System and method for controlling compressor capacity

Abstract

A heat exchanger for heating, ventilation, air conditioning and refrigeration (HVACamp; a compressor system of an HVACamp (R, R) system, the compressor system comprising one or more compressors configured to circulate a working fluid through the HVACamp; a vapor compression system of an R system, each compressor of the one or more compressors having a pre-rotating vane (PRV) and a variable geometry diffuser (VGD), the PRV and the VGD configured to operate to adjust a capacity of the compressor system. The compressor system further includes a controller having a memory and processing circuitry, where the memory includes instructions stored thereon that, when executed by the processing circuitry, cause the processing circuitry to: determine a head coefficient for each compressor of the one or more compressors, and determine a head coefficient for each compressor of the one or more compressors; determining a compressor lift for each of the one or more compressors based at least in part on the head coefficient, comparing the compressor lift for each of the one or more compressors to a low lift threshold and a high lift threshold, and operating each of the one or more compressors in a first mode or a second mode based on a comparison of the compressor lift to the low lift threshold and the high lift threshold.

Description

[0001] describe Cross-reference to related applications This application claims priority and benefit to U.S. Provisional Application No. 63 / 466,152, filed May 12, 2023, entitled “SYSTEM AND METHOD FOR CONTROLLING CAPACITY OF COMPRESSOR,” the entire contents of which are incorporated herein by reference for all purposes. Background Technology

[0002] This section aims to introduce the reader to various aspects of the technology that may relate to the various aspects of this disclosure described below. It is believed that this discussion will help provide the reader with background information to facilitate a better understanding of the various aspects of this disclosure. Therefore, it should be understood that these statements should be read in this light, rather than as an endorsement of prior art.

[0003] Refrigeration systems, or vapor compression systems, utilize a working fluid (e.g., a refrigerant) that changes the phase between vapor, liquid, and combinations thereof in response to varying temperatures and pressures exposed within components of the refrigeration system. Refrigeration systems can place the working fluid in a heat exchange relationship with a cooling fluid (e.g., water) and can deliver the cooling fluid to regulated equipment and / or regulated environments served by the refrigeration system. In such applications, the cooling fluid can be directed through downstream devices such as air handlers to regulate other fluids, such as air within a building. Refrigeration systems may include one or more compressors configured to pressurize the working fluid and circulate it through a working fluid loop. Unfortunately, implementing multiple compressors and / or multi-stage compressors and their various components in a refrigeration system increases the complexity of effectively controlling the refrigeration system. Summary of the Invention

[0004] The following provides an overview of certain embodiments disclosed herein. It should be understood that these aspects are presented merely to provide the reader with a brief overview of these particular embodiments, and these aspects are not intended to limit the scope of this disclosure. In fact, this disclosure may cover various aspects that may not be set forth below.

[0005] In one embodiment, a compressor system for a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system includes one or more compressors configured to circulate working fluid through a vapor compression system of the HVAC&R system. Each of the one or more compressors has a pre-rotating vane (PRV) and a variable geometry diffuser (VGD) configured to operate to regulate the capacity of the compressor system. The compressor system further includes a controller having a memory and processing circuitry. The memory includes instructions stored thereon that, when executed by the processing circuitry, cause the processing circuitry to: determine a head coefficient for each of the one or more compressors; determine a compressor lift for each of the one or more compressors based at least in part on the head coefficient; compare the compressor lift for each of the one or more compressors with a low lift threshold and a high lift threshold; and operate each of the one or more compressors in a first mode or a second mode based on the comparison of the compressor lift with the low lift threshold and the high lift threshold.

[0006] In another embodiment, the heating, ventilation, air conditioning, and refrigeration (HVAC&R) system includes a vapor compression system having a vapor compression circuit and a compressor. The vapor compression circuit is configured to circulate a working fluid therethrough, and the compressor is configured to pressurize and direct the working fluid through the vapor compression circuit. The compressor includes a pre-rotating vane (PRV) adjustable between a fully open position and a first fully closed position, and a variable geometry diffuser (VGD) adjustable between a maximum permissible open position and a second fully closed position. The HVAC&R system further includes a controller having a memory and processing circuitry. The memory stores instructions that, when executed by the processing circuitry, cause the processing circuitry to switch the operation of the compressor between a first mode and a second mode to adjust the compressor capacity. In the first mode, a first position of the VGD is independent of a second position of the PRV, and in the second mode, the first position of the VGD depends on the second position of the PRV.

[0007] In another embodiment, a method for controlling the capacity of a compressor having a pre-rotating vane (PRV) and a variable geometry diffuser (VGD) includes: determining an actual head coefficient of the compressor based on one or more operating conditions of a vapor compression system employing the compressor; determining a compressor lift based on the ratio of the actual head coefficient to a maximum head coefficient, comparing the lift with a low lift threshold and a high lift threshold to generate a comparison result; operating the compressor in a first mode in response to the comparison result indicating that the lift is less than the low lift threshold, wherein in the first mode the position of the VGD changes independently of the position of the PRV; and operating the compressor in a second mode in response to the comparison result indicating that the lift is greater than the high lift threshold, wherein in the second mode the position of the VGD changes based on a correlation between the positions of the VGD and the PRV. Attached Figure Description

[0008] A better understanding of the various aspects of this disclosure can be achieved by reading the following detailed description and referring to the figures, in which: Figure 1 This is a perspective view of an embodiment of a building in a commercial environment that can utilize heating, ventilation, air conditioning and / or cooling (HVAC&R) systems, according to one aspect of this disclosure; Figure 2 This is a perspective view of an embodiment of a vapor compression system according to one aspect of the present disclosure; Figure 3 This is a schematic diagram of an embodiment of a vapor compression system according to one aspect of the present disclosure; Figure 4 This is a schematic diagram of an embodiment of a vapor compression system according to one aspect of the present disclosure; Figure 5 This is a schematic diagram of an embodiment of a vapor compression system having two compressors according to one aspect of this disclosure; Figure 6 This is a graphical representation illustrating the correlation between the position of the pre-rotating blades of a vapor compression system according to one aspect of this disclosure and the maximum permissible opening position of a variable geometry diffuser; Figure 7 This is a flowchart illustrating an embodiment of a method for controlling the capacity of a compressor in a vapor compression system according to one aspect of this disclosure; and Figure 8 This is a flowchart of an embodiment of a stall noise reduction control method according to one aspect of this disclosure. Detailed Implementation

[0009] One or more specific embodiments of the present invention will be described below. These described embodiments are examples of the currently disclosed technology. Additionally, in the process of providing a concise description of these embodiments, not all features of actual implementations may be described in the specification. It should be understood that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made to achieve specific goals of the developer, such as compliance with system-related and business-related constraints, which may vary from implementation to implementation. Furthermore, it should be understood that such development work may be complex and time-consuming, but is merely a routine task of design, manufacture, and production for those skilled in the art who benefit from this disclosure.

[0010] In describing the elements of various embodiments of this disclosure, the articles “a” and “the” are intended to mean the presence of one or more of the element. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that additional elements may be present in addition to those listed. Furthermore, it should be understood that references to “one embodiment” or “embodiment” in this disclosure are not intended to exclude the existence of additional embodiments further incorporated into the described features.

[0011] As used herein, the terms “approximately,” “generally,” “substantially,” etc., are intended to convey that the attribute value being described can be within a relatively small range, as understood by one of ordinary skill in the art. For example, when an attribute value is described as “approximately” equal to (or, for example, “substantially similar to” a given value), this is intended to convey that the attribute value can be within + / -5%, + / -4%, + / -3%, + / -2%, + / -1%, or even closer to the given value. Similarly, when a given feature is described as “substantially parallel” to another feature, “generally perpendicular” to another feature, etc., this is intended to convey that the given feature has the described property, such as being parallel to another feature, perpendicular to another feature, etc., within + / -5%, + / -4%, + / -3%, + / -2%, + / -1%, or even closer to the other feature. Mathematical terms (such as “parallel” and “perpendicular”) should not be interpreted strictly in a rigorous mathematical sense, but rather should be interpreted as such terms would be understood by one of ordinary skill in the art. For example, someone skilled in the art would understand that two lines that are generally parallel to each other are largely parallel, but may deviate slightly from being perfectly parallel.

[0012] As briefly discussed above, heating, ventilation, air conditioning, and / or cooling (HVAC&R) systems can be used to thermally condition spaces within buildings, residences, or other suitable structures. For example, such an HVAC&R system may include a vapor compression system (e.g., a refrigeration system, a vapor compression loop) that transfers heat between a working fluid (e.g., a refrigerant, a heat transfer fluid) and a fluid to be conditioned (e.g., air, water, brine). The vapor compression system may include a first heat exchanger (e.g., a condenser) and a second heat exchanger (e.g., an evaporator), which are fluidly connected to each other via one or more conduits (e.g., a vapor compression loop, a refrigerant loop, a working fluid loop). A compressor may be used to pressurize the working fluid and circulate it through one or more conduits, thus enabling heat transfer between the working fluid and the fluid to be conditioned via the condenser and evaporator.

[0013] Compressors (e.g., centrifugal compressors) can be designed for certain operating conditions, which may include one or more characteristics or parameters of the working fluid (e.g., refrigerant). For example, compressors can be designed and / or selected for implementation in an HVAC&R system based on the working fluid flow rate (e.g., velocity), the working fluid temperature and pressure conditions at the compressor's suction inlet, and / or the working fluid temperature and pressure conditions at the compressor's discharge outlet. In some applications, the HVAC&R system may utilize multiple compressors (e.g., compressor systems) to achieve a desired lift (e.g., differential pressure) of the working fluid through a vapor compression fluid loop. The lift or "head" of a compressor or compressor system can be defined as the work or productivity of the compressor or compressor system and can be expressed as the difference between the compressor discharge pressure and the compressor suction pressure. The operation of each compressor can be controlled to enable operation under various design conditions (e.g., parameters) and / or to avoid undesirable operation or operating conditions (e.g., compressor surge, compressor stall).

[0014] The design conditions of a centrifugal compressor can be defined by parameters of the flow rate of the working fluid through the compressor, as well as the temperature and pressure conditions at the compressor's suction (e.g., inlet) and discharge (e.g., outlet). The compressor may operate continuously near its design conditions, or the operating environment may deviate significantly from the design conditions over extended periods. Compressors used in HVAC&R systems can vary considerably. The flow rate of the working fluid through the compressor may depend on the cooling load requirements, while pressure conditions such as condensing pressure may depend on ambient temperature conditions.

