Liquid cooling unit for energy storage system and operation method thereof

Abstract

The present invention discloses a liquid cooling unit for an energy storage system and an operation method thereof, which relates to the technical field of thermal management systems. The liquid cooling medium passes through the liquid cooling medium channel of the main circulation pump, and is divided into the liquid cooling medium channel of the first heat exchanger and the liquid cooling medium channel of the second heat exchanger, and converges from the liquid cooling medium channel of the first heat exchanger and the liquid cooling medium channel of the second heat exchanger to the liquid cooling medium channel of the radiator, and then flows back to the liquid cooling medium channel of the main circulation pump to form a cycle; the liquid cooling medium also passes through the liquid cooling medium channel of the main circulation pump, the liquid cooling medium channel of the second heat exchanger, and the liquid cooling medium channel of the first heat exchanger in sequence, and then flows back to the liquid cooling medium channel of the main circulation pump to form a cycle. The present invention mainly solves the problem of how to provide a liquid cooling unit that can perform thermal management on battery packs and converters at the same time; the present invention can realize centralized cooling of battery packs and power conversion devices (especially converters) in energy storage systems through a group of liquid cooling units.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal management systems, and in particular to a liquid cooling unit for an energy storage system and an operating method thereof. Background Art

[0002] An energy storage system is a system used to store and release electrical energy. It involves the conversion between electrical energy and chemical energy, as well as the conversion between electrical energy and electrical energy. In the above process, a lot of heat will be generated. If the heat cannot be discharged in time, the temperature of the energy storage system will rise, bringing safety hazards, and thus affecting the performance, life and normal operation of the energy storage system.

[0003] Lithium-ion battery packs are one of the core components of energy storage systems. They must be in a suitable temperature range to achieve their maximum energy efficiency. In the past, the optimal energy efficiency temperature range for lithium-ion battery packs was 15°C to 45°C. In order to control the temperature of the energy storage system (especially the lithium-ion battery pack), a heat dissipation system needs to be configured in the energy storage system to dissipate heat for the energy storage system. Among them, the liquid cooling system using phase change refrigeration technology is the most widely used heat dissipation solution.

[0004] With the continuous development of battery technology, the optimal energy efficiency temperature zone of the new generation of battery cells can reach 60°C. The temperature zone regulated by the traditional liquid cooling system is much lower than the optimal energy efficiency temperature zone of the new generation of battery cells. Taking into account factors such as environmental protection and energy saving, reducing system complexity, and controlling the overall cost of the energy storage system, the energy storage system using the new generation of battery cells does not need to use phase change refrigeration technology. Only a wind and water-linked liquid cooling system (that is, forced convection is used to dissipate heat for the coolant in the liquid cooling system) can complete the temperature control of the energy storage system.

[0005] At the same time, the power conversion system (PCS) in the energy storage system includes components such as controllers, power electronic devices, and necessary peripheral circuits, which also have heat dissipation requirements. Its optimal energy efficiency temperature zone is basically the same as the optimal energy efficiency temperature zone of the new generation of battery cells.

[0006] In summary, how to provide a liquid cooling unit for the energy storage system that can simultaneously perform thermal management on the battery pack and the converter has become one of the urgent issues to be solved. Summary of the invention

[0007] The object of the present invention is to provide a liquid cooling unit for an energy storage system and an operation method thereof, which can simultaneously perform thermal management on a battery pack and a power conversion device in the energy storage system.

[0008] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a liquid cooling unit for an energy storage system, used for dissipating heat for the energy storage system, wherein the energy storage system at least includes a battery pack and a power conversion device; the liquid cooling unit includes a main circulation pump, a radiator with a fan, and a first heat exchanger and a second heat exchanger capable of exchanging heat with a heating element; the first heat exchanger can exchange heat with the battery pack of the energy storage system, and the second heat exchanger can exchange heat with the power conversion device of the energy storage system; the liquid cooling medium can selectively pass through the liquid cooling medium channel of the main circulation pump and be diverted to the first heat exchanger ... The liquid-cooling medium passes through the liquid-cooling medium channel of the main circulation pump, the liquid-cooling medium channel of the second heat exchanger and the liquid-cooling medium channel of the second heat exchanger, and then flows from the liquid-cooling medium channel of the first heat exchanger and the liquid-cooling medium channel of the second heat exchanger to the liquid-cooling medium channel of the radiator, and then flows back to the liquid-cooling medium channel of the main circulation pump to form a circulation. The liquid-cooling medium can also selectively pass through the liquid-cooling medium channel of the main circulation pump, the liquid-cooling medium channel of the second heat exchanger and the liquid-cooling medium channel of the first heat exchanger in sequence, and then flows back to the liquid-cooling medium channel of the main circulation pump to form a circulation. At this time, the radiator is cut out of the liquid-cooling medium circulation.

