Air compressor with delayed maximum flow

Abstract

A fixed-speed air compressor device (101) is provided with a controller unit (164) for controlling the speed of a motor (120) for driving the compressor (101). The controller unit (164) comprises an inverter (165) to induce discrete speed regulation of the air compressor (101) for generating extra flow and to provide a higher output pressure. Based on the discrete speed regulation, the air compressor (101) runs at increased speed when required per compressor application.

Description

DescriptionTitle of Invention: AIR COMPRESSORWITH DELAYED MAXIMUM FLOW

[0001] FIELD OF THE DISCLOSURE

[0002] The disclosure is related to an air compressor having an internal inverter allowing for a delayed maximum flow.BACKGROUND

[0003] A rotary screw air compressor is a type of positive displacement gas compressor that uses two rotors to create pressure needed for air compression. The two rotors rotate in opposite directions to draw in air that is compressed as the space between the rotors and the rotor housing decreases. Each screw element has a fixed, built-in pressure ratio dependent on the length and pitch of the screw, and form of the discharge port. To attain maximum efficiency, the built-in pressure ratio must be adapted to the required working pressure. The order of operation of these compressors is determined by the pressure values, and the different scenarios that arise in the factory present varying compressor loads of operation, such as no-load, standby, ready to operate, and load settings. The varying compressed air requirements of a factory can be met by different types of compressors, such as a variable speed drive (VSD) or fixed speed drive compressor.

[0004] Traditional fixed speed compressors operate at fixed revolutions per minute (RPM) over time and supply a consistent frequency output to the motor. To adjust the airflow amount, a fixed-speed air compressor requires adjustment of the air inlet valve to let more or less air out. Once the pressure of the gas storage tank reaches the set value, the motor stops. And when the compressed air is partially used, the pressure of the air storage tank decreases. After the pressure reaches a set value, the motor is started again to drive the air compressor to work. If the compressed air is used a lot, the motor will start and stop frequently, and the motor will consume more electric energy while the electric current is larger during the starting process. Once the motor stops, the energy of the motor cannot be used, so the energy consumed by the frequent start and stop of the motor is increased. A disadvantage of traditional fixed speed compressors is that, even when the air demand is low, the motor always operates at the same fixed speed. Thus, this leads to a less energy-efficient process and is a waste of energy.

[0005] VSD compressors increase the speed of the motor as the need for air increases, thus supplying more flow. If the demand for air decreases, the motor will automatically slow down and only use the required energy to provide appropriate flow. During slow production days or breaks in workflow, VSD compressors are especially useful. Thistype of air compressor saves electricity and energy cost, compared to traditional fixed speed models. VSD compressors use stepless speed regulation characteristics of the motor for air pressure stability and thus address airflow needs according to the realtime demand for a factory. While VSD compressors are more energy-efficient for most applications, they are not necessary if the compressed air needs are constant, or even mostly constant with only occasional slight variations. For example, if the compressed air application is to run assembly-line machinery for 10-12 hours per day, investing in a variable speed compressor will require extra up-front costs. Moreover, if a VSD compressor is correctly sized based on the published maximum Free Air Delivery (FAD) of the unit, the VSD compressor can increase maintenance costs by not turning off and consequently running more hours than needed.

[0006] Many compressors are often oversized based on the published FAD of the compressor device to prevent under sizing and the need of an extra “future-proof’ flow. As a result, the over sizing results in inefficient, bigger compressors and high energy consumption. Under sizing a compressor will result in pressure drops and inability to complete a task; however, oversizing the unit can lead to future mechanical problems and potential failure of the compressor. Moreover, it may become necessary to switch and uninstall compressors as production needs increase and demand for compressed air rises. This subsequently increases costs imposed on the factory. As such, there is a need for a compact compressor device that satisfies the compressed air requirements of a factory with reduced up-front costs and low energy consumption. SUMMARY

[0007] Embodiments of the present disclosure are directed to an air compressor comprising a housing including a pressure vessel, a controller unit, and an air compression element within the housing and being configured to compress air in the pressure vessel. The air compressor has an inverter in the electrical cubicle and coupled directly to a motor of the air compression element, and the inverter operates the air compression element to compress the air into the pressure vessel in at least three phases: load, unload, and stop. During the load phase the inverter causes the air compression element to compress air into the pressure vessel, the pressure vessel having an outlet port from which the compressed air is selectively discharged. During the unload phase the compressed air in the pressure vessel is maintained and the air compression element is operated at a diminished rate, and during the stop phase the air compression element is stopped and pressure within the pressure vessel is maintained. The disclosed compressor device overcomes the drawbacks of existing compressors by comprising an inverter that induces discrete speed regulation of the motor for air pressure stability. The inverterensures that the motor runs at a reference speed before increasing to a maximum speed or RPM.