[0015] Centrifugal compressors may encounter instabilities such as surge or stall during operation when operating conditions deviate from design conditions. A stall or stall process is a localized flow separation in one or more components of the compressor, and it can be characterized by discharge pressure disturbances at frequencies lower than the compressor's impeller rotation frequency. Surge or surge is a transient phenomenon with oscillations in pressure and flow rate, and can potentially lead to a complete reversal of flow through the compressor. When surge occurs, the compressor may be unable to deliver the desired working fluid flow rate under the desired pressure conditions. Furthermore, surge can cause excessive noise and / or vibration in both rotating and stationary components of the compressor, which can lead to compressor damage, wear, and / or degradation. Various devices and control parameters can be used to regulate compressor operation to desired flow and pressure conditions while avoiding compressor surge. A simple way to reduce the working fluid flow rate through a centrifugal compressor is to reduce the compressor speed. Variable speed compressors can be achieved via a turbine drive or an electric motor powered by a variable speed drive (VSD). Surge can be avoided within a limited range, if feasible, but may not be completely eliminated. When deceleration is not possible, another solution is to use flow reduction devices (“FRDs”), such as pre-rotating vanes (“PRVs”) or variable geometry diffusers (“VGDs”), to reduce the flow of working fluid through the compressor.

[0016] For example, pre-rotating vanes (“PRV”) or inlet guide vanes may be located at the inlet of the respective compressor and configured to control the flow rate of the working fluid entering the compressor (e.g., from the evaporator). In some cases, actuators may be used to control the opening and closing of the PRV to regulate the flow rate of the working fluid entering the compressor, thereby regulating the cooling capacity of the system. A variable geometry diffuser (“VGD”) may be located at the outlet of the compressor and may be used to prevent stall, prevent surge, and reduce noise associated with such conditions. In some cases, the VGD may be used to control the flow rate of the working fluid exiting the compressor. For example, the VGD may include a diffuser ring configured to move into and out of a diffuser clearance, which may also correspond to an outlet or discharge path (e.g., a diffuser) for the compressed working fluid discharged from the compressor. The VGD can be adjusted to a fully open position, in which the diffuser ring is completely removed from the outlet flow path to achieve the upper threshold flow rate of the working fluid; the VGD can also be adjusted to a partially or fully closed position, in which the diffuser ring occupies at least a portion of the outlet flow path or extends within at least a portion of the outlet flow path, thereby limiting the working fluid flow rate. For example, when a stall condition is detected, the actuator can turn the VGD toward the partially or fully closed position until the stall condition is suppressed, thereby avoiding surge.

[0017] Traditionally, PRV (Pressure Variants Drive), or VGD (Voltage Gear Diverter), is used to regulate compressor capacity, while VGD is typically controlled based on stall voltage. Depending on the availability on the compressor, the settings of these components (i.e., variable speed drive, pre-rotating vanes, and variable geometry diffuser) are managed by stability control algorithms (e.g., control logic) designed to keep the machine operating stably under required operating conditions, avoiding surge while improving efficiency. However, when the flow rate of the working fluid through the compressor is below a threshold (e.g., at low flow rates), this control logic may fail to enable the corresponding compressor to meet certain lift requirements.

[0018] Traditional HVAC&R systems employing multiple compressors or compression stages (e.g., low-pressure compressor, medium-pressure compressor, high-pressure compressor, first-stage compressor, second-stage compressor, third-stage compressor) may have corresponding capacity regulation components (e.g., PRV system, inlet guide vanes, VGD) or flow reduction devices (FRDs) associated with each compressor. Existing systems utilizing various flow reduction devices (e.g., capacity regulation components) can be configured to operate the various components using a common control scheme. Unfortunately, incorporating multiple capacity regulation components (e.g., PRV system and VGD associated with each compressor) into a system with multiple compressors increases the costs associated with the manufacture, operation (e.g., energy consumption), and / or maintenance of the HVAC&R system, and increases the complexity of controlling the various capacity regulation components. Therefore, embodiments of the present invention relate to a vapor compression system having multiple compressors (e.g., one or more of a low-pressure compressor, a medium-pressure compressor, and / or a high-pressure compressor, a first-stage compressor, a second-stage compressor, a third-stage compressor, a low-stage compressor, and a high-stage compressor), which are configured to operate in combination with each other, resulting in improved efficiency and reduced energy consumption to meet load and / or cooling requirements. More specifically, embodiments of this disclosure relate to a control scheme (e.g., adaptive control logic) for a vapor compression system having multiple compressors, which enables the multiple compressors to operate in a coordinated manner to meet the load requirements of the vapor compression system while reducing energy consumption and maintaining the operation of the vapor compression system within desired operating conditions (e.g., avoiding surge and / or stall).

[0019] Now turn to the attached diagram. Figure 1This is a perspective view of an embodiment of a heating, ventilation, air conditioning, and cooling (HVAC&R) system 10 in a building 12 for a typical commercial environment. The HVAC&R system 10 may include a vapor compression system 14 (e.g., a chiller) that supplies a cooling liquid for cooling the building 12. The HVAC&R system 10 may also include a boiler 16 that supplies warm liquid to heat the building 12 and an air distribution system that circulates air through the building 12. The air distribution system may also include an air return duct 18, an air supply duct 20, and / or an air handler 22. In some embodiments, the air handler 22 may include a heat exchanger connected to the boiler 16 and the vapor compression system 14 via a conduit 24. Depending on the operating mode of the HVAC&R system 10, the heat exchanger in the air handler 22 may receive heated liquid from the boiler 16 or cooled liquid from the vapor compression system 14. HVAC&R system 10 is shown as having a separate air processor on each floor of building 12, but in other embodiments, HVAC&R system 10 may include air processor 22 and / or other components that may be shared between floors.

[0020] Figure 2 and Figure 3 An embodiment of a vapor compression system 14 that can be used in an HVAC&R system 10 is shown. The vapor compression system 14 circulates working fluid through a loop beginning with a compressor 32. This loop may also include a condenser 34, an expansion valve or expansion device 36, and a liquid chiller or evaporator 38. The vapor compression system 14 may further include a control panel 40 having an analog-to-digital (A / D) converter 42, a microprocessor 44, non-volatile memory 46, and / or an interface board 48.

[0021] Some examples of fluids that can be used as working fluids (e.g., refrigerants) in vapor compression system 14 include hydrofluorocarbon (HFC) working fluids such as R-410A, R-407, R-134a, hydrofluoroolefins (HFO); “natural” working fluids such as ammonia (NH3), R-717, carbon dioxide (CO2), R-744; or hydrocarbon-based refrigerants, water vapor, or any other suitable working fluid. In some embodiments, vapor compression system 14 may be configured to effectively utilize a working fluid with a standard boiling point of about 19 degrees Celsius (66 degrees Fahrenheit) at one atmosphere, also referred to as a low-pressure working fluid relative to medium-pressure working fluids such as R-134a. As used herein, “standard boiling point” can refer to the boiling point temperature measured at one atmosphere.

[0022] In some embodiments, the vapor compression system 14 may use one or more of a variable speed drive (VSD) 52, a motor 50, a compressor 32, a condenser 34, an expansion valve or device 36, and / or an evaporator 38. The motor 50 may drive the compressor 32 and may be powered by the VSD 52. The VSD 52 receives AC power with a specific fixed line voltage and fixed line frequency from an alternating current (AC) power source and supplies power with a variable voltage and frequency to the motor 50. In other embodiments, the motor 50 may be directly powered by an AC or direct current (DC) power source. The motor 50 may include any type of motor that can be powered by a VSD or directly by an AC or DC power source, such as a switched reluctance motor, an induction motor, an electronically rectified permanent magnet motor, or another suitable motor.

[0023] Compressor 32 compresses the working fluid vapor and delivers it to condenser 34 through a discharge passage. In some embodiments, compressor 32 may be a centrifugal compressor. The working fluid vapor delivered by compressor 32 to condenser 34 can transfer heat to the cooling fluid (e.g., water or air) in condenser 34. As a result of heat transfer with the cooling fluid, the working fluid vapor can condense into liquid refrigerant in condenser 34. The liquid working fluid from condenser 34 can flow to evaporator 38 through expansion device 36. Figure 3 In the illustrated embodiment, the condenser 34 is water-cooled and includes a tube bundle 54 connected to a cooling tower 56, which supplies cooling fluid to the condenser 34.

[0024] The liquid working fluid delivered to evaporator 38 may absorb heat from another cooling fluid, which may or may not be the same cooling fluid used in condenser 34. The liquid working fluid in evaporator 38 may undergo a phase change from liquid working fluid to working fluid vapor. For example... Figure 3 As shown in the illustrated embodiment, the evaporator 38 may include a tube bundle 58 having a supply line 60S and a return line 60R connected to the cooling load 62. Cooling fluid (e.g., water, ethylene glycol, calcium chloride brine, sodium chloride brine, or any other suitable fluid) enters the evaporator 38 via the return line 60R and exits the evaporator 38 via the supply line 60S. The evaporator 38 may reduce the temperature of the cooling fluid in the tube bundle 58 via heat transfer with the working fluid. The tube bundle 58 in the evaporator 38 may comprise multiple tubes and / or multiple tube bundles. In any case, the vapor working fluid exits the evaporator 38 and returns to the compressor 32 via the suction line to complete the cycle.

[0025] Figure 4This is a schematic diagram of a vapor compression system 14, in which an intermediate loop 64 is connected between the condenser 34 and the expansion device 36. The intermediate loop 64 may have an inlet line 68 that is directly fluidly connected to the condenser 34. In other embodiments, the inlet line 68 may be indirectly fluidly connected to the condenser 34. Figure 4 As shown in the illustrated embodiment, the inlet line 68 includes a first expansion device 66 positioned upstream of the intermediate container 70. In some embodiments, the intermediate container 70 may be a flash tank (e.g., a flash intermediate freezer, an economizer, etc.). In other embodiments, the intermediate container 70 may be configured as a heat exchanger or a "surface economizer." Figure 4 In the illustrated embodiment, the intermediate container 70 serves as a flash tank, and the first expansion device 66 is configured to reduce the pressure of the liquid working fluid received from the condenser 34 (e.g., to expand the liquid working fluid). During the expansion process, a portion of the liquid may evaporate, and thus the intermediate container 70 can be used to separate the vapor from the liquid received from the first expansion device 66.

[0026] Additionally, the intermediate container 70 provides further expansion of the liquid working fluid due to the pressure drop it experiences upon entering the intermediate container 70 (e.g., due to the rapid increase in volume experienced upon entering the intermediate container 70). Vapor in the intermediate container 70 can be drawn into the compressor 32 via its suction line 74. In other embodiments, vapor in the intermediate container 70 can be drawn into an intermediate stage of the compressor 32 (e.g., not the suction stage). Due to expansion in the expansion device 66 and / or the intermediate container 70, the enthalpy of the liquid collected in the intermediate container 70 can be lower than the enthalpy of the liquid working fluid leaving the condenser 34. The liquid from the intermediate container 70 can then flow through the second expansion device 36 in line 72 to the evaporator 38.

