Battery heating method, battery device, battery management system, and electric device

Abstract

This application provides a battery heating method, a battery device, a battery management system, and an electrical device, belonging to the field of battery technology. The battery includes at least one battery pack. The method includes: responding to a battery temperature less than or equal to a first temperature threshold, controlling the positive and negative terminals of the battery to alternately short-circuit and disconnect based on a pulse width modulation signal to heat the battery; responding to a battery temperature greater than the first temperature threshold, controlling the battery pack to alternately charge and discharge until the battery temperature reaches a target temperature, where the first temperature threshold is less than the target temperature. The battery heating method of this application can improve battery heating stability and thus improve the heating effect.

Description

Technical Field

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

[0002] Energy conservation and emission reduction are key to sustainable social development. Rechargeable batteries, with their ability to store and release energy as needed, are widely used in various electrical devices and energy storage systems, and are an important component in promoting energy transition and sustainable development. For the new energy industry, battery technology is a crucial factor in its development.

[0003] Battery performance is easily affected by temperature. For example, when a battery is in a low-temperature environment, its performance will be significantly reduced compared to room temperature. To address this issue, batteries are typically heated. However, the stability of battery heating can also be affected by temperature, thus impacting the heating effect. Summary of the Invention

[0004] This application aims to at least address one of the technical problems existing in the background art. Therefore, one object of this application is to provide a battery heating method, battery device, battery management system, and power supply device to improve battery heating stability and thus enhance heating effect.

[0005] An embodiment of the first aspect of this application provides a battery heating method, the battery including at least one battery pack, the method comprising: in response to the battery temperature being less than or equal to a first temperature threshold, controlling the positive and negative terminals of the battery to alternately short-circuit and disconnect based on a pulse width modulation signal to heat the battery; and in response to the battery temperature being greater than the first temperature threshold, controlling the battery pack to alternately charge and discharge until the battery temperature reaches a target temperature, wherein the first temperature threshold is less than the target temperature.

[0006] In the technical solution of this application embodiment, when the battery temperature is less than or equal to a first temperature threshold, the battery's internal resistance increases significantly, and the discharge polarization effect is severe. In this case, the positive and negative terminals of the battery are alternately short-circuited and disconnected based on a pulse width modulation signal. When the positive and negative terminals are short-circuited, the battery short-circuits and generates a large instantaneous current, triggering high-power heat generation. This allows the battery to generate heat quickly at low temperatures, improving the problem that the severe discharge polarization effect at low temperatures leads to insufficient heating power and an inability to continuously raise the temperature. When the positive and negative terminals of the battery are disconnected, no current flows inside the battery, and the battery does not need to discharge. This improves the problem that the severe discharge polarization effect at low temperatures leads to insufficient heating power and an inability to continuously raise the temperature. Furthermore, by controlling the duty cycle of the pulse width modulation signal, the battery obtains a stable equivalent average current, thereby enabling continuous heating of the battery at low temperatures and improving heating stability. When the temperature exceeds the first temperature threshold, the battery temperature is relatively high, and the battery's internal resistance drops rapidly. In this case, the battery pack is controlled to perform alternating charging and discharging. Even if the battery's internal resistance drops rapidly, the continuous increase in current can be limited by periodic current commutation. This avoids the rapid increase in current caused by the sudden drop in internal resistance, which would lead to increased heat generation and achieve battery heating stability.

[0007] In some embodiments, in response to a battery temperature being less than or equal to a first temperature threshold, heating the battery based on a pulse width modulation signal includes: acquiring a preset heating power required to heat the battery; and determining the frequency of the pulse width modulation signal based on the preset heating power and the battery's impedance characteristics at different temperatures and under different states of charge. The battery's impedance characteristics can be used to characterize the change in battery impedance with frequency. Selecting an optimal frequency based on the preset heating power can adjust the battery's impedance, thereby ensuring that the average heating power of the battery remains at or near the preset heating power. This promotes a more stable overall heating rate for the battery and, to some extent, avoids the risk of uneven internal temperature distribution and a sharp increase in local temperature caused by an excessively rapid heating rate.

[0008] In some embodiments, determining the frequency of the pulse width modulation signal based on a preset heating power and the battery's impedance characteristics at different temperatures and states of charge includes: acquiring the initial open-circuit voltage of the battery at the initial heating temperature; and determining the initial impedance of the battery at the initial heating temperature and the corresponding initial frequency based on the initial open-circuit voltage, the preset heating power, and the battery's impedance characteristics, wherein the initial frequency is used as the frequency of the pulse width modulation signal. At the initial heating moment of the battery, the required impedance at the initial heating moment can be inferred from the initial open-circuit voltage and the initial preset heating power. Since the battery's impedance characteristics characterize the relationship between impedance and frequency, the optimal frequency of the pulse width modulation signal input to the battery at the initial heating moment can be determined based on the obtained impedance, enabling the battery to heat at the preset heating power at the initial heating moment. Thus, during subsequent heating processes, the duty cycle of the pulse width modulation signal can be adjusted based on the heating power at the initial heating moment, stabilizing the average heating power of the battery at or near the preset heating power.

[0009] In some embodiments, heating the battery based on a pulse width modulation signal in response to the battery temperature being less than or equal to a first temperature threshold further includes: acquiring a preset heating power required to heat the battery; acquiring the current actual heating power of the battery; and determining the duty cycle of the pulse width modulation signal based on the ratio of the preset heating power to the current actual heating power of the battery. The actual heating power multiplied by the duty cycle equals the average power over one cycle. Determining the duty cycle of the pulse width modulation signal by the ratio of the preset heating power to the current actual heating power allows for real-time adjustment of the duty cycle, ensuring that the average heating power of the battery remains stable at or near the preset heating power, thereby improving the stability of battery heating.

[0010] In some embodiments, obtaining the current actual heating power of the battery includes: obtaining a first mapping relationship, which characterizes the change in the actual heating power of the battery with respect to battery temperature under the current state of charge and current excitation signal frequency; and determining the current actual heating power of the battery based on the current temperature of the battery and the first mapping relationship. By establishing a correlation between the actual heating power of the battery under the current state of charge and current excitation signal frequency and the battery temperature, the current actual heating power can be found from the first mapping relationship by determining the current temperature of the battery, eliminating complex calculation processes and improving response speed.

[0011] In some embodiments, the method further includes: heating the battery based on a pulse width modulation signal in response to the battery temperature being greater than or equal to a second temperature threshold and less than or equal to a first temperature threshold, wherein the second temperature threshold is less than the first temperature threshold. When the battery temperature is less than the second temperature threshold, the battery heating efficiency may be too low. Therefore, heating the battery based on the pulse width modulation signal only when the battery temperature is greater than or equal to the second temperature threshold and less than or equal to the first temperature threshold is beneficial for improving the overall heating efficiency of the battery.

[0012] In some embodiments, controlling the battery pack to perform alternating charge and discharge includes: acquiring a second mapping relationship, which characterizes the change in battery impedance with battery temperature at the current state of charge and the current alternating charge and discharge frequency; and adjusting the current of the battery pack during alternating charge and discharge based on the current temperature of the battery and the second mapping relationship. By establishing the correlation between the battery impedance and temperature at the current state of charge and the current excitation signal frequency, the current impedance of the battery can be predicted based on the second mapping relationship by determining the battery temperature. This eliminates the need for impedance detection and improves the response rate. Furthermore, by determining the battery impedance and adjusting the current, the real-time heating power of the battery can be controlled to prevent the heating power from becoming too low.

[0013] In some embodiments, the method further includes: acquiring the current open-circuit voltage of the battery; and determining a current threshold for adjusting the current of alternating charge and discharge of the battery pack based on the current temperature of the battery, the current open-circuit voltage, and a second mapping relationship. By determining the current threshold for alternating charge and discharge of the battery, the voltage across the battery terminals will not exceed the protection voltage during alternating charge and discharge, which helps to improve the stability of battery heating.

[0014] In some embodiments, controlling the battery pack to perform alternating charge and discharge further includes: obtaining a third mapping relationship, which characterizes the change in battery impedance with excitation signal frequency at the current state of charge and current temperature; and adjusting the frequency of alternating charge and discharge of the battery pack based on the third mapping relationship. By establishing a correlation between the battery impedance and excitation signal frequency at the current state of charge and current temperature, and adjusting the frequency of alternating charge and discharge of the battery pack based on this correlation, the battery can achieve the corresponding impedance, thereby enabling the real-time heating power of the battery to be regulated so that the heating power of the battery is not too low.

[0015] In some embodiments, the method further includes: acquiring the battery's temperature rise rate; and stopping heating the battery in response to the battery's temperature rise rate being greater than or equal to a first threshold. This can, to some extent, avoid the problem of uneven temperature distribution inside the battery due to an excessively rapid temperature rise rate.

[0016] In some embodiments, obtaining the battery's temperature rise rate includes: establishing a temperature rise model for the battery, which characterizes the rate of change of the battery's temperature rise function with temperature; and determining the battery's temperature rise rate based on the temperature rise model and the current temperature. The temperature rise rate can be predicted using a temperature rise model, eliminating the need for actual detection and improving response speed.

[0017] In some embodiments, obtaining the battery's temperature rise rate further includes: obtaining the temperature difference between the battery's current temperature and the initial heating temperature; obtaining the battery's heating time; determining the battery's actual temperature rise rate based on the ratio of the temperature difference between the battery's current temperature and the initial heating temperature to the battery's heating time; and determining the actual temperature rise rate as the battery's temperature rise rate if the temperature rise rate determined based on the battery's temperature rise model and the current temperature is inconsistent with the actual temperature rise rate. This improves the accuracy of detection and effectively avoids the problem of excessively rapid battery temperature rise rates.

[0018] An embodiment of the second aspect of this application provides a battery device, comprising: a battery including at least one battery pack; a first heating circuit connected to the positive and negative terminals of the battery; a second heating circuit connected to the positive and negative terminals of the battery; and a controller configured to: in response to the battery temperature being less than or equal to a first temperature threshold, control the first heating circuit to alternately short-circuit and disconnect the positive and negative terminals of the battery based on a pulse width modulation signal to heat the battery; and in response to the battery temperature being greater than the first temperature threshold, control the second heating circuit to alternately charge and discharge the battery pack in the battery until the battery temperature reaches a target temperature, wherein the first temperature threshold is less than the target temperature. Heating the battery using a pulse width modulation signal eliminates the need for battery discharge, thus improving the problem of insufficient heat generation power and inability to continuously heat up the battery at low temperatures due to severe discharge polarization effects. Furthermore, by controlling the duty cycle of the pulse width modulation signal, the battery obtains a stable equivalent average current, thereby enabling continuous heating of the battery at low temperatures and improving heating stability. When the temperature exceeds the first temperature threshold, the battery's internal resistance decreases rapidly. Periodic current commutation limits the continuous increase of current, preventing a sharp rise in current due to a sudden drop in internal resistance, which would lead to increased heat generation and thus achieve battery heating stability.

[0019] In some embodiments, the first heating circuit includes: a first switching circuit connected to the positive and negative terminals of the battery; the controller is configured to: in response to the battery temperature being less than or equal to a first temperature threshold, control the first switching circuit to alternately turn on and off to input a pulse width modulation signal to the battery. By setting the first switching circuit, the control logic is simple, and the reliability of the first heating circuit heating the battery is improved.

[0020] In some embodiments, the controller is further configured to: acquire a preset heating power required to heat the battery; and determine the frequency of a pulse width modulation signal based on the preset heating power and the impedance characteristics of the battery at different temperatures and states of charge. The battery's impedance characteristics can be used to characterize the change in battery impedance with frequency. Selecting the optimal frequency based on the preset heating power can adjust the battery's impedance, thereby ensuring that the average heating power of the battery remains at or near the preset heating power. This promotes a more stable overall heating rate for the battery and, to some extent, avoids the risk of uneven internal temperature distribution and rapid local temperature increases caused by excessively rapid heating.

[0021] In some embodiments, the controller is further configured to: acquire the initial open-circuit voltage of the battery at the initial heating temperature; and, based on the initial open-circuit voltage, the preset heating power, and the battery's impedance characteristics, determine the initial impedance of the battery at the initial heating temperature and the initial frequency corresponding to the initial impedance, wherein the initial frequency is used as the frequency of the pulse width modulation signal. At the initial heating moment of the battery, the required impedance at the initial heating moment can be inferred from the initial open-circuit voltage and the initial preset heating power. Since the battery's impedance characteristics characterize the relationship between impedance and frequency, the optimal frequency of the pulse width modulation signal input to the battery at the initial heating moment can be determined based on the obtained impedance, enabling the battery to heat at the preset heating power at the initial heating moment. Thus, during subsequent heating, the duty cycle of the pulse width modulation signal can be adjusted based on the heating power at the initial heating moment, stabilizing the average heating power of the battery at or near the preset heating power.

[0022] In some embodiments, the controller is further configured to: acquire a preset heating power required to heat the battery; acquire the current actual heating power of the battery; and determine the duty cycle of the pulse width modulation signal based on the ratio of the preset heating power to the current actual heating power of the battery. The actual heating power multiplied by the duty cycle equals the average power over one cycle. Determining the duty cycle of the pulse width modulation signal by the ratio of the preset heating power to the current actual heating power allows for real-time adjustment of the duty cycle, ensuring that the average heating power of the battery remains stable at or near the preset heating power, thereby improving the stability of battery heating.

[0023] In some embodiments, the controller is further configured to: acquire a first mapping relationship, which characterizes the change in actual heating power of the battery at different excitation signal frequencies with battery temperature under the current state of charge; and determine the current actual heating power of the battery based on the frequency of the pulse width modulation signal, the current temperature of the battery, and the first mapping relationship. By establishing the correlation between the actual heating power of the battery under the current state of charge and the current excitation signal frequency and the battery temperature, the current actual heating power can be found from the first mapping relationship by determining the current temperature of the battery, eliminating complex calculation processes and improving response speed.

[0024] In some embodiments, the controller is further configured to: in response to a battery temperature greater than or equal to a second temperature threshold and less than or equal to a first temperature threshold, control a first heating circuit to heat the battery based on a pulse width modulation signal, wherein the second temperature threshold is less than the first temperature threshold. When the battery temperature is below the second temperature threshold, the battery's heating efficiency may be too low. Therefore, heating the battery based on the pulse width modulation signal only when the battery temperature is greater than or equal to the second temperature threshold and less than or equal to the first temperature threshold is beneficial for improving the overall heating efficiency of the battery.

