SYSTEM AND METHOD FOR OPERATING A COMPRESSOR OF AN HVAC SYSTEM

A heating, ventilation, and/or air conditioning (HVAC) system includes a variable capacity compressor and a controller communicatively coupled to the variable capacity compressor. The controller is configured to receive data indicative of an operating parameter of the HVAC system, determine an upper suction pressure limit of the HVAC system based on the data, determine a lower suction pressure limit of the HVAC system based on the data, determine a target suction pressure value, wherein the target suction pressure value is less than or equal to the upper suction pressure limit and is greater than or equal to the lower suction pressure limit, and modulate operation of the variable capacity compressor such that a detected suction pressure of the HVAC system approaches the target suction pressure value.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from and the benefit of India Provisional Patent Application No. 202221019315, entitled “A SYSTEM AND METHOD FOR OPERATING A COMPRESSOR OF AN HVAC SYSTEM,” filed Mar. 31, 2022, which is hereby incorporated by reference in its entirety for all purposes.

BACKGROUND

Heating, ventilation, and air conditioning (HVAC) systems are utilized in residential, commercial, and industrial environments to control environmental properties, such as temperature and humidity, for occupants of the respective environments (e.g., enclosed spaces). For example, an HVAC system may include one or more heat exchangers, such as a heat exchanger configured to place an air flow in a heat exchange relationship with a working fluid of a vapor compression circuit (e.g., evaporator, condenser), a heat exchanger configured to place an air flow in a heat exchange relationship with combustion products (e.g., a furnace), or both. In general, the heat exchange relationship(s) may cause a change in pressures and/or temperatures of the air flow, the working fluid, the combustion products, or any combination thereof. The air flow may be directed toward the environment (e.g., enclosed space) to change conditions of the environment. Control features may be employed to control the above-described features such that an environmental parameter (e.g., temperature) of the environment reaches a target value.

Multi-stage HVAC equipment may be employed to provide heating or cooling at a faster rate and/or more efficiently than single stage HVAC equipment. For example, two stage HVAC equipment may be configured to operate in a first stage operating mode and a second stage operating mode that cause conditioning of an air flow at different respective rates. The two stage HVAC equipment may be controlled by a controller that receives a call from a thermostat and determines, in response to the call, if and when to operate the two stage HVAC equipment in the second stage operating mode. Unfortunately, traditional systems may be ill-equipped to determine if and when to initiate second stage operation of the two stage HVAC equipment, leading to inefficient heat exchange and/or lengthy amounts of time to condition the environment (e.g., enclosed space) until the call from the thermostat is satisfied. Further, traditional systems may suffer from compatibility issues associated with certain traditional thermostats and certain multi-stage HVAC equipment. Accordingly, it is now recognized that improved operation of multi-stage HVAC equipment is desired.

SUMMARY

A summary of certain embodiments disclosed herein is set forth below. It should be noted that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below.

In one embodiment, a heating, ventilation, and/or air conditioning (HVAC) system includes a variable capacity compressor and a controller communicatively coupled to the variable capacity compressor. The controller is configured to receive data indicative of an operating parameter of the HVAC system, determine an upper suction pressure limit of the HVAC system based on the data, determine a lower suction pressure limit of the HVAC system based on the data, determine a target suction pressure value, wherein the target suction pressure value is less than or equal to the upper suction pressure limit and is greater than or equal to the lower suction pressure limit, and modulate operation of the variable capacity compressor such that a detected suction pressure of the HVAC system approaches the target suction pressure value.

In another embodiment, a controller of a heating, ventilation, and air conditioning (HVAC) system includes a non-transitory, computer-readable medium having instructions stored thereon. The instructions, when executed by processing circuitry of the controller, are configured to cause the controller to receive a call for cooling, receive data indicative of an operating parameter of the HVAC system, determine an upper suction pressure limit of the HVAC system based on the data, determine a lower suction pressure limit of the HVAC system based on the data, determine a target suction pressure value of the HVAC system, wherein the target suction pressure value is less than or equal to the upper suction pressure limit and is greater than or equal to the lower suction pressure limit, iteratively reduce the target suction pressure value, and modulate operation of a compressor of the HVAC system based on the target suction pressure value.

In a further embodiment, a heating, ventilation, and air conditioning (HVAC) system includes a compressor configured to operate at variable capacities and a controller configured to communicatively couple to the compressor. The controller is configured to receive a call for cooling from a non-communicating thermostat, receive data indicative of an outdoor ambient temperature, compare the outdoor ambient temperature to a threshold temperature value, establish a lower suction pressure limit and an upper suction pressure limit based on the comparison, determine a target suction pressure value, wherein the target suction pressure value is less than or equal to the upper suction pressure limit and is greater than or equal to the lower suction pressure limit, and modulate operation of the compressor such that a detected suction pressure of the HVAC system approaches the target suction pressure value.

DETAILED DESCRIPTION

As used herein, the terms “approximately,” “generally,” and “substantially,” and so forth, are intended to convey that the property value being described may be within a relatively small range of the property value, as those of ordinary skill would understand. For example, when a property value is described as being “approximately” equal to (or, for example, “substantially similar” to) a given value, this is intended to mean that the property value may be within +/- 5%, within +/- 4%, within +/- 3%, within +/- 2%, within +/- 1%, or even closer, of the given value. Similarly, when a given feature is described as being “substantially parallel” to another feature, “generally perpendicular” to another feature, and so forth, this is intended to mean that the given feature is within +/- 5%, within +/- 4%, within +/- 3%, within +/- 2%, within +/- 1%, or even closer, to having the described nature, such as being parallel to another feature, being perpendicular to another feature, and so forth. Further, it should be understood that mathematical terms, such as “planar,” “slope,” “perpendicular,” “parallel,” and so forth are intended to encompass features of surfaces or elements as understood to one of ordinary skill in the relevant art, and should not be rigidly interpreted as might be understood in the mathematical arts. For example, a “planar” surface is intended to encompass a surface that is machined, molded, or otherwise formed to be substantially flat or smooth (within related tolerances) using techniques and tools available to one of ordinary skill in the art. Similarly, a surface having a “slope” is intended to encompass a surface that is machined, molded, or otherwise formed to be oriented at an angle (e.g., incline) with respect to a point of reference using techniques and tools available to one of ordinary skill in the art.

The present disclosure is directed to heating, ventilation, and air conditioning (HVAC) systems. The HVAC system may include a vapor compression system configured to circulate a working fluid to condition a conditioning fluid, such as an air flow. For example, the vapor compression system may place the working fluid in a heat exchange relationship with the air flow to heat, cool, and/or dehumidify the air flow. The vapor compression system may then deliver the conditioned air flow to a space serviced by the HVAC system to condition the space.

The HVAC system may include modulating HVAC equipment, such as a compressor, configured to operate at each of a plurality of operating capacities (e.g., frequencies, speeds, stages, etc.). In accordance with present techniques, the HVAC system may further include a control system configured to enable variable operation of the modulating HVAC equipment to more efficiently satisfy a load or demand of the HVAC system.

