CN115435471A - Multi-split air conditioner control method and system and air conditioner - Google Patents
Multi-split air conditioner control method and system and air conditioner Download PDFInfo
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- CN115435471A CN115435471A CN202211130205.2A CN202211130205A CN115435471A CN 115435471 A CN115435471 A CN 115435471A CN 202211130205 A CN202211130205 A CN 202211130205A CN 115435471 A CN115435471 A CN 115435471A
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- 238000012937 correction Methods 0.000 claims description 27
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- 238000001514 detection method Methods 0.000 claims description 3
- 238000011161 development Methods 0.000 claims description 3
- 238000004378 air conditioning Methods 0.000 claims 2
- 230000003247 decreasing effect Effects 0.000 claims 2
- 239000003507 refrigerant Substances 0.000 description 21
- 230000005494 condensation Effects 0.000 description 15
- 238000009833 condensation Methods 0.000 description 15
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- 230000000694 effects Effects 0.000 description 5
- 238000010586 diagram Methods 0.000 description 3
- 238000001816 cooling Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000010977 unit operation Methods 0.000 description 2
- 230000003044 adaptive effect Effects 0.000 description 1
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/62—Control or safety arrangements characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values
- F24F11/63—Electronic processing
- F24F11/64—Electronic processing using pre-stored data
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/70—Control systems characterised by their outputs; Constructional details thereof
- F24F11/72—Control systems characterised by their outputs; Constructional details thereof for controlling the supply of treated air, e.g. its pressure
- F24F11/74—Control systems characterised by their outputs; Constructional details thereof for controlling the supply of treated air, e.g. its pressure for controlling air flow rate or air velocity
- F24F11/77—Control systems characterised by their outputs; Constructional details thereof for controlling the supply of treated air, e.g. its pressure for controlling air flow rate or air velocity by controlling the speed of ventilators
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/70—Control systems characterised by their outputs; Constructional details thereof
- F24F11/80—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air
- F24F11/83—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air by controlling the supply of heat-exchange fluids to heat-exchangers
- F24F11/84—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air by controlling the supply of heat-exchange fluids to heat-exchangers using valves
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/70—Control systems characterised by their outputs; Constructional details thereof
- F24F11/80—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air
- F24F11/86—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air by controlling compressors within refrigeration or heat pump circuits
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Abstract
The invention provides a control method and a control system of a multi-split air conditioner and the air conditioner, wherein the control method of the multi-split air conditioner comprises the following steps: s1: starting up and refrigerating the multi-split system, and detecting a starting-up load rate out and an outdoor environment temperature Tao; s2: in the soft start stage, determining the rotating speed of an outer fan and the initial valve step of an inner machine; s3: collecting the slope of pressure drop during the operation of the soft start stage, predicting the low pressure value at the end of the soft start, and correcting the valve step of the internal machine and the frequency of the soft start compressor if the predicted low pressure value is too low. According to the control method of the multi-split air conditioner, the starting and stopping of the outer fan are controlled by adopting high pressure PH at the low ambient temperature starting stage through the starting load rate and the outdoor ambient temperature, when the high ambient temperature is started, the windshield is divided according to the environment temperature and the starting load, the initial valve step of the inner fan is divided in a gridding mode, and the valve step of the inner fan and the soft starting frequency are corrected through predicting the low pressure value of the ending of the soft starting, so that the normal starting of the unit is realized.
Description
Technical Field
The invention relates to the technical field of air conditioners, in particular to a control method and a control system of a multi-split air conditioner and the air conditioner.