[0027] It should be understood that any features described herein can be combined with embodiments of the vapor compression system 14 or any other suitable HVAC&R system. For example, this technology can be combined with any HVAC&R system having an energy-saving device (such as intermediate container 70) and a compressor (such as compressor 32). The following discussion describes the technology of this application in combination with embodiments of the vapor compression system 14 having multiple compressors 32. For example, the vapor compression system 14 may include one compressor 32 as a low-pressure compressor or a first-stage compressor and another compressor 32 as a high-pressure compressor or a second-stage compressor. However, it should be understood that the technology described herein can be combined with other embodiments of the compressor 32, the vapor compression system 14, and the HVAC&R system 10.

[0028] Considering the foregoing, Figure 5This is a schematic diagram of an embodiment of a vapor compression system 14 (e.g., a freezer, a freezer system, a heat pump system) having a compressor system 100 (e.g., a multi-stage compressor system) according to various aspects of this disclosure. It should be understood that the compressor system 100 and / or its components can be implemented using any of the systems described above, according to the technology of this application. Furthermore, it should be understood that the compressor system 100 can be used in a system with constant-speed compressors. The compressor system 100 can be configured to operate according to a control algorithm (e.g., control logic, capacity control program) that causes the operation of the compressors of the compressor system 100 to switch between a first mode and a second mode to control the capacity of each compressor based on certain operating conditions of the vapor compression system 14 (e.g., based on the compressor's lift). In a first operating mode (e.g., PRV drive mode, low-lift mode), the PRV of each compressor can be adjusted or controlled to control the compressor's capacity, and the position of the VGD can be controlled independently of the PRV position. For example, the position of the VGD can be set based on a stall voltage detected by one or more sensors of the vapor compression system 14. In the second operating mode (e.g., VGD drive mode, high-lift mode), the VGD can be adjusted or controlled to control the compressor capacity, and the VGD position can be directly dependent on the PRV position. The controller can switch between each of the first and second operating modes discussed above based on a comparison of the compressor lift with high-lift and low-lift thresholds (e.g., each threshold can be based on certain design conditions of the compressor), as described in more detail below.

[0029] For example, when it is determined that the compressor lift in compressor system 100 is less than a low lift threshold, the controller can operate the compressor in a first operating mode, in which PRV is used to control the compressor capacity. When it is determined that the compressor lift is greater than a high lift threshold, the controller can operate the compressor in a second operating mode, in which VGD (e.g., in conjunction with PRV) is used to control the compressor capacity. When it is determined that the compressor lift is between the low and high lift thresholds, the controller can switch between the first and second operating modes, as discussed in more detail below. In this way, the lift limit can be achieved at low compressor flow rates while reducing or limiting the possibility of surge and / or stall conditions. Furthermore, the technology of this application can reduce energy consumption associated with the operation of vapor compression system 14 and improve its efficiency.

[0030] In the illustrated embodiment, the vapor compression system 14 is configured to direct working fluid (e.g., vapor refrigerant) from the evaporator 38 to the compressor system 100. The compressor system 100 includes a first compressor 102 (e.g., a low-pressure compressor, a first-stage compressor, a low-level compressor, a first compressor system) and a second compressor 104 (e.g., a high-pressure compressor, a second-stage compressor, a high-level compressor, a second compressor system). More specifically, the first compressor 102 and the second compressor 104 are arranged in series relative to the flow rate of working fluid through the compressor system 100. The compressor system 100 is configured to pressurize (e.g., increase in pressure) the working fluid to a desired pressure and direct the working fluid through the vapor compression system 14 (e.g., based on the cooling requirements of the vapor compression system 14). That is, the first compressor 102 may receive working fluid from the evaporator 38, pressurize the working fluid by a first amount (e.g., a first increase in pressure), and direct the working fluid to the second compressor 104. The second compressor 104 may further pressurize the working fluid by a second amount (e.g., a second lift) and discharge the working fluid toward the condenser 34 of the vapor compression system 14.

[0031] The first compressor 102 may include a pre-rotating vane (PRV) 106 (e.g., a PRV system) and a variable geometry diffuser (VGD) 108. As will be understood, the PRV 106 may be an adjustable guide vane disposed at or near the inlet (e.g., suction side) of the first compressor 102 and configured to control and / or regulate the flow rate of the working fluid entering the first compressor 102 (e.g., by causing swirl or movement of the working fluid). For example, the PRV 106 may be adjustable between a fully closed position and a fully open position to control the capacity (e.g., compressor stage capacity) of the first compressor 102 (e.g., a first compressor stage). The VGD 108 may be configured to adjust the size of the diffuser clearance or passage of the first compressor 102 (e.g., downstream of the impeller of the first compressor 102) to regulate and / or control the flow rate of the working fluid through the first compressor 102. Similar to PRV 106, VGD 108 of compressor 102 is adjustable between a fully closed position and an upper limit open position (e.g., the maximum permissible open position) to control the capacity of the first compressor 102. This allows for adjustment of the operation of PRV 106 and / or VGD 108 to control the operation of vapor compression system 14 (e.g., based on the load demand or cooling load of vapor compression system 14) and / or prevent stalling and / or surge in the first compressor 102.

[0032] The second compressor 104 may also include a pre-rotating vane (PRV) 110 (e.g., a PRV system) and a variable geometry diffuser (VGD) 112. As will be understood, the PRV 110 may be adjustable guide vanes located at or near the inlet (e.g., suction side) of the second compressor 104 and configured to control and / or regulate the flow rate of the working fluid entering the compressor 104 (e.g., by inducing swirling or vortex motion of the working fluid). For example, the PRV 110 may be adjustable between a fully closed position and a fully open position to control the capacity (e.g., compressor stage capacity) of the second compressor 104 (e.g., a second compressor stage). The VGD 112 may be configured to adjust the size of the diffuser passage or clearance of the second compressor 104 (e.g., downstream of the impeller of the second compressor 104) to regulate and / or control the flow rate of the working fluid through the second compressor. Similar to PRV 106, VGD 108 of compressor 102 is adjustable between a fully closed position and an upper limit open position (e.g., maximum permissible open position) to control the capacity of the first compressor 102. This allows the operation of PRV 110 and / or VGD 112 to be adjusted to control the operation of vapor compression system 14 (e.g., based on the load demand or cooling load of vapor compression system 14) and / or prevent stall and / or surge in the second compressor 104.

[0033] Compressor system 100 includes motor system 114 (e.g., one or more motors) configured to drive the rotation of first compressor 102 and second compressor 104. In some embodiments, each of compressors 102, 104 may correspond to a fixed-speed motor, such that each of compressors 102, 104 is configured to operate at a fixed speed to meet the load requirements on vapor compression system 14. For example, the motor of motor system 114 may be coupled to a fixed-speed drive or may be powered directly from an alternating current (AC) or direct current (DC) power source. If a fixed-speed drive is used, it receives AC power from an AC power source with a specific fixed line voltage and fixed line frequency, and provides power with a constant voltage and frequency to the motor of motor system 114. Motor system 114 may include any type of motor that can be powered by a fixed-speed drive or directly from an AC or DC power source. The motor of motor system 114 may be any other suitable motor type, such as a switched reluctance motor, induction motor, or electronically commutated permanent magnet motor. The speed of each of compressors 102, 104 may be based on design operating conditions and / or expected operating conditions. For example, the speed of the first compressor 102 or the second compressor 104 can be set to operate the respective compressor 102, 104 at a frequency lower limit corresponding to the desired lift, while avoiding stall and / or surge conditions. Furthermore, depending on the relevant lift requirements of each compressor 102, 104, each of the compressors 102, 104 can operate at the same speed or at different speeds.

[0034] In some embodiments, the vapor compression system 14 may include a hot gas bypass valve 116. In the illustrated embodiment, the hot gas bypass valve 116 is configured to direct compressed working fluid from the discharge outlet of the second compressor 104 to the suction inlet of the first compressor 102. However, in some embodiments, the hot gas bypass valve 116 may be configured to direct compressed working fluid from the discharge outlet of the second compressor 104 to a location downstream of the expansion valve 36 and upstream of the evaporator 38 (e.g., along the loop of the vapor compression system 14). Additionally, in some embodiments, the hot gas bypass valve 116 may be configured to direct compressed working fluid from the discharge outlet of the first compressor 102 to the suction inlet of the first compressor 102, or from the discharge outlet of the second compressor 104 to the suction inlet of the second compressor 104. Furthermore, as discussed in more detail below, PRV 106, 110, VGD 108, 112, and hot gas bypass valve 116 can be operated or controlled to regulate the flow rate and / or differential pressure (e.g., lift, head) of the working fluid guided through the compressor system 100 (e.g., based on the load or cooling requirements of the vapor compression system 14).

[0035] In some embodiments, each of compressors 102, 104 (e.g., each of compressor stages) may include a stall detector 118 (e.g., a stall voltage detection circuit). The stall detector 118 may be a stall pressure transducer located at a respective outlet of the first compressor 102 and / or the second compressor 104. For example, stall detector 118A may be configured to detect (e.g., sense, measure, record) pressure pulsations at the outlet of the first compressor 102, and stall detector 118B may be configured to detect pressure pulsations at the outlet of the second compressor 104. Each of stall detectors 118A, 118B may then output a stall voltage signal (e.g., a DC stall voltage signal) to controller 120. The stall voltage signal may indicate the magnitude of stall noise present at compressors 102, 104. In some embodiments, the positions of VGDs 108, 112 of each compressor 102, 104 may be adjusted individually to control (e.g., reduce, suppress, or eliminate) stall noise. For example, when a stall voltage signal detected by stall detector 118A is greater than a threshold, controller 120 may begin adjusting the position of VGD 108 of the first compressor 102 from the maximum permissible open position to the fully closed position until stall noise is suppressed. Once stall noise is suppressed, VGD 108 remains in the same position for a predetermined amount of time (e.g., a preset waiting period). After the predetermined amount of time has elapsed, controller 120 may adjust the position of VGD 108 toward the maximum permissible open position (e.g., pulsed, discrete steps, or incrementally) until stall noise is detected again, or the maximum permissible open position is reached.

