A method and device for collaborative control of refrigerant distribution and air supplement defrosting of an ejection hyperbolic system

Abstract

The application discloses a method and device for collaborative control and air supplement defrosting of a refrigerant distribution of an air injection enthalpy increasing system, belonging to the technical field of air source heat pump control, and the unit is equipped with a main road EEVH, an economizer EEVSC and a plurality of temperature and pressure sensors. During heating, the initial opening degrees of the two valves are calculated first, and the basic adjustment amount is obtained through PID operation. According to the superheat degree of the economizer, the exhaust temperature and the temperature rise trend, the opening degree compensation is superimposed for different working conditions. The target superheat degree of the economizer is corrected in high-temperature working conditions. When the superheat degree is too low, the EEVSC compensation is shielded to realize the anti-liquid impact interlocking. The defrosting is divided into four stages, and the indoor unit electronic expansion valve is differentially controlled. In the second stage of defrosting, the EEVSC air supplement is started to meet the multi-dimensional conditions. There is no PI operation, the valve is quickly adjusted at an exhaust superheat degree of 25 DEG C, and the air supplement is closed when the exit condition is reached. The application realizes precise refrigerant distribution of double valves, suppresses exhaust over-temperature, shortens the defrosting time, and takes into account the heating energy efficiency, compressor reliability and indoor comfort.

Description

Technical Field

[0001] This invention relates to the fields of air source heat pump and central air conditioning multi-split system control technology, and is particularly applicable to the refrigerant distribution coordination control and gas injection defrosting optimization control of jet enthalpy-increasing heat pump systems operating under ultra-low temperature conditions of -15℃ to -30℃. Background Technology

[0002] Jet enthalpy enhancement technology is the core technology for expanding the low-temperature heating capacity of air source heat pumps. It can extend the minimum ambient temperature for stable heating of the unit from the conventional -15℃ to -30℃, greatly improving the heating capacity and energy efficiency ratio under low-temperature conditions. It is now widely used in commercial and residential air source heat pumps and variable frequency multi-split air conditioning products in low-temperature areas in the north.

[0003] The existing jet enthalpy enhancement system mainly includes two refrigerant flow paths: the main heating flow path and the jet enthalpy enhancement flow path. The two flow paths are respectively equipped with the main electronic expansion valve EEVH and the economizer electronic expansion valve EEVSC. The two expansion valves are the core control components of the system's refrigerant flow, and their flow rates are coupled and influence each other.

[0004] The current mainstream control solution in the industry is dual-valve independent PID control: Main circuit electronic expansion valve EEVH: Calculates the superheat at the evaporator outlet based on suction temperature and suction pressure, and adjusts the opening independently with the goal of keeping the superheat constant to ensure the refrigerant supply in the main heating flow path. Economizer Electronic Expansion Valve (EEVSC): Calculates superheat based on the inlet and outlet temperatures of the economizer, adjusts the opening independently, and controls the refrigerant flow in the jet enthalpy-increasing branch.

[0005] The above-mentioned independent control methods can basically meet the usage requirements under normal temperature conditions, but they have obvious defects under low temperature and ultra-low temperature heating conditions: the suction superheat of the unit is too small in low temperature environment, the opening of the main circuit electronic expansion valve EEVH is too large, the main heating flow path will take priority to occupy the system refrigerant flow, directly resulting in insufficient refrigerant supply to the Economizer side EEVSC, the vapor injection enthalpy-increasing branch cannot establish an effective vapor flow, the vapor injection enthalpy-increasing structure of the compressor cannot play its role, and ultimately the unit's low temperature heating capacity is insufficient, the energy efficiency ratio is far lower than the design value, and in severe cases, it can also cause compressor high temperature, liquid compressor and other operating failures.

[0006] Existing optimization schemes for a limited number of vapor injection enthalpy-boosting valves only address temperature correction for a single valve, failing to achieve dual-valve linkage flow constraint. This fails to fundamentally solve the problems of main line flow competition and insufficient flow in the vapor injection branch. Furthermore, during defrosting operation of existing vapor injection enthalpy-boosting units, the vapor injection enthalpy-boosting branch does not participate in the defrosting cycle, resulting in low refrigerant circulation in the outdoor heat exchanger, slow heat exchange and temperature rise, long defrosting cycles, large indoor temperature fluctuations, and a poor user experience. Therefore, developing an integrated control scheme that combines coordinated refrigerant distribution with vapor injection enthalpy-boosting defrosting optimization is a pressing technical challenge in this field. Summary of the Invention

