Dual valve control method, device, vehicle and readable storage medium for refrigeration system

Abstract

The application discloses a refrigeration system double-valve control method and device, a vehicle and a readable storage medium, comprising: obtaining an evaporator temperature threshold; adjusting the opening degree of the evaporator expansion valve through a first proportional-integral-derivative closed-loop adjustment circuit until the evaporator outlet superheat reaches a preset superheat threshold; adjusting the rotating speed of the compressor through a second proportional-integral-derivative closed-loop adjustment circuit to make the actual evaporator temperature approach the evaporator temperature threshold; and adjusting the opening degree of the bypass valve through a third proportional-integral-derivative closed-loop adjustment circuit if the actual evaporator temperature is lower than the evaporator temperature threshold and the current rotating speed of the compressor has reached a preset minimum rotating speed threshold. Through the above method, the excess refrigerant can be branched through the bypass branch under the low load working condition of the refrigeration system, the frequent start and stop of the compressor can be avoided, and the service life of the compressor and the air conditioner comfort can be improved.

Description

Technical Field

[0001] This application relates to the field of thermal management technology for new energy vehicles, and in particular to a dual-valve control method, device, vehicle, and readable storage medium for a refrigeration system. Background Technology

[0002] With the increasing popularity of new energy vehicles, the vehicle thermal management system is placing increasingly higher demands on the performance of the air conditioning system. The cooling system of new energy vehicles usually needs to simultaneously meet the cooling needs of the passenger compartment and the cooling needs of the power battery. Therefore, the performance selection of the core components of the cooling system (including electric compressor, evaporator expansion valve, evaporator, condenser, etc.) is often determined based on the maximum cooling capacity corresponding to the sum of the cooling needs of the passenger compartment and the cooling needs of the battery.

[0003] However, refrigeration systems selected based on maximum cooling capacity exhibit significant low-load adaptability issues in actual operation. When the passenger cabin or power battery experiences low-load cooling demand (e.g., during spring and autumn, at night, or when ambient temperatures are moderate), the minimum cooling capacity provided by the system still exceeds the actual low-load demand, resulting in excess cooling capacity. Furthermore, due to the minimum speed threshold limitation of the electric compressor, when the cooling demand further decreases and falls below the cooling capacity corresponding to the compressor operating at its minimum speed threshold, the system struggles to operate stably under low-load conditions.

[0004] To meet demand under low-load conditions, systems often need to frequently adjust the compressor speed, and even repeatedly start and stop the compressor, leading to problems such as frequent control fluctuations, inaccurate target control, and delayed target response. Frequent compressor starts and stops cause jerking during refrigeration system operation, affecting passenger comfort and exacerbating mechanical wear and electrical shocks to the compressor, reducing its lifespan. Ultimately, these issues result in a poor user experience with the air conditioner, with fluctuating airflow temperatures that are difficult to maintain within a stable, comfortable range.

[0005] Therefore, how to enable the refrigeration system of new energy vehicles to operate stably, accurately, and continuously under low-load conditions, and avoid frequent compressor start-stop, has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] The purpose of this application is to provide a dual-valve control method, device, vehicle, and readable storage medium for a refrigeration system, which enables continuous and precise adjustment of the cooling capacity when the refrigeration system of a new energy vehicle is under low load conditions, thereby avoiding frequent start-stop of the compressor.

[0007] To achieve the above objectives: In a first aspect, embodiments of this application provide a dual-valve control method for a refrigeration system. The method is applied to a refrigeration system for a new energy vehicle, which includes a compressor, an evaporator, an evaporator expansion valve, and a bypass valve. The bypass valve is disposed in a bypass branch connecting the compressor outlet and inlet, and a coaxial tube heat exchanger is further connected in series in the bypass branch. The method includes: In response to receiving a cooling demand, the evaporator temperature threshold is obtained; The opening of the evaporator expansion valve is adjusted by the first proportional-integral-derivative closed-loop control circuit until the superheat at the evaporator outlet reaches the preset superheat threshold. In response to the evaporator outlet superheat reaching a preset superheat threshold, the compressor speed is adjusted through a second proportional-integral-derivative closed-loop control loop to make the actual evaporator temperature approach the evaporator temperature threshold. During the process of adjusting the compressor speed, if the actual temperature of the evaporator is lower than the evaporator temperature threshold and the current speed of the compressor has reached the preset minimum speed threshold, the opening of the bypass valve is adjusted through the third proportional-integral-derivative closed-loop control circuit to divert the refrigerant discharged by the compressor through the bypass branch until the actual temperature of the evaporator reaches the evaporator temperature threshold.

[0008] In one embodiment, adjusting the opening degree of the bypass valve through a third proportional-integral-derivative closed-loop control circuit includes: The diverted refrigerant flows through the high-pressure side channel of the coaxial tube heat exchanger connected in series in the bypass branch, releasing heat to the low-pressure refrigerant flowing through the low-pressure side channel of the coaxial tube heat exchanger from the evaporator outlet, thereby achieving heat exchange between the high and low pressure sides. After releasing heat, the diverted refrigerant merges with the low-pressure refrigerant after absorbing heat and enters the inlet of the compressor to increase the superheat of the refrigerant at the compressor inlet.

[0009] In one embodiment, adjusting the opening degree of the evaporator expansion valve through a first proportional-integral-derivative closed-loop control circuit includes: The evaporator expansion valve is an electronic expansion valve, and its opening degree is continuously adjustable between the closed opening degree and the fully open opening degree. The evaporator outlet superheat is determined based on the difference between the measured temperature at the evaporator outlet and the saturation temperature at the corresponding pressure at the evaporator outlet.

