Frequency conversion control method, system and logic controller for air compressor

Abstract

The present application relates to the field of air compressors, and more particularly to a variable frequency control method, system, and logic controller for air compressors. The variable frequency control method for air compressors includes presetting an air compressor outlet pressure P0 and a first pressure P1 of the air compressor when the air compressor is in a stopped state; obtaining a second pressure P2 at the air compressor outlet detected by a pressure transmitter within a preset time range, wherein the second pressure P2 is the maximum pressure value within the preset time range; obtaining a pressure comparison result based on the outlet pressure P0, the first pressure P1, and the second pressure P2, and adjusting the operating frequency of the air compressor based on the pressure comparison result. The present application has the effect of making the operating state of the air compressor system more stable during operation, thereby reducing frequent speed adjustments of the equipment and increasing the service life of the equipment.

Description

Technical Field

[0001] The present application relates to the field of air compressors, and in particular to a variable frequency control method, system, and logic controller for air compressors. Background Art

[0002] An air compressor is a device used for... Air compressors are similar in structure to... Most air compressors are reciprocating piston type, with rotating blades or screws; they primarily convert mechanical energy into gas pressure energy. Air compressors are widely used, including in household appliances, installation and maintenance equipment, and even production line preparation machinery.

[0003] The traditional compressor control methods used in pressure swing adsorption devices include: on / off control, unloading / load control, variable speed control, variable capacity control, etc. Among them, the variable speed control using a frequency converter to control the motor speed is the most energy-saving and reliable; in the related technology, taking a double-tower pressure swing adsorption nitrogen production device as an example, the air consumption required during the working process will present a non-continuous curve from large to small within the working cycle, as shown in the attached figure. Figure 4 The maximum raw gas consumption Q3 is 3 to 5 times the average raw gas consumption Q2, and the minimum raw gas consumption Q1 is 1 / 5 to 1 / 10 of the average raw gas consumption Q2.

[0004] In response to this drastically changing gas usage condition, the existing air compressor variable frequency control system is difficult to achieve ideal control effects, and the inverter adjustment is too frequent, which can easily cause damage to the motor, compressor host and inverter. Summary of the Invention

[0005] In response to the problems in the prior art, the present application provides a variable frequency control method, system and logic controller for an air compressor, which has the advantages that during operation, the system operation state is more stable and there will be no frequent unloading / loading conditions, so as to reduce frequent speed adjustment of the equipment and increase the service life of the equipment.

[0006] In a first aspect, the present application provides a variable frequency control method for an air compressor, which adopts the following technical solution:

[0007] A variable frequency control method for an air compressor comprises the following steps:

[0008] Preset the air compressor outlet pressure P0 and the first pressure P1 of the air compressor in the shutdown state;

[0009] Acquire a second pressure P2 at the air compressor outlet detected by the pressure transmitter within a preset time range, wherein the second pressure P2 is a maximum pressure value within the preset time range;

[0010] A pressure comparison result is obtained according to the outlet pressure P0, the first pressure P1 and the second pressure P2, and the operating frequency of the air compressor is adjusted according to the pressure comparison result.

[0011] Furthermore, when applied to an air compressor provided with a pressure swing adsorption device, the preset time range is the adsorption cycle of the pressure swing adsorption device.

[0012] Furthermore, the outlet pressure P0 of the air compressor outlet is lower than the first pressure P1 when the air compressor is in a stopped state.

[0013] Furthermore, obtaining a pressure comparison result according to the outlet pressure P0, the first pressure P1, and the second pressure P2 specifically includes:

[0014] When the second pressure P2 is greater than or equal to the first pressure P1, a first comparison result is obtained;

[0015] When the second pressure P2 is less than the first pressure P1 and the second pressure P2 is greater than or equal to the outlet pressure P0, a second comparison result is obtained;

[0016] When the second pressure P2 is less than the outlet pressure P0, a third comparison result is obtained.

[0017] Furthermore, the method further includes: adjusting the operating frequency of the air compressor according to the pressure comparison result, specifically including:

[0018] When the comparison result is the first comparison result, the operating frequency of the air compressor in the next adsorption cycle is reduced to reduce the exhaust volume of the air compressor;

[0019] When the comparison result is the second comparison result, the operating frequency of the air compressor in the next adsorption cycle is maintained to keep the exhaust volume of the air compressor unchanged;

[0020] When the comparison result is the third comparison result, the operating frequency of the air compressor in the next adsorption cycle is increased to increase the exhaust volume of the air compressor.

