Optimized rollback control system and method thereof

Abstract

The invention relates to an optimized rollback control system and a method thereof. Embodiments of the present disclosure describe a method for controlling fallback of a heating, ventilation, and air conditioning (HVAC) system that includes a first HVAC unit and a second HVAC unit. The method is performed by a fallback control system. The method includes monitoring an internal temperature and an external temperature of a target region associated with the HVAC system. The method includes determining one or more operating parameters associated with a first HVAC unit of the HVAC system and determining a recovery time based on the operating parameters. The recovery time is a time required by the first HVAC unit to recover the internal temperature value from the fallback temperature setpoint value to the normal temperature setpoint value. The method includes triggering a fallback recovery based on the determined recovery time and a remaining time in a fallback period associated with a fallback of the HVAC system.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 590,880, filed on October 17, 2023, which is incorporated herein by reference in its entirety. Technical Field

[0002] The present disclosure relates generally to heating, ventilation, and air conditioning (HVAC) control systems and, more particularly, to an optimized fallback control system that optimizes the performance of the HVAC system and reduces the operating cost of the HVAC system. Background Art

[0003] Typically, an HVAC system operates to either heat or cool an indoor space by transferring heat from one location to another. An HVAC system may include one or more HVAC units for heating or cooling an indoor space. The thermal capacity of the one or more HVAC units is the ability of the one or more HVAC units to deliver heat at a specific time. Typically, the thermal capacity of the one or more HVAC units depends on various factors, such as the outdoor temperature relative to the indoor space, the temperature difference between the current indoor temperature and the current outdoor temperature, the area of ​​a barrier separating the indoor space from the outdoor space, and the thermal conductivity of the barrier separating the indoor space from the outdoor space.

[0004] Generally, for heating purposes, when the outdoor temperature is lower than the indoor temperature and the outdoor temperature decreases, the heat capacity required to maintain the temperature of the indoor space increases. However, the maximum heat capacity of the heat pump decreases as the outdoor temperature decreases. At a threshold temperature, the heat capacity required to maintain the internal temperature will be the same as the maximum heat capacity of the heat pump. If the outside temperature further drops below the threshold temperature, additional heating sources will be required to maintain the internal temperature.

[0005] In addition, the HVAC system can be operated in a fallback mode. During the fallback mode, the temperature setting of the heating or cooling system for the indoor space is adjusted, i.e., changed from a normal set point to a fallback set point, to save energy during a period when the indoor space is not actively used. As the time of the fallback mode approaches the end, when the fallback mode ends, a fallback recovery mode can be employed to restore the temperature from the fallback set point to the normal set point. During the fallback recovery mode, an additional heating or cooling source is required to return to the preset temperature value.

[0006] Operation in the fallback mode reduces heating costs and / or cooling costs. Such a fallback mode is generally beneficial to HVAC systems with a single heating and / or cooling technology. Today, HVAC systems can include multiple heating and / or cooling technologies, however, for HVAC systems that use multiple heating and / or cooling technologies, fallback performance may not be efficient. This is because it is very challenging to optimize fallback performance considering the varying operating costs of multiple heating and / or cooling technologies. For example, a system that reduces the use of a lower-cost heating technology during fallback but then needs to use a higher-cost heating technology to complete fallback recovery may ultimately experience a higher total heating cost due to fallback compared to if fallback had not been used during the same period. In this case, the benefits of fallback are lost and may become disadvantageous overall. Therefore, there is a need for an improved control system and method that can overcome the above-mentioned problems. Summary of the invention

[0007] This summary is provided to introduce a selection of concepts in a simplified form that are further described in the detailed description of the disclosure. This summary is neither intended to identify key or essential inventive concepts of the disclosure nor to determine the scope of the disclosure.

[0008] Disclosed herein is a fallback control system for controlling fallback of a heating, ventilation and air conditioning (HVAC) system, the fallback control system comprising a first HVAC unit and a second HVAC unit. The fallback control system comprises a memory and one or more processors communicatively coupled to the memory. The one or more processors are configured to monitor an internal temperature of a target area associated with the HVAC system. The one or more processors are further configured to monitor an external temperature of a target area associated with the HVAC system. The one or more processors are further configured to determine one or more operating parameters associated with the first HVAC unit of the HVAC system, wherein the one or more operating parameters include at least one of excess capacity of the first HVAC unit or relative operating cost of the first HVAC unit relative to the second HVAC unit. The one or more processors are further configured to determine a recovery time based on the determined one or more operating parameters. The recovery time indicates the time required by the first HVAC unit to restore the internal temperature value of the target area from a fallback temperature set point value to a normal temperature set point value. The one or more processors are further configured to trigger a fallback recovery based on the determined recovery time and the remaining time in the fallback period associated with the fallback of the HVAC system.

[0009] In one or more embodiments, the one or more processors are configured to continuously monitor the remaining time in the backoff period before triggering the backoff recovery. The backoff period indicates the period of time that the HVAC system operates in the backoff mode. The remaining time indicates the remaining time when the backoff period is completed.

[0010] In one or more embodiments, to trigger rollback recovery, the one or more processors are configured to compare the determined recovery time with the determined remaining time. The one or more processors are further configured to trigger rollback recovery when it is determined that the determined recovery time is equal to the determined remaining time.

[0011] In one or more embodiments, the normal temperature set point value indicates a temperature value maintained when the HVAC system is operating in the normal mode. The fallback temperature set point value indicates a temperature value maintained during the fallback period when the HVAC system is operating in the fallback mode.

[0012] In one or more embodiments, the one or more processors are configured to trigger the fallback recovery before the internal temperature value of the target zone reaches the fallback temperature set point value.

