Compressor control method and compression system

Abstract

The present invention provides a method for controlling a compressor and a compression system, the method for controlling a compressor comprises: acquiring a discharge pressure of the compressor; and dynamically controlling working modes of the variable-frequency compression unit and the fixed-frequency compression unit according to the discharge pressure, so as to adjust free air delivery of the compressor, wherein the working modes at least include a stopping working mode, a loading working mode and an unloading working mode, and the variable-frequency compression unit and the fixed-frequency compression unit are respectively connected to an oil-gas separator, so that compressed gas is supplied to the oil-gas separator via the variable-frequency compression unit and the fixed-frequency compression unit in cooperation. According to the above method, the free air delivery of the compressor is adjusted by controlling the working modes of the variable-frequency compression unit and the fixed-frequency compression unit, so that the adjustment method for the free air delivery is more flexible, and the adjustment range of the free air delivery can be expanded.

Description

TECHNICAL FIELD

[0001] The present invention relates to the technical field of compressed gas, and in particular, to a method for controlling a compressor, and a compression system.BACKGROUND

[0002] An air compressor is a device for compressing gas. At present, one compressor is often connected to compression units of one traditional motor in air compressors, and each compression unit needs to be connected to a corresponding oil-gas separator for oil-gas separation. Such a traditional drive system is high in energy consumption, low in efficiency, and limited in adjustment range of the output gas volume of the whole machine.SUMMARY

[0003] In view of the above technical problems existing in the prior art, the present invention provides a method for controlling the compressor, and a compression system. Accordingly, free air delivery of the compressor can be adjusted by controlling working modes of the variable-frequency compression unit and the fixed-frequency compression unit, so that the adjustment method for the free air delivery is more flexible, and the adjustment range of the free air delivery can be expanded.

[0004] An embodiment of the present invention provides a method for controlling the compressor. The method comprises: acquiring a discharge pressure of the compressor; and dynamically controlling working modes of the variable-frequency compression unit and the fixed-frequency compression unit according to the discharge pressure, so as to adjust free air delivery of the compressor, wherein: the working modes at least comprise a stopping working mode, a loading working mode and an unloading working mode, and the variable-frequency compression unit and the fixed-frequency compression unit are respectively connected to an oil-gas separator, so that compressed gas is supplied to the oil-gas separator via the variable-frequency compression unit and the fixed-frequency compression unit in cooperation.

[0005] In some embodiments, said dynamically controlling working modes of a variable-frequency compression unit and a fixed-frequency compression unit according to the discharge pressure specifically comprises: in a case where the discharge pressure is less than a first preset pressure, controlling the variable-frequency compression unit to enter the loading working mode and continuously load, and controlling the fixed-frequency compression unit to enter the stopping working mode; and in a case where the discharge pressure is greater than or equal to the first preset pressure, controlling both the variable-frequency compression unit and the fixed-frequency compression unit to enter the stopping working mode.

[0006] In some embodiments, after controlling the variable-frequency compression unit to enter the loading working mode and continuously load, the method further comprises: in a case where the discharge pressure is greater than or equal to the first preset pressure and the discharge pressure is less than a fourth preset pressure, controlling the variable-frequency compression unit to remain in the loading working mode and controlling the fixed-frequency compression unit to enter the stopping working mode; wherein: the fourth preset pressure is greater than the first preset pressure.

[0007] In some embodiments, the method further comprises: in a case where the discharge pressure is greater than or equal to the fourth preset pressure, controlling the variable-frequency compression unit to enter the unloading working mode and the fixed-frequency compression unit to remain in the stopping working mode.

[0008] In some embodiments, after controlling the variable-frequency compression unit to enter the unloading working mode and the fixed-frequency compression unit to remain in the stopping working mode, the method further comprises: determining whether the discharge pressure is greater than or equal to the first preset pressure; if yes, controlling the variable-frequency compression unit to remain in the unloading working mode and the fixed-frequency compression unit to remain in the stopping working mode; and if no, controlling the variable-frequency compression unit to enter the loading working mode and the fixed-frequency compression unit to remain in the stopping working mode.

[0009] In some embodiments, after controlling the variable-frequency compression unit to remain in the unloading working mode and the fixed-frequency compression unit to remain in the stopping working mode, the method further comprises: determining whether a duration of the variable-frequency compression unit remaining in the unloading working mode exceeds a third preset time; and if yes, controlling both the variable-frequency compression unit and the fixed-frequency compression unit to enter the stopping working mode.

[0010] In some embodiments, after controlling the variable-frequency compression unit to enter the loading working mode and continuously load, the method further comprises: in a case where the discharge pressure is less than a second preset pressure, controlling the fixed-frequency compression unit to enter the unloading working mode and the variable-frequency compression unit to remain in the loading working mode; or, in a case where the discharge pressure is less than the first preset pressure and greater than the second preset pressure and the duration exceeds a first preset time, controlling the fixed-frequency compression unit to enter the unloading working mode and the variable-frequency compression unit to remain in the loading working mode, wherein the first preset pressure is greater than the second preset pressure.

[0011] In some embodiments, after controlling the fixed-frequency compression unit to enter the unloading working mode, the method further comprises: determining whether the discharge pressure is less than the second preset pressure; or, determining whether the discharge pressure is less than the first preset pressure and the discharge pressure is greater than or equal to the second preset pressure and the duration exceeds the first preset time, if yes, controlling the fixed-frequency compression unit to enter the loading working mode and continuously load and the variable-frequency compression unit to remain in the loading working mode; and if no, controlling the fixed-frequency compression unit to remain in the unloading working mode and the variable-frequency compression unit to remain in the loading working mode.

[0012] In some embodiments, after controlling the fixed-frequency compression unit to enter the loading working mode and continuously load and the variable-frequency compression unit to remain in the loading working mode, the method further comprises: determining whether the discharge pressure is greater than or equal to a third preset pressure; and if yes, controlling the fixed-frequency compression unit to enter the unloading working mode and the variable-frequency compression unit to remain in the loading working mode, wherein: the third preset pressure is greater than the first preset pressure.

[0013] In some embodiments, the method further comprises: determining whether the discharge pressure is greater than or equal to a fourth preset pressure; if yes, controlling the variable-frequency compression unit to enter the unloading working mode and the fixed-frequency compression unit to remain in the unloading working mode; and if no, controlling the fixed-frequency compression unit to remain in the unloading working mode and the variable-frequency compression unit to remain in the loading working mode, wherein: the fourth preset pressure is greater than the third preset pressure.

[0014] In some embodiments, after controlling the fixed-frequency compression unit to remain in the unloading working mode and the variable-frequency compression unit to remain in the loading working mode, the method further comprises: determining whether a duration of the fixed-frequency compression unit remaining in the unloading working mode exceeds a second preset time; and if yes, controlling the fixed-frequency compression unit to enter the stopping working mode and the variable-frequency compression unit to remain in the loading working mode.

[0015] In some embodiments, after controlling the variable-frequency compression unit to enter the unloading working mode and the fixed-frequency compression unit to remain in the unloading working mode, the method further comprises: determining whether the discharge pressure is greater than or equal to the first preset pressure; if yes, controlling the variable-frequency compression unit to remain in the unloading working mode and the fixed-frequency compression unit to remain in the unloading working mode; and if no, controlling the variable-frequency compression unit to enter the loading working mode and the fixed-frequency compression unit to enter the unloading working mode.

[0016] In some embodiments, after controlling the variable-frequency compression unit to remain in the unloading working mode and the fixed-frequency compression unit to remain in the unloading working mode, the method further comprises: determining whether the duration of the variable-frequency compression unit remaining in the unloading working mode exceeds the third preset time; and if yes, controlling both the variable-frequency compression unit and the fixed-frequency compression unit to enter the stopping working mode.

[0017] In some embodiments, the method further comprises: determining whether the discharge pressure is greater than or equal to a fifth preset pressure; and if yes, controlling the fixed-frequency compression unit and the variable-frequency compression unit to enter the stopping working mode, wherein: the fifth preset pressure is greater than the fourth preset pressure.

[0018] In some embodiments, the method further comprises: in a case where the variable-frequency compression unit enters the loading working mode, the oil-gas mixture discharged from the variable-frequency compression unit is separated by the oil-gas separator to obtain gas and oil, cooling the gas by an aftercooler and then discharging the cooled gas, and cooling the oil by an oil cooler and then returning the cooled oil to the variable-frequency compression unit, wherein: the aftercooler is connected to the oil-gas separator to cool the gas separated by the oil-gas separator, and the oil cooler is connected to the variable-frequency compression unit and the oil-gas separator respectively.

