A control method

Abstract

A control method applicable to vehicle thermal management systems where both the battery pack and air conditioning require heating includes: PTC heater heating; setting an initial flow rate of the working medium on the air conditioning side; adjusting the flow rate of the working medium on the air conditioning side according to the relationship between the outlet temperature of the PTC heater and the required temperature of the working medium on the air conditioning side by adjusting a flow control valve according to a set flow rate increase / decrease; and further adjusting the flow rate of the working medium on the air conditioning side according to the relationship between the actual temperature of the battery pack and the target temperature of the battery pack. This technical solution first gradually adjusts the flow rates of the working medium on the air conditioning side and the battery pack side by monitoring the outlet temperature of the PTC heater and the set temperature of the air conditioning, prioritizing heating of the air conditioning side, and then adjusting the flow rate according to the actual temperature of the battery pack and the target temperature of the battery pack, which is beneficial for dynamically and rationally distributing the heat between the battery pack and the air conditioning side.

Description

Technical Field

[0001] This invention relates to the field of electronic control, and more specifically to a control method for a vehicle thermal management system. Background Technology

[0002] The vehicle thermal management system includes an air conditioning system and a battery thermal management system. The air conditioning system includes a heating mode, which is activated in low-temperature environments. The thermal management system uses a PTC heater to provide a heat source for the battery pack and passenger compartment. The PTC heater is connected to heat exchange pipelines on both the battery pack and passenger compartment sides. Heat distribution between the battery pack and passenger compartment sides can be adjusted by regulating flow control valves. However, in very low-temperature environments, such as -20°C, both the battery pack and passenger compartment have significant heat demands. How to dynamically distribute the heat between the battery pack and passenger compartment sides is a technical problem that needs improvement. Summary of the Invention

[0003] The purpose of this invention is to provide a control method that facilitates the dynamic distribution of heat between the battery pack and the passenger compartment when both require heating.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A control method is provided for a vehicle thermal management system. The thermal management system includes a controller, a flow control valve, a PTC heater, a battery pack heat exchanger, and an air conditioning unit. The outlet of the PTC heater is connected to the inlet of the flow control valve. One outlet of the flow control valve is connected to the heat exchange pipeline of the battery pack heat exchanger, which is capable of exchanging heat with the battery pack. The other outlet of the flow control valve is connected to the heat exchange pipeline of the air conditioning unit. The controller is electrically / signally connected to the flow control valve and can control the opening of the flow control valve to adjust the flow rate of the working medium flowing to the air conditioning unit and the battery pack heat exchanger. The thermal management system includes an air conditioning system, which includes a heating mode. When the air conditioning system is in heating mode and the battery pack requires heating, the PTC heater is controlled to heat. The control method includes:

[0006] S1. Adjust the initial flow rate of the working medium flowing to the air conditioning unit side and the battery pack heat exchanger side using the flow control valve;

[0007] S2. Determine whether the temperature of the working medium at the outlet of the PTC heater is greater than or equal to the required temperature of the working medium on the air conditioning unit side. If yes, proceed to step S3. If no, control the flow control valve to increase the flow rate of the working medium flowing to the air conditioning unit side by a first set increment, and keep the increased flow rate at a first set time interval unchanged.

[0008] S3. Determine whether the actual temperature of the battery pack is greater than or equal to the target temperature value of the battery pack. If yes, adjust the flow control valve to increase the flow rate of the working medium flowing to the air conditioning unit side by a second set increment every second set time interval until the flow rate flowing to the air conditioning unit side is maximum. If no, repeat step S2.

