A battery pack temperature control method, device and system for a thermal management system

Abstract

Embodiments of the present invention disclose a battery pack temperature control method, device, and system for a thermal management system. The thermal management system includes a refrigerant circuit, a water circuit, and a controller. The refrigerant circuit includes a compressor, a condenser, an evaporator, a water-cooled heat exchanger, a gas-liquid separator, a first electronic expansion valve, and a battery pack. A control method is executed by the controller, and the control method includes: obtaining the temperature and pressure of the second end of the water-cooled heat exchanger and the temperature and pressure of the first end of the battery pack. The current operating mode of the thermal management system is a single-battery cooling mode or a battery refrigeration compartment heating mode. According to the temperature and pressure of the second end of the water-cooled heat exchanger and the temperature and pressure of the first end of the battery pack, the first opening and the second opening of the first electronic expansion valve are determined; according to the first opening and the second opening, the target opening of the first electronic expansion valve is determined. The battery pack temperature control method, device, and system for the thermal management system provided by the embodiments of the present invention can prevent excessive temperature differences between the inlet and outlet of the battery pack.

Description

Technical Field

[0001] Embodiments of the present invention relate to thermal system control technology, and more particularly to a method, device, and system for controlling the temperature of a battery pack in a thermal management system. Background Art

[0002] Thermal management systems cool or heat the battery pack during operation. Excessively high or low battery pack temperatures can affect the battery pack's operation. Therefore, the thermal management system must control the battery pack temperature to prevent it from overheating or underheating. Currently, existing thermal management system temperature control methods for battery packs suffer from a large temperature difference between the inlet and outlet of the battery pack, leading to excessive temperature differences within the battery cells. Summary of the Invention

[0003] Embodiments of the present invention provide a method, device, and system for controlling the temperature of a battery pack in a thermal management system to prevent excessive temperature differences between the inlet and outlet of the battery pack.

[0004] In a first aspect, an embodiment of the present invention provides a battery pack temperature control method for a thermal management system, the thermal management system comprising a refrigerant circuit, a water circuit, and a controller, the refrigerant circuit comprising a compressor, a condenser, an evaporator, a water-cooled heat exchanger, a gas-liquid separator, a first electronic expansion valve, and a battery pack; the outlet of the compressor is in communication with a first end of the water-cooled heat exchanger, an inlet of the condenser, and a first end of the battery pack; the second end of the water-cooled heat exchanger is in communication with the outlet of the condenser, the outlet of the condenser is in communication with an inlet of the evaporator and a second end of the battery pack; the outlet of the evaporator is in communication with the first end of the battery pack and the first end of the water-cooled heat exchanger; the first end of the battery pack is in communication with the inlet of the gas-liquid separator; the outlet of the gas-liquid separator is in communication with the inlet of the compressor; the first electronic expansion valve is located in a pipeline connected to the second end of the battery pack and is close to the second end of the battery pack; the third and fourth ends of the water-cooled heat exchanger are in communication with the water circuit; the compressor and the first electronic expansion valve are both electrically connected to the controller; the control method is executed by the controller, and the control method includes:

[0005] Acquiring the temperature and pressure of the second end of the water-cooled heat exchanger and the temperature and pressure of the first end of the battery pack; the current operating mode of the thermal management system is a single battery cooling mode or a battery cooling cabin heating mode;

[0006] determining a first opening degree and a second opening degree of the first electronic expansion valve according to the temperature and pressure of the second end of the water-cooled heat exchanger and the temperature and pressure of the first end of the battery pack;

[0007] A target opening of the first electronic expansion valve is determined according to the first opening and the second opening to control the temperature of the battery pack.

[0008] Optionally, determining the first opening and the second opening of the first electronic expansion valve according to the temperature and pressure at the second end of the water-cooled heat exchanger and the temperature and pressure at the first end of the battery pack includes:

[0009] determining a subcooling degree at the second end of the water-cooled heat exchanger according to the temperature and pressure at the second end of the water-cooled heat exchanger;

[0010] determining an overheat degree of the first end of the battery pack according to the temperature and pressure of the first end of the battery pack;

[0011] A first opening degree and a second opening degree of the first electronic expansion valve are determined according to the second-end subcooling degree, the first-end superheating degree, a target superheating degree, and a target subcooling degree.

[0012] Optionally, determining the first opening degree and the second opening degree of the first electronic expansion valve according to the second end subcooling degree, the first end superheating degree, the target superheating degree, and the target subcooling degree includes:

[0013] determining a superheat difference between the first end superheat and the target superheat according to the first end superheat and the target superheat, and performing PID control on the superheat difference to obtain a first opening of the first electronic expansion valve;

[0014] A subcooling difference between the second end subcooling degree and the target subcooling degree is determined according to the second end subcooling degree and the target subcooling degree, and a second opening degree of the first electronic expansion valve is obtained by performing PID control on the subcooling difference.

[0015] Optionally, determining a target opening of the first electronic expansion valve according to the first opening and the second opening to control the temperature of the battery pack includes:

[0016] If the first opening is greater than the second opening, the first opening is used as the target opening;

[0017] If the first opening is smaller than the second opening, the second opening is used as the target opening.

[0018] Optionally, the water circuit includes an armature assembly, an electronic water pump, a radiator, and a cooling fan; the third end of the water-cooled heat exchanger, the armature assembly, the electronic water pump, and the radiator are sequentially connected; the cooling fan is located on one side of the radiator; and the cooling fan is electrically connected to the controller;

[0019] After determining the target opening of the first electronic expansion valve, the method includes:

[0020] When the overheat degree of the first end of the battery pack is greater than a preset overheat threshold, and the first electronic expansion valve fails or the opening degree of the first electronic expansion valve reaches a preset opening degree threshold, controlling the speed of the cooling fan to increase;

[0021] When the rotation speed of the cooling fan increases to a preset rotation speed threshold, the rotation speed of the compressor is controlled to decrease.