[0009] In the above technical scheme, the liquid cooling unit for the energy storage system of the present invention also includes a first three-way valve, a second three-way valve and a stop valve; the first three-way valve and the second three-way valve both include a port, a b port and a c port which are opened / closed by the host computer, and the stop valve can be opened / closed by the host computer; the output end of the liquid cooling medium channel of the main circulation pump, the a port of the second three-way valve, the b port of the second three-way valve, the liquid cooling medium channel of the first heat exchanger, the stop valve, the liquid cooling medium channel of the radiator, and the input end of the liquid cooling medium channel of the main circulation pump are connected in sequence to form a circulation loop; the liquid cooling medium channel of the main circulation pump The output end of the liquid-cooling medium channel of the second heat exchanger, the a port of the first three-way valve, the b port of the first three-way valve, the stop valve, the liquid-cooling medium channel of the radiator, and the input end of the liquid-cooling medium channel of the main circulation pump are connected in sequence to form another circulation loop; the output end of the liquid-cooling medium channel of the main circulation pump, the liquid-cooling medium channel of the second heat exchanger, the c port of the second three-way valve, the b port of the second three-way valve, the liquid-cooling medium channel of the first heat exchanger, the b port of the first three-way valve, the c port of the first three-way valve, and the input end of the liquid-cooling medium channel of the main circulation pump are connected in sequence to form another circulation loop.

[0010] In the above technical solution, the liquid cooling unit for the energy storage system of the present invention further includes a heater for heating the liquid cooling medium; the heater is connected between the b port of the second three-way valve and the liquid cooling medium channel of the first heat exchanger.

[0011] In the above technical solution, the liquid cooling unit for the energy storage system of the present invention further comprises a filter for filtering the liquid cooling medium; the filter is connected to any node of the liquid cooling unit for the energy storage system.

[0012] In the above technical solution, the liquid cooling unit for the energy storage system of the present invention further includes a first pressure sensor and a first temperature sensor; the first pressure sensor and the first temperature sensor are both connected to the output end of the liquid cooling medium channel of the main circulation pump.

[0013] In the above technical solution, the liquid cooling unit for the energy storage system of the present invention further includes a second pressure sensor; the second pressure sensor is connected to the input end of the liquid cooling medium channel of the radiator.

[0014] In the above technical solution, the liquid cooling unit for the energy storage system of the present invention further includes an expansion tank for balancing the pressure of the liquid cooling medium; the expansion tank is connected to any node of the liquid cooling unit for the energy storage system.

[0015] In the above technical solution, the liquid cooling unit for the energy storage system of the present invention also includes a second temperature sensor and a third temperature sensor; the second temperature sensor is connected to the output end of the liquid cooling medium channel of the first heat exchanger; the third temperature sensor is connected to the output end of the liquid cooling medium channel of the second heat exchanger.

[0016] A method for operating a liquid cooling unit for an energy storage system, which is applied to the above-mentioned liquid cooling unit for an energy storage system; the method comprises:

[0017] Depending on the ambient temperature, it can selectively enter one of the following operating modes:

[0018] Refrigeration mode: the fan of the radiator is running, the main circulation pump is running, driving the liquid cooling medium to pass through the liquid cooling medium channel of the main circulation pump, and then being divided into the liquid cooling medium channel of the first heat exchanger and the liquid cooling medium channel of the second heat exchanger, and then being merged from the liquid cooling medium channel of the first heat exchanger and the liquid cooling medium channel of the second heat exchanger to the liquid cooling medium channel of the radiator, and then flowing back to the liquid cooling medium channel of the main circulation pump to form a cycle;

[0019] Self-circulation mode: the fan of the radiator stops, the main circulation pump runs, and drives the liquid cooling medium to pass through the liquid cooling medium channel of the main circulation pump, and is divided into the liquid cooling medium channel of the first heat exchanger and the liquid cooling medium channel of the second heat exchanger, and then the liquid cooling medium channel of the first heat exchanger and the liquid cooling medium channel of the second heat exchanger are merged into the liquid cooling medium channel of the radiator, and then refluxed to the liquid cooling medium channel of the main circulation pump to form a cycle;

[0020] Waste heat utilization mode / heating mode: the fan of the radiator stops, the main circulation pump runs, and drives the liquid cooling medium to pass through the liquid cooling medium channel of the main circulation pump, the liquid cooling medium channel of the second heat exchanger, and the liquid cooling medium channel of the first heat exchanger in sequence, and then flows back to the liquid cooling medium channel of the main circulation pump to form a circulation. At this time, the radiator is cut out of the liquid cooling medium circulation;

[0021] In the heating mode, the liquid cooling medium is heated by the heater before flowing into the liquid cooling medium channel of the first heat exchanger.

[0022] In the above technical solution, the liquid cooling unit for the energy storage system also includes a first three-way valve, a second three-way valve and a stop valve; the first three-way valve and the second three-way valve both include a port, a b port and a c port which are opened / closed by the host computer, and the stop valve can be opened / closed by the host computer; the output end of the liquid cooling medium channel of the main circulation pump, the a port of the second three-way valve, the b port of the second three-way valve, the liquid cooling medium channel of the first heat exchanger, the stop valve, the liquid cooling medium channel of the radiator, and the input end of the liquid cooling medium channel of the main circulation pump are connected in sequence to form a circulation loop; the liquid cooling medium channel of the main circulation pump The output end, the liquid-cooling medium channel of the second heat exchanger, the a port of the first three-way valve, the b port of the first three-way valve, the stop valve, the liquid-cooling medium channel of the radiator, and the input end of the liquid-cooling medium channel of the main circulation pump are connected in sequence to form another circulation loop; the output end of the liquid-cooling medium channel of the main circulation pump, the liquid-cooling medium channel of the second heat exchanger, the c port of the second three-way valve, the b port of the second three-way valve, the liquid-cooling medium channel of the first heat exchanger, the b port of the first three-way valve, the c port of the first three-way valve, and the input end of the liquid-cooling medium channel of the main circulation pump are connected in sequence to form another circulation loop;