Background
At present, after soft start of a multi-split air conditioner is finished under the conditions of low-temperature refrigeration and small load (one minimum internal machine is singly started), the condition of low-voltage protection is easy to occur. The reason is as follows: firstly, different scenes are not distinguished in the unit soft start stage, the initial valve step of the internal unit is a fixed value, the internal unit is operated with the same starting frequency, the initial valve step is small (the valve step of the internal unit in the refrigeration operation shutdown is 0, cold energy waste is prevented), the refrigerant circulation volume is small and the frequency is high (the air suction volume of the compressor is greater than the refrigerant circulation volume), the low pressure in the soft start stage is continuously reduced, the pressure difference is slowly established, the refrigerant circulation volume is increased, the low pressure is gradually increased (response capability is poor), and low pressure protection is easy to occur in the period. And secondly, the outer fan only carries out grading corresponding to different rotating speeds according to the environment temperature, the refrigeration and heating modes are not distinguished, the outer machine is used as a condenser during low-temperature refrigeration, the internal pressure of the system is low during shutdown, and the low-environment-temperature condensation effect is good. And in the starting stage, the external machine is started, the high pressure is rapidly reduced, the system pressure difference is small, the circulation quantity of the refrigerant is reduced, the refrigerant is condensed in the external machine and deposited in the condenser or the high-pressure liquid storage device, the liquid shortage on the suction side is caused, the low-pressure switch is triggered, and the external machine is stopped in a fault manner.
Disclosure of Invention
In view of the above, the present invention is directed to a control method, a control system and an air conditioner for a multi-split air conditioner, so as to solve the problem of low-voltage protection after the soft start of the multi-split air conditioner is finished under the conditions of low-temperature refrigeration and small-load start.
In order to achieve the purpose, the technical scheme of the invention is realized as follows:
a control method of a multi-split air conditioner comprises the following steps:
s1: starting up and refrigerating the multi-split system, and detecting a starting-up load rate out and an outdoor environment temperature Tao;
s2: in the soft start stage, determining the rotating speed of an outer fan and the initial valve step of an inner machine;
s3: collecting the slope of pressure drop during the operation of the soft start stage, predicting the low pressure value at the end of the soft start, and correcting the valve step of the internal machine and the frequency of the soft start compressor if the predicted low pressure value is too low.
Further, in step S2, tao ≦ T 1 When the refrigeration is started, the start and stop of the fan are controlled through high pressure; at Tao > T 1 When refrigeration is started, dividing the outdoor environment temperature Tao and the starting load rate out according to the running rotating speed of the external fan, wherein the higher the starting load rate out is, the faster the rotating speed of the outdoor fan is; the higher the outdoor ambient temperature Tao, the faster the outdoor fan speed, wherein T 1 A pre-set chamber ambient temperature threshold.
Further, in step S2, the internal initial valve step decreases as the startup load rate out increases, and decreases as the outdoor ambient temperature Tao increases.
Further, the specific step of controlling the start and stop of the fan through high pressure in the step S2 includes:
S2A1: if the high pressure PH is not less than PH 1 Then, the operation is carried out according to the highest rotating speed at the outdoor environment temperature Tao;
S2A2: if the high pressure PH is less than or equal to PH 0 If so, the outdoor unit stops rotating;
S2A3: if pH is above 0 pH < pH under high pressure 1 And then the outer fan is started to operate according to the lowest rotating speed.
Further, in step S2, the rotation speed of the external fan and the assignment of the initial valve step of the internal fan are obtained by looking up a table according to the startup load rate out and the outdoor ambient temperature Tao.
Further, in step S3, the following steps are included:
s31: acquisition of Soft Start phase operation t 1 Low pressure P of 1 And t 2 Low pressure P of 2 ；
S32: calculating the pressure drop Δ P 1 ＝P 1 -P 2 Estimating the low pressure P at the end of the soft start from a linear relationship 4 ；
S33: judging whether P is present 4 ＜P Protection of If yes, executing step S34; if not, executing S38;
s34: the first correction is carried out on the inner valve step by step, and the correction formula is as follows:
target valve step M of internal machine 0 = current valve step of inner machine M At present +(P Protection of -P 4 )*k；
Wherein M is 0 ≤M Threshold(s) ，M Threshold(s) Is the maximum threshold value, P, of the target valve step of the internal machine Protection of K is a periodic valve opening coefficient t for presetting a low-pressure protection value 2 And t 1 Is the development period t Period of time ；
S38: the internal valve steps are not corrected.
