A power battery heating device and a method for thermal management control

Abstract

The application relates to the technical field of power batteries, and discloses a power battery heating device and a heat management control method, the power battery heating device comprises a liquid-heat assembly, the liquid-heat assembly comprises a plurality of heating plates, a plurality of heat exchange flow channels for transmitting heat exchange medium are arranged in the width direction of the heating plate, the two ends in the length direction of the heating plate are respectively provided with a current collector which is in communication with the plurality of heat exchange flow channels, a heating wire is arranged on the heat exchange surface of the heating plate, and the heating power of the heating wire increases along the transmission direction of the heat exchange medium; under the premise that the existing liquid-heat structural design arrangement scheme is not changed, the heating compensation design is integrated, that is, the heating wire is arranged on the heat exchange surface of the heating plate, on one hand, the heating rate is improved, and on the other hand, since the temperature distribution trends of the liquid-heat assembly and the heating wire are opposite when the two work separately, the heating wire can also balance the temperature difference generated by the liquid-heat system heating.

Description

Technical Field

[0001] This invention relates to the field of power battery technology, and in particular to a power battery heating device and a method for thermal management control. Background Technology

[0002] Currently, liquid heating is generally used in power battery heating solutions. However, using liquid heating alone has the following problems:

[0003] Due to the limited flow channel structure and the accompanying gradient change in the temperature of the fluid medium, the temperature of the battery cells in different regions will inevitably be different. The temperature difference between the highest and lowest temperatures of the battery cells in the power battery is large, which affects the performance and lifespan consistency of the battery system.

[0004] In existing liquid thermal solutions, the heat transfer path is generally: heater - fluid medium - circulation pipeline - water-cooled plate - thermally conductive material - battery cell. On the one hand, the heat exchange efficiency of liquid-solid interface convective heat transfer is relatively low compared to solid-to-solid heat conduction; on the other hand, the heat transfer path involves multiple heat exchange links, and the thermal resistance of each link leads to a low overall comprehensive heat exchange efficiency, resulting in high energy consumption of the thermal management system. Furthermore, differences in the heat exchange links of different battery cells can also lead to temperature differences between individual battery cells, resulting in significant temperature variations.

[0005] During the heating process, the high-temperature fluid medium transfers heat through the liquid cooling plate and its thermally conductive material, resulting in a large temperature difference between different battery cells. At the same time, the heating rate of the low-temperature region is much lower than that of the heat exchange method that heats the battery cells in close contact. This leads to a low overall heating rate of the power battery during the heating process, which seriously affects the operation of the vehicle and the efficiency of fast charging. Summary of the Invention

[0006] The purpose of this invention is to provide a power battery heating device and a thermal management control method to solve or at least partially solve the technical problems mentioned in the background art.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a power battery heating device, including a liquid thermal assembly, the liquid thermal assembly including a plurality of heating plates, the heating plates having a plurality of heat exchange channels for transmitting heat exchange medium in the width direction, and the heating plates having a current collector at both ends in the length direction that is connected to the plurality of heat exchange channels.

[0009] The heat exchange surface of the heating plate is provided with heating wires, and the heating power of the heating wires increases along the transmission direction of the heat exchange medium.

[0010] Optionally, the heat exchange surface of the heating plate is attached to the side of the battery cell, and the heating power of the heating wire increases from one end of the side of the battery cell near the electrode post to the other end of the side of the battery cell.

[0011] Optionally, the heating power of the heating wire increases along the width direction of the heating plate;

[0012] The heating wire is a straight section on the initial end side near the heat exchange medium in the transmission direction, and a meandering section on the end side near the heat exchange medium in the transmission direction.

[0013] The straight segment is disposed along the length of the heating plate at the other end of the heat exchange surface of the heating plate, near the side of the battery cell.

[0014] The meandering segments are arranged along the width direction of the heating plate, and the meandering length of each meandering segment along the length direction of the heating plate increases from one end of the side of the battery cell near the electrode post to the other end of the side of the battery cell, and / or the width and / or spacing of each meandering segment along the width direction of the heating plate decreases from one end of the side of the battery cell near the electrode post to the other end of the side of the battery cell.

[0015] Optionally, the heating wire is periodically wavy along the length of the heating plate, with its period decreasing along the transmission direction of the heat exchange medium and / or its amplitude increasing along the transmission direction of the heat exchange medium.

[0016] Optionally, the heat exchange surface of the heating plate includes a first surface and / or a second surface of the heating plate; wherein the first surface and the second surface of the heating plate are two surfaces of the heating plate that are disposed opposite to each other;

[0017] The heating wires on the first surface and the second surface are connected to each other by a connecting section. The current collector is provided with a connecting groove on the side away from the heating plate. At least a portion of the connecting section is embedded in the connecting groove. The two ends of the connecting section are respectively connected to the heating wires on the first surface and the second surface.

[0018] Optionally, the heat exchange surface of the heating plate is provided with heating grooves, which are strip-shaped grooves distributed in a roundabout manner on the heat exchange surface;

[0019] The heating wire is covered with a flexible insulating layer and is interference-fitted into the heating groove.

[0020] Secondly, the present invention also provides a method for thermal management control of a power battery, which employs a power battery heating device as described above, comprising:

[0021] Continuously acquire temperature parameters of multiple individual cells in the power battery;

[0022] If the lowest cell temperature T of the power battery min Less than the preset heating start-up temperature threshold T limit A current is applied to the heating wire to heat the power battery;

[0023] When the lowest cell temperature T min The preset heating shut-off temperature threshold T is reached. close When T is reached, heating is stopped; where T close Greater than T limit ;

[0024] When the lowest cell temperature T min The preset heating shut-off temperature threshold T was not reached. close At that time, if the highest cell temperature T in the power battery is... max With the lowest cell temperature T min The difference ΔT is greater than the preset temperature difference threshold ΔT limit The current is stopped from being applied to the heating wire, and the heated heat exchange medium is transferred to the heat exchange channel of the heating plate to heat the power battery through the heat exchange surface of the heating plate.

[0025] Optionally, after stopping the current applied to the heating wire and transferring the heated heat exchange medium to the heat exchange channel of the heating plate, and heating the power battery through the heat exchange surface of the heating plate, the process further includes:

[0026] Determine the lowest cell temperature T min Does it show a gradual downward trend, or the highest cell temperature T max With the lowest cell temperature T min Does the difference ΔT show a gradually increasing trend?

