A defrosting control method of a variable frequency air conditioner and a variable frequency air conditioner controller

Abstract

This invention discloses a defrosting control method and controller for variable frequency air conditioners. The controller dynamically fits the initial opening degree of heat storage based on the indoor ambient temperature and limits it to 350-450 pps. In high-temperature conditions, the opening degree is increased to prevent shutdown; in low-temperature conditions, the opening degree is decreased to fully store heat. The fixed heat storage time is eliminated; the valve opens when the coil temperature reaches 48-52℃, reducing the low-temperature defrosting time from 10 minutes to 7 minutes while ensuring thorough defrosting. During defrosting, the valve is adjusted in steps: it closes the valve and heats up at 39-41℃, stopping at 44-46℃ to eliminate the risk of liquid slugging. When the valve reaches the lower limit and the temperature is too low, the frequency is increased to supplement heat, and protection is provided through exhaust temperature monitoring, achieving dual-parameter redundant control. Dual-parameter fusion determines the defrosting entry condition to avoid false defrosting. A smooth transition after defrosting prevents vibration; when the coil temperature reaches 10-15℃ after defrosting, the fan is started at low speed to prevent secondary icing. A self-learning mechanism updates the baseline value based on historical data, providing full lifecycle self-adaptation. Only software upgrades are required, no new hardware is needed, it is compatible with single-sensor models, and is low-cost and highly versatile.

Description

Technical Field

[0001] This invention relates to the field of air conditioning technology, specifically to a defrosting control method and controller for a variable frequency air conditioner. Background Technology

[0002] Currently, most household inverter air conditioners only have one external coil temperature sensor in their outdoor heat exchanger, and this sensor is located in the middle to rear section of the condenser flow path. Conventional hot gas defrosting requires adding an external coil temperature sensor at the condenser's cooling inlet (heating mode outlet). This invention addresses the technical deficiencies in the hot gas defrosting control method for models with only one conventional external coil temperature sensor, specifically by innovatively optimizing the method for defrosting (hot gas defrosting) in heating mode without reversing the four-way valve.

[0003] The existing workflow for hot gas defrosting in heating mode with the four-way valve not reversing is as follows: When the air conditioner is running in heating mode, when the amount of frost on the outdoor condenser reaches the defrosting trigger condition and the outdoor coil temperature drops to a preset threshold, the system determines that it is entering the hot gas defrosting process. First, the indoor unit fan and the outdoor unit fan are turned off, and the four-way valve remains in heating mode without reversing, and the whole unit continues to maintain heating operation; then, the electronic expansion valve is adjusted to a fixed opening (usually 400pps) to store heat in the refrigerant, and the heat storage time is fixed at 2 minutes; after the heat storage stage is completed, the electronic expansion valve is opened to near the maximum opening (480~500pps), and the high-temperature refrigerant returning from the indoor unit evaporator flows through the outdoor condenser to achieve the defrosting operation.

[0004] The existing control scheme with fixed opening and fixed duration has obvious technical defects, as follows: 1. Poor defrosting performance in low-temperature indoor environments can easily lead to liquid slugging in the compressor. When the indoor ambient temperature At that time, a fixed 2-minute heat storage time was insufficient to ensure adequate heat storage by the refrigerant, resulting in an overall low refrigerant temperature. After defrosting with the valve open, the indoor coil temperature remained below 4 degrees Celsius. The outdoor condenser coil temperature is lower than During defrosting, the refrigerant's heat is continuously consumed by outdoor defrosting heat exchange, causing the temperature to drop continuously; the outdoor coil temperature only briefly rises to [a certain level] in the first 2 minutes after the valve is opened. The temperature continued to drop, and even after running for up to 10 minutes, defrosting could not be completely completed, leaving frost residue. Simultaneously, the low-temperature refrigerant flowed back into the compressor, which could easily cause liquid slugging, severely impacting the reliability of the air conditioner.

[0005] 2. High-temperature protection is triggered in high-temperature indoor environments, interrupting the defrosting process. When the indoor ambient temperature At this time, the accumulated heat in the indoor environment leads to excessive heat storage in the refrigerant. Under fixed control parameters, the heat storage time is less than 2 minutes before the indoor coil temperature reaches the preset heating overload protection threshold, triggering the air conditioner's shutdown protection and directly terminating the defrosting process, thus failing to complete defrosting.