[0008] According to embodiments of the present disclosure, a fixed-speed air compressor is provided with a controller unit, such as an electrical cubicle, for controlling the speed of a motor for driving the air compression element of the compressor. The motor is connected to the air compression element, such as one or more rotary elements, and generates flow. The controller unit comprises an inverter to adjust the frequency and voltage of an electrical signal sent to the motor, which in turn controls its speed and torque output. The motor is configured to receive the electrical signal from the inverter to control working speed of the motor, the inverter being configured to induce discrete speed regulation of the working speed of the motor. In an embodiment, the inverter provides power and is directly coupled to the air compression element and does not involve any gears connecting a power source to the air compression element. The direct coupling allows for the air compressor to achieve a wide range of pressures by discretely altering the speed at which the motor runs. In alternative embodiments, the inverter may be coupled to the air compression element by means of elastic or flexible couplings, belts, gears, or bearings to connect the inverter to the air compression element. The inverter ensures that the motor runs at one or more discrete reference speeds and a discrete maximum speed. Prior art designs for fixed-speed air compressors do not include an inverter. Thus, the motors of the prior art designs can only run at a fixed maximum speed. The discrete speed regulation of the disclosed air compressor generates extra flow by the compressor and results in a higher output pressure.

[0009] In an embodiment, a compressor device is provided with a controller unit for controlling the speed of a motor for driving the compressor, wherein the controller unit comprises an inverter. The controller unit comprises a processing unit provided with an algorithm to calculate at least one reference working speed of the motor. The algorithm may also calculate a maximum working speed of the motor. In an embodiment, the working speed is discretely defined by a first fixed speed and a second fixed speed. The working speed may be increased by a predefined percentage from the reference working speed to a maximum working speed. Likewise, the working speed may be decreased by a predefined percentage from the maximum working speed to the reference working speed.

[0010] In an embodiment, a fixed- speed compressor apparatus is provided that comprises a processing unit and a computer storage media that stores computer-executable instructions that are executable by the processing unit. Embodiments of the disclosure may comprise or utilize computer hardware, such as, for example, a processor system (e.g., processing unit) and system memory. Computer-readable media thatstore computer-executable instructions and / or data structures are computer storage media (e.g., storage media 104). Computer storage media are physical storage media that store computer-executable instructions and / or data structures. The computerexecutable instructions that are executable by the processing unit include instructions to control the speed of a motor for driving a fixed- speed compressor by an electrical inverter and induce discrete speed regulation of the motor. The computer-executable instructions may also include instructions for calculating at least one reference working speed of the motor and a maximum working speed of the motor.

[0011] In an embodiment, a method for controlling outlet, or output, pressure of a fixed- speed compressor is provided. The method includes providing a controller unit for controlling a speed of a motor to drive the fixed-speed compressor, wherein the controller unit comprises an inverter and inducing, by utilizing the inverter, discrete speed regulation of the speed of the motor.

[0012] In an embodiment, the discrete speed regulation is defined by at least one reference speed and a maximum speed. The at least one reference speed is operable while the outlet pressure of the fixed-speed compressor is below a load setpoint. Additionally, the maximum speed is operable while the outlet pressure of the fixed- speed compressor is between a load setpoint and an unload setpoint. The outlet pressure increases from a steady-state operating level to an advanced operating level after the fixed-speed compressor necessitates an advanced flow demand. Additionally, the advanced operating level of the outlet pressure is greater than a load setpoint and less than an unload setpoint.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Features, aspects, and advantages of the presently disclosed technology may be better understood concerning the following description, appended claims, and accompanying drawings. A person skilled in the relevant art will understand that the features shown in the drawings are purposes of illustration, and variations, including different or additional features and arrangements thereof, are possible.