[0009] This technical solution first monitors the relationship between the outlet working medium temperature of the PTC heater and the required working medium temperature on the air conditioning unit side. When the outlet working medium temperature of the PTC heater does not reach the required working medium temperature on the air conditioning unit side, the flow rate of the working medium on the air conditioning unit side is increased by a first set increment and maintained for a first set time interval. Then, the flow rate is adjusted again based on the actual temperature of the battery pack and the target temperature of the battery pack. If the actual temperature of the battery pack has reached the target temperature, the flow rate of the working medium flowing to the air conditioning unit side is increased by a second set increment every second set time interval. If it has not reached the target temperature, the relationship between the outlet working medium temperature of the PTC heater and the required working medium temperature on the air conditioning unit side is reassessed. In the initial stage of heating, the heat exchange efficiency between the battery pack and the working medium is low, and the battery pack temperature rises slowly. Meanwhile, the temperature inside the vehicle is low and needs to be heated as soon as possible. Therefore, in the initial stage, heating of the air conditioning unit side, i.e., the passenger compartment, is prioritized, followed by heating of the battery pack side. This is beneficial for dynamically distributing the heat between the battery pack and the passenger compartment side. Attached Figure Description

[0010] Figure 1 This is a schematic block diagram showing the connection of one implementation of a vehicle thermal management system.

[0011] Figure 2 This is a schematic diagram of a control flow for a thermal management system.

[0012] Figure 3 yes Figure 2 A schematic diagram of the control flow for step S1;

[0013] Figure 4 This is a schematic diagram of the second control flow of the thermal management system control method;

[0014] Figure 5 This is a schematic diagram of the third control flow of the thermal management system control method;

[0015] Figure 6 Is with Figure 2 The corresponding control flow diagram of the thermal management system;

[0016] Figure 7 This is another control flow diagram of the control method for the thermal management system;

[0017] Figure 8 This is a schematic diagram of the control process of the thermal management system in defrosting mode. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0019] The vehicle thermal management system includes an air conditioning system and a battery thermal management system. The air conditioning system includes multiple modes such as heating, cooling, and defrosting. This technical solution mainly relates to the heating mode. See also Figure 1 , Figure 1 This is a schematic block diagram illustrating one implementation of a vehicle thermal management system. The vehicle thermal management system includes a controller 100, a flow control valve 2, a PTC heater 3, a water pump 4, a battery pack 5, a battery pack heat exchanger 6, and an air conditioning unit 7. The air conditioning unit contains a blower 71 and a heater core 72. The blower 71 blows in air, and the heater core 72 heats the air to raise the temperature of the passenger compartment. The inlet of the PTC heater 3 is connected to the water pump 4 to heat the working medium pumped in from the water pump 4. In this embodiment, the working medium is mainly water. The outlet of PTC heater 3 is connected to the inlet of flow control valve 2. Flow control valve 2 has one inlet and two outlets, which divides the heated working medium into two paths. One outlet of flow control valve 2 is connected to the heat exchange pipeline of battery pack heat exchanger 6, i.e., connected to battery pack heat exchanger 6. Heat exchange between battery pack heat exchanger 6 and battery pack 5 is achieved through heat exchange, thus heating battery pack 5. The other outlet of flow control valve 2 is connected to the heat exchange pipeline of air conditioning unit, i.e., connected to heater core 72. Heat heater core 72 is used to heat the passenger compartment. The outlets of heater core 72 and battery pack heat exchanger 6 are respectively connected to the inlet of water pump 4. The working medium flowing out of heater core 72 and battery pack heat exchanger 6 after heat exchange is recycled by water pump 4 and re-enters PTC heater 3 for heating, forming a loop. Controller 100 is electrically / signally connected to flow control valve 2. Controller 100 can control the opening ratio of the flow control valve, controlling the flow rate in two paths: the air conditioning unit side (hereinafter referred to as the air conditioning side) and the battery pack heat exchanger side (hereinafter referred to as the battery pack side), thereby controlling the heat distribution between the air conditioning unit and the battery pack, i.e., controlling the heat distribution between the passenger compartment and the battery pack. In addition, controller 100 is also electrically / signally connected to the air conditioning unit, capable of acquiring signals from the air conditioning unit, such as the working medium temperature requirement value T0 on the air conditioning unit side, and issuing control commands to the air conditioning unit; controller 100 is also electrically / signally connected to the PTC heater, capable of acquiring the working medium temperature at the PTC heater outlet and controlling the PTC heater to operate; controller 100 is also electrically / signally connected to the battery pack, capable of acquiring the actual temperature of the battery pack and controlling the battery pack to operate.

