Constant temperature and humidity control method and air conditioning unit

Abstract

The invention discloses a constant-temperature and constant-humidity control method and an air conditioning unit. The constant-temperature and constant-humidity control method comprises the steps that the actual temperature, the actual relative humidity and the actual absolute humidity of an indoor environment are detected; the temperature difference delta T between the actual temperature and the set temperature, the relative humidity difference delta RH between the actual relative humidity and the set relative humidity and the absolute humidity difference delta SH between the actual absolute humidity and the set absolute humidity are calculated; selecting an absolute humidity control strategy or a relative humidity control strategy according to the temperature difference delta T; wherein the control parameters of the absolute humidity control strategy are the temperature difference delta T and the absolute humidity difference delta SH, and the control parameters of the relative humidity control strategy are the temperature difference delta T and the relative humidity difference delta RH. Regional division is carried out on temperature and humidity control of the unit, an absolute humidity control strategy is preferentially adopted, the relative control strategy is switched within the temperature precision range, the problem of high energy consumption in the traditional humidity control process is solved, and meanwhile the set temperature and humidity are achieved as soon as possible.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioning units, and in particular to a constant temperature and humidity control method and an air conditioning unit. Background Art

[0002] As a kind of precise environmental control equipment, constant temperature and humidity units are widely used in places with extremely high requirements for temperature and humidity control, such as laboratories, electronic manufacturing workshops, and pharmaceutical warehouses. In these places, precise temperature control is usually relatively easy to achieve, mainly due to the maturity of modern temperature control technology and the application of precise sensors. However, the control of humidity, especially in places where the humidity accuracy is required to be around 3% to 5% RH (relative humidity), is significantly more difficult to achieve.

[0003] The complexity of humidity control is mainly reflected in two aspects: first, the rapid fluctuation of humidity in a short period of time needs to be effectively suppressed; second, the stability of humidity over a long period of time needs to be guaranteed. Both requirements pose a great challenge to the stable operation of constant temperature and humidity units. In the existing technology, the main target of humidity control is relative humidity, because it directly reflects the ratio of the water vapor content in the air to the maximum amount of water vapor that the air may contain at the current temperature.

[0004] However, relative humidity control has an inherent drawback, which is that it is easy to cause an invalid humidity adjustment process. This is because relative humidity is a parameter that is closely related to temperature. When the ambient temperature changes, even if the absolute humidity (that is, the actual content of water vapor in the air) remains unchanged, the relative humidity will fluctuate accordingly. This characteristic leads to the situation that in the actual control process, the temperature meets the accuracy requirements, the absolute humidity deviation is also within the allowable range, but the relative humidity does not meet the accuracy requirements. The temperature and humidity adjustment process is repeated, which is inefficient, time-consuming and energy-intensive.

[0005] Therefore, how to design a constant temperature and humidity control method and air-conditioning unit that can effectively improve the temperature and humidity accuracy is a technical problem that needs to be solved urgently in the industry. Summary of the invention

[0006] In order to solve the defect of low temperature and humidity adjustment efficiency of existing units, the present invention proposes a constant temperature and humidity control method and an air-conditioning unit. The constant temperature and humidity control method selects an absolute humidity control strategy or a relative humidity control strategy according to the temperature difference, thereby effectively improving the temperature and humidity adjustment efficiency.

[0007] The technical solution adopted by the present invention is to design a constant temperature and humidity control method, including:

[0008] Detect the actual temperature, actual relative humidity and actual absolute humidity of the indoor environment;

[0009] Calculate the temperature difference ΔT between the actual temperature and the set temperature, the relative humidity difference ΔRH between the actual relative humidity and the set relative humidity, and the absolute humidity difference ΔSH between the actual absolute humidity and the set absolute humidity;

[0010] Select absolute humidity control strategy or relative humidity control strategy according to the size of the temperature difference ΔT;

[0011] Among them, the control parameters of the absolute humidity control strategy are the temperature difference ΔT and the absolute humidity difference ΔSH, and the control parameters of the relative humidity control strategy are the temperature difference ΔT and the relative humidity difference ΔRH.

[0012] Furthermore, selecting an absolute humidity control strategy or a relative humidity control strategy according to the size of the temperature difference ΔT includes: when the temperature difference ΔT is lower than the set temperature range, determining whether the absolute humidity difference ΔSH ≤ the set absolute humidity difference SH0; if so, selecting the relative humidity control strategy; if not, selecting the absolute humidity control strategy.