[0019] In some embodiments, the method further comprises: in a case where the variable-frequency compression unit enters the unloading working mode, passing an oil-gas mixture discharged from the variable-frequency compression unit through the oil-gas separator and a venting pipeline, emptying the gas in the oil-gas separator through the variable-frequency compression unit, separating the oil-gas mixture discharged from the variable-frequency compression unit by the oil-gas separator to obtain oil, and cooling the oil by the oil cooler and then returning the cooled oil to the variable-frequency compression unit.

[0020] In some embodiments, the method further comprises: in a case where the fixed-frequency compression unit enters the loading working mode, the oil-gas mixture discharged from the fixed-frequency compression unit is separated by the oil-gas separator to obtain gas, and cooling the gas by the aftercooler and then discharging the cooled gas; the oil-gas mixture discharged from the fixed-frequency compression unit is separated by the oil-gas separator to obtain oil, and cooling the oil by the oil cooler and then making the cooled oil enter the fixed-frequency compression unit, wherein: the aftercooler is connected to the oil-gas separator to cool the gas separated by the oil-gas separator.

[0021] In some embodiments, the method further comprises: in a case where the fixed-frequency compression unit enters the unloading working mode, making an oil-gas mixture discharged from the fixed-frequency compression unit enter a buffer tank, making the gas enter the variable-frequency compression unit via the buffer tank, and making the oil enter the fixed-frequency compression unit via a combination valve, wherein: the buffer tank is provided between the fixed-frequency compression unit and the oil-gas separator, and the combination valve is connected to the oil-gas separator, the buffer tank, the oil cooler and an oil filter respectively.

[0022] An embodiment of the present invention further provides a compression system, including the compressor and a control apparatus, wherein the control apparatus is configured to execute the method for controlling the compressor as described above.

[0023] In some embodiments, the compressor comprises a box body, and further comprises: an oil-gas separator, arranged in the box body and configured to separate the oil-gas mixture; and at least two compression units, arranged in the box body and connected to the oil-gas separator, respectively, wherein the at least two compression units are constructed in one of the following forms: both being fixed-frequency compression units, both being variable-frequency compression units, or being a combination of the fixed-frequency compression unit and the variable-frequency compression unit, and the at least two compression units are configured to cooperate in providing compressed gas to the oil-gas separator.

[0024] In some embodiments, the at least two compression units are constructed as a combination of a fixed-frequency compression unit and a variable-frequency compression unit, wherein a buffer tank is provided between the fixed-frequency compression unit and the oil-gas separator, and is configured to provide buffering for the fixed-frequency compression unit when the fixed-frequency compression unit is in an unloading state.

[0025] In some embodiments, the buffer tank is provided between the box body and the oil-gas separator, and is arranged close to the oil-gas separator.

[0026] In some embodiments, the at least two compression units are staggered in the box body.

[0027] In some embodiments, the at least two compression units are arranged side by side in the box body.

[0028] In some embodiments, the compressor further comprises an aftercooler, a first fan, and a plurality of oil coolers arranged in one-to-one correspondence with the compression units, wherein the aftercooler and the plurality of oil coolers are arranged side by side, and the first fan is arranged above the oil coolers and the aftercooler.

[0029] In some embodiments, the compressor further comprises an aftercooler, first fans, and a plurality of oil coolers arranged in one-to-one correspondence with the compression units, wherein the plurality of oil coolers are arranged between the compression units corresponding thereto and the box body, the aftercooler is arranged close to any one of the oil coolers, and the first fans are arranged at the sides of the plurality of oil coolers and the side of the aftercooler away from the box body in one-to-one correspondence.

[0030] In some embodiments, a staggered space is formed between the at least two compression units and the box body, and the oil-gas separator is arranged in the staggered space.

[0031] In some embodiments, an accommodating space is formed between the at least two compression units and a first side wall of the box body, and the oil-gas separator is arranged in the accommodating space.

[0032] In some embodiments, the compressor further comprises an aftercooler and a plurality of oil coolers arranged in one-to-one correspondence with the compression units, wherein the aftercooler and the oil coolers are sequentially arranged side by side in the accommodating space.

[0033] In some embodiments, the compressor further comprises air filters connected to the compression units and arranged in one-to-one correspondence with the compression units, wherein the air filters are arranged in the box body and correspond to gas inlets in the box body.

[0034] In some embodiments, the oil-gas separator is arranged close to a first side wall of the box body, and the compressor further includes an electric control cabinet which is arranged in the box body and close to a second side wall of the box body opposite to the first side wall.

[0035] Compared with the prior art, the beneficial effects of the embodiments of the present invention lie in that: according to the present invention, free air delivery of the compressor is adjusted by acquiring a discharge pressure of the compressor and dynamically controlling working modes of the variable-frequency compression unit and the fixed-frequency compression unit according to the discharge pressure, so that the adjustment method for the free air delivery is more flexible, and the adjustment range of the free air delivery can be expanded, thereby having the advantages of energy saving and efficiency improvement.BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In the accompanying drawings which are not necessarily drawn to scale, the same reference numerals may describe similar components in different views. The same reference numerals with a letter suffix or different letter suffixes may represent different instances of similar components. The accompanying drawings illustrate various embodiments generally by way of example but not limitation, and together with the description and claims, are used to illustrate the disclosed embodiments. Wherever appropriate, the same reference numerals will be used throughout the accompanying drawings to refer to the same or similar parts. Such embodiments are illustrative and are not intended to be exhaustive or exclusive embodiments of this apparatus or method. FIG. 1 is a diagram showing the working principle of the compressor including two compression units according to an embodiment of the present invention; FIG. 2 is a diagram showing the working principle of the compressor including a fixed-frequency compression unit and a variable-frequency compression unit according to an embodiment of the present invention; FIG. 3 is a first flowchart of a method for controlling the compressor according to an embodiment of the present invention; FIG. 4 is a second flowchart of the method for controlling the compressor according to an embodiment of the present invention; FIG. 5 is a third flowchart of the method for controlling the compressor according to an embodiment of the present invention; FIG. 6 is a gas circuit diagram of a compression system using the method for controlling the compressor according to an embodiment of the present invention, in which the variable-frequency compression unit is in a loading working mode and the fixed-frequency compression unit is in an unloading working mode; FIG. 7 is an oil circuit diagram of the compression system using the method for controlling the compressor according to an embodiment of the present invention, in which the variable-frequency compression unit is in the loading working mode and the fixed-frequency compression unit is in the unloading working mode; FIG. 8 is a gas circuit diagram of a compression system using the method for controlling the compressor according to an embodiment of the present invention, in which both the variable-frequency compression unit and the fixed-frequency compression unit are in the loading working mode; FIG. 9 is an oil circuit diagram of the compression system using the method for controlling the compressor according to an embodiment of the present invention, in which both the variable-frequency compression unit and the fixed-frequency compression unit are in the loading working mode; FIG. 10 is a gas circuit diagram of the compression system using the method for controlling the compressor according to an embodiment of the present invention, in which both the variable-frequency compression unit and the fixed-frequency compression unit are in the unloading working mode; FIG. 11 is an oil circuit diagram of the compression system using the method for controlling the compressor according to an embodiment of the present invention, in which both the variable-frequency compression unit and the fixed-frequency compression unit are in the unloading working mode; FIG. 12 is a schematic structural diagram of an air-cooled compressor according to a first embodiment of the present utility model; FIG. 13 is a schematic structural diagram of the air-cooled compressor according to the first embodiment of the present utility model from another perspective; FIG. 14 is a top view of the air-cooled compressor according to the first embodiment of the present utility model; FIG. 15 is a schematic structural diagram of an air-cooled compressor according to a second embodiment of the present utility model; FIG. 16 is a schematic structural diagram of the air-cooled compressor according to the second embodiment of the present utility model from another perspective; FIG. 17 is a top view of the air-cooled compressor according to the second embodiment of the present utility model; FIG. 18 is a schematic structural diagram of a water-cooled compressor according to an embodiment of the present utility model; FIG. 19 is a schematic structural diagram of the water-cooled compressor according to an embodiment of the present utility model from another perspective; and FIG. 20 is a top view of the water-cooled compressor according to an embodiment of the present utility model.