[0025] In some embodiments, the second heating circuit includes a switching branch and an energy storage circuit. The switching branch is connected to the positive and negative terminals of the battery; the energy storage circuit is connected to the battery and the switching branch; and the controller is configured to control the switching branch in response to a battery temperature exceeding a first temperature threshold, causing the battery and the energy storage circuit to discharge to each other. Through the energy storage circuit and the switching circuit, alternating charging and discharging of the battery can be achieved, thereby enabling pulse heating of the battery.

[0026] In some embodiments, there are at least two switching branches and at least two energy storage circuits. Each switching branch includes a first connection point, a second connection point, and a third connection point interconnected by switching elements. The first connection point is connected to the positive terminal of the battery, and the second connection point is connected to the negative terminal of the battery. The first terminal of each energy storage circuit is connected to the third connection point, and the second terminals of each energy storage circuit are interconnected. Through these switching branches, the battery can alternately discharge to the energy storage circuit, and the energy storage circuit can alternately discharge to the battery. When the battery discharges to the energy storage circuit, the battery discharges; when the energy storage circuit discharges to the battery, the battery charges. This enables alternating charging and discharging of the battery.

[0027] In some embodiments, the battery includes two battery packs connected in series. The controller is configured to control the two battery packs to discharge to each other via a second heating circuit in response to the battery temperature exceeding a first temperature threshold. The mutual discharge between the two battery packs via the second heating circuit enables alternating charging and discharging of each battery pack, achieving pulse heating of each battery pack. Furthermore, the energy exchange between the two battery packs during mutual discharge helps maintain their energy balance.

[0028] In some embodiments, the second heating circuit includes a switching branch and an energy storage circuit. The switching branch is connected to the positive and negative terminals of the battery; the energy storage circuit is connected to the switching branch and the midpoint between the two battery packs; the controller is configured to control the two battery packs to discharge to each other via the switching branch and the energy storage circuit in response to the battery temperature exceeding a first temperature threshold. The switching branch and energy storage circuit enable mutual discharge between the two battery packs, resulting in a simple and reliable structure.

[0029] In some embodiments, the switching branch includes a first connection point, a second connection point, and a third connection point interconnected by a switching element. The first connection point is connected to the positive terminal of the battery, and the second connection point is connected to the negative terminal of the battery. A first terminal of the energy storage circuit is connected to the third connection point. The second heating circuit also includes a neutral line, with a first terminal connected to a second terminal of the energy storage circuit and a second terminal connected to the midpoint between the two battery packs. The switching branch, energy storage circuit, and neutral line enable mutual discharge between the two battery packs, thereby enabling alternating charging and discharging of each battery pack.

[0030] In some embodiments, the controller is further configured to: in response to a battery temperature less than or equal to a first temperature threshold, control all switching elements of the switching branch to alternately and simultaneously turn on and off simultaneously, so as to heat the battery based on a pulse width modulation signal. By setting a switching branch connected to the positive and negative terminals of the battery, the switching branch can not only be used to form a second heating circuit, but also function as a first heating circuit, thus simplifying the circuit topology and reducing hardware costs.

[0031] In some embodiments, the controller is further configured to: acquire a second mapping relationship, which characterizes the change in impedance of the battery at different excitation signal frequencies with battery temperature under the current state of charge; and adjust the alternating charge and discharge current of the battery pack based on the current temperature of the battery, the current frequency of alternating charge and discharge of the battery, and the second mapping relationship. By establishing the correlation between the battery impedance and temperature under the current state of charge and the current excitation signal frequency, the current impedance of the battery can be predicted based on the second mapping relationship by determining the battery temperature. This eliminates the need for impedance detection and improves the response rate. Furthermore, by determining the battery impedance and adjusting the current, the real-time heating power of the battery can be controlled to prevent the heating power from becoming too low.

[0032] In some embodiments, the controller is further configured to: acquire the current open-circuit voltage of the battery; and determine a current threshold for adjusting the current of alternating charge and discharge of the battery pack based on the current temperature of the battery, the current open-circuit voltage, and a second mapping relationship. By determining the current threshold for alternating charge and discharge of the battery, the voltage across the battery terminals will not exceed the protection voltage during alternating charge and discharge, which helps to improve the stability of battery heating.

[0033] In some embodiments, the controller is further configured to: acquire a third mapping relationship, which characterizes the change in impedance of the battery at different temperatures under the current state of charge as a function of the excitation signal frequency; and adjust the frequency of alternating charge and discharge of the battery pack based on the battery's current temperature, current state of charge, and the third mapping relationship. By establishing a correlation between the battery's impedance and the excitation signal frequency under the current state of charge and temperature, and adjusting the frequency of alternating charge and discharge of the battery pack based on this correlation, the battery can achieve the corresponding impedance, thereby enabling real-time regulation of the battery's heating power and preventing the battery's heating power from becoming too low.

[0034] In some embodiments, the controller is further configured to: acquire the battery's temperature rise rate; control the first heating circuit to stop heating the battery based on a pulse width modulation signal in response to the battery's temperature rise rate being greater than or equal to a first threshold; and control the second heating circuit to stop alternating charging and discharging of the battery pack within the battery. This can, to some extent, avoid the problem of uneven temperature distribution inside the battery due to an excessively rapid temperature rise rate.

[0035] An embodiment of the third aspect of this application provides a battery management system for managing a battery, the battery including at least one battery pack, the battery management system being configured to: in response to the battery temperature being less than or equal to a first temperature threshold, control the positive and negative terminals of the battery to alternately short-circuit and disconnect based on a pulse width modulation signal to heat the battery; and in response to the battery temperature being greater than the first temperature threshold, control the battery pack to alternately charge and discharge until the battery temperature reaches a target temperature, the first temperature threshold being less than the target temperature.

[0036] An embodiment of the fourth aspect of this application provides an electrical device that includes the battery device described in the above embodiments, the battery device being used to provide electrical energy.

[0037] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, specific embodiments of this application are given below. Attached Figure Description

[0038] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the various drawings denote the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings depict only some embodiments disclosed in this application and should not be construed as limiting the scope of this application.

[0039] Figure 1 This is a schematic diagram of the vehicle structure according to some embodiments of this application; Figure 2 This is one of the flowcharts of a battery heating method according to some embodiments of this application; Figure 3 This is one of the circuit diagrams of a battery device according to some embodiments of this application; Figure 4 This is a second flowchart of a battery heating method according to some embodiments of this application; Figure 5 Impedance-temperature-frequency characteristic curves of batteries in some embodiments of this application; Figure 6 This is one of the impedance-temperature curves of batteries according to some embodiments of this application; Figure 7 This is the second example of the impedance variation curve of a battery according to some embodiments of this application as a function of temperature. Figure 8 This is the third flowchart of a battery heating method according to some embodiments of this application; Figure 9 This is the fourth flowchart of a battery heating method according to some embodiments of this application; Figure 10This is a second circuit diagram of a battery device according to some embodiments of this application; Figure 11 This is the third circuit diagram of a battery device according to some embodiments of this application; Figure 12 This is the fifth of several flowcharts illustrating battery heating methods according to embodiments of this application; Figure 13 This is the sixth flowchart of a battery heating method according to some embodiments of this application.

[0040] Explanation of reference numerals in the attached figures: Vehicle 1000, first battery pack 1011, second battery pack 1012, first switching element 1021, fuse element 1022; Battery device 100, battery 101, first switching circuit 102, switching branch 103, first switching branch 103a, second switching branch 103b, third switching branch 103c, energy storage circuit 104, first energy storage circuit 104a, second energy storage circuit 104b, third energy storage circuit 104c, neutral line 105, vehicle controller 200, motor 300, battery heating method 400; Current sensor 30; First connection point A1, second connection point A2, third connection point A3, main positive relay K11, main negative relay K12, precharge relay K2, precharge resistor R0. Detailed Implementation

[0041] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0043] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0044] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0045] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0046] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0047] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0048] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0049] Currently, the application of rechargeable batteries is becoming increasingly widespread, judging from market trends. They are not only used in energy storage systems for hydropower, thermal power, wind power, and solar power plants, but also extensively in various electronic devices, such as electric bicycles, electric motorcycles, and electric vehicles, as well as in military equipment and aerospace. As the application areas of rechargeable batteries continue to expand, the market demand is also constantly increasing.

[0050] Currently, to heat a battery, it is controlled by alternating charging and discharging. However, this method may prevent the battery from heating continuously at low temperatures.

[0051] At low temperatures, such as below freezing, the internal resistance of batteries increases significantly, especially for solid-state batteries, whose internal resistance at low temperatures is much higher than that of liquid-state batteries. This increased internal resistance reduces the rate of lithium-ion transport and charge transfer, causing lithium-ion supply to lag behind the discharge reaction rate. This leads to the electrode potential deviating from the equilibrium potential, resulting in severe discharge polarization. Affected by discharge polarization, the battery's discharge current is limited, resulting in insufficient heat generation and potentially preventing the battery's heating process from being sustained.

[0052] The internal resistance of a battery will drop rapidly at medium to high temperatures, causing the current flowing through the battery to increase exponentially. At this time, the heat generation rate is too fast, which may cause local overheating.

[0053] Therefore, the heating stability of a battery is greatly affected by temperature, which in turn affects the battery's heating effect.

[0054] Based on the above considerations, in order to improve the battery heating stability and thus enhance the battery heating effect, a battery heating method is designed. The battery includes at least one battery pack. The method includes: in response to the battery temperature being less than or equal to a first temperature threshold, controlling the positive and negative terminals of the battery to alternately short-circuit and disconnect based on a pulse width modulation signal to heat the battery; in response to the battery temperature being greater than the first temperature threshold, controlling the battery pack to alternately charge and discharge until the battery temperature reaches a target temperature, wherein the first temperature threshold is less than the target temperature.

[0055] When the battery temperature is below or equal to the first temperature threshold, the battery's internal resistance increases significantly, and the discharge polarization effect is severe. In this case, the positive and negative terminals of the battery are alternately short-circuited and disconnected based on a pulse width modulation signal. When the positive and negative terminals are short-circuited, the battery generates a large instantaneous current, triggering high-power heat generation. This allows the battery to generate heat rapidly at low temperatures, improving the problem of insufficient heating power and inability to sustain heating due to severe discharge polarization at low temperatures. When the positive and negative terminals are disconnected, no current flows inside the battery, eliminating the need for discharge. This also improves the problem of insufficient heating power and inability to sustain heating due to severe discharge polarization at low temperatures. Furthermore, by controlling the duty cycle of the pulse width modulation signal, the battery obtains a stable equivalent average current, enabling continuous heating of the battery at low temperatures and improving heating stability. When the temperature exceeds the first temperature threshold, the battery temperature is relatively high, and the battery's internal resistance drops rapidly. In this case, the battery pack is controlled to perform alternating charging and discharging. Even if the internal resistance drops rapidly, the continuous increase in current can be limited by periodic current commutation. This avoids the sudden increase in current caused by the sudden drop in internal resistance, which would lead to increased heat generation and achieve battery heating stability.

[0056] The battery cells disclosed in this application can be used, but are not limited to, in electrical devices or energy storage devices such as vehicles, ships, or aircraft. A power system comprising the battery cells and batteries disclosed in this application can be used to construct such an electrical device or energy storage device.

[0057] This application provides an electrical device that uses a battery as a power source. The electrical device can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0058] This application also provides an energy storage device that uses a battery as a power source. The energy storage device can be, but is not limited to, an energy storage container, an energy storage cabinet, an energy storage power station, an energy storage battery pack, or a portable energy storage system.

[0059] For ease of explanation, the following embodiments will be described using a vehicle 1000 as an example of an electrical device according to an embodiment of this application.

[0060] Please refer to Figure 1 , Figure 1This is a schematic diagram of the structure of a vehicle provided in some embodiments of this application. The vehicle 1000 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A battery device 100 is installed inside the vehicle 1000, and the battery device 100 can be located at the bottom, front, or rear of the vehicle 1000. The battery device 100 can be used to power the vehicle 1000; for example, the battery device 100 can serve as the operating power source for the vehicle 1000. The vehicle 1000 may also include a vehicle controller 200 and a motor 300. The vehicle controller 200 is used to control the battery device 100 to supply power to the motor 300, for example, to meet the power needs of the vehicle 1000 during starting, navigation, and driving.

[0061] In some embodiments of this application, the battery device 100 can not only serve as the operating power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0062] refer to Figure 2 This application provides a battery heating method 400, wherein the battery includes at least one battery pack, and the method includes: Step 410: In response to the battery temperature being less than or equal to a first temperature threshold, the positive and negative terminals of the battery are alternately shorted and disconnected based on a pulse width modulation signal to heat the battery. Step 420: In response to the battery temperature being greater than the first temperature threshold, control the battery pack to perform alternating charging and discharging until the battery temperature reaches the target temperature and the first temperature threshold is less than the target temperature.

[0063] Pulse Width Modulation (PWM) signal (hereinafter referred to as PWM signal) is a digital control signal that adjusts the equivalent average value of the output signal by periodically changing the duration of the high level in a pulse sequence.

[0064] By adjusting the duty cycle of the PWM signal, the average output current can be adjusted accordingly. The duty cycle is the ratio of the high-level duration to one PWM signal cycle within one period.

[0065] The average energy input to the battery per unit time can be changed by adjusting the duty cycle of the PWM signal. Furthermore, the high-frequency switching of the PWM signal makes the equivalent average current continuous, which in turn makes the heat generated by the battery per unit time more stable, thus improving the battery heating stability.

[0066] In some embodiments, the BMS (Battery Management System) can output a PWM signal. The BMS can detect the battery temperature, and if the detected battery temperature is less than or equal to a first temperature threshold, the BMS can send a command to the MCU (Microcontroller Unit) to output a PWM signal. The MCU then outputs the PWM signal based on the command. The MCU can control the alternating shorting and opening of the positive and negative terminals of the battery.

[0067] refer to Figure 3 In some embodiments, a first switching circuit 102 can be connected between the positive and negative terminals of battery 101. The first switching circuit 102 connects the positive and negative terminals of battery 101 and can switch the positive and negative terminals of battery 101 on and off. When the first switching circuit 102 is on, the positive and negative terminals of battery 101 are short-circuited, causing battery 101 to short-circuit and allowing current to flow through battery 101. When the first switching circuit 102 is off, the positive and negative terminals of battery 101 are disconnected, and no current flows through battery 101. The MCU can control the first switching circuit to alternately turn on and off based on a preset PWM signal, thereby controlling the positive and negative terminals of battery 101 to alternately short-circuit and open, so that current flows through battery 101 periodically. By controlling the frequency and on / off time of the alternating short-circuit and open-off of the positive and negative terminals of battery 101, it is equivalent to inputting a PWM signal with a certain frequency and duty cycle into battery 101.