[0007] This invention overcomes the shortcomings of existing jet enthalpy-enhancing systems, such as independent control of dual expansion valves, imbalance in low-temperature refrigerant distribution, failure of jet enthalpy enhancement function, slow defrosting speed, and large indoor temperature fluctuations. It provides a method and device for coordinated control of refrigerant distribution and gas-injection defrosting in a jet enthalpy-enhancing system. Through dual-valve cross-compensation in heating mode, multi-threshold segmented opening adjustment, and interlock protection in liquid-carrying mode, a balanced distribution of refrigerant flow between the main circuit and the jet branch is achieved. Simultaneously, a new gas-injection defrosting control logic is added, activating the jet enthalpy-enhancing branch to supplement refrigerant flow during the defrosting stage, improving defrosting heat exchange efficiency, shortening defrosting time, and comprehensively enhancing the unit's heating capacity, operating efficiency, and defrosting comfort under all operating conditions, especially ultra-low temperature conditions.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a method for coordinated control of refrigerant distribution and defrosting via vapor injection enthalpy enhancement system, applied to an air conditioning unit with a vapor injection enthalpy enhancement compressor. The unit includes a main circuit electronic expansion valve (EEVH), an economizer electronic expansion valve (EEVSC), a suction temperature sensor, a suction pressure sensor, an economizer inlet temperature sensor, an economizer outlet temperature sensor, a compressor discharge temperature sensor, an ambient temperature sensor, and a high-pressure pressure sensor. The control method includes a heating refrigerant coordinated distribution control method and a defrosting via vapor injection defrosting control method. The heating refrigerant coordinated distribution control method includes the following steps: S1. Collect unit operating parameters: Real-time collection of intake temperature TS, intake pressure PSL, economizer inlet temperature Tsin, economizer outlet temperature Tsout, compressor discharge temperature TD, ambient temperature TA, and high-pressure saturation temperature CT. S2. Calculate the basic control quantities: Calculate the basic opening adjustment of the main circuit electronic expansion valve EEVH and the basic opening adjustment of the economizer electronic expansion valve EEVSC respectively using the PID algorithm. S3. Main Circuit Expansion Valve Opening Compensation Control: Calculate the superheat ΔT1 at the inlet and outlet of the economizer (ΔT1 = Tsout - Tsin). When the economizer electronic expansion valve EEVSC is open and ΔT1 > 5℃, apply negative opening compensation to the main circuit electronic expansion valve EEVH. When the economizer electronic expansion valve EEVSC is closed, apply positive opening compensation based on the exhaust temperature and temperature rise trend. The final output opening of the main circuit electronic expansion valve EEVH is obtained by superimposing the corresponding compensation amount on the basic opening. S4. Economizer Expansion Valve Segmented Compensation Control: Based on the compressor discharge temperature TD and its real-time changes, the Economizer Electronic Expansion Valve EEVSC is applied with positive opening compensation in different levels; when TD≥100℃, the Economizer superheat target value is corrected; at the same time, an interlock condition is set: when ΔT1≤-2℃, all opening compensation actions of the Economizer Electronic Expansion Valve EEVSC are prohibited. S5. Output the final opening command to the main electronic expansion valve EEVH and the economizer electronic expansion valve EEVSC respectively to complete the coordinated distribution control of refrigerant flow. The defrosting control method divides defrosting into four operating stages and controls the opening of the indoor unit's electronic expansion valve in each stage. When the second defrosting operating stage meets the preset conditions, the EEVSC (Economy Evaporator Electronic Expansion Valve) is activated for defrosting circulation. The opening of the EEVSC is dynamically adjusted according to the exhaust superheat. After the exit conditions are met, the defrosting is turned off.

[0009] Furthermore, in step S2, the initial opening degree of the main circuit electronic expansion valve EEVH is calculated using the following formula: P EEVH =P1+P2×TA,P EEEVH ≤P3, where P1 is the EEVH reference opening degree, which is the factory setting value; P2 is the EEVH initial opening degree coefficient; and P3 is the upper limit of the EEVH initial opening degree. After the initial opening degree is maintained for 1 minute, the high superheat control stage begins. After the main circuit electronic expansion valve EEVH enters the high superheat control stage, it maintains the evaporator outlet superheat target of 10℃ for 5 minutes. After the high superheat control stage ends, it enters PID automatic adjustment. The refrigerant saturated evaporation temperature SST is calculated from the suction pressure PSL. With the evaporator outlet superheat degree = TS - SST as the control target, the opening degree adjustment increment y(t) is output through the PID algorithm, according to the formula P H (n)=P H (n-1)+y(t) calculates the basic opening degree of EEVH, and the refrigerant flow rate into the evaporator is controlled by adjusting the opening degree of EEVH; Among them, P H (n-1) represents the opening degree of the main circuit electronic expansion valve EEVH in the previous cycle, and y(t) represents the adjustment increment of the opening degree of the main circuit electronic expansion valve EEVH in this cycle.

[0010] Furthermore, in step S2, the initial opening degree of the Economizer Electronic Expansion Valve (EEVSC) is calculated using the formula: P EEVSC =P4+P5×TA,P EEVSC ≤P6, where P4 is the EEVSC reference opening (factory setting), P5 is the EEVSC initial opening coefficient, and P6 is the upper limit of the EEVSC initial opening. After maintaining the initial opening for 30 seconds, it enters PID automatic adjustment. The economizer inlet temperature Tsin and economizer outlet temperature Tsout are collected, and the economizer inlet and outlet superheat x(t) = Tsout - Tsin is calculated. The opening adjustment increment y(t) is output through the PID algorithm according to formula P. SC (n)=P SC (n-1)+y(t) calculates the basic opening of EEVSC, and the refrigerant flow through the economizer is controlled by adjusting the opening of EEVSC; Among them, PSC (n-1) represents the opening degree of the Economizer Electronic Expansion Valve EEVSC in the previous cycle, and y(t) represents the adjustment increment of the opening degree of the Economizer Electronic Expansion Valve EEVSC in the current cycle.

