Power battery thermal management system and thermal management method

Abstract

The invention relates to the technical field of power battery thermal management, in particular to a power battery thermal management system and a thermal management method. Comprising a cockpit flow path; the system comprises an evaporator, a power battery flow path, a cooling structure and a control structure, and the power battery flow path is a refrigerant flow path with the two ends communicating with an inlet side pipeline and an outlet side pipeline of the evaporator correspondingly. The power battery flow path is provided with a heat exchange structure used for conducting heat exchange on a plurality of subsequent battery packs of the power battery and a valve structure used for controlling on-off of the power battery flow path. The cooling structure is arranged at the front end of the power battery and is used for cooling the power battery; the control structure controls the valve structure based on the battery pack temperature difference of the power battery. The thermal management system solves the problem of high temperature after forced convection heat dissipation, keeps temperature uniformity between power battery packs, ensures continuous and efficient work of power batteries under dynamic charging and discharging power, and ensures normal service life of the power batteries.

Description

Technical Field

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

[0002] The power battery system of current new energy vehicles includes multiple battery packs. The thermal management system of existing power battery systems mostly adopts a single system method of air cooling or liquid cooling. The existing method cannot well ensure the uniformity of temperature between battery packs, and the temperature of the battery pack in the later part of the flow path is relatively high. If reverse flow heat exchange is adopted, the temperature of the battery pack in the middle part is generally high. At the same time, although the cooling effect of the liquid cooling plate alone is relatively better than that of air cooling, this method sacrifices the thermal comfort of part of the cockpit, and the temperature uniformity is not good. In addition, the charging and discharging power of the power battery pack changes dynamically according to the form and charging conditions, so the heat generation is also dynamic. The existing technology is not timely enough in responding to the feedback of dynamic power, and lacks corresponding control methods. Summary of the invention

[0003] The purpose of this application is to address the deficiencies of the above-mentioned background technology and to provide a power battery thermal management system and a thermal management method.

[0004] The technical solution of the present application is: a power battery thermal management system, including a cockpit flow path; the cockpit flow path includes a compressor, a gas-liquid separator, a condenser, an air conditioning loop electronic expansion valve and an evaporator connected in series by pipelines; a blower is provided on one side of the evaporator, and further includes,

[0005] A power battery flow path, wherein the power battery flow path is a refrigerant flow path whose two ends are respectively connected to the inlet and outlet pipes of the evaporator, and a heat exchange structure for performing heat exchange on a plurality of battery packs in the rear stage of the power battery and a valve structure for controlling the on-off of the power battery flow path are provided on the power battery flow path;

[0006] A cooling structure, which is arranged at the front end of the power battery and is used to cool the power battery;

[0007] A control structure controls the valve structure based on a battery pack temperature difference of the power battery.

[0008] According to a power battery thermal management system provided by the present application, the control structure includes:

[0009] A thermoelectric module, the thermoelectric module is used to convert the temperature difference of a plurality of battery packs corresponding to the power battery flow path into an electric potential;

[0010] A potential difference acquisition module, wherein the potential difference acquisition module is used to collect the potential difference of the thermoelectric module;

[0011] A control module is provided to adjust the opening of the valve structure based on the potential difference.

[0012] According to a power battery thermal management system provided by the present application, the control structure further includes:

[0013] A front-end temperature acquisition module, which is used to collect the temperature of the power battery forward battery pack;

[0014] The rear-end temperature acquisition module is used to collect the temperature of the rear-end battery pack of the power battery.

[0015] According to a power battery thermal management system provided by the present application, the heat exchange structure includes a liquid cooler for exchanging heat with a plurality of battery packs in the rear stage of the power battery.

[0016] According to a power battery thermal management system provided by the present application, the valve structure includes an electric valve, a battery loop electronic expansion valve and a check valve electrically connected to the control structure; the electric valve is arranged between the power battery flow path inlet end and the liquid cooler; the battery loop electronic expansion valve is arranged between the electric valve and the liquid cooler; the check valve is arranged between the liquid cooler and the power battery flow path outlet end.