[0010] In one embodiment, determining that the current speed of the compressor has reached a preset minimum speed threshold includes: When the current speed of the compressor is less than or equal to the minimum speed threshold, it is determined that the compressor's adjustment capability has been exhausted. At this time, adjusting the compressor speed alone cannot further reduce the cooling capacity to match the evaporator temperature threshold. When the current speed of the compressor is greater than the minimum speed threshold, the compressor continues to adjust the speed using the second proportional-integral-derivative closed-loop control circuit, and the bypass valve is not activated.

[0011] In one embodiment, adjusting the opening degree of the bypass valve through a third proportional-integral-derivative closed-loop control circuit includes: When the opening of the bypass valve increases, the amount of refrigerant diverted through the bypass branch increases, the amount of refrigerant entering the evaporator decreases accordingly, the cooling capacity of the evaporator decreases, the actual temperature of the evaporator rises and converges towards the evaporator temperature threshold. When the opening of the bypass valve decreases, the amount of refrigerant diverted through the bypass branch decreases, the amount of refrigerant entering the evaporator increases accordingly, the cooling capacity of the evaporator increases, the actual temperature of the evaporator decreases and converges towards the evaporator temperature threshold.

[0012] In one embodiment, the first proportional-integral-derivative closed-loop control loop, the second proportional-integral-derivative closed-loop control loop, and the third proportional-integral-derivative closed-loop control loop are all integrated into the same thermal system controller. When the third proportional-integral-derivative closed-loop control loop is activated, the compressor is driven by the thermal system controller to run continuously at the minimum speed threshold. The evaporator expansion valve maintains its opening at the preset superheat threshold and adjusts the opening of the bypass valve to control the actual temperature of the evaporator.

[0013] In one embodiment, the method further includes setting a first trigger threshold for switching from normal mode to bypass mode and a second trigger threshold for switching back from bypass mode to normal mode; If the deviation between the actual temperature of the evaporator and the evaporator temperature threshold is between the first trigger threshold and the second trigger threshold, then the current control mode remains unchanged.

[0014] Secondly, embodiments of this application provide a dual-valve control device for a refrigeration system, comprising: Temperature threshold acquisition module, used to acquire evaporator temperature threshold in response to received cooling demand; The expansion valve control module is used to adjust the opening of the evaporator expansion valve through a first proportional-integral-derivative closed-loop regulation loop until the superheat at the evaporator outlet reaches a preset superheat threshold. The compressor control module is used to adjust the speed of the compressor through a second proportional-integral-derivative closed-loop control loop when the superheat at the evaporator outlet reaches a preset superheat threshold, so that the actual temperature of the evaporator approaches the evaporator temperature threshold. The bypass valve control module is used to adjust the opening of the bypass valve through a third proportional-integral-derivative closed-loop control circuit when the actual temperature of the evaporator is lower than the evaporator temperature threshold and the current speed of the compressor has reached the preset minimum speed threshold during the process of adjusting the compressor speed. This is to divert the refrigerant discharged by the compressor through the bypass branch until the actual temperature of the evaporator reaches the evaporator temperature threshold.

[0015] Thirdly, embodiments of this application provide a vehicle, specifically including: processor; Memory used to store the processor's executable instructions; The processor is configured to execute the instructions for performing the dual-valve control method for the refrigeration system as described in the first aspect.

[0016] Fourthly, embodiments of this application provide a machine-readable storage medium storing a computer program that, when the instructions in the machine-readable storage medium are executed by a vehicle's processor, enables the vehicle to implement the dual-valve control method for the refrigeration system as described in the first aspect.

[0017] This application provides a dual-valve control method, device, vehicle, and readable storage medium for a refrigeration system, comprising: in response to receiving a refrigeration demand, acquiring an evaporator temperature threshold; adjusting the opening of the evaporator expansion valve through a first proportional-integral-derivative (PID) closed-loop control circuit until the evaporator outlet superheat reaches a preset superheat threshold; in response to the evaporator outlet superheat reaching the preset superheat threshold, adjusting the compressor speed through a second PID closed-loop control circuit to bring the actual evaporator temperature closer to the evaporator temperature threshold; during the compressor speed adjustment process, if the actual evaporator temperature is lower than the evaporator temperature threshold and the current compressor speed has reached a preset minimum speed threshold, adjusting the opening of the bypass valve through a third PID closed-loop control circuit to divert the refrigerant discharged by the compressor via the bypass branch until the actual evaporator temperature reaches the evaporator temperature threshold. This method enables the diversion of excess refrigerant via the bypass branch under low-load conditions of the refrigeration system, avoiding frequent compressor start-stop cycles and improving compressor life and air conditioning comfort. Attached Figure Description

[0018] Figure 1This is a flowchart illustrating the dual-valve control method for a refrigeration system provided in an embodiment of the present invention.

[0019] Figure 2 This is a schematic diagram of the structure of a refrigeration system provided in an embodiment of the present invention.

[0020] Figure 3 A schematic diagram of the structure of the dual-valve control device for the refrigeration system provided in this embodiment of the invention.

[0021] Figure 4 This is a structural schematic diagram of a vehicle provided in an embodiment of the present invention.

[0022] Processor 410, memory 411, network interface 412, bus system 413. Detailed Implementation

[0023] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0024] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, components, features, and elements with the same names in different embodiments of this application may have the same meaning or different meanings, the specific meaning of which must be determined by its interpretation in that specific embodiment or further in conjunction with the context of that specific embodiment.

