A battery thermal management system, control method and vehicle

Abstract

The present invention provides a battery thermal management system, a control method and a vehicle, wherein the battery thermal management system includes a battery refrigerant circuit, an air conditioning refrigerant circuit and a coolant circuit; the battery refrigerant circuit is used to cool or heat the battery; a first heat exchanger is provided between the battery refrigerant circuit and the air conditioning refrigerant circuit; the first heat exchanger is used for heat exchange between the battery refrigerant circuit and the air conditioning refrigerant circuit; a second heat exchanger is provided between the battery refrigerant circuit and the coolant circuit, and the second heat exchanger is used for heat exchange between the battery refrigerant circuit and the coolant circuit. The present invention uses an independent battery refrigerant circuit, whose temperature and flow are independently adjusted, to avoid the temperature uniformity and temperature fluctuation problems of the existing battery direct cooling system, and can exchange heat with the coolant circuit, using waste heat to heat the battery, effectively reducing the energy consumption of low-temperature vehicle driving.

Description

Technical Field

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

[0002] At present, with the increasingly serious global environmental problems, electric vehicles as new energy vehicles have developed rapidly.

[0003] Electric vehicles use power batteries as their energy source, and power batteries generally have better performance within the temperature range of 15℃ ~ 35℃. Too low temperature will cause their capacity to decay rapidly, and even lithium deposition at the negative electrode will occur, causing safety hazards; and too high battery temperature will easily cause overheating or even thermal runaway.

[0004] The existing method of using a direct cooling system to control the temperature of the battery is that the refrigerant of the vehicle's air-conditioning system directly enters the battery. Although it has the characteristic of fast battery cooling rate, it also has the problem of difficult control of temperature uniformity, and requires the addition of a battery heating film for oscillating heating, which has a high control cost. Summary of the invention

[0005] In view of this, the present invention aims to propose a battery thermal management system, a control method and a vehicle to solve the problems of poor temperature uniformity and high cost in the existing power battery temperature control method of electric vehicles.

[0006] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0007] A battery thermal management system, comprising a battery refrigerant circuit, an air conditioning refrigerant circuit and a coolant circuit; the battery refrigerant circuit is used to cool or heat the battery;

[0008] A first heat exchanger is provided between the battery refrigerant circuit and the air-conditioning refrigerant circuit; the first heat exchanger is used for heat exchange between the battery refrigerant circuit and the air-conditioning refrigerant circuit;

[0009] A second heat exchanger is provided between the battery refrigerant circuit and the coolant circuit, and the second heat exchanger is used for heat exchange between the battery refrigerant circuit and the coolant circuit.

[0010] Furthermore, in the battery thermal management system, the battery refrigerant circuit includes a first compressor, the first compressor, the first heat exchanger, the second heat exchanger and the battery pipeline are connected to form a loop, and both ends of the first compressor are connected to the first heat exchanger and the battery pipeline through a first four-way valve.

[0011] Furthermore, in the battery thermal management system, the air-conditioning refrigerant circuit includes a second compressor, a third heat exchanger and a fourth heat exchanger connected by pipes to form a circuit, the third heat exchanger is used for heat exchange with outdoor air, the fourth heat exchanger is used for heat exchange with indoor air, the first heat exchanger and the fourth heat exchanger are arranged in parallel, and both ends of the second compressor are connected to the fourth heat exchanger and the third heat exchanger pipelines through a second four-way valve.

[0012] Furthermore, in the battery thermal management system, the coolant circuit includes a heat source and a fifth heat exchanger, the two ends of the heat source are connected to the two end pipes of the fifth heat exchanger through a first three-way valve and a second three-way valve respectively, the second heat exchanger is connected between the first three-way valve and the second three-way valve through a pipe, and the heat source and the fifth heat exchanger are also connected through a pipe provided with a water pump.

[0013] Furthermore, in the battery thermal management system, the heat source includes an electric heater.

[0014] Furthermore, in the battery thermal management system, a first expansion valve is provided between the fourth heat exchanger and the third heat exchanger, and a second expansion valve is provided between the third heat exchanger and the first heat exchanger.

[0015] Furthermore, in the battery thermal management system, the first heat exchanger and the second heat exchanger are plate heat exchangers.

[0016] Furthermore, in the battery thermal management system, an expansion valve is provided on the battery refrigerant circuit.

