CN114739081B - Air conditioning unit control method and control system and air conditioning unit - Google Patents
Air conditioning unit control method and control system and air conditioning unit Download PDFInfo
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- CN114739081B CN114739081B CN202210318897.7A CN202210318897A CN114739081B CN 114739081 B CN114739081 B CN 114739081B CN 202210318897 A CN202210318897 A CN 202210318897A CN 114739081 B CN114739081 B CN 114739081B
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- 238000004378 air conditioning Methods 0.000 title claims abstract description 80
- 238000000034 method Methods 0.000 title claims abstract description 35
- 238000001704 evaporation Methods 0.000 claims abstract description 122
- 230000008020 evaporation Effects 0.000 claims abstract description 109
- 230000008859 change Effects 0.000 claims abstract description 88
- 238000001514 detection method Methods 0.000 claims description 87
- 238000005057 refrigeration Methods 0.000 claims description 22
- 238000012937 correction Methods 0.000 claims description 18
- 230000009467 reduction Effects 0.000 claims description 11
- 238000006243 chemical reaction Methods 0.000 claims 1
- 230000003750 conditioning effect Effects 0.000 abstract description 7
- 239000007788 liquid Substances 0.000 description 19
- 230000000694 effects Effects 0.000 description 6
- 230000008569 process Effects 0.000 description 5
- 238000001816 cooling Methods 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 239000003507 refrigerant Substances 0.000 description 2
- 230000001960 triggered effect Effects 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 230000001174 ascending effect Effects 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 235000013399 edible fruits Nutrition 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 239000008267 milk Substances 0.000 description 1
- 210000004080 milk Anatomy 0.000 description 1
- 235000013336 milk Nutrition 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000008092 positive effect Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 235000013311 vegetables Nutrition 0.000 description 1
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
- F25D11/00—Self-contained movable devices, e.g. domestic refrigerators
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
- F25D29/00—Arrangement or mounting of control or safety devices
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
- Y02B30/70—Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating
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- Combustion & Propulsion (AREA)
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- General Engineering & Computer Science (AREA)
- Air Conditioning Control Device (AREA)
Abstract
The invention discloses a control method and a control system of an air conditioning unit and the air conditioning unit, wherein by periodically detecting the evaporation pressure, when the evaporation pressure is detected to be reduced and the change rate of the evaporation pressure is greater than a change rate threshold value, the compressor is controlled to reduce the frequency; when the increase of the evaporation pressure is detected, and the change rate of the evaporation pressure is larger than a change rate threshold value, controlling the compressor to increase frequency; the low-pressure protection stop of the compressor is avoided, the air conditioning effect is ensured, the problem that the compressor is frequently started and stopped is solved, the temperature control precision of the indoor unit is improved, and the reliability of the air conditioning unit is improved.
Description
Technical Field
The invention belongs to the technical field of air conditioning, and particularly relates to an air conditioning unit control method, a control system and an air conditioning unit.
Background
With the development of economy, the living standard of people is greatly improved, and the freezing and refrigerating technology is widely applied. More and more commercial refrigeration cabinets are configured for fresh-keeping and storage of milk products, drinks and time-ordered vegetables and fruits, and the product quality is improved. A plurality of refrigeration showcases are generally configured in the business, and the outdoor unit of the corresponding condensing unit generally adopts a one-to-multiple mode due to unit power, namely, a plurality of refrigeration cases are configured outside one outdoor condensing unit.
Because the types or the delivery amounts of the articles placed by different refrigerated cabinets are different, the shutdown time for achieving the target set temperature is different, the existing refrigerated showcases are stopped at the set temperature, and the load of the existing refrigerated showcases is larger and the phenomenon that the shutdown temperature is not met for continuous operation is avoided. In the process of starting and stopping the refrigerated cabinets, the load of the whole system is greatly changed, the whole refrigerating system is greatly fluctuated, the evaporating side area is reduced due to the fact that one or more refrigerated cabinets are stopped, the evaporating pressure of the outside condensing unit is suddenly reduced, the unit compressor is stopped in a low-pressure protection mode, the refrigerating effect of the running refrigerated display cabinet is poor, the temperature in the cabinet is fluctuated, and the temperature control effect is poor. The compressor trigger protection of the outside condensing unit affects the operation life of the compressor.