[0023] When entering the refrigeration mode or the self-circulation mode: the a port and the b port of the first three-way valve are opened, the c port of the first three-way valve is closed, and the a port and the b port of the second three-way valve are opened, and the c port of the second three-way valve is closed, so that the liquid cooling medium passes through the liquid cooling medium channel of the main circulation pump, is divided into the liquid cooling medium channel of the first heat exchanger and the liquid cooling medium channel of the second heat exchanger, and is merged from the liquid cooling medium channel of the first heat exchanger and the liquid cooling medium channel of the second heat exchanger to the liquid cooling medium channel of the radiator, and then flows back to the liquid cooling medium channel of the main circulation pump to form a cycle;

[0024] When entering the waste heat utilization mode or the heating mode: the b port and the c port of the first three-way valve are opened, the a port of the first three-way valve is closed, and the b port and the c port of the second three-way valve are opened, and the a port of the second three-way valve is closed, so that the liquid-cooling medium passes through the liquid-cooling medium channel of the main circulation pump, the liquid-cooling medium channel of the second heat exchanger, and the liquid-cooling medium channel of the first heat exchanger in sequence, and then flows back to the liquid-cooling medium channel of the main circulation pump to form a circulation. At this time, the radiator is cut out of the liquid-cooling medium circulation.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: the liquid cooling unit for the energy storage system of the present invention and the operating method thereof do not require the provision of a phase change refrigeration mechanism. Under medium and high temperature environments, a group of liquid cooling units can be used to achieve centralized cooling of the battery pack and the power conversion device (especially the inverter) in the energy storage system to reduce the temperature of the battery pack and the power conversion device, thereby reducing the number of components, complexity and economic cost of the liquid cooling unit and the energy storage system, and improving the operating stability of the liquid cooling unit and the energy storage system; under low temperature environments, the heat generated by the power conversion device can also be used to heat the battery pack, so that the waste heat can be effectively utilized, maintaining the normal operation of the energy storage system while being more energy-saving and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a system structure diagram of the present invention.

[0027] Figure 2 It is a schematic diagram of the flow direction of the liquid cooling medium in the refrigeration mode or the self-circulation mode of the present invention.

[0028] Figure 3 It is a schematic diagram of the flow direction of the liquid cooling medium in the waste heat utilization mode or the heating mode of the present invention.

[0029] The accompanying drawings are marked as follows: 1. main circulation pump; 2. radiator; 3. fan; 4. filter; 5. first heat exchanger; 6. heater; 7. second heat exchanger; 8. expansion tank; 9-1. first three-way valve; 9-2. second three-way valve; 9-3. stop valve; TT1. first temperature sensor; TT2. second temperature sensor; TT3. third temperature sensor; PT1. first pressure sensor; PT2. second pressure sensor; 10. battery pack; 20. inverter. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] This embodiment provides a liquid cooling unit for an energy storage system, which is used to dissipate heat for the energy storage system.

[0032] The energy storage system at least includes a battery pack 10 and a power conversion device. In this embodiment, a converter 20 (Power Conversion System, PCS) commonly used in energy storage systems is taken as a typical case of the power conversion device to specifically illustrate the technical solution of the present invention.

[0033] See also Figure 1 The liquid cooling unit for the energy storage system of this embodiment includes a main circulation pump 1, a radiator 2 with a fan 3, and a first heat exchanger 5 and a second heat exchanger 7 capable of exchanging heat with a heating element; wherein the main circulation pump 1 is a liquid pump capable of driving the flow of a liquid cooling medium, and the radiator 2 is a metal radiator 2 having a plurality of liquid flow channels, and cooling fins are arranged between each liquid flow channel, which can dissipate heat for the liquid cooling medium flowing through it by forced convection or natural convection.

[0034] The first heat exchanger 5 can exchange heat with the battery pack 10 of the energy storage system. In this embodiment, the first heat exchanger 5 is a metal plate with good thermal conductivity and an internal flow channel, which is attached / built-in to the battery pack 10 of the energy storage system; the second heat exchanger 7 can exchange heat with the power conversion device of the energy storage system. In some possible embodiments, the second heat exchanger 7 is a metal plate with good thermal conductivity and an internal flow channel, which is attached / built-in to the power conversion device of the energy storage system. In other possible embodiments, the second heat exchanger 7 is a liquid-cooled heat dissipation channel integrated in the power conversion device itself, and can be connected to the second heat exchanger 7 through the liquid-cooling medium interface integrated in the power conversion device itself.

[0035] The liquid cooling medium can selectively pass through the liquid cooling medium channel of the main circulation pump 1, be divided into the liquid cooling medium channel of the first heat exchanger 5 and the liquid cooling medium channel of the second heat exchanger 7, and converge from the liquid cooling medium channel of the first heat exchanger 5 and the liquid cooling medium channel of the second heat exchanger 7 to the liquid cooling medium channel of the radiator 2, and then flow back to the liquid cooling medium channel of the main circulation pump 1 to form a cycle;

[0036] The liquid-cooling medium can also selectively pass through the liquid-cooling medium channel of the main circulation pump 1, the liquid-cooling medium channel of the second heat exchanger 7 and the liquid-cooling medium channel of the first heat exchanger 5 in sequence, and then flow back to the liquid-cooling medium channel of the main circulation pump 1 to form a circulation. At this time, the radiator 2 is cut out of the liquid-cooling medium circulation.