[0017] Another object of an embodiment of the present invention is to provide a control method, wherein the control method is applied to a controller in a vehicle, and the control method is applied to control the battery thermal management system as described above, and the control method includes:

[0018] obtaining a temperature of the battery;

[0019] When the temperature of the battery is less than a first temperature threshold, controlling the air conditioning refrigerant circuit or the coolant circuit to heat the battery through the battery refrigerant circuit;

[0020] When the temperature of the battery is greater than a second temperature threshold, controlling the air conditioning refrigerant circuit or the coolant circuit to cool the battery through the battery refrigerant circuit;

[0021] The second temperature threshold is greater than the first temperature threshold.

[0022] Furthermore, in the control method, when the temperature of the battery is greater than a second temperature threshold, the step of controlling the air conditioning refrigerant circuit or the coolant circuit to cool the battery through the battery refrigerant circuit includes:

[0023] When the temperature of the battery is greater than the second temperature threshold and less than or equal to a third temperature threshold, controlling the coolant circuit to cool the battery through the battery refrigerant circuit;

[0024] When the temperature of the battery is greater than the third temperature threshold, controlling the air conditioning refrigerant circuit to cool the battery through the battery refrigerant circuit;

[0025] Wherein, the third temperature threshold is greater than the second temperature threshold.

[0026] Furthermore, in the control method, when the temperature of the battery is less than a first temperature threshold, the step of controlling the air conditioning refrigerant circuit or the coolant circuit to heat the battery through the battery refrigerant circuit includes:

[0027] When the temperature of the battery is lower than a first temperature threshold, if the temperature difference between the coolant circuit and the battery refrigerant circuit is greater than or equal to a preset temperature difference threshold, controlling the coolant circuit to perform heat exchange with the battery refrigerant circuit through the second heat exchanger to heat the battery;

[0028] When the temperature of the battery is lower than a first temperature threshold, if the temperature difference is lower than the preset temperature difference threshold, and the compressor of the air-conditioning refrigerant circuit is not in a restricted start state, the air-conditioning refrigerant circuit is controlled to perform heating, and heat is exchanged with the battery refrigerant circuit through the first heat exchanger to heat the battery;

[0029] When the temperature of the battery is lower than a first temperature threshold, if the temperature difference is lower than the preset temperature difference threshold, and the compressor of the air-conditioning refrigerant circuit is in a restricted start state, the coolant circuit is controlled to heat, and heat is exchanged with the battery refrigerant circuit through the second heat exchanger to heat the battery.

[0030] Yet another object of the present invention is to provide a vehicle, wherein the vehicle comprises the battery thermal management system as described above.

[0031] Compared with the prior art, the battery thermal management system, control method and vehicle of the present invention have the following advantages:

[0032] A battery refrigerant circuit is provided to cool or heat the battery alone, and a first heat exchanger is provided between the battery refrigerant circuit and the vehicle's air conditioning refrigerant circuit, and a second heat exchanger is provided between the battery refrigerant circuit and the vehicle's coolant circuit. Because when the battery temperature is low, the air conditioning refrigerant circuit can be controlled to exchange heat with the battery refrigerant circuit through the first heat exchanger, or the coolant circuit can be controlled to exchange heat with the battery refrigerant circuit through the second heat exchanger to achieve heating of the battery; and when the battery temperature is high, the air conditioning refrigerant circuit can be controlled to exchange heat with the battery refrigerant circuit through the first heat exchanger, or the coolant circuit can be controlled to exchange heat with the battery refrigerant circuit through the second heat exchanger to achieve cooling of the battery. This not only avoids the direct entry of the air conditioning refrigerant into the battery, and does not cause problems with battery temperature uniformity and temperature fluctuation when adjusting the temperature at the same time as the vehicle interior, but also can exchange heat with the coolant circuit, using the waste heat of the internal combustion engine or drive system to cool and heat the battery, saving manufacturing and control costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0034] Figure 1 A schematic diagram of the structure of a battery thermal management system proposed in an embodiment of the present invention;

[0035] Figure 2 A schematic flow chart of a control method proposed in an embodiment of the present invention;

[0036] Figure 3 This is a schematic diagram of a first control state of a battery thermal management system in an embodiment of the present invention;

[0037] Figure 4 This is a schematic diagram of a second control state of a battery thermal management system in an embodiment of the present invention;

[0038] Figure 5 Schematic diagram of the third control state of the battery thermal management system in an embodiment of the present invention;

[0039] Figure 6 Schematic diagram of the fourth control state of the battery thermal management system in an embodiment of the present invention;

[0040] Figure 7 Schematic diagram of the fifth control state of the battery thermal management system in an embodiment of the present invention. DETAILED DESCRIPTION

[0041] Embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to enable the scope of the present invention to be fully communicated to those skilled in the art.

