Oil return control method, air conditioning system and storage medium

Abstract

The application discloses an oil return control method, an air conditioning system and a computer readable storage medium, and applies to the technical field of air conditioning system control. The method comprises the following steps: determining a current oil level of a compressor based on operation parameters of the compressor; determining a first oil return demand signal based on a difference between the current oil level and a preset safe oil level; performing energy analysis on the operation parameters of the compressor to determine a second oil return demand signal; the first oil return demand signal and the second oil return demand signal are both used to represent the emergency degree of oil return of the compressor; determining a target oil return control strategy based on the first oil return demand signal and the second oil return demand signal, wherein the target oil return control strategy is any preset oil return control strategy; and controlling the air conditioning system to return oil based on the target oil return control strategy. In this way, the installation of a physical oil level sensor can be avoided, the production cost is reduced, the oil return demand of the compressor can be accurately perceived and fine oil return can be realized, and the operation reliability of the air conditioning system is improved.

Description

Technical Field

[0001] This application belongs to the field of air conditioning system control technology, specifically relating to an oil return control method, an air conditioning system, and a computer-readable storage medium. Background Technology

[0002] During the operation of an air conditioning system, sufficient lubricating oil is required in the compressor to prevent wear and burn-out, thus ensuring the compressor's normal operation and lifespan. Since the refrigerant carries some of the lubricating oil from the compressor into the heat exchange lines, a return oil operation is necessary to send the accumulated lubricating oil from the heat exchange lines back to the compressor.

[0003] Traditional oil return control methods detect the oil level in the compressor using physical oil level sensors, triggering oil return when the actual oil level is low. However, physical oil level sensors are expensive and susceptible to interference from vibrations, leading to long-term reliability issues and the air conditioning system's inability to accurately sense the compressor's oil level. Furthermore, triggering oil return based on simple logic such as interval running time cannot adapt to the actual oil level in real time, easily resulting in insufficient or excessive oil return, reducing the overall energy efficiency of the air conditioning system, and even affecting the compressor's lifespan. Summary of the Invention

[0004] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes an oil return control method, an air conditioning system, and a computer-readable storage medium, which can avoid the installation of physical oil level sensors, reduce production costs, accurately sense the compressor's oil return demand and achieve refined oil return, thereby improving the operational reliability of the air conditioning system.

[0005] In a first aspect, this application provides an oil return control method, which is applied to an air conditioning system, the air conditioning system including a compressor, and the oil return control method includes: Based on the operating parameters of the compressor, determine the current oil level of the compressor; Based on the difference between the current oil level and the preset safe oil level, the first return oil demand signal is determined; Energy analysis is performed on the operating parameters of the compressor to determine the second oil return demand signal. Both the first and second oil return demand signals are used to characterize the urgency of the compressor's oil return. Based on the first return oil demand signal and the second return oil demand signal, a target return oil control strategy is determined, wherein the target return oil control strategy is any preset return oil control strategy. Based on the target oil return control strategy, the air conditioning system is controlled to return oil.

[0006] Secondly, this application provides an air conditioning system, which includes a compressor, a memory, and a processor; the memory stores a computer program, and the processor executes the above-mentioned oil return control method by calling the computer program stored in the memory.

[0007] Thirdly, this application provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the above-mentioned oil return control method.

[0008] The oil return control method, air conditioning system, and computer-readable storage medium provided in this application embodiment can determine the current oil level of the compressor based on the different operating parameters of the compressor under different oil level conditions, thereby avoiding the installation of high-cost physical oil level sensors and reducing production costs.

[0009] Based on the difference between the current oil level and the preset safe oil level, a first oil return demand signal is determined. A second oil return demand signal is determined based on the compressor's operating efficiency through energy analysis of its operating parameters. Since both the first and second oil return demand signals characterize the urgency of compressor oil return and are obtained through different methods, integrating them for dual-channel analysis and verification enables refined and continuous perception of oil return demand. This refined oil return demand then allows for the determination of a corresponding preset oil return control strategy as the target oil return control strategy.

[0010] Finally, the air conditioning system is controlled to return oil according to the target oil return control strategy. In this way, the compressor's oil return demand is accurately sensed and precise on-demand oil return control is achieved, thereby improving the operational reliability of the air conditioning system.

[0011] Additional aspects and advantages of embodiments of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of embodiments of this application. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 This is an application scenario diagram of the oil return control method provided in some embodiments of this application; Figure 2 This is a first flowchart illustrating the oil return control method provided in certain embodiments of this application; Figure 3 This is a schematic diagram of the second process of the oil return control method provided in some embodiments of this application; Figure 4 This is a schematic diagram of the third process of the oil return control method provided in some embodiments of this application; Figure 5 This is a schematic diagram of the fourth process of the oil return control method provided in some embodiments of this application; Figure 6 This is a schematic diagram of the fifth process of the oil return control method provided in some embodiments of this application; Figure 7 This is a schematic diagram of the sixth process of the oil return control method provided in some embodiments of this application; Figure 8 This is a schematic diagram of the structure of the oil return control device provided in some embodiments of this application; Figure 9 This is a schematic diagram of the structure of an air conditioning system provided in some embodiments of this application; Figure 10 This is a schematic diagram of the composition architecture of an air conditioning system provided in some embodiments of this application. Detailed Implementation

[0013] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0014] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0015] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joint" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection. They can refer to a mechanical connection or an electrical connection. They can refer to a direct connection or an indirect connection through an intermediate medium, and they can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0016] Please see Figure 1 , Figure 1 This is an application scenario diagram of the oil return control method provided in certain embodiments of this application. The application scenario provided in this application includes an air conditioning system 100, which includes an outdoor unit 10, an indoor unit 20, a compressor 30, a heat exchange pipeline 40, at least one electronic expansion valve 50, a data acquisition device 60, and a control device 70. The oil return control method provided in this application can be executed by the control device 70.

[0017] The outdoor unit 10, installed outdoors, serves as the power source for the refrigerant circulation and the carrier for outdoor heat exchange. The indoor unit 20, installed in the indoor space, is a functional component used for direct heat exchange with indoor air to regulate indoor temperature and humidity. Optionally, the air conditioning system 100 may include multiple indoor units 20, and one outdoor unit 10 may be connected to multiple indoor units 20. Alternatively, the air conditioning system 100 may include multiple indoor units 20 and outdoor units 10, with each indoor unit 20 connected to only one of the multiple outdoor units 10.