[0027] If so, reapply current to the heating wire, and use the heating wire and the heating plate together to heat the power battery;

[0028] Among them, the lowest cell temperature T min The trend of gradual decline is manifested in the lowest cell temperature T. min_j ≤T min_j-△t <T limit T min_j Let T be the lowest cell temperature at time j. min_j-△T Δt represents the lowest temperature of a single battery cell at time j-Δt; Δt is the period between multiple times.

[0029] Maximum cell temperature T maxWith the lowest cell temperature T min The difference ΔT shows a gradually increasing trend, which is reflected in the lowest cell temperature ΔT. limit <△T j-△t <△T j , △T j T is the highest single-cell temperature at time j. max With the lowest cell temperature T min The difference, △T j-△t The highest single-cell temperature T at time j-Δt max With the lowest cell temperature T min The difference.

[0030] Optionally, the lowest cell temperature T of the power battery min Less than the preset heating start-up temperature threshold T limit Before heating the power battery, the process further includes applying current to the heating wire:

[0031] Based on the current operating status of the electrical equipment, set the heating start-up temperature threshold T of the power battery. limit Specifically, this includes:

[0032] When the electrical equipment is charging, set the heating start-up temperature threshold T of the power battery. limit For T limit1 ;

[0033] When the electrical equipment is in operation, set the power battery heating start-up temperature threshold T. limit For T limit2 ;

[0034] Among them, T limit1 =T limit2 +m; m takes the value of 2-5℃.

[0035] Optionally, the lowest cell temperature T of the power battery min Less than the preset heating start-up temperature threshold T limit Before heating the power battery, the process further includes applying current to the heating wire:

[0036] Determine the lowest cell temperature T min Is it lower than the preset heating start temperature threshold T? limit ;

[0037] If the lowest cell temperature T min Less than the preset heating start-up temperature threshold T limit The circuit resistance R between the two ends of the heating wire is detected, and it is determined whether the circuit resistance R is less than or equal to a preset resistance threshold R. min ;

[0038] The detection unit measures the circuit resistance R between the two ends of the heating wire and determines whether the circuit resistance R is less than or equal to a preset resistance threshold R. min Following that, it also includes:

[0039] If so, issue a heating circuit fault alarm;

[0040] If not, apply current to the heating wire to heat the power battery.

[0041] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0042] This solution integrates a heating compensation design without altering the existing liquid thermal structure layout. This involves placing heating wires on the heat exchange surface of the heating plate. This not only increases the heating rate but also, since the temperature distribution trends of the two components are opposite when they work alone, the heating wires can balance the temperature difference generated by the liquid thermal system, thus improving the temperature uniformity. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 A three-dimensional structural diagram of a power battery with a heating device provided in this embodiment;

[0045] Figure 2 for Figure 1 A schematic diagram of the exploded structure;

[0046] Figure 3 This is a partially exploded view of a power battery heating device provided in this embodiment;

[0047] Figure 4 This is a schematic diagram of the heat exchange surface of one of the heating plates of a power battery heating device provided in this embodiment;

[0048] Figure 5 for Figure 4 Enlarged view of some of the structures in the image;

[0049] Figure 6 This is a first-view perspective three-dimensional structural diagram of a group of heating units of a power battery heating device provided in this embodiment;

[0050] Figure 7 for Figure 6Enlarged view of some of the structures in the image;

[0051] Figure 8 This is a first-view perspective structural diagram of a grouped heating unit of a power battery heating device provided in this embodiment.

[0052] Figure 9 for Figure 8 Enlarged view of some of the structures in the image;

[0053] Figure 10 This is a schematic diagram of the structure of the heating plate of a power battery heating device provided in this embodiment;

[0054] Figure 11 This embodiment provides a circuit diagram of the heating circuit of a power battery heating device.

[0055] Figures 12-18 This is a schematic diagram of seven different arrangements of the heating wire provided in this embodiment;

[0056] Figure 19 This embodiment provides a modular architecture diagram of a liquid thermal component for a power battery heating device.

[0057] Figure 20 This embodiment provides a flowchart of a method for thermal management control of a power battery.

[0058] In the picture:

[0059] 10. Battery cell; 20. Liquid thermal module; 30. Heating circuit;

[0060] 21. Heating plate; 2101. Current collector; 2101-1. Connecting groove; 2102. Heat exchange channel; 211. Connecting pipe; 212. Heating groove; 2111. Inlet pipe; 2112. Outlet pipe; 22. Thermal pad; 23. Connecting pipe; 231. Medium inflow pipe; 232. First connecting pipe; 233. Second connecting pipe; 234. Medium outflow pipe; 31. Heating wire; 32. Connecting section;

[0061] 40. Relay switch; 50. BMS; 60. Power supply; 70. VCU; 80. TMS; 90. Circulating heat exchange system; 91. Water pump. Detailed Implementation

[0062] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0063] Example 1:

[0064] Please refer to Figure 1 and Figure 2 , Figure 1 This is a three-dimensional structural diagram of a power battery with a heating device provided in this embodiment. Figure 2 for Figure 1 A schematic diagram of the explosion structure.

[0065] The power battery with a heating device shown in this embodiment includes several groups of battery cells 10, and a liquid thermal assembly 20 is attached to at least one side of each group of battery cells 10.

[0066] Please continue to refer to this. Figure 3 and Figure 10 , Figure 3 This is a partially exploded view of a power battery heating device provided in this embodiment. Figure 10 This is a schematic diagram of the structure of the heating plate 21 of a power battery heating device provided in this embodiment.

[0067] Specifically, the liquid heat pump assembly 20 includes multiple heating plates 21, and multiple heat exchange channels 2102 for transferring heat exchange medium are provided in the heating plates 21 along their width direction. At both ends of the heating plates 21 along their length direction, there are current collectors 2101 that are connected to the multiple heat exchange channels 2102.

[0068] Heating wires 31 are provided on the heat exchange surface of the heating plate 21, and the heating power of the heating wires 31 increases along the transmission direction of the heat exchange medium.

[0069] In this embodiment, the heating wire 31 serves as a heating compensation element, and its wiring density increases along the transmission direction of the heat exchange medium. The denser the heating wire 31, the higher the heating efficiency. When the heating plate 21 is turned on for heating alone, the temperature of the heat exchange surface of the heating plate 21 changes in a gradient along the flow direction of the heat exchange medium. The temperature is higher closer to the inlet. Therefore, after the heating plate 21 has been working alone for a period of time, the battery cells 10 near the inlet will heat up faster.