[0042] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0043] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0044] See also Figure 1 , showing a schematic structural diagram of a battery thermal management system provided in an embodiment of the present invention, the battery thermal management system provided in an embodiment of the present invention is specifically a battery thermal management system for an electric vehicle, including a battery refrigerant circuit 10, an air conditioning refrigerant circuit 20 and a coolant circuit 30; the battery refrigerant circuit 10 is used to cool or heat the battery;

[0045] A first heat exchanger 11 is provided between the battery refrigerant circuit 10 and the air conditioning refrigerant circuit 20; the first heat exchanger 11 is used for heat exchange between the battery refrigerant circuit 10 and the air conditioning refrigerant circuit 20;

[0046] A second heat exchanger 12 is disposed between the battery refrigerant circuit 10 and the coolant circuit 30 . The second heat exchanger 12 is used for heat exchange between the battery refrigerant circuit 10 and the coolant circuit 30 .

[0047] The air-conditioning refrigerant circuit 20 is used to adjust the temperature inside the vehicle; the coolant circuit 30 is used to cool and reduce the temperature of the vehicle's drive system, such as a motor or an internal combustion engine.

[0048] In the embodiment of the present invention, a battery refrigerant circuit 10 is provided for cooling or heating the battery alone, a first heat exchanger 11 is provided between the battery refrigerant circuit 10 and the air conditioning refrigerant circuit 20 of the vehicle, and a second heat exchanger 12 is provided between the battery refrigerant circuit 10 and the coolant circuit 30 of the vehicle. When the battery temperature is low, the air-conditioning refrigerant circuit 20 can be controlled to perform heat exchange with the battery refrigerant circuit 10 through the first heat exchanger 11, or the coolant circuit 30 can be controlled to perform heat exchange with the battery refrigerant circuit 10 through the second heat exchanger 12, so as to achieve heating of the battery; and when the battery temperature is high, the air-conditioning refrigerant circuit 20 can be controlled to perform heat exchange with the battery refrigerant circuit 10 through the first heat exchanger 11, or the coolant circuit 30 can be controlled to perform heat exchange with the battery refrigerant circuit 10 through the second heat exchanger 12, so as to achieve cooling of the battery. This not only avoids the direct entry of the air-conditioning refrigerant into the battery, and does not cause problems with battery temperature uniformity and temperature fluctuation when adjusting the temperature simultaneously with the vehicle interior temperature, but also can perform heat exchange with the coolant circuit 30, and utilize the waste heat of the internal combustion engine or the drive system to cool and heat the battery, effectively reducing the energy consumption of low-temperature vehicle driving, and saving manufacturing cost and control cost.

[0049] Optionally, in one embodiment, the first heat exchanger 11 and the second heat exchanger 12 are plate heat exchangers, which facilitate heat exchange between the battery refrigerant circuit 10 and the air conditioning refrigerant circuit 20 , and heat exchange between the battery refrigerant circuit 10 and the coolant circuit 30 .

[0050] Optionally, in one embodiment, the battery refrigerant circuit 10 includes a first compressor 13, and the first compressor 13, the first heat exchanger 11, the second heat exchanger 12 and the battery 14 are connected by pipelines to form a loop, and both ends of the first compressor 13 are connected to the first heat exchanger 11 and the battery 14 pipelines through a first four-way valve 15, that is, the four interfaces of the first four-way valve 15 are respectively connected to the output end of the first compressor 13, the first heat exchanger 11, the battery 14 and the input end pipelines of the first compressor 13.

[0051] Among them, by connecting the two interfaces of the first four-way valve 15 respectively connected to the output end of the first compressor 13 and the pipeline of the first heat exchanger 11, and connecting the two interfaces of the first four-way valve 15 respectively connected to the input end of the first compressor 13 and the pipeline of the battery 14, the battery refrigerant circuit 10 can be controlled to enter the cooling mode; and by connecting the two interfaces of the first four-way valve 15 respectively connected to the output end of the first compressor 13 and the pipeline of the battery 14, and connecting the two interfaces of the first four-way valve 15 respectively connected to the input end of the first compressor 13 and the pipeline of the first heat exchanger 11, the battery refrigerant circuit 10 can be controlled to enter the heating mode.

