Battery heating method, heating device and heating system

Abstract

The application provides a battery heating method, a heating device and a heating system, which can effectively heat a power battery and has high heating efficiency. The heating method comprises an application to a heating circuit, the heating circuit is connected with a battery and is used for outputting a heating current to the battery, the heating current is used for heating the battery, and the heating method comprises the following steps: obtaining a polarization parameter of the battery; determining a frequency of the heating current according to the polarization parameter and a peak current of the heating circuit, so that an amplitude of the heating current does not exceed the peak current; and controlling the heating circuit to output the heating current with the frequency to the battery.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular, to a method, device and system for heating a battery. Background Technology

[0002] Due to their advantages such as high energy density, rechargeability, safety, and environmental friendliness, power batteries are widely used in new energy vehicles, consumer electronics, energy storage systems, and other fields.

[0003] However, the use of power batteries in low-temperature environments is limited. For example, the discharge capacity of power batteries degrades significantly at low temperatures, and they cannot be charged. To ensure normal operation of the power batteries, heating is necessary in low-temperature environments. How to effectively heat power batteries has become a pressing issue. Summary of the Invention

[0004] This application provides a method, device, and system for heating a battery, which can effectively heat a power battery and has high heating efficiency.

[0005] In a first aspect, a method for heating a battery is provided, applied to a heating circuit connected to the battery, for outputting a heating current to the battery, the heating current being used to heat the battery, the heating method comprising: acquiring polarization parameters of the battery; determining the frequency of the heating current based on the polarization parameters and a peak current of the heating circuit, such that the amplitude of the heating current does not exceed the peak current; and controlling the heating circuit to output a heating current having the frequency to the battery.

[0006] In this embodiment, the heating circuit outputs an alternating current to the battery to heat it. The frequency of the heating current is related to the heating efficiency, therefore it is necessary to determine the optimal frequency of the heating current. When determining the optimal frequency of the heating current, the peak current of the heating circuit is used as a condition, thereby preventing the amplitude of the heating current from exceeding the peak current of the heating circuit and avoiding damage to other components in the heating circuit during the heating process.

[0007] In one implementation, determining the frequency of the heating current based on the polarization parameter and the peak current of the heating circuit, so that the amplitude of the heating current does not exceed the peak current, includes: determining the frequency of the heating current based on the polarization parameter, the peak current and the equilibrium potential of the lithium plating reaction of the battery, so that the amplitude of the heating current does not exceed the peak current and the polarization voltage of the battery does not exceed the equilibrium potential.

[0008] In this embodiment, when determining the optimal frequency of the heating current, the peak current of the heating circuit and the equilibrium potential of the lithium plating reaction are used as conditions. This can prevent the amplitude of the heating current from exceeding the peak current of the heating circuit, thus avoiding damage to other components in the heating circuit. It can also prevent the lithium plating phenomenon caused by the polarization voltage of the battery exceeding the equilibrium potential of the lithium plating reaction, thereby ensuring the safety of the battery.

[0009] These polarization parameters include, for example, the polarization internal resistance and polarization capacitance of the battery.

[0010] In one implementation, determining the frequency of the heating current based on the polarization parameters, the peak current, and the equilibrium potential of the lithium plating reaction of the battery includes: determining the angular frequency of the heating current based on the polarization internal resistance, the polarization capacitance, the peak current, and the equilibrium potential; and determining the frequency of the heating current based on the angular frequency of the heating current.

[0011] Since alternating current is used to heat the battery, in this embodiment, the angular frequency of the alternating current can be determined based on the battery's polarization resistance and polarization capacitance, as well as the peak current of the heating circuit and the equilibrium potential of the lithium plating reaction. Then, the frequency of the alternating current can be determined based on the angular frequency. The calculation is simple and easy to implement.

[0012] In one implementation, determining the angular frequency of the heating current based on the polarization internal resistance, the polarization capacitance, the peak current, and the equilibrium potential includes: determining the angular frequency of the heating current based on the following formula: [R1 / (1+jωR1C1)]×I A =X×U e，1 Where R1 is the internal resistance of the polarization, C1 is the polarization capacitance, and I... A For this peak current, U e，1 ω is the equilibrium potential of the battery at its current state of charge (SOC), ω is the angular frequency of the heating current, and X is a preset value, which is greater than 0 and less than or equal to 1.

[0013] In this embodiment, given that the polarization resistance R1 and polarization capacitance C1 of the battery are known in advance, the formula [R1 / (1+jωR1C1)]×I is used. A =X×U e，1 This allows us to obtain the optimal angular frequency ω of the heating current, and further, the optimal frequency of the heating current. The battery's polarization voltage Ux = [R1 / (1+jωR1C1)] × I. We set a parameter X less than or equal to 1, and make Ux = X × U e，1 This ensures that the polarization voltage Ux does not exceed the equilibrium potential U. e，1 This prevents the battery's polarization voltage from exceeding the equilibrium potential U of the lithium plating reaction. e，1This leads to lithium plating. Simultaneously, the current I in Ux=[R1 / (1+jωR1C1)]×I is limited to be equal to the peak current I of the heating circuit. A This prevents the amplitude of the heating current from exceeding the peak current I of the heating circuit. A This avoids damage to other components in the heating circuit during the heating process.

[0014] In one implementation, determining the frequency of the heating current based on the angular frequency includes: determining the frequency of the heating current based on ω = 2πf, where ω is the angular frequency of the heating current and f is the frequency of the heating current.

[0015] In one implementation, obtaining the polarization parameters of the battery includes: determining an equation representing the relationship between the open-circuit voltage, terminal voltage, and current of the battery based on the battery's equivalent circuit, the equation being associated with the polarization internal resistance and the polarization capacitance; sampling the open-circuit voltage, terminal voltage, and current multiple times during the heating process to obtain multiple sets of sampled data; and determining the polarization internal resistance and the polarization capacitance based on the equation according to the multiple sets of sampled data.

[0016] In this embodiment, by establishing an equivalent circuit for the battery, an equation is obtained to represent the relationship between the battery's open-circuit voltage, terminal voltage, and current. This equation is related to the battery's polarization resistance and polarization capacitance. Thus, by sampling the battery's open-circuit voltage, terminal voltage, and current multiple times beforehand during the heating process, multiple sets of sampled data are obtained. Substituting these multiple sets of sampled data into the equation, the battery's polarization resistance and polarization capacitance can be obtained. The calculation is simple and easy to implement. Therefore, given the battery's polarization resistance and polarization capacitance beforehand, the angular frequency of the heating current can be obtained according to the aforementioned formula, and further, the frequency of the heating current can be derived.

[0017] In one implementation, the equivalent circuit is a first-order Thevenin equivalent circuit, and the equation is: U0=[R1 / (1+jωR1C1)]×I A +I×R0+U, where U0 is the open-circuit voltage of the battery at the current SOC and temperature, U is the terminal voltage, I is the current, R1 is the polarization internal resistance, C1 is the polarization capacitance, and R0 is the ohmic internal resistance of the battery.

[0018] In this embodiment, the polarization resistance and polarization capacitance of the battery are determined by establishing a first-order Thevenin equivalent circuit and its corresponding model formula. The model is simple and easy to implement. Of course, other circuit models can also be used to determine the polarization resistance and polarization capacitance of the battery in this embodiment.

