Battery pack and cell temperature difference control method

Abstract

The invention relates to the technical field of new energy batteries, in particular to a battery pack and a battery cell temperature difference control method, and the battery pack comprises a battery cell module which comprises a plurality of battery cell units which are arranged according to a preset rule; the uniform temperature plate comprises a heat insulation plate body and a plurality of groups of heat conduction units arranged on the heat insulation plate body, each battery cell unit corresponds to one group of heat conduction units, and the heat conduction units are mutually independent. According to the invention, the plurality of independent heat conduction units are arranged between the battery pack and the liquid cooling plate, and each heat conduction unit has a corresponding heat conduction coefficient, so that proper heat conduction capability can be formed according to the cooling capacity requirements of each battery cell unit in the battery pack in different environments and the temperature of the cooling liquid at the position; therefore, the temperature difference of all the battery cell units is reduced under the condition that the different cooling capacity requirements of the multiple battery cell units are met, the heat exchange efficiency is high, and the manufacturing difficulty and the operation power consumption of the water pump are reduced.

Description

Technical Field

[0001] The present invention relates to the field of new energy battery technology, and in particular to a battery pack and a method for controlling temperature differences in battery cells. Background Art

[0002] As the world moves toward sustainable development, energy management has become a key issue. With the widespread adoption of renewable energy sources such as solar and wind power, and the rapid growth of the electric vehicle market, the demand for energy storage systems has increased. As a crucial component of energy management, energy storage technology is becoming increasingly important. Current energy storage technologies primarily rely on liquid cooling for heat dissipation. Liquid cooling regulates temperature uniformity by altering the flow path of the liquid cooling plate at the bottom of the battery cells to distribute and adjust the flow rate, indirectly controlling the temperature difference between the cells.

[0003] For example, the patent publication number CN116780024A proposes a cooling channel structure, liquid cooling plate and battery system. By designing the cooling pipes into a tree-like structure, the number of cooling pipes can be increased layer by layer, ensuring that the heat exchange in the second half of the cooling pipes is more intensive, thereby gradually increasing the contact area with the heating element, reducing the temperature difference between the battery cells, achieving uniform heat exchange, and helping to increase the service life of the heating element.

[0004] For example, the patent publication number CN118589094A proposes a cooling device and battery pack, which achieves the self-temperature equalization characteristics of the liquid cooling plate through an alternating hot and cold and nearly symmetrical flow structure, reduces the temperature difference caused by asymmetry, and improves the uniformity of the cooling effect.

[0005] The above-mentioned liquid cooling systems mostly use complex and sophisticated flow channel structures to achieve uniform heat exchange, but these design processes are complicated, which increases the manufacturing difficulty and the mold development cost is high. At the same time, overly complex flow channels also reduce reliability, and there is still the problem of large temperature differences in battery cells in some areas. Summary of the Invention

[0006] In view of the technical problems existing in the thermal management of battery packs in the prior art, a first aspect of the present invention provides a battery pack, comprising:

[0007] The battery cell module includes a plurality of battery cell units, and the plurality of battery cell units are arranged according to a predetermined rule;

[0008] A temperature homogenizing plate, comprising a heat-insulating plate body and a plurality of heat-conducting units arranged on the heat-insulating plate body, wherein each battery cell unit corresponds to a group of heat-conducting units, and each heat-conducting unit is independent of each other;

[0009] a liquid cooling plate connected to a liquid cooling system to maintain the liquid cooling plate at a predetermined temperature, the liquid cooling plate comprising a housing and a cooling liquid channel constructed in the housing, the cooling liquid channel having an inlet, a flow channel, and an outlet;

[0010] The first end of the heat conducting unit is directed toward the battery core unit and is in contact with the outer wall of the battery core unit, and the second end of the heat conducting unit is directed toward the liquid cooling plate and is in contact with the surface of the shell;

[0011] Each of the heat conduction units is configured to have a predetermined thermal conductivity, so that the plurality of battery core units are maintained within a predetermined temperature range.

[0012] Preferably, the thermal conductivity of the heat conducting unit is set to change according to predetermined conditions, so that the thermal conductivity of the heat conducting unit corresponding to the battery cell with a higher temperature is higher than the thermal conductivity of the heat conducting unit corresponding to the battery cell with a lower temperature.

[0013] Preferably, the thermal insulation board body is provided with a plurality of openings penetrating the upper and lower surfaces thereof, and the heat-conducting unit includes a heat-conducting medium arranged in the openings, and the heat-conducting medium fills the openings so that the first end of the heat-conducting medium contacts the surface of the battery cell unit, and the second end contacts the shell outside the coolant channel.

[0014] Preferably, according to the direction from the inlet to the outlet of the flow channel, the heat transfer unit is set to have an opening area S at the upstream 上游 and / or thermal conductivity λ of the heat transfer medium 上游 Smaller than the downstream opening area S 下游 and / or thermal conductivity λ of the heat transfer medium 下游 .

[0015] Preferably, the thermal conductivity of the heat-conducting medium is set to change according to the temperature, and the thermal conductivity of the heat-conducting medium is proportional to the temperature.