[0068] In some embodiments, the positive terminal of battery 101 is connected to a main positive relay K11, and the negative terminal of battery 101 is connected to a main negative relay K12. When battery 101 needs to be powered on, main positive relay K11 and main negative relay K12 are turned on, realizing the output of battery 101 signal. One of the main positive relay K11 and main negative relay K12 may also be connected in parallel with a pre-charge relay K2 and a pre-charge resistor R0. When the temperature of battery 101 is less than or equal to a first temperature threshold, battery 101 cannot be powered on. Therefore, at least one of the main positive relay K11 and main negative relay K12 is in an open state, and pre-charge relay K2 is also in an open state.

[0069] The positive terminal of battery 101 refers to the total positive terminal after all battery packs in battery 101 are connected, and the negative terminal of battery 101 refers to the total negative terminal after all battery packs in battery 101 are connected.

[0070] Continue to refer to Figure 3In some embodiments, the first switching circuit 102 may include a first switching element 1021, which controls the switching on and off of the positive and negative terminals of the battery 101. In some embodiments, the BMS may control the first switching element 1021 to alternately switch on and off according to a preset frequency and duty cycle in response to the temperature of the battery 101 being less than or equal to a first temperature threshold, thereby inputting a PWM signal to the battery 101. Here, the duty cycle refers to the ratio of the on-time of the first switching element in one on and off cycle to the entire cycle.

[0071] In some embodiments, the first switching element 1021 may include, but is not limited to, a switching transistor. The high switching speed of the switching transistor facilitates high-frequency switching and generates a PWM signal that meets the requirements.

[0072] Continue to refer to Figure 3 In some embodiments, the first switching circuit 102 may further include a fuse 1022, which is connected in series with the first switching element 1021 between the positive and negative terminals of the battery 101. The fuse 1022 is configured to disconnect the first switching circuit 102 when the current in the battery 101 is too high. It is understood that because a large current is input to the battery 101 by short-circuiting it in step 410, the current in the battery 101 is relatively large, making it more prone to overcurrent problems. Therefore, in this embodiment, a fuse 1022 is provided to protect the battery 101 from overcurrent. In some embodiments, the fuse 1022 may include, but is not limited to, a fuse or a circuit breaker.

[0073] When the positive and negative terminals of battery 101 are short-circuited, a large instantaneous current is generated, triggering high-power heat generation. This allows battery 101 to quickly generate heat at low temperatures, further improving the problem of insufficient heating power and inability to sustain temperature rise caused by severe discharge polarization at low temperatures. When the positive and negative terminals of battery 101 are disconnected, no current flows through battery 101. Thus, by controlling the alternating short-circuiting and disconnection of the positive and negative terminals of battery 101, the periodic change in the current flowing through battery 101 is generated, thereby forming a PWM signal.

[0074] The first temperature threshold can be a specific temperature value or a temperature range. It can be determined based on the change in the battery's internal resistance with temperature. For example, if the battery's internal resistance significantly decreases when the temperature is less than or equal to a certain value, then that temperature value can be determined as the first temperature threshold. Different types of batteries can have different first temperature thresholds. Battery types can include, but are not limited to, solid-state batteries and liquid batteries. For example, for solid-state batteries, the first temperature threshold could be 0°C.

[0075] It is worth noting that in some embodiments, the battery may include multiple battery packs, which may be connected in series or in parallel. Optionally, in step 410, heating may be performed on all battery packs in the battery based on a PWM signal, or heating may be performed on a portion of the battery packs based on a PWM signal.

[0076] In some embodiments, the battery pack may include at least one battery cell, and the temperature of the battery cell surface can be detected to determine the battery temperature. Exemplarily, the side of the battery cell includes two first surfaces disposed opposite each other along its width direction and two second surfaces disposed opposite each other along its length direction, wherein the surface area of ​​the first surfaces may be larger than the surface area of ​​the second surfaces. The battery temperature can be determined by actually detecting the temperature of the first surfaces.

[0077] In step 420, when the battery temperature is greater than the first temperature threshold but less than the target temperature, the heating of the battery based on the PWM signal is stopped, and the battery is heated by controlling the battery pack to alternately charge and discharge.

[0078] Alternating charge and discharge of the battery pack refers to the battery pack alternating between charging and discharging.

[0079] In some embodiments, all battery packs in the battery can be charged and discharged synchronously. For example, all battery packs can be controlled to charge synchronously first, and then all battery packs can be controlled to discharge synchronously, and the above steps can be performed alternately to achieve alternating charging and discharging of battery packs.

[0080] In other embodiments, the battery may include two battery packs, and the two battery packs may discharge into each other, achieving alternating charging and discharging of each battery pack. For example, the two battery packs include a first battery pack and a second battery pack. First, the first battery pack can be controlled to discharge into the second battery pack, so that the first battery pack is in a discharging state and the second battery pack is in a charging state. Then, the second battery pack can be controlled to discharge into the first battery pack, so that the first battery pack is in a charging state and the second battery pack is in a discharging state. In this way, although the first and second battery packs are not charged and discharged synchronously, each battery pack undergoes both alternating charging and discharging processes.

[0081] By controlling the alternating charging and discharging of the battery pack, the current flowing through the battery pack is a pulsed current, and current flows through the battery pack regardless of whether the battery pack is charging or discharging, which enables continuous heating of the battery pack.

[0082] It is worth noting that pulse current can be either symmetrical or asymmetrical. Symmetrical pulse current usually refers to positive and negative pulses that are basically the same in terms of parameters such as amplitude, pulse width, and duty cycle, with the waveform symmetrical about the time axis and the energy distribution of the positive and negative half-cycles relatively balanced. Asymmetrical pulse current, on the other hand, has differences in amplitude, duration, waveform shape, or duty cycle, and the positive and negative pulse components are not equal.

[0083] Once the battery reaches the target temperature, stop heating the battery.

[0084] The target temperature can be set as needed; for example, the target temperature can be set to 30°C or 40°C.

[0085] In the above technical solution, when the battery temperature is less than or equal to the first temperature threshold, the battery's internal resistance increases significantly, and the discharge polarization effect is severe. In this case, the positive and negative terminals of the battery are alternately short-circuited and disconnected based on the pulse width modulation signal. When the positive and negative terminals are short-circuited, the battery short-circuits and generates a large instantaneous current, triggering high-power heat generation. This allows the battery to generate heat quickly at low temperatures, improving the problem of insufficient heating power and inability to continuously raise the temperature due to severe discharge polarization at low temperatures. When the positive and negative terminals of the battery are disconnected, no current flows inside the battery, and the battery does not need to discharge. This improves the problem of insufficient heating power and inability to continuously raise the temperature due to severe discharge polarization at low temperatures. Furthermore, by controlling the duty cycle of the pulse width modulation signal, the battery obtains a stable equivalent average current, thereby enabling continuous heating of the battery at low temperatures and improving heating stability. When the temperature exceeds the first temperature threshold, the battery temperature is relatively high, and the battery's internal resistance drops rapidly. In this case, the battery pack is controlled to perform alternating charging and discharging. Even if the internal resistance drops rapidly, the continuous increase in current can be limited by periodic current commutation. This avoids the sudden increase in current caused by the sudden drop in internal resistance, which would lead to increased heat generation and achieve battery heating stability.

[0086] refer to Figure 4 According to some embodiments of this application, step 410 may further include: Step 4101: Obtain the preset heating power required to heat the battery 101; Step 4102: Based on the preset heating power and the impedance characteristics of the battery 101 at different temperatures and under different states of charge, determine the frequency of the pulse width modulation signal.

[0087] In step 4101, a preset heating power for heating the battery 101 is determined, so that the frequency and duty cycle of the PWM signal can be adjusted according to the preset heating power. This ensures that the average power of the entire heating process can be stabilized at or near the preset heating power, which is beneficial to improving the stability of heating the battery 101.

[0088] In some embodiments, in step 4101, the preset heating power can be determined by the following formula (1). (1) Where P1 is the preset heating power, C is the specific heat capacity of battery 101, and m is the mass of battery 101. Let t be the difference between the initial heating temperature and the desired temperature of battery 101, and let t be the estimated heating time for battery 101 to rise from the initial heating temperature to the desired temperature. In some embodiments, the desired temperature of battery 101 can be a first temperature threshold, that is, during the period when battery 101 rises from the initial heating temperature at the beginning of heating to the first temperature threshold, the average heating power is stable at or near a preset heating power. In other words, during the heating of battery 101 based on the PWM signal, the average heating power is stable at or near a preset heating power. In other embodiments, the desired temperature of battery 101 can also be a target temperature, so that the average heating power can be stable at or near a preset heating power throughout the entire heating period of battery 101.

[0089] In the above formula (1), the preset heating power is determined based on the temperature required to be reached by the battery 101 and the expected heating time. In this way, during the subsequent heating process, by controlling the average heating power to be close to the preset heating power, the temperature and heating time of the battery 101 after heating can meet expectations.

[0090] Impedance characteristics can be used to characterize the impedance of battery 101 as a function of state of charge (SOC), temperature, and frequency. Electrochemical impedance spectra of battery 101 at different SOCs, temperatures, and frequencies can be obtained. Impedance parameters can be fitted from the electrochemical impedance spectra to establish impedance characteristic curves. The impedance of battery 101 can be represented by the real part of the impedance in the electrochemical impedance spectrum. As an example, Figure 5 The diagram shows the variation of the real part of the impedance of a 50% SOC battery 101 with the frequency of the excitation signal at different temperatures. For ease of fitting and calibration, the real part of the impedance can be transformed using the natural logarithm, and the temperature can be transformed using the reciprocal, so that the natural logarithm of the real part of the impedance has a linear relationship with the reciprocal of the temperature. As an example, Figures 6 to 7 The natural logarithm of the real part of the impedance of a 50% SOC battery 101 varies with the reciprocal of temperature at excitation signal frequencies of 10 Hz and 50 Hz.

[0091] In some embodiments, the battery 101 can be scanned by EIS before each heating to obtain the latest electrochemical impedance spectrum, and the impedance characteristics of the battery 101 can be obtained based on the latest electrochemical impedance spectrum.

[0092] In other embodiments, impedance errors after repeated use can also be corrected based on a K-value attenuation model.

[0093] For example, battery 101 can be scanned with EIS (Electrochemical Impedance Spectroscopy) at regular intervals to update its impedance characteristics, without needing to perform an EIS scan before each heating. If battery 101 needs to be heated during the period when the impedance characteristics are not updated, a K-value decay model can be used to correct the previously updated impedance characteristics based on the number of cycles of battery 101, thus obtaining the corrected impedance characteristics. The previously updated impedance characteristics serve as the baseline impedance characteristics.

[0094] For example, EIS scanning can be performed on battery 101 only when it is first manufactured to obtain initial impedance characteristics as a reference impedance characteristic. For each subsequent heating, a K-value decay model can be used to correct the reference impedance characteristics. The excitation signal frequency corresponding to the reference impedance characteristics corrected by the K-value decay model can be 50Hz.

[0095] A K-value decay model can be established by setting an exponential correlation model between the number of battery cycles and the impedance decay coefficient K. The decay coefficient K is used to correct the impedance data in the reference electrochemical impedance spectrum, thus offsetting the deviation between the measured impedance value and the reference value caused by the aging of battery 101.

[0096] The expression for the K-value decay model is as follows:

[0097] Where K is the impedance attenuation coefficient, and K0 is the initial reference coefficient, used to characterize the K value of battery 101 at 0 cycles. is the aging degradation rate constant, used to characterize the rate of aging, and cycle is the number of battery cycles (101).

[0098] In some embodiments, a full life cycle aging test can be performed on battery 101. The impedance values ​​at different cycle numbers and across all states of charge (SOC) and frequencies are measured, and K0 and K0 are obtained through exponential fitting. Determine the expression for the K-value model.

[0099] During the use of battery 101, the BMS will automatically count the number of alternating charge and discharge cycles of battery 101 to obtain the current cycle. Substituting the current cycle value into the K-value decay model can obtain the current K value.

[0100] After obtaining the current K value, the impedance in the reference electrochemical impedance spectrum can be corrected using the following formula (2).

[0101] (2) Among them, Z eis For the corrected impedance, Z 基准 This is the reference impedance.

[0102] In step 4102, the temperature and SOC of battery 101 can be determined first, and the corresponding impedance characteristics can be obtained. Then, the relationship between the impedance of battery 101 and the frequency of excitation signal can be determined. The actual power of battery 101 can be calculated by the following formula (3).

[0103] (3) Where P2 is the actual heating power of battery 101, U is the voltage of battery 101, and R is the current impedance of battery 101.

[0104] In some embodiments, U can be determined by directly detecting the current open-circuit voltage of battery 101. Since the PWM signal is a high-frequency, fast-switching signal, during the extremely short instant when the PWM signal is a low-level signal (the switching transistor is off), there is no current flowing through the battery 101, and the voltage across the battery 101 is the open-circuit voltage. The voltage across the battery 101 at this time is used to characterize the electromotive force of the battery 101.

[0105] As can be seen from formula (3), the actual power of battery 101 is related to the impedance of battery 101, and the impedance is related to the frequency of PWM signal. When the preset heating power is determined, the required impedance of battery 101 can be determined, and thus the frequency of PWM signal can be determined.

[0106] In the above technical solution, the impedance characteristics of battery 101 can be used to characterize the change of battery 101 impedance with frequency. By selecting the optimal frequency based on the preset heating power, the impedance of battery 101 can be adjusted, so that the average heating power of battery 101 can be maintained at or near the preset heating power. This is beneficial to the overall heating rate of battery 101 being relatively stable, and to a certain extent avoids the problem of uneven internal temperature distribution caused by the excessively fast heating rate of battery 101.

[0107] According to some embodiments of this application, step 4102 includes: Obtain the initial open-circuit voltage of battery 101 at the initial heating temperature; Based on the initial open-circuit voltage, preset heating power, and impedance characteristics of battery 101, the initial impedance of battery 101 at the initial heating temperature and the initial frequency corresponding to the initial impedance are determined, and the initial frequency is used as the frequency of the pulse width modulation signal.

[0108] In other words, the initial frequency serves as the fixed frequency of the PWM signal, and the frequency of the PWM signal remains constant throughout the heating process. Using a fixed frequency for the PWM signal simplifies the control logic, as only the duty cycle needs to be adjusted to regulate the heating power.

