Heat pump non-stop defrosting control method and system based on double-evaporator cooperative control

Abstract

The application provides a heat pump non-stop defrosting control method and system based on double-evaporator cooperative control, which comprises the following steps: collecting the refrigerant inlet and outlet temperatures of two groups of fin heat exchangers in real time, constructing a temperature difference response change rate index, and identifying the defrosting side and the heating side; dynamically configuring an electronic expansion valve, a fan and an electromagnetic valve, so that the defrosting side enters a static defrosting mode, and the heating side continuously supplies heat; cooperatively adjusting the compressor frequency increase and the four-way valve switching, and performing a small-flow pre-balancing before switching to suppress pressure impact; after the defrosting is completed, the defrosting end is judged based on the thermal response state and the heat change trend, the defrosting side is reset and re-input for heating. The application realizes uninterrupted user-side heating during the defrosting process, significantly reduces water temperature fluctuation and energy consumption, and improves the operation stability and energy efficiency of the heat pump in a low-temperature and high-humidity environment.

Description

Technical Field

[0001] This invention belongs to the field of heat pumps, and particularly relates to a method and system for controlling defrosting of heat pumps without stopping based on dual evaporator coordinated control. Background Technology

[0002] With the widespread application of air source heat pumps in cold and humid regions, the problem of frequent frosting in low-temperature and high-humidity environments has become increasingly serious. Under winter heating conditions, finned evaporators are prone to frost formation due to their surface temperature being below the air dew point, leading to a sharp decline in heat exchange efficiency, reduced heating capacity, increased compressor load, and even system failure. Currently, most mainstream heat pump products use a four-way valve reverse-cycle defrosting method, which temporarily heats the evaporator as a condenser by changing the refrigerant flow direction. This method causes the refrigerant originally intended for heating the water side to flow back to the outdoor side during defrosting, resulting in a significant drop in the user's outlet water temperature and forced interruption of system heating. Simultaneously, to compensate for the heat loss from reverse-cycle defrosting, the compressor often needs to operate at a higher frequency for a short period, causing a sudden increase in power consumption and mechanical stress, significantly affecting unit reliability. Although some improved systems have introduced a dual-evaporator structure for alternating operation to achieve uninterrupted defrosting, existing designs generally use fixed timing logic, which cannot adaptively adjust according to the actual state of frost growth, resulting in problems such as delayed defrosting judgment, large switching shocks, and unreasonable refrigerant flow distribution. Furthermore, the lack of a unified dynamic coordination control mechanism between the four-way valve, electronic expansion valve, and compressor often leads to energy imbalances or insufficient defrosting efficiency during refrigerant path switching, resulting in significant water-side temperature fluctuations and low system energy efficiency. Especially in extreme northern conditions, the system needs to simultaneously maintain high-load heating and efficient defrosting at low temperatures, placing higher demands on control algorithms and energy scheduling. Existing solutions often fail to achieve synchronized adjustment of refrigerant flow, heat distribution, and compressor frequency, leading to a disconnect between heat compensation and defrosting control. Summary of the Invention

[0003] The purpose of this invention is to design a heat pump defrosting control method and system based on dual evaporator coordinated control, which can achieve dynamic heat distribution, coordinated switching of compressor and circuit under non-stop conditions, and intelligent reset.

[0004] To achieve the above objectives, a first aspect of the present invention provides a heat pump defrosting control method based on dual evaporator coordinated control, the method comprising:

[0005] Based on the refrigerant inlet and outlet temperature data of the two finned heat exchangers, a temperature difference response change rate index is constructed to identify the finned heat exchanger with a more severe frosting trend as the defrosting side and the other finned heat exchanger as the heating side.

[0006] Based on the identification results, the opening degree of the electronic expansion valve, the start / stop status of the fan and the solenoid valve passage of the defrosting side and the heating side are configured respectively, so that the defrosting side receives high-temperature refrigerant and shuts down the fan to form a static defrosting environment, while the heating side maintains normal evaporation operation and continuously supplies heat to the user side.

[0007] After the refrigerant path is configured, the compressor frequency and four-way valve switching operation are coordinated and adjusted. During the compressor frequency increase process, suppression and inertia compensation terms are introduced to smooth pressure fluctuations. A small flow pre-balancing operation is performed before the four-way valve switches to reduce the risk of liquid slugging.

[0008] During the coordinated operation phase, based on the thermal response status of the side requiring defrosting and the heating side, as well as the trend of the target defrosting heat change, it is determined whether defrosting is completed. If completed, the fan on the side requiring defrosting is restarted, the electronic expansion valve is restored to superheat control, and the four-way valve is driven to reset after the system pressure stabilizes, so that the side requiring defrosting is put back into heating operation as the heating side, thereby realizing closed-loop control of defrosting without stopping the machine.

