Battery thermal management system

Abstract

The invention discloses a battery thermal management system which comprises a natural cooling mode, a refrigeration cycle mode, a battery module and a control module. The natural cooling mode is connected with the battery module through a natural cooling loop and is used for cooling the battery module; the refrigeration cycle mode is connected with the battery module through a refrigeration cycle loop and is used for cooling the battery module; the battery module comprises a battery management system, the control module is electrically connected with the battery management system, and the control module is used for obtaining a current environment temperature signal and a current state signal, collected by the battery management system, of the battery module. And according to the current environment temperature signal and the current state signal of the battery module, the natural cooling mode and / or the refrigeration cycle mode are / is controlled to be opened or closed. By means of the structure, according to the current environment temperature signal and the current state signal of the battery module, start-stop control over different cooling modes is more accurately achieved, and it is guaranteed that the temperature of the battery module is always within the preset temperature range.

Description

Technical Field

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

[0002] In today's society, vehicles have become an indispensable means of transportation in people's daily lives, and the maintenance and management of battery modules in vehicles have gradually become more important. Battery modules generate a lot of heat during the operation of the car. If the heat is not dissipated in time, the temperature of the battery module will rise. Excessive temperature may cause an explosion, resulting in a greater safety hazard. Therefore, the temperature of the battery module during charging and discharging must be controlled within a certain safety range.

[0003] Normally, battery module cooling methods include compressor cooling and natural cooling, and the operating compressor cooling or natural cooling method is determined by obtaining the ambient temperature value. However, there is a certain delay time when the operating mode is determined solely by ambient temperature, and it is impossible to accurately and quickly start the corresponding cooling mode, which affects the operating efficiency and life of the battery module. In addition, when the compressor cooling works for a long time, the overall power consumption of the vehicle will be too large and the energy loss will be too high. Summary of the invention

[0004] The present invention provides a battery thermal management system, which can realize precise control of the natural cooling mode and the refrigeration cycle mode according to the current ambient temperature signal and the current state signal of the battery module, ensure that the temperature of the battery module is always within a safe preset temperature range, reduce the operating time of the refrigeration cycle mode, reduce the energy consumption of the whole vehicle, improve the operating efficiency of the battery module, and extend the life of the battery module.

[0005] The present invention provides a battery thermal management system, including a natural cooling mode, a refrigeration cycle mode, a battery module and a control module;

[0006] The natural cooling mode is connected to the battery module through a natural cooling circuit to cool the battery module;

[0007] The refrigeration cycle mode is connected to the battery module through a refrigeration cycle loop to cool the battery module;

[0008] The battery module includes a battery management system, and the control module is electrically connected to the battery management system. The control module is used to obtain the current ambient temperature signal and the current status signal of the battery module collected by the battery management system, and control the natural cooling mode and / or the refrigeration cycle mode to be turned on or off according to the current ambient temperature signal and the current status signal of the battery module.

[0009] Optionally, the control module is further used to control the natural cooling mode to be turned on and the refrigeration cycle mode to be turned off when the current ambient temperature signal meets the first ambient temperature range;

[0010] When the current ambient temperature signal meets the second ambient temperature range, the refrigeration cycle mode is controlled to be turned on and the natural cooling mode is turned off;

[0011] When the current ambient temperature signal meets the third ambient temperature range, the current state signal of the battery module is obtained, and the refrigeration cycle mode and / or the natural cooling mode are controlled to be turned on or off according to the current state signal of the battery module.

[0012] Optionally, the battery module includes a plurality of battery cells, and the current state signal of the battery module includes a real-time charge and discharge current signal of the battery module, a water inlet temperature signal, and a maximum temperature signal of the battery cell;

[0013] When the current ambient temperature signal meets the third ambient temperature range, the control module is further used to calculate the current ambient temperature signal and the water inlet temperature signal based on the first calculation formula: ΔT FC =T coolant -T amb , determine the heat transfer temperature difference between the inlet water temperature signal and the current ambient temperature signal in the natural cooling mode;

[0014] According to the real-time charge and discharge current signal, the rated maximum charge and discharge current value of the battery module and the maximum heat dissipation of the battery module, based on the second calculation formula: Determine the maximum heat transfer temperature difference required to dissipate heat in real time from the battery module;

[0015] When the heat transfer temperature difference is greater than or equal to the maximum heat transfer temperature difference, the natural cooling mode is controlled to be turned on and the refrigeration cycle mode is turned off;

[0016] When the heat transfer temperature difference is less than the maximum heat transfer temperature difference, the refrigeration cycle mode and / or the natural cooling mode are controlled to be turned on or off according to the maximum temperature signal of the battery cell;

[0017] Among them, T coolant is the inlet water temperature signal, T amb is the current ambient temperature signal, ΔT FC is the heat transfer temperature difference, Q K0 For battery modules in I 1C Maximum heat dissipation during charge and discharge current, I xc is the real-time charge and discharge current signal, I 1C is the rated maximum charge and discharge current value of the battery module, k is a constant, ΔT FC_max The maximum heat transfer temperature difference required for real-time heat dissipation of the battery module.

[0018] Optionally, when the heat transfer temperature difference is less than the maximum heat transfer temperature difference, the control module is further used to control the natural cooling mode to be turned on and the refrigeration cycle mode to be turned off when the highest temperature signal of the battery cell meets the first battery cell temperature range;

[0019] When the highest temperature signal of the battery cell meets the second battery cell temperature range, both the natural cooling mode and the refrigeration cycle mode are controlled to be turned on, or the refrigeration cycle mode is controlled to be turned on and the natural cooling mode is turned off;

[0020] When the highest temperature signal of the battery cell meets the third battery cell temperature range, the refrigeration cycle mode is controlled to be turned on and the natural cooling mode is turned off.