[0037] The components indicated by the reference numerals in the figures: 1, oil-gas separator; 2, compression unit; 201, fixed-frequency compression unit; 202, variable-frequency compression unit; 3, intake valve; 4, buffer tank; 5, aftercooler; 6, minimum pressure valve; 7, air filter; 8, temperature control valve; 9, oil cooler; 10, oil filter; 11, first fan; 12, electric control cabinet; 13, combination valve; and 14, oil injection valve.DETAILED DESCRIPTION

[0038] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the present invention is described in detail below in conjunction with the accompanying drawings and specific implementations. The embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings and specific embodiments, but are not intended to limit the present invention.

[0039] "First", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are merely used to distinguish between different portions. "Comprise" or "contain" and similar words mean that the elements before the word cover the elements listed after the word, and do not exclude the possibility of also covering other elements. "Up", "down", "left", "right", etc. are merely used to indicate relative position relationships. When the absolute position of an object being described changes, the relative position relationship may also change accordingly.

[0040] In the present invention, when it is described that a specific component is located between a first component and a second component, there may or may not be an intermediate component between the specific component and the first component or the second component. When it is described that a specific component is connected to other components, the specific component may be directly connected to the other components without having an intermediate component, or may have an intermediate component without being directly connected to the other components.

[0041] All terms (including technical terms or scientific terms) used in the present invention have the same meanings as those understood by those of ordinary skill in the field to which the present invention belongs, unless otherwise specifically defined. It should also be understood that terms defined in, for example, general dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and should not be interpreted in an idealized or extremely formal sense, unless expressly so defined herein.

[0042] Technologies, methods, and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

[0043] An embodiment of the present invention provides a method for controlling the compressor. The method for controlling the compressor can be applied to a compression system including the compressor. As shown in FIGS. 1 and 2, the compressor at least includes compression units 2 and an oil-gas separator 1. The compression units 2 may include a variable-frequency compression unit 202 (Variable frequency speed regulation device; VSD) and a fixed-frequency compression unit 201 (Fix speed device; FS) that are connected to the oil-gas separator 1 respectively, so that compressed gas is supplied to the oil-gas separator 1 via the variable-frequency compression unit 202 and the fixed-frequency compression unit 201 in cooperation.

[0044] The above compressor may be constructed as an air-cooled compressor or a water-cooled compressor. FIG. 1 is a diagram showing the working principle of a compressor including two compression units 2. FIG. 2 is a diagram showing the working principle of a compressor including the fixed-frequency compression unit 201 and the variable-frequency compression unit 202.

[0045] Further, as shown in FIG. 3, the method for controlling the compressor includes steps S101 to S102.

[0046] Step S101: Acquire a discharge pressure of the compressor; and Step S102: Dynamically control working modes of the variable-frequency compression unit 202 and the fixed-frequency compression unit 201 according to the discharge pressure, so as to adjust free air delivery of the compressor, where the working modes at least include a stopping working mode, a loading working mode, and an unloading working mode.

[0047] Specifically, the above discharge pressure can be understood as any one of the gas pressure discharged from the oil-gas separator 1, the gas pressure at an inlet and an outlet of an aftercooler 5, and the gas pressure at an outlet of the complete compressor. The discharge pressure is a real-time measured value, so that the working modes of the variable-frequency compression unit 202 and the fixed-frequency compression unit 201 are controlled according to the real-time discharge pressure. As shown in FIGS. 1 and 2, the aftercooler 5 is connected to a gas outlet of the oil-gas separator 1, and is configured to cool the compressed gas separated by the oil-gas separator 1.

[0048] Specifically, the above loading working mode and unloading working mode are working modes that the compression units 2 have when in a running state. In addition to the working modes in the running state, the above working modes may also include a stopping working mode when the compression units 2 are shut down.

[0049] Specifically, the free air delivery and discharge pressure of the above compressor can be understood to have a positive correlation. When the free air delivery increases, the discharge pressure increases accordingly, and when the free air delivery decreases, the discharge pressure decreases accordingly.

[0050] Specifically, controlling the working modes of the variable-frequency compression unit 202 and the fixed-frequency compression unit 201 can be understood as controlling the variable-frequency compression unit 202 and the fixed-frequency compression unit 201 to be in different working modes, respectively, or in the same working mode. In short, the free air delivery can be adjusted by controlling the working modes of the variable-frequency compression unit 202 and the fixed-frequency compression unit 201.

[0051] Specifically, at least two compression units 2 being respectively connected to the oil-gas separator 1 can be understood as there is no direct connection relationship between the compression units 2, and the compression units 2 are respectively connected to the oil-gas separator 1 in a parallel arrangement.

[0052] According to the present invention, the free air delivery of the compressor is adjusted by acquiring a discharge pressure of the compressor and dynamically controlling the working modes of the variable-frequency compression unit 202 and the fixed-frequency compression unit 201 according to the discharge pressure, so that the adjustment method for the free air delivery is more flexible, and the adjustment range of the free air delivery can be expanded, thereby having the advantages of energy saving and efficiency improvement.

[0053] In some embodiments, when the compressor is in an initial state, intake valves 3 of the compressor that are connected to the respective compression units 2 are in a closed state. After the control apparatus of the compressor issuing a start command, the compression system using the compressor starts to run, and the discharge pressure (P) and a first preset pressure (P1) can be compared after the running. The intake valves 3 are connected to the compression units 2 and are arranged in one-to-one correspondence with the compression units 2, so that the gas entering through the intake valves 3 is compressed by the corresponding compression units 2 and then enters the oil-gas separator 1.

[0054] In some embodiments, as shown in FIG. 4, the step S 102 of dynamically controlling the working modes of the variable-frequency compression unit 202 and the fixed-frequency compression unit 201 according to the discharge pressure specifically comprises: in a case where the discharge pressure is less than a first preset pressure, controlling the variable-frequency compression unit 202 to enter the loading working mode and controlling the fixed-frequency compression unit 201 to enter the stopping working mode. That is, when P < P1, the compression system is in a standby mode, the variable-frequency compression unit 202 enters the loading working mode, and the fixed-frequency compression unit 201 enters the stopping working mode.

[0055] Specifically, the above first preset pressure can be understood as a set value which can be set based on experience or obtained based on experimental conclusions, on which this application does not make any specific limitation. The second preset pressure (P2), the third preset pressure (P3), the fourth preset pressure (P4) and the fifth preset pressure (P5) hereinafter are also set values.

[0056] In some embodiments, further in conjunction with FIG. 4, in a case where the discharge pressure is greater than or equal to the first preset pressure, both the variable-frequency compression unit 202 and the fixed-frequency compression unit 201 are controlled to enter the stopping working mode.

[0057] In some embodiments, as shown in FIG. 4, after controlling the variable-frequency compression unit 202 to enter the loading working mode and controlling the fixed-frequency compression unit 201 to enter the stopping working mode, the method further comprises: in a case where the discharge pressure is greater than or equal to a fourth preset pressure (P4), controlling the variable-frequency compression unit 202 to enter the unloading working mode and the fixed-frequency compression unit 201 to remain in the stopping working mode, wherein the fourth preset pressure is greater than the first preset pressure; and in a case where the discharge pressure is less than the fourth preset pressure, determining whether P1≤P<P4 is satisfied, or whether P<P2 is satisfied, or whether P2≤P≤P1 is satisfied and lasts for a first preset time (T1).

[0058] That is, when P≥P4, the variable-frequency compression unit 202 enters the unloading working mode, and the fixed-frequency compression unit 201 remains in the stopping working mode; when P<P4, it is determined whether P1≤P<P4 is satisfied, or whether P<P2 is satisfied, or whether P2≤P≤P1 is satisfied and lasts for T1.

[0059] In some embodiments, as shown in FIG. 4, the step S102 of dynamically controlling the working modes of the variable-frequency compression unit 202 and the fixed-frequency compression unit 201 according to the discharge pressure specifically comprises: in a case where the discharge pressure is less than the first preset pressure (P1), controlling the variable-frequency compression unit 202 to enter the loading working mode and continuously load, and controlling the fixed-frequency compression unit 201 to enter the stopping working mode. That is, when P<P1, the variable-frequency compression unit 202 starts, enters the loading working mode, and continuously loads; and in a case where the discharge pressure is greater than or equal to the first preset pressure, controlling both the variable-frequency compression unit 202 and the fixed-frequency compression unit 201 to enter the stopping working mode. That is, when P≥P1, both the variable-frequency compression unit 202 and the fixed-frequency compression unit 201 are controlled to enter the stopping working mode.