[0009] Furthermore, the temperature difference response change rate index is obtained by calculating the ratio of the current refrigerant inlet and outlet temperature difference to the average temperature difference within the historical window, and the identification results of the defrosting side and the heating side are confirmed only when the preset threshold conditions are consistently met within three consecutive control cycles.

[0010] Furthermore, the electronic expansion valve on the defrosting side is set to fully open, the fan on the defrosting side is turned off, and the solenoid valve is controlled to connect to the defrosting liquid supply path; the opening of the electronic expansion valve on the heating side is dynamically adjusted according to the thermal response state of the heating side, and the fan on the heating side remains in normal operation to maintain continuous heating to the user side.

[0011] Furthermore, the adjustment of the compressor frequency is not only based on the target defrosting heat demand, but also combined with the operating status of the heating side electronic expansion valve for suppression, and inertial compensation is introduced considering the target heat change rate to achieve synchronization between the frequency increase process and heat switching.

[0012] Furthermore, the switching of the four-way valve is triggered after the compressor frequency reaches 90% of the target value and remains stable for a predetermined time. Before switching, a small bypass path is established by briefly increasing the opening of the electronic expansion valve on the heating side to pre-balance the refrigerant pressure.

[0013] Furthermore, the determination of defrosting completion is based on the similarity of the thermal response rates of the side requiring defrosting and the heating side, as well as the changing trend of the target defrosting heat over time. When the combined indicators of both meet the set threshold three times consecutively, defrosting is determined to be complete.

[0014] Furthermore, the defrosting side fan starts at an initial speed lower than the rated wind speed during the reset phase, and linearly accelerates to the normal wind speed within a predetermined time to avoid heat exchange shock caused by sudden air intrusion.

[0015] Furthermore, when the defrosting-side electronic expansion valve is reset, it switches from the fully open state to the fixed superheat control mode, with the target superheat corresponding to the intermediate opening range. The heating-side electronic expansion valve maintains its original opening to reduce refrigerant disturbance.

[0016] Furthermore, before resetting and switching the four-way valve, the high and low pressure difference of the system is checked again. If the pressure difference exceeds the safety limit, the switching is delayed or the compressor frequency is temporarily reduced. The switching is then performed after the pressure stabilizes.

[0017] A second aspect of the invention provides a heat pump non-stop defrosting control system based on dual evaporator coordinated control, the system comprising:

[0018] The frost recognition module is used to construct a temperature difference response change rate index based on the refrigerant inlet and outlet temperature data of the two sets of finned heat exchangers, and to identify in real time the finned heat exchanger with a more severe frost trend as the side that needs to be defrosted, and the other finned heat exchanger as the heating side.

[0019] The path configuration module is used to dynamically configure the opening degree of the electronic expansion valve, the start / stop state of the fan and the solenoid valve passage of each side according to the identification results of the side to be defrosted and the side to be heated, so that the side to be defrosted receives high temperature refrigerant and shuts down the fan to form a static defrosting environment, while the side to be heated maintains normal evaporation operation and continuously supplies heat to the user side.

[0020] The collaborative execution module is used to coordinate the adjustment of compressor frequency and four-way valve switching operation after the refrigerant path configuration is completed. During the compressor frequency increase process, suppression and inertia compensation terms are introduced to smooth pressure fluctuations, and a small flow pre-balancing operation is performed before the four-way valve switching to reduce the risk of liquid slugging.

[0021] The reset judgment module is used to determine whether defrosting is completed during the collaborative operation phase based on the thermal response status of the side requiring defrosting and the heating side and the trend of the target defrosting heat change. After determining that defrosting is completed, it controls the fan on the side requiring defrosting to restart, the electronic expansion valve on the side requiring defrosting to resume superheat control, and drives the four-way valve to reset after the system pressure stabilizes, so that the side requiring defrosting can be put back into heating operation as the heating side.

[0022] The beneficial technical effects of the present invention are at least as follows:

[0023] To address the aforementioned issues, this invention provides a heat pump defrosting control method and system based on dual evaporator collaborative control. A dynamic thermal response model is constructed using the refrigerant inlet and outlet temperatures of the two heat exchangers to identify heat exchangers with severe frosting tendencies in real time. Based on the judgment results, the control targets of two sets of electronic expansion valves, fans, and solenoid valves are dynamically configured to establish an adjustable heat distribution path. The system utilizes a target heat function with an introduced heat attenuation term and a residual compensation model to accurately calculate the refrigerant flow ratio between the defrosting and heating sides, realizing an asymmetric collaborative heating mechanism between the two evaporators. Subsequently, the controller jointly adjusts the compressor frequency ramp-up process based on heat load and valve state deviation, introducing a regularized control structure with suppression and inertia compensation terms to synchronize the frequency ramp-up process with heat switching, avoiding pressure fluctuations caused by sudden frequency increases. Before the four-way valve switches, short-term low-flow pre-balancing is used to buffer the refrigerant path, effectively reducing the risk of liquid slugging and energy shock. During the defrosting completion phase, the system constructs a comprehensive judgment index using thermal response ratio and energy difference to automatically identify the timing of defrosting completion. It then performs a reset verification based on temperature and energy balance functions, ensuring the defrosting-side finned heat exchanger smoothly resumes heating operation. Compared to traditional solutions, the innovation of this invention lies in achieving real-time coupled control of the compressor, expansion valve, and four-way valve through a multi-variable collaborative algorithm. This establishes a dual closed-loop relationship between energy flow and control logic, enabling the heat pump system to achieve a dynamic balance between intelligent defrosting and continuous heating without shutting down. This significantly reduces energy consumption and temperature fluctuations, and substantially improves the system's stability and energy efficiency in low-temperature environments. Attached Figure Description