[0021] Optionally, the natural cooling circuit includes a heat dissipation coil and a circulation pump;

[0022] The heat dissipation coil is connected to the circulation pump and is located at both ends of the battery module.

[0023] Optionally, the natural cooling circuit further includes a water circuit proportional regulating valve;

[0024] The water circuit proportional regulating valve is connected in series between the heat dissipation coil and the battery module.

[0025] Optionally, the refrigeration cycle includes a compressor, a plate heat exchanger, a condenser, a thermal expansion valve and a circulation pump;

[0026] One end of the circulation pump is connected to the output end of the battery module, the other end of the circulation pump is connected to the first input end of the plate heat exchanger, the first output end of the plate heat exchanger is connected to one end of the compressor, the other end of the compressor is connected to one end of the condenser, the other end of the condenser is connected to one end of the thermal expansion valve, the other end of the thermal expansion valve is connected to the second input end of the plate heat exchanger, and the second output end of the plate heat exchanger is connected to the input end of the battery module.

[0027] Optionally, the refrigeration cycle further includes a PTC heater;

[0028] One end of the PTC heater is communicated with the other end of the circulation pump, and the other end of the PTC heater is communicated with the first input end of the plate heat exchanger.

[0029] Optionally, the refrigeration cycle further includes a condensing fan;

[0030] The condensing fan and condenser are arranged at preset intervals.

[0031] Optionally, the refrigeration cycle further comprises a shell;

[0032] The condensing fan, the condenser and the heat dissipation coil are arranged in sequence in the casing at preset intervals.

[0033] The technical solution of the present invention collects the current status signal of the battery module through the battery management system, and sends the current status signal of the battery module to the control module. After the control module obtains the current status signal of the battery module, it controls the natural cooling mode and / or the refrigeration cycle mode to be turned on or off in combination with the current ambient temperature signal obtained. Utilizing the above structure, the natural cooling mode and the refrigeration cycle mode are accurately controlled dynamically according to the current ambient temperature signal and the current status signal of the battery module, ensuring that the temperature of the battery module is always within a safe preset temperature range, reducing the operating time of the refrigeration cycle mode, reducing the energy consumption of the entire vehicle, improving the operating efficiency of the battery module, and extending the life of the battery module.

[0034] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 A schematic diagram of the structure of a battery thermal management system provided by an embodiment of the present invention;

[0037] Figure 2 A flow chart of the operation logic of a control module provided by an embodiment of the present invention;

[0038] Figure 3 A schematic diagram of the principle structure of a battery thermal management system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0039] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings 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 should fall within the scope of protection of the present invention.

[0040] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0041] In one embodiment, Figure 1 This is a schematic diagram of a battery thermal management system provided by an embodiment of the present invention. This embodiment is applicable to the case where the battery module temperature in a car is within a dynamic safety temperature range. Figure 1 As shown, the battery thermal management system includes a natural cooling mode 1, a refrigeration cycle mode 2, a battery module 3 and a control module 4; the natural cooling mode 1 is connected to the battery module 3 through a natural cooling loop, and is used to cool the battery module 3; the refrigeration cycle mode 2 is connected to the battery module 3 through a refrigeration cycle loop, and is used to cool the battery module 3; the battery module 3 includes a battery management system 31, and the control module 4 is electrically connected to the battery management system 31, and the control module 4 is used to obtain the current ambient temperature signal and the current state signal of the battery module 3 collected by the battery management system 31, and control the natural cooling mode 1 and / or the refrigeration cycle mode 2 to be turned on or off according to the current ambient temperature signal and the current state signal of the battery module 3.

[0042] Among them, natural cooling mode 1 is to utilize the temperature difference between the external environment and the battery module 3, and dissipate the heat of the battery module 3 into the atmosphere through the naturally cooled scattering coil to realize the pipeline structure of cooling the battery module 3. Refrigeration cycle mode 2 is a pipeline structure for cooling the temperature of the battery module 3 by means of compressor refrigeration. The battery module 3 (Battery Module) is a unit assembled from multiple battery cells, which is used to provide higher voltage and capacity. The battery module 3 usually includes a battery management system 31, and the battery management system 31 (Battery Management System, BMS) is responsible for monitoring and managing the charging and discharging process of the battery module 3 to ensure the safety and stability of the battery module 3. The battery management system 31 can monitor the voltage, temperature and current parameters of the battery module 3, perform state estimation and balance control of the battery module 3 to avoid overcharging, over-discharging, over-temperature and other situations, and provide a communication interface to interact with the external system for data, extend the service life of the battery module 3, and ensure that the battery module 3 operates under safe and stable conditions. The control module 4 is the main control module of the battery thermal management system, and is used to control the natural cooling mode 1 and / or the refrigeration cycle mode 2 to be turned on or off according to the current ambient temperature signal and the current state signal of the battery module 3 collected by the battery management system 31. The method of obtaining the current ambient temperature signal may include but is not limited to obtaining it through a sensor or a thermometer, etc., and is not specifically limited here.

