Energy storage battery liquid cooling temperature control system combining natural cooling and compressor refrigeration

Abstract

The invention discloses an energy storage battery liquid cooling temperature control system combining natural cooling and compressor refrigeration, and relates to the technical field of energy storage equipment temperature control. The system comprises a compression cooling loop, a natural cooling loop, an environment temperature sensor and a controller, the compression cooling loop adopts a compressor refrigeration technology, the natural cooling loop is connected with the compression cooling loop in parallel, and the compression cooling loop comprises a compressor, a condensation pipe, an expansion valve and a first heat exchange plate which are sequentially and circularly communicated. The natural cooling loop comprises a liquid storage tank, a circulating pump, a natural cooling coil and a second heat exchange plate which are sequentially and circularly communicated, the two heat exchange plates are integrated in the evaporator and used for exchanging heat with the energy storage battery, and a compression cooling mode and a natural cooling mode can be switched at different environment temperatures through the hardware structure relation of the two heat exchange plates; therefore, the system energy efficiency can be improved by avoiding long-term operation of the compressor, and the phenomena of poor oil return and insufficient lubrication are avoided by avoiding long-term low rotating speed of the compressor, so that the reliability is improved and the service life is prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of temperature control for energy storage devices, and particularly relates to a liquid cooling temperature control system for energy storage batteries that combines natural cooling and compression refrigeration. Background Art

[0002] An energy storage liquid cooling system is a cooling system that reduces the internal temperature of an energy storage device through liquid circulation. Compared with traditional air cooling systems, the liquid cooling system has higher heat dissipation efficiency and better temperature control effect, and is particularly suitable for energy storage scenarios with high energy density and fast charging and discharging.

[0003] Currently, traditional energy storage liquid cooling systems generally face the problem of low energy efficiency. Especially when operating at low ambient temperatures, that is, existing energy storage liquid cooling systems usually adopt compression refrigeration technology. However, in low ambient temperature situations such as winter or at night, the compressor runs at a low speed for a long time, which not only increases energy consumption, but also may affect the reliability and lifespan of the unit due to poor oil return and insufficient lubrication. In addition, the energy storage system has heat dissipation characteristics during the charging and discharging process of the battery, and existing temperature control systems often cannot make full use of this characteristic, resulting in low overall energy efficiency. Summary of the Invention

[0004] The purpose of the present invention is to provide a liquid cooling temperature control system for energy storage batteries that combines natural cooling and compression refrigeration, so as to solve the problems existing in existing energy storage liquid cooling systems, such as low energy efficiency, poor reliability and short lifespan of the unit caused by relying solely on the compression refrigeration cycle to achieve heat dissipation.

[0005] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0006] The present invention provides a liquid cooling temperature control system for energy storage batteries that combines natural cooling and compression refrigeration, including a compression cooling circuit using compression refrigeration technology, a natural cooling circuit parallel to the compression cooling circuit, an ambient temperature sensor and a controller. Among them, the compression cooling circuit includes a compressor, a condenser tube, an expansion valve and a first heat exchange plate that are sequentially circulated and connected. The natural cooling circuit includes a liquid storage tank, a circulation pump, a natural cold coil and a second heat exchange plate that are sequentially circulated and connected. The first heat exchange plate and the second heat exchange plate are respectively integrated in the evaporator and used for heat exchange with the energy storage battery;

[0007] The output end of the ambient temperature sensor is communicatively connected to the input end of the controller, and the output end of the controller is respectively communicatively connected to the controlled end of the compressor and the controlled end of the circulation pump, so as to switch between compression cooling and natural cooling at different ambient temperatures.

[0008] Based on the above invention content, a new energy storage battery liquid cooling temperature control solution capable of switching between dual cooling modes by combining natural cooling and compression refrigeration technologies is provided. It includes a compression cooling circuit using compression refrigeration technology, a natural cooling circuit in parallel with the compression cooling circuit, an ambient temperature sensor, and a controller. Among them, the compression cooling circuit includes a compressor, a condenser tube, an expansion valve, and a first heat exchange plate connected in sequence for cyclic communication. The natural cooling circuit includes a liquid storage tank, a circulation pump, a natural cold coil, and a second heat exchange plate connected in sequence for cyclic communication. The two heat exchange plates are respectively integrated in the evaporator and used for heat exchange with the energy storage battery. Through their hardware structure relationship, the compression cooling mode and the natural cooling mode can be switched at different ambient temperatures. Thus, the system energy efficiency can be improved by avoiding the long-term operation of the compressor, and the phenomena of poor oil return and insufficient lubrication can be eliminated by avoiding the long-term low speed of the compressor. Furthermore, the reliability of the unit can be enhanced and the service life can be extended, which is convenient for practical application and promotion.

