Air compressor with internal frequency converter capable of stopping pressurization unloading

Abstract

An air compressor (101) having an electrical frequency converter (165) that controls an air compression assembly (122), where the electrical frequency converter (165) is located inside the air compressor (101) and housed in an electrical cabinet (123). During an unloading phase and a stop phase of the air compressor (101), the pressure within the pressure vessel (121) is maintained at an elevated level, thereby reducing the time and power required to return the air compressor (101) to a full load state.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to an air compressor with an internal frequency inverter that allows stopping the pressurized unloading. BACKGROUND

[0002] A rotary screw air compressor is a positive displacement gas compressor that uses two rotors to generate the required pressure for air compression. The two rotors rotate in opposite directions to suck in air, which is compressed as the space between the rotors and the rotor housing decreases. Each screw element has a fixed built-in pressure ratio, which depends on the length and pitch of the screw and the form of the discharge port. To achieve the highest efficiency, the built-in pressure ratio must be adapted to the required working pressure. The sequence of operation of these compressors is determined by the pressure value, and different scenarios that occur in the plant present different compressor operation loads, such as no load, standby, ready to operate, and loading settings. Different air compression requirements of the plant can be met with different types of compressors, such as variable speed drive (VSD) or fixed speed drive compressors.

[0003] Conventional fixed speed compressors operate with a fixed number of revolutions per minute (RPM) over time and provide a constant frequency output to the motor. To adjust the air flow, fixed speed air compressors require adjustment of the air inlet valve to discharge more or less air. Conventional fixed speed compressors also switch between two operating states: a) no load; and b) load. During the no load state, air is recirculated within the compressor and no air flow is generated. Once the pressure in the compressor outlet reaches the unloading pressure level, the motor is unloaded and then stopped. When the compressed air is partially used, the pressure of the air storage tank decreases. After the pressure reaches the loading pressure level, the motor is started again, driving the air compressor to work. After a certain amount of operating time, the motor is frequently started and stopped, and the motor consumes more electrical energy during the start and stop process. To prevent the current level from reaching an elevated level, the internal compressor system is de-pressurized before restarting. Once the motor is stopped, the energy consumed by the frequent start and stop of the motor increases. The disadvantage of conventional fixed speed compressors is that the motor always operates at the same fixed speed, even when the air demand is low. This therefore results in a less energy efficient process and wastes energy due to the large number of start / stop and high transient losses.

[0004] VSD compressors increase the speed of the motor as the demand for air increases, thereby supplying more flow. If the demand for air decreases, the motor will automatically slow down, using only the energy needed to provide the appropriate flow. VSD compressors are particularly useful on low production days or during work process breaks. This type of air compressor saves power and energy costs compared to traditional fixed speed models. VSD compressors utilize the motor's variable speed regulation feature to maintain air pressure stability, thereby responding to air flow needs according to the plant's real-time demand. While VSD compressors are more energy efficient in most applications, if the compressed air demand is constant, or even nearly constant, with only occasional minor variations, a VSD compressor is not necessary. For example, if a compressed air application runs assembly line machinery 10-12 hours a day, the investment in a variable speed compressor will require additional upfront capital costs.

[0005] Fixed speed compressors are unable to perform star-delta start when the pressure within the pressure vessel is high, which further exacerbates the inefficiencies of fixed speed compressors. Doing so causes a surge in drawn current, leading to losses and potential failure. There remains a need in the art for a compressor with improved efficiency that can meet the needs of customers with different applications. SUMMARY

[0006] Embodiments of the present disclosure relate to an air compressor comprising a housing comprising a pressure vessel and an electrical cabinet and an air compression assembly located within the housing and configured to compress air for a customer application. The air compressor has a variable frequency drive located within the electrical cabinet, the variable frequency drive defining a speed of the air compression assembly, and the variable frequency drive operating the air compression assembly to compress air into the pressure vessel in at least three phases, a loading phase, an unloading phase, and a stop phase. During the loading phase, the variable frequency drive causes the air compression assembly to compress air into the pressure vessel, the pressure vessel having an outlet port from which compressed air is selectively discharged according to the customer application. During the unloading phase, the compressed air in the pressure vessel is maintained and air is recirculated internally and / or vented to near atmospheric pressure, and during the stop phase, the air compression assembly is stopped and the pressure within the pressure vessel is maintained. During a subsequent loading phase, the variable frequency drive starts without causing a surge in drawn current.