[0022] Optionally, the refrigerant circuit further includes a second electronic expansion valve, a third electronic expansion valve, a fourth electronic expansion valve, a first solenoid valve, a second solenoid valve, a third solenoid valve and a fourth solenoid valve, the second electronic expansion valve being located in a pipeline connected to the inlet of the evaporator and close to the inlet of the evaporator, the third electronic expansion valve being located in a pipeline connected to the outlet of the condenser and close to the outlet of the condenser, the fourth electronic expansion valve being located in a pipeline connected to the first end of the battery pack and the inlet of the gas-liquid separator, the first solenoid valve being located in a pipeline connected to the outlet of the compressor and the first end of the water-cooled heat exchanger, the second solenoid valve being located in a pipeline connected to the first end of the battery pack and the inlet of the condenser, the third solenoid valve being located in a pipeline connected to the outlet of the evaporator and the first end of the water-cooled heat exchanger, and the fourth solenoid valve being located in a pipeline connected to the first end of the battery pack and the inlet of the gas-liquid separator; each solenoid valve and each electronic expansion valve are electrically connected to the controller;

[0023] After determining the target opening of the first electronic expansion valve, the method includes:

[0024] The first solenoid valve, the fourth solenoid valve, and the fourth electronic expansion valve are all controlled to be turned on, and the second solenoid valve, the third solenoid valve, the second electronic expansion valve, and the third electronic expansion valve are all controlled to be turned off.

[0025] In a second aspect, an embodiment of the present invention provides a battery pack temperature control device of a thermal management system, the thermal management system including a refrigerant circuit, a water circuit and a controller, the refrigerant circuit including a compressor, a condenser, an evaporator, a water-cooled heat exchanger, a gas-liquid separator, a first electronic expansion valve and a battery pack; the outlet of the compressor is connected to the first end of the water-cooled heat exchanger, the inlet of the condenser and the first end of the battery pack, the second end of the water-cooled heat exchanger is connected to the outlet of the condenser, the outlet of the condenser is connected to the inlet of the evaporator and the second end of the battery pack, the outlet of the evaporator is connected to the first end of the battery pack and the first end of the water-cooled heat exchanger, the first end of the battery pack is connected to the inlet of the gas-liquid separator, the outlet of the gas-liquid separator is connected to the inlet of the compressor, the first electronic expansion valve is located in a pipeline connected to the second end of the battery pack and is close to the second end of the battery pack, the third and fourth ends of the water-cooled heat exchanger are connected to the water circuit; the compressor and the first electronic expansion valve are both electrically connected to the controller; the control device includes:

[0026] a parameter acquisition module, configured to acquire the temperature and pressure at the second end of the water-cooled heat exchanger and the temperature and pressure at the first end of the battery pack;

[0027] an opening degree determining module, configured to determine a first opening degree and a second opening degree of the first electronic expansion valve according to the temperature and pressure at the second end of the water-cooled heat exchanger and the temperature and pressure at the first end of the battery pack;

[0028] A temperature control module is configured to determine a target opening of the first electronic expansion valve according to the first opening and the second opening, so as to control the temperature of the battery pack.

[0029] In a third aspect, an embodiment of the present invention provides a thermal management system, comprising: a refrigerant circuit, a water circuit and a controller, wherein the refrigerant circuit comprises a compressor, a condenser, an evaporator, a water-cooled heat exchanger, a gas-liquid separator, a first electronic expansion valve and a battery pack; the outlet of the compressor is connected to the first end of the water-cooled heat exchanger, the inlet of the condenser and the first end of the battery pack, the second end of the water-cooled heat exchanger is connected to the outlet of the condenser, the outlet of the condenser is connected to the inlet of the evaporator and the second end of the battery pack, the outlet of the evaporator is connected to the first end of the battery pack and the first end of the water-cooled heat exchanger, the first end of the battery pack is connected to the inlet of the gas-liquid separator, the outlet of the gas-liquid separator is connected to the inlet of the compressor, the first electronic expansion valve is located in a pipeline connected to the second end of the battery pack and is close to the second end of the battery pack, the third and fourth ends of the water-cooled heat exchanger are connected to the water circuit; the compressor and the first electronic expansion valve are both electrically connected to the controller, and the control device as described in the second aspect is integrated into the controller.

[0030] Optionally, the refrigerant circuit also includes a second electronic expansion valve, a third electronic expansion valve, a fourth electronic expansion valve, a first solenoid valve, a second solenoid valve, a third solenoid valve and a fourth solenoid valve, the second electronic expansion valve is located in a pipeline connected to the inlet of the evaporator and is close to the inlet of the evaporator, the third electronic expansion valve is located in a pipeline connected to the outlet of the condenser and is close to the outlet of the condenser, the fourth electronic expansion valve is located in a pipeline connected to the first end of the battery pack and the inlet of the gas-liquid separator, the first solenoid valve is located in a pipeline connected to the outlet of the compressor and the first end of the water-cooled heat exchanger, the second solenoid valve is located in a pipeline connected to the first end of the battery pack and the inlet of the condenser, the third solenoid valve is located in a pipeline connected to the outlet of the evaporator and the first end of the water-cooled heat exchanger, and the fourth solenoid valve is located in a pipeline connected to the first end of the battery pack and the inlet of the gas-liquid separator; each solenoid valve and each electronic expansion valve is electrically connected to the controller.

[0031] Optionally, the water circuit includes an armature assembly, an electronic water pump, a radiator and a cooling fan, the third end of the water-cooled heat exchanger, the armature assembly, the electronic water pump, the radiator and the fourth end of the water-cooled heat exchanger are connected in sequence, and the cooling fan is located on one side of the radiator; the cooling fan is electrically connected to the controller.