[0017] According to a power battery thermal management system provided in the present application, the cooling structure includes an axial flow fan arranged at the front end of the power battery.

[0018] The present application also provides a power battery thermal management method, the thermal management method is used to operate any of the above-mentioned power battery thermal management systems, including:

[0019] When the vehicle is started and the power battery starts working, the temperature of the power battery is collected, and based on the temperature of the power battery, it is determined whether the power battery needs to be cooled;

[0020] When the power battery needs to be cooled, the battery pack temperature of the power battery and the potential difference of thermoelectric modules of several battery packs in the rear of the power battery are collected, and the opening of the valve structure is adjusted based on the potential difference and the battery pack temperature.

[0021] According to a power battery thermal management method provided in the present application, the method for judging whether the power battery needs to be cooled based on the power battery temperature includes: collecting the temperatures of several battery packs ahead of the power battery, and when the maximum temperature of the several battery packs ahead is not less than a first temperature threshold, judging that the power battery needs to be cooled, turning on the axial flow fan at the front end of the power battery, and opening the electric valve in the valve structure and maintaining it at the set initial opening.

[0022] According to a power battery thermal management method provided in the present application, the method for adjusting the opening of the valve structure based on the potential difference and the battery pack temperature includes: obtaining the potential difference of thermoelectric modules of several groups of battery packs in the later stage of the power battery, and adjusting the opening of the electric valve in the valve structure in such a manner that the greater the potential difference, the greater the opening of the electric valve.

[0023] According to a power battery thermal management method provided in the present application, the method for adjusting the opening of the valve structure based on the potential difference and the battery pack temperature includes: when the opening of the electric valve is fully open, obtaining the maximum temperature of several battery packs in the rear stage of the power battery, and if the maximum temperature is not lower than the second temperature threshold, adjusting the opening of the battery loop electronic expansion valve in the valve structure, and adjusting the opening of the battery loop electronic expansion valve in such a manner that the more the maximum temperature exceeds the second temperature threshold, the larger the opening of the battery loop electronic expansion valve.

[0024] The advantages of the present application are as follows: 1. The present application adopts two sets of cooling structures for the power battery. The cooling structure is specifically used to dissipate heat for the front-end battery pack of the power battery, and the power battery flow path is specifically used to dissipate heat for the rear-end battery pack of the power battery. The power battery flow path uses the refrigerant of the cockpit flow path. Only when the power battery needs to be dissipated, the refrigerant of part of the cockpit flow path will be used for cooling and cooling, which can avoid the problem of excessive sacrifice of cockpit cooling in the prior art, and at the same time ensure that the battery packs of the entire power battery always maintain a good working temperature. The problem of large temperature difference caused by inconsistent front and rear heat dissipation can be well solved. By controlling the power battery flow path through the control structure, the temperature of the rear-end battery pack of the power battery can be quickly adjusted accurately and timely, and the control accuracy and efficiency are extremely high;

[0025] The thermal management system of the present application suppresses the local high temperature of the power battery in the later stage of air cooling and liquid cooling, and flexibly controls the liquid cooling system according to the actual heat generation, especially in the case of excessive temperature difference of the battery components, so as to timely eliminate the high temperature, thereby ensuring that the power battery pack of the new energy vehicle can work stably and efficiently under dynamic power, and prolong the service life of the power battery. This system has no hysteresis, is easy to adjust, and does not consume extra energy;

[0026] 2. The control structure of the present application includes multiple potential acquisition modules. The control structure of the present application is not only controlled from the temperature level. The present application collects the potential difference of the thermoelectric module of the battery pack and analyzes the temperature difference based on the potential difference. The acquisition of the potential difference is more efficient and the response to the temperature change is more timely. The temperature difference change can be acquired quickly and efficiently, which is convenient for timely temperature adjustment of the battery pack, with rapid feedback and precise control.