[0021] Furthermore, reducing the operating frequency of the air compressor in the next adsorption cycle specifically includes:

[0022] Obtain the pressure rise time taken for the pressure value at the air compressor outlet to rise to the first pressure P1 during the current adsorption cycle;

[0023] Obtaining a frequency reduction amplitude according to the boost duration;

[0024] According to the frequency reduction amplitude, the operating frequency of the air compressor in the next adsorption cycle is reduced.

[0025] Furthermore, the step of increasing the operating frequency of the air compressor in the next adsorption cycle specifically includes:

[0026] Get the final pressure value of the air compressor outlet at the end of the current adsorption cycle;

[0027] The frequency increase amplitude is obtained according to the difference between the end pressure value and the outlet pressure P0;

[0028] According to the frequency increase amplitude, the operating frequency of the air compressor in the next adsorption cycle is increased.

[0029] In a second aspect, the present application provides a variable frequency control system for an air compressor, which adopts the following technical solution:

[0030] A variable frequency control system for an air compressor, comprising

[0031] A pressure transmitter, configured to obtain a second pressure P2 at an outlet of the air compressor detected by the pressure transmitter within a preset time range, wherein the second pressure P2 is a maximum pressure value within the preset time range;

[0032] The controller is used to preset the outlet pressure P0 of the air compressor and the first pressure P1 of the air compressor in the shutdown state, and is also used to obtain a pressure comparison result based on the outlet pressure P0, the first pressure P1 and the second pressure P2;

[0033] The frequency converter is used to adjust the operating frequency of the air compressor according to the pressure comparison result.

[0034] In a third aspect, the present application provides a logic controller, which adopts the following technical solution:

[0035] A logic controller includes a memory, a processor, and a program stored in the memory and executable on the processor. The processor executes any one of the above-mentioned variable frequency control methods for an air compressor.

[0036] In a fourth aspect, the present application provides a computer-readable storage medium, which adopts the following technical solution:

[0037] A computer-readable storage medium stores a computer program capable of being loaded by a processor and executed by any one of the variable frequency control methods for an air compressor in the first aspect.

[0038] In summary, the present application includes the following beneficial technical effects: during the operation of the air compressor, the first pressure P1 when the air compressor is stopped is detected by the pressure transmitter and fed back to the controller, and then the controller obtains the second pressure P2 at the air compressor outlet within the preset time range and frequency range, and the second pressure P2 is the maximum pressure at the air compressor outlet within the preset time range and frequency range; then, the outlet pressure P0, the first pressure P1 and the second pressure P2 of the compressor outlet are compared, and based on the comparison result, the output frequency of the controller is adjusted to keep the output flow of the air compressor and the gas consumption of the pressure swing adsorption device stable in the next time range. This control method can achieve stable frequency operation of the frequency converter within the same adsorption cycle, reduce frequent speed regulation of the equipment, increase the service life of the equipment, and make the system operation state more stable, without frequent unloading / loading and other working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a flow chart of a variable frequency control method for an air compressor according to an embodiment of the present application.

[0040] Figure 2 This is a flow chart of a frequency conversion control method for an air compressor according to an embodiment of the present application, which is mainly used to indicate the output conditions of the controller adjusting the frequency converter.

[0041] Figure 3 This is a structural block diagram of a variable frequency control system for an air compressor according to an embodiment of the present application.

[0042] Figure 4 It is an air consumption curve diagram of a pressure swing adsorption device in the related art. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solutions and advantages of this application more clear, the following Figure 1-3 It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application.

[0044] An embodiment of the present application discloses a variable frequency control method for an air compressor.

[0045] Reference Figure 1 , including the following steps,

[0046] Step S100: Preset the air compressor outlet pressure P0 and the first pressure P1 of the air compressor in the shutdown state.

[0047] The outlet pressure P0 of the air compressor outlet is lower than the first pressure P1 when the air compressor is in a stopped state.

[0048] Step S200: obtaining a second pressure P2 at the air compressor outlet detected by a pressure transmitter within a preset time range.

[0049] The second pressure P2 is the maximum pressure value within a preset time range.

[0050] As an example, a pressure transmitter may be used to monitor the second pressure P2 at the outlet of the air compressor, and the monitored second pressure P2 may be converted into a pressure digital signal and fed back to the controller.

[0051] Specifically, when this embodiment is applied to an air compressor provided with a pressure swing adsorption device, the preset time range is the adsorption cycle of the pressure swing adsorption device.