[0011] Furthermore, in step S3, the main circuit electronic expansion valve EEVH is supplemented with an opening compensation amount based on the basic opening degree. The compensation method is to differentiate the operation based on the opening and closing state of the economizer electronic expansion valve EEVSC. When the EEVSC opening degree is >0 and it is in the open state, a negative opening degree compensation amount ΔP is generated. H1 =-P H (n-1) / 50; When the EEVSC opening degree is ≤0 and it is in the closed state, ΔP H1 =0, and based on the compressor exhaust temperature TD, the single-cycle change in exhaust temperature TD(n)-TD(n-1), and the high-pressure saturation temperature CT, a positive compensation amount is superimposed: if TD-CT≥25℃, TD>80℃, and TD(n)-TD(n-1)>0℃ are simultaneously satisfied, a compensation amount ΔP is generated. H2 =P H (n-1) / 60; If TD≥100℃ and TD(n)-TD(n-1)>0℃ are satisfied simultaneously, the compensation amount ΔP is generated. H3 =P H (n-1) / 30; The final output opening of EEVH is calculated using the formula: P H (n)=P H (n-1)+y(t)+ΔP H1 +ΔP H2 +ΔP H3 Where y(t) is the EEVH basic opening adjustment increment output by the PID algorithm, and PH(n-1) is the EEVH output opening of the previous cycle.

[0012] Furthermore, step S4 applies positive opening compensation based on the compressor exhaust temperature TD, high-pressure saturation temperature CT, and the single-cycle change in exhaust temperature TD(n)-TD(n-1) at different levels: when TD-CT≥25℃, TD>80℃, and TD(n)-TD(n-1)>0℃ are simultaneously satisfied, the compensation amount ΔP sc1 =P sc (n-1) / 40; When both TD≥100℃ and TD(n)-TD(n-1)>0℃ are satisfied, the compensation amount ΔP sc2 =P sc (n-1) / 20; The formula for calculating the current opening degree of EEVSC after superimposed compensation is P. sc (n)=P sc (n-1)+y (t)+ΔP sc1 or Psc (n)=P sc (n-1)+y (t)+ΔP sc2 , where P sc (n-1) represents the opening degree of the electronic expansion valve EEVSC in the previous cycle, and y(t) represents the PID opening degree adjustment increment of EEVSC in the current cycle.

[0013] Furthermore, in step S2, the target value of ΔT1 under normal operating conditions is set to 1℃. When the compressor exhaust temperature TD≥100℃, the target value of superheat at the inlet and outlet of the economizer is corrected to -1℃.

[0014] Furthermore, 1 minute before the defrosting begins in the second operating phase, the electronic expansion valve of the operating indoor unit is fixed at 200PLS, and the valve of the shut-off indoor unit is fixed at 100PLS. After 1 minute, the opening of the electronic expansion valve of the operating indoor unit is adjusted according to the heat exchange temperature difference TRI3-min (TRI1 / 2): the valve is closed when the temperature difference is >3℃, the valve is opened when the temperature difference is <1℃, and the valve position remains unchanged when the temperature difference is between 1℃ and 3℃. Here, TRI3 is the refrigerant temperature at the outlet of the indoor unit heat exchanger, TRI2 is the refrigerant temperature in the middle section of the indoor unit heat exchanger, and TRI1 is the refrigerant temperature at the inlet of the indoor unit heat exchanger.

[0015] Furthermore, during the third stage of defrosting, the indoor unit's electronic expansion valve first maintains 200 PLS for 1 minute and then adjusts adaptively. When the unit stops, the indoor unit's electronic expansion valve locks at 40 PLS for 5 minutes, and then returns to its original opening before defrosting.

[0016] Furthermore, when the following conditions are met simultaneously: defrosting is in the second operating stage for 1 minute, TD-CT ≥ 25℃, compressor frequency Hz ≥ 43Hz, TD ≥ 50℃, and indoor unit capacity percentage ≥ 50%, the Economizer Electronic Expansion Valve (EEVSC) will be activated to replenish gas; P 霜 =P7+P8×TA calculates the initial opening of the electronic expansion valve EEVSC of the economizer, and P EEEVsc ≤P9, where P7 is the initial reference opening of the Economist Electronic Expansion Valve (EEVSC) under defrosting conditions, P8 is the ambient temperature correction coefficient for the initial opening of EEVSC under defrosting conditions, and P9 is the upper limit of the EEVSC opening under defrosting conditions. After holding for 10 seconds, the opening is corrected with the compressor exhaust superheat SHTD = 25℃ as the target. The compensation amount is calculated using the formula △P. 霜 =P10×(SHTD-25), where P10 is the defrost opening compensation coefficient, and the defrost EEVSC opening is updated in real time to satisfy P. 霜 (n) = P 霜 (n-1) + △P 霜 , where P 霜 (n-1) represents the EEVSC opening during the previous defrost cycle, P 霜(n) is the EEVSC opening degree for defrosting in this cycle; if any of the following conditions are met, such as the end of the second stage of defrosting operation, TD-CT≤15℃, or HZ<40HZ, the gas supply function will be turned off.

