Battery heating system, battery heating method, power supply system, and electrical device

Abstract

To provide a battery heating system, a battery heating method, a power supply system, and an electrical device.SOLUTION: A battery heating system (100) comprises a voltage conversion unit (110) and a control unit (120). The voltage conversion unit (110) is electrically connected to a power supply (200) and a battery (300) to be heated, respectively, and receives a first voltage inputted by the power supply (200) or a second voltage inputted by the battery to be heated. The control unit (120) obtains a charging and discharging frequency of the voltage conversion unit (110), determines, according to the charging and discharging frequency, a charge transfer impedance of the battery to be heated, calculates, according to the charge transfer impedance, a safe amplitude current of the battery to be heated, and sends a control signal to the voltage conversion unit (110) according to the charging and discharging frequency and the safe amplitude current, where the voltage conversion unit (110) is used to perform boost or buck processing on the first voltage or the second voltage according to the control signal.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present application relates to the field of batteries, and in particular to battery heating systems, methods, power supply systems and electrical devices. [Background technology]

[0002] Energy conservation and emission reduction are key to the sustainable development of the automotive industry, and electric vehicles have become an important part of this due to their advantages in energy saving and environmental protection. For electric vehicles, battery technology is a key factor in their development.

[0003] With the widespread application of batteries, how to improve the performance of batteries has become an increasingly urgent issue to be solved in the development of battery technology. The inventors of the present application have found that the effect of temperature on the performance of batteries is particularly serious, and especially at low temperatures, the available capacity of the battery is greatly attenuated, leading to a situation where the battery cannot be discharged or charged under low temperature conditions, which significantly limits the performance of the battery. Summary of the Invention

[0004] SUMMARY OF THE DISCLOSURE The embodiments of the present application provide a battery heating system, method, power supply system and electrical device to solve the above problems in the prior art.

[0005] According to one aspect, an embodiment of the present application provides a battery heating system including a voltage conversion unit and a control unit, wherein the voltage conversion unit is electrically connected to a power source and a battery to be heated, respectively, and receives a first voltage input from the power source or a second voltage input from the battery to be heated, and the control unit obtains a charge / discharge frequency of the voltage conversion unit, determines a charge transfer resistance of the battery to be heated based on the charge transfer resistance, calculates a safe amplitude current of the battery to be heated based on the charge / discharge frequency and sends a control signal to the voltage conversion unit based on the charge / discharge frequency and the safe amplitude current, and the voltage conversion unit is used to perform a step-up or step-down process on the first voltage or the second voltage based on the control signal.

[0006] The above-mentioned embodiment of the present application determines a safe amplitude current based on the charge / discharge frequency and charge transfer resistance of the voltage conversion unit, sends a control signal to the voltage conversion unit based on the charge / discharge frequency and the safe amplitude current, and the voltage conversion unit performs a boost or down process on the first voltage or the second voltage based on the control signal, thereby significantly improving the heating effect of the battery and improving the heating efficiency.

[0007] In some embodiments, the method further includes a temperature monitoring unit, which is used to monitor a temperature of the heated battery and transmit the temperature to the control unit, and the control unit determines a charge transfer resistance of the heated battery based on the temperature and the charge / discharge frequency of the voltage conversion unit.

[0008] By using this method, the state of the battery being heated can be monitored in real time and the charge / discharge voltage can be corrected, thereby always providing the optimal heating effect to the battery being heated and greatly improving the heating efficiency.

[0009] In some embodiments, the control unit is further used to determine a charge transfer resistance of the heated battery based on a charge state of the heated battery, the temperature and the charge / discharge frequency, and the control unit is further used to calculate a safe amplitude current of the heated battery based on a lithium deposition potential of the heated battery and the charge transfer resistance.

[0010] The embodiments of the present application do not rely on the charge cut-off voltage and open circuit voltage set by the manufacturer, but obtain a safe amplitude current based on the equilibrium potential and charge transfer resistance of the graphite negative electrode, thereby maximally responding to the actual state of the battery being charged, breaking through the limitations of the cut-off voltage set by the manufacturer, and greatly improving the heating efficiency.

[0011] In some embodiments, the control unit pre-stores a mapping table of the charge state, temperature, charge / discharge frequency and safe amplitude current of the battery to be heated, and the control unit is further used to query the mapping table of safe amplitude current based on the charge state, the temperature and the charge / discharge frequency of the battery to be heated, and determine the safe amplitude current of the battery to be heated in a current state.

[0012] By setting a mapping table of the charge state of the battery to be heated, the temperature, the charging / discharging frequency and the safe amplitude current, the safe amplitude current of charging / discharging can be quickly obtained, and the heating efficiency is improved.

[0013] In some embodiments, the voltage conversion unit is used to perform a step-up or step-down process on the first voltage or the second voltage within a first time period, so as to make the charging current received by the heated battery smaller than the safe amplitude current.

[0014] In some embodiments, the voltage conversion unit is used to perform a voltage increase or decrease process on the first voltage or the second voltage within a second time period, so as to make the discharge current output by the heated battery smaller than the safe amplitude current.

[0015] In some embodiments, the control unit is further used to send a control signal to the voltage conversion unit when the temperature is less than a first preset threshold, and stop outputting the control signal when the temperature is equal to or greater than the first preset threshold.

[0016] By monitoring the temperature of the battery being heated in real time, the heating process can be controlled in a timely manner based on the condition of the battery being heated, and when the heating effect is low, the heating process can be stopped in a timely manner, thereby saving energy.

[0017] In some embodiments, the system includes an external heating source, and the control unit is used to activate the external heating source to heat the heated battery when the temperature is less than a second preset threshold, and to turn off the external heating source when the temperature is equal to or greater than a second preset threshold, and the first preset threshold is less than the second preset threshold.

[0018] By combining the rapid heating mode with the conventional heating mode using an external heating source, the heating effect of the heated battery is improved, and the heating efficiency is improved.

[0019] According to another aspect, an embodiment of the present application further provides a battery heating method in which a battery to be heated is electrically connected to a power source through a voltage conversion unit, the method including: obtaining a charge / discharge frequency of a voltage conversion unit; determining a charge transfer resistance of the battery to be heated based on the charge / discharge frequency; calculating a safe amplitude current of the battery to be heated based on the charge transfer resistance; sending a control signal to the voltage conversion unit based on the safe amplitude current and the charge / discharge frequency, and adjusting a first voltage input to the battery to be heated or a second voltage input to the power source based on the control signal.

[0020] The above-mentioned embodiment of the present application determines a safe amplitude current based on the charge / discharge frequency and charge transfer resistance of the voltage conversion unit, sends a control signal to the voltage conversion unit based on the charge / discharge frequency and the safe amplitude current, and the voltage conversion unit performs a boost or down process on the first voltage or the second voltage based on the control signal, thereby significantly improving the heating effect of the battery and improving the heating efficiency.

[0021] In some embodiments, determining a charge transfer resistance of the heated battery based on the charge and discharge frequency includes obtaining a temperature of the heated battery and determining a charge transfer resistance of the heated battery based on the temperature and the charge and discharge frequency.

[0022] By using this method, the state of the battery being heated can be monitored in real time and the charge / discharge voltage can be corrected, thereby always providing the optimal heating effect to the battery being heated and greatly improving the heating efficiency.

[0023] In some embodiments, determining a charge transfer resistance of the heated battery based on the charge and discharge frequency includes determining a charge transfer resistance of the heated battery based on a charge state of the heated battery, the temperature, and the charge and discharge frequency, and calculating a safe amplitude current of the heated battery based on the charge transfer resistance includes calculating a safe amplitude current of the heated battery based on a lithium deposition potential of the heated battery and the charge transfer resistance.

[0024] The embodiments of the present application do not rely on the charge cut-off voltage and open circuit voltage set by the manufacturer, but obtain a safe amplitude current based on the equilibrium potential and charge transfer resistance of the graphite negative electrode, thereby maximally responding to the actual state of the battery being charged, breaking through the limitations of the cut-off voltage set by the manufacturer, and greatly improving the heating efficiency.

