A power battery pack and a cooling control method thereof

Abstract

The application discloses a power battery pack and a cooling control method thereof. The power battery pack comprises a plurality of batteries, a first cooling subsystem, a second cooling subsystem, a third cooling subsystem and a control subsystem. The first cooling subsystem is used for cooling and dissipating heat at the top of the batteries. The third cooling subsystem is used for cooling and dissipating heat at the bottom of the batteries. The second cooling subsystem is used for cooling the side walls of the batteries. The first and third cooling subsystems are both provided with channels through which a first working medium flows. The second cooling subsystem is provided with a second working medium. The control subsystem monitors the temperature of the side walls of the batteries according to a temperature sensor arranged in the power battery pack, thereby adjusting the flow rate of the working medium, and thereby forming an energy-saving control device capable of changing with the temperature of the batteries.

Description

Technical Field

[0001] This invention belongs to the field of power battery pack technology, specifically relating to a power battery pack and its cooling control method. Background Technology

[0002] With the increasingly widespread use of new energy vehicles, the power battery, as the main energy storage component, directly affects the vehicle's performance and safety due to its heat dissipation performance. Improving the stability of power batteries has become a key research focus for major companies.

[0003] Current power battery packs typically use a liquid cooling plate between the bottom of the battery module and the bottom of the casing to facilitate heat exchange between the battery and the coolant, thus suppressing battery temperature rise. However, this structure has low thermal management efficiency and poor cooling effect. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and propose a power battery pack and its control method. The power battery pack has three cooling subsystems, which respectively cool the top, sidewalls and bottom of the battery cells; at least the second cooling subsystem is equipped with a temperature sensor, which can control the flow rate of the working fluid according to the monitored temperature, thereby forming an energy-saving control device that can change with the battery temperature.

[0005] The first aspect of the present invention provides a power battery pack, which includes a plurality of batteries, a first cooling subsystem, a second cooling subsystem, a third cooling subsystem, and a control subsystem;

[0006] The first cooling subsystem is used to cool and dissipate heat to the top of the battery, including an upper liquid cooling plate and an upper liquid cooling channel disposed inside the upper liquid cooling plate, the upper liquid cooling plate covering the top of the battery; a first working fluid flows through the upper liquid cooling channel;

[0007] The third cooling subsystem is used to cool and dissipate heat at the bottom of the battery, including a lower liquid cooling plate and a lower liquid cooling channel. The bottom of the battery cell is placed on top of the lower liquid cooling plate. A first working fluid flows through the lower liquid cooling channel.

[0008] The second cooling subsystem is used to cool the battery sidewalls, and a second working fluid is provided within the second cooling subsystem;

[0009] The control subsystem includes a controller, a temperature sensor, and a control valve; the temperature sensor is located at least on the side wall of the battery and is electrically connected to the controller; the control valve is used to adjust at least the first working fluid flow rate according to the controller's indication; the controller is used to adjust the first working fluid flow rate in the first cooling subsystem and the third cooling subsystem according to the temperature monitored by the temperature sensor.

[0010] Furthermore, the battery pack contains multiple battery cells arranged side by side; the second cooling subsystem is used to cool the sidewalls of the battery cells and includes a heat-conducting plate, a heat-insulating plate, a barrier box, and an outer casing; a heat-conducting plate and a heat-insulating plate are arranged side by side between every two adjacent battery cells, and multiple fins extend from one side of the heat-conducting plate, with the ends of the fins extending beyond the battery cell and contacting the inner wall of the barrier box; the heat-conducting plate is used to transfer the heat of its adjacent battery cells to the heat-conducting plate and its fins, and the heat-insulating plate is used to block the heat transfer between adjacent battery cells;

[0011] All the battery cells are housed within the barrier box, which is fitted inside the outer casing with a gap between the two casings. A second working fluid is filled in the gap between the barrier box and the outer casing to form a cooling chamber, which cools the heat from the fins. Multiple refrigerant channels are arranged laterally along the two opposite side walls of the outer casing, through which the second working fluid flows. Temperature sensors are located on the tabs and the side walls of the battery cells, respectively. Control valves are located at the liquid inlets and refrigerant inlets of the upper and lower liquid cooling channels, respectively, and are used to adjust the flow rates of the first and second working fluids according to the controller's instructions. The controller is used to adjust the flow rates of the first and second working fluids in the first, second, and third cooling subsystems based on the temperatures monitored by the temperature sensors.

