System and method for operating a variable speed compressor of an air conditioner unit

Abstract

An air conditioner unit includes a variable speed compressor for circulating refrigerant through a refrigeration circuit and a controller configured to initiate a run cycle, initiate a compressor transition timer, and determine an unfiltered compressor speed. The unfiltered compressor speed is fixed based on a selected run mode until the compressor transition timer reaches a predetermined transition delay time, after which a closed loop feedback control algorithm is used to determine the unfiltered compressor speed. The controller is further configured to operate the variable speed compressor at a target compressor speed that is modified from the unfiltered compressor speed based on identification of a speed modification condition, such as identification of insufficient dehumidification, speed limit, or one or more resonance avoidance zones.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to air conditioner units, and more particularly to a method of operating a variable speed compressor of an air conditioner unit. BACKGROUND

[0002] Air conditioner units, or air conditioning units, are commonly used to regulate indoor temperatures, for example, within buildings such as homes and office buildings. Such units typically include a closed refrigeration circuit to heat or cool indoor air. Typically, the indoor air is recirculated while being heated or cooled. Various sizes and configurations are available for such air conditioner units. For example, some units can have one portion installed indoors that is connected to another portion located outdoors, for example, by a pipe or conduit that carries refrigerant. These types of units are commonly used to regulate air in a larger space.

[0003] Another type of air conditioner unit, commonly referred to as a single-package vertical unit (SPVU) or a package terminal air conditioner (PTAC), can be used to regulate the temperature in, for example, a single room or a group of rooms of a building. These units typically operate like a split heat pump system, except that the indoor and outdoor portions are defined by a partition and all system components are housed within a single package that is installed within a wall sleeve located in an opening of an exterior wall of the building. When a conventional PTAC is operating in a cooling or heating mode, the compressor circulates refrigerant within the sealed system, while indoor and outdoor fans respectively force air flow across the indoor and outdoor heat exchangers.

[0004] Notably, the speed of the compressor of an air conditioner unit is often varied according to the conditioning needs of a room. However, certain operating conditions or system characteristics can arise that result in undesirable operating regions of the compressor. For example, the compressor can periodically produce undesirable noise that can disturb room occupants and vibrations that can potentially damage system components and result in early unit failure. These noises can be particularly undesirable for SPVUs, PTACs, or other single-room air conditioners that are installed within or near the room being conditioned. Furthermore, these vibrations can result in premature wear and failure of the compressor or other sealed system components. This can be especially true when the compressor is operated at a speed that corresponds to a resonant frequency of the compressor and / or other components of the air conditioner unit.

[0005] Accordingly, an improved air conditioner unit and method of operation that reduces harmful noise or vibration would be useful. More particularly, a packaged terminal air conditioner unit that regulates compressor operation to avoid operating in undesirable operating regions would be particularly beneficial. SUMMARY

[0006] These and other features, aspects, and advantages of the present application will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the application and, together with the description, serve to explain the principles of the application.

[0007] In one example embodiment, an air conditioner unit is provided that includes a refrigeration circuit including an outdoor heat exchanger and an indoor heat exchanger, a variable speed compressor operably coupled to the refrigeration circuit and configured to cause a flow of refrigerant through the outdoor heat exchanger and the indoor heat exchanger, and a controller operably coupled to the variable speed compressor. The controller is configured to initiate a run cycle, determine an unfiltered compressor speed based at least in part on a sealed system demand, determine that the unfiltered compressor speed falls within a resonance avoidance zone bounded by a minimum resonance frequency and a maximum resonance frequency, identify a target compressor speed that avoids the resonance avoidance zone, and operate the variable speed compressor at the target compressor speed.

[0008] In another example embodiment, a method of operating an air conditioner unit is provided. The air conditioner unit includes a refrigeration circuit and a variable speed compressor operably coupled to the refrigeration circuit and configured to cause a flow of refrigerant through the refrigeration circuit. The method includes initiating a run cycle, determining an unfiltered compressor speed based at least in part on a sealed system demand, determining that the unfiltered compressor speed falls within a resonance avoidance zone bounded by a minimum resonance frequency and a maximum resonance frequency, identifying a target compressor speed that avoids the resonance avoidance zone, and operating the variable speed compressor at the target compressor speed.

[0009] These and other features, aspects, and advantages of the present application will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the application and, together with the description, serve to explain the principles of the application. BRIEF DESCRIPTION OF DRAWINGS

[0010] With reference to the accompanying drawings, a complete and enabling disclosure of the application, including the best mode thereof, is set forth in the description which utilizes reference characters to refer to like elements of the application.

[0011] Figure 1A perspective view of an exemplary air conditioner unit according to one example embodiment of the disclosure is provided, with a portion of the indoor section exploded from the remainder of the air conditioner unit for purposes of illustration.

[0012] Figure 2 is another perspective view of components of the indoor section of the exemplary air conditioner unit of Figure 1

[0013] Figure 3 is a schematic diagram of a refrigeration circuit according to one embodiment of the disclosure.

[0014] Figure 4 is a rear perspective view of the outdoor section of the exemplary air conditioner unit of Figure 1

[0015] Figure 5 is a front perspective view of the exemplary damper of Figure 4

[0016] Figure 6 is a rear perspective view of the exemplary air conditioner unit and damper of Figure 4

[0017] Figure 7 is a side cross-sectional view of the exemplary air conditioner unit of Figure 1

[0018] Figure 8 A method for controlling a variable speed compressor of a packaged terminal air conditioner unit according to one embodiment of the disclosure is shown.

[0019] Figure 9 A method for controlling a variable speed compressor of a packaged terminal air conditioner unit according to another embodiment of the disclosure is shown.

