Thermal management system, method and vehicle for power battery

Abstract

The present invention discloses a thermal management system, method and vehicle for a power battery, the system comprising: an air conditioning subsystem, a coolant circulation pipeline and a power battery liquid cooling plate, the air conditioning subsystem comprising an evaporator, the outer surface of the evaporator being covered with a phase change material; the power battery liquid cooling plate is connected to one side of the evaporator through a coolant circulation pipeline, and the other side of the evaporator is connected to a refrigerant circulation pipeline in the air conditioning subsystem; when the power battery is super-fast charged, the high-temperature coolant flowing out of the power battery liquid cooling plate flows into the evaporator through the coolant circulation pipeline, the refrigerant in the evaporator and the phase change material cool the high-temperature coolant, and the cooled coolant flows back to the power battery liquid cooling plate through the coolant circulation pipeline. The system can quickly cool a large amount of heat generated by the power battery, greatly reducing the cooling load during super-fast charging, and improving the thermal management performance of the vehicle power battery.

Description

Technical Field

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

[0002] At present, the cooling and heating methods of power batteries in the industry mainly adopt liquid cooling and liquid heating. The coolant is passed into the liquid cooling water pipe or liquid cooling plate flow channel at the bottom or top of the battery module, and the heat of the high-temperature battery is taken away or the low-temperature battery is heated by heat conduction and heat convection. As the market has higher and higher requirements for the charging speed of automotive power batteries, super fast charging has become the mainstream design of power batteries in the future. Compared with conventional fast charging solutions, super fast charging will generate more heat during the charging process, and conventional bottom liquid cooling solutions can no longer cool down the heat generated by super charging of the battery. Most of the current design solutions for super fast charging cooling are to add additional cooling pipes or cooling plates on the side or top of the battery pack to take away the heat.

[0003] However, the amount of battery heat that traditional solutions can remove depends on the vehicle's heat dissipation capacity design on the vehicle's air-conditioning system. The current vehicles on the market are limited by size, weight, power, cost and other reasons, and the heat dissipation is not enough to support future super-fast charging needs. Summary of the invention

[0004] The embodiments of the present application provide a thermal management system, method and vehicle for a power battery, which can quickly cool a large amount of heat generated by the power battery, greatly reducing the cooling load during super-fast charging and improving the thermal management performance of the vehicle's power battery.

[0005] In a first aspect, the present invention provides the following technical solution through an embodiment of the present invention:

[0006] A thermal management system for a power battery, the system comprising: an air-conditioning subsystem, a coolant circulation pipeline and a power battery liquid cooling plate, the air-conditioning subsystem comprising an evaporator, the outer surface of the evaporator being covered with a phase change material; the power battery liquid cooling plate is connected to one side of the evaporator through the coolant circulation pipeline, and the other side of the evaporator is connected to the refrigerant circulation pipeline in the air-conditioning subsystem; when the power battery is super-fast charged, the high-temperature coolant flowing out of the power battery liquid cooling plate flows into the evaporator through the coolant circulation pipeline, the refrigerant in the evaporator and the phase change material cool the high-temperature coolant, and the cooled coolant flows back to the power battery liquid cooling plate through the coolant circulation pipeline.

[0007] Preferably, the thickness of the phase change material is between 1-10 mm.

[0008] Preferably, the phase change temperature of the phase change material is between 37°C and 43°C.

[0009] Preferably, the phase change material is a composite phase change material, the thermal conductivity of the composite phase change material is 0.26 W / (m·K), and the phase change latent heat is greater than 120 J / cm 3 .

[0010] Preferably, the evaporator is also used to cool the coolant and the phase change material when the heat storage capacity of the phase change material reaches an upper limit.

[0011] Preferably, the system also includes: a main controller, a control valve and a temperature sensor, the main controller is connected to the control valve and the temperature sensor respectively; the temperature sensor is connected to the power battery and is used to collect the temperature of the power battery; the control valve is connected to the coolant circulation pipeline between the evaporator and the power battery liquid cooling plate, and the main controller is used to control the opening and closing of the control valve according to the temperature.

[0012] Preferably, the air conditioning subsystem further includes: a compressor, a condenser and an expansion valve, and the compressor, the condenser, the expansion valve and the evaporator are connected through the refrigerant circulation pipeline.

[0013] In a second aspect, the present invention provides the following technical solution through an embodiment of the present invention:

[0014] A thermal management method for a power battery is applied to a system as described in any one of the first aspects above, the method comprising: determining whether the power battery enters a super fast charging mode; if so, turning on the air conditioning subsystem so that an evaporator and a phase change material cool the high-temperature coolant flowing into the evaporator.

