CN112803670A - Magnetic suspension centrifugal compressor cooling method and device - Google Patents
Magnetic suspension centrifugal compressor cooling method and device Download PDFInfo
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- CN112803670A CN112803670A CN202110004955.4A CN202110004955A CN112803670A CN 112803670 A CN112803670 A CN 112803670A CN 202110004955 A CN202110004955 A CN 202110004955A CN 112803670 A CN112803670 A CN 112803670A
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- 238000001816 cooling Methods 0.000 title claims abstract description 119
- 239000000725 suspension Substances 0.000 title claims abstract description 83
- 238000004804 winding Methods 0.000 claims abstract description 187
- 230000008859 change Effects 0.000 claims abstract description 132
- 239000003507 refrigerant Substances 0.000 claims abstract description 87
- 238000000034 method Methods 0.000 claims abstract description 38
- 239000007788 liquid Substances 0.000 claims description 49
- 238000005339 levitation Methods 0.000 claims description 10
- 230000001133 acceleration Effects 0.000 claims description 8
- 230000005484 gravity Effects 0.000 claims description 7
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 claims description 3
- 238000004364 calculation method Methods 0.000 claims description 3
- 238000001514 detection method Methods 0.000 claims description 3
- 229910052731 fluorine Inorganic materials 0.000 claims description 3
- 239000011737 fluorine Substances 0.000 claims description 3
- 238000002347 injection Methods 0.000 claims description 3
- 239000007924 injection Substances 0.000 claims description 3
- 230000000052 comparative effect Effects 0.000 claims description 2
- 230000000903 blocking effect Effects 0.000 claims 1
- 230000001276 controlling effect Effects 0.000 description 19
- 239000002826 coolant Substances 0.000 description 12
- 238000010586 diagram Methods 0.000 description 11
- 230000008569 process Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 238000005057 refrigeration Methods 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000000110 cooling liquid Substances 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000013021 overheating Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000004781 supercooling Methods 0.000 description 1
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D25/00—Pumping installations or systems
- F04D25/02—Units comprising pumps and their driving means
- F04D25/06—Units comprising pumps and their driving means the pump being electrically driven
- F04D25/0693—Details or arrangements of the wiring
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/58—Cooling; Heating; Diminishing heat transfer
- F04D29/5806—Cooling the drive system
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/58—Cooling; Heating; Diminishing heat transfer
- F04D29/582—Cooling; Heating; Diminishing heat transfer specially adapted for elastic fluid pumps
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K11/00—Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection
- H02K11/20—Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection for measuring, monitoring, testing, protecting or switching
- H02K11/25—Devices for sensing temperature, or actuated thereby
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Abstract
The application relates to a cooling method of a magnetic suspension centrifugal compressor. The method comprises the following steps: detecting the temperature of a motor winding of the magnetic suspension centrifugal compressor; calculating the temperature change rate of the motor winding according to the change condition of the temperature of the motor winding in a period of time; comparing the motor winding temperature with a winding temperature threshold corresponding to the motor winding temperature, and comparing the temperature change rate with a temperature change rate threshold corresponding to the temperature change rate; and if the temperature of the motor winding is greater than the winding temperature threshold value, or the temperature change rate is greater than the temperature change rate threshold value, controlling a cooling valve to be opened, wherein the cooling valve controls the circulation of a refrigerant of the compressor. The scheme provided by the application can realize precooling of the high-temperature winding of the magnetic suspension centrifugal compressor before starting, and ensures normal starting of the magnetic suspension centrifugal compressor.
Description
Technical Field
The application relates to the technical field of magnetic suspension centrifugal compressors, in particular to a cooling method of a magnetic suspension centrifugal compressor.
Background
The motor rotating speed of the magnetic suspension centrifugal compressor is high, the impeller compresses a refrigerant, the temperature of the motor can rise, certain influence can be exerted on mechanical parts after the temperature rises, and the motor is prone to failure, so that the motor can be effectively cooled, and the normal operation of the magnetic suspension centrifugal compressor can be guaranteed.
The cooling mode of the magnetic suspension compressor commonly used in the industry at present is cooling by a refrigerant, and the principle of the cooling mode is that part of refrigerant discharged from an exhaust port of the compressor enters a cooling interface of the compressor through a pipeline and passes through a throttling device of the compressor, so that high-temperature and high-pressure gaseous refrigerant is converted into low-temperature and low-pressure liquid refrigerant to cool a motor part of the compressor.
The existing cooling control method of the magnetic suspension compressor generally adopts the air gap temperature of a stator and a rotor of a motor, and controls the opening and closing of a cooling valve of the motor through a certain control logic.
The patent with publication number CN110086295A proposes a cooling structure and method of a magnetic suspension refrigeration compressor, which uses a pressure sensor, a temperature sensor, an electromagnetic valve, a condenser and a controller in cooperation; the temperature and the pressure in the motor can be monitored immediately, cooling is carried out at any time, and the refrigerant in the cavity of the motor is ensured to be in a saturated state or a micro-overheating state, so that the condition that the heat dissipation of a motor rotor is poor and the reliability of the motor operation is influenced due to the fact that the permanent magnet is demagnetized due to overhigh temperature of the rotor is avoided.