Further, after step S34, the method further includes the following steps:
s35: operation t 2 +t Period of time At the same time, the low pressure is collected and recorded as P 3 Calculate the sum of this time and t 2 Pressure drop Δ P in time 2 ＝P 2 -P 3 Then, the low pressure P at the end of the soft start is estimated according to the linear relation 5 ；
S36: judging whether P is present 5 ＜P Protection of If yes, go to step S37; if not, executing S38;
s37: and reducing the frequency of the compressor to the lowest operation frequency, and performing secondary correction of the internal valve step on the basis of the primary correction again, wherein the formula of the secondary correction is consistent with that in the step S34.
Further, t 1 Is 90s,t Period of time Is 30s Protection of Is 0.5bar, k is 300, M Threshold(s) Is 480.
Compared with the prior art, the control method of the multi-split air conditioner has the following advantages:
(1) According to the control method of the multi-split air conditioner, the starting and stopping of the outer fan are controlled by high pressure PH in a low environment temperature starting stage through the starting load rate and the outdoor environment temperature, when the high environment temperature is started, the windshield is divided according to the environment temperature and the starting load, the initial valve step of the inner fan is divided in a gridding mode, then the low pressure early warning function is used for predicting the low pressure value of the soft start end, the valve step and the soft start frequency of the inner fan are corrected in time, the condition that low pressure protection occurs in small load starting under the low temperature refrigeration working condition is improved, and the normal starting of the unit is realized.
(2) According to the control method of the multi-split air conditioner, the unit operation scene is refined through the startup load rate and the ambient temperature, the initial valve steps of the inner unit are divided in a gridding mode, the low-pressure early warning function is adopted, the low-pressure value of the soft start end is predicted, the valve steps and the soft start frequency of the inner unit are corrected automatically, the adaptive capacity of the unit in a complex scene is improved, and the normal start of the unit is ensured.
Another object of the present invention is to provide a multi-split air conditioner control system, for performing the multi-split air conditioner control method as described above, including:
the detection module is used for detecting the outdoor environment temperature Tao and the startup load rate out of the multi-split air conditioner;
the obtaining module is used for determining the rotating speed assignment and the inner valve step assignment of the outer fan in the starting stage under the corresponding outdoor environment temperature Tao and the starting load rate out;
the correction module is used for calculating the target valve step of the internal machine by collecting the pressure difference after the soft start stage operates for the preset time t1, correcting the valve step of the internal machine and adjusting the operation frequency of the compressor;
and the execution module is used for performing refrigeration starting of the multi-split air conditioner according to the corrected target valve step of the inner fan, the running frequency of the compressor and the acquired rotating speed of the outer fan.
The third objective of the present invention is to provide an air conditioner, which includes at least one outdoor unit and a plurality of indoor units, and the air conditioner employs a control method for performing the multi-split air conditioner as described above when low-temperature cooling starts.
Compared with the prior art, the multi-split air conditioner control system, the air conditioner and the multi-split air conditioner control method have the same advantages, and the description is omitted.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
fig. 1 is a logic block diagram of a control method of a multi-split air conditioner according to an embodiment of the invention;
fig. 2 is a logic block diagram of the correction of the valve steps of the internal unit in the control method of the multi-split air conditioner according to the embodiment of the invention;
fig. 3 is a schematic diagram of an operation timing sequence of the internal machine valve step correction in the control method of the multi-split air conditioner according to the embodiment of the invention;
Detailed Description
In order to make the technical means, objectives and functions of the present invention easy to understand, embodiments of the present invention will be described in detail with reference to the specific drawings.
Example 1
As shown in fig. 1 to 2, the present invention discloses a control method of a multi-split air conditioner, comprising the steps of:
s1: starting and refrigerating the multi-split system, and detecting a starting load rate out and an outdoor environment temperature Tao;
s2: in the soft start stage, determining the rotating speed of an outer fan and the initial valve step of an inner machine;
wherein, tao is less than or equal to T 1 At the time of refrigeration start, T 1 Controlling the start and stop of a fan by high pressure for presetting a room environment temperature threshold; at Tao > T 1 When the refrigeration is started, the higher the starting load rate out is, the higher the rotating speed of the outdoor fan is; the higher the outdoor environment temperature Tao is, the faster the outdoor fan rotating speed is; the internal machine initial valve step is reduced when the starting load rate out is increased, and the internal machine initial valve step is reduced when the outdoor environment temperature Tao is increased;
s3: and predicting a low pressure value when the soft start is finished through a low pressure early warning function, and correcting the internal machine valve step and the soft start compressor frequency if the predicted low pressure value is too low.