[0007] Further embodiments of the present disclosure relate to a method for operating an air compressor having an internal variable frequency drive that powers an air compression assembly. The method includes loading a pressure vessel of the air compressor with compressed air from the air compression assembly to a first pressure level, venting compressed air from the pressure vessel, and unloading compressed air from the pressure vessel. The unloading includes sealing the pressure vessel to comply with a customer's application and reducing air pressure within the pressure vessel by recirculating and / or venting air to reduce the air pressure within the pressure vessel to near atmospheric pressure. During the unloading phase, the compressed air in the pressure vessel is internally recirculated and / or vented to reduce the air pressure in the pressure vessel to a second pressure level near atmospheric pressure, the second pressure level being lower than the first pressure level, and the power consumption is operated at a reduced rate. The air compression assembly is stopped using the internal variable frequency drive with the air pressure within the pressure vessel maintained at the second pressure level lower than the first pressure level. The pressure vessel of the air compressor is loaded with compressed air from the air compression assembly by raising the pressure from the second level to the first level and not allowing the air pressure to drop below the second air pressure.

[0008] Still further embodiments of the present disclosure relate to a method of operating an air compressor. The method includes performing a loading phase, an unloading phase, a stopping phase, and a reloading phase. In the loading phase, an internal variable frequency drive located within a housing of the air compressor powers an air compression assembly that pressurizes air into a pressure vessel, and the pressure in the pressure vessel reaches a first pressure level. In the unloading phase, the internal variable frequency drive de- speeds the air compression assembly, and the pressure within the pressure vessel is reduced to a second pressure level lower than the first pressure level. During the unloading phase, the pressure vessel is sealed to comply with a customer's application, and the pressure in the pressure vessel is reduced to the second pressure level. In the stopping phase, the motor is stopped and the pressure in the pressure vessel is maintained at the second pressure level. In the reloading phase, the internal variable frequency drive powers the air compression assembly to raise the pressure from the second pressure level to the first pressure level without allowing the pressure in the pressure vessel to fully dissipate. BRIEF DESCRIPTION OF DRAWINGS

[0009] The features, aspects, and advantages of the presently disclosed technology can be better understood with regard to the following description, appended claims, and accompanying drawings. Those skilled in the relevant art will understand that features shown in the drawings are for purposes of illustration and that variations or additional features are possible in different or additional embodiments.

[0010] Figure 1 FIG. 1 illustrates example components of an example multi-mode compressor system.

[0011] FIG. 2 is a plot of torque versus speed of a motor of an air compressor according to an embodiment of the prior art.

[0012] Figure 3 It is a curve of torque versus speed of the motor of the air compressor according to this disclosure.

[0013] The accompanying drawings are for illustrative purposes only and are not drawn to scale. It should be understood that the invention is not limited to the arrangements and means shown in the drawings.

[0014] definition:

[0015] To facilitate understanding of the disclosed embodiments of the methods and system components, some terms need to be described.

[0016] The term "compressor" or "compressor equipment" refers to a machine that draws low-pressure gas from an auxiliary storage device as a raw input and then outputs high-pressure gas for storage or supply to other processes. The terms "compressor" and "compressor equipment" are not intended to be limiting, but can refer to displacement compressors and / or dynamic compressors (turbo compressors) and / or discrete components of compressors.