[0013] Furthermore, selecting an absolute humidity control strategy or a relative humidity control strategy according to the size of the temperature difference ΔT includes: when the temperature difference ΔT is in the set temperature range, determining whether the relative humidity difference ΔRH ≤ the set relative humidity difference RH0 or the absolute humidity difference ΔSH ≤ the set absolute humidity difference SH0; if so, selecting the relative humidity control strategy; if not, selecting the absolute humidity control strategy.

[0014] Further, selecting the absolute humidity control strategy or the relative humidity control strategy according to the size of the temperature difference ΔT includes: when the temperature difference ΔT is higher than the set temperature range, selecting the absolute humidity control strategy.

[0015] Furthermore, the absolute humidity control strategy includes: adjusting the compressor according to the set absolute humidity and the set temperature, and adjusting the electric heating device according to the set temperature; the relative humidity control strategy includes: adjusting the compressor according to the set relative humidity and the set temperature, and adjusting the electric heating device according to the set temperature.

[0016] Further, adjusting the compressor according to the set absolute humidity and the set temperature includes:

[0017] The set absolute humidity and set temperature are used as the target values ​​of the PID algorithm, the actual temperature and actual absolute humidity are used as the actual values ​​of the PID algorithm, and the capacity change percentage of the compressor is used as the actual value of the PID algorithm. 压 % as the output of the PID algorithm;

[0018] According to the percentage change P of the compressor capacity 压 % Regulate the compressor.

[0019] Furthermore, the electric heating device is provided with a plurality of gears, each gear having a corresponding output capacity percentage P热0 %, the electric heating device is adjusted according to the set temperature and includes:

[0020] Turn on the electric heating device according to the first set initial gear

[0021] The set temperature is used as the target value of the PID algorithm, the actual temperature is used as the actual value of the PID algorithm, and the capacity change percentage P of the electric heating device is used as the 热 % as the output of the PID algorithm;

[0022] Calculate the output capacity percentage P corresponding to the current gear 热0 % and capacity change percentage P 热 % Sum P′ 热 %, switch the electric heating device to a value lower than P′ 热 % and closest to P′ 热 % gear.

[0023] Further, adjusting the compressor according to the set relative humidity and the set temperature includes:

[0024] The set relative humidity and set temperature are used as the target values ​​of the PID algorithm, the actual temperature and actual relative humidity are used as the actual values ​​of the PID algorithm, and the capacity change percentage P of the compressor is used as the actual value of the PID algorithm. 压 % as the output of the PID algorithm;

[0025] According to the percentage change P of the compressor capacity 压 % Regulate the compressor.

[0026] Furthermore, the electric heating device is provided with a plurality of gears, each gear having a corresponding output capacity percentage P 热0 %, the electric heating device is adjusted according to the set temperature and includes:

[0027] Turn on the electric heating device according to the second set initial gear;

[0028] The set temperature is used as the target value of the PID algorithm, the actual temperature is used as the actual value of the PID algorithm, and the capacity change percentage P of the electric heating device is used as the 热 % as the output of the PID algorithm;

[0029] The capacity change percentage P within the continuous set time 热 % are less than the set percentage, calculate the capacity change percentage P of the compressor 压 % and the capacity change percentage of the electric heating device P 热 % Difference P 差 %;

[0030] According to P 差 % adjusts the gear position of the electric heating device.

[0031] Furthermore, according to P 差 The gears of the electric heating device for adjusting the size of % include:

[0032] A gear comparison relationship between the difference interval and the working gear is established in advance, and the working gear corresponding to the minimum interval among all the difference intervals is to maintain the current gear;

[0033] Get P from the gear mapping relationship 差 % corresponds to the working gear in the difference interval, and the electric heating device is switched to the working gear.

[0034] The present invention also proposes an air-conditioning unit, comprising: a compressor, a condenser, a throttling device, and an evaporator connected in sequence to form a refrigeration circuit, an electric heating device is provided on the air outlet side of the evaporator, and the controller of the air-conditioning unit executes the above-mentioned constant temperature and humidity control method.

[0035] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0036] 1. Select the absolute humidity control strategy or the relative humidity control strategy based on the temperature difference. When the temperature difference is large, the absolute humidity control strategy is preferred to speed up the humidity adjustment speed. When the temperature difference is small, the relative humidity control strategy is preferred to improve the accuracy of indoor humidity adjustment. By switching between the absolute humidity control strategy and the relative humidity control strategy, the effect of efficient temperature and humidity adjustment can be achieved.

