A control method of a variable frequency constant temperature and humidity unit

Abstract

The application discloses a control method of a variable frequency constant temperature and humidity unit, which comprises an indoor unit, an outdoor unit and a constant temperature and humidity space, the indoor unit and the outdoor unit are connected through a first refrigerant connecting pipe and a second refrigerant connecting pipe, temperature sensors and humidity sensors are installed in the constant temperature and humidity space, the indoor unit and the constant temperature and humidity space are connected through air supply pipes and return air pipes, and a PID controller is further included, the temperature sensors, the humidity sensors and the outdoor unit are connected with the PID controller, and the PID controller is used for PID control of two variables of required temperature and humidity, so that the running frequency of a compressor is controlled, and the effects of energy saving and rapid adjustment are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of refrigeration and air conditioning, in particular to a control method of a variable frequency constant temperature and humidity unit. BACKGROUND

[0002] At present, constant temperature and humidity air conditioning units are needed in laboratories, libraries, museums, electronic workshops and other places. To achieve constant temperature and humidity function, the current direct expansion unit is one of the commonly used options. The constant temperature and humidity unit often has problems that the temperature and humidity control is not within the range, or it takes a long time to stabilize to the set temperature and humidity range, affecting use and energy consumption. SUMMARY

[0003] To solve the defects that the existing technology often has problems that the temperature and humidity control is not within the range, or it takes a long time to stabilize to the set temperature and humidity range, affecting use and energy consumption, the present application provides a control method of a variable frequency constant temperature and humidity unit.

[0004] To solve the above technical problems, the present application provides the following technical solutions:

[0005] The control method of the variable frequency constant temperature and humidity unit comprises an indoor unit, an outdoor unit and a constant temperature and humidity space, the indoor unit and the outdoor unit are connected through a first refrigerant connecting pipe and a second refrigerant connecting pipe; a temperature sensor and a humidity sensor are installed in the constant temperature and humidity space; the indoor unit and the constant temperature and humidity space are connected through a supply air pipe and a return air pipe; and a PID controller is further included, the temperature sensor, the humidity sensor, the outdoor unit and the PID controller are connected.

[0006] The control method of the unit is,

[0007] Step 1: periodically sampling the constant temperature and humidity space through the temperature sensor and the humidity sensor; real-time detecting the actual temperature Tm(i) and the actual humidity Фm(i) of the constant temperature and humidity space in the i-th sampling period, and comparing them with the set temperature Tset and the set humidity Фset, and calculating the change of the frequency of the direct current variable frequency compressor through the PID algorithm;

[0008] Step 2: adjusting and controlling the constant temperature and humidity working mode of the unit according to the actual temperature Tm(i) and the actual humidity Фm(i).

[0009] As a preferred technical solution of the present application, the specific method of step 2 is to determine the temperature deviation amount △T(i) and the humidity deviation amount △Ф(i), and in the refrigeration mode,

[0010] When the humidifier is started in the continuous N sampling periods, i.e. the switch value is closed or the analog value is output, and the electric heating is not started in the continuous N sampling periods, i.e. the switch value is opened or the analog value is not output, then the analog value △f(i)=△T(i);

[0011] When the humidifier is not started in the continuous N sampling periods, i.e. the switch value is opened or the analog value is not output, and the electric heating is started in the continuous N sampling periods, i.e. the switch value is closed or the analog value is output, then the analog value △f(i)=△Ф(i);

[0012] When the humidifier is not started in the continuous N sampling periods, i.e. the switch value is opened or the analog value is not output, and the electric heating is not started in the continuous N sampling periods, i.e. the switch value is opened or the analog value is not output, then there is △f(i)=max(△T(i),△Ф(i)), and the running frequency of the outdoor unit is increased;

[0013] If the humidifier is started in the continuous N sampling periods, i.e. the switch value is closed or the analog value is output, and the electric heating is started in the continuous N sampling periods, i.e. the switch value is closed or the analog value is output, then the outdoor unit is sent a decrease instruction.

[0014] As a preferred technical scheme of the application, the unit is in a constant temperature and humidity mode refrigeration working state, the compressor is in a refrigeration working state, the running frequency of the compressor is controlled according to the changes of temperature and humidity, and there is △f(i)=max(△T(i),△Ф(i)), so that

[0015] △f(i)≥set1, fast increase; set1 is 10 by default and can be adjusted to 8-13

[0016] set1>△f(i)≥set2, medium increase; set2 is 5 by default and can be adjusted to 4-7

[0017] set2>△f(i)≥set3, slow increase; set3 is 2 by default and can be adjusted to 1-3

[0018] set3>△f(i)>-set3, maintain;

[0019] -set3≥△f(i)>-set2, slow decrease;

[0020] -set2≥△f(i)>-set1, medium decrease;

[0021] -set1≥△f(i), fast decrease.