Aiming at the problems, no effective solution is provided at present to solve the problems, and the operation of the whole unit system is maintained under the condition that the service life reliability of the unit is sacrificed only by frequently starting and stopping the compressor of the outside condensing unit.
Disclosure of Invention
The invention provides a control method of an air conditioning unit, which solves the problem that a compressor is frequently started and stopped.
In order to achieve the technical purpose, the invention is realized by adopting the following technical scheme:
the control method of the air conditioning unit comprises an outdoor unit and a plurality of indoor units, wherein each indoor unit is connected with the outdoor unit respectively; the control method comprises the following steps:
periodically detecting the evaporation pressure;
when the evaporation pressure is reduced and the change rate is greater than the change rate threshold, controlling the compressor to reduce the frequency;
when the evaporating pressure rises and the change rate is larger than the change rate threshold value, the compressor is controlled to rise.
In some embodiments of the present application, when the compressor is controlled to reduce the frequency, the target operating frequency N1 of the compressor is:
N1=k1*Nqyc*（Psqyc-Psdq）/Psqyc；
Wherein,
K1, which is a correction coefficient;
Nqyc, which is the compressor operating frequency of the last detection period;
psqyc, which is the evaporation pressure detection value of the previous detection period;
psdq, which is the evaporation pressure detection value of the current detection period.
In some embodiments of the present application, when the compressor is controlled to increase frequency, the target operating frequency N2 of the compressor is:
N2=k2*Nqyc*Psdq/Psqyc；
Wherein,
K2 is a correction coefficient;
Nqyc, which is the compressor operating frequency of the last detection period;
psqyc, which is the evaporation pressure detection value of the previous detection period;
psdq, which is the evaporation pressure detection value of the current detection period.
In some embodiments of the present application, the rate of change threshold is a preset fixed value; or alternatively
Change rate threshold = K3 Ps1;
Wherein,
K3, which is a correction coefficient;
ps1 is the evaporation pressure change rate when all indoor units are operated.
In some embodiments of the present application, when the compressor is controlled to down-convert, the compressor is controlled to down-convert at a second speed;
When the control compressor increases the frequency, the control compressor increases the frequency at a second speed;
wherein the second speed > the first speed;
The first speed is the frequency raising or reducing speed of the compressor when all the indoor units are operated.
The air conditioning unit control system comprises an outdoor unit and a plurality of indoor units, wherein each indoor unit is connected with the outdoor unit respectively; the control system includes:
The evaporation pressure detection module is used for periodically detecting the evaporation pressure;
a calculation module for calculating a rate of change of the evaporation pressure;
a judging module for
When the evaporation pressure is reduced and the change rate is greater than the change rate threshold, controlling the compressor to reduce the frequency;
when the evaporating pressure rises and the change rate is larger than the change rate threshold value, the compressor is controlled to rise.
In some embodiments of the present application, the air conditioning unit control system further includes:
the target operating frequency calculation module is used for calculating a target operating frequency N1 when the compressor is in frequency reduction;
N1=k1*Nqyc*（Psqyc-Psdq）/Psqyc；
Wherein,
K1, which is a correction coefficient;
Nqyc, which is the compressor operating frequency of the last detection period;
psqyc, which is the evaporation pressure detection value of the previous detection period;
psdq, which is the evaporation pressure detection value of the current detection period.
The method is also used for calculating a target operating frequency N2 when the compressor is in frequency up;
N2=k2*Nqyc*Psdq/Psqyc；
Wherein,
K2 is a correction coefficient;
Nqyc, which is the compressor operating frequency of the last detection period;
psqyc, which is the evaporation pressure detection value of the previous detection period;
psdq, which is the evaporation pressure detection value of the current detection period.