[0016] Preferably, the thermal conductivity of the heat-conducting medium is configured to change according to an electrical signal.

[0017] Preferably, an electromagnetic coil is provided on the inner wall of the opening, the heat-conducting medium includes a heat-conducting colloid and a coating layer covering the heat-conducting colloid, a permanent magnet is provided on the surface of the coating layer, and the electromagnetic coil is electrically connected to a controller, and the controller is used to control the current of the electromagnetic coil, change the compression state of the heat-conducting colloid in the coating layer, and change the density of the heat-conducting colloid.

[0018] Preferably, the coating layer is a flexible coating layer, the thermally conductive colloid comprises thermally conductive adhesive and thermally conductive particles distributed in the thermally conductive adhesive, and when the thermally conductive adhesive is compressed, the contact density of the thermally conductive particles increases.

[0019] Preferably, the controller controls the state of the electromagnetic coil in the corresponding heat conducting unit according to the temperature of the battery cell unit at a certain position, so that the temperature of the battery cell unit is within a preset range; or the controller controls the state of the electromagnetic coil in the heat conducting unit at a corresponding position according to the temperature of a certain position in the flow channel, so that the thermal conductivity coefficient of the current heat conducting unit is inversely proportional to the temperature of the coolant in the flow channel.

[0020] The second aspect of the present invention provides a technical solution, a method for controlling the temperature difference of the battery cells of the above-mentioned battery pack, which adopts one of the following methods a, b, and c to control the temperature difference of the battery cells;

[0021] Method a includes: step a1, obtaining the temperature state of multiple positions from the inlet to the outlet of the flow channel, and calculating the temperature rise ratio of the coolant based on the obtained temperature state;

[0022] Step a2: according to the temperature rise ratio of the coolant, openings of corresponding sizes are provided on the heat insulation board along the flow direction of the coolant, wherein the area ratio of the openings at different positions is positively correlated with the temperature rise ratio of the coolant;

[0023] Step a3, filling the opening with thermal conductive adhesive to form a thermal conductive unit;

[0024] Method b includes: step b1, obtaining the temperature state of multiple positions from the inlet to the outlet of the flow channel, and calculating the temperature rise ratio of the coolant based on the obtained temperature state;

[0025] Step b2: according to the temperature rise ratio of the coolant, openings of corresponding sizes are provided on the heat insulation board along the flow direction of the coolant, wherein the area ratio of the openings at different positions is positively correlated with the temperature rise ratio of the coolant;

[0026] Step b3, filling the opening with a phase-change heat-conducting medium to form a heat-conducting unit;

[0027] Wherein, method c comprises: step c1, obtaining the temperature of the battery cell unit at different positions or the temperature of the coolant at different positions in real time;

[0028] Step c2: adjusting the thermal conductivity of the heat conducting unit according to the temperature of the battery cell unit or the temperature of the coolant to maintain the temperature of all battery cell units within a preset range;

[0029] Wherein, in step c2, the thermal conductivity of the heat conducting unit is changed by electronic control.

[0030] Compared with the prior art, the advantages of the present invention are:

[0031] The present invention provides multiple independent heat transfer units between the battery pack and the liquid cold plate, and each heat transfer unit has a corresponding thermal conductivity coefficient. This allows for the formation of appropriate heat transfer capacity based on the cooling requirements of each battery cell in the battery pack under different environments and in accordance with the coolant temperature at that location. This satisfies the varying cooling requirements of multiple battery cells while minimizing the temperature difference across all of them. This structural design is simpler and more reliable than designs with complex flow channels, offering high heat exchange efficiency and helping to reduce manufacturing difficulty and the operating power consumption of the water pump.

[0032] The heat-conducting unit in the present application may have an opening area and the heat-conducting medium filled therein determines the size of the heat-conducting capacity, which is conducive to flexibly adjusting the heat-conducting units at different positions to have appropriate heat-conducting performance; at the same time, the heat-conducting medium is designed to actively or passively adaptively adjust its thermal conductivity coefficient according to temperature or other conditions, so that all battery cells have a more consistent operating temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in various figures may be represented by the same reference numeral. For the sake of clarity, not every component is labeled in every figure. Embodiments of various aspects of the present invention will now be described by way of example and with reference to the accompanying drawings, in which:

[0034] Figure 1 is a schematic structural diagram of the battery pack shown in the present invention;

[0035] Figure 2 This is a schematic diagram of the principle of the present invention showing that the temperature equalizing plate is arranged between the battery cell module and the liquid cooling plate;

[0036] Figure 3 is a schematic diagram of the internal structure of the battery pack shown in the present invention;

[0037] Figure 4 is an exploded view of the battery pack shown in the present invention;

[0038] Figure 5 It is a structural schematic diagram of the cooling liquid channel shown in the present invention;

[0039] Figure 6 is a schematic structural diagram of a heat transfer unit shown in the first embodiment of the present invention;

[0040] Figure 7 is a schematic diagram of a heat conduction unit in a first thermal conductivity configuration shown in a second embodiment of the present invention;

[0041] Figure 8 1 is a schematic structural diagram of a heat conduction unit in a second embodiment of the present invention having a second thermal conductivity. DETAILED DESCRIPTION

[0042] In order to better understand the technical content of the present invention, specific embodiments are given and described below with reference to the accompanying drawings.