[0025] In some embodiments, calculating the safe amplitude current of the heated battery based on the charge transfer resistance includes: pre-storing a mapping table of the state of charge, temperature, charge / discharge frequency and safe amplitude current of the heated battery; and querying the mapping table of safe amplitude current based on the state of charge, the temperature and the charge / discharge frequency of the heated battery to determine the safe amplitude current of the heated battery in a current state.

[0026] By setting a mapping table of the charge state of the battery to be heated, the temperature, the charging / discharging frequency and the safe amplitude current, the safe amplitude current of charging / discharging can be quickly obtained, and the heating efficiency is improved.

[0027] In some embodiments, adjusting the first voltage input to the heated battery or the second voltage input to the power source based on the control signal includes performing a step-up or step-down process on the first voltage or the second voltage within a first time period so as to reduce the charging current received by the heated battery to less than the safe amplitude current.

[0028] In some embodiments, adjusting the first voltage input to the heated battery or the second voltage input to the power source based on the control signal includes performing a voltage increase or decrease process on the first voltage or the second voltage within a second time period so as to make the discharge current output from the heated battery smaller than the safe amplitude current.

[0029] In some embodiments, the method further includes adjusting a first voltage input to the heated battery or a second voltage input to the power source when the temperature is less than a first preset threshold, and stopping adjusting the first voltage input to the heated battery or the second voltage input to the power source when the temperature is equal to or greater than the first preset threshold.

[0030] By monitoring the temperature of the battery being heated in real time, the heating process can be controlled in a timely manner based on the condition of the battery being heated, and when the heating effect is low, the heating process can be stopped in a timely manner, thereby saving energy.

[0031] In some embodiments, the method further includes activating an external heating source to heat the heated battery when the temperature is less than a second preset threshold, and shutting off the external heating source when the temperature is equal to or greater than a second preset threshold, the first preset threshold being less than the second preset threshold.

[0032] By combining the rapid heating mode with the conventional heating mode using an external heating source, the heating effect of the heated battery is improved, and the heating efficiency is improved.

[0033] According to another aspect of the embodiment of the present application, there is further provided a power supply system including the battery heating system provided by the above embodiment, the battery heating system being used to heat a battery to be heated, and the heated battery being used to provide a power source.

[0034] According to another aspect of an embodiment of the present application, there is further provided an electric device including the power supply system, the power supply system being adapted to provide a power source.

[0035] The above description is only a summary of the technical solution of the present invention, which can be implemented according to the contents of the specification in order to more clearly understand the technical solution of the present invention. In addition, in order to make the above and other objects, features and advantages of the present invention more clearly comprehensible, specific embodiments of the present invention are presented below. [Brief description of the drawings]

[0036] The drawings described herein provide further understanding of the present application and constitute a part of the present application, and the illustrative embodiments and the description thereof are intended to interpret the present application and are not intended to unduly limit the present application. [Figure 1] 1 shows a schematic diagram of an electrical device provided by an embodiment of the present application. [Diagram 2] 1 shows a schematic diagram of a heating system of an electric device provided by an embodiment of the present application. [Diagram 3] 1 shows a schematic diagram of a battery heating system provided by an embodiment of the present application. [Figure 4] FIG. 2 shows a schematic diagram of an equivalent circuit of a battery internal resistance provided by an embodiment of the present application. [Diagram 5] 1 shows a schematic diagram of the relationship between the internal resistance of a battery and the frequency of charging and discharging provided by an embodiment of the present application. [Figure 6] 1 shows a schematic diagram of the relationship between battery temperature and safe current provided by an embodiment of the present application. [Figure 7] FIG. 2 shows a schematic diagram of forward charging of a battery heating system provided by an embodiment of the present application. [Figure 8]FIG. 2 shows a schematic diagram of reverse discharge of a battery heating system provided by an embodiment of the present application. [Figure 9] FIG. 2 shows a topology diagram of a low-voltage battery heating provided by an embodiment of the present application. [Figure 10] FIG. 2 shows a topology diagram of high-voltage battery and low-voltage battery heating provided by an embodiment of the present application. [Figure 11] 1 shows a topology diagram of the OBC, high-voltage battery and low-voltage battery heating provided by an embodiment of the present application. [Figure 12] FIG. 1 shows a topology diagram of the OBC and low-voltage battery heating provided by an embodiment of the present application. [Figure 13] 1 shows a topology diagram of a battery heating system and an external heat source provided by an embodiment of the present application. [Figure 14] 1 shows a flow chart of a battery heating method provided by an embodiment of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly describe the technical solutions in the embodiments of the present application in combination with the drawings in the embodiments of the present application, and obviously, the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. Based on the embodiments of the present application, those skilled in the art can obtain all other embodiments without any creative effort, all of which are included in the claims of the present application.

[0038] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by those skilled in the art. In this application, the terms used in the specification of the application are only for describing specific embodiments and are not intended to limit the present application. The terms "comprise" and "have" and any variations thereof in the specification, claims and drawings of this application are intended to cover a non-exclusive inclusion. The terms "first", "second", etc. in the specification, claims and drawings of this application are intended to distinguish various objects and do not describe a particular order or primary relationship.

[0039] Reference to an "embodiment" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of this application. The appearance of the phrase in various places in the specification does not necessarily refer to all the same embodiment, nor is it an embodiment mutually exclusive, independent, or alternative to other embodiments. It is understood by those skilled in the art, either explicitly or implicitly, that the embodiment described in this application can be combined with other embodiments.

[0040] In the description of the present application, it should be explained that unless otherwise clearly specified or limited, the terms "attach", "connect", "join" and "attach" should be understood broadly. For example, they may be fixedly connected, detachably connected, or integrally connected. They may be directly connected, indirectly connected through an intermediate member, or communicated within two elements. Those skilled in the art can understand the specific meaning of the above terms in the present application according to the specific circumstances.

[0041] The term "and / or" in this application is merely a description of the relation between related objects, and represents the existence of three relations. For example, A and / or B can represent three situations: A exists, A and B exist simultaneously, and B exists. In addition, the character " / " in this application generally means that the related objects before and after it are in an "or" relationship.

[0042] The appearance of "plurality" in this application refers to two or more (including two), and similarly, "multiple groups" refers to two or more groups (including two groups), and "multiple sheets" refers to two or more sheets (including two sheets).

[0043] In the present application, the battery unit may include a lithium ion secondary battery, a lithium ion primary battery, a lithium sulfur battery, a sodium lithium ion battery, a sodium ion battery, or a magnesium ion battery, etc., and the embodiments of the present application are not limited thereto. The battery unit may be cylindrical, flat, rectangular, or other shapes, etc., and the embodiments of the present application are not limited thereto. The battery unit is generally divided into three types according to the package type: a cylindrical battery unit, a rectangular battery unit, and a soft package battery unit, and the embodiments of the present application are not limited thereto.

[0044] At present, with the development of technology, the application of power battery is becoming more and more widespread. Power battery is not only applied to energy storage power supply systems such as hydroelectric power generation, thermal power generation, wind power generation and solar power stations, but also widely applied to various fields such as electric transportation tools such as electric bicycles, electric motorcycles, electric cars, military equipment and aerospace. With the continuous expansion of the application field of power battery, its market demand is also constantly increasing.

[0045] The inventors of the present application have found that in existing electric devices that use battery technology as a power source, such as electric vehicles, the battery may provide power to the electric device, or may power low-voltage systems such as dashboards, car lights, and radar equipment. Currently, most batteries use lithium-ion batteries for electrical energy storage. The inventors of the present application have found that lithium-ion batteries mainly realize the conversion of chemical energy and electrical energy by the movement of lithium ions between the positive and negative electrodes, and that under low temperature conditions, the mobility of lithium ions in the electrolyte is greatly weakened, so that the impact of temperature on the performance of lithium-ion batteries is very serious, especially at low temperatures, the available capacity of the battery is greatly attenuated, leading to a situation in which the lithium battery cannot be charged or discharged under low temperature conditions, and the battery's multiplication performance is seriously attenuated, greatly limiting the performance of the lithium battery. In addition, under low temperature charging conditions, the activity of the battery is low, so that lithium precipitation reactions are likely to occur, causing short circuits in the battery and leading to serious safety risks. Therefore, under low temperature conditions, the lithium battery must first be heated to an appropriate temperature before use.