According to the control method of the multi-split air conditioner, when the multi-split air conditioner is used for refrigerating, the startup load rate out and the outdoor environment temperature Tao are detected, the startup load rate out is the sum of the number of working units in the multi-split air conditioner operation/the number of working units capacity, the rotating speed assignment is carried out in the starting stage of an outer fan, the larger the startup load rate out is, after the soft start is finished, the higher the operating frequency of a compressor is, the system refrigerant circulation amount is large, the condensation load of an outer fan heat exchanger is increased, and the rotating speed of the outer fan with higher assignment is used for enhancing the heat exchange effect and preventing the problem of unit protection due to overhigh high-pressure PH; when the outdoor environment temperature Tao is higher, the condensation temperature is higher, when the unit operates to limit the highest condensation temperature, the heat exchange temperature difference is reduced (condensation temperature-environment temperature) along with the increase of the environment temperature, and the heat exchange efficiency is enhanced by increasing the rotating speed of the external fan; when the outdoor environment temperature Tao is low, the system pressure is low when the refrigeration is started, the outdoor unit serves as a condenser, the condensation effect is good, the starting and stopping of the fan are controlled through high pressure, the system is helped to quickly establish pressure difference, and low-pressure protection is avoided; and regarding the assignment of the initial valve step of the internal machine, when the startup load rate out is low, the refrigerant circulation amount is increased by increasing the initial valve step of the internal machine; when the startup load rate out is high, the number of the startup internal machines is large, and the refrigerant circulation volume is reduced by reducing the initial valve steps of the internal machines; when the outdoor environment temperature Tao is higher, the system establishes the pressure difference quickly, the refrigerant can circulate quickly, and the initial valve steps of the internal machine are properly reduced. According to the control method of the multi-split air conditioner, the rotating speed of an outdoor fan and the step of an internal machine initial valve are assigned according to the startup load rate out and the outdoor environment temperature Tao in the refrigeration starting stage, the low-pressure at the end of soft starting is predicted according to the low-pressure descending trend through the low-pressure early warning function, the normal starting of a unit is ensured by correcting the step of the internal machine initial valve and the running frequency of a compressor when the low-pressure is too low, and the fault shutdown caused by the frequent occurrence of low-pressure protection is avoided.
According to the control method of the multi-split air conditioner, the starting and stopping of the outer fan are controlled by adopting high pressure PH at the low ambient temperature starting stage through the starting load rate and the outdoor ambient temperature, when the high ambient temperature is started, the windshield is divided according to the environment temperature and the starting load, the initial valve step of the inner fan is divided in a gridding mode, then the low pressure early warning function is used for predicting the low pressure value of the end of soft starting, the valve step and the soft starting frequency of the inner fan are corrected in time, the condition that low pressure protection occurs in small load starting under the low temperature refrigeration working condition is improved, and the normal starting of the fan set is realized.
As a preferred example of the present invention, in step S3, the following steps are included:
s31: collecting soft start phase operation t 1 Low pressure P of 1 And t 2 Low pressure P of time 2 ；
S32: calculating the pressure drop Δ P 1 ＝P 1 -P 2 Estimating the low pressure P at the end of the soft start from a linear relationship 4 ；
S33: judging whether P is present 4 ＜P Protection of If yes, go to step S34; if not, executing S38;
s34: the first correction is carried out on the inner valve step by step, and the correction formula is as follows:
target valve step M of internal machine 0 = current valve step of inner machine M At present +(P Protection of -P 4 )*k；
Wherein, M 0 ≤M Threshold(s) ，M Threshold(s) Is the maximum threshold value, P, of the target valve step of the internal machine Protection of K is a periodic valve opening coefficient t for presetting a low-pressure protection value 2 And t 1 Is the development period t Period of time ；
S38: the internal valve steps are not corrected.