[0043] Uneven temperatures across battery cells within a battery pack are a core challenge in battery thermal management. The root causes are multifaceted, encompassing battery cell characteristics, system design, environmental factors, and operating conditions. It's important to understand that the battery pack's temperature field varies under varying operating conditions. Therefore, designing complex flow channels or using gradient thermal interface materials cannot effectively address this issue.

[0044]

Battery Pack

[0045] Combine Figures 1 to 4 As shown, a first aspect of the present invention provides a battery pack, including a cell module 100 , a temperature vapor chamber 200 , and a liquid cooling plate 300 .

[0046] In the present application, a temperature averaging plate 200 is added between the battery cell module 100 and the liquid cooling plate 300, and heat exchange between each battery cell unit 110 in the battery cell module 100 and the temperature averaging plate 200 is achieved through multiple heat conduction units 220 on the temperature averaging plate 200. By independently exchanging heat with a certain heat conduction unit 220, each battery cell unit 110 has a different heat dissipation capacity, which is beneficial to maintaining all battery cell units 110 at consistent or similar temperatures.

[0047] like Figure 2 and Figure 3 As shown, the battery module 100 includes a plurality of battery cells 110, and the plurality of battery cells 110 are arranged according to a predetermined rule, such as Figure 3 As shown, the multiple battery cell units 110 are arranged in a rectangular array, and the multiple battery cell units 110 are connected in series or in parallel.

[0048] Furthermore, the battery cell units 110 maintain the stability of the predetermined regular arrangement through the limiting structure 120. At the same time, due to the setting of the limiting structure 120, each battery cell unit 110 has a different heat exchange capacity in the environment, which is also one of the factors causing the uneven temperature of each battery cell unit 110.

[0049] Furthermore, the temperature homogenizing plate 200 includes a heat insulating plate body 210 and a plurality of heat conducting units 220 provided on the heat insulating plate body 210 . Each battery cell unit 110 corresponds to a group of heat conducting units 220 , and each heat conducting unit 220 is independent of each other.

[0050] In this way, each battery cell unit 110 exchanges heat with the cold liquid plate 300 through an independent set of heat conducting units 220 , which is beneficial for targeted control of the heat dissipation capacity of each battery cell unit 110 .

[0051] Optionally, a group of heat conducting units 220 includes at least one heat conducting unit 220 , for example, one, two or more heat conducting units 220 are provided corresponding to one battery cell unit 110 .

[0052] Furthermore, the liquid cooling plate 300 is connected to a liquid cooling system, which continuously provides circulating cooling liquid to the liquid cooling plate 300 to keep the liquid cooling plate 300 at a predetermined temperature, wherein the temperature of the liquid cooling plate 300 is 30±2°C.

[0053] Combine Figure 4 and Figure 5 As shown, the liquid cooling plate 300 includes a housing 310 and a cooling liquid channel 320 constructed in the housing 310 . The cooling liquid channel 320 has an inlet 321 , a flow channel 322 and an outlet 323 .

[0054] Since the coolant enters from the inlet 321, passes through the flow channel 322, and then flows out of the outlet 323, during this process, the coolant continuously exchanges heat with the heat conduction unit 220. Therefore, along the direction of the coolant flow, the temperature of the cold zone liquid continues to rise. Obviously, at the inlet 321, it can provide more cooling for the battery cell unit 110, but at the outlet 323, it cannot provide more cooling for the battery cell unit 110. Therefore, in order to balance this problem, it is necessary to change the thermal conductivity of the heat conduction unit 220 at the inlet 321 and the outlet 323, that is, the thermal conductivity coefficient of the heat conduction unit 220 at the inlet 321 should be lower than the thermal conductivity coefficient of the heat conduction unit 220 at the outlet.

[0055] As described above, each heat transfer unit 220 is configured to have a predetermined thermal conductivity, so that the plurality of battery cells 110 are maintained within a predetermined temperature range.

[0056] In a specific embodiment, when the coolant temperature at the inlet is 25°C, the thermal conductivity of the corresponding heat conduction unit can be selected as 3W / (m·K); when the coolant temperature at the outlet rises to 35°C, the thermal conductivity of the corresponding heat conduction unit is adjusted to 5W / (m·K).

[0057] The first end of the heat conducting unit 220 faces the battery cell unit 110 and is in contact with the outer wall of the battery cell unit 110 . The second end of the heat conducting unit 220 faces the liquid cooling plate 300 and is in contact with the surface of the shell 310 .

[0058] Optionally, the area where the heat conducting unit 220 and the battery cell unit 110 are attached includes but is not limited to the bottom surface and the side surface.

[0059] In this way, by designing the heat conducting unit 220 so that the surfaces at both ends are respectively in contact with the surfaces of the battery cell unit 11 and the shell 310 , the thermal resistance can be reduced and the heat exchange efficiency can be improved.