[0020] Figure 2This is a first implementation of the control method. This control method is suitable for use in cold environments, such as -30℃ to -10℃, where the air conditioning system is in heating mode and the battery pack also requires heating. The PTC heater provides heating, and the control method includes:

[0021] S1. Adjust the initial flow rate of the working medium flowing to the air conditioning unit side and the battery pack heat exchanger side using the flow control valve;

[0022] S2. Determine whether the temperature Ta of the working medium at the outlet of the PTC heater is greater than or equal to the required temperature T0 of the working medium on the air conditioning unit side. If yes, proceed to step S3. If no, control the flow control valve to increase the flow rate of the working medium flowing to the air conditioning unit side by a first set increment L1, and keep the increased flow rate at a first set time interval t1 unchanged.

[0023] S3. Determine whether the actual temperature Tb of the battery pack is greater than or equal to the target temperature T1 of the battery pack. If yes, adjust the flow control valve to increase the flow rate of the working medium flowing to the air conditioning unit side by a second set increment L3 every second set time interval t2 until the flow rate to the air conditioning unit side is maximum. If no, repeat step S2.

[0024] The flow rate of the working medium exiting the PTC heater is the total flow rate. This total flow rate is divided into two streams by a flow control valve: one flowing to the air conditioning unit and the other to the battery pack. The sum of the flows to the air conditioning unit and the battery pack equals the total flow rate. With the total flow rate constant, an increase in the flow rate to the air conditioning unit results in a decrease in the flow rate to the battery pack, and vice versa. Therefore, by adjusting the flow control valve, the flow rate of the working medium to the air conditioning unit and the battery pack heat exchanger can be distributed. The initial flow rate of the working medium on the air conditioning unit side in step S1 is denoted as L0.

[0025] Step S2 adjusts the flow control valve appropriately based on the relationship between the outlet working medium temperature Ta of the PTC heater and the required working medium temperature T0 on the air conditioning unit side to adjust the heat distribution. When the PTC heater is not heating, the temperature of the working medium inside the PTC heater is basically the same as the working medium temperature in the air conditioning unit's heating core and battery pack heat exchanger. When the PTC heater is started, the working medium inside the PTC heater is gradually heated, and the working medium temperature inside the PTC heater is higher than the working medium temperature in the air conditioning unit's heating core and battery pack heat exchanger. As the heating time increases, the outlet working medium temperature Ta of the PTC heater gradually increases. The heated working medium flows to the heating core and battery pack heat exchanger after passing through the flow control valve, heating the air conditioning unit and battery pack. When the outlet temperature Ta of the PTC heater has not yet reached the required working medium temperature T0 on the air conditioning unit side, heat is preferentially distributed to the air conditioning side. The flow control valve is adjusted to increase the flow rate on the air conditioning side by a first set increment L2. After the increase, the flow rate on the air conditioning side also remains at a first set time interval t1. The increased flow rate on the air conditioning side is less than or equal to the maximum preset flow rate Lmax. The first set increment L2 and the maximum preset flow rate Lmax are set values ​​or set ranges that can be adjusted according to different situations. In this text, the reduced flow rate on the air conditioning side must be greater than or equal to the minimum preset flow rate Lmin. If the flow rate on the air conditioning side is less than the minimum preset flow rate Lmin after the first set reduction L1, then the flow rate on the air conditioning side can be reduced to the minimum preset flow rate Lmin. The same applies to increasing the flow rate on the air conditioning side to be less than or equal to the maximum preset flow rate Lmax.

[0026] When both the air conditioning unit and the battery pack require heating, the PTC heater heats the working medium pumped in by the water pump. The heated working medium is then split by a flow control valve to provide heat to both the air conditioning unit and the battery pack. Because the battery pack's heat exchange efficiency with the working medium is low at the beginning of heating, its temperature rises slowly, resulting in low heat demand during this initial phase. However, at the beginning of heating, the passenger compartment has not reached the set temperature, and the interior temperature is low, requiring rapid heating and thus high heat demand. Therefore, step S2, which increases the flow rate on the battery side only after the PTC heater's outlet temperature reaches a certain value (in this embodiment, the working medium temperature demand value T0 on the air conditioning unit side), improves heat utilization efficiency.