[0017] The term "computer storage medium" refers to a physical storage medium that stores computer-executable instructions and / or data structures. Storage media such as digital data carriers include computer hardware such as random access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), solid-state drives (SSDs), flash memory, phase-change memory (PCM), optical disc storage, disk storage, and the like.

[0018] The term "controller" or "controller unit" generally refers to a computerized command terminal that includes a collection of sensors and electrical components, i.e., for regulating various compressor components. A compressor controller includes at least one main processing unit with a graphical interface and instruments adapted to monitor various compressor parts, such as motors, rotors, filters, bearings, valves, pressure sensors, and temperature sensors.

[0019] The term "processor" or "processing unit" refers to one or more devices, circuits, and / or processing cores configured to process data such as computer program instructions, and includes personal computers, desktop computers, laptop computers, message processors, handheld devices, multiprocessor systems, microprocessor-based or programmable consumer electronics, network computers, minicomputers, mainframe computers, mobile phones, personal digital assistants (PDAs), tablet computers, pagers, routers, switches, and the like.

[0020] The term "software" generally refers to computer-executable instructions, code, data, applications, programs, program modules, and the like, which are stored in or on any form or type of computer-readable medium configured to store computer-executable instructions or the like in a manner accessible to a computing device.

[0021] As used herein, references to any type of machine learning or artificial intelligence may include any type of machine learning algorithm or device, (one or more) convolutional neural networks, (one or more) multilayer neural networks, (one or more) recurrent neural networks, (one or more) recurrent neural networks, (one or more) deep neural networks, (one or more) decision tree models (e.g., decision trees, random forests, and gradient boosting trees), (one or more) linear regression models, (one or more) logistic regression models, (one or more) support vector machines (SVMs), (one or more) artificial intelligence devices, or any other type of intelligent computing system. Machine learning algorithms can be trained to dynamically perform the disclosed operations using any amount of training data (and potentially refined later).

[0022] When elements are described in the appended claims, the articles “a,” “an,” “the,” and “the” are intended to mean the presence of one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that additional elements may be present in addition to the listed elements. Detailed Implementation

[0023] Different embodiments of this disclosure can be better understood by reading the following description in conjunction with the accompanying drawings, in which the same reference numerals refer to the same elements.

[0024] While this disclosure may have various modifications and alternative constructions, certain illustrative embodiments are shown in the accompanying drawings and described below. Dimensions, angles, and curvatures represented should be understood as exemplary and not necessarily shown to scale.

[0025] However, it should be understood that this disclosure is not intended to be limited to the specific embodiments disclosed, but rather to cover all modifications, alternative constructions and equivalents that fall within the spirit and scope of this disclosure.

[0026] Figure 1 Various example components are illustrated for an example compressor system 100 (e.g., a multi-mode compressor system) that may include or implement one or more of the disclosed embodiments. For example, Figure 1The illustration shows a compressor system 100 that may include one or more processors 102, memory 104, one or more sensors 110, one or more input / output systems 114 (I / O systems 114), one or more communication systems 116, and / or other components. Although Figure 1 The compressor system 100 is illustrated as including specific components; however, in view of this disclosure, one will appreciate that the compressor system 100 may include any number of additional or alternative components. Furthermore, although some of the components may be illustrated or described as different entities, in view of this disclosure, one will appreciate that such differences are made only for purposes of explanation / description. For example, the function associated with a particular component described herein may be performed by different components or combinations of components as described herein. Therefore, according to this disclosure, aspects of the components described herein may be combined with other components or divided into multiple components. Additionally, aspects of this disclosure may be incorporated into oil-free compressors and various types of multistage compressors.

[0027] Processor 102 (one or more) may include one or more sets of electronic circuitry systems, including any number of logic units, registers, and / or control units to facilitate the execution of computer-readable instructions (e.g., instructions forming a computer program). Such computer-readable instructions may be stored in memory 104 (e.g., instruction 106). Memory 104 may include physical system memory and may be volatile, non-volatile, or some combination thereof. Furthermore, memory 104 may include local memory, remote memory (e.g., accessible via communication system 116 or otherwise), or some combination thereof. Additional details relating to the processor (e.g., processor 102 (one or more)) and computer storage media (e.g., memory 104) are provided below.