[0046] At present, in order to ensure the performance of lithium-ion batteries, batteries are usually heated by external heating sources, such as heating by heating film or heating by PTC water heating. Both heating film and PTC water heating are contact heat transfer with the surface of the battery, and their main advantages are simple heating structure and mature technology. However, this method requires the installation of an additional heating device and the provision of power or heat source for the additional heating device, so the structure is relatively complicated and the cost is relatively high. At the same time, the method of external heating source has a relatively low temperature rise rate, generally 0.2-0.6℃ / min, the heating between battery cells is uneven, and the temperature difference between the inside and outside of the battery cell is large; at the same time, the external heating source is heated by thermal conduction, so the heat is easily dissipated and the energy utilization rate is relatively low.

[0047] Based on the above considerations, in order to solve the problems of the prior art, such as low heating efficiency and complicated structure when heating a battery, the embodiment of the present application provides a battery heating system and method, which utilizes the characteristics that the battery has a large internal resistance and is prone to heat generation under low temperature conditions according to the principle that the battery itself generates heat when charging and discharging, and frequently charges and discharges between battery packs, and different battery packs become loads on each other, and the control unit controls the voltage conversion unit to periodically adjust the input and output voltage of different battery packs, so that the entire battery circuit generates high-frequency AC current, and when the AC current passes through the low-temperature battery, the high resistance of the battery formed under low temperature conditions is used to directly generate heat from inside the battery, thereby achieving the purpose of rapid heating of the battery. With this method, the battery directly generates heat using the heat generated by itself, so there is no need for an additional heating device, and the energy utilization rate is high and the heating speed is fast.

[0048] The battery heating system, method and power supply system disclosed in the embodiments of the present application can be applied to a battery management system as a part of the battery management system, which can be applied to, but is not limited to, electric devices such as vehicles, ships or spacecraft, and is advantageous in rapidly heating the batteries and improving the performance of the batteries.

[0049] An embodiment of the present application provides an electric device that uses a battery including the battery heating system provided by the embodiment of the present application as a power source, and the electric device may be, but is not limited to, a mobile phone, a tablet, a laptop, an electric toy, an electric tool, a battery car, an electric car, a ship, a spacecraft, etc. Here, the electric toy may include a stationary or mobile electric toy such as a game console, an electric car toy, an electric boat toy, and an electric plane toy, and the spacecraft may include an airplane, a rocket, a space shuttle, a space capsule, etc.

[0050] In the following embodiment, for ease of explanation, one embodiment of the present application will be described taking an example in which the electric device is a vehicle 1000 .

[0051] Please refer to FIG. 1, which is a configuration diagram of a vehicle provided by an embodiment of the present application. The vehicle may be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid car or an extended vehicle, etc. A battery 2000 is installed inside the vehicle, and the battery 2000 may be installed at the bottom, head or tail of the vehicle. The battery 2000 may supply power to the vehicle, for example, the battery 2000 may be used as an operating power source for the vehicle. The vehicle further includes a battery management system 1000 and a motor 3000, and the battery management system 1000 controls the battery 2000 to supply power to the motor 3000, for example, used as an operating power source during starting, navigation and running of the vehicle.

[0052] In some embodiments of the present application, the battery 2000 can be used not only as an operational power source for the vehicle, but also to replace or partially replace fuel or natural gas as the vehicle's propulsion power source to provide propulsion power to the vehicle.

[0053] The battery 2000 referred to in the embodiments of the present application refers to a single physical module including one or more battery units to provide higher voltage and capacity. For example, the battery 2000 referred to in the present application may include a battery module or a battery pack. There may be a plurality of battery units, and the plurality of battery units may be connected in series, parallel, or mixed, and mixed connection means that both series and parallel connections exist among the plurality of battery units. The plurality of battery units may be directly connected in series, parallel, or mixed, and then the whole consisting of the plurality of battery units may be housed in a case, or, naturally, the plurality of battery units may first be connected in series, parallel, or mixed to form a battery in the form of a battery module, and the plurality of battery modules may be connected in series, parallel, or mixed to form a whole and housed in a case. The battery 2000 may include other structures. For example, the battery 2000 may further include a junction member for realizing electrical connection between the plurality of battery units. Here, each battery unit may be, but is not limited to, a lithium ion secondary battery, a lithium ion primary battery, a lithium-sulfur battery, a sodium lithium ion battery, or a magnesium ion battery, and may be cylindrical, flat, rectangular, or have any other shape.

[0054] The battery management system 1000 is a system for managing the battery, which is the core of the battery. The battery management system is a management system that controls the charging and discharging process of the battery, realizes protection for the battery, and improves the overall performance of the battery by collecting and calculating parameters such as voltage, current, temperature, and SOC, and is an important link between the vehicle-mounted power battery and the electric vehicle. The battery heating system 100 provided by the embodiment of the present application is a component part of the battery management system 1000. As shown in FIG. 2, it is an application configuration diagram of the battery heating system 100 provided by the present application. In an electric device, it usually includes a high-voltage battery 500 and a low-voltage battery 700, and the high-voltage battery 500 charges the low-voltage battery 700 after being stepped down by a voltage conversion unit, and supplies the entire low-voltage system together with the low-voltage battery 700, and the low-voltage battery 700 mainly provides power to the low-voltage loads of the electric device, such as dashboards, car lights, and radars, and the low-voltage battery 700 is directly connected to the low-voltage load 600.

[0055] The battery heating system 100 provided by the embodiment of the present application includes a control unit 120 and a voltage conversion unit 110, which is responsible for voltage conversion processing under normal operating conditions. When the battery needs to be heated, the voltage conversion unit 110 performs a voltage increase or decrease processing for the battery under the control of the control unit 120, so as to realize rapid heating of the battery 300 to be heated.

[0056] Specifically, the battery heating system 100 provided by the embodiment of the present application includes a voltage conversion unit 110 and a control unit 120, as shown in Fig. 3, the voltage conversion unit 110 is electrically connected to a power source 200 and a battery 300 to be heated, and receives a first voltage input from the power source 200 or a second voltage input from the battery 300 to be heated. The control unit 120 obtains the charge / discharge frequency of the voltage conversion unit 110, determines the charge transfer resistance of the battery 300 to be heated according to the charge / discharge frequency, calculates the safe amplitude current of the battery 300 to be heated according to the charge transfer resistance, and sends a control signal to the voltage conversion unit 110 according to the charge / discharge frequency and the safe amplitude current, so that the voltage conversion unit 110 performs a step-up or step-down process on the first voltage or the second voltage according to the control signal.

[0057] As shown in Fig. 3, a configuration diagram of a battery heating system 100 provided by an embodiment of the present application is shown. A control unit 120 is electrically connected to the voltage conversion unit 110 and is used to control the voltage conversion unit 110. Both ends of the voltage conversion unit 110 are respectively connected to a power source 200 and a battery 300 to be heated, and are used to convert the voltage output by the power source 200 or convert the voltage output by the battery 300 to be heated.

[0058] Here, the power source 200 is a carrier that provides input to the battery 300 to be heated, and may be a high-voltage battery 500 assembled in the electrical device itself, or an additionally installed low-voltage battery 700, or an external power source, etc., and its purpose is to provide a voltage input to the battery 300 to be heated.

