Control Method for Electronic Expansion Valve of Air Conditioner and Air Conditioner

Abstract

The present invention relates to a control method for an electronic expansion valve of an air conditioner and an air conditioner, belonging to the technical field of air conditioners. The electronic expansion valve has a flow inflection point and an inflection opening corresponding to the flow inflection point. The control method includes: obtaining the opening degree and the opening degree adjustment amount of the electronic expansion valve; judging whether the opening degree fluctuates near the inflection opening degree based on the opening degree and the opening degree adjustment amount; if so, controlling the opening degree according to a preset program. The control method of the present application accurately determines whether the opening degree of the electronic expansion valve fluctuates up and down near the inflection opening degree, and then executes a preset program to control the opening degree, thereby avoiding overshoot phenomena, reducing or avoiding excessive increase or decrease of the refrigerant flow rate, and reducing or avoiding the actual exhaust temperature from fluctuating above and below the set target exhaust temperature, achieving the effect of shortening the air conditioner stabilization process time, saving energy consumption, and improving the user experience.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioners, and particularly to a control method for an electronic expansion valve for an air conditioner and an air conditioner. Background Art

[0002] In some air conditioner refrigeration systems, an electronic expansion valve is provided. By adjusting its opening degree, the flow rate of the refrigerant can be adjusted, thereby changing the refrigeration and heating capacities of the refrigeration system. Generally, the refrigerant flow rate does not change at a certain fixed slope with the opening degree of the electronic expansion valve. Instead, as the opening degree increases, the refrigerant flow rate first changes with the opening degree at a smaller growth rate, and then at a preset opening degree, the growth rate suddenly becomes larger, and the refrigerant flow rate then changes with the opening degree at the increased growth rate. That is to say, a flow rate inflection point will be formed when the refrigerant flow rate changes with the opening degree. By setting the flow rate inflection point, the same change in the opening degree can result in a larger change in the refrigerant flow rate, more quickly improving the refrigeration and heating capacities of the refrigeration system, and can cope with extreme working conditions. Air conditioners usually use the PID algorithm to control the opening degree of the electronic expansion valve. When the opening degree is near the inflection point, due to the sudden change in the size of the refrigerant flow rate, the PID algorithm will produce an overshoot phenomenon, causing the refrigerant flow rate to increase or decrease excessively, resulting in the actual exhaust temperature fluctuating above and below the set target exhaust temperature, and further causing the air conditioner to be in an unsteady state for a long time. This not only wastes energy consumption but also affects the user experience. Summary of the Invention

[0003] In view of the above problems, the present invention proposes a control method for an electronic expansion valve for an air conditioner and an air conditioner that at least partially solves the above problems, aiming to solve the problem that in the prior art, when the control algorithm controls an electronic expansion valve with a flow rate inflection point, it is easy to cause the actual exhaust temperature to fluctuate above and below the set target exhaust temperature, improving the control algorithm to reduce or avoid overshoot, and then shortening the air conditioner stabilization process time, achieving the effects of saving energy consumption and improving the user experience.

[0004] Specifically, the present invention provides the following technical solutions:

[0005] A control method for an electronic expansion valve for an air conditioner, the electronic expansion valve having a flow rate inflection point and an inflection opening degree corresponding to the flow rate inflection point. The control method includes:

[0006] Obtain the opening degree and the opening degree adjustment amount of the electronic expansion valve;

[0007] Based on the opening degree and the opening degree adjustment amount, determine whether the opening degree fluctuates near the inflection opening degree;

[0008] If so, control the opening degree according to a preset program.

[0009] Optionally, determining whether the opening degree fluctuates near the inflection point opening degree based on the opening degree and the opening degree adjustment amount includes:

[0010] In response to the two opening degree adjustment amounts in two adjacent adjustment cycles changing from positive to negative, setting the opening degree in the previous adjustment cycle to the maximum preset opening degree;

[0011] In response to the two opening degree adjustment amounts in two adjacent adjustment cycles changing from negative to positive, setting the opening degree in the previous adjustment cycle to the minimum preset opening degree;

[0012] Judging whether the inflection point opening degree is between the maximum preset opening degree and the minimum preset opening degree, and if so, accumulating to obtain an accumulation result;

[0013] If the accumulation result reaches a preset value, it is determined that the opening degree fluctuates near the inflection point opening degree.

[0014] Optionally, determining whether the opening degree fluctuates near the inflection point opening degree based on the opening degree and the opening degree adjustment amount includes:

[0015] Obtaining the opening degree adjustment amount to be adjusted in the current adjustment cycle based on the PID algorithm;

[0016] In response to the opening degree adjustment amount in the previous adjustment cycle being positive and the opening degree adjustment amount to be adjusted in the current adjustment cycle being negative, setting the opening degree in the previous adjustment cycle to the maximum preset opening degree;

[0017] In response to the opening degree adjustment amount in the previous adjustment cycle being negative and the opening degree adjustment amount to be adjusted in the current adjustment cycle being positive, setting the opening degree in the previous adjustment cycle to the minimum preset opening degree;

[0018] Judging whether the inflection point opening degree is between the maximum preset opening degree and the minimum preset opening degree, and if so, accumulating to obtain an accumulation result;

[0019] If the accumulation result reaches a preset value, it is determined that the opening degree fluctuates near the inflection point opening degree.

[0020] Optionally, the preset program includes:

[0021] Obtaining the opening degree adjustment amount to be adjusted in the current adjustment cycle based on the PID algorithm;

[0022] If the opening degree adjustment amount to be adjusted is greater than 0, setting the opening degree adjustment amount in the current adjustment cycle to the preset opening degree adjustment amount; the preset opening degree adjustment amount is positive;

[0023] If the opening degree to be adjusted is less than 0, set the opening degree adjustment amount in the current adjustment period to a negative preset opening degree adjustment amount.

