Air compressor with delayed maximum flow

Abstract

A constant speed air compressor arrangement (101) has a controller unit (164) for controlling the speed of a motor (120) for driving a compressor (101). The controller unit (164) includes a frequency converter (165) to initiate discrete speed regulation of the air compressor (101) in order to produce additional flow and provide higher output pressure. Based on the discrete speed regulation, the air compressor (101) operates at an increased speed when required for compressor application.

Description

Technical Field

[0001] This disclosure relates to an air compressor with an internal frequency converter that allows for a maximum flow delay. Background Technology

[0002] A rotary screw air compressor is a positive displacement type of gas compressor that uses two rotors to generate the pressure required for air compression. These two rotors rotate in opposite directions to draw in compressed air as the space between the rotors and their housings decreases. Each screw element has a fixed built-in pressure ratio, which depends on the screw length and pitch, as well as the shape of the discharge port. For maximum efficiency, this built-in pressure ratio must be adapted to the required operating pressure. The operating sequence of these compressors is determined by the pressure value; different conditions occurring in a plant result in different compressor operating loads, such as no load, standby, ready to run, and load setting. Different compressed air requirements in a plant can be met using different types of compressors, such as variable speed drive compressors or fixed speed drive compressors.

[0003] Traditional fixed-speed compressors operate at a constant number of revolutions per minute (RPM) and supply a consistent output to the motor. To adjust the airflow, the intake valve needs to be adjusted to allow more or less air to be discharged. Once the pressure in the air tank reaches the set value, the motor stops. And as compressed air is partially used, the pressure in the air tank drops. When the pressure reaches the set value again, the motor restarts to drive the air compressor. If a large amount of compressed air is used, the motor will start and stop frequently, and the motor will consume more electrical energy during the start-up process while drawing a higher current. Once the motor stops, its energy cannot be used; therefore, the energy consumed due to the frequent start-stop of the motor increases. The disadvantage of traditional fixed-speed compressors is that the motor always runs at the same fixed speed, even when gas demand is low. Therefore, this results in a less energy-efficient process and wastes energy.

[0004] VSD compressors increase motor speed as air demand increases, thus providing more airflow. If air demand decreases, the motor automatically slows down, using only the energy needed to provide the appropriate airflow. VSD compressors are particularly useful during slow production days or workflow interruptions. Compared to traditional fixed-speed compressors, this type saves on electricity and energy costs. VSD compressors utilize the continuously variable speed characteristic of the motor to stabilize air pressure and thus meet airflow demands based on the plant's real-time requirements. While VSD compressors are more energy efficient for most applications, they are not necessary if compressed air demand is constant, or even nearly constant with only occasional slight variations. For example, if the compressed air application involves running assembly line machinery for 10 to 12 hours per day, investing in a variable-speed compressor would require additional upfront costs. Furthermore, if the size of the VSD compressor is correctly determined based on the unit's published maximum free air delivery (FAD), the VSD compressor may increase maintenance costs by running for more hours than required due to lack of shutdown.

[0005] Many compressors are typically oversized based on the published FAD (Flat Design Aspect) of the compressor unit to prevent undersized designs and accommodate additional forward-looking airflow requirements. Therefore, the oversized design leads to lower efficiency, larger compressors, and higher energy consumption. Undersized compressors will result in pressure drops and inability to perform tasks; however, oversized units may lead to future mechanical problems and potential compressor failures. Furthermore, as production demands increase and compressed air requirements rise, compressor switching and unloading may be necessary. This, in turn, increases costs imposed on the plant. Therefore, there is a need for a compact compressor unit that meets the plant's compressed air requirements with lower upfront costs and lower energy consumption. Summary of the Invention

[0006] Embodiments of this disclosure relate to an air compressor comprising a housing containing a pressure vessel, a controller unit, and an air compression element located within the housing and configured to compress air in the pressure vessel. The air compressor has a frequency converter in an electrical cabinet and is directly coupled to a motor of the air compression element, and the frequency converter operates the air compression element to compress air into the pressure vessel in at least three phases: load, unload, and stop. During the load phase, the frequency converter causes the air compression element to compress air into the pressure vessel, which has an outlet port from which the compressed air is selectively discharged. During the unload phase, the compressed air in the pressure vessel is held, the air compression element operates at a reduced rate, and during the stop phase, the air compression element stops and the pressure within the pressure vessel is maintained. The disclosed compressor device overcomes the disadvantages of existing compressors by including a frequency converter that initiates discrete speed regulation of the motor to achieve air pressure stability. The frequency converter ensures that the motor operates at a reference speed before increasing to a maximum speed or RPM.