[0037] Specifically, the liquid cooling unit for the energy storage system of this embodiment also includes a first three-way valve 9-1, a second three-way valve 9-2 and a stop valve 9-3, wherein the first three-way valve 9-1, the second three-way valve 9-2 and the stop valve 9-3 are all electrically controlled valves, such as electric three-way valves or magnetically controlled three-way valves; the first three-way valve 9-1 and the second three-way valve 9-2 both include a port, b port and c port that are opened / closed by the host computer, and the stop valve 9-3 can be opened / closed by the host computer; the output end of the liquid-cooling medium channel of the main circulation pump 1, the a port of the second three-way valve 9-2, the b port of the second three-way valve 9-2, the liquid-cooling medium channel of the first heat exchanger 5, the stop valve 9-3, the liquid-cooling medium channel of the radiator 2, and the input end of the liquid-cooling medium channel of the main circulation pump 1 are connected in sequence to form a circulation loop. ; The output end of the liquid-cooling medium channel of the main circulation pump 1, the liquid-cooling medium channel of the second heat exchanger 7, the a port of the first three-way valve 9-1, the b port of the first three-way valve 9-1, the stop valve 9-3, the liquid-cooling medium channel of the radiator 2, and the input end of the liquid-cooling medium channel of the main circulation pump 1 are connected in sequence to form another circulation loop; the output end of the liquid-cooling medium channel of the main circulation pump 1, the liquid-cooling medium channel of the second heat exchanger 7, the c port of the second three-way valve 9-2, the b port of the second three-way valve 9-2, the liquid-cooling medium channel of the first heat exchanger 5, the b port of the first three-way valve 9-1, the c port of the first three-way valve 9-1, and the input end of the liquid-cooling medium channel of the main circulation pump 1 are connected in sequence to form another circulation loop; it can be understood that the above-mentioned nodes are all connected through pipes suitable for circulating liquid cooling medium.

[0038] Furthermore, the liquid cooling unit for the energy storage system of this embodiment also includes a heater 6 for heating the liquid cooling medium, which is an electric liquid heater 6 and is used to prevent the temperature of the liquid cooling medium from being too low; the heater 6 is connected between the b port of the second three-way valve 9-2 and the liquid cooling medium channel of the first heat exchanger 5.

[0039] Furthermore, the liquid cooling unit for the energy storage system of the present embodiment also includes a filter 4 for filtering the liquid cooling medium. The filter 4 is a liquid cooling medium-specific filter 4 commonly used in the prior art, which can filter out impurities such as particles, flocs and colloids in the liquid cooling medium, so that the liquid cooling medium can maintain good thermal conductivity and fluidity; the filter 4 is connected to any node of the liquid cooling unit for the energy storage system. In the present embodiment, the filter 4 is connected to the input end of the liquid cooling medium channel of the main circulation pump 1.

[0040] Furthermore, the liquid cooling unit for the energy storage system of the present embodiment further includes a first pressure sensor PT1 and a first temperature sensor TT1, and the first pressure sensor PT1 and the first temperature sensor TT1 are both connected to the output end of the liquid cooling medium channel of the main circulation pump 1; it can be understood that the first pressure sensor PT1 and the first temperature sensor TT1 are respectively connected to the host computer (such as a programmable controller, an embedded system, and an industrial computer) by signal, so as to transmit the liquid cooling medium pressure and temperature (i.e., the output hydraulic pressure and temperature of the main circulation pump 1, which are also the output hydraulic pressure and temperature of the liquid cooling unit) at the output end of the liquid cooling medium channel of the main circulation pump 1 to the host computer.

[0041] Furthermore, the liquid cooling unit for the energy storage system of the present embodiment further includes a second pressure sensor PT2, which is connected to the input end of the liquid cooling medium channel of the radiator 2; it can be understood that the second pressure sensor PT2 is connected to a host computer (such as a programmable controller, an embedded system, and an industrial computer) by signal to transmit the liquid cooling medium pressure at the input end of the liquid cooling medium channel of the radiator 2 (i.e., the input hydraulic pressure of the radiator 2, which is also the input hydraulic pressure of the liquid cooling unit) to the host computer.

[0042] In the liquid cooling unit for energy storage system, due to factors such as temperature change, small leakage or evaporation of liquid cooling medium, too little / too much filling amount of liquid cooling medium and operation fluctuation of main circulation pump 1, the pressure of liquid cooling medium in the liquid cooling unit for energy storage system may change, which may affect the normal operation of the liquid cooling unit for energy storage system and even cause pipeline damage or falling off; to solve the above problems, the liquid cooling unit for energy storage system of this embodiment also includes an expansion tank 8 for balancing the pressure of liquid cooling medium, and the expansion tank 8 is connected to any node of the liquid cooling unit for energy storage system; in this embodiment, the expansion tank 8 is connected to the input end of the liquid cooling medium channel of the main circulation pump 1; the expansion tank 8 is provided to provide additional pressure / reduced pressure to the liquid cooling unit for the energy storage system, thereby ensuring that the pressure of the liquid cooling unit for the energy storage system is maintained in an appropriate range; in some possible embodiments, the electronic control device of the expansion tank 8 is connected to the host computer (such as a programmable controller, an embedded system, and an industrial computer) by signal, and the host computer controls the operation of the electronic control device of the expansion tank 8 according to the liquid cooling medium pressure transmitted by the first pressure sensor PT1 and / or the second pressure sensor PT2 to achieve closed-loop control.

