Compressor oil return control method, device and unit

Abstract

The application discloses a compressor oil return control method, device and unit. The method comprises the following steps: after the compressor is started and runs stably, when the rising value of the motor current meets a first preset condition, the frequency and speed of the compressor are reduced until the motor current is stable; after the motor current is stable for a preset time, the oil return mode is started; when the falling value of the motor current meets a second preset condition, the frequency and speed of the compressor are increased until the motor current is stable, and the oil return mode is exited. When the oil return mode is exited, the motor current is detected, and when the rising value of the motor current meets the first preset condition, the frequency and speed of the compressor are reduced again. The application provides a compressor automatic oil return control scheme based on current detection control, can automatically control the oil return operation time and the oil return interval time according to the motor current change, and not only can ensure that the compressor is not short of oil, but also can avoid the working efficiency reduction caused by the frequent oil return of the compressor.

Description

Technical Field

[0001] This invention relates to the field of compressor control technology, and more specifically, to a compressor oil return control method, device, and unit. Background Technology

[0002] Oil return in compressors is typically achieved by installing an oil separator. However, oil separators have a limited oil separation rate and cannot completely separate the lubricating oil. Therefore, after a period of operation, the unit needs to undergo a lubricating oil separation and regeneration process. This allows the liquid refrigerant to flush away the lubricating oil adhering to the pipe walls and carry it back to the gas-liquid separator.

[0003] Determining the time interval and duration of each oil return cycle is crucial for successful oil return operation. However, many factors influence oil return, such as the diameter of the gas-liquid pipe, the performance of the oil-gas separator, outdoor temperature, and refrigerant charge. Traditional methods involve manually setting fixed oil return intervals and cycle durations, which cannot accurately estimate the impact of various factors. Therefore, an automatic control method for compressor oil return operation is needed.

[0004] There is currently no effective solution to the problem that existing technologies cannot accurately determine the compressor oil return operation time and oil return interval time. Summary of the Invention

[0005] This invention provides a compressor oil return control method, device, and unit to solve the problem in the prior art that the compressor oil return operation time and oil return interval time cannot be accurately determined.

[0006] To address the aforementioned technical problems, this invention provides a compressor oil return control method, comprising: after the compressor starts and reaches stable operation, if the increase in motor current meets a first preset condition, performing a frequency reduction and speed reduction operation on the compressor until the motor current stabilizes; after the motor current stabilizes for a preset time, activating the oil return mode; if the decrease in motor current meets a second preset condition, performing a frequency increase and speed increase operation on the compressor until the motor current stabilizes, and exiting the oil return mode; detecting the motor current when exiting the oil return mode, and if the increase in motor current meets the first preset condition again, performing a frequency reduction and speed reduction operation on the compressor.

[0007] Furthermore, the method also includes:

[0008] After the compressor starts, it operates at a preset low frequency.

[0009] After detecting that the motor current is within the preset range and tends to stabilize, the compressor is subjected to frequency increase and speed-up operation until the motor current stabilizes.

[0010] Furthermore, after the compressor starts and reaches stable operation, the increase in motor current is detected to meet the first preset condition, including:

[0011] After the compressor starts up and reaches stable operation, the current motor current is obtained as the first reference current I1;

[0012] If the increase in motor current reaches the increase threshold of the first reference current I1 and is maintained for a preset duration, then the first preset condition is confirmed to be met.

[0013] Furthermore, detecting a decrease in motor current to meet a second preset condition includes:

[0014] The motor current when the oil return mode is activated is used as the second reference current I2;

[0015] If the decrease in motor current reaches the decrease threshold of the second reference current I2 and remains so for a preset duration, then the second preset condition is confirmed to be met.

[0016] Furthermore, after exiting the oil return mode, the method further includes:

[0017] Record the motor current when exiting the oil return mode, and use it as the new first reference current I1.

[0018] Furthermore, obtaining the current motor current as the first reference current I1 includes:

[0019] Set the sampling period;

[0020] The average value of the multiple effective values ​​of motor current detected within the sampling period is taken as the first reference current I1.

[0021] Furthermore, obtaining the motor current when the oil return mode is activated as the second reference current I2 includes:

[0022] Set the sampling period;

[0023] The average value of the multiple effective values ​​of motor current detected within the sampling period is taken as the second reference current I2.