[0018] The compressor 30 is a mechanical device that compresses low-pressure gaseous refrigerant (such as difluoromethane, propane, etc.) into high-pressure, high-temperature gaseous refrigerant through mechanical work. The compressor 30 can be installed in the outdoor unit 10. The compressor 30 drives the refrigerant to continuously circulate in the heat exchange pipeline 40. The compressor 30 stores lubricating oil, which lubricates the friction parts of the compressor 30 to reduce wear and operating noise, and also seals the internal gaps of the compressor 30 to prevent refrigerant leakage. The lubricating oil can return to its original position along with the refrigerant circulation to ensure the overall operational stability of the air conditioning system 100.

[0019] Optionally, the compressor 30 may include, but is not limited to, scroll compressors, rotary compressors, piston compressors, screw compressors, etc.

[0020] The heat exchange pipe 40 is a closed-loop system used for heat exchange. It connects the outdoor unit 10 and the indoor unit 20. The refrigerant can undergo a phase change in the heat exchange pipe 40 to absorb or release heat, thus transferring heat between the indoor and outdoor units. Simultaneously, the refrigerant can also carry lubricating oil through its circulation, returning any accumulated oil to the compressor 30 to ensure its efficiency and safe operation.

[0021] The electronic expansion valve 50 is an electrically controlled throttling element. Connected in series with the heat exchange pipeline 40, the electronic expansion valve 50 precisely regulates the refrigerant flow rate in the heat exchange pipeline 40 by changing its opening degree (i.e., the cross-sectional area of ​​the flow), thereby meeting the user's needs. Optionally, the electronic expansion valve 50 includes a main circuit electronic expansion valve and a jet electronic expansion valve. The main circuit electronic expansion valve controls the refrigerant in the main circulation, ensuring the indoor heat exchange flow rate; the jet electronic expansion valve is located on the branch auxiliary pipe of the heat exchange pipeline 40, used to throttle a portion of the refrigerant, so that the throttled refrigerant vaporizes and is injected into the gas injection port of the compressor 30, realizing on-demand opening and closing to adjust the gas injection volume. The type of electronic expansion valve 50 may include, but is not limited to: array electronic expansion valve, ball valve type electronic expansion valve, capillary tube type electronic expansion valve, etc., and this embodiment does not limit this.

[0022] Optionally, the air conditioning system 100 may also include components such as an oil separator, a four-way valve, a gas-liquid separator, and a plate heat exchanger. Figure 1 (Not shown in the image). These components can be connected via heat exchange pipes 40 and work in conjunction with components such as compressor 30 to ensure the normal operation of the air conditioning system 100.

[0023] The data acquisition device 60 is a sensing component used to collect operating parameters such as temperature, pressure, and operating frequency of the components of the air conditioning system 100 (such as the compressor 30). For example, the data acquisition device 60 includes multiple temperature sensors, pressure sensors, current sensors, and valve position acquisition units. The multiple temperature sensors can be used to collect the discharge temperature of the compressor 30, indoor temperature, and outdoor temperature, respectively; the multiple pressure sensors can be used to collect the discharge pressure of the compressor 30 and the pressure in the heat exchange pipeline 40, respectively; the multiple current sensors can be used to collect the output current of the compressor 30 and the operating current of the fan, respectively; and the multiple valve position acquisition units can be used to collect the actual opening degree of each electronic expansion valve 50, respectively.

[0024] The control device 70 is a device with data processing capabilities. The control device 70 can acquire and process relevant data collected by the acquisition device 60 in real time, and output corresponding control commands to control the operating conditions of relevant components in the air conditioning system 100, ensuring the normal operation of the air conditioning system 100. Optionally, the control device 70 may include, but is not limited to, a system on a chip (SoC), a microcontroller unit (MCU), a digital signal processor (DSP), etc., but this embodiment does not limit the specific implementation.

[0025] Based on the above description of the relevant scenarios, this application provides a method for controlling oil return, which will be described in detail below: Please see Figure 2 The oil return control method provided in this application embodiment is implemented by steps 011, 012, 013, 014 and 015, which are described in detail below.

[0026] Step 011: Determine the current oil level of the compressor based on its operating parameters; It is understandable that compressor operating parameters differ depending on the oil level. When the oil level is low, insufficient lubrication increases compressor friction losses, leading to higher exhaust temperature, increased power consumption, and decreased isentropic efficiency. When the oil level is too high, the lubricating oil occupies cylinder volume, resulting in increased compression load, increased power consumption, and a higher risk of liquid slugging. Therefore, the compressor's current oil level can be estimated based on its real-time operating parameters.

[0027] The compressor's operating parameters can be acquired in real time using a corresponding acquisition device. The real-time acquired compressor operating parameters can form a real-time feature vector, with each feature vector corresponding to a preset oil level value. Optionally, the compressor's operating parameters may include operating current, operating frequency, exhaust temperature, exhaust pressure, etc., which are not limited in this embodiment.

[0028] In one alternative embodiment, please refer to Figure 3 The oil return control method also includes steps 016 and 017, which are explained in detail below.

[0029] Step 016: Obtain the virtual oil level training set; Step 017: Iteratively train the virtual oil level sensor using the virtual oil level training set to obtain a trained preset virtual oil level sensor.

[0030] The virtual oil level training set includes multiple sets of compressor operating parameter samples and corresponding real oil level samples. The real oil level samples are obtained based on high-precision physical oil level sensors under calibration conditions. The parameter types of the operating parameter samples are the same as those of the compressor operating parameters collected in step 011.

[0031] Specifically, operational experiments covering all operating conditions were conducted on a prototype (air conditioning system) equipped with a high-precision physical oil level sensor. In addition to stable operation, sensitive operating conditions (such as operation in low-frequency sensitive ranges, load step changes, etc.) could be specially designed and executed to enhance the observability of oil level changes. During the operation of the prototype, the compressor's operating parameters and the corresponding readings from the high-precision physical oil level sensor were simultaneously collected. The collected raw data underwent time alignment, filtering, noise reduction, and outlier processing to create a high-quality virtual oil level training set and a real oil level sample.