[0013] In one or more embodiments, to determine the recovery time, the one or more processors are further configured to determine the recovery time based on one or more of a current internal temperature value, a maximum capacity of the first HVAC unit, an operating cost of the first HVAC unit, a temperature difference between the internal temperature and the external temperature, and a thermal conductivity of a barrier separating the target area and an area outside the target area.

[0014] Also disclosed herein is a method for controlling a fallback of a heating, ventilation, and air conditioning (HVAC) system, the system comprising a first HVAC unit and a second HVAC unit. The method is performed by a fallback control system. The method includes monitoring an internal temperature of a target area associated with the HVAC system. In addition, the method includes monitoring an external temperature of a target area associated with the HVAC system. In addition, the method includes determining one or more operating parameters associated with a first HVAC unit of the HVAC system, wherein the one or more operating parameters include at least one of an excess capacity of the first HVAC unit or a relative operating cost of the first HVAC unit relative to the second HVAC unit. In addition, the method includes determining a recovery time based on the determined one or more operating parameters. The recovery time indicates the time required by the first HVAC unit to restore an internal temperature value of the target area from a fallback temperature set point value to a normal temperature set point value. In addition, the method includes triggering a fallback recovery based on the determined recovery time and a remaining time in a fallback period associated with the fallback of the HVAC system.

[0015] In one or more embodiments, the method includes, before triggering the fallback restoration, continuously monitoring the remaining time in the fallback period. The fallback period indicates the period of time that the HVAC system operates in the fallback mode. The remaining time indicates the remaining time when the fallback period is completed.

[0016] In one or more embodiments, triggering the rollback recovery includes comparing the determined recovery time with the determined remaining time. In addition, the method includes triggering the rollback recovery when it is determined that the determined recovery time is equal to the determined remaining time.

[0017] In one or more embodiments, the normal temperature set point value indicates a temperature value maintained when the HVAC system is operating in the normal mode. The fallback temperature set point value indicates a temperature value maintained during the fallback period when the HVAC system is operating in the fallback mode.

[0018] In one or more embodiments, the method includes triggering a fallback recovery before an internal temperature value of the target zone reaches a fallback temperature set point value.

[0019] In one or more embodiments, determining the recovery time includes determining the recovery time based on one or more of a current internal temperature value, a maximum capacity of the first HVAC unit, an operating cost of the first HVAC unit, a temperature difference between the internal temperature and the external temperature, and a thermal conductivity of a barrier separating the target area and an area outside the target area.

[0020] In order to further clarify the advantages and features of the method, system and apparatus, a more specific description of the method, system and apparatus will be presented by reference to the specific embodiments thereof illustrated in the accompanying drawings. It is understood that these drawings depict only typical embodiments of the present disclosure and therefore should not be considered as limiting the scope thereof. The present disclosure will be described and explained using the accompanying drawings, using additional features and details. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] These and other features, aspects and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings, wherein like reference numerals refer to like parts throughout the drawings, and wherein:

[0022] Figure 1 illustrates an environment including a heating, ventilation, and air conditioning (HVAC) system and a fallback control system according to one or more embodiments of the present disclosure;

[0023] Figure 2a-2b illustrates a characteristic graph depicting an interior temperature value of a target zone versus a capacity of a first HVAC unit of an HVAC system and an outside temperature according to one or more embodiments of the present disclosure;

[0024] Figure 2cillustrates a characteristic graph depicting a relationship between a thermal capacity of a first HVAC unit of an HVAC system and a capacity required to maintain an interior temperature relative to an exterior temperature in accordance with one or more embodiments of the present disclosure;

[0025] Figure 3a-3e A graphical representation illustrating the operation of a rollback control system according to one or more embodiments of the present disclosure; and

[0026] Figure 4 A process flow depicting a method for controlling fallback of an HVAC system according to one or more embodiments of the present disclosure is illustrated.

[0027] Furthermore, those skilled in the art will appreciate that the elements in the drawings are illustrated for simplicity and may not necessarily have been drawn to scale. For example, a flow chart illustrates the method in terms of the most significant steps involved to help improve understanding of aspects of the present disclosure. Furthermore, with respect to the construction of the device, one or more components of the device may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details relevant to understanding the embodiments of the present disclosure so as not to obscure the drawings with details that would be readily apparent to one of ordinary skill in the art having the benefit of the description herein. DETAILED DESCRIPTION

[0028] For the purpose of promoting an understanding of the principles of the present disclosure, reference will now be made to various embodiments, and specific language will be used to describe the embodiments. It will be understood, however, that no limitation of the scope of the present disclosure is thereby intended, and such changes and further modifications in the illustrated systems and devices, and such further applications of the principles of the present disclosure as illustrated therein are contemplated as would normally occur to one skilled in the art to which the present disclosure relates.

[0029] It will be understood by those skilled in the art that both the foregoing general description and the following detailed description are illustrative of the present disclosure and are not intended to limit the present disclosure.

[0030] Throughout this specification, references to "aspect," "another aspect," or similar language mean that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the present disclosure. Thus, throughout this specification, appearances of the phrases "in an embodiment," "in another embodiment," "some embodiments," "one or more embodiments," and similar language may, but do not necessarily, all refer to the same embodiment.

[0031] The terms "comprises, comprising" or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process or method that includes a series of steps includes not only those steps but may also include other steps not expressly listed or inherent to such a process or method. Similarly, one or more devices or subsystems or elements or structures or components beginning with "comprises ..." do not exclude the presence of other devices or other subsystems or other elements or other structures or other components or additional devices or additional subsystems or additional elements or additional structures or additional components without more constraints.

[0032] In addition to overcoming challenges associated with operating costs of HVAC systems, the present disclosure provides systems and methods for operating a smart fallback HVAC control system that results in energy and cost savings.

