Subarea control immersed cooling system and method for square power battery pack

Abstract

The invention provides a square power battery pack partition control immersed cooling system and method.The square power battery pack partition control immersed cooling system comprises a box body, battery modules, spoilers, a driving mechanism and a control unit, the box body is in a cuboid shape, the length direction of the box body is the X-axis direction, the width direction of the box body is the Y-axis direction, and the height direction of the box body is the Z-axis direction; the battery module comprises a plurality of square single batteries which are connected in series and are horizontally placed in the box body along the length direction of the box body; the spoilers are installed on the two inner side walls in the length direction of the box body in a staggered mode and rotate along the installation side shafts. The driving mechanism is coupled with the spoiler; the control unit is in signal connection with the driving mechanism. The expansion angle is adjusted in real time according to the temperature and the heat production rate, the local flow field is changed, heat is rapidly taken away, monomer-level accurate temperature control is achieved, the temperature uniformity of the battery pack is remarkably improved, and the cycle life of the battery pack is remarkably prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power battery thermal management, in particular to a square power battery pack partition control immersion cooling system and method. BACKGROUND

[0002] Carbon emissions exacerbate the greenhouse effect, and electric vehicles have obvious advantages in reducing carbon emissions, and have been widely concerned and promoted. In recent years, the sales of electric vehicles have increased sharply, and the global trend is electric, and power battery thermal management has become the core bottleneck of safety and performance improvement.

[0003] Immersion cooling has become the next generation of technology focus for high-rate charging, thermal runaway suppression and system integration of power batteries due to direct contact between the cooling liquid and the battery surface, high specific heat capacity of the liquid and excellent temperature uniformity. However, when the local cell temperature of the battery pack is too high or the instantaneous heat generation increases sharply, the macro-uniform flow field cannot remove the heat in time, and the heat transfer will raise the temperature of the adjacent cells, triggering chain thermal runaway, such as SEI (solid electrolyte interphase) decomposition, electrolyte combustion, etc. SUMMARY

[0004] In view of the deficiencies in the prior art, the present application provides a square power battery pack partition control immersion cooling system and method.

[0005] The present application achieves the above technical purpose through the following technical means.

[0006] A square power battery pack partition control immersion cooling system, comprising a box body, a battery module, a spoiler, a driving mechanism and a control unit, wherein: the box body is a rectangular parallelepiped, the length direction of the box body is the X-axis direction, the width direction is the Y-axis direction, and the height direction is the Z-axis direction; the battery module comprises a plurality of square single cell batteries connected in series and horizontally placed inside the box body along the length direction of the box body; the spoilers are installed on the two inner side walls of the box body in the length direction and are rotated along the installation edge; the driving mechanism is coupled with the spoilers; and the control unit is signal connected with the driving mechanism.

[0007] Further, an inlet is arranged on one side wall of the box body in the width direction, and an outlet is arranged on the other side wall in the lower end.

[0008] Further, gaps are left between the battery module and the four inner side walls and the top of the box body.

[0009] Further, the spoilers are flush with the inner side walls of the box body, the spoilers are in a continuous S shape after installation, and the angle θ of the spoilers is 0°-90°. opt The adjustment range is 0° to 90°.

[0010] Furthermore, each of the aforementioned spoilers corresponds to one square single cell, and the installation position of each spoiler is on the side of the corresponding square single cell away from the inlet of the housing.

[0011] Furthermore, the surface of the spoiler is provided with hydrophilic microstructures, and the average roughness Ra of the hydrophilic microstructures is 1-10 μm.

[0012] Furthermore, the drive mechanism includes a micro motor.

[0013] Furthermore, the control unit includes a temperature sensor, a current sensor, and a voltage sensor arranged on the square single cell.

[0014] A method for controlled immersion cooling of a square power battery pack includes the following steps:

[0015] The surface temperature, discharge current and open-circuit voltage of each square cell were collected at a period of ≤100 ms, and the real-time heat generation rate q of each square cell was calculated.