[0052] It should also be noted that within the preset time range, the initial frequency of the air compressor also needs to be preset. The preset range of the initial frequency is usually the general operating frequency of the inverter, that is, the operating frequency that can support the start-up of the air compressor, between the minimum frequency and the maximum frequency that support the operation of the air compressor; the second pressure P2 is set to the maximum output pressure of the air compressor during the adsorption cycle and the general operating frequency.

[0053] It should be understood that the controller controls the motor speed in the air compressor and adjusts the pressure in the air compressor through the output frequency of the controller, thereby controlling the output flow of the air compressor.

[0054] Step S300: Obtain a pressure comparison result according to the outlet pressure P0, the first pressure P1 and the second pressure P2, and adjust the operating frequency of the air compressor according to the pressure comparison result.

[0055] In summary, during the operation of the air compressor, the first pressure P1 of the air compressor in the shutdown state is fed back to the controller through the preset pressure transmitter, and then the controller obtains the maximum output pressure of the air compressor during the adsorption cycle and the general working frequency, that is, the second pressure P2; then, the outlet pressure P0 of the compressor outlet, the first pressure P1 and the second pressure P2 are compared, and based on the comparison result, the output frequency of the controller is adjusted to keep the output flow of the air compressor and the gas consumption of the pressure swing adsorption device stable in the next adsorption cycle, so that the adjustment of the frequency converter tends to be stable, and in the next adsorption cycle, the output working frequency of the controller is adjusted to control the output flow of the air compressor.

[0056] Specifically, the first pressure P1 when the air compressor is shut down or unloaded is always greater than the outlet pressure P0 of the air compressor outlet, that is, the first pressure P1 is the maximum exhaust pressure of the air compressor, which is the upper limit of the exhaust pressure of the air compressor. If the pressure exceeds the first pressure P1 when the air compressor is running, the air compressor will be unloaded or shut down.

[0057] As an implementation of step S300, step S300 specifically includes the following steps.

[0058] Step S1: When the second pressure P2 is greater than or equal to the first pressure P1, a first comparison result is obtained. When the comparison result is the first comparison result, the operating frequency of the air compressor in the next adsorption cycle is reduced to reduce the exhaust volume of the air compressor.

[0059] Specifically, reducing the operating frequency of the air compressor in the next adsorption cycle specifically includes: obtaining the boost time taken for the pressure value at the air compressor outlet to rise to the first pressure P1 during the current adsorption cycle; obtaining a frequency reduction amplitude based on the boost time; and the frequency reduction amplitude reduces the operating frequency of the air compressor in the next adsorption cycle.

[0060] The frequency reduction range can be determined by establishing a mapping table including the correspondence between the boost duration and the frequency reduction range, and the shorter the boost duration, the greater the frequency reduction range.

[0061] It should be understood that when the pressure transmitter detects that the second pressure P2 is greater than or equal to the first pressure P1, the pressure of the air compressor during operation exceeds the first pressure P1, that is, during the adsorption cycle, the air compressor has produced at least one shutdown or unloading state, and the output flow of the air compressor at this time is greater than the gas consumption of the pressure swing adsorption device; the controller reduces the operating frequency of the inverter output in the next adsorption cycle based on the first comparison result, thereby reducing the exhaust volume of the air compressor output to avoid the air compression from shutting down or unloading in the next cycle.

[0062] Step S2: When the second pressure P2 is less than the first pressure P1 and the second pressure P2 is greater than or equal to the outlet pressure P0, a second comparison result is obtained. When the comparison result is the second comparison result, the operating frequency of the air compressor in the next adsorption cycle is maintained to keep the exhaust volume of the air compressor unchanged.

[0063] Furthermore, when the second pressure P2 is less than the first pressure P1 and the second pressure P2 is greater than or equal to the outlet pressure P0, a second comparison result is obtained, that is, the first pressure P1>the second pressure P2≥the outlet pressure P0; when the comparison result is the second comparison result, the controller maintains the current operating frequency output based on the second comparison result to keep the exhaust volume of the air compressor unchanged.

[0064] Specifically, when the pressure transmitter detects that the second pressure P2 is greater than or equal to the outlet pressure P0, and the second pressure P2 is less than the first pressure P1, the pressure of the air compressor does not exceed the first pressure P1 when it is running, and does not fall below the outlet pressure P0, that is, during the adsorption cycle, the air compressor is in a normal operating state, and the output flow of the air compressor and the gas consumption of the pressure swing adsorption device at this time remain stable; based on the second comparison result, the controller causes the frequency converter to output the original operating frequency of the next adsorption cycle, so that the subsequent output flow of the air compressor and the gas consumption of the pressure swing adsorption device continue to remain stable.