[0024] Optionally, the preset program further includes:

[0025] Obtain the maximum preset opening degree of the electronic expansion valve; in response to the sum of the opening degree in the previous adjustment period and the opening degree adjustment amount in the current adjustment period being greater than the maximum preset opening degree, update the opening degree in the previous adjustment period to the difference between the maximum preset opening degree and the preset opening degree adjustment amount.

[0026] Optionally, the preset program further includes:

[0027] Obtain the minimum preset opening degree of the electronic expansion valve; in response to the sum of the opening degree in the previous adjustment period and the opening degree adjustment amount in the current adjustment period being less than the minimum preset opening degree, update the opening degree in the previous adjustment period to the sum of the minimum preset opening degree and the preset opening degree adjustment amount.

[0028] Optionally, for the step of setting the opening degree in the previous adjustment period to the maximum preset opening degree in response to the two opening degree adjustment amounts in two adjacent adjustment periods changing from positive to negative, it further includes:

[0029] In response to the absolute value of the sum of the two opening degree adjustment amounts being less than the absolute value of the opening degree adjustment amount in the previous adjustment period, set the opening degree in the previous period to the maximum preset opening degree.

[0030] Optionally, for the step of setting the opening degree in the previous adjustment period to the minimum preset opening degree in response to the two opening degree adjustment amounts in two adjacent adjustment periods changing from negative to positive, it further includes:

[0031] In response to the absolute value of the sum of the two opening degree adjustment amounts being less than the absolute value of the opening degree adjustment amount in the previous adjustment period, set the opening degree in the previous period to the minimum preset opening degree.

[0032] Optionally, for the step of determining whether the inflection point opening degree is between the maximum preset opening degree and the minimum preset opening degree, and if so, accumulating to obtain an accumulation result, it further includes:

[0033] Accumulate once every time the maximum preset opening degree or the minimum preset opening degree is updated; or

[0034] Accumulate once every time the positive and negative signs of the two opening degree adjustment amounts in two adjacent adjustment periods change.

[0035] Optionally, if the cumulative result reaches a preset value, determining that the opening degree fluctuates near the inflection point opening degree includes: the preset value is three times.

[0036] Optionally, if the cumulative result reaches a preset value, determining that the opening degree fluctuates near the inflection point opening degree includes: reaching three times in cumulative within three consecutive adjustment cycles.

[0037] Optionally, if the cumulative result reaches a preset value, determining that the opening degree fluctuates near the inflection point opening degree includes: reaching three times in cumulative within five consecutive adjustment cycles.

[0038] Optionally, the control method further includes:

[0039] In response to a change in one or more of the set exhaust temperature, the compressor operating frequency, and the ambient temperature, re-acquire the opening degree and the opening degree adjustment amount of the electronic expansion valve, and determine whether the opening degree fluctuates near the inflection point opening degree based on the opening degree and the opening degree adjustment amount. If so, control the opening degree according to a preset program.

[0040] On the other hand, the present application also provides an air conditioner, which includes a compressor, a condenser, and an evaporator, and further includes an electronic expansion valve with a flow inflection point, a memory, a processor, and a machine-executable program stored on the memory and running on the processor. When the processor executes the machine-executable program, the control method for the electronic expansion valve for an air conditioner as described above is implemented.

[0041] The control method for the electronic expansion valve for an air conditioner provided by the present application determines whether the opening degree of the electronic expansion valve fluctuates near the inflection point opening degree by obtaining and based on the opening degree and the opening degree adjustment amount of the electronic expansion valve. If so, if the opening degree of the electronic expansion valve continues to be controlled according to algorithms such as the PID algorithm or the fuzzy algorithm, overshoot may occur, causing the air conditioner to enter an unstable state, not only wasting energy but also affecting the user experience. After determining whether the opening degree of the electronic expansion valve fluctuates near the inflection point opening degree, the present application does not continue to control the opening degree of the electronic expansion valve according to the PID algorithm or the fuzzy algorithm, but controls it according to a preset program, thereby avoiding the overshoot phenomenon, reducing or avoiding excessive increase or decrease of the refrigerant flow rate, and reducing or avoiding the actual exhaust temperature from fluctuating above and below the set target exhaust temperature, achieving the effect of shortening the air conditioner's stabilization process time, saving energy consumption, and improving the user experience.

[0042] Further, the control method for the electronic expansion valve of an air conditioner provided by the present application also provides a method for determining whether the opening degree of the electronic expansion valve fluctuates near the inflection point opening degree. By the positive and negative changes of the two opening degree adjustment amounts in two adjacent adjustment cycles, a maximum preset opening degree and a minimum preset opening degree are set. According to whether the inflection point opening degree is between the maximum preset opening degree and the minimum preset opening degree, a cumulative result is obtained by accumulation, and according to whether the cumulative result reaches a preset value, it is determined whether the opening degree fluctuates near the inflection point opening degree. This method can perform real-time self-adjustment according to various working conditions and various actual usage situations, and can accurately determine whether the opening degree of the electronic expansion valve fluctuates near the inflection point opening degree.