[0016] (1) If q≤72000W / m 3 ,but:

[0017] Continue to collect the surface temperature, discharge current, and open-circuit voltage of each square cell at a period of ≤100 ms, and obtain the highest temperature T of each square cell. max ;

[0018] Continuous monitoring of T max If T max ≤35℃, control the corresponding spoiler to deploy to the initial angle θ opt =0°;

[0019] Continuous monitoring of T max If 35℃ <T max If the temperature is ≤45℃, then the corresponding spoiler should be deployed to angle θ. opt =25°; if 45°C <T max If the temperature is ≤55℃, then the corresponding spoiler should be deployed to angle θ. opt =45°; if 55℃ <T max If the temperature is ≤60℃, then the corresponding spoiler should be deployed to angle θ. opt =60°; if 60℃ <T max If the temperature is ≤65℃, then the corresponding spoiler should be deployed to angle θ. opt =75°; if T max If the temperature is >65℃, then the corresponding spoiler will be deployed to angle θ. opt =90°;

[0020] (2) If q>72000W / m 3 ,but:

[0021] Continue to collect the surface temperature, discharge current and open circuit voltage of each square single battery at a period of ≤100 ms;

[0022] If 72000W / m 3 <q≤128000W / m 3 , the corresponding spoiler is controlled to be expanded to an angle θ opt =25°; if 128000W / m 3 <q≤200000W / m 3 , the corresponding spoiler is controlled to be expanded to an angle θ opt =60°; if q>200000W / m 3 , the corresponding spoiler is controlled to be expanded to an angle θ opt =90°.

[0023] Further, the real-time heat production rate q of the square single battery is calculated according to the following formula:

[0024]

[0025] Wherein, I is the battery discharge current, T is the surface temperature of the battery, E is the open circuit voltage, R is the battery internal resistance, and V is the battery volume.

[0026] The present application has the following advantages:

[0027] (1) The present application forms a minimum thermal control unit by a single battery, a spoiler, a driving mechanism and a control unit, and an expandable spoiler is independently arranged for each battery, the expansion angle is adjusted in real time according to the temperature and the heat production rate, the local flow field is changed, the heat is quickly taken away, the single-level precise temperature control is realized, and the battery pack temperature uniformity and cycle life are significantly improved.

[0028] (2) The spoiler expansion mechanism of the present application adopts a micro motor direct drive scheme, the response time is low, the 90° expansion can be completed in an instant when the heat runaway sign appears, the local heat exchange intensity increases sharply, the heat spread is effectively blocked, and the whole pack thermal safety boundary is significantly enhanced. In addition, this scheme has high control precision and can accurately execute the expansion of other preset angles.

[0029] (3) In the low load working condition, the spoiler of the present application is completely attached to the wall, the flow channel is restored to be smooth, the liquid resistance is significantly reduced, the cooling pump does not need to run at high speed to maintain the necessary flow, the system auxiliary power consumption is obviously reduced, and the vehicle endurance is simultaneously benefited.

[0030] (4) The present application adopts integrated design, the spoiler and the micro motor are installed in the gap between the battery and the inner wall of the box, without occupying additional space of the battery pack, and the compactness of the structure can be ensured. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 This is the overall architecture of the cooling system described in this invention.

[0032] Figure 2 This is an isometric view of the cooling system spoiler of the present invention unfolded at 90°.

[0033] Figure 3 This is a schematic diagram illustrating the naming of the battery in the cooling system described in this invention.

[0034] Figure 4 This is the temperature change curve obtained in Example 2 of the present invention.

[0035] Figure 5 This is the temperature change curve obtained in Example 3 of the present invention.

[0036] Figure 6 This is the temperature change curve obtained in Example 4 of the present invention. Detailed Implementation

[0037] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0038] like Figure 1 , Figure 2 As shown, a sectional control immersion cooling system for a square power battery pack includes a housing, battery modules, a spoiler, a drive mechanism, and a control unit.