[0024] The present invention also provides a compressor oil return control device, wherein the device comprises:

[0025] The first control module is used to detect that the increase in motor current meets the first preset condition after the compressor starts up and runs stably, and then perform frequency reduction and speed reduction operation on the compressor until the motor current stabilizes.

[0026] The second control module is used to start the oil return mode after the motor current has stabilized for a preset time; after detecting that the decrease in motor current meets the second preset condition, it performs frequency increase and speed-up operation on the compressor until the motor current stabilizes and then exits the oil return mode.

[0027] The circulation module is used to detect the motor current when exiting the oil return mode. After the increase in the motor current meets the first preset condition, the compressor is subjected to frequency reduction and speed reduction operation again.

[0028] The present invention also provides a unit, wherein the unit includes the above-described compressor oil return control device.

[0029] The present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein the program, when executed by a processor, implements the method as described above.

[0030] The present invention provides an automatic oil return control scheme for compressors based on current detection control, which solves the problem in the prior art that the compressor oil return running time and oil return interval time cannot be accurately determined. It can automatically control the oil return running time and oil return interval time according to the changes in motor current, which not only prevents the compressor from running out of oil, but also avoids the reduction in working efficiency caused by frequent oil return of the compressor. Attached Figure Description

[0031] Figure 1 This is a flowchart of a compressor oil return control method according to an embodiment of the present invention;

[0032] Figure 2 This is a flowchart of the compressor startup and operation process according to an embodiment of the present invention;

[0033] Figure 3 This is a flow chart of the compressor oil return operation according to an embodiment of the present invention;

[0034] Figure 4 This is a structural block diagram of a compressor oil return control device according to an embodiment of the present invention. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0036] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.

[0037] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0038] It should be understood that although the terms first, second, third, etc., may be used to describe preset conditions in the embodiments of the present invention, these preset conditions should not be limited to these terms. These terms are only used to distinguish preset conditions. For example, without departing from the scope of the embodiments of the present invention, the first preset condition may also be referred to as the second preset condition, and similarly, the second preset condition may also be referred to as the first preset condition.

[0039] Depending on the context, the words “if” or “suppose” as used here can be interpreted as “when” or “in response to determination” or “in response to detection.” Similarly, depending on the context, the phrases “if determination” or “if detection (of the stated condition or event)” can be interpreted as “when determination” or “in response to determination” or “when detection (of the stated condition or event)” or “in response to detection (of the stated condition or event).”

[0040] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device that includes said element.

[0041] The optional embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0042] Example 1

[0043] According to an embodiment of the present invention, a method embodiment for compressor oil return control is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0044] Figure 1 This is a flowchart of a compressor oil return control method according to an embodiment of the present invention, such as... Figure 1 As shown, the method includes the following steps:

[0045] Step S101: After the compressor starts up and runs stably, if the increase in motor current meets the first preset condition, the compressor is subjected to frequency and speed reduction operation until the motor current stabilizes.

[0046] Specifically, after the compressor starts up and reaches stable operation, the current motor current is obtained as the first reference current I1; if the increase value of the motor current reaches the increase threshold of the first reference current I1 and is maintained for a preset time, it is confirmed that the first preset condition is met.

[0047] Step S102: After the motor current has stabilized for a preset time, start the oil return mode.

[0048] In the oil return mode, the refrigerant can fully dissolve the lubricating oil in the pipe wall and carry it back to the oil separator during heating or cooling operation.

[0049] Step S103: After detecting that the decrease in motor current meets the second preset condition, the compressor is subjected to frequency increase and speed-up operation until the motor current stabilizes and the oil return mode is exited.

[0050] Step S104: Detect the motor current when exiting the oil return mode. After the increase in the motor current meets the first preset condition, perform frequency reduction and speed reduction operation on the compressor again.

[0051] Specifically, the motor current when the oil return mode is activated is obtained as the second reference current I2; if the decrease in motor current reaches the decrease threshold of the second reference current I2 and is maintained for a preset duration, it is confirmed that the second preset condition is met.

[0052] This embodiment provides an automatic oil return control scheme for compressors based on current detection control, which solves the problem in the prior art that the compressor oil return running time and oil return interval time cannot be accurately determined. It can automatically control the oil return running time and oil return interval time according to the changes in motor current, which not only prevents the compressor from running out of oil, but also avoids the reduction in working efficiency caused by frequent oil return of the compressor.