[0020] The repeated use of reference characters in the present specification and drawings is intended to represent the same or similar features or elements of the application. DETAILED DESCRIPTION

[0021] ​​​​​Reference will now be made in detail to embodiments of the application, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the application and is not meant as a limitation of the application. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present application without departing from the scope or spirit of the application. For instance, features illustrated or described as part of one embodiment, can be used with another embodiment to yield still a further embodiment. Thus, it is intended that the present application covers modifications and variations of this application provided they come within the scope of the appended claims and their equivalents.

[0022] Reference will now be made in detail to embodiments of the application, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the application and is not meant as a limitation of the application. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present application without departing from the scope or spirit of the application. For instance, features illustrated or described as part of one embodiment, can be used with another embodiment to yield still a further embodiment. Thus, it is intended that the present application covers modifications and variations of this application provided they come within the scope of the appended claims and their equivalents. Figure 1 Figure 2 An air conditioner unit 10 is provided, now with reference to

[0023] The housing 20 of the unit 10 can house various other components of the unit 10. The housing 20 can include, for example, a rear grille 22 and a room front 24, which can be spaced apart along the transverse direction T by a through-the-wall sleeve 26. The rear grille 22 can be part of the outdoor portion 14, and the room front 24 can be part of the indoor portion 12. Components of the outdoor portion 14, such as an outdoor heat exchanger 30, an outdoor fan 32, and a compressor 34 can be housed within the through-the-wall sleeve 26. As shown, a fan shroud 36 can additionally enclose the outdoor fan 32.

[0024] The indoor portion 12 can include, for example, an indoor heat exchanger 40, a blower fan or indoor fan 42, and a heating unit 44. These components can be housed, for example, behind the room front 24. Additionally, a bulkhead 46 can generally support and / or house various other components or portions thereof of the indoor portion 12, such as the indoor fan 42 and the heating unit 44. The bulkhead 46 can generally separate and define the indoor portion 12 and the outdoor portion 14.

[0025] The outdoor heat exchanger 30 and the indoor heat exchanger 40 can be components of a sealed system or refrigeration circuit 48, which is described in greater detail in Figure 3 ​The refrigeration circuit 48 can further include, for example, the compressor 34 and the expansion device 50. As shown, the compressor 34 and the expansion device 50 can be in fluid communication with the outdoor heat exchanger 30 and the indoor heat exchanger 40 for the flow of refrigerant therethrough, as generally understood. More specifically, the refrigeration circuit 48 can include various lines for the flow of refrigerant between the various components of the refrigeration circuit 48, thereby providing fluid communication therebetween. Thus, refrigerant can flow from the indoor heat exchanger 40 to the compressor 34, from the compressor 34 to the outdoor heat exchanger 30, from the outdoor heat exchanger 30 to the expansion device 50, and from the expansion device 50 to the indoor heat exchanger 40 through such lines. As the refrigerant flows to and through these various components, the refrigerant can generally undergo phase changes associated with a refrigeration cycle, as generally understood. Suitable refrigerants for use in the refrigeration circuit 48 can include pentafluoroethane, difluoromethane, or mixtures such as R410a, although it should be understood that the present disclosure is not limited to such examples, but can utilize any suitable refrigerant.

[0026] As understood in the art, the refrigeration circuit 48 can alternately operate as a refrigeration assembly (and thus perform a refrigeration cycle) or as a heat pump (and thus perform a heat pump cycle). As Figure 3 shown, when the refrigeration circuit 48 operates in a cooling mode and thus performs a refrigeration cycle, the indoor heat exchanger 40 acts as an evaporator and the outdoor heat exchanger 30 acts as a condenser. Alternatively, when the assembly operates in a heating mode and thus performs a heat pump cycle, the indoor heat exchanger 40 acts as a condenser and the outdoor heat exchanger 30 acts as an evaporator. The outdoor heat exchanger 30 and the indoor heat exchanger 40 can each include a coil through which refrigerant can flow for heat exchange purposes, as generally understood.

[0027] According to exemplary embodiments, the compressor 34 can be a variable speed compressor. In this regard, the compressor 34 can operate at various speeds depending on the current air conditioning needs of the room and the needs from the refrigeration circuit 48. For example, according to exemplary embodiments, the compressor 34 can be configured to operate at any speed between a minimum speed, for example, 1500 revolutions per minute (RPM), and a maximum rated speed, for example, 3500 RPM. Notably, the use of a variable speed compressor 34 enables efficient operation of the refrigeration circuit 48 (and thus the air conditioner unit 10), minimizes unnecessary noise when the compressor 34 does not need to operate at full speed, and ensures a comfortable environment within the room.

[0028] In particular, according to example embodiments, the compressor 34 can be a variable speed compressor. In this regard, the compressor 34 can include power inverters, power electronics, rectifiers, or other control electronics suitable for converting alternating current (AC) power input into direct current (DC) power for the compressor. The inverter electronics can adjust the DC power output to any suitable DC voltage corresponding to a particular operating speed of the compressor. In this manner, the compressor 34 can be adjusted to any suitable operating speed, e.g., from 0% to 100% of the full rated power and / or speed of the compressor. This can facilitate the compressor operating precisely at a desired operating power and speed to meet system demands, while maximizing efficiency and minimizing unnecessary system cycling, energy usage, and noise.

