Method for adjusting initial stage, operation stage and closing stage of electronic expansion valve

Abstract

The invention relates to the technical field of electronic expansion valve adjustment, in particular to an adjustment method for an initial stage, an operation stage and a closing stage of an electronic expansion valve. The method comprises the following steps that S1, the current environment temperature and the current actual water temperature are obtained; s2, inputting the obtained environment temperature and the actual water temperature into a preset initial opening calculation model to obtain an initial opening value of the electronic expansion valve; and S3, the initial opening degree of the electronic expansion valve is adjusted according to the obtained initial opening degree value. According to the method, the initial opening degree of the electronic expansion valve is dynamically calculated, adjustment lag caused by the fixed opening degree is avoided, the time of the system from starting to stabilizing is shortened, and therefore quick response and stable operation under the extreme working conditions of high-temperature cooling, low-temperature heating and the like are ensured, and the limitation of traditional fixed opening degree control is overcome.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic expansion valve adjustment, in particular to an adjustment method for the initial stage, running stage and closing stage of an electronic expansion valve. BACKGROUND

[0002] In the design of an air conditioning system, an electronic expansion valve is used as an electronic control element to control the opening degree thereof according to the system superheat degree, so as to control the discharge temperature of a compressor. The electronic expansion valve has a high precision, a fast, accurate and energy-saving action, and is widely used in refrigeration and air conditioning.

[0003] The opening degree control method of the electronic expansion valve of a current variable frequency air conditioning unit mainly adopts a method of directly presetting a fixed initial opening degree to start, and then generating a control electronic expansion valve running opening degree by a conventional adjustment strategy to generate a given opening degree increase / decrease amplitude of the electronic expansion valve. In actual work, the air conditioning unit is used for heating in a low-temperature environment and cooling in a high-temperature environment, and the working environment temperature fluctuates greatly, about between -35℃ and 43℃. In addition, the water temperature of the air conditioning unit is about between 10℃ and 60℃ when starting. If the electronic expansion valve adopts a fixed opening degree in the initial stage under different working conditions, it will obviously cause the time required for the air conditioning unit to stabilize from starting to system stabilization to be prolonged under most working conditions, and thus needs to be solved urgently. SUMMARY

[0004] In order to avoid and overcome the technical problems in the prior art, the present application provides an adjustment method for the initial stage, running stage and closing stage of an electronic expansion valve, which dynamically calculates the initial opening degree of the electronic expansion valve, avoids the adjustment lag caused by the fixed opening degree, shortens the time from starting to stabilization of the system, and thus ensures the fast response and stable operation under extreme working conditions such as high-temperature cooling and low-temperature heating, and overcomes the limitations of the conventional fixed opening degree control.

[0005] To achieve the above object, the present application provides the following technical scheme:

[0006] The adjustment method for the initial stage of the electronic expansion valve comprises the following steps:

[0007] S1, obtaining the current environment temperature and the current actual water temperature;

[0008] S2, inputting the obtained environment temperature and actual water temperature into a preset initial opening degree calculation model to obtain an initial opening degree value of the electronic expansion valve;

[0009] The initial opening degree calculation model is specifically as follows:

[0010] P EXVE1 =EXV1+(T wJ -T w )*P+(T a -TaJ )*M

[0011] P = T EXVE1 is the initial opening value of the electronic expansion valve, in pls;

[0012] EXV1 is the rated opening, in pls;

[0013] T wJ is the reference water temperature, in ℃;

[0014] T win is the current actual water temperature, in ℃;

[0015] T a is the current ambient temperature, in ℃;

[0016] T aJ is the reference ambient temperature, in ℃;

[0017] P is the water temperature influence coefficient;

[0018] M is the ambient temperature influence coefficient;

[0019] S3, adjusting the initial opening of the electronic expansion valve according to the obtained initial opening value.

[0020] The adjustment method of the running stage, which applies the adjustment method of the initial stage of the electronic expansion valve, keeps the initial opening value running for a fixed adjustment period after the start of the unit; continuously obtains the discharge temperature T d of the compressor, the fin temperature T def of the compressor, the discharge superheat T dsh of the compressor, and the current opening value P i of the electronic expansion valve, and generates the predetermined opening increase / decrease amplitude of the electronic expansion valve according to the conventional adjustment strategy before each subsequent fixed adjustment period of the electronic expansion valve;

[0021] Before each subsequent fixed adjustment period, it is first determined whether T d and T dsh are in the abnormal interval, if so, the electronic expansion valve is adjusted according to the discharge abnormal strategy and the superheat abnormal strategy respectively; if not, it is further determined whether T def is in the abnormal interval, if T def is in the abnormal interval, the electronic expansion valve is adjusted according to the fin abnormal strategy; if T def is not in the abnormal interval, the electronic expansion valve is adjusted according to the optimization adjustment strategy;

[0022] In addition, if the compressor frequency changes in each fixed adjustment period, the frequency opening adjustment range is generated according to the conventional frequency adjustment strategy, and before adjustment in each fixed adjustment period, the opening of the electronic expansion valve is adjusted according to the frequency opening adjustment range.

[0023] As a further scheme of the present application, the optimization adjustment strategy is specifically: cumulative continuous increase or cumulative continuous decrease of a plurality of previous fixed adjustment periods is obtained, and a difference value of the exhaust temperature at the end of the last fixed adjustment period and the beginning of the last fixed adjustment period is obtained; thereafter, it is first judged whether the current opening value P of the electronic expansion valve i and the set interval of the difference value of the exhaust temperature, and then it is judged whether the cumulative continuous decrease or the cumulative continuous increase exceeds the decrease threshold or the increase threshold corresponding to the set interval, if not, the electronic expansion valve is directly adjusted according to the predetermined opening adjustment range; if the decrease threshold is exceeded, the electronic expansion valve is limited to only perform the adjustment operation of opening the valve with the predetermined opening adjustment range in the subsequent fixed adjustment period; if the increase threshold is exceeded, it is further judged whether the difference value of the exhaust temperature exceeds the temperature increase threshold, if yes, the electronic expansion valve is limited to only perform the adjustment operation of opening the valve with the predetermined opening adjustment range in the subsequent fixed adjustment period, if not, the electronic expansion valve is limited to only perform the adjustment operation of closing the valve with the predetermined opening adjustment range in the subsequent fixed adjustment period.

[0024] As a further scheme of the present application, in the optimization adjustment strategy:

[0025] When P i > 240 pls, the difference value of the exhaust temperature of the last fixed adjustment period is in the full range, and the decrease threshold is 8% of the current opening; the increase threshold is 6% of the current opening;

[0026] When 160 pls≤P i ≤240 pls, the difference value of the exhaust temperature of the last fixed adjustment period is in the full range, and the decrease threshold is 6% of the current opening; when the difference value of the exhaust temperature of the last fixed adjustment period is less than or equal to 4℃, the increase threshold is 5% of the current opening, and when the difference value of the exhaust temperature of the last fixed adjustment period is greater than 4℃, the increase threshold is 4% of the current opening;

[0027] When P iWhen the exhaust temperature difference is less than or equal to 1 ℃ in the last fixed adjustment cycle, the decrease threshold is 6% of the current opening, the temperature increase in the last fixed adjustment cycle is greater than 1 ℃, and the decrease threshold is 5% of the current opening; when the exhaust temperature difference is less than or equal to 1.5 ℃ in the last fixed adjustment cycle, the increase threshold is 5% of the current opening, the exhaust temperature difference in the last fixed adjustment cycle is less than or equal to 2.5 ℃ and greater than or equal to 1.5 ℃, the increase threshold is 4% of the current opening, and the exhaust temperature difference in the last fixed adjustment cycle is greater than 2.5 ℃, the increase threshold is 3% of the current opening.