[0043] Furthermore, the liquid cooling unit for the energy storage system of this embodiment also includes a second temperature sensor TT2 and a third temperature sensor TT3, the second temperature sensor TT2 is connected to the output end of the liquid cooling medium channel of the first heat exchanger 5, and the third temperature sensor TT3 is connected to the output end of the liquid cooling medium channel of the second heat exchanger 7; the second temperature sensor TT2 and the third temperature sensor TT3 are respectively connected to the host computer (such as a programmable controller, an embedded system, and an industrial computer) by signal, so as to transmit the liquid cooling medium temperature at the output end of the liquid cooling medium channel of the first heat exchanger 5 (i.e., the liquid outlet temperature of the battery pack 10) and the liquid cooling medium temperature at the output end of the liquid cooling medium channel of the second heat exchanger 7 (i.e., the power conversion device temperature of the battery pack 10) to the host computer.

[0044] This embodiment also provides an operation method of a liquid cooling unit for an energy storage system, which is applied to the above-mentioned liquid cooling unit for an energy storage system.

[0045] See also Figure 1-Figure 3 , the method comprising:

[0046] Depending on the ambient temperature, it can selectively enter one of the following operating modes:

[0047] Cooling mode (such as Figure 2 As shown): the fan 3 of the radiator 2 runs, and the main circulation pump 1 runs, driving the liquid-cooling medium to pass through the liquid-cooling medium channel of the main circulation pump 1, and then being diverted to the liquid-cooling medium channel of the first heat exchanger 5 and the liquid-cooling medium channel of the second heat exchanger 7, and then converging from the liquid-cooling medium channel of the first heat exchanger 5 and the liquid-cooling medium channel of the second heat exchanger 7 to the liquid-cooling medium channel of the radiator 2, and then flowing back to the liquid-cooling medium channel of the main circulation pump 1 to form a cycle.

[0048] The cooling mode is suitable for high temperature environments (for example, the ambient temperature is ≥ 30°C). At this time, the fan 3 of the radiator 2 runs to dissipate the heat of the high-temperature liquid cooling medium flowing through the radiator 2 in a forced convection manner, so that the high-temperature liquid cooling medium flowing through the radiator 2 can be quickly cooled.

[0049] Self-circulating mode (such as Figure 2 As shown): The fan 3 of the radiator 2 stops, and the main circulation pump 1 runs, driving the liquid-cooling medium to pass through the liquid-cooling medium channel of the main circulation pump 1, and then being diverted to the liquid-cooling medium channel of the first heat exchanger 5 and the liquid-cooling medium channel of the second heat exchanger 7, and then converging from the liquid-cooling medium channel of the first heat exchanger 5 and the liquid-cooling medium channel of the second heat exchanger 7 to the liquid-cooling medium channel of the radiator 2, and then flowing back to the liquid-cooling medium channel of the main circulation pump 1 to form a cycle.

[0050] The self-circulation mode is suitable for medium temperature environments (for example, 10℃≤ambient temperature<30℃). At this time, the fan 3 of the radiator 2 stops, and the natural heat exchange between the radiator 2 and the air is sufficient to dissipate the heat of the high-temperature liquid cooling medium flowing through the radiator 2, so that the high-temperature liquid cooling medium flowing through the radiator 2 can be cooled; the fan 3 stops, which can save the electric energy consumed by the liquid cooling unit of the energy storage system.

[0051] Waste heat utilization mode / heating mode (such as Figure 3 As shown): The fan 3 of the radiator 2 stops, and the main circulation pump 1 runs, driving the liquid cooling medium to pass through the liquid cooling medium channel of the main circulation pump 1, the liquid cooling medium channel of the second heat exchanger 7 and the liquid cooling medium channel of the first heat exchanger 5 in sequence, and then flows back to the liquid cooling medium channel of the main circulation pump 1 to form a circulation. At this time, the radiator 2 is cut out of the liquid cooling medium circulation.

[0052] In the heating mode, the liquid cooling medium is heated by the heater 6 before flowing into the liquid cooling medium channel of the first heat exchanger 5 .

[0053] The waste heat utilization mode is applicable to low temperature environments (for example, 0°C ≤ ambient temperature < 10°C), and the heating mode is applicable to ultra-low temperature environments (for example, the ambient temperature is lower than the freezing point of the liquid cooling medium, or the ambient temperature is lower than the minimum operating temperature of the battery); the battery pack 10 of the energy storage system does not generate enough heat when it is operated in a low temperature environment, and too low a temperature will affect the performance of the battery pack 10. In addition, if the temperature of the liquid cooling medium drops below its freezing point and freezes, it will damage the liquid cooling unit; the waste heat utilization mode / heating mode is applicable to cold environments. At this time, the fan 3 of the radiator 2 stops (the upper computer can also be used to prohibit the operation of the fan 3 through software) to prevent additional air flow; the power electronic devices of the power conversion device can also be used normally in a low temperature environment and will generate heat. Through the second The heat exchanger 7 absorbs the heat of the power conversion device, maintains the temperature of the power conversion device, and can heat the liquid cooling medium through the heat of the power conversion device. When the liquid cooling medium with a higher temperature flows to the first heat exchanger 5, the heat can be transferred to the battery pack 10 through the first heat exchanger 5, thereby maintaining the temperature of the battery pack 10; at a colder ambient temperature (for example, the ambient temperature is less than 0°C), the heat generated by the normal operation of the power conversion device is not enough to raise the temperature of the liquid cooling medium to a suitable temperature range, so that the battery pack 10, the power conversion device and the liquid cooling unit of the energy storage system are at risk of shutdown and damage; at this time, the heater 6 can be turned on to provide more heat to the liquid cooling medium through the heater 6, so that the liquid cooling medium is heated to a suitable temperature range, thereby maintaining the normal operation of the battery pack 10, the power conversion device and the liquid cooling unit of the energy storage system.