[0024] The present invention will be further described with reference to the accompanying drawings, but the embodiments in the drawings do not constitute any limitation on the present invention. For those skilled in the art, other drawings can be obtained based on the following drawings without creative effort.

[0025] Figure 1 This is a flowchart of the heat pump defrosting control method based on dual evaporator coordinated control according to the present invention.

[0026] Figure 2 This is a framework diagram of the heat pump non-stop defrosting control system based on dual evaporator coordinated control of the present invention. Detailed Implementation

[0027] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0028] In one or more embodiments, such as Figure 1As shown, a heat pump defrosting control method based on dual evaporator coordinated control is disclosed, the method comprising the following:

[0029] S1: Based on the refrigerant inlet and outlet temperature data of the two finned heat exchangers, a temperature difference response change rate index is constructed to identify the finned heat exchanger with a more severe frosting trend as the defrosting side and the other finned heat exchanger as the heating side in real time.

[0030] Specifically, the goal of this step is to determine in real time which group of finned heat exchangers (A or B) has shown a tendency to frost while the system is in normal heating operation, thus providing an operational target for subsequent defrosting control. This determination does not rely on an additional frost image recognition module, nor does it use data sources with high uncertainty such as ambient temperature and humidity. Instead, it is based on data collected by the refrigerant inlet and outlet temperature sensors already deployed in the system, and identifies the finned heat exchanger by constructing a temperature difference response change rate index. The core idea of ​​this method is that frost causes a decrease in the heat exchange efficiency of the finned heat exchanger, thereby changing the trend of the temperature difference between the refrigerant inlet and outlet. By observing this trend change, the system can identify the heat exchanger with the most significant performance degradation in real time without stopping operation.

[0031] The input for this step comes from temperature sensor data on both sides of the heat exchanger. In the system, each finned heat exchanger (A and B) is equipped with a type K thermocouple sensor at both the refrigerant inlet and outlet. The thermocouple heads are tightly attached to the outer wall of the copper tube and fixed with thermally conductive adhesive to reduce thermal hysteresis. The sensors are connected to a 12-bit ADC module on the main control board, and a stable temperature sequence is formed after a 0.5-second sliding filter. Each sensor has a sampling period of 2 seconds, and the data format is 32-bit floating-point. Specific signals include... and (Indicates the refrigerant inlet and outlet temperatures of heat exchanger A) and and (This indicates the refrigerant inlet and outlet temperatures of heat exchanger B).

[0032] In a typical northern winter environment of low temperature and high humidity, assuming the system has been running for 1200 seconds, the following data segment was collected: , , , This indicates that the refrigerant in heat exchanger A has a stronger heat exchange capacity during this period, while the performance of heat exchanger B may begin to decline due to frost formation.

[0033] The system first constructs the instantaneous thermal response rate of change index for each group of heat exchangers, calculated as follows:

[0034] ;

[0035] in Indicates the heat exchanger number. The fixed time window length is set to 120 seconds. This represents the average temperature difference between the refrigerant inlet and outlet of the heat exchanger over the past 120 seconds, calculated by sliding a window of historical data recorded in the system cache. All temperature data are preprocessed by a filtering module, using a first-order moving average method to reduce fluctuations.

[0036] Taking a real-world scenario as an example: if the average temperature difference of heat exchanger A over the past 2 minutes is 3.4, and the currently measured temperature difference is 3.6, then its response will be... If the average temperature difference for group B is 3.2, and it currently drops to 2.6, then its response will be... Obviously, the performance of the heat exchanger in group B deteriorates faster, possibly due to frost affecting the air-side heat exchange capacity.

[0037] The system determines the objects that need defrosting using the following structure:

[0038] ;

[0039] in A response difference threshold, typically between 0.003 and 0.01, is set empirically to filter out false alarms caused by sensor errors or short-cycle jitter. The system only confirms the defrosting request as valid if the results are consistent across three consecutive control cycles (6 seconds), thus improving reliability. The output of this step consists of two variables: This indicates the number of the finned heat exchanger that is currently determined to require defrosting; the value can be either A or B. This indicates the heat exchanger number that will continue to perform the evaporation task, belonging to the other group of two. This output will be directly used as an input in subsequent control logic to determine the configuration of the expansion valve opening, solenoid valve path, and fan start / stop status.