[0032] During the iterative training of the virtual oil level sensor, the collected operating parameter samples of each group of compressors are used as input, and the corresponding real oil level samples are used as the convergence target. The iterative training of the virtual oil level sensor is considered complete when the difference between the predicted oil level value output by the virtual oil level sensor and the real oil level sample corresponding to the target operating parameter sample is less than a preset oil level threshold, provided that any input target operating parameter sample is provided. The preset oil level threshold is a default value set based on experience.

[0033] The finally trained preset virtual oil level sensor, after receiving a target operating parameter sample, can output the corresponding oil level. The difference between the output oil level and the actual oil level sample corresponding to the target operating parameter sample is less than a preset oil level threshold. The target operating parameter sample can be any operating parameter sample. In this way, a high-precision preset virtual oil level sensor can be obtained.

[0034] Optionally, during the iterative training of the virtual oil level sensor, the concept of feature decoupling can be introduced. Through algorithms (such as independent component analysis algorithms) or network structure design, the virtual oil level sensor can automatically separate and focus on operating parameters that are strongly correlated with lubricating oil migration from the input operating parameter samples. This improves the immunity of the final preset virtual oil level sensor to other faults such as refrigerant leakage, enabling the preset virtual oil level sensor to determine whether there is a fault in the air conditioning system.

[0035] In one alternative embodiment, please continue to refer to Figure 3 Step 011 includes: Step 0111: Input the compressor's operating parameters into the preset virtual oil level sensor to output the current oil level.

[0036] Specifically, the compressor's operating parameters, which are collected and preprocessed in real time by the acquisition device, are input into a preset virtual oil level sensor to output the current oil level. Alternatively, the compressor's operating parameters, which are collected and preprocessed in real time, can be converted into a real-time feature vector, and then this feature vector can be input into the preset virtual oil level sensor to output the current oil level.

[0037] Step 012: Determine the first return oil demand signal based on the difference between the current oil level and the preset safe oil level; The preset safe oil level is a pre-set reasonable liquid level threshold for the lubricating oil in the compressor. The first oil return demand signal is used to characterize the urgency of oil return in the compressor; optionally, the first oil return demand signal includes oil return required and oil return not required.

[0038] Specifically, a preset safe oil level is used as a benchmark to determine whether there is a shortage or overflow of oil. Based on the difference between the current oil level and the preset safe oil level (similar to a comparison), it is determined whether there is a shortage or overflow of oil, which serves as the first oil return demand signal.

[0039] In one alternative embodiment, please refer to Figure 3 Step 012 includes: Step 0121: If the difference between the current oil level and the preset safe oil level is less than zero, determine that the first return oil demand signal is required to return oil. Step 0122: If the difference between the current oil level and the preset safe oil level is greater than or equal to zero, determine that the first return oil demand signal is no return oil required.

[0040] Specifically, the difference between the current oil level and the preset safe oil level is calculated. If the difference is less than zero, it indicates that the actual estimated oil level is lower than the safety standard, and oil return is required. If the difference is not less than zero, it indicates that the actual estimated oil level meets the standard, and oil return is not required.

[0041] Step 013: Perform energy analysis on the compressor's operating parameters to determine the second oil return demand signal; The second oil return demand signal is used to characterize the urgency of compressor oil return.

[0042] Specifically, based on the principles of system energy balance and entropy production analysis, energy analysis is performed on the compressor's operating parameters to determine the changes in parameters related to the compressor's operating performance (such as output energy efficiency). Based on the changes in these parameters, it is determined whether the compressor is short of oil and whether it needs to return oil, thereby determining the second oil return demand signal.

[0043] Thus, the second oil return demand signal obtained through energy analysis can provide additional basis for accurately judging the compressor's oil return demand, thereby improving the accuracy of oil return demand judgment.

[0044] In one alternative embodiment, please continue to refer to Figure 3 Step 013 includes: Step 0131: Perform energy analysis on the compressor's operating parameters to obtain the current energy parameter values; Step 0132: Determine the second return oil demand signal based on the degree of deviation of the current energy parameter value from the preset energy parameter range.

[0045] The current energy parameter values ​​are numerical values ​​of parameters related to the compressor's operating performance, such as operating energy efficiency ratio, isentropic efficiency, and compression power consumption. The preset energy parameter range is a range of values ​​determined based on the compressor's efficiency under conditions of sufficient oil supply.

[0046] It's understandable that when the compressor has sufficient oil, its lubrication process is normal, and the compressor's operating performance, including current energy parameters (such as the energy efficiency ratio), falls within the normal range. Conversely, when the compressor is short of oil, these energy parameters become abnormal. Therefore, by monitoring whether the current energy parameters fall within the preset range, we can determine if there is an oil shortage based on the unit's energy consumption and thermal performance, thus identifying hidden oil accumulation faults. Furthermore, by assessing the degree of deviation of the current energy parameters from the preset range, we can further determine a more accurate oil return demand and obtain a precise second oil return demand signal.

[0047] In one alternative embodiment, please refer to Figure 4 Step 0132 includes: Step 01321: If the current energy parameter value is within the preset energy parameter range, determine that the second return oil demand signal is not required; Step 01322: If the current energy parameter value is not within the preset energy parameter range and the distance between it and the midpoint of the preset energy parameter range is less than the preset distance threshold, determine the second return oil demand signal as the return oil of interest. Step 01323: If the current energy parameter value is not within the preset energy parameter range and the distance between it and the midpoint of the preset energy parameter range is greater than or equal to the preset distance threshold, determine that the second return oil demand signal is an urgent return oil demand.

[0048] The second return fuel demand signal includes return fuel urgency signals in ascending order: no return fuel needed, return fuel under observation, and return fuel urgently needed. The preset distance threshold is either a default value based on experience or a user-defined value.

[0049] In this way, based on whether the current energy parameter value is within the preset energy parameter range and the degree of deviation from the preset energy parameter range, it is possible to achieve a refined identification of the return oil demand from an energy perspective.