[0037] 2. Divide the temperature and humidity control of the unit into zones, give priority to the absolute humidity control strategy, and switch to the relative control strategy within the temperature accuracy range to solve the high energy consumption problem of the traditional humidity control process and reach the set temperature and humidity as soon as possible;

[0038] 3. Adjust the compressor according to the temperature difference and absolute humidity difference / relative humidity difference to make the absolute humidity / relative humidity approach the set temperature and humidity. Adjust the electric heating device according to the temperature difference, use the heat output by the electric heating device to adjust the temperature, couple the cooling capacity with the heat to reduce temperature and humidity fluctuations and meet high precision requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The present invention is described in detail below with reference to the embodiments and accompanying drawings, wherein:

[0040] Figure 1 It is a flow chart of the constant temperature and humidity control method of the present invention;

[0041] Figure 2 is a connection diagram of the air conditioning unit of the present invention;

[0042] Description of the drawings: 1. Compressor; 2. Condenser; 21. External fan; 3. Throttling device; 4. Evaporator; 41. Internal fan; 5. Gas-liquid separator; 6. Electric heating device; 61. First electric heating group; 62. Second electric heating group; 63. Third electric heating group; 7. Temperature and humidity sensor. DETAILED DESCRIPTION

[0043] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0044] like Figure 1 , 2 As shown, the constant temperature and humidity control method proposed in the present invention is suitable for air-conditioning units, especially air-conditioning units that can flexibly adjust indoor temperature and humidity, namely constant temperature and humidity units.

[0045] Specifically, the constant temperature and humidity control method includes:

[0046] Detect the actual temperature, actual relative humidity and actual absolute humidity of the indoor environment;

[0047] Calculate the temperature difference ΔT between the actual temperature and the set temperature, the relative humidity difference ΔRH between the actual relative humidity and the set relative humidity, and the absolute humidity difference ΔSH between the actual absolute humidity and the set absolute humidity;

[0048] Select absolute humidity control strategy or relative humidity control strategy according to the size of the temperature difference ΔT;

[0049] Among them, the control parameters of the absolute humidity control strategy are the temperature difference ΔT and the absolute humidity difference ΔSH, and the control parameters of the relative humidity control strategy are the temperature difference ΔT and the relative humidity difference ΔRH.

[0050] The present invention selects an absolute humidity control strategy or a relative humidity control strategy according to the size of the temperature difference ΔT. This dynamic selection mechanism enables the system to flexibly adjust the control strategy according to the current indoor temperature and humidity conditions. When the temperature difference is large, the absolute humidity control strategy is preferred to speed up the humidity adjustment speed. When the temperature difference is small, the relative humidity control strategy is preferred to improve the temperature and humidity adjustment accuracy. By switching the absolute humidity control strategy and the relative humidity control strategy, the effect of efficiently adjusting the temperature and humidity is achieved.

[0051] The principle of this design is that relative humidity and absolute humidity are two important indicators for measuring the moisture content in the air, but there are obvious differences in their definitions and influencing factors. Absolute humidity refers to the mass or density of water vapor contained in a unit volume of air, usually expressed in grams per cubic meter (g / m 3 ) or kg / m3 (kg / m3 ) is the unit of absolute humidity, which directly reflects the actual content of water vapor in the air and is a more physically accurate humidity measurement indicator. Relative humidity refers to the ratio between the water vapor content in the air and the water vapor saturation at that temperature, expressed as a percentage (%). Relative humidity describes the ratio of the water vapor content in the air to the maximum amount of water vapor that the air may contain at the current temperature, reflecting the saturation of the air.

[0052] Absolute humidity is mainly affected by the water vapor content in the air and has no direct relationship with temperature. However, changes in temperature may affect the evaporation and condensation of water vapor, thereby indirectly affecting absolute humidity. For example, when the temperature rises, the amount of water vapor evaporation in the air may increase, but if the water vapor content in the air remains unchanged, then the absolute humidity will not change. Relative humidity is affected by both temperature and the water vapor content in the air. When the temperature rises, the saturated water vapor content increases. If the actual water vapor content remains unchanged, the relative humidity decreases; vice versa, so relative humidity is a parameter closely related to temperature.

[0053] After the air-conditioning unit is turned on, the temperature difference is usually large (generally the relative humidity deviation is also large), and the effect of adjusting the absolute humidity on the relative humidity is small. The absolute humidity control strategy is adopted to make the actual absolute humidity quickly approach the set absolute humidity. During the operation of the unit, the temperature difference will gradually decrease (generally the relative humidity deviation will also gradually decrease). The relative humidity control strategy is adopted to make the temperature and relative humidity synchronously approach the corresponding set values.