[0015] Preferably, the method further comprises: obtaining the temperature of the power battery; if the temperature is lower than a preset temperature threshold, opening a control valve so that the heat stored in the phase change material is released through a coolant circulation pipe to heat the power battery.

[0016] In a third aspect, the present invention provides the following technical solution through an embodiment of the present invention:

[0017] A vehicle comprises: a vehicle body and the thermal management system described in any one of the first aspects above.

[0018] One or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages:

[0019] The embodiment of the present invention provides a thermal management system for a power battery. When the power battery is super-fast charged, the power battery first exchanges heat with the liquid cooling plate, and then the high-temperature coolant flows into the evaporator through the coolant circulation pipeline. While the evaporator evaporates and cools the coolant, the phase change material covering the surface of the evaporator also absorbs heat from the coolant, thereby cooling the coolant through the evaporator and the phase change material at the same time, achieving a rapid cooling effect. The cooled coolant flows back to the power battery through the coolant circulation pipeline. The system utilizes the large latent heat characteristics of the phase change material to achieve cooling of the large amount of heat generated by the power battery under super-fast charging with a small volume change, greatly reducing the cooling load during super-fast charging, improving the thermal management performance of the vehicle power battery, and effectively reducing the cooling load of the power battery on the air conditioning subsystem during super-fast charging. The system does not consume too much power of the entire vehicle, nor does it bring additional volume, weight and cost burden to the vehicle end, which is conducive to maintaining the power economy of the entire vehicle and reducing carbon emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 A simplified schematic diagram of the structure of a thermal management system for a power battery provided by an embodiment of the present invention;

[0022] Figure 2 A curve comparison diagram of heat generation and temperature rise of super fast charging and ordinary fast charging provided in an embodiment of the present invention;

[0023] Figure 3 A schematic diagram of the structure of a thermal management system for a power battery provided by an embodiment of the present invention;

[0024] Figure 4 A flow chart of a thermal management method for a power battery provided by an embodiment of the present invention;

[0025] Figure 5 A schematic structural diagram of a vehicle provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0026] The working principle of the traditional power battery thermal management system and coolant circuit is: the coolant takes away the heat generated during the operation of the battery cells inside the battery through the battery liquid cooling plate and transfers it to the cooling device. In the cooling device, the refrigerant in the air conditioning circuit will exchange heat with the high-temperature coolant, take away the heat in the coolant and cool it down. The cooled coolant circulates in the power battery liquid cooling plate through a water pump to continue cooling and exchanging heat with the battery. The cooling effect of the entire thermal management system on the battery in the above process depends on the heat exchange efficiency limit of the cooling device and the displacement limit of the air conditioning circuit compressor. However, due to the space, weight and NVH (noise, vibration and harshness) limitations of the vehicle itself, it is impossible to break through the limits of the cooling device and the air conditioning compressor, and it is impossible to arrange a sufficient number of cooling devices and compressors to meet the ideal heat dissipation requirements of the entire vehicle. At this time, a new design is needed to meet the heat dissipation requirements caused by the large amount of heat generated by the battery in a short period of time under super-fast charging conditions.

[0027] In view of this, the embodiments of the present application provide a thermal management system, method and vehicle for a power battery, which can quickly cool the large amount of heat generated by the power battery, greatly reducing the cooling load during super-fast charging and improving the thermal management performance of the vehicle's power battery.

[0028] The technical solution of the embodiment of the present application is to solve the above technical problems, and the overall idea is as follows:

[0029] A thermal management system for a power battery, the system comprising: an air-conditioning subsystem, a coolant circulation pipeline and a power battery liquid cooling plate, the air-conditioning subsystem comprising an evaporator, the outer surface of the evaporator being covered with a phase change material; the power battery liquid cooling plate is connected to one side of the evaporator through the coolant circulation pipeline, and the other side of the evaporator is connected to a refrigerant circulation pipeline in the air-conditioning subsystem; when the power battery is super-fast charged, high-temperature coolant flowing out of the power battery liquid cooling plate flows into the evaporator through the coolant circulation pipeline, the refrigerant and phase change material in the evaporator cool the high-temperature coolant, and the cooled coolant flows back to the power battery liquid cooling plate through the coolant circulation pipeline.

[0030] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0031] In the first aspect, an embodiment of the present invention provides a thermal management system for a power battery. Specifically, as shown in FIG1 , the system includes: an air-conditioning subsystem 10, a coolant circulation pipeline 201, and a power battery liquid cooling plate 202. The air-conditioning subsystem 10 includes an evaporator 101, and the outer surface of the evaporator 101 is covered with a phase change material 102.