[0050] Step 014: Determine the target return oil control strategy based on the first return oil demand signal and the second return oil demand signal; The preset return oil control strategy is a pre-defined set of return oil control logic and execution rules. Optionally, the preset return oil control strategy includes a first return oil control strategy, a second return oil control strategy, a third return oil control strategy, a fourth return oil control strategy, and a no-return oil control strategy, with the return oil intensity decreasing sequentially. The target return oil control strategy is any of the preset return oil control strategies.

[0051] Optionally, the oil return control strategy without a corresponding oil return control parameter does not exist. The other different preset oil return control strategies have different oil return control parameters and different oil return forces. The oil return control parameters are used to control the air conditioning system to return oil. The oil return control parameters may include, but are not limited to, the compressor's operating frequency, the duration of the oil return operation, and the opening degree of the electronic expansion valve. This application embodiment does not limit these parameters.

[0052] Specifically, a parameterized basic control strategy framework is pre-set for each preset oil return control strategy. Each basic control strategy framework defines the relationships between the control logic sequence (such as the opening and closing timing of each electronic expansion valve), core control parameters (such as the compressor operating frequency, the duration of oil return operation, and the opening degree of each electronic expansion valve), and the adjustment direction and weight relative to the baseline values ​​under standard operating conditions. The baseline values ​​under standard operating conditions can be obtained through theoretical modeling, experimental calibration, or digital twin simulation.

[0053] Specifically, since the first and second oil return demand signals characterize the urgency of compressor oil return from different perspectives and are obtained through different methods, they form heterogeneous and redundant sensing channels. By fusing the first and second oil return demand signals for analysis and verification, the impact of weak signal sensing and anti-interference on oil return demand can be avoided, achieving refined and continuous sensing of oil return demand. Based on this refined oil return demand, a corresponding preset oil return control strategy can be determined as the target oil return control strategy.

[0054] In one alternative embodiment, please refer to Figure 5 Step 014 includes steps 0141, 0142, 0143, 0144 and 0145, in order to achieve accurate identification of return oil demand, which will be explained in detail below.

[0055] Step 0141: When the first return oil demand signal is that return oil is needed, and the second return oil demand signal is that return oil is of concern or that return oil is urgently needed, the target return oil control strategy is determined to be the first return oil control strategy. Specifically, given the current low oil level and the need for oil return from an energy analysis perspective, both dual-channel verifications indicate the necessity of oil return. Therefore, the first oil return control strategy with the strongest return force is adopted to meet the strong oil return demand.

[0056] Step 0142: If the first oil return demand signal indicates that oil return is required and the second oil return demand signal indicates that oil return is not required, determine the target oil return control strategy based on whether there is a fault in the air conditioning system. Specifically, when the current oil level is too low, but oil return is not required from an energy analysis perspective, discrepancies arise in the dual-channel verification. In this case, relevant data collected by the acquisition device is used to determine whether there is a fault in the air conditioning system, to rule out interference faults such as sensor drift and refrigerant leakage, and then to determine the accuracy of the first oil return demand signal obtained based on the current oil level, before finally determining the final target oil return control strategy.

[0057] In one alternative embodiment, please refer to Figure 6 Step 0142 includes: Step 01421: In the event of a malfunction in the air conditioning system, determine the target oil return control strategy as an oil return-free control strategy; Step 01422: If there is no fault in the air conditioning system, determine the target oil return control strategy as the third oil return control strategy; Specifically, due to interference from a fault in the air conditioning system, the accuracy of the current oil level obtained through the preset virtual oil level sensor is insufficient. When the air conditioning system is faulty, the second oil return demand signal still indicates no oil return is needed, and it is less affected by the system fault. Therefore, based on the second oil return demand signal, the target oil return control strategy is determined to be a no-oil-return control strategy. Optionally, if a fault is determined in the air conditioning system, a control strategy that handles the corresponding fault can be implemented to eliminate the fault.

[0058] In the absence of a fault in the air conditioning system, the discrepancy between the first and second oil return demand signals cannot be explained. Therefore, a conservative third oil return control strategy with a certain oil return force is adopted as the target oil return control strategy to avoid compressor oil shortage and ensure the compressor's oil quantity and normal operation.

[0059] Step 0143: When the first return oil demand signal is no return oil required and the second return oil demand signal is return oil under scrutiny, determine the target return oil control strategy based on the changing trend of the current energy parameter value. Specifically, when the current oil level is high, but a certain amount of oil return is required from an energy analysis perspective, there are discrepancies in the dual-channel verification. In this case, the accuracy of the second oil return demand signal is verified again by analyzing the changing trend of the current energy parameter values, and then the final target oil return control strategy is determined.

[0060] In one alternative embodiment, please refer to Figure 6 Step 0143 includes: Step 01431: If the distance between the current energy parameter value and the midpoint of the preset energy parameter range continues to increase within the first preset time period, the target oil return control strategy is determined to be the fourth oil return control strategy. Step 01432: If the distance between the current energy parameter value and the midpoint of the preset energy parameter range does not continuously increase within the first preset time period, determine that the target oil return control strategy is an oil return control strategy that does not require oil return.

[0061] The first preset duration is a default value set based on experience.

[0062] Specifically, if the distance between the current energy parameter value and the midpoint of the preset energy parameter range continuously increases within a first preset time period, it indicates that the current energy parameter value is gradually moving away from the preset energy parameter, and the compressor's performance is deteriorating. Therefore, based on the second oil return demand signal, adopting a conservative fourth oil return control strategy with a certain oil return force as the target oil return control strategy, and performing preventative oil return operations can avoid excessive oil shortage in the compressor, ensuring the compressor's oil quantity and normal operation.

[0063] If the distance between the current energy parameter value and the midpoint of the preset energy parameter range does not continuously increase within the first preset time period, it indicates that the compressor performance has not deteriorated. Therefore, based on the first oil return demand signal, no oil return is required, and the target oil return control strategy is determined to be an oil return-free control strategy.