[0060] Specifically, in a case where the discharge pressure is less than the first preset pressure, the variable-frequency compression unit 202 can start its variable-frequency motor at the lowest speed, and after a certain delay, the variable-frequency compression unit 202 enters the loading working mode.

[0061] In some embodiments, as shown in FIG. 4, after controlling the variable-frequency compression unit 202 to enter the loading working mode and continuously load, the method further comprises: in a case where the discharge pressure is greater than or equal to the first preset pressure and is less than a fourth preset pressure, controlling the variable-frequency compression unit 202 to remain in the loading working mode and controlling the fixed-frequency compression unit 201 to enter the stopping working mode, wherein the fourth preset pressure is greater than the first preset pressure. That is, when P1≤P<P4, the variable-frequency compression unit 202 is controlled to remain in the loading working mode, and the fixed-frequency compression unit 201 is controlled to enter the stopping working mode.

[0062] In some embodiments, as shown in FIG. 4, the method further comprises: in a case where the discharge pressure is greater than or equal to the fourth preset pressure, controlling the variable-frequency compression unit 202 to enter the unloading working mode and the fixed-frequency compression unit 201 to remain in the stopping working mode. That is, when P ≥P4, the variable-frequency compression unit 202 enters the unloading working mode, and the fixed-frequency compression unit 201 remains in the stopping working mode.

[0063] In some embodiments, as shown in FIG. 4, after controlling the variable-frequency compression unit to enter the unloading working mode and the fixed-frequency compression unit 201 to remain in the stopping working mode, the method further comprises: determining whether the discharge pressure is greater than or equal to the first preset pressure; if yes, controlling the variable-frequency compression unit 202 to remain in the unloading working mode and the fixed-frequency compression unit 201 to remain in the stopping working mode; and if no, controlling the variable-frequency compression unit 202 to enter the loading working mode and the fixed-frequency compression unit 201 to remain in the stopping working mode.

[0064] That is, when P≥P1, the variable-frequency compression unit 202 remains in the unloading working mode, and the fixed-frequency compression unit 201 remains in the stopping working mode; when P<P1, the variable-frequency compression unit 202 enters the loading working mode, and the fixed-frequency compression unit 201 remains in the stopping working mode.

[0065] In some embodiments, as shown in FIG. 4, after controlling the variable-frequency compression unit 202 to remain in the unloading working mode and the fixed-frequency compression unit 201 to remain in the stopping working mode, the method further comprises: determining whether a duration of the variable-frequency compression unit 202 remaining in the unloading working mode exceeds a third preset time (T3); and if yes, controlling both the variable-frequency compression unit 202 and the fixed-frequency compression unit 201 to enter the stopping working mode. The system of compressor restarts self-running after controlling both the variable-frequency compression unit 202 and the fixed-frequency compression unit 201 to enter the stopping working mode.

[0066] In some embodiments, as shown in FIG. 4, after controlling the variable-frequency compression unit to enter the loading working mode and continuously load, the method further comprises: in a case where the discharge pressure is less than a second preset pressure, controlling the fixed-frequency compression unit 201 to enter the unloading working mode and the variable-frequency compression unit 202 to remain in the loading working mode; or, in a case where the discharge pressure is less than the first preset pressure and greater than the second preset pressure and the duration exceeds a first preset time (T1), controlling the fixed-frequency compression unit 201 to enter the unloading working mode and the variable-frequency compression unit 202 to remain in the loading working mode, wherein the first preset pressure is greater than the second preset pressure.

[0067] That is, when P<P2 or P2≤P<P1, lasting for T1, the fixed-frequency compression unit 201 enters the unloading working mode, and the variable-frequency compression unit 202 remains in the loading working mode.

[0068] In some embodiments, as shown in FIG. 4, after controlling the fixed-frequency compression unit 201 to enter the unloading working mode, the method further comprises: determining whether the discharge pressure is less than the second preset pressure; or, determining whether the discharge pressure is less than the first preset pressure and is greater than or equal to the second preset pressure and the duration exceeds the first preset time, if yes, controlling the fixed-frequency compression unit 201 to enter the loading working mode and continuously load and the variable-frequency compression unit 202 to remain in the loading working mode; and if no, controlling the fixed-frequency compression unit 201 to remain in the unloading working mode and the variable-frequency compression unit 202 to remain in the loading working mode.

[0069] That is, when P<P2 or P2≤P<P1, lasting for T1, the fixed-frequency compression unit 201 enters the loading working mode and continues to load, and the variable-frequency compression unit 202 remains in the loading working mode.

[0070] In some embodiments, as shown in FIG. 4, after controlling the fixed-frequency compression unit 201 to enter the loading working mode and continuously load and the variable-frequency compression unit 202 to remain in the loading working mode, the method further comprises: determining whether the discharge pressure is greater than or equal to a third preset pressure; if yes, controlling the fixed-frequency compression unit 201 to enter the unloading working mode and the variable-frequency compression unit 202 to remain in the loading working mode; and if no, controlling the fixed-frequency compression unit 201 to remain in the loading working mode and the variable-frequency compression unit 202 to remain in the loading working mode, wherein the third preset pressure is greater than the first preset pressure.

[0071] That is, when P≥P3, the fixed-frequency compression unit 201 enters the unloading working mode, and the variable-frequency compression unit 202 remains in the loading working mode; when P<P3, the fixed-frequency compression unit 201 remains in the loading working mode, and the variable-frequency compression unit 202 remains in the loading working mode.

[0072] In some embodiments, as shown in FIG. 4, the method further comprises: determining whether the discharge pressure is greater than or equal to the fourth preset pressure; if yes, controlling the variable-frequency compression unit 202 to enter the unloading working mode and the fixed-frequency compression unit 201 to remain in the unloading working mode; and if no, controlling the fixed-frequency compression unit 201 to remain in the unloading working mode and the variable-frequency compression unit 202 to remain in the loading working mode, wherein the fourth preset pressure is greater than the third preset pressure.

[0073] That is, when P≥P4, the variable-frequency compression unit 202 enters the unloading working mode, and the fixed-frequency compression unit 201 remains in the unloading working mode.

[0074] In some embodiments, as shown in FIG. 4, after controlling the fixed-frequency compression unit 201 to remain in the unloading working mode and the variable-frequency compression unit 202 to remain in the loading working mode, the method further comprises: determining whether a duration of the fixed-frequency compression unit 201 remaining in the unloading working mode exceeds a second preset time (T2); if yes, controlling the fixed-frequency compression unit 201 to enter the stopping working mode and the variable-frequency compression unit 202 to remain in the loading working mode; and if no, controlling the fixed-frequency compression unit 201 to remain in the unloading working mode and the variable-frequency compression unit 202 to remain in the loading working mode.

[0075] Specifically, the above first preset time, second preset time and third preset time may be the same time, or different times, or any two of the three may be the same time, on which this application does not make any specific limitation.

[0076] In some embodiments, as shown in FIG. 4, after controlling the variable-frequency compression unit 202 to enter the unloading working mode and the fixed-frequency compression unit 201 to remain in the unloading working mode, the method further comprises: determining whether the discharge pressure is greater than or equal to the first preset pressure; if yes, controlling the variable-frequency compression unit 202 to remain in the unloading working mode and the fixed-frequency compression unit 201 to remain in the unloading working mode; and if no, controlling the variable-frequency compression unit 202 to enter the loading working mode and the fixed-frequency compression unit 201 to enter the unloading working mode.

[0077] That is, when P≥P1, the variable-frequency compression unit 202 remains in the unloading working mode, and the fixed-frequency compression unit 201 remains in the unloading working mode; when P<P1, the variable-frequency compression unit 202 enters the loading working mode, and the fixed-frequency compression unit 201 enters the unloading working mode.

[0078] In some embodiments, as shown in FIG. 4, after controlling the variable-frequency compression unit 202 to remain in the unloading working mode and the fixed-frequency compression unit 201 to remain in the unloading working mode, the method further comprises: determining whether the duration of the variable-frequency compression unit 202 remaining in the unloading working mode exceeds the third preset time; if yes, controlling both the variable-frequency compression unit 202 and the fixed-frequency compression unit 201 to enter the stopping working mode; and if no, controlling the fixed-frequency compression unit 201 to remain in the unloading working mode and the variable-frequency compression unit 202 to remain in the unloading working mode.