[0059] The heated battery 300 is a battery that requires heating and is installed in the electric device itself, and may be a low-voltage battery 700 or a high-voltage battery 500. The heated battery 300 is usually a lithium battery, and at a relatively low temperature, the available capacity of the battery is greatly attenuated, the battery cannot be discharged or charged, and the battery's multiplication performance is seriously attenuated. And, under the condition of low-temperature charging, the battery is prone to lithium deposition reaction, which causes a short circuit in the battery and leads to serious safety risks. In the charging process of a lithium-ion battery, lithium ions are released from the positive electrode and inserted into the negative electrode. However, in some cases, such as when charging at low temperature, the lithium ions released from the positive electrode are not inserted into the negative electrode, and the lithium ions are only deposited on the surface of the negative electrode, which is called lithium deposition reaction. When a lithium deposition reaction occurs in a lithium battery, it causes a short circuit in the battery and leads to serious safety risks.

[0060] In the embodiment of the present application, in order to heat the heated battery 300 under low temperature conditions, the heated battery 300 is periodically charged and discharged, and self-heating is performed by the heat generated by the heated battery itself, in combination with the characteristic that the resistance of the heated battery 300 under low temperature conditions is relatively high. In the frequent charging and discharging process of the heated battery 300, the larger the charging and discharging current is, the higher the frequency of charging and discharging is, and the more heat the heated battery 300 generates during the charging and discharging process, the faster the temperature rise rate is. However, since lithium precipitation reaction is likely to occur when charging and discharging a lithium battery under low temperature conditions, it is necessary to consider the balance relationship between the charging and discharging frequency, the safe amplitude current, and the heating efficiency as a whole when charging and discharging a lithium battery, so as to quickly heat the heated battery 300 and at the same time avoid the lithium precipitation reaction of the heated battery 300 during the heating process.

[0061] As shown in Figure 4, a schematic diagram of the equivalent circuit of the battery internal resistance of a lithium-ion battery is shown. The equivalent circuit of a lithium-ion battery is composed of three parts including Z1, Z2 and Z3. Here, Z1 is the ohmic resistance component of the battery internal current collector, active material, electrolyte, etc., and Z2 is QSEI and R SEI is the resistance component corresponding to the solid electrolyte phase interface (SEI) film containing dl and R CT is the charge transfer resistance of the solid-liquid phase interface of the active material.

[0062] Here, Q SEI and Q dl belongs to the constant phase element (CPE), which is expressed by the CPE coefficient Q and the CPE index n, and its resistance formula is as follows:

[0063]

number

[0064] The equation for the real part of the electrical resistance of the equivalent circuit of the lithium ion battery is as follows:

[0065]

number

[0066] As can be seen from the above, the real part of the resistance of the lithium-ion battery, Z Reis related to the frequency. As shown in Figure 5, the electrochemical spectrum analysis schematic diagram of the lithium battery after the above calculation of the internal resistance of the lithium battery is simplified, showing the resistance of the lithium-ion battery at various charge and discharge frequencies. Here, the horizontal axis represents the real part resistance of the battery, and the vertical axis represents the imaginary part resistance of the battery. The electrochemical spectrum can be divided into a charge transfer region and a mass transfer region, and the region between the charge transfer region and the mass transfer region is a mixed region.

[0067] In the charge transfer region, the higher the charge and discharge frequency of the battery, the more charge transfer occurs in the charge and discharge process, and no diffusion of materials occurs, i.e., no lithium precipitation reaction occurs. In the extremely high frequency region, the battery exhibits pure electrical resistance characteristics, and its resistance is Z=R 0 In the mass transfer region, the charge and discharge frequency is relatively low, and both charge and mass transfer occur, that is, the battery undergoes lithium precipitation reaction in this region, and the charge and discharge frequency in the mass transfer region is lower than that in the charge transfer region. In the mixed region, the lithium ion battery transitions from charge transfer to mass transfer, and in this section, both charge and mass transfer occur. Therefore, as can be seen from the above, in order to avoid the occurrence of lithium precipitation reaction in the charge and discharge process, the charge and discharge frequency needs to be as high as possible. Here, there is no unified standard for the values ​​of the high and low frequencies, and in general, the high frequency range is divided into 1KHz to 10KHz, and the medium and low frequency ranges are divided into 0.001Hz to 1KHz. It should be noted that the above frequency range is not constant, but changes according to the influence of the battery temperature and the battery state.

[0068] It should be noted that, theoretically, the higher the charge / discharge frequency in the charge transfer region, the less likely the lithium precipitation reaction will occur in the battery being charged, but in order to most effectively guarantee the charge / discharge performance of the battery, the charge / discharge frequency needs to be set high. However, in practice, the charge / discharge of the battery needs to be controlled by the voltage conversion unit 110, and the voltage conversion unit 110 needs to switch between the charge process and the discharge process by a switch, and since the switching by the switch takes time, it is very difficult to switch between the charge / discharge more quickly. Therefore, the switching frequency of the voltage conversion unit 110 is an important factor that limits the charge / discharge frequency. Therefore, in this application, in order to reduce the complexity of the battery heating system 100 and improve the charge / discharge efficiency, the inventor of this application proposes to directly use the maximum switching frequency of the voltage conversion unit 110 as the charge / discharge frequency of the battery heating system 100.

[0069] As described above, when charging and discharging a lithium-ion battery, the balance relationship between the charging and discharging frequency, the safe amplitude current and the heating efficiency should be considered as a whole, so as to quickly charge the heated battery 300 and at the same time avoid the lithium deposition reaction of the heated battery 300. After the charging and discharging frequency is determined, the safe amplitude current of the battery heating system 100 under a specific temperature condition should be determined based on the charging and discharging frequency.

[0070] Referring to the schematic diagram of the equivalent circuit of the battery internal resistance shown in Figure 4, in order to avoid the occurrence of lithium deposition reaction in the negative electrode of a lithium ion battery, it is necessary to satisfy the solid-liquid phase potential difference on the surface of the negative electrode particles to be greater than the equilibrium potential of the lithium deposition reaction. That is, it is as follows.

[0071]

number

[0072] For the lithium deposition reaction to occur, lithium ions must gain electrons and be reduced to lithium metal. It is generally believed that the lithium deposition reaction first occurs on the surface of graphite particles, i.e., inside the solid electrolyte phase interface (SEI) film. The overpotential for the lithium insertion reaction inside the SEI film is as follows:

[0073]

number

[0074] Based on the derivation process of the lithium-ion battery resistance spectrum, by linearizing the Butler-Volmer equation, the overpotential of the lithium insertion reaction inside the SEI film can be approximated as follows:

[0075]

number

[0076]

number

[0077] The equilibrium potential of the graphite anode at a particular battery charge state SOC is U e,1 Therefore, in order to prevent the lithium deposition reaction from occurring on the negative electrode surface, the charge transfer resistance R ct The voltage across V 3 must satisfy the following formula:

[0078]

number

[0079] In the equivalent circuit of the battery internal resistance shown in Figure 4, Z 3 The relationship between the overall resistance of the part and the charge / discharge frequency is as follows:

[0080]

number

[0081] When applying AC excitation to a lithium-ion battery, Z 3 The voltage amplitude across

[0082]

number

[0083] As can be seen from the above equations (1) and (2), the conditions under which lithium deposition does not occur in a lithium-ion battery under AC excitation are as follows:

[0084]

number

[0085] In order to avoid the occurrence of lithium precipitation reactions, Z 3 The voltage amplitude across the section is always less than the equilibrium potential of the graphite anode.

[0086] As can be seen from the above, in the embodiment of the present application, when the maximum switching frequency of the battery conversion unit is used as the charge / discharge frequency of the battery heating system 100, as can be seen from FIG. 3 The electrical resistance of the part is the charge transfer resistance R of the lithium battery.ct That is,

[0087]

number

[0088] Therefore, the safe amplitude current under the above charge / discharge frequency is U e,1 / R ct That is, in the process of charging and discharging the heated battery, the charging current is U e,1 / R ct Less than.