[0064] Step 0144: If the first return oil demand signal is that return oil is not needed, and the second return oil demand signal is that return oil is urgently needed, determine the target return oil control strategy as the second return oil control strategy. Specifically, given a high current oil level but an urgent need for oil return from an energy analysis perspective, although there are discrepancies in the dual-channel verification, the second oil return demand signal indicates a more urgent need for oil return. Therefore, to avoid severe wear or malfunction, an emergency second oil return control strategy with a large oil return force is adopted as the target oil return control strategy to perform emergency oil return operations, prevent the compressor from being in an excessively oil-deficient state, reduce compressor wear, and ensure the normal operation of the compressor.

[0065] Step 0145: If the first return oil demand signal is no return oil required and the second return oil demand signal is no return oil required, determine the target return oil control strategy as the no-return oil control strategy.

[0066] Specifically, given the current high oil level and the lack of need for oil return from an energy analysis perspective, both dual-channel verifications indicate that oil return is unnecessary. Therefore, the target oil return control strategy is to avoid ineffective oil return leading to excessively high oil levels in the compressor, which could result in increased power consumption, liquid slugging, and other problems, thus ensuring the compressor's service life.

[0067] In one alternative embodiment, please refer to Figure 7The oil return control method also includes steps 017 and 018, which are explained in detail below.

[0068] Step 017: Determine the safety feature vector based on the operating parameters of the air conditioning system; Step 018: Based on the safety feature vector, update the return oil control parameters corresponding to the target return oil control strategy.

[0069] Among them, the safety feature vector is used to limit the numerical range of the return oil control parameters.

[0070] It's understandable that the target oil return control strategy's corresponding oil return control parameters are adapted to general oil return operating conditions. However, different oil return operating conditions vary in actual air conditioning system operation. While fixed oil return control parameters can adapt to the corresponding general oil return operating conditions, the oil return effect is generally poor. Therefore, by combining the air conditioning system's operating parameters to dynamically optimize the oil return control parameters corresponding to the target oil return control strategy, the control logic can be better matched to the current actual operating conditions, thereby improving the oil return effect.

[0071] Specifically, the operating parameters of the air conditioning system can be acquired in real time by a data acquisition device. A pre-selected subset of parameters strongly correlated with the oil return effect (such as the compressor's ambient temperature, air conditioning system load rate, and heat exchange pipeline configuration) are input into a preset dynamic parameter optimizer. The dynamic parameter optimizer then converts these input operating parameters into a defined safety feature vector.

[0072] Then, the dynamic parameter optimizer determines the safety boundary values ​​of the oil return control parameters based on the safety feature vector, thereby optimizing and updating the oil return control parameters corresponding to the target oil return control strategy. For example, it adjusts the operating frequency of the compressor according to the ambient temperature to compensate for changes in oil viscosity, and adjusts the valve timing of electronic expansion release according to the piping configuration of the heat exchange pipeline to optimize the oil return path. In this way, the updated oil return control parameters are better adapted to the current operating conditions of the air conditioning system, thereby improving the oil return effect.

[0073] Optionally, during the execution of the target oil return control strategy, feedback data such as the compressor's oil level recovery rate and exhaust temperature can be monitored in real time. Then, by fine-tuning the oil return control parameters corresponding to the target oil return control strategy within the safety boundary corresponding to the safety feature vector, the oil return process can be ensured to be completed efficiently and safely. This achieves on-demand, adaptive, safe, and reliable intelligent closed-loop management, thereby significantly improving the energy efficiency, operational reliability, and adaptability of the air conditioning system to different application scenarios.

[0074] Step 015: Based on the target oil return control strategy, control the air conditioning system to return oil.

[0075] Specifically, based on the oil return control parameters corresponding to the target oil return control strategy (or the oil return control parameters optimized in step 018), each component in the air conditioning system is controlled to operate according to the corresponding oil return control parameters to collaboratively achieve the oil return operation. This enables precise, on-demand oil return control, improving the overall operational reliability of the air conditioning system.

[0076] In one alternative embodiment, please refer to Figure 7 The oil return control method also includes steps 019 and 020, which are explained in detail below.

[0077] Step 019: During the process of controlling the air conditioning system to return oil based on the target oil return control strategy, obtain the oil level recovery rate of the compressor; Step 020: If the oil level recovery rate is greater than the preset recovery threshold, the oil return is confirmed to be effective, and the current oil level and the corresponding compressor operating parameters are used as a set of sample data in the virtual oil level training set.

[0078] The preset recovery threshold is a default value set based on experience.

[0079] Specifically, the oil level recovery rate can be calculated in real time by receiving the oil level output from the compressor's operating parameters from a preset virtual oil level sensor. The oil level recovery rate is compared with a preset recovery threshold; if the rate exceeds the threshold, the oil return operation is considered valid. The current actual oil level and compressor operating parameters are then integrated into a sample and stored in the virtual oil level training set to continuously optimize the preset virtual oil level sensor by accumulating truly effective training data.

[0080] In this way, by accurately selecting effective training data for incremental learning, the estimation capability of the preset virtual oil level sensor can be optimized, the accuracy of oil level judgment can be improved, and thus the operational stability of the air conditioning system can be enhanced.

[0081] In one alternative embodiment, please continue to refer to Figure 7 The oil return control method also includes steps 021 and 022, which are explained in detail below.

[0082] Step 021: Based on the operating parameters of the air conditioning system during the oil return process, determine the oil return effect score. The operating parameters of the oil return process should include at least the compressor oil level recovery rate and the energy consumption of the oil return process. Step 022: If the oil return effect score is greater than the preset score threshold, store the target oil return control strategy as the oil return operation corresponding to the compressor operating parameters corresponding to the current oil level.

[0083] The oil return effect score is a numerical value that quantifies the quality of the oil return operation. The preset score threshold is a default value set based on the numerical range of the oil return effect score and experience.

[0084] Specifically, by collecting operating parameters of the air conditioning system during the oil return process (for example, the oil level recovery speed can be calculated through the real-time output of a preset virtual oil level sensor), the operating status of the compressor is determined, thereby establishing the corresponding oil return effect score. It can be understood that the faster the compressor's oil level recovers during the oil return process, the lower the energy consumption of the oil return process, resulting in a better oil return effect and a higher oil return effect score.