[0079] In some embodiments, as shown in FIG. 5, the method further comprises: determining whether the discharge pressure is greater than or equal to a fifth preset pressure (P5); if yes, controlling the fixed-frequency compression unit 201 and the variable-frequency compression unit 202 to enter the stopping working mode; and if no, controlling the system to continue to run as in the method described above, wherein the fifth preset pressure is greater than the fourth preset pressure.

[0080] That is, when P ≥ P5, the fixed-frequency compression unit 201 and the variable-frequency compression unit 202 enter the stopping working mode; when P<P5, the system is controlled to continuously run as in the method described above, that is, continuously determine.

[0081] In some embodiments, as shown in FIGS. 6 to 9, the method further comprises: in a case where the variable-frequency compression unit 202 enters the loading working mode, the oil-gas mixture discharged from the variable-frequency compression unit 202 is separated by the oil-gas separator 1 to obtain gas and oil, cooling the gas by an aftercooler 5 and then discharging the cooled gas, and cooling the oil by an oil cooler 9 and then returning the cooled oil to the variable-frequency compression unit 202, wherein the aftercooler 5 is connected to the oil-gas separator 1 to cool the gas separated by the oil-gas separator 1, and the oil cooler 9 is connected to the variable-frequency compression unit 202 and the oil-gas separator 1 respectively.

[0082] Specifically, a part of the gas separated by the oil-gas separator 1 is cooled by the aftercooler 5 and then discharged, and the other part enters the variable-frequency compression unit 202 to open the intake valve 3 connected thereto.

[0083] Specifically, a part of the oil flows through a temperature control valve 8, the oil cooler 9 and the oil filter 10 corresponding to the variable-frequency compression unit 202 in sequence and then enters the variable-frequency compression unit 202, and the other part is directly drawn back into the variable-frequency compression unit 202 by the oil-gas separator 1 under the action of the variable-frequency compression unit 202. The temperature control valve 8 is connected to the bottom of the oil-gas separator 1 and the compression units 2 respectively, and is configured to control the oil temperature of the oil entering the compression units 2 after being separated by the oil-gas separator 1. The oil cooler 9 is configured to cool the oil entering the compression units 2 through the temperature control valve 8. The oil filter 10 is provided between the oil cooler 9 and the compression units 2, and is configured to filter the oil cooled by the oil cooler 9 before entering the compression units 2.

[0084] Specifically, the above temperature control valves 8, oil coolers 9 and oil filters 10 are arranged in one-to-one correspondence with the compression units 2, respectively. The compressor may further comprise first fans 11 configured to exchange heat with the oil coolers 9 and the aftercooler 5 through external gas.

[0085] Specifically, a minimum pressure valve 6 is provided at a gas outlet of the oil-gas separator 1, and the aftercooler 5 is communicated with the oil-gas separator 1 through the minimum pressure valve 6. The minimum pressure valve 6 is configured to keep the gas pressure in the oil-gas separator 1 within a preset threshold.

[0086] Specifically, the temperature control valve 8, the oil cooler 9 and the oil filter 10 corresponding to the variable-frequency compression unit 202 are connected in sequence, the temperature control valve 8 is connected to the bottom of the oil-gas separator 1, and the oil filter 10 is connected to the variable-frequency compression unit 202.

[0087] In some embodiments, as shown in FIGS. 10 and 11, the method further comprises:

[0088] in a case where the variable-frequency compression unit 202 enters the unloading working mode, passing an oil-gas mixture discharged from the variable-frequency compression unit 202 through the oil-gas separator 1 and a venting pipeline, emptying the gas in the oil-gas separator 1 through the variable-frequency compression unit 202, separating the oil-gas mixture discharged from the variable-frequency compression unit 202 by the oil-gas separator 1 to obtain oil, and cooling the oil by the oil cooler 9 and then returning the cooled oil to the variable-frequency compression unit 202.

[0089] Specifically, a part of the oil flows through the temperature control valve 8, the oil cooler 9 and the oil filter 10 corresponding to the variable-frequency compression unit 202 in sequence and then enters the variable-frequency compression unit 202, and the other part is directly drawn back into the variable-frequency compression unit 202 by the oil-gas separator 1 under the action of the variable-frequency compression unit 202.

[0090] Specifically, the above variable-frequency compression unit 202 empties gas specifically through the intake valve 3 provided upstream of the variable-frequency compression unit 202.

[0091] In some embodiments, as shown in FIGS. 8 and 9, the method further comprises:

[0092] in a case where the fixed-frequency compression unit 201 enters the loading working mode, the oil-gas mixture discharged from the fixed-frequency compression unit 201 is separated by the oil-gas separator 1 to obtain gas, and cooling the gas by the aftercooler 5 and then discharging the cooled gas; and

[0093] separating the oil-gas mixture discharged from the fixed-frequency compression unit 201 by the oil-gas separator 1 to obtain oil, and cooling the oil by the oil cooler 9 and then making the cooled oil enter the fixed-frequency compression unit 201, wherein the aftercooler 5 is connected to the oil-gas separator 1 to cool the gas separated by the oil-gas separator 1.

[0094] Specifically, the minimum pressure valve 6 is provided at the gas outlet of the oil-gas separator 1, and the aftercooler 5 is connected to the minimum pressure valve 6 to discharge the gas separated by the oil-gas separator 1.

[0095] Specifically, the oil flows through the temperature control valve 8, the oil cooler 9 and the oil filter 10 corresponding to the fixed-frequency compression unit 201 in sequence and then enters the fixed-frequency compression unit 201.

[0096] In some embodiments, as shown in FIGS. 6, 7, 10 and 11, the method further comprises:

[0097] in a case where the fixed-frequency compression unit 201 enters the unloading working mode, making an oil-gas mixture discharged from the fixed-frequency compression unit 201 enter a buffer tank 4, making the gas enter the variable-frequency compression unit 202 via the buffer tank 4, and making the oil enter the fixed-frequency compression unit 201 via a combination valve 13, wherein:

[0098] the buffer tank 4 is provided between the fixed-frequency compression unit 201 and the oil-gas separator 1, and is arranged close to the oil-gas separator 1.

[0099] Specifically, the above buffer tank 4 is configured to provide buffering for the fixed-frequency compression unit 201 when the fixed-frequency compression unit 201 is in an unloading working mode. The combination valve 13 is connected to the oil-gas separator 1, the buffer tank 4, the oil cooler 9, and the oil filter 10 respectively.

[0100] In some embodiments, as shown in FIG. 9, the method further comprises:

[0101] in a case where the fixed-frequency compression unit 201 enters the loading working mode, separating the oil-gas mixture discharged from the fixed-frequency compression unit 201 by the oil-gas separator 1 to obtain oil, and making the oil flow through the temperature control valve 8, the oil cooler 9 and the oil filter 10 corresponding to the fixed-frequency compression unit 201 in sequence to enter the fixed-frequency compression unit 201, wherein:

[0102] the temperature control valve 8, the oil cooler 9 and the oil filter 10 corresponding to the fixed-frequency compression unit 201 are connected in sequence, the temperature control valve 8 is connected to the bottom of the oil-gas separator 1, and the oil filter 10 is connected to the fixed-frequency compression unit 201.

[0103] In some embodiments, the oil-gas separator 1 is arranged close to the first side wall of the box body, and the compressor further includes an electric control cabinet 12 which is arranged in the box body and close to a second side wall of the box body opposite to the first side wall.

[0104] In some embodiments, the compressor further comprises air filters 7 connected to the compression units 2 and arranged in one-to-one correspondence with the compression units 2. The air filters 7 are arranged at gas inlets of the box body.

[0105] In some embodiments, as shown in FIGS. 6 to 11, the variable-frequency compression unit 202 and the fixed-frequency compression unit 201 can be connected through an oil pipeline, and an oil injection valve 14 is provided on the oil pipeline. The oil injection valve 14 is configured to introduce the oil in the variable-frequency compression unit 202 into the fixed-frequency compression unit 201.