The setting discloses a mode of first correction of the valve steps of the internal machine, only acts on the starting stage, and avoids low-voltage protection during soft starting. By soft-starting in cooling operation for a preset time t 1 And then calculating the low-pressure drop to estimate the low-pressure at the end of the soft start, so as to avoid the inaccurate pressure drop linear relation caused by small refrigerant circulation amount when the system pressure difference is not established at the initial stage of the soft start, and therefore, selecting the operation t 1 And the back pressure drop difference, namely the pressure drop difference when the low pressure drops most quickly, can obtain a relatively accurate estimated low-pressure value when the soft start is finished according to the linear relation, so that the reliability of the automatic correction of the valve step of the internal machine is met.
Preferably, the step S3 further includes the steps of:
s35: operation t 2 +t Period of time At the time, the low pressure is collected and recorded as P 3 Calculate the sum of this time and t 2 Pressure drop Δ P of time 2 ＝P 3 -P 2 Then, the low pressure P at the end of the soft start is estimated according to the linear relation 5 ；
S36: judging whether P is present 5 ＜P Protection of If yes, go to step S37; if not, executing S38;
s37: and reducing the frequency of the compressor to the lowest operation frequency, and performing secondary correction of the internal valve step on the basis of the primary correction again, wherein the formula of the secondary correction is consistent with that in the step S34.
The compressor frequency is reduced through the step-by-step initial valve of the internal unit, and then the second correction is carried out, so that the valve step of the internal unit is autonomously corrected through the low-pressure early warning function of the multi-unit system, the self-adaptive capacity of the unit under a complex scene is improved, and the normal start of the unit is ensured.
As a preferred example of the present invention, the specific step of controlling the start and stop of the wind turbine by high pressure in step S2 includes:
S2A1: if the high pressure PH is not less than PH 1 Then the operation is carried out according to the highest rotating speed at the outdoor environment temperature Tao;
S2A2: if the high pressure PH is less than or equal to PH 0 If so, the outdoor unit stops rotating;
S2A3: if pH is above 0 pH < pH under high pressure 1 And then the outer fan is started to operate according to the lowest rotating speed.
As a preferred example of the present invention, in step S2, the external fan rotation speed and the assignment of the internal machine initial valve step are obtained by looking up a table according to the startup load rate out and the outdoor ambient temperature Tao.
As an example of the present invention, T 1 Is taken to be 22 ℃, t 1 Is 90s,t Period of time Is 30s Protection of Is 0.5bar, k is 300, M Threshold(s) Is 480,PH 1 The value of (A) is 23bar 0 Is 18bar.
As an example of the present invention, the table of the correspondence between the operating speed of the external fan and the power-on load rate out and the outdoor ambient temperature Tao is as follows:
table 1: in the refrigeration starting stage, the running rotating speed of the external fan
As an example of the present invention, the corresponding table of the internal machine initial valve step and the startup load rate out and the outdoor ambient temperature Tao is as follows:
table 2: refrigerating operation, internal machine initial valve step
In the example of the present invention, the external fan operating speed assignment and the internal machine initial valve step given in tables 1 and 2 are exemplary illustrations, and are not used to limit the specific values of the external fan operating speed and the internal machine initial valve step.
As a preferred example of the present invention, the outer fan is operated at the maximum rotation speed at the outdoor ambient temperature Tao in the normal operation stage after the soft start is ended. This setting guarantees that the unit has higher heat exchange efficiency, also receives high-pressure PH control simultaneously, even when outdoor ambient temperature Tao is higher, after the soft start stage, the load changes, and the low-load also can normal operating.
The embodiment of the invention also discloses a multi-split air conditioner control system, which is used for executing the multi-split air conditioner control method and comprises the following steps:
the detection module is used for detecting the outdoor environment temperature Tao and the startup load rate out of the multi-split air conditioner;
the acquisition module is used for determining the rotating speed assignment and the internal valve step assignment of the external fan at the starting stage under the corresponding outdoor environment temperature Tao and the starting load rate out;
a correction module for operating for a preset time t by acquiring a soft start phase 1 Rear pressureCalculating the target valve step of the internal machine, correcting the valve step of the internal machine, and adjusting the running frequency of the compressor;
and the execution module is used for performing refrigeration starting on the multi-split air conditioner according to the corrected target valve step of the inner fan, the running frequency of the compressor and the acquired rotating speed of the outer fan.