[0043] Specifically, by electrically connecting the control module 4 and the battery management system 31, the battery management system 31 can collect the current state signal of the battery module 3 in real time, wherein the current state signal of the battery module 3 may include but is not limited to the real-time charge and discharge current signal of the battery module 3, the water outlet temperature signal of the coolant entering the battery module 3, and the maximum temperature signal of the battery cell in the battery module 3. The control module 4 obtains the current state signal of the battery module 3 collected by the battery management system 31, and the current ambient temperature signal obtained, and controls the natural cooling mode 1 and / or the refrigeration cycle mode 2 to be turned on or off according to the current ambient temperature signal and the current state signal of the battery module 3. When the natural cooling mode 1 is turned on and the refrigeration cycle mode 2 is turned off, it indicates that the battery module 3 can be cooled down by the natural cooling mode 1 alone. At this time, the heat dissipation capacity of the natural cooling circuit can be used to cool the battery module 3, so that the heat of the battery module 3 is dissipated to the atmosphere, that is, the temperature of the battery module 3 is within the preset temperature range, wherein the preset temperature range can be 20°C-25°C. When natural cooling mode 1 is turned off and refrigeration cycle mode 2 is turned on, it indicates that the heat dissipation capacity of natural cooling mode 1 is insufficient to meet the heat demand of battery module 3, and the battery module 3 needs to be cooled by compressor refrigeration. At this time, the battery module 3 can be cooled by the heat dissipation capacity of the refrigeration cycle loop, so that the temperature of the battery module 3 is within the preset temperature range. When both natural cooling mode 1 and refrigeration cycle mode 2 are turned on, it indicates that the heat of the battery module 3 cannot be completely dissipated by natural cooling mode 1 alone, and the heat of the battery module 3 needs to be dissipated by running refrigeration cycle mode 2 to cool the battery module 3. At this time, the battery module 3 can be cooled by the natural cooling loop and the refrigeration cycle loop. Among them, when both the natural cooling mode 1 and the refrigeration cycle mode 2 are turned on, the natural cooling loop 1 can be turned on first according to the actual situation, such as the operating power problem, and the heat of the battery module 3 is dissipated into the atmosphere through the temperature difference between the temperature of the battery module 3 and the current ambient temperature, so that the temperature of the battery module 3 is partially reduced. Secondly, the refrigeration cycle mode 2 is turned on to dissipate the remaining heat of the battery module 3 into the atmosphere through the refrigeration cycle loop, thereby achieving cooling of the battery module 3.

[0044] The technical solution of the embodiment of the present invention collects the current status signal of the battery module through the battery management system, and sends the current status signal of the battery module to the control module. After the control module obtains the current status signal of the battery module, it controls the natural cooling mode and / or the refrigeration cycle mode to be turned on or off in combination with the current ambient temperature signal obtained. Utilizing the above structure, accurate control of the natural cooling mode and the refrigeration cycle mode is achieved according to the current ambient temperature signal and the current status signal of the battery module, ensuring that the temperature of the battery module is always within a safe preset temperature range, reducing the operating time of the refrigeration cycle mode, reducing the energy consumption of the entire vehicle, improving the operating efficiency of the battery module, and extending the life of the battery module.

[0045] Optional, Figure 2 A flowchart of the operation logic of a control module provided by an embodiment of the present invention, Figure 3 A schematic diagram of the principle structure of a battery thermal management system provided by an embodiment of the present invention, referring to Figure 2 and Figure 3 As shown, the control module 4 is also used to control the natural cooling mode 1 to be turned on and the refrigeration cycle mode 2 to be turned off when the current ambient temperature signal meets the first ambient temperature range; to control the refrigeration cycle mode 2 to be turned on and the natural cooling mode 1 to be turned off when the current ambient temperature signal meets the second ambient temperature range; and to obtain the current status signal of the battery module 3 when the current ambient temperature signal meets the third ambient temperature range, and control the refrigeration cycle mode 2 and / or the natural cooling mode 1 to be turned on or off according to the current status signal of the battery module 3.

[0046] Specifically, after the control module 4 obtains the current ambient temperature signal, it will judge the current ambient temperature signal. When it is determined that the current ambient temperature signal obtained satisfies the first ambient temperature range, in this embodiment, the first ambient temperature range can be T≤-15°C, which can be determined according to actual conditions and is not limited here. When it is determined that the current ambient temperature signal satisfies the first ambient temperature range, it indicates that the external ambient temperature is very low at this time. Under normal circumstances, the temperature difference between the external ambient temperature and the temperature of the battery module 3 is large. The heat dissipation capacity of the natural cooling mode 1 can fully meet the heat dissipation demand of the battery module 3, that is, the refrigeration cycle mode 2 can be ignored. Only the natural cooling mode 1 can reduce the temperature of the battery module 3 to within the preset temperature range. Therefore, the control module 4 will control the natural cooling mode 1 to be turned on, and control the refrigeration cycle mode 2 to be turned off, so that the heat of the battery module 3 is only dissipated through the natural cooling circuit until the temperature of the battery module 3 reaches the preset temperature range.

[0047] When the control module 4 determines that the acquired current ambient temperature signal meets the second ambient temperature range, in this embodiment, the second ambient temperature range can be T>12℃, which can be determined according to the actual situation and is not limited here. When it is determined that the current ambient temperature signal meets the second ambient temperature range, it indicates that the external ambient temperature is relatively high at this time, and the heat dissipation capacity of the natural cooling mode 1 cannot meet the heat dissipation demand of the battery module 3, and the temperature of the battery module 3 cannot be reduced to the preset temperature range, that is, the natural cooling mode 1 can be ignored, and the temperature of the battery module 3 can be quickly reduced to the preset temperature range only through the refrigeration cycle mode 2. Therefore, the control module 4 will control the natural cooling mode 1 to be turned off, and control the refrigeration cycle mode 2 to be turned on, so that the heat of the battery module 3 is only dissipated through the refrigeration cycle loop until the temperature of the battery module 3 reaches the preset temperature range.