[0009] In a possible design, it further includes an oil separator and an oil return capillary tube configured on the compressor. Among them, the oil separator is used to separate and collect the used lubricating oil of the compressor;

[0010] The lubricating oil output end of the oil separator communicates with one end of the oil return capillary tube, and the other end of the oil return capillary tube communicates with the internal cavity of the compressor, so as to return the collected lubricating oil to the compressor cavity.

[0011] In a possible design, the controlled end of the oil separator is communicatively connected to the output end of the controller, so as to be periodically started and maintained for a preset duration under the control of the controller when the rotational speed of the compressor is lower than a preset rotational speed threshold.

[0012] In a possible design, when the preset rotational speed threshold is 20% - 40% of the rated rotational speed of the compressor, the oil separator is started once every 20 - 40 minutes and maintained for 5 - 15 seconds under the control of the controller.

[0013] In a possible design, it further includes a cooling fan for blowing air towards the condenser tube and / or the natural cold coil;

[0014] The controlled end of the cooling fan is communicatively connected to the output end of the controller.

[0015] In a possible design, the natural cooling circuit further includes an electric three-way valve and a check valve. Among them, the common end of the electric three-way valve communicates with the output end of the circulation pump, the first switching end of the electric three-way valve communicates with one end of the natural cold coil, the input end of the check valve communicates with the other end of the natural cold coil, and the second switching end of the electric three-way valve and the output end of the check valve respectively communicate with the output end of the second heat exchange plate;

[0016] The controlled end of the electric three-way valve is communicatively connected to the output end of the controller, so that when the ambient temperature is within the first preset temperature range, the common end and the first switching end are conducted and the common end and the second switching end are cut off under the control of the controller, and when the ambient temperature is within the second preset temperature range, the common end and the second switching end are conducted and the common end and the first switching end are cut off under the control of the controller, wherein the first preset temperature range and the second preset temperature range have no intersection, and the first preset temperature range is lower than the second preset temperature range.

[0017] In a possible design, the natural cooling circuit further includes an electric heater and a coolant temperature sensor, wherein the coolant temperature sensor is arranged at the coolant inlet of the liquid storage tank;

[0018] The output end of the coolant temperature sensor is communicatively connected to the input end of the controller, and the controlled end of the electric heater is communicatively connected to the output end of the controller, so that when the coolant temperature at the inlet side is lower than the third preset temperature threshold, the electric heater is started under the control of the controller.

[0019] In a possible design, it further includes a battery temperature sensor and a coolant temperature sensor, wherein the battery temperature sensor is arranged on the surface of the energy storage battery module, and the coolant temperature sensor is arranged in the natural cooling circuit;

[0020] The output ends of the battery temperature sensor and the coolant temperature sensor are respectively communicatively connected to the input end of the controller.

[0021] In a possible design, it further includes a pressure sensor and a flow meter, wherein the pressure sensor is arranged in the compression cooling circuit, and the flow meter is arranged in the natural cooling circuit;

[0022] The output ends of the pressure sensor and the flow meter are respectively communicatively connected to the input end of the controller.

[0023] In a possible design, the energy storage battery includes a lithium battery or a flow battery.

[0024] In a possible design, the controller controls the compressor and the circulation pump according to the following working mode~:

[0025] Natural cooling mode: When the ambient temperature is less than or equal to the first preset temperature threshold, the compressor is turned off and the circulation pump is turned on;

[0026] Hybrid cooling mode: When the ambient temperature is greater than the first preset temperature threshold and less than or equal to the second preset temperature threshold, the compressor is intermittently turned on, and the circulation pump is turned on, where the second preset temperature threshold is greater than the first preset temperature threshold;

[0027] Compression cooling mode: When the ambient temperature is greater than the second preset temperature threshold, the compressor is turned on, and the circulation pump is turned off.

[0028] In a possible design, the energy storage battery liquid cooling temperature control system further includes a battery temperature sensor, where the battery temperature sensor is arranged on the surface of the energy storage battery module, and the output end of the battery temperature sensor is communicatively connected to the input end of the controller;

[0029] Turning on the circulation pump includes: adaptively adjusting the operating frequency of the circulation pump so that the operating frequency is positively correlated with the battery temperature.