[0014] Figure 1 illustrates example components of a compressor system according to the present disclosure.

[0015] Figure 2 is a graph of the outputs of pressure, speed, and flow of a reference compressor unit of the prior art.

[0016] Figure 3 is a graph of the outputs of pressure, speed, and flow of an embodiment of a compressor device having two levels of discrete speed regulation.

[0017] Figure 4 is a graph of the outputs of pressure, speed, and flow of an embodiment of a compressor device having three levels of discrete speed regulation.

[0018] Figure 5 illustrates the outputs of motor speed and flow demand of an embodiment of a compressor device having three levels of discrete speed regulation.

[0019] The drawings are to illustrate exemplary implementations and are not drawn to scale. It is understood that the inventions are not limited to the arrangements and instrumentalities shown in the drawings.

[0020] DEFINITIONS

[0021] For ease of understanding the disclosed embodiments of the disclosed method and system elements, a description of a few terms is necessary.

[0022] The term ‘compressor’ or ‘compressor device’ refers to a machine that draws low- pressure gas from auxiliary storage as raw input and then outputs high-pressure gas, either for storage or to feed other processes. The terms ‘compressor’ and ‘compressor elements’ are not intended to be limiting in scope and may refer to positive displacement compressors and / or dynamic compressors (turbocompressors) and / or individual components of compressors.

[0023] The term ‘computer storage media’ refers to physical storage media that store computer-executable instructions and / or data structures. Storage media, such as a digital data carrier, includes 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 disk storage, magnetic disk storage, and the like.

[0024] The term ‘controller’ or ‘controller unit’ generally refers to a computerized command terminal comprising a collection of sensors and electrical components i.e., to regulate various compressor elements. Compressor controllers include at least one main processing unit with a graphical interface and are adapted to monitor the instrumentation of various compressor parts (e.g., motors, rotors, filters, bearings, valves, pressure sensors, temperature sensors).

[0025] 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, hand-held devices, multi-processor systems, microprocessor-based or programmable consumer electronics, network PCs, minicomputers, mainframe computers, mobile telephones, PDAs, tablets, pagers, routers, switches, and the like.

[0026] The term ‘software’ generally refers to computer-executable instructions, code, data, applications, programs, program modules, or the like maintained in or on any form or type of computer-readable media that is configured for storing computer-executable instructions or the like in a manner that is accessible to a computing device.

[0027] As used herein, reference to any type of machine learning or artificial intelligence may include any type of machine learning algorithm or device, convolutional neuralnetwork(s), multilayer neural network(s), recursive neural network(s), recurrent neural network(s), deep neural network(s), decision tree model(s) (e.g., decision trees, random forests, and gradient boosted trees) linear regression model(s), logistic regression model(s), support vector machine(s) (SVM), artificial intelligence device(s), or any other type of intelligent computing system. Any amount of training data may be used (and perhaps later refined) to train the machine learning algorithm to dynamically perform the disclosed operations.

[0028] When introducing elements in the appended claims, the articles “a,” “an,” “the,” and “said” are intended to mean there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.DETAILED DESCRIPTION

[0029] A better understanding of different embodiments of the disclosure may be had from the following description read with the drawings in which like reference characters refer to like elements.

[0030] While the disclosure is susceptible to various modifications and alternative constructions, certain illustrative embodiments are in the drawings and are described below. The dimensions, angles, and curvatures represented are to be understood as exemplary and are not necessarily shown in proportion.

[0031] It should be understood, however, there is no intention to limit the disclosure to the specific embodiments disclosed, but on the contrary, the intention covers all modifications, alternative constructions, and equivalents falling within the spirit and scope of the disclosure.

[0032] According to embodiments of the present disclosure, a fixed-speed air compressor is provided with a controller unit, such as an electrical cubicle, for controlling the speed of a motor for driving the compressor. The controller unit comprises an inverter to adjust the frequency and voltage of an electrical signal sent to the motor, which in turn controls its speed and torque output. The motor is configured to receive the electrical signal from the inverter to control working speed of the motor, the inverter being configured to induce discrete speed regulation of the working speed of the motor. The inverter ensures that the motor runs at one or more discrete reference speeds and a discrete maximum speed.