[0106] An embodiment of the present invention further provides a compression system, including the compressor and a control apparatus. The control apparatus is configured to execute the above method for controlling a compressor. According to the compression system using the above compressor, free air delivery of the compressor is adjusted by acquiring a discharge pressure of the compressor and dynamically controlling the working modes of the variable-frequency compression unit 202 and the fixed-frequency compression unit 201 according to the discharge pressure, so that the adjustment method for the free air delivery is more flexible, and the adjustment range of the free air delivery can be expanded, thereby having the advantages of energy saving and efficiency improvement.

[0107] In some embodiments, as shown in FIGS. 12 to 20, the compressor includes a box body (not shown in the figures), an oil-gas separator 1, and at least two compression units 2. The oil-gas separator 1 is arranged in the box body and configured to separate an oil-gas mixture. The at least two compression units 2 are arranged in the box body and respectively connected to the oil-gas separator 1. The at least two compression units 2 are constructed in one of the following forms: both being fixed-frequency compression units 201, both being variable-frequency compression units 202, or being a combination of a fixed-frequency compression unit 201 and a variable-frequency compression unit 202. The at least two compression units 2 are configured to cooperate in providing compressed gas to the oil-gas separator 1.

[0108] The above compressor may be constructed as an air-cooled compressor or a water-cooled compressor. FIGS. 12 to 14 are structural diagrams of an air-cooled compressor according to a first embodiment, FIGS. 15 to 17 are structural diagrams of an air-cooled compressor according to a second embodiment, and FIGS. 18 to 20 are structural diagrams of a water-cooled compressor.

[0109] Specifically, as shown in FIGS. 12 and 14, the air-cooled compressor according to the first embodiment includes two compression units 2, namely a fixed-frequency compression unit 201 and a variable-frequency compression unit 202. The two compression units 2 are respectively connected to the oil-gas separator 1, to cooperate in providing compressed gas to the oil-gas separator 1.

[0110] Specifically, as shown in FIGS. 15 and 17, the second embodiment involves another air-cooled compressor including two compression units 2, namely a fixed-frequency compression unit 201 and a variable-frequency compression unit 202. The two compression units 2 are respectively connected to the oil-gas separator 1, to cooperate in providing compressed gas to the oil-gas separator 1.

[0111] Specifically, as shown in FIGS. 18 and 20, the water-cooled compressor includes two compression units 2, namely a fixed-frequency compression unit 201 and a variable-frequency compression unit 202. The two compression units 2 are respectively connected to the oil-gas separator 1, to cooperate in providing compressed gas to the oil-gas separator 1.

[0112] Specifically, the fact that the at least two compression units 2 are respectively connected to the oil-gas separator 1, can be understood as there is no direct connection relationship between the compression units 2, and the compression units 2 are respectively connected to the oil-gas separator 1 in parallel arrangement.

[0113] Specifically, the above box body can be constructed as a rectangular box body, and can also be constructed as other shapes certainly, such as a hexagonal box body. The box body is configured to cover the oil-gas separator 1 and the compression units 2, and is used as the housing of the whole machine.

[0114] When a gas consuming end corresponding to the compressor operates normally at full load, the at least two compression units 2 can meet the requirements of simultaneous start, simultaneous operation or simultaneous stop; when the gas consuming end requires a small amount of gas, part of the at least two compression units 2 can be stopped, and the gas volume can be adjusted by means of other compression units 2 in operation. For example, when the at least two compression units 2 are constructed as a combination of a fixed-frequency compression unit 201 and a variable-frequency compression unit 202, the operation of the fixed-frequency compression unit 201 can be stopped, and the gas volume can be adjusted by means of the variable-frequency compression unit 202.

[0115] According to the present utility model, the at least two compression units 2 which are respectively connected to the oil-gas separator 1 cooperate in providing compressed gas to the oil-gas separator 1, so that the energy consumption of the compressor is lower than that of a compressor including a single compression unit 2, that is, the energy consumption is reduced; and the above plurality of compression units 2 are respectively connected to the oil-gas separator 1, which can reduce the product size compared to those providing a plurality of oil-gas separators 1, so that the size of the whole compressor can be optimized and the manufacturing cost can be reduced.

[0116] In some embodiments, as shown in FIGS. 12-20, the at least two compression units 2 are constructed as the combination of a fixed-frequency compression unit 201 and a variable-frequency compression unit 202. A buffer tank 4 is provided between the fixed-frequency compression unit 201 and the oil-gas separator 1, and is configured to provide buffering for the fixed-frequency compression unit 201 when the fixed-frequency compression unit 201 is in an unloading state.

[0117] Specifically, the above oil-gas separator 1 and the buffer tank 4 are constructed both as cylindrical tank bodies, and the volume of the oil-gas separator 1 is greater than that of the buffer tank 4.

[0118] In some embodiments, as shown in FIGS. 14 and 20, the buffer tank 4 is provided between the box body and the oil-gas separator 1, and is arranged close to the oil-gas separator 1.

[0119] Specifically, when the above box body is constructed as a rectangular box body, the buffer tank 4 is arranged at one of the corners of the rectangular box body.

[0120] In some embodiments, as shown in FIGS. 12 to 17, the at least two compression units 2 of the air-cooled compressor according to the first embodiment and the air-cooled compressor according to the second embodiment are staggered in the box body.

[0121] Specifically, there are two compression units 2 shown in FIGS. 12 to 17, one of which is arranged close to a first side wall of the box body, relative to the other. The first side wall of the box body can be understood as a side wall located on the left side close to the oil-gas separator 1 in FIG. 13.

[0122] In some embodiments, as shown in FIGS. 12 to 14, the air-cooled compressor according to the first embodiment further comprises an aftercooler 5, first fans 11, and a plurality of oil coolers 9 arranged in one-to-one correspondence with the compression units 2. The aftercooler 5 and the plurality of oil coolers 9 are arranged side by side, and the first fans 11 are arranged above the oil coolers 9 and the aftercooler 5. The first fans 5 can be set as an integral large fan, or can be set as a plurality of small fans arranged side by side. Such a design has a compact structure and a reasonable layout.

[0123] Specifically, as shown in FIGS. 1 and 2, the aftercooler 5 is connected to a gas outlet of the oil-gas separator 1, and is configured to cool the compressed gas separated by the oil-gas separator 1.

[0124] Specifically, as shown in FIGS. 1 and 2, the compressor may further comprise a plurality of temperature control valves 8 which are arranged in one-to-one correspondence with the compression units 2. The temperature control valves 8 are connected to the bottom of the oil-gas separator 1 and the compression units 2, respectively, and are configured to control the oil temperature of oil entering the compression units 2 after being separated by the oil-gas separator 1. The oil coolers 9 are arranged between the temperature control valves 8 and the compression units 2, and are configured to cool the oil entering the compression units 2 by means of the temperature control valves 8.

[0125] Specifically, as shown in FIGS. 1 and 2, the compressor may further comprise oil filters 10, which are arranged between the oil coolers 9 and the compression units 2, and are configured to filter the oil cooled by the oil coolers 9 before entering the compression units 2.

[0126] Specifically, the first fans 11 are configured to exchange heat with the oil coolers 9 and the aftercooler 5 through external gas.

[0127] In some embodiments, as shown in FIGS. 15 to 17, the air-cooled compressor according to the first embodiment further includes an aftercooler 5, first fans 11, and a plurality of oil coolers 9 arranged in one-to-one correspondence with the compression units 2. The plurality of oil coolers 9 are arranged between the compression units 2 corresponding thereto and the box body, the aftercooler 5 is arranged close to any one of the oil coolers 9, and the first fans 11 are arranged at the sides of the plurality of oil coolers 9 and the side of the aftercooler 5 away from the box body in one-to-one correspondence, so as to exchange heat with the oil coolers 9 and the aftercooler 5 through external gas.

[0128] In some embodiments, as shown in FIGS. 12 to 17, a staggered space is formed between the at least two compression units 2 of the air-cooled compressor according to the first embodiment and the air-cooled compressor according to the second embodiment and the box body, and the oil-gas separator 1 is arranged in the staggered space. Such a design has a compact structure and a reasonable layout.

[0129] Specifically, as shown in FIGS. 14 and 17, the above staggered space is defined by the two compression units 2 and the first side wall of the box body.

[0130] In some embodiments, as shown in FIGS. 18 to 20, the at least two compression units 2 are arranged side by side in the box body.

