Constant pressure control method, device, equipment and medium for variable frequency air compressor

Abstract

The present application discloses a constant pressure control method, device, equipment and medium for a variable frequency air compressor, belonging to the technical field of variable frequency air compressors. The method includes: detecting the operating pressure value of the variable frequency air compressor in real time. If the operating pressure value is greater than or equal to the first preset threshold, the target pressure value is dynamically set according to the first preset threshold and the set pressure value. At the same time, based on the principle that the target pressure value gradually approaches the set pressure value with the change of the adjustment time, and according to the PID algorithm, the variable frequency air compressor is subjected to constant pressure control according to the target pressure value; when the operating pressure value is greater than or equal to the sum of the unloading pressure value and the third preset threshold, or the duration for which the operating pressure value is greater than or equal to the unloading pressure value is greater than or equal to the preset delay duration, pressure unloading is performed on the variable frequency air compressor. This method can ensure the stable and reliable operation of the variable frequency air compressor, and can also ensure that the variable frequency air compressor can quickly enter the constant pressure operation state.

Description

Technical Field

[0001] The present invention relates to the technical field of variable frequency air compressors, and in particular to a constant pressure control method, device, equipment and medium for variable frequency air compressors. Background Art

[0002] Variable frequency air compressors are usually composed of air compressors, pressure sensors, frequency converters and control panels. Existing variable frequency air compressors can directly use the PID (Proportion Integral Differential) function of the frequency converter to achieve constant pressure control of the variable frequency air compressor and meet the application needs of most users. This is because the pressure difference of most variable frequency air compressors is relatively large. The pressure difference here refers to the difference between the set pressure value and the unloading pressure value on the variable frequency air compressor. Among them, the set pressure value refers to the pressure value that the variable frequency air compressor will eventually reach, and the unloading pressure value refers to the upper limit of the operating pressure of the variable frequency air compressor. Once the operating pressure value of the variable frequency air compressor reaches the unloading pressure value, the variable frequency air compressor will adjust the valve and automatically unload the pressure, thereby avoiding the explosion caused by excessive pressure in the gas tank in the variable frequency air compressor.

[0003] However, in actual applications, there are sometimes some application scenarios with small pressure differences. For example, the set pressure value of the variable frequency air compressor is 0.78Mpa, and the unloading pressure value is 0.80Mpa. Since the pressure difference of the variable frequency air compressor is only 0.02Mpa, once the variable frequency air compressor has an overshoot of 0.02Mpa during the PID adjustment process, the variable frequency air compressor will reach the unloading pressure point and pressure unload the variable frequency air compressor. When the operating pressure value of the variable frequency air compressor drops to the loading pressure point, the variable frequency air compressor will reload the pressure. After the variable frequency air compressor reloads the pressure, once the overshoot of the variable frequency air compressor exceeds 0.02Mpa or more of the set pressure value of the variable frequency air compressor, the variable frequency air compressor will adjust back and forth between the unloading pressure point and the loading pressure point, and cannot reach a stable state. In the prior art, although the overshoot of the variable frequency air compressor can be suppressed to a certain extent by adjusting the differential link of the PID, and the variable frequency air compressor will not trigger the unloading pressure point of the variable frequency air compressor when performing PID adjustment, this method will cause the dynamic response of the variable frequency air compressor to be slow and cannot meet the application requirements of users. At present, there is no more effective solution to the above technical problems.

[0004] It can be seen that how to ensure the stable and reliable operation of the variable frequency air compressor and ensure that the variable frequency air compressor can quickly enter the constant pressure operation state is a technical problem that needs to be urgently solved by technical personnel in this field. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a constant pressure control method, device, equipment and medium for a variable frequency air compressor, so as to ensure that the variable frequency air compressor can reach a stable operating state while also ensuring that the variable frequency air compressor can quickly enter the constant pressure operating state. The specific solutions are as follows:

[0006] A constant pressure control method for a variable frequency air compressor, comprising:

[0007] Real-time detect the operating pressure value of the variable frequency air compressor, and determine whether the operating pressure value is greater than or equal to a first preset threshold; wherein, the difference between the set pressure value and the unloading pressure value of the variable frequency air compressor is less than a second preset threshold; the first preset threshold is greater than the loading pressure value of the variable frequency air compressor;

[0008] If the operating pressure value is greater than or equal to the first preset threshold, dynamically set a target pressure value according to the first preset threshold and the set pressure value, and at the same time, based on the principle that the target pressure value gradually approaches the set pressure value as the adjustment time changes, and according to the PID algorithm, perform constant pressure control on the variable frequency air compressor according to the target pressure value;

[0009] When the operating pressure value is greater than or equal to the sum of the unloading pressure value and a third preset threshold, or the duration for which the operating pressure value is greater than or equal to the unloading pressure value is greater than or equal to a preset delay duration, perform pressure unloading on the variable frequency air compressor.

[0010] Preferably, the process of dynamically setting a target pressure value according to the first preset threshold and the set pressure value, and at the same time, based on the principle that the target pressure value gradually approaches the set pressure value as the adjustment time changes, and performing constant pressure control on the variable frequency air compressor according to the PID algorithm and the target pressure value includes:

[0011] Set a pressure increment according to the difference between the first preset threshold and the set pressure value;

[0012] Taking i equal to 1 as the initial value, set the target pressure value according to the target model and the pressure increment, and perform constant pressure control on the variable frequency air compressor according to the PID algorithm and the target pressure value, and at the same time time the duration of the constant pressure control to obtain a target duration;

[0013] Determine whether the target duration is greater than or equal to a preset duration;

[0014] If the target duration is greater than or equal to the preset duration, increment the value of i by 1 in sequence, and continue to execute the step of setting the target pressure value according to the target model and the pressure increment, and performing constant pressure control on the variable frequency air compressor according to the target pressure value according to the PID algorithm, while timing the duration of the constant pressure control to obtain the target duration, until the target pressure value is equal to the set pressure value;

[0015] Among them, the expression of the pressure increment is:

[0016] ΔP = (P2 - P a ) / N; 2 ≤ N ≤ 10;

[0017] The expression of the target model is:

[0018] P j = P a + i * ΔP;

[0019] In the formula, ΔP is the pressure increment, P2 is the set pressure value, P a is the first preset threshold, and P j is the target pressure value.