[0033] Figure 1 illustrates various example components of an example compressor system 100 (e.g., a multi-modal compressor system or apparatus) that may comprise or implement one or more disclosed embodiments. For example, Figure 1 illustrates that a compressor system 100 may include processing unit(s) or processor(s) 102, storage 104, sensor(s) 110, input / output system(s) 114 (I / O system(s) 114), communicationsystem(s) 116, and / or other components. Although Figure 1 illustrates a compressor system 100 as including particular components, one will appreciate, in view of the present disclosure, that a compressor system 100 may comprise any number of additional or alternative components. Furthermore, although some of the components may be illustrated or described as distinct entities, one will appreciate, in view of the present disclosure, that such distinctions are made for the sake of explanation / description only. For example, functionality described herein in association with a particular component may be performed by a different component or a combination of components as described herein. Accordingly, aspects of the components described herein may be combined with other components or divided into multiple components in accordance with the present disclosure. Additionally, aspects of the present disclosure may be incorporated into oil-free compressors and various types of multistage compressors.

[0034] The processor(s) 102 may comprise one or more sets of electronic circuitries that include any number of logic units, registers, and / or control units to facilitate the execution of computer-readable instructions (e.g., instructions that form a computer program). Such computer-readable instructions may be stored within storage 104 (e.g., instructions 106). The storage 104 may comprise physical system memory and may be volatile, non-volatile, or some combination thereof. Furthermore, storage 104 may comprise local storage, remote storage (e.g., accessible via communication system(s) 116 or otherwise), or some combination thereof. Additional details related to processors (e.g., processor(s) 102) and computer storage media (e.g., storage 104) will be provided hereinafter.

[0035] In some implementations, the processor(s) 102 may comprise or be configurable to execute any combination of software and / or hardware components that are operable to facilitate processing using machine learning models or other artificial intelligencebased structures / architectures. For example, processor(s) 102 may comprise and / or utilize hardware components or computer-executable instructions operable to carry out function blocks and / or processing layers configured in the form of, by way of non-limiting example, 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 machine networks, restricted Boltzmann machine networks, deep belief networks, deep convolutional networks (or convolutional neural networks), deconvolutional neural networks, deep convolutional inverse graphics networks, generative adversarial networks, liquid state machines,extreme learning machines, echo state networks, deep residual networks, Kohonen networks, support vector machines, neural Turing machines, and / or others.

[0036] As will be described in more detail, the processor(s) 102 may be configured to execute instructions 106 stored within storage 104 to perform certain actions associated with operation of the compressor system 100. The actions may rely at least in part on data 108 stored on storage 104 in a volatile or non-volatile manner.

[0037] In some instances, the actions may rely at least in part on communication system(s) 116 for receiving data from other components and / or remote system(s) 118, which may include, for example, separate systems or computing devices, sensors, and / or others. The communications system(s) 116 may comprise any combination of software or hardware components that are operable to facilitate communication between on-system components / devices and / or with off-system components / devices. For example, the communications system(s) 116 may comprise ports, buses, or other physical connection apparatuses for communicating with other devices / component s. Additionally, or alternatively, the communications system(s) 116 may comprise systems / components operable to communicate wirelessly with external systems and / or devices through any suitable communication channel(s), such as, by way of nonlimiting example, Bluetooth, ultra-wideband, WLAN, infrared communication, and / or others.

[0038] Figure 1 illustrates that a compressor system 100 may comprise or be in communication with sensor(s) 110 (e.g., to obtain data 108 used to perform acts described herein). Sensor(s) 110 may comprise any device for capturing or measuring data representative of perceivable or detectable phenomena. By way of non-limiting example, the sensor(s) 110 may comprise one or more flow sensors, pressure sensors, hygrometers, image sensors, microphones, thermometers, barometers, magnetometers, accelerometers, gyroscopes, and / or others.