[0036] As described above, the vapor compression system 14 directs the working fluid discharged from the compressor system 100 to the condenser 34. The condenser 34 is configured to transfer heat (e.g., thermal energy) from the working fluid to a regulating or cooling fluid (e.g., water, air) to cool and / or cool the working fluid. The working fluid is then directed through the expansion valve 36 and to the evaporator 38. The evaporator 38 may be fluidly coupled to a cooling load (e.g., cooling load 62), and the evaporator 38 may transfer heat (e.g., thermal energy) from the cooling load (e.g., cooling fluid, water) to the working fluid, thereby heating the working fluid and cooling the cooling load. For example, the evaporator 38 may allow the working fluid to exchange heat with a cooling fluid (e.g., water) that circulates through the cooling load to provide cooling. However, it should be understood that embodiments of this disclosure also include the vapor compression system 14 as a heat pump (e.g., a refrigerator heat pump), which is configured to operate to provide heating to the load.

[0037] As described above, in some embodiments, components of the compressor system 100 and / or the vapor compression system 14 may be controlled by a controller 120 (e.g., a control system, an automation controller), which may correspond to... Figure 3 and Figure 4 Control panel 40 of, or any other suitable controller (e.g., compressor controller). For example, controller 120 may include interface board 122, processing circuitry 124 (e.g., one or more microprocessors), memory 126, analog-to-digital (A / D) converter 128, and stall voltage detection board 129. The A / D converter 128 may be configured to receive input signals indicative of the performance of the vapor compression system 14 from various components of the vapor compression system 14. For example, input signals received by controller 120 may include: the temperature of the cooled liquid (e.g., regulating fluid) exiting evaporator 38, the working fluid pressure in evaporator 38 and condenser 34, acoustic or sound pressure measurements in the discharge passages of compressors 102, 104, the saturation temperature at the suction inlet and discharge outlet of compressors 102, 104, and / or the pressure at the suction inlet of compressors 102, 104.

[0038] The stall voltage detection board 129 can be configured to receive DC stall voltage signals from stall detectors 118A and 118B of compressors 102 and 104, respectively. The stall voltage detection board 129 can be further configured to convert the DC stall voltage signal into an AC stall voltage signal. The AC stall voltage signal can further represent the stall noise amplitude experienced by the compressors (e.g., compressors 102 and 104). The stall voltage detection board 129 can be further connected to the controller 120 to transmit the AC stall voltage signal.

[0039] Memory 126 may include volatile memory (such as random access memory (RAM)) and / or non-volatile memory (such as read-only memory (ROM), optical drive, hard disk drive, solid-state drive, or any other non-transient computer-readable medium for storing instructions (e.g., control algorithms) that, when executed, control the operation of compressor system 100 and / or vapor compression system 14. For example, controller 120 may utilize (e.g., executed via processing circuitry 124) various control algorithms (e.g., stored in memory 126) to determine when to adjust the positions of PRV 106, 110 and / or VGD 108, 112 in response to specific compressor adjustments, thereby maintaining the desired capacity of each of compressors 102, 104. Furthermore, controller 120 may use control algorithms to determine when to adjust the positions of VGD 108, 112 to reduce or suppress stall noise (e.g., stall noise reduction control). Even further, controller 120 may use control algorithms to control the position of hot gas bypass valve 116 in response to specific compressor conditions, thereby maintaining system and compressor stability. Memory 126 may be further configured to store various thresholds required to maintain system efficiency and stability, as discussed in more detail below. Processing circuitry system 124 may be configured to execute such instructions. In some embodiments, processing circuitry 124 may include one or more application-specific integrated circuits (ASICs), one or more field-programmable gate arrays (FPGAs), one or more general-purpose processors, or any combination thereof.

[0040] Controller 120 is configured to control the operation of compressor system 100 (e.g., control the operation of one or more components of compressor system 100, control the operation of one or more components of vapor compression system 14) to enable vapor compression system 14 to operate more efficiently. Specifically, controller 120 is configured to coordinate the operation of a first compressor 102 and a second compressor 104, each of which may include one or more capacity regulating components (e.g., PRV 106, 110, VGD 108, 112) to achieve more efficient operation of compressor system 100 (e.g., operation at isentropic efficiency). In some embodiments, controller 120 may be configured to control the operation of compressor system 100 to achieve a desired lift for each of compressors 102, 104 while limiting surge and / or stall in compressor system 100. For example, controller 120 may be configured to switch the operation of each of compressors 102, 104 between a first mode (e.g., PRV drive mode, low lift mode) and a second mode (e.g., VGD drive mode, high lift mode) based on a comparison between the lift on each compressor 102, 104 and one or more lift thresholds (e.g., high lift threshold, low lift threshold), as described in more detail below. To this end, controller 120 may be configured to output control signals to control the operation (e.g., corresponding positions) of PRVs 106, 110, the operation (e.g., respective positions) of VGDs 108, 112, the operation of motor system 114, and / or the operation (e.g., position) of hot gas bypass valve 116. In some embodiments, controller 120 may adjust the operation of one or more components of compressor system 100 based on the operating conditions of vapor compression system 14, and / or the load on vapor compression system 14 (e.g., the corresponding load on each of compressors 102, 104) or other suitable data.

[0041] In some embodiments, controller 120 may be configured to control the operation of compressor system 100 based on feedback received from one or more sensors 130 of vapor compression system 14. Sensors 130 may be configured to detect one or more operating conditions (e.g., operating parameters) of vapor compression system 14 and provide feedback to controller 120 indicating these operating conditions. Sensors 130 may include any suitable sensors configured to detect operating parameters of vapor compression system 14 and / or compressor system 100, such as pressure sensors, temperature sensors, position sensors, voltage sensors, current sensors, flow rate sensors, speed sensors, etc. In the illustrated embodiments, one or more sensors 130 are located at a respective inlet (e.g., suction side) of each of compressors 102, 104, a respective outlet (e.g., discharge side) of compressors 102, 104, an outlet of condenser 34 (e.g., working fluid outlet, cooling fluid outlet), and / or an outlet of evaporator 38 (e.g., working fluid outlet, cooling fluid outlet). However, other embodiments of the vapor compression system 14 may include a sensor 130 located at additional or alternative locations along the vapor compression system 14 (e.g., a vapor compression loop) and / or within the compressor system 100.

[0042] Sensor 130 may be configured to collect (e.g., measure, detect) data related to the working fluid, the cooling or regulating fluid circulated by evaporator 38, and / or the cooling or regulating fluid circulated by condenser 34. For example, one or more sensors 130 may detect the temperature, pressure, flow rate, or other operating parameters of the working fluid, regulating fluid, or cooling fluid. Further, one or more sensors 130 may be associated with PRV 106, 110, VGD 108, 112, and / or hot gas bypass valve 116. For example, sensor 130 may be configured to detect and transmit data indicating the position of PRV 106, 110, VGD 108, 112, and / or hot gas bypass valve 116. Vapor compression system 14 may also include one or more sensors 130 associated with motor system 114 (e.g., each motor of motor system 114) and may be configured to detect and transmit data indicating corresponding operating parameters of motor system 114. It should be noted that vapor compression system 14 may include more than Figure 5 The sensors shown are fewer or more sensors 130, and additional or alternative sensors 130 may be configured to detect one or more operating parameters and transmit data indicating the operating parameters to the controller 120 for operation of other components of the compressor system 100 and / or the vapor compression system 14.

[0043] As discussed above, PRVs 106, 110 and VGDs 108, 112 can operate as flow reduction devices (FRDs) configured to control or otherwise regulate the flow rate of working fluid through the respective compressors (e.g., compressors 102, 104). One or more of PRVs 106, 110 and VGDs 108, 112 can be coupled to a corresponding actuator, each of which can be communicatively connected to controller 120. The actuators can be configured to operate based on control signals received from controller 120. For example, the actuators can be operated to adjust the respective positions of PRVs 106, 110 and / or VGDs 108, 112. Depending on the operating mode of each of compressors 102, 104, controller 120 can instruct one or more actuators to adjust one or more of PRVs 106, 110 toward the open position, and / or adjust one or more of VGDs 108, 112 toward the open position. In this way, controller 120 can control compressor system 100 to increase the flow rate of working fluid through compressor system 100, thereby increasing the capacity (e.g., operating capacity) of vapor compression system 14. Similarly, controller 120 can instruct one or more actuators to adjust one or more of PRV 106, 110 toward the off position, and / or adjust one or more of VGD 108, 112 toward the off position to reduce the flow rate of working fluid through compressor system 100, thereby reducing the capacity of vapor compression system 14.

[0044] In some embodiments, the controller 120 may execute a capacity control program or algorithm to switch the operation of each compressor 102, 104 between a first operating mode and a second operating mode based on a comparison between the lift at each compressor 102, 104 and one or more lift thresholds, thereby meeting the load demand of each compressor 102, 104. When the capacity control program is executed, the controller 120 may automatically operate the compressors 102, 104 in either the first or second mode to control the capacity at the respective compressor 102, 104 based on the lift of each compressor 102, 104. Furthermore, the capacity control program may further prompt the controller 120 to determine the desired location to achieve the desired capacity of PRV 106, 110 and / or VGD 108, 112. After determining the appropriate mode based on the lift, and after determining the desired position of each flow reduction device (e.g., PRV 106, 110, VGD 108, 112), controller 120 can be configured to transmit control signals to PRV 106, 110 and / or VGD 108, 112 (e.g., via interface 122) to adjust the position of PRV 106, 110 and / or VGD 108, 112. For example, when the lift on a particular compressor 102, 104 is less than a low lift threshold, controller 120 can operate compressor 102, 104 in a first mode in which the capacity of compressor 102, 104 is controlled independently of the position of VGD 108, 112 using the PRV 106, 110 of each of compressors 102, 104.

[0045] When the lift on a particular compressor 102, 104 exceeds a high lift threshold, controller 120 can operate compressors 102, 104 in a second mode, in which VGD is used to control the compressor capacity. Therefore, in the second mode, the VGD position depends on (e.g., directly depends on) the PRV position of the corresponding compressor 102, 104. If the lift on a particular compressor 102, 104 is between a low lift threshold and a high lift threshold, controller 120 can switch between a first mode and a second mode to achieve the desired cooling capacity, as discussed in more detail below. It should be understood that controller 120 can be configured to use continuous feedback from sensor 130 to monitor changes in the system cooling load, which monitors various operating parameters of the vapor compression system 14. For example, controller 120 can be configured to change the position of at least one of the PRVs 106, 110 and / or VGDs 108, 112 of each of compressors 102, 104 to maintain the required capacity to meet the updated cooling load. In other words, when the load demand on the vapor compression system 14 increases, the operating parameters of compressors 102 and 104 are updated and / or modified accordingly to meet the new cooling capacity requirements. Furthermore, the controller 120 can continuously monitor the compressor lift (e.g., working fluid system differential pressure) of each of compressors 102 and 104 to increase the volumetric flow rate (e.g., capacity) of the working fluid in the vapor compression system 14 and maximize the final efficiency of compressors 102 and 104. Furthermore, although in Figure 5 The illustrated embodiments show two compressors (e.g., compressor stages), and it should be understood that the embodiments discussed herein may include more or fewer compressor stages. That is, this disclosure relates to a vapor compression system having any number (e.g., one, two, three, four, five, six or more) of compressors or compression stages.