[0027] 3. The control structure of the present application also involves a temperature acquisition module. By acquiring the front-end temperature and the rear-end temperature, the current temperature of the battery pack can be intuitively obtained. In combination with the potential difference acquisition, the temperature of the battery pack can be accurately controlled. The overall adjustment method is simple and the temperature adjustment is accurate.

[0028] 4. The heat exchange structure of the present application includes a liquid cooler, which is connected to the cockpit flow path through a pipeline structure. The refrigerant flowing through the cockpit flow path can exchange heat with the downstream battery pack in the liquid cooler. The refrigerant can take away the heat of the downstream battery pack to achieve the purpose of cooling it. The liquid cooler has a simple structure, is easy to use, has high heat exchange efficiency, and cools quickly.

[0029] 5. The valve structure of the present application includes an electric valve, a battery loop electronic expansion valve and a check valve. The electric valve is used to control the flow rate of the refrigerant in the entire power battery flow path. The battery loop electronic expansion valve can control the coldness of the refrigerant in the power battery flow path by throttling. The check valve controls the flow direction of the refrigerant in the power battery flow path, so that the power battery flow path can operate efficiently and the subsequent battery pack can be efficiently temperature regulated and controlled.

[0030] 6. The cooling structure of the present application includes an axial flow fan, which is arranged at the front end of the power battery and dissipates heat from the power battery by air cooling, which is equivalent to integrating the two modes of air cooling and liquid cooling in the thermal management system of the power battery. The axial flow fan has a simple structure and is easy to use;

[0031] 7. The present application also relates to a thermal management method. The thermal management method of the present application can efficiently perform thermal management on power batteries, and has good control over the temperature difference of the battery pack of the power battery. The overall control is extremely efficient and rapid, and can be quickly regulated through the potential difference of the thermoelectric module, with timely feedback, thus avoiding the problem of large changes in the temperature difference of the battery pack.

[0032] 8. This application determines whether heat dissipation is required by collecting the maximum temperature of the Qiancheng battery pack. The Qiancheng battery pack represents the general situation of the current power battery. The temperature of the Qiancheng battery pack can be used to determine whether heat dissipation is currently required. The judgment method is simple and heat dissipation regulation is also extremely convenient;

[0033] 9. This application is to perform thermal management and control of the subsequent battery pack by collecting the potential difference of the thermoelectric modules of several subsequent battery packs. When the potential difference is large, it proves that the temperature difference of the battery pack has a tendency to increase. The heat dissipation control is performed by the potential difference, the feedback is very rapid, and the control accuracy is extremely high;

[0034] 10. The present application has made control settings for extreme situations. When the electric valve is fully open but the temperature of the rear-stage battery pack is still too high, the opening of the battery loop electronic expansion valve can be adjusted. The throttling effect of the battery loop electronic expansion valve can be used to adjust the coolness of the refrigerant, so that the refrigerant with a lower temperature can exchange heat in the liquid cooler, thereby achieving a more efficient heat dissipation effect.

[0035] The thermal management system of the present application can well solve the problem of temperature difference of power battery packs, can efficiently and quickly adjust the temperature of power battery packs, realize precise thermal management of new energy vehicle power batteries, solve the high temperature problem in the later stage of forced convection heat dissipation, maintain temperature uniformity between power battery packs, and keep them in a suitable operating temperature range to prevent thermal runaway, thereby ensuring the continuous and efficient operation of the power battery under dynamic charging and discharging power, and ensuring the normal service life of the power battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 : Schematic diagram of the thermal management system structure of this application;

[0037] Figure 2 : Schematic diagram of the thermal management method of the present application;