[0025] It should be understood that although the terms first, second, third, etc., may be used herein to describe various information, such information should not be limited to these terms. These terms are used only to distinguish information of the same type from one another. For example, without departing from the scope of this document, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if," as used herein, can be interpreted as "when," "when," or "in response to determination." Furthermore, as used herein, the singular forms "a," "an," and "the" are intended to also include the plural forms unless the context indicates otherwise. It should be further understood that the terms "comprising," "including," indicate the presence of the stated feature, step, operation, element, component, item, kind, and / or group, but do not exclude the presence, occurrence, or addition of one or more other features, steps, operations, elements, components, items, kinds, and / or groups. The terms "or" and "and / or" as used herein are to be interpreted as inclusive, or mean any one or any combination thereof. Therefore, "A, B, or C" or "A, B, and / or C" means "any one of the following: A; B; C; A and B; A and C; B and C; A, B, and C". Exceptions to this definition will only occur if the combination of elements, functions, steps, or operations is inherently mutually exclusive in some way.

[0026] It should be understood that although the steps in the flowcharts of this application's embodiments are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some of the steps in the figures may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times, and their execution order is not necessarily sequential, but can be performed alternately or in turn with other steps or at least a portion of the sub-steps or stages of other steps.

[0027] It should be noted that step designations such as S101 and S102 are used in this document for the purpose of more clearly and concisely describing the corresponding content, and do not constitute a substantial limitation on the order. In specific implementation, those skilled in the art may execute S102 first and then S101, etc., but these should all be within the protection scope of this application.

[0028] It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0029] In the following description, the use of suffixes such as "module," "part," or "unit" to denote elements is solely for the purpose of illustrative purposes and has no specific meaning in itself. Therefore, "module," "part," or "unit" may be used interchangeably.

[0030] It should be noted that currently, the air conditioning systems of new energy vehicles typically use compressor speed regulation combined with evaporator expansion valve opening adjustment to control cooling capacity, a control strategy that relies solely on the compressor as the primary adjustment method. This strategy can effectively match medium-to-high load demands within the compressor's adjustable speed range. However, when demand drops below the cooling capacity corresponding to the compressor's minimum speed, the system lacks an effective means to further release excess cooling capacity, and can only rely on repeated compressor start-stop cycles to approximate the demand, leading to fluctuations and reduced lifespan. The existing technology lacks the capability to further reduce cooling capacity at low loads, resulting in wasted compressor resources and potential performance issues.

[0031] To address the aforementioned issues, this application proposes a dual-valve control method for a refrigeration system. By adding a bypass branch with a bypass valve and a coaxial tube heat exchanger connected in series between the compressor's outlet and inlet, and employing a cascaded control architecture of first, second, and third proportional-integral-derivative closed-loop regulation loops, the excess refrigerant discharged by the compressor can be diverted and returned via the bypass branch under low-load conditions when the compressor has already reduced to its minimum speed threshold and still cannot meet the demand. This breaks through the minimum cooling capacity limit set by the compressor's minimum speed, achieving continuous and precise adjustment of the cooling capacity. It avoids frequent compressor start-stop cycles, improves compressor lifespan and air conditioning comfort, and can be widely applied to vehicle thermal management and passenger cabin air conditioning scenarios in various new energy vehicles.

[0032] like Figure 1 As shown, this application proposes a dual-valve control method for a refrigeration system. This method can be implemented using software and / or hardware, for example, it can be integrated into the thermal system controller of a new energy vehicle. This embodiment uses a new energy vehicle refrigeration system including a compressor, evaporator, evaporator expansion valve, and bypass valve as an example. The refrigeration system also includes a coaxial tube heat exchanger connected in series in the bypass branch, and the bypass valve is located in the bypass branch connecting the compressor outlet and inlet. The dual-valve control method for a refrigeration system provided in this application includes the following steps: Step S101: In response to receiving a cooling demand, obtain the evaporator temperature threshold.

[0033] Optionally, cooling demand can refer to a passenger compartment cooling request or a cooling command issued by the vehicle thermal management system, such as a user turning on the air conditioning or the vehicle thermal management system determining that the passenger compartment needs to be cooled. Optionally, evaporator temperature threshold can refer to the desired temperature that the evaporator should reach to meet the current cooling demand.

[0034] Optionally, the evaporator temperature threshold can be calculated by the vehicle thermal management system based on parameters such as the passenger compartment set temperature, the actual passenger compartment temperature, the ambient temperature, and the solar radiation intensity. Alternatively, it can be obtained by looking up a pre-calibrated correspondence (such as a mapping table between the passenger compartment set temperature and the evaporator temperature threshold).

[0035] Furthermore, in response to receiving a cooling demand, the evaporator temperature threshold is obtained, including: the thermal system controller receiving the cooling demand and calculating the corresponding evaporator temperature threshold based on at least one of the passenger cabin set temperature, the actual passenger cabin temperature, the ambient temperature, and the solar radiation intensity; or, obtaining the corresponding evaporator temperature threshold by looking up a table according to a pre-calibrated mapping relationship between the passenger cabin set temperature and the evaporator temperature threshold.

[0036] In the above embodiments, by transforming the passenger cabin cooling demand into a clear and quantifiable evaporator temperature threshold, a clear and traceable control target is provided for subsequent closed-loop control with the actual evaporator temperature as the controlled variable. This makes the system's adjustment direction quantifiable and calibrable, thereby improving control accuracy and maintainability.

[0037] Step S102: Adjust the opening of the evaporator expansion valve through the first proportional-integral-derivative closed-loop control circuit until the superheat at the evaporator outlet reaches the preset superheat threshold.

[0038] Optionally, the evaporator expansion valve may be an electronic expansion valve, whose opening degree is continuously adjustable between closed and fully open; the evaporator outlet superheat can be determined based on the difference between the measured temperature at the evaporator outlet and the saturation temperature at the corresponding pressure at the evaporator outlet.

[0039] Optionally, the first proportional-integral-derivative closed-loop control loop can refer to a closed-loop control loop with the evaporator outlet superheat as the controlled variable and a preset superheat threshold as the control target. Its actuator is the evaporator expansion valve, and the thermal system controller runs the loop to output the opening adjustment of the evaporator expansion valve.