[0089] According to the above process, the charging and discharging frequency of the heated battery 300 is determined, the charge transfer resistance is determined based on the charging and discharging frequency, and then the safe amplitude current of charging and discharging is determined based on the charge transfer resistance. It should be noted that the above charge transfer resistance and the corresponding safe amplitude current are closely related to the temperature and the state of charge SOC of the battery, and are not constant, but constantly change according to the change of temperature. The charge transfer resistance and the corresponding safe amplitude current at a specific temperature and a specific state of charge SOC can be obtained by querying the electrochemical spectrum EIS of the battery to be charged, which is pre-installed in the control unit 120, and the control unit 120 can query and obtain it under specific conditions, and the specific query method is not described here.

[0090] In the prior art, for a heated battery 300, the battery manufacturer sets the charge cut-off voltage V mas , and set different charging currents according to the charging cut-off voltage, and different cut-off voltages have different charging capacities. The charging cut-off voltage is generally a relatively conservative value, and is generally applied to the DC operating mode, and cannot actually reflect the state of the battery in the AC operating mode. For example, when the SOC is relatively low, the open circuit voltage V at the SOC is ocv is relatively small, the current of several tens of thousands is too large, leading to lithium precipitation reactions in the battery.

number

number

[0091] In the present embodiment, the equilibrium potential U of the graphite negative electrode of the lithium battery is determined independently of the set charge cutoff voltage and open circuit voltage. e,1 and charge transfer resistance R ct By determining the safe amplitude current based on the above, it can respond to the actual state of the battery being charged to the maximum extent, break through the cut-off voltage limit set by the manufacturer, and greatly improve the heating efficiency. As shown in Fig. 6, under the action of the method provided by this embodiment, the heated battery 300 can be heated quickly within a short time, and the safe amplitude current also gradually increases, which greatly improves the heating effect of the heated battery 300.

[0092] After the control unit 120 determines the charge / discharge frequency and the safe amplitude current of the battery 300 to be heated, it sends a control signal to the voltage conversion unit 110 according to the charge / discharge frequency and the safe amplitude current, and the voltage conversion unit 110 performs a step-up or step-down process on the first voltage or the second voltage of the power source and the battery to be heated according to the control signal. The charge / discharge frequency is the maximum charge / discharge frequency, and the safe amplitude current is the maximum charge / discharge current.

[0093] The control unit 120 sends a control signal to the voltage conversion unit 110 according to the charging / discharging frequency and the safe amplitude current within the first time period to make the first voltage output by the power source 200 higher than the second voltage of the heated battery 300, thereby performing forward charging of the battery to be charged. Within the second time period, the control unit 120 sends a control signal to the voltage conversion unit 110 to make the first voltage of the power source 200 lower than the second voltage of the heated battery 300, thereby putting the heated battery 300 into a discharging state. During the first and second time periods, when the first voltage is increased or decreased, the voltage difference between the first voltage and the second voltage needs to be kept within a certain range, so that the maximum charging / discharging current of the heated battery 300 in a charging state is smaller than the determined safe amplitude current.

[0094] Therefore, as can be seen from the above, in the embodiment of the present application, the control unit 120 determines a safe amplitude current based on the charge / discharge frequency and charge transfer resistance of the voltage conversion unit 110, sends a control signal to the voltage conversion unit 110 based on the charge / discharge frequency and the safe amplitude current, and the voltage conversion unit 110 performs a boost or down process on the first voltage or the second voltage based on the control signal, thereby greatly improving the heating effect of the battery and improving the heating efficiency.

[0095] In some embodiments, the battery heating system 100 further includes a temperature monitoring unit 130, which is used to monitor the temperature of the heated battery 300 and transmit the temperature to the control unit 120, and the control unit 120 determines the charge transfer resistance of the heated battery 300 based on the temperature and the charge / discharge frequency of the voltage conversion unit 110.

[0096] As shown in FIG. 7, the battery heating system 100 provided by the embodiment of the present application further includes a temperature monitoring unit 130, which is connected to the battery 300 to be heated and used to monitor the temperature of the battery 300 to be heated and transmit the monitored temperature information to the control unit 120, so that the control unit 120 controls the charging / discharging frequency and charging / discharging current of the voltage conversion unit 110 based on the temperature information of the battery to be heated.

[0097] The temperature monitoring unit 130 may be a temperature sensor, which may include a thermocouple, a negative temperature coefficient temperature sensor, or an infrared sensor, etc., and is usually installed around or on the surface of the heated battery 300, thereby accurately monitoring the temperature of the heated battery 300. The temperature monitoring unit 130 periodically obtains temperature information of the heated battery 300 and transmits the temperature information to the control unit 120, and the control unit 120 periodically determines a safe amplitude current according to the temperature information, the state of charge SOC of the heated battery 300 and the charging and discharging frequency of the voltage conversion unit 110, and adjusts the charging and discharging voltage of the power source 200 and the heated battery 300 according to the safe amplitude current.

[0098] In this manner, the state of the heated battery 300 can be monitored in real time and the charging / discharging voltage can be corrected, so that the heated battery 300 can always have an optimal heating effect and the heating efficiency is greatly improved.

[0099] In some embodiments, the control unit 120 is further used to determine a charge transfer resistance of the heated battery 300 based on a state of charge SOC, a temperature and a charge / discharge frequency of the heated battery 300, and the control unit 120 is further used to calculate a safe amplitude current of the heated battery 300 based on a lithium deposition potential of the heated battery 300 and the charge transfer resistance.

[0100] The control unit 120 obtains the state of charge of the battery 300 to be heated in advance, and the state of charge (SOC) can be obtained by various methods. One method is that when the battery is shipped, the manufacturer calibrates the SOC and specifies the state of charge (SOC) of the battery at a specific temperature and voltage. The SOC can also be calculated by ampere-hour integration, that is, the battery management system records the current flowing through the battery and then calculates the current SOC according to the usage time. The SOC can also be obtained by combining the above two methods. Of course, there are other methods of obtaining SOC, but the description of them will be omitted here.

[0101] After acquiring the state of charge SOC of the battery 300 to be heated, the control unit 120 determines the charge transfer resistance R of the battery 300 to be heated by the electrochemical spectrum EIS of the battery 300 to be heated based on the temperature information acquired by the temperature monitoring unit 130 and the charge / discharge frequency. CT Determine.

[0102] The control unit 120 further obtains a lithium deposition potential of the heated battery 300, where the lithium deposition potential is an equilibrium potential U of the graphite negative electrode of the heated battery 300 at a specific state of charge SOC. e,1 In order to prevent lithium deposition on the surface of the graphite anode, the charge transfer resistance R ct The voltage across V 3 must satisfy the following formula:

[0103]

number

[0104] In the equivalent circuit of the battery internal resistance shown in Figure 4, Z 3 The relationship between the overall resistance of the part and the charge / discharge frequency is as follows:

[0105]

number

[0106] When applying AC excitation to a lithium-ion battery, Z 3 The voltage amplitude across

[0107]

number

[0108] The conditions under which lithium deposition does not occur in a lithium ion battery under AC excitation are as follows:

[0109]

number

[0110] That is, in the equivalent circuit of a lithium-ion battery graphite anode, under a specific battery charge state SOC, Z 3 The voltage amplitude across the section is always less than the equilibrium potential of the graphite anode.

[0111] In the embodiment of the present application, when the maximum switching frequency of the battery conversion unit is used as the charge / discharge frequency of the battery heating system 100, as can be seen from FIG. 3 The electrical resistance of the part is the charge transfer resistance R of the lithium battery. ct That is,

[0112]

number

[0113] The safe amplitude current at the above charge / discharge frequency is U e,1 / R ct can be determined.

[0114] By obtaining a safe amplitude current based on the equilibrium potential and charge transfer resistance of the graphite negative electrode, rather than relying on the set charge cut-off voltage and open circuit voltage, the actual state of the charging battery can be maximally reacted to, breaking through the limitations of the cut-off voltage set by the manufacturer, and greatly improving the heating efficiency of the heated battery.

