simulation results.

[0089] In one optional implementation, the thermal model acquisition module is used to construct a heat conduction equation based on the specific heat capacity and thermal conductivity. Based on the heat conduction equation and the spatial structure of the target battery pack, calculate the predicted temperature response curves of the target battery pack under different convective heat transfer coefficients. The convective heat transfer coefficient of the target battery pack is determined by comparing the predicted temperature response curve with the actual temperature response curve of the target battery pack.

[0090] In one optional implementation, the equivalent thermal model includes a heat transfer term, a thermal power term, and a temperature change term, wherein the temperature change term is equal to the difference between the thermal power term and the heat transfer term. The heat transfer term is the ratio of the temperature difference between the target battery pack and the environment to the convective heat transfer coefficient; the thermal power term is used to characterize the electrothermal power of the target battery pack; and the temperature change term is used to characterize the product of the temperature change rate of the target battery pack and its heat capacity.

[0091] In one optional implementation, the equivalent RC circuit includes a series ohmic internal resistance and an RC circuit structure; the electrical model acquisition module is used for: Construct an initial electrical model corresponding to the equivalent RC circuit; the initial electrical model includes an open-circuit voltage term, a terminal voltage term, an ohmic resistance term represented by the ohmic internal resistance, and a polarization resistance term represented by the RC circuit structure; the open-circuit voltage term is equal to the sum of the terminal voltage term, the ohmic resistance term, and the polarization resistance term; Based on the cell test data, voltage drop curves under various operating conditions are generated; By fitting the voltage drop curves under each operating condition to the initial electrical model, the ohmic resistance value of the initial electrical model under different operating conditions and the component parameters in the RC circuit structure are obtained to generate the equivalent electrical model.

[0092] In one optional implementation, the electrical model acquisition module is used to acquire the RC parameters of the initial electrical model under different operating conditions, fit the voltage drop curves under each operating condition, and obtain the equivalent model of the battery cell. Obtain the electrical components in the target battery pack; the electrical components are all electronic devices in the target battery pack other than the battery cells; the internal resistance of the electrical components is a constant value; Based on the circuit connection relationship between electrical components and battery cells, the equivalent model of the battery cell is transformed into the equivalent electrical model.

[0093] In one alternative implementation, the equivalent RC circuit is a second-order RC circuit.

[0094] In one optional implementation, the simulation module is used to obtain the simulated operating conditions of the target battery pack; Based on the simulated operating conditions of the target battery pack, the operating parameters of the target battery pack are determined; the operating parameters include whether the target battery pack is charging / discharging and the current ratio of the target battery pack. The operating parameters of the target battery pack are input into the coupled model of the equivalent thermal model and the equivalent electrical model to obtain the terminal voltage variation curve of the target battery pack under the pulse condition.

[0095] In summary, this application, when simulating the terminal voltage under pulse conditions, first acquires cell test data and thermal parameters. The cell test data includes the voltage-current relationship of the cells in the target battery pack under various operating conditions, while the thermal parameters include the specific heat capacity and thermal conductivity of the cells in the target battery pack. Then, an equivalent RC circuit is fitted based on the cell test data to characterize the complex polarization resistance in the target battery pack, thereby obtaining an equivalent electrical model. Next, based on the thermal parameters of the target battery pack, the convective heat transfer coefficient is fitted to construct an equivalent thermal model of the target battery pack. At this point, the equivalent thermal model and the equivalent electrical model of the target battery pack are coupled to simulate the terminal voltage under pulse conditions, thus obtaining the simulation results. The above scheme uses an equivalent thermal model to characterize the terminal voltage at different SOCs and temperatures, and then fits a simple equivalent thermal model using the convective heat transfer coefficient. Coupled with the equivalent thermal model, the terminal voltage under different pulse conditions can be simulated, improving simulation efficiency while ensuring simulation accuracy.

[0096] Further functional descriptions of the above modules and units are the same as those in the corresponding embodiments described above, and will not be repeated here.