[0040] S2: Based on the identification results, configure the opening degree of the electronic expansion valve, the start / stop status of the fan and the solenoid valve passage of the side that needs to be defrosted and the heating side respectively, so that the side that needs to be defrosted receives high-temperature refrigerant and shuts down the fan to form a static defrosting environment, while the heating side maintains normal evaporation operation and continuously supplies heat to the user side.

[0041] Specifically, this step, based on the heat exchanger role identification results output from the previous stage, dynamically configures the target operating states of each control component to ensure the orderly distribution of refrigerant flow paths in the heat pump system without shutting down. Its main task is to... (Heat exchangers requiring defrosting) and The control states of the electronic expansion valve, fan, and solenoid valves corresponding to the heat exchanger (continuously evaporating for heating) are rationally matched to establish the actual control path for the heat zone. To improve system energy efficiency and reduce water-side temperature fluctuations, this step proposes a dynamic flow path adjustment mechanism based on heat offset compensation. This takes into account the compressor's total heat output capacity. The heat transfer exhibits nonlinear growth at different frequencies, and the heat exchanger's ability to absorb heat from the refrigerant decreases significantly under frosting conditions. If the refrigerant distribution is directly set based on the heat load ratio, insufficient heat flow on the evaporator side will result. Therefore, this step designs an objective function for the heat required for defrosting, incorporating a heat attenuation term. ,as follows:

[0042] ;

[0043] in, It is the heat distribution coefficient, with an initial value set at 0.38; It is the thermal decay adjustment factor, with a value ranging from 0.5 to 1; The thermal response rate of the heat exchanger requiring defrosting, calculated in step one; This is the system's empirical baseline thermal response rate constant. The formula incorporates thermal response decay into the heat distribution model: the worse the heat exchanger performance, the lower the thermal response, and the more refrigerant heat is allocated, thus prioritizing compensation for areas with severe frosting. This design breaks through the traditional constant heat ratio control logic, making heat distribution more closely aligned with dynamic operating conditions. It is an asymmetric heat load control strategy adapted to a dual-heat exchanger collaborative structure.

[0044] Once the heat target is determined, the system adjusts the current compressor operating frequency accordingly. Based on the current directional state of the four-way valve, the target opening degree of the electronic expansion valve for each heat exchanger group can be deduced. To prevent refrigerant mismatch between the two heat exchangers due to expansion valve hysteresis or response differences, this step proposes a residual compensation expansion valve opening adjustment model:

[0045] ;

[0046] in, This is the thermal response residual correction factor, with a value between 0.1 and 0.2. This is the current thermal response rate of the evaporator, consistent with the variable of the same structure in step one; This represents the maximum opening percentage of the expansion valve (typically 100%). This structure incorporates fluctuations in the evaporator-side heat exchange capacity into the refrigerant control chain, enabling fine-tuning and coordination between the two pathways and providing strong adaptability to thermal balance. Unlike traditional fixed-ratio opening settings, this scheme considers not only the system's heat distribution results but also the dynamic changes in the evaporator's operating status.

[0047] During the control execution process, the system also needs to complete the following operations:

[0048] Will The corresponding electronic expansion valve is forced to be set to the fully open mode, specifically by controlling the drive pulse stepper to enter the maximum opening position;

[0049] Stop the operation of its fan, and the main control board outputs a low level to the fan relay contact to create a closed high-temperature zone with no airflow on the air side, which accelerates the softening of the frost layer.

[0050] Control solenoid valve Switch to the "defrost supply path". This solenoid valve is normally closed and is opened by a pulse signal output from the control board to drive the coil to be energized.

[0051] The corresponding fan maintains normal operation, and the standard wind speed is maintained by the PWM control signal;

[0052] Its electronic expansion valve calculates the target value using an opening model and then loads it into the corresponding register of the control chip to complete real-time adjustment.

[0053] The output of this step is two quantities: one is... The first is the target refrigerant heat required for defrosting, which guides subsequent compressor frequency control and four-way valve timing decisions; the second is... This refers to the target opening percentage of the evaporator-side expansion valve, which serves as the direct execution command for adjusting refrigerant distribution. By introducing a thermal response residual compensation mechanism and a dynamic thermal attenuation factor into the control objective, this step proposes a practically operable refrigerant path configuration method. This not only improves the system's adaptability to asymmetric heat transfer conditions but also endows the system with independent response and complementary control capabilities at the structural level. It is a key control module supporting the closed-loop operation of "non-stop defrosting." This control structure is highly adaptable to dual-heat exchanger configurations and can be implemented in software logic without requiring new hardware investment.