[0039] Furthermore, Figure 1 illustrates that a compressor system 100 may comprise or be in communication with I / O system(s) 114. I / O system(s) 114 may include any type of input or output device such as, by way of non-limiting example, a display, a touch screen, a mouse, a keyboard, a controller unit, a speaker, and / or others, without limitation.

[0040] Figure 1 also illustrates additional example components of or in communication with the compressor system 100. For instance, Figure 1 illustrates the compressor system 100 comprising a compressor device 101 with a compressor motor 120 configured to actuate a compressor element 122 to facilitate gas compression (e.g., compression of ambient air). The compressor device 101 is a fixed-speed compressor. The compressor motor 120 may take on any suitable form, such as a three-phase induction motor. Similarly, the compressor element 122 may take on any suitable form, such as anytype of dynamic compressor (e.g., ejector, radial, or axial compressor) or displacement compressor such as a rotary compressor (e.g., a single rotor such as a vane, liquid ring, or scroll compressor; or a multi-rotor compressor such as a screw, tooth, or blower compressor) or a piston compressor.

[0041] Figure 1 also illustrates various additional components that may operate in conjunction with the compressor motor 120 and the compressor element 122 to facilitate gas compression. Figure 1 illustrates the compressor system as including an inlet filter 124, a sentinel valve 126, air / oil vessel separator 128, thermostatic bypass valve 130, oil filter 132, safety valve 134, oil separator 136, minimum pressure valve 138, solenoid valve 140, after cooler 142, fan 144, oil cooler 146, electronic drain 148, a dryer 150 (the electronic drain 148 can be mounted on the after cooler 142 in implementations that omit the dryer 150), and a condensate prevention cycle 152. As noted above, one or more of the components shown in Figure 1 may be omitted from a compressor system 100, or alternative components / structures may be utilized in accordance with the scope of the present disclosure.

[0042] Figure 1 also illustrates the compressor system 100 as including a frequency converter 160 configured to connect to a power source 162 and to the compressor motor 120 (as indicated in Figure 1 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 discussed above, the frequency converter 160 controls the operational motor speed of the compressor motor by controlling the frequency and voltage of the compressor motor 120. The frequency converter 160 may comprise a rotary frequency converter, a solid state frequency converter, etc. The power source 162 may comprise a grid-connected power source or an off-grid power source.

[0043] Figure 1 depicts that operation of the frequency converter 160 (and / or the compressor device 101) may be controlled by a controller unit or multi-modal drive controller 164 (as indicated in Figure 1 by dashed lines extending from the multi-modal drive controller 164 to the frequency converter 160 and to the compressor motor 120). The compressor 101 includes an internal inverter 165 to adjust the frequency and voltage of an electrical signal sent to the motor 120, which in turn controls its speed and torque output. The multi-modal drive controller 164 may comprise or operate in conjunction with the processor(s) 102 to govern operation of the frequency converter 160 and / or the compressor motor 120. The processor(s) 102 are preferably provided with an algorithm to calculate at least one reference working speed of the motor 120. In an embodiment, the multi-modal drive controller 164 comprises or operates in conjunction with the processor(s) 102 to adjust the frequency and voltage of an electrical signal sent to the motor 120, which in turn controls its speed and torque output.

[0044] According to a first embodiment, the multi-modal controller is configured to operate the frequency converter 160 and / or the compressor motor 120 according to a plurality of operational modes including at least a first compression mode 166 and a second compression mode 168 (as indicated in Figure 1 by solid lines extending from the multi-modal 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 operational motor speed profiles. For example, the first compression mode 166 may comprise a load / unload compression mode, and the second compression mode 168 may comprise a 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 a period of idling). During the load state (and often the unload state), the compressor motor 120 runs at a substantially constant operational motor speed. This can be accomplished, for example, by configuring the frequency converter 160, via the multi-modal drive controller 164, to impose a substantially constant frequency and voltage for the compressor motor 120 for operation in the load state of the load / unload compression mode, or by bypassing, via the multi-modal drive controller 164, one or more aspects of the frequency converter 160 to allow a constant frequency and voltage to be supplied to the compressor motor 120 from the power source 162 and / or one or more intervening components.

[0045] According to other embodiments, the multi-modal controller is configured to operate the one or more other control components of the compressor system according to a plurality of operational 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.