[0054] It should be noted that in the waste heat utilization mode / heating mode, the radiator 2 is cut out of the liquid cooling medium circulation, and the liquid cooling medium does not pass through the radiator 2 to prevent the liquid cooling medium from losing heat at the radiator 2 .

[0055] As mentioned above, when entering the refrigeration mode or the self-circulation mode: the a port and the b port of the first three-way valve 9-1 are opened, the c port of the first three-way valve 9-1 is closed, and the a port and the b port of the second three-way valve 9-2 are opened, and the c port of the second three-way valve 9-2 is closed, so that the liquid-cooling medium passes through the liquid-cooling medium channel of the main circulation pump 1, is diverted to the liquid-cooling medium channel of the first heat exchanger 5 and the liquid-cooling medium channel of the second heat exchanger 7, and is converged from the liquid-cooling medium channel of the first heat exchanger 5 and the liquid-cooling medium channel of the second heat exchanger 7 to the liquid-cooling medium channel of the radiator 2, and then flows back to the liquid-cooling medium channel of the main circulation pump 1, forming a cycle;

[0056] As mentioned above, when entering the waste heat utilization mode or the heating mode: the b port and the c port of the first three-way valve 9-1 are opened, the a port of the first three-way valve 9-1 is closed, and the b port and the c port of the second three-way valve 9-2 are opened, and the a port of the second three-way valve 9-2 is closed, so that the liquid-cooling medium passes through the liquid-cooling medium channel of the main circulation pump 1, the liquid-cooling medium channel of the second heat exchanger 7 and the liquid-cooling medium channel of the first heat exchanger 5 in sequence, and then flows back to the liquid-cooling medium channel of the main circulation pump 1 to form a circulation. At this time, the radiator 2 is cut out of the liquid-cooling medium circulation.

[0057] The liquid cooling unit for the energy storage system of this embodiment and its operation method have the following working principles: in the cooling mode or the self-circulation mode, the liquid cooling medium passes through the liquid cooling medium channel of the main circulation pump 1, and is distributed by the first three-way valve 9-1 and the second three-way valve 9-2, so that the liquid cooling medium is diverted to the liquid cooling medium channel of the first heat exchanger 5 and the liquid cooling medium channel of the second heat exchanger 7. At this time, the first heat exchanger 5 absorbs the heat of the battery pack 10, and the second heat exchanger 7 absorbs the heat of the power conversion device. The liquid cooling medium with a higher temperature flows from the liquid cooling medium channel of the first heat exchanger 5 and the liquid cooling medium channel of the second heat exchanger 7 to the liquid cooling medium channel of the radiator 2, and then enters the liquid cooling medium channel of the main circulation pump 1; at the radiator 2, the liquid cooling medium in the radiator 2 can be cooled by forced convection or by natural heat exchange between the radiator 2 and the air; in the waste heat utilization mode or the heating mode, the liquid cooling medium The liquid cooling medium passes through the liquid cooling medium channel of the main circulation pump 1 and is distributed by the first three-way valve 9-1 and the second three-way valve 9-2, so that the liquid cooling medium passes through the liquid cooling medium channel of the second heat exchanger 7 and the liquid cooling medium channel of the first heat exchanger 5 in turn, and then flows back to the liquid cooling medium channel of the main circulation pump 1 to form a cycle. In the above process, the liquid cooling medium passes through the second heat exchanger 7, absorbs the heat of the power conversion device, and while maintaining the temperature of the power conversion device, the liquid cooling medium can be heated by the heat of the power conversion device. When the liquid cooling medium with a higher temperature flows to the first heat exchanger 5, the heat can be transferred to the battery pack 10 through the first heat exchanger 5, thereby maintaining the temperature of the battery pack 10. In addition, through the distribution of the first three-way valve 9-1 and the second three-way valve 9-2, and the shut-off of the shut-off valve 9-3, the radiator 2 is cut out of the liquid cooling medium circulation, and the liquid cooling medium does not pass through the radiator 2, so as to prevent the liquid cooling medium from losing heat at the radiator 2.

[0058] It can be understood that the liquid cooling unit for the energy storage system of this embodiment is configured with a host computer (such as a programmable controller, an embedded system and an industrial computer); the actuators of the first three-way valve 9-1, the second three-way valve 9-2 and the stop valve 9-3 are all connected to the host computer through a universal input / output interface or a communication interface, so that the first three-way valve 9-1, the second three-way valve 9-2 and the stop valve 9-3 can be controlled by the host computer, thereby realizing independent opening / closing of port a, port b and port c, and realizing opening / closing of the stop valve 9-3; the first temperature sensor TT1, the second temperature sensor TT2, the third temperature sensor TT3, the first pressure sensor PT1 and the second pressure sensor PT2 are all connected to the host computer through a universal input / output interface, an analog interface or a communication interface.