[0012] Furthermore, the top tab of the battery cell has electrical connection wires on some of the tabs; the upper liquid cooling channel is laid in an S-shape inside the upper liquid cooling plate, and the contact portion between the upper liquid cooling plate and the top of the battery cell is provided with a groove that matches the outer contour of the tab and the electrical connection wires, so that when the upper liquid cooling plate is fastened to the top of the battery cell as a cover for the tab and the electrical connection wires, the first cooling subsystem can fully contact the tab.

[0013] The lower liquid cooling channel is laid in an S-shape inside the lower liquid cooling plate.

[0014] Furthermore, the liquid cooling circulation paths of the first and third cooling subsystems are as follows: the first working fluid stored in the first storage tank is water. The outlet of the first storage tank is connected to one end of a water pump through a pipeline. The other end of the water pump is divided into two branches. One branch enters the inlet of the upper liquid cooling channel after passing through a control valve, flows through the first cooling subsystem, flows out from the outlet of the upper liquid cooling channel, and then flows back to the first storage tank through the outer channel. The other branch enters the lower liquid cooling channel after passing through another control valve, flows through the second cooling subsystem, flows out from the outlet of the lower liquid cooling channel, and then flows back to the first storage tank through the outer channel.

[0015] Furthermore, the ends of the multiple refrigerant channels located on the same side of the sidewall are refrigerant inlets, and the ends located on the other side are refrigerant outlets, thereby causing the second working fluid in all refrigerant channels within the power battery pack to flow in the same direction; the liquid cooling circulation path of the second cooling subsystem is as follows: the second working fluid stored in the second storage tank is liquid nitrogen, and the outlet of the second storage tank flows through a pipeline, then through a control valve, and then through a pipeline to the refrigerant inlet. The liquid nitrogen flows laterally from the refrigerant inlet along the sidewall of the outer casing, and finally flows out from the refrigerant outlet. After passing through the outer channel and a pressurization device, it is re-formed into liquid nitrogen and returns to the second storage tank.

[0016] The cooling control method for the power battery pack includes:

[0017] Temperature sensors monitor the temperature of the tabs and sidewalls of the battery cells in the power battery pack in real time and upload the data to the controller.

[0018] When the highest monitored temperature of the battery cell sidewall and electrode sidewall is 25-40℃, adjust the control valves at the inlet of the upper and lower liquid cooling channels to make the flow rate of the first working fluid 0.3m / s, and close the control valve at the refrigerant inlet of the second cooling subsystem; when the highest monitored temperature of the battery cell sidewall and electrode sidewall is 40-60℃, adjust the control valves at the inlet of the upper and lower liquid cooling channels to make the flow rate of the first working fluid inside the upper and lower liquid cooling channels 0.8m / s, and adjust the control valve at the refrigerant inlet of the refrigerant channel to make the flow rate of the second working fluid at the refrigerant inlet 0.5m / s ... When the highest monitored temperature of the battery cell wall and tabs is 60-90℃, adjust the control valves at the inlet of the upper and lower liquid cooling channels to make the flow rate of the first working fluid inside the upper and lower liquid cooling channels 1.2m / s, and adjust the control valve at the refrigerant inlet to make the flow rate of the second working fluid at the refrigerant inlet 0.8m / s; when the highest monitored temperature of the battery cell sidewall and tabs exceeds 90℃, adjust the control valves at the inlet of the upper and lower liquid cooling channels to make the flow rate of the first working fluid inside the upper and lower liquid cooling channels 1.2m / s, and adjust the control valve at the refrigerant inlet to make the flow rate of the second working fluid at the refrigerant inlet 1m / s.

[0019] Optionally, the battery in the power battery pack consists of multiple cylindrical cells, the upper liquid cooling plate and the lower liquid cooling plate are disc-shaped, and the top and bottom ends of a fastener are fixedly connected to the edges of the upper liquid cooling plate and the lower liquid cooling plate, respectively, so that the upper liquid cooling plate, the lower liquid cooling plate and the fastener together form a hollow structure; the multiple cells are vertically arranged in the hollow structure, and the top of the cells faces the upper liquid cooling plate;

[0020] The second cooling subsystem specifically comprises a second working medium filled in the gaps between the cells inside the upper liquid cooling plate, the lower liquid cooling plate, and the fasteners. The second working medium is a phase change material.

[0021] The upper liquid cooling channel in the first cooling subsystem is a spiral pipe, including a first liquid inlet and a first liquid outlet. The first liquid inlet is located at the outermost end of the spiral and the first liquid outlet is located at the center of the spiral.

[0022] The lower liquid cooling channel in the third cooling subsystem is a spiral pipe, including a second liquid inlet and a second liquid outlet. The second liquid inlet is located at the center of the spiral, and the second liquid outlet is located at the outermost end of the spiral.