[0060] In an optional embodiment, the thermal conductivity of the heat conducting unit 220 is configured to change according to a predetermined condition.

[0061] The predetermined conditions include conditions that cause each battery cell 110 to form a different temperature, such as the temperature of the battery cell 110 at the inlet and outlet positions along the direction of the flow channel is different, or the arrangement position of the battery cell 110 causes the temperature of the battery cell 110 at different positions to be different, or the discharge state of the battery cell 110 causes the temperature of the battery cell 110 at different positions to be different.

[0062] The thermal conductivity of the heat conducting unit 220 should satisfy the following requirement: the thermal conductivity of the heat conducting unit 220 corresponding to the battery cell 110 with a higher temperature is higher than the thermal conductivity of the heat conducting unit 220 corresponding to the battery cell 110 with a lower temperature. In this way, the temperature of the battery cell 110 at each position can be balanced.

[0063] Combine Figure 2 and Figure 6 As shown, the insulation board body 210 is provided with a plurality of openings 211 penetrating the upper and lower surfaces thereof, and the heat conducting unit 220 includes a heat conducting medium arranged in the opening 211. The heat conducting medium fills the opening 211 so that the first end of the heat conducting medium contacts the surface of the battery cell unit 110 and the second end contacts the shell 310 outside the coolant channel 320.

[0064] Optionally, the cross-section of the opening 211 includes but is not limited to a rectangle, a circle, a regular polygon, etc.

[0065] In this way, heat exchange between the coolant in the coolant channel 320 and the battery cell unit 110 can be completed through the heat-conducting medium in the opening 211. By changing the area of ​​the opening 211 or the thermal conductivity coefficient of the heat-conducting medium, the heat exchange capacity of the heat-conducting unit 220 can be changed, so that the temperature of the battery cell unit 110 at each position is balanced.

[0066] In an optional embodiment, according to the direction from the inlet 321 to the outlet 323 of the flow channel 322, the heat transfer unit 220 is configured to have an area S of the opening 211 located upstream. 上游 and / or thermal conductivity λ of the heat transfer medium 上游 Smaller than the area S of the opening 211 located downstream 下游 and / or thermal conductivity λ of the heat transfer medium 下游 .

[0067] Since the temperature of the coolant tends to increase from the inlet 321 to the outlet 323 of the flow channel 322, in order to maintain similar cooling capacity for the battery cells 110 at all positions, the heat exchange capacity of the heat transfer unit 220 at the upstream should be smaller than that at the downstream.

[0068] Specifically, the heat exchange capacity of the heat transfer unit 220 may be changed by changing the area S of the opening 211 and / or the thermal conductivity λ of the heat transfer medium.

[0069] In an optional embodiment, the area S of the opening 211 of the heat conducting unit 220 is 上游 Smaller than the area S of the opening 211 located downstream 下游 In this way, since the contact surface of the heat-conducting units at different positions along the flow direction of the coolant tends to increase, the heat exchange capacity of the heat-conducting unit 220 located upstream is smaller than the heat exchange capacity of the heat-conducting unit 220 located downstream, which can balance the temperature difference of the battery cell units 110 at different positions.

[0070] Specifically, when the temperature of a battery cell exceeds 32°C, the thermal conductivity of the corresponding heat conduction unit is increased by 20% to improve heat exchange efficiency.

[0071] Specifically, the area ratio of the openings 211 at different locations along the coolant flow direction can be designed based on the temperature field of the battery pack. For example, if the temperature rise ratio of a certain section of the coolant reaches 0.6, the opening area is increased to 1.8 times the base value.

[0072] In an optional embodiment, the thermal conductivity coefficient λ of the heat transfer medium of the upstream heat transfer unit 220 is 上游 Less than the thermal conductivity λ of the downstream heat transfer medium 下游 In this way, since the thermal conductivity of the heat-conducting medium at different positions along the flow direction of the coolant tends to increase, the heat exchange capacity of the heat-conducting unit 220 located upstream is smaller than the heat exchange capacity of the heat-conducting unit 220 located downstream, which can balance the temperature difference of the battery cell units 110 at different positions.

[0073] Furthermore, when the temperature field changes due to the change in the discharge power of the battery cell unit 110, since the heat exchange capacity of the heat transfer unit 220 at each position does not change, the temperature difference between the battery cell units 110 cannot be reduced by simply increasing or decreasing the flow rate of the coolant. Preferably, the thermal conductivity of the heat transfer medium is set to change according to the temperature, and the thermal conductivity of the heat transfer medium is proportional to the temperature.

[0074] Optionally, the heat-conducting medium includes a heat-conducting adhesive with an adjustable phase change temperature point, such as a heat-conducting adhesive composed of a paraffin-based composite material, which can increase the thermal conductivity to form a self-adaptive adjustment when the temperature rises.

[0075] Thus, when the temperature of the battery cell unit 110 rises, the thermal conductivity of the heat-conducting medium at the corresponding position increases, thereby improving the heat exchange capacity at this position and increasing the heat exchange capacity of the battery cell unit 110 at this position, thereby reducing the temperature difference of the battery cell units 110 at all positions.