[0033] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0034] Figure 1 An environment 100 including a heating, ventilation, and air conditioning (HVAC) system and a fallback control system according to one or more embodiments of the present disclosure is illustrated. The environment 100 may include a target area 102. The target area 102 may be, but is not limited to, a room in a residential building, a commercial building, an industrial facility, a hospital facility, an educational institution, a hotel, an entertainment venue, etc. The target area 102 may have at least one temperature sensor 106 installed inside the target area 102. In addition, an HVAC system 104 may be installed in or near the target area 102 to maintain an internal temperature value of the target area 102. The HVAC system 104 may be configured to provide at least one of heated air and cooled air to the target area 102.

[0035] The fallback control system 108 is communicatively connected to at least one temperature sensor 106 and the HVAC system 104. The fallback control system 108 may include one or more processors 112, a memory 110, an input / output (I / O) interface unit 114, one or more modules 116, and a database 118. In an embodiment, the memory 110, the input / output (I / O) interface unit 114, the database 118, and the one or more modules 116 may be external to the one or more processors 112. The one or more processors 112 may be a single control unit or multiple units, all of which may include multiple computing units. The one or more processors 112 may be implemented as one or more microprocessors, microcomputers, microcontrollers, digital signal processors, central processing units, state machines, logic circuits, and / or any device that manipulates signals based on operating instructions. Among other capabilities, the one or more processors 112 may be configured to retrieve and execute computer-readable instructions and data stored in the memory 110.

[0036] Memory 110 may include any non-transitory computer-readable medium known in the art, including, for example, volatile memory (such as static random access memory (SRAM) and dynamic random access memory (DRAM)) and / or non-volatile memory, such as (read-only memory (ROM), erasable programmable ROM, flash memory, hard disk, optical disk, and tape).

[0037] The module(s) 116 include routines, programs, objects, components, data structures, etc. that perform specific tasks or implement data types. The module(s) 116 may also be implemented as signal processor(s), state machine(s), logic circuits, and / or any other device or component that manipulates signals based on operational instructions.

[0038] In addition, the module(s) 116 may be implemented in hardware, instructions executed by the one or more processors 112, or a combination thereof. The one or more processors 112 may include a computer, a processor, a state machine, a logic array, and / or any other suitable device capable of processing instructions. The one or more processors 112 may be a general purpose controller that executes instructions to cause a general purpose processor to perform operations, or a processing unit may be dedicated to performing a desired function. In some example embodiments, the module(s) 116 may be machine readable instructions (software, such as a web application, mobile application, program, etc.) that, when executed by the one or more processors 112, perform any of the described functionalities.

[0039] Database 118 serves as a repository, etc., for storing data processed, received, and generated by one or more of module(s) 116. Programs or routines stored in database 118 may include HVAC control programs and / or scheduling software that may be capable of automatically controlling an HVAC system.

[0040] In an embodiment of the present disclosure, the module(s) 116 may be implemented as part of the one or more processors 112. In another embodiment of the present disclosure, the module(s) 116 may be external to the one or more processors 112. In yet another embodiment of the present disclosure, the module(s) 116 may be part of the memory 110. In another embodiment of the present disclosure, the module(s) 116 may be part of the hardware, separate from the one or more processors 112.

[0041] The one or more processors 112 may be included in a computing system installed in a cloud-based network, a mobile computing device, or a local control system such as, for example, an HVAC control system. The one or more processors 112 may be in electrical communication with the memory 110 in response to receiving commands from one or more input / output (I / O) devices. In some embodiments, the (one or more) I / O devices may include one or more of a keyboard or keypad, a touch screen or touch panel, a display screen, a microphone, a speaker, a mouse, a button, a remote control, a joystick, a printer, a phone, or a mobile device (e.g., a smartphone), etc. The (one or more) I / O devices may be configured to provide an interface such as a thermostat interface, for example, to allow a user to interact with the system.

[0042] The one or more processors 112 may be configured to communicate with the memory 110 to execute programmable instructions stored in the memory 110. When executed by the one or more processors 112, the programmable instructions cause the one or more processors 112 to provide the functionality of the rollback control system 108 as discussed in the present disclosure. In one or more embodiments, the one or more processors 112 may be one or more microprocessors or microcontrollers. The one or more processors 112 may include one or more processors, which may also include one or more general-purpose processors (such as a central processing unit (CPU), an application processor (AP), etc.), a pure graphics processing unit (such as a graphics processing unit (GPU), a visual processing unit (VPU)) and / or an artificial intelligence (AI) dedicated processor (such as a neural processing unit (NPU)).

[0043] In some embodiments, the memory 110 may store data and instructions executable by the one or more processors 112 to perform method steps for optimizing the rollback of the HVAC system 104, as discussed herein throughout the present disclosure. The memory 110 may also include, but is not limited to, non-transitory computer-readable storage media, such as various types of volatile and non-volatile storage media, including but not limited to random access memory, read-only memory, programmable read-only memory, electrically programmable read-only memory, electrically erasable read-only memory, flash memory, tape or disk, optical media, etc. In addition, the non-transitory computer-readable storage media of the memory 110 may include executable instructions in the form of modules and a database 118 for storing data. The module may include a set of instructions that may be executed to cause the one or more processors 112 to perform any one or more of the methods disclosed herein throughout the present disclosure. In one or more embodiments, the module may be configured to use the data stored in the database 118 of the memory 110 to perform the steps of the present disclosure for optimizing the rollback of the HVAC system.

[0044] In some embodiments, the HVAC system 104 may include a first HVAC unit and a second HVAC unit. The first HVAC unit may be associated with a lower operating cost than the second HVAC unit. In an embodiment, the first HVAC unit may be a heat pump. In some embodiments, the second HVAC unit may be an electrical resistance heater or furnace that generates heat through the combustion of a fossil fuel or similar fuel source. In other embodiments, the first and second HVAC units may be integrated into a single piece of equipment, where the first and second HVAC units operate independently or together to provide heating.