The patent with publication number CN209054812U discloses a magnetic suspension chiller compressor cooling system, which controls the circulation volume of a refrigerant by the magnetic suspension compressor cooling system through the start and stop of a refrigerant pump and the action of a pressure relief pipeline, so as to realize the effective temperature exposure of the compressor and prevent the magnetic suspension compressor from frequently stopping.
The cooling system and the cooling method of the magnetic suspension centrifugal compressor cool the temperature of the unit after the magnetic suspension centrifugal compressor starts to work normally, but the problem that the magnetic suspension centrifugal compressor cannot be started normally due to high temperature of a motor winding before the magnetic suspension centrifugal compressor works normally is not considered.
Disclosure of Invention
In order to overcome the problems in the related art, the application provides a cooling method of a magnetic suspension centrifugal compressor, which can cool a high-temperature motor winding of the magnetic suspension centrifugal compressor before the magnetic suspension centrifugal compressor is started.
A first aspect of the present application provides a magnetic levitation centrifugal compressor cooling method, comprising:
detecting the temperature of a motor winding of the magnetic suspension centrifugal compressor;
calculating the temperature change rate of the motor winding according to the change condition of the temperature of the motor winding in a period of time;
comparing the motor winding temperature with a winding temperature threshold corresponding to the motor winding temperature, and comparing the temperature change rate with a temperature change rate threshold corresponding to the temperature change rate;
and if the temperature of the motor winding is greater than or equal to the winding temperature threshold value, or the temperature change rate is greater than or equal to the temperature change threshold value, controlling the cooling valve to be opened.
In a first possible implementation of the first aspect, at the temperature change rate threshold, then,
the method for monitoring the temperature of the motor winding of the magnetic suspension centrifuge also comprises the following steps of:
and receiving a starting control instruction and controlling the cooling valve to be opened.
In a second possible implementation of the method of the first aspect,
the method for monitoring the temperature of the motor winding of the magnetic suspension centrifuge also comprises the following steps of:
and receiving a starting control instruction and controlling the cooling valve to be opened.
In a third possible implementation manner of the first aspect, the calculating a temperature change rate of the motor winding according to a temperature change of the motor winding over a period of time includes: calculating the temperature change rate of the motor winding according to the following formula;
Δ V is the winding temperature change rate in ℃/min;
tr2 is the winding temperature detected at the current moment and has the unit of;
tr1 is the winding temperature detected t seconds ago in units of; t is the temperature change time from the temperature Tr2 to the temperature Tr1, and the value range is 10-30 seconds.
In a fourth possible implementation method of the first aspect, after comparing the motor winding temperature with a winding temperature threshold corresponding to the motor winding temperature, and comparing the temperature change rate with a temperature change rate threshold corresponding to the temperature change rate, the method further includes:
and if the temperature of the motor winding is smaller than the winding temperature threshold value and the winding temperature change rate is smaller than the winding temperature change rate threshold value, controlling the cooling valve to be closed.
In a fifth possible implementation of the method of the first aspect, the method comprises:
acquiring a first pressure and a second pressure;
calculating a third pressure according to the density of the refrigerant, the gravity acceleration and the height difference;
comparing the sum of the second pressure and the third pressure with the first pressure;
and controlling the reversing device according to the comparison result.
With reference to the fifth possible implementation method of the first aspect, in a sixth possible implementation method, the method includes: the reversing device adopts an electric flow guiding device,
this electronic guiding device includes: the refrigerant return main pipe, the two refrigerant return branch pipes, the annular turntable, the flow guide baffle plate and the power switch;
the refrigerant liquid return main pipe is connected with the magnetic suspension centrifuge, and the two refrigerant liquid return branch pipes are respectively connected with the upper liquid return pipe and the lower liquid return pipe;
with reference to the fifth possible implementation method of the first aspect, in a seventh possible implementation method, the method includes: should according to refrigerant density, acceleration by gravity and difference in height calculate the third pressure, include: calculating the third pressure according to the following formula;
P＝ρgH
wherein rho is the density of the refrigerant in the evaporator, g is the gravity acceleration, and H is the height from the bottom of the magnetic suspension centrifuge to the bottom of the evaporator.
With reference to the fifth possible implementation method of the first aspect, in an eighth possible implementation method, the method includes:
should control switching-over device according to the comparative result, include:
if the first pressure is less than or equal to the sum of the second pressure and the third pressure, controlling the reversing device to be switched to the upper liquid return pipeline;
and if the first pressure is greater than the sum of the second pressure and the third pressure, controlling the reversing device to be switched to the lower liquid return pipeline.