[0030] In a possible design, the energy storage battery liquid cooling temperature control system further includes a battery temperature sensor and a coolant temperature sensor, where the battery temperature sensor is arranged on the surface of the energy storage battery module, the coolant temperature sensor is arranged in the natural cooling circuit, and the output ends of the battery temperature sensor and the coolant temperature sensor are respectively communicatively connected to the input end of the controller;

[0031] Intermittently turning on the compressor and turning on the circulation pump includes: dynamically adjusting the operating parameters of the compressor and / or the operating parameters of the circulation pump according to the ambient temperature, battery temperature, and coolant temperature, in combination with the PID algorithm, where the operating parameters of the compressor include the intermittent opening period and / or rotation speed of the compressor, and the operating parameters of the circulation pump include the operating frequency of the circulation pump.

[0032] Beneficial effects of the above solution:

[0033] (1) The present invention provides a new energy storage battery liquid cooling temperature control solution that can combine natural cooling and compression refrigeration technologies for dual cooling mode switching, including a compression cooling circuit using compression refrigeration technology, a natural cooling circuit parallel to the compression cooling circuit, an ambient temperature sensor, and a controller. Among them, the compression cooling circuit includes a compressor, a condenser tube, an expansion valve, and a first heat exchange plate that are sequentially connected in a cycle. The natural cooling circuit includes a liquid storage tank, a circulation pump, a natural cooling coil, and a second heat exchange plate that are sequentially connected in a cycle. The two heat exchange plates are respectively integrated in the evaporator and used for heat exchange with the energy storage battery. Through their hardware structure relationship, the compression cooling mode and the natural cooling mode can be switched at different ambient temperatures. Thus, the system energy efficiency can be improved by avoiding long-term operation of the compressor, and the phenomenon of poor oil return and insufficient lubrication can be eliminated by avoiding long-term low speed of the compressor, thereby enhancing the reliability of the unit and extending its life;

[0034] (2) It can improve energy efficiency: that is, by adopting natural cooling mode at low ambient temperature, the unnecessary energy consumption of the compressor is avoided, and the overall energy efficiency is improved;

[0035] (3) It can enhance reliability: that is, the running time of the compressor at low speed is reduced, the failure risk caused by poor oil return is reduced, and the reliability of the unit is improved;

[0036] (4) It can achieve the purpose of intelligent control: that is, the automatic switching of the cooling mode is realized through intelligent control, and the automation degree and intelligent level of the system are improved;

[0037] (5) It can improve the energy efficiency and reliability of the energy storage system at different ambient temperatures, and is particularly suitable for scenarios that require efficient thermal management such as lithium battery energy storage systems and flow battery energy storage systems, which is convenient for practical application and popularization. Description of the Drawings

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0039] Figure 1 It is a schematic structural diagram of an energy storage battery liquid cooling temperature control system that combines natural cooling and compression refrigeration provided by an embodiment of the present invention. Detailed Embodiments

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the present invention will be briefly introduced below in conjunction with the accompanying drawings and the description of the embodiments or the prior art. Obviously, the following description of the structure of the drawings is only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other embodiments can be obtained based on these embodiments. It should be noted here that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation to the present invention.

[0041] It should be understood that although terms such as first and second etc. may be used herein to describe various objects, these objects should not be limited by these terms. These terms are only used to distinguish one object from another. For example, the first object can be called the second object, and similarly, the second object can be called the first object, without departing from the scope of the exemplary embodiments of the present invention.

[0042] It should be understood that for the term "and / or" that may appear in this text, it is only a description of the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, B exists alone, or A and B exist simultaneously, etc. There are three cases; another example, A, B and / or C can represent any one of A, B and C or any combination of them; for the term " / and" that may appear in this text, it is a description of another association object relationship, indicating that two relationships can exist. For example, A / and B can represent: A exists alone or A and B exist simultaneously, etc. There are two cases; in addition, for the character " / " that may appear in this text, generally it represents that the front and rear associated objects are an "or" relationship.