[0054] In order to improve the accuracy of the control method, the preferred solution is to compare the temperature difference ΔT with the set temperature range, and then design corresponding control logic according to the different ranges in which the temperature difference ΔT is located.

[0055] The first control logic:

[0056] If the temperature difference ΔT is lower than the set temperature range, it means that the actual temperature has met the indoor ambient temperature requirement. It is determined whether the absolute humidity difference ΔSH ≤ the set absolute humidity difference SH0. If so, it means that the actual absolute humidity is close to the set absolute humidity. At this time, the relative humidity control strategy is selected to accurately adjust the indoor ambient humidity. If not, it means that the absolute humidity deviates from the set absolute humidity. The absolute humidity control strategy is selected. Since absolute humidity is less sensitive to ambient temperature fluctuations, the actual absolute humidity can be quickly adjusted to the set absolute humidity through simple and quick adjustment actions.

[0057] The second control logic:

[0058] If the temperature difference ΔT is in the set temperature range, it means that the actual temperature is close to the set temperature. Determine whether the relative humidity difference ΔRH ≤ the set relative humidity difference RH0 or the absolute humidity difference ΔSH ≤ the set absolute humidity difference SH0. If so, it means that the actual absolute humidity is close to the set absolute humidity or the actual relative humidity is close to the set relative humidity. Select the relative humidity control strategy to accurately adjust the indoor humidity. If not, it means that the actual absolute humidity deviates from the set absolute humidity and the actual relative humidity deviates from the set relative humidity. Select the absolute humidity control strategy. Since the absolute humidity is less sensitive to ambient temperature fluctuations, the actual absolute humidity can be quickly adjusted to the set absolute humidity through simple and quick adjustment actions.

[0059] The third control logic:

[0060] If the temperature difference ΔT is higher than the set temperature range, it means that the actual temperature deviates from the set temperature. The absolute humidity control strategy is selected. Since absolute humidity is less sensitive to ambient temperature fluctuations, the actual absolute humidity can be quickly adjusted to the set absolute humidity through simple and quick adjustments. The temperature difference ΔT is monitored during the execution of the absolute humidity control strategy, and the control strategy is dynamically selected based on the size of the temperature difference ΔT.

[0061] In a preferred embodiment of the present invention, the above three control logics exist simultaneously, and regional division is performed for the temperature and humidity control of the unit. When the temperature difference is large, the absolute humidity control strategy is prioritized, and the relative control strategy is switched within the temperature accuracy range to accurately adjust the indoor environmental humidity, solve the high energy consumption problem of the traditional humidity control process, and reach the set temperature and humidity as soon as possible.

[0062] For ease of understanding, some application examples of the present invention are used as examples to illustrate the switching method of the absolute humidity control strategy and the relative humidity control strategy as follows:

[0063]

[0064] Among them: ΔT1>ΔT2>ΔT3>ΔT4, ΔT1 is higher than the set temperature range, ΔT2 is in the set temperature range, ΔT3 and ΔT4 are lower than the set temperature range; ΔRH1>ΔRH2, ΔRH1>RH0, ΔRH2≤RH0; ΔSH1>ΔSH2, ΔSH1>SH0, ΔSH2≤SH0.

[0065] No. ① is the case where the temperature difference ΔT is higher than the set temperature range, so the absolute humidity control strategy is selected;

[0066] No. ② is the case where the temperature difference ΔT is within the set temperature range and the relative humidity difference ΔRH ≤ the set relative humidity difference RH0, and the relative humidity control strategy is selected;

[0067] No. ③ is the case where the temperature difference ΔT is within the set temperature range and the absolute humidity difference ΔSH ≤ the set absolute humidity difference SH0, and the relative humidity control strategy is selected;

[0068] No. ④ is the case where the temperature difference ΔT is lower than the set temperature range and the absolute humidity difference ΔSH is greater than the set absolute humidity difference SH0, and the absolute humidity control strategy is selected;

[0069] No. ⑤ is the case where the temperature difference ΔT is lower than the set temperature range and the absolute humidity difference ΔSH ≤ the set absolute humidity difference SH0, and the relative humidity control strategy is selected;

[0070] No. ⑥ belongs to the situation where the temperature difference ΔT is lower than the set temperature range and the absolute humidity difference ΔSH ≤ the set absolute humidity difference SH0, and the relative humidity control strategy is selected.