A second aspect of the present application provides a magnetic levitation centrifugal compressor cooling apparatus comprising:
the detection unit is used for detecting the temperature of a motor winding of the magnetic suspension centrifugal compressor;
the change rate calculation unit is used for calculating the temperature change rate of the motor winding according to the change condition of the temperature of the motor winding within a period of time;
the comparison unit is used for comparing the motor winding temperature with a winding temperature threshold corresponding to the motor winding temperature, and comparing the temperature change rate with a temperature change rate threshold corresponding to the temperature change rate;
and the cooling valve control unit is used for controlling a cooling valve to be opened if the temperature of the motor winding is greater than or equal to the winding temperature threshold value or the temperature change rate is greater than or equal to the temperature change rate threshold value, and the cooling valve controls the circulation of a refrigerant of the compressor.
The technical scheme provided by the application can comprise the following beneficial effects:
according to the scheme, the temperature of the motor winding is obtained, the temperature change rate of the motor winding is calculated, the temperature change rate is compared with the set threshold values, and if the comparison result does not accord with the preset condition, the cooling valve is controlled to be opened, so that the refrigerant is controlled to enter. The winding temperature and the winding temperature change rate are used as the opening judgment indexes of the cooling valve, so that the cooling medium is introduced for cooling whenever a high-temperature condition occurs at any time, when the high-temperature condition exists in the unit before the magnetic suspension centrifugal compressor is started, the cooling system controls the cooling valve to introduce the cooling medium for precooling, the cooling reaches the temperature capable of enabling the motor rotor to be stably suspended, and the motor rotor is started again to ensure that the motor rotor can be normally started.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.
Drawings
The foregoing and other objects, features and advantages of the application will be apparent from the following more particular descriptions of exemplary embodiments of the application, as illustrated in the accompanying drawings wherein like reference numbers generally represent like parts throughout the exemplary embodiments of the application.
FIG. 1 is a schematic flow diagram of a cooling method of a magnetically levitated centrifugal compressor according to an embodiment of the present application;
FIG. 2 is another schematic flow diagram of a cooling method for a magnetically levitated centrifugal compressor according to an embodiment of the present application;
FIG. 3 is another schematic flow diagram of a cooling method for a magnetically levitated centrifugal compressor according to an embodiment of the present application;
FIG. 4 is a schematic structural diagram of a cooling device of a magnetic levitation centrifugal compressor according to an embodiment of the present application;
fig. 5 is a schematic structural diagram of an electric deflector according to an embodiment of the present application;
fig. 6 is a schematic structural diagram of a cooling system of a complete magnetic levitation centrifugal compressor according to an embodiment of the present application.
Detailed Description
Preferred embodiments of the present application will be described in more detail below with reference to the accompanying drawings. While the preferred embodiments of the present application are shown in the drawings, it should be understood that the present application may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in this application and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.
It should be understood that although the terms "first," "second," "third," etc. may be used herein to describe various information, these information should not be limited to these terms. These terms are only used to distinguish one type of information from another. For example, first information may also be referred to as second information, and similarly, second information may also be referred to as first information, without departing from the scope of the present application. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present application, "a plurality" means two or more unless specifically limited otherwise.
The existing cooling system and method of the magnetic suspension centrifugal compressor are that after the magnetic suspension centrifugal compressor starts to work normally, part of refrigerant discharged from the air outlet of the compressor enters a cooling interface of the compressor through a pipeline, and the refrigerant passes through a throttling device of the compressor, so that high-temperature and high-pressure gaseous refrigerant is converted into low-temperature and low-pressure liquid refrigerant, and the motor part of the compressor is cooled. However, the problem that the magnetic suspension centrifugal compressor cannot be started normally due to high temperature before normal operation is not considered.
In order to solve the above problem, an embodiment of the present application provides a method for cooling a magnetic suspension centrifugal compressor, which can pre-cool a high-temperature motor winding of the magnetic suspension centrifugal compressor before the magnetic suspension centrifugal compressor is started, so as to ensure that the magnetic suspension centrifugal compressor can be started normally.
The technical solutions of the embodiments of the present application are described in detail below with reference to the accompanying drawings.
Fig. 1 is a schematic flow chart of a cooling method of a magnetic levitation centrifugal compressor according to an embodiment of the present application.
Referring to fig. 1, an embodiment of a cooling method of a magnetically levitated centrifugal compressor in an embodiment of the present application includes:
101. detecting the temperature of a motor winding of the magnetic suspension centrifugal compressor;
the magnetic suspension centrifugal compressor is a refrigeration compressor adopting magnetic suspension bearing technology, and is characterized by that it utilizes magnetic field principle to make the rotor of the compressor be in a suspension state when it is worked, and utilizes position sensor and control circuit to ensure that the rotor can be always rotated in the central position, and if the rotor is deviated, according to the rotor position, it can calculate and produce proper current to ensure that the rotor can be returned to central point to run. Under normal conditions, the magnetic suspension bearing is composed of dozens of electromagnetic coils which are independently controlled, the energy output is continuously matched and adjusted to ensure that a rotor is stabilized at the center of the bearing, and each electromagnetic coil is fed back to a controller through a signal obtained from a sensor and then performs adjustment, so that the magnetic suspension bearing does not make mechanical contact with a base during rotation, and mechanical friction is avoided.