[0065] Step S3: When the second pressure P2 is less than the outlet pressure P0, a third comparison result is obtained. When the comparison result is the third comparison result, the operating frequency of the air compressor in the next adsorption cycle is increased to increase the exhaust volume of the air compressor.

[0066] Furthermore, when the second pressure P2 is less than the first pressure P1, and the second pressure P2 is less than the outlet pressure P0, a third comparison result is obtained, that is, the first pressure P1>outlet pressure P0>second pressure P2; when the comparison result is the third comparison result, the controller increases the output operating frequency based on the third comparison result to increase the air output of the air compressor.

[0067] Specifically, increasing the operating frequency of the air compressor in the next adsorption cycle includes: obtaining the end pressure value of the air compressor outlet at the end of the current adsorption cycle; obtaining the frequency increase amplitude based on the difference between the end pressure value and the outlet pressure P0; and increasing the operating frequency of the air compressor in the next adsorption cycle based on the frequency increase amplitude. The frequency increase amplitude can be determined by establishing a mapping table containing a correspondence between the difference and the frequency increase amplitude. The larger the difference, the larger the frequency increase amplitude. That is, when the pressure transmitter detects that the second pressure P2 is less than the outlet pressure P0, the controller needs to control the frequency converter to increase the output frequency in the next adsorption cycle. During the adsorption cycle, the difference between the second pressure P2 and the outlet pressure P0 is calculated. The larger the difference between the second pressure P2 and the outlet pressure P0, the higher the increase in the frequency converter output frequency.

[0068] In the above embodiment, during the operation of the air compressor, the first pressure P1 when the air compressor is stopped is detected by the pressure transmitter and fed back to the controller. Then, the controller obtains the maximum output pressure of the air compressor during the adsorption cycle and the general working frequency, that is, the second pressure P2, through the pressure transmitter; then, the outlet pressure P0 of the compressor outlet, the first pressure P1 and the second pressure P2 are compared. When the pressure transmitter detects that the second pressure P2 is greater than or equal to the first pressure P1, the pressure of the air compressor exceeds the first pressure P1 when it is running, that is, during the adsorption cycle, the air compressor is at a maximum pressure of 0.05. One less shutdown or unloading state is generated, and the output flow of the air compressor at this time is much greater than the gas consumption of the pressure swing adsorption device; through the first comparison result, the controller needs to control the frequency converter to reduce the output frequency in the next adsorption cycle. When the time taken for the second pressure P2 to drop to the first pressure P1 is closer to the adsorption cycle, the lower the reduction in the frequency converter output frequency is, so that the frequency of shutdown of the air compressor in the next adsorption cycle is reduced, and the subsequent output flow of the air compressor and the gas consumption of the pressure swing adsorption device are kept stable, which can reduce the frequency of shutdown of the air compressor to a certain extent and reduce the output flow of the air compressor.

[0069] When the pressure transmitter detects that the second pressure P2 is greater than or equal to the outlet pressure P0, and the second pressure P2 is less than the first pressure P1, the pressure during operation of the air compressor does not exceed the first pressure P1 and does not fall below the outlet pressure P0, that is, during the adsorption cycle, the air compressor is in a normal operating state, and the output flow of the air compressor and the gas consumption of the pressure swing adsorption device at this time remain stable; based on the second comparison result, the controller causes the frequency converter to output at the original output operating frequency, so that the air compressor operates normally, and the subsequent output flow of the air compressor and the gas consumption of the pressure swing adsorption device remain stable;

[0070] When the pressure transmitter detects the difference between the end pressure value and the outlet pressure P0, it means that during the adsorption cycle, the output flow of the air compressor at this time is far less than the gas consumption of the pressure swing adsorption device; based on the third comparison result, the controller needs to control the frequency converter to increase the output frequency during the next adsorption cycle. During the adsorption cycle, the difference between the end pressure value and the outlet pressure P0 is calculated. When the difference between the end pressure value and the outlet pressure P0 is larger, the increase in the frequency converter output frequency is higher, thereby increasing the air output of the air compressor, so that the subsequent output flow of the air compressor and the gas consumption of the pressure swing adsorption device remain stable.

[0071] The embodiment of the present application also discloses a variable frequency control system for an air compressor.