[0028] In some implementations, processor(s)102 may include or be configured to execute any combination of software and / or hardware components operable to facilitate processing using machine learning models or other artificial intelligence-based architectures. For example, processor (one or more) 102 may include and / or utilize hardware components or computer-executable instructions operable to execute function blocks and / or processing layers configured in the form of (e.g., but not limited to): single-layer neural networks, feedforward neural networks, radial basis function networks, deep feedforward networks, recurrent neural networks, long short-term memory (LSTM) networks, gated recurrent units, autoencoder neural networks, variational autoencoders, denoising autoencoders, sparse autoencoders, Markov chains, Hopfield neural networks, Boltzmann machine networks, restricted Boltzmann machine networks, deep belief networks, deep convolutional networks (or convolutional neural networks), deconvolutional neural networks, deep convolutional inverse graph networks, generative adversarial networks, liquid machines, extreme learning machines, echo state networks, deep residual networks, Kohonen networks, support vector machines, neural Turing machines, and / or other forms.

[0029] As will be described in more detail, processor(s) 102 may be configured to execute instructions 106 stored in memory 104 to perform certain actions associated with the operation of compressor system 100. These actions may depend at least in part on data 108 stored in memory 104 in a volatile or non-volatile manner.

[0030] In some cases, operation may depend at least in part on one or more communication systems 116 for receiving data from other components and / or one or more remote systems 118, which may include, for example, separate systems or computing devices, sensors, and / or other components. The one or more communication systems 116 may include any combination of software or hardware components operable to facilitate communication between components / devices on the system and / or with components / devices outside the system. For example, the one or more communication systems 116 may include ports, buses, or other physical connection devices for communicating with other devices / components. Additionally or alternatively, the one or more communication systems 116 may include systems / components operable to wirelessly communicate with external systems and / or devices via any suitable communication channel, such as, but not limited to, Bluetooth, ultra-wideband, wireless local area network (WLAN), infrared communication, and / or other communication channels.

[0031] Figure 1The illustration shows that the compressor system 100 may include one or more sensors 110 or communicate with (e.g., to obtain data 108 for performing the actions described herein). The one or more sensors 110 may include any device for capturing or measuring data representing a perceptible or detectable phenomenon. As a non-limiting example, the one or more sensors 110 may include one or more flow sensors, pressure sensors, hygrometers, image sensors, microphones, thermometers, barometers, magnetometers, accelerometers, gyroscopes, and / or other sensors.

[0032] also, Figure 1 The illustration shows that compressor system 100 may include or communicate with I / O system 114. I / O system 114 (one or more) may include any type of input or output device, such as, by way of non-limiting example, a display, touch screen, mouse, keyboard, controller, speaker and / or other device, but is not limited thereto.

[0033] Figure 1 Additional example components of or in communication with the compressor system 100 are also illustrated. For example, Figure 1 The illustration shows a compressor system 100, which includes a compressor 101 and a compressor motor 120 configured to actuate a compressor assembly 122 to compress a gas (e.g., compress ambient air). The compressor motor 120 can take any suitable form, such as a three-phase induction motor. Similarly, the compressor assembly 122 can take any suitable form, such as any type of dynamic compressor (e.g., jet, centrifugal, or axial compressor) or displacement compressor, such as a rotary compressor (e.g., a single-rotor compressor, such as a vane, liquid ring, or scroll compressor; or a multi-rotor compressor, such as a screw, gear, or blower compressor) or a reciprocating compressor.