[0019] In one implementation, the polarization resistance and polarization capacitance are determined based on the equation according to the multiple sets of sampled data, including: converting the equation into a differential polynomial U0(k)-U(k)=k1×[U0(k-1)-U(k-1)]+k2×I(k)-k3×I(k-1), where k1=R1C1 / (T+R1C1), k2=[R0R1C1+T(R0+R1)] / (T+R1C1), k3=R0R1C1 / (T+R1C1), and U0(k) and U0(k-1) are the open-circuit voltages obtained from the k-th and (k-1)-th sampling, respectively. Sample data, U(k) and U(k-1) are the sampled data of the terminal voltage obtained by the kth and k-1th sampling respectively, I(k) and I(k-1) are the sampled data of the current obtained by the kth and k-1th sampling respectively, T is the sampling time interval, and k is a positive integer greater than 1; based on the multiple sets of sampled data, k1, k2 and k3 are determined based on the polynomial; based on k1, k2 and k3, the polarization internal resistance and the polarization voltage are determined to be R1=(k2-k3) / (1-k1)-k3 / k1 and C1=(k1×k1×T) / [k1×(k2-k3)-k3×(1-k1)].

[0020] In this embodiment, by transforming the equation corresponding to the battery's equivalent circuit into a differential polynomial, the imaginary part in the equation can be effectively removed, thereby facilitating the determination of the battery's polarization resistance and polarization capacitance using sampled data of open-circuit voltage, terminal voltage, and current.

[0021] In one implementation, the heating current is alternating current, and the waveform of the alternating current is any one of pulse wave, square wave, triangle wave and sine wave.

[0022] In one implementation, the heating circuit includes a power source connected to the battery.

[0023] In one implementation, the heating circuit includes an energy storage unit and a voltage conversion module connected between the energy storage unit and the battery.

[0024] In a second aspect, a heating device for a battery is provided, applied to a heating circuit connected to the battery, for outputting a heating current to the battery for heating the battery. The heating device includes: a processing module for acquiring the polarization parameters of the battery and determining the frequency of the heating current based on the polarization parameters and the peak current of the heating circuit, so that the amplitude of the heating current does not exceed the peak current; and a control module for controlling the heating circuit to output the heating current with the specified frequency to the battery.

[0025] In one implementation, the processing module is specifically used to: determine the frequency of the heating current based on the polarization parameter, the peak current, and the equilibrium potential of the lithium plating reaction of the battery, so that the amplitude of the heating current does not exceed the peak current and the polarization voltage of the battery does not exceed the equilibrium potential.

[0026] In one implementation, the polarization parameters include the battery's polarization internal resistance and polarization capacitance.

[0027] In one implementation, the processing module is specifically used to: determine the angular frequency of the heating current based on the polarization internal resistance, the polarization capacitance, the peak current and the equilibrium potential; and determine the frequency of the heating current based on the angular frequency of the heating current.

[0028] In one implementation, the processing module is specifically used to: determine the angular frequency of the heating current based on the following formula, according to the polarization internal resistance, the polarization capacitance, the peak current, and the equilibrium potential: [R1 / (1+jωR1C1)]×I A =X×U e，1 Where R1 is the internal resistance of the polarization, C1 is the polarization capacitance, and I... A For this peak current, U e，1 ω is the equilibrium potential of the battery at its current state of charge (SOC), ω is the angular frequency of the heating current, and X is a preset value, which is greater than 0 and less than or equal to 1.

[0029] In one implementation, the processing module is specifically used to: determine the frequency of the heating current based on ω = 2πf, where ω is the angular frequency of the heating current and f is the frequency of the heating current.

[0030] In one implementation, the processing module is specifically used to: determine an equation representing the relationship between the open-circuit voltage, terminal voltage, and current of the battery based on the equivalent circuit of the battery, the equation being associated with the polarization internal resistance and the polarization capacitance; sample the open-circuit voltage, terminal voltage, and current multiple times during the heating process to obtain multiple sets of sampled data; and determine the polarization internal resistance and the polarization capacitance based on the equation according to the multiple sets of sampled data.

[0031] In one implementation, the equivalent circuit is a first-order Thevenin equivalent circuit, and the equation is: U0=[R1 / (1+jωR1C1)]×I A +I×R0+U, where U0 is the open-circuit voltage of the battery at the current SOC and temperature, U is the terminal voltage, I is the current, R1 is the polarization internal resistance, C1 is the polarization capacitance, and R0 is the ohmic internal resistance of the battery.

[0032] In one implementation, the processing module is specifically used to: convert the equation into a differential polynomial U0(k)-U(k)=k1×[U0(k-1)-U(k-1)]+k2×I(k)-k3×I(k-1), where k1=R1C1 / (T+R1C1), k2=[R0R1C1+T(R0+R1)] / (T+R1C1), k3=R0R1C1 / (T+R1C1), U0(k) and U0(k-1) are the sampled data of the open-circuit voltage obtained by the k-th and (k-1)-th sampling, respectively, and U(k) and U(k-1) are the sampled data of the open-circuit voltage obtained by the k-th and (k-1)-th sampling, respectively. I(k) and I(k-1) are the sampling data of the terminal voltage obtained by the kth and k-1th sampling, respectively, and I(k) and I(k-1) are the sampling data of the current obtained by the kth and k-1th sampling, respectively. T is the sampling time interval, and k is a positive integer greater than 1. Based on the multiple sets of sampling data, k1, k2 and k3 are determined based on the polynomial. Based on k1, k2 and k3, the polarization internal resistance and the polarization voltage are determined to be R1=(k2-k3) / (1-k1)-k3 / k1 and C1=(k1×k1×T) / [k1×(k2-k3)-k3×(1-k1)].

[0033] In one implementation, the heating current is alternating current, and the waveform of the alternating current is any one of pulse wave, square wave, triangle wave and sine wave.

[0034] In one implementation, the heating circuit includes a power source connected to the battery.

[0035] In one implementation, the heating circuit includes an energy storage unit and a voltage conversion module connected between the energy storage unit and the battery.

[0036] In one implementation, the heating device is the control circuit of the heating circuit, or the heating device is the battery management system (BMS) of the battery.

[0037] Thirdly, a battery heating device is provided, including a memory and a processor, the memory storing computer instructions, the processor invoking the computer instructions to cause the heating device to implement the battery heating method according to the first aspect or any implementation thereof.

[0038] Fourthly, a computer-readable storage medium is provided for storing a computer program that, when executed by a computing device, causes the computing device to implement the heating method of the battery according to the first aspect or any implementation thereof.