[0076] In an optional embodiment, in order to more accurately control the temperature of the battery cell unit 110 at the corresponding position, the thermal conductivity of the heat-conducting medium is set to change according to the electrical signal.

[0077] Combine Figure 7 and Figure 8 As shown, an electromagnetic coil 224 is provided on the inner wall of the opening 211, the heat-conducting medium includes a heat-conducting colloid 221 and a coating layer 222 covering the heat-conducting colloid 221, a permanent magnet 223 is provided on the surface of the coating layer 222, and the electromagnetic coil 224 is electrically connected to the controller. The controller is used to control the current of the electromagnetic coil 224, change the compression state of the heat-conducting colloid 221 in the coating layer 222, and change the density of the heat-conducting colloid 221.

[0078] Specifically, the opening 211 may be an opening with a rectangular cross-section, and the permanent magnets 223 are disposed on both sides of the coating layer 222 .

[0079] Specifically, sealing rings may be provided on the outer walls of the upper and lower ends of the coating layer 222 , and connected together by, for example, an adhesive, so that the positions and shapes of the upper and lower ends of the thermal conductive colloid 221 are fixed.

[0080] Optionally, the magnitude of the mutual magnetic force between the electromagnetic coil 224 and the permanent magnet 223 can be changed by controlling the current of the electromagnetic coil 224. When the magnetic force of the electromagnetic coil 224 on the permanent magnet 223 is greater, the permanent magnets 223 on both sides squeeze the inner thermal conductive colloid 221, thereby increasing the density of the thermal conductive colloid 221 and improving the thermal conductivity coefficient.

[0081] Furthermore, the coating layer 222 is a flexible coating layer, and the thermally conductive adhesive 221 includes thermally conductive adhesive and thermally conductive particles distributed in the thermally conductive adhesive. When the thermally conductive adhesive 221 is compressed, the contact density of the thermally conductive particles increases.

[0082] Optionally, the thermally conductive particles include ceramic or graphite particles, and the thermally conductive adhesive may be compressible thermally conductive silicone rubber or the like.

[0083] In a specific embodiment, the controller controls the state of the electromagnetic coil 224 in the corresponding heat conducting unit 220 according to the temperature of the battery cell unit 110 at a certain position, so that the temperature of the battery cell unit 110 is within a preset range.

[0084] For example, when the temperature of a battery cell 110 at a certain location is higher than a preset range, the current in the electromagnetic coil 224 is increased accordingly, causing the thermally conductive colloid 221 to be compressed to increase the heat exchange capacity, thereby improving the heat dissipation capacity of the battery cell 110 at that location.

[0085] Specifically, the current intensity in the electromagnetic coil 224 is linearly related to the temperature deviation of the battery cell, and is adjusted in real time through the PID algorithm to ensure fast response and avoid oscillation.

[0086] Specifically, when the battery cell temperature deviation ΔT=+3°C and the current I=0.2A×(1+ΔT / 10)=0.26A, the thermal conductivity coefficient is increased to 6W / (m·K) by compressing the thermal conductive colloid.

[0087] In other embodiments, the controller controls the state of the electromagnetic coil 224 in the heat transfer unit 220 at the corresponding position according to the temperature of a certain position in the flow channel 322, so that the thermal conductivity of the current heat transfer unit 220 is inversely proportional to the temperature of the coolant in the flow channel 322.

[0088] For example, if the temperature of the rear section of the flow channel is higher than a preset value, the current of the electromagnetic coil 224 is increased, so that the thermal conductive colloid 221 is compressed to improve the thermal conductivity, thereby increasing the thermal conductivity coefficient of the heat conductive unit 220 corresponding to the rear section of the flow channel, thereby improving the heat exchange efficiency between the battery cell unit 110 and the cold liquid plate.

[0089] As described above, the temperature difference of the battery cell units 110 or the temperature difference of the coolant in the flow channel can correspondingly adjust the thermal conductivity of each heat transfer unit 220, so as to facilitate controlling all battery cell units 110 to achieve consistent or similar temperatures under different heat exchange conditions.

[0090]

Battery pack cell temperature difference control method

[0091] The second aspect of the present invention provides a technical solution, a method for controlling the temperature difference of the battery cells of the above-mentioned battery pack, which adopts one of the following methods a, b, and c to control the temperature difference of the battery cells;

[0092] Method a includes:

[0093] Step a1: obtaining the temperature states of multiple locations from the inlet 321 to the outlet 322 in the flow channel 322, and calculating the temperature rise ratio of the coolant based on the temperature states;

[0094] Step a2: according to the temperature rise ratio of the coolant, openings 211 of corresponding sizes are provided on the heat insulation plate 210 along the flow direction of the coolant, wherein the area ratio of the openings 211 at different positions is positively correlated with the temperature rise ratio of the coolant;

[0095] Step a3: Fill the opening 211 with thermal conductive adhesive to form the thermal conductive unit 220 .

[0096] In step a1, the temperature state of a predetermined position of the flow channel 322 can be monitored by disposing temperature sensors, and the temperature rise ratio can be obtained by comparing the temperature difference between upstream and downstream positions of the flow channel 322.

