Battery thermal management system with staggered heat pipes and control method

Abstract

The invention provides a battery thermal management system with staggered heat pipes and a control method. The battery thermal management system comprises a shell, a heat pipe module, a battery pack module, a control unit module, a thermoelectric device module, a liquid cooling module, a phase change material and a power supply module. According to the system, the phase change and the heat pipe of the passive battery thermal management system are coupled with the liquid cooling and thermoelectric elements of the active battery thermal management system, and the switching between the cold end and the hot end of the thermoelectric device can be changed by changing the direction of the current introduced into the thermoelectric device through temperature monitoring, so that the heat dissipation and preheating requirements of the battery pack can be met at the same time; in consideration of the low thermal conductivity of the phase-change material, a mixed phase-change material composed of pure paraffin, foam metal and paraffin and a mixed phase-change material composed of expanded graphite and paraffin can be adopted, and meanwhile, a large amount of heat can be rapidly transferred under a small temperature difference through the heat pipe so as to remove the heat of the phase-change material.

Description

Technical Field

[0001] The present invention relates to the technical field of battery thermal management, and in particular to a battery thermal management system with staggered heat pipes and a control method. Background Art

[0002] Energy shortage and environmental pollution are the main problems facing the world today. The two main sectors, automobiles and construction, are the main causes of environmental problems. Standard fuel vehicles not only consume a large amount of oil resources, but also produce automobile exhaust and suspended solid particles, which are also the main causes of environmental pollution. In the context of fossil fuel shortage and environmental degradation, electric vehicles are rapidly replacing gasoline or diesel-powered vehicles with serious pollution. Electric vehicles have zero exhaust emissions and are more environmentally friendly. Rechargeable batteries are the main components of electric vehicles. Lead-acid, nickel-cadmium, lithium-ion batteries and nickel metal hydride are commonly used as rechargeable batteries. Lithium-ion batteries have been widely used in electric vehicles and hybrid vehicles due to their long cycle life and energy density. Lithium-ion batteries that can charge and discharge quickly and have high energy density will generate a lot of heat during work. It is crucial to keep these batteries under the optimal operating temperature conditions of about 15℃–35℃, which can not only avoid fatal phenomena such as thermal runaway and lithium plating, but also improve the overall performance, durability, life of the battery and reduce the battery degradation rate. Therefore, the development of an efficient battery thermal management system is urgently needed.

[0003] Among several methods for thermal management of batteries, air cooling and liquid cooling have been successfully commercialized, but the design of such cooling systems is quite complex due to the number of connections, making them more prone to failure risks. In addition, air-cooled battery thermal management methods are only suitable for low-density batteries due to their low thermal conductivity, poor heat dissipation between batteries, and less air heat capacity. The main challenge of liquid-cooled battery thermal management systems is their complex structure, which increases cost and size as well as the possibility of leakage. The main problem of phase-change-based battery thermal management methods is the low thermal conductivity. Although the addition of nanoparticles improves the thermal conductivity of PCM, these additives still reduce some of the properties of PCM. Due to its limited heat storage capacity, it has been found that battery thermal management systems using PCM cannot operate for a long time. In the case of PCM-based battery thermal management systems, the problem of successfully removing heat from PCM must be discussed. Heat pipes are a heat transfer medium that works through the liquid-gas phase transition of the working fluid. The most important feature of heat pipes is that they can transport heat even at very low temperature gradients. This phenomenon can be used to remove heat generated in lithium-ion batteries and phase change materials from the battery surface by conducting heat. The battery thermal management method based on thermoelectric cooling utilizes the Peltier effect of thermoelectric devices, that is, when current is passed through, one end of the thermoelectric device absorbs heat and the other end releases heat, and when the current direction is changed, the heat-absorbing and heat-releasing ends will also be changed accordingly. This feature greatly facilitates battery thermal management, but it will cause uneven temperature distribution of the battery pack module to a certain extent, so it needs to be coordinated with other methods to complete the thermal management of the battery. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a battery thermal management system and a control method with a staggered arrangement of heat pipes, which solve the problems of low heat dissipation efficiency and poor thermal conductivity of phase change materials in conventional battery thermal management systems in the prior art.