[0070] Since the wiring density of the heating wire 31 increases along the transmission direction of the heat exchange medium, the temperature near the inlet is lower than the temperature near the outlet. The temperature distribution trends of the two heating methods, heating wire 31 and liquid heating, are opposite. At this time, using the heating wire 31 and heating plate 21 to work independently can balance the temperature difference caused by their individual heating, which is conducive to further reducing the temperature difference. On the other hand, using two heating methods that compensate for each other's temperature is also conducive to reducing the energy consumption of the entire heating system.

[0071] Therefore, without changing the existing liquid thermal structure design and layout, this solution improves the heating rate or heating efficiency through integrated heating compensation design. On the other hand, it can also balance the temperature difference generated by the liquid thermal system, which helps to reduce the energy consumption of the entire heating system.

[0072] For details, please refer to Figure 2 The heat exchange surface of the heating plate 21 includes the first surface of the heating plate 21 ( Figure 2 The first and second surfaces of the heating plate 21 are two surfaces of the heating plate 21 that are arranged opposite to each other.

[0073] The heat exchange surface of the heating plate 21 is also covered with a thermally conductive pad 22, that is, the thermally conductive pad 22 is disposed between the heating plate 21 and the battery cell 10, thereby improving the heat conduction efficiency. The heating plate 21 is wavy.

[0074] like Figure 1 As shown, the thermal pad 22 is made of thermally conductive material, and the heat from the heat exchange surface of the heating plate 21 can be conducted to the battery cell 10 through the thermal pad 22. When the battery cell 10 is a cylindrical battery, in order to increase the thermal contact area, the heating plate 21 is wavy and the thermal pad 22 is also wavy. The heating plate 21 and the thermal pad 22 are attached to each other. Furthermore, this wavy structure forms several arc-shaped grooves on the heat exchange surface of the heating plate 21 that match the cylindrical surface of the battery cell. This not only ensures an increased heat exchange area but also plays a role in shaping and buffering the battery cell 10 to a certain extent.

[0075] Please continue to refer to this. Figure 4 and Figure 5 , Figure 4 This is a schematic diagram of the heat exchange surface of one of the heating plates 21 in a power battery heating device provided in this embodiment. Figure 5 for Figure 4 Enlarged view of part of the structure.

[0076] Specifically, the heat exchange surface of the heating plate 21 is provided with heating grooves 212, which are strip-shaped grooves distributed on the heat exchange surface;

[0077] The heating wire 31 is covered with a flexible insulating layer and is embedded in the heating groove 212 with an interference fit.

[0078] Figure 4 and Figure 5 This illustrates one arrangement of the heating groove 212 or heating wire 31, from Figure 4 or Figure 5 As can be seen from the arrangement of the heating wires 31, the right section of the heating wires 31 is arranged in a meandering pattern, which results in a denser arrangement and higher heating power, while the left section of the heating wires 31 is arranged in a straight line. By adjusting the length of the heating wires 31 in the longitudinal direction, the length of the heating wires 31 increases in the direction of heat exchange medium transmission. In other embodiments, the heating power can be increased along the length of the heating plate 21 by adjusting the coil turn density of the heating wires 31. In another embodiment, the heating power of the heating wires 31 can also be increased along the direction of heat exchange medium transmission by simultaneously adjusting both the length of the heating wires 31 and the coil turn density.

[0079] Considering that the temperature of the overcurrent area of ​​the top tab of the battery cell 10 will be relatively high and the heat required in the bottom area will be relatively large, the heating wire 31 can be set in the area below 1 / 2 of the battery cell 10. In addition, since the bottom of the battery cell 10 is generally a metal support and the top is air, the heat conduction at the bottom of the battery cell 10 is relatively large, so the temperature is relatively low and the compensation required is relatively large.

[0080] In this embodiment, the heat exchange surface of the heating plate 21 is attached to the side of the battery cell 10. Therefore, the heating power of the heating wire 31 should increase from the end of the side of the battery cell 10 near the electrode post to the other end of the side of the battery cell 10 to achieve uniform temperature of the individual battery cell 10 in the width direction of the heat exchange surface of the heating plate 21.

[0081] As an optional implementation, the heating power of the heating wire 31 increases progressively along the length of the heating plate 21 and / or along the width of the heating plate 21, which can be set as needed. It should be noted that in this embodiment, a single heating wire 31 can be arranged on the heat exchange surface of the heating plate 21. By changing one or more of the arrangement position, shape, density, or coil turn density of the heating wire, the heating power can be varied, facilitating the control of the heating wire 31. The arrangement shape includes horizontal stripes along the length direction, vertical stripes along the width direction, wavy shapes, etc. The arrangement density includes the number of heating wires along the length direction, the number of heating wires along the width direction, the length of the heating wires along the length direction, the width along the width direction, the amplitude, the period, and the spacing between adjacent heating wires, etc.

[0082] Please refer to Figures 12-18Given different application scenarios or user needs, Figures 12-18 Other arrangements of the heating wire 31 are also shown, as follows;

[0083] Optional implementation method one:

[0084] like Figure 12 As shown, the heating power of the heating wire 31 increases along the transmission direction of the heat exchange medium, and the heating power of the heating wire 31 increases from the side of the battery cell 10 near the electrode post (to be close to) Figure 12 From the upper end of the width direction of the heating plate 21 to the other end of the side of the battery cell 10 (to be close to) Figure 12 The width of the middle heating plate 21 increases from its lower end in the width direction, specifically as follows:

[0085] The heating wire 31 has a straight section near the initial end of the heat exchange medium's transmission direction, and a meandering section near the end of the heat exchange medium's transmission direction. This means the heating power at the left end of the heating plate 21 is less than the heating power at the right end, thus achieving an increase in heating power along the heat exchange medium's transmission direction. The arrangement density of the heating wires near the end of the heat exchange medium's transmission direction is greater than the arrangement density near the initial end. By changing the arrangement density, an increase in heating power from the initial end to the end of the heat exchange medium's transmission direction is achieved.

[0086] The straight segment is set along the length of the heating plate 21 at the other end of the heat exchange surface of the heating plate 21 near the side of the battery cell 10. In this way, within the length range of the heating wire 31, along the width direction of the heating plate 21, the heating wire 31 at the end near the electrode of the battery cell 10 is not provided with a heating wire 31, so that the heating power at the end near the electrode is less than the heating power at the other end near the side of the battery cell 10, thereby achieving an increase in heating power.