The embodiment of the invention also discloses an air conditioner which comprises at least one outdoor unit and a plurality of indoor units, and the air conditioner adopts the multi-split air conditioner control method when low-temperature refrigeration is started.
Example 2
The invention discloses a control method of a multi-split air conditioner, which comprises the following specific implementation steps of:
(1) Outer fan starting stage speed assignment
The refrigeration starting stage is divided according to the outdoor environment temperature Tao and the starting load rate out (the sum of the number of running internal fans/the number of capacity of the external fan), and the external fan runs at a rotating speed.
The larger the startup load rate out is, the higher the running frequency of the compressor is after the soft start is finished, the large refrigerant circulation amount of the system is, the condensation load of the outer machine heat exchanger is increased, the rotating speed of the outer fan is improved, the heat exchange effect is enhanced, and the situation of unit protection caused by overhigh high-pressure PH is prevented.
Tao is higher, condensation temperature is higher, but in order to guarantee safe operation of the unit, the highest condensation temperature of the unit is generally limited to be less than 65 ℃, and along with the increase of ambient temperature, the heat exchange temperature difference is reduced (condensation temperature-ambient temperature), so that under the same condensation load, the rotating speed of an outer fan needs to be increased at a lower annular temperature, and the heat exchange efficiency is enhanced. Meanwhile, tao is higher, the system pressure is higher (when the machine is stopped, the refrigerant in the outer machine heat exchanger exchanges heat with the environment fully, the high pressure of the refrigerant is equal to the saturation pressure of the refrigerant corresponding to the ring temperature), the high pressure is high under the condition of lower ring temperature, the time for establishing the same pressure difference is shortened, meanwhile, the high pressure is too high in a short time, the running speed of the outer fan in the starting stage is properly increased, and the normal running of the machine set is ensured.
When the temperature is higher than or equal to 22 ℃, the system pressure is low when the refrigeration is started, the outdoor unit serves as a condenser, the condensation effect is good, if a fan is started, the high pressure is reduced, the establishment of the system pressure difference is not facilitated, the refrigerant circulation is poor, and the low-pressure protection is easy to occur.
Therefore, the starting stage adopts high pressure PH control, the fan is turned on when the high pressure of the system reaches a preset value, the system pressure difference is quickly established, and the refrigerant circulation is accelerated. The method comprises the steps of presetting a high-pressure value, considering that the heat transfer temperature difference between the condensation temperature and the ambient temperature is 8-16 ℃, and therefore, when the temperature is more than or equal to 22 ℃, tao is taken as the high pressure lower than 18bar (R410A condensation temperature is 30 ℃), the outer fan is shut down, the high pressure is higher than 23bar (R410A condensation temperature is 39 ℃), the fan is started to run at the lowest rotating speed of a unit, wherein the lowest rotating speed depends on the unit drive and the motor, and the rotating speed of the outer unit is selected from the values shown in table 1.
After the soft start, the normal operating stage, according to the highest rotational speed operation under this ambient temperature, guarantee higher heat exchange efficiency as far as possible, also receive high pressure PH control (the priority of high pressure PH control is high) simultaneously, consider that 30 ℃ (R410A corresponds saturation pressure 18 bar) and is less than or equal to Tao, after the soft start stage, the load changes, and the low-load also can normal operating.
(2) Initial valve step assignment and low-pressure early warning valve step correction of internal machine
Step assignment of an internal machine initial valve: and when the refrigeration is started, determining the initial valve step of the internal machine according to the outdoor environment temperature Tao and the startup load rate out when the refrigeration is started. When the starting load rate out is low, the number of the starting internal machines is small, the valve steps of the refrigerating operation starting internal machines are all 0, when the starting is carried out under the condition of higher load under the same pressure difference, the refrigerant circulation quantity is small, and the initial valve steps of the internal machines are increased; when the startup load rate out is high, the number of the startup internal machines is large, the refrigerant circulation amount with the same pressure difference is large, and the initial valve step is properly reduced. When the outdoor environment temperature Tao is high, the system establishes a pressure difference quickly, and the refrigerant can circulate quickly, so that the initial valve steps of the internal machine can be reduced properly, and the specific initial valve step assignment of the internal machine is shown in table 2.