[0028] As a further scheme of the application, in the optimization adjustment strategy:

[0029] When P i > 240 pls, and the electronic expansion valve opening in the last fixed adjustment cycle is decreased:

[0030] If the exhaust temperature difference is less than or equal to 2 ℃, the electronic expansion valve is limited to perform the adjustment operation of opening the valve with a certain opening increase / decrease amplitude in the subsequent fixed adjustment cycle;

[0031] If the exhaust temperature difference is greater than 2 ℃ and less than or equal to 4 ℃, the electronic expansion valve is limited to perform the adjustment operation of opening the valve with a certain opening increase / decrease amplitude in the subsequent two fixed adjustment cycles;

[0032] If the exhaust temperature difference is greater than 4 ℃, the electronic expansion valve is limited to perform the adjustment operation of opening the valve with a certain opening increase / decrease amplitude in the subsequent three fixed adjustment cycles;

[0033] When P i > 240 pls, and the electronic expansion valve opening in the last fixed adjustment cycle is increased:

[0034] At this time, the temperature increase threshold is 2 ℃, and if the exhaust temperature difference is less than or equal to 2 ℃, the electronic expansion valve is limited to perform the adjustment operation of closing the valve with a certain opening increase / decrease amplitude in the subsequent two fixed cycles;

[0035] If the exhaust temperature difference is greater than 2 ℃ and less than or equal to 5 ℃, the electronic expansion valve is limited to perform the adjustment operation of opening the valve with a certain opening increase / decrease amplitude in the subsequent fixed cycle;

[0036] If the exhaust temperature difference is greater than 5 ℃, the electronic expansion valve is limited to perform the adjustment operation of opening the valve with a certain opening increase / decrease amplitude in the subsequent two fixed adjustment cycles;

[0037] When 160 pls≤P i ≤240 pls, and the electronic expansion valve opening in the last fixed adjustment cycle is decreased;

[0038] If the exhaust gas temperature difference is less than or equal to 2°C, then in the subsequent one fixed adjustment period, the electronic expansion valve is limited to perform the adjustment operation of opening the valve by the predetermined opening degree increase / decrease amplitude;

[0039] If the exhaust gas temperature difference is greater than 2°C and less than or equal to 3°C, then in the subsequent two fixed adjustment periods, the electronic expansion valve is limited to perform the adjustment operation of opening the valve by the predetermined opening degree increase / decrease amplitude;

[0040] If the exhaust gas temperature difference is greater than 3°C, then in the subsequent three fixed adjustment periods, the electronic expansion valve is limited to perform the adjustment operation of opening the valve by the predetermined opening degree increase / decrease amplitude;

[0041] When 160 pls ≤ P i < 240 pls, and the electronic expansion valve opening degree of the previous fixed adjustment period is rising;

[0042] At this time, the temperature increase threshold is 1.5°C, and if the exhaust gas temperature difference is less than or equal to 1.5°C, then in the subsequent two fixed adjustment periods, the electronic expansion valve is limited to perform the adjustment operation of closing the valve by the predetermined opening degree increase / decrease amplitude;

[0043] If the exhaust gas temperature difference is greater than 1.5°C and less than or equal to 4°C, then in the subsequent three fixed adjustment periods, the electronic expansion valve is limited to perform the adjustment operation of opening the valve by the predetermined opening degree increase / decrease amplitude;

[0044] If the exhaust gas temperature difference is greater than 4°C, then in the subsequent two fixed adjustment periods, the electronic expansion valve is limited to perform the adjustment operation of opening the valve by the predetermined opening degree increase / decrease amplitude;

[0045] When P i < 160 pls, and the electronic expansion valve opening degree of the previous fixed adjustment period is falling:

[0046] If the exhaust gas temperature difference is less than or equal to 1°C, then in the subsequent two fixed adjustment periods, the electronic expansion valve is limited to perform the adjustment operation of opening the valve by the predetermined opening degree increase / decrease amplitude;

[0047] If the exhaust gas temperature difference is greater than 1°C and less than or equal to 2.5°C, then in the subsequent two fixed adjustment periods, the electronic expansion valve is limited to perform the adjustment operation of opening the valve by the predetermined opening degree increase / decrease amplitude;

[0048] If the exhaust gas temperature difference is greater than 2.5°C, then in the subsequent three fixed adjustment periods, the electronic expansion valve is limited to perform the adjustment operation of opening the valve by the predetermined opening degree increase / decrease amplitude;

[0049] When P i < 160 pls, and the electronic expansion valve opening degree of the previous fixed adjustment period is rising:

[0050] The temperature rise threshold at this time is 1.5℃, if the exhaust temperature difference is less than or equal to 1.5℃, then in the subsequent two fixed adjustment periods, the electronic expansion valve is limited to perform the adjustment operation of closing the valve with the predetermined opening degree increase / decrease amplitude;

[0051] If the exhaust temperature difference is greater than 1.5℃ and less than or equal to 2.5℃, then in the subsequent three fixed adjustment periods, the electronic expansion valve is limited to perform the adjustment operation of opening the valve with the predetermined opening degree increase / decrease amplitude.

[0052] If the exhaust temperature difference is greater than 2.5℃, then in the subsequent two fixed adjustment periods, if the predetermined opening degree increase / decrease amplitude is an increase, the electronic expansion valve is limited to perform the adjustment operation of opening the valve with the predetermined opening degree increase / decrease amplitude.

[0053] As a further scheme of the present application: the execution condition of the superheat abnormality strategy is T dsh <the minimum exhaust superheat T dshmin , and the exhaust abnormality strategy is specifically: in the subsequent fixed adjustment periods, the electronic expansion valve is limited to perform the adjustment operation of closing the valve with the predetermined opening degree increase / decrease amplitude, until T dsh ≥ the minimum exhaust superheat T dshmin .

[0054] As a further scheme of the present application: the execution condition of the exhaust abnormality strategy is T d ≥ 105℃, and the exhaust abnormality strategy is specifically: obtaining the first opening degree value of the electronic expansion valve at this time, in the subsequent fixed adjustment periods, the electronic expansion valve is limited to perform the adjustment operation of opening the valve with the predetermined opening degree increase / decrease amplitude, until the exhaust temperature decreases and the exhaust temperature is less than 100℃, obtaining the second opening degree value of the electronic expansion valve at this time, and obtaining the increase difference of the second opening degree value minus the first opening degree value, and in the subsequent fixed adjustment periods, the electronic expansion valve is limited to perform the adjustment operation of closing the valve with the predetermined opening degree increase / decrease amplitude, until the electronic expansion valve decreases by a cumulative amplitude greater than or equal to 0.4 times the increase difference, and taking two fixed adjustment periods of the electronic expansion valve as one actual adjustment period, and after three actual adjustment periods, the fixed adjustment period is restored.

[0055] As a further scheme of the present application: the execution condition of the fin abnormality strategy is T def <the target fin temperature at the start of defrosting + 2℃, and the fin abnormality strategy is specifically: in the subsequent fixed adjustment periods, the electronic expansion valve is limited to perform the adjustment operation of opening the valve with the predetermined opening degree increase / decrease amplitude, and the amplitude of opening the valve is 1.5 times the predetermined opening degree increase / decrease amplitude, until T dsh ≥ the target fin temperature at the start of defrosting + 2℃.

