Low-temperature power battery thermal management system and control method thereof

Abstract

The invention discloses a low-temperature power battery thermal management system and a control method thereof, relates to a new energy technology, and aims to solve various problems of a lithium ion battery in a low-temperature environment. In the system, a micro-channel heat exchanger comprises a main flow plate and a plurality of micro-channel heat exchange plates, dozens of single-channel units are arranged in the micro-channel heat exchange plates, frames capable of moving along the inner walls of the single-channel units are arranged in the single-channel units, and liquid channels in the main flow plate are communicated with an anti-freezing liquid tank and the micro-channel heat exchange plates; the micro-channel heat exchange plate is communicated with an inlet of the anti-freezing solution tank to form an anti-freezing solution flowing channel; the first circulating pump is arranged in the flow channel; the storage battery heats the anti-freezing solution tank; the temperature sensor measures the temperature of the power battery; and the controller controls the first circulating pump to work according to a measurement result of the temperature sensor. The method comprises the steps that temperature data collected by a temperature sensor are obtained in real time, and two circulating pumps are controlled to work alternately according to the temperature data until the temperature data reach a preset threshold value.

Description

Technical Field

[0001] The present invention relates to new energy technology, and in particular to thermal management technology of low-temperature power batteries. Background Art

[0002] Nowadays, new energy is developing rapidly, and there are many new energy vehicles and ships. New energy lithium battery technology has also developed rapidly. Lithium iron phosphate batteries have become the "new focus" of the industry due to their superior electrochemical performance, high safety and reliability, and long life. As the core component of electric vehicles and ships, they determine the key performance indicators of the vehicle, such as cruising range, cost, service life, and safety indicators.

[0003] However, when the ambient temperature is low, the temperature of the lithium battery is low, and there are various problems such as difficulty in charging, difficulty in starting, significant reduction in cruising range, and reduced safety and reliability. The reason is that in a low temperature environment, the conductivity of the electrolyte and solid electrolyte interphase (SEI) of the lithium-ion battery decreases, the ion solid phase diffusion rate slows down, and the negative electrode overpotential increases. These factors will cause the output power, energy density and service life of the lithium-ion battery to be greatly reduced, and even affect driving safety. In addition, there is a risk of lithium precipitation when charging lithium batteries at low temperatures, and the growth of lithium dendrites will pierce the battery separator, causing a short circuit and irreversible damage to the battery. The above problems have seriously hindered the development of electric vehicles and ships in low temperature environments. Therefore, it is necessary to design a suitable thermal management system to control the temperature of the power battery during operation in a low temperature environment. Summary of the invention

[0004] The purpose of the present invention is to meet the development needs of the prior art and to provide a low-temperature power battery thermal management system and a control method thereof, so that the power battery (mainly lithium-ion battery) can operate stably in a low-temperature environment.

[0005] The low-temperature power battery thermal management system of the present invention comprises: a microchannel heat exchanger, an antifreeze tank, a first circulation pump, a storage battery, a controller, and a temperature sensor; the microchannel heat exchanger comprises a mainstream plate and a plurality of microchannel heat exchange plates, the microchannel heat exchange plate has a plurality of single-channel units inside, the single-channel unit is provided with a frame that can move along the inner wall of the single-channel unit, the plurality of microchannel heat exchange plates are respectively arranged on one side of a plurality of low-temperature power batteries, the mainstream plate is provided with a liquid channel inside, one end of the liquid channel is connected to the outlet of the antifreeze tank, and the other end is connected to one end of the plurality of microchannel heat exchange plates, the other end of the plurality of microchannel heat exchange plates is connected to the inlet of the antifreeze tank, so as to form a flow channel for the antifreeze; the first circulation pump is arranged in the flow channel; the storage battery is used to heat the antifreeze tank; the temperature sensor is used to measure the temperature of the power battery; the controller is used to control the operation of the first circulation pump according to the measurement result of the temperature sensor.

[0006] Optionally, an elastic structure is further provided inside the single-channel unit of the microchannel heat exchanger, one end of the elastic structure is fixed to the frame, and the other end is fixed to the end of the single-channel unit.