[0017] This invention also provides an apparatus employing a jet enthalpy enhancement system for refrigerant distribution coordination control and a gas injection defrosting method, comprising a compressor, a four-way valve, a main circuit electronic expansion valve EEVH, an economizer electronic expansion valve EEVSC, an evaporator, an economizer, a suction temperature sensor, a suction pressure sensor, an economizer inlet temperature sensor, an economizer outlet temperature sensor, a compressor discharge temperature sensor, an ambient temperature sensor, and a high-pressure sensor; the compressor is connected to the four-way valve and the economizer, the four-way valve is connected to the evaporator and the indoor unit, the evaporator is connected to the economizer, the main circuit electronic expansion valve EEVH is connected in series in the main refrigerant circuit between the economizer and the evaporator, and the economizer electronic expansion valve EEVSC is connected in series in the jet enthalpy enhancement branch between the economizer and the evaporator. The economizer is connected to the indoor unit; the suction temperature sensor and suction pressure sensor are located at the compressor suction port, the economizer inlet temperature sensor is located at the economizer inlet, the economizer outlet temperature sensor is located at the economizer outlet, the compressor discharge temperature sensor is located at the compressor discharge port, the ambient temperature sensor is located at the outdoor unit, and the high pressure sensor is located at the compressor discharge port; the signal output terminals of each sensor, the control terminals of the main circuit electronic expansion valve EEVH and the economizer electronic expansion valve EEVSC are all electrically connected to the controller. The controller executes the control method based on the temperature and pressure signals collected by each sensor and outputs control signals to the main circuit electronic expansion valve EEVH and the economizer electronic expansion valve EEVSC.

[0018] Compared with the prior art, the beneficial effects of the present invention are: Dual electronic expansion valves work together to precisely control flow, improving the stability of heating operation: Through independent feedforward initial opening of the EEVH main valve and EEVSC jet branch valve + PID closed-loop regulation, combined with exhaust temperature segmented opening compensation and economizer overheat interlock protection logic, the refrigerant distribution can be dynamically matched for high and low temperature heating conditions; under high temperature and high exhaust conditions, the jet flow is automatically increased to cool down, and the valve line is shielded and compensated to avoid liquid slugging when liquid is in the valve line, taking into account the compressor's operational reliability and heating heat exchange efficiency, and solving the problems of exhaust overheating and refrigerant distribution imbalance in low temperature heating.

[0019] The main valve is compensated differently according to different operating conditions, and the system heat exchange efficiency is optimized: The main valve compensation strategy is distinguished according to the opening and closing of EEVSC: when the jet branch is open, negative compensation is applied to reduce the refrigerant in the main circuit; when the jet branch is closed, the main valve is opened in the positive direction according to the exhaust temperature rise. The adaptive matching of the two operating modes with and without jet enthalpy increase avoids the refrigerant excess or deficiency caused by single fixed value compensation. The evaporator heat exchange is sufficient and the heating capacity output is more stable.

[0020] The system features a four-stage refined defrosting control system, ensuring fast defrosting speed and high indoor comfort. Defrosting is divided into four independent control stages, differentiating between the fixed opening of the electronic expansion valve in the running / shutdown indoor unit and its adaptive adjustment logic. In the second stage of defrosting, the operating indoor unit's valve opening is automatically corrected using the indoor heat exchange temperature difference to prevent the indoor coils from freezing and causing a sudden drop in temperature during defrosting. In the shutdown stage, the indoor unit's valve is locked for an extended period to reduce refrigerant backflow, and heating is quickly restored after defrosting.

[0021] EEVSC air injection control for defrosting shortens defrosting time and reduces energy consumption: After defrosting meets multiple composite conditions, it automatically starts air injection. Instead of using complex PI calculations, it directly and quickly corrects the air injection valve opening based on the exhaust superheat of 25°C, increasing the refrigerant flow and heat exchange temperature difference of the outdoor heat exchanger. Once the exit conditions are met, the air injection is immediately shut off, with no ineffective air injection loss, significantly shortening defrosting time and reducing indoor temperature drop during defrosting.

[0022] Multiple threshold interlock protection significantly reduces the unit's failure rate: The system features multiple judgment conditions, including economizer superheat liquid interlock, exhaust temperature segmentation limit, valve opening upper and lower limit constraints, and defrost gas supply start and stop. This fully utilizes the enthalpy-increasing and cooling capabilities of the jet gas, while completely preventing liquid refrigerant from entering the compressor's intermediate cavity and causing liquid slugging. This extends the service life of the compressor and expansion valve under all operating conditions, including high and low temperatures and defrosting.