[0027] Based on the relationship between the PTC heater outlet temperature Ta and the required working medium temperature T0 on the air conditioning unit side, the flow control valve is adjusted according to whether the actual battery pack temperature Tb reaches the target battery pack temperature T1. If the actual battery pack temperature has reached the target temperature, it indicates that the heat on the battery pack side is sufficient, and excess heat can be allocated to the air conditioning side. The flow control valve is adjusted so that the flow rate to the air conditioning side increases by a second set increment L3 every certain period of time (second set time interval t2), causing the working medium flow rate to the air conditioning side to increase slowly. This avoids sudden increases in air conditioning temperature, reduces temperature fluctuations in the passenger compartment, and makes the vehicle interior temperature more stable. The second set increment L3 and the second set time interval t2 are set values ​​or set ranges that can be adjusted according to different situations. Here, due to the limitation of the flow control valve, the air conditioning flow rate can only be increased to the maximum flow rate of all the working medium flowing to the air conditioning side. The maximum flow rate here is different from the maximum preset flow rate Lmax mentioned above. The maximum flow rate is the flow rate when the outlet of the flow control valve connected to the air conditioning heat exchange pipeline is fully open. The maximum preset flow rate Lmax is a preset value or range that can be adjusted. Of course, the maximum preset flow rate Lmax can be equal to or less than the maximum flow rate value.

[0028] If the actual temperature of the battery pack has not yet reached the target temperature, the heat exchange between the working medium and the battery pack after a period of time may cause the outlet temperature Ta of the PTC heater to decrease, and the heat on the air conditioning unit side may not be sufficient. Therefore, it is necessary to re-determine whether the outlet temperature Ta of the PTC heater has reached the required temperature T0 of the working medium on the air conditioning unit side, and repeat step S2.

[0029] In cold conditions, due to the limited power supply capacity of the PTC heater and battery, and the rapid heat loss, even with the PTC heater at maximum power, the thermal management system may struggle to simultaneously meet the heating demands of both the air conditioning and battery pack. This could result in the passenger cabin failing to reach the target temperature for an extended period. This technical solution addresses this by setting an initial flow rate L0 for the working medium on the air conditioning unit side during the initial heating phase of the PTC heater. Since the heating demand is high, the PTC heater power is already at maximum. A temperature sensor is typically installed at the PTC heater outlet. This solution uses the outlet working medium temperature Ta as the primary monitoring indicator. Once the PTC heater outlet temperature Ta reaches the required working medium temperature T0 on the air conditioning unit side, the flow control valve is adjusted based on whether the actual battery pack temperature Tb reaches the target battery pack temperature T1. This method simultaneously heats the battery pack and meets the heating requirements of the air conditioning. Once the air conditioning and battery pack meet their target requirements, the PTC heater power can be gradually reduced. It is understandable that if the PTC heater power is sufficiently high, even without dynamic adjustment of the flow control valve opening after the initial opening, the air conditioning and battery pack can reach their target requirements after a period of time.

[0030] like Figure 3 As shown, step S1, adjusting the initial flow rate of the working medium flowing through the flow control valve to the air conditioning unit side and the battery pack heat exchanger side, specifically includes the following steps:

[0031] a. Determine if the battery pack is charging. If yes, proceed to step b; otherwise, proceed to step c.

[0032] b. Determine whether the battery pack temperature is lower than the preset battery pack temperature threshold. If yes, set the initial flow rate of the working medium flowing to the air conditioning unit side as the first initial flow rate. If no, set the initial flow rate of the working medium flowing to the air conditioning unit side as the second initial flow rate. The first initial flow rate is less than the second initial flow rate.

[0033] c. Determine whether the ambient temperature is lower than the preset ambient temperature threshold. If so, set the initial flow rate of the working medium flowing to the air conditioning unit as the third initial flow rate. If not, set the initial flow rate of the working medium flowing to the air conditioning unit as the fourth initial flow rate. The third initial flow rate is greater than the fourth initial flow rate.