[0007] According to embodiments of this disclosure, a fixed-speed air compressor is provided, having a controller unit, such as an electrical cabinet, for controlling the speed of a motor used to drive an air compression element of the compressor. The motor is connected to the air compression element, such as one or more rotating elements, and generates airflow. The controller unit includes a frequency converter for adjusting the frequency and voltage of electrical signals sent to the motor, which in turn controls the speed and torque output of the motor. The motor is configured to receive electrical signals from the frequency converter to control its operating speed, and the frequency converter is configured to induce discrete speed regulation of the motor's operating speed. In one embodiment, the frequency converter provides power and is directly coupled to the air compression element without including any gears connecting the power supply to the air compression element. This direct coupling allows the air compressor to achieve a wide range of pressures by discretely changing the speed at which the motor operates. In an alternative embodiment, the frequency converter may be coupled to the air compression element via a resilient or flexible coupling, belt, gear, or bearing. The frequency converter ensures that the motor operates at one or more discrete reference speeds and discrete maximum speeds. Prior art designs for fixed-speed air compressors do not include frequency converters. Therefore, motors designed in the prior art can only operate at a fixed maximum speed. The discrete speed regulation of the air compressor disclosed herein utilizes the compressor to generate additional flow, resulting in higher output pressure.

[0008] In one embodiment, a compressor device is provided, comprising a controller unit for controlling the speed of a motor driving the compressor, wherein the controller unit includes a frequency converter. The controller unit includes a processing unit provided with an algorithm for calculating at least one reference operating speed of the motor. The algorithm can also calculate a maximum operating speed of the motor. In one embodiment, the operating speed is discretely defined by a first fixed speed and a second fixed speed. The operating speed can be increased by a predetermined percentage from the reference operating speed to the maximum operating speed. Similarly, the operating speed can be decreased by a predetermined percentage from the maximum operating speed to the reference operating speed.

[0009] In one embodiment, a constant-speed compressor device is provided, comprising a processing unit and a computer storage medium storing computer-executable instructions executable by the processing unit. Embodiments of this disclosure may include or utilize computer hardware, such as a processor system (e.g., the processing unit) and system memory. The computer-readable medium storing the computer-executable instructions and / or data structures is a computer storage medium (e.g., storage medium 104). The computer storage medium is a physical storage medium storing computer-executable instructions and / or data structures. The computer-executable instructions executable by the processing unit include instructions for controlling the speed of a motor driving the constant-speed compressor via a power frequency converter and inducing discrete speed regulation of the motor. The computer-executable instructions may also include instructions for calculating at least one reference operating speed of the motor and a maximum operating speed of the motor.

[0010] In one embodiment, a method is provided for controlling the outlet or output pressure of a constant-speed compressor. The method includes providing a controller unit for controlling the speed of a motor, the controller unit for driving the constant-speed compressor, wherein the controller unit includes a frequency converter and discrete speed regulation of the motor speed initiated by utilizing the frequency converter.

[0011] In one embodiment, the discrete speed regulation is defined by at least one reference speed and a maximum speed. The at least one reference speed is operational when the outlet pressure of the constant-speed compressor is below the load setpoint. Furthermore, the maximum speed is operational when the outlet pressure of the constant-speed compressor is between the load setpoint and the unload setpoint. When the constant-speed compressor requires a higher flow rate, the outlet pressure is increased from a steady-state operating level to a higher operating level. Moreover, this higher operating level of the outlet pressure is above the load setpoint and below the unload setpoint. Brief description of the attached figures

[0012] The features, aspects, and advantages of this disclosure will be better understood in conjunction with the following description, the appended claims, and the accompanying drawings. Those skilled in the art will understand that the features shown in the drawings are for illustrative purposes and may be varied, including different or additional features and arrangements.