[0039] The housing is rectangular in shape and is used to hold the coolant. The length of the housing corresponds to the X-axis, the width to the Y-axis, and the height to the Z-axis. An inlet is located at the top of one side wall along the width direction, and an outlet is located at the bottom of the other side wall. The battery module consists of multiple square individual cells connected in series and arranged in parallel. The battery module is placed horizontally inside the housing along its length, leaving gaps between it and the four inner side walls and the top. Baffles are installed at the same height as the inner side walls of the housing, staggered on two inner side walls along the length direction, forming a continuous S-shape. Specifically, one baffle corresponds to one square individual cell, and each baffle is installed on the side of the corresponding square individual cell furthest from the housing inlet. The baffles rotate along the mounting axis at an angle θ. opt The adjustment range is 0° to 90°. The drive mechanism is coupled to the spoiler. The control unit is signal-connected to the drive mechanism.

[0040] The coolant is liquid water.

[0041] The surface of the baffle is provided with hydrophilic microstructures, the average roughness Ra of which is 1-10 μm, in order to reduce the slip length of the coolant and improve the heat transfer coefficient.

[0042] The driving mechanism includes a micro motor, which is started after the control unit obtains the surface temperature and other conditions of the square single battery, and drives the spoiler to expand.

[0043] The control unit includes temperature sensors, current sensors, and voltage sensors arranged on the square single battery to monitor the state of each square single battery.

[0044] A square power battery partition control immersion cooling method, comprising the following steps:

[0045] The surface temperature, discharge current, and open circuit voltage of each square single battery are collected periodically at ≤100 ms, and the real-time heat generation rate q of each square single battery is calculated.

[0046] (1) If q≤72000W / m 3 , then:

[0047] Continue to collect the surface temperature, discharge current, and open circuit voltage of each square single battery periodically at ≤100 ms, and obtain the highest temperature T max of each square single battery.

[0048] Continue to monitor T max , if T max ≤35℃, control the corresponding spoiler to expand to the initial angle θ opt =0°.

[0049] Continue to monitor T max , if 35℃<T max ≤45℃, control the corresponding spoiler to expand to an angle θ opt =25°; if 45℃<T max ≤55℃, control the corresponding spoiler to expand to an angle θ opt =45°; if 55℃<T max ≤60℃, control the corresponding spoiler to expand to an angle θ opt =60°; if 60℃<T max ≤65℃, control the corresponding spoiler to expand to an angle θ opt =75°; if T max >65℃, control the corresponding spoiler to expand to an angle θ opt =90°.

[0050] (2) If q>72000W / m 3 , then:

[0051] Continue to collect the surface temperature, discharge current, and open circuit voltage of each square single battery periodically at ≤100 ms.

[0052] If 72000W / m 3< q < 128000 W / m 3 then control the corresponding spoiler to deploy to an angle θ = 25°; if 128000 W / m opt < q < 200000 W / m 3 then control the corresponding spoiler to deploy to an angle θ = 60°; if q > 200000 W / m 3 < q < 128000 W / m opt then control the corresponding spoiler to deploy to an angle θ = 25°; if 128000 W / m 3 < q < 200000 W / m opt then control the corresponding spoiler to deploy to an angle θ = 60°; if q > 200000 W / m 2 then control the corresponding spoiler to deploy to an angle θ = 90°.

[0053] The real-time heat production rate q of the square monomer battery is calculated by the formula:

[0054]

[0055] wherein I is the battery discharge current, T is the surface temperature of the battery, E is the open circuit voltage, R is the battery internal resistance, and V is the battery volume.

[0056] Example 1

[0057] In the cooling system, the box: the body size is 188 mm x 415 mm x 120 mm, the size of the two top inlets and the two bottom outlets is 50 mm x 10 mm x 10 mm, and the inside is filled with deionized liquid water as a coolant; the battery module: 13 pieces of 148 mm x 27 mm x 91 mm square ternary lithium batteries are connected in series to form a module, the battery monomer spacing is 5 mm, and a 10 mm gap is formed with the inner side wall of the box and a 20 mm gap is formed with the top of the box, cell-1~cell-13 are the names of each battery, as shown in Figure 3 The spoiler: PPS-GF40 (polyphenylene sulfide - 40% glass fiber) composite material with a thickness of 1 mm, the surface is laser textured to form Ra=5μm hydrophilic microstructure, and the width is 5 mm.