[0023] The first liquid outlet and the second liquid inlet are connected by a central liquid cooling pipe, and the first working fluid flows through the upper liquid cooling channel and the lower liquid cooling channel.

[0024] Furthermore, a vertical support column is provided at the center of the lower liquid cooling plate, pointing towards the upper liquid cooling plate. The height of the support column is equal to the distance between the upper and lower liquid cooling plates, and the support column is a hollow structure with a central liquid cooling pipe vertically installed inside.

[0025] Furthermore, the circulation path of the liquid cooling working fluid in the power battery pack is as follows: the first working fluid stored in the storage tank is water. The outlet of the storage tank is connected to one end of a water pump through a pipeline. The other end of the water pump enters the first inlet of the upper liquid cooling channel through a control valve. After flowing through the upper liquid cooling channel, it flows out from the first outlet. Then it flows through the central liquid cooling pipe and enters the second inlet. After flowing through the lower liquid cooling channel, it flows out from the second outlet and then flows back to the storage tank through the outer channel.

[0026] Furthermore, the positive terminal of the battery cell is topologically attached with a tab, which contacts the bottom of the liquid cooling plate, and multiple battery cells are arranged in a circle.

[0027] The cooling control method for the power battery pack includes: when the highest monitored temperature of the cell sidewall is 25-40℃, adjusting the control valve at the first inlet of the upper liquid cooling channel to make the working fluid flow rate 0.3m / s; when the highest monitored temperature of the cell sidewall is 40-60℃, adjusting the control valve at the first inlet to make the working fluid flow rate inside the upper and lower liquid cooling channels 0.8m / s; when the highest monitored temperature of the cell is 60-90℃, adjusting the control valve at the first inlet to make the working fluid flow rate inside the upper and lower liquid cooling channels 1.2m / s; when the highest monitored temperature of the cell exceeds 90℃, adjusting the control valve at the first inlet to make the working fluid flow rate inside the upper and lower liquid cooling channels 1.2m / s, and activating the internal BMS of the power battery pack to detect whether thermal runaway has occurred and to extinguish fires.

[0028] Compared with the prior art, the beneficial effects of the technical solution of the present invention are as follows:

[0029] 1. The upper liquid cooling plate, as a cover, is in close contact with the top of the battery, ensuring rapid heat dissipation and cooling while also meeting the requirements for tightness between the cover and the battery, thus enhancing the overall stability of the battery pack.

[0030] 2. This invention uses two liquid cooling working fluids to cool and / or circulate the top, sidewalls, and bottom of the battery cell / cell respectively; for the sidewalls of the battery cell, the heat dissipation fins are located between the outer casing and the barrier box, ensuring that the second working fluid, liquid nitrogen, does not directly contact the battery, thus improving the cell life and the overall safety performance of the battery pack; for the sidewalls of the cell, paraffin wax is selected as the second working fluid, using a simple method to isolate adjacent cells;

[0031] 3. In Example 1 of this invention, the flow rates of the two liquid cooling working fluids can be adjusted according to the temperature of the battery, thus avoiding energy waste caused by a single flow rate. Attached Figure Description

[0032] Figure 1 This is an exploded view of the power battery pack in Example 1;

[0033] Figure 2 This is a top view of the second cooling subsystem of the power battery pack in Embodiment 1;

[0034] Figure 3 This is a schematic diagram of the internal flow channel of the upper liquid cooling plate of the power battery pack in Example 1;

[0035] Figure 4 This is a liquid cooling circulation path diagram of the first and third cooling subsystems of the power battery pack described in Example 1;

[0036] Figure 5 This is a liquid cooling circulation path diagram of the second cooling subsystem of the power battery pack described in Example 1;

[0037] Figure 6 This is an exploded view of the power battery pack in Example 2;

[0038] Figure 7 for Figure 6 A top view of the power battery pack shown;

[0039] Figure 8 for Figure 6 The diagram shows a three-dimensional perspective view of the power battery pack.

[0040] In the picture:

[0041] 1, 111: Upper liquid cooling channel; 2, 112: Upper liquid cooling plate; 3: Tab.

[0042] 4: Battery cell 5: Electrical connection wire 6: Heat-conducting plate

[0043] 7: Heat insulation plate; 8: Temperature sensor; 9: Fins

[0044] 10: Barrier box; 11: Refrigerant inlet; 12: Outer casing

[0045] 13, 113: Lower liquid cooling channel; 14, 114: Lower liquid cooling plate; 15: Refrigerant outlet.