[0056] The adjustment method of the closing stage applies the adjustment method of the running stage, when the compressor receives a shutdown command, the electronic expansion valve keeps the current opening degree, when the compressor shuts down to 0Hz, the opening degree of the electronic expansion valve is adjusted to 80pls and kept for 120 seconds, then the opening degree of the electronic expansion valve is adjusted to 200pls, and after receiving the next startup adjustment command, the initial opening degree of the electronic expansion valve is adjusted according to the initial opening degree adjustment method of the electronic expansion valve.

[0057] Compared with the prior art, the application has the following beneficial effects:

[0058] 1. By obtaining different current actual water temperature and current ambient temperature, the initial opening degree of the electronic expansion valve can be obtained. In practice, for normal adjustment under normal conditions, the electronic expansion valve adopts different initial opening degrees, and the final stabilization time is different. When the initial opening degree of the electronic expansion valve is close to the initial opening degree calculated by the initial opening degree calculation model, the time required from startup to system stabilization is the shortest. It is also proved that the initial opening degree calculated by the initial opening degree calculation model of the application can reduce the adjustment time during the running of the unit from startup to system stabilization, avoid the adjustment lag caused by fixed opening degree, shorten the time from startup to stabilization of the system, and thus ensure the rapid response and stable operation under extreme conditions such as high-temperature cooling and low-temperature heating, and overcome the limitations of traditional fixed opening degree control.

[0059] 2. Before each fixed adjustment period, the given opening degree increase / decrease amplitude of the electronic expansion valve is generated according to the existing normal adjustment strategy, and then the layered abnormal state is judged to preferentially process the exhaust gas overheating abnormality that may cause the unit to lose control and the exhaust gas temperature or the compressor to be damaged, to ensure the safety of the system; secondly, the fin temperature abnormality is processed to avoid false defrosting; and when there is no abnormality, the optimized adjustment strategy is adopted to realize precise and stable operation control. Overall, safety, anti-misoperation and energy efficiency optimization are taken into account.

[0060] 3. When the current opening degree value of the electronic expansion valve and the exhaust gas temperature difference value are in different set intervals, the cumulative continuous decrease amplitude and the cumulative continuous increase amplitude of the valve step of the electronic expansion valve are compared with the decrease amplitude threshold and the increase amplitude threshold respectively.

[0061] If the decrease amplitude threshold is exceeded, the electronic expansion valve is limited to only perform the adjustment operation of opening the valve with the given opening degree increase / decrease amplitude in the subsequent several fixed adjustment periods, to prevent the cumulative continuous decrease amplitude from further expanding in the adjacent several periods, to ensure that the exhaust gas temperature is in a reasonable and stable fluctuation interval, and to avoid repeated adjustment of the electronic expansion valve, so that the system can enter the stable running stage more quickly.

[0062] If the increase threshold is exceeded, the system further determines whether the exhaust temperature difference exceeds the temperature rise threshold. If so, the exhaust temperature increase rate remains high. Therefore, for several subsequent fixed adjustment cycles, the electronic expansion valve is limited to only performing adjustment operations with a predetermined opening increase or decrease range of the valve opening, further reducing the exhaust temperature increase rate. If the increase rate is not exceeded, the exhaust temperature increase rate is adjusted too low. Therefore, for several subsequent fixed adjustment cycles, the electronic expansion valve is limited to only performing adjustment operations with a predetermined opening increase or decrease range of the valve closing, ensuring that the exhaust temperature fluctuates within a reasonable and stable range, avoiding repeated adjustments of the electronic expansion valve, and allowing the system to enter a stable operation phase more quickly.

[0063] 4. This application sets the current opening value of the electronic expansion valve to three numerical ranges of high, medium and low, and also sets the exhaust temperature difference to three numerical ranges of high, medium and low. When the current opening value of the electronic expansion valve and the exhaust temperature difference are in different numerical ranges, the difference in the increase threshold or decrease threshold is optimized to ensure that the fluctuation of the exhaust temperature is more stable, so that the system can enter the stable operation stage faster.

[0064] 5. On the basis of the above, when the current opening value of the electronic expansion valve and the exhaust temperature difference are in different numerical ranges, the number of cycles is further limited to ensure that the exhaust temperature fluctuation is more stable, so that the system can enter the stable operation stage more quickly.

[0065] 6. The exhaust abnormality strategy adopts a smoother adjustment method, which makes the valve closing amplitude smaller when the electronic expansion valve is closing, and can avoid repeated triggering of excessive exhaust temperature, which may cause the system to be unable to operate stably.

[0066] 7. During the shutdown phase of the unit, first reduce the opening of the electronic expansion valve and hold it for a while, then increase it and hold it. This can prevent the electronic expansion valve from opening too wide just after the shutdown phase, causing a large amount of refrigerant to flow to the low-pressure side. As a result, when the unit is restarted, the refrigerant on the low-pressure side will instantly vaporize and take away a large amount of refrigeration oil, causing oil shortage. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 This is a flowchart of the initial stage of the electronic expansion valve in the present invention.

[0068] Figure 2 This is a flowchart of the workflow for optimizing and adjusting the electronic expansion valve in the present invention.

[0069] Figure 3 The present invention is a flowchart of the workflow for obtaining a predetermined opening increase or decrease range in the prior art. DETAILED DESCRIPTION

[0070] With reference to the accompanying drawings, the technical solutions in the embodiments of the present application will be clearly and completely described below, obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work are within the protection scope of the present application.

[0071] For the convenience of understanding, the specific structure and working mode of the present application will be further described below in combination with the drawings:

[0072] The present application mainly comprises: a regulating method of an electronic expansion valve in an initial stage of a variable frequency air conditioning unit in a starting stage, a regulating method of an electronic expansion valve in a running stage of a variable frequency air conditioning unit in a running stage and a regulating method of an electronic expansion valve in a closing stage of a variable frequency air conditioning unit in a closing stage.

[0073] Among them:

[0074] I. As Figure 1 shown, the regulating method of the electronic expansion valve in the initial stage comprises the following steps:

[0075] S1, obtaining a current environment temperature and a current actual water temperature;

[0076] S2, inputting the obtained environment temperature and actual water temperature into a preset initial opening degree calculation model to obtain an initial opening degree value of the electronic expansion valve;

[0077] Among them, the initial opening degree calculation model is specifically:

[0078] P EXVE1 =EXV1+(T wJ -T w )*N+(T a -T aJ )*M

[0079] In the formula: R EXVE1 is the initial opening degree value of the electronic expansion valve, and the unit is pls;

[0080] EXV1 is a rated opening degree, and the unit is pls;

[0081] T wJ is a reference water temperature, and the unit is ℃;

[0082] T win is a current actual water temperature, and the unit is ℃;

[0083] T a is a current environment temperature, and the unit is ℃;

[0084] T aJ is a reference environment temperature, and the unit is ℃;

[0085] N is a water temperature influence coefficient;

[0086] M is an ambient temperature influence coefficient;

[0087] S3, adjusting the initial opening degree of the electronic expansion valve according to the obtained initial opening degree value.

[0088] In the above initial opening degree calculation model, the reference water temperature is 41℃, and the reference ambient temperature is 7℃.