[0043] From the following detailed description of the specific embodiments of the present invention in conjunction with the accompanying drawings, those skilled in the art will become more clearly aware of the above and other objects, advantages, and features of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Some specific embodiments of the present invention will be described in detail hereinafter with reference to the accompanying drawings in an illustrative but not restrictive manner. The same reference numerals in the drawings denote the same or similar components or parts. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0045] Figure 1 is the pulse number - flow diagram of an electronic expansion valve of a certain specification in the prior art;

[0046] Figure 2 is a schematic flow chart of the control method of the electronic expansion valve according to an embodiment of the present invention;

[0047] Figure 3 is a schematic flow chart for determining whether the opening degree fluctuates up and down near the inflection point opening degree corresponding to the flow inflection point in the control method according to an embodiment of the present invention;

[0048] Figure 4 is a schematic flow chart for determining whether the opening degree fluctuates up and down near the inflection point opening degree corresponding to the flow inflection point in the control method according to another embodiment of the present invention;

[0049] Figure 5 is a schematic flow chart for controlling the opening degree according to a preset program in the control method according to an embodiment of the present invention;

[0050] Figure 6 is a schematic flow chart of the control method according to another embodiment of the present invention;

[0051] Figure 7 is a schematic flow chart of the control method according to still another embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0052] The following refers toFigures 1 to 7 The control method for an electronic expansion valve for an air conditioner and an air conditioner according to embodiments of the present invention will be described. In the description of the embodiments of the present invention, it should be understood that the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of such features, that is, include one or more of such features. In the description of the present invention, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise specifically defined. When a certain feature "includes or contains" a certain or certain features it covers, unless otherwise specifically described, this indicates that other features are not excluded and other features may be further included.

[0053] Unless otherwise clearly specified and defined, terms such as "arranged", "installed", "connected", "coupled", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements or the interaction relationship between two elements, unless otherwise clearly defined. Those of ordinary skill in the art should be able to understand the specific meanings of the above terms in the present invention according to specific circumstances.

[0054] In addition, in the description of the embodiments of the present invention, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but in contact through additional features therebetween. That is, in the description of the embodiments of the present invention, the first feature being "above", "over" and "on" the second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature has a higher horizontal height than the second feature. The first feature being "below", "beneath" or "under" the second feature may be that the first feature is directly below or obliquely below the second feature, or simply indicating that the first feature has a lower horizontal height than the second feature.

[0055] In the description of the embodiments of the present invention, descriptions with reference to terms such as "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples.

[0056] As Figure 1The figure shows the pulse number - flow rate graph of an electronic expansion valve with a flow rate inflection point of a certain specification in the prior art. Figure 1 In the graph, the abscissa is the pulse number, and the ordinate is the refrigerant flow rate. The opening range of the electronic expansion valve is from 0 to 500 pulses, or 0 to 500 steps. Generally speaking, the pulse number is proportional to the opening. To cope with extreme working conditions, the electronic expansion valve is provided with a flow rate inflection point at a pulse number of 350. When the pulse number is between 0 and 350, the flow rate increases with the pulse number at a relatively small growth rate. When the pulse number is between 350 and 500, the flow rate increases with the pulse number at a relatively large growth rate.

[0057] In the prior art, the PID algorithm or the fuzzy algorithm is usually adopted to control the opening of the electronic expansion valve based on the current exhaust temperature and the set exhaust temperature, so as to adjust the refrigerant flow rate and thus change the refrigeration and heating capacities of the refrigeration system. The PID algorithm consists of a P proportional term, an I integral term, and a D differential term. The PID algorithm can be set to run once per operating cycle of the refrigeration cycle system, or can be set to run once at a preset time interval, such as 1 minute. In this application, one run of the algorithm is defined as one adjustment cycle. When running the PID algorithm, it is necessary to first obtain the current exhaust temperature and the set exhaust temperature, calculate the proportional term according to the temperature difference between the current exhaust temperature and the set exhaust temperature, and use the integral term and the differential term of the temperature difference of the corresponding data in several previous cycles as weighting terms to obtain a value of the opening to be adjusted in the current adjustment cycle. For example, the opening in the previous adjustment cycle is V0. In the current adjustment cycle, first obtain the value of V0 and the current exhaust temperature. After calculation by the PID algorithm, it will give the value of the opening to be adjusted △V in the current adjustment cycle. Next, perform the execution step to control the adjustment △V of the electronic expansion valve, so as to obtain the opening V = V0 + △V in this adjustment cycle. Among them, when △V is positive, V is greater than V0, and when △V is negative, V is less than V0.

[0058] When the opening of the electronic expansion valve is near the inflection point opening, due to the sudden change in the refrigerant flow rate, the PID algorithm will produce an overshoot phenomenon, that is, △V is too large or too small, resulting in the refrigerant flow rate increasing or decreasing excessively, causing the actual exhaust temperature to fluctuate above and below the set target exhaust temperature, and further causing the air conditioner to be in a non - steady state process for a long time. This not only wastes energy consumption but also affects the user experience.

[0059] Figure 2 is a schematic flowchart of the control method of the electronic expansion valve according to an embodiment of the present invention, and in combination with Figures 1 - 7 the present invention provides a control method for an electronic expansion valve used in an air conditioner, which is used to optimize the algorithm for adjusting the opening of the electronic expansion valve with a flow rate inflection point. The control method includes:

[0060] S1 Obtain the opening and the opening adjustment amount of the electronic expansion valve;

[0061] S2 determines whether the opening degree fluctuates near the inflection point opening degree based on the opening degree and the opening degree adjustment amount;

[0062] S3 If so, control the opening degree according to a preset program.

[0063] In this embodiment, in S1, the opening degree of the historical adjustment period and the opening degree adjustment amount of the historical adjustment period can be obtained, and the opening degree to be adjusted calculated by the existing control algorithm in the current adjustment period can also be obtained. For example, obtain the opening degree V0 and the opening degree adjustment amount △V0 of the previous adjustment period, and the opening degree V -1 and the opening degree adjustment amount △V -1 , etc., where V0 = V -1 +△V0. In S3, the preset program is different from the PID algorithm or the fuzzy algorithm, and can reduce or avoid the overshoot phenomenon of the opening degree.