[0006] 3. Fixed control parameters result in poor adaptability to operating conditions. The opening degree of the electronic expansion valve and the refrigerant heat storage time are fixed values, which cannot be adaptively adjusted according to changes in indoor ambient temperature. It can only be adapted to a narrow range of operating conditions, and cannot balance defrosting effect and equipment operation safety in both high and low temperature environments.

[0007] Currently, the industry generally uses the above-mentioned fixed parameter control logic for this type of single-sensor, four-way valve non-reversing hot gas defrosting structure, and there is no effective dynamic control scheme. The above-mentioned technical defects have existed for a long time. Summary of the Invention

[0008] The purpose of this invention is to provide a defrosting control method and a controller for a variable frequency air conditioner to solve the problems mentioned in the background art.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a defrosting control method for a variable frequency air conditioner, the method being applied to a hot gas defrosting process in heating mode where the four-way valve does not switch direction, comprising the following steps: S1. Collect the air conditioner operating parameters and determine whether the defrosting start conditions are met based on the operating parameters; S2. When the defrosting entry conditions are met, based on the indoor ambient temperature... Dynamic calculation of the initial opening degree of the electronic expansion valve for thermal storage And adjust the electronic expansion valve to the initial opening degree of the thermal storage. It enters the refrigerant heat storage stage; S3. After entering the refrigerant heat storage stage, the indoor coil temperature is collected in real time. The fixed heat storage duration limit is removed, and when the indoor coil temperature... When the first preset temperature threshold is reached, the electronic expansion valve is opened to the defrost opening degree to start hot gas defrosting. S4. During defrosting operation, monitor the indoor coil temperature in real time. According to the indoor coil temperature Dynamically adjust the opening degree of the electronic expansion valve; S5. Real-time acquisition of outdoor coil temperature When the outdoor coil temperature When the defrosting end threshold is reached, defrosting is determined to be complete, and the air conditioner is controlled to resume heating operation mode.

[0010] A variable frequency air conditioner controller has a built-in computer program that executes a variable frequency air conditioner defrosting control method when running. Compared with the prior art, the beneficial effects of the present invention are: By dynamically fitting the initial opening of the electronic expansion valve for heat storage to the indoor ambient temperature and limiting it to a boundary of 350-450 pps, the valve automatically increases its opening under high-temperature conditions to prevent overheating and shutdown, and automatically decreases its opening to fully store heat under low-temperature conditions. The fixed 2-minute heat storage time has been eliminated; instead, the valve opening is based on an indoor coil temperature of 48-52℃. Tests have shown that the defrosting time under low-temperature conditions has been reduced from 10 minutes to 7 minutes, with complete frost removal. During defrosting, the valve opening is adjusted in steps according to the indoor coil temperature. The valve closes at 39-41℃ to raise the refrigerant temperature, and stops closing at 44-46℃, eliminating the risk of compressor liquid slugging at its source. Simultaneously, compressor frequency control is introduced. When the valve has reached the lower limit of 350 pps but the temperature is still too low, the frequency is increased to supplement heat, and protection is provided through exhaust temperature monitoring, forming a dual-parameter redundant control. The defrosting entry condition is determined by fusing the indoor coil temperature drop and the electronic expansion valve closing amplitude, avoiding false or missed defrosting. After defrosting, heating parameters are restored using a smooth transition strategy to prevent system oscillation. When the outdoor coil temperature reaches 10-15℃ after defrosting, the outdoor fan is started at low speed to accelerate the evaporation of defrost water and prevent secondary icing.

[0011] This solution also includes a self-learning mechanism that automatically updates the temperature fitting benchmark value based on historical operating data, achieving adaptive optimization throughout the entire lifecycle. All improvements can be implemented solely through software upgrades, requiring no new hardware, and are compatible with existing single-sensor inverter air conditioner models, resulting in low retrofit costs and high versatility. Attached Figure Description

[0012] Figure 1 This is a flowchart of the present invention; Figure 2 This is a schematic diagram showing the temperature trend of the inner coil in the hot air defrosting system of the present invention. Figure 3 This is a schematic diagram showing the temperature trend of the external coil for hot air defrosting in this invention. Detailed Implementation