[0029] In the example embodiments as shown, the expansion device 50 can be disposed in the outdoor portion 14 between the indoor heat exchanger 40 and the outdoor heat exchanger 30. According to example embodiments, the expansion device 50 can be an electronic expansion valve capable of achieving controlled expansion of the refrigerant, as is known in the art. More particularly, the electronic expansion device 50 can be configured to precisely control the expansion of the refrigerant to maintain a desired temperature differential of the refrigerant across the indoor heat exchanger 40, for example. In other words, the electronic expansion device 50 throttles the flow of refrigerant based on a reaction of the amount of temperature differential or superheat differential across the indoor heat exchanger 40 to ensure that the refrigerant enters the compressor 34 in a gaseous state. According to alternative embodiments, the expansion device 50 can be a capillary tube or another suitable expansion device configured for a vapor compression cycle.

[0030] According to the example embodiments as shown, the outdoor fan 32 is an axial fan, while the indoor fan 42 is a centrifugal fan. However, it should be appreciated that according to alternative embodiments, the outdoor fan 32 and the indoor fan 42 can be any suitable fan type. Moreover, according to example embodiments, the outdoor fan 32 and the indoor fan 42 are variable speed fans, e.g., similar to the variable speed compressor 34. For example, the outdoor fan 32 and the indoor fan 42 can rotate at different rotational speeds to produce different air flow rates. It can be desirable to operate the fans 32, 42 at less than their maximum rated speeds to ensure that the refrigeration circuit 48 is safely and properly operated at less than its maximum rated speed, e.g., to reduce noise when full speed operation is not required. Moreover, according to alternative embodiments, the fans 32, 42 can be operated to induce supplemental air into the room.

[0031] According to the illustrated embodiment, the indoor fan 42 can operate as an evaporator fan in the refrigeration circuit 48 to facilitate airflow through the indoor heat exchanger 40. Thus, the indoor fan 42 can be positioned downstream of the indoor heat exchanger 40 and downstream of the heating unit 44 along the flow direction of the indoor air. Alternatively, the indoor fan 42 can be positioned upstream of the indoor heat exchanger 40 along the flow direction of the indoor air and can operate to cause air to pass through the indoor heat exchanger 40.

[0032] The heating unit 44 in the example embodiment includes one or more heater banks 60. Each heater bank 60 can operate to generate heat as needed. In some embodiments as illustrated, three heater banks 60 can be utilized. However, alternatively, any suitable number of heater banks 60 can be utilized. Each heater bank 60 can further include at least one heater coil or coil channel 62, such as two heater coils or coil channels 62 in the example embodiment. Alternatively, other suitable heating elements can be utilized.

[0033] Operation of the air conditioner unit 10 including the compressor 34 (and thus generally the refrigeration circuit 48), the indoor fan 42, the outdoor fan 32, the heating unit 44, the expansion device 50, and other components of the refrigeration circuit 48 can be controlled by a processing device such as a controller 64. The controller 64 can be in communication with such components of the air conditioner unit 10 (e.g., via suitable wired or wireless connections). The controller 64 can include a memory and one or more processing devices, such as a microprocessor, CPU, or the like, such as a general purpose or special purpose microprocessor, operable to execute programmed instructions or microcontrol code relating to operation of the unit 10. The memory can represent random access memory, such as DRAM, or read only memory, such as ROM or flash memory. In one embodiment, the processor executes programmed instructions stored in the memory. The memory can be a separate component from the processor, or can be included on board within the processor.

[0034] The unit 10 can additionally include a control panel 66 and one or more user inputs 68, which can be included in the control panel 66. The user inputs 68 can be in communication with the controller 64. A user of the unit 10 can interact with the user inputs 68 to operate the unit 10, and user commands can be transmitted between the user inputs 68 and the controller 64 to facilitate operation of the unit 10 based on such user commands. A display 70 can additionally be provided in the control panel 66 and can be in communication with the controller 64. The display 70 can be, for example, a touchscreen or other textually readable display screen, or alternatively can simply be a light that can be activated and deactivated as needed to provide an indication of, for example, an event or setting of the unit 10.

[0035] Briefly referring to Figure 4In one embodiment, a vent 80 may be defined in the partition 46 for providing fluid communication between the indoor portion 12 and the outdoor portion 14. The vent 80 may be used in an already installed air conditioner unit 10 to allow outdoor air to flow into the room through the indoor portion 12. In this regard, in some circumstances, it may be desirable to allow outside air (i.e., "make-up air") to flow into the room in order to, for example, meet government regulations, compensate for negative pressure created within the room, etc. In this manner, according to an exemplary embodiment, make-up air may be provided to the room through the vent 80 when needed.

[0036] like Figure 5 As shown, a vent door 82 can be pivotally mounted to the partition 46 near the vent 80 to open and close the vent 80. More specifically, as shown, the vent door 82 is pivotally mounted to the indoor-facing surface of the indoor portion 12. The vent door 82 can be configured to pivot between a first closed position in which the vent door 82 blocks air from flowing between the outdoor portion 14 and the indoor portion 12, and a second open position in which the vent door 82 is in an open position (e.g., Figure 5 According to the embodiment shown, the vent door 82 can be pivoted between the open and closed positions by a motor 84 controlled by the controller 64 or by any other suitable method.

[0037] In some cases, it may be desirable to treat or condition the make-up air flowing through vent 80 before it is blown into the room. For example, outdoor air with a relatively high humidity level may need to be treated before it enters the room. Furthermore, if the outdoor air is cold, it may be desirable to heat the air before it is blown into the room. Therefore, according to an exemplary embodiment of the present subject matter, unit 10 may further include a secondary seal system located above vent 80 for conditioning the make-up air. The secondary seal system may be a small seal system that functions similarly to refrigeration circuit 48, but only conditions the air flowing through vent 80. According to alternative embodiments (such as those described herein), make-up air may be forced through vent 80 without the aid of a secondary seal system. Instead, the make-up air forced through vent 80 may be at least partially conditioned by refrigeration circuit 48, for example, by passing through indoor heat exchanger 40. Furthermore, the make-up air may be conditioned immediately upon entering through vent 80, or after being combined with the air flow introduced through indoor heat exchanger 40.