In some embodiments of the present application, the air conditioning unit control system further includes:
a change rate threshold calculation module, configured to calculate a change rate threshold=k3×ps1;
Wherein,
K3, which is a correction coefficient;
ps1 is the evaporation pressure change rate when all indoor units are operated.
An air conditioning unit comprising:
An outdoor unit;
each indoor unit is connected with the outdoor unit respectively;
a controller for performing the air conditioning unit control method according to any one of claims 1 to 5.
In some embodiments of the application, the indoor unit is disposed within a refrigerated display cabinet.
Compared with the prior art, the invention has the advantages and positive effects that: according to the air conditioning unit control method, the control system and the air conditioning unit, the evaporation pressure is periodically detected, and when the evaporation pressure is detected to be reduced and the change rate of the evaporation pressure is greater than the change rate threshold value, the compressor is controlled to reduce the frequency; when the increase of the evaporation pressure is detected, and the change rate of the evaporation pressure is larger than a change rate threshold value, controlling the compressor to increase frequency; the low-pressure protection stop of the compressor is avoided, the air conditioning effect is ensured, the problem that the compressor is frequently started and stopped is solved, the temperature control precision of the indoor unit is improved, and the reliability of the air conditioning unit is improved.
Other features and advantages of the present invention will become more apparent from the following detailed description of embodiments of the present invention, which is to be read in connection with the accompanying drawings.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic view of an air conditioning unit according to the present invention;
FIG. 2 is a flow chart of one embodiment of a method of controlling an air conditioning unit in accordance with the present invention;
fig. 3 is a block diagram of an embodiment of an air conditioning unit control system according to the present invention.
Reference numerals:
TV1, thermal expansion valve; TV2, thermal expansion valve; TVn thermostatic expansion valves;
EV1, electromagnetic valve; EV2, solenoid valve; EVn, solenoid valve;
J1, a liquid pipe stop valve; j2, an air pipe stop valve;
a Sensor, low pressure Sensor;
A Switch, high voltage Switch;
Filter, dry Filter;
G. a liquid-viewing mirror.
Detailed Description
The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
In the description of the present application, it should be understood that the terms "center," "upper," "lower," "front," "rear," "top," "bottom," "inner," "outer," and the like indicate orientations or positional relationships based on the orientation or positional relationships shown in the drawings, merely to facilitate description of the present application and simplify the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be configured and operated in a particular orientation, and thus should not be construed as limiting the present application.
In the description of the present application, it should be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present application, unless otherwise indicated, the meaning of "a plurality" is two or more.
In the description of the present application, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present application will be understood in specific cases by those of ordinary skill in the art.
Aiming at the problem of frequent start and stop of a compressor, the invention provides an air conditioning unit control method, an air conditioning unit control system and an air conditioning unit, which solve the problem of frequent start and stop of the compressor and improve the temperature control effect of the air conditioning unit. The air conditioning unit control method, the air conditioning unit control system and the air conditioning unit according to the present invention will be described in detail with reference to the accompanying drawings.
Embodiment 1,
The air conditioning unit comprises an outdoor unit and a plurality of indoor units. The indoor units are connected in parallel, and each indoor unit is connected with the outdoor unit respectively. The liquid pipe of each indoor unit is connected with the liquid pipe of the outdoor unit respectively, and the air pipe of each indoor unit is connected with the air pipe of the outdoor unit respectively, as shown in fig. 1.
The outdoor unit comprises a compressor, an outdoor heat exchanger, a high-pressure liquid storage device, a gas-liquid separator, a high-pressure Switch, a drying Filter, a liquid viewing mirror G, a low-pressure Sensor, a liquid pipe stop valve J1, a gas pipe stop valve J2 and the like.
The liquid pipe of each indoor unit is provided with a thermal expansion valve and an electromagnetic valve. The thermal expansion valve is used for throttling the refrigerant; the electromagnetic valve is controlled by the controller to act, and when the actual temperature reaches the target value, the electromagnetic valve is closed.