[0045] In some embodiments, the HVAC system 104 may be adapted to operate in a normal mode and a fallback mode. In the normal mode, the HVAC system 104 may be operable to maintain the temperature within the target zone 102 at a normal temperature set point value. In the fallback mode, the HVAC system 104 may be operable to maintain the temperature within the target zone 102 at a fallback temperature set point value. In embodiments, the fallback temperature set point value may be less than the normal temperature set point value, such as when the HVAC system is operated to heat the target zone 102.

[0046] The HVAC system 104 may be adapted to switch between a normal mode and a fallback mode. The HVAC system 104 may operate in the normal mode and switch to the fallback mode for a predetermined period of time, referred to as the fallback period. At the end of the fallback period, the HVAC system 104 may switch to the normal mode. In some embodiments, the HVAC system 104 may have a fallback recovery mode such that the HVAC system 104 initially switches from the fallback mode to the fallback recovery mode before the predetermined period of time has expired, and subsequently switches to the normal mode. The fallback recovery mode may be associated with a temperature recovery from a fallback temperature set point value to a normal temperature set point value.

[0047] In some embodiments, the fallback temperature set point value and the normal temperature set point value may be preset values ​​stored in the database 118. In some embodiments, the fallback temperature set point value and the normal temperature set point value may be set based on user input.

[0048] According to one or more embodiments of the present disclosure, Figure 2a-2b Characteristic graphs 200 and 202 are illustrated, respectively, depicting interior temperature values ​​of the target zone 102 versus the thermal capacity required to maintain the interior temperature as a function of the exterior temperature, and interior temperature values ​​versus the available thermal capacity of the first HVAC unit of the HVAC system 104 as a function of the exterior temperature.

[0049] With respect to the target area 102 , the heat capacity required to maintain the internal temperature value depends on one or more factors, including the temperature difference between the interior of the target area 102 and the exterior of the target area 102 , the thermal conductivity of the barrier separating the interior of the target area 102 and the exterior of the target area 102 , and the area of ​​the barrier.

[0050] For a fixed set of factors, the heat capacity required to maintain the internal temperature value varies as a function of the external temperature (the temperature value outside the target area 102). Figure 2a As seen in , considering a first HVAC unit used to heat the target zone 102, for a given outside temperature, increasing the inside temperature value requires increasing the thermal capacity of the first HVAC unit. For a given inside temperature, decreasing the outside temperature requires increasing the thermal capacity of the first HVAC unit.

[0051] In addition, if Figure 2b As can be seen in FIG. 1 , the maximum heat capacity of the first HVAC unit varies with both the inside temperature and the outside temperature. As the inside temperature increases, the maximum heat capacity of the first HVAC unit decreases. As the outside temperature decreases, the maximum heat capacity of the first HVAC unit decreases.

[0052] Figure 2cA characteristic graph 204 depicting a relationship between a thermal capacity of a first HVAC unit of the HVAC system 104 and a capacity required to maintain an interior temperature relative to an exterior temperature is illustrated in accordance with one or more embodiments of the present disclosure.

[0053] As the outside temperature decreases, the thermal capacity required to maintain the inside temperature value increases. In addition, as the outside temperature decreases, the thermal capacity of the first HVAC unit decreases. At a threshold temperature T 阈值1 Under the threshold temperature, the thermal capacity required to maintain the internal temperature value may be the same as the maximum thermal capacity of the first HVAC unit. Below the threshold temperature, an additional heating source may be required to maintain the internal temperature.

[0054] In addition to maintaining the interior temperature value, the first HVAC unit may need to increase the interior temperature value of the target zone 102. For example, when the HVAC system 104 switches from the fallback mode to the normal mode, the first HVAC unit may be operable to increase the interior temperature value at the end of the fallback period. In order to increase the interior temperature value, thermal capacity in excess of that required to maintain the interior temperature value may be used to increase the interior temperature value in the target zone 102. The excess thermal capacity of the first HVAC unit may be represented by the difference between the capacity required to maintain the interior temperature value of the target zone 102 and the maximum capacity provided by the first HVAC unit.

[0055] Reference again Figure 1 , the one or more processors 112 can be configured to monitor the internal temperature value of the target area 102. In some embodiments, the one or more processors 112 can be configured to receive temperature readings from a temperature sensor 106 located within the target area 102. In some embodiments, the temperature sensor 106 can be integrated with a thermostat within the target area 102.

[0056] The one or more processors 112 may be configured to monitor an external temperature associated with the target area 102. The external temperature may be monitored using one or more sensors (not shown) located proximate to the exterior of the target area 102 and communicatively coupled to the control system 108. As described above, the external temperature refers to a temperature value outside the target area 102.

[0057] The one or more processors 112 may be configured to determine excess capacity of a first HVAC unit of the HVAC system 104. The excess capacity may be determined based on a difference between a capacity required to maintain an interior temperature value of the target zone 102 and a maximum capacity that can be provided by the first HVAC unit.

[0058] As described above, in the normal mode, the HVAC system 104 may maintain the interior temperature value at the normal temperature set point value. For example, the normal temperature set point value may be set at 70°F, and the HVAC system 104 may maintain the interior temperature value at 70°F.

[0059] In addition, when the HVAC system 104 is operating in the fallback mode, the HVAC system 104 may maintain the interior temperature value at the fallback temperature set point value. For example, the fallback temperature set point value may be set at 65° F., and the HVAC system 104 may stop or reduce heating to allow the interior temperature value to naturally decrease from 70° F. to 65° F. When the interior temperature value reaches 65° F., the HVAC system 104 may maintain the interior temperature value at 65° F., for example, by resuming its operation.

