Method for heating power battery, storage medium, controller, vehicle

Abstract

The application discloses a kind of heating method of power battery, storage medium, controller, vehicle.The method comprises: power test is carried out to power battery at multiple preset rates, and multiple groups of test parameters are obtained;Equivalent circuit model of power battery is constructed, and the internal resistance of power battery is obtained according to test parameters using equivalent circuit model;Multiple groups of undetermined pulse current parameters are obtained, and the target pulse current parameter is determined from multiple groups of undetermined pulse current parameters according to internal resistance using equivalent circuit model;The target pulse current parameter is used to heat power battery by pulse heating circuit.The method can improve the rate and uniformity of heating.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vehicles, in particular to a heating method of a power battery, a storage medium, a controller and a vehicle. BACKGROUND

[0002] Low temperature is an important scenario for electric vehicle application, and charging at low temperature brings many problems to the safety and charging performance of the power battery of the electric vehicle, including polarization of the power battery, lithium extraction of the anode and the like. However, the decline of the kinetic performance of the power battery at low temperature is an inherent property of lithium ion batteries, so rapidly increasing the temperature of the power battery before charging is an effective method to improve the charging performance of the power battery at low temperature. The power battery rapid heating technology includes external heating method and internal heating method.

[0003] The external heating method mainly refers to electric heating, heating of a thermal fluid or use of a phase change material for heating. Electric heating is a method of placing an electric heater around the module or the battery. The positive temperature coefficient heating method is the most widely studied electric heating method, and has the advantage of low cost. However, it has the disadvantages of large size and slow heating speed, which will cause the temperature difference of the battery system to increase. Many external heating methods are easy to control and have been used on electric vehicles, but because of the complexity of the heat conduction process of the external heating method and the need for additional equipment, it has the disadvantages of occupying the space of the module or the vehicle, and the temperature uniformity of the external heating method is worse than that of the internal heating method.

[0004] For internal heating, the related art has embedded nickel foil heating battery, so that the heating rate reaches 1-2℃ / s, the heating rate is insufficient, and the ohmic heat generated in the nickel foil will cause a large temperature gradient. Therefore, the heating rate and the heating uniformity are the current technical difficulties. SUMMARY

[0005] The present application aims to at least partially solve one of the technical problems in the related art. To this end, a first object of the present application is to propose a heating method of a power battery to improve the rate and uniformity of heating.

[0006] A second object of the present application is to propose a computer-readable storage medium.

[0007] A third object of the present application is to propose a controller.

[0008] A fourth object of the present application is to propose a vehicle.

[0009] To achieve the above object, the first aspect of the present application provides a heating method of a power battery, the method comprising: performing power tests of a plurality of preset rates on the power battery to obtain a plurality of groups of test parameters; constructing an equivalent circuit model of the power battery, and obtaining an internal resistance of the power battery according to the test parameters by using the equivalent circuit model; obtaining a plurality of groups of to-be-determined pulse current parameters, and determining target pulse current parameters from the plurality of groups of to-be-determined pulse current parameters according to the internal resistance by using the equivalent circuit model; and heating the power battery by using the target pulse current parameters through a pulse heating circuit.

[0010] To achieve the above object, the second aspect of the present application provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the heating method of the power battery.

[0011] To achieve the above object, the third aspect of the present application provides a controller, which comprises a memory, a processor and a computer program stored in the memory, and the computer program is executed by the processor to implement the heating method of the power battery.

[0012] To achieve the above object, the fourth aspect of the present application provides a vehicle, which comprises a power battery, a pulse heating circuit and the controller.

[0013] According to the heating method of the power battery, the storage medium, the controller and the vehicle, the power battery is tested at a plurality of preset rates to obtain a plurality of groups of test parameters, an equivalent circuit model of the power battery is constructed, and an internal resistance of the power battery is obtained according to the test parameters by using the equivalent circuit model, a plurality of groups of to-be-determined pulse current parameters are obtained, and target pulse current parameters are determined from the plurality of groups of to-be-determined pulse current parameters according to the internal resistance by using the equivalent circuit model, and the power battery is heated by using the target pulse current parameters through the pulse heating circuit, so that the power battery is heated by using the pulse current, and the battery system temperature uniformity and the heating efficiency are improved by using the cell self-heating.