[0097] The area ratio of the openings 211 can be controlled according to the temperature rise ratio in the flow channel. The larger the temperature rise ratio, the larger the area ratio of the openings 211, so as to meet higher heat exchange requirements in the latter part of the flow channel.

[0098] Optionally, the area ratio of the openings 211 may be selected by selecting a suitable coefficient according to the design of the flow channel and the temperature rise ratio, so as to minimize the temperature difference of the battery cell units 110 at various locations.

[0099] Method b includes:

[0100] Step b1, obtaining the temperature conditions at multiple locations from the inlet 321 to the outlet 322 in the flow channel 322, and calculating the temperature rise ratio of the coolant based on the temperature conditions;

[0101] Step b2: according to the temperature rise ratio of the coolant, openings 211 of corresponding sizes are provided on the heat insulation plate 210 along the flow direction of the coolant, wherein the area ratio of the openings 211 at different positions is positively correlated with the temperature rise ratio of the coolant;

[0102] Step b3: Fill the opening 211 with a phase-change heat-conducting medium to form a heat-conducting unit 220 .

[0103] Compared with method a, the opening 211 in method b is filled with a phase-change heat-conducting medium to form a heat-conducting unit 220, such as a thermally conductive adhesive composed of a paraffin-based composite material, which can improve thermal conductivity and form adaptive regulation when the temperature rises.

[0104] Thus, when the temperature of the battery cell unit 110 rises, the thermal conductivity of the heat-conducting medium at the corresponding position increases, thereby improving the heat exchange capacity at this position and increasing the heat exchange capacity of the battery cell unit 110 at this position, thereby reducing the temperature difference of the battery cell units 110 at all positions.

[0105] Method c includes:

[0106] Step c1, obtaining the temperature of the battery cell unit 110 at different positions or the temperature of the coolant at different positions in real time;

[0107] Step c2: adjusting the thermal conductivity of the heat conducting unit 220 according to the temperature of the battery cell unit 110 or the temperature of the coolant to maintain the temperature of all battery cell units 110 within a preset range;

[0108] In step c2, the thermal conductivity of the heat conducting unit 220 is changed by electronic control.

[0109] In an optional embodiment for method a:

[0110] Step a1: Calculation of temperature rise ratio

[0111] Data acquisition: 10 temperature sensors (T1 to T 10 ), real-time monitoring of coolant temperature.

[0112] Calculation of temperature rise ratio:

[0113] The temperature rise ratio (R) is defined as the ratio of the temperature rise of each section to the total temperature rise:

[0114] R i =(T i -T 入口 ) / (T 出口 -T 入口 )(i=1,2,…,10)

[0115] Among them, T 入口 is the inlet temperature, T 出口 is the outlet temperature, T i is the temperature of the i-th sensor.

[0116] Step a2: Setting the opening area ratio

[0117] Default principle: Linearly adjust the opening area ratio according to the temperature rise ratio (R). The opening area is the smallest at the inlet and the largest at the outlet.

[0118] Parameter range: Opening area ratio (S / S0) range: 0.5 to 2.0 (S0 is the base area, for example 5mm 2 ).

[0119] Specifically, S i =S×(1+1.5Ri)

[0120] For example, when R = 0.2, S i =5×(1+0.3)=6.5mm 2 ; When R = 0.8, S i =5×(1+1.2)=11mm 2 .

[0121] Step a3: Filling with thermal paste

[0122] Thermal adhesive parameters: Use a silicone-based thermal adhesive with a thermal conductivity of 3W / (m·K) and a filling density of 1.2g / cm 3 , after curing, it fits tightly with the battery cell unit and liquid cooling plate.

[0123] In an optional embodiment for method b:

[0124] Step b1 to step b2: The temperature rise ratio and the opening area ratio are the same as those in method a, but the heat transfer medium is replaced by phase change material (PCM).

[0125] The phase change material can be paraffin-based composite material with a phase change temperature of 35°C and a thermal conductivity that changes with temperature:

[0126] Among them, the range of the opening area ratio is consistent with that of method a, and the opening distribution can be additionally optimized according to the phase change characteristics of the PCM to ensure that the opening area ratio in the high temperature area (R ≥ 0.6) is ≥ 1.8.

[0127] In an optional embodiment for method c:

[0128] Step c1: Temperature data collection

[0129] Sensor arrangement: A temperature sensor is installed on the surface of each battery cell, with a sampling frequency of 10Hz.

[0130] Preset temperature range: Based on the optimal operating temperature of the lithium battery, the target temperature of the battery cell is set to 30±2℃.

[0131] Step c2: Electrically controlled thermal conductivity adjustment

[0132] The control logic is: If the temperature of a cell (T e )>32℃, increase the corresponding electromagnetic coil current (I) and compress the thermal conductive colloid to increase the thermal conductivity. e If the temperature is <28℃, reduce the current to lower the thermal conductivity.

[0133] In a preferred embodiment, the heat conduction units in the high temperature area are adjusted first, and the adjustment weight of the high temperature battery cell unit is 1.5 times that of the low temperature unit to ensure that the hot spots are quickly suppressed.