[0054] S3: After the refrigerant path configuration is completed, the compressor frequency and four-way valve switching operation are coordinated and adjusted. During the compressor frequency increase process, suppression and inertia compensation terms are introduced to smooth pressure fluctuations. A small flow pre-balancing operation is performed before the four-way valve switching to reduce the risk of liquid slugging.

[0055] Specifically, this step, building upon the refrigerant heat distribution and target control status configuration of each component completed in step two, further realizes the dynamic energy scheduling and path switching control of the system core. Its task is to coordinate the compressor frequency increase and the four-way valve reversal, enabling the system to smoothly transition from a single heating mode to a "dual-loop coordinated operation mode" without shutting down, i.e., one set of finned heat exchangers performs defrosting operations while the other set continues to provide heat.

[0056] To ensure continuous water-side heating and controlled refrigerant pressure fluctuations during system switching, this step proposes a "coupled gain-canonical balance" compressor control strategy. The core idea of ​​this strategy is to adjust the compressor frequency solely based on the target defrosting heat. Furthermore, a suppression term based on the offset of the evaporator-side expansion valve and an inertial energy balance term are introduced to counteract the transient thermal shock effect caused by a sudden increase in frequency. The formula for calculating the compressor target frequency is as follows:

[0057] ;

[0058] in, This is the minimum operating frequency limit; This is the heat load response coefficient, used to establish a positive relationship between heat demand and frequency increase; This is a refrigerant regulation suppression factor, used when the opening of the evaporator-side expansion valve deviates from the normal operating point. Suppressing excessively rapid frequency increase; The inertial compensation weight is used to describe the rate of change of the target defrosting heat. Buffering the impact of frequency changes. The second term in this formula is equivalent to a "negative regularization term," which limits the nonlinear response of the compressor through the squared difference, thereby balancing the pressure distribution between the two refrigerant paths for heating and defrosting, and achieving feedforward suppression of the system's transient thermodynamic behavior. This design directly couples energy distribution dynamics with valve control deviations, providing the system with a physical-level self-balancing constraint mechanism.

[0059] During the control execution process, the master controller first calculates the result based on this formula. The system then sends a frequency ramp command to the compressor inverter drive module. The inverter adjusts the pulse width modulation (PWM) carrier output based on the received target frequency signal to achieve a continuous increase in compressor speed. Simultaneously, an internal slow-up timer is activated, dividing the frequency ramp process into multiple linear intervals. For example, it gradually increases from the base frequency to the target frequency within 4 seconds, controlling the speed increase curve according to the time ratio to achieve a smooth transition in heat output.

[0060] To ensure the safety and timing coordination of heat transfer path switching, this step designs a four-way valve "delayed reversing - pressure balance" control logic. Specifically, the system detects that the compressor frequency reaches... The four-way valve switching signal is triggered only after the pressure reaches 90% and remains stable for 1.5 seconds. The four-way valve drive module uses a stepper electromagnetic control method. During the switching process, the main controller detects the pressure difference output by the high and low pressure sensors of the refrigerant. Determine whether the system meets the safe commutation conditions. If the conditions are met, the reversal is executed immediately; otherwise, a 0.5-second delay is applied for re-detection until the reversal is complete.

[0061] Furthermore, to further optimize the system's pressure balance and refrigerant flow stability, this step proposes implementing a "pre-balancing small-path bypass" mechanism before switching: the system adjusts the opening of the evaporator-side expansion valve. Temporarily raised to This process, lasting 0.3 seconds, allows some refrigerant to flow into the defrosting circuit first, establishing an initial micro-flow channel. This prevents the refrigerant from forming cavities or impinging flows during the reversing action. This micro-bypass strategy effectively reduces the risk of liquid slugging during four-way valve reversal and is a shock-proof measure specifically designed for dual-evaporator structures.

[0062] After the four-way valve completes its operation, the system automatically restores the expansion valve to the target opening and enters the "coordinated operation phase": at this time... The side receives the inflow of high-temperature refrigerant, and the fan is turned off to create a static thermal defrosting environment; The system continues evaporation and heat exchange on the side, while the fan maintains its rated speed, ensuring stable refrigerant circulation and heating. The system monitors the compressor input current and outlet air temperature in real time. If there are no abnormal fluctuations within a preset stabilization period (approximately 6 seconds), the control module locks the current operating state and records the system status as "cooperative operation startup completed".

[0063] The output variable for this step is (Compressor target frequency) and (Four-way valve switching complete signal). Among them... It will be used for subsequent steps such as determining the thermal balance and detecting the completion of defrosting. This serves as a system state synchronization signal, triggering the next round of heat exchanger thermal response calculation.