[0046] As will be understood, the operation and performance of compressors 102, 104 can be represented and / or defined based on head coefficient (Ω) and flow coefficient (θ). The head coefficient typically indicates the pressure ratio or differential between the discharge pressure and suction pressure of compressors 102, 104, and the flow coefficient typically indicates the velocity (e.g., mass flow rate) of the fluid directed through compressors 102, 104. During operation at a specific speed (e.g., rotational speed), the operating point of compressors 102, 104 can typically be represented by corresponding head coefficient and flow coefficient values ​​associated with the compressors 102, 104 at that specific speed. In fact, at that specific operating speed, each compressor 102, 104 can be configured to operate at multiple operating points, each explicitly defined by a specific corresponding head coefficient and flow coefficient value. The respective corresponding head coefficient and flow coefficient values ​​associated with compressors 102, 104 can be based on the specific design characteristics of compressors 102, 104. Furthermore, the compressor operating point can be adjusted and / or achieved via the operation adjustment of compressors 102 and 104. For example, since compressors 102 and 104 are constant-speed compressors, the positions of PRV 106 and 110 and / or VGD 108 and 112 can be adjusted to adjust and / or achieve specific operating points of compressors 102 and 104 (e.g., corresponding head coefficient values ​​and flow coefficient values, achieving specific capacities, achieving specific lift). However, it is desirable to avoid compressors 102 and 104 operating at certain head coefficient and / or flow coefficient values ​​to avoid undesirable operating conditions or events, such as surge.

[0047] For example, compressor operating efficiency can be improved by operating the compressor at the lowest possible speed while avoiding surge. Therefore, a compressor with a specific speed can be selected based on specific design conditions. In some embodiments, the minimum rotational speed and / or minimum frequency at which the compressor can operate without surge can be calculated according to the techniques described in U.S. Patent Nos. 10,184,482 and EP2751430, the entire contents of which are incorporated herein by reference, or any other suitable technique may be used for calculation. Controller 120 can then be configured to adjust the positions of PRV 106, 110 and / or VGD 108, 112 to achieve the desired capacity. That is, controller 120 can operate each of compressors 102, 104 in a manner that satisfies the load or demand of vapor compression system 14 while avoiding surge and improving the overall operating efficiency of vapor compression system 14. Furthermore, the techniques of this application can perform the above operations in compressor systems with multi-stage compression (e.g., two-stage, three-stage, four-stage, five-stage, or multi-stage compression).

[0048] In operation, controller 120 can be configured to execute a capacity control program to control the capacity of each of compressors 102 and 104, thereby controlling the capacity of compressor system 100. For simplicity, the capacity control program is described in the context of the control operation of the first compressor 102. However, it should be understood that the same capacity control algorithm can be applied to control the capacity of the second compressor 104 without departing from the scope of this disclosure. Furthermore, it should be understood that the same capacity control algorithm can be used to control the capacity of a compressor system having a single-stage compressor.

[0049] According to the capacity control program, controller 120 can be configured to determine the compressor lift (e.g., compressor stage lift) of compressor 102. A higher lift value may correspond to an increase in the amount of work performed by the corresponding compressor. In some embodiments, controller 120 may base its determination on the actual head coefficient Ω of compressor 102 and the maximum head coefficient Ω of compressor 102. 喘振 The compressor lift is determined by the ratio of the pressure head (Ω) and the flow rate (θ). For example, as mentioned above, the operating point of compressor 102 can be defined based on the head coefficient (Ω) and the flow rate coefficient (θ). It is generally desirable to maintain the operating point within the operating limits of compressor 102, for example, without stall or surge. Furthermore, compressor 102 must not exceed the maximum head coefficient Ω. 喘振 Without entering surge. For a single compressor, or for a specific compressor stage in the case of a multi-stage compressor, the maximum head coefficient Ω can be obtained by plotting the relationship between the head coefficient (Ω) and the flow coefficient (θ) (e.g., a compressor characteristic curve). 喘振 Typically, at a given impeller speed, the head coefficient (Ω) increases as the flow coefficient (θ) decreases. The flow coefficient (θ) can be reduced by shutting off flow reduction devices used in the compressor stage (e.g., PRV 106, 110, VGD 108, 112). Maximum head coefficient Ω 喘振 The head coefficient value corresponds to the point where the speed curve and surge curve intersect at a given impeller speed. The surge curve can be plotted in the diagram as a surge point model provided by the compressor manufacturer. Controller 120 can be configured to determine the maximum head coefficient Ω of compressor 102 using the compressor diagram plotted for compressor 102. 喘振 .

[0050] The controller 120 may be further configured to process sensor readings received from the sensor 130 to determine the actual head coefficient Ω of the compressor 102. In some embodiments, the controller 120 may use Equation 1 shown below to determine the actual head coefficient Ω of the compressor 102: In Equation 1 above, Ω refers to the actual head coefficient Ω of compressor 102, and d His This refers to the isentropic difference between the suction and discharge of compressor 102, and It refers to the speed of sound.

[0051] Based on sensor data received from various sensors 130 arranged at the suction inlet and discharge outlet of compressor 102, controller 120 can determine the isentropic difference (i.e., d). H is In some embodiments, the controller 120 may determine the compressor lift of the compressor 102 based on the pressure ratio of the discharge pressure to the suction pressure of the compressor 102, the saturation temperature difference between the saturation discharge temperature and the saturation suction temperature of the compressor 102, the pressure difference between the discharge pressure and the suction pressure of the compressor 102, etc.

[0052] After determining the compressor lift of compressor 102, controller 120 can compare the determined compressor lift with a low lift threshold and a high lift threshold of compressor 102. The low lift threshold and high lift threshold of compressor 102 can be stored in memory 126. In some embodiments, the low lift threshold and high lift threshold can be determined by an operator using user interface 122. In an exemplary embodiment, the low lift threshold of compressor 102 can be set to 0.8, and the high lift threshold of compressor 102 can be set to 0.9. It should be understood that the above examples are for illustrative purposes and do not limit the scope of this disclosure in any way. For example, the low lift threshold and high lift threshold can vary for different applications of the vapor compression system 14, and can also vary for different compressor stages in a multi-stage compressor. Based on this comparison, controller 120 can be configured to operate compressor 102 in a first mode (e.g., PRV drive mode, low lift mode) and a second mode (VGD drive mode, high lift mode) to control the capacity of the first compressor 102, as described in more detail below.

[0053] For example, based on the comparison results, controller 120 can determine that the compressor lift of the first compressor 102 is less than the low lift threshold of the first compressor 102. As a result, controller 120 can operate compressor 102 in a first mode to control the capacity of the first compressor 102. For example, the compressor lift of the first compressor 102 can be determined to be 0.68, which is less than the low lift threshold of 0.8. Therefore, controller 120 can operate compressor 102 in the first mode, wherein PRV 106 operating the first compressor 102 is used to adjust the capacity of the first compressor 102, while VGD 108 is operated to suppress (e.g., eliminate) stall noise. Therefore, in the first mode, the position of VGD 108 can be independent of the position of PRV 106 in the first mode.

[0054] In some embodiments, controller 120 may be configured to receive sensor readings from sensor 130 that monitors the position of PRV 106. When controller 120 operates compressor 102 in a first mode, to reduce the capacity of compressor 102, controller 120 may transmit an actuation signal to the actuator of PRV 106. The actuation signal may cause the actuator to gradually drive PRV 106 from its current position toward a fully closed position. The current position may correspond to a fully open position or a partially closed position. Therefore, the actuator may gradually or incrementally close PRV 106 based on the actuation signal until a desired capacity is achieved or a desired position is reached. When controller 120 operates compressor 102 in a first mode, to increase the capacity of compressor 102, controller 120 may transmit an actuation signal to the actuator of PRV 106. The actuation signal may cause the actuator to gradually drive PRV 106 from its current position toward a fully open position. The current position may correspond to a fully closed position or a partially open position. Therefore, the actuator can gradually or incrementally open the PRV 106 based on the actuation signal until the desired capacity is achieved or the fully open position is reached. That is, in the first mode, in response to the compressor lift of the first compressor 102 being less than the low lift threshold, the controller 120 can change (e.g., adjust) the position of the PRV 106 of the first compressor 102 between the fully open position and the fully closed position to control the capacity of the first compressor 102.

[0055] When controller 120 operates compressor 102 in a first mode (e.g., when controller 120 adjusts the capacity of compressor 102 using PRV 106), controller 120 (e.g., stall voltage detection board 129) can receive a stall voltage signal from stall detector 118A of the first compressor 102. The stall voltage signal can indicate the magnitude of stall noise detected by stall detector 118A in the first compressor 102. Controller 120 can be configured to compare the stall voltage signal with stall voltage thresholds stored in memory 126. Stall voltage thresholds can indicate an acceptable range of stall noise in the first compressor 102. For example, stall voltage thresholds can include a low stall voltage threshold and a high stall voltage threshold. If the stall noise magnitude indicated by the stall voltage signal is less than the low stall voltage threshold or greater than the high stall voltage threshold, the stall noise can be considered unacceptable. Therefore, based on the determination that stall noise is unacceptable (e.g., when the stall noise amplitude indicated by the stall voltage signal is determined to be less than a low stall voltage threshold or greater than a high stall voltage threshold), controller 120 may transmit an actuation signal to the actuator of VGD 108. The actuation signal may cause the actuator to gradually drive VGD 108 from the maximum permissible open position toward the closed position. For example, the actuator may, based on the actuation signal, gradually or incrementally close VGD 108 until the stall noise is corrected or VGD 108 reaches the fully closed position.

[0056] Once the stall noise is corrected, the controller 120 can send a stop signal to the actuator of the VGD 108, causing the actuator to stop shutting down the VGD 108 and maintain its current position for a preset waiting time. Once the preset waiting time has elapsed, the controller 120 can send an actuation signal to the actuator of the VGD 108 to gradually (incrementally, stepwise) open the VGD 108. Based on the actuation signal, the actuator can gradually or incrementally open the VGD 108 until stall noise is detected again or the maximum permissible opening position is reached. In some embodiments, the maximum permissible opening position of the VGD 108 refers to a position beyond which continued operation of the VGD 108 may cause surge. Therefore, in some embodiments, the maximum permissible opening position may be a fully open position or a partially closed position. In some embodiments, when controller 120 operates compressor 102 in a first mode (e.g., when controller 120 uses PRV 106 to control the capacity of compressor 102 independently of VGD 108, when the compressor lift of compressor 102 is less than a low lift threshold), controller 120 may be configured to set the fully open position to the maximum permissible open position. Controller 120 may be configured to repeatedly execute the aforementioned control loop of controlling the position of VGD 108 between the fully closed position and the maximum permissible open position based on a stall voltage signal, thereby maintaining the operation of the first compressor 102 while limiting stall noise and surge.