[0052] In this embodiment, the refrigerant in the battery refrigerant circuit 10 can be compressed and liquefied by utilizing the above-mentioned first compressor 13, and the cooling or heating mode switching of the battery refrigerant circuit 10 can be realized in combination with the above-mentioned first four-way valve 15, and the battery 14 can be autonomously auxiliary cooled or auxiliary heated by the first compressor 13 accordingly, so that the refrigerant flow of the battery refrigerant circuit 10 is easy to control, and will not cause the temperature uniformity problem of the battery 14 caused by insufficient distribution of the air-conditioning refrigerant flow, and the system control is simpler.

[0053] Optionally, in one embodiment, the air-conditioning refrigerant circuit 20 includes a second compressor 21, a third heat exchanger 22 and a fourth heat exchanger 23 connected by pipes to form a circuit, the third heat exchanger 22 is used for heat exchange with outdoor air, the fourth heat exchanger 23 is used for heat exchange with indoor air, and both ends of the second compressor 21 are connected to the fourth heat exchanger 23 and the third heat exchanger 22 by pipes through a second four-way valve 24, and the first heat exchanger 11 is arranged in parallel with the fourth heat exchanger 23.

[0054] In the above embodiment, because the four interfaces of the second four-way valve 24 are respectively connected to the output end of the second compressor 21, the fourth heat exchanger 23, the third heat exchanger 22 and the input end pipeline of the second compressor 21, the above-mentioned second compressor 21 can compress and liquefy the refrigerant in the air-conditioning refrigerant circuit 20, and the above-mentioned first heat exchanger 11 and the above-mentioned fourth heat exchanger 23 are arranged in parallel between the second four-way valve 24 and the fourth heat exchanger 23, so that the refrigerant flow used for heat exchange of the fourth heat exchanger 23 can be diverted to the first heat exchanger 11, and combined with the above-mentioned second four-way valve 24, the cooling or heating mode switching of the air-conditioning refrigerant circuit 20 can be realized, and correspondingly, the air-conditioning refrigerant circuit 20 is used to cool or heat the battery 14 through the first heat exchanger 11.

[0055] Optionally, in the above embodiment, a first expansion valve 25 is provided between the fourth heat exchanger 23 and the third heat exchanger 22, and a second expansion valve 26 is provided between the third heat exchanger 22 and the first heat exchanger 11, so as to facilitate precise control of the flow of the air-conditioning refrigerant flowing through the fourth heat exchanger 23 and the flow of the air-conditioning refrigerant flowing through the first heat exchanger 11, respectively, so as to realize precise temperature control of the battery and indoor air, respectively, and reduce mutual interference and fluctuation between the two during temperature control.

[0056] Optionally, the battery refrigerant circuit 10 is also provided with a third expansion valve 16 , which can be specifically provided on a pipeline between the second heat exchanger 12 and the battery 14 , so as to facilitate flow control of the battery refrigerant circuit 10 and achieve precise temperature control of the battery 14 .

[0057] Optionally, in one embodiment, the coolant circuit 30 includes a heat source 31 and a fifth heat exchanger 32, and both ends of the heat source 31 are connected to the pipes at both ends of the fifth heat exchanger 32 through a first three-way valve 33 and a second three-way valve 34, respectively. The second heat exchanger 12 is connected between the first three-way valve 33 and the second three-way valve 34 through a pipe, and the heat source 31 and the fifth heat exchanger 32 are also connected through a pipe provided with a water pump 35.

[0058] In the above embodiment, because the three interfaces of the first three-way valve 33 are respectively connected to the first interface end of the second heat exchanger 12, the third interface end of the fifth heat exchanger 32 and the input end pipeline of the heat source 31, and the three interfaces of the second three-way valve 34 are respectively connected to the second interface end of the second heat exchanger 12, the output end of the heat source 31 and the fourth interface end pipeline of the fifth heat exchanger 32, the first three-way valve 33 and the second three-way valve 34 can be controlled to realize the flow of coolant through the second heat exchanger 12, so that the heat of the heat source 31 is transferred to the second heat exchanger 12 by the coolant to heat the battery 14, or the coolant is used to cool the battery 14.

[0059] Optionally, in the above embodiment, the heat source includes not only an engine but also an electric heater. When the temperature of the heat source 31 decreases, that is, when the waste heat of the engine in the heat source 31 is insufficient to heat the battery 14 to a target temperature state, the electric heater can be used to heat the coolant, and then the coolant heated by the electric heater is used to perform heat exchange with the battery refrigerant circuit 10 at the second heat exchanger 12, and then the battery refrigerant circuit 10 heats the battery 14 until the battery 14 is heated to a target temperature state.