[0040] Furthermore, the opening of the evaporator expansion valve is adjusted through the first proportional-integral-derivative closed-loop control loop until the superheat at the evaporator outlet reaches the preset superheat threshold. This includes: the thermal system controller acquiring the measured temperature T_out at the evaporator outlet and the saturation temperature T_sat at the corresponding pressure at the evaporator outlet, and calculating the superheat at the evaporator outlet SH=T_out. T_sat; with superheat deviation e1 (e1 = preset superheat threshold) SH) serves as the input to the first proportional-integral-derivative closed-loop control circuit, outputting the opening adjustment of the evaporator expansion valve according to proportional, integral, and derivative operations. When the opening of the evaporator expansion valve increases, the refrigerant flow rate into the evaporator increases, and the superheat decreases. When the opening of the evaporator expansion valve decreases, the refrigerant flow rate into the evaporator decreases, and the superheat increases. Through the closed-loop control of the first proportional-integral-derivative closed-loop control circuit, the superheat at the evaporator outlet will gradually approach and stabilize at the preset superheat threshold.

[0041] Optionally, in a specific example, the preset superheat threshold can be a value between 3°C and 8°C, such as 5°C. It is understood that the preset superheat threshold can be pre-calibrated based on factors such as the type of refrigerant and the system structure, and this application does not limit this.

[0042] In the above embodiments, superheat is a key parameter for ensuring the safe operation of the compressor. If the superheat is too low or even zero, it indicates that there is incompletely vaporized liquid refrigerant at the evaporator outlet. This liquid refrigerant entering the compressor will cause liquid slugging and damage the compressor. Therefore, the first proportional-integral-derivative closed-loop control circuit, as a safety inner loop, prioritizes ensuring that the superheat at the evaporator outlet is stable within a reasonable range (i.e., reaching the preset superheat threshold), laying a safe foundation for subsequent temperature regulation. This allows the system to carry out temperature control under the safe premise of preventing liquid slugging, improving the system's reliability and compressor lifespan.

[0043] Step S103: In response to the evaporator outlet superheat reaching the preset superheat threshold, the compressor speed is adjusted through the second proportional-integral-derivative closed-loop control circuit to make the actual evaporator temperature approach the evaporator temperature threshold.

[0044] Optionally, the second proportional-integral-derivative closed-loop control loop can refer to a closed-loop control loop with the actual temperature of the evaporator as the controlled variable and the evaporator temperature threshold as the control target. Its actuator is a compressor, and the thermal system controller runs the loop to output the compressor speed regulation.

[0045] Furthermore, in response to the evaporator outlet superheat reaching a preset superheat threshold, the compressor speed is adjusted through a second proportional-integral-derivative closed-loop control circuit to bring the actual evaporator temperature closer to the evaporator temperature threshold, including: adjusting the compressor speed by adjusting the temperature deviation e2 (e2 = actual evaporator temperature). The evaporator temperature threshold is used as the input to the second proportional-integral-derivative (PID) closed-loop control loop. The loop outputs the compressor speed adjustment based on proportional, integral, and derivative operations. When the actual evaporator temperature is higher than the evaporator temperature threshold (i.e., insufficient cooling), the second PID closed-loop control loop increases the compressor speed and refrigerant circulation flow, thereby enhancing cooling capacity and lowering the actual evaporator temperature. When the actual evaporator temperature is lower than the evaporator temperature threshold (i.e., excessive cooling), the second PID closed-loop control loop decreases the compressor speed and refrigerant circulation flow, thereby weakening cooling capacity and causing the actual evaporator temperature to rise. Through the closed-loop regulation of the second PID closed-loop control loop, the actual evaporator temperature will gradually approach the evaporator temperature threshold.

[0046] In the above embodiments, the compressor, as the actuator of the main control loop, is the primary means of regulating the cooling capacity. Under most medium-to-high load conditions, the actual evaporator temperature can be stabilized near the evaporator temperature threshold simply by adjusting the compressor speed through the second proportional-integral-derivative closed-loop control circuit. At this time, the bypass valve remains closed, and the bypass shunting is not activated, thus enabling the system to operate with the simplest and most efficient control structure under medium-to-high load conditions, reducing control complexity and energy consumption.

[0047] Step S104: During the process of adjusting the compressor speed, if the actual temperature of the evaporator is lower than the evaporator temperature threshold and the current speed of the compressor has reached the preset minimum speed threshold, the opening of the bypass valve is adjusted through the third proportional integral derivative closed-loop control circuit to divert the refrigerant discharged by the compressor through the bypass branch until the actual temperature of the evaporator reaches the evaporator temperature threshold.

[0048] Optionally, the third proportional-integral-derivative closed-loop control loop can refer to a closed-loop control loop with the actual temperature of the evaporator as the controlled variable and the evaporator temperature threshold as the control target. Its actuator is a bypass valve, and the thermal system controller runs the loop to output the opening adjustment of the bypass valve.

[0049] Furthermore, determining that the current speed of the compressor has reached the preset minimum speed threshold includes: when the current speed of the compressor is less than or equal to the minimum speed threshold, it is determined that the compressor's adjustment capability has been exhausted, and at this time, adjusting the compressor speed alone cannot further reduce the cooling capacity to match the evaporator temperature threshold; when the current speed of the compressor is greater than the minimum speed threshold, the compressor continues to adjust the speed using the second proportional-integral-derivative closed-loop control circuit, without activating the bypass valve.

[0050] Furthermore, the opening of the bypass valve is adjusted through the third proportional-integral-derivative closed-loop control circuit, including: the diverted refrigerant flows through the high-pressure side channel of the coaxial tube heat exchanger connected in series in the bypass branch, and releases heat to the low-pressure refrigerant from the evaporator outlet flowing through the low-pressure side channel of the coaxial tube heat exchanger, thereby realizing heat exchange between the high and low pressure sides; the diverted refrigerant after heat release merges with the low-pressure refrigerant after heat absorption and enters the compressor inlet to increase the superheat of the refrigerant at the compressor inlet.