[0039] Fifthly, a heating system for a battery is provided, the heating system comprising: a battery; a heating circuit connected to the battery; and a heating device for the battery according to the second aspect or any implementation thereof, the heating device being connected to the heating circuit, the heating device being configured to control the heating circuit to output a heating current for heating the battery. Attached Figure Description

[0040] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0041] Figure 1 This is a schematic diagram of a heating system according to an embodiment of this application;

[0042] Figure 2 This is a schematic diagram of a heating system according to another embodiment of this application;

[0043] Figure 3 This is a schematic flowchart of a battery heating method according to an embodiment of this application;

[0044] Figure 4 This is an equivalent circuit of a battery according to an embodiment of this application;

[0045] Figure 5 This is another equivalent circuit of a battery according to an embodiment of this application;

[0046] Figure 6 This is a schematic diagram showing the relationship between the maximum allowable amplitude of heating current and temperature and frequency under conditions of suppressing lithium plating;

[0047] Figure 7 This is a schematic diagram showing the relationship between heating power, temperature, and current frequency under conditions that suppress lithium plating;

[0048] Figure 8 This is a schematic diagram illustrating the optimal selection of the heating current frequency given the amplitude of the heating current;

[0049] Figure 9 This is the first-order Thevenin equivalent circuit of the battery in this application embodiment;

[0050] Figure 10 yes Figure 3 A flowchart illustrating one possible specific implementation of the heating method shown;

[0051] Figure 11 This is a schematic block diagram of a heating device according to an embodiment of this application. Detailed Implementation

[0052] The embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to illustrate the principles of this application by way of example, but should not be used to limit the scope of this application, that is, this application is not limited to the described embodiments.

[0053] In the description of this application, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicating orientation or positional relationships, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first," "second," and "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. "Vertical" is not vertical in the strict sense, but within the allowable tolerance range. "Parallel" is not parallel in the strict sense, but within the allowable tolerance range.

[0054] The directional terms used in the following description refer to the directions shown in the figures and are not intended to limit the specific structure of this application. It should also be noted in the description of this application that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0055] With the development of the times, new energy vehicles have huge market prospects due to their advantages such as environmental friendliness, low noise, and low operating costs. They can also effectively promote energy conservation and emission reduction, which is beneficial to social development and progress.

[0056] Due to the electrochemical characteristics of power batteries, their charging and discharging capabilities are significantly limited in low-temperature environments, severely impacting the customer's winter driving experience. Therefore, in order to ensure the normal operation of the power battery, it is necessary to heat it in low-temperature environments.

[0057] The power battery in this application embodiment can be a lithium-ion battery, lithium metal battery, lead-acid battery, nickel-metal hydride battery, lithium-sulfur battery, lithium-air battery, or sodium-ion battery, etc., and is not limited thereto. In terms of scale, the power battery in this application embodiment can be a single cell, a battery module, or a battery pack, and is not limited thereto. In terms of application scenarios, this power battery can be used in power devices such as automobiles and ships. For example, it can be used in electric vehicles to power the motor of the electric vehicle, serving as a power source for electric vehicles. This power battery can also power other electrical components in electric vehicles, such as in-vehicle air conditioning and in-vehicle media players. For ease of description, the following will use the application of the power battery in new energy vehicles (i.e., electric vehicles, or electric cars) as an example to illustrate the solution of this application.

[0058] When self-heating a battery, either alternating current (AC) or direct current (DC) can be used. AC heating is easier to implement, provides faster heating, better heating uniformity, and does not change the battery's state of charge (SOC), resulting in no energy loss. While DC heating is cheaper and requires no additional circuit components, it leads to greater energy loss. Therefore, this embodiment uses AC power to heat the battery.

[0059] Since the frequency of the heating current is related to the heating efficiency, the lower the frequency, the higher the heating efficiency. However, excessively low frequencies can easily cause lithium plating in the battery, and the half-wave cycle process at too low a frequency is close to the DC charging and discharging process, failing to demonstrate the advantages of AC heating. Therefore, when using AC to heat a battery, it is necessary to determine and adjust the optimal heating current frequency.

[0060] Therefore, this application provides a battery heating solution that can effectively heat the battery, has high heating efficiency, and does not affect other components in the heating circuit.

[0061] Typically, AC power or energy storage batteries can be used to charge the power battery. For example, Figure 1 and Figure 2 The diagram illustrates possible application scenarios of embodiments of this application. For example, such as... Figure 1 The heating system shown may include a heating circuit 1 that includes a power source connected to a battery 2, for outputting a heating current to the battery 2. For example, such as... Figure 2 As shown, the heating circuit 1 may include an energy storage unit 11 and a voltage conversion module 12. The voltage conversion module 12 is connected between the energy storage unit 11 and the battery 2. The energy storage unit 11 is used to output heating current to the battery 2 via the voltage conversion module 12. The voltage conversion module 12 may be, for example, a DC / DC converter.

[0062] exist Figure 1 and Figure 2 In this circuit, battery 2 is connected to heating device 3. Heating device 3 can be, for example, a BMS or the control circuit of heating circuit 1. Heating device 3 is used to collect the status information of battery 2. For example, heating device 3 may include a current acquisition unit, a pressure acquisition unit, and a temperature acquisition unit to collect the current, voltage, and temperature information of battery 2, respectively. This information can be used to determine the optimal frequency of the heating current used to heat battery 1, thereby improving the heating efficiency of battery 2.

[0063] Figure 3 A schematic flowchart of a battery heating method 100 according to an embodiment of this application is shown. Figure 3 The heating method 100 shown can be performed by a heating device 3, for example, the heating device 3 can be a BMS; or, the heating device 3 can be the control circuit of the heating circuit 1. The heating method 100 is applied to the heating circuit 1, which is connected to the battery 2, and is used to output a heating current to the battery 2 for heating the battery 2.

[0064] like Figure 3 As shown, heating method 100 includes some or all of the following steps.

[0065] In step 110, the polarization parameters of battery 2 are obtained.

[0066] These polarization parameters include, for example, the polarization internal resistance and polarization capacitance of battery 2.

[0067] In step 120, the frequency of the heating current is determined based on the polarization parameter and the peak current of the heating circuit 1, so that the amplitude of the heating current does not exceed the peak current.

[0068] In step 130, the heating circuit 1 outputs a heating current with the specified frequency to the battery 2.

[0069] Here, heating circuit 1 outputs an alternating current to battery 2 to heat battery 2. The frequency of the heating current is related to the heating efficiency, so it is necessary to determine the optimal frequency of the heating current. In this embodiment, when determining the optimal frequency of the heating current, the peak current of heating circuit 1 is used as a condition, thereby preventing the amplitude of the heating current from exceeding the peak current of heating circuit 1 and avoiding damage to other components in heating circuit 1 during the heating process.

[0070] In this embodiment, during the heating process of battery 2, the temperature and SOC of battery 2 gradually change, and the optimal frequency of the heating current also changes accordingly. Therefore, the frequency of the heating current can be adjusted during the heating process. For example, when the temperature of battery 2 is below T0, the frequency of the heating current is determined to be f1 and heating of battery 2 begins; when the temperature of battery 2 is heated from T0 to T1, the frequency of the heating current is redefined to f2 and battery 2 is heated; when the temperature of battery 2 is heated from T1 to T2, the frequency of the heating current is redefined to f3 and battery 2 is heated; ...; until the temperature of battery 2 reaches the target value Tx. During the heating process, the temperature of battery 2 continuously increases, therefore T0 < T1 < T2 < ... < Tx. That is to say, during the heating process of battery 2, the frequency of the heating current can be adjusted in real time to achieve optimal heating performance.

[0071] The heating current is alternating current. The waveform of the heating current is not limited in the embodiments of this application. For example, the waveform of the alternating current can be any one of pulse wave, square wave, triangle wave and sine wave.