[0034] Figure 1 Various additional components that can operate together with the compressor motor 120 and compressor assembly 122 to facilitate gas compression are also illustrated. Figure 1 The compressor system is illustrated as including an inlet filter 124, a warning valve 126, an air / oil container separator 128, a thermostatic bypass valve 130, an oil filter 132, a safety valve 134, an oil separator 136, a minimum pressure valve 138, a solenoid valve 140, an aftercooler 142, a fan 144, an oil cooler 146, an electronic discharge device 148, a dryer 150 (in embodiments where the dryer 150 is omitted, the electronic discharge device pipe 148 may be mounted on the aftercooler 142), and an anti-condensation cycle 152. As noted above, within the scope of this disclosure, components such as the inlet filter 124, the air / oil container separator 128 ...Figure 1 One or more of the components shown, or alternative components / structures may be used.

[0035] Figure 1 The compressor system 100 is also illustrated as including a frequency converter 160, which is configured to be connected to a power supply 162 and a compressor motor 120 (e.g., Figure 1 (Indicated by the dashed lines extending from power source 162 to frequency converter 160 and from frequency converter 160 to compressor motor 120). As discussed above, frequency converter 160 controls the operating speed of compressor motor 120 by controlling the frequency and voltage of compressor motor 120. Frequency converter 160 may include rotary frequency converters, solid-state frequency converters, etc. Power source 162 may include grid-connected power supply or off-grid power supply.

[0036] Figure 1 The operation of the frequency converter 160 (and / or compressor motor 120) is described as being controllable by a multi-mode drive controller 164 (e.g., Figure 1 (Indicated by the dashed line extending from the multi-mode drive controller 164 to the frequency converter 160 and the compressor motor 120). The multi-mode drive controller 164 may include one or more processors 102 or operate in conjunction with one or more processors 102 to control the operation of the frequency converter 160 and / or the compressor motor 120.

[0037] According to the first embodiment, the multi-mode controller is configured to operate the frequency converter 160 and / or the compressor motor 120 according to a plurality of operating modes, the plurality of operating modes including at least a first compression mode 166 and a second compression mode 168 (e.g., ...). Figure 1(Indicated by the solid lines extending from the multi-mode drive controller 164 to the first compression mode 166 and the second compression mode 168). The first compression mode 166 and the second compression mode 168 are associated with different operating motor speed distributions. For example, the first compression mode 166 may include a load / unload compression mode, and the second compression mode 168 may include a variable speed drive (VSD) mode. As noted above, the load / unload compression mode may be associated with multiple states, such as a load state (to provide compressed air / gas), an unload state (e.g., idling), or a stop state (e.g., which may be implemented after idling for a period of time). During the load state (and often the unload state), the compressor motor 120 operates at a substantially constant operating motor speed. For example, this can be achieved by configuring the frequency converter 160 via the multi-mode drive controller 164 to apply a substantially constant frequency and voltage to the compressor motor 120 for operation in a loaded state of the loading / unloading compression mode, or by bypassing one or more aspects of the frequency converter 160 via the multi-mode drive controller 164 to allow a constant frequency and voltage to be supplied to the compressor motor 120 from the power supply 162 and / or one or more intermediary components.

[0038] As noted above, the VSD mode is associated with the variable operating motor speed of the compressor motor 120, which can be achieved by dynamically modifying the frequency and voltage used for the operation of the compressor motor 120 via the multi-mode drive controller 164. The motor speed (and / or associated voltage / frequency) of the compressor motor 120 can be dynamically determined based on the requirements associated with the use of the compressor system, such as the requested compressed air flow rate, the current compressed air pressure of the compressor system 100, etc.

[0039] According to other embodiments, the multi-mode controller is configured to operate one or more other control components of the compressor system according to multiple operating modes, including at least a first compression mode and a second compression mode. Such control components may include one or more solenoids, one or more control timers, and / or one or more pressure vessel controls.

