Heat pump water heater low-temperature freezing oil return control method and system based on dynamic adjustment of operation parameters

Abstract

The invention discloses a heat pump water heater low-temperature freezing oil return control method and system based on dynamic operation parameter adjustment, and the method comprises the following steps: monitoring the evaporator outlet refrigerant temperature, the compressor air return port temperature and the environment temperature in real time through a sensor, and calculating the temperature difference as a core control parameter; the opening degree of an electronic expansion valve and the rotating speed of a fan are dynamically adjusted through a fuzzy control algorithm in combination with the environment temperature and the compressor running frequency, and the low-temperature oil return stability of the system is maintained; when the core temperature difference exceeds a set threshold value, an oil return compensation mode is triggered, and the circulating fluidity of lubricating oil is enhanced by improving the frequency of a compressor and adjusting the opening degree of a bypass valve of a condenser; in the oil return compensation process, closed-loop adjustment is conducted on the exhaust temperature of the compressor through a PID control algorithm, and the operation safety of the system is ensured. The operating parameters are dynamically adjusted, the parameters such as the environment temperature and the system load are monitored in real time, and the control parameters are dynamically adjusted according to the parameters, so that the oil return requirements under different working conditions are met.

Description

Technical Field

[0001] The present invention relates to the technical field, and specifically to a low-temperature freezing oil return control method and system for a heat pump water heater based on dynamically adjusting operating parameters. Background Art

[0002] Low-temperature freezing oil return control is the core technology of an ultra-low-temperature variable-frequency heat pump water heater, aiming to solve the problems of difficult oil return of the compressor and decreased stability of the refrigerant cycle in a low-temperature environment. Its core logic is to ensure the efficient return of the refrigeration oil to the compressor through multi-parameter monitoring and dynamic strategy optimization, thereby maintaining system lubrication, preventing equipment failures, and improving the heating efficiency under low-temperature conditions.

[0003] Traditional heat pump water heaters usually use fixed control parameters for oil return control and cannot dynamically adjust according to real-time operating conditions (such as ambient temperature, system load, etc.). This static control strategy often fails to ensure the oil return efficiency in a low-temperature freezing environment, easily leading to insufficient or excessive oil return, and thus affecting the system performance and stability.

[0004] In a low-temperature freezing environment, traditional heat pump water heaters may experience difficult oil return due to the increased viscosity and decreased fluidity of the lubricating oil. Traditional methods often lack an effective intelligent compensation mechanism and cannot automatically take remedial measures when the oil return is insufficient, resulting in a decline in system performance or even failures. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the above technical defects and provide a low-temperature freezing oil return control method and system for a heat pump water heater based on dynamically adjusting operating parameters.

[0006] To solve the above problems, the technical solution of the present invention is a low-temperature freezing oil return control method for a heat pump water heater based on dynamically adjusting operating parameters, including the following steps: S1. Real-time monitor the refrigerant temperature at the outlet of the evaporator, the suction temperature of the compressor, and the ambient temperature through sensors, calculate the temperature difference, and use it as the core control parameter; S2. Combine the ambient temperature and the operating frequency of the compressor, and use a fuzzy control algorithm to dynamically adjust the opening of the electronic expansion valve and the speed of the fan to maintain the stability of low-temperature oil return in the system; S3. When the core temperature difference exceeds the set threshold, trigger the oil return compensation mode, and enhance the fluidity of the lubricating oil circulation by increasing the compressor frequency and adjusting the opening of the condenser bypass valve; S4. During the oil return compensation process, use a PID control algorithm to perform closed-loop regulation on the exhaust temperature of the compressor to ensure the safety of system operation.

[0007] Further, the oil return compensation mode in step S3 is triggered under any of the following conditions: The compressor runs continuously for more than the set duration and the viscosity of the lubricating oil is abnormal; Monitor the state of the oil separator through a vibration sensor and forcibly start it when the fluidity of the lubricating oil is insufficient.

[0008] Furthermore, after the oil return compensation ends, the system pressure is stabilized by gradually reducing the compressor frequency and maintaining the fan speed, and the stabilization time is dynamically adjusted according to the ambient temperature.

[0009] Furthermore, in step S2, the fuzzy control algorithm generates control commands by comprehensively considering the temperature difference, ambient temperature, and compressor frequency, and dynamically adjusts the opening degree of the electronic expansion valve and the fan speed to optimize the system energy efficiency.