[0057] Therefore, in the first mode, the positions of the PRVs 106 and 110 of each compressor 102, 104 are adjusted to control the corresponding compressor capacity, and the positions of the VGDs 108 and 112 of each compressor 102, 104 are adjusted to reduce, suppress, and / or eliminate stall noise in the corresponding compressor 102, 104. For example, when capacity control is performed on each of the compressors 102, 104, changes in the positions of the PRVs 106 and 110 do not cause any changes in the positions of the VGDs 108 and 112. In other words, when the controller 120 operates the compressors 102, 104 in the first mode, changes in the positions of the VGDs 108 and 112 are independent of the positions of the PRVs 106 and 110 associated with the compressors 102, 104, respectively.

[0058] In some embodiments, controller 120 may determine that the compressor lift of the first compressor 102 is greater than a high lift threshold of the first compressor 102. As a result, controller 120 may operate compressor 102 in a second mode to control the capacity of compressor 102. For example, the compressor lift of the first compressor 102 may be determined to be 0.92, which is greater than the high lift threshold of 0.9. Therefore, controller 120 may operate compressor 102 in a second mode in which both PRV 106 and VGD 108 are operated to adjust the capacity of the first compressor 102. Thus, in the second mode, the position of VGD 108 may depend on the position of PRV 106, as discussed in more detail below.

[0059] In the second mode, the controller 120 can be configured to update or adjust the maximum permissible opening position of the VGD 108 based on the changing position of the PRV 106 to control the capacity of the compressor 102. That is, the VGD 108 and PRV 106 can be used together to control the capacity of the first compressor 102, and the controller 120 can set the maximum permissible opening position of the VGD 108 based on the correlation between the position of the PRV 106 and the maximum permissible opening position of the VGD 108. For example, if the current position of the PRV 106 is in the range of 0% open (e.g., fully closed) to 50% open, the maximum permissible opening position of the VGD 108 can be set to the fully closed position. When the PRV 106 is open beyond 50%, the current position of the PRV 106 can have a linear relationship with the maximum permissible opening position of the VGD 108. Therefore, the maximum permissible opening position of the VGD 108 can vary within the range of fully closed to fully open based on the current position of the PRV 106.

[0060] For example, such as Figure 6 This is a schematic diagram 200 illustrating the correlation between the current position of the PRV and the corresponding maximum permissible opening position of the VGD associated with the compressor. For example, schematic diagram 200 may correspond to the current position of the PRV 106 and the corresponding maximum permissible opening position of the VGD 108 associated with the compressor 102. Schematic diagram 200 is plotted with the Y-axis representing the maximum permissible opening position of the VGD (%VGD maximum) and the X-axis representing the current percentage opening position of the PRV (%PRV). Line 202 corresponds to the maximum permissible opening position of the VGD when the compressor lift (or compressor stage) is determined to be less than the compressor's low lift threshold. For example, as described above, when the compressor lift on the compressor is less than the compressor's low lift threshold, the controller 120 may set the maximum possible opening position (e.g., 100%, fully open position) to the maximum permissible opening position. Therefore, plotted line 202 corresponds to the operation of the compressor in a first mode. Figure 6As shown, during operation in the first mode, the maximum permissible opening position of VGD is independent of the position of PRV.

[0061] Line 204 corresponds to the maximum permissible opening position of the VGD when the compressor lift is determined to be greater than the compressor's high lift threshold. For example, as described above, when the compressor lift on the compressor is greater than the compressor's high lift threshold, the controller 120 can set the maximum permissible opening position based on the position of the PRV. Therefore, line 204 corresponds to the operation of the compressor in the second mode. The controller 120 can further utilize line 204 while determining the % in Equation 2 described below. VGD maximum 允许 (% PRV )value.

[0062] Return to Figure 5 In some embodiments, controller 120 may receive sensor readings from sensor 130 that monitors the position of PRV 106 and VGD 108. When controller 120 operates compressor 102 in a second mode, in order to reduce the capacity of compressor 102, controller 120 may transmit an actuation signal to the actuator of PRV 106. The actuation signal may cause the actuator to gradually drive PRV 106 from its current position toward a fully closed position. Therefore, the actuator may gradually or incrementally close PRV 106 based on the actuation signal until the desired capacity is achieved or the desired position is reached. Further, in response to driving PRV 106 toward the fully closed position, controller 120 may be configured to reduce the maximum permissible open position of VGD 108 (e.g., based on the correlation between the changed position of PRV 106 and the maximum permissible open position of VGD 108). Figure 6 (As shown in the diagram). For example, controller 120 may transmit an actuation signal to the actuator of VGD 108 to gradually drive VGD 108 toward a desired position (e.g., the maximum permissible open position associated with the current position of PRV 106). Thus, based on the actuation signal, the actuator may gradually or incrementally close VGD 108 until the maximum permissible open position associated with the current position of PRV 106 is achieved. If the desired capacity is not reached, controller 120 may generate an actuation signal to further close the first-stage PRV 106, which in turn causes controller 120 to generate an actuation signal to further close VGD 108, bringing it to an updated maximum permissible open position based on the updated position of PRV 106.

[0063] When the controller 120 operates the compressor 102 in the second mode, in order to increase the capacity of the compressor 102, the controller 120 may transmit an actuation signal to the actuator of the PRV 106. The actuation signal may cause the actuator to drive the PRV 106 from its current position (e.g., gradually, incrementally) toward a fully open position. Therefore, the actuator may gradually or incrementally open the PRV 106 based on the actuation signal until the desired capacity is achieved or the desired position is reached. Furthermore, in response to driving the PRV 106 toward the fully open position, the controller 120 may be configured to increase the maximum permissible open position of the VGD 108 based on the correlation between the changed position of the PRV 106 and the maximum permissible open position of the VGD 108. For example, the controller 120 may transmit an actuation signal to the actuator of the VGD 108 to drive the VGD 108 toward a desired position (e.g., the maximum permissible open position associated with the current position of the PRV 106). Therefore, the actuator can gradually or incrementally open VGD 108 based on the actuation signal until the maximum permissible open position associated with the current position of PRV 106 is obtained.

[0064] It should be noted that when the controller 120 operates the compressor 102 in the second mode, the maximum permissible opening position of the VGD 108 can be further closed relative to the position required by the stall voltage. Therefore, stall noise suppression control (e.g., stall noise reduction control) can cause the actuator to drive the VGD 108 toward the maximum permissible opening position associated with the current position of the PRV 106. Based on the actuation signal and stall noise correction control, the actuator can gradually or incrementally open the VGD 108 until the maximum permissible opening position is reached. If the desired capacity is still not reached, the controller 120 can generate an actuation signal to further open the PRV 106, which in turn causes the controller 120 to generate an actuation signal to further open the VGD 108, bringing it to an updated maximum permissible opening position based on the updated position of the PRV 106. The controller 120 can continue to open the PRV 106 and VGD 108 until the desired capacity is achieved or until the position of the VGD 108 causes stall noise to occur.

[0065] Therefore, in the second mode, the positions of the PRVs 106 and 110 of each compressor 102 and 104, and the positions of the VGDs 108 and 112 of each compressor 102 and 104, are changed to control the corresponding compressor capacity, wherein the positions of the VGDs 108 and 112 are directly dependent on the current positions of the PRVs 106 and 110. That is, a change in the position of the PRVs 106 and 110 may cause a change in the position of the VGDs 108 and 112. In other words, when the controller 120 operates the compressors 102 and 104 in the second mode, the positions of the VGDs 108 and 112 change based on the positions of the PRVs 106 and 110. Furthermore, it should be understood that the operation of the compressors 102 and 104 in the second mode may cause the VGDs 108 and 112 of the corresponding compressors 102 and 104 to be more closed relative to the operation of the compressors 102 and 104 in the first mode, and / or relative to the opening required to suppress stall noise. Therefore, in some embodiments, the operation of compressors 102 and 104 in the second mode can suppress stall noise by default.

[0066] In some embodiments, the controller 120 may determine that the compressor lift of the first compressor 102 is between a low lift threshold and a high lift threshold. As a result, the controller 120 may switch the operation of the compressor 102 between a first mode and a second mode to control the capacity of the first compressor 102. For example, in an embodiment where the compressor lift increases in the direction toward a high lift threshold, the controller 120 may be configured to switch the operation of the compressor 102 in the first mode to the operation of the compressor 102 in the second mode to control the capacity of the compressor 102. Conversely, in an embodiment where the compressor lift decreases in the direction toward a low lift threshold, the controller 120 may be configured to switch the operation of the compressor 102 in the second mode to the operation of the compressor 102 in the first mode to control the capacity of the compressor 102.

[0067] As an example, the compressor lift of the first compressor 102 can be determined to be 0.82, which is greater than the low lift threshold of 0.8 but less than the high lift threshold of 0.9. Therefore, the controller 120 can utilize PRV 106 and VGD 108 to regulate the capacity of the compressor 102. For example, when the compressor lift moves from the low lift threshold to the high lift threshold, the controller 120 can be configured to control the compressor 102 such that the contribution of VGD 108 to capacity control increases, while the contribution of PRV 106 to capacity control decreases. Conversely, when the compressor lift moves from the high lift threshold to the low lift threshold, the controller 120 can be configured to control the compressor 102 such that the contribution of VGD 108 to capacity control decreases, while the contribution of PRV 106 to capacity control increases.

[0068] To switch between the first and second modes, controller 120 can be configured to update, adjust, or modify the maximum permissible opening position of VGD 108 based on the changing position of PRV 106. In some embodiments, controller 120 may use Equation 2 shown below to determine the maximum permissible opening position of VGD 108: (2) In equation 2 above, % VGD maximum 允许 This refers to the maximum permissible opening position of VGD 108, Ω. 喘振 This refers to the maximum head factor of the first compressor 102, Ω refers to the actual head coefficient of the first compressor 102, and % VGD's most big 允许 (% PRV This refers to the position of PRV 106 and the maximum permissible opening position of VGD 108 when the controller 120 operates the compressor 102 in the second mode (e.g., as shown in the image). Figure 6 The correlation between (as described in) (e.g., when the lift of compressor 102 is greater than the high lift threshold).