A liquid pipe of the indoor unit 1 is provided with a thermal expansion valve TV1 and a solenoid valve EV1;
a liquid pipe of the indoor unit 2 is provided with a thermal expansion valve TV2 and a solenoid valve EV2;
……；
the liquid pipe of the indoor unit N is provided with a thermal expansion valve TVn and a solenoid valve EVn.
The outdoor unit is provided with a variable-frequency compressor, the frequency of the compressor can be automatically adjusted to raise or lower the frequency according to the target evaporation pressure Ps0 of the system, and the air conditioning unit is ensured to run within the range of the target evaporation pressure deviation deltaPs.
The low-pressure Sensor can detect the real-time evaporation pressure Ps of the operation of the air conditioning unit in real time, compares the real-time evaporation pressure Ps with the target evaporation pressure Ps0, and controls the frequency-increasing or frequency-decreasing action of the compressor so that the evaporation pressure of the air conditioning unit is between Ps 0-deltaPs and Ps0+ deltaPs to run stably.
According to the air conditioning unit control method, the evaporation pressure is periodically detected; when the evaporation pressure is detected to be reduced, and the change rate (reduction rate) of the evaporation pressure is larger than the change rate threshold value, controlling the compressor to reduce the frequency; when an increase in the evaporating pressure is detected, and the rate of change of the evaporating pressure (rate of increase) is greater than the rate of change threshold, the compressor is controlled to increase in frequency.
The control method of the air conditioning unit mainly comprises the following steps, and is shown in fig. 2.
And in the running process of the air conditioning unit, the evaporation pressure is periodically detected by using a low-pressure Sensor.
Step S1: the evaporation pressure was measured.
Step S2: the difference between the evaporation pressure detected in the present detection period and the evaporation pressure detected in the last detection period is calculated, and the rate of change of the evaporation pressure is calculated.
Difference = evaporation pressure detected in the present detection period-evaporation pressure detected in the last detection period;
rate of change = absolute value of difference/detection period T.
Step S3: and controlling the operation of the compressor according to the difference value and the change rate.
When the difference is smaller than 0 and the change rate (reduction rate) is larger than the change rate threshold, the evaporation pressure is rapidly reduced, and the compressor is controlled to rapidly reduce the frequency, so that the compressor is prevented from triggering low-pressure protection to stop.
When the difference is greater than 0 and the change rate (rising rate) is greater than the change rate threshold, the evaporation pressure is rapidly increased, and the compressor is controlled to rapidly increase the frequency, so that the air conditioning effect is prevented from being deteriorated.
According to the air conditioning unit control method, the evaporation pressure is periodically detected, and when the evaporation pressure is detected to be reduced and the change rate of the evaporation pressure is greater than the change rate threshold value, the compressor is controlled to reduce the frequency; when the increase of the evaporation pressure is detected, and the change rate of the evaporation pressure is larger than a change rate threshold value, controlling the compressor to increase frequency; the low-pressure protection stop of the compressor is avoided, the air conditioning effect is ensured, the problem that the compressor is frequently started and stopped is solved, the temperature control precision of the indoor unit is improved, and the reliability of the air conditioning unit is improved.
In some embodiments of the present application, when the rate of decrease of the evaporating pressure is greater than the rate threshold, the target operating frequency N1 of the compressor is:
N1=k1*Nqyc*（Psqyc-Psdq）/Psqyc；
Wherein,
K1 is a correction coefficient. 0 < k 1.ltoreq.1, k1 may take any one of the values in the above range. Of course, the value of k1 can be optimized and adjusted according to the actual situation.
Nqyc, which is the compressor operating frequency of the last detection period; i.e., the compressor operating frequency before the vapor pressure suddenly changes.
Psqyc, which is the evaporation pressure detection value of the previous detection period.
Psdq, which is the evaporation pressure detection value of the current detection period.
According to the compressor operating frequency of the last detection period and the reduction percentage of the evaporating pressure, the target operating frequency of the compressor is determined, and the reasonable target operating frequency of the compressor can be determined, so that the compressor is prevented from being stopped.