[0040] According to embodiments of this disclosure, an air compressor 101 is provided having an electrical inverter 165 located within an electrical box 123, which is arranged within a housing 119 of the compressor 101. The air compressor 101 also includes a pressure vessel 121 and an assembly 122, also within the housing 119. The electrical box 123 of the air compressor 101 can be conveniently positioned relative to the pressure vessel 121 and the assembly 122, such that the inverter 165 within the electrical box 123 can supply power to the assembly 122. In one embodiment, the pressure vessel 121 is provided with an outlet port 125 from which compressed air is selectively discharged. The inverter 165 is directly coupled to the assembly 122 of the air compressor 101 and does not involve any gears connecting power to the assembly 122. Gear-based solutions involve configurations such as geared star-delta (YD) starting, which induce large current spikes during startup. This system does not induce such spikes, thereby improving efficiency and reducing wear and tear on components. Direct connection allows the air compressor to achieve a wide range of pressures by varying the operating speed of component 122. In an alternative embodiment, frequency converter 165 may be connected to air compressor assembly 122 by means of resilient or flexible couplings, belts, gears, or bearings.

[0041] Figure 2 is a graph 200 showing the pressure in a pressure vessel according to the prior art and the power required to achieve that pressure, both varying over time according to the operating phases (loading, unloading, and stopping). Graph 200 begins at a loading stop at 202, where the air compressor is started and steady-state operating conditions are achieved. 204 indicates the start of the unloading phase, which concludes at 206, which also indicates the start of the stopping phase. At 208, the cycle continues into a second loading phase, also known as a reloading phase, which may differ from the initial loading phase that begins at 202. In the first loading phase, block 212 represents the power required to achieve the desired pressure in the pressure vessel of the air compressor, and line 201 represents the pressure in the vessel. The disadvantages of this cycle in air compressors with gear drives and indirect connection to a power source will be described in more detail below.

[0042] The initial loading operation is characterized by a sharp increase in pressure and power required to achieve a quasi-steady state. During the unloading phase at 204, the pressure drops sharply and then continuously. The power required in this phase is characterized by two blocks: first, the transient loss block at 214, and second, the unloading power at 216. The unloading power is not necessarily a loss, but transient losses are and can be avoided by the systems and methods described herein as the subject of this disclosure.

[0043] At 206, the stopping phase begins, where the unloading process is complete and the pressure inside the pressure vessel drops to zero. At 217, transient losses continue in this phase. These losses are unavoidable in conventional geared air compressors without internal frequency converters. One reason is that at 208, when the next loading phase begins, a large starting current is required to load the system if there is pressure in the pressure vessel, as shown by ramp 218. These current peaks correspond to higher resource costs and higher overall losses. Curve 200 ends at 210, and at 220 is the full-load phase with utilized power, and pressure returns to the pressure vessel.

[0044] Figure 3 The present disclosure includes a graph 221 showing the pressure in the pressure vessel and the power required to achieve that pressure, both varying over time according to the operation phases (loading, unloading, and stopping), and includes an internal frequency converter directly coupled to the element. The initial loading phase at 202 can be the same as the system of FIG. 2, characterized by a steep ramp of pressure and associated power required to achieve that pressure, and a block 222 representing the power consumed to achieve that pressure, followed by a quasi-steady-state operation period. At 204, the unloading phase begins and is characterized by a decrease in pressure in the vessel, some transient losses at 224, and unloading power at 226. However, during the stopping phase at 206, the pressure in the pressure vessel is maintained at a non-zero level slightly less than the pressure decrease during the loading phase. In some embodiments, the pressure in this phase is approximately 45% of the pressure during the full-load phase. In some embodiments, the pressure in this phase is in the range of 25%–100% of the pressure during the loading phase.