[0013] Figure 1 Exemplary components of a compressor system according to this disclosure are illustrated;

[0014] Figure 2 This is an output curve of pressure, speed, and flow rate for a reference compressor unit in existing technology;

[0015] Figure 3 This is an example of a compressor unit with discrete speed regulation at two levels, showing the pressure, speed, and flow output curves.

[0016] Figure 4 This is an example of a compressor unit with discrete speed regulation at three levels, showing the pressure, speed, and flow output curves; and

[0017] Figure 5 This is an example of a compressor unit with three levels of discrete speed regulation, showing the output curves of motor speed versus flow demand.

[0018] The accompanying 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 setups and devices shown in the drawings.

[0019] definition

[0020] To facilitate understanding of the disclosed embodiments of the methods and system components, some terms must be described.

[0021] The term "compressor" or "compressor unit" 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 delivery to other processes. The term "compressor" or "compressor unit" is not intended to be limiting, but may refer to positive displacement compressors and / or dynamic compressors (turbo compressors) and / or individual components of a compressor.

[0022] 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.

[0023] The term "controller" or "controller unit" generally refers to a computerized command terminal, which includes a collection of sensors and electrical components used to regulate various compressor elements. A compressor controller includes at least one main processing unit with a graphical interface adapted to monitor instrumentation data from various compressor components (e.g., motors, rotors, filters, bearings, valves, pressure sensors, temperature sensors).

[0024] The term "processor" or "processing unit" refers to one or more devices, circuits, and / or processing chips configured to process data, such as computer program instructions, and includes personal computers, desktop computers, notebook computers, message processors, handheld devices, multifunction processor systems, microprocessor-based or programmable consumer electronics, network personal computers (PCs), minicomputers, mainframes, mobile phones, personal digital assistants (PDAs), tablet computers, pagers, routers, switches, and the like.

[0025] The term "software" generally refers to computer-executable instructions, code, data, applications, programs, program modules, or the like 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.

[0026] As used herein, references to any type of machine learning or artificial intelligence may include any type of machine learning algorithm or device, convolutional neural networks, multilayer neural networks, recurrent neural networks, recurrent neural networks, deep neural networks, decision tree models (e.g., decision trees, random forests, and gradient boosting trees), linear regression models, logistic regression models, support vector machines (SVMs), artificial intelligence devices, or any other type of intelligent computing system. Any amount of training data (and potentially optimized thereafter) may be used to train the machine learning algorithm to dynamically perform the disclosed actions.

[0027] When introducing an element in the appended claims, the articles “a,” “the,” and “the” indicate the presence of one or more elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements besides those listed. Detailed Implementation

[0028] Different embodiments of this disclosure can be better understood by referring to the accompanying drawings, in which similar reference numerals denote similar elements.

[0029] While this disclosure may have various modifications and alternative constructions, certain exemplary embodiments have been illustrated in the accompanying drawings and described below. Dimensions, angles, and curvatures represented should be understood as exemplary and not necessarily shown to scale.

[0030] However, it should be understood that this disclosure is not intended to limit it to the specific embodiments disclosed, but rather is intended to cover all modifications, alternative constructions and equivalents that fall within the spirit and scope of this disclosure.

[0031] According to embodiments of this disclosure, a constant-speed air compressor is provided, having a controller unit, such as an electrical cabinet, for controlling the speed of a motor used to drive the compressor. The controller unit includes a frequency converter for adjusting the frequency and voltage of electrical signals sent to the motor, which in turn controls the speed and torque output of the motor. The motor is configured to receive electrical signals from the frequency converter to control its operating speed, and the frequency converter is configured to trigger discrete speed regulation of the motor's operating speed. The frequency converter ensures that the motor operates at one or more discrete reference speeds and discrete maximum speeds.