[0072] In one implementation, in step 120, the frequency of the heating current is determined based on the polarization parameters and the peak current of the heating circuit 1, so that the amplitude of the heating current does not exceed the peak current. This includes: determining the frequency of the heating current based on the polarization parameters, the peak current, and the equilibrium potential of the lithium plating reaction of the battery 2, so that the amplitude of the heating current does not exceed the peak current and the polarization voltage of the battery 2 does not exceed the equilibrium potential.

[0073] In other words, when determining the optimal frequency of the heating current, the peak current of the heating circuit 1 and the equilibrium potential of the lithium plating reaction are used as conditions. This can prevent the amplitude of the heating current from exceeding the peak current of the heating circuit 1, thus avoiding damage to other components in the heating circuit 1. It can also prevent the lithium plating phenomenon caused by the polarization voltage of the battery 2 exceeding the equilibrium potential of the lithium plating reaction, thus ensuring the safety of the battery 2.

[0074] To better illustrate the heating scheme of this application, we will first combine... Figure 4 and Figure 5 The equivalent circuit shown describes the conditions for preventing lithium plating in battery 2.

[0075] Figure 4 The equivalent circuit consists of three parts, Z1, Z2, and Z3. Z1 includes the ohmic impedance components of the current collector, active material, and electrolyte inside battery 2; Z2 includes the impedance component corresponding to the SEI film on the particle surface; and Z3 includes the double-layer capacitance Qdl and charge transfer impedance R at the solid-liquid interface of the active material. CT And the impedance W corresponding to the diffusion process of lithium ions.

[0076] During charging, lithium ions are extracted from the positive electrode and inserted into the negative electrode. However, if abnormal conditions occur that prevent the extracted lithium ions from the positive electrode from inserting into the negative electrode, the lithium ions will precipitate on the surface of the negative electrode, forming a gray substance. This phenomenon is called lithium plating. Lithium plating is a type of loss condition in lithium-ion batteries.

[0077] The lithium plating reaction in battery 2 mainly occurs in the Z3 region, therefore the Z2 region can be omitted, resulting in a structure as follows: Figure 5 The equivalent circuit is shown. To prevent lithium plating in battery 2, the solid-liquid phase potential difference at the surface of the negative electrode particles must be greater than the equilibrium potential for the lithium plating reaction, i.e., the following must be satisfied: φ s -φ1>U e，2 (1);

[0078] Where, φ s φ1 and φ2 are the negative electrode potential and lithium plating potential of battery 2, respectively. e，2 The equilibrium potential for the lithium plating reaction in battery 2 is typically U. e，2 It can be considered as 0V, i.e., the ground potential.

[0079] When lithium plating occurs, lithium ions need to gain electrons to be reduced to lithium metal. It is generally believed that the lithium plating reaction initially occurs inside the SEI film on the surface of graphite particles, and the overpotential for the lithium intercalation reaction at this location is: η=φ s -φ1-U e，1 (2);

[0080] Among them, U e，1 This represents the equilibrium potential of the graphite negative electrode at a specific SOC.

[0081] Based on the derivation of the impedance spectrum of battery 2, and through the linearization of the Butler-Volmer equation, the overpotential can be approximated as: η = i ct R ct (3);

[0082] In formula (3), i ct R is the Faraday current. ct As the charge transfer impedance, i is the charge transfer impedance during battery 2 charging. ct The sign of is negative.

[0083] Reference Figure 5 The equivalent circuit of the graphite negative electrode shown is obtained as follows: i ct R ct =-V3 (4);

[0084] Where V3 is the charge transfer impedance R CT The voltage across the two ends, that is, the voltage across the two ends of part Z3.

[0085] Based on formulas (2) to (4), the conditions that must be met to avoid lithium plating in battery 2 can be obtained as follows: V3<U e，1 (5);

[0086] The impedance of section Z3 is related to the frequency of the current, and its expression is:

[0087] Here, Q dl This belongs to the category of constant phase element (CPE). A constant phase element is described by the CPE coefficient Q and the CPE indicator n, and its impedance is:

[0088] When an alternating current is applied to battery 2, the voltage amplitude across Z3 is: |V3|=I ac |Z3| (8);

[0089] In formula (8), |Z3| is the impedance amplitude of the equivalent circuit Z3 part, which is related to the frequency, and Iac is the amplitude of the applied AC current.

[0090] From formulas (5) and (8), we can obtain the condition under which battery 2 does not undergo lithium plating under AC current excitation: I ac |Z3|<U e，1 (9);

[0091] That is, the voltage amplitude across the Z3 portion of the equivalent circuit of the graphite negative electrode of battery 2, or the charge transfer impedance R. CT The voltage amplitude at both ends is always less than the equilibrium potential of the graphite negative electrode.

[0092] Based on the above analysis, if we want to improve the heating efficiency of battery 2 and ensure the safety of battery 2, we need to make the heating current I and the internal resistance of battery 2 as large as possible, but at the same time, we need to meet the conditions of formula (9).

[0093] Based on formulas (6) and (9), we can obtain Figure 6 The diagram shows the relationship between the maximum permissible heating current amplitude and frequency at different temperatures under conditions of suppressed lithium plating. It can be seen that the impedance amplitude of the Z3 section in the equivalent circuit decreases with increasing frequency; therefore, under conditions of suppressed lithium plating, the maximum permissible current amplitude increases with increasing frequency.

[0094] Figure 7 The effects of temperature and frequency on heating power are shown under conditions that suppress lithium plating. The heating power P of battery 2 is related to the heating current I and the internal resistance R of the battery, i.e., P = I. 2 R. The larger the heating current I and internal resistance R, the greater the heating power P. Figure 5 In the middle, as the frequency increases, through R CT With R SEI With a decrease in the current component, the heating power P will come more from the ohmic internal resistance R0. Without limiting the current amplitude, the frequency can be increased to allow the heating power to pass through the polarization internal resistance R0. CT The current component is reduced and the polarization voltage is decreased to avoid lithium plating in battery 2. At the same time, the current amplitude is increased to generate more heat through the ohmic internal resistance R0.

[0095] However, in reality, due to the presence of components such as wiring harnesses and switches in the heating system, the components in the system circuit have a maximum withstand current limit, that is, the heating system has a peak current I. A Due to limitations, given a maximum current amplitude, at excessively low frequencies, the polarization internal resistance R... CT An increase in the current component leads to an increase in polarization voltage, resulting in a decrease in the negative electrode potential of the battery, which may cause lithium plating. At excessively high frequencies, the overall impedance of the battery decreases, leading to a reduction in heating power. In such cases, it is necessary to select the optimal frequency to ensure that the amplitude of the heating current does not exceed the peak current I. A And to prevent lithium plating from occurring in battery 2.

[0096] Figure 8 The optimal selection of the heating current frequency is shown when limiting the amplitude of the heating current. The shaded area represents the lithium plating region. At the right boundary of the shaded area, the maximum heating power without lithium plating in battery 2 can be obtained, and the frequency corresponding to this location is the optimal frequency.

[0097] Taking the square wave as an example of the pulse waveform of the heating current, in the test of the temperature rise rate of a 67AH battery at a 2C current, the amplitude of the heating current was fixed at 134A. When the frequency f of the heating current was 1Hz, 5Hz and 10Hz, the temperature rise rates were 6℃ / min, 2.8℃ / min and 2.3℃ / min, respectively.