[0060] In order to restore the interior temperature value from the fallback temperature set point value to the normal temperature set point value, the HVAC system 104 may be operable to actively increase the interior temperature value. During the fallback period, the HVAC system 104 may allow the interior temperature value to decrease from the normal temperature set point value to the fallback temperature set point value. At a specific trigger time during the fallback period, the HVAC system 104 may begin operating to restore the interior temperature value from the fallback temperature set point value to the normal temperature set point value.

[0061] In some embodiments, the first HVAC unit of the HVAC system 104 may be operated to restore the interior temperature value from the fallback temperature set point value to the normal temperature set point value. The one or more processors 112 may be configured to determine a fallback recovery time to restore the interior temperature value to the normal temperature set point value using only the first HVAC unit of the HVAC system 104. That is, the current temperature value of the target zone 102, which may be at or near the fallback temperature set point value, may be restored to the normal temperature set point value. The fallback recovery time may be determined by dividing the thermal capacity of the target zone 102 by the excess thermal capacity of the first HVAC unit to determine the time to recover from the fallback. The thermal capacity of the target zone 102 may be determined by observing the heat loss as indicated by the capacity required to maintain the interior temperature before the fallback period, and then observing the decay rate of the interior temperature when the HVAC system 104 reduces or stops heating the target zone at the beginning of the fallback period.

[0062] The one or more processors 112 may be configured to determine the remaining time in the backoff period. The one or more processors 112 may determine the remaining time based on a timer function and a predetermined value of the backoff period. In an embodiment, the one or more processors 112 may be configured to continuously monitor the remaining time during the backoff period.

[0063] The one or more processors 112 may be configured to compare the determined recovery time with the determined remaining time. Upon determining that the recovery time is greater than or equal to the remaining time, the one or more processors 112 may be configured to trigger a fallback recovery. That is, the one or more processors 112 may cause the HVAC system 104 to operate to restore the interior temperature value to a normal temperature set point value. As a result, the interior temperature value may be restored to a normal temperature value at the end of the fallback period by avoiding a second HVAC unit having a higher operating cost. Thus, a more efficient system operation is achieved.

[0064] In other words, the triggering of the fallback recovery is determined based on the excess capacity of the first HVAC unit (i.e., the lower cost HVAC unit). The use of fallback is optimized to save operating costs, and the fallback is managed in such a way that the fallback recovery is possible without using the higher cost HVAC unit.

[0065] In an embodiment, when the HVAC system 104 is operating in the fallback mode, the fallback recovery may be triggered before the interior temperature value reaches the fallback temperature setpoint value.

[0066] In an embodiment, during fallback restoration, only the first HVAC unit is operable to restore the interior temperature value to a normal temperature set point value. That is, operation of the second HVAC unit is avoided during fallback restoration while restoring the interior temperature value to a normal temperature set point value. In an embodiment, during fallback restoration, the first HVAC unit as well as the second HVAC unit are operable to restore the interior temperature value to a normal temperature set point value.

[0067] In some embodiments, when the HVAC system 104 switches from the normal mode to the fallback mode, the interior temperature value is allowed to decrease from the normal temperature set point value to the fallback temperature set point value. The decrease in the interior temperature value may be due to heat loss outside the target zone 102. Once the interior temperature value decreases to the fallback temperature set point value, the HVAC system 104 maintains the interior temperature value at the fallback temperature set point value.

[0068] In some embodiments, the one or more processors 112 may be configured to determine, at a first periodic time interval, the excess capacity required to fall back to the normal temperature set point value at the end of the fallback period. In a non-limiting example, the first periodic time interval may be 5 minutes. The one or more processors 112 may be further configured to determine a predicted excess capacity available with the first HVAC unit for implementing the fallback restoration.

[0069] The one or more processors 112 may be configured to compare the predicted excess capacity available with the first HVAC unit to the excess capacity required for fallback restoration. Upon determining that the predicted excess capacity available with the first HVAC unit is within a threshold margin of the excess capacity required for fallback restoration, the one or more processors 112 may be configured to trigger fallback restoration. Fallback operation is optimized particularly under conditions of light to moderate loads that may be less than the maximum thermal capacity of the first HVAC unit, and additionally when the relative operating cost between the first HVAC unit and the second HVAC unit is relatively large (e.g., a factor of 2).

[0070] In another embodiment, the relative operating cost between the first HVAC unit and the second HVAC unit may be stored in the database 118. When the HVAC system 104 switches from the normal mode to the fallback mode, the internal temperature value is allowed to decrease from the normal temperature set point value to the fallback temperature set point value. The one or more processors 112 may be configured to monitor the relative operating cost if the fallback restoration is triggered at the current time and the relative operating cost if the fallback restoration is initiated at a future time at a second periodic time interval. The one or more processors 112 may be configured to determine that the relative operating cost if the fallback restoration is initiated at the future time exceeds the relative operating cost if the fallback restoration is initiated at the current time. Upon determination, the one or more processors 112 may be configured to trigger the fallback restoration.

[0071] Figure 3a Illustrated is a graphical representation 300 of the operation of the rollback control system 108 according to an embodiment of the present disclosure.

[0072] The one or more processors 112 may be further configured to control the operation of the HVAC system 104, including the first HVAC unit and the second HVAC unit, based on an operating schedule. In some embodiments, the operating schedule may be stored in a database 118. Figure 3a , the backoff period starts at a specific start time t1. Before t1, the HVAC system operates in normal mode, where the internal temperature value T Int Maintain at normal temperature set point value T SP1 At the beginning of the retreat period, the internal temperature value T int From the normal temperature set point value T SP1 Gradually reduce to the set point value T SP2 That is, during the backoff period, a lower temperature is maintained within the target area 102. The backoff period lasts until a specified end time t2.