[0109] In some embodiments, the SOC-OCV curve of battery 101 at the time of manufacture can be obtained. The SOC-OCV curve is used to characterize the change of open-circuit voltage of battery 101 with SOC. By determining the initial open-circuit voltage at the initial heating moment of battery 101, the corresponding SOC can be obtained from the SOC-OCV curve as the SOC at the initial heating moment of the battery, and then the corresponding impedance relationship can be determined.

[0110] Then, the initial open-circuit voltage and the preset heating power can be substituted into the above formula (2) to obtain the initial impedance required for battery 101 to reach the preset heating power at the initial heating moment. Based on the impedance characteristics of battery 101 at the initial heating temperature and the SOC at the initial heating moment, the impedance of battery 101 under the current state can be obtained as a function of frequency, such as... Figure 5 As shown. Based on this impedance relationship, the initial frequency required for battery 101 to reach its initial impedance can be obtained.

[0111] In the above technical solution, the actual heating power of battery 101 is related to the voltage across battery 101 and the impedance of battery 101. At the initial heating moment of battery 101, the impedance required for the initial heating moment of battery 101 can be deduced based on the initial open-circuit voltage and the initial preset heating power. The impedance characteristics of battery 101 can characterize the relationship between impedance and frequency. Therefore, the optimal frequency of the PWM signal input to battery 101 at the initial heating moment can be determined based on the obtained impedance, so that battery 101 can heat at the preset heating power at the initial heating moment. In this way, during the subsequent heating process, the duty cycle of the PWM signal can be adjusted based on the heating power at the initial heating moment, so that the average heating power of battery 101 is stabilized at or near the preset heating power.

[0112] refer to Figure 8 According to some embodiments of this application, step 410 may further include: Step 4103: Obtain the preset heating power required to heat the battery 101; Step 4104: Obtain the current actual heating power of battery 101; Step 4105: Determine the duty cycle of the pulse width modulation signal based on the ratio of the preset heating power to the current actual heating power of the battery 101.

[0113] In step 4103, the method for obtaining the preset heating power can be the same as the method for obtaining the preset heating power of battery 101 in step 4101 above, and will not be repeated here.

[0114] In step 4104, the actual heating power of battery 101 can be obtained based on formula (3). In some embodiments, U in formula (3) can be determined by the battery management system detecting the open-circuit voltage of battery 101. R can be obtained by actually detecting the resistance of battery 101, or it can be obtained based on the SOC, temperature, PWM signal frequency and impedance characteristics of battery 101.

[0115] It is understandable that within one PWM signal cycle, the average heating power of battery 101 is equal to the product of the actual heating power of battery 101 and the duty cycle. Therefore, the ratio of the preset heating power to the current actual heating power of battery 101 is used as the current duty cycle, so that the average heating power of battery 101 can be kept near the preset heating power.

[0116] It is worth noting that as the temperature of battery 101 continues to rise, the impedance of battery 101 will gradually decrease, causing the current actual heating power to gradually increase. In order to keep the average heating power of battery 101 near the preset heating power, the duty cycle needs to be adjusted in real time based on the current actual heating power of battery 101.

[0117] In the above technical solution, the average power within one cycle is obtained by multiplying the actual heating power by the duty cycle. The ratio of the preset heating power to the current actual heating power is determined as the duty cycle of the PWM signal, which can adjust the duty cycle in real time so that the average heating power of the battery 101 is stabilized at or near the preset heating power, thereby improving the heating stability of the battery 101.

[0118] According to some embodiments of this application, step 4104 includes: Obtain the first mapping relationship, which is used to characterize the change of the actual heating power of battery 101 with the temperature of battery 101 under the current state of charge and the current excitation signal frequency. Based on the current temperature of battery 101 and the first mapping relationship, the current actual heating power of battery 101 is determined.

[0119] When obtaining the actual heating power of battery 101 based on formula (3), U in formula (3) can be determined by detecting the current open-circuit voltage of battery 101. During a heating process, the SOC of battery 101 usually does not change, so the open-circuit voltage can be considered fixed. Therefore, the only variable in formula (3) is the impedance R. According to the impedance characteristics of battery 101, when the SOC of battery 101 and the frequency of PWM signal are constant, the impedance of battery 101 is related to the temperature of battery 101. Therefore, it can be determined that there is a certain mapping relationship between the actual heating power of battery 101 and the temperature of battery 101, and thus the first mapping relationship can be obtained.

[0120] In some embodiments, in order to obtain the first mapping relationship, the current SOC of the battery 101 and the frequency of the PWM signal input to the battery 101 can be determined first, and then the impedance of the battery 101 as a function of temperature can be obtained under the current SOC and the PWM signal frequency. Figures 6 to 7 As an example, the relationship between the real part of the impedance of a 50% SOC battery 101 and temperature is shown under different excitation signal frequencies. Using the above formula (3), the relationship between the impedance of the battery 101 and temperature can be converted into a first mapping relationship between the actual heating power and temperature.

[0121] In some embodiments, to simplify the control logic of the BMS, the first mapping relationship can be directly stored in the BMS. It is worth noting that since the impedance of battery 101 changes with temperature, influenced by the battery's state of charge (SOC) and the PWM signal frequency, the first mapping relationship of battery 101 under different SOCs and PWM signal frequencies can be obtained. The BMS can obtain the current SOC of battery 101 and the PWM signal frequency to determine the corresponding first mapping relationship, and obtain the current temperature of battery 101, determining the current actual heating power of battery 101 within the determined first mapping relationship.

[0122] In the above technical solution, by establishing the correlation between the actual heating power of the battery 101 under the current state of charge and the current excitation signal frequency and the temperature of the battery 101, the current actual heating power can be found from the first mapping relationship by determining the current temperature of the battery 101, thus eliminating the complex calculation process and improving the response speed.

[0123] According to some embodiments of this application, the battery 101 heating method 400 further includes: In response to the temperature of battery 101 being greater than or equal to a second temperature threshold and less than or equal to a first temperature threshold, battery 101 is heated based on a pulse width modulation signal, wherein the second temperature threshold is less than the first temperature threshold.

[0124] In other words, the battery 101 is not heated when its temperature is below the second temperature threshold.

[0125] The second temperature threshold can be a specific temperature value or a temperature range. If the temperature of battery 101 is lower than the second temperature threshold, the temperature of battery 101 is too low, resulting in low heating efficiency and hindering the improvement of the overall heating efficiency of battery 101. Different types of batteries 101 can be configured with different second temperature thresholds. For example, for a solid-state battery 101, the second temperature threshold can be -30℃.

[0126] In the above technical solution, the heating efficiency of the battery 101 may be too low when the temperature of the battery 101 is less than the second temperature threshold. Therefore, the battery 101 is heated based on the PWM signal only when the temperature of the battery 101 is greater than or equal to the second temperature threshold and less than or equal to the first temperature threshold, which is beneficial to improving the overall heating efficiency of the battery 101.

[0127] refer to Figure 9 According to some embodiments of this application, step 420 includes: Step 4201: Obtain the second mapping relationship. The second mapping relationship is used to characterize the change of impedance of battery 101 with temperature under the current state of charge and the current alternating charge and discharge frequency. Step 4202: Based on the current temperature of battery 101 and the second mapping relationship, adjust the current for alternating charging and discharging of the battery pack.

[0128] Controlling the alternating charging and discharging of the battery pack is equivalent to inputting a pulse current into the battery pack. Therefore, the frequency of the alternating charging and discharging of the battery pack is also the frequency of the pulse current. During the alternating charging and discharging of the battery pack, the impedance of battery 101 still satisfies the impedance characteristics of battery 101 with respect to the frequency of alternating charging and discharging. That is, when the state of charge (SOC) of battery 101 and the frequency of alternating charging and discharging are constant, the impedance of battery 101 is related to the temperature of battery 101, thus allowing the determination of the second mapping relationship. Since the relationship between the impedance of battery 101 and temperature is affected by the battery SOC and the frequency of the excitation signal input to battery 101, the second mapping relationship of battery 101 under different SOCs and different excitation signal frequencies can be obtained. Here, the excitation signal frequency is the frequency of alternating charging and discharging.

[0129] The corresponding second mapping relationship can be determined based on the current SOC of battery 101 and the frequency of alternating charging and discharging.

[0130] It is understandable that as the temperature of battery 101 increases, the impedance of battery 101 decreases accordingly. According to the following formula (4), it is not difficult to find that if the current of alternating charging and discharging of the battery pack remains unchanged, the actual heating of battery 101 will become lower and lower, which will lead to insufficient heat generation power of battery 101.

[0131] P2=I 2 R (4) Where P2 is the actual power of battery 101, I is the current of alternating charging and discharging of the battery pack, and R is the current impedance of battery 101.

[0132] It is understandable that during the heating of battery 101 based on PWM signal, since the current is uncontrollable, the actual heating power of battery 101 is calculated using formula (3). During the alternating charging and discharging of battery pack to heat battery 101, since the current is controllable, the actual heating power of battery 101 can be calculated using formula (4).

[0133] To avoid insufficient heat generation in battery 101 to some extent, the current of alternating charging and discharging of the battery pack can be adjusted based on the actual impedance of battery 101 to improve the actual heating power of battery 101.

[0134] Therefore, a second mapping relationship can be determined based on the current SOC of battery 101 and the frequency of alternating charge and discharge. Based on the second mapping relationship, after determining the current temperature of battery 101, the corresponding impedance of battery 101 can be determined, and then the direction of current adjustment can be determined based on the impedance of battery 101. For example, the magnitude of the current can be adjusted so that the actual heating power of battery 101 reaches or is close to a preset heating power.

[0135] In some embodiments, based on the above formula (4), if the actual heating power of battery 101 is kept at the preset heating power, then P2 is a fixed value, and the changing values ​​are the current and impedance of battery 101. By determining the impedance, the current of battery 101 can be determined. That is, there is a mapping relationship between the impedance of battery 101 and the current of battery 101. There is also a mapping relationship between the impedance of battery 101 and the temperature and resistance of battery 101. That is, by determining the temperature of battery 101, the impedance of battery 101 can be determined. Based on this, when the SOC of battery 101 and the excitation signal frequency are constant, based on the current temperature of battery 101 and the second mapping relationship, it can be determined that there is a mapping relationship between the temperature of battery 101 and the current of battery 101. Therefore, after the SOC of battery 101 and the excitation signal frequency are determined, the current of alternating charging and discharging of battery pack can be adjusted by obtaining the temperature of battery 101 so that the actual heating power of battery 101 is the preset heating power.

[0136] In some embodiments, battery 101 may be connected to a second heating circuit for alternating charge and discharge of the battery pack. The second heating circuit may be controlled by a BMS. For example, the BMS controls the second heating circuit to cause the battery pack to alternately charge and discharge in response to the temperature of battery 101 being greater than a first temperature threshold and less than a target temperature.

[0137] refer to Figure 3 In some embodiments, the second heating circuit includes at least two switching branches 103 and at least two energy storage circuits 104. The switching branches 103 include a first connection point A1, a second connection point A2, and a third connection point A3 that are interconnected by switching elements. The first connection point A1 is connected to the positive terminal of the battery 101, and the second connection point A2 is connected to the negative terminal of the battery 101. The at least two switching branches 103 are connected to the at least two energy storage circuits 104 in a one-to-one correspondence. The first end of the energy storage circuit 104 is connected to the third connection point A3, and the second end of each energy storage circuit 104 is connected to each other.

[0138] By controlling the switch branch 103, the battery 101 and the energy storage circuit 104 discharge to each other. In other words, the switch branch 103 alternately performs the discharge of the battery 101 to the energy storage circuit 104 and the discharge of the energy storage circuit 104 to the battery 101. When the battery 101 discharges to the energy storage circuit 104, the battery 101 discharges, and when the energy storage circuit 104 discharges to the battery 101, the battery 101 is charged. In this way, the alternating charging and discharging of the battery 101 can be achieved.

[0139] The first connection point A1 can be the node connecting the switch branch 103 to the positive terminal of the battery 101, the second connection point A2 can be the node connecting the switch branch 103 to the negative terminal of the battery 101, and the third connection point A3 can be the node connecting the energy storage circuit 104 and the switch branch 103.

[0140] The first connection point A1, the second connection point A2, and the third connection point A3 are interconnected by a switching element. That is, any two of the first connection point A1, the second connection point A2, and the third connection point A3 can be connected by a switching element. For example, when the first connection point A1 and the second connection point A2 are connected by a switching element, a path is formed between the first connection point A1 and the second connection point A2.

[0141] In some embodiments, the switching element may include, but is not limited to, a switching transistor. The switching transistor may include a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) or an IGBT (Insulated-Gate Bipolar Transistor), etc.

[0142] Since the conduction current of the switching transistor can be controlled by the voltage applied to its control terminal, the alternating charging and discharging current of the battery pack can be adjusted by controlling the magnitude of the conduction current flowing through the switching transistor.

[0143] In some embodiments, the energy storage circuit 104 may include an inductor.

[0144] In some embodiments, in response to the temperature of battery 101 exceeding a first temperature threshold, the first step and the second step can be alternately and repeatedly executed to heat battery 101. The first step involves discharging battery 101 to energy storage circuit 104 via switching branch 103, whereby energy storage circuit 104 stores electrical energy. The second step involves discharging energy storage circuit 104 to battery 101 via switching branch 103, whereby battery 101 is charged. By alternately executing the first and second steps, alternating charging and discharging of battery 101 is achieved.

[0145] For example, the explanation will be given with three switch branches 103 and three energy storage circuits 104. Figure 3 As shown, the three switch branches 103 are the first switch branch 103a, the second switch branch 103b, and the third switch branch 103c, respectively, and the three energy storage circuits 104 are the first energy storage circuit 104a, the second energy storage circuit 104b, and the third energy storage circuit 104c, respectively. The first switch branch 103a is connected to the first energy storage circuit 104a, the second switch branch 103b is connected to the second energy storage circuit 104b, and the third switch branch 103c is connected to the third energy storage circuit 104c.

[0146] In some embodiments, the first step may include: controlling the first connection point A1 of the first switch branch 103a and the second switch branch 103b to connect with the third connection point A3; controlling the second connection point A2 of the first switch branch 103a and the second switch branch 103b to disconnect from the third connection point A3; and controlling the first connection point A1 of the third switch branch 103c to disconnect from the third connection point A3, and controlling the second connection point A2 of the third switch branch 103c to connect with the third connection point A3. In this way, the first energy storage circuit 104a and the second energy storage circuit 104b are connected in parallel and then in series with the third energy storage circuit 104c. Current flows out from the positive terminal of battery 101, passes through the first connection point A1 and the third connection point A3 of the first switch branch 103a and the second switch branch 103b, flows into the parallel first energy storage circuit 104a and the second energy storage circuit 104b, then flows into the third energy storage circuit 104c, and finally flows from the third connection point A3 of the third switch branch 103c to the second connection point A2, and finally flows back to the negative terminal of battery 101, forming a complete circuit. During this process, battery 101 discharges, and energy storage circuit 104 stores electrical energy.

