Air compressor and method for providing air compressor to customer

Abstract

An air compressor (101) includes an electric frequency converter (165) that controls a motor (120) coupled to a compression element (122). The frequency converter (165) is located within a housing (119) of the air compressor (101). The frequency converter (165) operates at different speeds. The frequency converter (165) can receive specifications for unloading air pressure characteristics and operates at a speed corresponding to those specifications. There is an inverse relationship between the frequency converter speed and the unloading air pressure setting.

Description

Technical Field

[0001] This disclosure relates to a load / unload controlled air compressor with an internal inverter for controlling the motor, and thus the speed of the compressor's components. Based on the customer's desired pressure, the compressor's parameters can be adjusted to set the operating speed to achieve the desired pressure. Using the same equipment, even with different fixed speeds, the desired pressure can be achieved for a variety of applications and customers. Prior Art

[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 rotors rotate in opposite directions, drawing air in and compressing it as the space between the rotors and the rotor housing decreases. Each screw element has a fixed built-in pressure ratio, which is determined by the screw length, pitch, and discharge port shape. To achieve maximum efficiency, this built-in pressure ratio must be adapted to the required operating pressure. The operating sequence of these compressors is determined by pressure, and different conditions within a plant result in different compressor operating loads, such as no-load, standby, and load settings. A plant's varying compressed air needs can be met using different types of compressors, such as variable speed drive (VSD) compressors or fixed-speed compressors.

[0003] Traditional fixed-speed compressors operate at a fixed speed (revolutions per minute, RPM) over time because the motor relies on the constant frequency provided by the power grid. To adjust air flow, fixed-speed air compressors need to alternate between full-load and no-load conditions. Once the pressure in the air storage tank reaches the unload pressure setting, the compressor unloads and eventually stops. When the compressed air is partially used, the air storage tank pressure drops. When the pressure reaches the load pressure, the motor starts again to drive the compressor. The compressor can also switch back to a loaded state during the unloading process. If the compressed air usage is high, the motor will start and stop frequently, drawing more current during the startup process and consuming more power. The disadvantage of traditional fixed-speed compressors is that even when the air demand is low, the motor continues to run at the same fixed speed, resulting in low energy efficiency and energy waste.

[0004] As air demand increases, a VSD compressor increases motor speed, providing more airflow. If air demand decreases, the motor automatically slows down, using only the energy needed to provide adequate airflow. VSD compressors are particularly useful on days with low production or during breaks in the workflow. Compared to traditional fixed-speed compressors, these compressors save electricity and energy costs. VSD compressors utilize the motor's infinitely variable speed to maintain constant air pressure and adjust airflow demand based on the factory's real-time needs. While VSD compressors are more energy-efficient in most applications, they are not necessary if the demand for compressed air is constant, or even nearly constant, with only occasional minor variations. For example, if the compressed air is supplied to assembly-line machinery that operates 10 to 12 hours per day, investing in a variable-speed compressor will incur additional upfront costs.

[0005] Many compressors are often oversized based on the published FAD (free air delivery) of the compressor unit to prevent undersizing and "future-proof" for additional airflow requirements. As a result, oversizing results in reduced efficiency, larger compressor size, and higher energy consumption. Undersizing the compressor will cause pressure drops and fail to complete the work; however, oversizing the compressor may cause future mechanical problems and even compressor failure. In addition, as production demands increase and compressed air demand increases, the compressor may need to be switched and de-installed, further increasing the cost of the factory. Therefore, there is an urgent need for a compact compressor unit that can meet the factory's compressed air needs, has a lower upfront cost, and uses less energy. Summary of the Invention

[0006] Embodiments of the present disclosure relate to a method for providing an air compressor to a customer, efficiently meeting the customer's needs. The method includes receiving a specified unloading pressure from the customer. The air compressor includes an internal inverter that controls a motor coupled to a component of the air compressor. The method also includes adjusting the speed of the motor and the component based at least in part on a relationship between the motor speed and a desired outlet pressure.

[0007] Other embodiments of the present disclosure relate to an air compressor comprising an inverter. The inverter is located within the air compressor. A customer provides a specified output air pressure target. The component pressurizes air to the target value. The air compressor also includes a processor and a memory storing computer-readable instructions. The computer-readable instructions include receiving the specified output air pressure target, calculating a speed of the inverter based at least in part on a specified maximum output air pressure target, recording the speed, and operating the air compressor at the specified speed.