[0032] Figure 1 The illustrations depict various exemplary components of an exemplary compressor system 100 (e.g., a multi-mode compressor system or device), which may include or implement one or more embodiments of this disclosure. For example, Figure 1 The compressor system 100 may include a processing unit or processor 102, a memory 104, a sensor 110, an input / output system 114 (I / O system 114), a communication system 116, and / or other components. Although Figure 1 The illustration of compressor system 100 includes specific components; it will be understood that, according to this disclosure, compressor system 100 may include any number of additional or alternative components. Furthermore, while some of the components may be illustrated or described as different entities, it will be understood that such distinctions are for illustrative purposes only. For example, the function associated with a particular component herein may be performed by different components or combinations of components described herein. Therefore, aspects of the components described herein may be combined with other components or divided into multiple components according to this disclosure. Moreover, aspects of this disclosure can be incorporated into oil-free compressors and various types of multistage compressors.

[0033] The processor 102 may include one or more sets of electronic circuitry, which include any number of logic units, registers, and / or control units to facilitate the execution of computer-readable instructions (e.g., instructions constituting a computer program). Such computer-readable instructions (e.g., instruction 106) may be stored in memory 104. Memory 104 may include physical system memory and may be volatile, non-volatile, or a combination thereof. Further, memory 104 may include local memory, remote memory (e.g., accessible via communication system 116 or other means), or a combination thereof. Further details regarding the processor (e.g., processor 102) and computer storage media (e.g., memory 104) will be provided below.

[0034] In some embodiments, processor 102 may include or be configured to execute any combination of software and / or hardware components that may operate to facilitate processing using machine learning models or other artificial intelligence-based architectures. For example, processor 102 may include and / or utilize hardware components or computer-executable instructions that can operate to implement functional modules and / or processing layers, which are configured as non-limiting examples in the form of: 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.

[0035] As will be described in more detail below, the processor 102 may be configured to execute instructions 106 stored in memory 104 to perform certain actions associated with the operation of the 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.

[0036] In some examples, the operation 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, separate systems or computing devices, sensors, and / or others. The communication system 116 may include any combination of software or hardware components that can operate to facilitate communication between components / devices on the system and / or external components / devices. For example, the communication system 116 may include ports, buses, or other physical connection devices for communicating with other devices / components. Furthermore, 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, WLAN, infrared communication, and / or others.

[0037] Figure 1 The illustrated compressor system 100 may include sensors 110 or communicate with said sensors (e.g., to obtain data 108 for performing the actions described herein). Sensor 110 may include any means for capturing or measuring data representing a perceptible or detectable phenomenon. As a non-limiting example, said sensor 110 may include one or more flow sensors, pressure sensors, hygrometers, image sensors, microphones, thermometers, barometers, magnetometers, accelerometers, gyroscopes, and / or others.

[0038] Furthermore, Figure 1 The compressor system 100 may include or communicate with an I / O system 114. The I / O system 114 may include any type of input or output device, such as, by way of non-limiting example, a display, touch screen, mouse, keyboard, controller unit, speaker, and / or others, but is not limited thereto.

[0039] Figure 1 Other exemplary components of the compressor system 100 or other exemplary components communicating with the compressor system 100 are also illustrated. For example, Figure 1The compressor system 100 illustrated includes a compressor unit 101 having a compressor motor 120 configured to actuate a compressor element 122 to facilitate gas compression (e.g., compression of ambient air). The compressor unit 101 is a constant-speed compressor. 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., 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.

[0040] Figure 1 Various additional components that can operate together with the compressor motor 120 and the compressor element 122 to facilitate gas compression are also illustrated. Figure 1 The illustrated compressor system includes an inlet filter 124, a sentry valve 126, a gas / 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 148 may be installed on the aftercooler 142), and a condensing cycle 152. As described above, the compressor system 100 may be omitted. Figure 1 One or more of the components shown, or alternative components / structures that may be utilized within the scope of this disclosure.

[0041] Figure 1 The compressor system 100 is also illustrated, including a frequency converter 160 configured to be connected to a power supply 162 and to the compressor motor 120 (e.g., Figure 1 (As shown by the dashed line 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 motor 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, etc. The power source 162 may include a grid-connected power source or an off-grid power source.