In certain traditional systems, modulating (e.g., multi-stage) HVAC equipment, such as variable capacity compressors or variable speed compressors, may be incompatible with single stage thermostats that are designed for single stage HVAC equipment. Similarly, in certain existing systems, modulating HVAC equipment may be incompatible with other (e.g., non-modulating) HVAC equipment. Further, in certain traditional systems, modulating HVAC equipment may have limited compatibility with single stage thermostats and may include controls that are ill-equipped to determine if and when to adjust operation of the modulating HVAC equipment in a manner that provides efficient and timely environmental control of a conditioned space (e.g., enclosed space). Further still, in certain traditional systems, modulating HVAC equipment may be configured to partially interface with multi-stage thermostats, but control aspects associated with the modulating HVAC equipment and the multi-stage thermostat may nevertheless be ill-equipped to determine if and when to adjust (e.g., modulate) operation of the modulating HVAC equipment in a manner that provides efficient and timely environmental control of the conditioned space. For example, existing systems may be unable to modulate operation of the HVAC equipment based on a particular load or demand (e.g., call for conditioning) of the HVAC system and/or based on particular operating conditions of the HVAC system.

Indeed, different embodiments of thermostats (e.g., a communicating thermostat, a conventional thermostat) and/or control circuitry may be incorporated in different HVAC systems, and/or a communication link or coupling between the control system and the components of the vapor compression system may be different for different HVAC systems. As such, it may be difficult to enable the control systems of different HVAC systems to operate in a desirable manner to efficiently operate components of the HVAC system and satisfy a load or demand on the HVAC system. For example, an HVAC system may include a compressor (e.g., a modulating compressor) configured to operate at variable capacities or speeds and may also include an air handler and/or thermostat that is configured to operate with single stage equipment (e.g., a single stage compressor). In other words, the air handler and the thermostat may not be configured to enable operation of the HVAC system in multiple stages. In such instances, the thermostat and/or the air handler may be unable to adequately communicate with the modulating compressor to enable operation of the compressor across a range of capacities or speeds.

Thus, it is presently recognized that there is a desire to improve control systems of HVAC systems to enable operation of different types of HVAC equipment with one another in a more efficient manner. Accordingly, embodiments of the present disclosure are directed to a control system configured to enable variable operation of modulating HVAC equipment (e.g., a variable speed compressor) when the modulating HVAC equipment is utilized with non-modulating (e.g., non-communicating) HVAC equipment. Thus, present embodiments enable more efficient control and operation of the HVAC system to satisfy a load or demand on the HVAC system.

Turning now to the drawings,FIG.1illustrates an embodiment of a heating, ventilation, and/or air conditioning (HVAC) system for environmental management that may employ one or more HVAC units. As used herein, an HVAC system includes any number of components configured to enable regulation of parameters related to climate characteristics, such as temperature, humidity, air flow, pressure, air quality, and so forth. For example, an “HVAC system” as used herein is defined as conventionally understood and as further described herein. Components or parts of an “HVAC system” may include, but are not limited to, all, some of, or individual parts such as a heat exchanger, a heater, an air flow control device, such as a fan, a sensor configured to detect a climate characteristic or operating parameter, a filter, a control device configured to regulate operation of an HVAC system component, a component configured to enable regulation of climate characteristics, or a combination thereof. An “HVAC system” is a system configured to provide such functions as heating, cooling, ventilation, dehumidification, pressurization, refrigeration, filtration, or any combination thereof. The embodiments described herein may be utilized in a variety of applications to control climate characteristics, such as residential, commercial, industrial, transportation, or other applications where climate control is desired.

The HVAC unit12also may include other equipment for implementing the thermal loop. Compressors42increase the pressure and temperature of the working fluid before the working fluid enters the heat exchanger28. The compressors42may be any suitable type of compressors, such as scroll compressors, rotary compressors, screw compressors, or reciprocating compressors. In some embodiments, the compressors42may include a pair of hermetic direct drive compressors arranged in a dual stage configuration44. However, in other embodiments, any number of the compressors42may be provided to achieve various stages of heating and/or cooling. Additional equipment and devices may be included in the HVAC unit12, such as a solid-core filter drier, a drain pan, a disconnect switch, an economizer, pressure switches, phase monitors, and humidity sensors, among other things.

FIG.3illustrates a residential heating and cooling system50, also in accordance with present techniques. The residential heating and cooling system50may provide heated and cooled air to a residential structure, as well as provide outside air for ventilation and provide improved indoor air quality (IAQ) through devices such as ultraviolet lights and air filters. In the illustrated embodiment, the residential heating and cooling system50is a split HVAC system. In general, a residence52conditioned by a split HVAC system may include working fluid conduits54that operatively couple the indoor unit56to the outdoor unit58. The indoor unit56may be positioned in a utility room, an attic, a basement, and so forth. The outdoor unit58is typically situated adjacent to a side of residence52and is covered by a shroud to protect the system components and to prevent leaves and other debris or contaminants from entering the unit. The working fluid conduits54transfer working fluid between the indoor unit56and the outdoor unit58, typically transferring primarily liquid working fluid in one direction and primarily vaporized working fluid in an opposite direction.

When the system shown inFIG.3is operating as an air conditioner, a heat exchanger60in the outdoor unit58serves as a condenser for re-condensing vaporized working fluid flowing from the indoor unit56to the outdoor unit58via one of the working fluid conduits54. In these applications, a heat exchanger62of the indoor unit functions as an evaporator. Specifically, the heat exchanger62receives liquid working fluid, which may be expanded by an expansion device, and evaporates the working fluid before returning it to the outdoor unit58.

The residential heating and cooling system50may also operate as a heat pump. When operating as a heat pump, the roles of heat exchangers60and62are reversed. That is, the heat exchanger60of the outdoor unit58will serve as an evaporator to evaporate working fluid and thereby cool air entering the outdoor unit58as the air passes over the outdoor heat exchanger60. The indoor heat exchanger62will receive a stream of air blown over it and will heat the air by condensing the working fluid.

The compressor74compresses a working fluid vapor and delivers the vapor to the condenser76through a discharge passage. In some embodiments, the compressor74may be a centrifugal compressor. The working fluid vapor delivered by the compressor74to the condenser76may transfer heat to a fluid passing across the condenser76, such as ambient or environmental air96. The working fluid vapor may condense to a working fluid liquid in the condenser76as a result of thermal heat transfer with the environmental air96. The liquid working fluid from the condenser76may flow through the expansion device78to the evaporator80.

The liquid working fluid delivered to the evaporator80may absorb heat from another air flow, such as a supply air flow98provided to the building10or the residence52. For example, the supply air flow98may include ambient or environmental air, return air from a building, or a combination of the two. The liquid working fluid in the evaporator80may undergo a phase change from the liquid working fluid to a working fluid vapor. In this manner, the evaporator80may reduce the temperature of the supply air flow98via thermal heat transfer with the working fluid. Thereafter, the vapor working fluid exits the evaporator80and returns to the compressor74by a suction line to complete the loop.

In some embodiments, the vapor compression system72may further include a reheat coil in addition to the evaporator80. For example, the reheat coil may be positioned downstream of the evaporator relative to the supply air flow98and may reheat the supply air flow98when the supply air flow98is overcooled to remove humidity from the supply air flow98before the supply air flow98is directed to the building10or the residence52.