[0038] Now refer to Figure 6A fan assembly 100 will be described in accordance with one exemplary embodiment of the present subject matter. In accordance with the illustrated embodiment, the fan assembly 100 is generally configured to facilitate the flow of supplemental air through the vent 80 and into the conditioned room without the aid of an auxiliary sealing system. However, it should be appreciated that the fan assembly 100 can be used in conjunction with a supplemental air module that includes an auxiliary sealing system for regulating the flow of supplemental air. As illustrated, the fan assembly 100 includes an auxiliary fan 102 for facilitating the flow of supplemental air through a fan duct 104 and through the vent 80 into the indoor portion 12.

[0039] In accordance with the illustrated embodiment, the auxiliary fan 102 is an axial fan positioned at the inlet of the fan duct 104 (e.g., upstream of the vent 80). However, it should be appreciated that any other suitable number, type, and configuration of fan or blower can be used to facilitate the flow of supplemental air in accordance with alternative embodiments. Moreover, the auxiliary fan 102 can be positioned at any other suitable location within the air conditioner unit 10, and the auxiliary fan 102 can be positioned within the fan duct 104 or at any other suitable location in fluid communication with the fan duct. The embodiments described herein are merely exemplary and are not intended to limit the scope of the present subject matter.

[0040] Reference will now be made to Figure 7 Operation of the unit 10 will be described in accordance with exemplary embodiments. More specifically, operation of components within the indoor portion 12 during a cooling operation or cooling cycle of the unit 10 will be described. To simplify the discussion, operation of the auxiliary fan 102 that provides supplemental air through the vent 80 will be omitted, e.g., as if the vent door 82 were closed. Although a cooling cycle will be described, it should be further appreciated that the indoor heat exchanger 40 and / or the heating unit 44 are used to heat indoor air in accordance with alternative embodiments. Moreover, although operation of the unit 10 is described below with respect to an exemplary packaged terminal air conditioner unit, it should be further appreciated that aspects of the present subject matter can be used in any other suitable air conditioner unit, such as a heat pump or a split system unit.

[0041] As illustrated, the room front 24 of the unit 10 generally defines an intake 110 and an exhaust 112 for circulating air flow (indicated by arrows 114) throughout the room. In this regard, the indoor fan 42 is generally configured to draw air 114 in through the intake 110 and facilitate the flow of air through the indoor heat exchanger 40 before expelling the air 114 out of the exhaust 112. In accordance with the illustrated embodiment, the intake 110 is located near the bottom of the unit 10 and the exhaust 112 is located near the top of the unit 10. However, it should be appreciated that the intake 110 and the exhaust 112 can have any other suitable size, shape, location, or configuration in accordance with alternative embodiments.

[0042] During a cooling cycle, the refrigeration circuit 48 is generally configured to cause cool refrigerant to pass through the indoor heat exchanger 40 to reduce the temperature of the air stream 114 before discharging the air stream back into the room. In particular, during a cooling operation, the controller 64 can be provided with a target temperature, e.g., as set by a user for a desired room temperature. Generally, the components of the refrigeration circuit 48, the outdoor fan 32, the indoor fan 42, and other components of the unit 10 operate to continuously cool the air stream.

[0043] To facilitate operation of the refrigeration circuit 48 and other components of the unit 10, the unit 10 can include various sensors for detecting conditions internal and external to the unit 10. These conditions can be fed to the controller 64, which can make decisions regarding operation of the unit 10 to correct for undesirable conditions or otherwise adjust the air stream 114 entering the room. For example, as best shown in FIG. 1, the unit 10 can include an outdoor temperature sensor 124 positioned and configured to measure an outdoor temperature. In this way, the unit 10 can be used to adjust the air stream 114 entering the room until the measured outdoor temperature reaches a desired target temperature. Figure 7

[0044] As used herein, a "temperature sensor" or equivalent is intended to be any suitable type of temperature measurement system or device positioned at any suitable location for measuring a desired temperature. Thus, for example, the temperature sensors 120 can each be any suitable type of temperature sensor, such as a thermistor, a thermocouple, a resistance temperature detector, a semiconductor-based integrated circuit temperature sensor, etc. Further, the temperature sensors 120 can be positioned at any suitable location and can output a signal, such as a voltage, to the controller that is proportional to and / or indicative of the temperature being measured. Although exemplary positions of the temperature sensors are described herein, it should be understood that the unit 10 can include any other suitable number, type, and position of temperature sensors, humidity sensors, and / or other sensors according to alternative embodiments.

[0045] ​As used herein, the term "humidity sensor" or equivalent can be intended to designate any suitable type of humidity measurement system or device positioned at any suitable location for measuring a desired humidity. Thus, for example, the humidity sensor 122 can refer to any suitable type of humidity sensor, such as a capacitive digital sensor, a resistive sensor, and a thermal conductivity humidity sensor. Moreover, the humidity sensor 122 can be positioned at any suitable location, and can output a signal, such as a voltage, to the controller that is proportional to and / or indicative of the measured humidity. Although exemplary positions of the humidity sensor are described herein, it will be appreciated that the unit 10 can include any other suitable number, type, and position of humidity sensors according to alternative embodiments.

[0046] Having now presented the configuration of the air conditioner unit 10 and the configuration of the controller 64 according to exemplary embodiments, exemplary methods 200, 300 of operating the packaged terminal air conditioner unit will be described. Although the following discussion relates to exemplary methods 200, 300 of operating the air conditioner unit 10, it will be appreciated by those skilled in the art that the exemplary methods 200, 300 are applicable to the operation of various other air conditioning equipment. In exemplary embodiments, various method steps as disclosed herein can be performed by the controller 64 or a separate dedicated controller.