[0005] According to an embodiment of the present invention, a battery thermal management system with staggered heat pipe arrangement, integrated phase change material and thermoelectric devices includes: a housing, a heat pipe module, a battery pack module, a control unit module, a thermoelectric device module, a liquid cooling module, a phase change material, and a power module.

[0006] Preferably, the shell is an aluminum hollow rectangular structure, and cylindrical holes matching the size of the heat pipes are punched around the shell, into which the heat pipes in the heat pipe module are tightly inserted.

[0007] Preferably, the heat pipe module is divided into two types of heat pipes, namely heat pipes and heat pipes, which are inserted into the cylindrical holes punched in the outer shell. The heat pipes are divided into an evaporation section, an insulation section and a condensation section. Two heat pipes will be inserted into each pair of holes, and the evaporation sections are closely adjacent to each other, and the condensation section is inserted into the section outer shell.

[0008] Preferably, the battery pack module is composed of cylindrical battery cells of the same size, each battery cell is inserted in the center of the square frame formed by the heat pipe module, and the bottom of the battery cell is tightly embedded with the bottom surface of the shell.

[0009] Preferably, the control unit module is composed of an internal temperature sensor and a control unit. The i-th temperature sensor is placed on the outer surface of the i-th battery cell. There will be i temperatures, which are respectively recorded as T i , after a certain time interval △t, the temperature data T i The control unit processes the i temperature data so that the operating instruction temperature T C ={T i}max, operating instruction temperature T C Set the temperature T with the control unit min 、T max By comparison and judgment, the switching of various working modes of the thermoelectric device module and the liquid cooling module can be realized.

[0010] Preferably, the thermoelectric device module is composed of four thermoelectric devices of the same size, which are divided into two groups. The thermoelectric devices in each group are connected in series, and each group is tightly attached to the front and rear surfaces of the shell and maintains a certain distance from the left and right and upper and lower surfaces of the shell.

[0011] Furthermore, the thermoelectric device consists of an upper ceramic heat conductive plate, a lower ceramic heat conductive plate and a PN semiconductor component. The upper ceramic heat conductive plate is tightly attached to the outer wall surface of the shell, the lower ceramic heat conductive plate is tightly attached to the outer surface of the liquid cooling plate, and the PN semiconductor component is distributed between the upper ceramic heat conductive plate and the lower ceramic heat conductive plate.

[0012] Preferably, the liquid cooling module consists of a liquid cooling plate, a circulating water pump and a constant temperature liquid tank, wherein the length of the liquid cooling plate is the same as that of a group of thermoelectric devices, has a certain thickness, has holes punched inside for the cooling medium to flow in, and is provided with a water outlet and a water inlet connected to the circulating water pump. The circulating water pump changes its working state according to the operating instructions of the control unit and the voltage output of the power module: operation and standby.

[0013] Preferably, the phase change material will be filled in the internal space of the battery casing excluding the heat pipe module and the battery pack module. The phase change material filled inside can be but is not limited to pure paraffin or a low thermal conductivity phase change material with a small amount of fins, foam metal or expanded graphite added.

[0014] Preferably, the power module will change the magnitude and direction of the voltage and current under the operating instructions of the control unit to adjust the working state of the circulating water pump, and at the same time change the direction of the current passing through the thermoelectric device module to control the working state of the thermoelectric device module.

[0015] Preferably, the contact surfaces between the shell and each battery cell of the battery pack module, the contact surfaces between the shell and the heat pipes of the heat pipe module, the contact surfaces between the shell and the thermoelectric device module, and the contact surfaces between the thermoelectric device module and the liquid cooling plate of the liquid cooling module are provided with thermal conductive silicone grease to reduce the contact thermal resistance and increase the heat transfer efficiency.

[0016] Preferably, the battery thermal management system of the present invention uses a control unit to assist the power supply module to respectively complete the mutual switching of multiple working modes of the thermoelectric device module and the liquid cooling module. The thermoelectric device module mainly performs thermal management on the battery pack module and the phase change material, and the liquid cooling module mainly performs thermal management on the thermoelectric device module. The control unit processes i temperature data so that the operating instruction temperature T C ={T i}max, operating instruction temperature T C Set the temperature T with the control unit min 、T max By comparison and judgment, the switching of various working modes of the thermoelectric device module and the liquid cooling module can be realized.