Further, any of the systems illustrated inFIGS.1-4may include modulating HVAC equipment, such as a multi-stage or variable capacity compressor, configured to operate in multiple stages of operation (e.g., variable capacities) and a control system (e.g., a controller) configured to enable modulated operation of the modulating HVAC equipment. As previously mentioned, present embodiments enable modulated operation of a variable capacity compressor that is incorporated with an HVAC system having an air handler (e.g., indoor unit) and/or a thermostat that is not configured to provide certain information (e.g., a detected temperature of a conditioned space) that may otherwise enable modulated operation of the variable capacity compressor. For example, the air handler and/or thermostat may be a non-communicating or conventional embodiment that is configured to output limited control signals. Control systems and methods utilizing the present techniques are nevertheless configured to enable modulated operation of the compressor without the information typically provided by a communicating air handler and/or communicating thermostat. For example, the presently disclosed techniques enable modulated operation of a compressor based on a demand or load (e.g., cooling load) on the HVAC system. In some embodiments, the control system may be configured to enable modulated operation of the compressor based on a measured outdoor or ambient temperature. The control system may additionally or alternatively establish and adjust (e.g., iteratively adjust) one or more target operating parameters of the compressor (e.g., a target suction pressure) to enable modulated operation of the compressor. In this way, the presently disclosed techniques enable more efficient operation of the HVAC system having different types (e.g., communicating, non-communicating) HVAC equipment. It should be appreciated that the techniques described herein may be incorporated with HVAC systems configured as air conditioning systems, heat pumps, and/or any other suitable HVAC system having HVAC equipment configured for modulated operation and HVAC equipment that is not configured for modulated operation, such as non-communicating air handlers and/or non-communicating thermostats.

To provide context for the following discussion,FIG.5is a schematic of an embodiment of an HVAC system100, which may be incorporated any of the systems or units illustrated inFIGS.1-4or any other suitable HVAC system. The HVAC system100includes certain elements similar to those discussed above, including a compressor102, a condenser104, an evaporator106, and an expansion device108(e.g., expansion valve, electronic expansion valve) disposed along a working fluid circuit110(e.g., vapor compression circuit) of the HVAC system100. The HVAC system100may circulate a working fluid, such as a refrigerant, through the working fluid circuit110to enable conditioning (e.g., cooling) of an air flow supplied to a conditioned space in order to condition the space.

The compressor102is a variable capacity compressor (e.g., a variable speed compressor). To this end, the HVAC system100also includes a motor112and a VSD114configured to enable operation of the compressor102at various capacities or speeds. For example, the VSD114may be a variable frequency drive configured to vary an input voltage and/or frequency supplied to the motor112to enable variable speed operation of the motor112and the compressor102. It should be appreciated that the motor112and/or the VSD114may be considered components of the compressor102throughout the following discussion.

In some embodiments, the HVAC system100may be configured as a split system, such as the residential heating and cooling system50described above. For example, the compressor102and the condenser104may be packaged in an outdoor unit (e.g., outdoor unit58), and the evaporator106may be packaged in an indoor unit (e.g., indoor unit56). However, in other embodiments, the HVAC system100may be configured as a packaged system or unit.

In accordance with present techniques, the compressor102may be controlled to enable more efficient operation of the HVAC system100. For example, operation of compressor102may be modulated to provide variable capacity operation of the compressor102. The compressor102may be controlled based on an operating mode of the HVAC system100, based on operating conditions or parameters of the HVAC system100, based on a load or demand on the HVAC system100, and/or based on other suitable factors. Indeed, present techniques further enable modulated operation of the compressor102with conventional or non-communicating components that may be incorporated with the HVAC system100and may not be configured to provide data and/or information that is traditionally utilized to enable modulated operation of compressors.

To this end, the HVAC system100includes a controller116(e.g., a control system, a control panel, control circuitry) that is communicatively coupled to one or more components of the HVAC system100(e.g., compressor102, motor112, VSD114) and is configured to monitor, adjust, and/or otherwise control operation of the components of the HVAC system100. For example, one or more control transfer devices, such as wires, cables, wireless communication devices, and the like, may communicatively couple the compressor102, the motor112, the VSD114, and/or any other suitable components of the HVAC system100to the controller116. That is, the compressor102, the motor112, and/or the VSD114may each have one or more communication components that facilitate wired or wireless (e.g., via a network) communication with the controller116. In some embodiments, the communication components may include a network interface that enables the components of the HVAC system100to communicate via various protocols such as EtherNet/IP, ControlNet, DeviceNet, or any other communication network protocol. Alternatively, the communication components may enable the components of the HVAC system100to communicate via mobile telecommunications technology, Bluetooth®, near-field communications technology, and the like. As such, the compressor102, the motor112, and/or the VSD114may wirelessly communicate data between each other. In other embodiments, operational control of certain components of the HVAC system100may be regulated by one or more relays or switches (e.g., a 24 volt alternating current [VAC] relay).

In some embodiments, the controller116may be a component of or may include the control panel82. In other embodiments, the controller116may be a standalone controller, a dedicated controller, a group of controllers, multiple, separate controllers, an outdoor unit controller packaged with the compressor102, or another suitable controller included in the HVAC system100. In any case, the controller116is configured to control components of the HVAC system100in accordance with the techniques discussed herein. The controller116includes processing circuitry118, such as a microprocessor, which may execute software for controlling the components of the HVAC system100. The processing circuitry118may include multiple microprocessors, one or more “general-purpose” microprocessors, one or more special-purpose microprocessors, and/or one or more application specific integrated circuits (ASICS), or some combination thereof. For example, the processing circuitry118may include one or more reduced instruction set (RISC) processors.

The controller116may also include a memory device120(e.g., a memory) that may store information, such as executable instructions, control software, look up tables, configuration data, etc. The memory device120may include a volatile memory, such as random access memory (RAM), and/or a nonvolatile memory, such as read-only memory (ROM). The memory device120may store a variety of information and may be used for various purposes. For example, the memory device120may store processor-executable instructions including firmware or software for the processing circuitry118to execute, such as instructions for controlling components of the HVAC system100(e.g., compressor102, motor112, VSD114). Indeed, it should be appreciated that the memory device120may include executable instructions for performing any of the techniques disclosed herein. In some embodiments, the memory device120is a tangible, non-transitory, machine-readable-medium that may store machine-readable instructions for the processing circuitry118to execute. The memory device120may include ROM, flash memory, a hard drive, or any other suitable optical, magnetic, or solid-state storage medium, or a combination thereof. The memory device120may store data, instructions, and any other suitable data. For example, the memory device120may include a database122configured to store one or more reference values, operating parameter values, calculated values, historical values, and/or any other suitable data to enable operation of the HVAC system100in accordance with the presently disclosed techniques.

In some embodiments, the controller116may include one or more timers124(e.g., one or more clocks). For example, the controller116may include executable instructions stored on the memory device120, and the processing circuitry118may be configured to execute the executable instructions to operate one or more of the timers124to enable monitoring and/or tracking of one or more time durations associated with operations of the HVAC system100utilizing the present techniques, as described in greater detail below. In some embodiments, time durations and/or time duration thresholds associated with the one or more timers124may be stored in the memory device120, such as in the database122.