In some embodiments of the present application, when the rate of increase of the evaporating pressure is greater than the rate threshold, and the compressor is controlled to increase in frequency, the target operating frequency N2 of the compressor is:
N2=k2*Nqyc*Psdq/Psqyc；
Wherein,
K2 is a correction coefficient. 1.ltoreq.k2.ltoreq.2, and k2 may take any one of the values within the above-mentioned ranges. Of course, the value of k2 can be optimized and adjusted according to the actual situation.
Nqyc, which is the compressor operating frequency of the last detection period; i.e., the compressor operating frequency before the vapor pressure suddenly changes.
Psqyc, which is the evaporation pressure detection value of the previous detection period.
Psdq, which is the evaporation pressure detection value of the current detection period.
According to the compressor operating frequency of the last detection period and the evaporation pressure ratio of the current detection period and the last detection period, the target operating frequency of the compressor is determined, the reasonable target operating frequency of the compressor can be determined, and the refrigerating effect of the air conditioning unit is ensured.
In some embodiments of the present application, the change rate threshold is a preset fixed value, which is simple and convenient, and can directly determine whether the compressor needs to be up-converted or down-converted.
In other embodiments of the present application, the rate of change threshold = K3 Ps1;
Wherein,
K3 is a correction coefficient. 1 < K3 < 3, K3 may take any of the values in the above ranges. Of course, the value of k3 can be optimized and adjusted according to the actual situation. In some embodiments of the application, k3=2. I.e. the rate of change threshold = 2 x ps1.
Ps1 is the evaporation pressure change rate when all indoor units are operated.
When the indoor unit is fully started to operate, the low-pressure Sensor of the outdoor unit detects the evaporation low-pressure Ps of the air conditioning unit in real time, calculates the evaporation low-pressure change rate Ps1 when the indoor unit is fully started, and controls the compressor to operate at the speed of the first speed L1 (unit Hz/s) in an ascending or descending way, so that the evaporation pressure of the air conditioning unit is between Ps 0-deltaPs and Ps 0+deltaPs to operate stably.
The change rate Ps 1= | (the evaporation pressure detection value of the current detection period-the evaporation pressure detection value of the last detection period)/the detection period t|, that is, the change rate Ps1 is an absolute value after calculating the change difference value per unit time.
The detection period T defaults to 0.5 seconds.
In some embodiments of the present application, k3=2, i.e. the rate of change threshold=2×ps1.
By determining the change rate threshold value through the change rate Ps1, a more accurate change rate threshold value can be determined according to the actual operation of the air conditioning unit.
In some embodiments of the present application,
And when the compressor is controlled to reduce the frequency, controlling the compressor to reduce the frequency at a second speed L2, namely controlling the compressor to reduce the frequency rapidly, and preventing the compressor from triggering low-voltage protection stop.
When the compressor is controlled to raise the frequency, the compressor is controlled to raise the frequency at the second speed L2, i.e. the compressor is controlled to raise the frequency fast, so as to prevent the air conditioning effect from being deteriorated.
Wherein the second speed > the first speed; the first speed is the frequency raising or reducing speed of the compressor when all the indoor units are operated. I.e. the first speed is the normal running fm speed and the second speed is the pressure shock fm speed.
In some embodiments of the application, the indoor unit is arranged in the refrigerated cabinet, and the air conditioning unit operates in a refrigerating mode to provide cooling capacity for the refrigerated cabinet. That is, one outdoor unit drives a plurality of refrigerated cabinets to refrigerate the refrigerated cabinets.