[0051] Furthermore, adjusting the opening of the bypass valve through the third proportional-integral-derivative closed-loop control circuit also includes: when the opening of the bypass valve increases, the amount of refrigerant diverted through the bypass branch increases, the amount of refrigerant entering the evaporator decreases accordingly, the cooling capacity of the evaporator decreases, the actual temperature of the evaporator increases and converges towards the evaporator temperature threshold; when the opening of the bypass valve decreases, the amount of refrigerant diverted through the bypass branch decreases, the amount of refrigerant entering the evaporator increases accordingly, the cooling capacity of the evaporator increases, the actual temperature of the evaporator decreases and converges towards the evaporator temperature threshold.

[0052] For example, the third proportional-integral-derivative closed-loop control loop uses a temperature deviation e3 (e3 = actual evaporator temperature) as the control loop. Using the evaporator temperature threshold as input, the bypass valve opening is adjusted according to proportional, integral, and derivative operations: when the actual evaporator temperature is lower than the evaporator temperature threshold (overcooling), the bypass valve opening is increased to divert more refrigerant and reduce the amount of refrigerant entering the evaporator, causing the actual evaporator temperature to rise; when the actual evaporator temperature is higher than the evaporator temperature threshold (undercooling), the bypass valve opening is decreased to lower the actual evaporator temperature until the actual evaporator temperature stabilizes at the evaporator temperature threshold.

[0053] In the above implementation, when the compressor has already dropped to the minimum speed threshold and still cannot match the low load demand, the bypass valve takes over the temperature control and diverts the excess refrigerant through the bypass branch. This fundamentally avoids further speed reduction or even shutdown of the compressor, thereby eliminating the jerking and mechanical / electrical shocks caused by frequent compressor start-stop. At the same time, the diverted refrigerant completes heat exchange between the high and low pressure sides through the coaxial tube heat exchanger, further increasing the superheat of the refrigerant at the compressor inlet and preventing liquid refrigerant from entering the compressor and causing liquid slugging. This allows the system to continuously cover the operating conditions below the minimum speed and ensure the long-term safe operation of the compressor, improving compressor life and the user's air conditioning experience.

[0054] It should be noted that the first, second, and third proportional-integral-derivative (PID) closed-loop control loops are all integrated within the same thermal system controller. When the third PID closed-loop control loop is active, the thermal system controller drives the compressor to operate continuously at the minimum speed threshold. The evaporator expansion valve maintains its opening at the preset superheat threshold, and the bypass valve opening is adjusted to control the actual evaporator temperature. Therefore, the compressor can operate continuously without being shut down, fundamentally avoiding frequent compressor start-stop cycles.

[0055] Furthermore, it also includes setting a first trigger threshold for switching from normal mode to bypass shunting mode, and a second trigger threshold for switching from bypass shunting mode back to normal mode, including: if the deviation between the actual evaporator temperature and the evaporator temperature threshold is between the first trigger threshold and the second trigger threshold, then the current control mode remains unchanged.

[0056] Optionally, the normal mode can refer to a control mode in which the compressor uses only the second proportional-integral-derivative closed-loop control circuit to regulate the speed, while the bypass valve remains closed; the bypass shunting mode can refer to a mode in which the third proportional-integral-derivative closed-loop control circuit is activated, and the bypass valve takes over the control of the actual temperature of the evaporator. A first trigger threshold is used to switch from the normal mode to the bypass shunting mode, and a second trigger threshold is used to switch from the bypass shunting mode back to the normal mode. The first trigger threshold and the second trigger threshold are different, and the numerical range between them is defined as the hysteresis interval.

[0057] For example, the deviation between the actual evaporator temperature and the evaporator temperature threshold (deviation = actual evaporator temperature) is used. Taking the evaporator temperature threshold (a negative value indicates the actual temperature is lower than the target temperature) as an example, the first trigger threshold can be set to... 0.5℃ (i.e., deviation is less than) When the temperature drops to 0.5℃ and the compressor has reached the minimum speed threshold, the system switches from normal mode to bypass shunt mode. The second trigger threshold can be set to +0.5℃ (i.e., when the deviation rises above +0.5℃, the system switches back from bypass shunt mode to normal mode). The difference between the two is […]. The hysteresis range is defined as 0.5℃ to +0.5℃. When the deviation falls within this hysteresis range, the current control mode remains unchanged.

[0058] In the above embodiments, by setting different switching thresholds and hysteresis ranges for normal mode and bypass shunting mode, the frequent switching between modes caused by slight fluctuations in the actual evaporator temperature near the critical value is effectively avoided, thereby improving the stability of the control signal and the smoothness of compressor operation, and thus improving the user's air conditioning experience.

[0059] In summary, the above implementation method, by setting a bypass branch with a bypass valve and a coaxial tube heat exchanger connected in series between the compressor outlet and inlet, and adopting a cascaded control architecture of the first, second, and third proportional-integral-derivative closed-loop regulation loops, can divert excess refrigerant discharged by the compressor through the bypass branch under low-load conditions. This breaks through the minimum cooling capacity limit formed by the compressor's minimum speed limitation, achieves continuous and precise adjustment of cooling capacity, avoids frequent compressor start-stop, eliminates system jerking, and improves the compressor's service life and the user's air conditioning experience.

[0060] Based on the same methodological concept as the foregoing embodiments, the foregoing embodiments will be described in detail below through a specific example.

[0061] The specific embodiments of this application aim to construct a continuous cooling capacity regulation system based on bypass diversion and cascaded dual-valve control for use in low-load conditions of new energy vehicles. The following will provide a detailed description of the system architecture, working principle, key modules, and interaction flow, and will also illustrate the core content that should be shown in each of the accompanying drawings.