The controller116may also be coupled to one or more additional control components of the HVAC system100. For example, in the illustrated embodiment, the controller116is communicatively coupled to a thermostat126. As will be appreciated, the thermostat126may be associated with a space conditioned by the HVAC system100and may be configured to receive a user input corresponding to an operating parameter set point (e.g., temperature set point). Based on the user input, the thermostat126may output a call for conditioning (e.g., a call for cooling, 24 volt signal, electrical signal), and the call for conditioning may be received by the controller116. For example, the thermostat126may be disposed within a space conditioned by the HVAC system100, and the controller116may be disposed within an enclosure or unit having the compressor102(e.g., outdoor unit58). However, the thermostat126may be a conventional or non-communicating thermostat, in some embodiments, and may not be configured to provide data or information typically referenced and utilized to enable modulated operation of the compressor102. For example, the thermostat126may not be configured to collect and/or transmit data indicative of a measured temperature within the conditioned space to the controller116. In some embodiments, the controller116may additionally or alternatively be communicatively coupled to an air handler controller (e.g., controller of indoor unit56) having similar capability limitations as the thermostat126. That is, the controller116may be communicatively coupled to a conventional or non-communicating air handler controller. Nevertheless, the controller116incorporating the presently disclosed techniques is configured to enable modulated operation of the compressor102to satisfy a call for conditioning received from the thermostat126. For example, the controller116may be configured to determine and establish a desired operating parameter (e.g., suction pressure) according to which the HVAC system100(e.g., compressor102) may operate. More specifically, the controller116may be configured to determine, establish, and adjust a variable target operating parameter and enable operation (e.g., modulated operation) of the compressor102to approach and/or reach the target operating parameter. It should be appreciated that the disclosed techniques may also be utilized in embodiments of the HVAC system100in which the thermostat126is a communicating thermostat.

The controller116is also communicatively coupled to one or more sensors128of the HVAC system100. The one or more sensors128are configured to detect one or more operating parameters of the HVAC system100and provide feedback and/or data indicative of the operating parameters to the controller116. For example, a first sensor130of the one or more sensors128may be an outdoor or ambient temperature sensor configured to detect or measure a temperature of an ambient environment surrounding the HVAC system100. As another example, a second sensor132of the one or more sensors128may be a working fluid sensor configured to measure or detect an operating parameter (e.g., temperature, pressure) of the working fluid circulated through the working fluid circuit110. In some embodiments, the second sensor132may be disposed along the working fluid circuit110upstream of the compressor102relative to a flow direction of the working fluid through the working fluid circuit110and may be configured to detect a suction pressure of the working fluid entering the compressor102. The one or more sensors128may additionally or alternatively include other sensors, such as sensors configured to detect one or more operating parameters of the compressor102, the motor112, the VSD114, and/or other components of the HVAC system100. As described in further detail below, the controller116may utilize data and/or feedback received from the one or more sensors128to enable modulated operation of the compressor102in accordance with present techniques.

With the foregoing in mind,FIG.6is a process flow diagram of an embodiment of a method198(e.g., control sequence, one or more control sequences, algorithm) for operating the HVAC system100(e.g., the compressor102) and to enable modulated operation of the compressor102(e.g., in a cooling mode of the HVAC system100). In this way, the method198enables more efficient operation of the HVAC system100. As will be appreciated, the method198may be performed by the controller116(e.g., outdoor unit controller, compressor controller, one or more controllers). For example, computer-executable instructions or code for performing the method198may be stored on the memory device120, and the processing circuitry118may execute the instructions to perform the method198. In some embodiments, one or more steps of the method198may be performed by another controller of the HVAC system100and/or by a controller remote from the HVAC system100. In additional or alternative embodiments, multiple components or systems may perform the steps of the method198. It should also be noted that additional steps may be performed with respect to the depicted method198. Moreover, certain steps of the method198may be removed, modified, and/or performed in a different order. In some embodiments, certain steps of the method198may not be performed based on a configuration of the HVAC system100, such as based on a configuration of the compressor102. Further still, the steps of the method198may be performed in any suitable relation with one another, such as in response to one another and/or in parallel with one another. In some implementations, the method198may include multiple control schemes (e.g., loops, branches, portions, etc.). For example, the illustrated embodiment depicts an embodiment of a first control scheme200of the method198. Additional embodiments of control schemes of the method198are described in further detail below.

At block202, a call for cooling is received. For example, the controller116may receive the call for cooling from the thermostat126. As mentioned above, the call for cooling may be output by the thermostat126and may be received by the controller116as a 24-volt electrical signal (e.g., a signal configured to initiate operation of the compressor102). However, as the thermostat126may be a conventional or non-communicating thermostat, the call for cooling may not include data typically provided by communicating thermostats (e.g., data indicative of a measured temperature within the conditioned space). In some embodiments, the call for cooling may be transmitted to the controller116by another system or controller of the HVAC system100, such as a non-communicating or conventional indoor unit or air handler controller.

In response to receipt of the call for cooling, the controller116may operate the compressor102at a lower frequency limit (e.g., minimum allowable frequency, minimum allowable capacity, lower capacity limit) for an initial time period (e.g., duration of time, threshold time period), as indicated by block204. For example, the lower frequency limit may be a minimum allowable frequency at which the compressor102may be operated. In some embodiments, the lower frequency limit may be determined based on regulatory standards, target or desired operating (e.g., efficiency) metrics, and/or other restrictions or parameters. Additionally or alternatively, the lower frequency limit may be determined based on a type of the compressor102, a model of the compressor102, a capacity of the compressor102, a capacity of the HVAC system100, another characteristic of the HVAC system100, or any combination thereof. In some embodiments, the controller116may output one or more control signals to the VSD114, the motor112, the compressor102, or any combination thereof to enable operation of the compressor102at the lower frequency limit. Further, the controller116may monitor or track operation of the compressor102at the lower frequency limit for the initial time period utilizing one or more of the timers124(e.g., a first timer). In some embodiments, the initial time period may be a predetermined, constant, and/or fixed period or duration of time. For example, the initial time period may be approximately 3 minutes, 4 minutes, 5 minutes, 6 minutes, or any other suitable period of time.

Upon a determination that the initial time period has lapsed (e.g., as indicated by the timer124), the controller116may determine an upper suction pressure limit and a lower suction pressure limit within which the compressor102and/or HVAC system100is to be operated during the operating cycle of the HVAC system100, as indicated by block206. That is, the controller116may determine upper and lower suction pressure limits to be referenced as operational boundaries during operation of the compressor102and the HVAC system100to satisfy the call for cooling received at block202. The upper and lower suction pressure limits may be determined in any suitable manner. In some embodiments, the upper suction pressure limit and/or the lower suction pressure limit may be determined and/or selected based on predetermined values stored in the memory device120. Additionally or alternatively, the upper suction pressure limit and/or the lower suction pressure limit may be determined based on one or more equations that may be stored in the memory device120. The one or more equations may utilize any suitable inputs to enable calculation of the upper suction pressure limit and/or the lower suction pressure limit. For example, empirical data, test data, regulatory parameters, operating parameters, constant values, predetermined parameters, and/or any other suitable input. As discussed in further detail below, in some embodiments, the upper suction pressure limit and/or the lower suction pressure limit may be determined in different manners, such as based on a detected operating parameter or characteristic of the HVAC system100(e.g., based on a measured ambient temperature).