[0032] The power battery liquid cooling plate 202 is connected to one side of the evaporator 101 through the coolant circulation pipe 201, and the other side of the evaporator 101 is connected to the refrigerant circulation pipe 106 in the air-conditioning subsystem 10; when the power battery is super-fast charged, the power battery first exchanges heat with the power battery liquid cooling plate 202, and then the high-temperature coolant flows out of the power battery liquid cooling plate 202 and flows into the evaporator 101 through the coolant circulation pipe 201. The evaporator 101 and the phase change material 102 cool the high-temperature coolant, and the cooled coolant flows back to the power battery liquid cooling plate 202 through the coolant circulation pipe 201 to continue cooling the power battery.

[0033] like Figure 2 As shown in the figure, under the same cooling conditions, the heat generation and temperature rise of the power battery in the two charging modes of super fast charging and ordinary fast charging are compared:

[0034] The horizontal axis represents time, and the vertical axis represents heat generation power and battery temperature. During super-fast charging, the charging current is large in the first half, causing the battery to generate intense heat, which in turn causes the battery temperature to rise rapidly. Traditional thermal management systems are not sufficient to cool the battery to a safe temperature. Figure 2 The curves shown are a comparison of curve A (super-fast charging heat generation) and curve B (normal fast charging heat generation), as well as a comparison of curve C (super-fast charging temperature) and curve D (normal fast charging temperature). It can be seen from the curves that the heat generation and temperature rise rate of super-fast charging are significantly higher than those of normal fast charging, and the heat generation and temperature rise of super-fast charging will drop rapidly after a period of time.

[0035] Therefore, without increasing the size of the cooling equipment and compressor, we consider increasing the short-term cooling power of the battery thermal management system to slow down the temperature rise rate, thereby controlling the battery temperature within a safe range. Since the charging current of the battery decreases in the second half of super-fast charging, the heat flow of the battery decreases, and the system cooling capacity is sufficient, there is no need to increase the system cooling power.

[0036] Based on the above requirements, the present application considers adding a phase change material 102 inside the thermal management system. The phase change material 102 has high latent heat characteristics and can absorb a large amount of heat within an appropriate temperature range while maintaining a constant temperature of the phase change material 102 .

[0037] Taking into account the limited space in the battery pack, it is not suitable to coat a large amount of phase change material 102 in the battery pack to absorb heat. In this application, the outer surface of the evaporator 101 in the air-conditioning subsystem 10 is covered with phase change material 102 to achieve rapid cooling of the coolant through the evaporator 101 and the phase change material 102 at the same time.

[0038] Figure 3The schematic diagram of the structure of the thermal management system is shown. The air-conditioning subsystem 10 also includes: a compressor 103, a condenser 104 and an expansion valve 105. The compressor 103, the condenser 104, the expansion valve 105 and the evaporator 101 are connected through a refrigerant circulation pipeline 106. The compressor 103 and the condenser 104 are used to cool and condense the refrigerant. The expansion valve 105 is used to throttle and reduce the pressure of the high-pressure liquid refrigerant coming out of the condenser 104 to the evaporation pressure.

[0039] The refrigerant absorbs the high-temperature coolant in the battery through the sheet or tubular structure in the evaporator 101 ( Figure 3 The heat of the external heat source position in the evaporator 101 is used to cool the coolant, and then the high-temperature evaporated refrigerant is cooled and condensed through the compressor 103 and the condenser 104, thereby cooling the coolant through the heat exchange structure in the evaporator 101.

[0040] By covering the outer surface of the heat exchanger 101 with a phase change material 102, the present application can make the phase change material 102 absorb a portion of the heat and store it inside during the heat dissipation of the high-temperature coolant in the thermal management system, and the remaining heat is carried away by the refrigerant for circulation. Then, as the battery temperature rise rate decreases and the cooling demand decreases, the heat storage capacity of the phase change material 102 also reaches its upper limit. The refrigerant can then take away the heat of the battery coolant and the heat stored in the phase change material 102 at the same time. Through this structure, the purpose of reducing the initial temperature rise rate of the power battery during super-fast charging is achieved.

[0041] Optionally, the phase change material 102 here can be coated on the outer surface of the evaporator 101 by coating or spraying, or by other feasible means, which is not limited in the present application.

[0042] Furthermore, in order to make the phase change material 102 exert better latent heat characteristics, the phase change material 102 can continue to be in a heat absorption state before the temperature rise rate of the power battery decreases, and the thickness of the phase change material 102 on the surface of the evaporator 101 can be between 1-10mm.