[0020] Preferably, after the process of judging whether the target duration is greater than or equal to the preset duration, it further includes:

[0021] If the target duration is less than the preset duration, continue to execute the step of real-time detecting the operating pressure value of the variable frequency air compressor.

[0022] Preferably, after the process of real-time detecting the operating pressure value of the variable frequency air compressor, it further includes:

[0023] Judge whether the operating pressure value is greater than or equal to the loading pressure value;

[0024] If the operating pressure value is greater than or equal to the loading pressure value, continue to execute the step of judging whether the operating pressure value is greater than or equal to the first preset threshold;

[0025] If the operating pressure value is less than the loading pressure value, perform constant pressure control on the variable frequency air compressor based on the PID algorithm and according to the set pressure value.

[0026] Preferably, it further includes:

[0027] When the operating pressure value is greater than or equal to the loading pressure value, calculate the pressure change rate of the variable frequency air compressor according to the preset period to obtain the target change rate, and set the preset duration according to the target change rate.

[0028] Preferably, when the operating pressure value is greater than or equal to the sum of the unloading pressure value and a third preset threshold, or the duration for which the operating pressure value is greater than or equal to the unloading pressure value is greater than or equal to a preset delay duration, the process of performing pressure unloading on the variable-frequency air compressor includes:

[0029] Determine whether the operating pressure value is less than the sum of the unloading pressure value and the third preset threshold;

[0030] If the operating pressure value is greater than or equal to the sum of the unloading pressure value and the third preset threshold, perform pressure unloading on the variable-frequency air compressor, and continue to execute the step of continuously detecting the operating pressure value of the variable-frequency air compressor;

[0031] If the operating pressure value is less than the sum of the unloading pressure value and the third preset threshold, determine whether the operating pressure value is greater than or equal to the unloading pressure value;

[0032] If the operating pressure value is less than the unloading pressure value, continue to execute the step of continuously detecting the operating pressure value of the variable-frequency air compressor;

[0033] If the operating pressure value is greater than or equal to the unloading pressure value, time the duration for which the operating pressure value is greater than or equal to the unloading pressure value to obtain an overload duration, and determine whether the overload duration is greater than or equal to the preset delay duration;

[0034] If the overload duration is greater than or equal to the preset delay duration, perform pressure unloading on the variable-frequency air compressor, and continue to execute the step of continuously detecting the operating pressure value of the variable-frequency air compressor.

[0035] Preferably, after the process of determining whether the overload duration is greater than or equal to the preset delay duration, it further includes:

[0036] If the overload duration is less than the preset delay duration, clear the overload duration, and continue to execute the step of continuously detecting the operating pressure value of the variable-frequency air compressor.

[0037] Correspondingly, the present invention also discloses a constant-pressure control device for a variable-frequency air compressor, including:

[0038] A pressure detection module, configured to continuously detect the operating pressure value of the variable-frequency air compressor and determine whether the operating pressure value is greater than or equal to a first preset threshold; wherein, the difference between the set pressure value and the unloading pressure value of the variable-frequency air compressor is less than a second preset threshold; the first preset threshold is greater than the loading pressure value of the variable-frequency air compressor;

[0039] A pressure regulation module, which is configured to, if the operating pressure value is greater than or equal to the first preset threshold, dynamically set a target pressure value according to the first preset threshold and the set pressure value. Meanwhile, based on the principle that the target pressure value gradually approaches the set pressure value as the adjustment time changes, and according to the PID algorithm, perform constant pressure control on the variable frequency air compressor according to the target pressure value;

[0040] A pressure unloading module, which is configured to perform pressure unloading on the variable frequency air compressor when the operating pressure value is greater than or equal to the sum of the unloading pressure value and the third preset threshold, or when the duration for which the operating pressure value is greater than or equal to the unloading pressure value is greater than or equal to a preset delay duration.

[0041] Correspondingly, the present invention also discloses a constant pressure control device for a variable frequency air compressor, including:

[0042] A memory, which is configured to store a computer program;

[0043] A processor, which is configured to implement the steps of a constant pressure control method for a variable frequency air compressor as disclosed above when executing the computer program.

[0044] Correspondingly, the present invention also discloses a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of a constant pressure control method for a variable frequency air compressor as disclosed above are implemented.

[0045] It can be seen that in the present invention, first, the operating pressure value of the variable-frequency air compressor is detected in real time, and it is determined whether the operating pressure value is greater than or equal to the first preset threshold; if the operating pressure value of the variable-frequency air compressor is greater than or equal to the first preset threshold, the target pressure value is dynamically set according to the first preset threshold and the set pressure value. At the same time, based on the principle that the target pressure value gradually approaches the set pressure value as the adjustment time changes, and according to the PID algorithm, the variable-frequency air compressor is subjected to constant-pressure control according to the target pressure value. When the operating pressure value of the variable-frequency air compressor is greater than or equal to the sum of the unloading pressure value and the third preset threshold, or the duration for which the operating pressure value of the variable-frequency air compressor is greater than or equal to the unloading pressure value is greater than or equal to the preset delay duration, the pressure of the variable-frequency air compressor is unloaded. Compared with the prior art, in the application scenario of a variable-frequency air compressor with a small pressure difference, since it is not necessary to adjust the PID differential link of the variable-frequency air compressor, but by predicting in advance the change of the operating pressure value of the variable-frequency air compressor and intervening in the constant-pressure adjustment process of the set pressure value of the variable-frequency air compressor to adjust the operating process of the variable-frequency air compressor, the pressure adjustment process of the variable-frequency air compressor can be made more gentle and stable, and the phenomenon of overshoot of the variable-frequency air compressor can be suppressed. Thus, it can be ensured that the variable-frequency air compressor can quickly enter the constant-pressure operation state. At the same time, an unloading pressure delay protection mechanism for the variable-frequency air compressor is added in this method, which can prevent to a certain extent the phenomenon that the variable-frequency air compressor immediately unloads the pressure due to overshoot during the pressure regulation process. Thus, the stability and reliability of the variable-frequency air compressor during operation can be further ensured. Correspondingly, a constant-pressure control device, equipment and medium for a variable-frequency air compressor provided by the present invention also have the above beneficial effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0047] Figure 1 It is a flowchart of a constant-pressure control method for a variable-frequency air compressor provided by an embodiment of the present invention;