[0147] The second step may include: disconnecting the first connection point A1 of the first switch branch 103a and the second switch branch 103b from the third connection point A3; connecting the second connection point A2 of the first switch branch 103a and the second switch branch 103b from the third connection point A3; and connecting the first connection point A1 of the third switch branch 103c from the third connection point A3, and disconnecting the second connection point A2 of the third switch branch 103c from the third connection point A3. Current flows out of the energy storage circuit 104, through the third connection point A3 and the first connection point A1 of the third switch branch 103c, to the positive terminal of the battery 101, then flows out from the negative terminal of the battery 101, and then flows back to the energy storage circuit 104 through the second connection point A2 and the third connection point A3 of the first switch branch 103a and the second switch branch 103b, forming a complete loop. During this process, the energy storage circuit 104 discharges, and the battery 101 charges.

[0148] like Figure 10 As shown, in some embodiments, battery 101 may include two battery packs, and the second heating circuit may also include: a switching branch 103, an energy storage circuit 104, and a neutral line 105. The switching branch 103 includes a first connection point A1, a second connection point A2, and a third connection point A3 interconnected by a switching element. The first connection point A1 is connected to the positive terminal of battery 101, and the second connection point A2 is connected to the negative terminal of battery 101. The energy storage circuit 104 has its first end connected to the third connection point A3. The first end of the neutral line 105 is connected to the second end of the energy storage circuit 104, and the second end of the neutral line 105 is connected to the midpoint between the two battery packs. The switching branch 103 and the energy storage circuit 104 are connected in a one-to-one correspondence, and the number of both the switching branch 103 and the energy storage circuit 104 can be one or multiple.

[0149] In response to the temperature of battery 101 exceeding a first temperature threshold, the two battery packs can be controlled to discharge to each other via switch branch 103, energy storage circuit 104, and neutral line 105.

[0150] For example, the two battery packs are a first battery pack 1011 and a second battery pack 1012. The positive terminal of the first battery pack 1011 is connected to a first connection point A1, the negative terminal of the first battery pack 1011 is connected to the positive terminal of the second battery pack 1012, and the negative terminal of the second battery pack 1012 is connected to a second connection point A2. In response to the temperature of battery 101 exceeding a first temperature threshold, battery 101 can be alternately controlled to be in a first heating stage and a second heating stage. In the first heating stage, a third step and a fourth step can be executed alternately in sequence. The third step causes the first battery pack 1011 to charge the energy storage circuit 104 through the switch branch 103, and the fourth step causes the energy storage circuit 104 to charge the second battery pack 1012 through the switch branch 103. Thus, in the first heating stage, the first battery pack 1011 can charge the second battery pack 1012. In the second heating stage, steps five and six can be executed alternately in sequence. Step five charges the energy storage circuit 104 via the switch branch 103, and step six charges the first battery pack 1011 via the switch branch 103. Thus, in the second heating stage, the second battery pack 1012 can charge the first battery pack 1011.

[0151] For example, such as Figure 10 As shown, taking an example where there are three switching circuits and three energy storage circuits 104. The third step may include: controlling the first connection point A1 and the third connection point A3 of all switching circuits to be turned on, and the second connection point A2 and the third connection point A3 to be turned off. The current flows from the positive terminal of the first battery pack 1011 through the first connection point A1 and the third connection point A3 of the switching circuit, and then flows back to the negative terminal of the first battery pack 1011 via the neutral line 105. The energy storage circuit 104 stores energy. The fourth step may include: controlling the second connection point A2 and the third connection point A3 of all switching circuits to be turned on, and the first connection point A1 and the third connection point A3 to be turned off. The current flows from the energy storage circuit 104 through the neutral line 105 through the positive terminal of the second battery pack 1012, the negative terminal of the second battery pack 1012, and the second connection point A2 and the third connection point A3 of the switching circuit, and then flows back to the energy storage circuit 104.

[0152] The fifth step may include: controlling the second connection point A2 and the third connection point A3 of all switching circuits to be turned on, and the first connection point A1 and the third connection point A3 to be turned off. The current flows from the positive terminal of the second battery pack 1012 through the neutral line 105, through the energy storage circuit 104, the third connection point A3 and the second connection point A2 of the switching circuit, and then flows back to the negative terminal of the second battery pack 1012. The energy storage circuit 104 stores energy. The sixth step may include: controlling the first connection point A1 and the third connection point A3 of all switching circuits to be turned on, and the second connection point A2 and the third connection point A3 to be turned off. The current flows from the energy storage circuit 104 through the third connection point A3 of the switching circuit, the first connection point A1, the positive terminal of the first battery pack 1011, the negative terminal of the first battery pack 1011, and then flows back to the energy storage circuit 104 through the neutral line 105.

[0153] In some embodiments, the positive terminal of battery 101 is further connected to a main positive relay K11, and the negative terminal of battery 101 is further connected to a main negative relay K12. A first connection point A1 can be connected to the positive terminal of battery 101 via the main positive relay K11, and a second connection point A2 can be connected to the negative terminal of battery 101 via the main negative relay K12. In response to a temperature of battery 101 exceeding a first temperature threshold but falling below a target temperature, the main positive relay K11 and the main negative relay K12 are closed, allowing the first connection point A1 to be connected to the positive terminal of battery 101 and the second connection point A2 to be connected to the negative terminal of battery 101.

[0154] like Figure 11 As shown, in some embodiments, the first switching circuit may not be provided. Instead, in response to the battery temperature being less than or equal to a first temperature threshold, all switching elements of the switching branch 103 may be controlled to alternately turn on and off simultaneously, thereby achieving heating of the battery based on a pulse modulation signal.

[0155] In other words, when the battery temperature is higher than the first temperature threshold, the battery pack can be alternately charged and discharged through the switching branch 103 and the energy storage circuit 104. When the battery temperature is less than or equal to the first temperature threshold, the battery can be heated based on a PWM signal through the switching branch 103. Controlling all switching elements of the switching branch 103 to alternately turn on and off simultaneously means that all switching elements in the switching branch 103 operate in unison. When the switching elements turn on simultaneously, the entire switching branch 103 is turned on, that is, the first connection point A1 and the second connection point A2 are connected; when the switching elements turn off simultaneously, the entire switching branch 103 is turned off, that is, the first connection point A1, the second connection point A2, and the third connection point A3 are all turned off. By controlling the switching elements to alternately turn on and off, the switching branch is alternately turned on and off.

[0156] Understandably, without the first switching circuit, since switch branch 103 is connected to the positive and negative terminals of the battery, when switch branch 103 is on, the positive and negative terminals of the battery are short-circuited, resulting in current flowing through the battery. When switch branch 103 is off, the positive and negative terminals of the battery are disconnected, and no current flows through the battery. By controlling switch branch 103 to alternately turn on and off, the positive and negative terminals of the battery are alternately short-circuited and disconnected, thus periodically allowing current to flow through the battery. By controlling the frequency and on / off time of the alternating short-circuiting and disconnection of the positive and negative terminals of the battery, it is equivalent to inputting a PWM signal with a certain frequency and duty cycle into the battery.

[0157] When there are multiple switch branches, all of them are either turned on or turned off simultaneously.

[0158] In the above technical solution, by establishing the correlation between the impedance and temperature of battery 101 at its current state of charge and current excitation signal frequency, the current impedance of battery 101 can be predicted based on the second mapping relationship by determining the temperature of battery 101. This eliminates the need for impedance detection of battery 101, improving the response rate. Furthermore, by determining the impedance of battery 101 and adjusting the current, the real-time heating power of battery 101 can be controlled, ensuring that the heating power of battery 101 is not too low.

[0159] According to some embodiments of this application, the battery 101 heating method 400 further includes: Obtain the current open-circuit voltage of battery 101; Based on the current temperature of battery 101, the current open-circuit voltage, and the second mapping relationship, a current threshold for adjusting the current of alternating charging and discharging of the battery pack is determined.

[0160] In some embodiments, the current SOC corresponding to the current open-circuit voltage of battery 101 can be determined based on the SOC-OCV curve of battery 101 at the time of manufacture.

[0161] The second mapping relationship is used to characterize the change in impedance of battery 101 with temperature under the current state of charge and the current alternating charge and discharge frequency. The corresponding second mapping relationship can be determined based on the current state of charge (SOC) of battery 101 and the alternating charge and discharge frequency. Given the current temperature of battery 101, the corresponding impedance of battery 101 can be obtained based on the second mapping relationship, and then the current threshold can be determined according to the following formula (5).

[0162] (5) Among them, I max It is the current threshold, U ocvR is the current open-circuit voltage of battery 101, and R is the current impedance value of battery 101.

[0163] like Figure 3 as well as Figure 10 As shown, in some embodiments, when the current flowing through the battery 101 exceeds the current threshold, the main positive relay K11 and / or the main negative relay K12 can be controlled to disconnect. This disconnects the second heating circuit from the battery 101, thereby stopping the heating of the battery 101. Alternatively, other active circuit breaking devices, such as active fuses or MSDs (Manual Service Disconnects), can be disconnected. By disconnecting the MSD, the high-voltage circuit can be quickly cut off, electrical isolation can be achieved, personnel safety can be ensured, and short-circuit protection can be provided.

[0164] In some embodiments, a current sensor 30 is also connected between the positive terminal of the battery and the main positive relay K11. The current sensor 30 is used to detect the current flowing through the battery. The current sensor can send the battery current data to the BMS. In response to the battery current exceeding the current threshold, the BMS controls the high-voltage circuit to disconnect.

[0165] In the above technical solution, by determining the current threshold for alternating charging and discharging of battery 101, the voltage across battery 101 will not exceed the protection voltage during alternating charging and discharging, which is beneficial to improving the heating stability of battery 101.

[0166] refer to Figure 12 According to some embodiments of this application, step 420 further includes: Step 4203: Obtain the third mapping relationship, which is used to characterize the change of impedance of battery 101 with excitation signal frequency under the current state of charge and current temperature. Step 4204: Based on the third mapping relationship, adjust the frequency of alternating charging and discharging of the battery pack.

[0167] In step 4203, the battery pack is controlled to alternately charge and discharge, so that the current flowing through battery 101 is a pulse current. This pulse current is the excitation signal input to battery 101. Therefore, the frequency of the alternating charge and discharge of the battery pack is also the frequency of the excitation signal, meaning that the frequency of the alternating charge and discharge of the battery pack conforms to the impedance characteristics of battery 101. With a constant SOC and temperature of battery 101, the impedance of battery 101 is related to the frequency of alternating charge and discharge, thus allowing the determination of the third mapping relationship. Since the relationship between the impedance of battery 101 and the excitation signal frequency is affected by the battery SOC and temperature, the third mapping relationship of battery 101 at different SOCs and temperatures can be obtained. By obtaining the current SOC and current temperature of battery 101, the corresponding third mapping relationship can be determined.

[0168] As the temperature of battery 101 increases, the impedance of battery 101 decreases accordingly. As can be seen from the aforementioned formula (4), if the impedance of the battery pack during alternating charging and discharging decreases when the current remains constant, the actual heating of battery 101 will decrease, resulting in insufficient heat generation power of battery 101.

[0169] To avoid insufficient heat generation in battery 101 to some extent, the frequency of alternating charging and discharging of the battery pack can be adjusted to adjust the impedance of battery 101, thereby increasing the actual heating power of battery 101.

[0170] Therefore, the corresponding third mapping relationship can be determined based on the current SOC and current temperature of battery 101. Based on the third mapping relationship, the relationship between the impedance of battery 101 and the alternating charging and discharging frequency of the battery pack can be determined. In this way, by adjusting the alternating charging and discharging frequency of the battery pack, battery 101 can reach the corresponding impedance, thereby enabling the actual heating power of battery 101 to reach the preset heating power or its vicinity.

[0171] In some embodiments, the frequency of alternating charge and discharge of the battery pack can be adjusted in segments based on temperature feedback. For example, the frequency of alternating charge and discharge of the battery pack can be adjusted once in response to a preset temperature range increase in the temperature of battery 101. The preset temperature range can be 1°C, 5°C, or 10°C, etc. During the period when the temperature increase of battery 101 compared to the previous frequency adjustment does not reach the preset temperature range, the frequency of alternating charge and discharge of the battery pack can be left unchanged, and only the current of alternating charge and discharge can be adjusted. That is, during the period when the temperature increase of battery 101 compared to the previous frequency adjustment does not reach the preset temperature range, the frequency of alternating charge and discharge of the battery pack is fixed. Therefore, a second mapping relationship can be determined based on the current SOC of battery 101 and the current alternating charge and discharge frequency, facilitating current adjustment based on temperature and the second mapping relationship.

[0172] In some embodiments, such as Figure 5As shown, with a fixed current SOC of battery 101, as the temperature of battery 101 increases, the impact of changes in the excitation signal frequency on the impedance of battery 101 becomes less significant. That is, the higher the temperature of battery 101, the smoother the frequency response characteristics of its impedance. At this point, even adjusting the frequency may not affect the impedance of battery 101. Therefore, when the temperature of battery 101 reaches the third temperature threshold, the frequency of alternating charge and discharge of battery 101 can be adjusted without adjusting the frequency of alternating charge and discharge; only the current of alternating charge and discharge can be adjusted. The third temperature threshold is greater than the first temperature threshold but less than the target temperature. The third temperature threshold can be determined based on the degree of response of the battery 101's impedance to the excitation signal frequency. When the temperature of battery 101 reaches the third temperature threshold, the frequency response characteristics of the battery 101's impedance tend to be smooth.

[0173] In some embodiments, the second heating circuit includes a switching branch 103 and an energy storage circuit 104. The frequency of alternating charging and discharging of the battery pack can be adjusted by controlling the conduction frequency of the switching transistor in the switching branch 103.

[0174] In the above technical solution, by establishing the correlation between the impedance of the battery 101 at the current state of charge and the current temperature and the frequency of the excitation signal, and adjusting the frequency of alternating charging and discharging of the battery pack based on the correlation, the battery 101 can reach the corresponding impedance, thereby enabling the real-time heating power of the battery 101 to be controlled so that the heating power of the battery 101 is not too low.