[0098] It is evident that, under the same current, reducing the frequency f helps to increase the temperature rise rate. However, it should be noted that excessively low frequencies f may lead to lithium plating.

[0099] To facilitate the analysis of the equivalent circuit of battery 2, in one implementation, in step 120, the frequency of the heating current is determined based on the polarization parameter, the peak current, and the equilibrium potential of the lithium plating reaction of battery 2, including: determining the angular frequency of the heating current based on the polarization internal resistance, the polarization capacitance, the peak current, and the equilibrium potential; and determining the frequency of the heating current based on the angular frequency of the heating current.

[0100] For example, the angular frequency ω of the heating current, i.e., the fillet frequency ω of the AC current used for heating, can be determined based on the polarization resistance and polarization capacitance of battery 2, the peak current of heating circuit 1, and the equilibrium potential of the lithium plating reaction. Then, the frequency f of the heating current can be determined according to ω = 2πf. The calculation is simple and easy to implement.

[0101] In one implementation, in step 120, determining the angular frequency of the heating current based on the polarization resistance, the polarization capacitance, the peak current, and the equilibrium potential includes: determining the angular frequency of the heating current based on the following formula using the polarization resistance, the polarization capacitance, the peak current, and the equilibrium potential: [R1 / (1+jωR1C1)]×I A =X×U e，1 (10);

[0102] Where R1 is the polarization internal resistance of battery 2, C1 is the polarization capacitance of battery 2, and I A U is the peak current of heating circuit 1. e，1 ω is the equilibrium potential of battery 2 under the current SOC, ω is the angular frequency of the heating current, and X is a preset value, which is greater than 0 and less than or equal to 1, i.e., 0 < X ​​≤ 1.

[0103] Given the polarization resistance R1 and polarization capacitance C1 of battery 2 obtained in advance, according to formula (10), i.e. [R1 / (1+jωR1C1)]×I A =X×U e，1 This allows us to obtain the optimal angular frequency ω of the heating current, and further, the optimal frequency f of the heating current.

[0104] The polarization voltage of battery 2 is Ux = [R1 / (1+jωR1C1)]×I. By setting the parameter X to satisfy 0<X≤1, and making Ux=X×U e，1 This ensures that the polarization voltage Ux does not exceed the equilibrium potential U. e，1 This prevents the polarization voltage Ux of battery 2 from exceeding the equilibrium potential U of the lithium plating reaction. e，1 This leads to lithium plating. Simultaneously, the current I in Ux=[R1 / (1+jωR1C1)]×I is limited to be equal to the peak current I of heating circuit 1. AThis prevents the amplitude of the heating current from exceeding the peak current I of heating circuit 1. A This avoids damage to other components in heating circuit 1 during the heating process.

[0105] To obtain the polarization internal resistance R1 and polarization capacitance C1 of battery 2, in one implementation, step 110 involves obtaining the polarization parameters of battery 2, including: determining an equation representing the relationship between the open-circuit voltage, terminal voltage, and current of battery 2 based on the equivalent circuit of battery 2, the equation being associated with the polarization internal resistance and polarization capacitance; sampling the open-circuit voltage, terminal voltage, and current multiple times during the heating process to obtain multiple sets of sampled data; and determining the polarization internal resistance and polarization capacitance based on the equation according to the multiple sets of sampled data.

[0106] By establishing the equivalent circuit of battery 2, an equation is obtained to represent the relationship between the open-circuit voltage, terminal voltage, and current of battery 2. This equation is related to the polarization internal resistance and polarization capacitance of battery 2. Thus, by sampling the open-circuit voltage, terminal voltage, and current of battery 2 multiple times beforehand during the heating process, multiple sets of sampled data are obtained. Substituting these multiple sets of sampled data into the equation, the polarization internal resistance and polarization capacitance of battery 2 can be obtained. The calculation is simple and easy to implement. Therefore, given the polarization internal resistance and polarization capacitance of battery 2 beforehand, according to the aforementioned formula (10), i.e., [R1 / (1+jωR1C1)]×I A =X×U e，1 Then, the angular frequency of the heating current can be obtained, and further, the frequency of the heating current can be obtained.

[0107] Below, with Figure 9 For example, describe in detail how to obtain the polarization internal resistance R1 and polarization capacitance C1 of battery 2.

[0108] Figure 9 The first-order Thevenin equivalent circuit of battery 2 is shown. Based on this equivalent circuit, corresponding equations are established to determine the polarization resistance R1 and polarization capacitance C1. It should be understood that the polarization resistance and polarization capacitance of the battery are determined by establishing a first-order Thevenin equivalent circuit and its corresponding model formula. The model is simple and easy to implement. Of course, other circuit models can also be used in the embodiments of this application to determine the polarization resistance and polarization capacitance of the battery.

[0109] exist Figure 9 In the diagram, R0 is the internal resistance of battery 2 in ohms, R1 is the polarization resistance, C1 is the polarization voltage, U0 is the open-circuit voltage of battery 2, and U is the terminal voltage of battery 2. It should be understood that the internal resistance R0 in ohms can correspond to... Figure 5 The ohmic internal resistance of the Z1 section shown, the polarization internal resistance R1 can correspond to Figure 5 The charge transfer impedance R of the Z3 section shown CTThe polarization voltage C1 can correspond to Figure 5 The capacitor Q of section Z3 shown dl .

[0110] based on Figure 9 The equivalent circuit shown yields the following equation: U0=[R1 / (1+jωR1C1)]×I A +I×R0+U (11);

[0111] Where U0 is the open-circuit voltage of battery 2 at the current SOC and temperature, U is the terminal voltage, I is the current, R1 is the polarization internal resistance, C1 is the polarization capacitance, ω is the angular frequency of the heating current, and R0 is the ohmic internal resistance of battery 2.

[0112] Formula (11) describes the relationship between the open-circuit voltage U0, terminal voltage U, and current I of battery 2, and formula (11) is related to the polarization internal resistance R1 and polarization capacitance C1 of battery 2. Therefore, when the open-circuit voltage U0, terminal voltage U, and current I of battery 2 are sampled multiple times during the heating process, multiple sets of sampled data are obtained. Substituting these multiple sets of sampled data into the formula, the polarization internal resistance R1, polarization capacitance C1, and ohmic internal resistance R0 of battery 2 can be obtained.

[0113] In one implementation, the polarization resistance R1 and polarization capacitance C1 are determined based on the equation according to the multiple sets of sampled data, including:

[0114] First, convert equation (10) into a difference polynomial. For example, let s = (x(k) - x(k-1)) / T, where T is the sampling time interval and x represents the sampling parameters such as open-circuit voltage U0, terminal voltage U, and current I. The difference polynomial is then obtained as follows: U0(k)-U(k)=k1×[U0(k-1)-U(k-1)]+k2×I(k)-k3×I(k-1) (12); k1=R1C1 / (T+R1C1) (13); k2=[R0R1C1+T(R0+R1)] / (T+R1C1) (14); k3=R0R1C1 / (T+R1C1) (15);

[0115] Wherein, U0(k) and U0(k-1) are the sampled data of the open-circuit voltage obtained by the k-th and (k-1)-th sampling respectively, U(k) and U(k-1) are the sampled data of the terminal voltage obtained by the k-th and (k-1)-th sampling respectively, I(k) and I(k-1) are the sampled data of the current obtained by the k-th and (k-1)-th sampling respectively, and k is a positive integer greater than 1;

[0116] Secondly, based on multiple sets of sampled data, k1, k2 and k3 are determined according to polynomial (12);

[0117] Finally, based on k1, k2, and k3, the polarization internal resistance R1 and polarization voltage C1 are determined.