[0023] The control logic is clearly layered and adaptable to multi-split air conditioning systems with multiple indoor units in parallel: it is also compatible with separate control logic for multiple indoor units, distinguishes between the operation and shutdown of indoor unit valves for independent control, and takes into account different load ratios of multi-split air conditioning systems; the indoor unit capacity ratio is used as the condition for starting defrosting and gas supply, resulting in higher load matching; it can adaptively adjust under all operating conditions of partial load, low temperature heating, and defrosting, resulting in higher unit operating efficiency. Attached Figure Description

[0024] Figure 1 This is a system schematic diagram of the device used in the embodiment. Detailed Implementation

[0025] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below through examples.

[0026] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0027] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0028] like Figure 1 As shown, the system hardware composition The unit includes a main circuit electronic expansion valve EEVH1, an economizer electronic expansion valve EEVSC2, an evaporator 3, a suction temperature sensor 4, a suction pressure sensor 5, an economizer 6, an economizer inlet temperature sensor 7, an economizer outlet temperature sensor 8, a compressor discharge temperature sensor 9, a vapor injection enthalpy compressor 10, and an ambient temperature sensor 11. The data collected by the supporting sensors include: suction temperature TS, suction pressure PSL, economizer inlet temperature Tsin, economizer outlet temperature Tsout, compressor discharge temperature TD, and ambient temperature TA. The controller uses a dedicated MCU.

[0029] Example 1: Low-temperature heating conventional coordinated control condition (ambient temperature TA=0℃, no defrosting)

[0030] The refrigerant distribution and coordinated control method for the jet enthalpy enhancement system provided in this embodiment is as follows: Parameter acquisition: The controller acquires the following parameters in real time: TA=0℃, suction saturated evaporation temperature SST=0℃, suction temperature TS=10℃, evaporator outlet superheat 10℃; economizer inlet Tsin=20℃, outlet Tsout=26℃, and calculates economizer superheat ΔT1=6℃; compressor discharge temperature TD=92℃, high-pressure saturation temperature CT=60℃, TD-CT=32℃, compressor frequency 55Hz, and TD shows an upward trend in a single cycle.

[0031] Initial opening calculation: Calculate the initial opening P of EEVH based on TA. EEVH =P1+P2×0, upper limit constraint P3, maintain high superheat control for 1 minute; EEVSC initial opening P EEVSC =P4+P5×0, upper limit constraint P6, maintain for 30s and then enter PID automatic adjustment. Under normal operating conditions, the economizer target superheat is 1℃, and under this operating condition ΔT1=6℃, which is higher than the target, the PID continuously outputs positive opening increment.

[0032] Main valve compensation determination: The current opening degree of EEVSC is greater than 0 and is in the open state, and ΔT1>5℃, apply negative compensation ΔPH1=-PH (n-1) / 50; shield the positive compensation ΔPH2 and ΔPH3 for exhaust temperature; superimpose the PID adjustment and negative compensation to obtain the final opening degree of EEVH, reduce the refrigerant flow of the main circuit, increase the refrigerant supply of the jet branch, and reduce the compressor exhaust temperature.

[0033] Economizer valve segmental compensation: TD>80℃, TD-CT≥25℃, temperature continues to rise, generating compensation amount ΔPsc1=Psc (n-1) / 40, superimposed on the EEVSC basic opening ΔT1=6℃>-2℃, interlock protection is not triggered, compensation is effective normally.

[0034] Output execution: The controller sends the final opening signals of EEVH and EEVSC to the drive module, synchronously adjusts the refrigerant flow of the two channels, stabilizes the exhaust superheat, ensures stable low-temperature heating output of the unit, controls the exhaust temperature within 95℃, and prevents over-temperature protection shutdown.

[0035] Example 2: High-temperature heating condition (TA=30℃, TD≥100℃) With an ambient temperature of TA=30℃, the compressor operates at full load. After stabilization, the exhaust temperature TD=103℃. TD continues to rise, CT=65℃, TD-CT=38℃, and ΔT1=4℃.

[0036] The refrigerant distribution and coordinated control method for the jet enthalpy enhancement system provided in this embodiment is as follows: Target superheat correction: TD≥100℃, the controller will correct the standard target superheat of the economizer from 1℃ to -1℃, allowing the economizer to slightly carry liquid to enhance the cooling effect.

[0037] Compensation superposition logic: When EEVSC is activated, ΔT1 = 4℃ < 5℃, the main valve does not apply negative compensation; when the exhaust temperature meets TD ≥ 100℃ and the temperature rises, the EEVSC superposition compensation amount ΔPsc2 = Psc (n-1) / 20, further opening the jet valve, increasing the air supply volume and rapidly reducing the exhaust temperature.

[0038] Interlock verification: ΔT1 > -2℃, EEVSC opening compensation is executed normally; if there is too much refrigerant during operation, ΔT1 drops to -3℃, the system immediately disables all compensations for ΔPsc1 and ΔPsc2 to prevent a large amount of liquid refrigerant from entering the compressor and causing liquid slugging.

[0039] Example 3: Defrosting Process Control Conditions With an outdoor ambient temperature of -5℃, the unit meets the defrosting start-up conditions after 45 minutes of heating operation. The controller divides the defrosting into four stages and simultaneously executes indoor unit EEV regulation and EEVSC defrosting gas replenishment control.