[0038] Among them: 1-compressor; 2-gas-liquid separator; 3-four-way valve; 4-condenser; 5-air conditioning loop electronic expansion valve; 6-blower; 7-evaporator; 8-electric valve; 9-battery loop electronic expansion valve; 10-liquid cooler; 11-power battery; 12-battery pack; 13-thermoelectric module; 14-axial flow fan; 15-check valve; 16-cockpit flow path; 17-power battery flow path; 18-control circuit; 19-potential difference acquisition module. DETAILED DESCRIPTION

[0039] The embodiments of the present application are described in detail below, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0040] In the description of the present application, it should be understood that the terms "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0041] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0042] The present application is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0043] The present application relates to a power battery thermal management system. The thermal management system of the present application provides a heat dissipation module specifically for the downstream battery pack of the power battery for heat dissipation of the power battery, which can effectively solve the high temperature problem of the downstream power battery in the forced convection heat dissipation mode, maintain the temperature uniformity between the power battery packs, and keep the power battery in a suitable operating temperature range at all times to prevent thermal runaway, thereby ensuring the continuous and efficient operation of the power battery under dynamic charging and discharging power and ensuring the normal service life of the power battery.

[0044] Specifically, Figure 1 As shown, a power battery thermal management system of the present application includes a cockpit flow path 16, a power battery flow path 17, a cooling structure and a control structure. The cockpit flow path 16 is a flow path for controlling the temperature of the cockpit, which is actually an air conditioning flow path for cooling the cockpit, including a compressor 1, a gas-liquid separator 2, a condenser 4, an air conditioning loop electronic expansion valve 5 and an evaporator 7 connected in series by pipelines in sequence. A blower 6 is provided on one side of the evaporator 7. It also includes a four-way valve 3, and the four interfaces of the four-way valve 3 correspond to the inlet of the compressor 1, the outlet of the gas-liquid separator 2, the inlet of the condenser 4 and the outlet of the evaporator 7 respectively. When the cockpit has a cooling demand, the compressor 1 is started, and the compressor 1 drives the refrigerant in the pipeline to flow through the gas-liquid separator 2, and then enters the condenser 4 after passing through the four-way valve 3. The temperature of the refrigerant in the condenser 4 decreases, and then enters the evaporator 7, absorbs heat in the evaporator 7, and the blower 6 blows air into the cockpit to reduce the temperature in the cockpit. A control valve is provided on the cockpit flow path 16, and an air-conditioning loop electronic expansion valve 5 is installed on the pipeline between the condenser 4 and the evaporator 7. The air-conditioning loop electronic expansion valve 5 can adjust the coldness of the refrigerant entering the evaporator 7 by opening control to achieve different cooling effects.

[0045] The power battery flow path 17 is specifically for the several battery groups 12 in the rear of the power battery 11. It is a refrigerant flow path drawn from the cockpit flow path 16 and can dissipate heat for the several battery groups 12 in the rear of the power battery 11. Specifically, Figure 1As shown, the power battery flow path 17 is a refrigerant flow path whose two ends are respectively connected to the inlet side and outlet side pipelines of the evaporator 7. The power battery flow path 17 is provided with a heat exchange structure for heat exchange with several battery groups 12 in the rear of the power battery 11 and a valve structure for controlling the on-off of the power battery flow path 17. The on-off of the entire power battery flow path 17 is controlled by the valve structure to realize the flow of the refrigerant in the power battery flow path 17. When it is necessary to dissipate heat for several battery groups 12 in the rear of the power battery 11, the power battery flow path 17 can be opened by the valve structure to allow the refrigerant to enter the power battery flow path 17 to exchange heat with several battery groups 12 in the rear of the power battery 11, so as to achieve the purpose of dissipating heat for several battery groups 12 in the rear of the power battery 11.