[0118] Since the three parameters k1, k2 and k3 are solved by difference polynomial, the total number of samplings is usually not less than 4.

[0119] In other words, multiple samples are taken of the open-circuit voltage U0, terminal voltage U, and current I to obtain multiple sets of sampled data, such as U0(k), U0(k-1), U(k), U(k-1), I(k), and I(k-1). Substituting these multiple sets of sampled data into formula (12), several equations related to the ohmic internal resistance R0, polarization internal resistance R1, and polarization capacitance C1 of battery 2 can be obtained, thereby solving for k1, k2, and k3. Finally, based on k1, k2, and k3, and formulas (13) to (15), the ohmic internal resistance R0, polarization internal resistance R1, and polarization capacitance C1 of battery 2 can be obtained as follows: R0=k3 / k1 (16): R1=(k2-k3) / (1-k1)-k3 / k1 (17); C1=(k1×k1×T) / [k1×(k2-k3)-k3×(1-k1)] (18);

[0120] The sampling data of the open-circuit voltage U0 of battery 2 can be obtained, for example, by acquiring the state of charge (SOC) and temperature, and determining them from the MAP table based on the SOC and temperature. This MAP table contains the open-circuit voltage U0 of battery 2 at different temperatures and SOCs, calibrated before shipment. The sampling data of the terminal voltage U and current I of battery 2 can be obtained by detecting the voltage and current.

[0121] It can be seen that by transforming the equation corresponding to the equivalent circuit of battery 2 into a polynomial in differential form, the imaginary part in the equation can be effectively removed, thus making it convenient to use the sampling data of open-circuit voltage U0, terminal voltage U and current I to determine the polarization internal resistance R1 and polarization capacitance C1 of battery 2.

[0122] Thus, given the polarization internal resistance R1 and polarization capacitance C1 of battery 2 obtained beforehand, according to the aforementioned formula (10), i.e. [R1 / (1+jωR1C1)]×I A =X×U e，1 We can then obtain the angular frequency ω of the heating current, and further obtain the frequency f of the heating current based on ω=2πf.

[0123] Figure 10 It shows the basis Figure 3 A flowchart illustrating one possible specific implementation of the heating method 100 shown.

[0124] In step 101, it is determined that battery 2 will be heated.

[0125] For example, upon receiving a battery heating request, it is determined that battery 2 should be heated; the battery heating request is used to instruct battery 2 to be heated.

[0126] For example, when the temperature of battery 2 is lower than the preset temperature T0, it is determined that battery 2 should be heated.

[0127] In step 102, the status information of battery 2 is obtained.

[0128] This status information includes, for example, the current temperature, SOC, voltage, and current of battery 2.

[0129] In step 103, the equivalent circuit of battery 2 is established, and the ohmic internal resistance R0, polarization internal resistance R1 and polarization capacitance C1 of battery 2 are calculated.

[0130] Here, an equivalent circuit for battery 2 is established. The open-circuit voltage U0, terminal voltage U, and current I of battery 2 are sampled, and the ohmic internal resistance R0, polarization internal resistance R1, and polarization capacitance C1 of battery 2 are calculated based on the sampled data. The open-circuit voltage U0 can be determined based on the state of charge (SOC) and temperature.

[0131] In step 104, the threshold value of the polarization voltage Ux and the peak current I of the heating circuit 1 are determined. A And calculate the frequency f of the heating current.

[0132] Polarization voltage Ux=[R1 / (1+jωR1C1)]×I A X can be set between 0 and 1, for example, it can be set to 0.9, so that Ux is less than the equilibrium potential U. e，1 The corresponding U can be determined based on the current SOC of battery 2. e，1 .

[0133] Let [R1 / (1+jωR1C1)]×I A =X×U e，1 Given the polarization resistance R1 and polarization capacitance C1, due to parameter X and peak current I... A and equilibrium potential U e，1 As a constraint, the angular frequency ω of the heating current is determined, and the frequency f of the heating current is determined according to ω=2πf.

[0134] In step 105, battery 2 is heated according to the frequency f determined in step 104.

[0135] In step 106, the frequency f of updating the heating current is determined.

[0136] For example, when a battery heating request is received again, steps 102 to 105 are re-executed to update the frequency f of the heating current.

[0137] For example, when the temperature of battery 2 is lower than the preset temperature T1, T1 > T0, it is determined to re-execute steps 102 to 105 to update the frequency f of the heating current.

[0138] implement Figure 10 The process shown continues until the temperature of battery 2 reaches the required temperature threshold Tx.

[0139] Figure 10 In the illustrated process, when heating battery 2, the polarization resistance R1 and polarization capacitance C1 of battery 2 at different SOCs and temperatures can be sampled and calculated in real time, thereby providing parameters X and peak current I. A and equilibrium potential U e，1 As a constraint, the frequency f of the heating current is determined.

[0140] However, to further improve heating efficiency, the polarization resistance R1 and polarization capacitance C1 of battery 2 at different SOCs and temperatures can be pre-calculated and stored. This way, when heating battery 2, these values ​​can be directly read and used, eliminating the need to sample and calculate the polarization resistance R1 and polarization capacitance C1 of battery 2 at different SOCs and temperatures in real time for each heating cycle.

[0141] It should also be understood that, in this embodiment of the application, the maximum amplitude of the heating current is limited to the peak current I of the heating circuit 1. A In practical applications, the maximum amplitude of the heating current can also be limited to be slightly less than the peak current I. A .

[0142] The heating method described in the above embodiments of this application can effectively heat the battery 2 and prevent the amplitude of the heating current from exceeding the peak current of the heating circuit 1, thus avoiding damage to other components in the heating circuit 1 during the heating process. Furthermore, it can also prevent lithium plating caused by the polarization voltage of the battery 2 exceeding the equilibrium potential of the lithium plating reaction, ensuring the safety of the battery 2.

[0143] Figure 11 A heating device 3 for a battery 2 according to an embodiment of this application is shown. The heating device 3 is applied to a heating circuit 1, which is connected to the battery 2, and is used to output a heating current to the battery 2. The heating current is used to heat the battery 2. The heating device 3 includes:

[0144] The processing module 310 is used to acquire the polarization parameters of the battery 2 and determine the frequency of the heating current based on the polarization parameters and the peak current of the heating circuit 1, so that the amplitude of the heating current does not exceed the peak current.

[0145] The control module 320 is used to control the heating circuit 1 to output a heating current with the specified frequency to the battery 2.

[0146] In one implementation, the processing module 310 is specifically used to: determine the frequency of the heating current based on the polarization parameters, peak current and equilibrium potential of the lithium plating reaction of battery 2, so that the amplitude of the heating current does not exceed the peak current and the polarization voltage of battery 2 does not exceed the equilibrium potential.

[0147] In one implementation, the polarization parameters include the polarization internal resistance and polarization capacitance of battery 2.