[0089] In addition, when the current ambient temperature T a The value of the ambient temperature influence coefficient M at different ambient temperature reference values is shown in Table 1, and the value of the rated opening degree EXV1 is shown in Table 3; when the current ambient temperature T a The value of the ambient temperature influence coefficient M at different ambient temperature reference values and the current actual water temperature T win The value of the water temperature influence coefficient N at different water temperature reference values is shown in Table 2.

[0090] Table 1: Ambient temperature influence coefficient M value table

[0091]

[0092] Table 2: Water temperature influence coefficient N value table

[0093]

[0094] Table 3: Rated point valve opening degree EXV1 value table

[0095]

[0096] In the above Tables 1-3, M1-M3, N1-N9, P1-P3 are all obtained by interpolation method.

[0097] Specifically, the interpolation method is a prior art, and for the sake of understanding, the interpolation method value of the ambient temperature influence coefficient M1 when the current ambient temperature is -25℃ is taken as an example:

[0098] M1 = M value when ambient temperature reference value is -30℃ + (current ambient temperature -25℃ - ambient temperature reference value -30℃) * (M value when ambient temperature reference value is -20℃ - M value when ambient temperature reference value is -30℃) / (ambient temperature reference value -20℃ - ambient temperature reference value -30℃)

[0099] = 1.5 + (-25+30) * (2.1-1.5) / (-20+30)

[0100] = 1.5 + 0.3

[0101] = 1.8.

[0102] Similarly, the water temperature influence coefficient N calculation formula, first through the current environmental temperature and the current actual water temperature to determine the water temperature influence coefficient N interval, such as environmental temperature is 25℃, water temperature is 35℃, water temperature influence coefficient N value is N8, with the above interpolation method for solving the same reason, the difference is to water temperature control value as the interpolation method for solving the reference, thereby solving the value of N8.

[0103] N8 = water temperature control value for 30℃ N value + (current actual water temperature 35℃- water temperature control value 30℃)*(water temperature control value for 45℃ N value- water temperature control value for 30℃ N value) / (water temperature control value 45℃- water temperature control value 30℃)

[0104] = 4.5 + (35-30)*(3.5-4.5) / (45-30)

[0105] ≈4.17.

[0106] To verify the application effect of the initial opening of the electronic expansion valve calculated by the initial opening calculation model of the electronic expansion valve:

[0107] Practice 1, under the current environmental temperature of-12℃, the current actual water temperature of 41℃, the initial opening of the electronic expansion valve is 147pls according to the initial opening calculation model of the electronic expansion valve,

[0108] When the unit is started under the above working condition, the electronic expansion valve is adjusted to different opening degrees, and the subsequent adjustment is carried out according to the conventional adjustment method under normal circumstances (not the adjustment method of the running stage described later, the specific conventional adjustment and the adjustment of the running stage of the present application are compared in the following text).

[0109] After the unit is started, the electronic expansion valve is adjusted after maintaining the initial opening of 170pls, and after 28min, the system runs stably (the valve opening remains unchanged), and the valve step finally stabilizes at 160pls.

[0110] After the unit is started, the electronic expansion valve is adjusted after maintaining the initial opening of 147pls, and after 25min, the system runs stably (the valve opening remains unchanged), and the valve step finally stabilizes at 160pls.

[0111] After the unit is started, the electronic expansion valve is adjusted after maintaining the initial opening of 130pls, and after 27min, the system runs stably (the valve opening remains unchanged), and the valve step finally stabilizes at 160pls.

[0112] Practice 2, in the current environmental temperature is -12℃, the current actual water temperature 55℃ working condition, according to the initial opening degree of electronic expansion valve calculation model derived initial opening degree of electronic expansion valve is 119 pls,

[0113] Test, in the above working condition, when the unit is started, the electronic expansion valve is adjusted to different opening degrees, and then the subsequent adjustment is carried out according to the conventional adjustment mode under normal circumstances. The results are as follows:

[0114] After the unit is started, the electronic expansion valve is adjusted to different opening degrees, and then the subsequent adjustment is carried out according to the conventional adjustment mode under normal circumstances. The results are as follows:

[0115] After the unit is started, the electronic expansion valve is adjusted to different opening degrees, and then the subsequent adjustment is carried out according to the conventional adjustment mode under normal circumstances. The results are as follows:

[0116] After the unit is started, the electronic expansion valve is adjusted to different opening degrees, and then the subsequent adjustment is carried out according to the conventional adjustment mode under normal circumstances. The results are as follows:

[0117] Obviously, from the results of the above practice 1 and practice 2, for the conventional adjustment under normal circumstances, the electronic expansion valve takes different initial opening degrees, and the final stable time is different. When the initial opening degree of the electronic expansion valve is close to the initial opening degree calculated by the initial opening degree calculation model, the time from starting to system stabilization is the shortest. It is also proved that the initial opening degree calculated by the initial opening degree calculation model of the present application can reduce the adjustment time from starting to system stabilization, avoid the adjustment lag caused by fixed opening degree, shorten the time from starting to stabilization, and ensure the rapid response and stable operation under extreme working conditions such as high temperature cooling and low temperature heating, and overcome the limitations of traditional fixed opening degree control.

[0118] The adjustment method of the running stage, the adjustment method of the running stage applies the adjustment method of the initial stage of the electronic expansion valve.

[0119] The existing adjustment method is: after the unit is started, the initial opening degree value is kept for a fixed adjustment period, and the discharge temperature T d of the compressor, the fin temperature T def of the compressor, the discharge superheat T dsh of the compressor and the current opening value P i, and before each fixed adjustment cycle of the electronic expansion valve in the following, the electronic expansion valve is generated according to the conventional adjustment strategy The set opening increment or decrement of the electronic expansion valve is generated according to the conventional adjustment strategy The adjustment strategy is as shown in Figure 3 The part is a conventional strategy in the prior art, and the detailed PID calculation process of the electronic expansion valve adjustment value is not expanded in detail in the present application, and only the set opening increment or decrement result calculated therefrom is further controlled.

[0120] On the basis of the above, before each fixed adjustment cycle in the following, it is first judged whether T d And T dsh Is the abnormal interval, if so, the electronic expansion valve is adjusted according to the exhaust abnormal strategy and the overheating degree abnormal strategy respectively, which is respectively used to prevent the unit from losing control due to high exhaust temperature and to protect the compressor; if not, it is judged whether T def Is the abnormal interval, if T def Is the abnormal interval, the electronic expansion valve is adjusted according to the fin abnormal strategy to prevent the electronic expansion valve from being defrosted due to the inaccuracy of the traditional PID calculation adjustment precision; if T def Is not the abnormal interval, the electronic expansion valve is adjusted according to the optimization adjustment strategy; in addition, if the compressor frequency changes in each fixed adjustment cycle, the frequency opening increment or decrement is generated according to the conventional frequency adjustment strategy, and before each fixed adjustment cycle, the opening of the electronic expansion is adjusted according to the frequency opening increment or decrement.

[0121] The present application adopts hierarchical judgment of abnormal state, preferentially processes the exhaust overheating degree abnormality which may cause the unit to lose control of exhaust temperature or the compressor to be damaged, and ensures the safety of the system; secondly processes the fin temperature abnormality to avoid false defrosting; when there is no abnormality, the optimization adjustment strategy is adopted to realize precise and stable operation control. Overall, safety, anti-misoperation and energy efficiency optimization are taken into account.