[0064] In this embodiment, by obtaining and based on the opening degree and the opening degree adjustment amount of several historical adjustment periods, it can be determined whether the opening degree of the electronic expansion valve fluctuates near the inflection point opening degree. If so, if the opening degree of the electronic expansion valve continues to be controlled according to the original algorithms such as the PID algorithm or the fuzzy algorithm, overshoot may occur, causing the air conditioner to enter an unstable state, not only wasting energy but also affecting the user experience. After determining whether the opening degree of the electronic expansion valve fluctuates near the inflection point opening degree, this application does not continue to control the opening degree of the electronic expansion valve according to the PID algorithm or the fuzzy algorithm, but controls it according to a preset program, thereby avoiding the overshoot phenomenon, reducing or avoiding excessive increase or decrease of the refrigerant flow rate, and reducing or avoiding the actual exhaust temperature fluctuating above and below the set target exhaust temperature, achieving the effect of shortening the air conditioner stabilization process time, saving energy consumption, and improving the user experience.

[0065] In some embodiments of the control method of the electronic expansion valve of the present invention, in step S2, the control method includes:

[0066] S211 In response to the two opening degree adjustment amounts of two adjacent adjustment periods changing from positive to negative, set the opening degree of the previous adjustment period to the maximum preset opening degree;

[0067] S212 In response to the two opening degree adjustment amounts of two adjacent adjustment periods changing from negative to positive, set the opening degree of the previous adjustment period to the minimum preset opening degree;

[0068] S213 Determine whether the inflection point opening degree is between the maximum preset opening degree and the minimum preset opening degree. If so, perform accumulation to obtain an accumulation result;

[0069] S214 If the accumulation result reaches a preset value, determine that the opening degree fluctuates near the inflection point opening degree.

[0070] Generally speaking, to determine whether the opening degree of an electronic expansion valve fluctuates near the inflection point opening degree, it is mainly by obtaining in advance the operating parameters of a specific model of air conditioner under different working conditions, especially the operating parameters when the opening degree of the electronic expansion valve fluctuates near the inflection point opening degree, and presetting them into the control program. In this way, during actual use, when it is detected that these operating parameters conform to the preset characteristics, it can be determined that the opening degree of the electronic expansion valve fluctuates near the inflection point opening degree. However, this method has some drawbacks. For example, for air conditioners of the same model, the amount of refrigerant may be different, the aging degree of the refrigerant pipeline may be different, and there may also be differences in the actual performance of the compressor, evaporator, and condenser. Therefore, the preset control program may produce misjudgments.

[0071] In this embodiment, the control method for determining whether the opening degree of the electronic expansion valve fluctuates near the inflection point opening degree can be adjusted in real time and self - adaptively according to various working conditions and actual usage situations, and can accurately determine whether the opening degree of the electronic expansion valve fluctuates near the inflection point opening degree. For example, after obtaining the opening degree V0, the opening degree adjustment amount △V0 in the previous adjustment cycle and the opening degree adjustment amount △V in the current adjustment cycle, judge the values of △V0 and △V. If △V0 is positive and △V is negative, it indicates that an inflection point appears at V0, or in other words, an overshoot phenomenon may occur at V0. To reduce or avoid the overshoot phenomenon from occurring again, set V0 as the maximum preset opening degree dynamically to avoid overshooting again in subsequent cycles. If △V0 is negative and △V is positive, it indicates that an inflection point appears at V0, or in other words, an overshoot phenomenon occurs at V0. To reduce or avoid the overshoot phenomenon from occurring again, set V0 as the minimum preset opening degree dynamically to avoid overshooting again in subsequent cycles. It should be noted that the maximum preset opening degree and the minimum preset opening degree are only used under the current set exhaust gas temperature, compressor operating frequency, and ambient temperature conditions. When these conditions change, the maximum preset opening degree and the minimum preset opening degree need to be changed dynamically according to the corresponding strategy.

[0072] In this embodiment, next, judge the inflection point opening degree V x whether it is between the maximum preset opening degree and the minimum preset opening degree. If so, it means that the opening degree of the electronic expansion valve is at least near V x in two adjustment cycles. However, this still cannot determine that the opening degree of the electronic expansion valve fluctuates near the inflection point opening degree. Only when there are multiple inflection points near the inflection point opening degree within three or more adjustment cycles, that is to say, it is necessary to accumulate multiple times to obtain a preset cumulative result, can it be accurately determined that the opening degree of the electronic expansion valve fluctuates near the inflection point opening degree.

[0073] The preset value of the cumulative result can be set to three, four, five, etc., and it needs to be determined according to the actual situation. It should be noted that the larger the preset value, the more likely it is to more accurately determine that the opening degree of the electronic expansion valve fluctuates near the inflection point opening degree. However, it will also increase the unstable operation time of the system. The smaller the preset value, the more likely it is to timely detect that the opening degree of the electronic expansion valve fluctuates near the inflection point opening degree, and then timely execute the preset program to shorten the unstable operation time of the system. However, it will also increase misjudgment and reduce the accuracy of judging whether the opening degree of the electronic expansion valve fluctuates near the inflection point opening degree.