[0115] In some embodiments, in order to improve the heating efficiency of the battery, the control unit 120 pre-stores a mapping table of the charge state, temperature, charge / discharge frequency and safe amplitude current of the battery 300 to be heated, and the control unit 120 is further used to query the mapping table of the safe amplitude current based on the charge state, the temperature and the charge / discharge frequency of the battery 300 to be heated, and determine the safe amplitude current of the battery 300 to be heated in the current state.

[0116] According to the electrochemical spectrum EIS of the heated battery 300, the safe amplitude current of the battery at a certain temperature, charge / discharge frequency and charge state is determined, so that the control unit 120 can pre-store a mapping table of the charge state, temperature, charge / discharge frequency and safe amplitude current of the heated battery 300, and in the heating process, can determine the corresponding safe amplitude current in real time according to the obtained charge state and temperature of the heated battery 300. As shown in Table 1, the mapping table of the charge state, temperature, charge / discharge frequency and safe amplitude current of the heated battery 300 is shown.

[0117] [Table 1]

[0118] In the heating process of the heated battery 300, when the charge / discharge frequency, temperature and charge state are determined, the safe amplitude current can be obtained in time by querying the mapping table.

[0119] As can be seen from Table 1, under certain frequency XHZ and temperature conditions, the lower the SOC, the higher the allowable safe amplitude current, and the better the heating effect. Under certain frequency XHZ and SOC conditions, with the increase in temperature, the allowable safe amplitude current also increases, and when a certain temperature condition is reached, the allowable safe amplitude current is maintained stably.

[0120] In some embodiments, the voltage conversion unit 110 is used to increase or decrease the first voltage or the second voltage within a first time, so that the charging current received by the heated battery 300 is smaller than the safe amplitude current. The voltage conversion unit 110 is further used to increase or decrease the first voltage or the second voltage within a second time, so that the discharging current output by the heated battery 300 is smaller than the safe amplitude current.

[0121] As shown in Figures 7 and 8, a topology structure diagram is shown in which a voltage conversion unit 110 heats a battery 300 heated by a power source 200 under the control of a control unit 120, where communication between the control unit 120 and the voltage conversion unit 110 can be via a CAN path or other paths.

[0122] 7 shows an operation mode diagram of the power source 200 discharging and forward charging the heated battery 300 in the first time. In the initial condition, the control unit 120 first determines the charging and discharging frequency K1 and the safe amplitude current I1 of the voltage conversion unit 110 according to the state of charge SOC of the heated battery 300. In this case, the power source 200 discharges and charges the heated battery 300, the output voltage of the power source 200 is Ua, the voltage of the heated battery 300 is Ub, the voltage conversion unit 110 boosts the voltage Ua output by the power source 200, and Ua is boosted to Ua1 by the voltage conversion unit 110, and I1=(Ua1-Ub) / R, where R is the equivalent resistance value of the battery heating system 100. Here, Ua1 needs to be determined by the control unit based on the safe amplitude current I1, so as to ensure that the charging current of the heated battery 300 is smaller than the safe amplitude current, and also ensure that no lithium precipitation reaction occurs in the heated battery 300 while charging the heated battery 300.

[0123] Figure 8 shows an operation mode diagram in which the voltage conversion unit 110 is discharged by the heated battery 300 under the control of the control unit 120 and charges the power source 200 during the second time. Compared with the forward charging in Figure 7, Figure 8 shows a reverse discharging, and the directions of the two are reversed. The output voltage of the heated battery 300 is Ub, and the voltage of the power source 200 is Ua. The control unit 120 controls the voltage conversion unit 110 to perform a step-down process on Ua, and Ua becomes Ua2 after being stepped down by the voltage conversion unit 110, and I1=(Ub-Ua2) / R, where R is the equivalent resistance value of the battery heating system 100. The discharge current output by the heated battery 300 is smaller than the safe amplitude current.

[0124] The above forward charging and reverse discharging conversion period is the charging and discharging frequency K1, that is, the heated battery 300 and the power source 200 are in a charging state half the time and in a discharging state half the time, switching between charging and discharging. The heating equation of electrical resistance is as follows:

[0125]

number

[0126] As can be seen from the above, the larger the current, the higher the heating effect. The control unit 120 will constantly adjust the safe amplitude current as the battery is charged and discharged, so that the heating effect of the battery will be higher and higher as the battery is charged and discharged.

[0127] The battery heating method provided by the embodiment of the present application is applicable to various electric devices such as electric vehicles, which generally include a high-voltage battery 500 for providing power to the electric device and a low-voltage battery 700 for providing a power source 200 for a low-voltage device of the electric device. In order to heat the battery 300 to be heated, various methods can be used as the power source 200 to provide a heating power source for the battery 300 to be heated, and for ease of explanation, an electric vehicle is taken as an example below.

[0128] 9, the electric device includes a high-voltage battery 500, a first voltage transformation unit 111, a first low-voltage battery 301 and a low-voltage load 600, in which the high-voltage battery 500 provides power to the electric device in one embodiment, and further charges the first low-voltage battery 301 via the first voltage transformation unit 111 in another embodiment, and the first low-voltage battery 301 provides power to the low-voltage load 600. In order to quickly heat the first low-voltage battery 301, the electric device is provided with a second low-voltage battery 302, a second voltage transformation unit 112, a control unit 120 and a temperature monitoring unit 130.

[0129] In normal operation, the high-voltage battery 500 charges the first low-voltage battery 301 through the first voltage conversion unit 111, and the first low-voltage battery 301 provides the power supply 200 to the low-voltage load 600. If the temperature monitoring unit 130 monitors that the temperature of the first low-voltage battery 301 is lower than a certain threshold, the performance of the first low-voltage battery 301 is relatively greatly affected, and it needs to be heated first, and the control unit 120 sends a control signal to the second voltage conversion unit 112, which controls the first low-voltage battery 301 and the second low-voltage battery 302 to be continuously charged and discharged according to the determined charging and discharging frequency and safe amplitude current, and gradually increase the temperature of the first low-voltage battery 301, thereby realizing the rapid heating of the first low-voltage battery 301.

[0130] 10 shows another battery heating topology diagram, which includes a high-voltage battery 500, a first voltage transformation unit 111, a first low-voltage battery 301, a low-voltage load 600, a control unit 120 and a temperature monitoring unit 130, and the control unit 120 is connected to the first voltage transformation unit 111 and controls the first voltage transformation unit 111 to heat the first low-voltage battery 301. In this topology structure, the battery heating system 100 and the high-voltage battery 500 of the electric device share one voltage transformation unit, and by improving the original voltage transformation unit, high-frequency interaction between the high-voltage battery and the low-voltage battery can be realized.

[0131] In normal operation, the high-voltage battery 500 provides power to the electric device and at the same time charges the first low-voltage battery 301 through the first voltage conversion unit 111, and the first low-voltage battery 301 provides power to the low-voltage load 600. If the temperature monitoring unit 130 monitors that the temperature of the first low-voltage battery 301 is lower than a certain threshold, the performance of the first low-voltage battery 301 is relatively greatly affected, and it needs to be heated first, and the control unit 120 sends a control signal to the first voltage conversion unit 111, which controls the first low-voltage battery 301 and the high-voltage battery 500 to continuously charge and discharge according to the charging and discharging frequency and safe amplitude current determined by the first voltage conversion unit 111, and gradually increases the temperature of the first low-voltage battery 301, thereby realizing the rapid heating of the first low-voltage battery 301. In this way, the high-voltage battery and the low-voltage battery share one voltage conversion unit, which simplifies the structure and reduces the complexity of the electric device.

[0132] FIG. 11 shows another battery heating topology diagram, in which the battery heating system 100 of the electric device, the high-voltage battery 500 and the on-board charging system OBC (On Board Charger) are integrated. As shown in FIG. 11, the on-board charging system OBC includes an AC outlet 803, a compensation unit 801, an AC / DC voltage conversion unit 802 and a first voltage conversion unit 111. In FIG. 11, the high-voltage battery 500, the on-board charging system OBC and the battery heating system share one first voltage conversion unit 111. When the first low-voltage battery 301 needs to be heated, the high-voltage battery 500 or the on-board charging system OBC can be used as a power source to provide a heating power source to the first low-voltage battery 301.