[0047] Reference is now made to Figure 8 The method 200 includes, at step 210, initiating an operating cycle of the air conditioner unit. In this regard, for example, the air conditioner unit 10 can be triggered to begin performing an air conditioning process, for example, by selectively operating the compressor 34, the outdoor fan 32, the indoor fan 42, etc., to facilitate heat pump operation and heating or cooling of the indoor air 114. Initiation of the operating cycle can be triggered by any suitable source in any suitable manner, and can correspond to any suitable sealing system requirement, as described below according to exemplary embodiments.

[0048] In this regard, for example, the operating cycle can be initiated by a thermostat based at least in part on a difference between a measured temperature (e.g., as measured by the indoor temperature sensor 120) and a temperature setpoint for the room being air conditioned. In this regard, if the measured temperature differs from the temperature setpoint by more than a predetermined amount, the unit 10 can initiate the operating cycle to cause the measured temperature to approach the temperature setpoint. According to exemplary embodiments, the operating cycle can also be initiated directly by a user of the unit 10, for example, via manipulation of the control panel 66.

[0049] According to example embodiments, the sealed system demand can vary depending on the heating or cooling capacity demand within a particular room. Generally, the sealed system demand will typically vary proportionally with the corresponding sealed system component speed and the desired temperature rate of change. In this regard, a higher sealed system demand can correspond to increased compressor speed, increased fan speed, etc. to increase the ability of the unit 10 to quickly condition the room. In contrast, a lower sealed system demand can correspond to decreased compressor speed, fan speed, etc. for example, when the measured temperature is close to the target temperature and lower power consumption and noise generation is desired.

[0050] It will be appreciated that, according to example embodiments, the heating / cooling capacity or sealed system demand can vary based on the magnitude of the temperature difference between the measured temperature and the target temperature or temperature setpoint. Thus, for example, if the temperature difference exceeds a lower difference threshold (e.g., plus or minus 2 degrees Fahrenheit), a run cycle can be initiated with low sealed system demand (e.g., a low level run cycle in which the compressor 34, outdoor fan 32, and indoor fan 42 are run at a lower speed). In contrast, if the temperature difference exceeds a higher difference threshold (e.g., plus or minus 4 degrees Fahrenheit), the sealed system demand can be higher (e.g., a high level run cycle in which the compressor 34, outdoor fan 32, and indoor fan 42 are run at a higher speed).

[0051] According to yet other embodiments, the heating or cooling capacity or sealed system demand of the run cycle can be directly manipulated by a user of the unit 10. In this regard, for example, the user can directly manipulate the control panel 66 to increase or decrease the intensity of the run cycle or sealed system demand. Thus, if the user desires to quickly cool the room, the user can select the user input 68 corresponding to the maximum cooling capacity or highest level of sealed system demand. It will be appreciated that the run cycle can be executed in an open loop manner or can rely on temperature and humidity feedback (e.g., receiving the indoor temperature sensor 120 and / or indoor humidity sensor 122).

[0052] Notably, at the beginning of the run cycle, when the compressor 34 first begins circulating refrigerant flow within the refrigerant circuit 48, the unit 10 can have little or no impact on the temperature within the air conditioned room. Specifically, the cooling capacity of the sealed system can take several minutes to take effect. Thus, it can not be desirable to immediately begin operating the sealed system in a closed loop manner, as this can result in undesirably high run speeds. Accordingly, the step 210 can include initiating a compressor transition timer, e.g., contemporaneously with initiating the compressor 34. As will be described in greater detail below, the compressor speed of the variable speed compressor 34 can be determined based at least in part on the compressor transition timer.

[0053] Specifically, step 220 generally includes determining an unfiltered compressor speed of the variable speed compressor based at least in part on the compressor conversion timer. As used herein, "unfiltered compressor speed" can generally refer to a target compressor speed that is primarily based on the sealed system demand (e.g., how quickly the room should be heated / cooled). In this regard, for example, at the beginning of a run cycle, the variable speed compressor 34 can operate at a fixed compressor speed. As noted above, the fixed compressor speed can vary based on the sealed system demand, for example, based on the heating or cooling capacity required by the unit 10. In this regard, the sealed system demand can be at a low level, a high level, an intermediate level, or any other suitable operating level, and the fixed compressor speed can vary accordingly.

[0054] For example, at the beginning of a run cycle, when the temperature differential between the measured temperature and the setpoint temperature is relatively small, the sealed system demand can be low. Accordingly, the fixed compressor speed can be between about 800 and 2800 revolutions per minute, between about 1000 and 2600 revolutions per minute, between about 1200 and 2400 revolutions per minute, between about 1500 and 2100 revolutions per minute, or about 1800 revolutions per minute.

[0055] In contrast, if the temperature differential between the measured temperature and the setpoint temperature is relatively large at the beginning of a run cycle, the sealed system demand can be high. Accordingly, the fixed compressor speed can be between about 2600 and 4600 revolutions per minute, between about 2800 and 4400 revolutions per minute, between about 3000 and 4200 revolutions per minute, between about 3300 and 3900 revolutions per minute, or about 3600 revolutions per minute. It should be appreciated that these fixed operating speeds are merely exemplary and can vary while remaining within the scope of the present subject matter. Further, it should be appreciated that although only two operating modes or levels are described, the unit 10 can operate at any other suitable intermediate operating level while remaining within the scope of the present subject matter.