[0032] The battery pack temperature control method, device and system of the thermal management system provided by the embodiment of the present invention, the thermal management system includes a refrigerant circuit, a water circuit and a controller, the refrigerant circuit includes a compressor, a condenser, an evaporator, a water-cooled heat exchanger, a gas-liquid separator, a first electronic expansion valve and a battery pack; the outlet of the compressor is connected to the first end of the water-cooled heat exchanger, the inlet of the condenser and the first end of the battery pack, the second end of the water-cooled heat exchanger is connected to the outlet of the condenser, the outlet of the condenser is connected to the inlet of the evaporator and the second end of the battery pack, the outlet of the evaporator is connected to the first end of the battery pack and the first end of the water-cooled heat exchanger, the first end of the battery pack is connected to the inlet of the gas-liquid separator, the outlet of the gas-liquid separator is connected to the inlet of the compressor, the first electronic expansion valve ... The expansion valve is located in a pipeline connected to the second end of the battery pack and is close to the second end of the battery pack. The third and fourth ends of the water-cooled heat exchanger are connected to the water circuit. The compressor and the first electronic expansion valve are both electrically connected to a controller. A control method is executed by the controller. The control method includes: obtaining the temperature and pressure of the second end of the water-cooled heat exchanger and the temperature and pressure of the first end of the battery pack; the current operating mode of the thermal management system is single battery cooling mode or battery cooling compartment heating mode; determining a first opening and a second opening of the first electronic expansion valve based on the temperature and pressure of the second end of the water-cooled heat exchanger and the temperature and pressure of the first end of the battery pack; and determining a target opening of the first electronic expansion valve based on the first opening and the second opening to control the temperature of the battery pack. The battery pack temperature control method, device, and system of the thermal management system provided in the embodiment of the present invention control the flow rate of refrigerant flowing through the battery pack through the first electronic expansion valve by controlling the opening of the first electronic expansion valve, thereby controlling the inlet subcooling and outlet superheating of the battery pack, preventing excessive inlet subcooling or outlet superheating of the battery pack, and thus preventing excessive temperature difference between the inlet and outlet refrigerant of the battery pack. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a flow chart of a battery pack temperature control method of a thermal management system provided in Example 1 of the present invention;

[0034] Figure 2 This is a schematic structural diagram of a thermal management system provided by Embodiment 1 of the present invention;

[0035] Figure 3 This is a flow chart of a battery pack temperature control method of a thermal management system provided in Embodiment 2 of the present invention;

[0036] Figure 4 This is a schematic structural diagram of a thermal management system in single-battery cooling mode provided by the second embodiment of the present invention;

[0037] Figure 5 This is a schematic structural diagram of a thermal management system in a heating mode within a battery refrigeration compartment provided by a second embodiment of the present invention;

[0038] Figure 6 This is a schematic diagram of opening and pressure difference provided by the second embodiment of the present invention;

[0039] Figure 7 This is a structural block diagram of a battery pack temperature control device of a thermal management system provided in Example 3 of the present invention. DETAILED DESCRIPTION

[0040] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It will be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

[0041] Example 1

[0042] Figure 1 This is a flow chart of a battery pack temperature control method of a thermal management system provided in Example 1 of the present invention. Figure 2 This is a schematic diagram of the structure of a thermal management system provided by the first embodiment of the present invention. This embodiment can be applied to aspects such as controlling the battery pack temperature of the thermal management system. Figure 1 and Figure 2 The thermal management system includes a refrigerant circuit 100, a water circuit 200 and a controller (not shown in the figure). The refrigerant circuit 100 includes a compressor 10, a condenser 20, an evaporator 30, a water-cooled heat exchanger 40, a gas-liquid separator 50, a first electronic expansion valve 61 and a battery pack 70; the outlet of the compressor 10 is connected to the first end of the water-cooled heat exchanger 40, the inlet of the condenser 20, and the first end of the battery pack 70, the second end of the water-cooled heat exchanger 40 is connected to the outlet of the condenser 20, the outlet of the condenser 20 is connected to the inlet of the evaporator 30 and the second end of the battery pack 70, and the outlet of the evaporator 30 is connected to the battery pack 70. 0 and the first end of the water-cooled heat exchanger 40 are connected, the first end of the battery pack 70 is connected to the inlet of the gas-liquid separator 50, the outlet of the gas-liquid separator 50 is connected to the inlet of the compressor 10, the first electronic expansion valve 61 is located in the pipeline connected to the second end of the battery pack 70 and is close to the second end of the battery pack 70, the third and fourth ends of the water-cooled heat exchanger 40 are connected to the water circuit 200; the compressor 10 and the first electronic expansion valve 61 are both electrically connected to the controller; the method can be implemented in the controller of the thermal management system, and the controller can be implemented in the form of software and / or hardware. The method specifically includes the following steps:

[0043] Step 110: Obtain the temperature and pressure at the second end of the water-cooled heat exchanger and the temperature and pressure at the first end of the battery pack; the current operating mode of the thermal management system is single battery cooling mode or battery cooling cabin heating mode.

[0044] Specifically, the second end of the water-cooled heat exchanger and the first end of the battery pack are both provided with pressure and temperature sensors, which can collect the pressure and temperature at their respective locations. The battery pack temperature control device of the thermal management system is electrically connected to each pressure and temperature sensor to obtain the temperature and pressure at the second end of the water-cooled heat exchanger and the temperature and pressure at the first end of the battery pack.

[0045] Step 120 : Determine a first opening degree and a second opening degree of the first electronic expansion valve according to the temperature and pressure at the second end of the water-cooled heat exchanger and the temperature and pressure at the first end of the battery pack.