[0007] Optionally, a second circulating pump is further included, wherein the second circulating pump is connected to the flow channel of the antifreeze liquid, and the water outlet directions of the first circulating pump and the second circulating pump are opposite.

[0008] Optionally, a filtering device is provided at the inlet of the antifreeze tank.

[0009] Optionally, a power generation device is also included, and the power generation device is used to charge the battery.

[0010] Optionally, the power generation device includes a fan, a generator, and a rectifier and inverter device; the generator generates electric energy when driven by the fan, and the rectifier and inverter device is used to adjust the voltage value of the electric energy.

[0011] Optionally, mica is arranged on the blades of the fan, and a heating wire is arranged on the mica.

[0012] The control method of the above system includes: acquiring the temperature data collected by the temperature sensor in real time, and controlling the working status of the first circulation pump and the second circulation pump according to the temperature data, so that the first circulation pump and the second circulation pump work alternately until the temperature data reaches a preset threshold.

[0013] Optionally, if the temperature data is lower than a preset first threshold value, the first circulation pump and the second circulation pump are controlled so that the first circulation pump and the second circulation pump work alternately; if the temperature data reaches the preset first threshold value and is lower than a preset second threshold value, the first circulation pump and the second circulation pump are controlled so that the first circulation pump is in a working state and the second circulation pump is in a non-working state; if the temperature data reaches the preset second threshold value, the first circulation pump and the second circulation pump are controlled so that both the first circulation pump and the second circulation pump stop working.

[0014] The present invention enhances the heat exchange effect, improves the heating rate of the heat exchange medium refrigerant, reduces energy consumption, and improves the space utilization of ships, electric ships, and automobiles, and improves the heat exchange efficiency and energy utilization rate; and takes reasonable measures to solve the problem of heat exchange affected by microchannel blockage. The wind power generation device is improved to solve the problems of high energy consumption, low output power, and insufficient power generation efficiency at low temperatures, providing a guarantee for the preheating of the power battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic diagram of the principle of a low-temperature power battery thermal management system according to an embodiment of the present application;

[0016] Figure 2 is a schematic structural diagram of a microchannel heat exchanger according to an embodiment of the present application;

[0017] Figure 3 is a schematic structural diagram of a microchannel heat exchange plate according to an embodiment of the present application;

[0018] Figure 4 is a schematic structural diagram of a single-channel unit according to an embodiment of the present application;

[0019] Figure 5 is a schematic structural diagram of an antifreeze liquid tank according to an embodiment of the present application;

[0020] Figure 6 is a schematic diagram of the structure of a fan according to an embodiment of the present application. DETAILED DESCRIPTION

[0021] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0022] As used herein, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context indicates otherwise. It should be further understood that the terms "comprise", "include" indicate the presence of the described features, operations, elements, components, items, kinds, and / or groups, but do not exclude the presence, occurrence, or addition of one or more other features, operations, elements, components, items, kinds, and / or groups. The terms "or" and "and / or" used herein are interpreted as inclusive, or mean any one or any combination. Therefore, "A, B or C" or "A, B and / or C" means "any of the following: A; B; C; A and B; A and C; B and C; A, B and C". Exceptions to this definition will only occur when the combination of elements, functions, or operations is inherently mutually exclusive in some way.

[0023] In response to the problems of lithium-ion batteries such as difficulty in charging, difficulty in starting, significant reduction in cruising range, and reduced safety and reliability in low-temperature environments, the present invention provides a low-temperature power battery thermal management system and a control method thereof, which can heat lithium-ion batteries in low-temperature environments and start operation when they reach a suitable temperature, thereby avoiding the above-mentioned problems of lithium-ion batteries in low-temperature environments.

[0024] Figure 1 Schematic diagram of the principle of a low-temperature power battery thermal management system 100 according to an embodiment of the present application. Figure 1 As shown, the system 100 includes a microchannel heat exchanger 110, an antifreeze tank 120, a first circulation pump 130, a battery 140, a controller 150, and a temperature sensor.