[0071] During the operation of the air-conditioning unit, the control strategy is dynamically switched according to the temperature difference ΔT, relative humidity difference ΔRH, and absolute humidity difference ΔSH to quickly adjust the indoor temperature and humidity and reduce the energy consumption of the air-conditioning unit.

[0072] like Figure 2 As shown, in a feasible embodiment of the present invention, the air-conditioning unit includes a refrigeration circuit and an electric heating device. The refrigeration circuit includes a compressor 1, a condenser 2, a throttling device 3, an evaporator 4 and a gas-liquid separator 5 connected in sequence. The throttling device 3 here can be an electronic expansion valve or the like.

[0073] When the air-conditioning unit is in refrigeration operation, the high-temperature and high-pressure refrigerant gas discharged by the compressor 1 enters the condenser 2. The condenser 2 is usually located in the outdoor unit. The refrigerant exchanges heat with the outdoor environment, releases heat and condenses into a high-pressure liquid. The heat released during the condensation process is dissipated to the outdoor environment through the outdoor fan 21. The high-pressure refrigerant liquid condensed by the condenser 2 is throttled and reduced in pressure by the throttling device 3 to become a low-temperature and low-pressure liquid. After the low-temperature and low-pressure refrigerant liquid enters the evaporator 4, it exchanges heat with the indoor air in the evaporator 4. The refrigerant liquid evaporates into gas and absorbs the heat of the indoor air. The cooled airflow is blown into the indoor environment through the indoor fan 41 to lower the indoor temperature. The low-temperature and low-pressure refrigerant gas evaporated by the evaporator 4 passes through the gas-liquid separator 5 and is sucked into the compressor 1 to start a new round of refrigeration cycle.

[0074] In the above refrigeration cycle, when the indoor air passes through the evaporator 4, it will exchange heat with the surface of the evaporator 4. Since the temperature of the surface of the evaporator 4 is very low, the temperature of the air will drop significantly, and the water vapor in the air will condense on the surface of the evaporator 4, which has a dehumidification effect while cooling. In order to balance the refrigeration capacity of the excess output of humidity adjustment, an electric heating device 6 is installed on the air outlet side of the evaporator 4. After the indoor air passes through the evaporator 4, it passes through the electric heating device 6 and is reheated and sent to the room, so that the indoor temperature and humidity can meet the needs of users.

[0075] In order to realize intelligent control of the air-conditioning unit, a temperature and humidity sensor 7 is installed on the air inlet side of the evaporator 4 or indoors. The controller of the air-conditioning unit obtains the actual temperature, actual relative humidity and actual absolute humidity of the indoor environment through the temperature and humidity sensor 7, analyzes the temperature difference ΔT, the relative humidity difference ΔRH, and the absolute humidity difference ΔSH, and selects the corresponding control strategy according to the control logic mentioned above.

[0076] On this basis, the absolute humidity control strategy includes: adjusting the compressor 1 according to the set absolute humidity and the set temperature, and adjusting the electric heating device 6 according to the set temperature; the relative humidity control strategy includes: adjusting the compressor 1 according to the set relative humidity and the set temperature, and adjusting the electric heating device 6 according to the set temperature.

[0077] The control parameters for the compressor in different control strategies are different. The absolute humidity control strategy analyzes the workload of the compressor based on the set absolute humidity and set temperature, and then adjusts the capacity of the compressor. The relative temperature control strategy analyzes the workload of the compressor based on the set relative humidity and set temperature, and then adjusts the capacity of the compressor. Both control strategies analyze the heat load of the electric heating device based on the set temperature, and adjust the capacity of the electric heating device to balance the temperature fluctuation caused by the excess capacity of the compressor.

[0078] Specifically, the control methods of the two control strategies are as follows:

[0079] Control strategy Compressor capacity Electric heating control Absolute humidity control strategy PID(ΔSH+ΔT) PID(ΔT)+multi-gear Relative humidity control strategy PID (ΔRH+ΔT) PID(ΔT)+fixed gear

[0080] In actual application, the change of compressor capacity can be fed back to the operating frequency, that is, the operating frequency of compressor 1 is adjusted according to the output of PID (ΔSH+ΔT), and the change of electric heating device capacity can be fed back to the power, that is, the gear of electric heating device 6 is adjusted according to the output of PID (ΔT).

[0081] The two control strategies are introduced in detail below.