[0017] Furthermore, the thermoelectric device module has three working modes: cooling, stopping and heating. The control unit controls the operating instruction temperature T according to the set temperature. C After receiving the judgment signal, the power module switches the thermoelectric device module between three working modes:

[0018] When the operating instruction temperature T C Greater than or equal to T max When the power module passes a forward current to each thermoelectric device in the thermoelectric device module, the temperature of the upper ceramic heat conductive plate of the thermoelectric element begins to drop and becomes a cooling end, cooling the battery cells, phase change materials and heat pipe modules in the battery pack module. However, when the thermoelectric element passes a forward current, the temperature of the lower ceramic heat conductive plate begins to rise and becomes a heating end. If the temperature of the lower ceramic heat conductive plate is too high, it will affect the cooling effect of the upper ceramic heat conductive plate. At this time, a liquid cooling module is used to cool the lower ceramic heat conductive plate of the thermoelectric element.

[0019] When the operating instruction temperature T C Greater than T min Less than T max When the power module no longer continues to supply current to the thermoelectric devices in the thermoelectric device module, the thermoelectric device module stops working, and at this time, the battery pack module is thermally managed only by the phase change material;

[0020] When the operating instruction temperature T C Less than or equal to T minWhen the power module passes a reverse current to each thermoelectric element in the thermoelectric device module, the temperature of the upper ceramic heat conductive plate of the thermoelectric element begins to rise and becomes the heating end, heating the batteries and phase change materials in the battery pack module. However, when the thermoelectric element passes a reverse current, the temperature of the lower ceramic heat conductive plate will correspondingly begin to decrease and become the cooling end. If the temperature of the lower ceramic heat conductive plate is too low, it will affect the heating effect of the upper ceramic heat conductive plate. Therefore, a liquid cooling module is used at this time to insulate the lower ceramic heat conductive plate of the thermoelectric element.

[0021] Preferably, the liquid cooling module has two working modes: running and standby. The circulating water pump keeps the cooling medium in a certain temperature range and pumps it into the liquid cooling plate:

[0022] When the operating instruction temperature T C Greater than or equal to T max When or the operating instruction temperature T C Less than or equal to T min , the power module applies voltage and current to the circulating water pump, and the circulating water pump pumps the cooling medium or the heat preservation medium into the liquid cooling plate at a certain flow rate to meet the heat dissipation, preheating requirements or heating and heat preservation requirements of the battery module;

[0023] When the operating instruction temperature T C Greater than T min Less than T max When the power module stops supplying current to the circulating water pump, the circulating water pump is in standby state, and the liquid cooling plate no longer supplies cooling medium.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. A battery thermal management system with staggered heat pipe arrangement, integrated phase change materials and thermoelectric devices is provided, which couples the phase change and heat pipes of passive battery thermal management with the liquid cooling and thermoelectric elements of active battery thermal management, which can meet the heat dissipation requirements of the battery pack module and the preheating requirements of the battery pack.

[0026] 2. The present invention fills the outside of the battery pack module with phase change material, absorbs and releases a large amount of heat through the phase change of the phase change material. Considering the low thermal conductivity of the phase change material, a composite phase change material can be used. A heat pipe is used in the battery thermal management system, which can quickly transfer a large amount of heat under a small temperature difference, overcome the disadvantage of low thermal conductivity of the phase change material, and enable the thermoelectric device module to perform good thermal management of the overall battery pack module;

[0027] 3. The liquid cooling module and thermoelectric device module of the battery thermal management system of the present invention both have multiple working modes. Considering the maximum guarantee that the battery pack module operates at an appropriate temperature, the present invention uses the maximum temperature to ensure the working reliability of the battery thermal management system. When the thermoelectric device module operates in the heating or cooling mode, the liquid cooling module starts to work to keep the thermoelectric device module warm or dissipate heat. When the thermoelectric device module is on standby, the liquid cooling module also stops working, thereby ensuring that the battery operates at an appropriate temperature to the maximum extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic diagram of a battery thermal management system with staggered heat pipes, integrated phase change materials and thermoelectric devices according to the present invention; Figure 2 It is a top view of the combination of the housing, battery pack module, heat pipe module, thermoelectric device module, and liquid cooling module of the battery thermal management system of the present invention; Figure 3 AA cross-sectional schematic diagram of the battery thermal management system of the present invention; Figure 4 A schematic diagram of a thermoelectric device module of a battery thermal management system of the present invention; Figure 5 It is a schematic top view of a liquid cooling plate of a battery thermal management system of the present invention; Figure 6 It is a top view of the housing and phase change material combination of the battery thermal management system of the present invention; In the figure, 1, housing; 2, heat pipe module; 3, battery pack module; 4, control unit module; 5, thermoelectric device module; 6, liquid cooling module; 7, phase change material; 8, power module; 201, first type heat pipe; 202, second type heat pipe; 301, battery cell; 401, temperature sensor; 402, control unit; 501, upper ceramic heat conductive plate; 502, lower ceramic heat conductive plate; 503, PN junction; 601, liquid cooling plate; 602, circulating water pump; 603, constant temperature liquid tank.