[0043] Embodiment

[0044] As Figure 1 shown, the energy storage battery liquid cooling temperature control system of this embodiment provides and combines natural cooling and compression refrigeration, including but not limited to a compression cooling circuit using compression refrigeration technology, a natural cooling circuit in parallel with the compression cooling circuit, an ambient temperature sensor 31, a controller 4, etc. Among them, the compression cooling circuit includes but not limited to a compressor 11, a condenser tube 12, an expansion valve 13, a first heat exchange plate 14, etc. that are sequentially circulated and connected. The natural cooling circuit includes but not limited to a liquid storage tank 21, a circulation pump 22, a natural cold coil 23, a second heat exchange plate 24, etc. that are sequentially circulated and connected. The first heat exchange plate 14 and the second heat exchange plate 24 are respectively integrated in the evaporator 40 and used for heat exchange with the energy storage battery; the output end of the ambient temperature sensor 31 is communicatively connected to the input end of the controller 4, and the output end of the controller 4 is respectively communicatively connected to the controlled end of the compressor 11 and the controlled end of the circulation pump 22, so as to switch between compression cooling and natural cooling at different ambient temperatures.

[0045] As Figure 1 shown, in the specific structure of the energy storage battery liquid cooling temperature control system, the compression cooling circuit is a conventional structure in the existing energy storage liquid cooling system. Therefore, the specific uses and hardware selections of the compressor 11, the condenser pipe 12, the expansion valve 13, the first heat exchange plate 14, etc. can be conventionally deduced based on existing solutions and will not be elaborated here; the refrigerant in the compression cooling circuit can be in a liquid state, a gaseous state, or a switching combination of them (when the refrigerant is in a liquid state, another liquid storage tank can also be configured in the compression cooling circuit for temporary storage). The natural cooling circuit is used to enable the cold liquid (such as water) in the circuit to flow from the liquid storage tank 21 to the natural cold coil 23 when the circulation pump 22 is turned on (i.e., natural cooling is turned on), then obtain cold energy from the low-temperature environment through the natural cold coil 23, and carry it to the second heat exchange plate 24 to exchange heat with the energy storage battery for temperature reduction, and finally flow back to the liquid storage tank 21 for the next cycle. Among them, the liquid storage tank 21 can be conventionally realized by using an existing tank structure, the circulation pump 22 is preferably realized by using a variable-frequency water pump, the natural cold coil 23 and the second heat exchange plate 24 can both be conventionally realized by using existing corresponding products, and the evaporator 40 provides the parallel connection between the compression cooling circuit and the natural cooling circuit. The ambient temperature sensor 31 is used to be arranged on the ambient side to collect the ambient temperature in real time and transmit the collected result to the controller 4 in real time, and it can be conventionally realized by using an existing sensor product. The controller 4 is used to realize the switching between compression cooling and natural cooling by conventionally turning on / off the compressor 1 and the circulation pump 22 at different ambient temperatures (for example, at low ambient temperatures, turn off compression cooling and turn on natural cooling to exchange heat with the energy storage battery for temperature reduction; while at high ambient temperatures, turn off natural cooling and turn on compression cooling to exchange heat with the energy storage battery for temperature reduction), so as to improve the system energy efficiency by avoiding the long-term operation of the compressor, and to eliminate the phenomena of poor oil return and insufficient lubrication by avoiding the long-term low speed of the compressor, thereby improving the reliability of the unit and extending its life; the hardware selection of the controller 4 can be but is not limited to being conventionally realized by using existing single-chip microcomputer chips or FPGAs (Field-Programmable Gate Arrays), etc. In addition, the energy storage battery specifically includes but is not limited to lithium batteries or flow batteries, etc.

[0046] Preferably, in order to combine natural cooling and compression refrigeration to achieve the purpose of intelligent seamless switching between compression cooling and natural cooling, preferably, the controller 4 can control the compressor 11 and the circulation pump 22 according to the following working modes (A) to (C) but is not limited to this.

[0047] (A) Natural cooling mode: When the ambient temperature is less than or equal to the first preset temperature threshold, the compressor 11 is turned off (i.e., compression cooling is turned off), and the circulation pump 22 is turned on. The aforementioned first preset temperature threshold is, for example but not limited to, 15 degrees Celsius.

[0048] (B) Hybrid cooling mode: When the ambient temperature is greater than the first preset temperature threshold and less than or equal to the second preset temperature threshold, the compressor 11 is intermittently turned on (i.e., compression cooling is intermittently turned on), and the circulation pump 22 is turned on, where the second preset temperature threshold is greater than the first preset temperature threshold. At this time, natural cooling assists compression cooling to exchange heat and cool down the energy storage battery. In addition, the aforementioned second preset temperature threshold is, for example but not limited to, 25 degrees Celsius.