[0046] Specifically, based on the temperature and pressure of the first end of the battery pack, the overheat of the first end of the battery pack is determined (in the single battery cooling mode or the battery refrigeration cabin heating mode, the overheat of the first end of the battery pack is the outlet overheat of the battery pack), and based on the overheat of the first end of the battery pack and the target overheat, the first opening of the first electronic expansion valve is determined; and based on the temperature and pressure of the second end of the water-cooled heat exchanger (equivalent to the temperature and pressure of the second end of the battery pack), the subcooling of the second end of the water-cooled heat exchanger is determined (equivalent to the subcooling of the second end of the battery pack, in the single battery cooling mode or the battery refrigeration cabin heating mode, the subcooling of the second end of the battery pack is the inlet subcooling of the battery pack), and based on the subcooling of the second end of the water-cooled heat exchanger and the target subcooling, the second opening of the first electronic expansion valve is determined.

[0047] For example, the target subcooling is 5°C (calibration value 1), and the target superheat is 5°C (calibration value 2). Calibration value 1: used to control the refrigerant in front of the first electronic expansion valve to be in a pure liquid state. If it is too large, the second end of the battery pack will be in a large subcooling state under low load conditions. If it is too small, stable control of the subcooling cannot be achieved. Too large or too small will also affect the system performance. Therefore, calibration value 1 needs to be in a suitable range such as 4-10°C. Calibration value 2: used to control the refrigerant at the first end of the battery pack to be in a small superheat state. If it is too large, it will not prevent the first end of the battery pack from overheating. If it is too small, stable control of the superheat cannot be achieved. Therefore, calibration value 2 needs to be in a suitable range such as 4-6°C. The maximum acceptable degree of overheating at the first end of the battery pack is represented by calibration value 3, and the range of calibration value 3 is 10-15°C.

[0048] Step 130 : Determine a target opening of the first electronic expansion valve according to the first opening and the second opening to control the temperature of the battery pack.

[0049] Specifically, the larger of the first opening and the second opening is used as the target opening of the first electronic expansion valve, and the opening of the first electronic expansion valve is controlled to reach the target opening to control the flow of refrigerant flowing through the battery pack through the first electronic expansion valve, thereby controlling the inlet supercooling and outlet superheating of the battery pack to prevent a large temperature difference between the inlet and outlet of the battery pack.

[0050] It should be noted that the specific duration of the above preset time can be determined according to actual control requirements and is not limited here.

[0051] The battery pack temperature control method of the thermal management system provided in this embodiment controls the opening of the first electronic expansion valve to control the flow of refrigerant flowing through the battery pack through the first electronic expansion valve, thereby controlling the inlet supercooling and outlet superheating of the battery pack, preventing the inlet supercooling of the battery pack from being too large or the outlet superheating from being too large, thereby preventing the inlet and outlet temperature difference of the battery pack from being too large.

[0052] Example 2

[0053] Figure 3 This is a flow chart of a method for controlling the battery pack temperature of a thermal management system provided in the second embodiment of the present invention. This embodiment is applicable to controlling the battery pack temperature of the thermal management system. The structure of the thermal management system is as follows: Figure 2 As shown, the specific description can refer to the first embodiment, which will not be repeated here; the method can be implemented in the controller of the thermal management system, and the controller can be implemented in the form of software and / or hardware. The method specifically includes the following steps:

[0054] Step 210: Obtain the temperature and pressure at the second end of the water-cooled heat exchanger and the temperature and pressure at the first end of the battery pack; the current operating mode of the thermal management system is the single battery cooling mode or the battery cooling cabin heating mode.

[0055] Specifically, when the working mode of the thermal management system is the single battery cooling mode or the battery cooling compartment heating mode, the second end temperature and pressure of the water-cooled heat exchanger and the first end temperature and pressure of the battery pack are obtained. The specific acquisition process can be referred to the description of the above embodiment and will not be repeated here.

[0056] Step 220: Determine the subcooling degree at the second end of the water-cooled heat exchanger based on the temperature and pressure at the second end of the water-cooled heat exchanger.

[0057] Specifically, the subcooling degree at the second end of the water-cooled heat exchanger is the difference between the saturation temperature corresponding to the pressure at the second end of the water-cooled heat exchanger and the temperature at the second end of the water-cooled heat exchanger.

[0058] Step 230: Determine the overheat degree of the first end of the battery pack according to the temperature and pressure of the first end of the battery pack.

[0059] Specifically, the overheat degree of the first end of the battery pack is the difference between the temperature of the first end of the battery pack and the saturation temperature corresponding to the pressure of the first end of the battery pack.

[0060] Step 240: Determine a superheat difference between the first-end superheat and the target superheat according to the first-end superheat and the target superheat, and perform PID control on the superheat difference to obtain a first opening of the first electronic expansion valve.

[0061] The value obtained by performing proportional-integral-differential calculation on the superheat difference is used as the first opening degree of the first electronic expansion valve.

[0062] Step 250: Determine a subcooling difference between the second end subcooling and the target subcooling according to the second end subcooling and the target subcooling, and perform PID control on the subcooling difference to obtain a second opening of the first electronic expansion valve.

[0063] Step 260: If the first opening is greater than the second opening, the first opening is used as the target opening.

[0064] Step 270: If the first opening is smaller than the second opening, the second opening is used as the target opening.