[0046] Figure 2 is a plot 200 of the outputs of pressure in the pressure vessel, speed of the motor, and flow demand of the compressed air, each output being depicted as a function of time, according to the prior art. The plot 200 illustrates the output parameters of the prior art reference unit having a fixed- speed drive without a delayed maximum flow. The first reference speed 206, or reference RPM, of the motor is equal to the maximum speed, or maximum RPM, of the compressor unit. The reference unit of plot 200 does not comprise an inverter. Thus, over time, the motor runs at a fixed maximum speed, which is the reference speed 206, without control to increase or decrease with respect to the flow demand 201. The plot 200 begins at the time that the reference unit is initiated or turned on. The output pressure increases toward the load and unload setpoints 212, 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 aninitial flow level 204. However, as explained above, the motor of the reference unit of plot 200 will continuously run at a reference speed 206 that is equal to the maximum speed even when it is not required per factory application. Prior art designs for fixed- speed air compressors do not include an inverter. Thus, the motors of the prior art designs can only run at a fixed maximum speed. The discrete speed regulation of the disclosed air compressor generates extra flow by the compressor and results in a higher output pressure.

[0047] Figure 3 is a plot 300 of the outputs of pressure in the pressure vessel, speed of the motor, and flow demand of the compressed air, each output being depicted as a function of time. The plot 300 illustrates the output parameters of an embodiment of a compressor device 101 having a fixed-speed drive with a delayed maximum flow. The compressor device 101 of plot 300 comprises an inverter 165 that is configured to induce discrete speed regulation of the working speed of the motor. The discrete speed regulation portrayed in plot 300 depicts a first fixed speed 306 and a second fixed speed 313. In an 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. The plot 300 begins at the time that the compressor device 101 is initiated or turned on. Upon initiation of the compressor device 101, the motor of the compressor device 101 runs at a first fixed speed 306. As the motor runs at the first fixed speed 306, the output pressure increases to an initial pressure level 310 and the flow demand 301 to an initial flow level 304. The output pressure increases toward the load and unload setpoints 312, 314 to the initial pressure level 310 and remains below the load setpoint 312 at a steady-state operating level 308 until the flow demand 301 increases from a first level 305 to a second level 307 and transitions to an advanced flow demand 302.

[0048] Once the compressor device 101 necessitates the advanced flow demand 302, the output pressure increases from the steady-state operating level 308 at a lower pressure level 315 to an advanced operating level 319 at a higher pressure level 317. As depicted, the higher pressure level 317 is greater than the load setpoint 312 and less than the unload setpoint 314. Moreover, once the compressor device 101 necessitates the advanced flow demand 302, the first fixed speed 306 increases from a first discrete level 309 to a second discrete level 311 and the motor subsequently runs at the second fixed speed 313.

[0049] After the fixed-speed compressor device 101 of plot 300 is in load condition for a certain amount of time between the initial pressure level 310 and the lower pressure level 315, without reaching the load setpoint 312, the motor speed increases by a predefined percentage from the first discrete level 309 to the second discrete level 311. By doing so, extra flow is generated by the compressor device 101 resulting in a higheroutput pressure at an advanced operating level 319. Thus, the compressor device 101 will only run in a max speed condition at the second fixed speed 313 when required per factory application.

[0050] Figure 4 is a plot 400 of the outputs of pressure in the pressure vessel, speed of the motor, and flow demand of the compressed air, each output being depicted as a function of time. The plot 400 illustrates the output parameters of an embodiment of a compressor device 101 having a fixed-speed drive with a delayed maximum flow. The compressor device 101 of plot 400 comprises an inverter 165 that is configured to induce discrete speed regulation of the working speed of the motor. The discrete speed regulation portrayed in plot 400 depicts a first fixed speed 406, a second fixed speed 413, and a third fixed speed 426. The plot 400 begins at the time that the compressor device 101 is initiated or turned on. Upon initiation of the compressor device 101, the motor of the compressor device 101 runs at a first fixed speed 406. As the motor runs at the first fixed speed 406, the output pressure increases to an initial pressure level 410 and the flow demand 401 to an initial flow level 404. The output pressure increases toward the load, intermediate, and unload setpoints 435, 436, 437 to the initial pressure level 410 and remains below the load setpoint 435 at a steady-state operating level 408 until the flow demand 401 increases from a first level 405 to a second level 407 and transitions to an intermediate flow demand 402.