[0042] Figure 1 The operation of the frequency converter 160 (and / or the compressor unit 101) can be described by a controller unit or a multi-mode drive controller 164 (such as...). Figure 1(Dashed lines extending from the multi-mode drive controller 164 to the frequency converter 160 and then to the compressor motor 120 are shown in the diagram). The compressor 101 includes an internal frequency converter 165 for adjusting the frequency and voltage of electrical signals sent to the motor 120, which in turn controls the speed and torque output of the motor 120. The multi-mode drive controller 164 may include a processor 102 or operate in conjunction with the processor to manage the operation of the frequency converter 160 and / or the compressor motor 120. The processor 102 preferably provides an algorithm to calculate at least one reference operating speed 120 of the motor. In one embodiment, the multi-mode drive controller 164 includes a processor 102 or operates in conjunction with the processor 102 to adjust the frequency and voltage of electrical signals sent to the motor 120, which in turn controls the speed and torque output of the motor 120.

[0043] 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 (Shown by 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 motor operating speed configurations. For example, the first compression mode 166 may include a load / unload compression mode, and the second compression mode 168 may include a VSD mode. As described 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., idle), or a stop state (e.g., the stop state may be implemented after a period of idleness). During the load state (and often the unload state), the compressor motor 120 operates at a substantially constant motor operating 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 so that it operates under load in a load / unload 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 intermediate components.

[0044] According to other embodiments, the multi-mode controller is configured to operate one or more of other control components of the compressor system 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 solenoid valves, one or more control timers, and / or one or more pressure vessel controls.

[0045] Figure 2 The graph 200 is a curve representing the output of pressure in a pressure vessel, motor speed, and compressed air flow demand according to existing technology, where each output is plotted as a function of time. The graph 200 plots the output parameters of a prior art reference unit with a maximum flow rate driven at a fixed speed without delay. The motor's first reference speed 206, or reference RPM, is equal to the compressor unit's maximum speed or maximum RPM. The reference unit in graph 200 does not include a frequency converter. Therefore, over time, the motor operates at a fixed maximum speed (which is reference speed 206) without increasing or decreasing in response to flow demand 201. The graph 200 begins when the reference unit is started or turned on. The output pressure increases toward the load setpoint 212 and the unload setpoint 214 to an initial pressure level 210 and remains below the load setpoint 212 at a steady-state operating level 208. As the output pressure increases to the initial pressure level 210, the flow demand 201 simultaneously increases to an initial flow level 204. However, as explained above, the motor of the reference unit in graph 200 will continuously operate at a reference speed 206 equal to the maximum speed, even when it is not required in the factory application. Prior art designs of constant-speed air compressors do not include a frequency converter. Therefore, motors in prior art designs can only operate at a fixed maximum speed. The discrete speed regulation of the air compressor disclosed herein generates additional flow from the compressor, resulting in higher output pressure.

[0046] Figure 3Graph 300 is a curve representing the output of pressure in a pressure vessel, motor speed, and compressed air flow rate demand, where each output is plotted as a function of time. Graph 300 plots the output parameters of one embodiment of a compressor unit 101, which has a fixed-speed drive and a delayed maximum flow rate. The compressor unit 101 in Graph 300 includes a frequency converter 165 configured to induce discrete speed regulation of the motor's operating speed. The discrete speed regulation depicted in Graph 300 plots a first fixed speed 306 and a second fixed speed 313. In one embodiment, the first fixed speed 306 is a reference speed, and the second fixed speed 313 is a maximum speed, wherein the first fixed speed 306 is less than the second fixed speed 313. Graph 300 begins when the compressor unit 101 is started or turned on. Once the compressor unit 101 is started, the motor of the compressor unit 101 operates at the first fixed speed 306. When the motor operates at the first fixed speed 306, the output pressure increases to the initial pressure level 310 and the flow demand 301 increases to the initial flow level 304. The output pressure increases toward the load setpoint 312 and the unload setpoint 314 to the initial pressure level 310 and remains below the load setpoint 312 at the steady-state operating level 308 until the flow demand 301 increases from the first level 305 to the second level 307 and transitions to a higher flow demand 302.