[0022] As a preferred technical scheme of the present application, when the unit is in the constant temperature and humidity mode refrigeration working state and the compressor is in the heating working state, the running frequency of the compressor is controlled according to the temperature variation, at this time, △f(i)=△T(i), then,

[0023] △f(i)≥set1, fast reduction;

[0024] set1>△f(i)≥set2, medium reduction;

[0025] set2>△f(i)≥set3, slow reduction;

[0026] set3>△f(i)>-set3, maintenance;

[0027] -set3≥△f(i)>-set2, slow increase;

[0028] -set2≥△f(i)>-set1, medium increase;

[0029] -set1≥△f(i), fast increase.

[0030] As a preferred technical scheme of the present application, when the outdoor unit (5) is in the starting, stopping, defrosting and oil returning, the running frequency of the compressor in the outdoor unit (5) is not adjusted by the indoor unit (1).

[0031] As a preferred technical scheme of the present application, when the running frequency of the compressor (51) is loaded over fmax, the frequency is not increased any more and the compressor (51) is operated at the frequency fmax; when the running frequency of the compressor (51) is reduced to fmin, the frequency is not reduced any more and the compressor (51) is operated at the frequency fmin.

[0032] The present application has the following beneficial effects:

[0033] The control method of the variable frequency constant temperature and humidity unit detects the temperature and humidity in the constant temperature and humidity space through the temperature sensor and the humidity sensor, and controls the running frequency of the compressor through the PID controller, so that the energy saving and rapid adjustment effects are achieved. BRIEF DESCRIPTION OF DRAWINGS

[0034] The accompanying drawings are included to provide a further understanding of the present application and constitute a part of the specification, which together with the embodiments of the present application serve to explain the present application and do not constitute a limitation of the present application. In the drawings:

[0035] Figure 1 is a structural schematic diagram of the control method of the variable frequency constant temperature and humidity unit.

[0036] In the diagram: 1. Indoor unit; 2. Air supply duct; 3. Constant temperature and humidity space; 31. Temperature sensor; 32. Humidity sensor; 4. Return air duct; 5. Constant temperature and humidity space; 51. Compressor; 6. PID controller; 7. First refrigerant connection pipe; 8. Second refrigerant connection pipe. Detailed Implementation

[0037] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0038] Example: Figure 1 As shown, the present invention discloses a control method for a variable frequency constant temperature and humidity unit, comprising an indoor unit 1, an outdoor unit 5, and a constant temperature and humidity space 3. The indoor unit 1 and the outdoor unit 5 are connected by a first refrigerant connection pipe 7 and a second refrigerant connection pipe 8. A temperature sensor 31 and a humidity sensor 32 are installed in the constant temperature and humidity space 3. The indoor unit 1 and the constant temperature and humidity space 3 are connected by an air supply pipe 2 and a return air pipe 4. The method also includes a PID controller 6, and the temperature sensor 31, the humidity sensor 32, and the outdoor unit 5 are connected to the PID controller 6.

[0039] In cooling operation, the PID controller 6 adjusts the operating frequency of the compressor 51 inside the outdoor unit 5 based on temperature data detected by the temperature sensor 31 and humidity data detected by the humidity sensor 32. By detecting the temperature and humidity in the constant temperature and humidity space using the temperature and humidity sensors, and employing PID control for both temperature and humidity variables, the compressor's operating frequency is controlled, achieving energy saving and rapid adjustment.

[0040] In heating mode, the PID controller 6 adjusts and controls the operating frequency of the compressor 51 inside the outdoor unit 5 based on the temperature information data detected by the temperature sensor 31.

[0041] When the outdoor unit 5 is in the process of starting up, stopping, defrosting, or returning oil, the operating frequency of the compressor inside the outdoor unit 5 is not adjusted by the indoor unit 1.

[0042] Once the operating frequency of compressor 51 exceeds fmax, the frequency will not increase further and will operate at the fmax frequency. Once the operating frequency of compressor 51 decreases to fmin, the frequency will not decrease further and will operate at the fmin frequency.

[0043] PID controllers are used for both temperature and humidity, which require control. This controls the compressor's operating frequency, achieving energy savings and rapid adjustment. Details are as follows:

[0044] (1) Real-time detection of the actual temperature Tm(i) and actual humidity Фm(i) of the constant temperature and humidity space (3) in the i-th sampling period, and comparison with the set temperature Tset and the set humidity Фset, and calculation of the change of the frequency of the direct-current variable frequency compressor through the PID algorithm.