[0062] I. System Overall Architecture This system is primarily deployed in the thermal management system of new energy vehicles, and is a refrigeration system integrating refrigerant circulation, bypass diversion, and electronic control. For example... Figure 2 As shown, its overall architecture can be divided into three layers: Refrigeration cycle layer: The main refrigerant circulation loop consists of compressor 10, condenser 20, evaporator expansion valve 30, and evaporator 40. The outlet of compressor 10 is connected to the inlet of condenser 20, the outlet of condenser 20 is connected to the inlet of evaporator expansion valve 30, the outlet of evaporator expansion valve 30 is connected to the inlet of evaporator 40, and the outlet of evaporator 40 is connected to the inlet of compressor 10. A front-end fan 21 is installed on one side of condenser 20 to drive external air to flow through the fins of condenser 20 to release heat. This executes the main circulation throttling and evaporation process corresponding to step S102 above.

[0063] Bypass Diversion Layer: A bypass branch 70 is added between the outlet and inlet of compressor 10. A bypass valve 50 and a coaxial tube heat exchanger 60 are connected in series in bypass branch 70. The bypass valve 50 is used to regulate the flow rate of refrigerant diverted through bypass branch 70. The coaxial tube heat exchanger 60 is an internal heat exchanger with a high-pressure side flow channel 61 and a low-pressure side flow channel 62. The high-pressure side flow channel 61 is connected in series in bypass branch 70 to flow the diverted high-pressure refrigerant, and the low-pressure side flow channel 62 is connected in series in the pipeline from the outlet of evaporator 40 to the inlet of compressor 10 to flow the low-pressure refrigerant from the outlet of evaporator 40. This performs the bypass diversion and high / low-pressure side heat exchange process corresponding to step S104 above.

[0064] Control Layer: This is the core processing unit, namely the thermal system controller 80. It is electrically connected to the compressor 10, the evaporator expansion valve 30, and the bypass valve 50, respectively. It collects parameters such as the actual evaporator temperature, evaporator outlet temperature, and pressure, and runs the first, second, and third proportional-integral-derivative closed-loop control circuits, outputting control commands for the compressor speed, evaporator expansion valve opening, and bypass valve opening. In other words, it executes the entire process control described in steps S101 to S104 above.

[0065] The information flow of the entire system is as follows: the passenger cabin cooling demand is received by the thermal system controller to obtain the evaporator temperature threshold, the first closed loop adjusts the evaporator expansion valve to ensure superheat, the second closed loop adjusts the compressor speed to approach the evaporator temperature threshold, the third closed loop (at low load) adjusts the bypass valve to divert the refrigerant, the refrigerant flows back through the bypass branch and merges into the compressor inlet, and the actual evaporator temperature stabilizes at the evaporator temperature threshold.

[0066] II. Detailed Description of Core Module Functions 1. Overheat safety inner loop module Function: Using the superheat at the evaporator outlet as the controlled variable, ensure that there is no liquid refrigerant at the compressor inlet to prevent liquid slugging.

[0067] Input: Measured evaporator outlet temperature T_out, saturation temperature T_sat at the corresponding pressure at the evaporator outlet.

[0068] Processing and Output: Calculate superheat SH = T_out T_sat, with superheat deviation e1 = preset superheat threshold SH serves as the input to the first proportional-integral-derivative closed-loop control loop, and outputs the opening adjustment of the evaporator expansion valve 30 to stabilize the superheat at a preset superheat threshold (e.g., 5°C).

[0069] 2. Temperature main control loop module Function: Using the actual evaporator temperature as the controlled variable, the actual evaporator temperature is adjusted to the evaporator temperature threshold under medium and high load conditions.

[0070] Input: Actual evaporator temperature, evaporator temperature threshold.

[0071] Processing and Output: Temperature deviation e2 = actual evaporator temperature The evaporator temperature threshold serves as the input to the second proportional-integral-derivative closed-loop control circuit, outputting the speed adjustment of compressor 10. When the deviation is positive (actual temperature is too high), the speed is increased to enhance cooling; when the deviation is negative (actual temperature is too low), the speed is decreased to weaken cooling.

[0072] 3. Bypass / Shunting Auxiliary Control Loop Module Function: When the compressor has dropped to the minimum speed threshold and its regulating capacity has been exhausted, it takes over the actual temperature control of the evaporator and releases excess cooling capacity through bypass diversion.

[0073] Input: Actual evaporator temperature, evaporator temperature threshold, current compressor speed.

[0074] Processing and Output: When the actual evaporator temperature is lower than the evaporator temperature threshold and the compressor's current speed has reached the minimum speed threshold, the output is calculated as: Temperature deviation e3 = Actual evaporator temperature. The evaporator temperature threshold serves as the input to the third proportional-integral-derivative closed-loop control circuit, outputting the opening adjustment of the bypass valve 50. The diverted refrigerant releases heat from the high-pressure side channel 61 of the coaxial tube heat exchanger 60 to the low-pressure side channel 62 before converging into the compressor 10 inlet, increasing the inlet superheat. This module also needs to handle the hysteresis anti-shake judgment between the normal mode and the bypass diversion mode (adding the hysteresis interval formed by the first trigger threshold and the second trigger threshold), and set the compressor to run continuously at the minimum speed threshold, while maintaining the evaporator expansion valve at the opening constant when the preset superheat threshold is reached.

[0075] III. System Workflow and Timing Start: Receive passenger cabin cooling demand, and the thermal system controller obtains the evaporator temperature threshold.

[0076] Safety inner loop: The first proportional-integral-derivative closed-loop control circuit adjusts the opening of the evaporator expansion valve so that the superheat at the evaporator outlet reaches the preset superheat threshold.