[0034] See Figure 3 If the battery pack is charging, the initial flow rate setting mainly considers the influence of the battery pack temperature. In step b, the battery pack temperature threshold can include one or more battery pack temperature thresholds, meaning the relationship between the battery pack temperature and the battery pack temperature threshold can be judged multiple times to make different settings for the initial flow rate. In this embodiment, the battery pack temperature threshold includes a first battery pack temperature threshold and a second battery pack temperature threshold. The first battery pack temperature threshold can be -20℃. If the battery pack temperature is below -20℃, it indicates that the battery pack temperature is very low, and heat distribution can be appropriately biased towards the battery pack; conversely, heat distribution can be appropriately biased towards the air conditioning side. Specifically, when the flow control valve is at its maximum opening, the corresponding flow rate of the working medium flowing to the air conditioning side is at its maximum. If the battery pack temperature is below -20℃, the initial opening of the flow control valve can be set to 72%, and the initial flow rate of the working medium flowing to the air conditioning unit at this opening is the first initial flow rate. If the battery pack temperature is above -20℃, the initial opening of the flow control valve can be greater than 72%, and the initial flow rate of the working medium flowing to the air conditioning unit at this opening is the second initial flow rate. The corresponding first initial flow rate is less than the second initial flow rate. This embodiment also has a second battery pack temperature threshold of -10°C. When the battery pack temperature is higher than -20°C but lower than -10°C, the initial opening of the flow control valve can be set to 84%. When the battery pack temperature is higher than or equal to -10°C, the initial opening of the flow control valve can be set to 90%.

[0035] If the battery pack is not charged, the initial flow rate setting mainly considers the influence of ambient temperature; the lower the ambient temperature, the greater the initial flow rate allocated to the air conditioning unit. Similar to the battery pack temperature threshold, the ambient temperature threshold can also be one or more. In step c of this embodiment, the ambient temperature threshold can be -10℃. When the ambient temperature is below -10℃, the initial opening of the flow control valve can be 97%, and the initial flow rate of the working medium flowing to the air conditioning unit at this opening is the third initial flow rate. When the ambient temperature is greater than or equal to -10℃, the initial opening of the flow control valve can be 92%, and the initial flow rate of the working medium flowing to the air conditioning unit at this opening is the fourth initial flow rate. The third initial flow rate is greater than the fourth initial flow rate. Numerically, the third initial flow rate is greater than the first or second initial flow rate, and the fourth initial flow rate is greater than the first or second initial flow rate. The battery pack temperature threshold, ambient temperature threshold, and the first to fourth initial flow rates can be adjusted according to actual conditions and are not limited to the data given in this embodiment.

[0036] Figure 4 This is a second implementation of the control method. (And...) Figure 2 Compared to the control method shown, in step S2 of this embodiment, it is determined that the temperature of the working medium at the outlet of the PTC heater is greater than or equal to the required temperature of the working medium on the air conditioning unit side. If so, step S20 is included before executing step S3: adjusting the flow control valve to reduce the flow rate of the working medium flowing to the air conditioning unit side by a first set reduction L1, and keeping the reduced flow rate at a first set time interval t1 unchanged.

[0037] When the outlet temperature Ta of the PTC heater reaches the required working medium temperature T0 on the air conditioning unit side, the flow control valve can be adjusted to reduce the flow rate of the working medium to the air conditioning side. The reduction in flow rate is a first set reduction L1. After the reduction, the flow rate on the air conditioning side is maintained at a first set time interval t1. The reduced flow rate on the air conditioning side is greater than or equal to the minimum preset flow rate Lmin, causing the heat on the battery pack side to gradually increase and distributing most of the heat to the battery pack side. The first set reduction L1, the first set time interval t1, and the minimum preset flow rate Lmin are set values ​​or set ranges that can be adjusted according to different situations.

[0038] It is generally recommended that, numerically, the first set reduction L1 be smaller than the first set increase L2 and the second set increase L3, and the first set time interval t1 be larger than the second set time interval t2. This way, when the heat in the passenger compartment decreases, it should be reduced gradually in a small amount to prevent the temperature in the passenger compartment from dropping suddenly and to reduce temperature fluctuations in the passenger compartment. When the heat in the passenger compartment increases, it should be increased more rapidly in a relatively larger amount to increase the temperature in the passenger compartment as quickly as possible and increase the comfort of the passengers.