[0048] Figure 2 It is a schematic diagram of the principle of a constant-pressure control method for a variable-frequency air compressor provided by an embodiment of the present invention;

[0049] Figure 3 It is a flowchart of another constant-pressure control method for a variable-frequency air compressor provided by an embodiment of the present invention;

[0050] Figure 4Flow chart of a method for unloading pressure delay protection of a variable frequency air compressor provided by an embodiment of the present invention;

[0051] Figure 5 Structural diagram of a constant pressure control device of a variable frequency air compressor provided by an embodiment of the present invention;

[0052] Figure 6 Structural diagram of a constant pressure control device of a variable frequency air compressor provided by an embodiment of the present invention. Detailed implementation manners

[0053] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0054] Please refer to Figure 1 , Figure 1 Flow chart of a constant pressure control method of a variable frequency air compressor provided by an embodiment of the present invention. The method includes:

[0055] Step S11: Real-time detect the operating pressure value of the variable frequency air compressor, and determine whether the operating pressure value is greater than or equal to a first preset threshold; wherein, the difference between the set pressure value and the unloading pressure value of the variable frequency air compressor is less than a second preset threshold; the first preset threshold is greater than the loading pressure value of the variable frequency air compressor;

[0056] Step S12: If the operating pressure value is greater than or equal to the first preset threshold, dynamically set a target pressure value according to the first preset threshold and the set pressure value, and at the same time, based on the principle that the target pressure value gradually approaches the set pressure value as the adjustment time changes, and according to the PID algorithm, perform constant pressure control on the variable frequency air compressor according to the target pressure value;

[0057] Step S13: When the operating pressure value is greater than or equal to the sum of the unloading pressure value and a third preset threshold, or the duration for which the operating pressure value is greater than or equal to the unloading pressure value is greater than or equal to a preset delay duration, perform pressure unloading on the variable frequency air compressor.

[0058] In this embodiment, a constant pressure control method for a variable frequency air compressor is provided. Using this method, not only can it ensure that the variable frequency air compressor can reach a stable operating state, but also it can ensure that the variable frequency air compressor can quickly enter the constant pressure operating state.

[0059] In this method, first, the operating pressure value P of the variable frequency air compressor is detected in real time real , and it is determined whether the operating pressure value P of the variable frequency air compressor realIs it greater than or equal to the first preset threshold P a ; wherein, the difference between the set pressure value P2 and the unload pressure value P3 of the variable frequency air compressor is less than the second preset threshold, and this feature indicates that the variable frequency air compressor is operating in an application scenario with a small pressure difference. And the first preset threshold P a is greater than the load pressure value P1 of the variable frequency air compressor.

[0060] When the operating pressure value P of the variable frequency air compressor real is greater than or equal to the first preset threshold P a , it indicates that the operating pressure value P of the variable frequency air compressor real is greater than the pressure value at the pressure regulation inlet point of the variable frequency air compressor. In this case, in order to avoid overshoot of the variable frequency air compressor and the occurrence of pressure unloading. At this time, it is necessary to dynamically set the target pressure value according to the first preset threshold P a and the set pressure value P2 of the variable frequency air compressor. At the same time, based on the principle that the target pressure value gradually approaches the set pressure value as the adjustment time changes, and according to the PID algorithm, the variable frequency air compressor is subjected to constant pressure control according to the target pressure value. It should be noted that, according to the first preset threshold P a and the set pressure value P2 of the variable frequency air compressor, the target pressure value is dynamically set, and according to the PID algorithm, the variable frequency air compressor is subjected to constant pressure control according to the target pressure value. Under this setting mechanism, the target pressure value refers to the operating pressure value that the variable frequency air compressor finally needs to reach.

[0061] By setting in this way, it is equivalent to predicting the pressure change situation of the variable frequency air compressor in advance during the operation of the variable frequency air compressor, and adjusting the set pressure value of the constant pressure operation set for the variable frequency air compressor according to the pressure change situation of the variable frequency air compressor. Based on the principle that the target pressure value gradually approaches the set pressure value as the adjustment time changes, and according to the PID algorithm, the variable frequency air compressor is subjected to constant pressure control according to the target pressure value, which is equivalent to making the operating pressure value that the variable frequency air compressor finally needs to reach gradually approach the set pressure value. That is, the variable frequency air compressor finally operates at a constant pressure with the set pressure value. By this method, the pressure adjustment process of the variable frequency air compressor can be made more gentle and stable, and the overshoot phenomenon of the variable frequency air compressor can be suppressed. At the same time, it can also ensure that the variable frequency air compressor will not trigger the unloading pressure point and cause the situation of unloading pressure. Obviously, since this method does not require adjustment and modification of the differential link in the PID adjustment, but directly predicts and intervenes in the constant pressure adjustment process of the variable frequency air compressor, therefore, this method can ensure that the variable frequency air compressor can enter the constant pressure operation state more quickly.