Correcting the low-pressure early warning valve step: during the refrigeration operation, the pressure P is collected when the soft start stage operates for 90s 1 Pressure P at 120s 2 Because the system pressure difference is not established in the initial stage of soft start, the refrigerant circulation quantity is small, and the low pressure is reduced in a linear relation with time. However, because the external air separator and the internal heat exchanger store refrigerants, a little buffer memory is providedAnd when the initial start time is 0-90s and the low-pressure descending trend is not the fastest (namely the slope is not the steepest), taking the most serious running pressure drop of 90s-120s and calculating the pressure drop delta P 1 (△P 1 ＝P 1 -P 2 ) Linear relationship estimation of Low pressure at the end of Soft Start after 2 30s cycles (180 s), denoted P 4 (P 4 ＝P 2 -2*△P 1 ) If P is 4 ＜P Protection of If the internal engine valve is corrected for the first time in a stepping mode, only the starting stage is effective, and the correction formula is as follows:
target valve step M of inner machine 0 = current valve step of inner machine M At present +(P Protection of -P 4 )*300；
Target valve step M of internal machine 0 Has a maximum value of 480, the pressure units are bar and P Protection of The value is 0.5bar,300 is a periodic valve opening coefficient, and 30S is a period.
When the operation is 150S, collecting low-pressure and recording as P 3 Calculating the pressure drop DeltaP between 120s and 150s 2 (△P 2 ＝P 2 -P 3 ) Then linear pre-estimating the pressure P after the soft start is finished for 180s 5 (after 30S, i.e. 1 30S cycle), P at this time 5 ＝P 3 -△P 2 . If P 5 ＜P Protection of Then, the frequency of the compressor is reduced to the lowest operation frequency (the lowest frequency is 20HZ, which depends on the reliability of the compressor itself and the driving), and on the basis of the first correction, the second correction of the internal valve step is performed, in the same manner as above, and the operation timing sequence is as shown in fig. 3 below.
According to the control method of the multi-split air conditioner, when low-ring-temperature refrigeration is started, the start and stop of the fan are controlled through high pressure, and the system is helped to quickly establish pressure difference; when the high-environment temperature is started, the rotating speed of an outer fan is determined according to the outer ring temperature and the starting load rate, so that overhigh high voltage is prevented, and the normal starting of a unit is ensured; in the normal operation stage, the multi-split air conditioner operates at the highest rotating speed and is subjected to high-pressure control under the environment temperature, so that the multi-split air conditioner can normally operate under a low-load state after the soft start stage is finished; meanwhile, according to the outdoor environment temperature Tao and the startup load rate out during cold startup, the unit operation scene is refined, the internal unit initial valve steps are divided in a gridding mode, then the internal unit valve steps are corrected automatically through the low-voltage early warning function, the self-adaptive capacity of the unit in a complex scene is improved, and the normal startup of the unit is guaranteed.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (10)
1. A control method of a multi-split air conditioner is characterized by comprising the following steps:
s1: starting up and refrigerating the multi-split system, and detecting a starting-up load rate out and an outdoor environment temperature Tao;
s2: in the soft start stage, determining the rotating speed of an outer fan and the initial valve step of an inner machine;
s3: collecting the slope of pressure drop during the operation of the soft start stage, predicting the low pressure value at the end of the soft start, and if the predicted low pressure value is too low, correcting the internal machine valve step and the soft start compressor frequency.
2. A multi-split air conditioner control method as claimed in claim 1, wherein, in step S2, tao ≦ T 1 When the refrigeration is started, the start and stop of the fan are controlled through high pressure; at Tao > T 1 When refrigeration is started, dividing the outdoor environment temperature Tao and the starting load rate out according to the running rotating speed of the external fan, wherein the higher the starting load rate out is, the faster the rotating speed of the outdoor fan is; the higher the outdoor ambient temperature Tao, the faster the outdoor fan speed, wherein T 1 A pre-set chamber ambient temperature threshold.