[0065] The target opening is the larger of the first opening and the second opening. In addition, if the first opening is equal to the second opening, the first opening or the second opening is used as the target opening. Figure 2The refrigerant circuit also includes a second electronic expansion valve 62, a third electronic expansion valve 63, a fourth electronic expansion valve 64, a first solenoid valve 81, a second solenoid valve 82, a third solenoid valve 83 and a fourth solenoid valve 84. The second electronic expansion valve 62 is located in a pipeline connected to the inlet of the evaporator 30 and is close to the inlet of the evaporator 30. The third electronic expansion valve 63 is located in a pipeline connected to the outlet of the condenser 20 and is close to the outlet of the condenser 20. The fourth electronic expansion valve 64 is located in a pipeline connected to the first end of the battery pack 70 and the inlet of the gas-liquid separator 50. The first The solenoid valve 81 is located in the pipeline connecting the outlet of the compressor 10 and the first end of the water-cooled heat exchanger 40. The second solenoid valve 82 is located in the pipeline connecting the first end of the battery pack 70 and the inlet of the condenser 20. The third solenoid valve 83 is located in the pipeline connecting the outlet of the evaporator 30 and the first end of the water-cooled heat exchanger 40. The fourth solenoid valve 84 is located in the pipeline connecting the first end of the battery pack 70 and the inlet of the gas-liquid separator 50. A blower 31 is provided on the side of the evaporator 30 away from the condenser 20. Each solenoid valve and each electronic expansion valve is electrically connected to the controller. The water circuit includes an armature assembly 201, an electronic water pump 202, a radiator 203, and a cooling fan 204. The third end of the water-cooled heat exchanger 40, the armature assembly 201, the electronic water pump 202, the radiator 203, and the fourth end of the water-cooled heat exchanger 40 are connected in sequence. The cooling fan 204 is located on one side of the radiator 203 and is electrically connected to the controller. When a fault occurs in the thermal management system, the control logic for the compressor and cooling fan is added, and the controller controls the compressor and cooling fan. The logic jump time of the compressor and cooling fan is a calibration value of 4. If the time is too long, the temperature control of the first end of the battery pack will be poor. If the time is too short, frequent switching will easily lead to unstable system pressure. The range of calibration value 4 is 2-5 minutes. Calibration value 5: Set according to actual conditions, indicating that the fan is close to the maximum speed, that is, the preset speed threshold. Calibration value 6: System high-pressure protection point, which is related to system factors such as refrigerant type, compressor type, and pipeline pressure resistance.

[0066] For example, Figure 4 This is a schematic diagram of the structure of a thermal management system in single battery cooling mode provided by the second embodiment of the present invention. Figure 4 In the single battery cooling mode, the refrigerant flow direction of the refrigerant circuit is as follows: Figure 4In the direction of the middle arrow, the refrigerant enters the gas-liquid separator 50 and enters the compressor 10, where it is compressed into a high-temperature, high-pressure gas. The high-temperature, high-pressure gas then flows out of the water-cooled heat exchanger 40 as a liquid refrigerant. The liquid refrigerant is throttled and expanded by the first electronic expansion valve 61 into a low-temperature, low-pressure refrigerant. The low-temperature, low-pressure refrigerant evaporates and exchanges heat in the battery pack 70, transforming into a gas or gas-liquid mixed state. It then enters the gas-liquid separator 50 and enters the next cycle. Furthermore, in this mode, the first solenoid valve 81, the fourth solenoid valve 84, and the fourth electronic expansion valve 64 are all open, while the second solenoid valve 82, the third solenoid valve 83, the second electronic expansion valve 62, and the third electronic expansion valve 63 are all closed. When the overheat degree of the first end of the battery pack 70 is greater than the preset overheat threshold, and the first electronic expansion valve 61 fails or the opening degree of the first electronic expansion valve 61 reaches the preset opening threshold, the speed of the cooling fan 204 is controlled to increase; when the speed of the cooling fan 204 increases to the preset speed threshold, the speed of the compressor 10 is controlled to decrease, and the compressor 10 stops after the speed reaches the minimum allowable speed.

[0067] For example, Figure 5 This is a schematic diagram of the structure of a thermal management system in a battery refrigeration compartment in heating mode according to the second embodiment of the present invention. Figure 5 In the battery cooling and cabin heating mode (when the thermal management system is applied to new energy vehicles, cabin heating refers to the passenger compartment heating of new energy vehicles), the refrigerant flow direction of the refrigerant circuit is as follows: Figure 5 In the direction of the middle arrow, the refrigerant enters the gas-liquid separator 50 and then enters the compressor 10, where it is compressed into a high-temperature, high-pressure gas. The high-temperature, high-pressure gas then flows out of the water-cooled heat exchanger 40 and the condenser 20, both exiting as liquid refrigerant. The liquid refrigerant then undergoes throttling and expansion through the first electronic expansion valve 61, transforming into a low-temperature, low-pressure refrigerant. The low-temperature, low-pressure refrigerant evaporates and exchanges heat in the battery pack 70, transforming into a gas or a gas-liquid mixture. It then enters the gas-liquid separator 50 and enters the next cycle. In this mode, the first solenoid valve 81, the fourth solenoid valve 84, the third electronic expansion valve 63, and the fourth electronic expansion valve 64 are all open, while the second solenoid valve 82, the third solenoid valve 83, and the second electronic expansion valve 62 are all closed. When the superheat at the first end of the battery pack 70 exceeds a preset superheat threshold, and the first electronic expansion valve 61 fails or its opening reaches a preset threshold, the speed of the compressor 10 is controlled to decrease, and the compressor 10 stops when it reaches the minimum allowable speed. In order to alleviate the problem that the expansion valve in the system is stuck in a large opening position, resulting in the refrigerant at the battery inlet not being throttled and reduced in pressure, and the impact of the battery inlet temperature being too high on the battery, the control logic of the third electronic expansion valve 63 is added, and the opening of the third electronic expansion valve 63 is equal to the opening of the first electronic expansion valve 61.