[0010] Furthermore, in step S4, the PID control algorithm dynamically adjusts the control parameters according to the deviation between the compressor exhaust temperature and the safety threshold to ensure that the exhaust temperature is always within the safe range.

[0011] A low-temperature freezing oil return control system for a heat pump water heater based on dynamically adjusting operating parameters includes the following modules: A data acquisition module that monitors the system temperature, pressure, and lubricating oil status in real time; A control module that generates control commands based on the monitored data and dynamically adjusts the system operating parameters through an algorithm; An execution module that includes an electronic expansion valve, a variable-frequency fan, a bypass valve, and a compressor drive unit to execute the control commands; A safety protection module that triggers an alarm or shutdown protection when the oil return is abnormal; A fault diagnosis module that identifies system faults by comparing actual parameters with predicted values and switches to a backup control strategy.

[0012] Furthermore, the control module includes the following units: An ambient temperature compensation unit that automatically adjusts the control threshold according to the ambient temperature; A frequency adaptive unit that optimizes the control strategy based on the compressor historical operation data to improve the system energy efficiency.

[0013] Furthermore, the data acquisition module also includes an oil level sensor to monitor the lubricating oil level and trigger an emergency oil return mode when the level is too low.

[0014] Furthermore, the control module also includes the following units: A remote communication unit that remotely sets parameters through a mobile terminal APP or a cloud platform to achieve remote monitoring and debugging of the system; Historical data storage unit, which records the trigger time, duration and effect evaluation index of each oil return compensation mode, providing data support for the optimization of subsequent control strategies.

[0015] The advantages of the present invention compared with the existing technologies are as follows: The present invention provides a low-temperature freezing oil return control method and system for heat pump water heaters based on dynamically adjusting operating parameters. By dynamically adjusting operating parameters, monitoring parameters such as ambient temperature and system load in real time, and dynamically adjusting control parameters according to these parameters to meet the oil return requirements under different working conditions, it effectively solves the problem of difficult oil return of the compressor in low-temperature environments, ensures the normal circulation of lubricating oil, and improves the stability and reliability of the system; The present invention provides a low-temperature freezing oil return control method and system for heat pump water heaters based on dynamically adjusting operating parameters. It adopts a multi-parameter monitoring and intelligent compensation mechanism, combines multi-parameter monitoring systems such as temperature and vibration to monitor the system state, and automatically triggers the oil return compensation mode when the oil return is insufficient. By increasing the compressor frequency and adjusting the opening degree of the condenser bypass valve, it enhances the fluidity of the lubricating oil circulation, significantly improves the system stability and performance, and ensures the normal operation of the system in low-temperature freezing environments. Brief Description of the Drawings

[0016] Figure 1 is a flowchart of the low-temperature freezing oil return control method for heat pump water heaters based on dynamically adjusting operating parameters of the present invention.

[0017] Figure 2 is a block diagram of the low-temperature freezing oil return control system for heat pump water heaters based on dynamically adjusting operating parameters of the present invention. Detailed Embodiments

[0018] Here, the exemplary embodiments will be described in detail, and the examples are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. On the contrary, they are only examples of devices consistent with some aspects of the present disclosure as detailed in the appended claims.

[0019] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0020] Such as Figure 1As shown in the figure, this embodiment proposes a low-temperature freezing oil return control method for a heat pump water heater based on dynamically adjusting operating parameters, including the following steps: S1. Real-time monitor the refrigerant temperature at the evaporator outlet, the suction temperature of the compressor, and the ambient temperature through sensors, calculate the temperature difference, and use it as the core control parameter; S2. Combine the ambient temperature and the compressor operating frequency, and use a fuzzy control algorithm to dynamically adjust the opening of the electronic expansion valve and the fan speed to maintain the stability of the low-temperature oil return of the system; S3. When the core temperature difference exceeds the set threshold, trigger the oil return compensation mode, and enhance the lubricating oil circulation fluidity by increasing the compressor frequency and adjusting the opening of the condenser bypass valve; S4. During the oil return compensation process, use a PID control algorithm to perform closed-loop regulation on the compressor discharge temperature to ensure the safety of system operation.