[0043] Furthermore, the phase change temperature of the phase change material 102 may be between 37° C. and 43° C. The phase change material 102 may be a composite phase change material 102, the thermal conductivity of the composite phase change material 102 may be 0.26 W / (m·K), and the phase change latent heat may be greater than 120 J / cm 3 .

[0044] The specific working principle of the thermal management system is as follows:

[0045] When the surface of the evaporator 101 is not coated with the phase change material 102, assuming that the minimum heat per unit time that the battery coolant needs to be taken away is P, and the heat per unit time that the refrigerant can dissipate is D, at the initial stage of the super charging condition: D <P, and as the charging process continues, the charging current decreases, and subsequently D>P.

[0046] When the surface of the evaporator 101 is coated with the phase change material 102, at the beginning of the super charging condition, assuming that the average power of the phase change material 102 absorbing heat in a short time is X, then the heat that can be dissipated by the refrigerant and the phase change material 102 is D+X, D+X>P. As the phase change material 102 absorbs heat and its temperature rises, after the absorption of heat is changed to heat release, the heat generation of the power battery has also been reduced, so that the heat relationship becomes D>X+P, thereby achieving a cooling effect.

[0047] Therefore, the present application utilizes the large latent heat property of the phase change material 102 to “smooth out the peaks and fill the valleys”, thereby reducing the cooling demand of the power battery on the air-conditioning subsystem 10 and the load on the air-conditioning system during the super-fast charging process of the power battery.

[0048] In addition, as people's requirements for vehicle performance are getting higher and higher, battery insulation has become a function that needs to be optimized and improved. However, as the current range increases, the size of the battery pack is getting larger and larger, and the insulation performance is difficult to improve, which has reached a bottleneck.

[0049] In order to solve the problem of heat preservation of the battery pack, in a specific embodiment, the thermal management system may also include: a main controller, a control valve and a temperature sensor, the main controller is connected to the control valve and the temperature sensor respectively, the temperature sensor is connected to the power battery to collect the temperature of the power battery; the control valve is connected to the coolant circulation pipe 201 between the evaporator 101 and the power battery liquid cooling plate 202, and the main controller is used to control the opening and closing of the control valve according to the temperature.

[0050] Among them, when the air-conditioning subsystem 10 is turned on, the control valve is also opened accordingly. After the air-conditioning subsystem 10 is turned off, the control valve is also closed accordingly. When the air-conditioning subsystem 10 stops running, if there is still some undissipated heat stored in the phase change material 102, then this part of the heat will still be stored in the phase change material 102. After the control valve is opened, the stored heat will heat the power battery through the coolant circulation pipe 201.

[0051] Specifically, if the main controller obtains that the power battery temperature collected by the temperature sensor is lower than the preset temperature threshold, the control valve is opened so that the heat absorbed by the phase change material 102 is transferred back to the power battery through the coolant circulation pipe 201, thereby slowing down the temperature drop rate of the battery under low temperature conditions and increasing the insulation time.

[0052] Alternatively, the main controller in the present application is respectively connected to the vehicle ECU, the temperature sensor and the control valve. When the main controller receives the vehicle start signal sent by the vehicle end (the power battery is cold started), the temperature collected by the temperature sensor is obtained. If the temperature is less than the preset temperature threshold, the control valve is opened to allow the heat absorbed by the phase change material 102 to be transferred back to the power battery through the coolant circulation pipe 201, thereby slowing down the temperature drop rate of the battery under low temperature conditions and increasing the insulation time.

[0053] Therefore, this application not only solves the risks and challenges brought about by the large amount of heat generated by the battery during super-fast charging, but also in the insulation scenario, the phase change latent heat can be used to improve the insulation performance of the battery pack, thereby reducing the energy consumption generated by vehicle heating.

[0054] In summary, this application utilizes the large latent heat of phase change materials to achieve cooling of the large amount of heat generated by the power battery under super-fast charging with a relatively small volume change, greatly reducing the cooling load during super-fast charging, improving the thermal management performance of the vehicle power battery, and effectively reducing the power battery's cooling demand for the air-conditioning subsystem and the load on the air-conditioning system during super-fast charging. The system does not consume too much power from the vehicle, nor does it bring additional volume, weight, and cost burdens to the vehicle, which is conducive to maintaining the power economy of the vehicle and reducing carbon emissions.

[0055] In a second aspect, an embodiment of the present invention provides a thermal management method for a power battery. Specifically, as shown in FIG4 , the method includes the following steps S101 to S102:

[0056] Step S101, determining whether the power battery enters a super fast charging mode;

[0057] Step S102: If yes, the air conditioning subsystem is turned on, so that the evaporator and the phase change material cool the coolant flowing into the evaporator.