[0087] The heating wire 31 is arranged in a roundabout manner, and the interval of each roundabout segment along the width direction of the heating plate 21 increases from one end of the side of the battery cell 10 near the electrode post to the other end of the side of the battery cell 10, so that the heating power of the heating wire 31 increases in the width direction of the heating plate 21.

[0088] The heating wire 31 is arranged in a roundabout way, which can balance the heat exchange deviation between multiple channels in the width direction, avoid the heating area concentration, and facilitate the equalization of different temperature gradients.

[0089] Optional Implementation Method Two:

[0090] like Figure 13 As shown, as Figure 12One modified scheme involves arranging at least two detour segment groups at intervals along the length direction. Each detour segment group includes several detour segments, and the length of the detour segments in each detour segment group increases along the transmission direction of the heat exchange medium, thereby achieving an increase in heating power along the length direction. This enhances the gradient of heating power variation along the length direction, enabling precise heating.

[0091] In each detour section group, the interval of the detour sections along the width direction of the heating plate 21 increases from one end of the side of the battery cell 10 near the electrode post to the other end of the side of the battery cell 10, so as to improve the gradient change of heating power in the width direction and improve heating accuracy.

[0092] It should be noted that, Figure 13 A straight section of heating wire 31 is set near the inlet of the heat exchange medium. In order to improve the gradient of heating power change in the width direction, a group of detour sections can be used instead of the straight section. In this way, multiple detour sections can be set at intervals in the length direction. The length of the detour section in each detour section group increases along the transmission direction of the heat exchange medium, so as to achieve the increase of heating power in the length direction and the width direction, while improving the coverage of heating wire 31 and ensuring heating efficiency.

[0093] Optional Implementation Method Three:

[0094] like Figure 14 As shown, the heating plate 21 is covered with heating wires 31 along its length. The heating wires 31 are arranged in a meandering manner throughout. Similarly, the spacing between the heating wires 31 in the width direction decreases from top to bottom to achieve an increase in heating power in the width direction.

[0095] At this point, along the length direction, the heating power of each meandering section can be increased by adjusting the coil turn density of the heating wire 31. In this way, heating wires 31 can be arranged in multiple heat exchange channels 2102 along their lengths, improving the coverage of heating wires 31 and increasing heating efficiency.

[0096] Optional Implementation Method Four:

[0097] like Figure 15 As shown, the meandering segments are arranged along the width direction of the heating plate 21. The meandering length of each meandering segment along the length direction of the heating plate 21 increases from one end of the side of the battery cell 10 near the electrode post to the other end of the side of the battery cell 10. This allows the heating power of the heating wire 31 to increase along the length direction of the heating plate 21. Compared with meandering segments of equal length, this improves the gradient of heating power change along the length direction, while ensuring the coverage of the heating wire 31 and improving heating efficiency.

[0098] Meanwhile, in the width direction, the spacing between the meandering segments decreases from top to bottom, as shown in the reference. Figure 15Since a > b, the heating power increases in the width direction.

[0099] It should be noted that multiple detour segment groups can also be set up at this time, with each detour segment group containing detour segments of increasing length from top to bottom. This will not be elaborated upon here.

[0100] Optional implementation method five: such as Figure 16 As shown, the heating wire 31 is periodically wavy along the length of the heating plate 21, and its period decreases along the transmission direction of the heat exchange medium.

[0101] Specifically, such as Figure 16 As shown, Figure 16 The diagram illustrates an arrangement where the heating wire 31 is arranged in a square wave shape. In this embodiment, the heating wire 31 is arranged in a periodic square wave shape along the length direction of the heating plate 21, with its period decreasing along the transmission direction of the heat exchange medium. This allows the heating power to increase along the length direction. Furthermore, compared to a meandering or straight section, the heating wire 31 can be distributed simultaneously on multiple heat exchange channels 2102, achieving heating uniformity between different heat exchange channels 2102. This avoids heating a single heat exchange channel 2102 to the point that the temperature difference between the heat exchange channels 2102 increases, thus ensuring the uniformity of the side temperature of the individual battery cell 10.

[0102] Optional Implementation Method Six:

[0103] Specifically, such as Figure 17 As shown, Figure 17 This illustrates an arrangement where the heating wire 31 is arranged in a sinusoidal wave shape. In this embodiment, the heating wire 31 is periodically wavy along the length of the heating plate 21, with its period decreasing along the heat exchange medium's transmission direction and its amplitude increasing along the same direction. In this way, along the length direction, not only is the heating power increased by decreasing the period, but also by increasing the amplitude, thereby further improving the adjustment accuracy of the heating power of the heating wire 31 while ensuring that the heating wire 31 can cover a suitable position.

[0104] It should be noted that, while keeping the cycle constant, the amplitude can be increased to achieve an increase in heating power. No restrictions are imposed here.

[0105] Optional Implementation Method Seven:

[0106] like Figure 16 As shown, in order to achieve an increase in heating power in the width direction, for the wavy heating wire 31, the amplitude near the end of the electrode is smaller than the amplitude near the side of the battery cell 10 in each cycle, thereby increasing the power of the heating wire 31 located below and realizing a variable power layout.

[0107] More specifically, as a supplementary explanation of the wavy arrangement, such as Figure 18 As shown, taking a square wave as an example, when the heating wire 31 is arranged in a wave-like structure, the shapes of two adjacent waveforms can be the same along the length of the heating plate 21. The waves of the wave-like structure do not need to be arranged in a sequentially decreasing manner. Figure 18 As shown, the first square wave has the longest period, the second and third square waves have the same period, but the period of the second square wave is shorter than that of the first square wave, the fourth, fifth and sixth square waves have the same period, but the period of the fourth square wave is shorter than that of the second square wave, and so on.

[0108] It is understandable that there are many other variations in the arrangement of the heating wire 31, which cannot be exhaustively listed, so they will not be described in detail here.

[0109] Please refer to Figure 6 , Figure 6 This is a first-view perspective three-dimensional structural diagram of a group of heating units of a power battery heating device provided in this embodiment.

[0110] Specifically, the multiple heating plates 21 include multiple groups of heating units, and the group of heating units includes two adjacent heating plates 21; the first surface and the second surface of the two adjacent heating plates 21 are both heat exchange surfaces;

[0111] The two adjacent heating plates 21 include a first heating plate and a second heating plate; the current collector 2101 includes a first current collector disposed at a first end of the first heating plate, a second current collector disposed at a second end of the first heating plate, a third current collector disposed at a first end of the second heating plate, and a fourth current collector disposed at a second end of the second heating plate.