[0051] Once the compressor device 101 necessitates the intermediate flow demand 402, the output pressure increases from the steady-state operating level 408 at a lower pressure level 415 to an intermediate operating level 419 at an intermediate pressure level 417. As depicted, the intermediate pressure level 417 is greater than the load setpoint 435 and less than the intermediate setpoint 436. Moreover, once the compressor device 101 necessitates 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 runs at the second fixed speed 413.

[0052] After the fixed-speed compressor device 101 of plot 400 is in load condition for a certain amount of time between the initial pressure level 410 and the lower pressure level 415, without reaching the load setpoint 435, the motor speed increases by a predefined percentage from the first discrete level 409 to the second discrete level 411. By doing so, extra flow is generated by the compressor device 101 resulting in a higher output pressure at an intermediate operating level 419. Thus, the compressor device 101 will only run in an intermediate speed condition at the second fixed speed 413 when required per factory application.

[0053] As the motor runs at the second fixed speed 413, the output pressure stays between the load setpoint 435 and the intermediate setpoint 436. As the intermediate flow demand 402 increases from a second level 421 to a third level 422 and transitions to anadvanced flow demand 403, the output pressure increases toward the intermediate and unload setpoints 436, 437.

[0054] Once the compressor device 101 necessitates the advanced flow demand 403, the output pressure increases from the intermediate operating level 419 at an intermediate pressure level 430 to an advanced operating level 431 at higher pressure level 432. As depicted, the higher pressure level 432 is greater than the intermediate setpoint 436 and less than the unload setpoint 437. Moreover, once the compressor device 101 necessitates the advanced flow demand 403, the second fixed speed 413 increases from a second discrete level 425 to a third discrete level 427 and the motor subsequently runs at the third fixed speed 426.

[0055] After the fixed-speed compressor device 101 of plot 400 is in load condition for a certain amount of time between intermediate pressure levels 417, 430, without reaching the intermediate setpoint 436, the motor speed increases by a pre-defined percentage from the second discrete level 425 to the third discrete level 427. By doing so, extra flow is generated by the compressor device 101 resulting in a higher output pressure at an advanced operating level 431. Thus, the compressor device 101 will only run in an advanced speed condition at the third fixed speed 426 when required per factory application.

[0056] As the motor runs at the third fixed speed 426, the output pressure stays between the intermediate setpoint 436 and the unload setpoint 437. As the advanced flow demand 403 decreases from a third level 423 to a second level 424 and transitions to an intermediate flow demand 402, the output pressure decreases toward the load and intermediate setpoints 435, 436.

[0057] Once the compressor device 101 no longer necessitates the advanced flow demand 403, the output pressure decreases from the advanced operating level 431 at an advanced pressure level 433 to an intermediate operating level 419 at intermediate pressure level 434. Moreover, once the compressor device 101 no longer necessitates the advanced flow demand 403, the third fixed speed 426 decreases from a third discrete level 428 to a second discrete level 429 and the motor subsequently runs at the second fixed speed 413. Thus, the compressor device 101 will only run in an advanced speed condition at the third fixed speed 426 when required per factory application. This saves energy and cost of continuously running the fixed-speed compressor at a single, fixed maximum speed during hours of operation.

[0058] In an embodiment wherein the motor has three control speeds (low speed or first fixed speed level 406, reference speed or second fixed speed level 413, and max speed or third fixed speed level 426), the speed can be selected based on the output pressure and pressure settings. When the output pressure drops below a load pressure limit or load setpoint 435 of the motor, the control system can switch the motor from theunloaded state to the load state, wherein both cases the motor is running at a low speed 406. As the output pressure begins to rise, the control system can evaluate if there is the need to switch to the reference speed 413. This means that when the pressure rise is too slow and the output pressure will remain below an intermediate load pressure limit or intermediate setpoint 436, the motor speed will increase from low speed 406 to reference speed 413. As the output pressure begins to rise further and faster, the control system should evaluate again if there is the extra need to switch to the max speed 426. This means that when the pressure rise is still too slow and the output pressure will remain below the maximum load pressure limit or unload setpoint 437, the motor speed will increase from reference speed 413 to max speed 426. If the output pressure increases and eventually exceeds the unload setpoint 437, the control system should switch the compressor to the unloaded state. This means that the compressor motor will go to again low speed 406 while the compressor recirculates the air inside the unit.