[0056] Notably, after the sealed system begins to properly heat / cool the room, it can be desirable to transition to a more active closed-loop control system. In this regard, the closed-loop control system can rely on temperature and / or humidity feedback from one or more system sensors (e.g., such as indoor temperature sensor 120 and indoor humidity sensor 122). Accordingly, method 200 can further include determining that a compressor transition timer (e.g., initiated at the beginning of the run cycle in step 210) has exceeded a predetermined transition delay time. Generally, the predetermined transition delay time can correspond to the amount of time it takes for the sealed system to begin effectively heating or cooling the room. This predetermined transition delay time can be set by a user or manufacturer, can be determined empirically, or can be set in any other suitable manner. For example, according to exemplary embodiments, the predetermined transition delay time can be between about 30 seconds and 10 minutes, between about 1 minute and 5 minutes, between about 2 minutes and 4 minutes, or about 3 minutes. Other transition delay times are possible and within the scope of the present subject matter.

[0057] Notably, step 220 of determining an unfiltered compressor speed of the variable speed compressor based at least in part on the current compressor transition timer can include determining the unfiltered compressor speed based on a closed-loop feedback control algorithm upon determining that the compressor transition timer has exceeded the predetermined transition delay time. For example, according to exemplary embodiments, the closed-loop feedback control algorithm can include a proportional control algorithm, a proportional-integral control algorithm (e.g., a PI controller), or a proportional-integral-derivative control algorithm (e.g., a PID controller).

[0058] Generally, the closed-loop feedback control algorithm can operate the compressor 34 to minimize the difference between the measured indoor temperature and the setpoint temperature. In this regard, implementation of the closed-loop feedback control algorithm can include obtaining the indoor temperature (e.g., using indoor temperature sensor 120), determining an error value between the indoor temperature and the setpoint temperature, and passing or inputting the error value into the closed-loop feedback control algorithm to produce the unfiltered compressor speed as a control input to minimize the error. Details regarding operation of the closed-loop feedback control algorithm are generally well known in the art and further detailed discussion will be omitted here for brevity.

[0059] Notably, step 220 generally results in an unfiltered compressor speed, which can generally correspond to a desired speed of the variable speed compressor 34 for effectively heating, cooling, and / or dehumidifying a room in which the unit 10 is located. However, during operation of the unit 10, there can be certain conditions or certain operational characteristics that can arise that can make it desirable to modify the unfiltered compressor speed. Accordingly, step 230 can generally include identifying a speed modification condition, such as a dehumidification deficiency, a speed limit, or an identification of one or more resonance avoidance zones, each of which will be described in greater detail below.

[0060] Further, step 240 can include generating a target compressor speed based at least in part on the unfiltered compressor speed and the identification of the speed modification condition. According to exemplary embodiments, step 250 can include operating the variable speed compressor at the target compressor speed. Notably, the target compressor speed can be modified from the unfiltered compressor speed, and such modification can depend on the speed modification condition detected at step 230. Various speed modification conditions and their respective effects on the unfiltered compressor speed will be described below according to exemplary embodiments of the present subject matter. However, it should be appreciated that other speed modification conditions are possible and within the scope of the present subject matter.

[0061] According to exemplary embodiments, the identification of the speed modification condition can generally include identifying a dehumidification deficiency. In this regard, a dehumidification deficiency can generally refer to a situation in which the room is not being properly dehumidified by the unit 10, or a situation in which the dehumidification process is inefficient or not needed to be performed. For example, the method 200 can include measuring a humidity of the conditioned room (e.g., using the indoor humidity sensor 122) and determining that the measured humidity exceeds a predetermined humidity threshold. According to alternative embodiments, the unit 10 can use the indoor humidity sensor 122 to identify a dehumidification rate, and can compare the dehumidification rate to a target dehumidification rate to determine whether the unit 10 is properly dehumidifying the room.

[0062] As noted above, for example, under certain conditions where the compressor 34 needs to run at a higher speed to properly cool the indoor heat exchanger to remove moisture from the air, a dehumidification deficiency can arise. Thus, if the unfiltered compressor speed (e.g., determined at step 220) is too low to facilitate this dehumidification process, the identification of a dehumidification deficiency can result in the implementation of a floor speed limit or lower speed limit for the compressor 34. Thus, the target compressor speed can be increased relative to the unfiltered compressor speed, e.g., set to the lower speed limit set as a result of the identification of the dehumidification deficiency. More specifically, for example, if the unfiltered compressor speed calls for the compressor 34 to run at 2000 RPM, but a dehumidification deficiency is identified that calls for the compressor speed to run at a minimum of 2400 RPM, the target compressor speed can be set to 2400 RPM instead of 2000 RPM. In this manner, the lower speed limit resulting from the dehumidification deficiency can act as a floor for the unfiltered compressor speed.

[0063] According to another exemplary embodiment, the identification of a speed modification condition can include identifying a speed limit or power limit condition for the compressor 34. In this regard, certain operating conditions can arise where it is not desirable to maintain a high speed for the compressor 34. For example, a speed limit can be implemented if a power consumption limit for the compressor 34 has been exceeded, a control board temperature has risen to an undesirably high level, or another unit operating characteristic indicates that the compressor speed should be reduced or limited to a particular speed. Thus, when a speed limit is identified, the unfiltered compressor speed (e.g., determined at step 220) is limited to an upper speed limit corresponding to the speed limit. Specifically, for example, if the unfiltered compressor speed is 5000 RPM, and the inverter board temperature begins to rise above a predetermined temperature threshold, the unfiltered compressor speed can be reduced to a predetermined value, e.g., such as 4000 to 4500 RPM, to prevent the inverter control board from overheating.