[0062] If the software program implementing the above variable frequency air compressor constant pressure control method is stored in the pressure adjustment strategy module of the variable frequency air compressor, then the result will be as shown in Figure 2Schematic diagram of the operating principle of the variable-frequency air compressor shown. Please refer to Figure 2 , Figure 2 This is a schematic diagram of the principle of a constant-pressure control method for a variable-frequency air compressor provided by an embodiment of the present invention. When the variable-frequency air compressor is in a normal operating state, the variable-frequency air compressor performs PID control according to the set pressure value. During this process, the operating pressure value of the variable-frequency air compressor is fed back in real time. When the operating pressure value of the variable-frequency air compressor is greater than or equal to the first preset threshold, the operating pressure value of the variable-frequency air compressor is adjusted according to the method from step S11 to step S13, and finally the variable-frequency air compressor can reach a constant-pressure operating state.

[0063] When the operating pressure value P of the variable-frequency air compressor real is greater than or equal to the sum of the unloading pressure value P3 and the third preset threshold P y , or the duration for which the operating pressure value P of the variable-frequency air compressor real is greater than or equal to the unloading pressure value P3 is greater than or equal to the preset delay duration T d , the pressure of the variable-frequency air compressor is unloaded. This is equivalent to adding a delay protection mechanism for the unloading pressure of the variable-frequency air compressor in the constant-pressure control method of the variable-frequency air compressor.

[0064] It can be imagined that when the operating pressure value P of the variable-frequency air compressor real is greater than or equal to the unloading pressure value P3, because there is a preset delay duration T d , then when the variable-frequency air compressor reaches the unloading pressure point, the variable-frequency air compressor will not immediately unload the pressure, but when the duration for which the operating pressure value P of the variable-frequency air compressor real is greater than or equal to the unloading pressure value P3 is greater than or equal to the preset delay duration T d , the pressure of the variable-frequency air compressor will be unloaded. And when the variable-frequency air compressor just overshoots to the unloading pressure value, since the variable-frequency air compressor is in a dynamic adjustment process at this time, the operating pressure value P of the variable-frequency air compressor real can quickly drop below the unloading pressure value P3 again, and the duration for which the variable-frequency air compressor is at the unloading pressure value P3 is smaller than the preset delay duration T d , thus ensuring that the variable-frequency air compressor will not unload the pressure due to triggering the unloading pressure point. In addition, when the operating pressure value P of the variable-frequency air compressor real is greater than or equal to the sum of the unloading pressure value P3 and the third preset threshold P y , the pressure of the variable-frequency air compressor is directly unloaded, so as to avoid the safety hazard of the variable-frequency air compressor exploding due to excessive air tank pressure, thus ensuring the safe and stable operation of the variable-frequency air compressor.

[0065] It can be seen that in this embodiment, first, the operating pressure value of the variable-frequency air compressor is detected in real time, and it is judged whether the operating pressure value is greater than or equal to the first preset threshold; if the operating pressure value of the variable-frequency air compressor is greater than or equal to the first preset threshold, the target pressure value is dynamically set according to the first preset threshold and the set pressure value. At the same time, based on the principle that the target pressure value gradually approaches the set pressure value as the adjustment time changes, and according to the PID algorithm, the variable-frequency air compressor is subjected to constant-pressure control according to the target pressure value. When the operating pressure value of the variable-frequency air compressor is greater than or equal to the sum of the unloading pressure value and the third preset threshold, or the duration for which the operating pressure value of the variable-frequency air compressor is greater than or equal to the unloading pressure value is greater than or equal to the preset delay duration, the pressure of the variable-frequency air compressor is unloaded. Compared with the prior art, in the application scenario of a variable-frequency air compressor with a small pressure difference, since it is not necessary to adjust the PID differential link of the variable-frequency air compressor, but to anticipate the change of the operating pressure value of the variable-frequency air compressor in advance and intervene in the constant-pressure adjustment process of the set pressure value of the variable-frequency air compressor to adjust the operating process of the variable-frequency air compressor, the pressure adjustment process of the variable-frequency air compressor can be made more gentle and stable, and the phenomenon of overshoot of the variable-frequency air compressor can be suppressed. Thus, it can be ensured that the variable-frequency air compressor can quickly enter the constant-pressure operation state. At the same time, an unloading pressure delay protection mechanism for the variable-frequency air compressor is added in this method, which can prevent the phenomenon that the variable-frequency air compressor immediately unloads the pressure due to overshoot during the pressure regulation process to a certain extent. Thus, the stability and reliability of the variable-frequency air compressor during operation can be further ensured.

[0066] Based on the above embodiment, this embodiment further explains and optimizes the technical solution. As a preferred implementation manner, the above steps: dynamically setting the target pressure value according to the first preset threshold and the set pressure value, and at the same time, based on the principle that the target pressure value gradually approaches the set pressure value as the adjustment time changes, and performing constant-pressure control on the variable-frequency air compressor according to the target pressure value according to the PID algorithm, include:

[0067] Set the pressure increment according to the difference between the first preset threshold and the set pressure value;

[0068] Taking i equal to 1 as the initial value, set the target pressure value according to the target model and the pressure increment, perform constant-pressure control on the variable-frequency air compressor according to the target pressure value according to the PID algorithm, and at the same time, time the duration of the constant-pressure control to obtain the target duration;

[0069] Judge whether the target duration is greater than or equal to the preset duration;

[0070] If the target duration is greater than or equal to the preset duration, then increment the value of i by 1 in sequence, and continue to execute the steps of setting the target pressure value according to the target model and the pressure increment, performing constant pressure control on the variable frequency air compressor according to the target pressure value using the PID algorithm, and simultaneously timing the duration of the constant pressure control to obtain the target duration, until the target pressure value is equal to the set pressure value;

[0071] Among them, the expression of the pressure increment is:

[0072] ΔP = (P2 - P a ) / N; 2 ≤ N ≤ 10;

[0073] The expression of the target model is:

[0074] P j = P a + i * ΔP;

[0075] In the formula, ΔP is the pressure increment, P2 is the set pressure value, P a is the first preset threshold, P j is the target pressure value.