[0045] It is worth noting that the transient loss shown at 217 in Figure 2 is... Figure 3 The pressure vessel is not present. It can be suitably sealed to maintain pressure during the shutdown phase. In some embodiments, the air compressor according to this disclosure may include a timer and routine to release pressure in the vessel after a predetermined time has elapsed at elevated pressure. The predetermined time can be any arbitrary period of time, such as five minutes. When the predetermined time expires, nearby personnel can be alerted that the time has elapsed and the pressure will be released. The pressure can be released slowly and safely to avoid injuring anyone nearby when the timer expires. In some embodiments, external events or conditions such as condensation, humidity, or air pressure may cause discharge to begin. In some embodiments, pressure is never released until the next phase begins or the equipment is shut down.

[0046] At 208, the second loading phase can begin, exhibiting a much smaller power requirement 228 than at 218 in Figure 2. The power required to achieve this pressure is shown at 230. In systems with internal frequency converters directly connected to the components, the pre-existing pressure is not an obstacle to overcome; rather, this portion has already been handled and does not require repeated handling. This gives the compressor a head start. The result is lower current draw, less power demand, shorter time to reach full load, and higher overall efficiency. At 210, the second loading phase ends, and can be followed by a second unloading phase at 204, and the cycle continues.

[0047] It should be understood that not all objectives or advantages may be achieved under any embodiment of this disclosure. Those skilled in the art will recognize that the claimed compressor equipment may be embodied or performed in a manner that achieves or optimizes one or more advantages of the teachings herein without achieving other objectives or advantages of the teachings or suggestions herein.

[0048] Skilled artisans will recognize the interchangeability of the various disclosed features. In addition to the variations described herein, those skilled in the art can mix and match other known equivalents of each feature to construct and use compressor equipment based on the principles of this disclosure. For example, the frequency converter of the disclosed fixed-speed compressor can allow discrete speed regulation of a motor with several fixed speeds. Those skilled in the art will understand that the features described herein can be applied to other methods and types of air compressor equipment / applications.

[0049] It is intended that this disclosure should not be limited to the disclosed embodiments described above, and can be extended to other applications that may employ the features described herein.

Claims

1. An air compressor (101), the air compressor comprising: The housing (119) includes a pressure vessel (121) and an electrical enclosure (123). At least one air compression assembly (122) is located within the housing (119) and configured to compress air in the pressure vessel (121); A frequency converter (165) is located in the electrical box (123) and connected to the at least one air compression assembly (122). The frequency converter (165) is configured to operate the at least one air compression assembly (122) to compress air into the pressure vessel (121) in at least three phases: a loading phase, an unloading phase, and a stopping phase. in: During the loading phase, the inverter drive motor (120) drives the at least one air compression assembly (122) to compress air into the pressure vessel (121) to a first pressure level, the pressure vessel (121) having an outlet port (125) from which the compressed air is selectively discharged; During the unloading phase, the compressed air in the pressure vessel (121) is internally recirculated and / or discharged to reduce the air pressure in the pressure vessel (121) to a second pressure level close to atmospheric pressure, which is lower than the first pressure level, and power consumption operates at a reduced rate. During the shutdown phase, the at least one air compression assembly (122) is stopped and the pressure within the pressure vessel (121) is maintained; and During the subsequent loading phase, the inverter (165) starts up without causing a surge in draw current.

2. The air compressor (101) according to claim 1, further comprising an inlet valve and a minimum pressure valve (MPV), wherein, Because the external pressure is higher than the pressure inside the pressure vessel (121), the minimum pressure valve is closed during the unloading phase, and the inlet valve is closed during the stop phase.

3. The air compressor (101) according to claim 1, wherein, During the stop phase, the air pressure in the pressure vessel (121) is maintained at a reduced non-zero level slightly below the first pressure level.

4. The air compressor (101) according to claim 1, wherein, During the stop phase, after a predetermined time has elapsed or after a predetermined condition has been met, the pressure inside the pressure vessel (121) is released, the predetermined condition depending on the degree of condensation, humidity or air pressure.

5. The air compressor (101) according to claim 1, wherein, During the unloading and shutdown phases, the pressure inside the pressure vessel (121) is approximately 10% to 25% of the maximum pressure level of the compressor (101).