[0046] 16: First storage tank; 17, 22: Piping; 18: Water pump

[0047] 19, 23: Control valves; 20, 25: Outflow channels; 21: Second storage tank.

[0048] 24: Second cooling subsystem; 26: Pressurization device; 31: First liquid inlet.

[0049] 32: First liquid outlet; 41: Second liquid inlet; 42: Second liquid outlet

[0050] 43: Phase change material; 44: Fasteners; 45: Central liquid cooling pipes

[0051] 46: Battery cell 47: Support pillar Detailed Implementation

[0052] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The specific embodiments described are only for explanation and illustration of the present invention and are not intended to limit the present invention.

[0053] Example 1

[0054] like Figure 1-2 As shown, a power battery pack includes multiple battery cells 4 arranged side by side and a first cooling subsystem, a second cooling subsystem, a third cooling subsystem, and a controller located from top to bottom at the top, side wall, and bottom of the battery cells, respectively. The top of each battery cell 4 has two protruding tabs 3. Each of the battery cells at both ends has one tab 3 without an electrical connection line 5 on its top. The tops of the tabs 3 of the remaining battery cells 4 are connected to the tops of the tabs 3 of the battery cells 4 to their right sides via an electrical connection line 5.

[0055] The first cooling subsystem includes an upper liquid cooling plate 2 and an upper liquid cooling channel 1, wherein the upper liquid cooling channel 1 is arranged in an S-shape within the upper liquid cooling plate 2 (e.g., Figure 3 (As shown); the bottom of the upper liquid cooling plate 2 has a groove that matches the outer contour of the tabs and electrical connection lines. When the upper liquid cooling plate 2 is fastened to the tabs and electrical connection lines 5 as a cover plate for the tabs 3 and electrical connection lines 5, it can make full contact with the tabs and electrical connection lines located on the top of the battery cells 4, which facilitates the cooling and heat dissipation of the tabs 3. The flow rate of water inside the upper liquid cooling channel 1 can be changed at any time according to the temperature of the battery.

[0056] The third cooling subsystem includes a lower liquid cooling plate 14 and a lower liquid cooling channel 13, wherein the lower liquid cooling channel 13 is laid in an S-shape within the lower liquid cooling plate 14 (e.g., ...). Figure 3 As shown, the top of the lower liquid cooling plate 14 rests against the bottom of the battery cell 4. The third cooling subsystem is used for cooling and heat dissipation at the bottom of the battery cell. The flow rate of water inside the lower liquid cooling channel 13 can be changed at any time according to the temperature of the battery.

[0057] like Figure 4 As shown, the liquid cooling circulation paths of the first and third cooling subsystems are as follows: the working fluid stored in the first storage tank 16 is water. The outlet of the first storage tank 16 is connected to one end of a water pump 18 through a pipe 17. The other end of the water pump 18 is divided into two branches. One branch enters the inlet of the upper liquid cooling channel 1 through a control valve 19, flows through the first cooling subsystem, flows out from the outlet of the upper liquid cooling channel 1, and then flows back to the first storage tank 16 through the outer channel 20. The other branch enters the lower liquid cooling channel 13 through another control valve 19, flows through the second cooling subsystem, flows out from the outlet of the lower liquid cooling channel 13, and then flows back to the first storage tank 16 through the outer channel 20.

[0058] The second cooling subsystem includes a heat-conducting plate 6, a heat-insulating plate 7, a barrier box 10, and an outer casing 12. The barrier box 10 includes a bottom wall and side walls, but no top wall. All the battery cells 4 are housed within the barrier box 10. A heat-conducting plate 6 and a heat-insulating plate 7 are arranged side-by-side between every two adjacent battery cells 4. The arrangement order of two adjacent battery cells, heat-conducting plates, and heat-insulating plates is: battery - heat-conducting plate - heat-insulating plate - battery. The size of the heat-insulating plate 7 is adapted to the side wall size of the battery cell. The heat-conducting plate 6 is a 2mm thick aluminum plate, and the heat-insulating plate 7 is a 3mm thick SiO2-Al2O3 aerogel. The heat-conducting plate 6 includes an integral body and fins 9. The size of the body of the heat-conducting plate 6 is the same as the size of the heat-insulating plate 7. Multiple fins 9 extend from one side of the body, and the ends of the fins 9 extend beyond the battery cell 4 and contact the inner wall of the barrier box 10.