3. The multi-split air conditioner control method as claimed in claim 2, wherein in step S2, the indoor unit initial valve step is decreased as the startup load rate out increases, and is decreased as the outdoor ambient temperature Tao increases.
4. The multi-split air conditioner control method as claimed in claim 2, wherein the specific step of controlling the start and stop of the fan by high pressure in step S2 includes:
S2A1: if the high pressure PH is not less than PH 1 Then, the operation is carried out according to the highest rotating speed at the outdoor environment temperature Tao;
S2A2: if the high pressure PH is less than or equal to PH 0 If so, the outdoor unit stops rotating;
S2A3: if pH is above 0 pH < pH under high pressure 1 And then the outer fan is started to operate according to the lowest rotating speed.
5. The multi-split air conditioner control method according to any one of claims 2 to 4, wherein in step S2, the values of the rotating speed of the outer fan and the initial valve step of the inner fan are obtained by looking up a table according to a startup load rate out and an outdoor ambient temperature Tao.
6. The multi-split air conditioner control method as claimed in claim 2, wherein in the step S3, the method comprises the steps of:
s31: acquisition of Soft Start phase operation t 1 Low pressure P of 1 And t 2 Low pressure P of 2 ；
S32: calculating the pressure drop Δ P 1 ＝P 1 -P 2 Estimating the low pressure P at the end of the soft start from a linear relationship 4 ；
S33: judging whether P is present 4 ＜P Protection of If yes, executing step S34; if not, executing S38;
s34: the first correction is carried out on the inner valve step by step, and the correction formula is as follows:
target valve step M of internal machine 0 = internal machine current valve step M At present +(P Protection of -P 4 )*k；
Wherein M is 0 ≤M Threshold(s) ，M Threshold(s) Is the maximum threshold value, P, of the target valve step of the internal machine Protection of K is a periodic valve opening coefficient t for presetting a low-pressure protection value 2 And t 1 Is the development period t Period of time ；
S38: the internal valve steps are not corrected.
7. The multi-split air conditioner control method as claimed in claim 6, further comprising, after the step S34, the steps of:
s35: operation t 2 +t Period of time At the same time, the low pressure is collected and recorded as P 3 Calculate the sum of this time and t 2 Pressure drop Δ P of time 2 ＝P 2 -P 3 Then, the low pressure P at the end of the soft start is estimated according to the linear relation 5 ；
S36: judging whether P is present 5 ＜P Protection of If yes, go to step S37; if not, executing S38;
s37: and reducing the frequency of the compressor to the lowest operation frequency, and performing secondary correction of the internal valve step on the basis of the primary correction again, wherein the formula of the secondary correction is consistent with that in the step S34.
8. A multi-split air conditioner control method as claimed in claim 7, wherein t is t 1 Is 90s,t Period of time Is 30s Protection of Is 0.5bar, k is 300, M Threshold value Is 480.
9. A multi-split air conditioning control system for performing the multi-split air conditioning control method according to any one of claims 1 to 8, comprising:
the detection module is used for detecting the outdoor environment temperature Tao and the startup load rate out of the multi-split air conditioner;
the acquisition module is used for determining the rotating speed assignment and the internal valve step assignment of the external fan at the starting stage under the corresponding outdoor environment temperature Tao and the starting load rate out;
a correction module for operating for a preset time t by acquiring a soft start phase 1 Calculating the target valve step of the internal machine by the pressure difference, correcting the valve step of the internal machine, and adjusting the running frequency of the compressor;
and the execution module is used for performing refrigeration starting of the multi-split air conditioner according to the corrected target valve step of the inner fan, the running frequency of the compressor and the acquired rotating speed of the outer fan.
10. An air conditioner, characterized by comprising at least one outdoor unit and a plurality of indoor units, wherein the air conditioner is used for executing the multi-split air conditioner control method according to any one of claims 1 to 8 when low-temperature refrigeration is started.
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