[0047] Once the compressor unit 101 requires a higher flow rate 302, the output pressure increases from a stable operating level 308 at a lower pressure level 315 to a higher operating level 319 at a higher pressure level 317. As described, the higher pressure level 317 is higher than the load setpoint 312 and lower than the unload setpoint 314. Additionally, once the compressor unit 101 requires the higher flow rate 302, the first fixed speed 306 increases from a first discrete level 309 to a second discrete level 311, and the motor subsequently operates at the second fixed speed 313.

[0048] After the constant-speed compressor unit 101 in graph 300 has been under load for a period of time (between the initial pressure level 310 and the lower pressure level 315, but before reaching the load setpoint 312), the motor speed increases from the first discrete level 309 to the second discrete level 311 by a predetermined percentage. This causes the compressor unit 101 to generate additional flow, resulting in a higher output pressure at a higher operating level 319. Therefore, the compressor unit 101 operates only at the second fixed speed 313 at maximum speed when required for factory applications.

[0049] Figure 4 The graph 400 is a curve showing the output of the pressure in the pressure vessel, the speed of the motor, and the flow rate demand of compressed air, with each output plotted as a function of time. The graph 400 plots the output parameters of one embodiment of the compressor unit 101, which has a fixed-speed drive and a delayed maximum flow rate. The compressor unit 101 of the graph 400 includes a frequency converter 165 configured to induce discrete speed regulation of the motor's operating speed. The discrete speed regulation depicted in the graph 400 illustrates a first fixed speed 406, a second fixed speed 413, and a third fixed speed 426. The graph 400 begins when the compressor unit 101 is started or turned on. Once the compressor unit 101 is started, the motor of the compressor unit 101 operates at the first fixed speed 406. When the motor is operating at the first fixed speed 406, the output pressure increases to an initial pressure level 410 and the flow rate demand 401 reaches an initial flow rate level 404. The output pressure increases toward the load setpoint 435, intermediate setpoint 436 and unload setpoint 437 to the initial pressure level 410 and remains below the load setpoint 435 at the steady state operating level 408 until the flow demand 401 increases from the first level 405 to the second level 407 and becomes the intermediate flow demand 402.

[0050] Once the compressor unit 101 requires an intermediate flow demand 402, the output pressure increases from a stable operating level 408 at a lower pressure level 415 to an intermediate operating level 419 at an intermediate pressure level 417. As previously mentioned, the intermediate pressure level 417 is higher than the load setpoint 435 and lower than the intermediate setpoint 436. Additionally, once the compressor unit 101 requires the intermediate flow demand 402, the first fixed speed 406 increases from a first discrete level 409 to a second discrete level 411, and the motor subsequently operates at the second fixed speed 413.

[0051] After the constant-speed compressor unit 101 in graph 400 has been under load for a period of time (between the initial pressure level 410 and the lower pressure level 415, but before reaching the load setpoint 435), the motor speed increases from the first discrete level 409 to the second discrete level 411 by a predetermined percentage. This causes the compressor unit 101 to generate additional flow, resulting in a higher output pressure at the intermediate operating level 419. Therefore, the compressor unit 101 operates only at the second fixed speed 413 under intermediate speed conditions when required for factory applications.

[0052] When the motor operates at the second fixed speed 413, the output pressure is maintained between the load setpoint 435 and the intermediate setpoint 436. When the intermediate flow demand 402 increases from the second level 421 to the third level 422 and then transitions to a higher flow demand 403, the output pressure increases toward the intermediate setpoint 436 and the unloading setpoint 437.

[0053] Once the compressor unit 101 requires the higher flow rate demand 403, the output pressure increases from the intermediate operating level 419 (at the intermediate pressure level 430) to the higher operating level 431 (at the higher pressure level 432). As described, the higher pressure level 432 is higher than the intermediate setpoint 436 and lower than the unloading setpoint 437. Additionally, once the compressor unit 101 requires the higher flow rate demand 403, the second fixed speed 413 increases from the second discrete level 425 to the third discrete level 427, and the motor subsequently operates at the third fixed speed 426.