[0053] In this embodiment, when setting the first and second preset conditions and performing certain control operations, it is necessary to ensure that the motor current is in a stable state (e.g., maintained for a preset duration) to prevent accidental oil return or cessation of oil return due to current fluctuations. This also ensures the accuracy of current detection. When determining current stability, the variance of the effective current value over a period of time can be calculated to determine whether the current is stable.

[0054] The compressor oil return control scheme described above is implemented after the compressor has been running stably. When the compressor is first started, considering that the compressor has not been running for a long time, the lubricating oil will have deposited and its temperature will be low. Direct operation would damage the mechanical structure. Therefore, the motor is first controlled to run at a low speed to raise the oil temperature and ensure sufficient lubrication of the mechanical structure. Based on this, this embodiment provides a preferred implementation method: after the compressor starts, it runs at a preset low frequency; after detecting that the motor current is within a preset range and tends to stabilize, the compressor is subjected to a frequency increase and speed-up operation until the motor current stabilizes.

[0055] Figure 2 This is a flowchart of the compressor startup and operation process according to an embodiment of the present invention, such as... Figure 2 As shown, the process includes the following steps: After the compressor starts, it first runs at a preset low frequency to ensure sufficient lubrication. Once the motor current amplitude is within a reasonable range and tends to stabilize, the compressor speed is increased and the frequency is raised until stable operation. If the motor current amplitude is not within a reasonable range and tends to stabilize, it continues to run at the preset low frequency. When the compressor has not been running for a long time, the lubricating oil will accumulate and the temperature will be low. If it is run directly, it will damage the mechanical structure. Therefore, the motor is first run at a low speed to raise the oil temperature and ensure that the lubricating oil fully lubricates the mechanical structure.

[0056] For normal operating conditions, the above control can effectively adjust the oil return interval and oil return operation time. However, for higher frequency operating conditions, a minimum oil return interval can be set to avoid frequent oil returns affecting compressor efficiency. After exiting the oil return mode, the motor current at the time of exiting the oil return mode is recorded as the new first reference current I1. Then, a new round of oil return operation begins.

[0057] Because the real-time current sampling frequency is very high, a sampling period can be set. The average of multiple effective motor current values ​​detected within the sampling period is used as the first reference current I1. The average of multiple effective motor current values ​​detected within the sampling period is used as the second reference current I2. The reference current values ​​obtained in this way are more accurate. When detecting motor current, sampling can also be performed within the period, and the average value is used as the detection result.

[0058] This embodiment avoids directly influencing the oil return process based on factors such as the pipe diameter of the gas-liquid pipe, the performance of the oil-gas separator, outdoor temperature, and refrigerant charge. Instead, it comprehensively considers their impact on oil quantity and thus on the compressor's mechanical structure. The oil return process is directly controlled by controlling the motor current. Specifically, it includes the following control logic:

[0059] 1) Logic for determining oil return during startup

[0060] To prevent excessive wear and overheating of the compressor, the compressor is initially run at a lower frequency after the motor starts. Based on the real-time sampled current value, the average value of the effective current within n times the current cycle is calculated to determine whether the average current is within a reasonable threshold range and stable. If the condition is met, the speed and frequency are increased; otherwise, the oil return continues.

[0061] 2) Logic for determining oil return during operation

[0062] When the compressor is short of oil, the motor current will increase due to the increased mechanical wear of the compressor. Based on the real-time sampled current value, the average value of the effective current within n times the current cycle is calculated. The average current is compared with the threshold current. If it is greater, the oil return process is started; otherwise, the operation continues.

[0063] 3) Stop the return oil logic

[0064] As the compressor gradually receives lubrication, the motor current decreases accordingly. Based on the real-time sampled current value, the average value of the effective current within n times the current cycle is calculated. The average current is compared to the threshold current. If it is less than the threshold current, the oil return process is stopped; otherwise, the oil return continues.

[0065] Figure 3 This is a flow chart of the compressor oil return operation according to an embodiment of the present invention, such as... Figure 3 As shown, the process includes the following steps:

[0066] In step S301, after the motor is running stably, the influence of factors such as the pipe diameter of the gas-liquid pipe, the refrigerant charge, and the performance of the oil-gas separator on the compressor's operating status is fixed. At this point, the motor current is recorded as reference current 1. Even if these factors may cause some lubricating oil residue on the pipe wall, we only care about whether the compressor can operate normally, and record the current value under normal operating conditions.