[0064] According to yet other embodiments, the identification of a speed modification condition can include identifying one or more resonance avoidance zones. If the unfiltered compressor speed falls within one or more resonance avoidance zones, the unfiltered compressor speed can be adjusted to fall outside of these zones. For example, resonance avoidance zones can generally correspond to operating speeds or frequencies that produce excessive vibrations within the compressor 34, the containment system, or more generally, the unit 10. If unchecked, these vibrations can lead to degradation of system components and premature failure of the unit 10. Reference will be made to FIGS. 3A and 3B to describe exemplary methods for adjusting the unfiltered compressor speed to avoid one or more resonance avoidance zones. Figure 9 Details regarding exemplary methods for adjusting the unfiltered compressor speed to avoid one or more resonance avoidance zones will be described in greater detail. It should be understood that the various steps in the methods 200 Figure 8 ) and 300 Figure 9 ) can be interchanged, combined, and varied to produce additional methods for operating an air conditioner unit.

[0065] Referring now to Figure 9 Method 300 includes, at step 310, initiating a run cycle of the air conditioner unit. Step 320 can include determining an unfiltered compressor speed of the variable speed compressor based at least in part on a sealing system demand. For example, as explained above with reference to steps 210 and 220, unit 10 can receive a command to initiate a run cycle, and can initiate a sealing system run in response to a sealing system demand that can be low for smaller temperature differentials, high for larger temperature differentials, or can include any other suitable sealing system demand and corresponding run speed and parameters of unit 10.

[0066] Step 330 can include determining that the unfiltered compressor speed falls within a resonance avoidance zone bounded by a minimum resonance frequency and a maximum resonance frequency. In this regard, the resonance avoidance zone can be a band of operating frequencies of compressor 34 that can produce undesirable vibrations within unit 10. For example, the resonance avoidance zone can be defined as compressor operating speeds between 2600 and 2800 RPM, or any other range of operating speeds. Thus, it can generally be desirable to avoid operation of compressor 34 in this operating zone. Notably, when no other limitations exist, it can be desirable for a default compressor operating speed to be on the high side of the resonance avoidance zone, such as at the maximum resonance frequency. However, according to exemplary embodiments, other system operating parameters or characteristics can make operation at the maximum resonance frequency undesirable.

[0067] For example, if a speed limit or power limit has been identified or triggered in operation of unit 10, and if the maximum resonance frequency exceeds the identified speed or power limit, it can be desirable to set the compressor speed based on the minimum resonance frequency instead. Thus, step 340 can include identifying a target compressor speed that avoids the resonance avoidance zone. In particular, step 340 can include setting the target compressor speed to the minimum resonance frequency if the unfiltered compressor speed exceeds the maximum speed limit. Further, step 340 can include setting the target compressor speed to the maximum resonance frequency if the unfiltered compressor speed is below the maximum speed limit.

[0068] Specifically, for example, if the unfiltered compressor speed is 3000 RPM, the resonance avoidance zone is identified as being between 2900 and 3100 RPM, and there is no power limit value (or a power limit at a maximum resonant frequency above 3100 RPM, such as 4000 RPM), the target compressor speed can be set to 3100 RPM. In contrast, if the unfiltered compressor speed is 4000 RPM, the resonance avoidance zone is identified as being between 3900 and 4200 RPM, and the power limit has been set to 4100 RPM, the target compressor speed can be set to 3900 RPM to avoid the resonance avoidance zone and the power limit range. Step 350 can generally include operating the variable speed compressor at the target compressor speed. Notably, implementing method 300 can generally help the compressor 34 and unit 10 operate in a manner that effectively cools or heats a room, does not generate excessive noise or harmful vibration, and does not exceed the power limit to protect system components.

[0069] Although method 300 is described herein as facilitating the operation of compressor 34 to avoid a single resonance avoidance zone, it should be understood that unit 10 may have more than one resident avoidance zone. Therefore, method 300 may include operating compressor 34 to avoid each resident avoidance zone. Furthermore, it should be understood that these resonance avoidance zones may be programmed by the user of the air conditioner unit or a maintenance technician. In this regard, these zones may be determined empirically and may be programmed into the controller to improve future performance of unit 10. For example, the resonance zone may be predetermined / specified in factory firmware based on unit make or model. Alternatively, testing may be performed at the factory before packaging / shipping to determine the resonant frequency of a particular unit.

[0070] For the purpose of illustration and discussion, Figure 8 and Figure 9 The steps are depicted as being performed in a particular order. Using the disclosure provided herein, one of ordinary skill in the art will appreciate that the steps of any method discussed herein may be adjusted, rearranged, expanded, omitted, or modified in various ways without departing from the scope of the present disclosure. Furthermore, while aspects of methods 200 and 300 are explained using unit 10 as an example, it should be understood that the method may be applied to operate any suitable air conditioning unit.

[0071] This written description uses examples to disclose the application, including the best mode, and also to enable any person skilled in the art to practice the application, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the application is defined by the claims, and can include other examples that occur to those skilled in the art. Such other examples are intended to fall within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Claims

1. An air conditioner unit comprising: a refrigeration circuit including an outdoor heat exchanger and an indoor heat exchanger; a variable speed compressor operably coupled to the refrigeration circuit and configured to cause a flow of refrigerant through the outdoor heat exchanger and the indoor heat exchanger; and a controller operably coupled to the variable speed compressor, the controller configured to: initiate a run cycle; determine an unfiltered compressor speed based at least in part on a sealing system demand; determine that the unfiltered compressor speed falls within a resonance avoidance zone bounded by a minimum resonance frequency and a maximum resonance frequency; identify a target compressor speed that avoids the resonance avoidance zone; and run the variable speed compressor at the target compressor speed; wherein determining the unfiltered compressor speed based at least in part on the sealing system demand comprises: initiating a compressor transition timer upon initiating the run cycle; running the variable speed compressor at a fixed compressor speed; determining that the compressor transition timer has exceeded a predetermined transition delay time; and in response to determining that the compressor transition timer has exceeded the predetermined transition delay time, determining the unfiltered compressor speed based at least in part on a closed loop feedback control algorithm.