[0013] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0014] Please see Figure 1-3This invention provides a technical solution: a defrosting control method for a variable frequency air conditioner. The method is applied to a hot gas defrosting process where the four-way valve does not switch direction in heating mode, and includes the following steps: S1. Collect the air conditioner operating parameters and determine whether the defrosting start conditions are met based on the operating parameters; S2. When the defrosting entry conditions are met, based on the indoor ambient temperature... Dynamic calculation of the initial opening degree of the electronic expansion valve for thermal storage And adjust the electronic expansion valve to the initial opening degree of the thermal storage. It enters the refrigerant heat storage stage; S3. After entering the refrigerant heat storage stage, the indoor coil temperature is collected in real time. The fixed heat storage duration limit is removed, and when the indoor coil temperature... When the first preset temperature threshold is reached, the electronic expansion valve is opened to the defrost opening degree to start hot gas defrosting. S4. During defrosting operation, monitor the indoor coil temperature in real time. According to the indoor coil temperature Dynamically adjust the opening degree of the electronic expansion valve; S5. Real-time acquisition of outdoor coil temperature When the outdoor coil temperature When the defrosting end threshold is reached, defrosting is determined to be complete, and the air conditioner is controlled to resume heating operation mode.

[0015] More specifically, the method includes the following steps when implemented: Step S100: Determining defrosting conditions and pre-processing the entire machine The air conditioner operates normally in heating mode, collecting real-time operating parameters such as outdoor coil temperature, outdoor ambient temperature, indoor ambient temperature, and indoor coil temperature. When the defrosting conditions are met based on these operating parameters, the system enters the defrosting preparation stage. The indoor and outdoor unit fans are stopped, and the four-way valve maintains the heating operation.

[0016] Furthermore, the method for determining the defrosting start condition is as follows: The indoor coil temperature drop value of the air conditioner in heating mode is collected. and the closing amplitude value of the electronic expansion valve ; according to and Determine the heating frosting constant : ; in, and The weighting coefficient is dimensionless; when the heating frosting constant is... Greater than the preset frosting constant threshold When the conditions for defrosting are met, it is determined that the conditions for defrosting are met.

[0017] Furthermore, this solution adopts and The dual-parameter fusion judgment is because when frosting occurs, the indoor coil temperature drops (reflecting the reduction in heating capacity), and at the same time, the electronic expansion valve closes slightly (attempting to increase the condensing temperature). The combination of the two can more accurately reflect the amount of frosting and avoid interference from environmental fluctuations on a single temperature threshold.

[0018] Step S200: Dynamically calculate and set the initial opening degree of the electronic expansion valve for thermal storage. Real-time collection of indoor ambient temperature Substitute into the formula to calculate the initial opening degree of the electronic expansion valve for thermal storage. : ; in, Indoor ambient temperature; The initial opening of the electronic expansion valve for thermal storage; constants 5 and 32 are the temperature fitting reference values; adjust the electronic expansion valve to... It enters the refrigerant heat storage stage; the initial opening degree is strictly limited to 350pps~450pps; This formula achieves a smooth change in opening degree with temperature through linear interpolation, using a larger value at high temperatures to prevent overheating and a smaller value at low temperatures to promote heat storage. Furthermore, 5 and 32 in the formula represent the fitting boundaries, determined through extensive experimentation. When When the minimum opening is 350pps, the refrigerant residence time in the indoor heat exchanger is extended, increasing heat absorption; when The maximum opening is set to 450pps to increase the flow rate and prevent overheating from triggering the instantaneous overload protection shutdown of the internal panel.

[0019] Step S300: Initiate formal defrosting based on indoor coil temperature Real-time monitoring of indoor coil temperature throughout the process Remove the fixed thermal storage duration limit; when and (Preferred) When the temperature is high, immediately open the electronic expansion valve to a defrost setting of 350-500 pps and start hot air defrosting.

[0020] Step S400: Dynamically adjust the opening of the electronic expansion valve during defrosting. Continuous monitoring during defrosting phase Adjust the valve opening (range 350-500pps): when and (Preferred) When this happens, gradually close the valve to reduce the refrigerant temperature; when and (Preferred) When the valve is open, stop closing it and maintain the opening.

[0021] The "gradual valve closing" is preferably performed by reducing the valve by 5-10 pps every 5-10 seconds until the temperature rises or the opening reaches the lower limit of 350 pps, in order to avoid system oscillation. Furthermore, the step-by-step valve closing (5-10 seconds, 5-10 pps) can avoid sudden pressure changes caused by a large valve closing at once, and the temperature response is monitored after each valve closing to form a closed loop and ensure stable control.

[0022] Step S500: Compressor frequency coordinated control During the heat storage phase, the compressor operates at the first frequency. Running at current frequency, 90Hz; when defrosting starts, gradually increase the frequency to the second frequency. (Current frequency, 95Hz), upsampling rate .