[0076] In this embodiment, the constant pressure control process of the variable frequency air compressor is specifically described. When the operating pressure value P real of the variable frequency air compressor is greater than or equal to the first preset threshold P a , first, set the pressure increment ΔP according to the difference between the first preset threshold P a and the set pressure value P2. At the same time, take i = 1 as the initial value, set the target pressure value according to the target model and the pressure increment, perform constant pressure control on the variable frequency air compressor according to the target pressure value using the PID algorithm, and simultaneously time the duration of the constant pressure control to obtain the target duration. If the target duration is greater than or equal to the preset duration, then increment the value of i by 1 in sequence, and continue to execute the steps of setting the target pressure value according to the target model and the pressure increment, performing constant pressure control on the variable frequency air compressor according to the target pressure value using the PID algorithm, and simultaneously timing the duration of the constant pressure control to obtain the target duration, until the target pressure value is equal to the set pressure value. In this way, it is equivalent to dividing the constant pressure operation process of the variable frequency air compressor into N-stage adjustment processes, thereby ensuring that the pressure adjustment process of the variable frequency air compressor becomes more gentle and stable, suppressing the overshoot phenomenon of the variable frequency air compressor, and at the same time ensuring that the variable frequency air compressor will not trigger the unloading pressure point and cause pressure unloading.

[0077] If the target duration is less than the preset duration, it means that the variable frequency air compressor will not have an overshoot phenomenon temporarily and will not trigger the unloading pressure point. In this case, it is only necessary to continue to detect the operating pressure value of the variable frequency air compressor in real time.

[0078] As a preferred embodiment, after the above step of detecting the operating pressure value of the variable-frequency air compressor in real time, the method further includes:

[0079] Determine whether the operating pressure value is greater than or equal to the loading pressure value;

[0080] If the operating pressure value is greater than or equal to the loading pressure value, continue to execute the step of determining whether the operating pressure value is greater than or equal to the first preset threshold;

[0081] If the operating pressure value is less than the loading pressure value, perform constant pressure control on the variable-frequency air compressor based on the PID algorithm and according to the set pressure value.

[0082] When the operating pressure value P of the variable-frequency air compressor is detected in real time real In order to accurately know the operating state of the variable-frequency air compressor, it is also possible to first determine whether the operating pressure value P of the variable-frequency air compressor real is greater than the loading pressure value P1 of the variable-frequency air compressor. If the operating pressure value P of the variable-frequency air compressor real is greater than or equal to the loading pressure value P1 of the variable-frequency air compressor, then continue to determine whether the operating pressure value P of the variable-frequency air compressor real is greater than or equal to the first preset threshold P a ; if the operating pressure value P of the variable-frequency air compressor real is less than the loading pressure value P1 of the variable-frequency air compressor, then directly perform constant pressure control on the variable-frequency air compressor based on the PID algorithm and according to the pressure set value P2.

[0083] As a preferred embodiment, the above constant pressure control method further includes:

[0084] When the operating pressure value is greater than or equal to the loading pressure value, calculate the pressure change rate of the variable-frequency air compressor according to a preset period to obtain a target change rate, and set a preset duration according to the target change rate.

[0085] In practical applications, the pressure adjustment duration of the variable-frequency air compressor can also be adjusted according to the pressure change rate of the variable-frequency air compressor. Specifically, when the operating pressure value of the variable-frequency air compressor is greater than or equal to the loading pressure value of the variable-frequency air compressor, the pressure change rate of the variable-frequency air compressor can be calculated according to a preset period to obtain a target change rate, and the preset duration can be set according to the target change rate.

[0086] If the pressure change rate of the variable-frequency air compressor is greater than the preset pressure change rate threshold, it means that the pressure of the variable-frequency air compressor rises rapidly. At this time, the value of the preset duration can be set to be larger; if the pressure change rate of the variable-frequency air compressor is less than or equal to the preset pressure change rate threshold, it means that the pressure of the variable-frequency air compressor rises slowly. At this time, the value of the preset duration can be set to be smaller.

[0087] In order to enable those skilled in the art to clearly understand the implementation principle of the variable-frequency air compressor provided by this application, here, a detailed description of the constant-pressure control method provided by this application is given through an application scenario example. It should be noted that when performing constant-pressure control on the variable-frequency air compressor in this scenario, the following operating parameters are preset in advance. That is, the load pressure value of the variable-frequency air compressor is set to P1, the set pressure value of the variable-frequency air compressor is set to P2, the unloading pressure value of the variable-frequency air compressor is set to P3, and the first preset threshold is set to P a ; the preset pressure change rate threshold of the variable-frequency air compressor is set to P s . At the same time, in this embodiment, the constant-pressure control process of the variable-frequency air compressor is equally divided into 4 stages, and the target pressure values of the variable-frequency air compressor are respectively set to P a + ΔP, P a + 2*ΔP, P a + 3*ΔP and P2, and the constant-pressure adjustment time for each stage is t1, t2, t3, and t4 respectively.

[0088] Please refer to Figure 3 Figure 3 , which is a flowchart of another constant-pressure control method for a variable-frequency air compressor provided by an embodiment of the present invention. The method includes:

[0089] Step S101: Real-time detect the operating pressure value P real ;

[0090] Step S102: Determine whether the operating pressure value P real of the variable-frequency air compressor is greater than or equal to the load pressure value P1 of the variable-frequency air compressor;

[0091] Step S103: If the operating pressure value P real of the variable-frequency air compressor is less than the load pressure value P1 of the variable-frequency air compressor, then based on the PID algorithm, perform constant-pressure control on the variable-frequency air compressor according to the set pressure value P2;

[0092] Step S104: If the operating pressure value P real of the variable-frequency air compressor is greater than or equal to the load pressure value P1 of the variable-frequency air compressor, then calculate the pressure change rate of the variable-frequency air compressor according to the preset period to obtain the target change rate P d , and determine whether the target change rate P d is less than the preset pressure change rate threshold P s ;

[0093] Step S105: If the target change rate P d is less than the preset pressure change rate threshold P s , then set the time multiplier K to 1;

[0094] Step S106: If the target change rate P d is greater than or equal to the preset pressure change rate threshold P s , then set the time magnification factor K to 2;