[0060] Another object of the present invention is to provide a control method, which is applied to a controller in a vehicle, and the control method is applied to control the battery thermal management system as described above, wherein the control method includes steps S100 to S300.

[0061] Step S100: Acquire the temperature of the battery.

[0062] In the above step S100, the temperature sensor is used to detect the temperature of the battery in real time, so as to control the operating state of the air-conditioning refrigerant circuit and the coolant circuit according to the real-time temperature of the battery, thereby achieving temperature control of the battery.

[0063] Step S200: When the temperature of the battery is less than a first temperature threshold, control the air-conditioning refrigerant circuit or the coolant circuit to heat the battery through the battery refrigerant circuit.

[0064] In the above step S200, the first temperature threshold is the lower limit of the temperature at which the battery has better performance. When the temperature of the battery is lower than the first temperature threshold, it means that the temperature of the battery is low and needs to be controlled to increase its temperature. Therefore, the air-conditioning refrigerant circuit is controlled to enter the heating mode, and then the first heat exchanger is used to perform heat exchange with the battery refrigerant circuit to heat the battery; or the coolant with a higher temperature in the coolant circuit is controlled to flow through the above-mentioned second heat exchanger, thereby performing heat exchange with the battery refrigerant circuit to heat the battery.

[0065] Step S300: When the temperature of the battery is greater than a second temperature threshold, control the air conditioning refrigerant circuit or the coolant circuit to cool the battery through the battery refrigerant circuit; wherein the second temperature threshold is greater than the first temperature threshold.

[0066] In the above step S300, the second temperature threshold is the upper temperature limit for the battery to have better performance. When the temperature of the battery is greater than the second temperature threshold, it means that the battery is overheated and needs to be cooled. Therefore, the air-conditioning refrigerant circuit is controlled to enter the cooling mode, and then the first heat exchanger is used to perform heat exchange with the battery refrigerant circuit to cool the battery; or the coolant with a lower temperature in the coolant circuit is controlled to flow through the above second heat exchanger, thereby performing heat exchange with the battery refrigerant circuit to cool the battery.

[0067] Compared with the prior art, the control method of the present invention has the following advantages:

[0068] When the battery temperature is low, the air-conditioning refrigerant circuit is controlled to exchange heat with the battery refrigerant circuit through the first heat exchanger, or the coolant circuit is controlled to exchange heat with the battery refrigerant circuit through the second heat exchanger, so as to heat the battery; and when the battery temperature is high, the air-conditioning refrigerant circuit is controlled to exchange heat with the battery refrigerant circuit through the first heat exchanger, or the coolant circuit is controlled to exchange heat with the battery refrigerant circuit through the second heat exchanger, so as to cool the battery. This not only avoids the direct entry of the air-conditioning refrigerant into the battery, and does not cause problems with battery temperature uniformity and temperature fluctuation when adjusting the temperature simultaneously with the vehicle interior temperature, but also can exchange heat with the coolant circuit, and use the waste heat of the internal combustion engine or drive system to cool and heat the battery, saving manufacturing cost and control cost.

[0069] Optionally, in one implementation, the above step S200 includes steps S201 to S203:

[0070] Step S201: When the temperature of the battery is lower than a first temperature threshold, if the temperature difference between the temperature of the coolant circuit and the temperature of the battery refrigerant circuit is greater than or equal to a preset temperature difference threshold, the coolant circuit is controlled to perform heat exchange with the battery refrigerant circuit through the second heat exchanger to heat the battery.

[0071] In the above step S201, the above preset temperature difference threshold is the temperature difference between the coolant circuit temperature and the battery refrigerant circuit temperature at which the coolant can effectively heat the battery. The preset temperature difference threshold needs to be calibrated in advance according to the battery thermal management system structure; when the battery temperature is less than the first temperature threshold, it means that the battery needs to be heated. If the temperature difference between the coolant circuit and the battery refrigerant circuit is greater than or equal to the above preset temperature difference threshold, it means that the coolant temperature is high enough to effectively heat the battery. Therefore, the coolant circuit is controlled to perform heat exchange with the battery refrigerant circuit through the second heat exchanger, thereby achieving heating of the battery.

[0072] Specifically, Figure 1 In the process, the two interfaces of the first three-way valve respectively connected to the second heat exchanger and the heat source pipeline are connected, and the two interfaces of the second three-way valve connected to the heat source and the fifth heat exchanger pipeline are connected; at the same time, the two interfaces of the first four-way valve respectively connected to the output end of the first compressor and the second heat exchanger pipeline are connected, and the two interfaces of the first four-way valve respectively connected to the input end of the first compressor and the first heat exchanger pipeline are connected to control the battery refrigerant circuit to enter the heating mode; the specific control effect is as follows Figure 3 shown.