[0069] According to Equation 2, based on the increase of compressor lift from a low lift threshold to a high lift threshold, controller 120 gradually decreases the maximum permissible opening position of VGD 108 from the possible maximum opening position (e.g., 100% open). Similarly, based on the decrease of compressor lift from a high lift threshold to a low lift threshold, controller 120 gradually increases the maximum permissible opening position of VGD 108 from the fully closed position (e.g., 0% open). As a result, by changing the current positions of PRV 106 and VGD 108 based on the relationship described in Equation 2, controller 120 is able to increase or decrease the capacity of the first compressor 102. For example, when PRV 106 is between 0% open and 50% open, the maximum permissible opening position of VGD 108 is set to 100% at compressor lift "0.80", 90% at compressor lift "0.81", 80% at compressor lift "0.82", 70% at compressor lift "0.83", and so on. Similarly, when PRV 106 is at 60% open, the maximum permissible opening position of VGD 108 is set to 100% at compressor lift "0.80", 92% at compressor lift "0.81", 84% at compressor lift "0.82", and so on.

[0070] Considering the preceding content, Figure 7A flowchart illustrating an embodiment of a method 300 (e.g., capacity control scheme, capacity control program, control logic) for controlling the operation of a compressor system 100 (e.g., controlling the operation of each of the compressors 102, 104 of the compressor system 100). Specifically, method 300 can be used to coordinate and / or control the operation of the first compressor 102 and the second compressor 104 and their respective components to meet the load (e.g., cooling capacity, heating capacity) of the vapor compression system 14 (e.g., operating the vapor compression system 14 at a desired capacity). For example, a controller 120 (e.g., a single controller, processing circuitry 124) may be configured to implement and / or execute method 300 to control the various components of the vapor compression system 14, and / or switch the operation of each of the compressors 102, 104 between a first mode and a second mode based on the lift requirements of the respective compressors 102, 104. In other embodiments, method 300 may be implemented by another controller (e.g., a dedicated controller for the compressor system 100), more than one controller, or other suitable control system. Furthermore, certain steps of the described method 300 may be removed, modified, and / or performed in a different order.

[0071] As described above, method 300 can be implemented to control the capacity (e.g., operating capacity) of the vapor compression system 14. In some embodiments, the outlet temperature of the evaporator 38 can be monitored and evaluated to determine the operating capacity (e.g., current operating capacity) of the vapor compression system 14. In other words, the outlet temperature of the evaporator 38 can represent the operating capacity of the vapor compression system 14. For example, the outlet temperature can be the temperature of the cooling fluid regulated and exiting the evaporator 38. However, in other embodiments, the outlet temperature can be the temperature of the working fluid exiting the evaporator 38. As will be understood, the outlet temperature can be measured or detected by one of the sensors 130 described above.

[0072] Although method 300 is shown as a series of steps, it should be understood that method 300 can be executed or implemented as a continuous or sequential control loop (e.g., a proportional-integral-derivative [PID] control loop) based on any suitable input, data, or feedback (e.g., feedback from sensor 130). That is, the steps of method 300 can be performed repeatedly (e.g., sequentially) to enable adjustment of the operating capacity of vapor compression system 14. In practice, method 300 can be performed continuously or sequentially to dynamically control components of vapor compression system 14 in real time (e.g., based on feedback provided by one or more sensors 130).

[0073] Method 300 begins at step block 302, where controller 120 calculates the head (e.g., actual head, work performed, head factor) for each of compressors 102, 104 (e.g., each compression stage of compressor system 100). In some embodiments, the head of each compressor 102, 104 can be calculated based on data indicating the working fluid temperature and / or pressure at the respective inlet and outlet of compressors 102, 104 (e.g., received from sensor 130), and / or based on data indicating the working fluid and / or cooling fluid temperature and / or pressure at condenser 34 and evaporator 38 (e.g., received from sensor 130). For example, the head of each compressor can be determined based on the saturation temperature at the suction inlet and the discharge outlet of compressors 102, 104. In some embodiments, the head of each compressor 102, 104 can be calculated according to the techniques described in EP2751430 (the entire contents of which are incorporated herein by reference) or using any other suitable techniques.

[0074] At step block 304, controller 120 determines the compressor lift based on the ratio of the actual head coefficient of compressors 102, 104 (e.g., as determined in step block 302) to the maximum head coefficient. In some embodiments, the maximum head coefficient may be based on designed operating conditions. At step block 306, controller 120 may compare the determined compressor lift associated with a particular compressor 102, 104 with a low lift threshold and a high lift threshold to generate a comparison result. As described above, the low lift threshold and the high lift threshold may be stored in memory 126.

[0075] At step 308, based on the comparison result generated in step 306, controller 120 can be configured to determine whether the compressor lift determined in step 304 is less than a low lift threshold. When it is determined that the compressor lift is less than the low lift threshold, method 300 can proceed to step 310, and controller 120 can operate compressors 102 and 104 in a first mode at step 310. Therefore, as described above, when the compressor lift is less than the low lift threshold, controller 120 can be configured to change the positions of PRV 106 and 110 to control the compressor capacity, and can control the positions of VGD 108 and 112 to reduce and / or suppress stall noise.

[0076] For example, when compressors 102 and 104 are selected to operate in the first mode, controller 120 can set the maximum possible opening position (e.g., 100%, fully open position) to the maximum permissible opening position of VGDs 108 and 112 at step block 312. The positions of VGDs 108 and 112 can then be changed to reduce, suppress, or eliminate stall noise (e.g., stall noise suppression control, stall noise reduction control), as referenced below. Figure 8 To describe in more detail.

[0077] At step block 314, controller 120 can change the positions of PRVs 106 and 110 from the fully open position to the fully closed position to control the capacity of compressors 102 and 104. For example, as described above, to reduce the capacity of compressors 102 and 104, controller 120 can send an actuation signal to the actuators of PRVs 106 and 110 to drive (e.g., progressively, incrementally) PRVs 106 and 110 from their current positions toward the fully closed position. Conversely, to increase the capacity of compressors 102 and 104, controller 120 can send an actuation signal to the actuators of PRVs 106 and 110 to drive PRVs 106 and 110 from their current positions toward the fully open position. By repeating steps 302 and 304, controller 120 can continue to determine and / or evaluate any changes in compressor lift. It should be noted that when the controller 120 operates the compressors 102 and 104 in the first mode, the positions of VGD 108 and 112 are independent of the changing positions of PRV 106 and 110.

[0078] At step block 308, if controller 120 determines that the compressor lift is not less than the low lift threshold, the method can proceed to step block 316, and controller 120 can determine whether the compressor lift is greater than the high lift threshold based on the comparison result generated in step block 306. When it is determined that the compressor lift is greater than the high lift threshold, method 300 can proceed to step block 318, and controller 120 can operate compressors 102 and 104 in a second mode at step block 318. Therefore, as described above, when the compressor lift is greater than the high lift threshold, controller 120 can be configured to change the positions of PRV 106 and 110 and VGD 108 and 112 to control the compressor capacity.

[0079] For example, when compressors 102 and 104 are selected to operate in the second mode, at step block 320, controller 120 can change the position of PRV 106 and 110 between a fully open position and a partially or fully closed position. Furthermore, in response to changing the position of PRV 106 and 110, at step block 322, controller 120 can determine the maximum permissible open position of VGD 108 and 112 based on the current position of PRV 106 and 110. That is, the maximum permissible open position of VGD 108 and 112 can be set based on the correlation between the current position of PRV 106 and 110 and the maximum permissible open position of VGD 108 and 112 (e.g., as...). Figure 6 (As shown by line 204 in the text).

[0080] At step block 324, controller 120 can change the positions of VGDs 108 and 112 to reach the set maximum allowable opening position determined by step block 322, thereby controlling the capacity of compressors 102 and 104. At step block 325, controller 120 can determine whether the desired capacity has been achieved. Figure 7 As shown, at step block 325, if controller 120 determines that the desired capacity has been achieved, controller 120 may continue to monitor compressor operation to determine any changes in compressor lift (e.g., by repeating steps 302 and 304). However, if at step block 325, controller 120 determines that the desired capacity has not been achieved, controller 120 may repeat steps 320, 322, and 324 until the desired capacity is achieved. Furthermore, by repeating steps 302 and 304, controller 120 may continue to monitor and / or detect any changes in compressor lift.

[0081] At step 316, if controller 120 determines that the compressor lift is not greater than the high lift threshold (e.g., if controller 120 determines that the compressor lift is between the low lift threshold and the high lift threshold), the method may proceed to step 326, and at step 326, controller 120 may switch the operation of compressors 102 and 104 between a first mode and a second mode to control the capacity of compressors 102 and 104.

[0082] For example, at step 328, when the compressor lift changes between a low lift threshold and a high lift threshold, controller 120 may decrease or increase the maximum permissible opening position of VGDs 108 and 112. As described above, in some embodiments, controller 120 may use Equation 2 to determine the maximum permissible opening position of VGDs 108 and 112 based on the current position of PRVs 106 and 110. For example, when the compressor lift moves from a low lift threshold to a high lift threshold, controller 120 may be configured to control compressors 102 and 104 such that the contribution of VGDs 108 and 112 to capacity control increases, while the contribution of PRVs 106 and 110 to capacity control decreases. Conversely, when the compressor lift moves from a high lift threshold to a low lift threshold, controller 120 may be configured to control compressors 102 and 104 such that the contribution of VGDs 108 and 112 to capacity control decreases, and the contribution of PRVs 106 and 110 to capacity control increases.

[0083] In step block 330, the positions of PRVs 106 and 110 and VGDs 108 and 112 are changed to achieve the desired capacity. It is worth noting that the positions of VGDs 108 and 112 are changed based on the current positions of PRVs 106 and 110 to obtain the maximum allowable open position.

[0084] Now for reference Figure 8A flowchart illustrating an embodiment of a method 400 for performing stall noise suppression control (e.g., a stall noise suppression control scheme, a stall noise program, or stall noise control logic) is shown. That is, method 400 can be used to minimize and / or reduce stall noise in compressors 102, 104. For example, controller 120 may be configured to implement and / or execute method 400 to control various components of vapor compression system 14 and / or compressor system 100. In other embodiments, method 400 may be implemented by another controller (e.g., a dedicated controller for compressor system 100), more than one controller, or other suitable control system.

[0085] Although method 400 is shown as a series of steps, it should be understood that method 400 can be performed or implemented as a continuous or ongoing control loop based on any suitable input, data, or feedback (e.g., feedback from sensor 130, feedback from stall detectors 118A, 118B). That is, the steps of method 400 can be performed repeatedly (e.g., sequentially) to minimize and / or reduce stall noise in compressors 102, 104. In practice, method 400 can be performed continuously or continuously to dynamically control the components of the vapor compression system 14 in real time.