[0058] ANSYS Fluent 19.2 is used to simulate the above structure. Transient simulation is used for numerical analysis of the battery module, and the battery module is placed in a sealed box, and the wall surface is considered as adiabatic. The k-ε model is used as the flow model, and the mass flow inlet boundary condition and the pressure outlet boundary condition are used at the inlet and outlet respectively. The inlet mass flow is set to 5g / s, and the standard atmospheric pressure is selected as the outlet pressure condition, and the wall surface uses the no-slip boundary condition. At the same time, considering the influence of gravity, the gravity acceleration of-9.8m / s 2 is set in the Z-axis direction.

[0059] Example 2

[0060] On the basis of embodiment 1, at the beginning of the test, the q of all batteries is not greater than 72000 W / m 3 , and the temperature of all batteries except cell-1 is not greater than 35℃. For cell-1 monomer, the temperature is 40℃ at the beginning of the test. At this time, the sensor detects the surface temperature, discharge current and open circuit voltage of the battery, and calculates that q is 32538 W / m 3 and the temperature is 40℃, the information is transmitted to the control unit, the control unit judges, and according to the above control logic, the corresponding spoiler is quickly expanded to 25°, and the temperature-time curve of the battery is recorded, as shown in Figure 4 , it can be found that the temperature of cell-1 first slowly rises and then rapidly falls, which can effectively realize the battery cooling.

[0061] Embodiment 3

[0062] On the basis of embodiment 1, at the beginning of the test, the temperature of all batteries is not greater than 35℃, and the q of all batteries except cell-7 is not greater than 72000 W / m 3 . For cell-7 monomer, the temperature is 30℃ at the beginning of the test. At this time, the sensor detects the surface temperature, discharge current and open circuit voltage of the battery, and calculates that q is 153256 W / m 3 and the temperature is 30℃, the information is transmitted to the control unit, the control unit judges, and according to the above control logic, the corresponding spoiler is quickly expanded to 60°, and the temperature-time curve of the battery is recorded, as shown in Figure 5 , it can be found that the temperature of cell-7 first rapidly rises and then tends to be stable, which can effectively inhibit the thermal runaway of the battery.

[0063] Embodiment 4

[0064] On the basis of embodiment 1, at the beginning of the test, the temperature of all batteries except cell-9 is not greater than 35℃, and the q of all batteries except cell-5 is not greater than 72000 W / m 3 . For cell-9 and cell-5, the temperature of the former is 68℃ at the beginning of the test, and the temperature of the latter is 32℃ at the beginning of the test. At this time, the sensor detects the surface temperature, discharge current and open circuit voltage of the battery, and calculates that the q of cell-9 is 35637 W / m 3 and the temperature is 68℃, the q of cell-5 is 108632 W / m 3 and the temperature is 32℃, the information is transmitted to the control unit, the control unit judges, and according to the above control logic, the corresponding spoiler is quickly expanded to 90°, 25° respectively, and the temperature-time curve of the battery is recorded, as shown in Figure 6It can be found that the temperature of cell-5 rises slowly, and the temperature of cell-9 rapidly decreases and tends to be stable, which not only can effectively inhibit the thermal runaway of the battery and realize the battery cooling, but also can realize the partition control of the battery pack.

[0065] The above embodiments are preferred embodiments of the present application, but the present application is not limited to the above embodiments, and any obvious improvement, replacement or modification made by those skilled in the art without departing from the essential content of the present application shall fall within the protection scope of the present application.