[0073] Step S202: When the temperature of the battery is lower than a first temperature threshold, if the temperature difference is lower than the preset temperature difference threshold, and the compressor of the air-conditioning refrigerant circuit is not in a restricted start-up state, the air-conditioning refrigerant circuit is controlled to heat, and heat is exchanged with the battery refrigerant circuit through the first heat exchanger to heat the battery.

[0074] In the above step S202, the restricted startup state is a low-temperature protection state in which the heating mode cannot be executed; it is not in the restricted startup state, that is, the compressor can enter the heating mode normally. When the temperature of the battery is less than the first temperature threshold, it means that the battery needs to be heated. If the temperature difference between the coolant circuit and the battery refrigerant circuit is less than the above preset temperature difference threshold, it means that the coolant temperature is not high enough to effectively heat the battery. At this time, if the compressor of the air-conditioning refrigerant circuit can enter the heating mode normally, the air-conditioning refrigerant circuit can be controlled to heat, and heat exchange can be performed with the battery refrigerant circuit through the first heat exchanger, thereby heating the battery.

[0075] Specifically, in Figure 1 In the process, the two interfaces of the second four-way valve respectively connected to the output end of the second compressor and the third heat exchanger pipeline are connected, and the two interfaces of the second four-way valve respectively connected to the input end of the second compressor and the fourth heat exchanger pipeline are connected to control the air conditioning refrigerant circuit to enter the heating mode; at the same time, the two interfaces of the first four-way valve respectively connected to the output end of the first compressor and the battery pipeline are connected, and the two interfaces of the first four-way valve respectively connected to the input end of the first compressor and the first heat exchanger pipeline are connected to control the battery refrigerant circuit to enter the heating mode; the specific control effect is as follows Figure 4 shown.

[0076] Step S203: When the temperature of the battery is lower than a first temperature threshold, if the temperature difference is lower than the preset temperature difference threshold, and the compressor of the air-conditioning refrigerant circuit is in a restricted start state, the coolant circuit is controlled to heat, and heat is exchanged with the battery refrigerant circuit through the second heat exchanger to heat the battery.

[0077] In the above step S203, when the temperature of the battery is lower than the first temperature threshold, it indicates that the battery needs to be heated. If the temperature difference between the coolant circuit and the battery refrigerant circuit is lower than the above preset temperature difference threshold, it indicates that the coolant temperature is not high enough to effectively heat the battery. At this time, if the compressor of the air-conditioning refrigerant circuit is in a restricted start-up state, that is, it cannot enter the heating mode normally, the coolant circuit can be controlled to heat. Specifically, the electric heater in the coolant circuit actively consumes energy to heat the coolant flowing into the second heat exchanger, and then performs heat exchange with the battery refrigerant circuit through the second heat exchanger, thereby achieving heating of the battery.

[0078] Specifically, in Figure 1 In the process, the two interfaces of the first three-way valve respectively connected to the second heat exchanger and the fifth heat exchanger pipeline are connected, the two interfaces respectively connected to the second heat exchanger and the heat source pipeline are connected, and the two interfaces of the second three-way valve connected to the second heat exchanger and the fifth heat exchanger pipeline are connected, and the electric heater is controlled to perform heating; at the same time, the two interfaces of the first four-way valve respectively connected to the output end of the first compressor and the second heat exchanger pipeline are connected, and the two interfaces of the first four-way valve respectively connected to the input end of the first compressor and the first heat exchanger pipeline are connected to control the battery refrigerant circuit to enter the heating mode; the specific control effect is as follows Figure 5 shown.

[0079] In the above embodiment, when the battery needs to be heated, based on the temperature difference between the battery refrigerant circuit and the coolant circuit and the state of the compressor in the air-conditioning refrigerant circuit, it is determined whether to control the coolant circuit to exchange heat with the battery refrigerant circuit through the second heat exchanger, or to control the air-conditioning refrigerant circuit to exchange heat with the battery refrigerant circuit through the first heat exchanger to achieve heating of the battery, which can effectively improve the waste heat utilization rate of the heat source in the vehicle, thereby reducing the consumption of electric energy.

[0080] Optionally, in one implementation, the above step S300 further includes steps S301 to S302.