[0048] When the control module 4 determines that the current ambient temperature signal obtained satisfies the third ambient temperature range, in this embodiment, the third ambient temperature range may be -15°C<T≤12°C, which may be determined specifically according to actual conditions and is not limited here. When it is determined that the current ambient temperature signal satisfies the third ambient temperature range, in most cases the temperature difference with the battery module 3 is small, and it is difficult to determine whether to use natural cooling mode 1 and / or refrigeration cycle mode 2 for cooling only by the external ambient temperature signal. At this time, the control module 4 needs to obtain the current state signal of the battery module 3, and control the refrigeration cycle mode 2 and / or natural cooling mode 1 to turn on or off according to the current state signal of the battery module 3. This embodiment realizes the rough selection of different cooling modes through the temperature range of the external ambient temperature signal, simplifies the control logic, and improves the operating efficiency of the battery thermal management system.

[0049] Optional, continue to refer to Figure 2 and Figure 3 As shown, the battery module 3 includes a plurality of battery cells 32, and the current state signal of the battery module 3 includes a real-time charge and discharge current signal, a water inlet temperature signal, and a maximum temperature signal of the battery cell 32; when the current ambient temperature signal meets the third ambient temperature range, the control module 4 is further used to calculate the current ambient temperature signal and the water inlet temperature signal based on the first calculation formula: ΔT FC =T coolant -T amb , determine the heat transfer temperature difference between the water inlet temperature signal and the current ambient temperature signal in natural cooling mode 1; according to the real-time charge and discharge current signal, the rated maximum charge and discharge current value of the battery module 3 and the maximum heat dissipation of the battery module 3, based on the second calculation formula: Determine the maximum heat transfer temperature difference required for the real-time heat dissipation of the battery module 3; when the heat transfer temperature difference is greater than or equal to the maximum heat transfer temperature difference, control the natural cooling mode 1 to be turned on and the refrigeration cycle mode 2 to be turned off; when the heat transfer temperature difference is less than the maximum heat transfer temperature difference, control the refrigeration cycle mode 2 and / or the natural cooling mode 1 to be turned on or off according to the maximum temperature signal of the battery cell 32; wherein, T coolant is the inlet water temperature signal, T amb is the current ambient temperature signal, ΔT FC is the heat transfer temperature difference, Q K0 For battery module 3 in I 1C Maximum heat dissipation during charge and discharge current, I xc is the real-time charge and discharge current signal, I 1C is the rated maximum charge and discharge current value of battery module 3, k is a constant, ΔT FC_max It is the maximum heat transfer temperature difference required for the real-time heat dissipation of the battery module 3.

[0050] Among them, the battery cell 32 (Battery Cell) is the basic unit constituting the battery module 3, and it is the smallest energy storage unit in the battery module 3. The battery cell 32 can be a single battery cell, or it can be a part of the battery module 3 formed by a plurality of battery cells connected in series or in parallel. Normally, when the battery module 3 is prepared, the total resistance of all equivalent circuits such as the series-parallel layout of the battery cells 32, the positive and negative ears of each battery cell 32, and the wiring row of each battery cell 32 welded into a group is a certain value. The water inlet temperature signal is the coolant circulating in the battery module 3, that is, the temperature value of the ethylene glycol solution flowing into the battery module 3 after passing through the natural cooling mode 1 or the refrigeration cycle mode 2. Normally, the water inlet temperature signal can be 15°C or 20°C, which can be determined according to the actual situation and is not limited here. The heat transfer temperature difference is the coolant outlet temperature, that is, the difference between the water inlet temperature of the battery module 3 and the ambient temperature. Combined with the working principle of the natural cooling mode 1, the heat transfer temperature difference is usually greater than 0, and the natural cooling mode 1 can dissipate the heat of the battery module 3 into the atmosphere to achieve the cooling of the battery module 3. 1C The maximum heat dissipation during charge and discharge current indicates the maximum heat dissipation of the battery module 3 at 1C, i.e., 100% charging current, that is, the heat dissipation requirement of the battery module 3, which can be expressed in kW. For example, for a 280kW / h commercial vehicle battery module, the heat dissipation requirement to ensure stable temperature control and thermal balance of the battery module 3 under harsh working conditions is 10kW. At this time, Q K0=10kW. The rated maximum charge and discharge current value of the battery module 3 is the maximum charge and discharge current value of the battery module 3 at 1C, i.e., 100% charging current, or 1P, i.e., 100% discharging current. For example, for a 280kW / h commercial vehicle battery module, the charging current at 1C is 400A, then I 1C =400A, the current at any time is equal to this current value.