[0008] Still other embodiments of the present disclosure relate to an air compressor comprising a housing defining a pressure vessel and an electrical box, the electrical box being sealed and separated from the pressure vessel, and comprising an air compression element operably coupled to the pressure vessel and configured to force compressed air into the pressure vessel. The air compressor also comprises an internal inverter within the electrical box and a motor coupled to the air compression element and configured to operate the air compression element over a range of speeds. The air compressor also receives a desired output pressure range for the air compressor from a customer and calculates corresponding settings for the inverter to achieve a maximum outlet pressure within the pressure range. The speed and output pressure are inversely proportional. The air compressor also sets the internal inverter to operate at the corresponding speed and operates the air compressor at the corresponding speed. Simple diagram description

[0009] The features, aspects, and advantages of the disclosed technology can be better understood with reference to the following description, the appended claims, and the accompanying drawings. Those skilled in the relevant art will appreciate that the features shown in the drawings are for illustrative purposes only and are susceptible to various modifications, including different or additional features and their configurations. FIG1 illustrates an embodiment of the present invention in which a compressor system may include or be connected to a sensor (or several sensors); FIG2 is a graph showing the torque and speed of the motor of the air compressor according to an embodiment of the present disclosure; and 3 is a graph showing torque and speed of a motor of an air compressor having multiple speeds according to an embodiment of the present disclosure. These drawings are intended to illustrate exemplary embodiments and are not drawn to scale. It should be understood that the invention is not limited to the arrangements and apparatus shown in the drawings. [definition]

[0010] To facilitate understanding of the methods and system elements disclosed in the embodiments of the present disclosure, some terms must be explained.

[0011] The terms "compressor" or "compressor device" refer to a machine that draws low-pressure gas from an auxiliary storage device as its initial input and then outputs high-pressure gas for storage or supply to other processes. The terms "compressor" and "compressor device" are not intended to be limiting and may refer to positive displacement compressors and / or dynamic compressors (turbocompressors) and / or individual components of compressors.

[0012] The term "computer storage media" refers to physical storage media that store 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 read-only memory (EEPROM), solid-state drives (SSDs), flash memory, phase-change memory (PCM), optical disk memory, magnetic disk memory, and the like.

[0013] The term "controller" or "controller unit" generally refers to a computerized command terminal, including a collection of sensing and electrical components, used to regulate various compressor components. A compressor controller consists of at least one main processing unit with a graphical interface and instrumentation adapted to monitor various compressor components (e.g., motor, rotor, filter, bearings, valves, pressure sensors, temperature sensors).

[0014] 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, cellular phones, personal digital assistants (PDAs), tablet computers, pagers, routers, switches, and the like.

[0015] The term "software" generally refers to computer-executable instructions, program code, data, applications, programs, program modules, or the like in any form or type of removable media that is configured to store computer-executable instructions or other such storage in a manner accessible by a computing device.

[0016] As used herein, reference to any type of machine learning or artificial intelligence may include any type of machine learning algorithm or device, conventional convolutional neural networks, multilayer neural networks, recursive neural networks, recurrent neural networks, deep neural networks, decision tree models (e.g., decision trees, random forests, and gradient boosted trees), linear regression models, logistic regression models, support vector machines (SVMs), artificial intelligence devices, or any other type of intelligent computing system. The machine learning algorithm may be trained using any amount of training data (possibly followed by further optimization) to dynamically perform the actions of the present disclosure.

[0017] When referring to elements in the appended claims, the articles "a," "an," "the," and "said" refer to one or more of the elements. The words "including," "comprising," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements. Implementation Method

[0018] Various embodiments of the present disclosure may be better understood by referring to the following description and accompanying drawings, wherein like reference symbols represent like elements.

[0019] While the present disclosure is susceptible to various modifications and alternative configurations, certain exemplary embodiments have been illustrated in the drawings and described below. The dimensions, angles, and curvatures shown are to be understood as exemplary and not drawn to scale.

[0020] However, it should be understood that the above is not intended to limit the disclosure to the specific embodiments disclosed, but on the contrary, it is intended to cover all modifications, alternative constructions, and equivalents within the spirit and scope of the disclosure.