[0014] Additional aspects and advantages of the present application will be made apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a flowchart of the heating method of the power battery according to one or more embodiments;

[0016] Figure 2 is a flowchart of a sub-step of the heating method of the power battery according to one or more embodiments;

[0017] Figure 3is a circuit diagram of a second-order equivalent circuit model according to an example;

[0018] Figure 4 is a flowchart of a sub-step of a heating method of a power battery according to one or more embodiments;

[0019] Figure 5 is a circuit diagram of a pulse heating circuit according to an example;

[0020] Figure 6 is a structural block diagram of a vehicle according to one or more embodiments. DETAILED DESCRIPTION

[0021] Embodiments of the present application are described in detail below with reference to examples shown in the accompanying drawings, wherein the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the accompanying drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0022] A heating method of a power battery, a storage medium, a controller, and a vehicle of an embodiment of the present application are described below with reference to the accompanying drawings.

[0023] Figure 1 is a flowchart of a heating method of a power battery according to an embodiment of the present application.

[0024] As shown in Figure 1 , the heating method of the power battery comprises:

[0025] S11, performing power tests of a plurality of preset rates on the power battery to obtain a plurality of sets of test parameters.

[0026] The power test of the preset rate can be a standard power test, such as 1C, 2C, and 3C. The test parameters can include SOC (State of Charge), current, dynamic voltage, heat generation, temperature, etc.

[0027] S12, constructing an equivalent circuit model of the power battery, and obtaining the internal resistance of the power battery according to the test parameters by using the equivalent circuit model.

[0028] When designing the pulse current, the effects of the current and the frequency on the polarization internal resistance of the battery cell need to be considered.

[0029] The power battery internal resistance increases with the decrease of frequency, and the power battery internal resistance is divided into electronic transfer impedance, charge transfer impedance and charge diffusion impedance. The highest frequency of electronic transfer impedance is 1000 Hz, which means that the electronic transfer process in the battery needs 0.001 s. The highest frequency of charge transfer impedance is 100 Hz, and the highest frequency of charge diffusion impedance is 0.1 Hz. Therefore, for the pulse current, when the pulse frequency is less than 10 s, the charge diffusion process cannot be completed, resulting in that the electrons in the external circuit complete the transfer according to the predetermined path, and the charge diffusion in the battery cell affects the completion of the charge transfer in a short time, so that the surface ion concentration of the double layer is reduced, and the battery system enters a non-steady state. Similarly, when the frequency increases, the charge transfer and diffusion processes in the battery cell are affected, and the electrochemical reaction in the battery cell is reduced.

[0030] The polarization voltage of the power battery increases with the increase of current, which means that the polarization internal resistance of the power battery increases. The large current in the charging process causes the dynamic voltage to move up, which means that the charging pile needs to output more energy to meet the charging current of the power battery. The large current in the charging process causes the dynamic voltage to move down, which means that part of the energy of the output current of the power battery is converted into heat effect. The increase of pulse rate will directly affect the heat generation of the power battery, and the heat generation of the power battery follows Ohm's law.

[0031] Since the internal resistance of different battery cells is designed differently, it is necessary to pre-calibrate the internal resistance of the power battery. The equivalent circuit model of the power battery can be obtained in advance, which can reflect the relationship between the test parameters and the internal resistance, so that the internal resistance of the power battery can be obtained after obtaining the test parameters.

[0032] S13, a plurality of groups of to-be-determined pulse current parameters are obtained, and the equivalent circuit model is used to determine the target pulse current parameter from the plurality of groups of to-be-determined pulse current parameters according to the internal resistance.