[0029] Figure 2 It is a top view of the combination of the housing, battery pack module, heat pipe module, thermoelectric device module, and liquid cooling module of the battery thermal management system of the present invention;

[0030] Figure 3 AA cross-sectional schematic diagram of the battery thermal management system of the present invention;

[0031] Figure 4 A schematic diagram of a thermoelectric device module of a battery thermal management system of the present invention;

[0032] Figure 5 It is a schematic top view of a liquid cooling plate of a battery thermal management system of the present invention;

[0033] Figure 6 It is a top view of the housing and phase change material combination of the battery thermal management system of the present invention;

[0034] In the figure, 1, housing; 2, heat pipe module; 3, battery pack module; 4, control unit module; 5, thermoelectric device module; 6, liquid cooling module; 7, phase change material; 8, power module; 201, first type heat pipe; 202, second type heat pipe; 301, battery cell; 401, temperature sensor; 402, control unit; 501, upper ceramic heat conductive plate; 502, lower ceramic heat conductive plate; 503, PN junction; 601, liquid cooling plate; 602, circulating water pump; 603, constant temperature liquid tank. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0036] like Figure 1 The figure shows a schematic diagram of a battery thermal management system of the present invention that integrates phase change materials and thermoelectric devices with staggered heat pipe arrangement, including: a housing 1, a heat pipe module 2, a battery pack module 3, a control unit module 4, a thermoelectric device module 5, a liquid cooling module 6, a phase change material 7, and a power module 8.

[0037] like Figure 2 The figure shows a top view of the combination of the shell, battery pack module, heat pipe module, thermoelectric device module and liquid cooling module of the battery thermal management system of the present invention. The shell 1 is a hollow, uncovered rectangular structure made of aluminum, and cylindrical holes matching the size of the heat pipes are punched around the shell. The first type of heat pipe 201 and the second type of heat pipe 202 in the heat pipe module 2 are tightly inserted therein, and the battery cell in the battery pack module 3 is inserted in the center of the square frame formed by the heat pipe module 2. The bottom of the battery cell 301 is attached to the inner surface of the shell 1, and the two thermoelectric devices of the thermoelectric device module 5 are closely arranged together. The upper ceramic heat conductive plate 501 is closely attached to the front and rear surfaces of the shell 1, and the lower ceramic heat conductive plate is closely attached to the outer surface of the liquid cooling plate 601, wherein the upper ceramic heat conductive plate 501 is symmetrically placed on the outer surface of the shell 1.

[0038] like Figure 3 The figure shows the AA cross-sectional schematic diagram of the battery thermal management system of the present invention. The shell 1 is a hollow, lidless, aluminum rectangular structure. The surrounding shell is punched with cylindrical holes matching the size of the heat pipes. The first type of heat pipe 201 and the second type of heat pipe 202 in the heat pipe module 2 are tightly inserted therein. The battery cell in the battery pack module 3 is inserted in the center of the square frame formed by the heat pipe module 2. The bottom of the battery cell 301 is attached to the inner surface of the shell 1, and the phase change material 7 is filled in the internal space of the shell 1.

[0039] like Figure 4The figure shows a schematic diagram of a thermoelectric device module of a battery thermal management system of the present invention. The thermoelectric device consists of an upper ceramic heat conducting plate 501, a lower ceramic heat conducting plate 502 and a PN junction 503 semiconductor component. The upper ceramic heat conducting plate 501 is closely attached to the outer wall surface of the housing 1, the lower ceramic heat conducting plate 502 is closely attached to the outer surface of the liquid cooling plate 601, and the PN junction 503 semiconductor component is distributed between the upper ceramic heat conducting plate 501 and the lower ceramic heat conducting plate 502.