[0072] Reference Figure 3 A variable frequency control system for an air compressor is used to execute the above-mentioned variable frequency control method for an air compressor: the system comprises:

[0073] A pressure transmitter is used to obtain a second pressure P2 at the outlet of the air compressor detected by the pressure transmitter within a preset time range, wherein the second pressure P2 is a maximum pressure value within the preset time range;

[0074] The controller is used to preset the outlet pressure P0 of the air compressor and the first pressure P1 of the air compressor in the shutdown state, and is also used to obtain a pressure comparison result based on the outlet pressure P0, the first pressure P1 and the second pressure P2;

[0075] The frequency converter is used to adjust the operating frequency of the air compressor according to the pressure comparison result.

[0076] In the above embodiment, the controller is electrically connected to the frequency converter and the pressure transmitter, respectively. The frequency converter is used to output the operating frequency to rotate the motor in the air compressor and operate the air compressor, and the controller is used to control the output operating frequency of the frequency converter; and the controller is electrically connected to an HMI device, which is used to display the data received by the controller, so that the staff can monitor the output pressure value of the air compressor in real time.

[0077] In summary, the controller controls the frequency converter to output at a certain operating frequency during the adsorption cycle, so that the air compressor can operate to supply air to the pressure swing adsorption device. During the operation of the air compressor, the pressure when the air compressor stops is detected by the pressure transmitter and fed back to the controller. The controller determines whether the output flow of the air compressor can meet the gas consumption of the pressure swing adsorption device based on the preset pressure. The controller determines whether the air compressor has stopped or unloaded within this time range based on the pressure when the air compressor stops; the output operating frequency of the frequency converter is adjusted based on the judgment result, so that the subsequent output flow of the air compressor and the gas consumption of the pressure swing adsorption device remain stable, and in the subsequent operation process, the system operation state is more stable, and there will be no frequent start / stop or unloading / loading conditions, reducing switching noise, reducing failure rate, and the air compressor outlet pressure fluctuation is small, thereby improving the stability of the pressure swing adsorption device, reducing frequent speed regulation of the equipment, and increasing the service life of the equipment.

[0078] A variable frequency control system for an air compressor in an embodiment of the present application can implement any of the above-mentioned variable frequency control methods for an air compressor, and the specific working process of each module in a variable frequency control system for an air compressor can refer to the corresponding process in the above-mentioned method embodiment.

[0079] In the several embodiments provided in this application, it should be understood that the provided methods and systems can be implemented in other ways. For example, the system embodiments described above are merely illustrative; for example, the division of a module is merely a logical functional division, and in actual implementation, other division methods may be used, such as combining or integrating multiple modules into another system, or ignoring or not implementing certain features.

[0080] The embodiment of the present application also discloses a logic controller.

[0081] The logic controller includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the variable frequency control method for an air compressor as described above is implemented.

[0082] The embodiment of the present application also discloses a computer-readable storage medium.

[0083] A computer-readable storage medium stores a computer program that can be loaded by a processor and executed by any one of the above-mentioned variable frequency control methods for an air compressor.

[0084] Among them, computer-readable storage media can be any tangible medium that contains or stores a program that can be used by or in combination with an instruction execution system, apparatus or device; the program code contained on the computer-readable medium can be transmitted using any appropriate medium, including but not limited to wireless, wire, optical cable, RF, etc., or any suitable combination of the above.

[0085] It should be noted that, in the above embodiments, the description of each embodiment has different emphases. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0086] The above are all preferred embodiments of the present application and are not intended to limit the scope of protection of this application. Unless otherwise specified, any feature disclosed in this specification (including the abstract and drawings) may be replaced by other equivalent or similar features. In other words, unless otherwise specified, each feature is merely an example of a series of equivalent or similar features.