In the embodiment of the application, the temperature sensing bulb is arranged in the motor winding of the compressor, so that the winding temperature is detected in real time.
102. Calculating the temperature change rate of the motor winding according to the change condition of the temperature of the motor winding in a period of time;
the motor winding has resistance, heat is generated by the resistance of the winding in the electrifying process, and if the heat is not taken away in time, the heat is accumulated all the time, and the temperature of the winding is increased all the time. Under the condition that the cooling medium is not introduced for cooling, the temperature of the motor winding at the current moment is always higher than that of the motor winding at any previous moment along with the lapse of time. After the cooling medium is introduced for cooling, along with the lapse of time, the temperature of the motor winding at the current moment is less than, equal to or greater than the temperature of the motor winding at the previous moment, so that the temperature of the motor winding is a changed value.
In the embodiment of the present application, the temperature change rate of the motor winding can be obtained by calculating the ratio of the difference between the two temperatures and the temperature change time through the current motor winding temperature detected in step 101 and the motor winding temperature before a period of time.
103. Comparing the motor winding temperature with a winding temperature threshold corresponding to the motor winding temperature, and comparing the temperature change rate with a temperature change rate threshold corresponding to the temperature change rate;
the temperature of the motor winding has an influence on the stable suspension of the rotor of the motor, so that experiments can show that the rotor of the motor can have the best stability in what temperature range, and the temperature value of one temperature range, which is less than the maximum value of the temperature range and can enable the rotor of the motor to have the best stability, can be set as a winding temperature threshold value corresponding to the temperature of the motor winding.
The same motor winding temperature change rate also has certain influence on the stable suspension of the rotor of the motor, when the temperature of the motor winding is smaller than the winding temperature threshold value, the motor can be guaranteed to run stably theoretically, and the introduction of the refrigerant can be stopped.
In the embodiment of the present application, the set temperature threshold value must be compared with the current motor winding temperature, and the set temperature change threshold value must be compared with the current motor winding temperature change rate.
104. If the temperature of the motor winding is larger than the winding temperature threshold value, or the temperature change rate is larger than the temperature change rate threshold value, controlling a cooling valve to be opened;
the cooling valve is an adjusting device for controlling the flow of the refrigerant, such as an electromagnetic valve or a differential pressure adjusting valve.
When the temperature of the motor winding is greater than the winding temperature threshold, the temperature of the winding influences the stable suspension of the motor rotor, so that the cooling valve is controlled to be opened, a refrigerant is introduced to cool the motor rotor, the temperature of the motor rotor is guaranteed not to exceed the winding temperature threshold, and the stable operation or starting of the compressor is guaranteed. Similarly, when the temperature change rate is too fast and exceeds the temperature change rate threshold, even if the winding temperature is lower than the winding temperature threshold, the temperature will rise above the winding temperature threshold within a short time, so the cooling valve is also controlled to open to introduce the cooling medium for cooling.
According to the scheme, the temperature of the motor winding is obtained, the temperature change rate of the motor winding is calculated, the temperature change rate is compared with the set threshold values, and if the comparison result does not accord with the preset condition, the cooling valve is controlled to be opened, so that the refrigerant is controlled to enter. The winding temperature and the winding temperature change rate are used as the opening judgment indexes of the cooling valve, so that the cooling medium is introduced for cooling whenever a high-temperature condition occurs at any time, when the high-temperature condition exists in the unit before the magnetic suspension centrifugal compressor is started, the cooling system controls the cooling valve to introduce the cooling medium for precooling, the cooling reaches the temperature capable of enabling the motor rotor to be stably suspended, and the motor rotor is started again to ensure that the motor rotor can be normally started.
For ease of understanding, an application example of a cooling method of a magnetically levitated centrifugal compressor is provided below, and referring to fig. 2, an example of the cooling method of the magnetically levitated centrifugal compressor in the embodiment of the present application includes:
in the embodiment of the application, a more optimized solution embodiment aiming at two conditions that the motor winding cannot be normally started when high temperature exists before the magnetic suspension centrifugal compressor is started or the unit needs to be started and cannot be normally started when high temperature exists after the magnetic suspension centrifugal compressor is shut down is shown.
201. Receiving a starting-up control instruction or a shutdown control instruction, and controlling the cooling valve to be opened;
the control command in the embodiment of the application is a power-on control command or a power-off control command. The starting control instruction refers to an instruction for controlling the motor part of the magnetic suspension centrifugal compressor to start working; the shutdown control instruction also refers to an instruction for controlling the magnetic suspension centrifugal compressor motor to stop working.
After receiving a starting control instruction, the control center controls the cooling valve to be opened, and the magnetic suspension centrifugal compressor (namely, the motor) is started to start compressing the refrigerant; and after receiving the shutdown control instruction, the control center controls the cooling valve to be opened, and the magnetic suspension centrifugal compressor stops compressing the refrigerant.