[0040] like Figure 5 The figure shows a schematic top view of the liquid cooling plate of the battery thermal management system of the present invention. The liquid cooling plate 601 is provided with a water outlet and a water inlet. At the same time, pipes of a certain diameter and a certain length are provided inside the liquid cooling plate. These pipes are symmetrically distributed inside the liquid cooling plate.

[0041] like Figure 2 , Figure 3 and Figure 6 As shown, the heat pipe module 2 and the battery pack module 3 are inserted into the internal space of the outer shell 1 as required. In addition, the internal space of the outer shell 1 will be filled with phase change material 7, and the first type of heat pipe 201 and the second type of heat pipe 202 are inserted into the holes drilled in the outer shell 1. Both ends of the first type of heat pipe 201 and the second type of heat pipe 202 do not exceed the surface of the outer shell 1.

[0042] The contact surfaces between the shell 1 of this embodiment and the battery cells of the battery pack module 3, the contact surfaces between the shell 1 and the first type of heat pipe 201 and the second type of heat pipe 202 of the heat pipe module 2, the contact surfaces between the shell 1 and the thermoelectric device module 5, and the contact surfaces between the thermoelectric device module 5 and the liquid cooling plate 601 of the liquid cooling module 6 are covered with thermal conductive silicone grease to reduce contact thermal resistance and increase heat transfer efficiency.

[0043] like Figure 1 As shown, the control unit module 4 is composed of a temperature sensor 401 and a control unit 402, wherein the temperature sensor 401 is arranged in the middle of the surface of each battery cell 301, and the control unit 402 receives the temperature collected by each temperature sensor 401 to perform the next operation.

[0044] The temperature sensor 401 of this embodiment transmits the measured temperature to the control unit 402 at a specified time interval △t after the system is working. The control unit 402 issues the next operation instruction after processing the temperature information. The power module 8 receives the operation instruction and adjusts the power supply voltage and direction to the circulating water pump 602 and the thermoelectric device module 5.

[0045] In this embodiment, the control unit module 4 assists the power supply module 8 to respectively complete the switching of the thermoelectric device module 5 and the liquid cooling module 6 in various working modes. Considering that the thermoelectric device module 5 mainly performs thermal management on the batteries in the battery pack module 3, the temperature of the i-th battery cell 301 measured by the temperature sensor 401 is respectively recorded as T i , the control unit 402 processes i temperature data so that the operation instruction temperature T C ={T i}max, operating instruction temperature T C The control unit sets the temperature T min 、T max Comparison and judgment are performed to switch between various working modes of the thermoelectric device module 5 and the liquid cooling module 6 .

[0046] The thermoelectric device module 5 of this embodiment has three working modes: cooling, stopping and heating. The control unit 402 obtains the operating instruction temperature T according to the setting. C After receiving the judgment signal, the power module 8 switches the thermoelectric device module 5 between the three working modes:

[0047] When the operating instruction temperature T C Greater than or equal to T max When the power module 8 passes a forward current to each thermoelectric device in the thermoelectric device module 5, the temperature of the upper ceramic heat conductive plate 501 of the thermoelectric element begins to drop and becomes a cooling end, cooling the battery cells 301, the phase change material 7 and the heat pipe module 2 in the battery pack module 3. However, when the thermoelectric element passes a forward current, the temperature of the lower ceramic heat conductive plate 502 begins to rise and becomes a heating end. If the temperature of the lower ceramic heat conductive plate 502 is too high, it will affect the cooling effect of the upper ceramic heat conductive plate 501. At this time, the liquid cooling module 6 is used to cool the lower ceramic heat conductive plate 502 of the thermoelectric element.