[0068] Furthermore, when the thermal management system switches between different modes, the controller controls the working state of the compressor and the on / off state of each solenoid valve and each electronic expansion valve. For example, when the thermal management system switches from the battery cooling mode to the battery heating mode, the controller controls the compressor to stop, and controls the opening according to the pressure difference before and after the valve of each solenoid valve and each electronic expansion valve. The larger the pressure difference, the smaller the opening, and the smaller the pressure difference, the larger the opening, so as to balance the high and low pressures. When the high and low pressures are balanced, each solenoid valve and electronic expansion valve is controlled to switch to its respective target state. Then, each solenoid valve and electronic expansion valve is controlled to switch to the state corresponding to the system shutdown mode. When the battery issues a heating demand, the opening of each solenoid valve and electronic expansion valve is controlled to reach its respective target opening, and the compressor and electronic expansion valve PID automatic control are turned on to enter the battery heating mode. Among them, the high and low pressures are respectively controlled by Figure 4 The sensors PT1 and PT2 shown in the figure collect the data. If the high and low pressure difference is less than 300kpa (calibration value 20), the high and low pressures are balanced. Calibration value 20 is the judgment condition for the high and low pressure balance state of the system. If it is too large, directly switching the solenoid valve will produce abnormal noise. The initial value is 300kpa. The pressure difference before and after each valve is collected by the sensors at the corresponding position. For example, the pressure difference before and after the fourth electronic expansion valve is collected by sensors PT1 and PT4. Calibration value 23: The pressure drop when the valve has basically no throttling and pressure reduction effect, preferably 50kpa. Calibration value 24: In the single battery cooling mode or the battery refrigeration cabin heating mode, the target temperature at the second end of the battery pack cannot deviate too much from the target evaporation temperature, preferably 5°C.

[0069] For example, Figure 6 This is a schematic diagram of the opening and pressure difference provided by the second embodiment of the present invention. Figure 6 The opening calibration value of the fourth electronic expansion valve decreases as the pressure difference between the front and rear of the valve increases. The opening calibration value of each electronic expansion valve is the target opening size. Figure 5 The trend shown is the same. The opening calibration value affects the speed of pressure balancing before and after the valve. The opening adjustment speed should be slow at first and then fast to achieve pressure balance as quickly as possible without generating abnormal noise. The control process for the thermal management system to switch from battery heating mode to battery cooling mode is similar to the control process for switching from battery cooling mode to battery heating mode described above and will not be repeated here.

[0070] It should be noted that the specific size of each preset threshold in this embodiment can be determined according to actual control requirements and is not limited here.

[0071] The battery pack temperature control method of the thermal management system provided in this embodiment controls the opening of the first electronic expansion valve to control the flow of refrigerant flowing through the battery pack through the first electronic expansion valve, thereby controlling the inlet supercooling and outlet superheating of the battery pack, preventing the inlet supercooling of the battery pack from being too large or the outlet superheating from being too large, thereby preventing the inlet and outlet temperature difference of the battery pack from being too large.

[0072] Example 3

[0073] Figure 7 This is a block diagram of a battery pack temperature control device for a thermal management system provided by the third embodiment of the present invention. The device is integrated into the controller of the thermal management system. The specific structure of the thermal management system is as follows: Figure 2 and Figure 4 As shown, the specific description can refer to the above embodiment, which will not be repeated here. Figure 7 The device includes a parameter acquisition module 310, an opening determination module 320, and a temperature control module 330. The parameter acquisition module 310 is used to acquire the temperature and pressure at the second end of the water-cooled heat exchanger and the temperature and pressure at the first end of the battery pack. The opening determination module 320 is used to determine the first and second openings of the first electronic expansion valve based on the temperature and pressure at the second end of the water-cooled heat exchanger and the temperature and pressure at the first end of the battery pack. The temperature control module 330 is used to determine the target opening of the first electronic expansion valve based on the first and second openings to control the temperature of the battery pack.

[0074] Based on the above embodiment, the opening determination module 320 includes: a subcooling determination unit, a superheat determination unit and an opening determination unit; wherein the subcooling determination unit is used to determine the subcooling of the second end of the water-cooled heat exchanger according to the second end temperature and pressure of the water-cooled heat exchanger; the superheat determination unit is used to determine the overheat of the first end of the battery pack according to the first end temperature and pressure of the battery pack; the opening determination unit is used to determine the first opening and the second opening of the first electronic expansion valve according to the second end subcooling, the first end superheat, the target superheat and the target subcooling.

[0075] In one embodiment, the opening determination unit includes a first opening determination subunit and a second opening determination subunit; wherein the first opening determination subunit is used to determine the superheat difference between the first end superheat and the target superheat based on the first end superheat and the target superheat, and perform PID control on the superheat difference to obtain the first opening of the first electronic expansion valve; the second opening determination subunit is used to determine the subcooling difference between the second end subcooling and the target subcooling based on the second end subcooling and the target subcooling, and perform PID control on the subcooling difference to obtain the second opening of the first electronic expansion valve.

[0076] Optionally, the temperature control module 330 is specifically configured to use the first opening degree as the target opening degree if the first opening degree is greater than the second opening degree; and use the second opening degree as the target opening degree if the first opening degree is less than the second opening degree.

[0077] Preferably, the water circuit includes an armature assembly, an electronic water pump, a radiator and a cooling fan, the third end of the water-cooled heat exchanger, the armature assembly, the electronic water pump and the radiator are connected in sequence, and the cooling fan is located on one side of the radiator; the cooling fan is electrically connected to the controller; the above-mentioned device also includes a speed control module, which is used to control the speed of the cooling fan to increase after the temperature control module 330 determines the target opening of the first electronic expansion valve, when the overheating degree of the first end of the battery pack is greater than the preset overheating threshold, and the first electronic expansion valve fails or the opening of the first electronic expansion valve reaches the preset opening threshold; when the speed of the cooling fan increases to the preset speed threshold, the speed of the compressor is controlled to decrease.