[0051] Specifically, when the control module 4 determines that the current ambient temperature signal is within the third ambient temperature range, the control module 4 acquires the real-time charge and discharge current signal of the battery module 3, the water inlet temperature signal entering the battery module 3, and the maximum temperature signal of the battery cell collected by the battery management system 31, and calculates ΔT based on the first calculation formula according to the acquired current ambient temperature signal and water inlet temperature signal. FC =T coolant -T amb , subtract the inlet water temperature signal from the current ambient temperature signal to obtain the inlet water temperature signal T in natural cooling mode 1 coolant and the current ambient temperature signal T amb The heat transfer temperature difference ΔT FC . Determine the heat transfer temperature difference ΔT FC After that, it is also necessary to determine the maximum heat transfer temperature difference ΔT required for the real-time heat dissipation of the battery module 3 FC_max That is to say, the control module 4 will obtain the real-time charge and discharge current signal I of the battery module 3 xc , Rated maximum charge and discharge current value I 1C and maximum heat dissipation Q K0 , according to the second calculation formula: Q K0 ,I xc and I 1C Once determined, the maximum heat transfer temperature difference ΔT can be calculated FC_max . Calculate the maximum heat transfer temperature difference ΔT FC_max After that, the heat transfer temperature difference ΔT FC and the maximum heat transfer temperature difference ΔT FC_max By comparison, the heat transfer temperature difference ΔT is determined. FC Greater than or equal to the maximum heat transfer temperature difference ΔT FC_max When , it indicates that the heat dissipation of natural cooling mode 1 is greater than or equal to the heat dissipation of battery module 3, the external environment temperature is low, and the heat dissipation capacity of natural cooling mode 1 can fully meet the heat dissipation requirements of battery module 3. Therefore, the control module can only control natural cooling mode 1 to be turned on, and control refrigeration cycle mode 2 to be turned off, and use the natural cooling loop of natural cooling mode 1 to cool down battery module 3 to ensure that battery module 3 is always within the preset temperature range. The control module 4 determines the heat transfer temperature difference ΔT FCLess than the maximum heat transfer temperature difference ΔT FC_max , it indicates that the heat dissipation of natural cooling mode 1 is less than the heat dissipation of battery module 3, that is, the heat dissipation capacity of natural cooling mode 1 may not meet the heat dissipation requirement of battery module 3. At this time, it is necessary to obtain the temperature of battery cell 32 in battery module 3. In this embodiment, the maximum temperature signal of battery cell 32 can be obtained, and the refrigeration cycle mode 2 and / or natural cooling mode 1 can be controlled to be turned on or off according to the obtained maximum temperature signal of battery cell 32.

[0052] It should be noted that the calculated heat transfer temperature difference ΔT FC is the heat transfer temperature difference in natural cooling mode 1. This is because in practical applications, the heat dissipation in natural cooling mode 1 is proportional to the heat transfer temperature difference ΔT FC The relationship between is a linear relationship, and the amount of heat dissipation is only related to the heat transfer temperature difference ΔT FC Related, that is, to determine the heat transfer temperature difference ΔT FC After that, the heat transfer temperature difference ΔT FC Multiply by the slope coefficient, which is the same as the constant k, i.e. Q o_FC =k×ΔT FC , we can get the heat dissipation Q of natural cooling mode 1 o_FC , and since the coefficient k can be determined according to the actual situation, it is usually only necessary to determine the heat transfer temperature difference ΔT FC , the heat dissipation capacity of the natural cooling mode 1 can be determined, and accurate temperature control of the natural cooling mode 1 can be achieved. For example, k is 0.333 kW / °C, which can be determined according to actual conditions and is not specifically limited here.

[0053] It should also be noted that the cooling capacity design of the battery thermal management system is generally based on the worst ambient temperature conditions, that is, 1C (100% charging current) or 1P (100% discharging current), while ensuring that the temperature rise of the battery module 3 does not exceed the safety limit. According to the above embodiment, after the battery module 3 is prepared, the total resistance of all equivalent circuits of the battery module 3 is a certain value, and the heat dissipation of the battery module 3 during the charging and discharging process is directly related to the charging and discharging current of the battery module 3. According to Q=I 2 R, the resistance is constant, and the resistance change of the battery module 3 with temperature during the charge and discharge process can be ignored. The charge and discharge current of the battery module 3 determines the heat dissipation of the battery module 3. Therefore, this embodiment determines to collect the charge and discharge current of the battery module 3 in real time according to the above principle, and the heat dissipation can be determined according to the charge and discharge current.

[0054] Optional, continue to refer to Figure 2 and Figure 3When the heat transfer temperature difference is less than the maximum heat transfer temperature difference, the control module 4 is also used to control the natural cooling mode 1 to be turned on and the refrigeration cycle mode 2 to be turned off when the maximum temperature signal of the battery cell 32 meets the first battery cell temperature range; when the maximum temperature signal of the battery cell 32 meets the second battery cell temperature range, control both the natural cooling mode 1 and the refrigeration cycle mode 2 to be turned on, or control the refrigeration cycle mode 2 to be turned on and the natural cooling mode 1 to be turned off; when the maximum temperature signal of the battery cell 32 meets the third battery cell temperature range, control the refrigeration cycle mode 2 to be turned on and the natural cooling mode 1 to be turned off.

[0055] Specifically, in the heat transfer temperature difference ΔT FC Less than the maximum heat transfer temperature difference ΔT FC_max It is necessary to obtain the maximum temperature signal of the battery cell 32 to determine the cooling mode to be used. In the present embodiment, after the control module 4 obtains the maximum temperature signal of the battery cell 32, it determines that the maximum temperature signal of the battery cell 32 satisfies the first battery cell temperature range according to the maximum temperature signal, wherein the first battery cell temperature range may be 20°C<Tbatt-max≤25°C, Tbatt-max is the maximum temperature signal of the battery cell 32, and at this time the maximum temperature of the battery cell 32 is in the normal temperature range. Therefore, in order to ensure energy conservation and emission reduction, the natural cooling mode 1 may be used to cool the battery module 3 so that the battery module 3 is cooled to within the preset temperature range. That is to say, the control module 4 controls the natural cooling mode 1 to be turned on, controls the refrigeration cycle mode 2 to be turned off, and utilizes the heat dissipation capacity of the natural cooling mode 1 to cool the battery module 3.