[0085] If the return oil performance score exceeds a preset threshold, it indicates that the target return oil control strategy executed under the current operating condition is highly efficient. The return oil control parameters corresponding to the target strategy are then bound and stored with the operating condition corresponding to the current oil level. This allows for timely retrieval and execution of the target return oil control strategy when the same operating condition is encountered again, achieving efficient return oil performance. This enables continuous personalized optimization of the return oil control strategy, improving the stability of subsequent return oil operations.

[0086] In one alternative embodiment, please continue to refer to Figure 7 The oil return control method also includes steps 023, 024 and 025, which are explained in detail below.

[0087] Step 023: Obtain the similarity of return oil demand signals and the frequency of fault alarms; The similarity of the return oil demand signals is determined based on the similarity between the first and second return oil demand signals. Specifically, if the first return oil demand signal indicates a need for return oil and the second return oil demand signal indicates a need for or urgent return oil, the similarity of the return oil demand signals is set to 100%. If the first return oil demand signal indicates no need for return oil and the second return oil demand signal also indicates no need for return oil, the similarity of the return oil demand signals is set to 100%. In other cases involving the first and second return oil demand signals, corresponding similarity values ​​for the return oil demand signals are set respectively.

[0088] The fault alarm frequency is determined by the sum of the number of air conditioning system malfunctions and the number of times abnormal operating parameters occur within a second preset time period. The second preset time period is a default value set based on experience. Specifically, within the second preset time period from the current moment, the number of times the air conditioning system malfunctions (such as refrigerant leakage, sensor drift, heat exchanger blockage, four-way valve leakage, etc.) and the number of times abnormal operating parameters occur (such as exceeding preset limits, abnormal trends, etc.) are counted. The sum of these two counts is the corresponding fault alarm frequency.

[0089] Step 024: Perform a weighted summation based on the similarity of return oil demand signals and the frequency of fault alarms to determine the health index of the air conditioning system; Among them, the health index is a quantitative value that reflects the overall health status of the air conditioning system unit.

[0090] Specifically, the similarity of the oil return demand signal and the frequency of fault alarms are each assigned a preset weight. The weighted average of the two, multiplied by 100%, yields the health index of the air conditioning system. It can be understood that a higher similarity of the oil return demand signal indicates more stable overall operation, thus resulting in a higher health index; that is, the similarity of the oil return demand signal and the health index are positively correlated. Conversely, a higher frequency of fault alarms results in a lower health index; therefore, the frequency of fault alarms and the health index are negatively correlated.

[0091] Optionally, there is an upper limit to the frequency of fault alarms. Fault alarm frequencies exceeding the upper limit are used to calculate the health index based on the upper limit. For example, if the upper limit is 10 and the fault alarm frequency calculated in step 022 is 15, then the health index will be calculated using a fault alarm frequency of 10.

[0092] Step 025: If the health index continues to decrease within the third preset time period, or if the number of fluctuations in the first preset index range and the second preset index range exceeds the preset number, generate and issue a maintenance warning message.

[0093] The third preset duration is either a default value set based on experience or a user-defined value. The first and second preset index ranges are value ranges set based on experience, and they do not overlap; the minimum value of the first preset index range is greater than the maximum value of the second preset index range. The preset number of times is either a default value set based on experience or a user-defined value. Maintenance warning information is used to remind users to check the air conditioning system.

[0094] Specifically, if the health index continues to decline within the third preset time period, or fluctuates frequently between the high value of the first preset index range and the low value of the second preset index range, it indicates that the air conditioning system's operation is gradually deteriorating or that there are potential hidden dangers. Therefore, by issuing maintenance warning messages, relevant personnel are reminded to inspect and troubleshoot the air conditioning system as soon as possible to prevent potential faults from developing into major faults and causing safety risks, thus ensuring the long-term stable operation of the air conditioning system.

[0095] Optionally, a third preset index range is set, where the maximum value of the third preset index range is less than the minimum value of the second preset index range. The first, second, and third preset index ranges correspond to different control modes.

[0096] Among them, the first preset index range with the highest health index corresponds to the preset full-function optimized control mode, which uses all intelligent optimization algorithms to optimize the oil return control parameters of the target oil return control strategy, thereby pursuing the best oil return performance and improving the energy efficiency of the air conditioning system under the premise of high safety.

[0097] Among them, the second preset index range with the health index in the middle corresponds to the preset conservative operation control mode. It adopts a hybrid control strategy that combines intelligent perception with optimized fixed rules to finely determine the oil return demand and the corresponding target oil return control strategy. It no longer optimizes the oil return control parameters of the target oil return control strategy, thereby taking into account both the oil return performance and safety of the air conditioning system.

[0098] Among them, the third preset index range with the lowest health index corresponds to the preset full-function optimized control mode, which uses a fixed duration / frequency oil return strategy to return oil in order to prioritize the overall safety of the air conditioning system.

[0099] When the health index falls within the first, second, or third preset index range, the corresponding control mode is used to implement the oil return operation. In this way, by flexibly adapting different control modes according to the health index classification, the operational reliability and overall efficiency of the air conditioning system can be improved.

[0100] All of the above technical solutions can be combined in any way to form optional embodiments of this application, and will not be described in detail here.

[0101] To facilitate better implementation of the oil return control method of this application embodiment, this application embodiment also provides an oil return control device. Please refer to... Figure 8 , Figure 8 This is a schematic diagram of the structure of a return oil control device provided in certain embodiments of this application. The return oil control device 200 includes: The first determining module 201 is used to determine the current oil level of the compressor based on the compressor's operating parameters; The second determining module 202 is used to determine the first return oil demand signal based on the difference between the current oil level and the preset safe oil level. The third determining module 203 is used to perform energy analysis on the operating parameters of the compressor and determine the second oil return demand signal. Both the first oil return demand signal and the second oil return demand signal are used to characterize the urgency of the compressor's oil return. The fourth determining module 204 is used to determine the target return oil control strategy based on the first return oil demand signal and the second return oil demand signal. The target return oil control strategy is any preset return oil control strategy. The control module 205 is used to control the air conditioning system to return oil based on the target oil return control strategy.

[0102] Each module or unit in the aforementioned oil return control device can be implemented entirely or partially through software, hardware, or a combination thereof. Each of these units can be embedded in or independent of the processor in the air conditioning system in hardware form, or stored in the memory of the air conditioning system in software form, so that the processor can call and execute the corresponding operations of each unit.