Once the upper suction pressure limit and the lower suction pressure limit are determined (e.g., by the controller116), the method198may proceed to block208. At block208, the controller116, for example, may determine whether a Next Target Suction Pressure (NTSP) value (e.g., stored target suction pressure value, future target suction pressure value, subsequent target suction pressure value, expected target suction pressure value) of the HVAC system100equals zero (e.g., null). For example, the memory device120(e.g., database122) may be configured to store an NTSP value associated with the HVAC system100. In some embodiments, the NTSP value stored on the memory device120may be a non-zero value and may be associated with a previous operating cycle (e.g., cooling cycle) of the HVAC system100, such as most recent operating or cooling cycle of the HVAC system100prior to receipt of the call for cooling at block202. For example, the NTSP value stored in the memory device120may be the last NTSP value determined or established by the controller116during the most recent operating cycle. In some embodiments, the NTSP value may be reset to zero (e.g., in the memory device120and/or database122) in response to an interruption in supply of power to the HVAC system100and/or in response to a hard reset of the HVAC system100.

Based on a determination (e.g., via the controller116) that the NTSP value does not equal zero at block208, the method198may proceed to block210of a third control scheme212of the method198. The third control scheme212, including block210, is described in further detail below with reference toFIG.8. Based on a determination (e.g., via the controller116) that the NTSP value (e.g., stored in the memory device120) equals zero at block208(e.g., resulting from a hard reset of the HVAC system100or upon a new installation of the HVAC system100), the method198may proceed to block214of the first control scheme200of the method198. At block214, the controller116may set (e.g., designate, establish) the upper suction pressure limit determined at block206as a Target Suction Pressure (TSP) (e.g., TSP value, suction pressure set point) of the HVAC system100. The TSP value may be stored in the memory device120, in some embodiments. In general, with the TSP established, the HVAC system100may be operated to achieve the TSP. That is, operation of one or more components of the HVAC system100, such as the compressor102, may be adjusted or modified (e.g., during the cooling mode) to cause a measured suction pressure of the HVAC system100to approach and/or reach the TSP. As will be appreciated, the suction pressure may correspond to a pressure of the working fluid entering a suction side or inlet of the compressor102. Thus, in order to achieve the TSP, the controller116may be configured to adjust operation of the compressor102based on feedback received from one or more of the sensors128, such as the second sensor132disposed along the working fluid circuit110. The second sensor132may be configured to detect a suction pressure of the working fluid entering the compressor102. In some embodiments, the controller116may be configured to adjust an operating parameter of the compressor102, the motor112, and/or the VSD114based on the data and/or feedback received from the second sensor132. In this way, the controller116may modulate operation of the compressor102to cause the measured suction pressure to approach and/or reach the TSP.

Next, at block216, the compressor102may be operated for a first time period (T1). As similarly discussed above, the first time period may be monitored or tracked based on operation of one or more of the timers124(e.g., a second timer) of the controller116. The first time period may be any suitable time period. For example, the first time period may be a predetermined or fixed value (e.g., 3 minutes, 4 minutes, 5 minutes, 6 minutes, etc.), which may be stored in the memory device120and/or the database122. During the first time period, the controller116may operate the HVAC system100and/or may adjust operation of the HVAC system100(e.g., the compressor102) to cause the suction pressure of the working fluid detected by the second sensor132to approach the TSP established at block214. In some embodiments, the controller116may be configured to adjust a voltage and/or frequency applied to the motor112by the VSD114to cause a change in the suction pressure of the working fluid circuit110.

Upon lapse of the first time period (e.g., as determined by one of the timers124), the method198may proceed to block218. At block218, the controller116may set (e.g., establish) the NTSP as an updated value (e.g., future TSP value, subsequent TSP value, expected TSP value). The updated or new value of the NTSP may be determined by subtracting a differential pressure value (ΔP) (e.g., increment, predetermined value, fixed value, first differential pressure value) from the TSP (e.g., current TSP) designated at block214. The differential pressure value may be a target pressure reduction value. In some embodiments, the differential pressure value may be stored in the memory device120(e.g., database122) and may be referenced by the controller116to perform the step at block218. The differential pressure value may be any suitable value having any suitable units (e.g., 0.005 Megapascals [MPa], 0.01 MPa, 0.015 MPa, or any other suitable value). The updated value of the NTSP may be stored in the memory device120and/or database122. In accordance with present techniques, the NTSP is therefore decreased or reduced at block218.

After the NTSP value (e.g., future TSP value, subsequent TSP value, expected TSP value) is updated at block218, the method198may proceed to block220. At block220, the controller116, for example, may determine whether the NTSP value established or updated at block218is greater than the lower suction pressure limit determined at block206. Based on a determination that the NTSP is not greater than the lower suction pressure limit, the lower suction pressure limit may be established as the NTSP, as indicated by block222. In other words, the controller116may update or adjust the NTSP to be equal to the lower suction pressure limit. The NTSP updated as the lower suction pressure limit may be stored in the memory device120, and the controller116may continue to operate the HVAC system100utilizing the lower suction pressure limit as the NTSP for a remaining duration of the cooling cycle of the HVAC system100. That is, the controller116may operate and/or adjust operation of the HVAC system100(e.g., compressor102) to cause the measured suction pressure detected by the second sensor132to approach and/or reach the existing or current TSP until the call for cooling received at block202is satisfied and operation of the HVAC system100is suspended. As mentioned above, when operation of the HVAC system100is suspended at the end of an operating cycle, the existing or established NTSP at the time of suspended operation may remain stored in the memory device120(e.g., database122) for reference during execution of the method198(e.g., block208) in a subsequent operating cycle (e.g., cooling mode) of the HVAC system100.

Based on a determination that the NTSP is greater than the lower suction pressure limit at block220, the method198may proceed to block224. At block224, the controller116may initiate or start a timer (Tcheck), which may be one of the timers124(e.g., a third timer) of the controller116. Upon initiation of the timer (Tcheck), a frequency (e.g., first frequency, measured frequency, actual frequency, detected frequency, frequency value) of the compressor102may be determined, and the frequency value may be established as a first frequency value (e.g., F1), as indicated by block226. For example, the controller116may be configured to receive data and/or feedback from the compressor102, the motor112, and/or the VSD114indicative of a frequency applied to the compressor102(e.g., the motor112) at the start of the timer (Tcheck). In some embodiments, one of the sensors128of the HVAC system100may be configured to detect the frequency of the compressor102and provide data indicative of the frequency to the controller116at the start of the timer (Tcheck). The first frequency value (F1) may be stored in the memory device120, in some embodiments.