[0074] In some embodiments of the control method of the electronic expansion valve of the present invention, the control method in step S2 includes:

[0075] S221 Obtain the opening degree to be adjusted in the current adjustment period based on the PID algorithm;

[0076] S222 In response to the opening degree adjustment amount in the previous adjustment period being positive and the opening degree to be adjusted in the current adjustment period being negative, set the opening degree in the previous adjustment period to the maximum preset opening degree;

[0077] S223 In response to the opening degree adjustment amount in the previous adjustment period being negative and the opening degree to be adjusted in the current adjustment period being positive, set the opening degree in the previous adjustment period to the minimum preset opening degree;

[0078] S224 Determine whether the inflection point opening degree is between the maximum preset opening degree and the minimum preset opening degree. If so, perform accumulation to obtain a cumulative result;

[0079] S225 If the cumulative result reaches the preset value, determine that the opening degree fluctuates near the inflection point opening degree.

[0080] The difference between this embodiment and the previous embodiment is that the opening degree adjustment amount is replaced by the opening degree to be adjusted. Their positive and negative signs are the same, but the absolute values may be the same or different. In the prior art, in the PID algorithm, the opening degree adjustment amount is the actually executed amount, and the opening degree to be adjusted is the amount calculated by the algorithm. In the PID algorithm control, the opening degree adjustment amount is equal to the opening degree to be adjusted. In the embodiment of the present invention, if it is determined that the opening degree of the electronic expansion valve fluctuates near the inflection point opening degree, a preset program will be executed. That is to say, the opening degree adjustment amount may not be equal to the opening degree to be adjusted. Since in the method of judging whether the opening degree of the electronic expansion valve fluctuates near the inflection point opening degree, the step of accumulating to obtain a cumulative result is adopted. Therefore, in this embodiment, replacing the opening degree adjustment amount with the opening degree to be adjusted can timely accumulate the result.

[0081] For example, the preset value is accumulated four times. When entering the current adjustment cycle, the preset value has been accumulated to three. According to the PID algorithm, the sign of the opening adjustment amount to be adjusted in the current adjustment cycle is opposite to that of the opening adjustment amount in the previous adjustment cycle. According to the previous embodiment, the current cycle will be controlled and executed by the PID algorithm, and the preset value will be accumulated to four. When entering the next cycle, step S3 will be triggered. According to this embodiment, since only the opening adjustment amount to be adjusted is obtained and not yet executed, the system can accumulate the preset value to four times before execution, thereby triggering step S3. That is to say, S3 is directly executed in the current cycle. Compared with the previous embodiment, this embodiment can execute S3 one adjustment cycle earlier. That is to say, it can determine one adjustment cycle earlier that the opening of the electronic expansion valve fluctuates near the inflection point opening, shortening the time of unstable operation of the system.

[0082] In some embodiments of the control method of the electronic expansion valve of the present invention, the control method in step S3 includes:

[0083] S311 Obtain the opening adjustment amount to be adjusted in the current adjustment cycle based on the PID algorithm;

[0084] S312 If the opening adjustment amount to be adjusted is greater than 0, set the opening adjustment amount in the current adjustment cycle to the preset opening adjustment amount; the preset opening adjustment amount is positive;

[0085] S313 If the opening adjustment amount to be adjusted is less than 0, set the opening adjustment amount in the current adjustment cycle to the negative preset opening adjustment amount.

[0086] In this embodiment, the preset opening adjustment amount can be the minimum adjustable opening. That is to say, the preset opening adjustment amount is the opening corresponding to 1 pulse. In some other embodiments of the present invention, the preset opening adjustment amount can be greater than the minimum adjustable opening and is an integer multiple of the minimum adjustable opening. For example, the opening corresponding to 2 pulses. It should be noted that the smaller the preset opening adjustment amount, the easier it is to avoid overshoot. That is, it may take several more adjustment cycles to enter the stable state due to the smaller adjustment amount. The larger the preset opening adjustment amount, although it may enter the stable state in fewer cycles, it is also more likely to produce overshoot. Therefore, when applying this control method, the value of the preset opening adjustment amount should be set according to the actual situation.

[0087] In this application, the preset opening adjustment amount is used as the basic adjustment unit, and its value is positive. For the sake of simplicity of description, in the following formulas, the preset opening adjustment amount will be directly marked as "1". That is, when △V = 1, it means that the opening adjustment amount to be adjusted increases by 1 preset opening adjustment amount. When △V = -1, it means that the opening adjustment amount to be adjusted decreases by 1 preset opening adjustment amount.

[0088] In this embodiment, when it is determined that the opening degree of the electronic expansion valve fluctuates up and down near the inflection opening degree corresponding to the flow inflection point, it indicates that the system is in an unstable state, and this unstable state may be due to overshoot in the PID algorithm, that is, the △V controlled by the control algorithm is too large or too small. At this time, it is necessary to optimize the control algorithm, reduce the absolute value of △V, and adjust the opening degree in units of the preset opening adjustment amount. In this way, overshoot is reduced or avoided.

[0089] In this embodiment, the control program of the PID algorithm is optimized. The opening degree adjustment amount to be adjusted calculated by the PID algorithm only provides a positive or negative direction reference, or rather, the positive and negative values of the opening degree adjustment amount, while the absolute value of the opening degree adjustment amount is given by the preset opening degree adjustment amount.

[0090] In other embodiments of the control method of the electronic expansion valve of the present invention, there may be multiple preset opening degree adjustment amounts. The opening degree adjustment amount to be adjusted calculated by the PID algorithm not only provides a positive or negative direction reference but also provides a reference for the size. The preset program can select the corresponding value of the preset opening degree adjustment amount according to the size of the absolute value of the opening degree adjustment amount to be adjusted and set it as the executed opening degree adjustment amount.

[0091] In some embodiments of the control method of the electronic expansion valve of the present invention, the control method in step S3 includes:

[0092] S321 Obtain the maximum preset opening degree of the electronic expansion valve;

[0093] S322 In response to the sum of the opening degree in the previous adjustment cycle and the opening degree adjustment amount in the current adjustment cycle being greater than the maximum preset opening degree, update the opening degree in the previous adjustment cycle to the difference between the maximum preset opening degree and the preset opening degree adjustment amount.