[0058] In a specific embodiment, the thermal management method is applied to the thermal management system of a power battery. First, it is determined whether the power battery enters the super fast charging mode. If so, the air conditioning subsystem is turned on so that the evaporator and the phase change material cool the coolant flowing into the evaporator to achieve cooling of the power battery.

[0059] As an optional embodiment, the thermal management system may further include a main controller, a temperature sensor and a control valve. Under the insulation condition, if the main controller receives a vehicle start signal sent by the vehicle end, the temperature of the power battery is collected. If the temperature is lower than a preset temperature threshold, the control valve is opened to allow the heat stored in the phase change material to release heat through the coolant circulation pipeline, thereby heating the power battery and achieving insulation.

[0060] An embodiment of the present invention provides a thermal management method for a power battery, and its implementation principle and technical effects are the same as those of the aforementioned system embodiment. For the sake of brief description, for matters not mentioned in the method embodiment, reference may be made to the corresponding contents in the aforementioned system embodiment.

[0061] In a third aspect, based on the same inventive concept, this embodiment provides a vehicle 500, such as Figure 5 As shown, it includes: a vehicle body 502 and a thermal management system 501 as described in any one of the first aspects above.

[0062] Those skilled in the art will readily appreciate other embodiments of the invention after considering the specification and practicing the invention disclosed herein. The present invention is intended to cover any variations, uses or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art that are not disclosed in this disclosure. The description and examples are to be considered exemplary only, and the true scope and spirit of the present invention are indicated by the following claims.

[0063] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0064] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A thermal management system for a power battery, characterized in that: The system comprises: an air conditioning subsystem, a coolant circulation pipeline and a power battery liquid cooling plate, wherein the air conditioning subsystem comprises an evaporator, and the outer surface of the evaporator is covered with a phase change material; The power battery liquid cooling plate is connected to one side of the evaporator through the coolant circulation pipeline, and the other side of the evaporator is connected to the refrigerant circulation pipeline in the air conditioning subsystem; When the power battery is super-fast charged, the high-temperature coolant flowing out of the power battery liquid cooling plate flows into the evaporator through the coolant circulation pipeline, and the refrigerant in the evaporator and the phase change material cool the high-temperature coolant at the same time, and the cooled coolant flows back to the power battery liquid cooling plate through the coolant circulation pipeline; The system further comprises: a main controller, a control valve and a temperature sensor, wherein the main controller is connected to the control valve and the temperature sensor respectively; The temperature sensor is connected to the power battery and is used to collect the temperature of the power battery; The control valve is connected to the coolant circulation pipeline between the evaporator and the power battery liquid cooling plate, and the main controller is used to control the opening and closing of the control valve according to the temperature; If the main controller obtains that the temperature of the power battery collected by the temperature sensor is lower than a preset temperature threshold, the control valve is opened so that the heat absorbed by the phase change material is transferred back to the power battery through the coolant circulation pipe; the phase change temperature of the phase change material is between 37°C and 43°C.

2. The thermal management system according to claim 1, characterized in that: The thickness of the phase change material is between 1-10 mm.

3. The thermal management system according to claim 1, characterized in that: The phase change material is a composite phase change material, the thermal conductivity of the composite phase change material is 0.26W / (m·K), and the phase change latent heat is greater than 120J / cm 3 .

4. The thermal management system according to claim 1, characterized in that: The evaporator is also used to cool the coolant and the phase change material when the heat storage capacity of the phase change material reaches an upper limit.

5. The thermal management system according to claim 1, characterized in that: The air conditioning subsystem further includes: a compressor, a condenser and an expansion valve, and the compressor, the condenser, the expansion valve and the evaporator are connected through the refrigerant circulation pipeline.

6. A thermal management method for a power battery, characterized in that: Applied in the system according to any one of claims 1 to 5, the method comprises: Determining whether the power battery enters a super fast charging mode; If yes, the air conditioning subsystem is turned on, so that the evaporator and the phase change material simultaneously cool the high-temperature coolant flowing into the evaporator; The method further includes: obtaining the temperature of the power battery; If the temperature is lower than a preset temperature threshold, the control valve is opened so that the heat stored in the phase change material is released through the coolant circulation pipe to heat the power battery, wherein the phase change temperature of the phase change material is between 37°C and 43°C.

7. A vehicle, characterized in that: include: A vehicle body and a thermal management system according to any one of claims 1 to 5.

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