After the timer (Tcheck) runs for a designated time period (e.g., first designated time period), the method198proceeds to block228. At block228, an additional frequency (e.g., second frequency, measured frequency, actual frequency, detected frequency, frequency value) of the compressor102is determined at the end of the timer (Tcheck). The additional frequency value may be established as a second frequency value (e.g., F2) and may be stored in the memory device120. The additional frequency value may be determined in any suitable manner, such as utilizing the techniques described above with reference to block226. The duration of the timer (Tcheck, third timer, timer124) may be any suitable time period, such as a predetermined or fixed time period (e.g., 90 seconds, 120 seconds, 150 seconds, etc.), which may be stored in the memory device120.

The method198may then proceed to block230. At block230, the controller116may determine whether a difference between the additional frequency (F2) determined at block228and the frequency (F1) determined at block226is greater than zero. In other words, the controller116may be configured to subtract the frequency (F1) from the additional frequency (F2) at block230.

Based on a determination that the difference between the additional frequency (F2) and the frequency (F1) is not greater than zero, the method198may proceed to block232of a second control scheme234of the method198. The second control scheme234, including block232, is described in further detail below with reference toFIG.7. Based on a determination (e.g., via the controller116) that the difference between the additional frequency (F2) and the frequency (F1) is greater than zero at block230, the method198may proceed to block236of the first control scheme200of the method198. At block236, the TSP (e.g., TSP value, current TSP value) may be set (e.g., updated) based on the current NTSP value. In other words, the current NTSP value may be established as a new or updated value of the TSP. The updated value of the TSP may be stored in the memory device120. In this way, the TSP value may be decreased or reduced, and the controller116may modulate operation of the compressor102to cause the measured suction pressure of the working fluid circuit110to approach the updated value of the TSP and improve efficiency of the HVAC system100. Thereafter, the first control scheme200of the method198may return to block218, whereby the value of the NTSP may be updated in the manner described above.

In some instances, execution of the first control scheme200of the method198may include continual (e.g., repeated) execution of the steps at blocks218,220,224,226,228,230, and236in a loop or in succession. Thus, the values of the NTSP and the TSP may be iteratively reduced, and the controller116may continually adjust operation of the compressor102to approach and/or achieve the updated (e.g., reduced) TSP values. In this way, execution of the method198enables modulated operation of the compressor102during the operating cycle of the HVAC system100to satisfy the call for cooling (e.g., based on a load or demand on the HVAC system100). In particular, operation of the compressor102may be modulated without receipt of certain data (e.g., measured temperatures of the conditioned space) that would typically be provided by a communicating thermostat. The disclosed techniques therefore enable more efficient operation of the HVAC system100with the thermostat126(e.g., non-communicating thermostat) and/or other non-communicating HVAC equipment included in the HVAC system100.

FIG.7is a process flow diagram of an embodiment of the method198(e.g., control sequence, one or more control sequences) for operating the HVAC system100(e.g., the compressor102) to enable modulated operation of the compressor102and thereby enable more efficient operation of the HVAC system100. In particular, the illustrated embodiment depicts an embodiment of the second control scheme234of the method198. As discussed above, the method198includes block230, whereby the controller116may determine whether a difference between the additional frequency (F2) and the frequency (F1) determined at block230is greater than zero.

Based on a determination that the difference between the additional frequency (F2) and the frequency (F1) is not greater than zero, the method198may proceed to block232. At block232, the controller116may determine whether the difference between the additional frequency (F2) and the frequency (F1) is equal to zero. In response to a determination that the difference between the additional frequency (F2) and the frequency (F1) is not equal to zero (e.g., is less than zero), the method198may proceed to block250. At block250, a duration of the timer (Tcheck) discussed above with reference to blocks224,226, and228may be adjusted. For example, the duration of the timer (Tcheck) may be adjusted from the first duration of time utilized in the first control scheme200to a second duration of time. In some embodiments, the second duration of time may be greater or longer than the first duration of time. For example, the first duration of time may be approximately 120 seconds, and the second duration of time may be approximately 150 seconds, 180 seconds, 210 seconds, or another suitable duration of time that is greater than the first duration of time. The updated duration of time of the timer (e.g., timer124, third timer) may be stored in the memory device120and/or the database122(e.g., Tcheck_additional). Also at block250, a flag counter of the HVAC system100(e.g., the controller116) may be increased or incremented (e.g., by one unit or count). For example, the flag counter may be a metric or other data stored in the memory device120and/or the database122. Thus, at block250, the count, metric, or other value associated with the flag counter and stored in the memory device120may be updated, such as increased by one, and the updated value may be stored in the memory device120.

Thereafter, the method198may proceed to block252. At block252, the flag counter (e.g., a value of the flag counter) may be compared to a flag limit. Similar to the flag counter, a value of the flag limit may be stored in the memory device120and/or the database122. The value of the flag limit may be a predetermined and/or fixed value, such as an integer (e.g., 2, 3, etc.). The controller116may reference the value of the flag counter and the value of the flag limit stored in the memory device120to make the determination at block252. In response to a determination that the flag counter is less than or equal to the flag limit, the method198may proceed to block224of the first control scheme200discussed above with reference toFIG.6. From block224, the method198may continue (e.g., resume) operation of the first control scheme200in the manner discussed above. However, it should be noted that the continued operation of first control scheme200may utilize the timer (Tcheck_additional) instead of the timer (Tcheck) based on the time duration adjustment performed at block250. Thus, operation of the method198(e.g., execution of blocks224,226, and228) may extend a greater length of time. The lapse of a greater length of time during execution of blocks224,226, and228may enable increased stabilization in operating parameters of the HVAC system100(e.g., working fluid suction pressure), in some embodiments. For example, the increased length of time may enable the HVAC system100to more adequately or completely detect and/or assess operating parameters of the HVAC system100, such as a load or demand (e.g., cooling load) on the HVAC system100.

In response to a determination that the flag counter is not less than or equal to (e.g., is greater than) the flag limit, the method198may proceed to block254. At block254, the controller116may set (e.g., establish) the NTSP (e.g., future TSP value, subsequent TSP value, expected TSP value) as an updated value. The updated or new value of the NTSP may be determined by adding the differential pressure value (ΔP) (e.g., increment, predetermined value, fixed value, first differential pressure value) discussed above to the TSP (e.g., current TSP, designated at block214). The updated value of the NTSP may be stored in the memory device120for reference during later operation of the method198(e.g., during a current operating cycle of the HVAC system100, during a subsequent operating cycle of the HVAC system100). Additionally, at block254, a value of the flag counter (e.g., stored in the memory device120and/or database122) may be reset to a value of zero.

From block254, the method198may continue to block256, whereby the NTSP (e.g., updated NTSP value determined at block254) may be compared to a maximum allowable suction pressure value. For example, the controller116may be configured to compare the NTSP to the maximum allowable suction pressure value. The maximum allowable suction pressure value may also be a value stored in the memory device120and/or database122. In some embodiments, the maximum allowable suction pressure value may be a predetermined value that is designated based on any suitable parameters or factors, such as a type of the compressor102, a capacity of the compressor102, a configuration of the HVAC system100, other operating conditions or limits of the HVAC system100, testing data, empirical data, regulatory standards, target or desired operating (e.g., efficiency) metrics, or any combination thereof.