202. Detecting the temperature of a motor winding of the magnetic suspension centrifugal compressor;
in the embodiment of the present application, the specific content of step 202 is similar to that of step 101 in embodiment 1, and is not described herein again.
203. Calculating the temperature change rate of the motor winding according to the change condition of the temperature of the motor winding in a period of time;
the specific formula for calculating the temperature change rate according to the winding temperature detected at the current moment, the winding temperature detected at a certain moment before the current moment and the temperature change time is as follows:
Δ V is the winding temperature change rate in ℃/min;
tr2 is the winding temperature detected at the current moment and has the unit of;
tr1 is the winding temperature detected t seconds ago in units of;
t is the temperature change time from the temperature Tr2 to the temperature Tr1, and the value range is 10-30 seconds.
For example, when the winding temperature detected at the current moment is 50 ℃, the winding temperature detected before 10s is 60 ℃, the winding temperature change rate is calculated as follows:
204. comparing the motor winding temperature with a winding temperature threshold corresponding to the motor winding temperature, and comparing the temperature change rate with a temperature change rate threshold corresponding to the temperature change rate;
the temperature change rate threshold value in the embodiment of the application is a temperature change rate interval, the value range of the temperature change rate interval is 0.5-1 ℃/min, and the winding temperature threshold value is 35 ℃.
Comparing the current winding temperature detected in step 202 with 35 ℃, comparing the temperature change rate calculated in step 203 with the temperature change rate interval of 0.5-1 ℃/min,
205. if the winding temperature is smaller than the set winding temperature threshold value and the winding temperature change rate is smaller than the set winding temperature change rate, controlling the cooling valve to be closed;
in the embodiment of the application, when the winding temperature is less than 35 ℃ and the winding temperature change rate is less than 1 ℃/min, the winding is cooled in place, the magnetic suspension centrifugal compressor can be started normally, the cooling valve can be controlled to be closed, and the refrigerant is prevented from flowing in continuously.
206. If the temperature of the motor winding is larger than the winding temperature threshold value, or the temperature change rate is larger than the temperature change rate threshold value, controlling a cooling valve to be opened;
in the embodiment of the application, after step 205, after the magnetic suspension centrifugal compressor is normally started to work, the temperature of the unit of the magnetic suspension centrifugal compressor generates heat due to the winding resistance, and the winding temperature is greater than or equal to the winding temperature threshold value, or the temperature change rate is greater than or equal to the temperature change rate threshold value, and the cooling valve is also controlled to be opened, and a refrigerant is introduced for cooling.
According to the scheme, the cooling valve is controlled to be opened after the control command is received, the temperature of the motor winding is acquired, the temperature change rate of the motor winding is calculated, the temperature change rate is compared with the set threshold values, if the comparison result meets the control condition, the cooling valve is controlled to be closed, and the cooling valve is controlled to be opened to be cooled after the cooling valve is normally started to work and then under the high-temperature condition. The cooling medium is introduced before or after the starting, the winding temperature and the winding temperature change rate are used as the closing judgment indexes of the cooling valve, and after the normal starting is carried out, the winding temperature and the winding temperature change rate are also used as the control indexes of the cooling valve, so that the cooling medium can be always introduced into a unit of the magnetic suspension centrifugal compressor for cooling when the unit does not meet the set index standard, and the introduction of the cooling medium is stopped when the cooling reaches the index standard. The temperature of the motor is ensured to be within the optimal use temperature range of the motor during operation, and the necessary condition that the motor rotor is stably suspended is also ensured to be achieved in advance before starting and after shutdown, so that the motor can be normally started in the next starting.
For ease of understanding, an application example of a cooling method of a magnetic levitation centrifugal compressor is provided below, and referring to fig. 3, 5 and 6, an application example of the cooling method of the magnetic levitation centrifugal compressor in the application example includes:
the method for intelligently selecting the liquid return pipeline through the double cooling liquid return pipelines in the embodiment of the application solves the problem that how the refrigerant can better flow back to a refrigerating or heating cycle after cooling the magnetic suspension centrifugal compressor, which is not solved in the embodiment 1 and the embodiment 2, and ensures that the condition of starting the load caused by refrigerant backflow can not occur.
301. Receiving a starting-up control instruction or a shutdown control instruction, and controlling the cooling valve to be opened;
after receiving a starting control instruction, the control center controls the cooling valve to be opened, and starts a motor of the magnetic suspension centrifugal compressor to start compressing a refrigerant; and after receiving the shutdown control instruction, the control center controls the cooling valve to be opened, and the motor of the magnetic suspension centrifugal compressor stops compressing the refrigerant.