[0021] Real-time monitor the refrigerant temperature (T1) at the outlet side of the evaporator and the suction temperature (T2) of the compressor of the heat pump water heater through a temperature sensor, calculate the temperature difference ΔT = T2 - T1 between the two, and use ΔT as the core parameter. Combine the ambient temperature ( ) and the real-time operating frequency (f) of the compressor. Through a fuzzy control algorithm, generate the adjustment amount (Δθ) of the opening of the electronic expansion valve (θ) and the adjustment amount (ΔV) of the fan speed (V), and dynamically adjust the system operating parameters to maintain the stability of the low-temperature oil return cycle. When ΔT exceeds the preset safety threshold , automatically trigger the oil return compensation mode, and increase the compressor operating frequency to in stages and synchronously adjust the opening of the condenser bypass valve (φ) to forcibly enhance the circulating fluidity of the lubricating oil in the oil separator. During the operation of the oil return compensation mode, use a PID control algorithm to perform closed-loop control on the compressor discharge temperature ( ), and ensure that T_dis is always lower than the preset maximum allowable temperature ( ) by dynamically adjusting the PID parameters.

[0022] Further, in step S2, the fuzzy control algorithm generates control instructions by comprehensively considering the temperature difference, ambient temperature, and compressor frequency, and dynamically adjusts the opening of the electronic expansion valve and the fan speed to optimize the system energy efficiency.

[0023] The input variables of the fuzzy control algorithm include ΔT, and f, and the output variables are the correction amounts (Δθ, ΔV) of θ and V, and satisfy the following relationship: Among them, is the weight coefficient calibrated based on experimental data;

[0024] Among them, is the ambient temperature target value, is the dynamic adjustment coefficient, and the value of and increases linearly with the increase of the difference between

[0025] Furthermore, the oil return compensation mode in step S3 is triggered under any of the following conditions: The compressor runs continuously for more than the set duration, and the lubricating oil viscosity is abnormal; The oil separator state is monitored by a vibration sensor, and it is forced to start when the fluidity of the lubricating oil is insufficient.

[0026] When the continuous operation time of the compressor ( ) exceeds the preset duration , and the lubricating oil viscosity (μ) calculated by the vibration sensor installed at the bottom of the oil separator exceeds , the oil return compensation mode is forced to start. The calculation formula for the lubricating oil viscosity μ is:

[0027] where is the vibration frequency measured by the vibration sensor, is a constant calibrated by the lubricating oil type.

[0028] Furthermore, in step S4, the PID control algorithm dynamically adjusts the control parameters according to the deviation between the compressor exhaust temperature and the safety threshold to ensure that the exhaust temperature is always within the safe range.

[0029] The parameter tuning rules of the PID control algorithm are: The proportional coefficient varies with and The difference Δ is dynamically adjusted. When Δ , , where is the acceleration factor, and its value range is 0.1~0.5; The integral time constant and the differential time constant are adaptively adjusted according to the compressor frequency f, [[ID=6�]]where is the attenuation coefficient, the value range of is 0.01~0.1, Further, after the oil return compensation ends, the system pressure is stabilized by gradually reducing the compressor frequency and maintaining the fan speed. The stabilization time is dynamically adjusted according to the ambient temperature.

[0030] After the oil return compensation mode ends, by gradually reducing the compressor frequency to 80% of the original operating frequency and maintaining the fan speed at , for time to stabilize the system pressure; The time is dynamically adjusted according to the ambient temperature , and the adjustment formula is:

[0031] where, is the reference temperature, δ is the time adjustment coefficient, and the value range of δ is 0.02 - 0.1 As Figure 2 shown, this embodiment proposes a low-temperature freezing oil return control system for a heat pump water heater based on dynamically adjusting operating parameters, including the following modules: Data acquisition module, which monitors the system temperature, pressure, and lubricating oil status in real time; Control module, which generates control instructions through an algorithm based on the monitored data and dynamically adjusts the system operating parameters; Execution module, which includes an electronic expansion valve, a variable-frequency fan, a bypass valve, and a compressor drive unit to execute the control instructions; Safety protection module, which triggers an alarm or shutdown protection when the oil return is abnormal; Fault diagnosis module, which identifies system faults and switches to a standby control strategy by comparing the actual parameters with the predicted values.

[0032] Further, the data acquisition module also includes an oil level sensor to monitor the lubricating oil level and trigger an emergency oil return mode when the level is too low.

[0033] Further, the control module includes the following units: Ambient temperature compensation unit, which automatically adjusts the control threshold according to the ambient temperature; Frequency adaptive unit, which optimizes the control strategy according to the compressor historical operation data to improve the system energy efficiency.

[0034] Further, the control module also includes the following units: Remote communication unit, which remotely sets parameters through a mobile terminal APP or a cloud platform to achieve remote monitoring and debugging of the system; Historical data storage unit, which records the triggering time, duration, and effect evaluation indicators of each fuel return compensation mode, providing data support for subsequent optimization of control strategies.