[0073] During the back-off period, the HVAC system 104 may not actively operate to maintain the interior temperature value T IntAlternatively, due to heat loss from the target area 102, the internal temperature T Int Can naturally decrease. At time t3, the internal temperature value T Int The fallback temperature set point value T can be reached SP2 This indicates that the interior temperature value has dropped to the target level during the backoff period, and the HVAC system 104 operates to increase the interior temperature value T Int Maintain the set point temperature T SP2 .

[0074] During the backoff period from time t1 to time t2, the one or more processors 112 may be configured to monitor the estimated backoff recovery time t R and the remaining time t for the fallback ESB In the illustrated embodiment, the backoff recovery time t R The first HVAC unit of the HVAC system 104 may be used to set the interior temperature T Int From the fallback temperature set point value T SP2 Return to normal temperature set point value T SP1 The time required. Back-off recovery time t R The remaining time t may be continuously tracked by the one or more processors 112. ESB Can refer to the time remaining in the fallback period.

[0075] When the remaining time t ESB At time t4 it becomes equal to the rollback recovery time t R When the one or more processors 112 can trigger the fallback recovery. In the fallback recovery, the first HVAC unit is operable to set the internal temperature value T Int From the fallback temperature set point value T SP2 Towards the normal temperature set point value T SP1 Increase, such as Figure 3a The optimization of the fallback makes the internal temperature value T Int When the fallback period is completed (i.e., at time t2), the fallback temperature set point value TSP2 reaches the normal temperature set point value T SP1 ,like Figure 3a As seen in.

[0076] In some embodiments, the back-off recovery can be performed at the internal temperature value T Int Reach the fallback temperature set point value T SP2 was triggered before. Figure 3b A graphical representation 302 of the operation of the rollback control system 108 is illustrated according to another embodiment of the present disclosure. Figure 3b As can be seen, at time t4, at the internal temperature value T Int Reach the fallback temperature set point value T SP2Before, the remaining time t ESB becomes equal to the rollback recovery time t R Therefore, the one or more processors 112 trigger the rollback recovery at time t4, such as Figure 3b As seen in.

[0077] In some embodiments, the second HVAC unit of the HVAC system 104 may be needed during the fallback recovery in order to complete the fallback recovery at the end of the fallback period. The first HVAC unit may be a low-cost heating power source, while the second HVAC unit may be a high-cost heating power source. Figure 3c A graphical representation 304 of the operation of the rollback control system 108 is illustrated in accordance with another embodiment of the present disclosure. Figure 3c As can be seen in FIG. 1 , the operation during times t1, t3, and t4 is similar to that of FIG. Figure 3a At time t5, in addition to the first HVAC unit, the second HVAC unit is also operated to complete the fallback recovery at the end of the fallback period, ie, at time t2. Figure 3c Further depicted is a graph 306 of power usage of the HVAC system in operation.

[0078] Before the backoff period, i.e., before time t1, the HVAC system is operated at power level P1, where both the first HVAC unit and the second HVAC unit are operating. When the backoff period begins, the HVAC system can be turned off and the power consumption drops to zero. The internal temperature value T Int Drop to the fallback temperature set point value T SP2 When the internal temperature T Int Reach the fallback temperature set point value T SP2 When the first HVAC unit is operated at power level P2, the internal temperature value T Int Maintain the set point temperature T SP2 When the backoff recovery is triggered at time t4, the power of the first HVAC unit is increased to the maximum power level P3 until time t5, at which time the second HVAC unit must be engaged to complete the backoff recovery at the end of the backoff period. Between time t5 and t2, the power level of the HVAC system 104 may be P4, which may be a power level greater than power level P1. At the end of the backoff period, i.e., after time t2, the HVAC system returns to power level P1. The energy saved during the backoff period between t1 and t5 is indicated by the area below the P1 power label and is shown as P 减少 The additional power used during the back-off recovery period between t5 and t2 is indicated by the area above P1 and is shown as P 额外 .P 减少 Greater than P 额外, indicating that there is a net energy saving during the back-off period compared to operating without back-off at power level P1 during the entire period.

[0079] In some operating scenarios, the power P1 before the fallback period begins may not include operation of the second HVAC unit, but operation of the second HVAC unit may be required only during the fallback recovery period, as shown in FIG. Figure 3d In still other operating scenarios, operation of a second HVAC unit may be required to maintain temperature during the fallback period, and during the fallback recovery period, the second HVAC unit may need to be operated at a higher power, as described in reference to Figure 3e As described.

[0080] Figure 3d A graphical representation 308 of the operation of the fallback control system 108 according to another embodiment of the present disclosure is illustrated. The first HVAC unit may be a low-cost heating power source, while the second HVAC unit may be a high-cost heating power source. Figure 3d As can be seen in Figure 2, the operation during times t1, t3, and t4 is similar to the reference Figure 3a During the fallback recovery period, ie, between time t4 and time t2, the second HVAC unit is operated in addition to the first HVAC unit. Figure 3d Further depicted is a graph 310 of power usage of the HVAC system in operation.

[0081] Before the backoff period, i.e., before time t1, the HVAC system is operated at power level P1, with only the first HVAC unit in operation. When the backoff period begins, the HVAC system can be turned off and the power consumption drops to zero. The interior temperature value T Int Drop to the fallback temperature set point value T SP2 When the internal temperature T Int Reach the fallback temperature set point value T SP2 When the first HVAC unit is operated at power level P2, the internal temperature value T Int Maintain the set point temperature T SP2 When the fallback recovery is triggered at time t4, the power of the first HVAC unit is increased to the maximum capacity of the first HVAC unit, i.e., power level P3. In addition, at time t5, the second HVAC unit must be engaged to complete the fallback recovery at the end of the fallback period. Therefore, the second HVAC unit is also operated, and due to the operation of both the first HVAC unit and the second HVAC unit, the power level is P4.