[0067] In step S302, due to various factors affecting the oil level, the compressor gradually begins to run out of oil, increasing wear on its mechanical structure and consequently increasing the mechanical load on the motor, leading to a gradual increase in motor current. When the current exceeds the reference current 1 increase threshold (which can be set manually, for example, by increasing by 1% or 2%), and after stabilizing for a period of time, the compressor frequency and speed are reduced.

[0068] In step S303, when the motor is running stably at a low oil return frequency, the motor current at this time is recorded as reference current 2, and then the compressor starts to return oil.

[0069] In step S304, as the lubricating oil is gradually replenished, the mechanical wear of the compressor gradually decreases, and the corresponding motor current gradually decreases. When the motor current reaches the reduction threshold of the reference current 2 (which can be set by the user, for example, a reduction of 1% or 2%), and stabilizes for a period of time, the compressor frequency is increased and the speed is increased.

[0070] Step S305: After the compressor speed-up is completed and the operation stabilizes, record the stable current value under the current operating conditions. Wait for the minimum oil return interval time before starting sampling and comparison to ensure the stability of the compressor operation and thus ensure efficient and stable compressor operation. For general operating conditions, the above control can effectively adjust the oil return interval time and oil return running time. However, for higher frequency operating conditions, a minimum oil return interval time can be set to avoid frequent oil returns affecting the compressor's operating efficiency.

[0071] In this embodiment, when recording the motor current as the reference current, the reference current value calculated by the speed error via the PI controller is used as the comparison threshold.

[0072] Example 2

[0073] Corresponding to Figure 1 The compressor oil return control method described in this embodiment also provides a device for evaluating the performance of the unit, such as... Figure 4 The block diagram of the compressor oil return control device shown is shown. The device includes:

[0074] The first control module 10 is used to perform frequency reduction and speed reduction operation on the compressor after the compressor starts up and runs stably, and after detecting that the increase value of the motor current meets the first preset condition, until the motor current stabilizes.

[0075] The second control module 20 is connected to the first control module 10. It is used to start the oil return mode after the motor current has stabilized for a preset time; after detecting that the decrease in motor current meets the second preset condition, it performs frequency increase and speed-up operation on the compressor until the motor current stabilizes and then exits the oil return mode.

[0076] The circulation module 30, connected to the second control module 20, is used to detect the motor current when exiting the oil return mode. After the increase in the motor current meets the first preset condition, the compressor is subjected to frequency and speed reduction operation again. That is, the action of the first control module 10 is retried.

[0077] This embodiment also provides a unit, wherein the unit includes the compressor oil return control device described above.

[0078] The compressor oil return control device in this embodiment can realize an automatic oil return control scheme for compressors based on current detection control. The specific control scheme has been described in detail above and will not be repeated here. It can solve the problem in the prior art that the compressor oil return running time and oil return interval time cannot be accurately determined. It can automatically control the oil return running time and oil return interval time according to the changes in motor current, which not only prevents the compressor from running out of oil, but also avoids the reduction in working efficiency caused by frequent oil returns of the compressor.

[0079] Example 3

[0080] This embodiment provides an electronic device for a method of controlling oil return in a compressor. The electronic device includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein...

[0081] The memory stores instructions executable by the one processor, which are executed by the at least one processor to enable the at least one processor to:

[0082] After the compressor starts up and runs stably, once the rise in motor current meets the first preset condition, the compressor is subjected to frequency and speed reduction operation until the motor current stabilizes.

[0083] After the motor current has stabilized for a preset time, start the oil return mode;

[0084] Once the decrease in motor current meets the second preset condition, the compressor is subjected to frequency and speed-up operation until the motor current stabilizes and the oil return mode is exited.

[0085] Example 4

[0086] This invention provides software for executing the technical solutions described in the above embodiments and preferred embodiments.

[0087] This invention provides a non-volatile computer storage medium storing computer-executable instructions that can execute the compressor oil return control method in any of the above method embodiments.

[0088] The aforementioned storage medium stores the aforementioned software, and the storage medium includes, but is not limited to, optical discs, floppy disks, hard disks, and rewritable memory.

[0089] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0090] In the above embodiments of the present invention, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0091] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of units can be a logical functional division, and in actual implementation, there may be other division methods. For instance, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling, direct coupling, or communication connection may be through some interfaces; the indirect coupling or communication connection between units or modules may be electrical or other forms.