[0021] According to an embodiment of the present disclosure, and referring to FIG. 1 , an air compressor 101 is provided. The air compressor 101 includes an electric inverter 165 located within an electrical box 123 disposed within the housing 119 of the compressor 101. The inverter can function as a soft starter, a direct-on-line (DOL) starter, or a star-delta (YD) starter. The air compressor 101 is configured with a fixed speed, selecting a speed and operating the compressor 101 at that speed. The required output pressure is inversely proportional to the speed at which the air compressor 101 operates. The higher the required pressure, the lower the speed, and vice versa. The speed of the air compressor 101 can be modified at any time via software or firmware. This allows a single device to be modified without changing any underlying hardware. Within certain limits, a single commercially available compressor can be easily adjusted to meet specific customer requirements. This adjustability also allows for precise alignment with customer needs. The air compressor disclosed herein can precisely meet the required pressure output specification, eliminating the need for multiple compressors with different pressure levels (e.g., discrete levels of 7 bar, 9 bar, and 13 bar). Another advantage is that the air compressor disclosed herein operates efficiently at the required power level at any speed (and associated pressure output specification).

[0022] The air compressor 101 also includes a pressure vessel 121 and an element 122. The air compressor's electrical box 123 can be conveniently positioned relative to the pressure vessel 121 and element 122 and disposed within the housing 119. The inverter 165 provides power and is directly coupled to the element 122 of the air compressor 101, without the use of any gears connecting the power supply to the element 122. This direct coupling allows the air compressor 101 to achieve a wide range of pressures by varying the operating speed of the element 122. In alternative embodiments, the inverter 165 can be coupled to the air compression element 122 via an elastic or flexible coupling, belt, gears, or bearings. Using this system, a single design of the air compressor 101 can be maintained within a certain range, with the operating speed adjusted to achieve a specific pressure within the range. This eliminates the need to maintain air compressors of varying sizes or configurations within the range. Instead, a single, identical air compressor can be sold and appropriately configured based on the required pressure delivery parameters, and by adjusting the speed of the inverter and the components directly coupled in the air compressor, the required pressure can be achieved.

[0023] FIG1 illustrates exemplary components of an exemplary compressor system 100 (e.g., a multi-mode compressor system) that may include or implement one or more embodiments of the present disclosure. For example, FIG1 illustrates that compressor system 100 may include a processor 102, storage 104, sensors 110, an input / output system 114 (I / O system 114), a communication system 116, and / or other components. Although FIG1 illustrates compressor system 100 as including specific components, it is understood that, in accordance with the present disclosure, compressor system 100 may include a varying number of additional or alternative components. Furthermore, although some of these components may be illustrated or described as distinct entities, it is understood that, in accordance with the present disclosure, these distinctions are for purposes of explanation / illustration only. For example, the functionality associated with a particular component herein may be performed by a different component or a combination of the components described herein. Accordingly, aspects of the components described herein may be combined with other components or separated into multiple components in accordance with the present disclosure. Furthermore, the disclosed embodiments may be incorporated into oil-free compressors and various types of multi-stage compressors.

[0024] The processor 102 may include one or more electronic circuits, including any number of logic units, registers, and / or control units, to facilitate the execution of computer-readable instructions (e.g., instructions comprising a computer program). Such computer-readable instructions (e.g., instructions 106) may be stored in a memory 104. The memory 104 may include physical system memory and may be volatile, non-volatile, or some combination thereof. Furthermore, the memory 104 may include local memory, remote memory (e.g., accessible via the communication system 116 or other means), or some combination thereof. Additional details regarding the processor (e.g., processor 102) and computer storage media (e.g., memory 104) are described below.

[0025] In some embodiments, the processor 102 may include or be configured to execute any combination of software and / or hardware components that are executable to facilitate processing utilizing machine learning models or other artificial intelligence-based structures / architectures. For example, the processor 102 may include and / or utilize hardware components or computer-executable instructions that can execute such hardware components or computer-executable instructions to implement functional modules and / or processing layers, such as, but not limited to, single-layer neural networks, feed-forward neural networks, radial basis function networks, deep feed-forward 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 machines, restricted Boltzmann machines, etc. Boltzmann machine), deep belief network, deep convolutional network (or convolutional neural network), deconvolutional neural network, deep convolutional inverse graphics network, generative adversarial network, liquid state machine, extreme learning machine, echo state network, deep residual network, Kohonen network, support vector machine, neural Turing machine and / or other forms.

[0026] As will be described in further detail below, the processor 102 may be configured to execute instructions 106 stored in the memory 104 to perform certain actions associated with the operation of the compressor system 100. The execution of these actions may be based at least in part on data 108 stored in the memory 104 in a volatile or non-volatile manner.

[0027] In some examples, these actions may rely, at least in part, on the communication system 116 to receive data from other components and / or remote systems 118, which may include, for example, standalone systems or computing devices, sensors, etc. The communication system 116 may include any combination of software or hardware components that can be executed to facilitate communication between components / devices within the system and / or components / devices outside the system. For example, the communication system 116 may include ports, buses, or other physical connections for communicating with other devices / components. Additionally or alternatively, the communication system 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 others.