[0046] The cooling structure is arranged at the front end of the power battery 11 to cool down the power battery 11. The cooling structure dissipates heat for the entire power battery 11. The cooling structure is installed at the front end of the power battery 11 to dissipate heat for the power battery 11 by convection. Under normal circumstances, if the cooling structure is used alone to dissipate heat for the power battery 11, the heat dissipation effect of the battery pack 12 at the front end of the power battery 11 is better than that of the battery pack 12 at the rear end of the power battery 11. A temperature difference will occur in the battery packs 12 of the power battery 11. In order to avoid this situation, the present application actively dissipates heat for several groups of battery packs 12 at the rear end of the power battery 11 by designing a power battery flow path 17 to avoid a large temperature difference between the front and rear battery packs 12.

[0047] The control structure of the present application controls the valve structure based on the temperature difference of the battery pack 12 of the power battery 11 .

[0048] In actual operation, you can follow the steps below:

[0049] S1. When the vehicle is started and the power battery 11 starts to work, the temperature of the power battery 11 is collected, and whether the power battery 11 needs to be cooled is determined based on the temperature of the power battery 11;

[0050] The thermal management of the power battery in this application is performed after the vehicle is started and the power battery starts working. The power battery starting working in this application means that the power battery is in a discharging condition or a charging condition. The power battery needs to be cooled only when the temperature of the power battery obviously exceeds the suitable working temperature.

[0051] S2. When the power battery needs to be cooled, the temperature of the battery pack 12 of the power battery and the potential difference of the thermoelectric modules 13 of several battery packs 12 in the rear of the power battery are collected, and the opening of the valve structure is adjusted based on the potential difference of the thermoelectric module 13 and the temperature of the battery pack 12;

[0052] The present application converts the temperature difference of several battery groups corresponding to the power battery flow path into electric potential through the thermoelectric module 13. Under normal circumstances, corresponding control and adjustment can be performed by collecting the temperature of each battery group of the power battery (each battery group of the power battery corresponds to a temperature sensor, which can obtain the temperature of the current battery group in real time). That is, once there is a large temperature difference between the front and rear paths, the power battery flow path 17 can be opened to dissipate heat and cool the rear battery group of the power battery. However, if the control method only collects the battery group temperature, the feedback is not timely.

[0053] In order to solve the above technical problems, the present application collects the potential difference of the thermoelectric modules 13 of several groups of battery packs in the later stage of the power battery. The potential difference reflects the temperature difference in the current battery pack. The greater the potential difference, the greater the temperature difference between the battery packs. By collecting the potential difference, the temperature difference between the current battery packs can be quickly obtained. It can be known from the Seebeck effect that a potential difference will be generated at both ends of two different materials with different temperatures. The Seebeck effect has a fast response speed and is only driven by the temperature difference between the battery packs. No additional energy consumption is required, and the temperature difference of the battery pack can be quickly obtained, which is equivalent to directly collecting the temperature, and the response is faster.

[0054] In some embodiments of the present application, the present embodiment optimizes the structure of the power battery flow path 17, such as Figure 1 As shown, the power battery flow path 17 is a branch, including a valve structure and a liquid cooler 10 connected in series by a pipeline mechanism. The liquid cooler 10 is a heat exchange structure on the power battery flow path 17. When the refrigerant enters the liquid cooler 10, it will exchange heat with the battery pack in the liquid cooler 10. The refrigerant takes away the heat of the battery pack to cool the battery pack. The valve structure is a structure that controls the on-off, opening, refrigerant coldness and flow direction of the power battery flow path 17, as shown in FIG. Figure 1 As shown, the valve structure includes an electric valve 8 electrically connected to the control structure, a battery loop electronic expansion valve 9 and a check valve 15. The electric valve 8 is arranged between the inlet end of the power battery flow path 17 and the liquid cooler 10. The electric valve 8 controls the flow rate of the refrigerant in the entire power battery flow path 17. Different openings of the electric valve 8 correspond to different refrigerant flows in the power battery flow path 17. The larger the opening of the electric valve 8, the larger the flow rate of the refrigerant in the power battery flow path 17. The battery loop electronic expansion valve 9 is arranged between the electric valve 8 and the liquid cooler 10. 0, the battery loop electronic expansion valve 9 adjusts the coolness of the refrigerant by throttling. The larger the opening of the battery loop electronic expansion valve 9, the cooler the refrigerant in the power battery flow path 17, and the corresponding heat dissipation efficiency of the battery pack is higher. Conversely, the smaller the opening of the battery loop electronic expansion valve 9, the cooler the refrigerant in the power battery flow path 17, and the corresponding heat dissipation efficiency of the battery pack is lower. The check valve 15 is arranged between the liquid cooler 10 and the outlet end of the power battery flow path 17. The check valve 15 is actually a one-way valve.