[0112] The first current collector is connected to the third current collector through the first connecting pipe 232; the second current collector is connected to the fourth current collector through the second connecting pipe 233;

[0113] The first surface of the first collector is also connected to an inlet pipe 2111, which is sleeved with a medium inflow pipe 231; the first surface of the second collector is also connected to an outlet pipe 2112, which is sleeved with a medium outflow pipe 234.

[0114] It should be noted that, as Figure 1 As shown, the heating plate 21 can be disposed between two rows of battery cells 10. In this case, both the first and second surfaces of the heating plate 21 can be configured as heat exchange surfaces. However, the heating plate 21 can also be disposed on the outer side of the outermost row of battery cells 10. In this case, only the surface of the heating plate 21 closest to the battery cell 10 needs to be configured as a heat exchange surface.

[0115] Please refer to Figures 6 to 9 , Figure 6 This is a first-view perspective three-dimensional structural diagram of a group of heating units in a power battery heating device provided in this embodiment. Figure 7 for Figure 6 Enlarged view of some of the structures in the image. Figure 8 This is a first-view perspective perspective of the grouped heating unit of a power battery heating device provided in this embodiment. Figure 9 for Figure 8 Enlarged view of part of the structure.

[0116] For details, please refer to Figure 9 The heating wires 31 on the first and second surfaces are interconnected by connecting sections 32. A connecting groove 2101-1 is provided on the side of the current collector 2101 away from the heating plate 21. At least a portion of the connecting section 32 is embedded in the connecting groove 2101-1, and both ends of the connecting section 32 are connected to the heating wires 31 on the first and second surfaces, respectively. The connecting section 31 can be a non-heating section to reduce overall power consumption and save energy. For example, the connecting groove 2101-1 can be provided on the second current collector, or on the third or fourth current collector, depending on the requirements.

[0117] More specifically, in a group heating unit, the heating wire 31 includes four heating resistors connected in series. The four heating resistors are respectively installed in the heating grooves 212 on the four heat exchange surfaces of the group heating unit, thereby realizing the series connection of the heating wires 31, which is convenient for control and management.

[0118] The surface of the current collector is provided with a first connecting groove, the two ends of which are respectively connected to the heating grooves 212 on the two heat exchange surfaces of the heating plate. One end of the first connecting groove is connected to the heating groove 212, and the other end is connected to the connecting groove 2101-1, thereby guiding the heating wire 31 located on the heat exchange surface and the heating wire 31 located in the connecting groove 2101-1 to connect with each other. When the current collector 2101 is the second current collector, the setting of the first connecting groove and the connecting groove allows the heating wire 31 to bypass the current collector, realizing the connection of the heating wires on the first surface and the second surface. When the current collector 2101 is the third current collector, the setting of the first connecting groove and the connecting groove allows the heating wire to bypass the current collector, realizing the connection of the heating wires between two adjacent heating plates 21, while ensuring that the heating wire 31 can be snapped into the current collector, improving stability and avoiding the detachment of the heating wire 31 due to vibration, aging and other problems. The connecting groove 2101-1 can be set to a folded state to improve the snapping stability.

[0119] Please refer to Figure 11 , Figure 11 A circuit diagram of the heating circuit 30 of a power battery heating device provided in this embodiment; Figure 11 The high-voltage and low-voltage wire harnesses shown here simply represent that they are different circuit loops. The operating voltage of the circuit loop containing the high-voltage wire harness is higher than that of the circuit loop containing the low-voltage wire harness.

[0120] Specifically, the two ends of the heating wire 31 are electrically connected to the relay switch 40 and the power supply 60 through wires, and the heating wire 31, the relay switch 40 and the power supply 60 constitute the heating circuit 30.

[0121] The control coil of the relay switch 40 is also electrically connected to a BMS (Battery Management System) 50. The BMS 50 can provide operating current to the control coil, so that the relay switch 40 can be closed and turned on.

[0122] It should be noted that there can be many heating plates 21 in the power battery. The number and position of the heating plates 21 need to match the layout structure of the battery cells 10. Each heating wire 31 can be set independently or in series. As a preferred implementation, all heating wires 31 are connected in series. On the one hand, since the current is equal in the series connection, it can be ensured that the current flowing through each heating wire 31 is the same and the heating power is the same. On the other hand, it is beneficial to electrical safety design. That is, when a section of heating wire 31 is disconnected, the entire heating compensation system will also be in a disconnected state, preventing the problem of large temperature difference in the battery cells 10 caused by the operation of local heating wires 31.

[0123] For example, corresponding to a group of heating units, if the current supplied by the power supply 60 flows in the direction of... Figure 7 and Figure 9 As shown by the arrow, the current flows in from the starting point A, passes sequentially through the heating resistors on the first surface of the first heating plate, the heating resistors on the second surface of the first heating plate, the heating resistors on the second surface of the second heating plate, and the heating resistors on the first surface of the second heating plate, and then flows out from the ending point B.

[0124] Points A and B are electrically connected to BMS50 via a low-voltage wiring harness. This means that BMS50 can determine whether the entire heating circuit 30 is intact by monitoring the resistance value between points A and B.

[0125] In this embodiment, it can be understood that the "heat exchange medium" can be a fluid medium such as water or coolant. Its main purpose is to exchange heat with the battery cell 10 through heat exchange. The "heat exchange medium" can also be selected according to the user's specific application requirements, which will not be elaborated here.

[0126] Example 2:

[0127] Please refer to Figure 19 and Figure 20 , Figure 19 This is a modular architecture diagram of the liquid thermal component of a power battery heating device provided in this embodiment. Figure 20 This embodiment provides a flowchart of a method for thermal management control of a power battery.

[0128] This embodiment provides a method for thermal management control of a power battery, including:

[0129] S100. Based on the current operating status of the electrical equipment, set the heating start-up temperature threshold T of the power battery. limit .

[0130] In this embodiment, the electrical device is an electric vehicle. In S100, if the electric vehicle is in a charging state, T is set. limit For T limit1 If the electric vehicle is charging, then set T. limit For T limit2 ;T limit2 >T limit As a specific implementation method, T limit =T limit2 +m; m takes a value of 2~5℃;

[0131] The primary purpose of setting different thresholds is to ensure that the temperature of the power battery is controlled within a reasonable operating range, ensuring that the power battery reaches the temperature required to perform its function. In other words, the performance of the power battery is constrained by temperature. Secondly, energy saving needs to be considered, such as reducing heating time or improving heat exchange efficiency. Based on the battery system's capacity and vehicle speed requirements, most vehicles currently have a lower motor discharge power (which can also be understood as the battery charging rate) during driving than the charging power (rate) during charging. The power demand on individual battery cells during the discharge phase is relatively smaller than during the charging phase, therefore the threshold for the thermal management activation temperature during the heating process is also relatively lower. This helps to improve the vehicle's cruising range and meet the temperature requirements of the power battery's discharge power. If the charging power and discharging power are the same, the power battery will not be able to remain fully charged because it loses some energy during discharge. To fully charge and maintain a fully charged power battery, the charging power is usually higher than the discharging power.