[0094] The maximum preset opening degree can be the actual maximum opening degree of the electronic expansion valve, such as Figure 1 the opening degree corresponding to the pulse number of 500 shown in, or it can also be the preset maximum opening degree, for example, the opening degree corresponding to the preset pulse number of 480. On the other hand, the maximum preset opening degree can also be dynamic, and its strategy needs to be set in advance. For example, under certain specific set exhaust gas temperature, compressor operating frequency, and ambient temperature conditions, the maximum preset opening degree can be set to the opening degree corresponding to the pulse number of 370, etc. Particularly, under certain specific set exhaust gas temperature, compressor operating frequency, and ambient temperature conditions, within different cycles, the value of the maximum preset opening degree can also be dynamically set according to the preset strategy.

[0095] In this embodiment, to prevent the adjusted opening degree V = V0 + △V in this cycle from being greater than the maximum preset opening degree, set the current opening degree to the difference between the current opening degree and the preset opening degree adjustment amount, that is, V0 = V - 1. In this way, after adjusting the opening degree in this cycle, V = V0 + 1 = V, and it will not be greater than the maximum preset opening degree.

[0096] In some embodiments of the control method of the electronic expansion valve of the present invention, the control method in step S3 includes:

[0097] S331 Obtain the minimum preset opening degree of the electronic expansion valve;

[0098] S332 In response to the sum of the opening degree in the previous adjustment cycle and the opening degree adjustment amount in the current adjustment cycle being less than the minimum preset opening degree, update the opening degree in the previous adjustment cycle to the sum of the minimum preset opening degree and the preset opening degree adjustment amount.

[0099] The minimum preset opening degree can be the actual minimum opening degree of the electronic expansion valve. For example, Figure 1 the opening degree corresponding to the pulse number 0 shown in

[0100] or can be a preset minimum opening degree. For example, the opening degree corresponding to the preset pulse number of 20. On the other hand, the minimum preset opening degree can also be dynamic and its strategy needs to be set in advance. For example, under certain specific set exhaust gas temperature, compressor operating frequency, and ambient temperature conditions, the minimum preset opening degree can be set to the opening degree corresponding to the pulse number of 330, etc. In particular, under certain specific set exhaust gas temperature, compressor operating frequency, and ambient temperature conditions, within different cycles, the value of the minimum preset opening degree can also be dynamically set according to the preset strategy.

[0101] In some embodiments of the control method of the electronic expansion valve of the present invention, the control method of step S211 further includes:

[0102] S211a In response to the absolute value of the sum of two opening degree adjustment amounts being less than the absolute value of the opening degree adjustment amount in the previous adjustment cycle, set the opening degree in the previous cycle to the maximum preset opening degree.

[0103] Generally speaking, when the opening degree fluctuates up and down near the inflection point opening degree corresponding to the flow inflection point, the fluctuation amplitude will gradually become smaller. In this embodiment, the judgment condition is further narrowed. When △V0 is positive and △V is negative, it is also required that |△V0 + △V| ≤ |△V0|, that is, |△V| ≤ 2|△V0|. In this way, it is further accurately confirmed whether the inflection point is the inflection point of the upper pole point of the fluctuation.

[0104] In some embodiments of the control method of the electronic expansion valve of the present invention, the control method of step S212 further includes:

[0105] If the absolute value of the sum of the two opening adjustment amounts is less than the absolute value of the opening adjustment amount in the previous adjustment period, S211b sets the opening in the previous period to the minimum preset opening.

[0106] In this embodiment, the judgment condition is further narrowed. When △V0 is negative and △V is positive, it is also required that |△V0 + △V| ≤ |△V0|, that is, |△V| ≤ 2|△V0|. In this way, it is further accurately confirmed whether the inflection point is the inflection point of the lower pole of the fluctuation.

[0107] In some embodiments of the control method of the electronic expansion valve of the present invention, the control method of step S213 or step S223 further includes:

[0108] Each time the maximum preset opening or the minimum preset opening is updated, it is accumulated once.

[0109] In this embodiment, the maximum preset opening and the minimum preset opening are each given an initial value in the first adjustment period, and in subsequent adjustment periods, they are dynamically adjusted at any time. In each adjustment period, if the maximum preset opening or the minimum preset opening is updated, and within this adjustment period, V x is between the corresponding maximum preset opening and the minimum preset opening, it is accumulated once. In particular, for example, in the current adjustment period, when the opening in the previous adjustment period is set to the maximum preset opening, the value of the maximum preset opening may remain unchanged, that is, the value of the opening in the previous adjustment period is equal to the maximum preset opening in the previous adjustment period. At this time, it should also be accumulated once.

[0110] In some embodiments of the control method of the electronic expansion valve of the present invention, the control method of step S213 or step S223 further includes:

[0111] Each time the positive and negative signs of the two opening adjustment amounts in two adjacent adjustment periods change, it is accumulated once.

[0112] In this embodiment, in the current adjustment period, if the sign of the opening adjustment amount in the previous adjustment period is different from the sign of the opening adjustment amount (or the opening to be adjusted amount) in this period, and within this adjustment period, Vx is between the corresponding maximum preset opening and the minimum preset opening, it is accumulated once.

[0113] In some embodiments of the control method of the electronic expansion valve of the present invention, in step S214 or step S225, the preset value is three times.

[0114] In some embodiments of the control method of the electronic expansion valve of the present invention, in step S214 or step S225, the preset value accumulates to three times within three consecutive adjustment periods.