[0064] S4: During the coordinated operation phase, based on the thermal response status of the side requiring defrosting and the heating side and the trend of the target defrosting heat change, it is determined whether defrosting is completed; if completed, the fan on the side requiring defrosting is restarted, the electronic expansion valve is restored to superheat control, and the four-way valve is driven to reset after the system pressure stabilizes, so that the side requiring defrosting is put back into heating operation as the heating side, realizing closed-loop control of defrosting without stopping the machine;

[0065] Specifically, this step involves monitoring the thermodynamic state changes of the heat exchanger on the defrosting side after the system completes compressor frequency increase and four-way valve switching. This determines whether the frost layer has been completely removed. Once the conditions are met, the control system executes a series of reset operations, re-integrating the heat exchanger on the defrosting side into the heating loop, thus completing a closed-loop switch for a full dual-heat exchanger coordinated defrosting process. This step not only accurately determines whether defrosting is complete but also ensures a smooth transition for the entire system, with no drastic fluctuations in compressor operation and uninterrupted water-side heat supply.

[0066] The input for this step includes the two output variables from step three: (Current target operating frequency of the compressor) and (A Boolean signal indicating whether the four-way valve swivel is complete). Used to determine whether the system is in a stable high thermal load state, serving as a trigger condition for whether to enter the judgment phase; This is used to confirm that the four-way valve has completed its operation and that the system is in a coordinated operating state, ensuring that the refrigerant path is stable at the time of judgment and will not be affected by transient path switching.

[0067] During the judgment process, the system collects the refrigerant inlet and outlet temperatures of the heat exchanger on the side requiring defrosting through two temperature sensors, which are respectively and The sensor is a type K thermocouple, directly attached to the outer wall of the copper tube and encapsulated in a heat-shrink tubing to reduce interference. The sampling period is 2 seconds. It is connected to the controller's ADC module, and after digital filtering, the data is sent to the judgment module. Simultaneously, a comparison sensor is obtained from the evaporation side. and The signal is used to calculate the thermal response rates on both sides. and The definitions and calculation methods for these two quantities are consistent with those in step one.

[0068] The system further combines the output from step two. Compared with the current compressor frequency The corresponding theoretical heat output (Obtained from the compressor operating characteristic table), construct a comprehensive index function to determine the completion of defrosting. :

[0069] ;

[0070] in, It is a weighting factor for the rate of energy change, with a value ranging from 0.3 to 0.5; This is the time window for calculating the energy difference, set to 120 seconds. The first term of this function reflects the similarity in thermodynamic states between the defrosting side and the evaporation side, and the second term reflects the changing trend of the heat required for defrosting on the defrosting side over time. If When the value stabilizes in both aspects, it indicates that the frost layer has been largely removed, and the defrosting process can be considered complete. Taking a certain operation as an example, when... , , W, W, then If a threshold is to be determined... Setting the value to 0.9 allows the system to initially determine that defrosting is nearing completion. The system performs a judgment every 2 seconds, and confirms that defrosting is complete after three consecutive successful judgments.

[0071] Once the judgment result is confirmed, the system enters the reset process, first controlling... The corresponding fan restarts. The controller sends a PWM pulse to the fan drive module, setting the initial speed to 70% of the rated wind speed. After 5 seconds, it linearly accelerates to the normal level to prevent sudden temperature fluctuations caused by cold air entering the heat exchanger channel. This fan restart process simultaneously brings the heat exchanger surface back from the "static defrost thermal buffer zone" to the forced convection heat exchange state, helping it quickly return to heating conditions.

[0072] Simultaneously, the electronic expansion valve controller adjusts the valve on this side from the "fully open" state to a fixed superheat control mode, with the target set as follows: This corresponds to the midpoint of the opening range, typically 35% to 50%. The evaporator-side expansion valve maintains the value calculated in the previous cycle. The temperature remains unchanged to reduce refrigerant disturbance during heat exchanger switching.

[0073] The four-way valve begins switching 6 seconds after the fan restarts and valve settings are completed, at which point the controller sends a switching signal to the four-way valve drive module again. To ensure controllable refrigerant system pressure fluctuations during the switching process, the system again checks the high and low pressure difference before switching. If the pressure exceeds the set upper limit (e.g., 0.3 MPa), the commutation will be delayed or the frequency will be slightly reduced to allow the pressure drop to stabilize before switching. The compressor continues to run during the commutation process, but the frequency will be linearly reduced to the set upper limit within 3 seconds. After switching, the flow rate is slowly restored to ensure a smooth transition between system pressure and flow.

[0074] After all switching operations are completed, the system calculates the thermal balance verification value after reset. :

[0075] ;

[0076] in, It is the target calorie ratio set in step two. This is the temperature-to-balance coefficient, typically taken as 0.2. This function is used to determine whether the current system heat configuration has returned to the design state, and also examines the relative deviation of the outlet temperatures of the two heat exchangers to assess whether the flow rate and heat load are balanced. If... If the value is less than 0.05, the system determines that the current round of collaborative defrosting process has been successfully reset and prepares to re-enter the next round of thermal response judgment.