[0049] (C) Compression cooling mode: When the ambient temperature is greater than the second preset temperature threshold, the compressor 11 is turned on, and the circulation pump 22 is turned off (i.e., natural cooling is turned off). At this time, the compressor 11 will operate at full power and dissipate heat through the condenser pipe 12.

[0050] Preferably, it further includes but is not limited to a lubricating oil separator and an oil return capillary tube configured on the compressor 11, etc. Among them, the lubricating oil separator is used to separate and collect the used lubricating oil of the compressor 11; the lubricating oil output end of the lubricating oil separator is connected to one end of the oil return capillary tube, and the other end of the oil return capillary tube is connected to the internal cavity of the compressor 11 so as to return the collected lubricating oil to the compressor cavity. The aforementioned lubricating oil separator ( Figure 1 not shown) and the oil return capillary tube ( Figure 1 not shown) can both be realized by using existing products conventionally; their installation positions can also be determined conventionally according to the specific structure of the compressor 11. Through the aforementioned combined configuration, the phenomena of poor oil return and insufficient lubrication can be further eliminated when the compressor operates at low speed, promoting the improvement of the reliability of the unit and extending its life.

[0051] Further preferably, the controlled end of the lubricating oil separator is communicatively connected to the output end of the controller 4 so as to be periodically started and maintained for a preset duration under the control of the controller 1 when the rotational speed of the compressor 11 is lower than the preset rotational speed threshold. Through the aforementioned regular control of the lubricating oil separator, lubricating oil can be regularly collected and returned when the compressor operates at low speed, further eliminating the phenomena of poor oil return and insufficient lubrication. Specifically, when the preset rotational speed threshold is 20% - 40% (for example, 30%) of the rated rotational speed of the compressor 11, the lubricating oil separator is started once every 20 - 40 minutes (for example, 30 minutes) and maintained for 5 - 15 seconds (for example, 10 seconds) under the control of the controller 1.

[0052] Preferably, it further includes, but is not limited to, a cooling fan 6 for blowing air towards the condenser tube 12 and / or the natural cooling coil 23; the controlled end of the cooling fan 6 is communicatively connected to the output end of the controller 4. Through the configuration of the aforementioned cooling fan 6, under the control of the controller 4, the heat dissipation efficiency of the condenser tube 12 and / or the natural cooling coil 23 can be improved, and the system energy efficiency can be further enhanced.

[0053] Preferably, the natural cooling circuit further includes, but is not limited to, an electric three-way valve 25 and a check valve 26, etc. Among them, the common end of the electric three-way valve 25 is connected to the output end of the circulation pump 22, the first switching end of the electric three-way valve 25 is connected to one end of the natural cooling coil 23, the input end of the check valve 26 is connected to the other end of the natural cooling coil 23, and the second switching end of the electric three-way valve 25 and the output end of the check valve 26 are respectively connected to the output end of the second heat exchange plate 24; the controlled end of the electric three-way valve 25 is communicatively connected to the output end of the controller 4, so that when the ambient temperature is within the first preset temperature range, under the control of the controller 1, the common end and the first switching end are conducted and the common end and the second switching end are cut off, and when the ambient temperature is within the second preset temperature range, under the control of the controller 1, the common end and the second switching end are conducted and the common end and the first switching end are cut off, where the first preset temperature range and the second preset temperature range have no intersection, and the first preset temperature range is lower than the second preset temperature range. The electric three-way valve 25 is used to realize the switching between the long-range natural cooling circuit (i.e., the circuit including the natural cooling coil 23) and the short-range cooling circuit (i.e., the circuit not including the natural cooling coil 23), so as to avoid bringing ambient heat into and transferring it to the energy storage battery when the ambient temperature is too high, ensuring the temperature control purpose of the energy storage battery. For example, the first preset temperature range is less than or equal to 23 degrees Celsius, and the second preset temperature range is higher than 23 degrees Celsius. In addition, the electric three-way valve 25 and the check valve 26 can be implemented by using existing related products.