[0056] When the control module 4 determines that the maximum temperature signal of the battery cell 32 meets the second battery cell temperature range, the second battery cell temperature signal range can be 25℃<Tbatt-max≤43℃, at this time, the temperature of the battery cell 32 is at a relatively high operating temperature, and it is difficult to quickly cool the battery module 3 to the preset temperature range by relying solely on the heat dissipation capacity of the natural cooling mode 1. Therefore, in order to ensure energy conservation and emission reduction, the control module 3 can turn on the natural cooling mode 1 and the refrigeration cycle mode 2, and use the heat dissipation capacity of the natural cooling mode 1 to dissipate part of the heat dissipation of the battery module 3. The remaining heat that cannot be dissipated by the natural cooling mode 1 can be dissipated to the atmosphere through the heat dissipation capacity of the refrigeration cycle mode 2, so that the running time of the refrigeration cycle mode 2 can be reduced, the power of the overall system operation can be reduced, and the operating life of the system can be increased. In addition, according to actual conditions, if it is necessary to quickly reduce the temperature of the battery module 3, the control module 3 can also only control the refrigeration cycle mode 2 to be turned on, and control the natural cooling mode 1 to be turned off, and the heat of the battery module 3 can be quickly dissipated to the atmosphere through the heat dissipation capacity of the refrigeration cycle mode 2.

[0057] When the control module 3 determines that the maximum temperature signal of the battery cell 32 is within the third battery cell temperature range, wherein the third battery cell temperature range may be Tbatt-max>43°C, at this time the temperature of the battery cell 32 is too high, and being in a high temperature state for a long time will affect the performance and life of the battery cell 32, so it is necessary to quickly reduce the temperature of the battery module 3, that is, the control module 3 will immediately control the refrigeration cycle mode 2 to turn on, and the natural cooling mode 1 to turn off, and realize the rapid cooling of the battery module 3 through the heat dissipation capacity of the refrigeration cycle mode 2, so that the battery module 3 is within the preset temperature range, thereby ensuring the performance and life of the battery module 3.

[0058] Optional, continue to refer to Figure 3 As shown, the natural cooling circuit includes a heat dissipation coil 11 and a circulation pump 10 ; the heat dissipation coil 11 and the circulation pump 10 are connected and are located at both ends of the battery module 3 .

[0059] Optionally, the natural cooling circuit further includes a water circuit proportional regulating valve 13 ; the water circuit proportional regulating valve 13 is connected in series between the heat dissipation coil 11 and the battery module 3 .

[0060] The circulating pump 10 is used to pressurize the coolant, i.e., the ethylene glycol solution, flowing through the battery module 3 so that the ethylene glycol solution flows into the heat dissipation coil 11; the heat dissipation coil 11 is used to cool the ethylene glycol solution so that the cooled ethylene glycol solution flows into the battery module 3 and absorbs the heat of the battery module 3 to cool the battery module 3. The water circuit proportional control valve 13, also known as a two-way valve, is an industrial automatic control device that adjusts the valve opening according to the difference between the input control signal and the feedback signal to achieve the desired flow regulation effect.

[0061] Specifically, the power supply of the natural cooling mode 1 is provided by the circulating pump 10. When the temperature of the battery module 3 is high, the ethylene glycol solution circulating in the battery module 3 absorbs the heat of the battery module 3 and then increases in temperature, and flows out of the battery module 3 and enters the suction port of the circulating pump 10. The ethylene glycol solution is pushed to continue to flow under the pressure increase of the circulating pump 10. The ethylene glycol solution at one end of the circulating pump 10 will enter the heat dissipation coil 11 of the natural cooling mode 1. The heat dissipation coil 11 will absorb the heat of the ethylene glycol solution to cool it, so that the temperature of the ethylene glycol solution is reduced. The cooled ethylene glycol solution reaches the target water outlet temperature, that is, the water inlet temperature of the battery module 3, and enters the battery module 3 to cool the battery module 3, thereby realizing a water circuit cycle.

[0062] Optional, continue to refer to Figure 3The refrigeration cycle includes a compressor 21, a plate heat exchanger 22, a condenser 23, a thermal expansion valve 24 and a circulation pump 10; one end of the circulation pump 10 is connected to the output end of the battery module 3, the other end of the circulation pump 10 is connected to the first input end of the plate heat exchanger 22, the first output end of the plate heat exchanger 22 is connected to one end of the compressor 21, the other end of the compressor 21 is connected to one end of the condenser 23, the other end of the condenser 23 is connected to one end of the thermal expansion valve 24, the other end of the thermal expansion valve 24 is connected to the second input end of the plate heat exchanger 22, and the second output end of the plate heat exchanger 22 is connected to the input end of the battery module 3.

[0063] Optional, continue to refer to Figure 3 The refrigeration cycle further includes a PTC heater 25 ; one end of the PTC heater 25 is connected to the other end of the circulation pump 10 , and the other end of the PTC heater 25 is connected to the first input end of the plate heat exchanger 22 .

[0064] Optional, continue to refer to Figure 3 The refrigeration cycle loop also includes a condensing fan 26; the condensing fan 26 and the condenser 23 are arranged at a preset interval.