[0055] In actual use, when it is determined that several groups of battery packs in the rear of the power battery need to be cooled, the electric valve 8 is controlled to open, the power battery flow path 17 is opened, and the refrigerant flowing through the condenser 4 is divided into two parts. One part flows in the cockpit flow path 16 according to the cockpit cooling demand, and the other part enters the power battery flow path 17, passes through the electric valve 8 and the battery loop electronic expansion valve 9, and then enters the liquid cooler 10 (the flow direction of the refrigerant in the liquid cooler 10 is from back to front along the arrangement direction of the power battery battery pack, and the gas flow direction of the axial flow fan when dissipating heat to the power battery is from front to back). The refrigerant is in the liquid cooler 10 and flows with the power battery. In the post-battery process, heat exchange occurs in several groups of battery packs, the temperature of the refrigerant increases, and the temperature of the battery pack decreases. After the refrigerant flows out of the liquid cooler 10, it flows back to the cockpit flow path 16 through the check valve 15 for circulation; in extreme cases, that is, when the heat dissipation demand of the battery pack is still not met when the electric valve 8 is fully opened, the opening of the battery loop electronic expansion valve 9 can be adjusted to increase the opening of the battery loop electronic expansion valve 9 and increase the cooling degree of the refrigerant. In fact, the temperature of the refrigerant circulating in the power battery flow path 17 is reduced by throttling. The lower the temperature of the refrigerant, the higher the heat exchange efficiency with the battery pack, thereby meeting the heat dissipation demand of the battery pack.

[0056] In a further embodiment of the present application, the present embodiment optimizes the above control structure. Specifically, Figure 1 As shown, the control structure of this embodiment includes a potential difference acquisition module 19 and a control module. In this embodiment, a thermoelectric module 13 is arranged on the battery pack (the thermoelectric module 13 is installed on the battery pack corresponding to the power battery flow path), and the thermoelectric module 13 includes a plurality of pairs of thermocouples connected in series, a copper guide plate and a thermally conductive insulating plate, wherein the thermocouple pairs are composed of a P-type semiconductor and an N-type semiconductor, and the P-type semiconductor and the N-type semiconductor are connected in series end to end using a copper guide plate, and the thermally conductive insulating plates are respectively arranged at the outer ends of the upper and lower copper guide plates, and the thermoelectric module 13 is arranged between single battery packs, and the thermally conductive insulating plates at both ends directly contact the power battery pack. The potential acquisition module integrates and judges the unstable potential difference generated by the thermoelectric module 13 to obtain the temperature difference of each battery pack.

[0057] The potential difference acquisition module 19 is used to collect the potential difference of the thermoelectric module 13. After the control module obtains the potential difference, the opening of the valve structure can be adjusted based on the potential difference.

[0058] In addition, the control structure of this embodiment further includes a front-end temperature acquisition module and a rear-end temperature acquisition module. The front-end temperature acquisition module is used to acquire the temperature of the front-end battery pack of the power battery, and the rear-end temperature acquisition module is used to acquire the temperature of the rear-end battery pack of the power battery. In fact, the battery pack of the power battery is equipped with a temperature acquisition device such as a temperature sensor, which can obtain the temperature of the battery pack in real time. The front-end temperature acquisition module of this embodiment acquires the temperature of the front-end battery pack in the power battery that does not intersect with the power battery flow path 17. When the cooling structure and the power battery flow path 17 are not turned on, the front-end temperature acquisition module acquires the temperature of the entire power battery. The front-end temperature acquisition module of this embodiment acquires the maximum temperature of multiple front-end battery packs in the power battery that do not intersect with the power battery flow path 17. The rear-end temperature acquisition module acquires the temperature of the battery pack in the power battery that intersects with the power battery flow path 17. The rear-end temperature acquisition module of this embodiment acquires the maximum temperature of multiple rear-end battery packs in the power battery that intersect with the power battery flow path 17.