[0134] Combine Figure 7 and Figure 8 As shown, an electromagnetic coil 224 is provided on the inner wall of the opening 211, the heat-conducting medium includes a heat-conducting colloid 221 and a coating layer 222 covering the heat-conducting colloid 221, a permanent magnet 223 is provided on the surface of the coating layer 222, and the electromagnetic coil 224 is electrically connected to the controller. The controller is used to control the current of the electromagnetic coil 224, change the compression state of the heat-conducting colloid 221 in the coating layer 222, and change the density of the heat-conducting colloid 221.

[0135] Specifically, the opening 211 may be an opening with a rectangular cross-section, and the permanent magnets 223 are disposed on both sides of the coating layer 222 .

[0136] Optionally, the magnitude of the mutual magnetic force between the electromagnetic coil 224 and the permanent magnet 223 can be changed by controlling the current of the electromagnetic coil 224. When the magnetic force of the electromagnetic coil 224 on the permanent magnet 223 is greater, the permanent magnets 223 on both sides squeeze the inner thermal conductive colloid 221, thereby increasing the density of the thermal conductive colloid 221 and improving the thermal conductivity coefficient.

[0137] Furthermore, the coating layer 222 is a flexible coating layer, and the thermally conductive adhesive 221 includes thermally conductive adhesive and thermally conductive particles distributed in the thermally conductive adhesive. When the thermally conductive adhesive 221 is compressed, the contact density of the thermally conductive particles increases.

[0138] Optionally, the thermally conductive particles include ceramic or graphite particles, and the thermally conductive adhesive may be compressible thermally conductive silicone rubber or the like.

[0139] In a specific embodiment, the controller controls the state of the electromagnetic coil 224 in the corresponding heat conducting unit 220 according to the temperature of the battery cell unit 110 at a certain position, so that the temperature of the battery cell unit 110 is within a preset range.

[0140] For example, when the temperature of a battery cell 110 at a certain location is higher than a preset range, the current in the electromagnetic coil 224 is increased accordingly, causing the thermally conductive colloid 221 to be compressed to increase the heat exchange capacity, thereby improving the heat dissipation capacity of the battery cell 110 at that location.

[0141] In other embodiments, the controller controls the state of the electromagnetic coil 224 in the heat transfer unit 220 at the corresponding position according to the temperature of a certain position in the flow channel 322, so that the thermal conductivity of the current heat transfer unit 220 is inversely proportional to the temperature of the coolant in the flow channel 322.

[0142] For example, if the temperature of the rear section of the flow channel is higher than a preset value, the current of the electromagnetic coil 224 is increased, so that the thermal conductive colloid 221 is compressed to improve the thermal conductivity, thereby increasing the thermal conductivity coefficient of the heat conductive unit 220 corresponding to the rear section of the flow channel, thereby improving the heat exchange efficiency between the battery cell unit 110 and the cold liquid plate.

[0143] As described above, the temperature difference of the battery cell units 110 or the temperature difference of the coolant in the flow channel can correspondingly adjust the thermal conductivity of each heat transfer unit 220, so as to facilitate controlling all battery cell units 110 to achieve consistent or similar temperatures under different heat exchange conditions.

[0144] In combination with the above embodiments, the present invention provides multiple independent heat transfer units between the battery pack and the liquid cold plate, and each heat transfer unit has a corresponding thermal conductivity coefficient. This can form an appropriate heat transfer capacity based on the cooling requirements of each battery cell unit in the battery pack under different environments and in accordance with the coolant temperature at that location. In other words, it can meet the different cooling requirements of multiple battery cells while reducing the temperature difference between all battery cells. Compared with designs with complex flow channels, this structural design is simpler and more reliable, has high heat exchange efficiency, and helps reduce manufacturing difficulty and the operating power consumption of the water pump.

[0145] The heat-conducting unit in the present application may have an opening area and the heat-conducting medium filled therein determines the size of the heat-conducting capacity, which is conducive to flexibly adjusting the heat-conducting units at different positions to have appropriate heat-conducting performance; at the same time, the heat-conducting medium is designed to actively or passively adaptively adjust its thermal conductivity coefficient according to temperature or other conditions, so that all battery cells have a more consistent operating temperature.

[0146] While the present invention has been disclosed above with reference to preferred embodiments, this is not intended to limit the present invention. Persons skilled in the art will readily appreciate that various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A battery pack, characterized in that: include: A battery cell module (100) includes a plurality of battery cell units (110), wherein the plurality of battery cell units (110) are arranged according to a predetermined rule; A temperature homogenizing plate (200) comprises a heat insulating plate body (210) and a plurality of heat conducting units (220) arranged on the heat insulating plate body (210), wherein each battery cell unit (110) corresponds to a group of heat conducting units (220), and each heat conducting unit (220) is independent of each other; A liquid cooling plate (300) is connected to a liquid cooling system to maintain a predetermined temperature of the liquid cooling plate (300), wherein the liquid cooling plate (300) comprises a housing (310) and a cooling liquid channel (320) constructed in the housing (310), wherein the cooling liquid channel (320) has an inlet (321), a flow channel (322), and an outlet (323); The first end of the heat conducting unit (220) faces the direction of the battery core unit (110) and is in contact with the outer wall of the battery core unit (110); the second end of the heat conducting unit (220) faces the direction of the liquid cooling plate (300) and is in contact with the surface of the shell (310); Each of the heat conduction units (220) is configured to have a predetermined thermal conductivity, so that the plurality of battery core units (110) are maintained within a predetermined temperature range.