[0131] In some embodiments, as shown in FIG. 20, an accommodating space is formed between the at least two compression units 2 of the water-cooled compressor and the first side wall of the box body, and the oil-gas separator 1 is arranged in the accommodating space. Such a design has a compact structure and a reasonable layout.

[0132] Specifically, the water-cooled compressor includes a fixed-frequency compression unit 201 and a variable-frequency compression unit 202. A buffer tank 4 is provided between the fixed-frequency compression unit 201 and the oil-gas separator 1. The buffer tank 4 is arranged in the above accommodating space.

[0133] In some embodiments, as shown in FIG. 20, the compressor further comprises an aftercooler 5 and a plurality of oil coolers 9 arranged in one-to-one correspondence with the compression units 2. The aftercooler 5 and the oil coolers 9 are sequentially arranged side by side in the accommodating space. Such a design has a compact structure and a reasonable layout.

[0134] In some embodiments, as shown in FIGS. 12 to 20, the compressor further comprises air filters 7 connected to the compression units 2 and arranged in one-to-one correspondence with the compression units 2. The air filters 7 are arranged in the box body and correspond to gas inlets in the box body. The air filters 7 are configured to filter gas impurities entering the compression units 2.

[0135] Specifically, the above air filters 7 are all located above the compression units 2 corresponding thereto.

[0136] In some embodiments, as shown in FIGS. 12 to 20, the oil-gas separator 1 is arranged close to the first side wall of the box body. The compressor further comprises an electric control cabinet 12 which is arranged in the box body and close to a second side wall of the box body opposite to the first side wall.

[0137] In some embodiments, as shown in FIGS. 1, 2 and FIGS. 12 to 20, the compressor also includes intake valves 3, which are connected to the compression units 2 and arranged in one-to-one correspondence with the compression units 2, so that the gas entering through the intake valves 3 is compressed by the corresponding compression units 2 and then enters the oil-gas separator 1.

[0138] In some embodiments, as shown in FIGS. 1 and 2, the compressor also comprises a minimum pressure valve 6 arranged on the gas outlet of the oil-gas separator 1, and the aftercooler 5 is communicated with the oil-gas separator 1 by means of the minimum pressure valve 6. The minimum pressure valve 6 is configured to keep the gas pressure in the oil-gas separator 1 within a preset threshold.

[0139] The working process of the compressor is explained below: external gas enters the compression units 2 through the air filters 7 and the intake valves 3 in sequence, and the gas compressed by the compression units 2 enters the oil-gas separator 1 from inlets corresponding to the compression units 2 respectively. After the oil-gas mixture is separated by the oil-gas separator 1, the obtained gas is discharged to a gas consuming end after passing through the minimum pressure valve 6 and the aftercooler 5 in sequence, wherein the gas consuming end is an end that requires the compressor to provide compressed gas. The oil separated by the oil-gas separator 1 flows through the temperature control valves 8 corresponding to the compression units 2, respectively, and the oil is adjusted to a suitable temperature by the temperature control valves 8, cooled by the oil coolers 9, and then discharged to the compression units 2 after passing through the oil filters 10 for a recycling use.

[0140] In addition, although exemplary embodiments have been described herein, the scope thereof includes any and all embodiments based on the present invention having equivalent elements, modifications, omissions, combinations (e.g., schemes that cross various embodiments), adaptations, or changes. The elements in the claims are to be interpreted broadly based on the language employed in the claims, and are not limited to examples described in this specification or during the implementation of this application, which examples are to be construed as non-exclusive. Accordingly, it is intended that this specification and the examples are considered merely as exemplary, with a true scope and spirit being indicated by the following claims along with the full scope of their equivalents.

[0141] The above description is intended to be illustrative rather than limiting. For example, the above examples (or one or more schemes thereof) may be used in combination with each other. Other embodiments may be used by those of ordinary skill in the art after reading the above description for example. In addition, in the above specific implementations, various features can be grouped together to simplify the present invention, which should not be interpreted as intending that an unclaimed disclosed feature is essential to any claim. Rather, the subject matter of the present invention may lie in less than all features of a particular disclosed embodiment. Thus, the following claims are hereby incorporated into the specific implementations as examples or embodiments, with each claim standing on its own as a separate embodiment, and it is contemplated that these embodiments can be combined with each other in various combinations or permutations. The scope of the present invention should be determined with reference to the appended claims along with the full scope of equivalents to which these claims are entitled.

[0142] The above embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the present invention. The scope of protection of the present invention is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to the present invention within the essence and scope of protection of the present invention, and such modifications or equivalent substitutions should also be deemed to fall within the scope of protection of the present invention.

Claims

1. A method for controlling the compressor, <b>characterized by comprising: acquiring a discharge pressure of the compressor; and dynamically controlling working modes of the variable-frequency compression unit and the fixed-frequency compression unit according to the discharge pressure, so as to adjust free air delivery of the compressor, wherein: the working modes at least comprise a stopping working mode, a loading working mode and an unloading working mode, and the variable-frequency compression unit and the fixed-frequency compression unit are respectively connected to an oil-gas separator, so that compressed gas is supplied to the oil-gas separator via the variable-frequency compression unit and the fixed-frequency compression unit in cooperation.

2. The method for controlling the compressor of claim 1, <b>characterized in that, dynamically controlling the working modes of the variable-frequency compression unit and the fixed-frequency compression unit according to the discharge pressure specifically comprises: in a case where the discharge pressure is less than a first preset pressure, controlling the variable-frequency compression unit to enter the loading working mode and continuously load, and controlling the fixed-frequency compression unit to enter the stopping working mode; and in a case where the discharge pressure is greater than or equal to the first preset pressure, controlling both the variable-frequency compression unit and the fixed-frequency compression unit to enter the stopping working mode.

3. The method for controlling the compressor of claim 2, characterized in that, after controlling the variable-frequency compression unit to enter the loading working mode and continuously load, the method further comprises: in a case where the discharge pressure is greater than or equal to the first preset pressure and the discharge pressure is less than a fourth preset pressure, controlling the variable-frequency compression unit to remain in the loading working mode and controlling the fixed-frequency compression unit to enter the stopping working mode, wherein: the fourth preset pressure is greater than the first preset pressure.

4. The method for controlling the compressor of any one of claims 2 and 3, characterized by further comprising: in a case where the discharge pressure is greater than or equal to the fourth preset pressure, controlling the variable-frequency compression unit to enter the unloading working mode and the fixed-frequency compression unit to remain in the stopping working mode.

5. The method for controlling the compressor of claim 4, <b>characterized in that, after controlling the variable-frequency compression unit to enter the unloading working mode and the fixed-frequency compression unit to remain in the stopping working mode, the method further comprises: determining whether the discharge pressure is greater than or equal to the first preset pressure; if yes, controlling the variable-frequency compression unit to remain in the unloading working mode and the fixed-frequency compression unit to remain in the stopping working mode; and if no, controlling the variable-frequency compression unit to enter the loading working mode and the fixed-frequency compression unit to remain in the stopping working mode.

6. The method for controlling the compressor of claim 5, <b>characterized in that, after controlling the variable-frequency compression unit to remain in the unloading working mode and the fixed-frequency compression unit to remain in the stopping working mode, the method further comprises: determining whether a duration of the variable-frequency compression unit remaining in the unloading working mode exceeds a third preset time; and if yes, controlling both the variable-frequency compression unit and the fixed-frequency compression unit to enter the stopping working mode.

7. The method for controlling the compressor of claim 2, <b>characterized in that, after controlling the variable-frequency compression unit to enter the loading working mode and continuously load, the method further comprises: in a case where the discharge pressure is less than a second preset pressure, controlling the fixed-frequency compression unit to enter the unloading working mode and the variable-frequency compression unit to remain in the loading working mode; or, in a case where the discharge pressure is less than the first preset pressure and greater than the second preset pressure and the duration exceeds a first preset time, controlling the fixed-frequency compression unit to enter the unloading working mode and the variable-frequency compression unit to remain in the loading working mode, wherein the first preset pressure is greater than the second preset pressure.

8. The method for controlling the compressor of claim 7, <b>characterized in that, after controlling the fixed-frequency compression unit to enter the unloading working mode, the method further comprises: determining whether the discharge pressure is less than the second preset pressure; or, determining whether the discharge pressure is less than the first preset pressure and the discharge pressure is greater than or equal to the second preset pressure and the duration exceeds the first preset time, if yes, controlling the fixed-frequency compression unit to enter the loading working mode and continuously load, and the variable-frequency compression unit to remain in the loading working mode; and if no, controlling the fixed-frequency compression unit to remain in the unloading working mode and the variable-frequency compression unit to remain in the loading working mode.