[0175] It is understood that, in some other embodiments, during the entire process of controlling the alternating charging and discharging of the battery pack to heat the battery 101, only the current of the alternating charging and discharging of the battery pack may be adjusted, without adjusting the frequency of the alternating charging and discharging. This is because, as Figure 5 As shown, as the temperature of battery 101 increases, the impedance of battery 101 is less affected by the frequency of the excitation signal. Even if the frequency is adjusted, it may not affect the impedance of battery 101. Therefore, the frequency of alternating charging and discharging of the battery pack can be adjusted, but only the current can be adjusted, which simplifies the control logic.

[0176] According to some embodiments of this application, the battery 101 heating method 400 further includes: Obtain the temperature rise rate of battery 101; In response to the temperature rise rate of battery 101 being greater than or equal to a first threshold, heating of battery 101 is stopped.

[0177] In some embodiments, the temperature rise rate of the battery 101 can be acquired in real time during the execution of steps 410 and 420, and the execution of step 410 or step 420 can be stopped in response to the temperature rise rate of the battery 101 being greater than or equal to a first threshold.

[0178] For example, during step 410, the temperature rise rate of battery 101 is acquired in real time. If the temperature rise rate of battery 101 is less than a first threshold and the temperature of battery 101 is less than or equal to the first temperature threshold, battery 101 is heated based on a PWM signal. If the temperature rise rate of battery 101 is detected to be greater than or equal to the first threshold, heating battery 101 based on the PWM signal is stopped. For example, if a first switching element 1021 and a fuse element 1022 are connected between the positive and negative terminals of battery 101, the fuse element 1022 can be controlled to open to stop heating battery 101 based on the PWM signal.

[0179] like Figure 3 as well as Figure 10 As shown, when the temperature of battery 101 is detected to be higher than the first temperature threshold, the first switching element 1021 can be controlled to open, and step 420 can be executed. During step 420, the main positive relay K11 and the main negative relay K12 are closed, and the battery pack is alternately charged and discharged by controlling the second heating circuit. During step 420, the temperature rise rate of battery 101 is acquired in real time. If the temperature rise rate of battery 101 is less than the first threshold and the temperature of battery 101 is less than the target temperature, the battery pack is alternately charged and discharged by controlling the second heating circuit. If the temperature rise rate of battery 101 is detected to be greater than or equal to the first threshold, the operation of controlling the second heating circuit to alternately charge and discharge the battery pack is stopped. For example, the second heating circuit can be disconnected from battery 101 by opening the main positive relay K11 and / or the main negative relay K12, or the MSD can be disconnected. When the temperature of battery 101 is detected to have reached the target temperature, the connection between the switching branch 103 in the second heating circuit and battery 101 can be disconnected, thereby stopping the heating of battery 101.

[0180] In some embodiments, if the temperature rise rate of battery 101 is detected to be greater than a first threshold, the battery 101 can also be cooled using the current thermal field equalization strategy. For example, the battery 101 can be cooled using a thermal management module, a water cooling module, etc.

[0181] In some embodiments, the first threshold may be 30℃ / min, 35℃ / min, or 40℃ / min, etc.

[0182] In the above technical solution, in response to the temperature rise rate of battery 101 being greater than or equal to the first threshold, heating of battery 101 is stopped, which can avoid to some extent the problem of uneven temperature distribution inside battery 101 caused by excessively fast temperature rise rate of battery 101.

[0183] According to some embodiments of this application, obtaining the temperature rise rate of battery 101 may include: A temperature rise model for battery 101 is established. The temperature rise model is used to characterize the rate of change of the temperature rise function of battery 101 with temperature. Based on the temperature rise model of battery 101 and the current temperature, the temperature rise rate of battery 101 is determined.

[0184] In some embodiments, a basic model for the rate of temperature rise can be established based on the heat conservation equation, as shown below:

[0185] Where c is the specific heat capacity of battery 101, and m is the mass of battery 101. Q represents the rate of temperature rise of battery 101. 产 Q is the heat generation power of battery 101. 散 This refers to the heat dissipation power of battery 101.

[0186] The heat generation power of battery 101, which is also the actual heating power of battery 101, can be derived as follows:

[0187] Where I is the current flowing through battery 101, and R is the current impedance of battery 101.

[0188] Based on the heat dissipation power of battery 101 through thermal conduction, we can conclude that:

[0189] Where k is the thermal conductivity, A is the thermally conductive area of ​​battery 101, L is the thermally conductive path length of battery 101, T is the current temperature of battery 101, and T0 is the initial heating temperature of battery 101.

[0190] Combining the above formulas, the following temperature rise model can be established:

[0191] Given a fixed current state of charge (SOC) and excitation frequency of battery 101, a second mapping relationship exists between the impedance of battery 101 and its temperature. Based on this, R in the above temperature rise model can be represented by the second mapping relationship. That is, the change in temperature rise rate with impedance is transformed into the change in temperature rise rate with the temperature of battery 101. Thus, the temperature rise rate of battery 101 can be determined based on the temperature rise model of battery 101 and its current temperature.

[0192] In the above technical solution, the temperature rise rate can be predicted by a temperature rise model, eliminating the need for actual detection and improving the response rate.

[0193] In other embodiments, the temperature of battery 101 can be actually detected to obtain the temperature rise rate of battery 101, making the obtained temperature rise rate result more accurate.

[0194] According to some embodiments of this application, obtaining the temperature rise rate of battery 101 may further include: Obtain the temperature difference between the current temperature and the initial heating temperature of battery 101; Obtain the heating time of battery 101; The actual temperature rise rate of battery 101 is determined based on the ratio of the temperature difference between the current temperature and the initial heating temperature of battery 101 and the heating time of battery 101. If the temperature rise rate of battery 101 determined by the temperature rise model based on battery 101 and the current temperature is inconsistent with the actual temperature rise rate, the actual temperature rise rate shall be determined as the temperature rise rate of battery 101.

[0195] In some embodiments, the BMS can detect the actual temperature of the first side of the battery cell 101 in the battery 101 to determine the current temperature and initial heating temperature of the battery 101, and then obtain the temperature difference between the current temperature and the initial heating temperature of the battery 101.

[0196] In some embodiments, the heating time of battery 101 is recorded in the BMS, so the heating time of battery 101 can be obtained through the BMS.

[0197] It is understandable that since the temperature rise model predicts the temperature rise rate of battery 101 based on the current temperature of battery 101, the predicted value may have a certain error with the actual value. Therefore, if the temperature rise rate of battery 101 determined by the temperature rise model based on battery 101 and the current temperature is inconsistent with the actual temperature rise rate, the actual temperature rise rate shall be determined as the temperature rise rate of battery 101.

[0198] In the above technical solution, the temperature of battery 101 is also actually detected to obtain the actual temperature rise rate of battery 101, thereby improving the accuracy of detection and effectively avoiding the problem of excessively rapid temperature rise rate of battery 101.

[0199] This application provides a battery device, including: a battery, a first heating circuit, a second heating circuit, and a controller. The battery includes at least one battery pack. The first heating circuit is connected to the positive and negative terminals of the battery. The second heating circuit is connected to the positive and negative terminals of the battery. The controller is configured to: in response to the battery temperature being less than or equal to a first temperature threshold, control the first heating circuit to alternately short-circuit and disconnect the positive and negative terminals of the battery based on a pulse width modulation signal to heat the battery; and in response to the battery temperature being greater than the first temperature threshold, control the second heating circuit to alternately charge and discharge the battery pack in the battery 101 until the battery temperature reaches a target temperature, where the first temperature threshold is less than the target temperature.

[0200] In some embodiments, the controller may be a controller in a BMS.

[0201] The controller can execute steps 410 and 420 in the above embodiments. The execution method can be referred to the relevant description in the above embodiments, and will not be repeated here.

[0202] In the above technical solution, heating the battery via pulse width modulation (PWM) signals eliminates the need for battery discharge. This addresses the problem of insufficient heating power and inability to sustain temperature rise at low temperatures due to severe discharge polarization. Furthermore, by controlling the duty cycle of the PWM signal, the battery obtains a stable equivalent average current, enabling continuous heating at low temperatures and improving heating stability. When the temperature exceeds a first temperature threshold, the battery's internal resistance decreases rapidly. Periodic current commutation limits the continuous increase in current, preventing a sharp rise in current due to a sudden drop in internal resistance, which could lead to excessive heat generation and ensure stable battery heating.

[0203] refer to Figure 3 as well as Figure 10 According to some embodiments of this application, the first heating circuit includes: a first switching circuit 102, the first switching circuit 102 being connected to the positive and negative terminals of the battery 101; the controller is configured to: in response to the temperature of the battery 101 being less than or equal to a first temperature threshold, control the first switching circuit 102 to alternately turn on and off to input a pulse width modulation signal to the battery 101.

[0204] The structure of the first switching circuit 102 and its connection with the battery 101 can be found in the descriptions in the above embodiments, and will not be repeated here.

[0205] The manner in which the controller performs the step of controlling the first switching circuit 102 to alternately turn on and off in response to the temperature of the battery 101 being less than or equal to a first temperature threshold, so as to input a pulse width modulation signal to the battery 101, can be referred to the relevant description in the above embodiments, and will not be repeated here.

[0206] In the above technical solution, by controlling the first switching circuit 102 to alternately turn on and off, the positive and negative terminals of the battery 101 are alternately short-circuited and disconnected. When the positive and negative terminals of the battery 101 are short-circuited, the battery 101 generates a large instantaneous current, triggering high-power heat generation. This allows the battery 101 to generate heat rapidly at low temperatures, further improving the problem that the severe discharge polarization effect of the battery 101 at low temperatures leads to insufficient heating power and inability to sustain temperature rise. When the positive and negative terminals of the battery 101 are disconnected, no current flows through the battery 101. Thus, by controlling the alternating short-circuiting and disconnection of the positive and negative terminals of the battery 101, the periodic changes in the current flowing through the battery 101 are generated, thereby forming a PWM signal.

[0207] According to some embodiments of this application, the controller is also configured to: acquire a preset heating power required to heat the battery 101; and determine the frequency of the pulse width modulation signal based on the preset heating power and the impedance characteristics of the battery 101 at different temperatures and under different states of charge.

[0208] That is, the controller can execute steps 4101 and 4102 in the above embodiments. The execution method can be referred to the relevant description in the above embodiments, and will not be repeated here.

[0209] In the above technical solution, the impedance characteristics of battery 101 can be used to characterize the change of battery 101 impedance with frequency. By selecting the optimal frequency based on the preset heating power, the impedance of battery 101 can be adjusted, so that the average heating power of battery 101 can be maintained at or near the preset heating power. This is beneficial to the overall heating rate of battery 101 being relatively stable, and to a certain extent avoids the risk of uneven internal temperature distribution and sharp increase in local temperature caused by the excessively fast heating rate of battery 101.

[0210] According to some embodiments of this application, the controller is further configured to: acquire the initial open-circuit voltage of the battery 101 at the initial heating temperature; and determine the initial impedance of the battery 101 at the initial heating temperature and the initial frequency corresponding to the initial impedance based on the initial open-circuit voltage, the preset heating power, and the impedance characteristics of the battery 101, wherein the initial frequency is used as the frequency of the pulse width modulation signal.

[0211] The method by which the controller performs this step can be referred to the relevant description in the above embodiments, and will not be repeated here.

[0212] In the above technical solution, the actual heating power of battery 101 is related to the voltage across battery 101 and the impedance of battery 101. At the initial heating moment of battery 101, the impedance required for the initial heating moment of battery 101 can be deduced based on the initial open-circuit voltage and the initial preset heating power. The impedance characteristics of battery 101 can characterize the relationship between impedance and frequency. Therefore, the optimal frequency of the PWM signal input to battery 101 at the initial heating moment can be determined based on the obtained impedance, so that battery 101 can heat at the preset heating power at the initial heating moment. In this way, during the subsequent heating process, the duty cycle of the PWM signal can be adjusted based on the heating power at the initial heating moment, so that the average heating power of battery 101 is stabilized at or near the preset heating power.

[0213] According to some embodiments of this application, the controller is further configured to: acquire a preset heating power required to heat the battery 101; acquire the current actual heating power of the battery 101; and determine the duty cycle of the pulse width modulation signal based on the ratio of the preset heating power to the current actual heating power of the battery 101.

[0214] That is, the controller can execute steps 4103 to 4105 in the above embodiments. The execution method can be referred to the relevant description in the above embodiments, and will not be repeated here.

[0215] In the above technical solution, the average power within one cycle is obtained by multiplying the actual heating power by the duty cycle. The ratio of the preset heating power to the current actual heating power is determined as the duty cycle of the PWM signal, which can adjust the duty cycle in real time so that the average heating power of the battery 101 is stabilized at or near the preset heating power, thereby improving the heating stability of the battery 101.

[0216] According to some embodiments of this application, the controller is further configured to: obtain a first mapping relationship, the first mapping relationship being used to characterize the change of the actual heating power of the battery 101 corresponding to different excitation signal frequencies with the temperature of the battery 101 under the current state of charge; and determine the current actual heating power of the battery 101 based on the frequency of the pulse width modulation signal, the current temperature of the battery 101, and the first mapping relationship.

[0217] The method by which the controller performs this step can be referred to the relevant description in the above embodiments, and will not be repeated here.

[0218] In the above technical solution, by establishing the correlation between the actual heating power of the battery 101 under the current state of charge and the current excitation signal frequency and the temperature of the battery 101, the current actual heating power can be found from the first mapping relationship by determining the current temperature of the battery 101, thus eliminating the complex calculation process and improving the response speed.

[0219] According to some embodiments of this application, the controller is also configured to: in response to the temperature of the battery 101 being greater than or equal to a second temperature threshold and less than or equal to a first temperature threshold, control the first heating circuit to heat the battery 101 based on a pulse width modulation signal, wherein the second temperature threshold is less than the first temperature threshold.

[0220] The method by which the controller performs this step can be referred to the relevant description in the above embodiments, and will not be repeated here.

[0221] In the above technical solution, the heating efficiency of the battery 101 may be too low when the temperature of the battery 101 is less than the second temperature threshold. Therefore, the battery 101 is heated based on the PWM signal only when the temperature of the battery 101 is greater than or equal to the second temperature threshold and less than or equal to the first temperature threshold, which is beneficial to improving the overall heating efficiency of the battery 101.

[0222] According to some embodiments of this application, the second heating circuit includes: a switching branch and an energy storage circuit, wherein the switching circuit is connected to the positive and negative terminals of the battery; the energy storage circuit is connected to the battery and the switching branch; and the controller is configured to: in response to the battery temperature being greater than a first temperature threshold, control the switching branch to cause the battery and the energy storage circuit to discharge to each other.