[0077] Main control loop: The second proportional-integral-derivative closed-loop regulation loop adjusts the compressor speed so that the actual temperature of the evaporator approaches the evaporator temperature threshold.

[0078] Low load judgment: Real-time judgment of whether the actual temperature of the evaporator is lower than the evaporator temperature threshold and whether the current speed of the compressor has reached the minimum speed threshold.

[0079] Auxiliary control loop: If the above two conditions are met at the same time, the third proportional-integral-derivative closed-loop regulation loop is activated, and the opening of the bypass valve is adjusted to divert the excess refrigerant through the bypass branch until the actual temperature of the evaporator reaches the evaporator temperature threshold.

[0080] Loop: Continuous operation.

[0081] Through the above modular and process-oriented design, this application realizes the bypass diversion of excess refrigerant and the continuous and precise adjustment of cooling capacity under low load conditions, avoiding frequent start-stop of the compressor and improving compressor life and air conditioning comfort.

[0082] Based on the same inventive concept as the foregoing embodiments, this invention provides a dual-valve control device for a refrigeration system, see reference. Figure 3 The device includes: Temperature threshold acquisition module 01 is used to acquire the evaporator temperature threshold in response to receiving a cooling demand. The expansion valve control module 02 is used to adjust the opening of the evaporator expansion valve through the first proportional-integral-derivative closed-loop regulation circuit until the superheat at the evaporator outlet reaches the preset superheat threshold. The compressor control module 03 is used to adjust the compressor speed through the second proportional-integral-derivative closed-loop control loop when the superheat of the evaporator outlet reaches the preset superheat threshold, so that the actual temperature of the evaporator approaches the evaporator temperature threshold. The bypass valve control module 04 is used to adjust the opening of the bypass valve through the third proportional-integral-derivative closed-loop control circuit when the actual temperature of the evaporator is lower than the evaporator temperature threshold and the current speed of the compressor has reached the preset minimum speed threshold during the process of adjusting the compressor speed. This allows the refrigerant discharged by the compressor to be diverted through the bypass branch until the actual temperature of the evaporator reaches the evaporator temperature threshold.

[0083] It should be noted that the description of the dual-valve control device for the refrigeration system above is similar to the description of the dual-valve control method for the refrigeration system above, and the beneficial effects of the same method will not be repeated. For technical details not disclosed in the embodiments of the dual-valve control device for the refrigeration system of the present invention, please refer to the description of the embodiments of the dual-valve control method for the refrigeration system of the present invention.

[0084] Based on the same inventive concept as the foregoing embodiments, this invention provides a vehicle, such as... Figure 4 As shown, the vehicle includes: a processor 410 and a memory 411 storing a computer program; wherein, Figure 4 The processor 410 shown in the diagram does not indicate that there is only one processor 410, but only indicates the positional relationship of the processor 410 relative to other devices. In practical applications, there can be one or more processors 410; similarly, Figure 4 The memory 411 shown in the diagram has the same meaning, that is, it is only used to indicate the positional relationship of memory 411 relative to other devices. In practical applications, there can be one or more memories 411. When the processor 410 runs the computer program, the above-described dual-valve control method for the refrigeration system is implemented.

[0085] The vehicle may also include at least one network interface 412. Various components in the vehicle are coupled together via a bus system 413. It is understood that the bus system 413 is used to enable communication between these components. In addition to a data bus, the bus system 413 also includes a power bus, a control bus, and a status signal bus. However, for clarity, in... Figure 4The general designated all buses as Bus System 413.

[0086] The memory 411 can be volatile or non-volatile, or both. Non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), ferromagnetic random access memory (FRAM), flash memory, magnetic surface memory, optical disc, or compact disc read-only memory (CD-ROM); magnetic surface memory can be disk storage or magnetic tape storage. Volatile memory can be random access memory (RAM), used as an external cache. By way of example, but not limitation, many forms of RAM are available, such as Static Random Access Memory (SRAM), Synchronous Static Random Access Memory (SSRAM), Dynamic Random Access Memory (DRAM), Synchronous Dynamic Random Access Memory (SDRAM), Double Data Rate Synchronous Dynamic Random Access Memory (DDRSDRAM), Enhanced Synchronous Dynamic Random Access Memory (ESDRAM), SyncLink Dynamic Random Access Memory (SLDRAM), and Direct Rambus Random Access Memory (DRRAM).The memory 411 described in the embodiments of the present invention is intended to include, but is not limited to, these and any other suitable types of memory.

[0087] The memory 411 in this embodiment of the invention is used to store various types of data to support the operation of the vehicle. Examples of this data include: any computer programs used to operate on the vehicle, such as operating systems and applications; contact data; phonebook data; messages; pictures; videos, etc. The operating system includes various system programs, such as a framework layer, core library layer, driver layer, etc., used to implement various basic services and handle hardware-based tasks. Applications can include various applications, such as media players, browsers, etc., used to implement various application services. Here, the program implementing the method of this embodiment of the invention can be included in the application.

[0088] Based on the same inventive concept as the foregoing embodiments, this embodiment also provides a machine-readable storage medium storing a computer program. The machine-readable storage medium can be a magnetic random access memory (FRAM), a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a flash memory, a magnetic surface memory, an optical disc, or a compact disc read-only memory (CD-ROM), etc.; it can also be various devices including one or any combination of the above-mentioned memories, such as mobile phones, computers, tablet devices, personal digital assistants, etc. When the computer program stored in the machine-readable storage medium is executed by a processor, it implements a dual-valve control method for the refrigeration system of the aforementioned vehicle. For the specific steps implemented when the computer program is executed by the processor, please refer to [link to relevant documentation]. Figure 1 The description of the illustrated embodiments will not be repeated here.

[0089] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0090] In this document, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, which includes not only the elements listed but also other elements not expressly listed.