[0115] In some embodiments of the control method of the electronic expansion valve of the present invention, in step S214 or step S225, the preset value accumulates to three times within five consecutive adjustment cycles.

[0116] In some embodiments of the control method of the electronic expansion valve of the present invention, the control method further includes:

[0117] In response to a change in one or more of the set exhaust temperature, the compressor operating frequency, and the ambient temperature, the opening degree and the opening degree adjustment amount of the electronic expansion valve are re-acquired to determine whether the opening degree fluctuates near the inflection point opening degree based on the opening degree and the opening degree adjustment amount. If so, the opening degree is controlled according to a preset program.

[0118] In this embodiment, when one or more of the set exhaust temperature, the compressor operating frequency, and the ambient temperature change relative to the previous adjustment cycle, it indicates that the set state or working condition has changed. The electronic expansion valve will inevitably be in an unstable state, and it is necessary to re-preset the maximum preset opening degree and the minimum preset opening degree of the electronic expansion valve and execute the control algorithm according to the preset strategy.

[0119] In some embodiments of the control method of the electronic expansion valve of the present invention, the control method includes:

[0120] S501 Set the minimum preset opening degree V min to 0, set the maximum preset opening degree V max to 480, and set the constant variable a = 0;

[0121] S502 Obtain the current actual exhaust temperature T1 and the set exhaust temperature T0;

[0122] S503 If the set exhaust temperature T0, the compressor operating frequency, and the ambient temperature remain unchanged, then execute S504, otherwise return to execute S501;

[0123] S504 Obtain the current opening degree V0 and the adjusted opening degree ΔV0 of the previous adjustment cycle;

[0124] S505 Obtain the opening degree adjustment amount ΔV to be adjusted in the current adjustment cycle through the PID algorithm;

[0125] S506 Determine whether a is greater than 3. If so, execute S512. If not, execute S507;

[0126] S507 Adjust the opening degree to be set as V = V0 + ΔV;

[0127] S508 In response to ΔV0 > 0 and |ΔV 0+ ΔV| ≤ |ΔV0|, then set the maximum preset opening degree V max = V0, and then execute S510;

[0128] S509 responds to △V0 < 0 and |△V 0+ △V| ≤ |△V0|; then set the minimum preset opening V min = V0, and then execute S510;

[0129] S510 determines whether the inflection point opening V x > V min , and Vx < V max , if not, return to execute S501;

[0130] S511 If so, set the constant variable a = a + 1 and return to execute S501;

[0131] S512 responds to the opening to-be-adjusted amount △V < 0, then set △V = -1; responds to the opening to-be-adjusted amount △V > 0, then set △V = 1;

[0132] S513 responds to the adjusted opening V > V max , then set V0 = V max - 1; responds to the adjusted opening V < V min , then set V0 = V min + 1; execute S507.

[0133] In this embodiment, the constant variable a can be used to determine whether the opening of the electronic expansion valve fluctuates near the inflection point. When a is greater than 3, it can be more accurately determined that the opening of the electronic expansion valve fluctuates near the inflection point.

[0134] In some embodiments of the control method of the electronic expansion valve of the present invention, the control method includes:

[0135] S601 sets the minimum preset opening V min to 0, sets the maximum preset opening V max to 480, and sets the constant variable a = 0;

[0136] S602 obtains the current actual exhaust temperature T1 and the set exhaust temperature T0;

[0137] S603 If the set exhaust temperature T0, the compressor operating frequency, and the ambient temperature remain unchanged, then execute S604, otherwise return to execute S601;

[0138] S604 obtains the current opening V0 and the adjusted opening △V0 of the previous adjustment cycle;

[0139] S605 obtains the opening to-be-adjusted amount △V of the current adjustment cycle through the PID algorithm;

[0140] S606 responds to △V0 > 0 and |△V 0+ △V| ≤ |△V0|, then set the maximum preset opening Vmax = V0, then execute S608;

[0141] S607 responds to △V0 < 0 and |△V 0+ |△V| ≤ |△V0|; then set the minimum preset opening V min = V0, then execute S608;

[0142] S608 determines whether the inflection point opening V x > V min , and Vx < V max , if not, execute S610; if so, execute S609;

[0143] S609 sets the constant variable a = a + 1, then executes S610;

[0144] S610 determines whether a is greater than 3, if so, execute S611, if not, execute S613;

[0145] S611 responds to the opening adjustment amount △V < 0, then sets △V = -1; responds to the opening adjustment amount △V > 0, then sets △V = 1;

[0146] S612 responds to the adjusted opening V > V max , then sets V0 = V max - 1; responds to the adjusted opening V < V min , then sets V0 = V min + 1; executes S613;

[0147] S613 sets the adjusted opening to V = V0 + △V and returns to execute S601.

[0148] Compared with the previous embodiment, in this embodiment, replacing an opening adjustment amount with an opening adjustment amount to be adjusted can improve the determination that the opening of the electronic expansion valve fluctuates near the inflection point in one cycle.

[0149] In some embodiments of the air conditioner of the present invention, the air conditioner includes a compressor, a condenser and an evaporator, and further includes an electronic expansion valve with a flow inflection point, a memory, a processor, and a machine-executable program stored on the memory and running on the processor, and when the processor executes the machine-executable program, it implements the above control method for the electronic expansion valve of the air conditioner.

[0150] At this point, those skilled in the art should recognize that although multiple exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications that conform to the principles of the present invention can still be directly determined or derived from the content disclosed in the present invention without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should be understood and determined to cover all these other variations or modifications.