[0095] Step S107: Determine whether the operating pressure value P of the variable-frequency air compressor real is greater than or equal to the first preset threshold P a ; if the operating pressure value P of the variable-frequency air compressor real is less than the first preset threshold P a , then continue to execute the step of constant pressure control of the variable-frequency air compressor based on the PID algorithm according to the set pressure value P2;

[0096] Step S108: If the operating pressure value P of the variable-frequency air compressor real is greater than or equal to the first preset threshold P a , then set the target pressure value to P a +ΔP, and perform constant pressure control on the variable-frequency air compressor according to P a +ΔP based on the PID algorithm, and at the same time time the duration of the constant pressure control to obtain the timing time T1;

[0097] Step S109: Determine whether the timing time T1 is greater than or equal to K*t1; if the timing time T1 is less than the preset duration K*t1, then continue to execute Step S101: Real-time detect the operating pressure value of the variable-frequency air compressor;

[0098] Step S110: If the timing time T1 is greater than or equal to K*t1, then set the target pressure value to P a +2*ΔP, and perform constant pressure control on the variable-frequency air compressor according to P a +2*ΔP based on the PID algorithm, and at the same time time the duration of the constant pressure control to obtain the timing time T2;

[0099] Step S111: Determine whether the timing time T2 is greater than or equal to K*t2; if the timing time T2 is less than the preset duration K*t2, then continue to execute Step S101: Real-time detect the operating pressure value of the variable-frequency air compressor;

[0100] Step S112: If the timing time T2 is greater than or equal to K*t2, then set the target pressure value to P a +3*ΔP, and perform constant pressure control on the variable-frequency air compressor according to P a +3*ΔP based on the PID algorithm, and at the same time time the duration of the constant pressure control to obtain the timing time T3;

[0101] Step S113: Determine whether the timing time T3 is greater than or equal to K*t3; if the timing time T3 is less than the preset duration K*t3, then continue to execute Step S101: Continuously detect the operating pressure value of the variable frequency air compressor; if the timing time T3 is greater than or equal to K*t3, then continue to execute the step of performing constant pressure control on the variable frequency air compressor based on the PID algorithm and according to the set pressure value P2.

[0102] Obviously, through the technical solution provided by this embodiment, the pressure adjustment process of the variable frequency air compressor can be made more gentle and stable, and the phenomenon of overshoot of the variable frequency air compressor can be suppressed. Thus, it can be ensured that the variable frequency air compressor can quickly enter the constant pressure operation state.

[0103] Based on the above embodiment, this embodiment further explains and optimizes the technical solution. Please refer to Figure 4 , Figure 4 is a flowchart of a method for unloading pressure delay protection of a variable frequency air compressor provided by an embodiment of the present invention. As a preferred implementation manner, the above step: when the operating pressure value is greater than or equal to the sum of the unloading pressure value and the third preset threshold, or the duration for which the operating pressure value is greater than or equal to the unloading pressure value is greater than or equal to the preset delay duration, then the process of performing pressure unloading on the variable frequency air compressor includes:

[0104] Step S301: Determine whether the operating pressure value P real is less than the sum of the unloading pressure value P3 and the third preset threshold P y ;

[0105] Step S302: If the operating pressure value P real is greater than or equal to the sum of the unloading pressure value P3 and the third preset threshold P y , then perform pressure unloading on the variable frequency air compressor, and continue to execute Step S11: Continuously detect the operating pressure value of the variable frequency air compressor;

[0106] Step S303: If the operating pressure value P real is less than the sum of the unloading pressure value P3 and the third preset threshold P y , then determine whether the operating pressure value P real is greater than or equal to the unloading pressure value P3; if the operating pressure value P real is less than the unloading pressure value P3, then continue to execute Step S11: Continuously detect the operating pressure value P of the variable frequency air compressor real ;

[0107] Step S304: If the operating pressure value P real is greater than or equal to the unloading pressure value P3, then time the duration for which the operating pressure value P real is greater than or equal to the unloading pressure value P3 to obtain the overload duration T cnt, and determine the overload duration T cnt whether it is greater than or equal to the preset delay duration T d ; if the overload duration T cnt is greater than or equal to the preset delay duration T d , then perform pressure unloading on the variable frequency air compressor, and continue to execute step S11: continuously detect the operating pressure value P of the variable frequency air compressor real .

[0108] In this embodiment, a specific description is given to the unloading pressure delay protection mechanism of the variable frequency air compressor provided in this application. During the operation of the variable frequency air compressor, it will continuously determine whether the operating pressure value P of the variable frequency air compressor real is less than the sum of the unloading pressure value P3 and the third preset threshold P y ; if the operating pressure value P of the variable frequency air compressor real is greater than or equal to the sum of the unloading pressure value P3 and the third preset threshold P y , it indicates that the pressure borne by the air tank in the variable frequency air compressor is relatively large, and it is very likely to cause the variable frequency air compressor to explode. At this time, it is necessary to perform pressure unloading on the variable frequency air compressor, and continue to execute step S11: continuously detect the operating pressure value of the variable frequency air compressor.

[0109] If the operating pressure value P of the variable frequency air compressor real is less than the sum of the unloading pressure value P3 and the third preset threshold P y , then determine whether the operating pressure value P of the variable frequency air compressor real is greater than or equal to the unloading pressure value P3. If the operating pressure value P of the variable frequency air compressor real is less than the unloading pressure value P3, then continue to execute step S11: continuously detect the operating pressure value P of the variable frequency air compressor real ; if the operating pressure value P of the variable frequency air compressor real is greater than or equal to the unloading pressure value P3, then time the duration for which the operating pressure value P of the variable frequency air compressor real is greater than or equal to the unloading pressure value P3 to obtain the overload duration T cnt , and determine whether the overload duration T cnt is greater than or equal to the preset delay duration T d ; if the overload duration T cnt is greater than or equal to the preset delay duration T d , it indicates that the pressure borne by the air tank in the variable frequency air compressor is relatively large, and it is very likely to cause the variable frequency air compressor to explode. At this time, it is necessary to perform pressure unloading on the variable frequency air compressor, and continue to execute step S11: continuously detect the operating pressure value of the variable frequency air compressor.