[0028] FIG1 illustrates that a compressor system 100 may include or be connected to a sensor 110 (e.g., to obtain data 108 used to perform the actions described herein). The sensor 110 may include any device for capturing or measuring data representing a perceptible or detectable phenomenon. For example, but not limited to, the sensor 110 may include one or more flow sensors, pressure sensors, humidity sensors, image sensors, microphones, thermometers, barometers, magnetometers, accelerometers, gyroscopes, and / or the like.

[0029] 1 shows that the compressor system 100 may include or be connected to an I / O system 114. The I / O system 114 may include any type of input or output device, such as, but not limited to, a display, a touch screen, a mouse, a keyboard, a controller, a speaker, and / or the like, but the present disclosure is not limited thereto.

[0030] FIG1 also illustrates other exemplary components included in or connected to the compressor system 100. For example, FIG1 illustrates the compressor system 100 as including a compressor device 101 having a compressor motor 120 configured to actuate a compressor element 122 to cause gas compression (e.g., compression of ambient air). The compressor motor 120 can take any suitable form, such as a three-phase induction motor. Similarly, the compressor element 122 can take any suitable form, such as any type of dynamic compressor (e.g., an ejector, centrifugal, or axial compressor) or a 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 piston compressor.

[0031] FIG1 also illustrates various other components that may operate in conjunction with the compressor motor 120 and the compressor element 122 to enhance gas compression. FIG1 illustrates the compressor system including an inlet filter 124, a warning valve 126, an air / oil reservoir 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 drain 148, a dryer 150 (in embodiments without the dryer 150, the electronic drain 148 may be mounted on the aftercooler 142), and an anti-condensation loop 152. As noted above, the compressor system 100 may omit one or more of the components illustrated in FIG1 or utilize alternative components / configurations, consistent with the scope of the present disclosure.

[0032] FIG1 also illustrates that the compressor system 100 includes a frequency converter 160, which is configured to be connected to a power source 162 and to the compressor motor 120 (as shown in FIG1 by dashed lines extending from the power source 162 to the frequency converter 160 and from the frequency converter 160 to the compressor motor 120). As described above, the frequency converter 160 controls the operating speed of the compressor motor 120 by controlling the frequency and voltage of the compressor motor 120. The frequency converter 160 may include a rotary frequency converter, a solid-state frequency converter, or the like. The power source 162 may include a grid-connected power source or an off-grid power source.

[0033] FIG1 illustrates that the operation of the frequency converter 160 (and / or the compressor motor 120) may utilize a multi-mode drive controller 164 (shown in dashed lines in FIG1 , extending from the multi-mode drive controller 164 to the frequency converter 160 and to the compressor motor 120). The multi-mode drive controller 164 may include or operate in conjunction with the processor 102 to control the operation of the frequency converter 160 and / or the compressor motor 120.

[0034] According to a first embodiment, the multi-mode controller 164 is configured to operate the frequency converter 160 and / or the compressor motor 120 according to a plurality of operating modes, including at least a first compression mode 166 and a second compression mode 168 (illustrated by solid lines in FIG. 1 , extending from the multi-mode drive controller 164 to the first compression mode 166 and to the second compression mode 168). The first compression mode 166 and the second compression mode 168 are associated with different motor operating speed profiles. For example, the first compression mode 166 may include a load / unload compression mode, while the second compression mode 168 may include a variable speed drive (VSD) mode. As described above, the load / unload compression modes may be associated with a plurality of states, such as a loaded state (providing compressed air / gas), an unloaded state (e.g., an idle state), or a stopped state (e.g., such a state may be implemented after an idle period). During the loaded state (and typically the unloaded state), the compressor motor 120 operates at a substantially constant operating motor speed. This can be achieved, for example, 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 the loaded / unloaded compression mode, or by bypassing one or more aspects of the frequency converter 160 via the multi-mode drive controller 164 so that a constant frequency and voltage are supplied to the compressor motor 120 from the power supply 162 and / or one or more intervening components.

[0035] As described above, the VSD mode is associated with variable motor operating speed of the compressor motor 120, which can be achieved by having the frequency converter 160 dynamically modify the frequency and voltage used to operate the compressor motor 120 via the multi-mode drive controller 164. The motor speed for the compressor motor 120 (and / or the associated voltage / frequency) can be dynamically determined based on requirements associated with the use of the compressor system, such as the required flow rate of the compressed air, the current compressed air pressure of the compressor system 100, etc.