[0091] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A dual-valve control method for a refrigeration system, characterized in that, The method is applied to a refrigeration system for new energy vehicles. The refrigeration system includes a compressor, an evaporator, an evaporator expansion valve, and a bypass valve. The bypass valve is located in a bypass branch connecting the compressor outlet and inlet. A coaxial tube heat exchanger is also connected in series in the bypass branch. The method includes: In response to receiving a cooling demand, the evaporator temperature threshold is obtained; The opening of the evaporator expansion valve is adjusted by the first proportional-integral-derivative closed-loop control circuit until the superheat at the evaporator outlet reaches the preset superheat threshold. In response to the evaporator outlet superheat reaching a preset superheat threshold, the compressor speed is adjusted through a second proportional-integral-derivative closed-loop control loop to make the actual evaporator temperature approach the evaporator temperature threshold. During the process of adjusting the compressor speed, if the actual temperature of the evaporator is lower than the evaporator temperature threshold and the current speed of the compressor has reached the preset minimum speed threshold, the opening of the bypass valve is adjusted through the third proportional-integral-derivative closed-loop control circuit to divert the refrigerant discharged by the compressor through the bypass branch until the actual temperature of the evaporator reaches the evaporator temperature threshold.

2. The method according to claim 1, characterized in that, The adjustment of the bypass valve opening via the third proportional-integral-derivative closed-loop control circuit includes: The diverted refrigerant flows through the high-pressure side channel of the coaxial tube heat exchanger connected in series in the bypass branch, releasing heat to the low-pressure refrigerant flowing through the low-pressure side channel of the coaxial tube heat exchanger from the evaporator outlet, thereby achieving heat exchange between the high and low pressure sides. After releasing heat, the diverted refrigerant merges with the low-pressure refrigerant after absorbing heat and enters the inlet of the compressor to increase the superheat of the refrigerant at the compressor inlet.

3. The method according to claim 1, characterized in that, The adjustment of the opening degree of the evaporator expansion valve through the first proportional-integral-derivative closed-loop control circuit includes: The evaporator expansion valve is an electronic expansion valve, and its opening degree is continuously adjustable between the closed opening degree and the fully open opening degree. The evaporator outlet superheat is determined based on the difference between the measured temperature at the evaporator outlet and the saturation temperature at the corresponding pressure at the evaporator outlet.

4. The method according to claim 1, characterized in that, The step of determining that the current speed of the compressor has reached a preset minimum speed threshold includes: When the current speed of the compressor is less than or equal to the minimum speed threshold, it is determined that the compressor's adjustment capability has been exhausted. At this time, adjusting the compressor speed alone cannot further reduce the cooling capacity to match the evaporator temperature threshold. When the current speed of the compressor is greater than the minimum speed threshold, the compressor continues to adjust the speed using the second proportional-integral-derivative closed-loop control circuit, and the bypass valve is not activated.

5. The method according to claim 1, characterized in that, The adjustment of the bypass valve opening via the third proportional-integral-derivative closed-loop control circuit includes: When the opening of the bypass valve increases, the amount of refrigerant diverted through the bypass branch increases, the amount of refrigerant entering the evaporator decreases accordingly, the cooling capacity of the evaporator decreases, the actual temperature of the evaporator rises and converges towards the evaporator temperature threshold. When the opening of the bypass valve decreases, the amount of refrigerant diverted through the bypass branch decreases, the amount of refrigerant entering the evaporator increases accordingly, the cooling capacity of the evaporator increases, the actual temperature of the evaporator decreases and converges towards the evaporator temperature threshold.

6. The method according to claim 1, characterized in that, The first proportional-integral-derivative closed-loop control loop, the second proportional-integral-derivative closed-loop control loop, and the third proportional-integral-derivative closed-loop control loop are all integrated into the same thermal system controller; When the third proportional-integral-derivative closed-loop control loop is activated, the compressor is driven by the thermal system controller to run continuously at the minimum speed threshold. The evaporator expansion valve maintains its opening at the preset superheat threshold and adjusts the opening of the bypass valve to control the actual temperature of the evaporator.

7. The method according to claim 1, characterized in that, The method further includes setting a first trigger threshold for switching from normal mode to bypass mode, and a second trigger threshold for switching back from bypass mode to normal mode; If the deviation between the actual temperature of the evaporator and the evaporator temperature threshold is between the first trigger threshold and the second trigger threshold, then the current control mode remains unchanged.

8. A dual-valve control device for a refrigeration system, characterized in that, include: Temperature threshold acquisition module, used to acquire evaporator temperature threshold in response to received cooling demand; The expansion valve control module is used to adjust the opening of the evaporator expansion valve through a first proportional-integral-derivative closed-loop regulation loop until the superheat at the evaporator outlet reaches a preset superheat threshold. The compressor control module is used to adjust the speed of the compressor through a second proportional-integral-derivative closed-loop control loop when the superheat at the evaporator outlet reaches a preset superheat threshold, so that the actual temperature of the evaporator approaches the evaporator temperature threshold. The bypass valve control module is used to adjust the opening of the bypass valve through a third proportional-integral-derivative closed-loop control circuit when the actual temperature of the evaporator is lower than the evaporator temperature threshold and the current speed of the compressor has reached the preset minimum speed threshold during the process of adjusting the compressor speed. This is to divert the refrigerant discharged by the compressor through the bypass branch until the actual temperature of the evaporator reaches the evaporator temperature threshold.

9. A vehicle, characterized in that, include: A processor and a memory for storing executable instructions; wherein the processor is configured to execute the instructions to implement the dual-valve control method for a refrigeration system as described in any one of claims 1-7.

10. A machine-readable storage medium, characterized in that, When the instructions in the machine-readable storage medium are executed by the processor, the dual-valve control method for the refrigeration system as described in any one of claims 1 to 7 is implemented.

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