[0048] When the operating instruction temperature T C Greater than T min Less than T max When the power module 8 no longer continues to supply current to the thermoelectric devices in the thermoelectric device module 5, the thermoelectric device module 5 stops working, and at this time, the battery module 3 is thermally managed only by the phase change material 7;

[0049] When the operating instruction temperature T C Less than or equal to T minWhen the power module 8 passes a reverse current to each thermoelectric element in the thermoelectric device module 5, the temperature of the upper ceramic heat conductive plate 501 of the thermoelectric element begins to rise and becomes a heating end, thereby heating the batteries and phase change material 7 in the battery pack module 3. However, when the thermoelectric element passes a reverse current, the temperature of the lower ceramic heat conductive plate 502 begins to decrease and becomes a cooling end. If the temperature of the lower ceramic heat conductive plate 502 is too low, it will affect the heating effect of the upper ceramic heat conductive plate 501. Therefore, at this time, the liquid cooling module 6 is used to insulate the lower ceramic heat conductive plate 502 of the thermoelectric element.

[0050] The liquid cooling module 6 of this embodiment has two working modes: operation and standby. The circulating water pump 602 keeps the cooling medium in a certain temperature range and pumps it into the liquid cooling plate 601:

[0051] When the operating instruction temperature T C Greater than or equal to T max When or the operating instruction temperature T C Less than or equal to T min , the power module 8 applies voltage and current to the circulating water pump 602, and the circulating water pump 602 pumps the cooling medium or the heat preservation medium into the liquid cooling plate 601 at a certain flow rate to meet the heat dissipation, preheating requirements or heating and heat preservation requirements of the battery module 3;

[0052] When the operating instruction temperature T C Greater than T min Less than T max When , the power module 8 stops supplying current to the circulating water pump 602 , and the circulating water pump 602 is in a standby state. At this time, the liquid cooling plate 601 no longer supplies cooling medium.

[0053] The battery pack module 3 of the battery thermal management system described in the present invention is filled with phase change material on the outside, and a large amount of heat is absorbed and released through the phase change of the phase change material. Considering the low thermal conductivity of the phase change material, a composite phase change material can be used. The phase change material 7 can be pure paraffin, a mixed phase change material composed of foam metal and paraffin, or a mixed phase change material composed of expanded graphite and paraffin. The use of heat pipes in the battery thermal management system can quickly transfer a large amount of heat under a small temperature difference, overcoming the disadvantage of low thermal conductivity of the phase change material, so that the thermoelectric device module can perform good thermal management of the overall battery pack module.

Claims

1. A battery thermal management system with staggered heat pipe arrangement, characterized in that: The invention comprises a rectangular parallelepiped structure housing (1) which is hollow inside and open at the top, a heat pipe module (2) and a battery module (3) fixedly arranged in the housing (1), a thermoelectric device module (5) fixed to the outer side wall opposite to the housing (1), and a liquid cooling module (6) connected to the thermoelectric device module (5), and a control unit module (4) is connected between a power module (8) outside the housing (1) and the heat pipe module (2).

2. The battery thermal management system with staggered heat pipe arrangement as claimed in claim 1, characterized in that: The heat pipe module (2) comprises first-type heat pipes (201) arranged equidistantly in the longitudinal direction and second-type heat pipes (202) arranged equidistantly in the transverse direction, the first-type heat pipes (201) and the second-type heat pipes (202) being arranged in layers, the battery pack module (3) comprising a plurality of battery cells (301), the battery cells (301) being located in a rectangular cavity formed by the first-type heat pipes (201) and the second-type heat pipes (202), the bottom ends of the battery cells (301) being embedded in the inner bottom wall of the outer shell (1), and the outer shell (1) being further filled with a phase change material (7).

3. The battery thermal management system with staggered heat pipe arrangement as claimed in claim 2, characterized in that: A through hole penetrating through the opposite side wall is provided on the side wall of the shell (1); the first type of heat pipe (201) and the second type of heat pipe (202) both comprise an evaporation section, an insulation section and a condensation section; the condensation sections of the first type of heat pipe (201) and the second type of heat pipe (202) are both located in the corresponding through hole; and the condensation sections are both located inside the shell (1).

4. The battery thermal management system with staggered heat pipe arrangement as claimed in claim 3, characterized in that: The control unit module (4) comprises a temperature sensor (401) and a control unit (402) whose signal is connected to the temperature sensor (401); the temperature sensor (401) is arranged on the outer side wall of the battery cell (301).

5. The battery thermal management system with staggered heat pipe arrangement as claimed in claim 2, characterized in that: The phase change material (7) is selected from pure paraffin, a mixture of foamed metal and paraffin, or a mixture of expanded graphite and paraffin.