[0122] On the basis of the above, as shown in Figure 2 The optimization adjustment strategy is specifically: the cumulative continuous rise or the cumulative continuous fall of a plurality of fixed adjustment cycles in advance is obtained, and the exhaust temperature difference between the end of the last fixed adjustment cycle and the beginning of the last fixed adjustment cycle is obtained; thereafter, it is first judged whether the current opening value P i Of the electronic expansion valve and the exhaust temperature difference current set interval, and then it is judged whether the cumulative continuous fall or the cumulative continuous rise exceeds the fall threshold or the rise threshold corresponding to the set interval, if not, the electronic expansion valve is directly adjusted according to the set opening increment or decrement, that is, the electronic expansion valve is adjusted according to the set opening increment or decrement according to the conventional method.

[0123] When the opening degree of the electronic expansion valve is a decrease amplitude in the previous fixed adjustment period, the increase rate of the exhaust gas temperature is increased; if the decrease amplitude threshold is exceeded, the electronic expansion valve is limited to perform the adjustment operation of the opening valve with a predetermined opening degree increase / decrease amplitude in the subsequent several fixed adjustment periods, to prevent the electronic expansion valve from continuously decreasing the opening degree in adjacent periods, which further expands the decrease amplitude and causes the exhaust gas temperature to increase too much in the subsequent fixed adjustment period, so as to ensure that the exhaust gas temperature is in a reasonable and stable fluctuation range, avoid repeated adjustment of the electronic expansion valve, and make the system enter the stable operation stage more quickly.

[0124] When the opening degree of the electronic expansion valve is an increase amplitude in the previous fixed adjustment period, the increase rate of the exhaust gas temperature is decreased; if the increase amplitude threshold is exceeded, it is further judged whether the exhaust gas temperature difference exceeds the temperature increase threshold; if it exceeds, it means that the increase rate of the exhaust gas temperature is still high, so the electronic expansion valve is limited to perform the adjustment operation of the opening valve with a predetermined opening degree increase / decrease amplitude in the subsequent several fixed adjustment periods, to further reduce the increase rate of the exhaust gas temperature. If it does not exceed, it means that the increase rate of the exhaust gas temperature is adjusted too low, so the electronic expansion valve is limited to perform the adjustment operation of the closing valve with a predetermined opening degree increase / decrease amplitude in the subsequent several fixed adjustment periods, to ensure that the exhaust gas temperature is in a reasonable and stable fluctuation range, avoid repeated adjustment of the electronic expansion valve, and make the system enter the stable operation stage more quickly.

[0125] On the basis of the above, the optimization adjustment strategy is:

[0126] When P i > 240 pls, the exhaust gas temperature difference in the previous fixed adjustment period is in the full range, and the decrease amplitude threshold is 8% of the current opening degree; the increase amplitude threshold is 6% of the current opening degree;

[0127] When 160 pls≤P i ≤240 pls, the exhaust gas temperature difference in the previous fixed adjustment period is in the full range, and the decrease amplitude threshold is 6% of the current opening degree; when the exhaust gas temperature difference in the previous fixed adjustment period is less than or equal to 4℃, the increase amplitude threshold is 5% of the current opening degree, and when the exhaust gas temperature difference in the previous fixed adjustment period is greater than 4℃, the increase amplitude threshold is 4% of the current opening degree;

[0128] When P iWhen the exhaust temperature difference is less than or equal to 1℃ in the last fixed adjustment cycle, the decrease threshold is 6% of the current opening, the temperature increase is greater than 1℃ in the last fixed adjustment cycle, the decrease threshold is 5% of the current opening, the exhaust temperature difference is less than or equal to 1.5℃ in the last fixed adjustment cycle, the increase threshold is 5% of the current opening, the exhaust temperature difference is less than or equal to 2.5℃ and greater than or equal to 1.5℃ in the last fixed adjustment cycle, the increase threshold is 4% of the current opening, and the exhaust temperature difference is greater than 2.5℃, the increase threshold is 3% of the current opening.

[0129] As the opening of the electronic expansion valve is greater, the medium flow is greater, and the change range of the exhaust temperature is greater. The current opening value P of the electronic expansion valve is determined according to the exhaust temperature difference. i The exhaust temperature difference is set to high, medium and low value ranges, and the current opening value P of the electronic expansion valve is set to high, medium and low value ranges. i When the current opening value P of the electronic expansion valve and the exhaust temperature difference are in different value ranges, the difference of the optimized increase threshold or decrease threshold is ensured to make the fluctuation of the exhaust temperature more stable, so that the system enters the stable running stage more quickly.

[0130] On the basis of the above, the optimization adjustment strategy is:

[0131] When P i > 240 pls, and the opening of the electronic expansion valve in the last fixed adjustment cycle is decreased:

[0132] If the exhaust temperature difference is less than or equal to 2℃, the electronic expansion valve is limited to execute the adjustment operation of opening the valve with the given opening increase / decrease range in the subsequent fixed adjustment cycle;

[0133] If the exhaust temperature difference is greater than 2℃ and less than or equal to 4℃, the electronic expansion valve is limited to execute the adjustment operation of opening the valve with the given opening increase / decrease range in the subsequent two fixed adjustment cycles;

[0134] If the exhaust temperature difference is greater than 4℃, the electronic expansion valve is limited to execute the adjustment operation of opening the valve with the given opening increase / decrease range in the subsequent three fixed adjustment cycles;

[0135] When P i > 240 pls, and the opening of the electronic expansion valve in the last fixed adjustment cycle is increased:

[0136] At this time, the temperature increase threshold is 2℃, if the exhaust temperature difference is less than or equal to 2℃, the electronic expansion valve is limited to execute the adjustment operation of closing the valve with the given opening increase / decrease range in the subsequent two fixed adjustment cycles;

[0137] If the exhaust gas temperature difference is greater than 2°C and less than or equal to 5°C, then in the subsequent one fixed adjustment period, the electronic expansion valve is limited to perform the adjustment operation of opening the valve by the predetermined opening degree increase / decrease amplitude;

[0138] If the exhaust gas temperature difference is greater than 5°C, then in the subsequent two fixed adjustment periods, the electronic expansion valve is limited to perform the adjustment operation of opening the valve by the predetermined opening degree increase / decrease amplitude;

[0139] When 160 pls≤P i ≤240 pls, and the electronic expansion valve opening degree of the previous fixed adjustment period is decreased;

[0140] If the exhaust gas temperature difference is less than or equal to 2°C, then in the subsequent one fixed adjustment period, the electronic expansion valve is limited to perform the adjustment operation of opening the valve by the predetermined opening degree increase / decrease amplitude;

[0141] If the exhaust gas temperature difference is greater than 2°C and less than or equal to 3°C, then in the subsequent two fixed adjustment periods, the electronic expansion valve is limited to perform the adjustment operation of opening the valve by the predetermined opening degree increase / decrease amplitude;

[0142] If the exhaust gas temperature difference is greater than 3°C, then in the subsequent three fixed adjustment periods, the electronic expansion valve is limited to perform the adjustment operation of opening the valve by the predetermined opening degree increase / decrease amplitude;

[0143] When 160 pls≤P i ≤240 pls, and the electronic expansion valve opening degree of the previous fixed adjustment period is increased;

[0144] At this time, the temperature increase threshold is 1.5°C, and if the exhaust gas temperature difference is less than or equal to 1.5°C, then in the subsequent two fixed adjustment periods, the electronic expansion valve is limited to perform the adjustment operation of closing the valve by the predetermined opening degree increase / decrease amplitude;