In response to a determination that the NTSP (e.g., future TSP value, subsequent TSP value, expected TSP value) is less than or equal to the maximum allowable suction pressure value, the method198may proceed to block220of the first control scheme200discussed above with reference toFIG.6. From block220, the method198may continue (e.g., resume) operation of the first control scheme200in the manner discussed above. In response to a determination that the NTSP is not less than or equal to (e.g., is greater than) the maximum allowable suction pressure, the method198may proceed to block258. At block258, the maximum allowable suction pressure may be set or established as the NTSP. For example, the controller116may store a value of the maximum allowable suction pressure as the NTSP in the memory device120and/or database122. In this way, operation of the HVAC system100at working fluid suction pressures greater than the maximum allowable suction pressure may be avoided. From block258, the method198may proceed to block220of the first control scheme200discussed above.

Returning to block232, in response to a determination that the difference between the additional frequency (F2) and the frequency (F1) is equal to zero, the method198may proceed to block260. At block260, an actual suction pressure of the HVAC system100may be compared to the lower suction pressure limit (e.g., determined at block206). For example, the controller116may receive feedback from the second sensor132indicative of a detected (e.g., current, actual) working fluid suction pressure upstream of the compressor102, and the controller116may compare the measured working fluid suction pressure to the lower suction pressure limit, which may be stored in the memory device120. In particular, the controller116may determine whether the measured working fluid suction pressure is less than the lower suction pressure limit.

In response to a determination that the measured working fluid suction pressure is not less than the lower suction pressure limit, the method198may proceed to block218of the first control scheme200discussed above with reference toFIG.6. From block218, the method198may continue (e.g., resume) operation of the first control scheme200in the manner discussed above. In response to a determination that the measured working fluid suction pressure is less than the lower suction pressure limit, the method198may proceed to block262. At block262, a duration of the timer (Tcheck) discussed above with reference to blocks224,226, and228may be adjusted. For example, the duration of the timer (Tcheck) may be adjusted from the first duration of time utilized in the first control scheme200to a third duration of time (e.g., different from the second duration of time discussed above). In some embodiments, the third duration of time may be greater or longer than the first duration of time and greater or longer than the second duration of time. For example, the third duration of time may be approximately 500 seconds, 550 seconds, 600 seconds, 650 seconds, or another suitable duration of time that is greater than the first duration of time and the second duration of time. The updated duration of time of the timer (e.g., timer124, third timer) may be stored in the memory device120and/or the database122(e.g., Tstable).

After block262, the method198may proceed to block224of the first control scheme200discussed above with reference toFIG.6. From block224, the method198may continue (e.g., resume) operation of the first control scheme200in the manner discussed above. As similarly discussed above, the continued operation of first control scheme200may utilize the timer (Tstable) instead of the timer (Tcheck). Thus, operation of the method198(e.g., execution of blocks224,226, and228) may extend a greater length of time. The lapse of a greater length of time during execution of blocks224,226, and228may enable extended operation of the compressor102according to a particular TSP in instances when the additional frequency (F2) at the end of the timer (e.g., block228) is not greater than and the frequency (F1) at the start of the timer (e.g., block226). For example, an unexpected change in operating conditions of the HVAC system100(e.g., a decrease in ambient temperature) may cause a change in operating parameters of the HVAC system100, and the increased length of time may enable stabilization of the operating parameters and/or conditions of the HVAC system100.

FIG.8is a process flow diagram of an embodiment of the method198(e.g., control sequence, one or more control sequences) for operating the HVAC system100(e.g., the compressor102) to enable modulated operation of the compressor102and thereby enable more efficient operation of the HVAC system100. In particular, the illustrated embodiment depicts an embodiment of the third control scheme212of the method198. As discussed above, the method198includes block208, whereby the controller116may determine whether an NTSP value (e.g., future TSP value, subsequent TSP value, expected TSP value) of the HVAC system100equals zero. The NTSP value may be stored in the memory device120and/or the database122and may be referenced by the controller116at block208. In some instances, the NTSP value may be a value (e.g., a non-zero value) stored in the memory device120and may be associated with a previous (e.g., most recent) operating cycle of the HVAC system. For example, the NTSP value referenced at block208may be the last NTSP value determined by the HVAC system100during a most recent operating cycle. In other instances, the NTSP value may have a value of zero. For example, the NTSP may have a value of zero subsequent to a power interruption to the HVAC system100and/or subsequent to a hard reset of the HVAC system100.

Based on a determination (e.g., via the controller116) that the NTSP value does not equal zero at block208, the method198may proceed to block210. At block210, the controller116may set (e.g., establish) an updated value as the NTSP. The updated or new value of the NTSP may be determined by adding an additional differential pressure value (ΔPy) (e.g., additional increment, additional predetermined value, additional fixed value, second differential pressure value) to the NTSP (e.g., previous NTSP, most recent NTSP) stored in the memory device120. The additional differential pressure value may be an additional target pressure reduction value. In some embodiments, the additional differential pressure value may be stored in the memory device120(e.g., database122) and may be referenced by the controller116to perform the step at block210.

Additionally, the additional differential pressure value (ΔPy) may be greater than the differential pressure value (ΔP) discussed above with respect to block218. The additional differential pressure value may be any suitable value having any suitable units (e.g., 0.02 MPa, 0.03 MPa, 0.04 MPa, or any other suitable value). The additional differential pressure value may be greater than the differential pressure value and may be added to the NTSP, because at block210the method198utilizes the NTSP stored on the memory device120that is associated with a prior operation of the HVAC system100. In other words, the NTSP stored on the memory device120and utilized at block210may be an NTSP value generated during prior execution of the method198during previous operation of the HVAC system100to satisfy a prior call for cooling. Thus, as will be appreciated, the prior NTSP value may be a relatively low suction pressure value. Accordingly, the NTSP value may be increased at block210to enable more efficient operation of the HVAC system100(e.g., the compressor102) without setting the NTSP as the upper suction pressure limit (e.g., block214), in some instances. The updated value of the NTSP determined at block210may be stored in the memory device120and/or database122.

Following block210, the method198may proceed to block280. At block280, the NTSP (e.g., updated NTSP established at block210) may be compared to a maximum allowable suction pressure value, which may be the same maximum allowable suction pressure value referenced at block256. For example, the controller116may be configured to compare the NTSP to the maximum allowable suction pressure value. The maximum allowable suction pressure value may also be a value stored in the memory device120and/or database122. In some embodiments, the maximum allowable suction pressure value may be a predetermined value that is designated based on any suitable parameters or factors, such as a type of the compressor102, a capacity of the compressor102, a configuration of the HVAC system100, other operating conditions or limits of the HVAC system100, testing data, empirical data, regulatory standards, target or desired operating (e.g., efficiency) metrics, or any combination thereof.