[0097] The system in this embodiment is presented in the form of functional units. Here, a unit refers to an ASIC (Application Specific Integrated Circuit) circuit, a processor and memory that execute one or more software or fixed programs, and / or other devices that can provide the above functions.

[0098] Please see Figure 8 , Figure 8 This is a schematic diagram of the structure of an electronic device provided in an optional embodiment of the present invention. The electronic device can be a computer device used to achieve, for example... Figure 7The illustrated pulse-end voltage simulation device includes one or more processors 10, a memory 20, and interfaces for connecting the components, including high-speed and low-speed interfaces. The components communicate with each other via different buses and can be mounted on a common motherboard or otherwise as required. The processors can process instructions executed within the electronic device, including instructions stored in or on memory to display graphical information of a GUI on external input / output devices (such as display devices coupled to the interfaces).

[0099] The processor 10 may further include a hardware chip. This hardware chip may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The programmable logic device may be a complex programmable logic device (CAMP), a field-programmable gate array (FPGA), a general-purpose array logic (GDA), or any combination thereof.

[0100] The memory 20 stores instructions executable by at least one processor 10 to cause the at least one processor 10 to perform the method shown in the above embodiments.

[0101] The memory 20 may include a program storage area and a data storage area. The program storage area may store the operating system and applications required for at least one function; the data storage area may store data created by the use of the electronic device based on the display of a mini-program landing page. Furthermore, the memory 20 may include high-speed random access memory (RAM), and may also include non-transient memory, such as at least one disk storage device, flash memory device, or other non-transient solid-state storage device. The memory 20 may include volatile memory, such as RAM; the memory may also include non-volatile memory, such as flash memory, hard disk, or solid-state drive; the memory 20 may also include combinations of the above types of memory.

[0102] The electronic device also includes a communication interface 30 for communicating with other devices or communication networks.

[0103] This invention also provides a computer-readable storage medium. The methods described above according to embodiments of the invention can be implemented in hardware or firmware, or implemented as computer code that can be recorded on a storage medium, or implemented as computer code downloaded via a network and originally stored on a remote storage medium or a non-transitory machine-readable storage medium and then stored on a local storage medium. Thus, the methods described herein can be processed by software stored on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. The storage medium can be a magnetic disk, optical disk, read-only memory, random access memory, flash memory, hard disk, or solid-state drive, etc.; further, the storage medium can also include combinations of the above types of memory. It is understood that computers, processors, microprocessor controllers, or programmable hardware include storage components capable of storing or receiving software or computer code, which, when accessed and executed by the computer, processor, or hardware, implements the methods shown in the above embodiments.

[0104] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0105] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

[0106] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0107] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for simulating pulse terminal voltage, characterized in that, The method includes: Acquire cell test data and thermal parameters; the cell test data includes the voltage-current relationship of the cells in the target battery pack under various operating conditions; the thermal parameters include the specific heat capacity and thermal conductivity of the cells in the target battery pack. An equivalent RC circuit is fitted based on the cell test data to obtain an equivalent electrical model; the equivalent electrical model is used to characterize the terminal voltage of the target battery pack under different operating conditions. Based on the thermal parameters of the target battery pack, the convective heat transfer coefficient of the target battery pack is obtained by fitting, and an equivalent thermal model of the target battery pack is constructed based on the convective heat transfer coefficient. The equivalent thermal model and equivalent electrical model of the target battery pack are coupled to simulate the terminal voltage under pulsed operating conditions and obtain simulation results.

2. The method according to claim 1, characterized in that, The step of fitting the convective heat transfer coefficient of the target battery pack based on its thermal parameters includes: A heat conduction equation is constructed based on the specific heat capacity and thermal conductivity. Based on the heat conduction equation and the spatial structure of the target battery pack, calculate the predicted temperature response curves of the target battery pack under different convective heat transfer coefficients. The convective heat transfer coefficient of the target battery pack is determined by comparing the predicted temperature response curve with the actual temperature response curve of the target battery pack.