[0110] As a preferred implementation manner, the above step: determine whether the overload duration T cnt is greater than or equal to the preset delay duration Td After the process, it further includes:

[0111] Step S305: If the overload duration T cnt is less than the preset delay duration T d , then clear the overload duration T cnt , and continue to execute Step S11: Continuously detect the operating pressure value P of the variable-frequency air compressor real .

[0112] If the overload duration T cnt is less than the preset delay duration T d , it indicates that the variable-frequency air compressor just overshoots to the unloading pressure point at this time. However, since the variable-frequency air compressor is in the dynamic adjustment stage, the operating pressure value of the variable-frequency air compressor can quickly drop below the unloading pressure point. In this case, only clear the overload duration T cnt , and continue to execute Step S11: Continuously detect the operating pressure value of the variable-frequency air compressor.

[0113] Obviously, through the technical solution provided by this embodiment, the phenomenon that the variable-frequency air compressor immediately unloads the pressure due to overshoot during the pressure regulation process can be prevented to a certain extent. Therefore, through this delay protection mechanism, the overall stability of the variable-frequency air compressor during operation can be further ensured.

[0114] Please refer to Figure 5 , Figure 5 , which is the structural diagram of a constant pressure control device for a variable-frequency air compressor provided by an embodiment of the present invention. The device includes:

[0115] A pressure detection module 21, configured to continuously detect the operating pressure value of the variable-frequency air compressor and determine whether the operating pressure value is greater than or equal to a first preset threshold; wherein, the difference between the set pressure value and the unloading pressure value of the variable-frequency air compressor is less than a second preset threshold; the first preset threshold is greater than the loading pressure value of the variable-frequency air compressor;

[0116] A pressure regulation module 22, configured to, if the operating pressure value is greater than or equal to the first preset threshold, dynamically set a target pressure value according to the first preset threshold and the set pressure value, and at the same time, based on the principle that the target pressure value gradually approaches the set pressure value as the adjustment time changes, and perform constant pressure control on the variable-frequency air compressor according to the target pressure value according to the PID algorithm;

[0117] A pressure unloading module 23, configured to unload the pressure of the variable-frequency air compressor when the operating pressure value is greater than or equal to the sum of the unloading pressure value and a third preset threshold, or when the duration for which the operating pressure value is greater than or equal to the unloading pressure value is greater than or equal to the preset delay duration.

[0118] The constant pressure control device of a variable frequency air compressor provided by an embodiment of the present invention has the beneficial effects of the constant pressure control method of a variable frequency air compressor disclosed above.

[0119] Please refer to Figure 6 , Figure 6 which is a structural diagram of a constant pressure control device of a variable frequency air compressor provided by an embodiment of the present invention. The device includes:

[0120] A memory 31 for storing a computer program;

[0121] A processor 32 for implementing the steps of the constant pressure control method of a variable frequency air compressor disclosed above when executing the computer program.

[0122] The constant pressure control device of a variable frequency air compressor provided by an embodiment of the present invention has the beneficial effects of the constant pressure control method of a variable frequency air compressor disclosed above.

[0123] Correspondingly, an embodiment of the present invention further provides a computer-readable storage medium. A computer program is stored on the computer-readable storage medium, and when the computer program is executed by a processor, the steps of the constant pressure control method of a variable frequency air compressor disclosed above are implemented.

[0124] The computer-readable storage medium provided by an embodiment of the present invention has the beneficial effects of the constant pressure control method of a variable frequency air compressor disclosed above.

[0125] In this specification, the various embodiments are described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. The same or similar parts among the various embodiments can be referred to each other. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple. For the relevant parts, please refer to the description in the method part.

[0126] Finally, it should also be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover a non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0127] The above has introduced in detail a constant pressure control method, device, equipment and medium of a variable frequency air compressor provided by the present invention. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A constant pressure control method for a variable frequency air compressor, characterized in that, Including: Real-time detecting the operating pressure value of a variable-frequency air compressor, and judging whether the operating pressure value is greater than or equal to a first preset threshold value; wherein, the difference between the set pressure value and the unloading pressure value of the variable-frequency air compressor is less than a second preset threshold value; the first preset threshold value is greater than the loading pressure value of the variable-frequency air compressor; If the operating pressure value is greater than or equal to the first preset threshold value, dynamically setting a target pressure value according to the first preset threshold value and the set pressure value, and at the same time, based on the principle that the target pressure value gradually approaches the set pressure value as the adjustment time changes, and performing constant-pressure control on the variable-frequency air compressor according to the PID algorithm and in accordance with the target pressure value; When the operating pressure value is greater than or equal to the sum of the unloading pressure value and a third preset threshold value, or the duration for which the operating pressure value is greater than or equal to the unloading pressure value is greater than or equal to a preset delay duration, performing pressure unloading on the variable-frequency air compressor; The process of dynamically setting a target pressure value according to the first preset threshold value and the set pressure value, and at the same time, based on the principle that the target pressure value gradually approaches the set pressure value as the adjustment time changes, and performing constant-pressure control on the variable-frequency air compressor according to the PID algorithm and in accordance with the target pressure value, includes: Setting a pressure increment according to the difference between the first preset threshold value and the set pressure value; Taking i = 1 as the initial value, setting the target pressure value according to the target model and the pressure increment, performing constant-pressure control on the variable-frequency air compressor according to the PID algorithm and in accordance with the target pressure value, and at the same time timing the duration of the constant-pressure control to obtain a target duration; Judging whether the target duration is greater than or equal to a preset duration; If the target duration is greater than or equal to the preset duration, successively adding 1 to the value of i as the step size, and continuing to execute the step of setting the target pressure value according to the target model and the pressure increment, performing constant-pressure control on the variable-frequency air compressor according to the PID algorithm and in accordance with the target pressure value, and at the same time timing the duration of the constant-pressure control to obtain a target duration, until the target pressure value is equal to the set pressure value; Wherein, the expression of the pressure increment is: ΔP = (P2 - P a ) / N; 2 ≤ N ≤ 10; The expression of the target model is: P j = P a + i * ΔP; where ΔP is the pressure increment, P2 is the set pressure value, and P a is the first preset threshold, and P j is the target pressure value.