[0059] The outer casing 12 includes a bottom wall and side walls, but no top wall. The height of the barrier box 10 and the outer casing 12 is equal to the height of the battery cell. The width of the outer casing 12 is greater than the width of the barrier box 10, so that the barrier box 10 is fitted inside the outer casing 12 with a gap between the two casings. Liquid nitrogen is filled in the gap between the barrier box 10 and the outer casing 12 as a refrigerant to form a cooling chamber. Since the ends of the fins 9 abut against the inner wall of the barrier box 10, the cooling chamber between the barrier box 10 and the outer casing 12 can cool the heat of the fins by utilizing the property of liquid nitrogen vaporization absorbing a large amount of heat. The barrier box 10 completely isolates the battery cell 4 from contact with the refrigerant in the cooling chamber.

[0060] Multiple refrigerant channels extending laterally along the two opposite sidewalls of the outer casing 12 are provided. These refrigerant channels traverse the sidewalls laterally, with their two ends reaching the two ends of the sidewalls respectively. The ends of the multiple refrigerant channels on the same side of the sidewall serve as refrigerant inlets 11, and the ends on the other side serve as refrigerant outlets 15, thereby ensuring that the liquid nitrogen in all refrigerant channels within the power battery pack flows in the same direction; for example... Figure 5 As shown, the liquid cooling circulation path of the second cooling subsystem 24 is as follows: the working fluid stored in the second storage tank 21 is liquid nitrogen. The outlet of the second storage tank 21 flows through pipe 22, then through a control valve 23, and then through pipe 22 to the refrigerant inlet 11. Liquid nitrogen flows laterally from the refrigerant inlet along the side wall of the outer casing 12, and finally flows out from the refrigerant outlet 15. After passing through the outer flow channel 25 and a pressurization device 26, it re-forms liquid nitrogen and returns to the second storage tank 21. The flow rate and volume of liquid nitrogen in the refrigerant channel can be changed at any time according to the battery temperature, thereby continuously cooling the refrigerant located in the cooling chamber during the liquid nitrogen flow.

[0061] Temperature sensors 8 are respectively installed on the upper liquid cooling plate 2, lower liquid cooling plate 14, electrode tabs 3 (located on the side wall of each electrode tab 3), and each side wall of the battery cell within the power battery pack. The temperature sensors 8 are electrically connected to the controller and transmit the monitored temperature to the controller. The controller then controls the flow rate of the working fluid in the first, second, and third cooling subsystems based on the temperature monitored by the temperature sensors. Depending on actual needs, the power battery pack can also use a BMS to monitor the temperature.

[0062] The specific cooling control method for the power battery pack includes:

[0063] The temperature sensor monitors the temperature of the upper liquid cooling plate 2, lower liquid cooling plate 14, tabs 3, fins 9, and the sidewalls of the battery cells 4 in the power battery pack in real time and uploads the data to the controller. A control valve is installed at the liquid inlet and refrigerant inlet of the upper and lower liquid cooling channels, respectively. The control valve is electrically connected to the controller and is used to adjust the working fluid flow rate according to the controller's instructions.

[0064] When the highest monitored temperature of the battery cell sidewall and electrode sidewall is 25-40℃ (the control unit identifies this as temperature priority, using the highest temperature monitored by the temperature sensor), the controller controls the control valve 19 at the inlet of the upper and lower liquid cooling channels to make the water flow rate inside the upper and lower liquid cooling channels 0.3m / s, and closes the control valve 23 at the refrigerant inlet. At this time, the liquid nitrogen flow rate in the refrigerant channel of the second cooling subsystem is 0, and the second cooling subsystem does not work. When the highest monitored temperature of the battery cell sidewall and electrode is 40-60℃, the controller controls the control valve 19 at the inlet of the upper and lower liquid cooling channels to make the working fluid flow rate inside the upper and lower liquid cooling channels 0.8m / s, and the second cooling subsystem starts working. The control valve 23 at the refrigerant inlet 11 is adjusted to allow the refrigerant to flow through. The refrigerant inlet 11 of the refrigerant channel has a flow rate of 0.5 m / s. When the highest monitored temperature of the battery cell sidewall and electrode tabs is 60-90℃, the control valves 19 at the inlets of the upper and lower liquid cooling channels are adjusted to make the water flow rate inside the upper and lower liquid cooling channels 1.2 m / s, and the control valve 23 at the refrigerant inlet of the refrigerant channel is adjusted to make the liquid nitrogen flow rate at the refrigerant inlet 0.8 m / s. When the highest monitored temperature of the battery cell sidewall and electrode tabs exceeds 90℃, the control valves 19 at the inlets of the upper and lower liquid cooling channels are adjusted to make the water flow rate inside the upper and lower liquid cooling channels 1.2 m / s, and the control valve 23 at the refrigerant inlet 11 is adjusted to make the liquid nitrogen flow rate at the refrigerant inlet 1m / s. At this time, other fire-fighting measures inside the power battery pack are activated to detect whether thermal runaway has occurred in the power battery pack and to extinguish the fire. The synergistic working mechanism between other fire-fighting measures and this invention is not described here.