[0025] The antifreeze tank 120 stores antifreeze, and the electric energy output by the battery 140 heats the antifreeze after passing through the relay. The antifreeze tank 120 includes two ports, one as an outlet and the other as an inlet. The antifreeze flows out of the antifreeze tank 120 and enters the microchannel heat exchanger 110, and returns to the antifreeze tank 120 after flowing out of the microchannel heat exchanger 110. The first circulation pump 130 is arranged in the circulation channel of the antifreeze, for example, the first circulation pump 130 can be arranged between the outlet of the antifreeze tank 120 and the inlet of the microchannel heat exchanger 110, or between the outlet of the microchannel heat exchanger 110 and the inlet of the antifreeze tank 120.

[0026] The structure of the microchannel heat exchanger 110 is as follows: Figure 2 As shown, the microchannel heat exchanger 110 specifically includes a mainstream plate 111 and a plurality of microchannel heat exchange plates 112. Figure 3As shown, dozens of mutually parallel single-channel units are arranged inside the microchannel heat exchange plate 112. A liquid channel for the flow of refrigerant is arranged inside the mainstream plate 111, and the liquid channel has an inlet and several outlets, wherein the inlet is connected to the outlet of the antifreeze tank 120, and the several outlets are respectively connected to the inlets of several microchannel heat exchange plates 112, and the outlets of several microchannel heat exchange plates 112 are all connected to the inlet of the antifreeze tank 120.

[0027] The first circulation pump 130 may be arranged between the outlet of the antifreeze liquid tank 120 and the mainstream plate 111 , or may be arranged between the microchannel heat exchange plate 112 and the inlet of the antifreeze liquid tank 120 .

[0028] When the first circulation pump 130 is working, the antifreeze liquid flows out from the outlet of the antifreeze liquid tank 120 , is distributed to each microchannel of the microchannel heat exchange plate 112 through the mainstream plate 111 , and the antifreeze liquid flowing out of the microchannel flows back to the antifreeze liquid tank 120 .

[0029] The power battery 200 is a rectangular parallelepiped, and the two surfaces with the largest area are arranged with microchannel heat exchange plates 112. Two adjacent power batteries 200 can share one microchannel heat exchange plate 112. Figure 2 A bottom plate 113 may also be provided at the outlet of the microchannel, and a liquid channel is provided inside the bottom plate 113, and the liquid channel is connected to the outlets of each single channel of the microchannel heat exchanger, and outlets are provided on both sides of the bottom plate 113, and the antifreeze liquid flowing out from the inside of the bottom plate 113 flows out through the outlets on both sides of the bottom plate 113 and flows back to the antifreeze liquid tank 120.

[0030] In order to prevent leakage of antifreeze and reduce unnecessary dissipation losses, the entire antifreeze circulation channel is formed in one piece, or the various parts are connected by welding.

[0031] The temperature sensor can be arranged between the power battery cell and the microchannel heat exchange plate 112 to provide real-time feedback on the temperature of the power battery 200. The controller 150 controls the operation of the first circulation pump 130 according to the measurement data of the temperature sensor. For example, when the temperature value collected by the temperature sensor is lower than a preset threshold value, the controller 150 controls the first circulation pump 130 to make the first circulation pump 130 work at the set speed. When the first circulation pump 130 is working, the antifreeze liquid circulates continuously between the antifreeze liquid tank 120 and the microchannel heat exchanger 110 to achieve heating of the power battery 200; when the temperature value collected by the temperature sensor reaches the above threshold value, the controller 150 controls the first circulation pump 130 to stop the first circulation pump 130. At this time, the antifreeze liquid stops circulating, that is, the heating of the power battery 200 is stopped.

[0032] The speed of the first circulating pump 130 can be adjusted according to the temperature value collected by the temperature sensor. For example, when the system 100 is powered on and the temperature value collected by the temperature sensor is low, the controller 150 can control the first circulating pump 130 to operate at a higher speed, thereby increasing the flow of the first circulating pump 130 and improving the speed of battery preheating. The corresponding relationship between the temperature value and the speed of the first circulating pump 130 can be set based on experience to ensure safety while improving economy.

[0033] In addition, the controller 150 can also be used to control the heating of the antifreeze liquid by the battery 140 .