[0132] During the discharge phase, the discharge rate of the power battery is lower than that during the charging phase. Under the same SOC, the required battery temperature varies depending on the charge / discharge rate. Under the same SOC and battery type, the charge / discharge rate or power requirement of the power battery directly determines the temperature requirement for the individual battery cells. For example, for a battery cell with an SOC of 50%, the maximum charge / discharge rate can reach 0.2C at -20℃. If it is required to reach 0.3C, the temperature of the battery cell must be at least -15℃. This shows that different charging rate requirements lead to different temperature requirements for the battery cells. At low temperatures, the higher the charge / discharge rate, the higher the temperature. Therefore, the heating threshold is higher during the discharge phase, prioritizing heating.

[0133] In this way, in low-temperature environments, for a power battery in the same state to achieve a relatively high rate of performance during the charging phase, a higher temperature is required to ensure that it can perform to its full potential. Therefore, the heating needs to be turned on in advance during the charging phase, so the heating threshold needs to be larger to ensure the effective operation of the power battery during the charging phase while driving.

[0134] Meanwhile, during the charging phase, the heating system draws power from the external charging equipment rather than the battery system, so it does not consume battery power. The heating activation temperature threshold during charging should be higher to improve energy utilization.

[0135] S200 continuously acquires temperature parameters of multiple individual cells in the power battery.

[0136] S300, Determine the lowest single-cell temperature T of the power battery. min Is it lower than the preset heating start temperature threshold T? limit If yes, execute S400; otherwise, return to S100.

[0137] If the lowest cell temperature T of the power battery min Less than the preset heating start-up temperature threshold T limit This means that the battery cell 10 of the power battery needs to be heated, that is, the temperature of the battery cell is lower than T. limit Heating is then performed. In this embodiment, heating circuit 30 is preferentially used for heating. The lowest single-cell temperature T of the power battery is... min The current lowest cell temperature T min By obtaining the temperature parameters of multiple individual battery cells in real time, the heating circuit 30 and the liquid thermal component 20 can be controlled to achieve precise control.

[0138] It should be noted that the reason for prioritizing heating circuit 30 is as follows:

[0139] On the one hand, the heating wire 31 in the heating circuit 30 is embedded in the heating groove 212 outside the heating plate 21, and the heating wire 31 can directly contact the battery cell 10. Compared with the liquid heating method, the heating circuit 30 has higher heating efficiency through the heating wire 31. On the other hand, since the heating power required by the battery cell 10 is relatively small when the temperature is just below the critical threshold, the heating circuit 30 with higher heating efficiency can quickly ensure that the temperature of the battery cell rises above the heating start temperature threshold, thereby reducing the energy consumption of the heating system.

[0140] S400: Detect the circuit resistance R between the two ends of the heating wire and determine whether the circuit resistance R is less than or equal to the preset R. min If yes, execute S401; otherwise, execute S402.

[0141] In S400, after the opening conditions of the heating circuit 30 are met, the BMS50 needs to detect the resistance value across the heating circuit 30. For example, in this embodiment, the heating circuit 30 forms a group of heating units, and the two ends of the heating circuit 30 are... Figure 7 Points A and B are shown in the diagram;

[0142] It should be emphasized that points A and B are both located between the relay switch 40 and the heating wire 31 and are close to the heating wire 31. Points A and B are electrically connected to the BMS50 through low-voltage wiring harnesses. This ensures that the BMS50 can detect the status of the heating circuit 30 even when the relay switch 40 is open.

[0143] The judgment condition is as follows: If R ≤ R min If this occurs, it indicates a short circuit or partial short circuit in the heating wire 31 of the heating circuit 30. The BMS50 will report a circuit fault in the heating circuit 30 to the VCU (Vehicle Control Unit VCU) 70, where R... min =R0*λ, where R0 is the rated resistance of heating circuit 30, and λ is the resistance lower limit coefficient, which is generally taken as 0.02 to 0.1; otherwise, it indicates that the heating wire circuit is well connected, and the BMS controls the high-voltage relay to close and open heating circuit 30.

[0144] Therefore, R > Rmin is set as the condition for the heating circuit 30 to be turned on. It should be noted that if part of the heating wire 31 is disconnected, the BMS50 cannot detect the circuit resistance R of the heating circuit 30. In this case, the BMS50 will also issue an alarm signal, but this situation rarely occurs, so it will not be elaborated here.

[0145] Heating with heating wire 31 offers high energy efficiency. However, regardless of the heating method used, an increase in temperature difference occurs at the start of heating. In this design, the heating system includes a liquid thermal component 20 and a heating circuit 30. If liquid thermal heating is used alone, the high-temperature medium's flow path will inevitably cause the temperature of the battery cells 10 near the inlet to rise while the temperature of the battery cells 10 at the outlet will remain relatively low. Continuous heating will further increase this temperature difference. Similarly, if heating with heating wire 31 is used alone, its heating power increases along the direction of heat exchange medium transmission due to the special wiring structure described above. This will inevitably cause the temperature of the battery cells 10 at the front to be lower while the temperature of the battery cells 10 at the back to be higher, thus increasing the temperature difference (but in the opposite direction to liquid thermal heating). Only if all battery cells 10 are heated uniformly, i.e., heat exchange is equal at all locations, will the temperature difference not increase. However, current structural space limitations prevent this. Therefore, to save energy and shorten heating time during startup, we use the more efficient heating wire 31 for initial heating.

[0146] S401 is the current applied to the heating wire to heat the power battery.

[0147] like Figure 11 As shown, when no fault is found in the heating circuit 30, the BMS50 will control the relay switch 40 to close and conduct, and the power supply 60 will connect the heating wire 31 to apply current to the heating wire 31 to heat the power battery.

[0148] S402, Issues a heating circuit fault alarm.

[0149] Following S401, it also includes:

[0150] S500, Determine the lowest cell temperature T min Has the preset heating shut-off temperature threshold T been reached? close If yes, execute S501; otherwise, execute S502.