[0045] (2) Temperature deviation calculation

[0046] △T(i) = [Tm(i) - Tset] * Kp + [Tm(i) - Tm(i-1)] * Ki

[0047] (3) Humidity deviation calculation

[0048] △Ф(i) = [Фm(i) - Tset] * Kps + [Фm(i) - Фm(i-1)] * Kis

[0049] (4) Unit refrigeration mode capacity adjustment calculation

[0050] 1) The humidifier is started (the switch is closed or the analog quantity has a value output) for N consecutive sampling periods, and the electric heating is not started (the switch is opened or the analog quantity has no value output) for N consecutive sampling periods, and △f(i) = △T(i); N is 10 by default and can be adjusted between 8 and 12; the △f analog quantity value.

[0051] 2) The humidifier is not started (the switch is opened or the analog quantity has no value output) for N consecutive sampling periods, and the electric heating is started (the switch is closed or the analog quantity has a value output) for N consecutive sampling periods, and △f(i) = △Ф(i);

[0052] 3) The humidifier is not started (the switch is opened or the analog quantity has no value output) for N consecutive sampling periods, and the electric heating is not started (the switch is opened or the analog quantity has no value output) for N consecutive sampling periods, and △f(i) = max(△T(i), △Ф(i));

[0053] 4) The humidifier is started (the switch is closed or the analog quantity has a value output) for N consecutive sampling periods, and the electric heating is started (the switch is closed or the analog quantity has a value output) for N consecutive sampling periods, and a decrease command is sent to the outdoor unit;

[0054] (5) Unit heating mode capacity adjustment calculation

[0055] △f(i) = △T(i)

[0056] (6) Compressor capacity adjustment in constant temperature and humidity mode refrigeration working state

[0057] Compressor in refrigeration working state, through PID calculation, the change of temperature and humidity to control the compressor frequency.

[0058] 1) △f(i) ≥ set1, fast increase; set1 default 10, 8~13 adjustable

[0059] 2) set1 > △f(i) ≥ set2, medium increase; set2 default 5, 4~7 adjustable

[0060] 3) set2 > △f(i) ≥ set3, slow increase; set3 default 2, 1~3 adjustable

[0061] 4) set3 > △f(i) > -set3, maintain;

[0062] 5) -set3 ≥ △f(i) > -set2, slow decrease;

[0063] 6) -set2 ≥ △f(i) > -set1, medium decrease;

[0064] 7) -set1 ≥ △f(i), fast decrease;

[0065] (7) constant temperature and humidity mode heating working state compressor capacity regulation

[0066] Compressor in heating working state, through PID calculation, according to the change of temperature to control the compressor frequency. At this time, △f(i)= △T(i).

[0067] 1) △f(i) ≥ set1, fast decrease;

[0068] 2) set1 > △f(i) ≥ set2, medium decrease;

[0069] 3) set2 > △f(i) ≥ set3, slow decrease;

[0070] 4) set3 > △f(i) > -set3, maintain;

[0071] 5) -set3 ≥ △f(i) > -set2, slow increase;

[0072] 6) -set2 ≥ △f(i) > -set1, medium increase;

[0073] 7) -set1 ≥ △f(i), fast increase;

[0074] (8) unit capacity regulation rule

[0075] When the outdoor unit is in a special operating state (start-up, shutdown, defrosting, oil return), the outdoor unit compressor operating frequency is not subject to indoor unit adjustment. In other states, the indoor unit sends the outdoor unit: fast increase (default +5Hz, 5~8Hz adjustable), medium increase (default +3Hz, 2~4Hz adjustable), slow increase (default +1Hz, 1~2Hz adjustable), maintain (frequency remains unchanged), slow decrease (default -1Hz, -1~-2Hz adjustable), medium decrease (default -3Hz, -2~-4Hz adjustable), fast decrease command (default -5Hz, -5~-8Hz adjustable), and the indoor unit reads the operating frequency of each outdoor unit in real time.

[0076] (9) Compressor frequency limit

[0077] The total compressor frequency is ≤fmin, and has been sustained for more than 8 cycles; the compressor is in a standby state. fmin is the lower limit of the compressor frequency, and the default is 30Hz.

[0078] The upper limit of the compressor frequency is fmax, and the default is 90Hz, 90~108Hz adjustable.

[0079] When the compressor operating frequency exceeds fmax, the frequency is no longer increased, and the compressor operates at fmax frequency.