[0034] The system 100 reasonably arranges the microchannel heat exchange plates 112 between the power batteries 200 and heats the power batteries 200 with antifreeze, so that the heating effect is uniform and the temperature gradient is not easy to appear inside the power batteries 200. This can not only ensure the normal operation of the power batteries 200 in a cold environment, but also has little effect on the battery's mileage and life. The microchannel heat exchanger has outstanding heat exchange performance and has the advantage of energy saving. In addition, the antifreeze has high thermal energy transfer efficiency, which improves the power utilization rate of the battery 140.

[0035] The antifreeze is a mixture of 50% ethylene glycol and 50% water. Its pH value will gradually decrease over time. The acidic substances produced are likely to corrode the microchannel heat exchanger 110. Impurities will appear at the location where the inner wall of the microchannel heat exchanger 110 is corroded. The impurities gradually accumulate, resulting in a reduction in the size of the internal channel of the microchannel heat exchanger 110, affecting the flow of the antifreeze and reducing the heating efficiency of the power battery 200. In the embodiment of the present application, a frame 114 is added to the single channel unit of the microchannel, such as Figure 4 As shown, a microchannel heat exchange plate 112 may have multiple frames 114, the outer edges of the frames 114 are closely attached to the inner wall of the single channel unit, and the frames 114 can move along the length direction of the microchannel. If the cross section of the inner wall of the single channel unit is circular, the outer edge of the frame 114 is circular; if the cross section of the inner wall of the single channel unit is square, the outer edge of the frame 114 is square. Figure 4The cross section of the inner wall of the single-channel unit is square. An elastic structure 115, such as a spring, can also be arranged inside the single-channel unit, one end of the elastic structure 115 is fixed on the frame 114, and the other end is fixed on the end of the single-channel unit. A baffle with holes is arranged at the top and the end of the single-channel unit to prevent the frame from being stressed and detaching from the single-channel unit. When the first circulating pump 130 is working, the antifreeze flows inside the single-channel unit, driving the frame 114 to move along the flow direction of the antifreeze. During the movement, the elastic structure 115 is gradually stretched, and the frame 114 and the inner wall of the microchannel will have slight friction, so that the impurities attached to the inner wall of the microchannel fall off. After the first circulating pump 130 stops working, the antifreeze stops flowing, and the frame 114 returns to the initial position driven by the elastic structure 115.

[0036] Furthermore, the outer edge of the frame 114 may be processed into a sharp structure, such as a blade-like structure, through which impurities attached to the inner wall of the single-channel unit can be scraped off.

[0037] As a preferred embodiment of the present application, a circulation pump, that is, a second circulation pump 170, may be added to the system 100. Figure 1 As shown, the second circulating pump 170 is also arranged in the circulation channel of the antifreeze liquid, and its flow direction is opposite to that of the first circulating pump 130. In the process of heating the power battery 200, the controller 150 can control the first circulating pump 130 and the second circulating pump 170 to work alternately, or control the first circulating pump 130 and the second circulating pump 170 to work alternately at least in a time period. When the first circulating pump 130 is working, the second circulating pump 170 is not working, and the flow direction of the antifreeze liquid in the circulation channel is consistent with the inlet-outlet direction of the first circulating pump 130; when the second circulating pump 170 is switched to work, the first circulating pump 130 is not working, and the antifreeze liquid in the circulation channel begins to flow in the opposite direction. During the time period when the first circulating pump 130 and the second circulating pump 170 work alternately, the frame 114 can be moved repeatedly without the elastic structure 115, and impurities on the inner wall of the microchannel can be removed in a short time.

[0038] As a preferred embodiment of the present application, a conical integrated structure 121 is provided below the antifreeze tank 120, such as Figure 5 As shown, a filter screen 122 is arranged near the bottom tip of the conical integrated structure 121. Since the density of insoluble impurities is greater than the density of antifreeze, the corroded metal slag and other impurities in the antifreeze tank 120 will slowly settle on the slope below. With the gravity and the bumps and vibrations during the driving of new energy vehicles / ships, the insoluble impurities will be concentrated on the filter screen 122. The antifreeze below the filter screen 122 is pure antifreeze, which returns to the antifreeze tank 120 for preheating again under the action of the circulating pump.