[0040] (1) First stage of defrosting Before the defrosting conditions are met and the four-way valve switches to cooling, the unit maintains its original conventional heating and cooling coordinated control. EEVH and EEVSC execute conventional PID compensation logic, and the indoor unit valve maintains the opening degree for heating operation.

[0041] (2) Defrosting stage 2 (the four-way valve is switched to OFF and held for more than 1 minute) Indoor unit valve control: For the first 60 seconds, the indoor unit's EEV is fixed at 200PLS during operation, and the indoor unit's EEV is fixed at 100PLS when the unit is stopped; after 1 minute, TRI1, TRI2, and TRI3 are collected, and the heat exchange temperature difference TRI3-min(TRI1 / 2) = 4℃ > 3℃ is calculated. The controller continuously closes the electronic expansion valve of the indoor unit to reduce the amount of refrigerant in the room and prevent the coil from freezing; if the temperature difference drops to 0.5℃, the valve will automatically open.

[0042] Defrost and gas replenishment activation criteria: After running for 1 minute in the second stage, if TD-CT=28℃, compressor HZ=45Hz, TD=58℃, and indoor unit capacity reaches 60%, and all conditions are met, EEVSC defrosting and gas replenishment will be activated. Defrosting opening adjustment: controlled by P 霜 =P7+P8×TA calculates the initial opening degree and limits it to not exceed P9, maintaining the fixed opening degree for 10s; PI calculation is not enabled, and real-time correction is performed with SHTD=25℃ as the target. Actual measured SHTD=32℃, ΔP 霜 = P10×7, continuously increase EEVSC to improve jet flow and accelerate defrosting of the outdoor heat exchanger.

[0043] (3) Defrosting third stage (from the time the exit conditions are met until the four-way valve switches back to heating) After the indoor unit valve maintains an opening of 200PLS for 1 minute, it will automatically adjust. When the indoor unit is stopped, the EEV will lock at 40PLS and continuously throttle for 5 minutes to reduce refrigerant backflow. At this time, the compressor frequency drops to 38Hz, which meets the gas replenishment exit condition HZ < 40Hz, and the EEVSC defrosting gas replenishment will be directly shut off.

[0044] (4) Defrosting Stage 4 (Four-way valve switched to ON) The refrigerant discharge process is executed, all expansion valves exit the defrost-specific control logic, and the normal heating PID coordinated regulation is gradually restored. After the indoor unit valves are stopped and the 5-minute timer is completed, the original opening degree before defrosting is restored, and the unit quickly raises the indoor heating temperature.

[0045] It should be noted that 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 preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for coordinated control of refrigerant distribution and defrosting in a vapor injection enthalpy-enhancing system, applied to an air conditioning unit with a vapor injection enthalpy-enhancing compressor, the unit comprising a main circuit electronic expansion valve EEVH, an economizer electronic expansion valve EEVSC, a suction temperature sensor, a suction pressure sensor, an economizer inlet temperature sensor, an economizer outlet temperature sensor, a compressor discharge temperature sensor, an ambient temperature sensor, and a high-pressure sensor, characterized in that... The control methods include a heating refrigerant coordinated distribution control method and a gas injection and defrosting control method. The heating refrigerant coordinated distribution control method includes the following steps: S1. Collect unit operating parameters: Real-time collection of intake temperature TS, intake pressure PSL, economizer inlet temperature Tsin, economizer outlet temperature Tsout, compressor discharge temperature TD, ambient temperature TA, and high-pressure saturation temperature CT. S2. Calculate the basic control quantities: Calculate the basic opening adjustment of the main circuit electronic expansion valve EEVH and the basic opening adjustment of the economizer electronic expansion valve EEVSC respectively using the PID algorithm. S3. Main Circuit Expansion Valve Opening Compensation Control: Calculate the superheat ΔT1 at the inlet and outlet of the economizer (ΔT1 = Tsout - Tsin). When the economizer electronic expansion valve EEVSC is open and ΔT1 > 5℃, apply negative opening compensation to the main circuit electronic expansion valve EEVH. When the economizer electronic expansion valve EEVSC is closed, apply positive opening compensation based on the exhaust temperature and temperature rise trend. The final output opening of the main circuit electronic expansion valve EEVH is obtained by superimposing the corresponding compensation amount on the basic opening. S4. Economizer Expansion Valve Segmented Compensation Control: Based on the compressor discharge temperature TD and its real-time changes, the Economizer Electronic Expansion Valve EEVSC is applied with positive opening compensation in different levels; when TD≥100℃, the Economizer superheat target value is corrected; at the same time, an interlock condition is set: when ΔT1≤-2℃, all opening compensation actions of the Economizer Electronic Expansion Valve EEVSC are prohibited. S5. Output the final opening command to the main electronic expansion valve EEVH and the economizer electronic expansion valve EEVSC respectively to complete the coordinated distribution control of refrigerant flow. The defrosting control method divides defrosting into four operating stages and controls the opening of the indoor unit's electronic expansion valve in each stage. When the second defrosting operating stage meets the preset conditions, the EEVSC (Economy Evaporator Electronic Expansion Valve) is activated for defrosting circulation. The opening of the EEVSC is dynamically adjusted according to the exhaust superheat. After the exit conditions are met, the defrosting is turned off.