[0039] Figure 5 This is the third implementation of the control method. (And...) Figure 4Compared to the control method shown, in this embodiment, if the actual temperature of the battery pack is determined not to have reached the target temperature value in step S3, step S20 can be executed for a predetermined time or a predetermined number of times before re-executing step S2. That is, when the actual temperature of the battery pack is not reached, the air conditioning flow rate is reduced by a first preset reduction amount L1. After the reduction, the air conditioning flow rate is maintained at a first preset time interval t1. The battery pack flow rate is then increased and maintained for a period of time or step S20 is repeated a predetermined number of times before step S2 is executed.

[0040] When the flow control valve is at its maximum opening, the flow rate of the working medium flowing to the air conditioning side is at its maximum, and the flow rate of the working medium flowing to the battery pack side is at its minimum. Conversely, when the flow control valve is at its minimum opening, the flow rate of the working medium flowing to the air conditioning side is at its minimum, and the flow rate of the working medium flowing to the battery pack side is at its maximum. Figure 4 The specific execution steps of the control method shown can be found in Figure 6. The control method includes the following steps:

[0041] S21: The initial opening degree of the flow control valve is set to R0;

[0042] S22: Determine whether the outlet temperature Ta of the PTC heater reaches the required working medium temperature T0 on the air conditioning unit side. If yes, decrease the opening of the flow control valve by the first reduction amount R1, and keep the reduced opening at the first set time interval t1 unchanged. The flow control valve opening is reduced to the minimum preset opening Rmin. If no, increase the opening of the flow control valve by the first increase amount R2, and keep the increased opening at the first set time interval t1 unchanged. The flow control valve opening is increased to the maximum preset opening Rmax.

[0043] S23: Determine whether the actual temperature Tb of the battery pack has reached the target temperature value T1 of the battery pack. If yes, increase the opening of the flow control valve every second set time interval t2 by an increment of the second opening increment R3 until the flow control valve is opened to the maximum opening. If no, proceed to step S22.

[0044] In step S22, R1 represents the first reduction in opening degree, corresponding to the first set reduction amount L1. When the flow control valve opening degree decreases by R1, the flow rate on the air conditioning side decreases by L1. The minimum preset opening degree Rmin also corresponds to the minimum preset flow rate Lmin. When the flow control valve opening degree is the minimum preset opening degree Rmin, the flow rate on the air conditioning side is the minimum preset flow rate Lmin. Similarly, R2 represents the first increase in opening degree, corresponding to the first set increase amount L2, and the maximum preset opening degree Rmax also corresponds to the maximum preset flow rate Lmax. In step S24, R3 represents the second increase in opening degree, corresponding to the second set increase amount L3. When the flow control valve is opened to the maximum opening degree, the flow rate on the air conditioning side is the maximum flow rate described above.

[0045] Specifically, the initial opening R0 of the flow control valve can be referenced. Figure 3 The settings are adjusted based on factors such as charging mode, battery pack temperature, and ambient temperature. The required working medium temperature T0 for the air conditioning unit can be 60℃; the opening reduction rate R1 can be set to 3%, with a minimum preset opening rate Rmin of 80%; the opening increase rate R2 is 6%, with a maximum preset opening rate Rmax of 92%; the target battery pack temperature T1 is 20℃; the first set time interval t1 is 5 minutes, the second set time interval t2 is 1 minute, and the opening increase rate R3 is 6%. Of course, the above data is for reference only and can be adjusted according to actual conditions. The first opening reduction rate R1 is smaller than the first opening increase rate R2 and the second opening increase rate R3, and the first set time interval t1 is larger than the second set time interval t2. This ensures that when the passenger compartment heat decreases, it decreases gradually in small increments to prevent sudden drops in passenger compartment temperature and reduce temperature fluctuations. Conversely, when increasing passenger compartment heat, it increases relatively quickly in larger increments to rapidly increase the temperature inside the passenger compartment and improve passenger comfort.