[0151] In S500, the heating off temperature threshold is different from the heating on temperature threshold. Generally speaking, when setting the temperature threshold, the heating off temperature threshold should be slightly higher than the heating on temperature threshold to avoid the heating circuit 30 from frequently switching on and off.

[0152] S501, Stop heating.

[0153] When the lowest cell temperature T min The preset heating shut-off temperature threshold T is reached. close When heating stops, including:

[0154] If the current heating circuit 30 is heating, the relay switch 40 is disconnected by controlling the BMS50; if the current heating component 20 is liquid heat exchanger, the water pump 91 is shut off by the VCU70, and the circulating heat exchange system 90 stops transferring heat exchange medium to the heat exchange channel 2102.

[0155] S502. Determine the highest cell temperature T in the power battery. max With the lowest cell temperature T min Is the difference greater than the preset temperature difference threshold ΔT? limit If yes, proceed to step S600; otherwise, return to step S402.

[0156] As mentioned above, when the heating circuit 30 is turned on alone, there will be uneven heating, that is, the temperature of the front battery cell 10 is lower and the temperature of the rear battery cell 10 is higher. Therefore, in this embodiment, the BMS50 will continuously monitor the temperature parameters of the battery cells of the power battery, and when the temperature difference is large (greater than the preset temperature difference threshold), the heating circuit 30 will be turned off and the liquid heat pump component 20 will be used to heat the cells separately in order to balance the temperature difference problem generated during the heating phase of the heating circuit 30.

[0157] As a preferred implementation method, different temperature difference thresholds ΔT can also be set according to the current operating status of the electrical equipment. limit For example, △T limit1 The temperature difference threshold for the charging state; △T limit2 The temperature difference threshold for the discharge state; ΔT limit1 <△T limit2 ;

[0158] The main reason is that the temperature difference requirements during the discharge process are relatively lenient, while the temperature difference requirements during driving are relatively lenient compared to the charging process. This is mainly because the discharge rate during driving is relatively small, so the temperature range required for individual battery cells to achieve consistent performance is relatively wide.

[0159] S600: Disconnect the heating circuit and start the liquid heat exchanger assembly. Control the high-temperature heat exchange medium to continuously flow through the heat exchange channel and heat the power battery through the heat exchange surface of the heating plate.

[0160] After the liquid thermal component 20 is activated, the circulating heat exchange system 90, driven by the water pump 91, can circulate the heated heat exchange medium through the heat exchange channel 2102 of the heating plate 21, and heat the power battery through the heat exchange surface of the heating plate 21.

[0161] In this scheme, the TMS80 mainly uses a PTC (Positive Temperature Coefficient) heater, which heats the heat exchange medium and delivers it to the heating plate 21 through the water pump 91 and circulation pipeline.

[0162] Following the S600, it also includes:

[0163] S700, Determine the lowest cell temperature T min Does it show a gradual downward trend, or the highest cell temperature T max With the lowest cell temperature T min Does the difference ΔT show a gradually increasing trend? If yes, return to S400; if no, return to S500.

[0164] In certain special circumstances, such as extremely cold weather, the heating power of a liquid thermal system alone may be insufficient, causing the lowest battery cell temperature to gradually decrease, or the highest battery cell temperature T to remain below the lowest level. max With the lowest cell temperature T min The difference ΔT shows a gradually increasing trend. At this time, two heating systems need to work together, that is, the liquid heat component 20 and the heating circuit 30 are activated at the same time to heat the battery cell 10, and the temperature rise rate of the battery cell 10 of the power battery will be further improved.

[0165] Specifically, the lowest cell temperature T min The trend of gradual decline is manifested as follows:

[0166] Minimum cell temperature T min_j ≤T min_j-△t <T limit T min_j Let T be the lowest cell temperature at time j. min_j-△T The lowest cell temperature at time j-Δt; passing through the lowest cell temperature T min The downward trend can accurately determine the heating status of the heating device, thereby achieving precise heating based on the status of the power battery.

[0167] Maximum cell temperature T max With the lowest cell temperature T min The difference ΔT shows a gradually increasing trend, which is manifested as follows:

[0168] Minimum cell temperature ΔT limit <△T j-△t <△T j , △T j T is the highest single-cell temperature at time j. max With the lowest cell temperature T min The difference, △T j-△t The highest single-cell temperature T at time j-Δt max With the lowest cell temperature T min The difference;

[0169] Where △t is the cycle time for BMS50 to calculate the temperature difference.

[0170] Based on the temperature T of the battery cell max With the lowest cell temperature T min The trend of the difference, compared to only using the lowest cell temperature T min The downward trend adds a dimension to the judgment, enabling accurate judgment even when the lowest battery cell temperature is inaccurate, thus improving the accuracy and applicability of the judgment.

[0171] In this embodiment, a reasonable heating strategy can be formulated based on the actual usage of the power battery and the dynamically detected temperature of the battery cells. This not only takes into account the different heating requirements under charging and discharging states, allowing for the specification of strategies according to different requirements, balancing heating efficiency and heating energy consumption, but also accurately judges the extreme cold conditions of the power battery by dynamically detecting the temperature of the battery cells in real time, thereby adaptively increasing the heating power and avoiding the impact of extreme cold on the power battery.

[0172] In this embodiment, without changing the existing thermal management layout design structure and its space, the heat exchange efficiency is improved by adding a heating circuit 30 for heating compensation, which is beneficial to improving the temperature rise rate of the battery cell 10.

[0173] In the present invention, the BMS electrical principle control circuit scheme can realize the real-time monitoring of the heating wire circuit status of the heating compensation system, and accurately determine its reliability and safety before the heating compensation system is turned on.

[0174] In low-temperature environments, this solution sets different heating activation thermal management strategies based on the actual operating conditions of the vehicle and its different requirements for the performance of the battery cell system. This is closer to the actual use conditions of the vehicle, improves heating efficiency, and saves energy.

[0175] Based on the influence trend of heating circuit 30 and liquid thermal component 20 on the temperature distribution of battery cells, a reasonable heating control strategy was designed. By first heating through heating circuit 30 and then heating through liquid thermal component 20, the temperature rise of battery cell 10 is achieved while ensuring the consistency of temperature difference of battery cell, which is beneficial to improving the battery system life.

[0176] This solution also takes into account the heating activation thermal management strategy under special extreme environmental conditions, and realizes dynamic temperature difference balancing during the heating process under special extreme environmental conditions. This solves the problem of temperature consistency throughout the battery life cycle, which is something that cannot be achieved by a single heating system at present.