6. The air compressor (101) according to claim 2, wherein, One or more of the inlet valve and the minimum pressure valve are passive valves.

7. The air compressor (101) according to claim 1, wherein, The at least one air compression assembly (122) is located at least partially within the pressure vessel (121).

8. A method for operating an air compressor (101) having an internal frequency converter (165) that supplies power to an air compression assembly (122), the method comprising: The pressure vessel (121) of the air compressor (101) is loaded with compressed air from the air compression assembly (122) and its pressure is increased to a first pressure level; The compressed air is discharged from the pressure vessel (121); Compressed air from the pressure vessel (121) is unloaded, wherein unloading includes sealing the pressure vessel (121) to maintain the air pressure inside the pressure vessel (121), and recirculating and / or venting the air inside the pressure vessel (121) to reduce the air pressure inside the pressure vessel (121) to a second pressure level close to atmospheric pressure, the second pressure level being lower than the first pressure level. The air compression assembly (122) is stopped using the internal frequency converter (165), wherein the air pressure in the pressure vessel (121) is maintained at a second pressure level lower than the first pressure level; and The pressure vessel (121) of the air compressor (101) is loaded with compressed air from the air compression assembly (122) by increasing the pressure from the second pressure level to the first pressure level without causing the air pressure to drop below the second air pressure.

9. The method according to claim 8, wherein, The second pressure level is in the range of 25-100% of the first pressure level.

10. The method according to claim 8, wherein, The first pressure level is in the range of 4-13 bar, and the second pressure level is in the range of 1-4 bar.

11. The method according to claim 8, wherein, Sealing the pressure vessel (121) includes passively sealing the pressure vessel (121) using a check valve.

12. The method according to claim 8, wherein, The internal frequency converter (165) is located inside the housing (119) of the air compressor (101).

13. The method according to claim 12, wherein, The internal frequency converter (165) is located in an electrical box (123) of the housing (119) that is separate from the pressure vessel (121).

14. The method according to claim 13, wherein, The internal frequency converter (165) is mechanically connected from the electrical box (123) to the pressure vessel (121) to the air compression assembly (122).

15. The method of claim 8, further comprising discharging the air pressure from the pressure vessel (121) after a predetermined time during which the air compressor (101) has not been started.

16. A multi-mode compressor system (100), comprising: Air compressor (101); Processor (102); A memory (104) configured to store instructions (106) that, when executed by the processor (102), cause the processor (102) to execute a plurality of instructions (106), the instructions (106) including: During the loading phase, an internal frequency converter (165) located within the housing (119) of the air compressor (101) supplies power to the air compression assembly (122), which pressurizes air into a pressure vessel (121) to a first pressure level. An unloading phase is performed, during which the compressor power consumption is reduced by recirculating and / or discharging the compressed air, and the pressure is reduced to a second pressure level below the first pressure level, wherein, during the unloading phase, the pressure vessel (121) is sealed to maintain the pressure inside the pressure vessel (121) at the second pressure level; A stop phase is executed, during which the internal frequency converter (165) stops, and the pressure in the pressure vessel (121) is maintained at the second pressure level; and During the reloading phase, the internal frequency converter (165) supplies power to the air compression assembly (122) to increase the pressure from the second pressure level to the first pressure level, without allowing the pressure in the pressure vessel (121) to dissipate completely.

17. The system according to claim 16, wherein, The pressure vessel (121) includes one or more check valves at the outlet port to maintain pressure in the pressure vessel (121) during the unloading and shutdown phases.

18. The system according to claim 16, wherein, The second pressure level is at least 35% of the first pressure level.

19. The system according to claim 16, wherein, The pressure vessel (121) is configured to release the pressure in the pressure vessel (121) after a predetermined time period during the stop phase.

20. The system according to claim 16, wherein, The pressure vessel (121) is configured to release pressure in the pressure vessel (121) in response to one or more external conditions during the stop phase.

Images