[0082] In some embodiments of the present invention, the absolute humidity control strategy uses a PID algorithm to adjust the compressor, and the calculation process of the compressor capacity change is as follows:

[0083] The set absolute humidity and set temperature are used as the target values ​​of the PID algorithm, the actual temperature and actual absolute humidity are used as the actual values ​​of the PID algorithm, and the capacity change percentage of the compressor is used as the actual value of the PID algorithm. 压 % is the output of the PID algorithm, which can be designed according to actual needs, for example, ΔT n Indicates the temperature difference at the current moment, ΔT n-1 Indicates the temperature difference at the previous moment, ΔSH n Indicates the absolute humidity difference at the current moment, ΔSH n-1 Indicates the absolute humidity difference at the previous moment, kp1, ki1 and kd1 are the coefficients of the PID algorithm;

[0084] According to the percentage change P of the compressor capacity 压 % Regulate the compressor.

[0085] The advantage of this design is that the compressor is PID-regulated according to the set absolute humidity and set temperature, with a fast response speed, and the working state of the compressor can be quickly adjusted to reduce the deviation between the actual value and the set value.

[0086] In some embodiments of the present invention, the electric heating device 6 is provided with a plurality of gears, each gear having a corresponding output capacity percentage P. 热0 %, the electric heating device 6 adopts multi-gear adjustment, and the adjustment process of different gears is as follows:

[0087] Turn on the electric heating device 6 according to the first set initial gear;

[0088] The set temperature is used as the target value of the PID algorithm, the actual temperature is used as the actual value of the PID algorithm, and the capacity change percentage P of the electric heating device is used as the 热 % is the output of the PID algorithm, which can be designed according to actual needs, for example, ΔT n Indicates the temperature difference at the current moment, ΔT n-1 Indicates the temperature difference at the previous moment, kp2, ki2 and kd2 are the coefficients of the PID algorithm;

[0089] Calculate the output capacity percentage P corresponding to the current gear 热0 % and capacity change percentage P 热 % Sum P′ 热 %, the electric heating device 6 is switched to a value lower than P′ 热 % and closest to P′ 热 % gear.

[0090] The advantage of this design is that changes in the output capacity of the compressor will cause changes in the indoor temperature, and the gear position of the electric heating device 6 will switch dynamically following the changes in the indoor temperature. Therefore, under the absolute humidity control strategy, the indoor temperature and humidity can quickly tend to the corresponding set values, and the adjustment efficiency is higher.

[0091] For ease of understanding, some application examples of the present invention are used for illustration.

[0092] The electric heating device 6 comprises a first electric heating group 61, a second electric heating group 62 and a third electric heating group 63, and the capacity ratio of each electric heating group is as follows:

[0093] Capacity ratio Electric heating group 15％ The first electric heating group 30％ The second electric heating group 45％ The third electric heating group

[0094] The gear setting of the electric heating device 6 is as follows:

[0095]

[0096]

[0097] The electric heating device 6 is turned on at the first gear, with an output percentage of 15%, and then according to P' 热 % Adjust the gear position of the electric heating device 6, define P 热 %∈[-30%, 30%].

[0098] For example, the current gear is 1st gear, and the calculated P 热 % is 16%, then P′ 热 % is 31%, the electric heating device 6 is switched to the second gear; for another example, the current gear is the second gear, and the calculated P 热 % is -14%, then P′ 热 % is 16%, the electric heating device 6 switches to the first gear.

[0099] In some embodiments of the present invention, the relative humidity control strategy uses a PID algorithm to adjust the compressor 1, and the calculation process of the compressor capacity change is as follows:

[0100] The set relative humidity and set temperature are used as the target values ​​of the PID algorithm, the actual temperature and actual relative humidity are used as the actual values ​​of the PID algorithm, and the capacity change percentage P of the compressor is used as the actual value of the PID algorithm. 压 % is the output of the PID algorithm, which can be designed according to actual needs, for example, ΔT n Indicates the temperature difference at the current moment, ΔT n-1 Indicates the temperature difference at the previous moment, ΔRH n Indicates the relative humidity difference at the current moment, ΔRH n-1Indicates the relative humidity difference at the previous moment, kp3, ki3 and kd3 are the coefficients of the PID algorithm;

[0102] According to the percentage change P of the compressor capacity 压 % Adjust compressor 1.

[0103] The advantage of this design is that the compressor is PID-regulated according to the set relative humidity and the set temperature, the response speed is fast, and the working state of the compressor 1 can be quickly adjusted to reduce the deviation between the actual value and the set value.