[0033] The design of pulse current needs to consider the safety boundary, i.e. lithium precipitation potential. When the pulse current works, the anode potential of the power battery needs to be higher than the lithium precipitation potential. In addition, under the premise of ensuring safety, the heating performance needs to be considered, i.e. the maximum heat generated by the battery cell per unit time.

[0034] For the design of the safety boundary, the available window cutoff voltage of the power battery is usually used as the cutoff voltage boundary of the rapid heating of the battery, so as to ensure that the anode potential of the power battery is not lower than the lithium precipitation potential when the power battery is rapidly heated. For the design of the heating performance, high frequency is the target of performance pursuit, and its advantage is that in the high frequency area, the main source of the internal resistance of the power battery is Ohmic impedance, so the internal electrochemical process of the power battery is not completed, and the capacity loss of the power battery is small.

[0035] Therefore, a plurality of groups of undetermined pulse current parameters can be obtained, the target pulse current parameter is determined from the plurality of groups of undetermined pulse current parameters according to the internal resistance by using the equivalent circuit model, and strategy optimization is performed with the highest and lowest voltages as boundaries and the maximum heat generation as an optimal condition.

[0036] S14, heating the power battery by using the target pulse current parameter through the pulse heating circuit.

[0037] Therefore, by performing power tests on the power battery at a plurality of preset rates, a plurality of groups of test parameters are obtained, an equivalent circuit model of the power battery is constructed, the internal resistance of the power battery is obtained by using the equivalent circuit model according to the test parameters, a plurality of groups of undetermined pulse current parameters are obtained, and the target pulse current parameter is determined from the plurality of groups of undetermined pulse current parameters according to the internal resistance by using the equivalent circuit model. The power battery is heated by using the target pulse current parameter through the pulse heating circuit, so as to realize heating of the power battery by using the pulse current, rapid charging and discharging of the power battery by using the super-high-frequency charging and discharging current, self-heat generation of the power battery by using the polarization effect of the power battery, and improvement of the damage of the power battery caused by the rapid heating technology by using the change characteristics of the internal resistance of the power battery in the time domain. Meanwhile, the battery system temperature uniformity and the heating efficiency are improved by using the self-heat generation of the power battery.

[0038] In an embodiment of the present application, the heating method of the power battery further comprises:

[0039] A1, the power battery is placed at a first preset temperature for a preset time.

[0040] A2, the power battery is charged at a first preset current to a cutoff voltage, then charged at a constant voltage to a cutoff current, and initial capacity calibration is performed.

[0041] A3, the ambient temperature of the power battery is adjusted to a second preset temperature, and the power battery is discharged at a second preset current to realize capacity regulation of the power battery, wherein the second preset temperature is less than the first preset temperature.

[0042] A4, the ambient temperature of the power battery is adjusted to a third preset temperature, and the power battery is heated by using the target pulse current parameter until thermal equilibrium is reached, wherein the third preset temperature is less than the second preset temperature.

[0043] A5, the process of A1-A4 is repeated to obtain a heating cycle number.

[0044] A6, the heating cycle number is compared with a target number, and the durability of the power battery heating is obtained according to the comparison result.

[0045] As an example, in order to perform durability test on the power battery, the battery cell is placed at 25℃ for 2h, each battery is charged at a corresponding 1 / 3C constant current to a cut-off voltage, and then converted to a constant voltage mode to charge to a 0.05C cut-off current to perform initial capacity calibration. Then, the temperature of the temperature box is adjusted to the target temperature, and the battery is discharged at the target temperature at 1 / 3C to adjust the capacity. The temperature of the environmental chamber is adjusted to -30℃, and the power battery is continuously pulse heated until thermal equilibrium is reached, and the cycle is continued.

[0046] It should be noted that, since the internal resistance at different temperatures and different SOCs of the battery needs to be estimated according to the equivalent circuit model, the current at different temperatures and different SOCs is determined by the internal resistance prediction, and thus the second preset temperature can be determined according to actual needs.

[0047] The above capacity adjustment of the power battery is to adjust the battery system to a target SOC.

[0048] When the temperature change is less than 0.05℃ / min, it is determined that thermal equilibrium is reached.