[0046] Figure 6 The control method shown is based on the premise that the air conditioning side flow is the largest when the flow control valve is at its largest opening and the air conditioning side flow is the smallest when the opening is at its smallest opening. If the air conditioning side flow is the smallest when the flow control valve is at its largest opening and the air conditioning side flow is the largest when the opening is at its smallest opening, then the part of the control method that controls the flow control valve opening to decrease is changed to increase the opening, and the part that controls the opening to increase is changed to decrease the opening. Adaptive adjustments can be made, which will not be described in detail here.

[0047] The control methods described above are all for controlling the flow control valve when the air conditioning system is in heating mode and the battery pack requires heating. See also... Figure 7 When the air conditioning system is in heating mode and the battery pack does not require heating, the PTC heater heats the system, and the flow control valve opening is controlled to maximize the flow to the air conditioning side. When neither the battery pack nor the air conditioning unit requires heating, such as in cooling mode, the PTC heater does not start, and the flow control valve maintains its current position. When only the battery pack requires heating, the flow control valve opening is controlled to maximize the flow to the battery pack side.

[0048] See Figure 8The air conditioning system also includes a defrost mode. In defrost mode, the flow control valve is controlled as follows: It determines whether the battery pack is charging. If so, the flow control valve is adjusted to ensure the flow rate of the working medium to the air conditioning unit is always at a first flow rate (e.g., the flow control valve opening is set to 84%). If not, the flow control valve is adjusted to ensure the flow rate of the working medium to the air conditioning unit is always at a second flow rate (e.g., the flow control valve opening is set to 97%), where the first flow rate is less than the second flow rate. If the battery pack is charging, some heat still needs to be allocated to it; if the battery pack is not charging, more heat can be allocated to the air conditioning unit. In this solution, because the defrost mode requires a relatively short time, the flow control valve opening can be set to a fixed value.

[0049] It should be noted that the above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still make modifications or equivalent substitutions to the present invention. All technical solutions and improvements that do not depart from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A control method for use in a vehicle thermal management system, the thermal management system comprising a controller, a flow control valve, a PTC heater, a battery pack heat exchanger, and an air conditioning unit, wherein the outlet of the PTC heater is connected to the inlet of the flow control valve, one outlet of the flow control valve is connected to the heat exchange pipeline of the battery pack heat exchanger, the battery pack heat exchanger is capable of exchanging heat with the battery pack, the other outlet of the flow control valve is connected to the heat exchange pipeline of the air conditioning unit, the controller is electrically / signally connected to the flow control valve, the controller is capable of controlling the opening of the flow control valve to adjust the flow rate of the working medium flowing to the air conditioning unit side and the battery pack heat exchanger side, the thermal management system includes an air conditioning system, the air conditioning system includes a heating mode, and when the air conditioning system is in heating mode and the battery pack has a heating demand, the PTC heater is controlled to heat, the control method comprising: S1. Adjust the initial flow rate of the working medium flowing to the air conditioning unit side and the battery pack heat exchanger side using the flow control valve; S2. Determine whether the temperature of the working medium at the outlet of the PTC heater is greater than or equal to the required temperature of the working medium on the side of the air conditioning unit. If yes, proceed to step S3. If no, control the flow control valve to increase the flow rate of the working medium flowing to the side of the air conditioning unit by a first set increment, and keep the increased flow rate at a first set time interval unchanged. S3. Determine whether the actual temperature of the battery pack is greater than or equal to the target temperature value of the battery pack. If yes, adjust the flow control valve to increase the flow rate of the working medium flowing to the air conditioning unit side by a second set increment every second set time interval until the flow rate flowing to the air conditioning unit side is maximum. If no, repeat step S2.

2. The control method as described in claim 1, characterized in that, In step S2, it is determined that the temperature of the working medium at the outlet of the PTC heater is greater than or equal to the required temperature of the working medium on the air conditioning unit side. Before executing step S3, step S20 is also included: adjusting the flow control valve to reduce the flow rate of the working medium flowing to the air conditioning unit side by a first set reduction, and keeping the reduced flow rate at a first set time interval unchanged.

3. The control method as described in claim 2, characterized in that, In step S3, if it is determined that the actual temperature of the battery pack has not reached the target temperature value of the battery pack, step S20 is executed for a predetermined time or a predetermined number of times before step S2 is re-executed.