[0065] Example 2

[0066] The power battery pack in this embodiment uses an upper liquid cooling plate and a lower liquid cooling plate with built-in spiral pipes to cool the top and bottom of the battery cells. The liquid cooling medium located in the pipes can also adjust the flow rate according to the battery cell temperature monitored by the BMS or the temperature sensor installed inside it. In addition, phase change materials are placed between the battery cells to absorb the heat generated by the battery, thereby cooling the top, sidewalls and bottom of the battery cells respectively according to the battery temperature.

[0067] like Figure 6-8As shown, a power battery pack includes multiple cylindrical battery cells 46, an upper liquid cooling plate 112 and a lower liquid cooling plate 114, and a controller. The upper liquid cooling plate 112 and the lower liquid cooling plate 114 are disc-shaped. The upper and lower ends of a circular fastener 44 are fixedly connected to the edges of the upper liquid cooling plate 112 and the lower liquid cooling plate 114, respectively, so that the upper liquid cooling plate 112, the lower liquid cooling plate 114, and the fastener 44 together form a hollow cylindrical structure. A vertical support column 47 is provided at the center of the lower liquid cooling plate 114, pointing towards the upper liquid cooling plate 112. The height of the support column 47 is equal to the distance between the upper and lower liquid cooling plates, and the support column 47 is a hollow structure with a central liquid cooling pipe 45 vertically arranged inside. The negative terminals of multiple battery cells 46 are located on the lower liquid cooling plate 114, and the positive terminals of the battery cells 46 are attached to tabs 3. The tabs 3 of the battery cells 46 contact the bottom of the upper liquid cooling plate 112, and the multiple battery cells 46 are arranged in a circle. Inside the upper liquid cooling plate 112, the lower liquid cooling plate 114, and the fasteners 44, the gaps between the battery cells 46 are filled with phase change material 43. The phase change material 43 is paraffin wax (with 30 carbon atoms), which is used to absorb and store the heat generated by the battery. The power battery pack is also equipped with a battery thermal management system (BMS) to monitor the cell temperature. The BMS will not be described in detail here.

[0068] The upper liquid cooling plate 112 has an internal upper liquid cooling channel 111, which is a spiral pipe including a first inlet 31 and a first outlet 32. The first inlet 31 is located at the outermost end of the spiral, and the first outlet 32 ​​is located at the center of the spiral. The other end of the first inlet 31 is connected to an external storage tank, which stores liquid cooling medium. The first outlet 32 ​​is connected to one end of the central liquid cooling pipe 45. The flow rate of the working medium inside the upper liquid cooling channel 111 can be changed at any time according to the battery temperature monitored by the BMS. A control valve is provided at the first inlet 31 to adjust the flow rate of the working medium entering the first inlet according to the instructions of the BMS. Moreover, the upper liquid cooling plate has a groove that matches the outer contour of the tab 3 at the contact portion with the top of the cell 46, so that when the upper liquid cooling plate 112 is fastened to the top of the cell 46 as a cover plate, the upper liquid cooling plate and the tab are in full contact.

[0069] The lower liquid cooling plate 114 has a built-in lower liquid cooling channel 113, which is a spiral pipe including a second liquid inlet 41 and a second liquid outlet 42. The second liquid inlet 41 is located at the center of the spiral, and the second liquid outlet 42 is located at the outermost end of the spiral. The second liquid inlet 41 is connected to the other end of the central liquid cooling pipe 45. The first liquid outlet 32 ​​and the second liquid inlet 41 are connected by the central liquid cooling pipe 45. The central liquid cooling pipe 45 is placed inside the support column 47 because the central liquid cooling pipe 45 cannot bear weight. The main function of the support column is to bear weight. In addition, it protects the central liquid cooling pipe 45 from bending when the vehicle shakes. The flow rate of the working fluid inside the lower liquid cooling channel 113 can be changed at any time according to the battery temperature monitored by the BMS. The heat stored in the phase change material 43 is transferred to the upper liquid cooling channel 111 via the upper liquid cooling plate 112, and to the lower liquid cooling channel 113 via the lower liquid cooling plate 114, and is carried away by the working fluid, thereby realizing battery cooling that couples liquid cooling and phase change material.