[0049] Therefore, by performing durability test on the power battery, the cut-off voltage boundary can be verified, and after the durability test is completed, the capacity and internal resistance of the battery cell are calibrated, and the damage of the rapid heating technology to the battery system is verified. Moreover, compared with the related art, the test method saves the soaking temperature time before and after the test, and the test efficiency is improved by 200%.

[0050] In an embodiment of the present application, the big data platform can also be used to collect vehicle driving data for many years to form user behavior analysis. According to the temperature data in the behavior analysis, the target value of the vehicle power battery system cycle test can be effectively and accurately calculated.

[0051] In an embodiment of the present application, the equivalent circuit model adopts a second-order equivalent circuit model, and the test parameters include state of charge, current, and dynamic voltage, as shown in Figure 2 , the internal resistance of the power battery is obtained by using the equivalent circuit model according to the test parameters, including:

[0052] S21, the open circuit voltage of the power battery is obtained according to the state of charge.

[0053] S22, a plurality of sets of open circuit voltages and corresponding currents and dynamic voltages are input into the second-order equivalent circuit model to obtain the corresponding internal resistance.

[0054] S23, the final internal resistance of the power battery is obtained according to a plurality of sets of internal resistances, wherein each set of internal resistance includes an ohmic internal resistance and two second-order polarization internal resistances.

[0055] The above-mentioned second-order equivalent circuit model can refer to the example shown in Figure 3 R ohmis the ohmic internal resistance, Uc and Ud are the voltages across the two second-order polarization internal resistances, U OCV is the open circuit voltage, Ut is the dynamic voltage, I is the charge and discharge current of the power battery, C c 、C d are two second-order polarized capacitors, R c 、R d are the two second-order polarization internal resistances.

[0056] In one embodiment of the present invention, the undetermined pulse current parameter is determined based on the charge and discharge control conditions of the equipment to which the power battery belongs, the hardware tolerance during charging and discharging, and / or the charging control conditions of the charging equipment that charges the power battery, and the hardware tolerance during charging.

[0057] In one embodiment of the present invention, see Figure 4 , using an equivalent circuit model to determine target pulse current parameters from multiple sets of undetermined pulse current parameters according to internal resistance, including:

[0058] S41, construct an electrothermal coupling model based on the equivalent circuit model.

[0059] S42, inputting each set of undetermined pulse current parameters into the electrothermal coupling model to obtain the corresponding fitting voltage and heat generation.

[0060] S43 , determining a cutoff voltage range for power battery heating, screening out a fitting voltage within the cutoff voltage range, and recording it as a pending fitting voltage.

[0061] S44, taking the undetermined pulse current parameter corresponding to the undetermined fitting voltage with the maximum heat generation as the target pulse current parameter.

[0062] See also Figure 3 In the example shown, the electrothermal coupling model is expressed as follows:

[0063]

[0064]

[0065] Q n =hS(T bat -T amb )

[0066] Among them, Q is the heat generation power of the power battery, U t =U OCV -U C -U d -IR ohm , R ohm is the ohmic internal resistance, Uc and Ud are the voltages across the two second-order polarization internal resistances, U OCVUt is the open-circuit voltage, I is the charge and discharge current of the power battery, Tabs is the adiabatic temperature of the power battery, Qn is the heat conduction capacity of the power battery, m is the mass of the power battery, c is the specific heat capacity, h is the heat conduction coefficient, S is the surface area of the power battery, Tbat is the actual temperature of the power battery, Tamb is the ambient temperature, and t is time. is the reaction heat, and I(U ocv -U t ) is the Joule heat, wherein the Joule heat includes Ohmic internal resistance and polarization internal resistance heat. is the cell heat generation model. The heat conduction part includes three models, namely a heat conduction model, a heat radiation model, and a convection heat transfer model, wherein the heat conduction model is the main model, and Q n = hS(T bat -T amb ) is the heat conduction model. The voltage range of the fitting voltage is the full window voltage of the power battery system.