[0065] Among them, the compressor 21 is used to provide power for the circulation of the refrigerant. The motor drives the compressor 21 to roll the rotor mechanical structure, and compresses the low-temperature and low-pressure refrigerant gas sucked into the suction cavity into a high-temperature and high-pressure superheated gas. The condenser 23 is used to exchange heat between the refrigerant and the ambient air, so that a large amount of heat of the high-temperature and high-pressure refrigerant superheated gas is transferred to the ambient air, and the refrigerant is condensed and liquefied into a high-temperature and high-pressure refrigerant supercooled liquid. The thermal expansion valve 24 is used to reduce the pressure of the high-temperature and high-pressure refrigerant supercooled liquid to a mixture of low-temperature and low-pressure refrigerant liquid and gas. The plate heat exchanger 22 is used to provide heat exchange between the refrigerant liquid and the ethylene glycol solution flowing through the battery module 3, so that the refrigerant liquid absorbs the heat of the ethylene glycol solution and vaporizes into a superheated refrigerant gas. The PTC heater 25 is used to heat the ethylene glycol solution. The circulating pump 10 is used to pressurize the ethylene glycol solution so that the ethylene glycol solution flows into the PTC heater 25. The condensing fan 26 is used to accelerate the air flow on the surface of the condenser 23 so as to transfer the heat of the high-temperature and high-pressure refrigerant superheated gas generated by the compressor 21 to the external environment through the condenser 23 .

[0066] Specifically, by injecting refrigerant into the refrigeration cycle mode 2, the refrigerant will be sucked into the compressor 21, the compressor 21 compresses the low-temperature and low-pressure refrigerant gas into a high-temperature and high-pressure superheated gas, and enters the condenser 23, the condenser 23 transfers a large amount of heat of the high-temperature and high-pressure refrigerant superheated gas to the ambient air, the refrigerant condenses and liquefies into a high-temperature and high-pressure refrigerant supercooled liquid and then flows into the thermal expansion valve 24, the thermal expansion valve 24 reduces the pressure of the high-temperature and high-pressure refrigerant supercooled liquid into a mixture of low-temperature and low-pressure refrigerant liquid and gas and then enters the plate heat exchanger 22, the plate heat exchanger 22 absorbs the heat of the ethylene glycol solution through the refrigerant liquid, and vaporizes it into superheated refrigerant gas. During this process, the refrigerant liquid undergoes phase change heat transfer, the latent heat of vaporization is very large, and the heat transfer efficiency is high. The temperature of the ethylene glycol solution that absorbs heat is reduced, and a water supply with an inlet temperature of about 15°C or 18°C ​​is provided to the battery module 3, and the heat of the battery module 3 is absorbed. After the ethylene glycol solution absorbs the heat of the battery module 3, the temperature rises and returns to the plate heat exchanger 22 of the refrigeration cycle mode 2, and the temperature drops again, thus completing the water circuit circulation; and the low-temperature and low-pressure superheated refrigerant gas at the outlet of the plate heat exchanger 22 returns to the suction port of the compressor 21 again, completing the refrigeration cycle of the battery module 3.

[0067] It can be understood that when the refrigeration cycle mode 2 is turned off and the natural cooling mode 1 is turned on, the refrigeration cycle mode 2 only does not cool the ethylene glycol solution so that the ethylene glycol solution does not exchange heat, but it does not mean that the refrigeration cycle mode 2 is disconnected and the ethylene glycol solution does not pass through the refrigeration cycle mode 2. In other words, the ethylene glycol solution that finally flows into the battery module 3 is a mixed solution of the ethylene glycol solutions of the refrigeration cycle mode 2 and the natural cooling mode 1.

[0068] In addition, the actual principle of the control module 4 controlling the opening or closing of the refrigeration cycle mode 2 and the natural cooling mode 1 is briefly described here. When the refrigeration cycle mode 2 is turned on and the natural cooling mode 1 is turned off, the control module 4 controls the water circuit proportional regulating valve 13 to be turned off, the passage of the heat dissipation coil 11 is cut off, and all the ethylene glycol solution enters the PTC heater 25 and the plate heat exchanger 22. The ethylene glycol solution with a lowered temperature after being cooled by the plate heat exchanger 22 is returned to the battery module 3 to cool the battery module 3 again, completing a water circuit cycle.

[0069] In the combined cooling mode in which both the refrigeration cycle mode 2 and the natural cooling mode 1 are turned on, the water circuit proportional regulating valve 13 of the control module 4 is turned on, and the ethylene glycol solution pressurized by the circulation pump 10 is evenly diverted to two paths. The ethylene glycol solution cooled after passing through the plate heat exchanger 22 and the ethylene glycol solution with a lowered temperature after passing through the heat dissipation coil 11, these two fluids merge together to meet the target cold water outlet temperature, enter the battery module 3 to cool the battery module 3 again, and complete a water circuit cycle.

[0070] When the natural cooling mode 1 is turned on and the refrigeration cycle module 2 is turned off, the water circuit proportional regulating valve 13 of the control module 4 is turned on, and the ethylene glycol solution pressurized by the circulation pump 10 is evenly diverted to two paths, and the compressor refrigeration cycle mode 2 is turned off. Therefore, there is no heat exchange in this path of ethylene glycol solution after passing through the plate heat exchanger 22, and the ethylene glycol solution whose temperature is lowered after being cooled by the heat dissipation coil 11, the two fluids merge together to meet the target cold water outlet temperature, enter the battery module 3 to cool the battery module 3 again, and complete a water circuit cycle.

[0071] Optionally, the refrigeration cycle further includes a shell (not shown in the figure); the condensing fan 26, the condenser 23 and the heat dissipation coil 11 are arranged in sequence in the shell at preset intervals.