[0078] Preferably, the refrigerant circuit further includes a second electronic expansion valve, a third electronic expansion valve, a fourth electronic expansion valve, a first solenoid valve, a second solenoid valve, a third solenoid valve and a fourth solenoid valve. The second electronic expansion valve is located in a pipeline connected to the inlet of the evaporator and is close to the inlet of the evaporator. The third electronic expansion valve is located in a pipeline connected to the outlet of the condenser and is close to the outlet of the condenser. The fourth electronic expansion valve is located in a pipeline connected to the first end of the battery pack and the inlet of the gas-liquid separator. The first solenoid valve is located in a pipeline connected to the outlet of the compressor and the first end of the water-cooled heat exchanger. The second solenoid valve is located in a pipeline connected to the first end of the battery pack and the cooler. The third solenoid valve is located in a pipeline connected to the inlet of the condenser, the third solenoid valve is located in a pipeline connected to the outlet of the evaporator and the first end of the water-cooled heat exchanger, and the fourth solenoid valve is located in a pipeline connected to the first end of the battery pack and the inlet of the gas-liquid separator; each solenoid valve and each electronic expansion valve is electrically connected to the controller; the above-mentioned device also includes a state control module, which is used to control the first solenoid valve, the fourth solenoid valve, and the fourth electronic expansion valve to be turned on after the temperature control module 330 determines the target opening of the first electronic expansion valve, and to control the second solenoid valve, the third solenoid valve, the second electronic expansion valve, and the third electronic expansion valve to be turned off.

[0079] The battery pack temperature control device of the thermal management system provided in this embodiment and the battery pack temperature control method of the thermal management system provided in any embodiment of the present invention belong to the same inventive concept and have corresponding beneficial effects. For technical details not detailed in this embodiment, please refer to the battery pack temperature control method of the thermal management system provided in any embodiment of the present invention.

[0080] Note that the above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will appreciate that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, combinations, and substitutions are possible for those skilled in the art without departing from the scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments and may include many other equivalent embodiments without departing from the scope of the present invention. The scope of the present invention is determined by the scope of the appended claims.

Claims

1. A battery pack temperature control method for a thermal management system, characterized in that: The thermal management system includes a refrigerant circuit, a water circuit and a controller. The refrigerant circuit includes a compressor, a condenser, an evaporator, a water-cooled heat exchanger, a gas-liquid separator, a first electronic expansion valve and a battery pack. The outlet of the compressor is in communication with the first end of the water-cooled heat exchanger, the inlet of the condenser and the first end of the battery pack. The second end of the water-cooled heat exchanger is in communication with the outlet of the condenser. The outlet of the condenser is in communication with the inlet of the evaporator and the second end of the battery pack. The outlet of the evaporator is in communication with the first end of the battery pack and the first end of the water-cooled heat exchanger. The first end of the battery pack is in communication with the inlet of the gas-liquid separator. The outlet of the gas-liquid separator is in communication with the inlet of the compressor. The first electronic expansion valve is located in a pipeline connected to the second end of the battery pack and is close to the second end of the battery pack. The third and fourth ends of the water-cooled heat exchanger are in communication with the water circuit. The compressor and the first electronic expansion valve are both electrically connected to the controller. The control method is executed by the controller. The control method includes: Acquiring the temperature and pressure of the second end of the water-cooled heat exchanger and the temperature and pressure of the first end of the battery pack; the current operating mode of the thermal management system is a single battery cooling mode or a battery cooling cabin heating mode; determining a first opening degree and a second opening degree of the first electronic expansion valve according to the temperature and pressure of the second end of the water-cooled heat exchanger and the temperature and pressure of the first end of the battery pack; determining a target opening of the first electronic expansion valve according to the first opening and the second opening to control the temperature of the battery pack; The determining the first opening and the second opening of the first electronic expansion valve according to the temperature and pressure of the second end of the water-cooled heat exchanger and the temperature and pressure of the first end of the battery pack includes: determining a subcooling degree at the second end of the water-cooled heat exchanger according to the temperature and pressure at the second end of the water-cooled heat exchanger; determining an overheat degree of the first end of the battery pack according to the temperature and pressure of the first end of the battery pack; A first opening degree and a second opening degree of the first electronic expansion valve are determined according to the second-end subcooling degree, the first-end superheating degree, a target superheating degree, and a target subcooling degree.

2. The control method according to claim 1, characterized in that: Determining the first opening degree and the second opening degree of the first electronic expansion valve according to the second end subcooling degree, the first end superheating degree, the target superheating degree, and the target subcooling degree includes: determining a superheat difference between the first end superheat and the target superheat according to the first end superheat and the target superheat, and performing PID control on the superheat difference to obtain a first opening of the first electronic expansion valve; A subcooling difference between the second end subcooling degree and the target subcooling degree is determined according to the second end subcooling degree and the target subcooling degree, and a second opening degree of the first electronic expansion valve is obtained by performing PID control on the subcooling difference.

3. The control method according to claim 1, wherein: The determining a target opening of the first electronic expansion valve according to the first opening and the second opening to control the temperature of the battery pack includes: If the first opening is greater than the second opening, the first opening is used as the target opening; If the first opening is smaller than the second opening, the second opening is used as the target opening.

4. The control method according to claim 1, wherein: The water circuit includes an armature assembly, an electronic water pump, a radiator and a cooling fan. The third end of the water-cooled heat exchanger, the armature assembly, the electronic water pump and the radiator are connected in sequence. The cooling fan is located on one side of the radiator. The cooling fan is electrically connected to the controller. After determining the target opening of the first electronic expansion valve, the method includes: When the overheat degree of the first end of the battery pack is greater than a preset overheat threshold, and the first electronic expansion valve fails or the opening degree of the first electronic expansion valve reaches a preset opening degree threshold, controlling the speed of the cooling fan to increase; When the rotation speed of the cooling fan increases to a preset rotation speed threshold, the rotation speed of the compressor is controlled to decrease.