[0039] As a preferred embodiment of the present application, the battery 140 can be charged by a power generation device 180, such as Figure 1 As shown, the power generation device 180 is a wind power generation device. Air enters the air inlet of the wind power generation device, forming a power source for driving the fan blades to rotate, driving the fan to rotate and thus driving the generator to generate electricity. Since the quality of the power generated under different working conditions is different, it is necessary to set a rectifier inverter device 160 to ensure the stability of its output voltage.

[0040] In low temperature and snowstorm weather, wind turbines start up quickly in low temperature environments, and the blades are easily iced and damaged, which affects the output power and seriously reduces the power generation efficiency. To this end, the embodiment of the present application wraps the heating wire around the mica board and fixes the mica board on the fan blades, such as Figure 6 As shown, before the system is started, a battery can be used to heat the heating wire, and the wind turbine generator set can be started when the appropriate temperature is reached to prevent the damage to the wind turbine generator set caused by the sudden start of the energy storage system. At the same time, it can also ensure the stability of the output power of the wind turbine generator set and guarantee the power generation efficiency in a low temperature environment.

[0041] The embodiment of the present application also provides a control method of the above system 100. The control method can be implemented by a computer program embedded in the controller.

[0042] The control method includes: acquiring temperature data collected by a temperature sensor in real time, and controlling the working state of the first circulation pump and the second circulation pump according to the temperature data, so that the first circulation pump and the second circulation pump work alternately until the temperature data reaches a preset threshold. The preset threshold here refers to the lowest ambient temperature at which the system 100 can be started. When the ambient temperature is equal to or higher than the threshold, the power battery 200 can be started normally and will not cause negative impact on the power battery 200.

[0043] Specifically, two temperature thresholds may be preset, namely a first threshold and a second threshold. The second threshold refers to the lowest ambient temperature at which the power battery 200 can be started, and the second threshold is higher than the first threshold.

[0044] If the temperature data is lower than a preset first threshold, the first circulation pump and the second circulation pump are controlled to work alternately. During the alternating operation, impurities on the inner wall of the microchannel are washed away by the antifreeze liquid.

[0045] When the temperature data reaches a preset first threshold and is lower than a preset second threshold, the first circulation pump and the second circulation pump are controlled so that the first circulation pump is in working state and the second circulation pump is in non-working state. In this stage, the antifreeze liquid circulates in one direction, and impurities in the antifreeze liquid enter the antifreeze liquid tank 120 along with the antifreeze liquid.

[0046] When the temperature data reaches the preset second threshold, it indicates that the temperature of the power battery 200 has met the start-up condition. At this time, there is no need to heat the power battery 200 anymore. The first circulation pump and the second circulation pump are controlled to stop working.

[0047] The time for the first circulating pump and the second circulating pump to work alternately can also be set in any time period during the entire heating period, and this application does not limit this time period.

[0048] The above method is used to control the operation of the two circulation pumps, which can not only ensure the normal operation of the power battery 200 in a low temperature environment, but also remove impurities in the antifreeze circulation channel to prevent the circulation channel from being blocked.

[0049] The embodiment of the present application also provides a control device for the above system 100.

[0050] The control device comprises a temperature collecting unit and a control unit.

[0051] The temperature acquisition unit is suitable for acquiring temperature data collected by the temperature sensor in real time.

[0052] The control unit is suitable for controlling the working states of the first circulation pump and the second circulation pump according to the temperature data, so that the first circulation pump and the second circulation pump work alternately until the temperature data reaches a preset threshold value.

[0053] As a preferred embodiment of the present application, the control unit includes a first control subunit, a second control subunit, and a third control subunit.

[0054] The first control subunit is suitable for controlling the first circulation pump and the second circulation pump when the temperature data is lower than a preset first threshold value, so that the first circulation pump and the second circulation pump work alternately. During the alternating operation, impurities on the inner wall of the microchannel are washed away by the antifreeze liquid.

[0055] The second control subunit is suitable for controlling the first circulation pump and the second circulation pump when the temperature data reaches a preset first threshold value and is lower than a preset second threshold value, so that the first circulation pump is in a working state and the second circulation pump is in a non-working state. At this stage, the antifreeze liquid circulates in one direction, and the impurities in the antifreeze liquid enter the antifreeze liquid tank 120 along with the antifreeze liquid.