The indoor side is provided with a plurality of refrigeration display cabinet bodies according to the commercial and super practical application requirements, and a thermal expansion valve (namely a thermal expansion valve on a liquid pipe of an indoor unit) is arranged on a liquid pipe pipeline of each refrigeration display cabinet body to throttle a refrigerant; the electromagnetic valve is controlled by a refrigeration display cabinet controller (i.e. an indoor unit controller), when the real-time cabinet temperature T is smaller than a target set value (Ts-delta T), the electromagnetic valve is controlled to be closed, namely the refrigeration display cabinet reaches the target set value, the electromagnetic valve is closed, the liquid pipe is cut off for supplying liquid, the refrigeration display cabinet is withdrawn from the system operation, namely the evaporation side area of the whole system is reduced at the moment, the evaporation pressure of the whole system is rapidly reduced due to the instant of liquid supply of the liquid pipe, the compressor triggering protection stop of conventional products is generated, and the temperature control precision of the running refrigeration display cabinet is poor; when the temperature T of the real-time cabinet is > (Ts+DeltaT), the temperature of the refrigerated display cabinet is higher, the corresponding electromagnetic valve of the refrigerated display cabinet is controlled to be opened, and the liquid supply at the liquid pipe side is recovered for refrigeration operation.
Ts: the target temperature control temperature set by the refrigeration showcase controller is different in different cabinet numerical value set values.
Δt: the temperature control precision value set by the refrigeration showcase controller is different from the numerical value set value of the different cases.
In the continuous operation process of the air conditioning unit, part of the refrigeration showcases gradually reach the set target warehouse temperature and stop to close the electromagnetic valve, if the evaporation low-pressure change rate at the moment is more than 2x Ps1 and the evaporation pressure detection value Psdq in the detection period is smaller than the evaporation pressure detection value Psqyc in the previous detection period, namely the rapid reduction of the evaporation pressure is detected, the compressor is controlled to rapidly reduce the frequency according to the speed of the second speed L2Hz/s, and the frequency of the frequency reduction target of the compressor is N1=k1 x Nqyc (Psqyc-Psdq)/Psqyc. The quick frequency reduction is realized, the compressor is prevented from triggering low-voltage protection stop caused by the closing of the indoor side refrigeration showcase, and further the influence of refrigeration interruption on the temperature control precision and the reliability of the compressor of the operation showcase caused by the stop of the compressor is avoided.
In the continuous operation process of the air conditioning unit, the temperature of the refrigeration showcase with partial shutdown is increased, the electromagnetic valve is opened after the opening condition is triggered, and if the evaporation low pressure change rate at the moment is more than 2 Ps1 and the evaporation pressure detection value Psdq of the detection period is more than the evaporation pressure detection value Psqyc of the previous detection period, namely the rapid increase of the evaporation pressure is detected, the compressor is controlled to be rapidly increased according to the speed of the second speed L2Hz/s, and the target frequency of the compressor frequency increase is N2=k2× Nqyc × Psdq/Psqyc. The quick frequency raising is realized, and the stopped refrigerated showcase is started again to be put into operation, so that the quick temperature lowering is realized in a quick frequency raising mode, and the effect of the rerun cabinet body is prevented from being poor due to insufficient cooling.
According to the air conditioning unit control method, the influence of frequent triggering protection start-stop of the compressor on the service life is avoided, meanwhile, the temperature control precision of the refrigeration display cabinet is improved, and the quality of the refrigeration product is improved.
The air conditioning unit control method of the embodiment improves the reliability of products and prolongs the service life of the unit; and the temperature control precision of the indoor unit is improved, and the product quality is improved.
Embodiment II,
Based on the design of the air conditioning unit control method in the first embodiment, the second embodiment provides an air conditioning unit control system.
The air conditioning unit comprises an outdoor unit and a plurality of indoor units, and each indoor unit is connected with the outdoor unit respectively, as shown in fig. 1.
The air conditioning unit control system of the present embodiment includes an evaporation pressure detection module, a calculation module, a judgment module, and the like, as shown in fig. 3.
And the evaporation pressure detection module is used for periodically detecting the evaporation pressure.
And the calculation module is used for calculating the change rate of the evaporation pressure.
A judging module for
When the evaporation pressure is reduced and the change rate is greater than the change rate threshold, controlling the compressor to reduce the frequency;
when the evaporating pressure rises and the change rate is larger than the change rate threshold value, the compressor is controlled to rise.