[0145] If the exhaust gas temperature difference is greater than 1.5°C and less than or equal to 4°C, then in the subsequent three fixed adjustment periods, the electronic expansion valve is limited to perform the adjustment operation of opening the valve by the predetermined opening degree increase / decrease amplitude;

[0146] If the exhaust gas temperature difference is greater than 4°C, then in the subsequent two fixed adjustment periods, the electronic expansion valve is limited to perform the adjustment operation of opening the valve by the predetermined opening degree increase / decrease amplitude;

[0147] When P i < 160 pls, and the electronic expansion valve opening degree of the previous fixed adjustment period is decreased:

[0148] If the exhaust gas temperature difference is less than or equal to 1°C, then in the subsequent two fixed adjustment periods, the electronic expansion valve is limited to perform the adjustment operation of opening the valve by the predetermined opening degree increase / decrease amplitude;

[0149] If the exhaust temperature difference is greater than 1℃ and less than or equal to 2.5℃, then in the subsequent two fixed adjustment periods, the electronic expansion valve is limited to perform the adjustment operation of opening the valve by the predetermined opening degree increase / decrease amplitude;

[0150] If the exhaust temperature difference is greater than 2.5℃, then in the subsequent three fixed adjustment periods, the electronic expansion valve is limited to perform the adjustment operation of opening the valve by the predetermined opening degree increase / decrease amplitude;

[0151] When P i <160 pls, and the previous fixed adjustment period electronic expansion valve opening degree is rising:

[0152] At this time, the temperature rise threshold is 1.5℃, if the exhaust temperature difference is less than or equal to 1.5℃, then in the subsequent two fixed adjustment periods, the electronic expansion valve is limited to perform the adjustment operation of closing the valve by the predetermined opening degree increase / decrease amplitude;

[0153] If the exhaust temperature difference is greater than 1.5℃ and less than or equal to 2.5℃, then in the subsequent three fixed adjustment periods, the electronic expansion valve is limited to perform the adjustment operation of opening the valve by the predetermined opening degree increase / decrease amplitude;

[0154] If the exhaust temperature difference is greater than 2.5℃, then in the subsequent two fixed adjustment periods, if the predetermined opening degree increase / decrease amplitude is opening the valve, the electronic expansion valve is limited to perform the adjustment operation of opening the valve by the predetermined opening degree increase / decrease amplitude.

[0155] The present application sets the current opening degree value P i of the electronic expansion valve to high, medium and low three numerical ranges, and sets the exhaust temperature difference to high, medium and low three numerical ranges, and the current opening degree value P i of the electronic expansion valve and the exhaust temperature difference are in different numerical ranges, further limit the number of periods to ensure that the fluctuation of the exhaust temperature is more stable, so that the system enters the stable running stage more quickly.

[0156] In practice, under the working condition of an ambient temperature of-12℃ and an outlet water temperature of 41℃,

[0157] According to the optimization adjustment strategy of the present application:

[0158] After starting, the initial opening degree of the electronic expansion valve is 147 pls, and after 20 min, the unit runs stably at 160 pls, the minimum valve step is 135 pls, and the maximum valve step is 175 pls;

[0159] Without the above optimization adjustment strategy:

[0160] After starting, the initial opening of the electronic expansion valve is 147 pls, and after 25 minutes, the unit runs stably at 160 pls, with the minimum valve step being 120 pls and the maximum valve step being 180 pls.

[0161] From the above valve step operation data, using the above-mentioned optimization adjustment strategy, the unit requires less time to run stably, the valve step adjustment is more stable, and the up and down amplitude is smaller.

[0162] On the above basis, the execution condition of the superheat abnormality strategy is T dsh <minimum exhaust gas superheat T dshmin In actual implementation, to meet the compressor reliability requirements, the minimum exhaust gas superheat T dshmin Generally, a value not lower than 15℃ can meet the minimum oil temperature superheat requirement. Of course, under different refrigerant requirements, the minimum exhaust gas superheat T dshmin The value is different, which can be set according to the actual requirements of the compressor. The exhaust gas abnormality strategy is as follows: in the subsequent fixed adjustment period, the electronic expansion valve is limited to only perform the adjustment operation of the predetermined opening increment / decrement amplitude of the closed valve, until T dsh ≥minimum exhaust gas superheat T dshmin The conventional frequency adjustment strategy is the prior art, and the frequency opening increment / decrement amplitude is obtained according to the product of the frequency change value and the valve step adjustment coefficient. Through the above adjustment mode, the value of the exhaust gas superheat can be prevented from being too small, and the protection of the compressor can be effectively realized.

[0163] The execution condition of the exhaust gas abnormality strategy is T d ≥105℃, and the exhaust gas abnormality strategy is as follows: the first opening value of the electronic expansion valve at this time is obtained, in the subsequent fixed adjustment period, the electronic expansion valve is limited to only perform the adjustment operation of the predetermined opening increment / decrement amplitude of the open valve, until the exhaust gas temperature decreases and the exhaust gas temperature <100℃, the second opening value of the electronic expansion valve at this time is obtained, and the increment difference between the second opening value and the first opening value is obtained, and in the subsequent fixed adjustment period, the electronic expansion valve is limited to only perform the adjustment operation of the predetermined opening increment / decrement amplitude of the closed valve, until the electronic expansion valve in this stage decreases by more than or equal to 0.4 times the increment difference, and takes the fixed adjustment period of the two electronic expansion valves as one actual adjustment period, and after three actual adjustment periods, the fixed adjustment period is restored.

[0164] In practice, under the working conditions of an ambient temperature of-25℃ and a water outlet temperature of 50℃, the opening of the electronic expansion valve is adjusted according to the exhaust gas temperature abnormality strategy of the present application and the opening of the electronic expansion valve is adjusted according to the conventional adjustment strategy, and the comparison is as follows:

[0165] When the exhaust abnormality strategy is used in practice, when the exhaust temperature Td ≥ 105°C, in the subsequent three fixed adjustment cycles, the predetermined opening increase and decrease amplitudes of the generated electronic expansion valve are +20pls, +15pls, and +15pls, then the increase difference is 50pls, and the increase difference of 0.4 times is 20pls. When it is detected that the valve needs to be closed, that is, when the exhaust temperature drops, in two of the subsequent fixed adjustment cycles, the predetermined opening increase and decrease amplitudes are -15pls and -10pls. After closing the valve twice according to the predetermined opening increase and decrease amplitude, the cumulative decrease amplitude of the electronic expansion valve of 25pls is greater than the increase difference of 0.4 times. Thereafter, the valve is closed once every 2*TM, and the valve closing amplitudes for three consecutive actual adjustment cycles are 7pls, 5pls, and 3pls, and the fixed adjustment cycle is restored. At this time, T d <105℃;

[0166] If the aforementioned abnormal exhaust strategy is not implemented, when the exhaust temperature Td ≥ 105°C, the electronic expansion valve's opening amplitude is generated to increase or decrease by +20 pls, +15 pls, and +15 pls in the subsequent three fixed adjustment cycles. When the valve closing is detected, i.e., the exhaust temperature drops, the valve is closed continuously by -15 pls, -10 pls, -10 pls, -10 pls, and -9 pls in subsequent adjustment cycles. Then, when the exhaust temperature Td ≥ 105°C is met again, the valve opening amplitude is increased by +20 pls, +15 pls, and +13 pls, repeatedly triggering excessively high exhaust temperatures and preventing stable operation.