[0067] In an embodiment of the present application, referring to Figure 5 , the power battery includes a first battery pack E1 and a second battery pack E2, the negative electrode of the first battery pack E1 is connected with the negative electrode of the second battery pack E2 to form a first node, and the battery heating circuit includes a motor, an inverter, and a switching circuit S; wherein the switching circuit S is connected between the positive electrode of the first battery pack E1 and the positive electrode of the second battery pack E2, the inverter includes three-phase bridge arms, the three-phase bridge arms correspond one-to-one to three-phase coils of the motor, the midpoint of each phase bridge arm is connected with one end of the corresponding phase coil, one end of the three-phase bridge arms is connected with the first node, the other end of any two phase bridge arms is connected with the positive electrode of the first battery pack E1, and the other end of the remaining one phase bridge arm is connected with the positive electrode of the second battery pack E2; the pulse heating circuit is controlled according to target pulse current parameters, including: controlling the switching circuit S to be disconnected, and controlling the on-off of each switch tube in the three-phase bridge arms according to the target pulse current parameters.

[0068] Specifically, the power battery and the motor form six paths, respectively corresponding to the A, B and C three-phase circuits of the motor. During the charging and discharging process, the battery direct current passes through the three paths and is connected in series with the motor, realizing the conversion of direct current and alternating current. In a frequency domain, the first battery pack E1 is in a discharging state, and the direct current enters the motor through the A, B and C three-phase. Through the motor inductive reactance characteristics, a charging current is generated. The charging current enters the second battery pack E2, realizing the charging of the second battery pack E2. Through the action of the high-frequency inverter, the high-frequency charging and discharging of the first and second battery packs is switched, realizing high-frequency pulse rapid heating current. Moreover, through the above-mentioned circuit, the first battery pack E1 and the second battery pack E2 can be simultaneously and symmetrically charged and discharged, and the effective output current of the motor is doubled. Compared with the series battery system rapid heating, the heating efficiency is increased by 4 times. Moreover, due to the adoption of the above-mentioned double-circuit topology, the decrease of heating effect caused by the pulse interval of the pulse current can be avoided. According to the physical environment warehouse test, the heating rate reaches 6℃ / min, which is much higher than the related art, for example, the series battery system rapid heating rate in the related art is 2℃ / min.

[0069] As an example, when the switch tubes V2, V3 and V6 are opened and the switch tubes V1, V4 and V5 are closed, if the first battery pack E1 is discharged, the current enters the motor through the motor C phase, flows out through the motor A and B phases, enters the negative electrode of E1 through the switch tube V4, and enters the positive electrode of E2 through the switch tube V1, charging E2.

[0070] It can be seen that through the control of the switch tubes, the first battery pack E1 can be discharged while the second battery pack E2 is charged. Similarly, by controlling the switch tubes, the first battery pack E1 can be charged while the second battery pack E2 is discharged, or only the first battery pack E1 or the second battery pack E2 can be discharged without charging, or both the first battery pack E1 and the second battery pack E2 can be discharged. The two battery packs can be simultaneously and symmetrically charged and discharged, improving the heating efficiency.

[0071] The voltage of the double module presents a sine wave, and the voltage fluctuation range is 270V-330V (corresponding to the single cell voltage 3.375V-4.125V) in the-5℃ rapid heating test, and the static voltage before rapid heating is 294V. At the same time, the voltage waveform and the current waveform present opposite fluctuation trends, that is, when the current reaches the positive half-axis peak value, the voltage reaches the negative half-axis peak value. From the oscillograph, the peak value of the voltage waveform is 5ms later than that of the current waveform. It can be seen that the battery presents obvious capacitive characteristics during the rapid heating process. It can be inferred that the capacitors near the double layers of the battery core are frequently charged and discharged during the high-frequency pulse current process, thereby providing non-faradic current.