2. The method for coordinated control of refrigerant distribution and defrosting in a jet enthalpy enhancement system according to claim 1, characterized in that, In step S2, the initial opening degree of the main electronic expansion valve EEVH is calculated using the following formula: P EEVH =P1+P2×TA,P EEEVH ≤P3, where P1 is the EEVH reference opening degree, which is the factory setting value; P2 is the EEVH initial opening degree coefficient; and P3 is the upper limit of the EEVH initial opening degree. After the initial opening degree is maintained for 1 minute, the high superheat control stage begins. After the main circuit electronic expansion valve EEVH enters the high superheat control stage, it maintains the evaporator outlet superheat target of 10℃ for 5 minutes. After the high superheat control stage ends, it enters PID automatic adjustment. The refrigerant saturated evaporation temperature SST is calculated from the suction pressure PSL. With the evaporator outlet superheat degree = TS - SST as the control target, the opening degree adjustment increment y(t) is output through the PID algorithm, according to the formula P H (n)=P H (n-1)+y(t) calculates the basic opening degree of EEVH, and the refrigerant flow rate into the evaporator is controlled by adjusting the opening degree of EEVH; Among them, P H (n-1) represents the opening degree of the main circuit electronic expansion valve EEVH in the previous cycle, and y(t) represents the adjustment increment of the opening degree of the main circuit electronic expansion valve EEVH in this cycle.

3. The method for coordinated control of refrigerant distribution and defrosting in a jet enthalpy enhancement system according to claim 1, characterized in that: In step S2, the initial opening degree of the Economizer Electronic Expansion Valve (EEVSC) is calculated using the formula: P EEVSC =P4+P5×TA,P EEVSC ≤P6, where P4 is the EEVSC reference opening (factory setting), P5 is the EEVSC initial opening coefficient, and P6 is the upper limit of the EEVSC initial opening. After maintaining the initial opening for 30 seconds, it enters PID automatic adjustment. The inlet temperature Tsin and outlet temperature Tsout of the economizer are collected, and the superheat at the inlet and outlet of the economizer x(t) = Tsout - Tsin is calculated. The opening adjustment increment y(t) is output through the PID algorithm according to formula P. SC (n)=P SC (n-1)+y(t) calculates the basic opening of EEVSC, and the refrigerant flow through the economizer is controlled by adjusting the opening of EEVSC. Among them, P SC (n-1) represents the opening degree of the Economizer Electronic Expansion Valve EEVSC in the previous cycle, and y(t) represents the adjustment increment of the opening degree of the Economizer Electronic Expansion Valve EEVSC in the current cycle.

4. The method for coordinated control of refrigerant distribution and defrosting in a jet enthalpy enhancement system according to claim 2, characterized in that: In step S3, the main circuit electronic expansion valve EEVH is adjusted by adding an opening compensation amount to the basic opening. The compensation method is based on the opening and closing status of the economizer electronic expansion valve EEVSC. When the EEVSC opening degree is greater than 0 and the system is in the open state, a negative opening degree compensation amount ΔP is generated. H1 =-P H (n-1) / 50; When the EEVSC opening degree is ≤0 and it is in the closed state, ΔP H1 =0, and based on the compressor exhaust temperature TD, the single-cycle change in exhaust temperature TD(n)-TD(n-1), and the high-pressure saturation temperature CT, a positive compensation amount is superimposed: if TD-CT≥25℃, TD>80℃, and TD(n)-TD(n-1)>0℃ are simultaneously satisfied, a compensation amount ΔP is generated. H2 =P H (n-1) / 60; If TD≥100℃ and TD(n)-TD(n-1)>0℃ are satisfied simultaneously, the compensation amount ΔP is generated. H3 =P H (n-1) / 30; The final output opening of EEVH is calculated using the formula: P H (n)=P H (n-1)+y(t)+ΔP H1 +ΔP H2 +ΔP H3 Where y(t) is the EEVH basic opening adjustment increment output by the PID algorithm, and PH(n-1) is the EEVH output opening of the previous cycle.

5. The method for coordinated control of refrigerant distribution and defrosting in a jet enthalpy enhancement system according to claim 3, characterized in that: Step S4 applies positive opening compensation based on the compressor exhaust temperature TD, high-pressure saturation temperature CT, and the single-cycle change in exhaust temperature TD(n)-TD(n-1) at different levels: when TD-CT≥25℃, TD>80℃, and TD(n)-TD(n-1)>0℃ are simultaneously satisfied, the compensation amount ΔP sc1 =P sc (n-1) / 40; When both TD≥100℃ and TD(n)-TD(n-1)>0℃ are satisfied, the compensation amount ΔP sc2 =P sc (n-1) / 20; The formula for calculating the current opening degree of EEVSC after superimposed compensation is P. sc (n)=P sc (n-1)+y (t)+ΔP sc1 or P sc (n)=P sc (n-1)+y (t)+ΔP sc2 , where P sc (n-1) represents the opening degree of the electronic expansion valve EEVSC in the previous cycle, and y(t) represents the PID opening degree adjustment increment of EEVSC in the current cycle.