[0148] In one implementation, the processing module 310 is specifically used to: determine the angular frequency of the heating current based on the polarization internal resistance, polarization capacitance, peak current and equilibrium potential; and determine the frequency of the heating current based on the angular frequency of the heating current.

[0149] In one implementation, the processing module 310 is specifically used to: determine the angular frequency of the heating current based on the following formula, according to the polarization internal resistance, polarization capacitance, peak current, and equilibrium potential:

[0150] [R1 / (1+jωR1C1)]×I A =X×U e，1 Where R1 is the polarization internal resistance, C1 is the polarization capacitance, and I... A U is the peak current. e，1 ω is the equilibrium potential of battery 2 at its current state of charge (SOC), ω is the angular frequency of the heating current, and X is a preset value, which is greater than 0 and less than or equal to 1.

[0151] In one implementation, the processing module 310 is specifically used to: determine the frequency of the heating current according to ω = 2πf, where ω is the angular frequency of the heating current and f is the frequency of the heating current.

[0152] In one implementation, the processing module 310 is specifically used to: determine an equation representing the relationship between the open-circuit voltage, terminal voltage, and current of the battery 2 based on the equivalent circuit of the battery 2, the equation being associated with the polarization internal resistance and polarization capacitance; sample the open-circuit voltage, terminal voltage, and current multiple times during the heating process to obtain multiple sets of sampled data; and determine the polarization internal resistance and polarization capacitance based on the equation according to the multiple sets of sampled data.

[0153] In one implementation, the equivalent circuit is a first-order Thevenin equivalent circuit, with the equation: U0=[R1 / (1+jωR1C1)]×IA +I×R0+U, where U0 is the open-circuit voltage of battery 2 at the current SOC and temperature, U is the terminal voltage, I is the current, R1 is the polarization internal resistance, and C1 is the polarization capacitor.

[0154] In one implementation, the processing module 310 is specifically used to: convert the equation into a difference form polynomial U0(k)-U(k)=k1×[U0(k-1)-U(k-1)]+k2×I(k)-k3×I(k-1), where k1=R1C1 / (T+R1C1), k2=[R0R1C1+T(R0+R1)] / (T+R1C1), k3=R0R1C1 / (T+R1C1), U0(k) and U0(k-1) are the sampled data of the open-circuit voltage obtained by the k-th and (k-1)-th sampling, respectively, and U(k) U(k-1) and I(k-1) are the sampled data of the terminal voltage obtained by the kth and (k-1)th sampling, respectively. I(k) and I(k-1) are the sampled data of the current obtained by the kth and (k-1)th sampling, respectively. T is the sampling time interval, and k is a positive integer greater than 1. Based on multiple sets of sampled data, k1, k2 and k3 are determined based on polynomials. Based on k1, k2 and k3, the polarization internal resistance and polarization voltage are determined to be R1=(k2-k3) / (1-k1)-k3 / k1 and C1=(k1×k1×T) / [k1×(k2-k3)-k3×(1-k1)].

[0155] In one implementation, the heating current is alternating current, and the waveform of the alternating current is any one of pulse wave, square wave, triangle wave and sine wave.

[0156] In one implementation, the heating circuit 1 includes a power source connected to a battery.

[0157] In one implementation, the heating circuit 1 includes an energy storage unit and a voltage conversion module, with the voltage conversion module connected between the energy storage unit and the battery 2.

[0158] In one implementation, the heating device 3 is the control circuit of the heating circuit 1, or the heating device 3 is the battery's BMS.

[0159] This application also provides a battery heating device, including a memory and a processor. The memory is used for a computer program, and the processor is used to call and run the computer program stored in the memory to perform the battery heating method of any of the above embodiments.

[0160] This application also provides a computer-readable storage medium for storing a computer program that causes a computer to perform the battery heating method of any of the above embodiments.

[0161] This application also provides a battery heating system, which includes: a battery; a heating circuit connected to the battery; and, in any of the above embodiments, a battery heating device connected to the heating circuit for controlling the heating circuit to output a heating current, the heating current being used to heat the battery.

[0162] This application also provides a power unit, including a battery, a heating circuit, and a heating device as described in any of the above embodiments. The heating device is connected to the heating circuit and is used to control the heating circuit to output a heating current, which is used to heat the battery. The power unit may be, for example, a motor vehicle.

[0163] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0164] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the above method embodiments, and will not be repeated here.

[0165] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0166] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

Claims

1. A method for heating a battery, characterized in that, An application is made in a heating circuit, the heating circuit being connected to a battery, for outputting a heating current to the battery, the heating current being used to heat the battery, the heating method comprising: Obtain the polarization parameters of the battery; Based on the polarization parameters and the peak current of the heating circuit, the frequency of the heating current is determined so that the amplitude of the heating current does not exceed the peak current. The heating circuit is controlled to output a heating current having the specified frequency to the battery; Determining the frequency of the heating current based on the polarization parameters and the peak current of the heating circuit, so that the amplitude of the heating current does not exceed the peak current, includes: The frequency of the heating current is determined based on the polarization parameters, the peak current, and the equilibrium potential of the lithium plating reaction of the battery, so that the amplitude of the heating current does not exceed the peak current and the polarization voltage of the battery does not exceed the equilibrium potential.

2. The heating method according to claim 1, characterized in that, The polarization parameters include the polarization internal resistance and polarization capacitance of the battery.

3. The heating method according to claim 2, characterized in that, Determining the frequency of the heating current based on the polarization parameters, the peak current, and the equilibrium potential of the lithium plating reaction in the battery includes: The angular frequency of the heating current is determined based on the polarization internal resistance, the polarization capacitance, the peak current, and the equilibrium potential. The frequency of the heating current is determined based on the angular frequency of the heating current.

4. The heating method according to claim 3, characterized in that, Determining the angular frequency of the heating current based on the polarization internal resistance, the polarization capacitance, the peak current, and the equilibrium potential includes: The angular frequency of the heating current is determined based on the polarization resistance, the polarization capacitance, the peak current, and the equilibrium potential, using the following formula: [R1 / (1+ j ωR1C1)]×I A =X×U e,1 Where R1 is the polarization internal resistance, C1 is the polarization capacitance, IA is the peak current, and U e,1 The equilibrium potential of the battery at its current state of charge (SOC) is ω, the angular frequency of the heating current is X, and X is a preset value that is greater than 0 and less than or equal to 1.

5. The heating method according to claim 3, characterized in that, Determining the frequency of the heating current based on the angular frequency includes: According to ω=2π f The frequency of the heating current is determined, where ω is the angular frequency of the heating current. f The frequency of the heating current.

6. The heating method according to claim 2, characterized in that, The process of obtaining the polarization parameters of the battery includes: Based on the equivalent circuit of the battery, an equation is determined to represent the relationship between the open-circuit voltage, terminal voltage, and current of the battery, and the equation is associated with the polarization internal resistance and the polarization capacitance. The open-circuit voltage, the terminal voltage, and the current during the heating process are sampled multiple times to obtain multiple sets of sampled data; Based on the multiple sets of sampled data, the polarization internal resistance and the polarization capacitance are determined according to the equation.