[0086] Method 400 begins at step block 402, where controller 120 receives a stall voltage signal from stall detectors 118A, 118B, indicating the magnitude of stall noise in compressors 102, 104. Upon receiving the stall voltage signal, controller 120 may, at step block 404, compare the stall voltage signal with one or more stall voltage thresholds stored in memory 126. For example, controller 120 may compare the stall voltage signal with multiple stall voltage thresholds that provide an acceptable range of stall voltage signal values. For example, if the stall voltage signal transmitted to controller 120 by stall detectors 118A, 118B is outside the range of stall voltage thresholds, controller 120 may determine that the stall noise associated with the stall voltage signal is unacceptable.

[0087] If, at step block 404, controller 120 determines that the stall voltage signal is outside the range of the stall voltage threshold, the method may proceed to step block 406, and controller 120 may change the position of VGDs 108 and 112 between the maximum permissible open position and the fully closed position based on the stall voltage signal. For example, when it is determined that the stall voltage signal indicates unacceptable stall noise (e.g., when it is determined that the stall voltage signal is outside the range of the stall voltage threshold), controller 120 may transmit an actuation signal to the actuators of VGDs 108 and 112 to change the position of VGDs 108 and 112. For example, the actuators may gradually or incrementally close VGDs 108 and 112 based on the actuation signal until the stall noise is suppressed or VGDs 108 and 112 reach the fully closed position. In some embodiments, VGDs 108 and 112 may remain at the current position that suppresses stall noise for a preset waiting period. Once the waiting period ends, controller 120 can send an actuation signal to the actuators of VGD 108, 112 to gradually open VGD 108, 112 until stall noise is detected again or the maximum permissible opening position is reached. Controller 120 can be configured to repeat steps 402, 404 and 406 to reduce, suppress and / or eliminate stall noise and / or surge.

[0088] This disclosure provides one or more technical effects useful in the operation of HVAC&R systems. Specifically, the disclosed systems and methods employ a capacity control algorithm that enables the upper lift limit to be achieved at a lower flow rate in a constant-speed compressor while minimizing the occurrence of undesirable operating conditions such as stall and / or surge. Furthermore, the capacity control algorithm discussed herein can be applied to single-stage or multi-stage compressors for capacity control and enables simplified control techniques for systems with multi-stage compression and / or multiple capacity regulating components associated with each stage of compression. Moreover, the capacity control algorithm discussed herein enables the compressor system to operate efficiently, thereby reducing energy consumption associated with the operation of HVAC&R systems employing such compressor systems.

[0089] While only certain features and embodiments are shown and described, many modifications and alterations will occur to those skilled in the art without substantially departing from the novel teachings and advantages of the subject matter set forth in the claims, such as variations in the size, dimensions, structure, shape and proportions of various elements, parameter values ​​(such as temperature and pressure), installation arrangements, use of materials, color, orientation, etc. The order or sequence of any process or method steps may be altered or rearranged according to alternative embodiments. Therefore, it should be understood that the appended claims are intended to cover all such modifications and alterations as fall within the true spirit of this disclosure.

[0090] Furthermore, in the effort to provide a concise description of exemplary embodiments, not all features of actual implementations may be described, such as features unrelated to the currently anticipated optimal mode or features unrelated to enabling. It should be understood that, in the development of such actual implementations, as in any engineering or design project, many implementation-specific decisions can be made. Such development work may be complex and time-consuming, but for those skilled in the art who benefit from this disclosure, these are routine tasks of design, fabrication, and production without excessive experimentation.

[0091] The technical references presented and asserted herein are applied to tangible objects and specific examples of practical nature that arguably improve the technical field of the invention and are therefore not abstract, intangible, or purely theoretical. Furthermore, if any claim appended to this specification contains one or more elements expressed as "means for [performing] [function]..." or "steps for [performing] [function]...", it is intended that such elements be interpreted in accordance with 35 USC 112(f). However, for any claim containing elements specified in any other manner, it is intended that such elements not be interpreted in accordance with 35 USC 112(f).

Claims

1. A compressor system for a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system, the compressor system comprising: - one or more compressors configured to circulate a working fluid through a vapor compression system of the HVAC&R system, each of the one or more compressors including a pre-rotation vane and a variable geometry diffuser configured to operate to adjust a capacity of the compressor system; and - a controller including a memory and a processing circuit, wherein the memory includes instructions stored thereon that, when executed by the processing circuit, cause the processing circuit to: - determine a head coefficient for each of the one or more compressors; - determine a compressor lift for each of the one or more compressors based at least in part on the head coefficient; - compare the compressor lift for each of the one or more compressors to a low lift threshold and a high lift threshold; and - operate each of the one or more compressors in a first mode or a second mode based on the comparison of the compressor lift to the low lift threshold and the high lift threshold.

2. The compressor system of claim 1, wherein each of the one or more compressors includes: - a pre-rotation vane (PRV) located proximate to a suction inlet of the compressor; and - a variable geometry diffuser (VGD) located proximate to a discharge outlet of the compressor.

3. The compressor system of claim 2, wherein the PRV is adjustable between a first fully closed position and a fully open position, and the VGD is adjustable between a second fully closed position and a maximum allowed open position.

4. The compressor system of claim 2 or 3, wherein the instructions, when executed by the processing circuit, cause the processing circuit to: - control a first position of the PRV in the first mode to adjust a capacity of each of the one or more compressors, wherein a second position of the VGD in the first mode is independent of the first position of the PRV; and - control the first position of the PRV and the second position of the VGD in the second mode to adjust a capacity of each of the one or more compressors, wherein the second position of the VGD in the second mode is dependent on the first position of the PRV.

5. The compressor system of claim 4, wherein the instructions, when executed by the processing circuit, cause the processing circuit to: - determine that the compressor lift for a respective compressor of the one or more compressors is below the low lift threshold; and - operate the respective compressor in the first mode.

6. The compressor system of claim 4 or 5, wherein the instructions, when executed by the processing circuit, cause the processing circuit to: - determine that the compressor lift for a respective compressor of the one or more compressors is greater than the low lift threshold; and - operate the respective compressor in the second mode. ​ - operating the respective compressor in the second mode.

7. The compressor system of any one of claims 2 to 6, wherein each of the one or more compressors comprises a stall detector configured to detect a pressure pulsation at a discharge outlet of the compressor, wherein the pressure pulsation is indicative of a stall noise amplitude at the discharge outlet of the compressor.

8. The compressor system of claim 7, wherein the instructions, when executed by the processing circuitry, cause the processing circuitry to: - receive, from the stall detector, data indicative of the stall noise amplitude; - compare the stall noise amplitude to an acceptable stall voltage threshold range; and - based on the stall noise amplitude exceeding the acceptable stall voltage threshold range, control a position of the VGD to reduce the stall noise amplitude.

9. The compressor system of claim 8, wherein the instructions, when executed by the processing circuitry, cause the processing circuitry to: drive the position of the VGD toward a fully closed position to reduce the stall noise amplitude.

10. The compressor system of any one of claims 1 to 9, wherein each of the one or more compressors is coupled to a fixed speed driver configured to drive operation of the compressor.

11. A heating, ventilation, air conditioning, and refrigeration (HVAC&R) system comprising: - a vapor compression system comprising: - a vapor compression circuit configured to circulate a working fluid therethrough; and - a compressor configured to pressurize the working fluid and direct it through the vapor compression circuit, wherein the compressor comprises a pre-rotary vane (PRV) adjustable between a fully open position and a first fully closed position, and a variable geometry diffuser (VGD) adjustable between a maximum allowed open position and a second fully closed position; and - a controller comprising a memory and a processing circuitry, wherein the memory stores instructions that, when executed by the processing circuitry, cause the processing circuitry to transition operation of the compressor between a first mode and a second mode to adjust a capacity of the compressor, wherein a first position of the VGD is independent of a second position of the PRV in the first mode, and the first position of the VGD is dependent on the second position of the PRV in the second mode.

12. The HVAC&R system of claim 11, wherein the vapor compression system comprises one or more sensors configured to detect one or more operating conditions of the vapor compression system and provide feedback to the controller indicative of the one or more operating conditions.

13. The HVAC&R system of claim 12, wherein the one or more operating conditions include: an inlet temperature of an evaporator of the vapor compression system, an outlet temperature of the evaporator of the vapor compression system, an inlet temperature of a condenser of the vapor compression system, an outlet temperature of the condenser of the vapor compression system, or any combination thereof.

14. The HVAC&R system of claim 12 or 13, wherein the instructions, when executed by the processing circuitry, cause the processing circuitry to: determine a lift of the compressor based on a ratio of an actual head coefficient of the compressor to a maximum head coefficient of the compressor; compare the lift to a low lift threshold and a high lift threshold; operate the compressor in the first mode when the lift is less than the low lift threshold; and operate the compressor in the second mode when the lift is greater than the high lift threshold.

15. The HVAC&R system of claim 14, wherein the actual head coefficient is based on the one or more operating conditions of the vapor compression system.

16. The HVAC&R system of any of claims 11 to 15, wherein the instructions, when executed by the processing circuitry, cause the processing circuitry to: adjust the first position of the VGD between a maximum allowed open position and a first fully closed position; and adjust the second position of the PRV between a fully open position and a second fully closed position.

17. The HVAC&R system of claim 16, wherein the instructions, when executed by the processing circuitry, cause the processing circuitry to, in the first mode, set the maximum allowed open position of the VGD at a maximum possible open position of the VGD.

18. The HVAC&R system of claim 16 or 17, wherein the instructions, when executed by the processing circuitry, cause the processing circuitry to, in the second mode, set the maximum allowed open position of the VGD based on the second position of the PRV.

19. A method for controlling a capacity of a compressor having a pre-rotating vane (PRV) and a variable geometry diffuser (VGD), the method comprising: determining an actual head coefficient of the compressor based on one or more operating conditions of a vapor compression system employing the compressor; determining a lift of the compressor based on a ratio of the actual head coefficient of the compressor to a maximum head coefficient; comparing the lift to a low lift threshold and a high lift threshold to generate a comparison result; in response to the comparison result indicating that the lift is less than the low lift threshold, operating the compressor in a first mode in which a position of the VGD varies independently of a position of the PRV; and in response to the comparison result indicating that the lift is greater than the high lift threshold, operating the compressor in a second mode in which the position of the VGD varies based on a correlation between the position of the VGD and the position of the PRV.

20. The method of claim 19, comprising: - receiving sensor data from one or more sensors, wherein the sensor data is indicative of one or more operating parameters of the vapor compression system; - receiving stall voltage signal data from a stall detector coupled to the compressor, wherein the stall voltage signal data is indicative of a stall noise amplitude in the compressor; and - controlling the position of the VGD based on the sensor data and the stall voltage signal data.

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