[0167] Compared with the above actual operating conditions, when the exhaust temperature changes drastically, the use of exhaust abnormality strategy logic control can more easily control the stable operation of the unit.

[0168] The execution condition of the fin abnormality strategy is T def <Target fin temperature at the start of defrosting + 2°C. The specific fin abnormality strategy is: in the subsequent fixed adjustment cycle, the electronic expansion valve is limited to only perform the adjustment operation with the predetermined opening increase or decrease amplitude being the valve opening, and the valve opening amplitude is 1.5 times the predetermined opening increase or decrease amplitude, until T def ≥Target fin temperature when defrosting starts + 2°C, at the compressor fin temperature T def The temperature is about to be lower than the target fin temperature during defrosting. By increasing the opening of the electronic expansion valve, it is possible to avoid the electronic expansion valve from defrosting due to inaccurate traditional PID calculation and adjustment accuracy.

[0169] The adjustment method of the closing stage is applied to the adjustment method of the running stage, when the compressor receives a shutdown command, the electronic expansion valve keeps the current opening degree, when the compressor is shut down to a frequency of 0Hz, the opening degree of the electronic expansion valve is adjusted to 80pls and kept for 120 seconds, after that, the opening degree of the electronic expansion valve is adjusted to 200pls, until the next time the opening adjustment command is received, the initial opening degree of the electronic expansion valve is adjusted according to the initial opening degree adjustment method of the electronic expansion valve. The adjustment method can prevent the opening degree of the electronic expansion valve from being too large during the just shutdown stage, which causes a large amount of refrigerant to flow to the low pressure side, and then causes the low pressure side refrigerant to instantaneously vaporize and take away a large amount of refrigeration oil when starting again, resulting in oil deficiency.

[0170] Of course, the present application is not limited to the details of the above-described exemplary embodiments, but also includes the same or similar structures that can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered in all respects as illustrative and not restrictive, the scope of the present application being defined by the appended claims rather than the above description, and it is intended to encompass all changes falling within the meaning and range of equivalents of the claims. Any reference signs in the claims should not be considered as limiting the claims to which they relate.

[0171] Furthermore, it should be understood that, although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that those skilled in the art can understand.

[0172] The technologies, shapes, and structural parts not described in detail in the present application are well-known technologies.

Claims

1. The adjustment method of the electronic expansion valve in the initial stage is characterized by: The following steps are involved: S1. Get the current ambient temperature and the current actual water temperature; S2. Inputting the acquired ambient temperature and actual water temperature into a preset initial opening calculation model to obtain an initial opening value of the electronic expansion valve; The initial opening calculation model is as follows: P EXVE1 =EXV1+(T wJ -T w )*P+(T a -T aJ )*M Where: P EXVE1 is the initial opening value of the electronic expansion valve, in pls; EXV1 is the rated opening, in pls; T wJ is the reference water temperature, in °C; T win is the current actual water temperature, in °C; T a is the current ambient temperature, in °C; T aJ The reference ambient temperature is in °C; P is the water temperature influence coefficient; M is the ambient temperature influence coefficient; S3. Adjust the initial opening of the electronic expansion valve according to the obtained initial opening value.

2. The adjustment method in the operation phase is applied to the adjustment method in the initial phase of the electronic expansion valve as claimed in claim 1, characterized in that: After the unit is started, the initial opening value is maintained and a fixed adjustment cycle is run; the exhaust temperature T of the compressor is continuously obtained. d , compressor fin temperature T def , compressor exhaust superheat T dsh And the current opening value P of the electronic expansion valve i , and before each subsequent fixed adjustment cycle of the electronic expansion valve, generate a predetermined increase or decrease range of the opening of the electronic expansion valve according to the conventional adjustment strategy; Before each subsequent fixed adjustment cycle, first determine T d and T dsh Is it an abnormal range? If so, adjust the electronic expansion valve according to the exhaust abnormality strategy and superheat abnormality strategy respectively; if not, then judge T def Is it an abnormal interval? If T def If it is an abnormal range, the electronic expansion valve is adjusted according to the fin abnormality strategy; if T def If it is not in the abnormal range, the electronic expansion valve is adjusted according to the optimization adjustment strategy; In addition, within each fixed adjustment cycle, if the compressor frequency changes, the frequency opening increase or decrease range is generated according to the conventional frequency adjustment strategy, and before adjusting each fixed adjustment cycle, the opening of the electronic expansion is adjusted according to the frequency opening increase or decrease range.

3. The adjustment method in the operation phase according to claim 2, characterized in that: The optimization adjustment strategy is specifically as follows: obtaining the cumulative continuous increase or decrease of several previous fixed adjustment cycles, and obtaining the exhaust temperature difference between the end of the previous fixed adjustment cycle and the beginning of the previous fixed adjustment cycle; thereafter, first determining the current opening value P of the electronic expansion valve i The difference between the exhaust temperature and the current set range is determined, and then the cumulative continuous decrease or the cumulative continuous increase is judged to see whether it exceeds the decrease threshold or increase threshold corresponding to the set range. If it does not exceed, the electronic expansion valve is directly adjusted according to the predetermined opening increase or decrease range; If the decrease threshold is exceeded, the electronic expansion valve is limited to only performing the adjustment operation of opening the valve with a predetermined increase or decrease in the opening degree within several subsequent fixed adjustment cycles; if the increase threshold is exceeded, it is further determined whether the exhaust temperature difference exceeds the temperature increase threshold. If it exceeds, the electronic expansion valve is limited to only performing the adjustment operation of opening the valve with a predetermined increase or decrease in the opening degree within several subsequent fixed adjustment cycles. If it does not exceed, the electronic expansion valve is limited to only performing the adjustment operation of closing the valve with a predetermined increase or decrease in the opening degree within several subsequent fixed adjustment cycles.

4. The adjustment method in the operation phase according to claim 3, characterized in that: In the optimization and adjustment strategy: When P i When the exhaust temperature difference of the previous fixed adjustment cycle is greater than 240 pls, within the full range, the decrease threshold is 8% of the current opening; the increase threshold is 6% of the current opening; When 160pls≤P i When the exhaust temperature difference in the previous fixed adjustment cycle is less than or equal to 240 pls, the decrease threshold is 6% of the current opening; when the exhaust temperature difference in the previous fixed adjustment cycle is less than or equal to 4°C, the increase threshold is 5% of the current opening; when the exhaust temperature difference in the previous fixed adjustment cycle is greater than 4°C, the increase threshold is 4% of the current opening; When P i When the temperature is less than 160pls, the exhaust temperature difference of the previous fixed adjustment cycle is less than or equal to 1°C, the decrease threshold is 6% of the current opening, the temperature increase of the previous fixed adjustment cycle is greater than 1°C, and the decrease threshold is 5% of the current opening; and the exhaust temperature difference of the previous fixed adjustment cycle is less than or equal to 1.5°C, the increase threshold is 5% of the current opening, the exhaust temperature difference of the previous fixed adjustment cycle is less than or equal to 2.5 and greater than or equal to 1.5°C, the increase threshold is 4% of the current opening, and the exhaust temperature difference of the previous fixed adjustment cycle is greater than 2.5, and the increase threshold is 3% of the current opening.