[0054] Preferably, the natural cooling circuit further includes, but is not limited to, an electric heater 27 and a coolant temperature sensor, etc. Among them, the coolant temperature sensor is arranged at the coolant inlet of the liquid storage tank 21; the output end of the coolant temperature sensor is communicatively connected to the input end of the controller 4, and the controlled end of the electric heater 27 is communicatively connected to the output end of the controller 4, so that when the coolant temperature at the inlet side is lower than the third preset temperature threshold, the electric heater 27 is started under the control of the controller 1. The coolant temperature sensor ( Figure 1(not shown in the figure) is used to collect the temperature of the coolant on the inlet side in real time and transmit the collected result to the controller 4 in real time, which can be realized by using existing sensor products in a conventional manner. Through the above configuration design, when the temperature of the coolant in the natural cooling circuit is too low, the electric heater 27 can be used to appropriately heat the coolant to ensure the smoothness of the circulation. For example, when the coolant in the natural cooling circuit is water, the third preset temperature threshold is specifically 4 degrees Celsius.

[0055] Preferably, it further includes, but is not limited to, a battery temperature sensor 32 and a coolant temperature sensor. Among them, the battery temperature sensor 32 is arranged on the surface of the energy storage battery module, and the coolant temperature sensor is arranged in the natural cooling circuit; the output ends of the battery temperature sensor and the coolant temperature sensor are respectively communicatively connected to the input end of the controller 4. The battery temperature sensor 32 is used to collect the battery temperature in real time and transmit the collected result to the controller 4 in real time, which can be realized by using existing sensor products in a conventional manner. The coolant temperature sensor is used to collect the temperature of the coolant in the natural cooling circuit (such as the temperature of the coolant on the inlet side and / or the outlet side) in real time and transmit the collected result to the controller 4 in real time, which can be realized by using existing sensor products in a conventional manner; the number of the coolant temperature sensors can be two, one of which is arranged at the coolant inlet of the liquid storage tank 21 to collect the temperature of the coolant on the inlet side, and the other is arranged at the coolant outlet of the liquid storage tank 21 to collect the temperature of the coolant on the outlet side. Through the configuration design of the above two temperature sensors, more abundant feedback parameters can be provided for the intelligent operation of the controller 4, which is further beneficial to the system intelligence.

[0056] Specifically, when the energy storage battery liquid cooling temperature control system further includes the battery temperature sensor 32, starting the circulation pump 22 includes, but is not limited to, the following steps: adaptively adjusting the operating frequency of the circulation pump 22 so that the operating frequency is positively correlated with the battery temperature. In this way, the heat dissipation characteristics during the charge and discharge process of the energy storage battery can be utilized to make the power consumption of the circulation pump 22 dynamically adapt to the battery temperature, further improving the system energy efficiency.

[0057] Specifically, when the energy storage battery liquid cooling temperature control system further includes the battery temperature sensor 32 and the coolant temperature sensor, the compressor 11 is intermittently turned on, and the circulation pump 22 is turned on, including but not limited to the following steps: According to the ambient temperature, battery temperature, and coolant temperature, the working parameters of the compressor 11 and / or the working parameters of the circulation pump 22 are dynamically adjusted in combination with the PID algorithm. Among them, the working parameters of the compressor 11 include but are not limited to the intermittent opening period and / or rotation speed of the compressor 11, etc., and the working parameters of the circulation pump 22 include but are not limited to the working frequency of the circulation pump 22, etc. The PID algorithm is a closed-loop control algorithm based on the combination of three links: proportional, integral, and derivative, which is used to eliminate system errors and achieve stable control; it adjusts the output in real time to make the controlled object quickly and accurately reach the set value, and is widely used in industrial control, robotics, aerospace and other fields. Therefore, it can be applied to this embodiment to dynamically adjust the working parameters such as the intermittent opening period of the compressor 11, the rotation speed of the compressor 11, and / or the working frequency of the circulation pump 22 according to multiple feedback parameters such as the ambient temperature, the battery temperature, and the coolant temperature (such as the coolant temperature on the inlet side, the coolant temperature on the outlet side, or their temperature difference), so as to adapt to specific hybrid cooling requirements, and further improve the system energy efficiency by utilizing the heat dissipation characteristics during the charging and discharging process of the energy storage battery. In addition, the first preset temperature threshold and the second preset temperature threshold can also be dynamically adjusted according to the ambient temperature, the battery temperature, and the coolant temperature, etc., so as to further improve the switching flexibility and intelligence of natural cooling and compression cooling.