6. The method for coordinated control of refrigerant distribution and defrosting in a jet enthalpy enhancement system according to claim 5, characterized in that, In step S2, the target value of ΔT1 under normal operating conditions is set to 1℃. When the compressor exhaust temperature TD≥100℃, the target value of superheat at the inlet and outlet of the economizer is corrected to -1℃.

7. The method for coordinated control of refrigerant distribution and defrosting in a jet enthalpy enhancement system according to claim 1, characterized in that, One minute before the defrosting begins in the second operating phase, the electronic expansion valve of the indoor unit is fixed at 200 PLS and the valve of the indoor unit is fixed at 100 PLS. After one minute, the opening of the electronic expansion valve of the indoor unit is adjusted according to the heat exchange temperature difference TRI3−min(TRI1 / 2): valve is closed when the temperature difference is >3℃, valve is opened when the temperature difference is <1℃, and the valve position remains unchanged when the temperature difference is between 1℃ and 3℃. Here, TRI3 is the refrigerant temperature at the outlet of the indoor unit heat exchanger, TRI2 is the refrigerant temperature in the middle section of the indoor unit heat exchanger, and TRI1 is the refrigerant temperature at the inlet of the indoor unit heat exchanger.

8. The method for coordinated control of refrigerant distribution and defrosting in a jet enthalpy enhancement system according to claim 1, characterized in that, During the third stage of defrosting, the indoor unit's electronic expansion valve first maintains 200 PLS for 1 minute and then adjusts adaptively. When the unit stops, the indoor unit's electronic expansion valve locks at 40 PLS for 5 minutes, and then returns to its original opening before defrosting.

9. The method for coordinated control of refrigerant distribution and defrosting in a jet enthalpy enhancement system according to claim 1, characterized in that, Simultaneously, when defrosting is in the second operating stage for 1 minute, TD-CT ≥ 25℃, compressor frequency Hz ≥ 43Hz, TD ≥ 50℃, and indoor unit capacity percentage ≥ 50%, the Economizer Electronic Expansion Valve (EEVSC) is activated to replenish gas; P 霜 =P7+P8×TA calculates the initial opening of the electronic expansion valve EEVSC of the economizer, and P EEEVsc ≤P9, where P7 is the initial reference opening of the Economist Electronic Expansion Valve (EEVSC) under defrosting conditions, P8 is the ambient temperature correction coefficient for the initial opening of EEVSC under defrosting conditions, and P9 is the upper limit of the EEVSC opening under defrosting conditions. After holding for 10 seconds, the opening is corrected with the compressor exhaust superheat SHTD = 25℃ as the target. The compensation amount is calculated using the formula △P. 霜 =P10×(SHTD-25), where P10 is the defrost opening compensation coefficient, and the defrost EEVSC opening is updated in real time to satisfy P. 霜 (n) = P 霜 (n-1) + △P 霜 , where P 霜 (n-1) represents the EEVSC opening during the previous defrost cycle, P 霜 (n) is the EEVSC opening degree for defrosting in this cycle; if any of the following conditions are met, such as the end of the second stage of defrosting operation, TD-CT≤15℃, or HZ<40HZ, the gas supply function will be turned off.

10. An apparatus employing the refrigerant distribution coordination control and gas replenishment defrosting method of any one of claims 1 to 9 in a jet enthalpy enhancement system, characterized in that, The system includes a compressor, a four-way valve, a main circuit electronic expansion valve (EEVH), an economizer electronic expansion valve (EEVSC), an evaporator, an economizer, a suction temperature sensor, a suction pressure sensor, an economizer inlet temperature sensor, an economizer outlet temperature sensor, a compressor discharge temperature sensor, an ambient temperature sensor, and a high-pressure sensor. The compressor is connected to the four-way valve and the economizer. The four-way valve is connected to the evaporator and the indoor unit. The evaporator is connected to the economizer. The main circuit electronic expansion valve (EEVH) is connected in series in the main refrigerant circuit between the economizer and the evaporator. The economizer electronic expansion valve (EEVSC) is connected in series in the vapor injection enthalpy-increasing branch between the economizer and the evaporator. The economizer is connected to the indoor unit; the suction temperature sensor and suction pressure sensor are located at the compressor suction port, the economizer inlet temperature sensor is located at the economizer inlet, the economizer outlet temperature sensor is located at the economizer outlet, the compressor discharge temperature sensor is located at the compressor discharge port, the ambient temperature sensor is located at the outdoor unit, and the high pressure sensor is located at the compressor discharge port; the signal output terminals of each sensor, the control terminals of the main circuit electronic expansion valve EEVH and the economizer electronic expansion valve EEVSC are all electrically connected to the controller, and the controller executes the control method described in any one of claims 1 to 9 according to the temperature and pressure signals collected by each sensor, and outputs control signals to the main circuit electronic expansion valve EEVH and the economizer electronic expansion valve EEVSC.

Images