[0103] This application also provides an air conditioning system, including a compressor, a memory, and a processor; the memory stores a computer program, and the processor calls the computer program stored in the memory to implement the various processes of the above-described oil return control method embodiments, and can achieve the same technical effect. To avoid repetition, it will not be described again here.

[0104] In one alternative embodiment, please refer to Figure 9 , Figure 9 This is a schematic diagram of the structure of an air conditioning system provided in certain embodiments of this application. The air conditioning system 300 includes a compressor 301, a processor 302, and a memory 303. The compressor 301 is used to compress low-pressure gaseous refrigerant (such as difluoromethane, propane, etc.) into high-pressure, high-temperature gaseous refrigerant. The memory 303 stores a computer program 304 that can run on the processor 302. When the processor 302 executes the computer program 304, it implements the various processes of the embodiments of the above-described oil return control method and achieves the same technical effect. To avoid repetition, it will not be described again here.

[0105] Optionally, please refer to Figure 10 , Figure 10 This is a schematic diagram of the architecture of an air conditioning system provided in certain embodiments of this application. The air conditioning system includes a sensing layer, a control layer, a storage layer, an optimization layer, and an execution layer. The sensing layer includes data acquisition devices such as temperature sensors, pressure sensors, valve position sensors, and current sensors, used to collect various operating parameters of the air conditioning system.

[0106] The control layer includes an oil level status identification module, an independent monitoring module, a return oil demand arbitration processing module, and a strategy selection and parameter optimization module. The oil level status identification module outputs a first return oil demand signal based on the operating parameters collected by the sensing layer. The independent monitoring module outputs a second return oil demand signal based on the operating parameters collected by the sensing layer. The return oil demand arbitration processing module determines which return oil demand signal to follow when there is a discrepancy between the first and second return oil demand signals. The strategy selection and parameter optimization module determines the corresponding target return oil control strategy based on the return oil demand and optimizes the return oil control parameters of the target return oil control strategy.

[0107] The storage layer includes a mapping table storage module and an operational database. The mapping table storage module stores the oil return control parameters corresponding to the preset oil return control strategy. The operational database stores the real-time operational parameters collected by the air conditioning system during operation (including the oil return process).

[0108] The optimization layer includes a data comparison and analysis module, a control strategy evaluation module, a parameter adaptive adjustment module, and a mapping table optimization module. The data comparison and analysis module analyzes relevant operating parameters collected during the oil return process. The control strategy evaluation module scores the target oil return control strategy to obtain an oil return performance score. The parameter adaptive adjustment module continuously optimizes and adjusts the oil return control parameters corresponding to the target oil return control strategy to improve the oil return performance. The mapping table optimization module queries the corresponding oil return control parameters in the storage layer and then transmits the determined oil return control parameters to the strategy selection and parameter optimization module in the control layer.

[0109] The execution layer includes various components of the air conditioning system (such as the compressor, main circuit electronic expansion valve (i.e., main circuit EEV), and jet electronic expansion valve (i.e., jet EEV). The strategy selection and parameter optimization module of the control layer controls each component to operate with the corresponding return oil control parameters based on the return oil control parameters transmitted by the mapping table storage module, so as to realize the entire return oil operation process.

[0110] This application also provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, it implements the various processes of the above-described control method embodiments and achieves the same technical effect. To avoid repetition, it will not be described again here.

[0111] The processor can be the processor in the air conditioning system described in the above embodiments. The computer-readable storage medium can be a computer read-only memory (ROM), random access memory (RAM), magnetic disk, or optical disk, etc.

[0112] Computer-readable media can include computer storage media and communication media. Computer storage media includes volatile and non-volatile, removable and non-removable media implemented by any method or technology for storing information such as computer-readable instructions, data structures, program modules, or other data. Computer storage media include RAM, ROM, erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other solid-state storage technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape cassettes, magnetic tape, disk storage, or other magnetic storage devices. Of course, those skilled in the art will recognize that computer storage media are not limited to the above-mentioned types.

[0113] This application also provides a computer program product, including computer instructions that, when executed by a processor, implement the aforementioned control method. The processor may be the processor in the air conditioning system described above. When executed by the processor, the computer instructions implement various processes of the embodiments of the aforementioned control method and achieve the same technical effects; therefore, to avoid repetition, they will not be described again here.

[0114] It is understood that in the specific implementation of this application, data related to user identity or characteristics is involved. When the above embodiments of this application are applied to specific products or technologies, user permission or consent is required, and the collection, use and processing of related data must comply with the relevant laws, regulations and standards of the relevant countries and regions.

[0115] In the description of this specification, the references to terms such as "certain embodiments," "an alternative embodiment," and "exemplarily" indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0116] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order according to the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

[0117] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for controlling oil return, characterized in that, Applied to an air conditioning system, the air conditioning system including a compressor, the method includes: Based on the operating parameters of the compressor, determine the current oil level of the compressor; Based on the difference between the current oil level and the preset safe oil level, the first return oil demand signal is determined; Energy analysis is performed on the operating parameters of the compressor to determine the second oil return demand signal. Both the first and second oil return demand signals are used to characterize the urgency of the compressor's oil return. Based on the first return oil demand signal and the second return oil demand signal, a target return oil control strategy is determined, wherein the target return oil control strategy is any preset return oil control strategy. Based on the target oil return control strategy, the air conditioning system is controlled to return oil.

2. The oil return control method according to claim 1, characterized in that, Also includes: A virtual oil level training set is obtained, which includes multiple sets of compressor operating parameter samples and corresponding real oil level samples. The real oil level samples are obtained based on high-precision physical oil level sensors. The virtual oil level sensor is iteratively trained using the virtual oil level training set to obtain a trained preset virtual oil level sensor. The difference between the oil level output by the preset virtual oil level sensor after inputting a target operating parameter sample and the real oil level sample corresponding to the target operating parameter sample is less than a preset oil level threshold. The target operating parameter sample can be any of the operating parameter samples. Determining the current oil level of the compressor based on its operating parameters includes: The compressor's operating parameters are input into a preset virtual oil level sensor to output the current oil level.