[0223] An energy storage circuit is a circuit capable of storing electrical energy. By controlling the switching branch, the battery can discharge into the energy storage circuit; in this process, the battery discharges and the energy storage circuit charges. By controlling the switching circuit, the electrical energy stored in the energy storage circuit can also be released into the battery; in this process, the battery charges and the energy storage circuit discharges. Thus, alternating charging and discharging of the battery can be achieved.

[0224] The mutual discharge between the battery and the energy storage circuit referred to here can be either each battery pack in the battery simultaneously discharging into the energy storage circuit, or the energy storage circuit simultaneously discharging into each battery pack in the battery.

[0225] In the above technical solution, the energy storage circuit and the switching circuit can realize the alternating charging and discharging of the battery, thereby enabling pulse heating of the battery.

[0226] refer to Figure 3 According to some embodiments of this application, the number of switch branches 103 and energy storage circuits 104 is at least two. The switch branch 103 includes a first connection point A1, a second connection point A2 and a third connection point A3 that are interconnected by a switch element. The first connection point A1 is connected to the positive terminal of the battery 101 and the second connection point A2 is connected to the negative terminal of the battery 101. The first terminal of the energy storage circuit 104 is connected to the third connection point A3, and the second terminals of each energy storage circuit 104 are connected to each other.

[0227] At least two switching branches 103 are connected to at least two energy storage circuits 104 in a one-to-one correspondence. By controlling the switching branches 103, the battery 101 and the energy storage circuit 104 are able to discharge to each other.

[0228] The structure of the switch branch 103 and the energy storage circuit 104, as well as the method for controlling the switch branch 103 to make the battery 101 and the energy storage circuit 104 discharge to each other, can be referred to the relevant description in the above embodiments, and will not be repeated here.

[0229] In the above technical solution, the switching branch 103 can alternately discharge the battery 101 to the energy storage circuit 104 and discharge the energy storage circuit 104 to the battery 101. When the battery 101 discharges to the energy storage circuit 104, the battery 101 discharges; when the energy storage circuit 104 discharges to the battery 101, the battery 101 is charged. In this way, the alternating charging and discharging of the battery 101 can be achieved.

[0230] According to some embodiments of this application, the battery includes two battery packs connected in series, and the controller is configured to control the two battery packs to discharge to each other via a second heating circuit in response to the battery temperature being greater than a first temperature threshold.

[0231] The two battery packs are the first battery pack and the second battery pack. The mutual discharge between the two battery packs means that the first battery pack discharges to the second battery pack, and the second battery pack discharges to the first battery pack. In this way, the alternating charging and discharging of each battery pack can be achieved.

[0232] In some embodiments, the second heating circuit can be connected to the midpoint between the two battery packs, thereby enabling it to establish a path with each battery pack. For example, if the two battery packs are a first battery pack and a second battery pack, the controller can control the second heating circuit to first establish a path with the first battery pack, allowing the first battery pack to discharge to the second heating circuit, which can store electrical energy. Then, the controller can control the second heating circuit to establish a path with the second battery pack, allowing the second heating circuit to release electrical energy to the first battery pack, thus enabling the first battery pack to discharge to the second battery pack. Similarly, if the controller first controls the second heating circuit to establish a path with the first battery pack, and then controls the second heating circuit to establish a path with the second battery pack, then the second battery pack can discharge to the first battery pack.

[0233] In other embodiments, the second heating circuit can also create a discharge path between the two battery packs, so that one battery pack can directly discharge to the other battery pack through the second heating circuit, thereby realizing mutual discharge between the two battery packs.

[0234] In the above technical solution, the two battery packs are mutually discharged through the second heating circuit, thereby enabling alternating charging and discharging of each battery pack and achieving pulse heating of each battery pack. Furthermore, during the mutual discharge process between the two battery packs, energy exchange occurs, which helps maintain the energy balance of the two battery packs.

[0235] According to some embodiments of this application, the second heating circuit includes: a switching branch and an energy storage circuit, wherein the switching branch is connected to the positive and negative terminals of the battery; the energy storage circuit is connected to the switching branch and the midpoint between the two battery packs; and the controller is configured to: in response to the battery temperature being greater than a first temperature threshold, control the two battery packs to discharge to each other through the switching branch and the energy storage circuit.

[0236] The energy storage circuit connects the switching branch to the midpoint between the two battery packs, thus enabling it to establish a path with each battery pack. For example, if the two battery packs are a first battery pack and a second battery pack, the controller can control the switching branch to first establish a path with the first battery pack and the energy storage circuit, allowing the first battery pack to discharge into the energy storage circuit, which stores electrical energy. Next, the controller can control the switching branch to establish a path with the second battery pack and the energy storage circuit, allowing the energy storage circuit to release electrical energy into the first battery pack, thus enabling the first battery pack to discharge into the second battery pack. Similarly, if the controller first controls the switching branch to establish a path with the first battery pack and the energy storage circuit, and then controls the switching branch to establish a path with the second battery pack and the energy storage circuit, then the second battery pack can discharge into the first battery pack.

[0237] In the above technical solution, the mutual discharge of the two battery packs can be achieved by using the switch branch and the energy storage circuit, and the structure is simple and reliable.

[0238] refer to Figure 10 According to some embodiments of this application, the switch branch 103 includes a first connection point A1, a second connection point A2, and a third connection point A3 interconnected by a switch element. The first connection point A1 is connected to the positive terminal of the battery 101, and the second connection point A2 is connected to the negative terminal of the battery 101. The first terminal of the energy storage circuit 104 is connected to the third connection point A3. The second heating circuit also includes a neutral line 105, the first terminal of which is connected to the second terminal of the energy storage circuit 104, and the second terminal of which is connected to the midpoint between the two battery packs.

[0239] The switch branch 103 is connected to the energy storage circuit 104 in a one-to-one correspondence. The two battery packs are controlled to discharge to each other through the switch branch 103, the energy storage circuit 104 and the neutral line 105. There can be multiple switch branches and multiple energy storage circuits, and they are set up in a one-to-one correspondence.

[0240] The structure of the interconnection between the switch branch 103, the energy storage circuit 104 and the neutral line 105, as well as the method of controlling the switch branch 103, the energy storage circuit 104 and the neutral line 105 to enable the two battery packs to discharge to each other, can be referred to the relevant description in the above embodiments, and will not be repeated here.

[0241] In the above technical solution, the two battery packs can discharge to each other through the switch branch 103, the energy storage circuit 104 and the neutral line 105, thereby enabling the alternating charging and discharging of each battery pack.

[0242] According to some embodiments of this application, the controller is also configured to: in response to the battery temperature being less than or equal to a first temperature threshold, control all switching elements of the switching branch to alternately and simultaneously turn on and off, so as to heat the battery based on a pulse width modulation signal.

[0243] In other words, when the battery temperature is above the first temperature threshold, the battery pack can be alternately charged and discharged through the switching branch and the energy storage circuit. When the battery temperature is below or equal to the first temperature threshold, the battery can be heated based on a PWM signal through the switching branch.

[0244] The alternating simultaneous opening and closing of all switching elements in a control branch means that all switching elements in the branch operate in unison. When the switching elements open simultaneously, the entire branch is connected, meaning the first connection point and the second connection point are connected. When the switching elements close simultaneously, the entire branch is disconnected, meaning the first, second, and third connection points are all disconnected. By controlling the alternating opening and closing of the switching elements, the branch is alternately connected and disconnected.

[0245] like Figure 11 As shown, it can be understood that without the first switching circuit, since the switching branch 103 is connected to the positive and negative terminals of the battery, when the switching branch 103 is on, the positive and negative terminals of the battery are short-circuited, and current flows through the battery. When the switching branch 103 is off, the positive and negative terminals of the battery are disconnected, and no current flows through the battery. By controlling the switching branch 103 to alternately turn on and off, the positive and negative terminals of the battery are alternately short-circuited and disconnected. In this way, current flows through the battery periodically. By controlling the frequency and on / off time of the alternating short-circuiting and disconnection of the positive and negative terminals of the battery, it is equivalent to inputting a PWM signal with a certain frequency and duty cycle into the battery.

[0246] When there are multiple switch branches 103, all multiple switch branches 103 are simultaneously turned on or simultaneously turned off.

[0247] In the above technical solution, by setting a switch branch connected to the positive and negative terminals of the battery, the switch branch can not only be used to form the second heating circuit, but also act as the first heating circuit. This simplifies the circuit topology and reduces hardware costs.

[0248] According to some embodiments of this application, the controller is further configured to: obtain a second mapping relationship, the second mapping relationship being used to characterize the change of impedance of battery 101 corresponding to different excitation signal frequencies with the temperature of battery 101 under the current state of charge; and adjust the current of alternating charging and discharging of battery pack based on the current temperature of battery 101, the current alternating charging and discharging frequency of battery 101 and the second mapping relationship.

[0249] That is, the controller can execute steps 4201 and 4202 in the above embodiments. The execution method can be referred to the relevant description in the above embodiments, and will not be repeated here.

[0250] In the above technical solution, by establishing the correlation between the impedance and temperature of battery 101 at its current state of charge and current excitation signal frequency, the current impedance of battery 101 can be predicted based on the second mapping relationship by determining the temperature of battery 101. This eliminates the need for impedance detection of battery 101, improving the response rate. Furthermore, by determining the impedance of battery 101 and adjusting the current, the real-time heating power of battery 101 can be controlled, ensuring that the heating power of battery 101 is not too low.

[0251] According to some embodiments of this application, the controller is also configured to: acquire the current open-circuit voltage of the battery 101; and determine a current threshold for adjusting the current of alternating charging and discharging of the battery pack based on the current temperature of the battery 101, the current open-circuit voltage, and a second mapping relationship.

[0252] The method by which the controller performs this step can be referred to the relevant description in the above embodiments, and will not be repeated here.

[0253] In the above technical solution, by determining the current threshold for alternating charging and discharging of battery 101, the voltage across battery 101 will not exceed the protection voltage during alternating charging and discharging, which is beneficial to improving the heating stability of battery 101.

[0254] According to some embodiments of this application, the controller is further configured to: obtain a third mapping relationship, which is used to characterize the change of impedance of battery 101 at different temperatures with the frequency of excitation signal under the current state of charge; and adjust the frequency of alternating charging and discharging of battery pack based on the current temperature of battery 101, current state of charge and the third mapping relationship.

[0255] That is, the controller can execute steps 4203 and 4204 in the above embodiments. The execution method can be referred to the relevant description in the above embodiments, and will not be repeated here.

[0256] In the above technical solution, by establishing the correlation between the impedance of the battery 101 at the current state of charge and the current temperature and the frequency of the excitation signal, and adjusting the frequency of alternating charging and discharging of the battery pack based on the correlation, the battery 101 can reach the corresponding impedance, thereby enabling the real-time heating power of the battery 101 to be controlled so that the heating power of the battery 101 is not too low.

[0257] According to some embodiments of this application, the controller is further configured to: acquire the temperature rise rate of the battery 101; in response to the temperature rise rate of the battery 101 being greater than or equal to a first threshold, control the first heating circuit to stop heating the battery 101 based on the pulse width modulation signal, and control the second heating circuit to stop alternating charging and discharging of the battery pack in the battery 101.

[0258] The method by which the controller performs this step can be referred to the relevant description in the above embodiments, and will not be repeated here.

[0259] In the above technical solution, in response to the temperature rise rate of battery 101 being greater than or equal to the first threshold, heating of battery 101 is stopped, which can avoid to some extent the problem of uneven temperature distribution inside battery 101 caused by excessively fast temperature rise rate of battery 101.

[0260] This application provides a battery management system for managing a battery, the battery including at least one battery pack. The battery management system is configured to: in response to the battery temperature being less than or equal to a first temperature threshold, control the positive and negative terminals of the battery to alternately short-circuit and disconnect based on a pulse width modulation signal to heat the battery; and in response to the battery temperature being greater than the first temperature threshold, control the battery pack to alternately charge and discharge until the battery temperature reaches a target temperature, where the first temperature threshold is less than the target temperature.

[0261] The battery management system can be signal-connected to a first heating circuit and a second heating circuit, thereby enabling it to control the first heating circuit to heat the battery based on a pulse-modulated signal in response to the battery temperature being less than or equal to a first temperature threshold; and to control the second heating circuit to alternately charge and discharge the battery pack in the battery in response to the battery temperature being greater than the first temperature threshold, until the battery temperature reaches the target temperature. This control method can be referred to the relevant description in the above embodiments, and will not be repeated here.

[0262] This application provides an electrical device, which includes the battery device described in the above embodiments, and the battery device is used to provide electrical energy.

[0263] The battery device and the power supply device can be referred to the relevant descriptions in the above embodiments, and will not be repeated here.

[0264] The technical solution of this application will be further described below with reference to a specific embodiment.

[0265] refer to Figure 2 as well as Figure 10 The battery device includes a battery 101, a first heating circuit, a second heating circuit, and a controller. The battery 101 includes at least one battery pack. The first heating circuit is connected to the positive and negative terminals of the battery 101. The second heating circuit is also connected to the positive and negative terminals of the battery 101. The controller is configured to: in response to the temperature of the battery 101 being less than or equal to a first temperature threshold, control the first heating circuit to heat the battery 101 based on a pulse width modulation signal; and in response to the temperature of the battery 101 being greater than the first temperature threshold, control the second heating circuit to alternately charge and discharge the battery pack in the battery 101 until the temperature of the battery 101 reaches a target temperature, where the first temperature threshold is less than the target temperature.

[0266] The first heating circuit includes a first switching circuit 102, which includes a first switching element 1021 and a fuse element 1022 connected in series. The first switching element 1021 is used to control the on / off state of the positive and negative terminals of the battery 101, and the fuse element 1022 is configured to disconnect the first switching circuit 102 when the current of the battery 101 is too high.

[0267] For example, refer to Figure 3 The second heating circuit may include at least three switching branches 103 and three energy storage circuits 104. The switching branches 103 include a first connection point A1, a second connection point A2 and a third connection point A3 that are interconnected by switching elements. The first connection point A1 is connected to the positive terminal of the battery 101 and the second connection point A2 is connected to the negative terminal of the battery 101. The switching branches 103 and the energy storage circuits 104 are connected in a one-to-one correspondence. The first end of the energy storage circuit 104 is connected to the third connection point A3, and the second ends of each energy storage circuit 104 are connected to each other.