Claims

1. A control method for an electronic expansion valve of an air conditioner, characterized in that, The electronic expansion valve has a flow inflection point and an inflection opening corresponding to the flow inflection point; The control method includes: Obtaining the opening degree and the opening adjustment amount of the electronic expansion valve; Judging whether the opening degree fluctuates near the inflection opening based on the opening degree and the opening adjustment amount; If so, controlling the opening degree according to a preset program; Wherein, the judging whether the opening degree fluctuates near the inflection opening based on the opening degree and the opening adjustment amount includes: In response to the two opening adjustment amounts in two adjacent adjustment cycles changing from positive to negative, setting the opening degree in the previous adjustment cycle to the maximum preset opening degree; In response to the two opening adjustment amounts in two adjacent adjustment cycles changing from negative to positive, setting the opening degree in the previous adjustment cycle to the minimum preset opening degree; Judging whether the inflection opening is between the maximum preset opening degree and the minimum preset opening degree, and if so, accumulating to obtain an accumulation result; If the accumulation result reaches a preset value, it is determined that the opening degree fluctuates near the inflection opening.

2. A control method for an electronic expansion valve used in an air conditioner, characterized in that, The electronic expansion valve has a flow inflection point and an inflection opening corresponding to the flow inflection point; The control method includes: Obtaining the opening degree and the opening adjustment amount of the electronic expansion valve; Judging whether the opening degree fluctuates near the inflection opening based on the opening degree and the opening adjustment amount; If so, controlling the opening degree according to a preset program; Wherein, the judging whether the opening degree fluctuates near the inflection opening based on the opening degree and the opening adjustment amount includes: Obtaining the opening degree to be adjusted in the current adjustment cycle based on the PID algorithm; In response to the opening adjustment amount in the previous adjustment cycle being positive and the opening degree to be adjusted in the current adjustment cycle being negative, setting the opening degree in the previous adjustment cycle to the maximum preset opening degree; In response to the opening adjustment amount in the previous adjustment cycle being negative and the opening degree to be adjusted in the current adjustment cycle being positive, setting the opening degree in the previous adjustment cycle to the minimum preset opening degree; Judging whether the inflection opening is between the maximum preset opening degree and the minimum preset opening degree, and if so, accumulating to obtain an accumulation result; If the accumulation result reaches a preset value, it is determined that the opening degree fluctuates near the inflection opening.

3. The control method according to claim 1 or 2, characterized in that, The judging whether the inflection opening is between the maximum preset opening degree and the minimum preset opening degree, and if so, accumulating to obtain an accumulation result, further includes: Accumulating once every time the maximum preset opening degree or the minimum preset opening degree is updated; or Accumulating once every time the positive and negative signs of the two opening adjustment amounts in two adjacent adjustment cycles change.

4. The control method according to claim 1 or 2, characterized in that, The preset program includes: Obtaining the opening degree to be adjusted in the current adjustment cycle based on the PID algorithm; If the opening degree to be adjusted is greater than 0, setting the opening adjustment amount in the current adjustment cycle to the preset opening adjustment amount; the preset opening adjustment amount is positive; If the opening degree to be adjusted is less than 0, setting the opening adjustment amount in the current adjustment cycle to the negative preset opening adjustment amount.

5. The control method according to claim 4, wherein The preset program further includes: Obtain the maximum preset opening degree of the electronic expansion valve; in response to the sum of the opening degree in the previous adjustment period and the opening degree adjustment amount in the current adjustment period being greater than the maximum preset opening degree, update the opening degree in the previous adjustment period to the difference between the maximum preset opening degree and the preset opening degree adjustment amount; and / or Obtain the minimum preset opening degree of the electronic expansion valve; in response to the sum of the opening degree in the previous adjustment period and the opening degree adjustment amount in the current adjustment period being less than the minimum preset opening degree, update the opening degree in the previous adjustment period to the sum of the minimum preset opening degree and the preset opening degree adjustment amount.

6. The control method according to claim 1, wherein The step of setting the opening degree in the previous adjustment period to the maximum preset opening degree in response to the two opening degree adjustment amounts in two adjacent adjustment periods changing from positive to negative further includes:[[]] In response to the absolute value of the sum of the two opening degree adjustment amounts being less than the absolute value of the opening degree adjustment amount in the previous adjustment period, set the opening degree in the previous period to the maximum preset opening degree; and / or The step of setting the opening degree in the previous adjustment period to the minimum preset opening degree in response to the two opening degree adjustment amounts in two adjacent adjustment periods changing from negative to positive further includes:[[]] In response to the absolute value of the sum of the two opening degree adjustment amounts being less than the absolute value of the opening degree adjustment amount in the previous adjustment period, set the opening degree in the previous period to the minimum preset opening degree.

7. The control method according to claim 1 or 2, wherein The step of determining that the opening degree fluctuates near the inflection point opening degree if the cumulative result reaches a preset value includes:[[]] The preset value is reaching three times cumulatively; or Reaching three times cumulatively within three consecutive adjustment periods; or Reaching three times cumulatively within five consecutive adjustment periods.

8. The control method according to claim 1 or 2, characterized in that, The control method further includes:[[]] In response to a change in one or more of the set exhaust temperature, the compressor operating frequency, and the ambient temperature, re-obtain the opening degree and the opening degree adjustment amount of the electronic expansion valve, and based on the opening degree and the opening degree adjustment amount, determine whether the opening degree fluctuates near the inflection point opening degree. If so, control the opening degree according to a preset program.

9. An air conditioner, comprising a compressor, a condenser and an evaporator, characterized in that, It further includes an electronic expansion valve with a flow inflection point, a memory, a processor, and a machine-executable program stored on the memory and running on the processor. When the processor executes the machine-executable program, it implements the control method for the electronic expansion valve for an air conditioner according to any one of claims 1 to 8.

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