5. The adjustment method in the operation phase according to claim 3, characterized in that: In the optimization and adjustment strategy: When P i >240pls, and the opening of the electronic expansion valve is decreasing in the previous fixed adjustment cycle: If the exhaust temperature difference is less than or equal to 2°C, then in a subsequent fixed adjustment cycle, the electronic expansion valve is limited to only perform the adjustment operation of the predetermined opening increase or decrease range to open the valve; If the exhaust temperature difference is greater than 2°C and less than or equal to 4°C, the electronic expansion valve is limited to performing only the opening adjustment operation with the predetermined opening increase or decrease range being the opening valve in the subsequent two fixed adjustment cycles; If the exhaust temperature difference is greater than 4°C, the electronic expansion valve is limited to performing only the opening adjustment operation with the predetermined opening increase or decrease range being the opening valve in the subsequent three fixed adjustment cycles; When P i >240pls, and the opening of the electronic expansion valve in the previous fixed adjustment cycle is rising: The temperature increase threshold at this time is 2°C. If the exhaust temperature difference is less than or equal to 2°C, the electronic expansion valve is limited to performing only the adjustment operation of the predetermined opening increase or decrease to close the valve in the next two fixed cycles; If the exhaust gas temperature difference is greater than 2°C and less than or equal to 5°C, then in a subsequent fixed cycle, the electronic expansion valve is limited to performing only the adjustment operation of the predetermined opening increase or decrease range to open the valve; If the exhaust temperature difference is greater than 5°C, the electronic expansion valve is limited to only perform the adjustment operation of the predetermined opening increase or decrease range to open the valve in the subsequent two fixed adjustment cycles; When 160pls≤P i ≤240pls, and the opening of the electronic expansion valve is decreasing in the previous fixed adjustment cycle; If the exhaust temperature difference is less than or equal to 2°C, then in a subsequent fixed adjustment cycle, the electronic expansion valve is limited to only perform the adjustment operation of the predetermined opening increase or decrease range to open the valve; If the exhaust temperature difference is greater than 2°C and less than or equal to 3°C, the electronic expansion valve is limited to performing only the opening adjustment operation with the predetermined opening increase or decrease range being the opening valve in the subsequent two fixed adjustment cycles; If the exhaust temperature difference is greater than 3°C, the electronic expansion valve is limited to performing only the opening adjustment operation with the predetermined opening increase or decrease range being the opening valve in the subsequent three fixed adjustment cycles; When 160pls≤P i ≤240pls, and the opening of the electronic expansion valve in the previous fixed adjustment cycle is rising; The temperature increase threshold at this time is 1.5°C. If the exhaust temperature difference is less than or equal to 1.5°C, the electronic expansion valve is limited to performing only the adjustment operation of the predetermined opening increase or decrease to close the valve in the subsequent two fixed adjustment cycles; If the exhaust temperature difference is greater than 1.5°C and less than or equal to 4°C, the electronic expansion valve is limited to performing only the opening adjustment operation with the predetermined opening increase or decrease range being the opening valve in the subsequent three fixed adjustment cycles; If the exhaust temperature difference is greater than 4°C, the electronic expansion valve is limited to only perform the adjustment operation of the predetermined opening increase or decrease range to open the valve in the subsequent two fixed adjustment cycles; When P i <160pls, and the opening of the electronic expansion valve is decreasing in the previous fixed adjustment cycle: If the exhaust temperature difference is less than or equal to 1°C, the electronic expansion valve is limited to performing only the opening adjustment operation with the predetermined opening increase or decrease range being the opening valve in the subsequent two fixed adjustment cycles; If the exhaust temperature difference is greater than 1°C and less than or equal to 2.5°C, the electronic expansion valve is limited to performing only the opening adjustment operation with the predetermined opening increase or decrease range being the opening valve in the subsequent two fixed adjustment cycles; If the exhaust temperature difference is greater than 2.5°C, the electronic expansion valve is limited to performing only the opening adjustment operation with the predetermined opening increase or decrease range being the opening valve in the subsequent three fixed adjustment cycles; When P i <160pls, and the opening of the electronic expansion valve in the previous fixed adjustment cycle is rising: The temperature increase threshold at this time is 1.5°C. If the exhaust temperature difference is less than or equal to 1.5°C, the electronic expansion valve is limited to performing only the adjustment operation of the predetermined opening increase or decrease to close the valve in the subsequent two fixed adjustment cycles; If the exhaust temperature difference is greater than 1.5°C and less than or equal to 2.5°C, the electronic expansion valve is limited to performing only the opening adjustment operation with the predetermined opening increase or decrease range being the opening valve in the subsequent three fixed adjustment cycles; If the exhaust temperature difference is greater than 2.5°C, then in the subsequent two fixed adjustment cycles, if the predetermined opening increase or decrease range is the valve opening increment, the electronic expansion valve is limited to only perform the adjustment operation with the predetermined opening increase or decrease range being the valve opening.

6. The adjustment method in the operation phase according to claim 2, characterized in that: The execution condition of the superheat abnormality strategy is T dsh <Minimum exhaust superheat T dshmin , the exhaust abnormality strategy is specifically as follows: in the subsequent fixed adjustment cycle, the electronic expansion valve is limited to perform only the adjustment operation of the predetermined opening increase or decrease range of the valve closing, until T dsh ≥Minimum exhaust superheat T dshmin .

7. The adjustment method in the operation phase according to claim 2, characterized in that: The execution condition of the exhaust abnormality strategy is T d ≥105℃, the exhaust abnormality strategy is specifically as follows: obtain the first opening value of the electronic expansion valve at this time, and in the subsequent fixed adjustment cycle, limit the electronic expansion valve to only perform the adjustment operation with the predetermined opening increase or decrease amplitude being the valve opening, until the exhaust temperature drops and the exhaust temperature is less than 100℃, obtain the second opening value of the electronic expansion valve at this time, and obtain the increase difference of the second opening value minus the first opening value, and in the subsequent fixed adjustment cycle, limit the electronic expansion valve to only perform the adjustment operation with the predetermined opening increase or decrease amplitude being the valve closing, until the cumulative decrease amplitude of the electronic expansion valve at this stage is greater than or equal to 0.4 times the increase difference, take the fixed adjustment cycles of two electronic expansion valves as one actual adjustment cycle, and after three actual adjustment cycles, restore the fixed adjustment cycle.

8. The adjustment method in the operation phase according to claim 2, characterized in that: The execution condition of the fin abnormality strategy is T def <Target fin temperature at the start of defrosting + 2°C. The specific fin abnormality strategy is: in the subsequent fixed adjustment cycle, the electronic expansion valve is limited to only perform the adjustment operation with the predetermined opening increase or decrease amplitude being the valve opening, and the valve opening amplitude is 1.5 times the predetermined opening increase or decrease amplitude, until T dsh ≥Target fin temperature at the start of defrosting + 2°C.

9. A closing phase adjustment method, wherein the closing phase adjustment method applies the operating phase adjustment method according to any one of claims 2 to 7, characterized in that: When the compressor receives a shutdown command, the electronic expansion valve maintains its current opening. When the compressor is shut down to a frequency of 0 Hz, the opening of the electronic expansion valve is adjusted to 80 pls and maintained for 120 seconds. Thereafter, the opening of the electronic expansion valve is adjusted to 200 pls until the next startup adjustment command is received, and the initial opening of the electronic expansion valve is adjusted according to the initial opening adjustment method of the electronic expansion valve.

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