[0059] The above modules are connected by signals via a control circuit 18 .

[0060] When the power battery thermal management system of this application is actually operated: Figure 2 As shown, when the vehicle starts and the power battery starts working, the maximum temperature of several battery packs at the front end of the power battery is collected by the front-end temperature collection module, and the maximum temperature collected by the front-end temperature collection module is compared with the first temperature threshold (the first temperature threshold of the present application is 25°C to 30°C, and is not limited to this temperature in actual application). If the maximum temperature collected by the front-end temperature collection module is not less than the first temperature threshold, it is determined that the current power battery needs to be cooled and cooled, and the axial flow fan 14 is turned on, and the electric valve 8 is turned on at the same time, and the opening of the electric valve 8 is maintained at 5% (this can ensure that a small amount of refrigerant enters the power battery flow path 17 to cool and dissipate the heat of the rear battery pack of the power battery, but will not affect the cooling demand of the cockpit too much); collect the potential difference of the thermoelectric module 13 of the battery pack that intersects with the power battery flow path 17, and adjust the opening of the electric valve 8 according to the potential difference. The opening of the electric valve 8 can be adjusted according to the following mode,

[0061] If the first potential threshold ≤ potential difference < second potential threshold, the electric valve 8 is controlled to open at 25%; if the second potential threshold ≤ potential difference < third potential threshold, the electric valve 8 is controlled to open at 50%; if the third potential threshold ≤ potential difference < fourth potential threshold, the electric valve 8 is controlled to open at 75%; if the fourth potential threshold ≤ potential difference, the electric valve 8 is controlled to open at 100%; the first potential region < the second potential region < the third potential region < the fourth potential region; in actual application, it is not limited to the above method, and it only needs to be adjusted according to the mode in which the larger the potential difference, the larger the opening of the electric valve 8;

[0062] The opening of the battery loop electronic expansion valve 9 is maintained at the set initial opening. When the opening of the electric valve 8 reaches 100%, that is, the electric valve 8 is in a fully open state, the maximum temperature of several groups of battery packs in the rear process of the power battery is collected based on the rear-end temperature acquisition module, and the maximum temperature of several groups of battery packs in the rear process of the power battery is compared with the second temperature threshold (the second temperature threshold of the present application is 35°C to 40°C, and is not limited to this temperature in actual application). If the maximum temperature of several groups of battery packs in the rear process of the power battery is not less than the second temperature threshold, it is judged that the heat dissipation efficiency of the rear process battery pack needs to be improved, and the opening of the battery loop electronic expansion valve 9 needs to be increased. The opening of the battery loop electronic expansion valve 9 is adjusted in such a manner that the more the maximum temperature exceeds the second temperature threshold, the larger the opening of the battery loop electronic expansion valve 9 is, until the rear-end temperature acquisition module collects that the maximum temperature is less than the second temperature threshold;

[0063] This is done sequentially until the maximum temperature collected by the front-end temperature collection module is less than the first temperature threshold, then the axial flow fan 14 is stopped and the electric valve 8 is closed.

[0064] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited by the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present application. The present application may have various changes and improvements without departing from the spirit and scope of the present application, and these changes and improvements fall within the scope of the present application to be protected. The scope of protection claimed in the present application is defined by the attached claims and their equivalents.