[0133] When the first low-voltage battery 301 is heated by the on-board charging system OBC, in a normal operating state, the high-voltage battery 500 charges the first low-voltage battery 301 through the first voltage conversion unit 111, and the first low-voltage battery 301 provides power to the low-voltage load 600. When the temperature monitoring unit 130 monitors that the temperature of the first low-voltage battery 301 is lower than a certain threshold, it means that the performance of the first low-voltage battery 301 is relatively greatly affected, and it needs to be heated first, and connects the on-board charging system OBC to the first voltage conversion unit 111, and the control unit 120 sends a control signal to the first voltage conversion unit 111, which controls the first low-voltage battery 301 to constantly charge and discharge between the on-board charging system OBC and the on-board charging system OBC according to the charging and discharging frequency and safe amplitude current determined by the first voltage conversion unit 111, and controls the gradual increase in the temperature of the first low-voltage battery 301, thereby realizing the rapid heating of the first low-voltage battery 301. In this manner, the on-board charging system OBC is used to heat the low-voltage battery, and the on-board charging system OBC, the high-voltage battery and the low-voltage battery share one voltage conversion unit, thereby simplifying the structure and reducing the complexity of the electrical device.

[0134] FIG. 12 shows another battery heating topology diagram, in which the battery heating system 100 of the electric device and the on-board charging system OBC are integrated. As shown in FIG. 12, the high-voltage battery 500 charges the first low-voltage battery 301 through the first voltage conversion unit 111. The on-board charging system OBC includes an AC outlet 803, a compensation unit 801, an AC-DC voltage conversion unit 802 and a second voltage conversion unit 112. In FIG. 12, the on-board charging system OBC and the heating system share a second voltage conversion unit 112, and can provide heating power to the first low-voltage battery 301 using the on-board charging system OBC as a power source, and the control unit 120 is connected to the second voltage conversion unit 112.

[0135] In a normal operating state, the high-voltage battery 500 charges the first low-voltage battery 301 through the first voltage conversion unit 111, and the first low-voltage battery 301 provides power to the low-voltage load 600. If the temperature monitoring unit 130 monitors that the temperature of the first low-voltage battery 301 is lower than a certain threshold, the performance of the first low-voltage battery 301 is relatively greatly affected, and it needs to be heated first, and the control unit 120 sends a control signal to the second voltage conversion unit 112, which controls the second voltage conversion unit 112 to continuously charge and discharge between the first low-voltage battery 301 and the on-board charging system OBC system according to the determined charging and discharging frequency and safe amplitude current, and gradually increase the temperature of the first low-voltage battery 301, thereby realizing the rapid heating of the first low-voltage battery 301. In this manner, the on-board charging system OBC is used to heat the low-voltage battery, and the on-board charging system OBC and the low-voltage battery share one voltage conversion unit, thereby simplifying the structure and reducing the complexity of the electrical device.

[0136] In some embodiments, the control unit 120 is further used to send a control signal to the voltage conversion unit when the temperature is less than a first preset threshold, and stop outputting the control signal when the temperature is equal to or greater than the first preset threshold.

[0137] The temperature monitoring unit 130 monitors the temperature, and when the temperature of the heated battery 300 is equal to or greater than a first preset threshold, it indicates that the temperature of the heated battery 300 can ensure the normal operation of the battery, and the control unit 120 stops outputting the control signal and stops heating the heated battery 300.

[0138] Naturally, when the temperature is relatively low, the internal resistance of the lithium battery is relatively large, so that when the battery heated by this method is heated at low temperature, the heating effect is relatively obvious. After the temperature of the lithium battery reaches a certain threshold, the internal resistance of the battery has already decreased significantly, so that when the battery heating system is used for heating, the effect is significantly decreased. Therefore, in this case, the control unit 120 can stop outputting the control signal and stop heating the battery 300 to be heated.

[0139] By monitoring the temperature of the heated battery 300 in real time, the heating process can be controlled in a timely manner based on the state of the heated battery 300, and when the heating effect is low, the heating process can be stopped in a timely manner, thereby saving energy.

[0140] In some embodiments, the battery heating system 100 includes an external heating source 400, and the control unit 120 is used to activate the external heating source 400 to heat the heated battery 300 when the temperature is less than a second preset threshold, and to turn off the external heating source 400 when the temperature is equal to or greater than a second preset threshold, and the first preset threshold is less than the second preset threshold.

[0141] As shown in Fig. 12, the battery heating system 100 further includes an external heating source 400, which includes heating by a heating film or PTC water heating, both of which are contact heat transfer with the surface of the battery, and the main advantages of which are simple heating structure and mature technology. The embodiment of this application combines two heating methods according to the characteristics of lithium batteries.

[0142] When the temperature is lower than the first preset threshold, the control unit 120 controls the voltage conversion unit to heat the battery to be heated 300, and at the same time starts the external heating source 400 to heat the battery to be heated 300. When the temperature is equal to or higher than the first preset threshold, the internal resistance of the battery has already been greatly reduced, so that the heating effect is greatly reduced due to frequent charging and discharging, in this case, the battery heating system stops heating the battery, but the temperature of the battery to be heated 300 has not reached the second preset threshold, in this case, the external heating source 400 continues to heat the battery to be heated 300 until the temperature of the battery to be heated 300 reaches the second preset threshold, in this case, the temperature of the battery to be heated 300 can be used normally, and the external heating source 400 can be cut off.

[0143] The embodiment of the present application combines the self-heating mode of the battery with the conventional heating mode by an external heating source to improve the heating effect of the heated battery and improve the heating efficiency.

[0144] As can be seen from the above, the battery heating system provided in the embodiments of the present application has a control unit that determines a safe amplitude current based on the charge / discharge frequency and charge transfer resistance of the voltage conversion unit, sends a control signal to the voltage conversion unit based on the charge / discharge frequency and the safe amplitude current, and the voltage conversion unit performs a boost or down process on the first voltage or the second voltage based on the control signal, thereby greatly improving the heating effect of the battery and improving the heating efficiency.

[0145] According to another aspect of the embodiment of the present application, there is further provided a battery heating method applied to the battery heating system provided by the above embodiment, which is specifically shown in FIG. The battery heating method provided by the embodiment of the present application includes: Step 1401 of acquiring the charging and discharging frequency of the voltage conversion unit; determining 1402 the charge transfer resistance of the heated battery 300 based on the charge / discharge frequency; calculating 1403 a safe amplitude current for the heated battery 300 based on the charge transfer resistance; and step 1404 of sending a control signal to the voltage conversion unit based on the safe amplitude current and the charge / discharge frequency, and adjusting the first voltage input to the heated battery 300 or the second voltage input to the power source 200 based on the control signal.

[0146] Here, the battery to be heated is electrically connected to a power source via a voltage conversion unit, and the power source can be in various forms, such as a high-voltage battery, a low-voltage battery in an electric device, or a power source provided after voltage conversion by an on-board charging system.

[0147] The above-mentioned embodiment of the present application determines a safe amplitude current based on the charge / discharge frequency and charge transfer resistance of the voltage conversion unit, sends a control signal to the voltage conversion unit based on the charge / discharge frequency and the safe amplitude current, and the voltage conversion unit performs a boost or down process on the first voltage or the second voltage based on the control signal, thereby significantly improving the heating effect of the battery and improving the heating efficiency.

[0148] In some embodiments, determining the charge transfer resistance of the heated battery based on the charge and discharge frequency includes obtaining a temperature of the heated battery and determining a charge transfer resistance of the heated battery based on the temperature and the charge and discharge frequency.