[0036] According to other embodiments, the multi-mode controller 164 is configured to operate one or more other control components of the compressor system 100 according to a plurality of 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 mechanisms.

[0037] FIG2 is a graph 200 showing torque and speed of a motor for an air compressor according to an embodiment of the present disclosure. The air compressor includes a power source, such as a motor, which may be an electric motor, a combustion engine, or other suitable power source. Curve 202 illustrates the constant torque motor characteristic for this type of air compressor. With this design, each air compressor must be individually manufactured to achieve the desired pressure output, resulting in high logistical costs associated with manufacturing and maintaining multiple different inventory items.

[0038] The air compressor disclosed herein can achieve the desired pressure output using the same device that adjusts for the speed of the component. The pressure vessel, which contains the pressure vessel and power inverter, is directly coupled to the component to drive it. There are no gears between the power supply and the component. This configuration allows for customization of the air compressor's output, a feat not possible with other air compressors. The customer specifies the desired pressure output, and the air compressor's speed is adjusted to the corresponding value. The speed is set in the air compressor, ensuring that the air compressor meets the customer's specifications. This eliminates the expense and management burden of maintaining multiple air compressors with varying outputs and selecting the correct pressure level. Instead, the component's speed is fixed at the appropriate speed, and the air compressor meets the customer's needs.

[0039] Curve 204 represents the desired unloading pressure selected by the customer, and line 206 represents the speed corresponding to the desired unloading pressure. The torque is proportional to the outlet pressure. The speed of the element is inversely proportional to the desired output pressure. That is, a higher output pressure is achieved with a lower speed, while a lower output pressure is achieved with a higher speed.

[0040] As seen in Figure 3, some embodiments of the air compressor have different fixed speeds. Figure 3 is a graph 300 of torque and speed for a motor of an air compressor with three fixed speeds, according to an embodiment of the present disclosure. For illustrative purposes, an air compressor with three speeds or three fixed speed levels is illustrated: low speed 302, reference speed 304, and maximum or high speed 306. The motor speed is based on a customer-specified desired outlet pressure 308. When outlet pressure 308 drops below the compressor's load pressure limit, the control system switches the compressor from an unloaded state to a loaded state. In both states, the motor operates at low speed 302. When outlet pressure 308 begins to increase, the control system determines whether a speed switch to reference speed 304 is necessary. This means that if the pressure increases too slowly and outlet pressure 308 remains below the load pressure limit, the motor speed increases from low speed 302 to reference speed 304. When the outlet pressure 308 begins to rise further and faster, the control system should again determine whether it is necessary to increase the speed further to the maximum speed 306. This means that if the pressure is still rising too slowly and the outlet pressure 308 remains continuously below the load level, the motor speed will increase from the reference speed 304 to the maximum speed 306. If the outlet pressure 308 increases and eventually exceeds the unload pressure limit, the control system should switch the compressor to the unloaded state. This means that the compressor motor will once again enter the low speed 302 while the compressor circulates air within itself. It should be noted that the air compressor may have two or more speeds, meaning that the present disclosure is not limited to three speeds.

[0041] It should be understood that not all objects or advantages are necessarily achieved by any embodiment of the present disclosure. Those skilled in the art will appreciate that the compressor device claimed in the present disclosure can be embodied or implemented in a manner that achieves or optimizes one advantage or group of advantages as taught in the present disclosure, without necessarily achieving other objects or advantages as taught or suggested in the present disclosure.

[0042] Those skilled in the art will appreciate the interchangeability of the various features disclosed herein. In addition to the variations described herein, those skilled in the art can mix and match features with other known equivalents to construct and use a compressor device in accordance with the principles of this disclosure. For example, the inverter of a fixed-speed compressor disclosed herein can allow for discrete speed adjustment of the motor at several fixed speeds. Those skilled in the art will appreciate that the features described herein are applicable to other methods and types of air compressor devices / applications.

[0043] The present disclosure should not be limited to the embodiments described above, but may extend to other applications using the features described herein.