[0070] The circulation path of the liquid cooling working fluid in the power battery pack is as follows: the working fluid stored in the storage tank is water. The outlet of the storage tank is connected to one end of a water pump through a pipeline. The other end of the water pump enters the first inlet 31 of the upper liquid cooling channel 2 through a control valve. After flowing through the upper liquid cooling channel 2, it flows out from the first outlet 32. Then it flows through the central liquid cooling pipe 7 and enters the second inlet 41. After flowing through the lower liquid cooling channel 4, it flows out from the second outlet 42 and then flows back to the storage tank through the outer channel.

[0071] The control method of the controller is similar to that in Embodiment 1. When the highest monitored temperature of the cell sidewall monitored by the BMS is 25-40℃, the control valve at the first inlet 31 of the upper liquid cooling channel 2 is adjusted to make the working fluid flow rate 0.3m / s. When the highest monitored temperature of the cell is 40-60℃, the control valve at the first inlet 31 is adjusted to make the working fluid flow rate inside the upper and lower liquid cooling channels 0.8m / s. When the highest monitored temperature of the cell is 60-90℃, the control valve at the first inlet 31 is adjusted to make the working fluid flow rate inside the upper and lower liquid cooling channels 1.2m / s. When the highest monitored temperature of the cell exceeds 90℃, the control valve at the first inlet 31 is adjusted to make the working fluid flow rate inside the upper and lower liquid cooling channels 1.2m / s, and the BMS inside the power battery pack is activated to detect whether thermal runaway has occurred in the power battery pack and to extinguish fires. Other fire-fighting measures and the collaborative working mechanism of this invention are not described here.

[0072] Example 3

[0073] This embodiment is basically the same as Embodiment 2, the only difference being that a BMS is not used. Instead, a temperature sensor is installed inside the fastener 44 of the power battery pack (i.e., the contact surface between the wall of the cell 46 and the phase change material). The temperature sensor is electrically connected to the controller to monitor the temperature of the cell. The controller is used to control the valve to adjust the flow rate of the working fluid entering the first inlet according to the temperature indication transmitted by the temperature sensor.

[0074] Although preferred embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these are within the scope of protection of the present invention.

Claims

1. A power battery pack, characterized in that, It includes multiple batteries, a first cooling subsystem, a second cooling subsystem (24), a third cooling subsystem, and a control subsystem; The battery pack consists of multiple battery cells arranged side by side (4). The first cooling subsystem is used to cool and dissipate heat to the top of the battery, including an upper liquid cooling plate (2,112) and an upper liquid cooling channel (1,111) disposed inside the upper liquid cooling plate (2,112), the upper liquid cooling plate (2,112) covering the top of the battery; a first working fluid flows through the upper liquid cooling channel (1,111); The third cooling subsystem is used to cool and dissipate heat at the bottom of the battery, including a lower liquid cooling plate (14, 114) and a lower liquid cooling channel (13, 113). The bottom of the battery cell is placed on top of the lower liquid cooling plate (14, 114); a first working fluid flows through the lower liquid cooling channel (13, 113). The second cooling subsystem (24) is used to cool the battery sidewalls, and a second working fluid is provided in the second cooling subsystem; The control subsystem includes a controller, a temperature sensor (8), and a control valve; the temperature sensor (8) is located at least on the side wall of the battery and is electrically connected to the controller; the control valve is used to adjust at least the first working fluid flow rate according to the controller's indication; the controller is used to adjust the first working fluid flow rate in the first cooling subsystem and the third cooling subsystem according to the temperature monitored by the temperature sensor (8); The second cooling subsystem (24) is used to cool the sidewalls of the battery cells and includes a heat-conducting plate (6), a heat-insulating plate (7), a barrier box (10), and an outer casing (12). A heat-conducting plate (6) and a heat-insulating plate (7) are arranged side by side between each two adjacent battery cells (4). A plurality of fins (9) extend from one side of the heat-conducting plate, and the ends of the fins (9) extend beyond the battery cells (4) and contact the inner wall of the barrier box (10). The heat-conducting plate is used to transfer the heat of its adjacent battery cells (4) to the heat-conducting plate (6) and its fins (9), and the heat-insulating plate (7) is used to block the heat transfer between adjacent battery cells. All of the battery cells (4) are disposed in the barrier box (10), the barrier box (10) is fitted inside the outer box (12), and there is a gap between the two boxes. The gap between the barrier box (10) and the outer box (12) is filled with a second working fluid to form a cooling chamber, which can cool the heat of the fins. Multiple refrigerant channels are provided in the two opposite side walls of the outer casing (12), and a second working fluid flows through the refrigerant channels. The temperature sensor (8) is located on the side wall of the tab (3) and the battery cell (4), respectively. The control valves (19, 23) are located at the liquid inlet and refrigerant inlet of the upper and lower liquid cooling channels, respectively, and are used to adjust the flow rate of the first and second working fluids according to the instructions of the controller. The controller is used to adjust the flow rate of the first and second working fluids in the first cooling subsystem, the second cooling subsystem and the third cooling subsystem according to the temperature monitored by the temperature sensor (8). The cooling control method for the power battery pack includes: The temperature sensor monitors the temperature of the tabs (3) and the sidewalls of the battery cells (4) of the power battery pack in real time and uploads the data to the controller. When the highest monitored temperature of the battery cell sidewall and electrode sidewall is 25-40℃, adjust the control valve (19) at the inlet of the upper and lower liquid cooling channels to make the flow rate of the first working fluid 0.3m / s, and close the control valve (23) at the refrigerant inlet (11) in the second cooling subsystem (24); when the highest monitored temperature of the battery cell sidewall and electrode is 40-60℃, adjust the control valve (19) at the inlet of the upper and lower liquid cooling channels to make the flow rate of the first working fluid inside the upper and lower liquid cooling channels 0.8m / s, and adjust the control valve (23) at the refrigerant inlet (11) of the refrigerant channel to make the flow rate of the second working fluid at the refrigerant inlet (11) 0.5m / s; when the battery cell sidewall and electrode sidewall are ... When the highest monitored temperature of the battery cell sidewall and electrode tab is 60-90℃, adjust the control valve (19) at the liquid inlet of the upper and lower liquid cooling channels to make the flow rate of the first working medium inside the upper and lower liquid cooling channels 1.2m / s, and adjust the control valve (23) at the refrigerant inlet (11) to make the flow rate of the second working medium at the refrigerant inlet 0.8m / s; when the highest monitored temperature of the battery cell sidewall and electrode tab exceeds 90℃, adjust the control valve (19) at the liquid inlet of the upper and lower liquid cooling channels to make the flow rate of the first working medium inside the upper and lower liquid cooling channels 1.2m / s, and adjust the control valve (23) at the refrigerant inlet (11) to make the flow rate of the second working medium at the refrigerant inlet 1m / s.