In some embodiments of the present application, the air conditioning unit control system further includes a target operating frequency calculation module.
The target operating frequency calculation module is used for calculating a target operating frequency N1 when the compressor is in frequency reduction;
N1=k1*Nqyc*（Psqyc-Psdq）/Psqyc；
Wherein,
K1 is a correction coefficient. 0 < k 1.ltoreq.1, k1 may take any one of the values in the above range. Of course, the value of k1 can be optimized and adjusted according to the actual situation.
Nqyc, which is the compressor operating frequency of the last detection period;
psqyc, which is the evaporation pressure detection value of the previous detection period;
psdq, which is the evaporation pressure detection value of the current detection period.
The target operating frequency calculation module is also used for calculating a target operating frequency N2 when the compressor is in frequency up;
N2=k2*Nqyc*Psdq/Psqyc；
Wherein,
K2 is a correction coefficient. 1.ltoreq.k2.ltoreq.2, and k2 may take any one of the values within the above-mentioned ranges. Of course, the value of k2 can be optimized and adjusted according to the actual situation.
Nqyc, which is the compressor operating frequency of the last detection period;
psqyc, which is the evaporation pressure detection value of the previous detection period;
psdq, which is the evaporation pressure detection value of the current detection period.
In some embodiments of the present application, the air conditioning unit control system further includes a rate of change threshold calculation module.
A change rate threshold calculation module, configured to calculate a change rate threshold=k3×ps1;
Wherein,
K3 is a correction coefficient. 1 < K3 < 3, K3 may take any of the values in the above ranges. Of course, the value of k3 can be optimized and adjusted according to the actual situation.
Ps1 is the evaporation pressure change rate when all indoor units are operated.
The working process of the specific air conditioning unit control system is described in detail in the air conditioning unit control method of the first embodiment, and will not be described here again.
According to the air conditioning unit control system, the evaporation pressure is periodically detected, and when the evaporation pressure is detected to be reduced and the change rate of the evaporation pressure is greater than the change rate threshold value, the compressor is controlled to reduce the frequency; when the increase of the evaporation pressure is detected, and the change rate of the evaporation pressure is larger than a change rate threshold value, controlling the compressor to increase frequency; the low-pressure protection stop of the compressor is avoided, the air conditioning effect is ensured, the problem that the compressor is frequently started and stopped is solved, the temperature control precision of the indoor unit is improved, and the reliability of the air conditioning unit is improved.
Third embodiment,
Based on the design of the control method of the air conditioning unit according to the first embodiment, the third embodiment provides an air conditioning unit, which includes an outdoor unit, a plurality of indoor units, and a controller; each indoor unit is connected with the outdoor unit respectively; see fig. 1.
And a controller for executing the air conditioning unit control method of the first embodiment.
According to the air conditioning unit, the evaporation pressure is periodically detected, and when the evaporation pressure is detected to be reduced and the change rate of the evaporation pressure is greater than the change rate threshold value, the compressor is controlled to reduce the frequency; when the increase of the evaporation pressure is detected, and the change rate of the evaporation pressure is larger than a change rate threshold value, controlling the compressor to increase frequency; the low-pressure protection stop of the compressor is avoided, the air conditioning effect is ensured, the problem that the compressor is frequently started and stopped is solved, the temperature control precision of the indoor unit is improved, and the reliability of the air conditioning unit is improved.