2. The constant pressure control method according to claim 1, wherein After the process of judging whether the target duration is greater than or equal to the preset duration, it further includes: If the target duration is less than the preset duration, continuing to execute the step of real-time detecting the operating pressure value of the variable-frequency air compressor.

3. The constant voltage control method according to claim 1, characterized in that After the process of real-time detecting the operating pressure value of the variable-frequency air compressor, it further includes: Judging whether the operating pressure value is greater than or equal to the loading pressure value; If the operating pressure value is greater than or equal to the loading pressure value, continuing to execute the step of judging whether the operating pressure value is greater than or equal to the first preset threshold value; If the operating pressure value is less than the loading pressure value, performing constant-pressure control on the variable-frequency air compressor based on the PID algorithm and in accordance with the set pressure value.

4. The constant voltage control method according to claim 3, characterized in that Also including: When the operating pressure value is greater than or equal to the loading pressure value, calculate the pressure change rate of the variable frequency air compressor according to a preset period to obtain a target change rate, and set the preset duration according to the target change rate.

5. The constant pressure control method according to claim 1, characterized in that, When the operating pressure value is greater than or equal to the sum of the unloading pressure value and a third preset threshold, or the duration for which the operating pressure value is greater than or equal to the unloading pressure value is greater than or equal to a preset delay duration, perform pressure unloading on the variable frequency air compressor, including: Judge whether the operating pressure value is less than the sum of the unloading pressure value and the third preset threshold; If the operating pressure value is greater than or equal to the sum of the unloading pressure value and the third preset threshold, perform pressure unloading on the variable frequency air compressor and continue to execute the step of continuously detecting the operating pressure value of the variable frequency air compressor; If the operating pressure value is less than the sum of the unloading pressure value and the third preset threshold, judge whether the operating pressure value is greater than or equal to the unloading pressure value; If the operating pressure value is less than the unloading pressure value, continue to execute the step of continuously detecting the operating pressure value of the variable frequency air compressor; If the operating pressure value is greater than or equal to the unloading pressure value, time the duration for which the operating pressure value is greater than or equal to the unloading pressure value to obtain an overload duration, and judge whether the overload duration is greater than or equal to the preset delay duration; If the overload duration is greater than or equal to the preset delay duration, perform pressure unloading on the variable frequency air compressor and continue to execute the step of continuously detecting the operating pressure value of the variable frequency air compressor.

6. The constant pressure control method according to claim 5, characterized in that, After the process of judging whether the overload duration is greater than or equal to the preset delay duration, it further includes: If the overload duration is less than the preset delay duration, clear the overload duration and continue to execute the step of continuously detecting the operating pressure value of the variable frequency air compressor.

7. A constant pressure control device for a variable frequency air compressor, characterized in that, It includes: A pressure detection module for continuously detecting the operating pressure value of the variable frequency air compressor and judging whether the operating pressure value is greater than or equal to a first preset threshold; wherein, the difference between the set pressure value and the unloading pressure value of the variable frequency air compressor is less than a second preset threshold; the first preset threshold is greater than the loading pressure value of the variable frequency air compressor; A pressure regulation module for, if the operating pressure value is greater than or equal to the first preset threshold, dynamically setting a target pressure value according to the first preset threshold and the set pressure value, and at the same time, based on the principle that the target pressure value gradually approaches the set pressure value as the adjustment time changes, and performing constant pressure control on the variable frequency air compressor according to the target pressure value according to the PID algorithm; A pressure unloading module for performing pressure unloading on the variable frequency air compressor when the operating pressure value is greater than or equal to the sum of the unloading pressure value and a third preset threshold, or the duration for which the operating pressure value is greater than or equal to the unloading pressure value is greater than or equal to a preset delay duration; Dynamically setting a target pressure value according to the first preset threshold and the set pressure value, and based on the principle that the target pressure value gradually approaches the set pressure value as the adjustment time changes, and performing a constant pressure control on the variable frequency air compressor according to the target pressure value according to the PID algorithm, the process includes: Setting a pressure increment according to the difference between the first preset threshold and the set pressure value; Taking i = 1 as the initial value, setting the target pressure value according to the target model and the pressure increment, performing a constant pressure control on the variable frequency air compressor according to the target pressure value according to the PID algorithm, and at the same time timing the duration of the constant pressure control to obtain a target duration; Judging whether the target duration is greater than or equal to a preset duration; If the target duration is greater than or equal to the preset duration, incrementing the value of i in steps of 1 in sequence, and continuing to execute the step of setting the target pressure value according to the target model and the pressure increment, performing a constant pressure control on the variable frequency air compressor according to the target pressure value according to the PID algorithm, and at the same time timing the duration of the constant pressure control to obtain a target duration, until the target pressure value is equal to the set pressure value; Wherein, the expression of the pressure increment is: ΔP = (P2 - P a ) / N; 2 ≤ N ≤ 10; The expression of the target model is: P j = P a + i*ΔP; Wherein, ΔP is the pressure increment, P2 is the set pressure value, and P a is the first preset threshold value, and P j is the target pressure value.

8. A constant pressure control device for a variable frequency air compressor, characterized in that, Including: A memory for storing a computer program; A processor for implementing the steps of a constant pressure control method for a variable frequency air compressor according to any one of claims 1 to 6 when executing the computer program.

9. A computer-readable storage medium, characterized in that, A computer program is stored on the computer-readable storage medium, and when the computer program is executed by a processor, the steps of a constant pressure control method for a variable frequency air compressor according to any one of claims 1 to 6 are implemented.

Images