2. The power battery pack according to claim 1, characterized in that, The battery cell (4) has a top tab (3) on top, and some of the tabs have electrical connection lines (5) on top. The upper liquid cooling channel (1) is laid in an S-shape inside the upper liquid cooling plate (2), and the upper liquid cooling plate (2) is provided with a groove that matches the outer contour of the tab and the electrical connection line at the contact part with the top of the battery cell (4). When the upper liquid cooling plate (2) is fastened to the top of the battery cell (4) as a cover plate for the tab (3) and the electrical connection line (5), the first cooling subsystem is in full contact with the tab (3), and the lower liquid cooling channel is laid in an S-shape inside the lower liquid cooling plate.

3. The power battery pack according to claim 1, characterized in that, The liquid cooling circulation paths of the first and third cooling subsystems are as follows: the first working fluid stored in the first storage tank (16) is water. The outlet of the first storage tank (16) is connected to one end of a water pump (18) through a pipeline (17). The other end of the water pump (18) is divided into two branches. One branch enters the inlet of the upper liquid cooling channel (1) after passing through a control valve (19), flows through the first cooling subsystem, and then flows out from the outlet of the upper liquid cooling channel (1) and then flows back to the first storage tank (16) through the outer channel (20). The other branch enters the lower liquid cooling channel (13) after passing through another control valve (19), flows through the second cooling subsystem, and then flows out from the outlet of the lower liquid cooling channel (13) and then flows back to the first storage tank (16) through the outer channel (20).

4. The power battery pack according to claim 1, characterized in that, The ends of the multiple refrigerant channels located on the same side of the sidewall are refrigerant inlets (11), and the ends located on the other side are refrigerant outlets (15), so that the second working fluid in all the refrigerant channels in the power battery pack flows in the same direction; the liquid cooling circulation path of the second cooling subsystem (24) is as follows: the second working fluid stored in the second liquid tank (21) is liquid nitrogen. The outlet of the second liquid tank (21) flows through a control valve (23) through a pipeline (22) and then connects to the refrigerant inlet (11) through a pipeline (22). Liquid nitrogen flows laterally from the refrigerant inlet along the sidewall of the outer casing (12) and finally flows out from the refrigerant outlet (15). After passing through the outer flow channel (25) and a pressurization device (26), it forms liquid nitrogen again and returns to the second liquid tank (21).

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