In some embodiments of the application, the indoor unit is disposed within a refrigerated display cabinet. When the evaporation pressure is reduced and the change rate of the evaporation pressure is larger than the change rate threshold value, controlling the compressor to reduce the frequency; when the evaporating pressure rises and the evaporating pressure change rate is larger than the change rate threshold value, controlling the compressor to raise the frequency; the low-voltage protection stop is avoided from being triggered by the compressor, the refrigeration effect of the refrigeration showcase is ensured, and the temperature control precision and reliability of the refrigeration showcase are improved.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (7)
1. The control method of the air conditioning unit comprises an outdoor unit and a plurality of indoor units, wherein each indoor unit is connected with the outdoor unit respectively; the method is characterized in that: the control method comprises the following steps:
periodically detecting the evaporation pressure;
when the evaporation pressure is reduced and the change rate is greater than the change rate threshold, controlling the compressor to reduce the frequency;
when the evaporation pressure rises and the change rate is greater than the change rate threshold, controlling the compressor to raise the frequency;
When the compressor is controlled to reduce the frequency, the target operating frequency N1 of the compressor is as follows:
N1=k1*Nqyc*（Psqyc-Psdq）/Psqyc；
Wherein,
K1, which is a correction coefficient;
Nqyc, which is the compressor operating frequency of the last detection period;
psqyc, which is the evaporation pressure detection value of the previous detection period;
psdq, which is the evaporation pressure detection value of the current detection period;
when the control compressor is in frequency up-conversion, the target operating frequency N2 of the compressor is as follows:
N2=k2*Nqyc*Psdq/Psqyc；
Wherein,
K2 is a correction coefficient;
Nqyc, which is the compressor operating frequency of the last detection period;
psqyc, which is the evaporation pressure detection value of the previous detection period;
psdq, which is the evaporation pressure detection value of the current detection period.
2. The air conditioning unit control method according to claim 1, wherein:
the change rate threshold is a preset fixed value; or alternatively
Change rate threshold = K3 Ps1;
Wherein,
K3, which is a correction coefficient;
ps1 is the evaporation pressure change rate when all indoor units are operated.
3. The air conditioning unit control method according to any one of claims 1 to 2, characterized in that:
when the control compressor is in frequency reduction, the control compressor is in frequency reduction at a second speed;
When the control compressor increases the frequency, the control compressor increases the frequency at a second speed;
wherein the second speed > the first speed;
The first speed is the frequency raising or reducing speed of the compressor when all the indoor units are operated.
4. The air conditioning unit control system comprises an outdoor unit and a plurality of indoor units, wherein each indoor unit is connected with the outdoor unit respectively; the method is characterized in that: the control system includes:
The evaporation pressure detection module is used for periodically detecting the evaporation pressure;
a calculation module for calculating a rate of change of the evaporation pressure;
a judging module for
When the evaporation pressure is reduced and the change rate is greater than the change rate threshold, controlling the compressor to reduce the frequency;
when the evaporation pressure rises and the change rate is greater than the change rate threshold, controlling the compressor to raise the frequency;
the air conditioning unit control system further includes:
the target operating frequency calculation module is used for calculating a target operating frequency N1 when the compressor is in frequency reduction;
N1=k1*Nqyc*（Psqyc-Psdq）/Psqyc；
Wherein,
K1, which is a correction coefficient;
Nqyc, which is the compressor operating frequency of the last detection period;
psqyc, which is the evaporation pressure detection value of the previous detection period;
psdq, which is the evaporation pressure detection value of the current detection period;
the method is also used for calculating a target operating frequency N2 when the compressor is in frequency up;
N2=k2*Nqyc*Psdq/Psqyc；
Wherein,
K2 is a correction coefficient;
Nqyc, which is the compressor operating frequency of the last detection period;
psqyc, which is the evaporation pressure detection value of the previous detection period;
psdq, which is the evaporation pressure detection value of the current detection period.
5. The air conditioning unit control system of claim 4, wherein: the air conditioning unit control system further includes:
a change rate threshold calculation module, configured to calculate a change rate threshold=k3×ps1;
Wherein,
K3, which is a correction coefficient;
ps1 is the evaporation pressure change rate when all indoor units are operated.
6. An air conditioning unit, characterized in that: comprising the following steps:
An outdoor unit;
each indoor unit is connected with the outdoor unit respectively;
a controller for performing the air conditioning unit control method according to any one of claims 1 to 3.
7. The air conditioning assembly of claim 6, wherein: the indoor unit is arranged in the refrigeration showcase.
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