6. The battery thermal management system with staggered heat pipe arrangement as claimed in claim 1, characterized in that: The thermoelectric device module (5) comprises an upper ceramic heat conducting plate (501), a lower ceramic heat conducting plate (502), and a PN junction (503) located between the upper ceramic heat conducting plate (501) and the lower ceramic heat conducting plate (502); the upper ceramic heat conducting plate (501) is closely attached to the front and rear outer side walls of the housing (1), and the lower ceramic heat conducting plate (502) is closely attached to the side wall of the liquid cooling module (6).

7. The battery thermal management system with staggered heat pipe arrangement as claimed in claim 1, characterized in that: The liquid cooling module (6) comprises a liquid cooling plate (601) filled with a cooling medium, a constant temperature liquid tank (603), and a circulating water pump (602) connecting the liquid cooling plate (601) and the constant temperature liquid tank (603); a continuously bent pipe is arranged inside the liquid cooling plate (601); and a water inlet and a water outlet are arranged on the end wall of the liquid cooling plate (601).

8. The control method of the battery thermal management system with staggered heat pipe arrangement as claimed in claim 1, characterized in that: The method comprises the following steps: a control unit module (4) measures the temperature of a battery pack module (3) at a prescribed time interval after the system is operating, and compares the measured temperature information with a set operating temperature range, controls a power supply module (8) to adjust the supply voltage and operating direction of a thermoelectric device module (5), switches the operating mode of the thermoelectric device module (5), wherein the thermoelectric device module (5) comprises three operating modes: cooling, stopping and heating, controls a liquid cooling module (6) to perform heat exchange, switches the operating mode of the liquid cooling module (6), wherein the liquid cooling module (6) comprises two operating modes: operation and standby.

9. The control method of the battery thermal management system with staggered heat pipe arrangement as claimed in claim 8, characterized in that: The cooling mode is that when the measured temperature is greater than or equal to the set maximum temperature, the power module (8) passes a forward current to each thermoelectric device in the thermoelectric device module (5), and the temperature of the ceramic heat conductive plate (501) on the hot spot element begins to drop and becomes a cooling end, thereby cooling the battery cells (301), the phase change material (7) and the heat pipe module (2) in the battery pack module (3). However, when the thermoelectric element is flowing with a forward current, the temperature of the lower ceramic heat conductive plate (502) begins to rise and becomes a heating end. If the temperature of the lower ceramic heat conductive plate (502) is too high, it will affect the cooling effect of the upper ceramic heat conductive plate (501). At this time, the liquid cooling module (6) is used to cool the lower ceramic heat conductive plate (502) of the thermoelectric element. The stop mode is that the power module (8) no longer continues to pass current to each thermoelectric device in the thermoelectric device module (5), and the thermoelectric device module (5) stops working. At this time, the battery pack module (3) is thermally managed only by the phase change material (7). The heating mode is that the power module (8) passes a reverse current to each thermoelectric element in the thermoelectric device module (5), and the temperature of the upper ceramic heat conductive plate (501) of the thermoelectric element begins to rise and becomes a heating end, thereby heating the battery and the phase change material (7) in the battery pack module (3). However, when the thermoelectric element passes a reverse current, the temperature of the lower ceramic heat conductive plate (502) begins to decrease and becomes a cooling end. If the temperature of the lower ceramic heat conductive plate (502) is too low, it will affect the heating effect of the upper ceramic heat conductive plate (501). Therefore, the liquid cooling module (6) is used to perform heat preservation treatment on the lower ceramic heat conductive plate (502) of the thermoelectric element.

10. The control method of the battery thermal management system with staggered heat pipe arrangement as claimed in claim 8, characterized in that: The operation mode is that when the detected temperature is not within the set temperature range, the power module (8) applies voltage and current to the circulating water pump (602), and the circulating water pump (602) pumps cooling medium or thermal insulation medium into the liquid cooling plate (601) at a certain flow rate to meet the heat dissipation, preheating requirements or heating and thermal insulation requirements of the battery pack module (3); the standby mode is that when the detected temperature is within the set temperature range, the power module (8) stops supplying current to the circulating water pump (602), and the circulating water pump (602) is in a standby state, at which time the cooling medium is no longer supplied to the liquid cooling plate (601).

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