9. The method for controlling the compressor of claim 8, <b>characterized in that, after controlling the fixed-frequency compression unit to enter the loading working mode and continuously load and the variable-frequency compression unit to remain in the loading working mode, the method further comprises: determining whether the discharge pressure is greater than or equal to a third preset pressure; and if yes, controlling the fixed-frequency compression unit to enter the unloading working mode and the variable-frequency compression unit to remain in the loading working mode, wherein: the third preset pressure is greater than the first preset pressure.

10. The method for controlling the compressor of claim 9, <b>characterized by further comprising: determining whether the discharge pressure is greater than or equal to a fourth preset pressure; if yes, controlling the variable-frequency compression unit to enter the unloading working mode and the fixed-frequency compression unit to remain in the unloading working mode; and if no, controlling the fixed-frequency compression unit to remain in the unloading working mode and the variable-frequency compression unit to remain in the loading working mode, wherein: the fourth preset pressure is greater than the third preset pressure.

11. The method for controlling the compressor of any one of claims 8 or 10, <b>characterized in that, after controlling the fixed-frequency compression unit to remain in the unloading working mode and the variable-frequency compression unit to remain in the loading working mode, the method further comprises: determining whether a duration of the fixed-frequency compression unit remaining in the unloading working mode exceeds a second preset time; and if yes, controlling the fixed-frequency compression unit to enter the stopping working mode and the variable-frequency compression unit to remain in the loading working mode.

12. The method for controlling the compressor of claim 10, <b>characterized in that, after controlling the variable-frequency compression unit to enter the unloading working mode and the fixed-frequency compression unit to remain in the unloading working mode, the method further comprises: determining whether the discharge pressure is greater than or equal to the first preset pressure; if yes, controlling the variable-frequency compression unit to remain in the unloading working mode and the fixed-frequency compression unit to remain in the unloading working mode; and if no, controlling the variable-frequency compression unit to enter the loading working mode and the fixed-frequency compression unit to enter the unloading working mode.

13. The method for controlling the compressor of claim 12, <b>characterized in that, after controlling the variable-frequency compression unit to remain in the unloading working mode and the fixed-frequency compression unit to remain in the unloading working mode, the method further comprises: determining whether the duration of the variable-frequency compression unit remaining in the unloading working mode exceeds the third preset time; and if yes, controlling both the variable-frequency compression unit and the fixed-frequency compression unit to enter the stopping working mode.

14. The method for controlling the compressor of any one of claims 3 or 10, <b>characterized by further comprising: determining whether the discharge pressure is greater than or equal to a fifth preset pressure; and if yes, controlling the fixed-frequency compression unit and the variable-frequency compression unit to enter the stopping working mode, wherein: the fifth preset pressure is greater than the fourth preset pressure.

15. The method for controlling the compressor of claim 1, characterized by further comprising: in a case where the variable-frequency compression unit enters the loading working mode, the oil-gas mixture discharged from the variable-frequency compression unit is separated by the oil-gas separator to obtain gas and oil, cooling the gas by an aftercooler and then discharging the cooled gas, and cooling the oil by an oil cooler and then returning the cooled oil to the variable-frequency compression unit, wherein: the aftercooler is connected to the oil-gas separator to cool the gas separated by the oil-gas separator, and the oil cooler is connected to the variable-frequency compression unit and the oil-gas separator respectively.

16. The method for controlling a compressor of claim 1, characterized by further comprising: in a case where the variable-frequency compression unit enters the unloading working mode, passing an oil-gas mixture discharged from the variable-frequency compression unit through the oil-gas separator and a venting pipeline, emptying the gas in the oil-gas separator through the variable-frequency compression unit, separating the oil-gas mixture discharged from the variable-frequency compression unit by the oil-gas separator to obtain oil, and cooling the oil by the oil cooler and then returning the cooled oil to the variable-frequency compression unit.

17. The method for controlling a compressor of claim 15, characterized by further comprising: in a case where the fixed-frequency compression unit enters the loading working mode, the oil-gas mixture discharged from the fixed-frequency compression unit is separated by the oil-gas separator to obtain gas, and cooling the gas by the aftercooler and then discharging the cooled gas; the oil-gas mixture discharged from the fixed-frequency compression unit is separated by the oil-gas separator to obtain oil, and cooling the oil by the oil cooler and making the cooled oil enter the fixed-frequency compression unit, wherein: the aftercooler is connected to the oil-gas separator to cool the gas separated by the oil-gas separator.

18. The method for controlling a compressor of claim 1 or any one of claims 15 to 16, characterized by further comprising: in a case where the fixed-frequency compression unit enters the unloading working mode, making an oil-gas mixture discharged from the fixed-frequency compression unit enter a buffer tank, making the gas enter the variable-frequency compression unit via the buffer tank, and making the oil enter the fixed-frequency compression unit via a combination valve, wherein: the buffer tank is provided between the fixed-frequency compression unit and the oil-gas separator, and the combination valve is connected to the oil-gas separator, the buffer tank, the oil cooler and an oil filter respectively.

19. A compression system, characterized by comprising the compressor and a control apparatus, the control apparatus is configured to execute the method for controlling the compressor of any one of claims 1 to 18.

20. The compression system of claim 19, <b>characterized in that, the compressor comprises a box body, and further comprises: an oil-gas separator, arranged in the box body and configured to separate the oil-gas mixture; and at least two compression units, arranged in the box body and respectively connected to the oil-gas separator, wherein the at least two compression units are constructed in one of the following forms: both being fixed-frequency compression units, both being variable-frequency compression units, or being a combination of the fixed-frequency compression unit and the variable-frequency compression unit, and the at least two compression units are configured to cooperate in providing compressed gas to the oil-gas separator.

21. The compression system of claim 20, characterized in that, the at least two compression units are constructed as a combination of a fixed-frequency compression unit and a variable-frequency compression unit, wherein a buffer tank is provided between the fixed-frequency compression unit and the oil-gas separator, and is configured to provide buffering for the fixed-frequency compression unit when the fixed-frequency compression unit is in an unloading state.

22. The compression system of claim 21, characterized in that, the buffer tank is provided between the box body and the oil-gas separator, and is arranged close to the oil-gas separator.

23. The compression system of claim 20, characterized in that, the at least two compression units are staggered in the box body24. The compression system of claim 20, characterized in that, the at least two compression units are arranged side by side in the box body.

25. The compression system of claim 23, characterized in that, the compressor further comprises an aftercooler, a first fan, and a plurality of oil coolers arranged in one-to-one correspondence with the compression units, wherein the aftercooler and the plurality of oil coolers are arranged side by side, and the first fan is arranged above the oil coolers and the aftercooler.

26. The compression system of claim 23, characterized in that, the compressor further comprises an aftercooler, first fans, and a plurality of oil coolers arranged in one-to-one correspondence with the compression units, wherein the plurality of oil coolers are arranged between the compression units corresponding thereto and the box body, the aftercooler is arranged close to any one of the oil coolers, and the first fans are arranged at the sides of the plurality of oil coolers and the side of the aftercooler away from the box body in one-to-one correspondence.

27. The compression system of claim 23, characterized in that, a staggered space is formed between the at least two compression units and the box body, and the oil-gas separator is arranged in the staggered space.

28. The compression system of claim 24, characterized in that, an accommodating space is formed between the at least two compression units and a first side wall of the box body, and the oil-gas separator is arranged in the accommodating space.

29. The compression system of claim 28, characterized in that, the compressor further comprises an aftercooler and a plurality of oil coolers arranged in one-to-one correspondence with the compression units, wherein the aftercooler and the oil coolers are sequentially arranged side by side in the accommodating space.

30. The compression system of claim 20, characterized in that, the compressor further comprises air filters connected to the compression units and arranged in one-to-one correspondence with the compression units, wherein the air filters are arranged in the box body and correspond to gas inlets in the box body.

31. The compression system of claim 20, characterized in that, the oil-gas separator is arranged close to a first side wall of the box body, and the compressor further comprises an electric control cabinet which is arranged in the box body and close to a second side wall of the box body opposite to the first side wall.

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