[0058] Preferably, it further includes but is not limited to a pressure sensor, a flow meter, etc. Among them, the pressure sensor is arranged in the compression cooling circuit, and the flow meter is arranged in the natural cooling circuit; the output ends of the pressure sensor and the flow meter are respectively communicatively connected to the input end of the controller 4. The aforementioned pressure sensor is used to collect the fluid pressure of the refrigerant in the compression cooling circuit in real time (which can be air pressure or hydraulic pressure), and transmit the collected result to the controller 4 in real time, which can be conventionally realized by using existing sensor products; the aforementioned flow meter is used to collect the flow rate of the cold liquid in the natural cooling circuit in real time, and transmit the collected result to the controller 4 in real time, which can be conventionally realized by using existing sensor products. Through the configuration design of the aforementioned pressure sensor and flow meter, more abundant feedback parameters can also be provided for the intelligent operation of the controller 4, which is further beneficial to the system intelligence.

[0059] In summary, the energy storage battery liquid cooling temperature control system combining natural cooling and compression refrigeration provided by this embodiment has the following technical effects:

[0060] (1) This embodiment provides a new energy storage battery liquid cooling temperature control solution that can combine natural cooling and compression refrigeration technologies for dual cooling mode switching, that is, it includes a compression cooling circuit using compression refrigeration technology, a natural cooling circuit parallel to the compression cooling circuit, an ambient temperature sensor, and a controller. Among them, the compression cooling circuit includes a compressor, a condenser tube, an expansion valve, and a first heat exchange plate that are sequentially circulated and connected. The natural cooling circuit includes a liquid storage tank, a circulation pump, a natural cooling coil, and a second heat exchange plate that are sequentially circulated and connected. The two heat exchange plates are respectively integrated in the evaporator and used for heat exchange with the energy storage battery. Through their hardware structure relationship, the compression cooling mode and the natural cooling mode can be switched at different ambient temperatures. Thus, the system energy efficiency can be improved by avoiding the long-term operation of the compressor, and the phenomena of poor oil return and insufficient lubrication can be eliminated by avoiding the long-term low speed of the compressor, thereby improving the reliability of the unit and extending its life;

[0061] (2) It can improve energy efficiency: that is, by adopting natural cooling at low ambient temperatures, the unnecessary energy consumption of the compressor is avoided, and the overall energy efficiency is improved;

[0062] (3) It can enhance reliability: that is, the running time of the compressor at low speed is reduced, the failure risk caused by poor oil return is reduced, and the reliability of the unit is improved;

[0063] (4) It can achieve the purpose of intelligent control: that is, the automatic switching of the cooling mode is realized through intelligent control, and the automation degree and intelligent level of the system are improved;

[0064] (5) It can improve the energy efficiency and reliability of the energy storage system at different ambient temperatures, and is particularly suitable for scenarios that require efficient thermal management such as lithium battery energy storage systems and flow battery energy storage systems, which is convenient for practical application and promotion.

[0065] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A liquid cooling temperature control system for energy storage batteries that combines natural cooling and compression refrigeration, characterized in that, It includes a compression cooling circuit adopting compression refrigeration technology, a natural cooling circuit connected in parallel with the compression cooling circuit, an ambient temperature sensor (31), and a controller (4). Among them, the compression cooling circuit includes a compressor (11), a condenser tube (12), an expansion valve (13), and a first heat exchange plate (14) that are sequentially connected in a cycle. The natural cooling circuit includes a liquid storage tank (21), a circulation pump (22), a natural cooling coil (23), and a second heat exchange plate (24) that are sequentially connected in a cycle. The first heat exchange plate (14) and the second heat exchange plate (24) are respectively integrated in an evaporator (40) and used for heat exchange with an energy storage battery. The output end of the ambient temperature sensor (31) is communicatively connected to the input end of the controller (4), and the output end of the controller (4) is respectively communicatively connected to the controlled end of the compressor (11) and the controlled end of the circulation pump (22) to switch between compression cooling and natural cooling at different ambient temperatures.

2. The energy storage battery liquid cooling temperature control system according to claim 1, wherein, It also includes an oil separator and an oil return capillary configured on the compressor (11). Among them, the oil separator is used to separate and collect the used lubricating oil of the compressor (11). The lubricating oil output end of the oil separator is connected to one end of the oil return capillary, and the other end of the oil return capillary is connected to the internal cavity of the compressor (11) to return the collected lubricating oil to the compressor cavity.

3. The energy storage battery liquid cooling temperature control system according to claim 2, wherein, The controlled end of the oil separator is communicatively connected to the output end of the controller (4) so that when the rotational speed of the compressor (11) is lower than a preset rotational speed threshold, it is periodically started and maintained for a preset duration under the control of the controller (4).