[0056] The third control subunit is adapted to control the first circulation pump and the second circulation pump to stop both the first circulation pump and the second circulation pump when the temperature data reaches a preset second threshold value.

[0057] The above control device has the same principle and effect as the above control method, which will not be described in detail here.

[0058] The various techniques described herein may be implemented in combination with hardware or software, or a combination thereof. Thus, the method and apparatus of the present invention, or some aspects or parts of the method and apparatus of the present invention may be in the form of program codes (i.e., instructions) embedded in a tangible medium, such as a removable hard disk, a USB flash drive, a floppy disk, a CD-ROM, or any other machine-readable storage medium, wherein when the program is loaded into a machine such as a computer and executed by the machine, the machine becomes a device for practicing the present invention.

[0059] In the case where the program code is executed on a programmable computer, the computing device generally includes a processor, a storage medium readable by the processor (including volatile and non-volatile memory and / or storage elements), at least one input device, and at least one output device. The memory is configured to store the program code; the processor is configured to execute the control method of the present invention according to the instructions in the program code stored in the memory.

Claims

1. A low-temperature power battery thermal management system, characterized in that: include: Microchannel heat exchanger, antifreeze tank, first circulation pump, battery, controller, temperature sensor; The microchannel heat exchanger comprises a mainstream plate and a plurality of microchannel heat exchange plates, wherein the microchannel heat exchange plate has a plurality of single-channel units inside, wherein the single-channel unit is provided with a frame capable of moving along the inner wall of the single-channel unit, wherein the plurality of microchannel heat exchange plates are respectively arranged on one side of a plurality of low-temperature power batteries, wherein the mainstream plate is provided with a liquid channel inside, wherein one end of the liquid channel is communicated with the outlet of the antifreeze tank, and the other end is communicated with one end of the plurality of microchannel heat exchange plates, and the other end of the plurality of microchannel heat exchange plates is communicated with the inlet of the antifreeze tank, so as to form a flow channel for the antifreeze; The first circulation pump is arranged in the flow channel; The battery is used to heat the antifreeze tank; The temperature sensor is used to measure the temperature of the power battery; The controller is used for controlling the operation of the first circulation pump according to the measurement result of the temperature sensor.

2. The system according to claim 1, characterized in that An elastic structure is also provided inside the single-channel unit of the microchannel heat exchanger, one end of the elastic structure is fixed to the frame, and the other end is fixed to the end of the single-channel unit.

3. The system according to claim 1, characterized in that It also includes a second circulation pump, which is connected to the flow channel of the antifreeze liquid, and the water outlet directions of the first circulation pump and the second circulation pump are opposite.

4. The system according to any one of claims 1 to 3, characterized in that A filtering device is arranged at the inlet of the antifreeze liquid tank.

5. The system according to claim 1, characterized in that It also includes a power generation device, which is used to charge the battery.

6. The system according to claim 5, characterized in that The power generation device includes a fan, a generator, and a rectifier and inverter device; The generator generates electric energy driven by the fan, and the rectifying and inverting device is used to adjust the voltage value of the electric energy.

7. The system according to claim 6, characterized in that Mica is arranged on the blades of the fan, and electric heating wires are arranged on the mica.

8. The control method of the system according to claim 3, characterized in that: include: The temperature data collected by the temperature sensor is acquired in real time, and the working states of the first circulation pump and the second circulation pump are controlled according to the temperature data, so that the first circulation pump and the second circulation pump work alternately until the temperature data reaches a preset threshold.

9. The control method of the system according to claim 8, characterized in that: If the temperature data is lower than a preset first threshold, controlling the first circulation pump and the second circulation pump to make the first circulation pump and the second circulation pump work alternately; If the temperature data reaches a preset first threshold value and is lower than a preset second threshold value, controlling the first circulation pump and the second circulation pump so that the first circulation pump is in a working state and the second circulation pump is in a non-working state; If the temperature data reaches a preset second threshold, the first circulation pump and the second circulation pump are controlled to stop working.

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