[0077] The output of this step is two quantities: This is used to determine the defrosting completion status and directly control whether to perform a system reset. This is used to determine whether the system's thermal state has successfully returned to equilibrium, and is a starting condition for the system to re-enter the normal heating cycle. All data acquisition is based on data from the pre-heater thermocouple sensor and the compressor controller's internal data, requiring no additional hardware support. The control logic is fully embedded in the existing main control program and can be executed periodically via timed interrupts to ensure stability and real-time performance.

[0078] In one or more embodiments, such as Figure 2 As shown, a heat pump non-stop defrosting control system based on dual evaporator coordinated control is disclosed. The system includes:

[0079] The frost recognition module is used to construct a temperature difference response change rate index based on the refrigerant inlet and outlet temperature data of the two sets of finned heat exchangers, and to identify in real time the finned heat exchanger with a more severe frost trend as the side that needs to be defrosted, and the other finned heat exchanger as the heating side.

[0080] The path configuration module is used to dynamically configure the opening degree of the electronic expansion valve, the start / stop state of the fan and the solenoid valve passage of each side according to the identification results of the side to be defrosted and the side to be heated, so that the side to be defrosted receives high temperature refrigerant and shuts down the fan to form a static defrosting environment, while the side to be heated maintains normal evaporation operation and continuously supplies heat to the user side.

[0081] The collaborative execution module is used to coordinate the adjustment of compressor frequency and four-way valve switching operation after the refrigerant path configuration is completed. During the compressor frequency increase process, suppression and inertia compensation terms are introduced to smooth pressure fluctuations, and a small flow pre-balancing operation is performed before the four-way valve switching to reduce the risk of liquid slugging.

[0082] The reset judgment module is used to determine whether defrosting is completed during the collaborative operation phase based on the thermal response status of the side requiring defrosting and the heating side and the trend of the target defrosting heat change. After determining that defrosting is completed, it controls the fan on the side requiring defrosting to restart, the electronic expansion valve on the side requiring defrosting to resume superheat control, and drives the four-way valve to reset after the system pressure stabilizes, so that the side requiring defrosting can be put back into heating operation as the heating side.

[0083] It is worth noting that the specific workflow of the heat pump non-stop defrosting control system based on dual evaporator collaborative control provided in this embodiment of the invention is the same as that of the heat pump non-stop defrosting control method based on dual evaporator collaborative control described in the above embodiment, and will not be repeated here.

[0084] This invention also provides a heat pump non-stop defrosting control device based on dual evaporator collaborative control, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the steps described in the above embodiments of the heat pump non-stop defrosting control method based on dual evaporator collaborative control, for example... Figure 1 The steps S1 to S4 described above; or, when the processor executes the computer program, it implements the functions of each module in the above system embodiments.

[0085] For example, the computer program may be divided into one or more modules, which are stored in the memory and executed by the processor to complete the present invention. The one or more modules may be a series of computer program instruction segments capable of performing specific functions, which describe the execution process of the computer program in the heat pump non-stop defrosting control device based on dual evaporator coordinated control.

[0086] The heat pump defrosting control device based on dual evaporator collaborative control can be a computing device such as a desktop computer, laptop, handheld computer, or cloud server. This device may include, but is not limited to, a processor and memory. Those skilled in the art will understand that the device may also include input / output devices, network access devices, and buses.

[0087] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASACs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor. This processor is the control center of the heat pump non-stop defrosting control equipment based on dual evaporator collaborative control, connecting all parts of the equipment via various interfaces and lines.

[0088] The memory can be used to store the computer program and / or modules. The processor implements various functions of the heat pump non-stop defrosting control device based on dual evaporator coordinated control by running or executing the computer program and / or modules stored in the memory and calling the data stored in the memory. The memory may mainly include a program storage area and a data storage area. The program storage area may store the operating system, at least one application program required for a function, etc.; the data storage area may store data created according to the operation of the air conditioner controller, etc. In addition, the memory may include high-speed random access memory, and may also include non-volatile memory, such as hard disk, memory, plug-in hard disk, smart media card (SMC), secure digital card (SD), flash card, at least one disk storage device, flash memory device, or other volatile solid-state storage device.

[0089] The module integrated into the heat pump non-stop defrosting control device based on dual evaporator coordinated control, if implemented as a software functional unit and sold or used as an independent product, can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc.

[0090] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc.