[0092] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0093] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0094] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.

[0095] The above-described product can execute the method provided in the embodiments of the present invention, and has the corresponding functional modules and beneficial effects for executing the method. Technical details not described in detail in this embodiment can be found in the method provided in the embodiments of the present invention.

[0096] The electronic devices of this invention exist in various forms, including but not limited to:

[0097] (1) Mobile communication devices: These devices are characterized by their mobile communication capabilities and primarily aim to provide voice and data communication. These terminals include: smartphones (e.g., iPhones), multimedia phones, feature phones, and low-end phones, etc.

[0098] (2) Ultra-mobile personal computer devices: These devices fall under the category of personal computers, possessing computing and processing capabilities, and generally also have mobile internet access features. These terminals include PDAs, MIDs, and UMPCs, such as the iPad.

[0099] (3) Portable entertainment devices: These devices can display and play multimedia content. This category includes audio and video players (such as iPods), handheld game consoles, e-book readers, as well as smart toys and portable car navigation devices.

[0100] (4) Server: A device that provides computing services. The components of a server include a processor, hard disk, memory, device bus, etc. Servers are similar to general computer architectures, but because they need to provide highly reliable services, they have higher requirements in terms of processing power, stability, reliability, security, scalability, and manageability.

[0101] (5) Other electronic devices with data interaction functions, such as televisions and in-vehicle screens.

[0102] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0103] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A compressor oil return control method, characterized in that, The method includes: After the compressor starts up and runs stably, once the rise in motor current meets the first preset condition, the compressor is subjected to frequency and speed reduction operation until the motor current stabilizes. After the motor current has stabilized for a preset time, start the oil return mode; Once the decrease in motor current meets the second preset condition, the compressor is subjected to frequency increase and speed boost operation until the motor current stabilizes and the oil return mode is exited. The motor current is detected when exiting the oil return mode. After the increase in the motor current meets the first preset condition, the compressor is subjected to frequency reduction and speed reduction operation again. The detection of the rise in motor current meeting the first preset condition includes: after the compressor starts and runs stably, obtaining the current motor current as the first reference current I1; if the rise in motor current reaches the rise threshold of the first reference current I1 and is maintained for a preset time, then it is confirmed that the first preset condition is met. The detection of the reduction of motor current to meet the second preset condition includes: acquiring the motor current when the oil return mode is turned on as the second reference current I2; if the reduction value of the motor current reaches the reduction threshold of the second reference current I2 and is maintained for a preset time, then it is confirmed that the second preset condition is met.

2. The method according to claim 1, characterized in that, The method further includes: After the compressor starts, it operates at a preset low frequency. After detecting that the motor current is within the preset range and tends to stabilize, the compressor is subjected to frequency increase and speed-up operation until the motor current stabilizes.

3. The method according to claim 1, characterized in that, After exiting the oil return mode, the method further includes: Record the motor current when exiting the oil return mode, and use it as the new first reference current I1.

4. The method according to claim 1, characterized in that, Obtaining the current motor current as the first reference current I1 includes: Set the sampling period; The average value of the multiple effective values ​​of motor current detected within the sampling period is taken as the first reference current I1.

5. The method according to claim 1, characterized in that, The motor current when the oil return mode is activated is obtained as the second reference current I2, including: Set the sampling period; The average value of the multiple effective values ​​of motor current detected within the sampling period is taken as the second reference current I2.

6. A compressor oil return control device, used to implement the compressor oil return control method as described in any one of claims 1 to 5, characterized in that, The device includes: The first control module is used to detect that the increase in motor current meets the first preset condition after the compressor starts up and runs stably, and then perform frequency reduction and speed reduction operation on the compressor until the motor current stabilizes. The second control module is used to start the oil return mode after the motor current has stabilized for a preset time; after detecting that the decrease in motor current meets the second preset condition, it performs frequency increase and speed-up operation on the compressor until the motor current stabilizes and then exits the oil return mode. The circulation module is used to detect the motor current when exiting the oil return mode. After the increase in the motor current meets the first preset condition, the compressor is subjected to frequency reduction and speed reduction operation again.

7. A generator unit, characterized in that, The unit includes the compressor oil return control device as described in claim 6.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the method as described in any one of claims 1 to 5.

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