4. The energy storage battery liquid cooling temperature control system according to claim 1, characterized in that It also includes a cooling fan (6) for blowing air towards the condenser tube (12) and / or the natural cooling coil (23). The controlled end of the cooling fan (6) is communicatively connected to the output end of the controller (4).

5. The energy storage battery liquid cooling temperature control system according to claim 1, wherein The natural cooling circuit also includes an electric three-way valve (25) and a check valve (26). Among them, the common end of the electric three-way valve (25) is connected to the output end of the circulation pump (22), the first switching end of the electric three-way valve (25) is connected to one end of the natural cooling coil (23), the input end of the check valve (26) is connected to the other end of the natural cooling coil (23), and the second switching end of the electric three-way valve (25) and the output end of the check valve (26) are respectively connected to the output end of the second heat exchange plate (24). The controlled end of the electric three-way valve (25) is communicatively connected to the output end of the controller (4) so that when the ambient temperature is in a first preset temperature range, the common end and the first switching end are conducted and the common end and the second switching end are cut off under the control of the controller (4), and when the ambient temperature is in a second preset temperature range, the common end and the second switching end are conducted and the common end and the first switching end are cut off under the control of the controller (4). Among them, the first preset temperature range and the second preset temperature range have no intersection, and the first preset temperature range is lower than the second preset temperature range.

6. The energy storage battery liquid cooling temperature control system according to claim 1, wherein The natural cooling circuit further includes an electric heater (27) and a coolant temperature sensor, wherein the coolant temperature sensor is arranged at the coolant inlet of the liquid storage tank (21). The output end of the coolant temperature sensor is communicatively connected to the input end of the controller (4), and the controlled end of the electric heater (27) is communicatively connected to the output end of the controller (4), so as to start the electric heater (27) under the control of the controller (4) when the coolant temperature at the inlet side is lower than the third preset temperature threshold.

7. The energy storage battery liquid cooling temperature control system according to claim 1, characterized in that It further includes a pressure sensor and a flow meter, wherein the pressure sensor is arranged in the compression cooling circuit, and the flow meter is arranged in the natural cooling circuit. The output end of the pressure sensor and the output end of the flow meter are respectively communicatively connected to the input end of the controller (4).

8. The energy storage battery liquid cooling temperature control system according to claim 1, characterized in that, The controller (4) controls the compressor (11) and the circulation pump (22) according to the following working modes (A) to (C): (A) Natural cooling mode: When the ambient temperature is less than or equal to the first preset temperature threshold, the compressor (11) is turned off and the circulation pump (22) is turned on. (B) Hybrid cooling mode: When the ambient temperature is greater than the first preset temperature threshold and less than or equal to the second preset temperature threshold, the compressor (11) is intermittently turned on and the circulation pump (22) is turned on, wherein the second preset temperature threshold is greater than the first preset temperature threshold. (C) Compression cooling mode: When the ambient temperature is greater than the second preset temperature threshold, the compressor (11) is turned on and the circulation pump (22) is turned off.

9. The energy storage battery liquid cooling temperature control system according to claim 8, wherein, The energy storage battery liquid cooling temperature control system further includes a battery temperature sensor (32), wherein the battery temperature sensor (32) is arranged on the surface of the energy storage battery module, and the output end of the battery temperature sensor (32) is communicatively connected to the input end of the controller (4). Turning on the circulation pump (22) includes: adaptively adjusting the working frequency of the circulation pump (22) so that the working frequency is positively correlated with the battery temperature.

10. The energy storage battery liquid cooling temperature control system according to claim 8, wherein The energy storage battery liquid cooling temperature control system further includes a battery temperature sensor (32) and a coolant temperature sensor, wherein the battery temperature sensor (32) is arranged on the surface of the energy storage battery module, the coolant temperature sensor is arranged in the natural cooling circuit, and the output ends of the battery temperature sensor (32) and the coolant temperature sensor are respectively communicatively connected to the input end of the controller (4). Intermittently turning on the compressor (11) and turning on the circulation pump (22) includes: dynamically adjusting the working parameters of the compressor (11) and / or the working parameters of the circulation pump (22) according to the ambient temperature, the battery temperature and the coolant temperature, in combination with the PID algorithm, wherein the working parameters of the compressor (11) include the intermittent opening period and / or the rotation speed of the compressor (11), and the working parameters of the circulation pump (22) include the working frequency of the circulation pump (22).

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