[0268] For example, refer to Figure 10The battery 101 includes two battery packs. The second heating circuit may also include: a switch branch 103, an energy storage circuit 104, and a neutral line 105. The switch branch 103 includes a first connection point A1, a second connection point A2, and a third connection point A3 interconnected by a switching element. The first connection point A1 is connected to the positive terminal of the battery 101, and the second connection point A2 is connected to the negative terminal of the battery 101. The first end of the energy storage circuit 104 is connected to the third connection point A3. The first end of the neutral line 105 is connected to the second end of the energy storage circuit 104, and the second end of the neutral line 105 is connected to the midpoint between the two battery packs. The switch branch 103 and the energy storage circuit 104 are connected in a one-to-one correspondence, and the number of both the switch branch 103 and the energy storage circuit 104 can be three.

[0269] The positive terminal of battery 101 is also connected to a main positive relay K11, and the negative terminal of battery 101 is also connected to a main negative relay K12. The first connection point A1 can be connected to the positive terminal of battery 101 through the main positive relay K11, and the second connection point A2 can be connected to the negative terminal of battery 101 through the main negative relay K12.

[0270] refer to Figure 13 The heating method for battery 101 includes the following steps 501 to 515.

[0271] Step 501: Start the BMS and set the second temperature threshold. The battery 101 will only be heated if the detected temperature of the battery 101 is greater than or equal to the second temperature threshold; the battery 101 will not be heated if the temperature of the battery 101 is less than the second temperature threshold.

[0272] Step 502: Based on the preset heating power and the impedance characteristics of battery 101 at different temperatures and under different states of charge, determine the frequency and duty cycle of the pulse width modulation signal. The method for determining the frequency and duty cycle of the pulse width modulation signal can be found in the relevant descriptions in the above embodiments, and will not be repeated here.

[0273] Step 503: Monitor the surface temperature of battery 101.

[0274] Step 504: Determine whether the temperature of battery 101 meets the condition of being greater than or equal to a second temperature threshold and less than or equal to a first temperature threshold. For example, the second temperature threshold can be -30℃, and the first temperature threshold can be 0℃. If the condition is met, proceed to step 505. If the condition is not met, proceed to step 508.

[0275] Step 505: Heating the battery 101 based on the pulse width modulation signal. Heating the battery 101 based on the pulse width modulation signal may include controlling the positive and negative terminals of the battery 101 to be alternately short-circuited and disconnected. For details, please refer to the relevant description in the above embodiments, which will not be repeated here.

[0276] Step 506: Determine whether the temperature rise rate of battery 101 is greater than the first threshold. If yes, proceed to step 515; otherwise, proceed to step 507. The first threshold can be 30℃ / min.

[0277] Step 507: Determine whether the temperature of battery 101 is greater than the first temperature threshold. If yes, proceed to steps 508 to 511 in sequence. If no, return to step 505.

[0278] Step 508: Stop heating the battery 101 based on the pulse width modulation signal. For example, the first switching circuit 102 can be disconnected to stop the alternating shorting and disconnection of the positive and negative terminals of the battery 101.

[0279] Step 509: Close the main positive relay K11 and the main negative relay K12 to control the second heating circuit to alternately charge and discharge the battery pack in battery 101.

[0280] Step 510: Monitor the surface temperature of battery 101.

[0281] Step 511: Determine whether the temperature rise rate of battery 101 is greater than the first threshold. If yes, proceed to step 515; otherwise, proceed to step 512. The first threshold can be 30℃ / min.

[0282] Step 512: Determine whether the temperature of battery 101 is greater than or equal to the target temperature. If yes, proceed to steps 513 and 514 in sequence. If no, return to step 509.

[0283] Step 513: Disconnect the switch branch 103 in the second heating circuit to end the heating of the battery 101.

[0284] Step 514: Start battery 101.

[0285] Step 515: Disconnect all circuits. Exemplarily, disconnecting all circuits may include disconnecting the fuse 1022 in the first switching circuit 102 and disconnecting the main positive relay K11 and the main negative relay K12.

[0286] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery heating method, characterized in that, The battery includes at least one battery pack, and the method includes: In response to the battery temperature being less than or equal to a first temperature threshold, the positive and negative terminals of the battery are alternately shorted and disconnected based on a pulse width modulation signal to heat the battery. In response to the battery temperature being greater than the first temperature threshold, the battery pack is controlled to perform alternating charging and discharging until the battery temperature reaches the target temperature, where the first temperature threshold is less than the target temperature.

2. The battery heating method according to claim 1, characterized in that, The step of heating the battery based on a pulse width modulation signal in response to the battery temperature being less than or equal to a first temperature threshold includes: Obtain the preset heating power required to heat the battery; The frequency of the pulse width modulation signal is determined based on the preset heating power and the impedance characteristics of the battery at different temperatures and under different states of charge.

3. The battery heating method according to claim 2, characterized in that, The step of determining the frequency of the pulse width modulation signal based on the preset heating power and the impedance characteristics of the battery at different temperatures and states of charge includes: Obtain the initial open-circuit voltage of the battery at the initial heating temperature; Based on the initial open-circuit voltage, the preset heating power, and the impedance characteristics of the battery, the initial impedance of the battery at the initial heating temperature and the initial frequency corresponding to the initial impedance are determined, and the initial frequency is used as the frequency of the pulse width modulation signal.

4. The battery heating method according to claim 1, characterized in that, The step of heating the battery based on a pulse width modulation signal in response to the battery temperature being less than or equal to a first temperature threshold further includes: Obtain the preset heating power required to heat the battery; Obtain the current actual heating power of the battery; The duty cycle of the pulse width modulation signal is determined based on the ratio of the preset heating power to the current actual heating power of the battery.

5. The battery heating method according to claim 4, characterized in that, The step of obtaining the current actual heating power of the battery includes: Obtain a first mapping relationship, which is used to characterize the change of the actual heating power of the battery with the battery temperature under the current state of charge and the current excitation signal frequency. Based on the current temperature of the battery and the first mapping relationship, the current actual heating power of the battery is determined.

6. The battery heating method according to claim 1, characterized in that, The method further includes: In response to the battery temperature being greater than or equal to a second temperature threshold and less than or equal to a first temperature threshold, the battery is heated based on a pulse width modulation signal, wherein the second temperature threshold is less than the first temperature threshold.

7. The battery heating method according to any one of claims 1-6, characterized in that, The control of the battery pack to perform alternating charging and discharging includes: Obtain a second mapping relationship, which is used to characterize the change of the battery impedance with battery temperature under the current state of charge and the current alternating charge and discharge frequency; Based on the current temperature of the battery and the second mapping relationship, the current for alternating charging and discharging of the battery pack is adjusted.

8. The battery heating method according to claim 7, characterized in that, The method further includes: Obtain the current open-circuit voltage of the battery; Based on the current temperature of the battery, the current open-circuit voltage, and the second mapping relationship, a current threshold for adjusting the current of the alternating charge and discharge of the battery pack is determined.

9. The battery heating method according to claim 7, characterized in that, The method of controlling the battery pack to perform alternating charging and discharging also includes: Obtain a third mapping relationship, which is used to characterize the change of the impedance of the battery with the frequency of the excitation signal under the current state of charge and current temperature; Based on the third mapping relationship, the frequency of alternating charging and discharging of the battery is adjusted.

10. The battery heating method according to any one of claims 1-6, characterized in that, The method further includes: Obtain the temperature rise rate of the battery; In response to the battery's temperature rise rate being greater than or equal to a first threshold, heating of the battery is stopped.

11. The battery heating method according to claim 10, characterized in that, The process of obtaining the temperature rise rate of the battery includes: A temperature rise model for the battery is established, which characterizes the rate of change of the battery's temperature rise function with temperature. The temperature rise rate of the battery is determined based on the battery's temperature rise model and the current temperature.

12. The battery heating method according to claim 11, characterized in that, The method of obtaining the temperature rise rate of the battery further includes: Obtain the temperature difference between the current temperature and the initial heating temperature of the battery; Obtain the heating time of the battery; The actual temperature rise rate of the battery is determined based on the ratio of the temperature difference between the current temperature and the initial heating temperature of the battery and the heating time of the battery. If the rate of temperature rise of the battery determined based on the battery's temperature rise model and the current temperature is inconsistent with the actual rate of temperature rise, the actual rate of temperature rise shall be determined as the rate of temperature rise of the battery.

13. A battery device, characterized in that, include: A battery, including at least one battery pack; The first heating circuit is connected to the positive and negative terminals of the battery; The second heating circuit is connected to the positive and negative terminals of the battery; The controller is configured as follows: In response to the battery temperature being less than or equal to a first temperature threshold, the first heating circuit is controlled to alternately short-circuit and disconnect the positive and negative terminals of the battery based on a pulse width modulation signal to heat the battery; and, In response to the battery temperature being greater than the first temperature threshold, the second heating circuit is controlled to alternately charge and discharge the battery pack in the battery until the battery temperature reaches the target temperature, where the first temperature threshold is less than the target temperature.

14. The battery device according to claim 13, characterized in that, The first heating circuit includes: A first switching circuit is connected to the positive and negative terminals of the battery. The controller is configured to control the first switching circuit to alternately turn on and off in response to the battery temperature being less than or equal to a first temperature threshold, so as to input the pulse width modulation signal to the battery.

15. The battery device according to claim 13, characterized in that, The controller is also configured to: Obtain the preset heating power required to heat the battery; The frequency of the pulse width modulation signal is determined based on the preset heating power and the impedance characteristics of the battery at different temperatures and under different states of charge.

16. The battery device according to claim 15, characterized in that, The controller is also configured to: Obtain the initial open-circuit voltage of the battery at the initial heating temperature; Based on the initial open-circuit voltage, the preset heating power, and the impedance characteristics of the battery, the initial impedance of the battery at the initial heating temperature and the initial frequency corresponding to the initial impedance are determined, and the initial frequency is used as the frequency of the pulse width modulation signal.

17. The battery device according to claim 13, characterized in that, The controller is also configured to: Obtain the preset heating power required to heat the battery; Obtain the current actual heating power of the battery; The duty cycle of the pulse width modulation signal is determined based on the ratio of the preset heating power to the current actual heating power of the battery.

18. The battery device according to claim 17, characterized in that, The controller is also configured to: Obtain a first mapping relationship, which is used to characterize the change of actual heating power corresponding to different excitation signal frequencies as the battery temperature changes under the current state of charge. Based on the frequency of the pulse width modulation signal, the current temperature of the battery, and the first mapping relationship, the current actual heating power of the battery is determined.

19. The battery device according to claim 13, characterized in that, The controller is also configured to: In response to the battery temperature being greater than or equal to a second temperature threshold and less than or equal to a first temperature threshold, the first heating circuit is controlled to heat the battery based on a pulse width modulation signal, wherein the second temperature threshold is less than the first temperature threshold.

20. The battery device according to any one of claims 13-19, characterized in that, The second heating circuit includes: A switch branch connects the positive and negative terminals of the battery; An energy storage circuit connects the battery and the switch branch; The controller is configured to control the switching branch in response to the battery temperature being greater than the first temperature threshold, so that the battery and the energy storage circuit discharge with each other.

21. The battery device according to claim 20, characterized in that, The number of each of the switch branches and the energy storage circuits is at least two. The switch branch includes a first connection point, a second connection point, and a third connection point that are interconnected by a switch element. The first connection point is connected to the positive terminal of the battery, and the second connection point is connected to the negative terminal of the battery. The first end of the energy storage circuit is connected to the third connection point, and the second ends of each of the energy storage circuits are connected to each other.

22. The battery device according to any one of claims 13-19, characterized in that, The battery comprises two battery packs connected in series, and the controller is configured to: In response to the battery temperature exceeding the first temperature threshold, the second heating circuit controls the two battery packs to discharge to each other.

23. The battery device according to claim 22, characterized in that, The second heating circuit includes: A switch branch connects the positive and negative terminals of the battery; An energy storage circuit is connected to the switch branch and the midpoint between the two battery packs; The controller is configured to control the two battery packs to discharge to each other via the switch branch and the energy storage circuit in response to the battery temperature being greater than the first temperature threshold.

24. The battery device according to claim 23, characterized in that, The switch branch includes a first connection point, a second connection point, and a third connection point that are interconnected by a switch element. The first connection point is connected to the positive terminal of the battery, and the second connection point is connected to the negative terminal of the battery. The first end of the energy storage circuit is connected to the third connection point; The second heating circuit also includes a neutral line, the first end of which is connected to the second end of the energy storage circuit, and the second end of which is connected to the midpoint between the two battery packs.

25. The battery device according to claim 23, characterized in that, The controller is also configured to: in response to the battery temperature being less than or equal to a first temperature threshold, control all switching elements of the switching branch to alternately and simultaneously turn on and off, so as to heat the battery based on the pulse width modulation signal.

26. The battery device according to any one of claims 13-19, characterized in that, The controller is also configured to: Obtain a second mapping relationship, which is used to characterize the change of impedance of the battery at different excitation signal frequencies with battery temperature under the current state of charge. Based on the current temperature of the battery, the current frequency of alternating charge and discharge of the battery, and the second mapping relationship, the current of alternating charge and discharge of the battery pack is adjusted.

27. The battery device according to claim 26, characterized in that, The controller is also configured to: Obtain the current open-circuit voltage of the battery; Based on the current temperature of the battery, the current open-circuit voltage, and the second mapping relationship, a current threshold for adjusting the current of the alternating charge and discharge of the battery pack is determined.

28. The battery device according to claim 27, characterized in that, The controller is also configured to: Obtain a third mapping relationship, which is used to characterize the change of the impedance of the battery at different temperatures under the current state of charge as a function of the excitation signal frequency. Based on the battery's current temperature, current state of charge, and the third mapping relationship, the frequency of alternating charging and discharging of the battery pack is adjusted.

29. The battery device according to any one of claims 13-19, characterized in that, The controller is also configured to: Obtain the temperature rise rate of the battery; In response to the battery's temperature rise rate being greater than or equal to a first threshold, the first heating circuit is controlled to stop heating the battery based on a pulse width modulation signal, and the second heating circuit is controlled to stop alternating charging and discharging of the battery pack in the battery.

30. A battery management system, characterized in that, The battery management system is used to manage the battery, which includes at least one battery pack, and the battery management system is configured to: In response to the battery temperature being less than or equal to a first temperature threshold, the positive and negative terminals of the battery are alternately shorted and disconnected based on a pulse width modulation signal to heat the battery. In response to the battery temperature being greater than the first temperature threshold, the battery pack is controlled to perform alternating charging and discharging until the battery temperature reaches the target temperature, where the first temperature threshold is less than the target temperature.

31. An electrical device, characterized in that, The electrical device includes a battery device as described in any one of claims 13-29, the battery device being used to provide electrical energy.

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