Claims

1. A power battery thermal management system, comprising a cockpit flow path; the cockpit flow path comprises a compressor, a gas-liquid separator, a condenser, an air conditioning loop electronic expansion valve and an evaporator connected in series by pipelines; a blower is provided on one side of the evaporator, characterized in that: Also includes, A power battery flow path, wherein the power battery flow path is a refrigerant flow path whose two ends are respectively connected to the inlet and outlet pipes of the evaporator, and a heat exchange structure for performing heat exchange on a plurality of battery packs in the rear stage of the power battery and a valve structure for controlling the on-off of the power battery flow path are provided on the power battery flow path; A cooling structure, which is arranged at the front end of the power battery and is used to cool the power battery; A control structure controls the valve structure based on a battery pack temperature difference of the power battery.

2. A power battery thermal management system according to claim 1, characterized in that: The control structure includes, A thermoelectric module, the thermoelectric module is used to convert the temperature difference of a plurality of battery packs corresponding to the power battery flow path into an electric potential; A potential difference acquisition module, wherein the potential difference acquisition module is used to collect the potential difference of the thermoelectric module; A control module is provided to adjust the opening of the valve structure based on the potential difference.

3. A power battery thermal management system according to claim 2, characterized in that: The control structure also includes, A front-end temperature acquisition module, which is used to collect the temperature of the power battery forward battery pack; The rear-end temperature acquisition module is used to collect the temperature of the rear-end battery pack of the power battery.

4. A power battery thermal management system according to claim 1, characterized in that: The heat exchange structure includes a liquid cooler for exchanging heat with a plurality of battery packs in the rear stage of the power battery.

5. A power battery thermal management system according to claim 1, characterized in that: The valve structure includes an electric valve, a battery loop electronic expansion valve and a check valve electrically connected to the control structure; the electric valve is arranged between the power battery flow path inlet and the liquid cooler; the battery loop electronic expansion valve is arranged between the electric valve and the liquid cooler; the check valve is arranged between the liquid cooler and the power battery flow path outlet.

6. A power battery thermal management system according to claim 1, characterized in that: The cooling structure includes an axial flow fan arranged at the front end of the power battery.

7. A power battery thermal management method, characterized in that: The thermal management method is used to operate any one of the power battery thermal management systems according to claims 1 to 6, comprising: When the vehicle is started and the power battery starts working, the temperature of the power battery is collected, and based on the power battery temperature, it is determined whether the power battery needs to be cooled; When the power battery needs to be cooled, the battery pack temperature of the power battery and the potential difference of thermoelectric modules of several battery packs in the rear of the power battery are collected, and the opening of the valve structure is adjusted based on the potential difference and the battery pack temperature.

8. A power battery thermal management method according to claim 7, characterized in that: The method for judging whether the power battery needs to be cooled based on the power battery temperature includes: collecting the temperatures of several battery packs ahead of the power battery, and when the maximum temperature of the several battery packs ahead is not less than a first temperature threshold, judging that the power battery needs to be cooled, turning on the axial flow fan at the front end of the power battery, and opening the electric valve in the valve structure and maintaining it at a set initial opening.

9. A power battery thermal management method according to claim 7, characterized in that: The method for adjusting the opening of the valve structure based on the potential difference and the battery pack temperature includes: obtaining the potential difference of the thermoelectric modules of several groups of battery packs in the rear process of the power battery, and adjusting the opening of the electric valve in the valve structure in such a way that the greater the potential difference, the greater the opening of the electric valve.

10. A power battery thermal management method according to claim 9, characterized in that: The method for adjusting the opening of the valve structure based on the potential difference and the battery pack temperature includes: when the opening of the electric valve is fully open, obtaining the maximum temperature of several battery packs in the rear process of the power battery, and if the maximum temperature is not lower than the second temperature threshold, adjusting the opening of the battery loop electronic expansion valve in the valve structure, and adjusting the opening of the battery loop electronic expansion valve in such a manner that the more the maximum temperature exceeds the second temperature threshold, the larger the opening of the battery loop electronic expansion valve.

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