In the embodiment of the application, after receiving the starting control instruction, the control center controls the motor of the magnetic suspension centrifugal compressor to start, the compressor starts to compress the refrigerant, the refrigerant is converted from a low-temperature low-pressure state to a high-temperature high-pressure state, meanwhile, the electromagnetic valve 601 is controlled to be opened, liquid refrigerant is introduced, the temperature of the refrigerant is reduced after the refrigerant passes through the capillary tube 602 connected with the electromagnetic valve, and then the refrigerant flows into the magnetic suspension centrifugal compressor 604 to be cooled, and the temperature of a motor winding is changed because the compressor can generate heat continuously in the running process, therefore, the electronic expansion valve 603 is controlled to be opened, the control center adjusts the opening degree of the electronic expansion valve 603 in real time according to the change of the winding temperature of the compressor in the running process, the inflow amount of the refrigerant is accurately regulated, and the liquid refrigerant enters the magnetic suspension centrifugal compressor to be cooled after being supercooled by the electronic expansion valve 603; after receiving a shutdown control instruction, the control center controls the motor of the magnetic suspension centrifugal compressor to shut down, the compressor stops compressing the refrigerant, the compressor does not work, heat is not generated continuously, the temperature does not rise any more, so that the electronic expansion valve 603 can be controlled to be closed, the electromagnetic valve 601 is controlled to be opened, the liquid refrigerant enters from one side of the electromagnetic valve cooling pipeline, the temperature of the refrigerant is reduced after passing through the capillary tube 602 connected with the electromagnetic valve, and the refrigerant flows into the magnetic suspension centrifugal compressor to be cooled.
302. Detecting the temperature of a motor winding of the magnetic suspension centrifugal compressor;
in this embodiment of the application, the specific content of step 302 is similar to that of step 202 in embodiment 2, and is not described herein again.
303. Calculating the temperature change rate of the motor winding according to the change condition of the temperature of the motor winding in a period of time;
in the embodiment of the present application, the specific content of step 303 is similar to that of step 203 in embodiment 2, and is not described herein again.
304. Comparing the motor winding temperature with a winding temperature threshold corresponding to the motor winding temperature, and comparing the temperature change rate with a temperature change rate threshold corresponding to the temperature change rate;
in this embodiment of the application, the specific content of step 304 is similar to that of step 204 in embodiment 2, and is not described herein again.
305. If the winding temperature is smaller than the set winding temperature threshold value and the winding temperature change rate is smaller than the set winding temperature change rate, controlling the cooling valve to be closed;
in the embodiment of the present application, if the winding temperature is less than the set winding temperature threshold, and the winding temperature change rate is less than the set winding temperature change rate, and the temperature has reached the requirement, the electromagnetic valve 601 is controlled to close, the refrigerant inflow is stopped, and the cooling is stopped.
306. If the temperature of the motor winding is larger than the winding temperature threshold value, or the temperature change rate is larger than the temperature change rate threshold value, controlling a cooling valve to be opened;
if the temperature of the motor winding is greater than the winding temperature threshold value or the temperature change rate is greater than the temperature change rate threshold value, which represents that cooling is needed, the electromagnetic valve 601 is controlled to be opened, so that the refrigerant flows into the capillary 602 for supercooling and then flows into the compressor for cooling.
307. Acquiring a first pressure and a second pressure;
the first pressure is the refrigerant pressure at the magnetic suspension centrifugal compressor, and the second pressure is the refrigerant pressure at the liquid collecting bag of the evaporator;
in the embodiment of the application, a 605 pressure sensor P1 is arranged at a refrigerant output port of the magnetic suspension centrifugal compressor to detect a first pressure; the second pressure is sensed by providing a 607 pressure sensor P2 at the evaporator sump bag 609.
308. Calculating a third pressure according to the density of the refrigerant, the gravity acceleration and the height difference,
the third pressure is the liquid pressure generated by the height difference between the evaporator liquid collecting bag and the magnetic suspension centrifuge after the refrigerant reaches the evaporator liquid collecting bag;
calculating the third pressure according to the following liquid pressure formula;
P＝ρgH
wherein rho is the density of the refrigerant in the evaporator, g is the gravity acceleration, and H613 is the height from the bottom of the magnetic suspension centrifuge to the bottom of the evaporator.
309. Comparing the sum of the second pressure and the third pressure, and the first pressure;
in the embodiment of the present application, the first pressure obtained by the pressure sensor in step 307 is P1, the second pressure is P2, the third pressure calculated by the formula in step 308 is P, the sum of the second pressure P2 and the third pressure P is P4, and P4 and P1 are compared.
310. Controlling a reversing device according to the comparison result;
the switching-over device is used for switching refrigerant liquid return pipeline, and refrigerant liquid return pipeline includes: an upper liquid return pipeline communicated with a fluorine injection nozzle at the upper end of the evaporator and a lower liquid return pipe communicated with a liquid collection bag at the bottom of the evaporator.
The switching-over device in this application embodiment adopts electronic guiding device 501, and electronic guiding device includes: the system comprises a refrigerant liquid return main pipe 502, two refrigerant liquid return branch pipes, an annular turntable 507, a flow guide baffle plate 506 and a power switch 505, wherein the refrigerant liquid return main pipe is connected with the magnetic suspension centrifugal machine, and the two refrigerant liquid return branch pipes are respectively connected with an upper liquid return pipe 503 and a lower liquid return pipe 504. The initial state of the electric backflow device is that the refrigerant is guided to enter the lower liquid return pipeline, the guide retaining pieces arranged on the annular turntable rotate after the power switch is powered on, the flow direction of the refrigerant is changed through rotation, the refrigerant is guided to flow to the upper liquid return pipeline, and switching of the refrigerant liquid return pipelines is achieved.