[0177] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention 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 of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A power battery heating device, comprising a liquid thermal assembly (20), characterized in that, The liquid thermal assembly (20) includes multiple heating plates (21), and the heating plates (21) are provided with multiple heat exchange channels (2102) for transmitting heat exchange medium in the width direction. The heating plates (21) are provided with current collectors (2101) at both ends in the length direction, which are connected to the multiple heat exchange channels (2102). The heat exchange surface of the heating plate (21) is provided with a heating wire (31), and the heating power of the heating wire (31) increases along the transmission direction of the heat exchange medium. The heat exchange surface of the heating plate (21) is attached to the side of the battery cell (10), and the heating power of the heating wire (31) increases from one end of the side of the battery cell (10) near the pole to the other end of the side of the battery cell (10).

2. The power battery heating device according to claim 1, characterized in that, The heating power of the heating wire (31) increases along the width direction of the heating plate (21).

3. The power battery heating device according to claim 2, characterized in that, The heating wire (31) has a straight section on the side near the initial end of the heat exchange medium in the transmission direction, and a meandering section on the side near the end of the heat exchange medium in the transmission direction. The straight segment is disposed along the length direction of the heating plate (21) at the other end of the heat exchange surface of the heating plate (21) near the side of the battery cell (10); The detour segments are arranged along the width direction of the heating plate (21), and the detour length of each detour segment along the length direction of the heating plate (21) increases from one end of the side of the battery cell (10) near the electrode post to the other end of the side of the battery cell (10), and / or the width and / or spacing of each detour segment along the width direction of the heating plate (21) decreases from one end of the side of the battery cell (10) near the electrode post to the other end of the side of the battery cell (10).

4. The power battery heating device according to claim 1, characterized in that, The heating wire (31) is periodically wavy along the length of the heating plate (21), with its period decreasing along the transmission direction of the heat exchange medium and / or its amplitude increasing along the transmission direction of the heat exchange medium.

5. A power battery heating device according to claim 1, characterized in that, The heat exchange surface of the heating plate (21) includes a first surface and / or a second surface of the heating plate (21); wherein the first surface and the second surface of the heating plate (21) are two surfaces of the heating plate (21) arranged opposite to each other; The heating wires (31) provided on the first surface and the second surface are connected to each other through the connecting section (32). The current collector (2101) is provided with a connecting groove (2101-1) on the side away from the heating plate (21). At least a part of the connecting section (32) is embedded in the connecting groove (2101-1). The two ends of the connecting section (32) are respectively connected to the heating wires (31) on the first surface and the second surface.

6. A power battery heating device according to claim 1, characterized in that, The heat exchange surface of the heating plate (21) is provided with heating grooves (212), which are strip-shaped grooves distributed in a roundabout manner on the heat exchange surface; The heating wire (31) is covered with a flexible insulating layer and is embedded in the heating groove (212) with an interference fit.

7. A method for thermal management control of a power battery, comprising a power battery heating device as described in any one of claims 1 to 6, characterized in that, include: Continuously acquire temperature parameters of multiple individual cells in the power battery; If the lowest cell temperature T of the power battery min Less than the preset heating start-up temperature threshold T limit A current is applied to the heating wire to heat the power battery; When the lowest cell temperature T min The preset heating shut-off temperature threshold T is reached. close When T is reached, heating is stopped; where T close Greater than T limit ; When the lowest cell temperature T min The preset heating shut-off temperature threshold T was not reached. close At that time, if the highest cell temperature T in the power battery is... max With the lowest cell temperature T min The difference ΔT is greater than the preset temperature difference threshold ΔT limit The current is stopped from being applied to the heating wire, and the heated heat exchange medium is transferred to the heat exchange channel of the heating plate to heat the power battery through the heat exchange surface of the heating plate.

8. The method for thermal management control of a power battery according to claim 7, characterized in that, After stopping the current applied to the heating wire and transferring the heated heat exchange medium to the heat exchange channel of the heating plate, and heating the power battery through the heat exchange surface of the heating plate, the process further includes: Determine the lowest cell temperature T min Does it show a gradual downward trend, or the highest cell temperature T max With the lowest cell temperature T min Does the difference ΔT show a gradually increasing trend? If so, reapply current to the heating wire, and use the heating wire and the heating plate together to heat the power battery; Among them, the lowest cell temperature T min The trend of gradual decline is manifested in the lowest cell temperature T. min_j ≤T min_j-△t <T limit T min_j Let T be the lowest cell temperature at time j. min_j-△T Δt represents the lowest temperature of a single battery cell at time j-Δt; Δt is the period between multiple times. Maximum cell temperature T max With the lowest cell temperature T min The difference ΔT shows a gradually increasing trend, which is reflected in the lowest cell temperature ΔT. limit <△T j-△t <△T j , △T j T is the highest single-cell temperature at time j. max With the lowest cell temperature T min The difference, △T j-△t The highest single-cell temperature T at time j-Δt max With the lowest cell temperature T min The difference.

9. The method for thermal management control of a power battery according to claim 7, characterized in that, The lowest cell temperature T of the power battery min Less than the preset heating start-up temperature threshold T limit Before heating the power battery, the process further includes applying current to the heating wire: Based on the current operating status of the electrical equipment, set the heating start-up temperature threshold T of the power battery. limit Specifically, this includes: When the electrical equipment is charging, set the heating start-up temperature threshold T of the power battery. limit For T limit1 ; When the electrical equipment is in operation, set the power battery heating start-up temperature threshold T. limit For T limit2 ; Among them, T limit1 =T limit2 +m; m takes the value of 2-5℃.

10. The method for thermal management control of a power battery according to claim 7, characterized in that, The lowest cell temperature T of the power battery min Less than the preset heating start-up temperature threshold T limit Before heating the power battery, the process further includes applying current to the heating wire: Determine the lowest cell temperature T min Is it lower than the preset heating start temperature threshold T? limit ; If the lowest cell temperature T min Less than the preset heating start-up temperature threshold T limit The circuit resistance R between the two ends of the heating wire is detected, and it is determined whether the circuit resistance R is less than or equal to a preset resistance threshold R. min ; The detection unit measures the circuit resistance R between the two ends of the heating wire and determines whether the circuit resistance R is less than or equal to a preset resistance threshold R. min Following that, it also includes: If so, issue a heating circuit fault alarm; If not, apply current to the heating wire to heat the power battery.

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