[0104] Based on the compressor PID adjustment, the electric heating device 6 is provided with multiple gears, each gear has a corresponding output capacity percentage P 热0 %, the gear position of the electric heating device 6 is adjusted according to the difference between the compressor capacity and the electric heating capacity, and the adjustment process of different gear positions is as follows:

[0105] Turn on the electric heating device 6 according to the second set initial gear;

[0106] The set temperature is used as the target value of the PID algorithm, the actual temperature is used as the actual value of the PID algorithm, and the capacity change percentage P of the electric heating device 6 is used as the 热 % is the output of the PID algorithm, which can be designed according to actual needs, for example, ΔT n Indicates the temperature difference at the current moment, ΔT n-1 Indicates the temperature difference at the previous moment, kp2, ki2 and kd2 are the coefficients of the PID algorithm;

[0107] The capacity change percentage P within the continuous set time 热 % are less than the set percentage, calculate the capacity change percentage P of compressor 1 压 % and the capacity change percentage P of the electric heating device 6 热 % Difference P 差 %;

[0108] According to P 差 % adjusts the gear position of the electric heating device 6.

[0109] The principle of this design is that when the capacity changes by percentage P within a continuous set time 热 % are all less than the set percentage, indicating that the indoor temperature fluctuation is small. At this time, the capacity change percentage P of compressor 1 is 压 % and the capacity change percentage P of the electric heating device 6 热 % Difference P 差 % Adjust the gear position of the electric heating device 6, so that under the relative humidity control strategy, the indoor temperature and humidity change in stages, gradually approaching and reaching the set value, thereby improving the temperature and humidity control accuracy.

[0110] Specifically, in some embodiments of the present invention, according to P 差 % The way to adjust the gear position of the electric heating device is as follows:

[0111] A gear comparison relationship between the difference interval and the working gear is established in advance, and the working gear corresponding to the minimum interval among all the difference intervals is to maintain the current gear;

[0112] Get P from the gear mapping relationship 差 % corresponds to the working gear in the difference interval, and the electric heating device is switched to the working gear.

[0113] For ease of understanding, some application examples of the present invention are used for illustration.

[0114] The electric heating device 6 comprises a first electric heating group 61, a second electric heating group 62 and a third electric heating group 63, and the capacity ratio of each electric heating group is as follows:

[0115] Capacity ratio Electric heating group 15％ The first electric heating group 30％ The second electric heating group 45％ The third electric heating group

[0116] The gear comparison relationship between the difference range and the working gear is as follows:

[0117] The difference between compressor capacity and electric heating capacity Additional electric heating capability ＞30％ 30％ 20％～30％ 15％ 0～20％ constant

[0118] The electric heating device 6 is turned on at the 3rd gear, with an output percentage of 45%, and then 差 %Adjust the gear of the electric heating device and set the percentage to 10%.

[0119] For example, the current gear is the 3rd gear. When P is calculated for 10 consecutive detection cycles, 热 % are less than 10%, calculate P 差 %, if P 差 % exceeds 30%, the electric heating capacity is increased by 30%, and the electric heating device 6 is switched to the 5th gear. If P 差 % is between 20% and 30%, the electric heating capacity is increased by 15%, and the electric heating device 6 is switched to the 4th gear. 差 % is between 0 and 20%, the electric heating device 6 maintains the third gear.

[0120] It should be noted that the terms used above are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. When the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof. The order of execution of actions, steps, etc. in the devices and methods shown in the specification and the accompanying drawings can be implemented in any order as long as there is no special explicit limitation on the order and the output of the previous processing is not used in the subsequent processing. Similar terms of order used for the convenience of description do not mean that they must be implemented in such an order.

[0121] Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such techniques, methods, and apparatus should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following figures, and therefore, once an item is defined in one figure, it does not need to be further discussed in subsequent figures.

[0122] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A constant temperature and humidity control method, characterized in that: include: Detect the actual temperature, actual relative humidity and actual absolute humidity of the indoor environment; Calculating a temperature difference ΔT between the actual temperature and the set temperature, a relative humidity difference ΔRH between the actual relative humidity and the set relative humidity, and an absolute humidity difference ΔSH between the actual absolute humidity and the set absolute humidity; Selecting an absolute humidity control strategy or a relative humidity control strategy according to the size of the temperature difference ΔT; The control parameters of the absolute humidity control strategy are the temperature difference ΔT and the absolute humidity difference ΔSH, and the control parameters of the relative humidity control strategy are the temperature difference ΔT and the relative humidity difference ΔRH.