[0044] 100:Compressor system 101: Compressor device 102: Processor 104: Storage 106: Instructions 108: Information 110:Sensor 114:I / O system 116: Communication System 118: Remote System 119: Shell 120: Motor 121: Pressure Vessel 122: Compressor components 123:Electrical box 124: Inlet filter 126: Warning valve 128: Gas / Oil Container Separator 130: Thermostatic bypass valve 132: Oil filter 134: Safety valve 136: Oil separator 138: Minimum pressure valve 140: Solenoid valve 142: Aftercooler 144: Fan 146:Oil cooler 148: Electronic emission device 150:Dryer 152: Anti-condensation cycle 160:Frequency Converter 162: Power Supply 164:Multi-mode drive controller 165:Inverter 166: First compression mode 168: Second compression mode 200,300: Curve Graph 202,204: Curve 206: Lines 302: Low speed 304: Reference speed 306: Maximum speed / high speed 308: outlet pressure

Claims

1. A method for supplying an air compressor to a customer, comprising: The customer receives a specified unloading pressure; in an air compressor (101) having an internal frequency converter (165) of a motor (120) of an element (122) coupled to the air compressor (101), the speeds of the motor (120) and the element (122) are adjusted, at least in part, based on the relationship between the motor speed and the specified unloading pressure; and the air compressor (101) is provided to the customer, with the speed of the air compressor (101) set at a level that meets a specification requirement, wherein the internal frequency converter (165) provides power and is directly coupled to the element (122) of the air compressor (101), without using any gears to connect the power supply to the element (122).

2. The method of request item 1 further includes checking whether the specification is within the known range of effective operation of the frequency converter (165).

3. The method of claim 1, wherein the frequency converter (165) operates at maximum power at the speed and unloading pressure.

4. The method of request item 1 further includes receiving updated specifications from the customer and adjusting the speed of the internal frequency converter (165) accordingly.

5. The method of claim 1, wherein the speed of the motor (120) is controlled at three fixed levels, the three fixed levels being a low speed, a high speed, and a reference speed defined as being between the low speed and the high speed.

6. As in request item 5, wherein, In response to the updated specifications received from the customer, the reference speed is based on the specified unloading pressure and the maximum power of the inverter (165), and is increased to that high speed.

7. An air compressor (101), comprising: A frequency converter (165) controls a motor (120) coupled to a component (122) in the air compressor. The frequency converter (165) is located within the air compressor (101), and the component (122) is configured to pressurize air. The internal frequency converter (165) provides power and is directly coupled to the component (122) of the air compressor (101) without using any gears to connect the power supply to the component (122). A processor (102) is also included. A memory (104) stores computer-readable instructions (106) that, when executed, cause the processor (102) to: receive a specified output air pressure target; calculate the speed of the frequency converter (165) based at least in part on the specified maximum output air pressure target; record the speed; and operate the air compressor (101) at a fixed and recorded speed.

8. The air compressor (101) of claim 7, wherein the processor (102) is further configured to measure the output air pressure and compare the output air pressure with the target.

9. An air compressor (101), comprising: A housing (119) defines a pressure vessel (121) and an electrical enclosure (123) which is sealed and separated from the pressure vessel (121); at least one air compression element (122) is operatively coupled to the pressure vessel (121) and configured to force compressed air into the pressure vessel (121); an internal frequency converter (165) located in the electrical enclosure (123) controls one of the motors (120) coupled to the at least one air compression element (122) and is configured to operate the at least one air compression element (122) within a speed range, wherein the internal frequency converter (165) provides power and is directly coupled to the element (122) of the air compressor (101) without using any gears to connect the power supply to the element (122); The processor (102) and the memory (104) are configured to store instructions (106) that, when executed, cause the processor (102) to perform a plurality of actions, including: receiving from the customer the required outlet pressure range of the air compressor; calculating the corresponding settings for the frequency converter (165) to achieve the required outlet pressure range, wherein speed and output pressure are inversely proportional; setting the internal frequency converter (165) to operate at the corresponding speed; and operating the air compressor (101) at the corresponding speed.

10. The air compressor (101) of request item 9 further includes receiving the updated required speed, calculating the updated corresponding speed, and setting the inverter (165) to operate at the updated corresponding speed.

11. The air compressor (101) of claim 9, wherein the internal frequency converter (165) operates at maximum power over substantially the entire speed range at the corresponding unloading pressure.

12. The air compressor (101) of claim 9, wherein the speed range includes a fixed low speed, a fixed reference speed and a fixed maximum speed.

13. The air compressor of claim 12, wherein the fixed low speed is increased to the fixed reference speed based on the outlet pressure range required by the processor (102) from the customer receiving the air compressor (101).

14. The air compressor of claim 12, wherein the fixed reference speed is increased to the fixed maximum speed in response to the range of outlet pressure required by the processor (102) from the customer receiving the air compressor (101).

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