[0082] To complete the backoff recovery at time t2, the power levels P3 and P4 during the backoff recovery are greater than P1, as shown by P 额外At the end of the back-off period, i.e., after time t2, the HVAC system returns to power level P1 and only the first HVAC unit is operated. The energy saved during the back-off period between t1 and t5 is indicated by the area below the P1 power label and is shown as P 减少 The additional power used during the back-off recovery period between t4 and t2 is indicated by the area above P1 and is shown as P 额外 .P 减少 Greater than P 额外 , indicating that there is a net energy saving during the back-off period.

[0083] Figure 3e A graphical representation 312 of the operation of the fallback control system 108 according to another embodiment of the present disclosure is illustrated. The first HVAC unit may be a low-cost heating power source, while the second HVAC unit may be a high-cost heating power source. Figure 3e As can be seen in FIG. 1 , in normal operation before time t1, both the first HVAC unit and the second HVAC unit are in operation. In the fallback mode between time t1 and t3, the indoor temperature may drop to the fallback temperature set point value T SP2 During the fallback period between time t3 and time t4, both the first HVAC unit and the second HVAC unit are in operation to maintain the indoor temperature at the fallback temperature set point value T SP2 Furthermore, during the fallback recovery period between time t4 and time t2, both the first HVAC unit and the second HVAC unit are in operation. Figure 3e Further depicted is a graph 314 of power usage of the HVAC system in operation.

[0084] Before the backoff period, i.e., before time t1, the HVAC system is operated at a combined power level P1, wherein both the first HVAC unit and the second HVAC unit are in operation. When the backoff period begins, the HVAC system may be turned off, and the power consumption drops to zero. The interior temperature value T Int Drop to the fallback temperature set point value T SP2 When the internal temperature T Int Reach the fallback temperature set point value T SP2 When the first HVAC unit and the second HVAC unit are operated at a combined power level P2 to reduce the interior temperature value T Int Maintain the set point temperature T SP2 .

[0085] When the fallback recovery is triggered at time t4, the first HVAC unit and the second HVAC unit are operated at the combined power level P3. In addition, at time t5, the power level of the second HVAC unit is increased to complete the fallback recovery at the end of the fallback period. Figure 3eAs seen in FIG. 5 , between time t5 and time t2, the power level is P4, which is greater than power level P1. The additional power used during the back-off recovery between t5 and t2 is indicated by the area above P1 and is shown as P 额外 The energy saved during the back-off period between t1 and t5 is indicated by the area below the P1 power label and is shown as P 减少 .P 减少 Greater than P 额外 , indicating that there is a net energy saving during the back-off period.

[0086] In some embodiments, the system 108 may be associated with multiple recovery profiles. The recovery profiles may be stored in the database 118. In some embodiments, the recovery profiles may be associated with corresponding costs. The system 108 may be configured to select an optimal profile from the multiple recovery profiles for fallback recovery. The optimal profile may be, for example, a profile with the lowest total cost. For example, a first recovery profile may be determined using only the first HVAC unit, and a second recovery profile may be determined using both the first and second HVAC units together. In order to operate at a higher capacity, the second recovery profile may operate at a higher instantaneous cost, but a lower total cost may be achieved by operating in recovery mode for a shorter period of time, thereby enabling a longer period of low-power operation in fallback before recovery begins.

[0087] In some embodiments, operation of the second HVAC unit may be required in the event of an outside temperature change that affects the thermal capacity of the first HVAC unit. In some embodiments, the operating cost of the fallback recovery may be based on an expected outside temperature. The expected temperature may be derived from a current trend in temperature change, a recent historical temperature trend observed over a time period (such as the last 1-5 days), a weather forecast for temperature, or some combination thereof. In some embodiments, an intermediate threshold temperature value may be set between the fallback temperature set point value and the normal temperature set point value, and operation of the second HVAC unit may be required only if the inside temperature value has not reached the intermediate threshold temperature value at the end of the fallback period.

[0088] In some embodiments, the database 118 may store normal temperature set point values, fallback temperature set point values, and operating schedules for different modes of the HVAC system 104. The database 118 may also store a history of temperature recovery rates (i.e., one or more previously recorded temperature recovery rates) corresponding to the target zone 102. A given temperature recovery rate is the rate at which the actual temperature changes to reach the normal temperature set point value during the fallback recovery period.

[0089] Figure 4A process flow depicting a method 400 for controlling fallback of an HVAC system 104 according to one or more embodiments of the present disclosure is illustrated. The method 400 may be implemented by the fallback control system 108.

[0090] At step 402 , method 400 includes monitoring an interior temperature of a target zone associated with an HVAC system.

[0091] At 404 , method 400 includes monitoring an external temperature of a target zone associated with the HVAC system.

[0092] At step 406, method 400 includes determining one or more operating parameters associated with a first HVAC unit of the HVAC system. The one or more operating parameters may include at least one of excess capacity of the first HVAC unit or a relative operating cost of the first HVAC unit relative to a second HVAC unit.

[0093] At step 408, method 400 includes determining a recovery time based on the determined one or more operating parameters. The recovery time indicates a time required by the first HVAC unit to restore the interior temperature value of the target zone from the fallback temperature set point value to the normal temperature set point value.

[0094] At 410 , method 400 includes triggering a fallback restoration based on the determined restoration time and a remaining time in a fallback period associated with the fallback of the HVAC system.

[0095] Although shown and described in a particular sequence Figure 4 However, according to various embodiments of the present disclosure, the steps may appear in a variation of this sequence. Figure 4 A detailed description of the various steps involved is included in the Figure 1-3c The relevant description is omitted in this article for the sake of brevity.

[0096] The system and method provide an optimized backoff of an HVAC system, wherein the backoff recovery can be optimized for the lowest operating cost of the HVAC system during the backoff period. The backoff can be designed so that the interior temperature can be restored to normal using only a low-cost heating source at the end of the backoff period.