[0080] Finally, it should be noted that the above only describes the preferred embodiments of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent replacements to some technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A control method of a variable frequency constant temperature and humidity unit, characterized by, The air conditioning unit comprises an indoor unit (1), an outdoor unit (5) and a constant temperature and humidity space (3), the indoor unit (1) and the outdoor unit (5) are connected through a first refrigerant connecting pipe (7) and a second refrigerant connecting pipe (8), the constant temperature and humidity space (3) is provided with a temperature sensor (31) and a humidity sensor (32), and the indoor unit (1) and the constant temperature and humidity space (3) are connected through an air supply pipe (2) and an air return pipe (4); the air conditioning unit further comprises a PID controller (6), the temperature sensor (31), the humidity sensor (32) and the outdoor unit (5) are connected with the PID controller (6); The control method of the air conditioning unit is, Step 1: periodically sampling the constant temperature and humidity space through the temperature sensor and the humidity sensor; Real-time detection of the actual temperature Tm(i) and the actual humidity Фm(i) of the constant temperature and humidity space in the i-th sampling cycle, comparison with the set temperature Tset and the set humidity Фset, and calculation of the change of the frequency of the direct-current variable frequency compressor through the PID algorithm; Step 2: adjusting and controlling the constant temperature and humidity working mode of the air conditioning unit according to the actual temperature Tm(i) and the actual humidity Фm(i); The specific method of step 2 is to determine the temperature deviation amount △T(i) and the humidity deviation amount △Ф(i), in the refrigeration mode, When the humidifier is started for N consecutive sampling periods, that is, the switching value is closed or the analog value is output, and the electric heating is not started for N consecutive sampling periods, that is, the switching value is opened or the analog value is not output, then the analog value △f(i)=△T(i); When the humidifier is not started for N consecutive sampling periods, that is, the switching value is opened or the analog value is not output, and the electric heating is started for N consecutive sampling periods, that is, the switching value is closed or the analog value is output, then the analog value △f(i)=△Ф(i); When the humidifier is not started for N consecutive sampling periods, that is, the switching value is opened or the analog value is not output, and the electric heating is not started for N consecutive sampling periods, that is, the switching value is opened or the analog value is not output, then there is △f(i)=max(△T(i),△Ф(i)), and the running frequency of the outdoor unit is increased; If the humidifier is started for N consecutive sampling periods, that is, the switching value is closed or the analog value is output, and the electric heating is started for N consecutive sampling periods, that is, the switching value is closed or the analog value is output, a decrease instruction is sent to the outdoor unit.

2. The control method of a variable frequency constant temperature and humidity unit according to claim 1, characterized in that, In the refrigeration working state, the air conditioning unit is in the constant temperature and humidity mode refrigeration working state, the compressor is in the refrigeration working state, the running frequency of the compressor is controlled according to the changes of the temperature and the humidity, and there is △f(i)=max(△T(i),△Ф(i)) △f(i)≥set1, fast increase; set1 is 10 by default and can be adjusted to 8-13 set1>△f(i)≥set2, medium increase; set2 is 5 by default and can be adjusted to 4-7 set2>△f(i)≥set3, slow increase; set3 is 2 by default and can be adjusted to 1-3 set3>△f(i)>-set3, maintain; -set3≥△f(i)>-set2, slow decrease; -set2≥△f(i)>-set1, medium decrease; -set1≥△f(i), fast decrease.

3. The control method of a variable frequency constant temperature and humidity unit according to claim 1, wherein, In the constant temperature and humidity mode refrigeration working state of the unit, the compressor is in the heating working state, the running frequency of the compressor is controlled according to the temperature change, at this time, △f(i)=△T(i), then, △f(i)≥set1, fast decrease; set1>△f(i)≥set2, medium decrease; set2>△f(i)≥set3, slow decrease; set3>△f(i)>-set3, maintain; -set3≥△f(i)>-set2, slow increase; -set2≥△f(i)>-set1, medium increase; -set1≥△f(i), fast increase.

4. The control method of a variable frequency constant temperature and humidity unit according to claim 1, characterized in that, When the outdoor unit (5) is in the starting, stopping, defrosting and oil returning, the running frequency of the compressor in the outdoor unit (5) is not adjusted by the indoor unit (1).

5. The control method of a variable frequency constant temperature and humidity unit according to claim 1, wherein, When the running frequency of the compressor (51) is loaded more than fmax, the frequency is not increased, and the compressor (51) is operated at fmax frequency; when the running frequency of the compressor (51) is reduced to fmin, the frequency is not reduced, and the compressor (51) is operated at fmin frequency.

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