7. The heating method according to claim 6, characterized in that, The equivalent circuit is a first-order Thevenin equivalent circuit, and the equation is: U0=[R1 / (1+ j ωR1C1)]×I A +I×R0+U, where U0 is the open-circuit voltage of the battery at the current SOC and temperature, U is the terminal voltage, I is the current, R1 is the polarization internal resistance, C1 is the polarization capacitor, and R0 is the ohmic internal resistance of the battery.

8. The heating method according to claim 7, characterized in that, The step of determining the polarization internal resistance and the polarization capacitance based on the equation according to the multiple sets of sampled data includes: Transform the equation into a polynomial in difference form: U0(k)-U(k)=k1×[U0(k-1)-U(k-1)]+k2×I(k)-k3×I(k-1), where, k1=R1C1 / (T+R1C1), k2=[R0R1C1+T(R0+R1)] / (T+R1C1), k3=R0R1C1 / (T+R1C1), U0(k) and U0(k-1) are the sampling data of the open-circuit voltage obtained by the kth and (k-1)th sampling respectively, U(k) and U(k-1) are the sampling data of the terminal voltage obtained by the kth and (k-1)th sampling respectively, I(k) and I(k-1) are the sampling data of the current obtained by the kth and (k-1)th sampling respectively, T is the sampling interval, and k is a positive integer greater than 1; Based on the multiple sets of sampled data, k1, k2, and k3 are determined according to the polynomial. Based on k1, k2 and k3, the polarization internal resistance and the polarization voltage are determined to be R1=(k2-k3) / (1-k1)-k3 / k1 and C1=(k1×k1×T) / [k1×(k2-k3)-k3×(1-k1)].

9. The heating method according to any one of claims 1 to 8, characterized in that, The heating current is alternating current, and the waveform of the alternating current is any one of pulse wave, square wave, triangle wave and sine wave.

10. The heating method according to any one of claims 1 to 8, characterized in that, The heating circuit includes a power source, which is connected to the battery.

11. The heating method according to any one of claims 1 to 8, characterized in that, The heating circuit includes an energy storage unit and a voltage conversion module, with the voltage conversion module connected between the energy storage unit and the battery.

12. A heating device for a battery, characterized in that, An application in a heating circuit, wherein the heating circuit is connected to a battery and is used to output a heating current to the battery, the heating current being used to heat the battery, the heating device comprising: The processing module is used to acquire the polarization parameters of the battery and determine the frequency of the heating current based on the polarization parameters and the peak current of the heating circuit, so that the amplitude of the heating current does not exceed the peak current. A control module is used to control the heating circuit to output a heating current with the specified frequency to the battery; The processing module is specifically used for: The frequency of the heating current is determined based on the polarization parameters, the peak current, and the equilibrium potential of the lithium plating reaction of the battery, so that the amplitude of the heating current does not exceed the peak current and the polarization voltage of the battery does not exceed the equilibrium potential.

13. The heating device according to claim 12, characterized in that, The polarization parameters include the polarization internal resistance and polarization capacitance of the battery.

14. The heating device according to claim 13, characterized in that, The processing module is specifically used for: The angular frequency of the heating current is determined based on the polarization internal resistance, the polarization capacitance, the peak current, and the equilibrium potential. The frequency of the heating current is determined based on the angular frequency of the heating current.

15. The heating device according to claim 14, characterized in that, The processing module is specifically used for: The angular frequency of the heating current is determined based on the polarization resistance, the polarization capacitance, the peak current, and the equilibrium potential, using the following formula: [R1 / (1+ j ωR1C1)]×I A =X×U e,1 Where R1 is the polarization internal resistance, C1 is the polarization capacitance, IA is the peak current, and U e,1 The equilibrium potential of the battery at its current state of charge (SOC) is ω, the angular frequency of the heating current is X, and X is a preset value that is greater than 0 and less than or equal to 1.

16. The heating device according to claim 14, characterized in that, The processing module is specifically used for: According to ω=2π f The frequency of the heating current is determined, where ω is the angular frequency of the heating current. f The frequency of the heating current.

17. The heating device according to claim 13, characterized in that, The processing module is specifically used for: Based on the equivalent circuit of the battery, an equation is determined to represent the relationship between the open-circuit voltage, terminal voltage, and current of the battery, and the equation is associated with the polarization internal resistance and the polarization capacitance. The open-circuit voltage, the terminal voltage, and the current during the heating process are sampled multiple times to obtain multiple sets of sampled data; Based on the multiple sets of sampled data, the polarization internal resistance and the polarization capacitance are determined according to the equation.

18. The heating device according to claim 17, characterized in that, The equivalent circuit is a first-order Thevenin equivalent circuit, and the equation is: U0=[R1 / (1+ j ωR1C1)]×I A +I×R0+U, where U0 is the open-circuit voltage of the battery at the current SOC and temperature, U is the terminal voltage, I is the current, R1 is the polarization internal resistance, C1 is the polarization capacitor, and R0 is the ohmic internal resistance of the battery.

19. The heating device according to claim 18, characterized in that, The processing module is specifically used for: Transform the equation into a polynomial in difference form: U0(k)-U(k)=k1×[U0(k-1)-U(k-1)]+k2×I(k)-k3×I(k-1), where, k1=R1C1 / (T+R1C1), k2=[R0R1C1+T(R0+R1)] / (T+R1C1), k3=R0R1C1 / (T+R1C1), U0(k) and U0(k-1) are the sampling data of the open circuit voltage obtained by the kth and (k-1)th sampling, respectively; U(k) and U(k-1) are the sampling data of the terminal voltage obtained by the kth and (k-1)th sampling, respectively; I(k) and I(k-1) are the sampling data of the current obtained by the kth and (k-1)th sampling, respectively; T is the sampling time interval; and k is a positive integer greater than 1. Based on the multiple sets of sampled data, k1, k2, and k3 are determined according to the polynomial. Based on k1, k2 and k3, the polarization internal resistance and the polarization voltage are determined to be R1=(k2-k3) / (1-k1)-k3 / k1 and C1=(k1×k1×T) / [k1×(k2-k3)-k3×(1-k1)].

20. The heating device according to any one of claims 12 to 19, characterized in that, The heating current is alternating current, and the waveform of the alternating current is any one of pulse wave, square wave, triangle wave and sine wave.

21. The heating device according to any one of claims 12 to 19, characterized in that, The heating circuit includes a power source, which is connected to the battery.

22. The heating device according to any one of claims 12 to 19, characterized in that, The heating circuit includes an energy storage unit and a voltage conversion module, with the voltage conversion module connected between the energy storage unit and the battery.

23. The heating device according to any one of claims 12 to 19, characterized in that, The heating device is either the control circuit of the heating circuit or the battery management system (BMS) of the battery.

24. A heating device for a battery, characterized in that, It includes a memory and a processor, the memory storing computer instructions, and the processor calling the computer instructions to cause the heating device to implement the heating method of the battery according to any one of claims 1 to 11.

25. A computer-readable storage medium, characterized in that, Used to store a computer program, which, when executed by a computing device, causes the computing device to implement the heating method of the battery according to any one of claims 1 to 11.

26. A heating system for a battery, characterized in that, The heating system includes: Battery; A heating circuit connected to the battery; and, The heating device according to any one of claims 12 to 23 is connected to the heating circuit, and the heating device is used to control the heating circuit to output a heating current, the heating current being used to heat the battery.

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