Claims

1. A square power battery pack zoned control immersion cooling system, characterized in that, The application relates to a battery module, which comprises a box, a battery module, a spoiler, a driving mechanism and a control unit, wherein the box is cuboid, the length direction of the box is the X-axis direction, the width direction of the box is the Y-axis direction, and the height direction of the box is the Z-axis direction; the battery module comprises a plurality of square single-body batteries which are arranged in series and horizontally placed in the box along the length direction of the box; the spoilers are staggered and arranged on the two inner side walls of the box along the length direction, and the spoilers rotate along the mounting edge; the driving mechanism is coupled with the spoilers; and the control unit is signal-connected with the driving mechanism.

2. The square power battery pack partition control immersion cooling system according to claim 1, wherein, An inlet is arranged on the upper end of one side wall of the box along the width direction, and an outlet is arranged on the lower end of the other side wall.

3. The square power battery pack partition control immersion cooling system according to claim 1, wherein, Gaps are left between the battery module and the four inner side walls and the top of the box.

4. The square power battery pack partition control immersion cooling system according to claim 1, wherein, The spoiler is equal in height to the inner side wall of the box, and the whole is in a continuous S shape after installation of the spoiler, and the angle θ of the spoiler opt The adjustment range is 0° to 90°.

5. The square power battery pack partition control immersion cooling system according to claim 2, wherein, One spoiler corresponds to one square single-body battery, and the mounting position of each spoiler is on the side of the corresponding square single-body battery which is far away from the inlet of the box.

6. The square power battery pack partition control immersion cooling system according to claim 1, wherein, The surface of the spoiler is provided with a hydrophilic microstructure, and the average roughness Ra of the hydrophilic microstructure is 1-10 mu m.

7. The square power battery pack partition control immersion cooling system according to claim 1, wherein, The driving mechanism comprises a micro motor.

8. The square power battery pack partition control immersion cooling system according to claim 1, wherein, The control unit comprises a temperature sensor, a current sensor and a voltage sensor which are arranged on the square single-body battery.

9. A square power battery pack zoned control immersion cooling method, characterized in that, The application further relates to a battery module control method, which comprises the following steps: The surface temperature, the discharge current and the open-circuit voltage of each square single-body battery are collected at a period of <=100 ms, and the real-time heat generation rate q of each square single-body battery is calculated; (1) if q < 72000 W / m 3 then: Continue to collect the surface temperature, discharge current and open circuit voltage of each prismatic single battery at a period of ≤100 ms, and obtain the highest temperature T of each prismatic single battery max ; Continuously monitor T max If T max ≤ 35°C, control the corresponding spoiler to deploy to the initial angle θ opt = 0°. continuously monitor T max ; if 35°C < T max ≤ 45°C, then control the corresponding spoiler to be deployed to an angle θ opt = 25°; if 45°C < T max ≤ 55°C, then control the corresponding spoiler to be deployed to an angle θ opt = 45°; if 55°C < T max ≤ 60°C, then control the corresponding spoiler to be deployed to an angle θ opt = 60°; if 60°C < T max ≤ 65°C, then control the corresponding spoiler to be deployed to an angle θ opt = 75°; if T max > 65°C, then control the corresponding spoiler to be deployed to an angle θ opt = 90°. (2) if q > 72000 W / m 3 then: The surface temperature, the discharge current and the open-circuit voltage of each square single-body battery are continuously collected at a period of <=100 ms; if 72000 < q < 128000 W / m 3 <q≤128000W / m 3 then control the corresponding spoiler to deploy to an angle θ opt = 25°; if 128000 < q < 200000 W / m 3 <q≤200000W / m 3 then control the corresponding spoiler to deploy to an angle θ opt = 60°; if q > 200000 W / m 3 then control the corresponding spoiler to deploy to an angle θ opt = 90°.

10. The method of claim 9, wherein the square power battery pack partition control immersion cooling method is characterized by, The real-time heat generation rate q of the square single-body battery is calculated according to the following formula: where I is the battery discharge current, T is the surface temperature of the battery, E is the open circuit voltage, R is the internal resistance of the battery, and V is the volume of the battery.

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