[0035] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device.

[0036] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

[0037] The above describes the present invention and its implementation manners. Such description is not restrictive. What is shown in the drawings is only one of the implementation manners of the present invention, and the actual structure is not limited thereto. Generally speaking, if those of ordinary skill in the art are inspired by it and design similar structural manners and embodiments without creative efforts without departing from the purpose of the present invention, they shall fall within the protection scope of the present invention.

Claims

1. A low-temperature freezing oil return control method for a heat pump water heater based on dynamically adjusting operating parameters, characterized in that It includes the following steps: S1. Real-time monitor the refrigerant temperature at the evaporator outlet, the suction temperature of the compressor, and the ambient temperature through sensors, calculate the temperature difference and use it as the core control parameter; S2. Combine the ambient temperature and the compressor operating frequency, and adopt a fuzzy control algorithm to dynamically adjust the opening of the electronic expansion valve and the fan speed to maintain the low-temperature oil return stability of the system; S3. When the core temperature difference exceeds the set threshold, trigger the oil return compensation mode, enhance the lubricating oil circulation fluidity by increasing the compressor frequency and adjusting the opening of the condenser bypass valve; S4. During the oil return compensation process, adopt a PID control algorithm to perform closed-loop regulation on the compressor discharge temperature to ensure the safe operation of the system.

2. The low-temperature freezing and oil return control method of a heat pump water heater based on dynamically adjusting operating parameters according to claim 1, characterized in that In step S2, the fuzzy control algorithm generates control instructions by comprehensively considering the temperature difference, ambient temperature, and compressor frequency, and dynamically adjusts the opening of the electronic expansion valve and the fan speed to optimize the system energy efficiency.

3. The low-temperature freezing oil return control method for a heat pump water heater based on dynamically adjusting operating parameters according to claim 1, characterized in that The oil return compensation mode in step S3 is triggered under any of the following conditions: The compressor runs continuously for more than the set duration and the lubricating oil viscosity is abnormal; Monitor the state of the oil separator through a vibration sensor and forcibly start when the lubricating oil fluidity is insufficient.

4. The low-temperature freezing oil return control method for a heat pump water heater based on dynamically adjusting operating parameters according to claim 1, wherein In step S4, the PID control algorithm dynamically adjusts the control parameters according to the deviation between the compressor discharge temperature and the safety threshold to ensure that the discharge temperature is always within the safe range.

5. The low-temperature freezing oil return control method of a heat pump water heater based on dynamically adjusting operating parameters according to claim 1, characterized in that: After the oil return compensation ends, gradually reduce the compressor frequency and maintain the fan speed to stabilize the system pressure, and the stabilization time is dynamically adjusted according to the ambient temperature.

6. A low-temperature freezing and oil return control system for a heat pump water heater based on dynamically adjusting operating parameters, characterized in that, It includes the following modules: Data acquisition module, which real-time monitors the system temperature, pressure, and lubricating oil state; Control module, which generates control instructions based on the monitored data and dynamically adjusts the system operating parameters through algorithms; Execution module, which includes an electronic expansion valve, a variable-frequency fan, a bypass valve, and a compressor drive unit to execute control instructions; Safety protection module, which triggers an alarm or shutdown protection when the oil return is abnormal; Fault diagnosis module, which identifies system faults by comparing actual parameters with predicted values and switches to a backup control strategy.

7. The low-temperature freezing and oil return control system for a heat pump water heater based on dynamically adjusting operating parameters according to claim 6, wherein: The data acquisition module also includes an oil level sensor to monitor the lubricating oil level and trigger an emergency oil return mode when the level is too low.

8. The low-temperature freezing and oil return control system of a heat pump water heater based on dynamically adjusting operating parameters according to claim 6, characterized in that, The control module includes the following units: Ambient temperature compensation unit, which automatically adjusts the control threshold according to the ambient temperature; Frequency adaptive unit, which optimizes the control strategy according to the compressor historical operation data to improve the system energy efficiency.

9. The low-temperature freezing oil return control system for a heat pump water heater based on dynamically adjusting operating parameters according to claim 6, characterized in that, The control module also includes the following units: Remote communication unit, which remotely sets parameters through a mobile terminal APP or a cloud platform to realize remote monitoring and debugging of the system; Historical data storage unit, which records the trigger time, duration, and effect evaluation index of each oil return compensation mode to provide data support for subsequent control strategy optimization.

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