[0059] It is understandable that the detection of ambient temperature can be achieved by installing a temperature sensor near the energy storage system or in the computer room / chassis. The temperature sensor is connected to the host computer through an analog output interface or a communication interface to achieve signal connection, thereby realizing the detection and transmission of the ambient temperature.

[0060] In the liquid cooling unit for the energy storage system of this embodiment and the operation method thereof, the liquid cooling medium can selectively pass through the liquid cooling medium channel of the main circulation pump 1, be diverted to the liquid cooling medium channel of the first heat exchanger 5 and the liquid cooling medium channel of the second heat exchanger 7, and converge from the liquid cooling medium channel of the first heat exchanger 5 and the liquid cooling medium channel of the second heat exchanger 7 to the liquid cooling medium channel of the radiator 2, and then flow back to the liquid cooling medium channel of the main circulation pump 1 to form a circulation; the liquid cooling medium can also selectively pass through the liquid cooling medium channel of the main circulation pump 1, the liquid cooling medium channel of the second heat exchanger 7 and the liquid cooling medium channel of the first heat exchanger 5 in sequence, and then flow back to the liquid cooling medium channel of the main circulation pump 1 to form a circulation. At this time, the radiator 2 is cut out of the liquid cooling medium circulation.

[0061] The energy storage system liquid cooling unit and its operation method of this embodiment do not need to set up a phase change refrigeration mechanism. In medium and high temperature environments, a group of liquid cooling units can realize centralized cooling of the battery pack 10 and the power conversion device (especially the converter 20) in the energy storage system to reduce the temperature of the battery pack 10 and the power conversion device, reduce the number of components, complexity and economic cost of the liquid cooling unit and the energy storage system, and improve the operation stability of the liquid cooling unit and the energy storage system; in low temperature environments, the heat generated by the power conversion device can also be used to heat the battery pack 10, so that the waste heat can be effectively utilized, while maintaining the normal operation of the energy storage system, it is more energy-saving and environmentally friendly.

[0062] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A liquid cooling unit for an energy storage system, used to dissipate heat for the energy storage system, wherein the energy storage system comprises at least a battery pack and a power conversion device; characterized in that: It includes a main circulation pump, a radiator with a fan, and a first heat exchanger and a second heat exchanger capable of exchanging heat with a heating element; The first heat exchanger is capable of exchanging heat with the battery pack of the energy storage system, and the second heat exchanger is capable of exchanging heat with the power conversion device of the energy storage system; The liquid cooling medium can selectively pass through the liquid cooling medium channel of the main circulation pump, be divided into the liquid cooling medium channel of the first heat exchanger and the liquid cooling medium channel of the second heat exchanger, and converge from the liquid cooling medium channel of the first heat exchanger and the liquid cooling medium channel of the second heat exchanger to the liquid cooling medium channel of the radiator, and then flow back to the liquid cooling medium channel of the main circulation pump to form a cycle; The liquid cooling medium can also selectively pass through the liquid cooling medium channel of the main circulation pump, the liquid cooling medium channel of the second heat exchanger and the liquid cooling medium channel of the first heat exchanger in sequence, and then flow back to the liquid cooling medium channel of the main circulation pump to form a circulation. At this time, the radiator is cut out of the liquid cooling medium circulation. It also includes a first three-way valve, a second three-way valve and a stop valve; The first three-way valve and the second three-way valve each include a port, a port and a port c which are opened / closed by the control of the host computer, and the stop valve can be opened / closed by the control of the host computer; The output end of the liquid cooling medium channel of the main circulation pump, the port a of the second three-way valve, the port b of the second three-way valve, the liquid cooling medium channel of the first heat exchanger, the stop valve, the liquid cooling medium channel of the radiator, and the input end of the liquid cooling medium channel of the main circulation pump are connected in sequence to form a circulation loop; The output end of the liquid cooling medium channel of the main circulation pump, the liquid cooling medium channel of the second heat exchanger, the a port of the first three-way valve, the b port of the first three-way valve, the stop valve, the liquid cooling medium channel of the radiator, and the input end of the liquid cooling medium channel of the main circulation pump are connected in sequence to form another circulation loop; The output end of the liquid-cooling medium channel of the main circulation pump, the liquid-cooling medium channel of the second heat exchanger, the c port of the second three-way valve, the b port of the second three-way valve, the liquid-cooling medium channel of the first heat exchanger, the b port of the first three-way valve, the c port of the first three-way valve, and the input end of the liquid-cooling medium channel of the main circulation pump are connected in sequence to form another circulation loop.

2. The liquid cooling unit for energy storage system according to claim 1, characterized in that: Also included is a heater for heating the liquid cooling medium; The heater is connected between the port b of the second three-way valve and the liquid cooling medium channel of the first heat exchanger.

3. The liquid cooling unit for energy storage system according to claim 1 or 2, characterized in that: Also included is a filter for filtering the liquid cooling medium; The filter is connected to any node of the liquid cooling unit for the energy storage system.

4. The liquid cooling unit for energy storage system according to claim 1 or 2, characterized in that: Also included is a first pressure sensor and a first temperature sensor; The first pressure sensor and the first temperature sensor are both connected to the output end of the liquid cooling medium channel of the main circulation pump.