[0072] Specifically, in order to ensure that the wind blown by the condensing fan 26 quickly dissipates the heat of the refrigerant gas of the condenser 23 and the ethylene glycol solution circulating in the natural cooling mode 1 into the atmosphere, a housing is provided in the present embodiment, and the condensing fan 26, the condenser 23 and the heat dissipation coil 11 are all arranged in the housing and arranged in sequence at preset intervals, so that the wind of the condensing fan 26 is not lost to the greatest extent, and is used to dissipate heat, thereby improving the cooling efficiency of the battery module 3. Exemplarily, the preset interval may be 50 mm.

[0073] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0074] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A battery thermal management system, characterized in that: Including natural cooling mode, refrigeration cycle mode, battery module and control module; The natural cooling mode is connected to the battery module via a natural cooling circuit, and is used to cool the battery module; The refrigeration cycle mode is connected to the battery module via a refrigeration cycle loop, and is used to cool the battery module; The battery module includes a battery management system, and the control module is electrically connected to the battery management system. The control module is used to obtain a current ambient temperature signal and a current status signal of the battery module collected by the battery management system, and control the natural cooling mode and / or the refrigeration cycle mode to be turned on or off according to the current ambient temperature signal and the current status signal of the battery module.

2. The system according to claim 1, characterized in that The control module is also used to control the natural cooling mode to be turned on and the refrigeration cycle mode to be turned off when the current ambient temperature signal meets the first ambient temperature range; When the current ambient temperature signal meets the second ambient temperature range, controlling the refrigeration cycle mode to be turned on and the natural cooling mode to be turned off; When the current ambient temperature signal meets the third ambient temperature range, the current state signal of the battery module is acquired, and the refrigeration cycle mode and / or the natural cooling mode are controlled to be turned on or off according to the current state signal of the battery module.

3. The system according to claim 2, characterized in that The battery module comprises a plurality of battery cells, and the current state signal of the battery module comprises a real-time charge and discharge current signal of the battery module, a water inlet temperature signal and a maximum temperature signal of the battery cell; When the current ambient temperature signal meets the third ambient temperature range, the control module is further configured to calculate based on the current ambient temperature signal and the inlet water temperature signal a first calculation formula: ΔT FC =T coolant -T amb , determining a heat transfer temperature difference between the water inlet temperature signal and the current ambient temperature signal in the natural cooling mode; According to the real-time charge and discharge current signal, the rated maximum charge and discharge current value of the battery module and the maximum heat dissipation of the battery module, based on the second calculation formula: Determine the maximum heat transfer temperature difference required for the real-time heat dissipation of the battery module; When the heat transfer temperature difference is greater than or equal to the maximum heat transfer temperature difference, controlling the natural cooling mode to be turned on and the refrigeration cycle mode to be turned off; When the heat transfer temperature difference is less than the maximum heat transfer temperature difference, controlling the refrigeration cycle mode and / or the natural cooling mode to be turned on or off according to the maximum temperature signal of the battery core; Among them, T coolant is the inlet water temperature signal, T amb is the current ambient temperature signal, ΔT F is the heat transfer temperature difference, Q K0 The battery module is in I 1C Maximum heat dissipation during charge and discharge current, I xc is the real-time charge and discharge current signal, I 1C is the rated maximum charge and discharge current value of the battery module, k is a constant, ΔT FCmax The maximum heat transfer temperature difference required for the real-time heat dissipation of the battery module.

4. The system according to claim 3, characterized in that When the heat transfer temperature difference is less than the maximum heat transfer temperature difference, the control module is further used to control the natural cooling mode to be turned on and the refrigeration cycle mode to be turned off when the maximum temperature signal of the battery cell meets the first battery cell temperature range; When the maximum temperature signal of the battery cell meets the second battery cell temperature range, controlling both the natural cooling mode and the refrigeration cycle mode to be turned on, or controlling the refrigeration cycle mode to be turned on and the natural cooling mode to be turned off; When the highest temperature signal of the battery cell meets the third battery cell temperature range, the refrigeration cycle mode is controlled to be turned on and the natural cooling mode is controlled to be turned off.

5. The system according to claim 1, characterized in that The natural cooling circuit includes a heat dissipation coil and a circulation pump; The heat dissipation coil is communicated with the circulation pump and is located at two ends of the battery module.

6. The system according to claim 5, characterized in that The natural cooling circuit also includes a water circuit proportional regulating valve; The water circuit proportional regulating valve is connected in series between the heat dissipation coil and the battery module.

7. The system according to claim 1, characterized in that The refrigeration cycle includes a compressor, a plate heat exchanger, a condenser, a thermal expansion valve and a circulation pump; One end of the circulation pump is connected to the output end of the battery module, the other end of the circulation pump is connected to the first input end of the plate heat exchanger, the first output end of the plate heat exchanger is connected to one end of the compressor, the other end of the compressor is connected to one end of the condenser, the other end of the condenser is connected to one end of the thermal expansion valve, the other end of the thermal expansion valve is connected to the second input end of the plate heat exchanger, and the second output end of the plate heat exchanger is connected to the input end of the battery module.

8. The system according to claim 7, characterized in that The refrigeration cycle also includes a PTC heater; One end of the PTC heater is communicated with the other end of the circulation pump, and the other end of the PTC heater is communicated with the first input end of the plate heat exchanger.

9. The system according to claim 7, characterized in that The refrigeration cycle also includes a condensing fan; The condensing fan and the condenser are arranged at a preset interval.

10. The system according to claim 9, characterized in that The refrigeration cycle also includes a housing; The condensing fan, the condenser and the heat dissipation coil are arranged in sequence in the housing at preset intervals.

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