2. The constant temperature and humidity control method according to claim 1, characterized in that: Selecting an absolute humidity control strategy or a relative humidity control strategy according to the size of the temperature difference ΔT includes: when the temperature difference ΔT is lower than the set temperature range, determining whether the absolute humidity difference ΔSH ≤ the set absolute humidity difference SH0; if so, selecting the relative humidity control strategy; if not, selecting the absolute humidity control strategy.

3. The constant temperature and humidity control method according to claim 1, characterized in that: Selecting an absolute humidity control strategy or a relative humidity control strategy according to the size of the temperature difference ΔT includes: when the temperature difference ΔT is in a set temperature range, determining whether the relative humidity difference ΔRH ≤ the set relative humidity difference RH0 or the absolute humidity difference ΔSH ≤ the set absolute humidity difference SH0; if so, selecting the relative humidity control strategy; if not, selecting the absolute humidity control strategy.

4. The constant temperature and humidity control method according to claim 1, characterized in that: Selecting the absolute humidity control strategy or the relative humidity control strategy according to the size of the temperature difference ΔT includes: when the temperature difference ΔT is higher than a set temperature range, selecting the absolute humidity control strategy.

5. The constant temperature and humidity control method according to claim 1, characterized in that: The absolute humidity control strategy includes: adjusting the compressor according to the set absolute humidity and the set temperature, and adjusting the electric heating device according to the set temperature; the relative humidity control strategy includes: adjusting the compressor according to the set relative humidity and the set temperature, and adjusting the electric heating device according to the set temperature.

6. The constant temperature and humidity control method according to claim 5, characterized in that: Adjusting the compressor according to the set absolute humidity and the set temperature comprises: The set absolute humidity and the set temperature are used as the target values ​​of the PID algorithm, the actual temperature and the actual absolute humidity are used as the actual values ​​of the PID algorithm, and the capacity change percentage P of the compressor is used as the actual value of the PID algorithm. 压 % as the output of the PID algorithm; According to the percentage change P of the compressor capacity 压 % Regulate the compressor.

7. The constant temperature and humidity control method according to claim 5, characterized in that: The electric heating device is provided with multiple gears, each gear has a corresponding output capacity percentage P 热0 %, the electric heating device is adjusted according to the set temperature and comprises: Turning on the electric heating device according to a first set initial gear position; The set temperature is used as the target value of the PID algorithm, the actual temperature is used as the actual value of the PID algorithm, and the capacity change percentage P of the electric heating device is used as the 热 % as the output of the PID algorithm; Calculate the output capacity percentage P corresponding to the current gear 热0 % and the percentage change in the capacity P 热 % Sum P ′ 热 %, the electric heating device is switched to a value lower than P ′ 热 % and closest to P ′ 热 % gear.

8. The constant temperature and humidity control method according to claim 5, characterized in that: Adjusting the compressor according to the set relative humidity and the set temperature includes: The set relative humidity and the set temperature are used as the target values ​​of the PID algorithm, the actual temperature and the actual relative humidity are used as the actual values ​​of the PID algorithm, and the capacity change percentage P of the compressor is used as the actual value of the PID algorithm. 压 % as the output of the PID algorithm; According to the percentage change P of the compressor capacity 压 % Regulate the compressor.

9. The constant temperature and humidity control method according to claim 8, characterized in that: The electric heating device is provided with multiple gears, each gear has a corresponding output capacity percentage P 热0 %, the electric heating device is adjusted according to the set temperature and comprises: Turning on the electric heating device according to a second set initial gear position; The set temperature is used as the target value of the PID algorithm, the actual temperature is used as the actual value of the PID algorithm, and the capacity change percentage P of the electric heating device is used as the 热 % as the output of the PID algorithm; The capacity change percentage P within the continuous set time 热 % are less than the set percentage, calculate the capacity change percentage P of the compressor 压 % and the percentage change in the capacity of the electric heating device P 热 % Difference P 差 %; According to the P 差 % adjusts the gear position of the electric heating device.

10. The constant temperature and humidity control method according to claim 9, characterized in that: According to the P 差 The size of the electric heating device is adjusted to include: A gear comparison relationship between the difference interval and the working gear is established in advance, and the working gear corresponding to the minimum interval among all the difference intervals is to maintain the current gear; Obtain the P from the gear mapping relationship 差 % corresponds to the working gear in the difference interval, and the electric heating device is switched to the working gear.

11. Air conditioning units, including: A compressor, a condenser, a throttling device, and an evaporator are connected in sequence to form a refrigeration circuit, and an electric heating device is provided on the air outlet side of the evaporator. It is characterized in that the controller of the air-conditioning unit executes the constant temperature and humidity control method described in any one of claims 1 to 10.

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