[0072] In summary, the heating method of the power battery in the embodiment of the present application, by the power battery is carried out multiple preset power test, get multiple sets of test parameters, construct the equivalent circuit model of the power battery, and utilize the equivalent circuit model according to test parameters get the internal resistance of the power battery, obtain multiple groups of undetermined pulse current parameters, and utilize the equivalent circuit model according to the internal resistance from multiple groups of undetermined pulse current parameters determine target pulse current parameters, utilize target pulse current parameters through pulse heating circuit to the power battery is heated, to realize the use of pulse current to the power battery is heated, high-frequency pulse technology utilizes the change characteristic of the internal resistance of the battery in the time domain, improves the ohmic resistance ratio, thereby improve the damage of the speed heating technology to the battery. Meanwhile, using the self-heating of the battery improves the temperature uniformity and the efficiency of the battery system. Through high-frequency current, the time of electrochemical reaction of the battery is reduced, and the safety of the speed heating technology is effectively improved. Moreover, by combining the voltage upper and lower limits and the heating speed during the battery speed heating to determine the pulse current, the safety and efficiency of the speed heating can be met. Moreover, by designing the double-circuit topology of the battery system, introducing the series-parallel conversion of the battery system, and connecting the 6-circuit topology design with the three-phase motor, the conversion between direct current and alternating current is realized. Through circuit modification, two battery groups can be simultaneously and symmetrically charged and discharged, and the heating efficiency is improved by 4 times.

[0073] Further, the present application provides a computer readable storage medium.

[0074] In the embodiment of the present application, a computer readable storage medium has a computer program stored thereon, and the computer program is executed by a processor to implement the heating method of the power battery described above.

[0075] The computer readable storage medium of the embodiment of the present application can realize the heating of the power battery by the heating method of the power battery described above, the high-frequency pulse technology utilizes the change characteristic of the internal resistance of the battery in the time domain, improves the ohmic resistance ratio, thereby improves the damage of the speed heating technology to the battery. Meanwhile, using the self-heating of the battery improves the temperature uniformity and the efficiency of the battery system. Through high-frequency current, the time of electrochemical reaction of the battery is reduced, and the safety of the speed heating technology is effectively improved. Moreover, by combining the voltage upper and lower limits and the heating speed during the battery speed heating to determine the pulse current, the safety and efficiency of the speed heating can be met. Moreover, by designing the double-circuit topology of the battery system, introducing the series-parallel conversion of the battery system, and connecting the 6-circuit topology design with the three-phase motor, the conversion between direct current and alternating current is realized. Through circuit modification, two battery groups can be simultaneously and symmetrically charged and discharged, and the heating efficiency is improved by 4 times.

[0076] Further, the present application provides a controller.

[0077] In the embodiment of the present application, the controller comprises a memory, a processor and a computer program stored in the memory, and the computer program is executed by the processor to implement the heating method of the power battery.

[0078] The controller of the embodiment of the present application can realize heating of the power battery by the pulse current, the high-frequency pulse technology utilizes the change characteristics of the internal resistance of the battery cell in the time domain, the proportion of the ohmic resistance is improved, and the damage of the rapid heating technology to the battery is improved. Meanwhile, the battery system temperature uniformity and the heating efficiency are improved by using the self-heating of the battery cell. The time of the electrochemical reaction of the battery cell is reduced by the high-frequency current, the safety of the rapid heating technology is effectively improved by heating the battery cell by the alternating current resistance. Moreover, the pulse current is determined by combining the upper and lower limits of the voltage and the heating speed of the battery during rapid heating, so that the safety and efficiency of the rapid heating can be met. Moreover, by designing the double-circuit topology of the battery system, introducing the series-parallel conversion of the battery system, and connecting the 6-circuit topology design with the three-phase motor, the conversion between direct current and alternating current is realized. Through the circuit modification, two battery packs can be simultaneously and symmetrically charged and discharged, and the heating efficiency is improved by 4 times.

[0079] Further, the present application provides a vehicle.

[0080] Figure 6 is a structural diagram of the vehicle of the embodiment of the present application.

[0081] As shown in Figure 6 , the vehicle 100 comprises a power battery 101, a pulse heating circuit 102 and a controller 103.