[0054] After the constant-speed compressor unit 101 in graph 400 has been under load for a period of time (between intermediate pressure levels 417 and 430, but before reaching the intermediate setpoint 436), the motor speed increases from the second discrete level 425 to the third discrete level 427 by a predetermined percentage. This causes the compressor unit 101 to generate additional flow, resulting in a higher output pressure at a higher operating level 431. Therefore, the compressor unit 101 operates at the third fixed speed 426 at higher speeds only when required for factory applications.

[0055] When the motor operates at the third fixed speed 426, the output pressure is maintained between the intermediate setpoint 436 and the unloading setpoint 437. When the higher flow demand 403 decreases from the third level 423 to the second level 424 and then to the intermediate flow demand 402, the output pressure decreases toward the load setpoint 435 and the intermediate setpoint 436.

[0056] Once the compressor unit 101 no longer requires a higher flow rate 403, the output pressure decreases from a higher operating level 431 (higher pressure level 433) to an intermediate operating level 419 (intermediate pressure level 434). Additionally, once the compressor unit 101 no longer requires a higher flow rate 403, the third fixed speed 426 decreases from a third discrete level 428 to a second discrete level 429, and the motor subsequently operates at the second fixed speed 413. Therefore, the compressor unit 101 operates only at the third fixed speed 426 at higher speeds when required for factory applications. This saves energy and costs associated with continuously operating the constant-speed compressor at a single, fixed maximum speed during operation.

[0057] In one embodiment, the motor has three control speeds (low speed or a first fixed speed level 406, a reference speed or a second fixed speed level 41, and a maximum speed or a third fixed speed level 426), which can be selected based on output pressure and a pressure setpoint. When the output pressure drops below the motor's load pressure limit or load setpoint 435, the control system can switch the motor from the unloaded state to the loaded state, wherein in both states, the motor operates at low speed 406. When the output pressure begins to rise, the control system can assess whether a switch to the reference speed 413 is necessary. This means that if the pressure rises too slowly and the output pressure will remain below the intermediate load pressure limit or intermediate setpoint 436, the motor speed will increase from low speed 406 to reference speed 413. When the output pressure begins to rise further and faster, the control system should reassess whether there is an additional need to switch to the maximum speed 426. This means that if the pressure rises too slowly and the output pressure remains below the maximum load pressure limit or unloading setpoint 437, the motor speed will increase from the reference speed 413 to the maximum speed 426. If the output pressure increases and eventually exceeds the unloading setpoint 437, the control system should switch the compressor to the unloading state. This means the compressor motor will return to a low speed 406, while the compressor recirculates air within the unit.

[0058] Figure 5 This is a graph 500 showing the output of motor speed 502 versus flow demand 510 in one embodiment of a compressor unit 101 with three levels of discrete speed regulation, each output being plotted as a function of time. Motor speed 502 is defined by a first fixed speed level 504, a second fixed speed level 506, and a third fixed speed level 508. The graph 500 illustrates the output parameters of one embodiment of the compressor unit 101, which has a fixed-speed drive and a delayed maximum flow rate.

[0059] It should be understood that not all objectives or advantages will necessarily be achieved in any embodiment of this disclosure. Those skilled in the art will appreciate that the claimed compressor apparatus may be embodied or implemented in a manner that achieves or optimizes one or more advantages taught in this disclosure without necessarily achieving other objectives or advantages taught or suggested in this disclosure.

[0060] Those skilled in the art will understand the interchangeability of the various features of this disclosure. In addition to the variations described herein, those skilled in the art can mix and match other known equivalents of the features to construct and use compressor devices under the principles of this disclosure. For example, the frequency converter of the constant-speed compressor of this disclosure allows for discrete speed regulation of a motor having several fixed speeds. Those skilled in the art will understand that the features described herein are applicable to other methods and types of air compressor devices / applications.