[0059] Figure 5 is a plot 500 of the outputs of motor speed 502 and flow demand 510 of an embodiment of a compressor device 101 having three levels of discrete speed regulation., each output being depicted as a function of time. The 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 plot 500 illustrates the output parameters of an embodiment of a compressor device 101 having a fixed-speed drive with a delayed maximum flow.

[0060] It is to be understood that not necessarily all objects or advantages may be achieved under any embodiment of the disclosure. Those skilled in the art will recognize that the claimed compressor device may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without achieving other objects or advantages as taught or suggested herein.

[0061] The skilled artisan will recognize the interchangeability of various disclosed features. Besides the variations described herein, other known equivalents for each feature can be mixed and matched by one of ordinary skill in this art to build and use a compressor device under principles of the present disclosure. For example, an inverter of the disclosed fixed-speed compressor may permit discrete speed regulation of a motor with several fixed speeds. It will be understood by the skilled artisan that the features described herein may be adapted to other methods and types of air compressor devices / applications.

[0062] It is intended that the present disclosure should not be limited by the disclosed embodiments described above and may be extended to other applications that may employ the features described herein.

Claims

Claims

1. A compressor device (101) comprising: a controller unit (164) for controlling speed of a motor (102) for driving the compressor device (101), the controller unit (164) including an inverter (165); wherein the motor (120) is configured to receive an electrical signal from the inverter (165) to control working speed of the motor (120), the inverter (165) being configured to induce discrete speed regulation of the working speed of the motor (165).

2. The compressor device (101) according to claim 1, wherein the inverter (165) adjusts 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) comprises a processing unit (102) provided with an algorithm to calculate a reference working speed (306, 406) of the motor (120).

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

5. The compressor device (101) according to claim 4, wherein the working 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 working 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 fixed-speed drive compressor.

8. A fixed-speed compressor apparatus (100) comprising: a processing unit (102); and a computer storage media (104) that stores computer-executable instructions (106) that are executable by the processing unit (102) to at least: control speed of a motor (120) for driving a fixed- speed compressor (101) by an electrical inverter (165); and induce discrete speed regulation of the motor (120).

9. The fixed-speed compressor apparatus (100) according to claim8, wherein the computer storage media (104) further stores computer-executable instructions (106) that are executable by the processing unit (102) to calculate at least one reference working speed (306, 406, 413) of the motor (102) and a maximum working speed (313, 426) of the motor (120).

10. The fixed- speed compressor apparatus (100) according to claim9, wherein the maximum working speed (313, 426) is greater than the at least one reference working speed (306, 406, 413) by a predefined percentage.

11. The fixed- speed compressor apparatus (100) according to claim10, wherein the speed of the motor (120) is increased from the at least one reference working speed (306, 406, 413) to the maximum working speed (313, 426) by the predefined percentage based on increased flow demand (301, 401).

12. A method for controlling output pressure of a fixed- speed compressor (101), the method comprising the steps of: providing a controller unit (164) for controlling a speed of a motor (120) to drive the fixed-speed compressor (101), wherein the controller unit (164) comprises an inverter (165); and inducing, by utilizing the inverter (165), discrete speed regulation of the speed of the motor (120).

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

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

15. The method according to claim 13, wherein the maximum speed(313, 426) is operable while the output pressure of the fixed-speed compressor (101) is between a load setpoint (312, 435) and an unload setpoint (314, 437).

16. The method according to claim 13, wherein the output pressure increases from a steady-state operating level (308, 408) to an advanced operating level (319, 431) after the fixed-speed compressor (101) necessitates an advanced flow demand (302, 403).

17. The method according to claim 16, wherein the advanced operating level (319, 431) of the output pressure is greater than a load setpoint (312, 435) and less than an unload setpoint (314, 437).

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

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

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

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