In the embodiment of the present application, if P1 is less than or equal to P4, the electric diversion device 606 is powered on to rotate the diversion baffle, so as to guide the refrigerant to enter the upper liquid return pipeline, flow through the ball valve 612 and flow to the fluorine injection nozzle 611 at the upper end of the evaporator 610; if P1 is larger than P4, the electric diversion device 606 is powered off or not powered on, so that the diversion baffle plate keeps the initial position state, and the refrigerant is guided to enter the lower liquid return pipe, flows through the ball 608 and the valve 2 and then flows to the liquid collection bag 609 at the bottom of the evaporator 610.
According to the scheme, the cooling valve is controlled to be opened after the control command is received, the temperature of the motor winding is obtained, the temperature change rate of the motor winding is calculated, the temperature change rate is compared with the set respective threshold values, and if the comparison result meets the control condition, the cooling valve is controlled to be opened and closed. The temperature of the motor is ensured to be within the optimal use temperature range of the motor before starting, during operation and after shutdown by introducing the refrigerant before starting or after closing and comparing the temperature of the continuous motor winding after starting with the temperature change rate, so that the magnetic suspension centrifugal compressor can be normally started and normally operated; meanwhile, the related pressure is calculated by acquiring the pressure of the refrigerant at the related position, and then the comparison of the pressure is carried out, and the reversing device is controlled according to the comparison result, so that the switching of the refrigerant return pipelines is realized, the refrigerant of the cooling motor can smoothly flow into the evaporator, and the phenomenon that the compressor is started and carried due to the backflow of the refrigerant can not occur.
Corresponding to the embodiment of the application function implementation method, the application also provides a cooling device of the magnetic suspension centrifugal compressor, electronic equipment and corresponding embodiments.
Fig. 4 is a schematic structural diagram of a cooling device of a magnetic levitation centrifugal compressor according to an embodiment of the present application.
Referring to fig. 4, the cooling apparatus of the magnetically levitated centrifugal compressor comprises:
the detection unit 401 is used for detecting the temperature of a motor winding of the magnetic suspension centrifugal compressor;
a change rate calculation unit 402, configured to calculate a temperature change rate of the motor winding according to a change condition of the temperature of the motor winding in a period of time;
a comparing unit 403, configured to compare the motor winding temperature with a winding temperature threshold corresponding to the motor winding temperature, and compare the temperature change rate with a temperature change rate threshold corresponding to the temperature change rate;
and a cooling valve control unit 404, configured to control a cooling valve to be opened if the temperature of the motor winding is greater than or equal to the winding temperature threshold, or the temperature change rate is greater than or equal to the temperature change rate threshold, where the cooling valve controls circulation of a refrigerant in the compressor.
According to the scheme, the temperature of the motor winding is obtained, the temperature change rate of the motor winding is calculated, the temperature change rate is compared with the set threshold values, and if the comparison result does not accord with the preset condition, the cooling valve is controlled to be opened, so that the refrigerant is controlled to enter. The winding temperature and the winding temperature change rate are used as the opening judgment indexes of the cooling valve, so that the cooling medium is introduced for cooling whenever a high-temperature condition occurs at any time, when the high-temperature condition exists in the unit before the magnetic suspension centrifugal compressor is started, the cooling system controls the cooling valve to introduce the cooling medium for precooling, the cooling reaches the temperature capable of enabling the motor rotor to be stably suspended, and the motor rotor is started again to ensure that the motor rotor can be normally started.
With regard to the apparatus in the above-described embodiment, the specific manner in which each module performs the operation has been described in detail in the embodiment related to the method, and will not be elaborated here.
The aspects of the present application have been described in detail hereinabove with reference to the accompanying drawings. In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments. Those skilled in the art should also appreciate that the acts and modules referred to in the specification are not necessarily required in the present application. In addition, it can be understood that the steps in the method of the embodiment of the present application may be sequentially adjusted, combined, and deleted according to actual needs, and the modules in the device of the embodiment of the present application may be combined, divided, and deleted according to actual needs.
Those of skill would further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the applications disclosed herein may be implemented as electronic hardware, computer software, or combinations of both.
The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems and methods according to various embodiments of the present application. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
Having described embodiments of the present application, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen in order to best explain the principles of the embodiments, the practical application, or improvements made to the technology in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.
Claims (10)
1. A method of cooling a magnetically levitated centrifugal compressor, comprising:
detecting the temperature of a motor winding of the magnetic suspension centrifugal compressor;
calculating the temperature change rate of the motor winding according to the change condition of the temperature of the motor winding in a period of time;
comparing the motor winding temperature with a winding temperature threshold corresponding to the motor winding temperature, and comparing the temperature change rate with a temperature change rate threshold corresponding to the temperature change rate;
and if the temperature of the motor winding is greater than or equal to the winding temperature threshold value, or the temperature change rate is greater than or equal to the temperature change rate threshold value, controlling a cooling valve to be opened, wherein the cooling valve is used for controlling the circulation of a refrigerant of the compressor.