Claims

1. A frequency conversion control method for an air compressor, characterized in that: The method comprises: Preset the air compressor outlet pressure P0 and the first pressure P1 of the air compressor in the shutdown state; Acquire a second pressure P2 at the air compressor outlet detected by the pressure transmitter within a preset time range, wherein the second pressure P2 is a maximum pressure value within the preset time range; Obtaining a pressure comparison result according to the outlet pressure P0, the first pressure P1, and the second pressure P2, and adjusting the operating frequency of the air compressor according to the pressure comparison result; The pressure comparison result is obtained according to the outlet pressure P0, the first pressure P1 and the second pressure P2, specifically including: When the second pressure P2 is greater than or equal to the first pressure P1, a first comparison result is obtained; When the second pressure P2 is less than the first pressure P1 and the second pressure P2 is greater than or equal to the outlet pressure P0, a second comparison result is obtained; When the second pressure P2 is less than the outlet pressure P0, a third comparison result is obtained; The method further includes: adjusting the operating frequency of the air compressor according to the pressure comparison result, specifically comprising: When the comparison result is the first comparison result, the operating frequency of the air compressor in the next adsorption cycle is reduced to reduce the exhaust volume of the air compressor; When the comparison result is the second comparison result, the operating frequency of the air compressor in the next adsorption cycle is maintained to keep the exhaust volume of the air compressor unchanged; When the comparison result is the third comparison result, the operating frequency of the air compressor in the next adsorption cycle is increased to increase the exhaust volume of the air compressor; The step of reducing the operating frequency of the air compressor in the next adsorption cycle specifically includes: Obtain the pressure rise time taken for the pressure value at the air compressor outlet to rise to the first pressure P1 during the current adsorption cycle; Obtaining a frequency reduction amplitude according to the boost duration; According to the frequency reduction amplitude, the operating frequency of the air compressor in the next adsorption cycle is reduced; Increasing the operating frequency of the air compressor in the next adsorption cycle specifically includes: Get the final pressure value of the air compressor outlet at the end of the current adsorption cycle; The frequency increase amplitude is obtained according to the difference between the end pressure value and the outlet pressure P0; According to the frequency increase amplitude, the operating frequency of the air compressor in the next adsorption cycle is increased.

2. The frequency conversion control method for an air compressor according to claim 1, characterized in that: Applicable to an air compressor provided with a pressure swing adsorption device, the preset time range is the adsorption cycle of the pressure swing adsorption device.

3. The frequency conversion control method for an air compressor according to claim 2, characterized in that: The outlet pressure P0 of the air compressor outlet is lower than the first pressure P1 when the air compressor is in a stopped state.

4. A variable frequency control system for an air compressor, characterized in that: include A pressure transmitter, configured to obtain a second pressure P2 at an outlet of the air compressor detected by the pressure transmitter within a preset time range, wherein the second pressure P2 is a maximum pressure value within the preset time range; The controller is used to preset the outlet pressure P0 of the air compressor and the first pressure P1 of the air compressor in the shutdown state, and is also used to obtain a pressure comparison result based on the outlet pressure P0, the first pressure P1 and the second pressure P2; The frequency converter is used to adjust the operating frequency of the air compressor according to the pressure comparison result; The pressure comparison result is obtained according to the outlet pressure P0, the first pressure P1 and the second pressure P2, specifically including: When the second pressure P2 is greater than or equal to the first pressure P1, a first comparison result is obtained; When the second pressure P2 is less than the first pressure P1 and the second pressure P2 is greater than or equal to the outlet pressure P0, a second comparison result is obtained; When the second pressure P2 is less than the outlet pressure P0, a third comparison result is obtained; The method further includes adjusting the operating frequency of the air compressor according to the pressure comparison result, specifically including: When the comparison result is the first comparison result, the operating frequency of the air compressor in the next adsorption cycle is reduced to reduce the exhaust volume of the air compressor; When the comparison result is the second comparison result, the operating frequency of the air compressor in the next adsorption cycle is maintained to keep the exhaust volume of the air compressor unchanged; When the comparison result is the third comparison result, the operating frequency of the air compressor in the next adsorption cycle is increased to increase the exhaust volume of the air compressor; The step of reducing the operating frequency of the air compressor in the next adsorption cycle specifically includes: Obtain the pressure rise time taken for the pressure value at the air compressor outlet to rise to the first pressure P1 during the current adsorption cycle; Obtaining a frequency reduction amplitude according to the boost duration; According to the frequency reduction amplitude, the operating frequency of the air compressor in the next adsorption cycle is reduced; Increasing the operating frequency of the air compressor in the next adsorption cycle specifically includes: Get the final pressure value of the air compressor outlet at the end of the current adsorption cycle; The frequency increase amplitude is obtained according to the difference between the end pressure value and the outlet pressure P0; According to the frequency increase amplitude, the operating frequency of the air compressor in the next adsorption cycle is increased.

5. A logic controller, characterized in that: The invention comprises a memory, a processor and a program stored in the memory and executable on the processor, wherein the processor executes a variable frequency control method for an air compressor as claimed in any one of claims 1 to 3.

6. A computer-readable storage medium, characterized in that The method comprises storing a computer program capable of being loaded by a processor and executing the method according to any one of claims 1 to 3.

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