[0097] It is appreciated that although the details are explained with reference to heating of the target region, similar details apply when cooling of the target region.

[0098] As will be apparent to those skilled in the art, various working modifications may be made to the methods disclosed herein in order to implement the inventive concepts as taught herein.

[0099] In addition, the actions of any flowchart do not need to be implemented in the order shown; nor do they necessarily require all actions in the action to be performed. Similarly, those actions that do not depend on other actions can be performed in parallel with other actions.

[0100] The accompanying drawings and the foregoing description give examples of embodiments. It will be appreciated by those skilled in the art that one or more of the elements described may be well combined into a single functional element. Alternatively, some elements may be divided into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, the order of the processes described herein may be changed and are not limited to the methods described herein.

[0101] Benefits, other advantages, and solutions to problems have been described above with respect to specific embodiments. However, the benefits, advantages, solutions to problems, and any (one or more) components that may cause any benefit, advantage, or solution to appear or become more significant are not to be construed as key, required, or essential features or components of any or all claims.

[0102] Although specific language has been used to describe the subject matter, any limitation resulting therefrom is not intended. As will be apparent to those skilled in the art, various modifications in operation may be made to the method to realize the inventive concept as taught herein. The accompanying drawings and the foregoing description provide examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may be well combined into a single functional element. Alternatively, some elements may be divided into a plurality of functional elements. Elements from one embodiment may be added to another embodiment.

Claims

1. A fallback control system for controlling fallback of a heating, ventilation, and air conditioning (HVAC) system, the system comprising a first HVAC unit and a second HVAC unit, the fallback control system comprising: Memory; as well as one or more processors communicatively coupled to the memory, the one or more processors configured to: monitoring an interior temperature of a target zone associated with the HVAC system; monitoring an external temperature of the target area associated with the HVAC system; determining one or more operating parameters associated with the first HVAC unit of the HVAC system, wherein the one or more operating parameters include at least one of excess capacity of the first HVAC unit or a relative operating cost of the first HVAC unit relative to the second HVAC unit; determining a recovery time based on the determined one or more operating parameters, the recovery time indicating a time required by the first HVAC unit to restore an interior temperature value of the target zone from a fallback temperature set point value to a normal temperature set point value; as well as A fallback restoration is triggered based on the determined restoration time and a remaining time in a fallback period associated with the fallback of the HVAC system.

2. The system according to claim 1, wherein: The one or more processors are configured to, before triggering the rollback recovery: The remaining time in the backoff period is continuously monitored, wherein the backoff period indicates a period of time that the HVAC system operates in a backoff mode, and wherein the remaining time indicates a time remaining when the backoff period is complete.

3. The system according to claim 1, wherein: To trigger the rollback recovery, the one or more processors are configured to: comparing the determined recovery time to the determined remaining time; and When it is determined that the determined recovery time is equal to the determined remaining time, the rollback recovery is triggered.

4. The system according to claim 1, wherein: The normal temperature set point value indicates a temperature value maintained when the HVAC system is operated in a normal mode, and wherein the fallback temperature set point value indicates a temperature value maintained during the fallback period when the HVAC system is operated in a fallback mode.

5. The system according to claim 4, wherein: The one or more processors are configured to trigger the fallback recovery before the internal temperature value of the target zone reaches the fallback temperature set point value.

6. The system according to claim 1, wherein: To determine the recovery time, the one or more processors are further configured to determine the recovery time based on one or more of a current internal temperature value, a maximum capacity of the first HVAC unit, an operating cost of the first HVAC unit, a temperature difference between the internal temperature and the external temperature, and a thermal conductivity of a barrier separating the target area and an area outside the target area.

7. A method for controlling fallback of a heating, ventilation, and air conditioning (HVAC) system, the system comprising a first HVAC unit and a second HVAC unit, the method being performed by a fallback control system, the method comprising: monitoring an interior temperature of a target zone associated with the HVAC system; monitoring an external temperature of the target area associated with the HVAC system; determining one or more operating parameters associated with the first HVAC unit of the HVAC system, wherein the one or more operating parameters include at least one of excess capacity of the first HVAC unit or a relative operating cost of the first HVAC unit relative to the second HVAC unit; determining a recovery time based on the determined one or more operating parameters, the recovery time indicating a time required by the first HVAC unit to restore an interior temperature value of the target zone from a fallback temperature set point value to a normal temperature set point value; as well as A fallback restoration is triggered based on the determined restoration time and a remaining time in a fallback period associated with the fallback of the HVAC system.

8. The method according to claim 7, wherein: The method comprises, before triggering the rollback recovery: The remaining time in the backoff period is continuously monitored, wherein the backoff period indicates a period of time that the HVAC system operates in a backoff mode, and wherein the remaining time indicates a time remaining when the backoff period is complete.

9. The method according to claim 7, wherein: Triggering the rollback recovery includes: comparing the determined recovery time to the determined remaining time; and When it is determined that the determined recovery time is equal to the determined remaining time, the rollback recovery is triggered.

10. The method according to claim 7, wherein: The normal temperature set point value indicates a temperature value maintained when the HVAC system is operated in a normal mode, and wherein the fallback temperature set point value indicates a temperature value maintained during the fallback period when the HVAC system is operated in a fallback mode. 11 . The method of claim 10 , further comprising triggering the fallback recovery before the interior temperature value of the target zone reaches the fallback temperature set point value.

12. The method according to claim 7, wherein: Determining the recovery time includes determining the recovery time based on one or more of a current internal temperature value, a maximum capacity of the first HVAC unit, an operating cost of the first HVAC unit, a temperature difference between the internal temperature and the external temperature, and a thermal conductivity of a barrier separating the target area and an area outside the target area.

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