5. The control method according to claim 1, characterized in that: The refrigerant circuit further includes a second electronic expansion valve, a third electronic expansion valve, a fourth electronic expansion valve, a first solenoid valve, a second solenoid valve, a third solenoid valve and a fourth solenoid valve, the second electronic expansion valve being located in a pipeline connected to the inlet of the evaporator and close to the inlet of the evaporator, the third electronic expansion valve being located in a pipeline connected to the outlet of the condenser and close to the outlet of the condenser, the fourth electronic expansion valve being located in a pipeline connected to the first end of the battery pack and the inlet of the gas-liquid separator, the first solenoid valve being located in a pipeline connected to the outlet of the compressor and the first end of the water-cooled heat exchanger, the second solenoid valve being located in a pipeline connected to the first end of the battery pack and the inlet of the condenser, the third solenoid valve being located in a pipeline connected to the outlet of the evaporator and the first end of the water-cooled heat exchanger, and the fourth solenoid valve being located in a pipeline connected to the first end of the battery pack and the inlet of the gas-liquid separator; Each solenoid valve and each electronic expansion valve is electrically connected to the controller; After determining the target opening of the first electronic expansion valve, the method includes: The first solenoid valve, the fourth solenoid valve, and the fourth electronic expansion valve are all controlled to be turned on, and the second solenoid valve, the third solenoid valve, the second electronic expansion valve, and the third electronic expansion valve are all controlled to be turned off.

6. A battery pack temperature control device for a thermal management system, characterized in that: The thermal management system includes a refrigerant circuit, a water circuit and a controller. The refrigerant circuit includes a compressor, a condenser, an evaporator, a water-cooled heat exchanger, a gas-liquid separator, a first electronic expansion valve and a battery pack; the outlet of the compressor is connected to the first end of the water-cooled heat exchanger, the inlet of the condenser and the first end of the battery pack, the second end of the water-cooled heat exchanger is connected to the outlet of the condenser, the outlet of the condenser is connected to the inlet of the evaporator and the second end of the battery pack, the outlet of the evaporator is connected to the first end of the battery pack and the first end of the water-cooled heat exchanger, the first end of the battery pack is connected to the inlet of the gas-liquid separator, the outlet of the gas-liquid separator is connected to the inlet of the compressor, the first electronic expansion valve is located in a pipeline connected to the second end of the battery pack and is close to the second end of the battery pack, the third and fourth ends of the water-cooled heat exchanger are connected to the water circuit; the compressor and the first electronic expansion valve are both electrically connected to the controller; the control device includes: a parameter acquisition module, configured to acquire the temperature and pressure at the second end of the water-cooled heat exchanger and the temperature and pressure at the first end of the battery pack; an opening degree determining module, configured to determine a first opening degree and a second opening degree of the first electronic expansion valve according to the temperature and pressure at the second end of the water-cooled heat exchanger and the temperature and pressure at the first end of the battery pack; a temperature control module, configured to determine a target opening of the first electronic expansion valve according to the first opening and the second opening, so as to control the temperature of the battery pack; The opening determination module includes: a subcooling degree determining unit, configured to determine the subcooling degree of the second end of the water-cooled heat exchanger according to the temperature and pressure of the second end of the water-cooled heat exchanger; an overheat determination unit, configured to determine an overheat degree of the first end of the battery pack based on the temperature and pressure of the first end of the battery pack; The opening degree determining unit is configured to determine a first opening degree and a second opening degree of the first electronic expansion valve according to the second end subcooling degree, the first end superheating degree, a target superheating degree, and a target subcooling degree.

7. A thermal management system, characterized in that: include: A refrigerant circuit, a water circuit and a controller, the refrigerant circuit includes a compressor, a condenser, an evaporator, a water-cooled heat exchanger, a gas-liquid separator, a first electronic expansion valve and a battery pack; the outlet of the compressor is connected to the first end of the water-cooled heat exchanger, the inlet of the condenser and the first end of the battery pack, the second end of the water-cooled heat exchanger is connected to the outlet of the condenser, the outlet of the condenser is connected to the inlet of the evaporator and the second end of the battery pack, the outlet of the evaporator is connected to the first end of the battery pack and the first end of the water-cooled heat exchanger, the first end of the battery pack is connected to the inlet of the gas-liquid separator, the outlet of the gas-liquid separator is connected to the inlet of the compressor, the first electronic expansion valve is located in the pipeline connected to the second end of the battery pack and is close to the second end of the battery pack, the third and fourth ends of the water-cooled heat exchanger are connected to the water circuit; the compressor and the first electronic expansion valve are both electrically connected to the controller, and the control device as claimed in claim 6 is integrated into the controller.

8. The thermal management system according to claim 7, characterized in that: The refrigerant circuit also includes a second electronic expansion valve, a third electronic expansion valve, a fourth electronic expansion valve, a first solenoid valve, a second solenoid valve, a third solenoid valve and a fourth solenoid valve. The second electronic expansion valve is located in a pipeline connected to the inlet of the evaporator and is close to the inlet of the evaporator. The third electronic expansion valve is located in a pipeline connected to the outlet of the condenser and is close to the outlet of the condenser. The fourth electronic expansion valve is located in a pipeline connected to the first end of the battery pack and the inlet of the gas-liquid separator. The first solenoid valve is located in a pipeline connected to the outlet of the compressor and the first end of the water-cooled heat exchanger. The second solenoid valve is located in a pipeline connected to the first end of the battery pack and the inlet of the condenser. The third solenoid valve is located in a pipeline connected to the outlet of the evaporator and the first end of the water-cooled heat exchanger. The fourth solenoid valve is located in a pipeline connected to the first end of the battery pack and the inlet of the gas-liquid separator. Each solenoid valve and each electronic expansion valve is electrically connected to the controller.

9. The thermal management system according to claim 7, wherein: The water circuit includes an armature assembly, an electronic water pump, a radiator and a cooling fan. The third end of the water-cooled heat exchanger, the armature assembly, the electronic water pump, the radiator and the fourth end of the water-cooled heat exchanger are connected in sequence. The cooling fan is located on one side of the radiator; the cooling fan is electrically connected to the controller.

Images