2. The battery pack according to claim 1, wherein: The thermal conductivity of the heat conduction unit (220) is set to change according to a predetermined condition, so that the thermal conductivity of the heat conduction unit (220) corresponding to the battery cell unit (110) with a higher temperature is higher than the thermal conductivity of the heat conduction unit (220) corresponding to the battery cell unit (110) with a lower temperature.

3. The battery pack according to claim 1, wherein: The heat insulation plate body (210) is provided with a plurality of openings (211) penetrating the upper and lower surfaces thereof. The heat conduction unit (220) includes a heat conduction medium arranged in the openings (211). The heat conduction medium fills the openings (211), so that a first end of the heat conduction medium contacts the surface of the battery cell unit (110), and a second end contacts the shell (310) outside the coolant channel (320).

4. The battery pack according to claim 3, wherein: According to the direction from the inlet (321) to the outlet (323) of the flow channel (322), the heat conduction unit (220) is configured to have an opening (211) area S at the upstream. 上游 and / or thermal conductivity λ of the heat transfer medium 上游 Smaller than the area S of the downstream opening (211) 下游 and / or thermal conductivity λ of the heat transfer medium 下游 .

5. The battery pack according to claim 4, characterized in that: The thermal conductivity of the heat-conducting medium is configured to change according to temperature, and the thermal conductivity of the heat-conducting medium is directly proportional to the temperature.

6. The battery pack according to claim 4, characterized in that: The thermal conductivity of the heat conducting medium is configured to change according to an electrical signal.

7. The battery pack according to claim 6, characterized in that: An electromagnetic coil (224) is provided on the inner wall of the opening (211); the heat-conducting medium comprises a heat-conducting colloid (221) and a coating layer (222) coating the heat-conducting colloid (221); a permanent magnet (223) is provided on the surface of the coating layer (222); the electromagnetic coil (224) is electrically connected to a controller; the controller is used to control the current of the electromagnetic coil (224), change the compression state of the heat-conducting colloid (221) in the coating layer (222), and change the density of the heat-conducting colloid (221).

8. The battery pack according to claim 7, characterized in that: The coating layer (222) is a flexible coating layer, the thermally conductive colloid (221) comprises thermally conductive glue and thermally conductive particles distributed in the thermally conductive glue, and when the thermally conductive glue (221) is compressed, the contact density of the thermally conductive particles increases.

9. The battery pack according to claim 7, characterized in that: The controller controls the state of the electromagnetic coil (224) in the corresponding heat conduction unit (220) according to the temperature of the battery cell (110) at a certain position, so that the temperature of the battery cell (110) is within a preset range; or the controller controls the state of the electromagnetic coil (224) in the heat conduction unit (220) at a corresponding position according to the temperature of a certain position in the flow channel (322), so that the thermal conductivity of the current heat conduction unit (220) is inversely proportional to the temperature of the coolant in the flow channel (322).

10. The method for controlling the temperature difference of a battery cell of a battery pack according to any one of claims 1 to 9, wherein: Use one of the following methods a, b, or c to control the temperature difference of the battery cell; The method a comprises: step a1, obtaining the temperature states of multiple positions from the inlet (321) to the outlet (322) in the flow channel (322), and calculating the temperature rise ratio of the coolant based on the obtained temperature states; Step a2: according to the temperature rise ratio of the coolant, openings (211) of corresponding sizes are provided on the heat insulation plate (210) along the flow direction of the coolant, wherein the area ratio of the openings (211) at different positions is positively correlated with the temperature rise ratio of the coolant; Step a3, filling the opening (211) with heat-conducting glue to form a heat-conducting unit (220); The method b comprises: step b1, obtaining the temperature states of multiple positions from the inlet (321) to the outlet (322) in the flow channel (322), and calculating the temperature rise ratio of the coolant based on the obtained temperature states; Step b2, according to the temperature rise ratio of the coolant, setting openings (211) of corresponding sizes on the heat insulation plate body (210) along the flow direction of the coolant, wherein the area ratio of the openings (211) at different positions is positively correlated with the temperature rise ratio of the coolant; Step b3, filling the opening (211) with a phase-change heat-conducting medium to form a heat-conducting unit (220); Wherein, method c comprises: step c1, obtaining the temperature of the battery cell (110) at different positions or the temperature of the coolant at different positions in real time; Step c2, adjusting the thermal conductivity of the heat conduction unit (220) according to the temperature of the battery cell unit (110) or the temperature of the coolant, to maintain the temperature of all battery cell units (110) within a preset range; Wherein, in step c2, the thermal conductivity of the heat conducting unit (220) is changed by an electrical control method.

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