[0149] By using this method, the state of the battery being heated can be monitored in real time and the charge / discharge voltage can be corrected, thereby always providing the optimal heating effect to the battery being heated and greatly improving the heating efficiency.

[0150] In some embodiments, determining a charge transfer resistance of the heated battery based on the charge and discharge frequency includes determining a charge transfer resistance of the heated battery based on a charge state of the heated battery, the temperature, and the charge and discharge frequency, and calculating a safe amplitude current of the heated battery based on the charge transfer resistance includes calculating a lithium deposition potential of the heated battery and a safe amplitude current of the heated battery based on the charge transfer resistance.

[0151] The embodiments of the present application do not rely on the charge cut-off voltage and open circuit voltage set by the manufacturer, but obtain a safe amplitude current based on the equilibrium potential and charge transfer resistance of the graphite negative electrode, thereby maximally responding to the actual state of the battery being charged, breaking through the limitations of the cut-off voltage set by the manufacturer, and greatly improving the heating efficiency.

[0152] In some embodiments, calculating the safe amplitude current of the heated battery based on the charge transfer resistance includes: pre-storing a mapping table of the charge state, temperature, charge / discharge frequency, and safe amplitude current of the heated battery; and querying the mapping table of the safe amplitude current based on the charge state, temperature, and charge / discharge frequency of the heated battery to determine the safe amplitude current of the heated battery in a current state.

[0153] By setting a mapping table of the charge state of the battery to be heated, the temperature, the charging / discharging frequency and the safe amplitude current, the safe amplitude current of charging / discharging can be quickly obtained, and the heating efficiency is improved.

[0154] In some embodiments, adjusting the first voltage input to the heated battery or the second voltage input to the power source based on the control signal includes increasing or decreasing the first voltage or the second voltage within a first time period so as to reduce the charging current received by the heated battery below the safe amplitude current.

[0155] In some embodiments, adjusting the first voltage input to the heated battery or the second voltage input to the power source based on the control signal includes increasing or decreasing the first voltage or the second voltage within a second time period so as to reduce the discharge current output by the heated battery to less than the safe amplitude current.

[0156] In some embodiments, the method further includes adjusting a first voltage input to the heated battery or a second voltage input to the power source when the temperature is less than a first preset threshold, and stopping adjusting the first voltage input to the heated battery or the second voltage input to the power source when the temperature is equal to or greater than the first preset threshold.

[0157] The above method monitors the temperature of the battery being heated in real time, so that the heating process can be controlled in a timely manner based on the state of the battery being heated; when the heating effect is low, the heating process can be stopped in a timely manner, thereby saving energy.

[0158] In some embodiments, the method further includes activating an external heating source to heat the heated battery if the temperature is less than a second preset threshold, and shutting off the external heating source if the temperature is equal to or greater than a second preset threshold, the first preset threshold being less than the second preset threshold.

[0159] The embodiment of the present application combines the rapid heating mode with the conventional heating mode using an external heating source to improve the heating effect of the heated battery and improve the heating efficiency.

[0160] According to another aspect of the embodiment of the present application, there is further provided a power supply system including the battery heating system provided by the above embodiment, the battery heating system being used to heat a battery to be heated, and the heated battery being used to provide a power source.

[0161] According to another aspect of the embodiment of the present application, there is further provided an electric device including the above-mentioned power supply system, which is used to provide a power source. The electric device may be, but is not limited to, a mobile phone, a tablet, a laptop, an electric toy, an electric tool, a battery car, an electric car, a ship, a spacecraft, etc., where the electric toy may include a stationary or mobile electric toy, such as a game console, an electric car toy, an electric boat toy, and an electric plane toy, and the spacecraft may include an airplane, a rocket, a space shuttle, and a space capsule, etc.

[0162] Finally, it should be noted that the above embodiments are merely for illustrating the technical solutions of the present application, and are not intended to limit the same. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art may still modify the technical solutions described in the above embodiments or make equivalent substitutions to some of the technical features thereof, but such modifications or substitutions will not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions in the embodiments of the present application.

Claims

1. A battery heating system including a voltage conversion unit, a temperature monitoring unit and a control unit, The voltage conversion unit is electrically connected to a power source and a battery to be heated, and receives a first voltage input from the power source or a second voltage input from the battery to be heated; The control unit obtains the charge / discharge frequency of the voltage conversion unit and the charge state of the heated battery; the temperature monitoring unit is used to monitor the temperature of the heated battery and transmit the temperature to the control unit; The control unit pre-stores a mapping table of the charge state, temperature, charge / discharge frequency and safe amplitude current of the battery to be heated; The control unit is further used to query the mapping table of safe amplitude current based on the charge state, the temperature and the charge / discharge frequency of the heated battery, and determine the safe amplitude current of the heated battery in a current state; Sending a control signal to the voltage conversion unit according to the charge / discharge frequency and the safe amplitude current, the voltage conversion unit being used to perform a step-up or step-down process on the first voltage or the second voltage according to the control signal; A battery heating system comprising:

2. The voltage conversion unit is used for performing a voltage increase or decrease process on the first voltage or the second voltage within a first time, so as to make the charging current received by the heated battery smaller than the safe amplitude current. The battery heating system according to claim 1 .

3. The voltage conversion unit is used for performing a voltage increase or decrease process on the first voltage or the second voltage within a second time period, so as to make a discharge current outputted from the heated battery smaller than the safe amplitude current. The battery heating system according to claim 1 .

4. The control unit is further used for sending the control signal to the voltage conversion unit when the temperature is lower than a first preset threshold, and stopping output of the control signal when the temperature is equal to or higher than the first preset threshold. The battery heating system according to claim 1 .

5. An external heating source is included; The control unit is used to activate the external heating source to heat the heated battery when the temperature is less than a second preset threshold, and to turn off the external heating source when the temperature is equal to or greater than a second preset threshold, and the first preset threshold is less than the second preset threshold. The battery heating system according to claim 4 .

6. 1. A battery heating method in which a battery to be heated is electrically connected to a power source via a voltage conversion unit, comprising: Obtaining a charge / discharge frequency of the voltage conversion unit, a temperature of the heated battery, and a charge state of the heated battery; storing a mapping table of the charge state, temperature, charge / discharge frequency and safe amplitude current of the battery to be heated in advance; Querying the mapping table of safe amplitude current based on the state of charge, the temperature and the charge / discharge frequency of the heated battery to determine a safe amplitude current of the heated battery in a current state; Send a control signal to the voltage conversion unit according to the safe amplitude current and the charging / discharging frequency, and adjust a first voltage input to the heated battery or a second voltage input to the power source according to the control signal; Including, A battery heating method comprising:

7. Adjusting the first voltage input to the heated battery or the second voltage input to the power source based on the control signal includes: performing a step-up or step-down process on the first voltage or the second voltage within a first time period so as to reduce a charging current received by the heated battery below the safe amplitude current; The battery heating method according to claim 6 .

8. Adjusting the first voltage input to the heated battery or the second voltage input to the power source based on the control signal includes: performing a step-up or step-down process on the first voltage or the second voltage within a second time period so that a discharge current output from the heated battery is made smaller than the safe amplitude current; The battery heating method according to claim 6 .

9. The method comprises: adjusting a first voltage input to the heated battery or a second voltage input to the power source when the temperature is less than a first preset threshold, and stopping the adjustment to the first voltage input to the heated battery or the second voltage input to the power source when the temperature is equal to or greater than the first preset threshold. The battery heating method according to claim 6 .

10. The method comprises: further comprising activating an external heating source to heat the heated battery when the temperature is less than a second preset threshold, and shutting off the external heating source when the temperature is equal to or greater than the second preset threshold; the first preset threshold is less than the second preset threshold; The battery heating method according to claim 9 .

11. A power supply system including the battery heating system according to any one of claims 1 to 5, The battery heating system is used to heat a battery to be heated, The heated battery is used to provide a power source. A power supply system comprising:

12. An electric device including the power supply system according to claim 11, The power supply system is used to provide a power source.

1. An electrical device comprising:

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