[0023] During defrosting, if and If the valve opening has reached the lower limit of 350pps, the frequency is further increased (2-5Hz each time, 10-20s interval) to raise the exhaust temperature and replenish heat. Exhaust temperature is monitored simultaneously. When the exhaust temperature reaches the preset threshold, the frequency increase or decrease will be stopped to prevent overheating protection. Furthermore, when the opening degree has reached the lower limit and If the temperature is still low, increasing the frequency can increase the refrigerant circulation volume and exhaust temperature, replenish heat, and at the same time monitor the exhaust temperature to prevent it from getting too high and ensure safety.

[0024] Step S600: Defrost completion determination and machine reset Collect outdoor coil temperature Defrosting is considered complete when the outdoor ambient temperature is reached. Dynamic settings: ; In addition, the maximum defrosting time (10 min) or exhaust temperature threshold (30-60℃) can be used as auxiliary criteria to prevent abnormalities.

[0025] After defrosting, the electronic expansion valve is restored to its normal heating opening, and the outdoor and indoor fans are restarted in sequence to return to heating mode. Furthermore, the termination threshold varies. The segmented design is necessary because coils dissipate heat quickly in low-temperature environments. Using a uniform high threshold might prolong defrosting time and waste energy. The segmented setting balances thorough defrosting with energy efficiency.

[0026] Step S700: Smooth transition after defrosting To avoid abrupt parameter changes, a gradual transition is adopted: The electronic expansion valve opening is gradually adjusted from the current defrost opening to the normal heating opening at a certain rate. ; The compressor frequency will be gradually adjusted from the current defrosting frequency to the normal heating frequency, at a rate of ; When both reach the target value, it is determined that full recovery has been achieved; Furthermore, the selection of the smooth transition rate needs to take into account the system response time. An opening rate of 5–20 pps / s and a frequency rate of 0.5–2 Hz / s can avoid pressure oscillations and current surges.

[0027] Step S800: Coordinated Control of Indoor and Outdoor Fans Once defrosting conditions are met, the indoor and outdoor fans will stop running. After defrosting is complete, when... Da During defrosting, the outdoor fan starts at a low speed (20-40% of rated speed) to accelerate the evaporation of defrost water and prevent secondary icing. After defrosting is completed, the fan resumes its heating mode speed. Furthermore, after defrosting, when the outdoor fan is... Start at low speed when the temperature reaches 10-15℃. At this time, the frost layer has basically melted. Starting the fan can accelerate the evaporation of water and prevent the residual water from freezing again after defrosting.

[0028] Step S900: Control parameter self-learning Record the operation data for each defrosting cycle. , , (Valve opening degree, frequency, defrosting duration, etc.)

[0029] Based on multiple sets of data, the temperature fitting baseline value (constant 5 and / or 32) in the initial opening formula of thermal storage is dynamically updated. For example, if defrosting is incomplete in a certain temperature range after multiple defrosting attempts, the lower limit of the opening in that range is lowered or the end threshold is raised to achieve adaptive parameter optimization. Furthermore, the self-learning adjusts the baseline value based on historical data (operating conditions, control parameters, and effects). For example, if the defrosting time is too long in a certain temperature range, it automatically fine-tunes and lowers the lower limit of the opening in that range (or raises the end threshold), so that the control strategy is continuously optimized as the usage environment and performance degrade.

[0030] Combination Figure 2 The indoor coil temperature during the hot air defrosting process is shown. Schematic diagram of the trend: During the refrigerant heat storage stage (corresponding to step S200). The heating operating temperature gradually increases until it reaches the 48-52℃ (preferably 50℃) set in step S300. At this point, the system controls the electronic expansion valve to open to the defrost setting, officially entering the hot gas defrost stage. Once in the defrost stage, the high-temperature refrigerant is guided to the outdoor heat exchanger for defrosting. Gradually decrease; when When the temperature drops to the 39-41°C range, the system executes the gradual valve closing operation in step S400 to raise the refrigerant temperature, so that... The temperature rises and stabilizes in the 44-46℃ range until defrosting is complete. At the end of defrosting, with the assistance of compressor frequency control (step S500), Maintaining a steady recovery provides sufficient heat for resuming heating, while eliminating the risk of compressor liquid slugging at its source.