[0082] The vehicle of the embodiment of the present application can realize heating of the power battery by the pulse current through the controller of the above embodiment, the high-frequency pulse technology utilizes the change characteristics of the internal resistance of the battery cell in the time domain, the proportion of the ohmic resistance is improved, and the damage of the rapid heating technology to the battery is improved. Meanwhile, the battery system temperature uniformity and the heating efficiency are improved by using the self-heating of the battery cell. The time of the electrochemical reaction of the battery cell is reduced by the high-frequency current, the safety of the rapid heating technology is effectively improved by heating the battery cell by the alternating current resistance. Moreover, the pulse current is determined by combining the upper and lower limits of the voltage and the heating speed of the battery during rapid heating, so that the safety and efficiency of the rapid heating can be met. Moreover, by designing the double-circuit topology of the battery system, introducing the series-parallel conversion of the battery system, and connecting the 6-circuit topology design with the three-phase motor, the conversion between direct current and alternating current is realized. Through the circuit modification, two battery packs can be simultaneously and symmetrically charged and discharged, and the heating efficiency is improved by 4 times.

[0083] It is to be appreciated that the above description and the examples that follow are intended to be illustrative only and that changes can be made to the description and examples without departing from the scope of the application. Note also that the use of particular brand names in the description is solely for illustration and should not be construed as an endorsement of such brands.

[0084] It should be understood that aspects of the application can be implemented in hardware, software, firmware or a combination thereof. In the above embodiments, various steps or methods can be implemented in software or firmware that is stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any of the following technologies, known in the art, can be used: a hybrid of the technologies mentioned above, discrete logic circuitry having logic gates for implementing logic functions upon data signals, application specific integrated circuits having appropriate combinational logic gates, programmable gate arrays (PGA), field programmable gate arrays (FPGA), and so forth.

[0085] In the description of the present application, reference has been made to the use of terms such as "one embodiment", "some embodiments", "an example", "a specific example" or "some examples" means that a particular feature, structure, material or characteristic is included in at least one embodiment or example of the present application. The illustrative examples given are not necessarily to be construed as preferred or advantageous or with the exclusion of other equally valid examples that can be particularly adapted to a given application. Furthermore, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the application to the exact construction and operation described. Accordingly, appropriate changes are intended to be incorporated within the scope of the present application.

[0086] In the description of the application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application.

[0087] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise explicitly specified and limited.

[0088] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0089] In the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature, which can be direct contact between the first and second features, or indirect contact between the first and second features through an intermediate medium. Moreover, the first feature "above", "above" and "above" the second feature can be directly above or obliquely above the first feature, or only indicate that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature can be directly below or obliquely below the first feature, or only indicate that the horizontal height of the first feature is less than that of the second feature.

[0090] Although the embodiments of the present application have been shown and described above, it should be understood that the above embodiments are exemplary and cannot be understood as a limitation on the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application.

Claims

1. A method for heating a power battery, characterized in that: The method comprises: Performing power tests on the power battery at multiple preset rates to obtain multiple sets of test parameters; Constructing an equivalent circuit model of the power battery, and using the equivalent circuit model to obtain the internal resistance of the power battery according to the test parameters; Acquire multiple groups of pending pulse current parameters, and determine target pulse current parameters from the multiple groups of pending pulse current parameters according to the internal resistance using the equivalent circuit model; heating the power battery through a pulse heating circuit using the target pulse current parameter; The equivalent circuit model adopts a second-order equivalent circuit model, the test parameters include state of charge, current, and dynamic voltage, and obtaining the internal resistance of the power battery according to the test parameters using the equivalent circuit model includes: Obtaining an open circuit voltage of the power battery according to the state of charge; Inputting multiple sets of open-circuit voltages and their corresponding currents and dynamic voltages into the second-order equivalent circuit model to obtain corresponding internal resistances; Obtaining a final internal resistance of the power battery according to the multiple groups of internal resistances, wherein each group of internal resistances includes an ohmic internal resistance and two second-order polarization internal resistances; The method of determining the target pulse current parameter from multiple groups of pending pulse current parameters using the equivalent circuit model according to the internal resistance includes: Constructing an electrothermal coupling model based on the equivalent circuit model; Inputting each group of the undetermined pulse current parameters into the electrothermal coupling model to obtain the corresponding fitting voltage and heat generation; determining a cutoff voltage range for heating the power battery, and selecting a fitting voltage within the cutoff voltage range as a pending fitting voltage; The undetermined pulse current parameter corresponding to the undetermined fitting voltage with the maximum heat generation is used as the target pulse current parameter.