[0081] Step S301: When the temperature of the battery is greater than the second temperature threshold and less than or equal to a third temperature threshold, control the coolant circuit to cool the battery through the battery refrigerant circuit.

[0082] In the above step S301, the third temperature threshold is a temperature threshold that determines whether the battery can be effectively cooled down by the coolant circuit; when the battery temperature is greater than the second temperature threshold and less than or equal to the third temperature threshold, it means that the battery is overheated, but its overheating degree is still within the control range that can be cooled down by the coolant circuit to below the above second temperature threshold, so the coolant in the coolant circuit is controlled to flow through the above second heat exchanger to perform heat exchange with the battery refrigerant circuit at the second heat exchanger, thereby achieving cooling down of the battery.

[0083] Specifically, in Figure 1 In the process, the two interfaces of the first three-way valve respectively connected to the second heat exchanger and the fifth heat exchanger pipeline are connected, and the two interfaces of the second three-way valve connected to the heat source and the second heat exchanger pipeline are connected, and the electric heater is controlled to perform heating; at the same time, the two interfaces of the first four-way valve respectively connected to the output end of the first compressor and the first heat exchanger pipeline are connected, and the two interfaces of the first four-way valve respectively connected to the input end of the first compressor and the second heat exchanger pipeline are connected to control the battery refrigerant circuit to enter the cooling mode; the specific control effect is as follows Figure 6 shown.

[0084] Step S302: When the temperature of the battery is greater than the third temperature threshold, control the air-conditioning refrigerant circuit to cool the battery through the battery refrigerant circuit; wherein the third temperature threshold is greater than the second temperature threshold.

[0085] In the above step S302, when the temperature of the battery is greater than the above third temperature threshold, it means that the battery is overheated, and the degree of overheating has exceeded the control range that can be cooled by the coolant circuit to below the above second temperature threshold. Therefore, the air conditioning refrigerant circuit is controlled to enter the cooling mode, and its refrigerant is controlled to flow through the first heat exchanger to perform heat exchange with the battery refrigerant circuit at the first heat exchanger, thereby achieving cooling of the battery.

[0086] Specifically, in Figure 1 In the embodiment, the two interfaces of the second four-way valve respectively connected to the output end of the second compressor and the third heat exchanger pipeline are connected, and the two interfaces of the second four-way valve respectively connected to the output end of the second compressor and the fourth heat exchanger pipeline are connected, so as to control the battery refrigerant circuit to enter the cooling mode; at the same time, the two interfaces of the first four-way valve respectively connected to the output end of the first compressor and the first heat exchanger pipeline are connected, and the two interfaces of the first four-way valve respectively connected to the input end of the first compressor and the second heat exchanger pipeline are connected, so as to control the battery refrigerant circuit to enter the cooling mode. The specific control effect is as follows: Figure 7 shown.

[0087] In the above embodiment, when the battery cooling demand is low, the coolant circuit cools it through the battery coolant circuit, and when the battery cooling demand is high, the air-conditioning refrigerant circuit cools the battery through the battery refrigerant circuit, thereby minimizing the use of the air-conditioning refrigerant circuit and effectively reducing energy consumption.

[0088] Another object of the present invention is to provide a vehicle, wherein the vehicle includes the battery thermal management system as described above.

[0089] The advantages of the vehicle, the battery thermal management system and the control method described above over the prior art are the same and will not be elaborated herein.

[0090] In summary, the battery thermal management system, control method and vehicle provided by the present invention are provided with a battery refrigerant circuit for cooling or heating the battery alone, and a first heat exchanger is provided between the battery refrigerant circuit and the air conditioning refrigerant circuit of the vehicle, and a second heat exchanger is provided between the battery refrigerant circuit and the coolant circuit of the vehicle. Because when the battery temperature is low, the air conditioning refrigerant circuit can be controlled to exchange heat with the battery refrigerant circuit through the first heat exchanger, or the coolant circuit can be controlled to exchange heat with the battery refrigerant circuit through the second heat exchanger to achieve heating of the battery; and when the battery temperature is high, the air conditioning refrigerant circuit can be controlled to exchange heat with the battery refrigerant circuit through the first heat exchanger, or the coolant circuit can be controlled to exchange heat with the battery refrigerant circuit through the second heat exchanger to achieve cooling of the battery, which not only avoids the direct entry of the air conditioning refrigerant into the battery, and does not cause the problem of battery temperature uniformity and temperature fluctuation when adjusting the temperature at the same time as the vehicle interior, but also can exchange heat with the coolant circuit, using the waste heat of the internal combustion engine or the drive system to cool and heat the battery, saving manufacturing cost and control cost.