[0031] Combination Figure 3 The outdoor coil temperature during the hot air defrosting process is shown. Trend diagram: When defrosting is activated, high-temperature refrigerant flows into the outdoor heat exchanger. The temperature rises rapidly to a positive range (e.g., 10-12°C when the valve is opened). As the frost continues to melt and absorb heat, the temperature increases. Maintain a relatively stable or slightly fluctuating state during the defrosting process. Step S600 is reached based on the outdoor ambient temperature. The system determines that defrosting is complete when the set end threshold (10-20℃, using the lower value for low-temperature conditions and the higher value for high-temperature conditions) is reached. After defrosting is complete, The temperature continues to rise naturally. When it reaches 10-15°C, step S800 controls the outdoor fan to start at a low speed to accelerate the evaporation of residual defrost water and effectively prevent secondary icing.

[0032] in, Figure 2 This is a diagram of the inner plate temperature. Curve a indicates that the inner plate temperature is too high and a shutdown will be triggered; curve b indicates that the inner plate temperature is too low and defrosting is not complete; curve c indicates that defrosting is complete after optimization. Figure 3 This is a diagram of the outer plate temperature. Curve A indicates that the outer plate temperature is too low and defrosting is not complete; Curve B indicates that defrosting is complete after optimization. Specific implementation examples: Example 1: Initial Opening Calculation Example For a 1.5 HP inverter air conditioner, the formula is the same as above.

[0034] Operating Condition 1: , ; ; Operating Condition 2: , ; ; Example 2: Comparison Test with Original Fixed Parameters Original plan: fixed opening of 400pps, fixed heat storage of 2min.

[0035] Operating condition 1 (30℃ / 5℃): Heat storage time less than 2 minutes. Rise to The system was shut down due to protection measures, and defrosting failed.

[0036] Operating Condition 2 (8℃ / -5℃): Insufficient heat storage, valve opening After 4 minutes, the temperature dropped to 25°C, and after 10 minutes, it was only 22.5°C. The temperature is 10°C when the valve is opened, 2°C after 4 minutes, and 6°C after 10 minutes. Frost residue forms, posing a risk of liquid slugging.

[0037] Example 3: Dynamic Scheme Test of the Invention Operating Condition 1 (30℃ / 5℃): When the valve is opened The temperature reached 38°C after 4 minutes and rose to 45°C before the end of the process. No protection was applied throughout the process, and defrosting was normal.

[0038] Operating Condition 2 (8℃ / -5℃): ,by Open the valve, when opening the valve When it rises to 12℃, Close the valve, at the lowest The temperature dropped to 4℃ (from 2℃ in the original plan), and the defrosting time was shortened from 10 minutes to 7 minutes, then it ended. The frost layer was completely removed.

[0039] As can be seen from the above embodiments and the overall solution, the solution of this application has the following advantages: 1. Wide temperature range adaptability, protection against high temperature shutdown (corresponding to dynamic initial opening): according to Adaptive adjustment High temperatures should be used to increase the thermal storage rate and avoid [further issues]. Protection against temperatures exceeding 62℃ (this application uses 62℃ as an example; the specific temperature can be preset according to the actual protection threshold) ensures continuous defrosting.

[0040] 2. Improved efficiency and effectiveness of low-temperature defrosting (corresponding to dynamic opening degree + cancellation of fixed duration): Low temperatures are set to the minimum value to fully store heat, thus... Based on the valve opening criteria, the test showed that the defrosting time was reduced from 10 minutes to 7 minutes, and the frost layer was thoroughly removed.

[0041] 3. Eliminate the risk of liquid slugging (corresponding to dynamic valve control in the process): When the temperature is too low, the valve closes to raise the refrigerant temperature. This, combined with frequency adjustment, ensures a safe refrigerant temperature and prevents liquid slugging.

[0042] 4. Precise defrosting (corresponding to the frost constant): Dual-parameter fusion judgment to avoid accidental defrosting or missed defrosting.

[0043] 5. Frequency-opening coordination (corresponding to frequency control): When the valve is adjusted to its limit, frequency is supplemented to enhance the adaptability to extreme working conditions.

[0044] 6. Smooth transition and fan coordination: Reduces oscillations and noise caused by sudden parameter changes, accelerates defrost water evaporation, and prevents secondary icing.

[0045] 7. Self-learning and continuous optimization: Update baseline values ​​based on historical data to achieve full lifecycle self-adaptation.

[0046] 8. Low cost and high versatility: Only software upgrades are required, no new hardware is needed, it is compatible with existing single-sensor models, and it is easy to promote.