[0061] It is intended that this disclosure should not be limited to the disclosed embodiments described above, but can be extended to other applications that may employ the features described herein.

Claims

1. A compressor device (101), comprising: A controller unit (164) is used to control the speed of a motor (102) for driving the compressor unit (101), and the controller unit (164) includes a frequency converter (165); The motor (120) is configured to receive an electrical signal from the frequency converter (165), the frequency converter being used to control the operating speed of the motor (120), and the frequency converter (165) being configured to induce discrete speed regulation of the operating speed of the motor (165).

2. The compressor device (101) according to claim 1, wherein the frequency converter (165) adjusts the frequency and voltage of the electrical signal sent to the motor (120).

3. The compressor device (101) according to claim 1, wherein the controller unit (164) includes a processing unit (102) having an algorithm for calculating a reference operating speed (306, 406) of the motor (120).

4. The compressor device (101) according to claim 3, wherein the operating speed is increased by a predetermined percentage from the reference operating speed (306, 406) to the maximum operating speed (313, 426).

5. The compressor device (101) according to claim 4, wherein the operating speed is discretely defined by a first fixed speed (306, 406) and a second fixed speed (313, 426).

6. The compressor device (101) according to claim 5, wherein the operating speed is further discretely defined by a third fixed speed (413).

7. The compressor device (101) according to claim 1, wherein the compressor device (101) is a constant speed driven compressor.

8. A constant-speed compressor device (100), comprising: Processing unit (102); and Computer storage medium (104) storing computer-executable instructions (106) executable by the processing unit (102) to at least: The speed of the motor (120) used to drive the constant-speed compressor (101) is controlled by a power frequency converter (165); and This triggers discrete speed regulation of the motor (120).

9. The constant-speed compressor device (100) according to claim 8, wherein the computer storage medium (104) further stores computer-executable instructions (106) that can be executed by the processing unit (102) to calculate at least one reference operating speed (306, 406, 413) of the motor (102) and the maximum operating speed (313, 426) of the motor (120).

10. The constant-speed compressor device (100) according to claim 9, wherein the maximum operating speed (313, 426) is greater than the at least one reference operating speed (306, 406, 413) by a predetermined percentage.

11. The constant-speed compressor device (100) according to claim 10, wherein the speed of the motor (120) is increased by the predetermined percentage from the at least one reference operating speed (306, 406, 413) to the maximum operating speed (313, 426) based on the increased flow demand (301, 401).

12. A method for controlling the output pressure of a constant-speed compressor (101), the method comprising the steps of: A controller unit (164) is provided for controlling the speed of the motor (120) to drive the constant-speed compressor (101), wherein the controller unit (164) includes a frequency converter (165); and Discrete speed regulation of the motor (120) is achieved by utilizing the frequency converter (165).

13. The method of claim 12, wherein the discrete speed adjustment is defined by at least one reference speed (306, 406, 413) and a maximum speed (313, 426).

14. The method of claim 13, wherein the at least one reference speed (306, 406, 413) is capable of operating while the output pressure of the constant-speed compressor (101) is below the load setpoint (312, 435).

15. The method of claim 13, wherein the maximum speed (313, 426) is capable of operating simultaneously with the output pressure of the constant speed compressor (101) between a load setpoint (312, 435) and an unload setpoint (314, 437).

16. The method of claim 13, wherein after the constant-speed compressor (101) requires a higher flow rate (302, 403), the output pressure is increased from a steady-state operating level (308, 408) to a higher operating level (319, 431).

17. The method of claim 16, wherein the higher operating level (319, 431) of the output pressure is above the load setpoint (312, 435) and below the unload setpoint (314, 437).

18. The method of claim 17, wherein the motor (120) is connected to the rotating element (122) and generates flow.

19. The method of claim 12, further comprising the step of adjusting the frequency and voltage of the electrical signal sent to the motor (120) to control the speed of the motor (120).

20. The method of claim 12, further comprising the step of increasing the speed of the motor (120) from at least one reference operating speed (306, 406, 413) to a maximum operating speed (313, 426) based on the increased flow demand (302, 403).

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