[0091] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A heat pump non-stop defrosting control method based on dual evaporator cooperative control, characterized in that, The method comprises: Based on the refrigerant inlet and outlet temperature data of the two groups of finned heat exchangers, a temperature difference response change rate index is constructed to identify the finned heat exchanger with a more serious frosting trend as the defrosting side and the other finned heat exchanger as the heating side; the temperature difference response change rate index is obtained by calculating the ratio of the current refrigerant inlet and outlet temperature difference to the average temperature difference in the historical window, and the identification result of the defrosting side and the heating side is confirmed only when the preset threshold condition is consistently met in three consecutive control cycles; According to the identification result, the opening degree of the electronic expansion valve, the fan start-stop state and the electromagnetic valve passage corresponding to the defrosting side and the heating side are configured, so that the defrosting side receives high-temperature refrigerant and the fan is closed to form a static defrosting environment, and the heating side maintains normal evaporation operation and continuously supplies heat to the user side; After the refrigerant path is configured, the compressor frequency and the four-way valve switching operation are adjusted, the suppression term and the inertia compensation term are introduced in the compressor frequency increasing process to suppress pressure fluctuation, and the small flow pre-balancing operation is performed before the four-way valve commutation to reduce the risk of liquid hammer; In the cooperative operation stage, whether the defrosting is completed is judged based on the thermal response state of the defrosting side and the heating side and the change trend of the target defrosting heat; if it is completed, the fan of the defrosting side is restarted, the electronic expansion valve of the defrosting side resumes the superheat control, and after the system pressure is stabilized, the four-way valve is reset, so that the defrosting side is re-used as the heating side to put into heating operation, realizing the non-stop defrosting closed-loop control.

2. The method according to claim 1, wherein, The electronic expansion valve of the defrosting side is set to full open state, the fan of the defrosting side is closed, and the electromagnetic valve is controlled to be on to the defrosting liquid supply path; the opening degree of the electronic expansion valve of the heating side is dynamically adjusted according to the thermal response state of the heating side, and the fan of the heating side remains normal operation to maintain continuous heat supply to the user side.

3. The method according to claim 1, wherein, The adjustment of the compressor frequency not only depends on the target defrosting heat demand, but also combines the operation state of the heating side electronic expansion valve for suppression, and considers the target heat change rate to introduce inertia compensation, so as to realize the synchronization of frequency increasing process and heat switching.

4. The method according to claim 1, wherein, The switching of the four-way valve is triggered after the compressor frequency reaches 90% of the target value and is stably maintained for a predetermined time, and a small amount of bypass path is established by temporarily increasing the opening degree of the electronic expansion valve of the heating side before switching to pre-balance the refrigerant pressure.

5. The method according to claim 1, wherein, The judgment of whether the defrosting is completed is based on the closeness of the thermal response rates of the defrosting side and the heating side and the change trend of the target defrosting heat in the time dimension, and when the comprehensive indexes of the two satisfy the set threshold value for three times in a row, it is determined that the defrosting is completed.

6. The method according to claim 1, wherein, The fan of the defrosting side starts at an initial speed lower than the rated wind speed in the reset stage, and linearly accelerates to the normal wind speed within a predetermined time, so as to avoid the heat exchange shock caused by air surge.

7. The method according to claim 1, wherein, The electronic expansion valve of the defrosting side is switched from full open state to fixed superheat control mode in the reset stage, the target superheat corresponds to the intermediate opening degree range, and the electronic expansion valve of the heating side maintains the original opening degree unchanged to reduce the refrigerant disturbance.

8. The method of claim 1, wherein the method further comprises: Before the four-way valve reset switching, the system high and low pressure difference is detected again, if the pressure difference exceeds the upper limit of safety, the switching is delayed or the compressor frequency is temporarily reduced, and after the pressure is stable, the switching is executed.

9. A heat pump non-stop defrosting control system based on dual evaporator cooperative control, characterized in that, The system comprises: A frost identification module is configured to construct a temperature difference response change rate index based on the refrigerant inlet and outlet temperature data of the two groups of finned heat exchangers, to identify in real time the finned heat exchanger with a more serious frost trend as the defrosting side and the other finned heat exchanger as the heating side; the temperature difference response change rate index is obtained by calculating the ratio of the current refrigerant inlet and outlet temperature difference to the average temperature difference in the historical window, and the identification results of the defrosting side and the heating side are confirmed only when the preset threshold condition is met consistently for three consecutive control periods; A path configuration module is configured to dynamically configure the respective electronic expansion valve opening degree, fan start-stop state and electromagnetic valve passage according to the identification results of the defrosting side and the heating side, so that the defrosting side receives high-temperature refrigerant and closes the fan to form a static defrosting environment, and the heating side maintains normal evaporation operation and continuously supplies heat to the user side; A cooperative execution module is configured to coordinate the adjustment of the compressor frequency and the four-way valve switching operation after the refrigerant path configuration is completed, to introduce a suppression term and an inertia compensation term in the compressor frequency increasing process to smooth the pressure fluctuation, and to perform a small flow pre-balancing operation before the four-way valve switching to reduce the risk of liquid hammer; A reset judgment module is configured to judge whether the defrosting is completed based on the thermal response state of the defrosting side and the heating side and the target defrosting heat change trend during the cooperative operation stage, and after determining that the defrosting is completed, to control the fan of the defrosting side to restart, the electronic expansion valve of the defrosting side to restore the superheat control, and to drive the four-way valve to reset after the system pressure is stable, so that the defrosting side re-enters the heating operation as the heating side.

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