2. The method for heating a power battery according to claim 1, characterized in that: The undetermined pulse current parameter is determined according to the charge and discharge control conditions of the equipment to which the power battery belongs, the hardware tolerance during charge and discharge, and / or the charge control conditions of the charging equipment that charges the power battery, and the hardware tolerance during charge.

3. The method for heating a power battery according to claim 1, wherein: The electrothermal coupling model is expressed by the following formula: Q n =hS(T bat -T amb ) Wherein, Q is the heat generation power of the power battery, U t =U OCV -U C -U d -IR ohm , R ohm is the ohmic internal resistance, Uc and Ud are the voltages across the two second-order polarization internal resistances, U OCV is the open circuit voltage, Ut is the dynamic voltage, I is the charge and discharge current of the power battery, Tabs is the adiabatic temperature of the power battery, Qn is the thermal conductivity of the power battery, m is the mass of the power battery, c is the specific heat capacity, h is the thermal conductivity coefficient, S is the surface area of ​​the power battery, Tbat is the actual temperature of the power battery, Tamb is the ambient temperature, and t is time.

4. The method for heating a power battery according to claim 1, wherein: The power battery includes a first battery pack and a second battery pack, the negative electrode of the first battery pack is connected to the negative electrode of the second battery pack to form a first node, and the battery heating circuit includes: a motor, an inverter and a switching circuit; The switching circuit is connected between the positive electrode of the first battery pack and the positive electrode of the second battery pack, and the inverter includes a three-phase bridge arm, each of which corresponds to the three-phase coil of the motor. The midpoint of the bridge arm of each phase is connected to one end of the corresponding phase coil, one end of the three-phase bridge arm is connected to the first node, the other end of the bridge arm of any two phases is connected to the positive electrode of the first battery pack, and the other end of the bridge arm of the remaining phase is connected to the positive electrode of the second battery pack; The controlling the pulse heating circuit according to the target pulse current parameter includes: The switch circuit is controlled to be disconnected, and each switch tube in the three-phase bridge arm is controlled to be on and off according to the target pulse current parameter.

5. The method for heating a power battery according to claim 1, wherein: The method further comprises: A1. Allowing the power battery to stand at a first preset temperature for a preset time; A2. Constant-current charging the power battery to a cut-off voltage at a first preset current, then constant-voltage charging to a cut-off current, and performing initial capacity calibration; A3. Adjusting the ambient temperature of the power battery to a second preset temperature and discharging the power battery at a second preset current to adjust the capacity of the power battery, wherein the second preset temperature is lower than the first preset temperature; A4. Adjusting the ambient temperature of the power battery to a third preset temperature, and heating the power battery using the target pulse current parameter until thermal equilibrium is reached, wherein the third preset temperature is lower than the second preset temperature; A5. Repeat the process of A1-A4 to obtain the number of heating cycles; A6. Compare the number of heating cycles with the target number, and obtain the heating durability of the power battery according to the comparison result.

6. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method for heating a power battery according to any one of claims 1 to 5 is implemented.

7. A controller, characterized in that: The method comprises a memory, a processor and a computer program stored in the memory, wherein when the computer program is executed by the processor, the method for heating the power battery according to any one of claims 1 to 6 is implemented.

8. A vehicle, characterized in that: include: A power battery, a pulse heating circuit and a controller as claimed in claim 7.

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