In response to a determination that the NTSP is not greater than or equal to (e.g., is less than) the maximum allowable suction pressure value, the method198may proceed to block224of the first control scheme200discussed above with reference toFIG.6. From block224, the method198may continue (e.g., resume) operation of the first control scheme200in the manner discussed above. In response to a determination that the NTSP is greater than or equal to the maximum allowable suction pressure value, the method198may proceed to block282. At block282, the maximum allowable suction pressure value may be established or set as the TSP (e.g., TSP value), such as by the controller116. Thus, the method198may avoid operation of the HVAC system100with a TSP that is greater than the maximum allowable suction pressure value of the HVAC system100. Thereafter, the method198may proceed to block218of the first control scheme200, and the method198may continue (e.g., resume) operation of the first control scheme200in the manner discussed above.

As discussed above, at block206of the method198, an upper suction pressure limit and a lower suction pressure limit within which the compressor102and/or HVAC system100is to be operated may be determined, such as by the controller116. In some embodiments, the upper suction pressure limit and/or the lower suction pressure limit may be determined and/or selected based on predetermined values stored in the memory device120. Additionally or alternatively, the upper suction pressure limit and/or the lower suction pressure limit may be determined based on one or more equations that may be stored in the memory device120. In some embodiments, the upper suction pressure limit and/or the lower suction pressure limit may be determined based on a detected or determined operating parameter or characteristic of the HVAC system100.

FIG.9is a process flow diagram of an embodiment of a method300for determining the upper suction pressure limit and the lower suction pressure limit of the HVAC system100, in accordance with aspects of the present disclosure. For example, the method300may be executed (e.g., via the controller116) at block206of the method198discussed above. The method300may begin at block302, which includes comparing an outdoor ambient temperature to a threshold temperature (e.g., threshold temperature value). However, it should be appreciated that other operating parameters of the HVAC system100and corresponding thresholds may be referenced and compared at block302. The outdoor ambient temperature may be a measured temperature detected by the HVAC system100. For example, the first sensor130of the one or more sensors128may be configured to measure or detect the outdoor ambient temperature and provide data or feedback indicative of the outdoor ambient temperature measurement (e.g., value) to the controller116. The controller116may be configured to reference the memory device120(e.g., database122) to identify the threshold temperature. The threshold temperature may be any suitable temperature value, such as 27° C., 28° C., 29° C., 30° C., 31° C., or another suitable temperature value.

In response to a determination that the measured outdoor ambient temperature value is greater than or equal to the threshold temperature, the method300may proceed to block304, whereby the controller116may determine the upper suction pressure limit and a lower suction pressure limit according to a first scheme (e.g., first calculation, first designation, first convention). In response to a determination that the measured outdoor ambient temperature value is less than the threshold temperature, the method300may proceed to block306, whereby the controller116may determine the upper suction pressure limit and the lower suction pressure limit according to a second scheme (e.g., second calculation, second designation, second convention). In some embodiments, the first scheme of block304and the second scheme of block306may determine both the upper suction pressure limit and the lower suction pressure limit in different manners. In other embodiments, the first scheme of block304and the second scheme of block306may determine one the upper suction pressure limit and the lower suction pressure limit in a similar manner and may determine the other of the upper suction pressure limit and the lower suction pressure limit in a different manner.

For example, at block304, the controller116may be configured to determine the upper suction pressure limit according to an equation associated with the first scheme, such as Equation (1) below.

As indicated by Equation (1), the outdoor ambient temperature value (e.g., measured by the first sensors130) may be utilized as an input to Equation (1). K1and K2may be values (e.g., constant values) that are determined based on empirical data and/or testing data related to the HVAC system100. Values of K1and K2may be different for different HVAC system100configurations (e.g., having different configurations and/or types of compressors102). The respective values of K1and K2may be stored in the memory device120(e.g., database122) and may be referenced by the controller116during execution of the step at block304and utilized as inputs for Equation (1). Equation (1) also includes ΔPtgt as an input. The value of ΔPtgt may also be stored in the memory device120(e.g., database122) and may be referenced by the controller116during execution of the step at block304. The value of ΔPtgt may also be any suitable value (e.g., fixed value), such as 0.05 MPa, 0.07 MPa, 0.09 MPa, or any other suitable value. Utilizing the inputs described above, the controller116may calculate the upper suction pressure limit utilizing the Equation (1). However, it should be appreciated that other equations may be utilized to determine the upper suction pressure limit at block304.

At block304, the lower suction pressure limit may also be determined according to the first scheme. In some embodiments of the first scheme, the controller116may determine the lower suction pressure limit based on a value (e.g., fixed value, predetermined value) of the lower suction pressure limit that is stored in the memory device120(e.g., database122). For example, a minimum allowable suction pressure value associated with the HVAC system100(e.g., a type of the HVAC system100, a model of the HVAC system100) may be set or established as the lower suction pressure limit. The minimum allowable suction pressure limit may be determined based on any suitable parameters, such as operational limitations of one or more components of the HVAC system100, desired operating parameters of the HVAC system100, and so forth.

At block306, the controller116may determine the upper suction pressure limit and the lower suction pressure limit according to the second scheme. In some embodiments of the second scheme, the controller116may determine the lower suction pressure limit based on a value (e.g., fixed value, predetermined value) of the lower suction pressure limit that is stored in the memory device120(e.g., database122), which may be the same or different from the value utilized to establish the lower suction pressure limit according to the first scheme. For example, a minimum allowable suction pressure value associated with the HVAC system100may be set as the lower suction pressure limit. Similarly, according to the second scheme, the controller116may determine the upper suction pressure limit based on a value (e.g., fixed value, predetermined value) of the upper suction pressure limit that is stored in the memory device120(e.g., database122). In some embodiments, a maximum allowable suction pressure value associated with the HVAC system100, which may be the same or similar to the maximum allowable suction pressure value discussed above, may be set as the upper suction pressure limit according to the second scheme. In other embodiments, one or more equations may be utilized in the second scheme (e.g., similar to the first scheme) to determine the upper suction pressure limit and/or the lower suction pressure limit.

The present disclosure may provide one or more technical effects useful in the operation of an HVAC system. In particular, the disclosed systems and methods enable to enable variable operation of modulating HVAC equipment, such as a compressor, when the modulating HVAC equipment is utilized with non-modulating (e.g., non-communicating) HVAC equipment, such as a non-communicating thermostat and/or a non-communicating air handler. For example, present embodiments implement a variable target suction pressure, which may be based on an operating parameter of the HVAC system (e.g., outdoor ambient temperature), to enable modulating of the compressor of the HVAC system (e.g., without use of data or feedback typically provided by communicating HVAC equipment). In this way, the disclosed systems and methods enable more efficient operation of the HVAC system to satisfy a load or demand (e.g., a cooling demand) on the HVAC system.

While only certain features and embodiments have been illustrated and described, many modifications and changes may occur to those skilled in the art, such as variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, such as temperatures and pressures, mounting arrangements, use of materials, colors, orientations, and so forth, without materially departing from the novel teachings and advantages of the subject matter recited in the claims. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the disclosure.

Furthermore, in an effort to provide a concise description of the exemplary embodiments, all features of an actual implementation may not have been described, such as those unrelated to the presently contemplated best mode, or those unrelated to enablement. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation specific decisions may be made. Such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure, without undue experimentation.