3. The oil return control method according to claim 1, characterized in that, The first return oil demand signal includes those requiring return oil and those not requiring return oil; determining the first return oil demand signal based on the difference between the current oil level and the preset safe oil level includes: If the difference between the current oil level and the preset safe oil level is less than zero, the first oil return demand signal is determined to be an oil return signal. If the difference between the current oil level and the preset safe oil level is greater than or equal to zero, the first return oil demand signal is determined to be no return oil required.

4. The oil return control method according to any one of claims 1-3, characterized in that, The step of performing energy analysis on the operating parameters of the compressor to determine the second oil return demand signal includes: Energy analysis is performed on the operating parameters of the compressor to obtain the current energy parameter values; The second return oil demand signal is determined based on the degree of deviation of the current energy parameter value from the preset energy parameter range.

5. The oil return control method according to claim 4, characterized in that, The second return fuel demand signal includes return fuel urgency increasing sequentially: no return fuel needed, return fuel under observation, and return fuel urgently needed; determining the second return fuel demand signal based on the deviation of the current energy parameter value from a preset energy parameter range includes: If the current energy parameter value is within the preset energy parameter range, the second return oil demand signal is determined to be no return oil required; If the current energy parameter value is not within the preset energy parameter range and the distance between it and the midpoint of the preset energy parameter range is less than a preset distance threshold, the second return oil demand signal is determined to be a return oil of interest. If the current energy parameter value is not within the preset energy parameter range and the distance between it and the midpoint of the preset energy parameter range is greater than or equal to the preset distance threshold, the second return oil demand signal is determined to be an urgent return oil demand.

6. The oil return control method according to claim 4, characterized in that, The preset oil return control strategy includes a first oil return control strategy, a second oil return control strategy, a third oil return control strategy, a fourth oil return control strategy, and an oil return control strategy with the oil return force decreasing sequentially. The step of determining the target return oil control strategy based on the first return oil demand signal and the second return oil demand signal includes: When the first return oil demand signal indicates a need for return oil, and the second return oil demand signal indicates a focus on return oil or an urgent need for return oil, the target return oil control strategy is determined to be the first return oil control strategy. When the first oil return demand signal indicates that oil return is required, and the second oil return demand signal indicates that oil return is not required, the target oil return control strategy is determined based on whether there is a fault in the air conditioning system. When the first return oil demand signal indicates no return oil is needed, and the second return oil demand signal indicates a focus on return oil, the target return oil control strategy is determined based on the changing trend of the current energy parameter value. When the first return oil demand signal indicates that return oil is not required, and the second return oil demand signal indicates that return oil is urgently needed, the target return oil control strategy is determined to be the second return oil control strategy. If the first return oil demand signal indicates that no return oil is needed, and the second return oil demand signal indicates that no return oil is needed, then the target return oil control strategy is determined to be the no-return oil control strategy.

7. The oil return control method according to claim 6, characterized in that, The step of determining the target oil return control strategy based on whether the air conditioning system has a fault includes: In the event of a malfunction in the air conditioning system, the target oil return control strategy is determined to be the oil return-free control strategy. If there is no fault in the air conditioning system, the target oil return control strategy is determined to be the third oil return control strategy; The determination of the target oil return control strategy based on the changing trend of the current energy parameter value includes: If the distance between the current energy parameter value and the midpoint of the preset energy parameter range continues to increase within a first preset time period, the target oil return control strategy is determined to be the fourth oil return control strategy. If the distance between the current energy parameter value and the midpoint of the preset energy parameter range does not continuously increase within a first preset time period, the target oil return control strategy is determined to be the oil return-free control strategy.

8. The oil return control method according to claim 6 or 7, characterized in that, The air conditioning system also includes at least one electronic expansion valve. Different preset oil return control strategies correspond to different oil return control parameters. The oil return control parameters are used to control the air conditioning system to return oil. The oil return control parameters include the operating frequency of the compressor, the duration of the oil return operation, and the opening degree of the electronic expansion valve.

9. The oil return control method according to claim 8, characterized in that, Also includes: Based on the operating parameters of the air conditioning system, a safety feature vector is determined, which is used to limit the numerical range of the oil return control parameter. Based on the safety feature vector, update the return oil control parameters corresponding to the target return oil control strategy.

10. The oil return control method according to claim 2, characterized in that, Also includes: During the process of controlling the air conditioning system to return oil based on the target oil return control strategy, the oil level recovery rate of the compressor is obtained; If the oil level recovery rate is greater than a preset recovery threshold, the oil return is determined to be effective, and the current oil level and the corresponding operating parameters of the compressor are used as a set of sample data in the virtual oil level training set.

11. The oil return control method according to claim 1, 2, or 10, characterized in that, After controlling the air conditioning system to return oil based on the target oil return control strategy, the method further includes: Based on the operating parameters of the air conditioning system during the oil return process, an oil return effect score is determined. The operating parameters of the oil return process include at least the oil level recovery rate of the compressor and the energy consumption of the oil return process. If the oil return effect score is greater than the preset score threshold, the target oil return control strategy is stored as the oil return operation corresponding to the operating parameters of the compressor corresponding to the current oil level.

12. The oil return control method according to claim 1, characterized in that, Also includes: The similarity of the return oil demand signal and the fault alarm frequency are obtained, wherein the similarity of the return oil demand signal is determined based on the similarity between the first return oil demand signal and the second return oil demand signal, and the fault alarm frequency is determined based on the sum of the number of faults of the air conditioning system and the number of times abnormal operating parameters occur within a second preset time period. The health index of the air conditioning system is determined by weighted summation based on the similarity of the oil return demand signal and the frequency of the fault alarm. If the health index continues to decrease within a third preset time period, or if the number of fluctuations in the first preset index range and the second preset index range exceeds a preset number, a maintenance warning message is generated and issued to remind the user to inspect the air conditioning system.

13. An air conditioning system, characterized in that, It includes a compressor, a processor, and a memory; the memory stores a computer program, and the processor executes the oil return control method as described in any one of claims 1-12 by calling the computer program stored in the memory.

14. A computer-readable storage medium, characterized in that, The system contains a computer program that, when executed by a processor, implements the oil return control method as described in any one of claims 1-12.

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