[0091] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0092] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

[0093] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A control method, characterized in that: The control method is used to control the battery thermal management system. The battery thermal management system includes a battery refrigerant circuit, an air conditioning refrigerant circuit and a coolant circuit; the battery refrigerant circuit is used to cool or heat the battery; A first heat exchanger is provided between the battery refrigerant circuit and the air-conditioning refrigerant circuit; the first heat exchanger is used for heat exchange between the battery refrigerant circuit and the air-conditioning refrigerant circuit; A second heat exchanger is provided between the battery refrigerant circuit and the coolant circuit, and the second heat exchanger is used for heat exchange between the battery refrigerant circuit and the coolant circuit; The control method comprises: obtaining a temperature of the battery; When the temperature of the battery is less than a first temperature threshold, controlling the air conditioning refrigerant circuit or the coolant circuit to heat the battery through the battery refrigerant circuit; When the temperature of the battery is greater than a second temperature threshold, controlling the air conditioning refrigerant circuit or the coolant circuit to cool the battery through the battery refrigerant circuit; Wherein, the second temperature threshold is greater than the first temperature threshold; When the temperature of the battery is less than a first temperature threshold, the step of controlling the air conditioning refrigerant circuit or the coolant circuit to heat the battery through the battery refrigerant circuit includes: When the temperature of the battery is lower than the first temperature threshold, if the temperature difference between the coolant circuit and the battery refrigerant circuit is greater than or equal to a preset temperature difference threshold, control the coolant circuit to perform heat exchange with the battery refrigerant circuit through the second heat exchanger to heat the battery; When the temperature of the battery is lower than the first temperature threshold, if the temperature difference is lower than the preset temperature difference threshold, and the compressor of the air-conditioning refrigerant circuit is not in a restricted start state, the air-conditioning refrigerant circuit is controlled to perform heating, and heat is exchanged with the battery refrigerant circuit through the first heat exchanger to heat the battery; When the temperature of the battery is lower than the first temperature threshold, if the temperature difference is lower than the preset temperature difference threshold, and the compressor of the air-conditioning refrigerant circuit is in a restricted start state, the coolant circuit is controlled to heat, and heat is exchanged with the battery refrigerant circuit through the second heat exchanger to heat the battery.

2. The control method according to claim 1, characterized in that: The battery refrigerant circuit includes a first compressor, the first compressor, the first heat exchanger, the second heat exchanger and a battery pipeline are connected to form a circuit, and both ends of the first compressor are connected to the first heat exchanger and the battery pipeline through a first four-way valve.

3. The control method according to claim 1, characterized in that: The air conditioner refrigerant circuit includes a second compressor, a third heat exchanger and a fourth heat exchanger connected by pipes to form a circuit, the third heat exchanger is used for heat exchange with outdoor air, the fourth heat exchanger is used for heat exchange with indoor air, both ends of the second compressor are connected to the fourth heat exchanger and the third heat exchanger pipes through a second four-way valve, and the first heat exchanger and the fourth heat exchanger are arranged in parallel.

4. The control method according to claim 1, characterized in that: The coolant circuit includes a heat source and a fifth heat exchanger. The two ends of the heat source are connected to the two end pipes of the fifth heat exchanger through a first three-way valve and a second three-way valve respectively. The second heat exchanger is connected between the first three-way valve and the second three-way valve through a pipe. The heat source and the fifth heat exchanger are also connected through a pipe equipped with a water pump.

5. The control method according to claim 4, characterized in that: The heat source includes an electric heater.

6. The control method according to claim 3, characterized in that: A first expansion valve is disposed between the fourth heat exchanger and the third heat exchanger, and a second expansion valve is disposed between the third heat exchanger and the first heat exchanger.

7. The control method according to claim 1, characterized in that: When the temperature of the battery is greater than a second temperature threshold, the step of controlling the air conditioning refrigerant circuit or the coolant circuit to cool the battery through the battery refrigerant circuit comprises: When the temperature of the battery is greater than the second temperature threshold and less than or equal to a third temperature threshold, controlling the coolant circuit to cool the battery through the battery refrigerant circuit; When the temperature of the battery is greater than the third temperature threshold, controlling the air conditioning refrigerant circuit to cool the battery through the battery refrigerant circuit; Wherein, the third temperature threshold is greater than the second temperature threshold.

8. A vehicle, characterized in that: It includes a battery thermal management system, which is used to execute the control method as described in any one of claims 1-7.

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