5. The liquid cooling unit for energy storage system according to claim 1 or 2, characterized in that: Also included is a second pressure sensor; The second pressure sensor is connected to the input end of the liquid cooling medium channel of the radiator.

6. The liquid cooling unit for energy storage system according to claim 5, characterized in that: Also included is an expansion tank for balancing the pressure of the liquid cooling medium; The expansion tank is connected to any node of the liquid cooling unit for the energy storage system.

7. The liquid cooling unit for energy storage system according to claim 1 or 2, characterized in that: Also including a second temperature sensor and a third temperature sensor; The second temperature sensor is connected to the output end of the liquid cooling medium channel of the first heat exchanger; The third temperature sensor is connected to the output end of the liquid cooling medium channel of the second heat exchanger.

8. A method for operating a liquid cooling unit for an energy storage system, characterized in that: It is applied to the liquid cooling unit for energy storage system according to any one of claims 1 to 7; the method comprises: Depending on the ambient temperature, it can selectively enter one of the following operating modes: Refrigeration mode: the fan of the radiator is running, the main circulation pump is running, driving the liquid cooling medium to pass through the liquid cooling medium channel of the main circulation pump, and then being divided into the liquid cooling medium channel of the first heat exchanger and the liquid cooling medium channel of the second heat exchanger, and then being merged from the liquid cooling medium channel of the first heat exchanger and the liquid cooling medium channel of the second heat exchanger to the liquid cooling medium channel of the radiator, and then flowing back to the liquid cooling medium channel of the main circulation pump to form a cycle; Self-circulation mode: the fan of the radiator stops, the main circulation pump runs, and drives the liquid cooling medium to pass through the liquid cooling medium channel of the main circulation pump, and is divided into the liquid cooling medium channel of the first heat exchanger and the liquid cooling medium channel of the second heat exchanger, and then the liquid cooling medium channel of the first heat exchanger and the liquid cooling medium channel of the second heat exchanger are merged into the liquid cooling medium channel of the radiator, and then refluxed to the liquid cooling medium channel of the main circulation pump to form a cycle; Waste heat utilization mode / heating mode: the fan of the radiator stops, the main circulation pump runs, and drives the liquid cooling medium to pass through the liquid cooling medium channel of the main circulation pump, the liquid cooling medium channel of the second heat exchanger, and the liquid cooling medium channel of the first heat exchanger in sequence, and then flows back to the liquid cooling medium channel of the main circulation pump to form a circulation. At this time, the radiator is cut out of the liquid cooling medium circulation; In the heating mode, the liquid cooling medium is heated by the heater before flowing into the liquid cooling medium channel of the first heat exchanger.

9. The method for operating a liquid cooling unit for an energy storage system according to claim 8, characterized in that: The liquid cooling unit for the energy storage system further includes a first three-way valve, a second three-way valve and a stop valve; The first three-way valve and the second three-way valve each include a port, a port and a port c which are opened / closed by the control of the host computer, and the stop valve can be opened / closed by the control of the host computer; The output end of the liquid cooling medium channel of the main circulation pump, the port a of the second three-way valve, the port b of the second three-way valve, the liquid cooling medium channel of the first heat exchanger, the stop valve, the liquid cooling medium channel of the radiator, and the input end of the liquid cooling medium channel of the main circulation pump are connected in sequence to form a circulation loop; The output end of the liquid cooling medium channel of the main circulation pump, the liquid cooling medium channel of the second heat exchanger, the a port of the first three-way valve, the b port of the first three-way valve, the stop valve, the liquid cooling medium channel of the radiator, and the input end of the liquid cooling medium channel of the main circulation pump are connected in sequence to form another circulation loop; The output end of the liquid-cooling medium channel of the main circulation pump, the liquid-cooling medium channel of the second heat exchanger, the c port of the second three-way valve, the b port of the second three-way valve, the liquid-cooling medium channel of the first heat exchanger, the b port of the first three-way valve, the c port of the first three-way valve, and the input end of the liquid-cooling medium channel of the main circulation pump are connected in sequence to form another circulation loop; When entering the refrigeration mode or the self-circulation mode: the a port and the b port of the first three-way valve are opened, the c port of the first three-way valve is closed, and the a port and the b port of the second three-way valve are opened, and the c port of the second three-way valve is closed, so that the liquid cooling medium passes through the liquid cooling medium channel of the main circulation pump, is divided into the liquid cooling medium channel of the first heat exchanger and the liquid cooling medium channel of the second heat exchanger, and is merged from the liquid cooling medium channel of the first heat exchanger and the liquid cooling medium channel of the second heat exchanger to the liquid cooling medium channel of the radiator, and then flows back to the liquid cooling medium channel of the main circulation pump to form a cycle; When entering the waste heat utilization mode or the heating mode: the b port and the c port of the first three-way valve are opened, the a port of the first three-way valve is closed, and the b port and the c port of the second three-way valve are opened, and the a port of the second three-way valve is closed, so that the liquid-cooling medium passes through the liquid-cooling medium channel of the main circulation pump, the liquid-cooling medium channel of the second heat exchanger, and the liquid-cooling medium channel of the first heat exchanger in sequence, and then flows back to the liquid-cooling medium channel of the main circulation pump to form a circulation. At this time, the radiator is cut out of the liquid-cooling medium circulation.

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