[0047] On another front, this solution also provides a variable frequency air conditioner controller with a built-in computer program that executes the aforementioned variable frequency air conditioner defrosting control method when running. In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially as a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium accessible to a computer or a data storage device such as a server or data center that integrates one or more available media. The available media may be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., DVDs), or semiconductor media (e.g., solid state disks (SSDs)).

[0048] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0049] The various embodiments in this specification are described in a related manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions of the method embodiments.

[0050] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A defrosting control method for a variable frequency air conditioner, characterized in that, The method is applied to the hot gas defrosting process where the four-way valve does not switch in heating mode, and includes the following steps: S1. Collect the air conditioner operating parameters and determine whether the defrosting start conditions are met based on the operating parameters; S2. When the defrosting entry conditions are met, based on the indoor ambient temperature... Dynamic calculation of the initial opening degree of the electronic expansion valve for thermal storage And adjust the electronic expansion valve to the initial opening degree of the thermal storage. It enters the refrigerant heat storage stage; S3. After entering the refrigerant heat storage stage, the indoor coil temperature is collected in real time. The fixed heat storage duration limit is removed, and when the indoor coil temperature... When the first preset temperature threshold is reached, the electronic expansion valve is opened to the defrost opening degree to start hot gas defrosting. S4. During defrosting operation, monitor the indoor coil temperature in real time. According to the indoor coil temperature Dynamically adjust the opening degree of the electronic expansion valve; S5. Real-time acquisition of outdoor coil temperature When the outdoor coil temperature When the defrosting end threshold is reached, defrosting is determined to be complete, and the air conditioner is controlled to resume heating operation mode.

2. The defrosting control method for a variable frequency air conditioner according to claim 1, characterized in that, The initial opening degree of thermal storage The calculation formula is: ； in, Indoor ambient temperature; 5 represents the initial opening degree of the electronic expansion valve for thermal storage; constants 5 and 32 are the temperature fitting reference values.

3. The defrosting control method for a variable frequency air conditioner according to claim 2, characterized in that, The initial opening degree of thermal storage It is mandatory to limit it to the range of 350pps to 450pps.

4. The defrosting control method for a variable frequency air conditioner according to claim 1, characterized in that, The first preset temperature threshold is and The defrost opening is 350pps to 500pps.

5. The defrosting control method for a variable frequency air conditioner according to claim 1, characterized in that, The defrosting process adjustment steps specifically include: When the indoor coil temperature and At that time, the electronic expansion valve is gradually closed and converged. When the indoor coil temperature and When the valve is closed, stop the valve closing action and maintain the current opening degree.

6. The defrosting control method for a variable frequency air conditioner according to claim 5, characterized in that, The "gradual valve closing and convergence" specifically refers to reducing the opening of the electronic expansion valve by 5-10 pps every 5-10 seconds until the indoor coil temperature reaches the specified level. Rebound to greater than and less than or equal to , or until the electronic expansion valve opening reaches the lower limit of 350pps.

7. The defrosting control method for a variable frequency air conditioner according to claim 1, characterized in that, The defrosting condition determination step specifically includes: Collect the indoor coil temperature drop value of the air conditioner in heating mode and the closing amplitude value of the electronic expansion valve ; Based on the indoor coil temperature drop value and the closing amplitude value of the electronic expansion valve Determine the heating frosting constant: ； in, and These are weighting coefficients, dimensionless. When the heating frosting constant Greater than the preset frosting constant threshold When the conditions for defrosting are met, it is determined that the conditions for defrosting are met.

8. The defrosting control method for a variable frequency air conditioner according to claim 1, characterized in that, It also includes compressor frequency control steps: During the refrigerant heat storage stage, control the compressor to operate at the first frequency. run; When hot gas defrosting starts, control the compressor from the first frequency. Gradually increase the frequency to the second frequency The upsampling rate is ; During the defrosting process, when the indoor coil temperature and Furthermore, when the electronic expansion valve opening reaches the lower limit of 350pps, the compressor frequency is increased.

9. The defrosting control method for a variable frequency air conditioner according to claim 1, characterized in that, In the defrosting completion determination step, the defrosting completion threshold is based on the outdoor ambient temperature. Dynamically determined: when At that time, the defrosting end threshold is ; when At that time, the defrosting end threshold is .

10. A variable frequency air conditioner controller, characterized in that, The controller has a built-in computer program, which executes the variable frequency air conditioner defrosting control method according to any one of claims 1 to 9 when it runs.

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