2. A method of cooling a magnetically levitated centrifugal compressor as claimed in claim 1, wherein: before detecting the temperature of a motor winding of the magnetic suspension centrifuge, the method further comprises the following steps:
and receiving a starting control instruction and controlling the cooling valve to be opened.
3. A method of cooling a magnetically levitated centrifugal compressor as claimed in claim 2, further comprising, prior to sensing the temperature of the motor windings of the magnetically levitated centrifugal compressor:
and receiving a shutdown control instruction, and controlling the cooling valve to be opened.
4. A method of cooling a magnetically levitated centrifugal compressor as set forth in claim 1, wherein said calculating a rate of change of temperature of the motor windings based on a change of temperature of the motor windings over a period of time includes: calculating the temperature change rate of the motor winding according to the following formula;
Δ V is the winding temperature change rate in ℃/min;
tr2 is the winding temperature detected at the current moment and has the unit of;
tr1 is the winding temperature detected t seconds ago in units of; t is the temperature change time from the temperature Tr2 to the temperature Tr1, and the value range is 10-30 seconds.
5. A method for cooling a magnetically levitated centrifugal compressor as set forth in claim 1, wherein after comparing said motor winding temperature to a winding temperature threshold corresponding to said motor winding temperature and comparing said rate of temperature change to a rate of temperature change threshold corresponding to said rate of temperature change, further comprising:
and if the temperature of the motor winding is smaller than the winding temperature threshold value and the winding temperature change rate is smaller than the temperature change rate threshold value, controlling the cooling valve to be closed.
6. A method of cooling a magnetically levitated centrifugal compressor as set forth in claim 1, further comprising:
acquiring a first pressure and a second pressure, wherein the first pressure is the refrigerant pressure at the magnetic suspension centrifugal compressor, and the second pressure is the refrigerant pressure at the liquid collection bag of the evaporator;
calculating a third pressure according to the density, the gravity acceleration and the height difference of the refrigerant, wherein the third pressure is the liquid pressure generated by the height difference between the evaporator liquid collecting bag and the magnetic suspension centrifuge after the refrigerant reaches the evaporator liquid collecting bag;
comparing the sum of the second pressure and the third pressure, and the first pressure;
according to the comparative result control switching-over device, the switching-over device is used for switching over refrigerant return liquid pipeline, refrigerant return liquid pipeline includes: an upper liquid return pipeline communicated with a fluorine injection nozzle at the upper end of the evaporator and a lower liquid return pipe communicated with a liquid collection bag at the bottom of the evaporator.
7. A cooling method for a magnetic levitation centrifugal compressor as claimed in claim 6, wherein the reversing device is an electrically operated flow guiding device,
the electric deflector comprises: the refrigerant return main pipe, the two refrigerant return branch pipes, the annular turntable, the flow guide baffle plate and the power switch;
the refrigerant liquid return main pipe is connected with the magnetic suspension centrifuge, and the two refrigerant liquid return branch pipes are respectively connected with the upper liquid return pipe and the lower liquid return pipe;
the power switch is electrified and then the flow guide blocking piece arranged on the annular turntable rotates.
8. A method of cooling a magnetically levitated centrifugal compressor as set forth in claim 6, wherein said calculating a third pressure based on a refrigerant density, a gravitational acceleration, and a height difference comprises: calculating the third pressure according to the following formula;
P＝ρgH
wherein rho is the density of the refrigerant in the evaporator, g is the gravity acceleration, and H is the height from the bottom of the magnetic suspension centrifuge to the bottom of the evaporator.
9. A method according to claim 6, wherein said controlling the reversing device according to the comparison comprises:
if the first pressure is less than or equal to the sum of the second pressure and the third pressure, controlling the reversing device to switch to the upper liquid return pipeline;
and if the first pressure is greater than the sum of the second pressure and the third pressure, controlling the reversing device to be switched to the lower liquid return pipeline.
10. A magnetic levitation centrifugal compressor cooling apparatus, comprising:
the detection unit is used for detecting the temperature of a motor winding of the magnetic suspension centrifugal compressor;
the change rate calculation unit is used for calculating the temperature change rate of the motor winding according to the change condition of the temperature of the motor winding within a period of time;
the comparison unit is used for comparing the motor winding temperature with a winding temperature threshold corresponding to the motor winding temperature, and comparing the temperature change rate with a temperature change rate threshold corresponding to the temperature change rate;
and the cooling valve control unit is used for controlling a cooling valve to be opened if the temperature of the motor winding is greater than or equal to the winding temperature threshold value or the temperature change rate is greater than or equal to the temperature change rate threshold value, and the cooling valve controls the circulation of a refrigerant of the compressor.
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