2. The air conditioner unit of claim 1, wherein the closed loop feedback control algorithm comprises a proportional control algorithm, a proportional integral control algorithm, or a proportional integral derivative control algorithm.

3. The air conditioner unit of claim 1, further comprising an indoor temperature sensor, wherein determining the target compressor speed based at least in part on the closed loop feedback control algorithm comprises: obtaining an indoor temperature using the indoor temperature sensor; determining an error value between the indoor temperature and a setpoint temperature; and passing the error value into the closed loop feedback control algorithm to determine the unfiltered compressor speed.

4. The air conditioner unit of claim 1, wherein identifying the target compressor speed that avoids the resonance avoidance zone comprises: determining that the unfiltered compressor speed exceeds a maximum speed limit; and setting the target compressor speed to the minimum resonance frequency of the resonance avoidance zone.

5. The air conditioner unit of claim 1, wherein identifying the target compressor speed that avoids the resonance avoidance zone comprises: determining that the unfiltered compressor speed is below a maximum speed limit; and setting the target compressor speed to the maximum resonance frequency of the resonance avoidance zone.

6. The air conditioner unit of claim 1, wherein the controller is further configured to: determine that the unfiltered compressor speed does not fall within the resonance avoidance zone; determine that the unfiltered compressor speed is below a maximum speed limit; and run the variable speed compressor at the unfiltered compressor speed.

7. The air conditioner unit of claim 1, wherein the resonance avoidance zone is a first resonance avoidance zone, wherein the controller is further configured to: determine that the target compressor speed falls within a second resonance avoidance zone bounded by a second minimum resonance frequency and a second maximum resonance frequency; and run the variable speed compressor at the target compressor speed. ​ ​ ​ determining that the unfiltered compressor speed falls within a second resonance avoidance zone bounded by a minimum resonance frequency and a maximum resonance frequency; identifying a target compressor speed that avoids the second resonance avoidance zone; and operating the variable speed compressor at the target compressor speed.

8. The air conditioner unit of claim 1, wherein the controller is further configured to: identify a maximum speed limit corresponding to a power consumption limit that cannot be exceeded or a control board temperature that cannot be exceeded.

9. The air conditioner unit of claim 1, wherein the resonance avoidance zone is programmable by a user of the air conditioner unit, predetermined based on a model of the air conditioner unit, or determined through unit testing.

10. A method of operating an air conditioner unit, the air conditioner unit including a refrigeration circuit and a variable speed compressor operably coupled to the refrigeration circuit and configured to cause a flow of refrigerant through the refrigeration circuit, the method comprising: initiating an operating cycle; determining an unfiltered compressor speed based at least in part on a sealed system demand; determining that the unfiltered compressor speed falls within a resonance avoidance zone bounded by a minimum resonance frequency and a maximum resonance frequency; identifying a target compressor speed that avoids the resonance avoidance zone; and operating the variable speed compressor at the target compressor speed; wherein determining the unfiltered compressor speed based at least in part on the sealed system demand comprises: initiating a compressor transition timer upon initiating the operating cycle; operating the variable speed compressor at a fixed compressor speed; determining that the compressor transition timer has exceeded a predetermined transition delay time; and in response to determining that the compressor transition timer has exceeded the predetermined transition delay time, determining the unfiltered compressor speed based at least in part on a closed loop feedback control algorithm.

11. The method of claim 10, wherein the closed loop feedback control algorithm comprises a proportional control algorithm, a proportional integral control algorithm, or a proportional integral derivative control algorithm.

12. The method of claim 10, the air conditioner unit further comprising an indoor temperature sensor, wherein determining the target compressor speed based at least in part on the closed loop feedback control algorithm comprises: obtaining an indoor temperature using the indoor temperature sensor; determining an error value between the indoor temperature and a setpoint temperature; and passing the error value into the closed loop feedback control algorithm to determine the unfiltered compressor speed.

13. The method of claim 10, wherein identifying the target compressor speed that avoids the resonance avoidance zone comprises: determining that the unfiltered compressor speed exceeds a maximum speed limit; and setting the target compressor speed to the minimum resonance frequency of the resonance avoidance zone.

14. The method of claim 10, wherein identifying the target compressor speed that avoids the resonance avoidance zone comprises: determining that the unfiltered compressor speed is below a maximum speed limit; and setting the target compressor speed to the maximum resonance frequency of the resonance avoidance zone. ​ ​ ​ ​ 15. The method of claim 10, further comprising: determining that the unfiltered compressor speed does not fall within the resonance avoidance zone; determining that the unfiltered compressor speed is below a maximum speed limit; and operating the variable speed compressor at the unfiltered compressor speed.

16. The method of claim 10, wherein the resonance avoidance zone is a first resonance avoidance zone, further comprising: determining that the unfiltered compressor speed falls within a second resonance avoidance zone bounded by a minimum resonance frequency and a maximum resonance frequency; identifying the target compressor speed that avoids the second resonance avoidance zone; and operating the variable speed compressor at the target compressor speed.

17. The method of claim 10, further comprising: identifying a maximum speed limit corresponding to a power consumption limit that cannot be exceeded or a control board temperature that cannot be exceeded.

18. The method of claim 10, wherein the resonance avoidance zone is programmable by a user of the air conditioner unit, predetermined based on a model of the air conditioner unit, or determined through unit testing.

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