3. The method according to claim 2, characterized in that, The equivalent thermal model includes a heat transfer term, a thermal power term, and a temperature change term, wherein the temperature change term is equal to the difference between the thermal power term and the heat transfer term; The heat transfer term is the ratio of the temperature difference between the target battery pack and the environment to the convective heat transfer coefficient; the thermal power term is used to characterize the electrothermal power of the target battery pack; and the temperature change term is used to characterize the product of the temperature change rate of the target battery pack and its heat capacity.

4. The method according to any one of claims 1 to 3, characterized in that, The equivalent RC circuit includes a series-connected ohmic internal resistance and an RC circuit structure. The step of fitting an equivalent RC circuit based on the cell test data to obtain an equivalent electrical model includes: Construct an initial electrical model corresponding to the equivalent RC circuit; the initial electrical model includes an open-circuit voltage term, a terminal voltage term, an ohmic resistance term represented by the ohmic internal resistance, and a polarization resistance term represented by the RC circuit structure; the open-circuit voltage term is equal to the sum of the terminal voltage term, the ohmic resistance term, and the polarization resistance term; Based on the cell test data, voltage drop curves under various operating conditions are generated; By fitting the voltage drop curves under each operating condition to the initial electrical model, the ohmic resistance value of the initial electrical model under different operating conditions and the component parameters in the RC circuit structure are obtained to generate the equivalent electrical model.

5. The method according to claim 4, characterized in that, The step of obtaining the ohmic resistance values ​​of the initial electrical model under different operating conditions and the component parameters in the RC circuit structure to generate the equivalent electrical model includes: Based on the ohmic resistance values ​​of the initial electrical model under different operating conditions and the component parameters in the RC circuit structure, an equivalent model of the battery cell is constructed. Obtain the electrical components in the target battery pack; the electrical components are all electronic devices in the target battery pack other than the battery cells; the internal resistance of the electrical components is a constant value; Based on the circuit connection relationship between electrical components and battery cells, the equivalent model of the battery cell is transformed into the equivalent electrical model.

6. The method according to claim 5, characterized in that, The equivalent RC circuit is a second-order RC circuit.

7. The method according to any one of claims 1 to 3, characterized in that, The simulation of the terminal voltage under pulsed operating conditions, and the resulting simulation results, include: Obtain the simulated operating conditions of the target battery pack; Based on the simulated operating conditions of the target battery pack, the operating parameters of the target battery pack are determined; the operating parameters include whether the target battery pack is charging / discharging and the current ratio of the target battery pack. The operating parameters of the target battery pack are input into the coupled model of the equivalent thermal model and the equivalent electrical model to obtain the terminal voltage variation curve of the target battery pack under the pulse condition.

8. A pulse-end voltage simulation device, characterized in that, The device includes: The data acquisition module is used to acquire cell test data and thermal parameters; the cell test data includes the voltage-current relationship of the cells in the target battery pack under various operating conditions; the thermal parameters include the specific heat capacity and thermal conductivity of the cells in the target battery pack. An electrical model acquisition module is used to fit an equivalent RC circuit based on the cell test data to obtain an equivalent electrical model; The thermal model acquisition module is used to fit the convective heat transfer coefficient of the target battery pack according to the thermal parameters of the target battery pack, and to construct an equivalent thermal model of the target battery pack based on the convective heat transfer coefficient. The simulation module is used to couple the equivalent thermal model and the equivalent electrical model of the target battery pack to simulate the terminal voltage under pulsed operating conditions and obtain simulation results.

9. An electronic device, characterized in that, include: A memory and a processor are interconnected, the memory storing computer instructions, and the processor executing the computer instructions to perform the pulse end voltage simulation method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions for causing the computer to execute the pulse-end voltage simulation method according to any one of claims 1 to 7.

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