4. The control method according to any one of claims 1-3, characterized in that, In step S1, the initial flow rate of the working medium flowing to the air conditioning unit side and the battery pack heat exchanger side via the flow control valve includes: a. Determine if the battery pack is charging. If yes, proceed to step b; otherwise, proceed to step c. b. Determine whether the battery pack temperature is lower than the preset battery pack temperature threshold. If yes, set the initial flow rate of the working medium flowing to the air conditioning unit side as the first initial flow rate. If no, set the initial flow rate of the working medium flowing to the air conditioning unit side as the second initial flow rate. The first initial flow rate is less than the second initial flow rate. c. Determine whether the ambient temperature is lower than the preset ambient temperature threshold. If yes, set the initial flow rate of the working medium flowing to the air conditioning unit as the third initial flow rate. If no, set the initial flow rate of the working medium flowing to the air conditioning unit as the fourth initial flow rate. The third initial flow rate is greater than the fourth initial flow rate.

5. The control method as described in claim 4, characterized in that, The third initial flow rate is greater than the first initial flow rate or the second initial flow rate, and the fourth initial flow rate is greater than the first initial flow rate or the second initial flow rate.

6. The control method as described in claim 5, characterized in that, Numerically, the first set decrease is less than the first set increase, and the first set decrease is less than the second set increase; the first set time interval is greater than the second set time interval.

7. The control method as described in claim 5 or 6, characterized in that, If the flow rate of the working medium flowing to the air conditioning unit is reduced by a first set reduction and is greater than or equal to the minimum preset flow rate, then the flow rate of the working medium on the air conditioning unit side is set to the minimum preset flow rate. If the increase in the working medium flow rate on the air conditioning unit side is less than or equal to the maximum preset flow rate, and the increase in the working medium flow rate on the air conditioning unit side is greater than the maximum preset flow rate, then the working medium flow rate on the air conditioning unit side is set to the maximum preset flow rate.

8. The control method according to any one of claims 1-3 and 5-6, characterized in that, When the air conditioning system is in heating mode and the battery pack has no heating requirement, the PTC heater is controlled to heat. The control method of the flow control valve includes adjusting the flow control valve so that the flow rate of the working medium flowing to the air conditioning unit is the maximum set flow rate.

9. The control method as described in claim 4, characterized in that, When the air conditioning system is in heating mode and the battery pack has no heating requirement, the PTC heater is controlled to heat. The control method of the flow control valve includes adjusting the flow control valve so that the flow rate of the working medium flowing to the air conditioning unit is the maximum set flow rate.

10. The control method as described in claim 7, characterized in that, When the air conditioning system is in heating mode and the battery pack has no heating requirement, the PTC heater is controlled to heat. The control method of the flow control valve includes adjusting the flow control valve so that the flow rate of the working medium flowing to the air conditioning unit is the maximum set flow rate.

11. The control method as described in claim 8, characterized in that, The air conditioning system also includes a defrosting mode. When the air conditioning system is in defrosting mode, the control method further includes: determining whether the battery pack is charging; if so, adjusting the flow control valve to ensure that the flow rate of the working medium flowing to the air conditioning unit is always a first flow rate; if not, adjusting the flow control valve to ensure that the flow rate of the working medium flowing to the air conditioning unit is always a second flow rate, wherein the first flow rate is less than the second flow rate.

12. The control method as described in claim 9 or 10, characterized in that, The air conditioning system also includes a defrosting mode. When the air conditioning system is in defrosting mode, the control method further includes: determining whether the battery pack is charging; if so, adjusting the flow control valve to ensure that the flow rate of the working medium flowing to the air conditioning unit is always a first flow rate; if not, adjusting the flow control valve to ensure that the flow rate of the working medium flowing to the air conditioning unit is always a second flow rate, wherein the first flow rate is less than the second flow rate.

13. The control method as described in claim 8, characterized in that, The air conditioning system also includes a cooling mode. When the air conditioning system is in cooling mode, the PTC heater is not started and the flow control valve is kept in its current position.

14. The control method as described in claim 9 or 10, characterized in that, The air conditioning system also includes a cooling mode. When the air conditioning system is in cooling mode, the PTC heater is not started and the flow control valve is kept in its current position.

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