CN108131871B - Variable frequency centrifuge and control method of hot gas bypass valve therein - Google Patents
Variable frequency centrifuge and control method of hot gas bypass valve therein Download PDFInfo
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B49/00—Arrangement or mounting of control or safety devices
- F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
- F25B49/022—Compressor control arrangements
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
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Abstract
The invention discloses a variable frequency centrifuge and a control method of a hot gas bypass valve therein, wherein the variable frequency centrifuge comprises a compressor, the hot gas bypass valve is arranged between a gas suction pipe and a gas exhaust pipe of the compressor, and the method comprises the following steps: when the variable-frequency centrifuge is in an operating state, acquiring the guide vane opening degree, the operating pressure ratio and the operating frequency upper limit of the compressor, wherein the operating pressure ratio is the ratio of the exhaust absolute pressure and the suction absolute pressure of the compressor; calculating the critical frequency of the variable frequency centrifuge according to the opening degree of the guide vane and the operation pressure ratio; and controlling the opening of the hot gas bypass valve according to the critical frequency and the upper limit of the operating frequency. The method can ensure that the variable frequency centrifuge can safely operate under the conditions of high ambient temperature and high pressure ratio by controlling the opening of the hot gas bypass valve, and meanwhile, the surge phenomenon of a compressor can not occur under the operation of small load, thereby improving the operation reliability of the variable frequency centrifuge.
Description
Technical Field
The invention relates to the technical field of air conditioners, in particular to a control method of a hot air bypass valve in a variable frequency centrifuge, a non-temporary computer readable storage medium and the variable frequency centrifuge.
Background
The frequency conversion centrifuge in the market before, when ambient temperature is high, because of centrifuge's operating characteristic problem, can't realize the safe operation under the light load. The main reason is that when the ambient temperature is high, the operation pressure ratio (the exhaust absolute pressure of the compressor/the suction absolute pressure of the compressor) of the variable frequency centrifuge is large, and when the variable frequency centrifuge operates under a small load, the variable frequency centrifuge can generate a surge phenomenon, and the impeller can be damaged when the variable frequency centrifuge operates under a severe load.
Disclosure of Invention
The present invention is directed to solving, at least to some extent, one of the technical problems in the related art. Therefore, a first object of the present invention is to provide a method for controlling a hot gas bypass valve in an inverter centrifuge, which can control the opening of the hot gas bypass valve, so that the inverter centrifuge can safely operate under a low load under the conditions of high ambient temperature and high pressure ratio, and meanwhile, a compressor surge phenomenon does not occur under the operation of the low load, thereby improving the operation reliability of the inverter centrifuge.
A second object of the invention is to propose a non-transitory computer-readable storage medium.
The third purpose of the invention is to provide a variable frequency centrifuge.
In order to achieve the above object, a first embodiment of the present invention provides a method for controlling a hot gas bypass valve in a variable frequency centrifuge, where the variable frequency centrifuge includes a compressor, and the hot gas bypass valve is disposed between a gas suction pipe and a gas discharge pipe of the compressor, and the method includes the following steps: when the variable-frequency centrifuge is in an operating state, acquiring the guide vane opening degree, the operating pressure ratio and the operating frequency upper limit of the compressor, wherein the operating pressure ratio is the ratio of the exhaust absolute pressure and the suction absolute pressure of the compressor; calculating the critical frequency of the variable frequency centrifuge according to the guide vane opening and the operation pressure ratio; and controlling the opening of the hot gas bypass valve according to the critical frequency and the upper limit of the operating frequency.
According to the control method of the hot gas bypass valve in the variable frequency centrifuge, when the variable frequency centrifuge is in the running state, the guide vane opening degree, the running pressure ratio and the running frequency upper limit of the compressor are obtained, then the critical frequency of the variable frequency centrifuge is calculated according to the guide vane opening degree and the running pressure ratio, and then the opening degree of the hot gas bypass valve is controlled according to the critical frequency and the running frequency upper limit. The method can ensure that the variable frequency centrifuge can safely operate under the conditions of high ambient temperature and high pressure ratio by controlling the opening of the hot gas bypass valve, and meanwhile, the surge phenomenon of a compressor can not occur under the operation of small load, thereby improving the operation reliability of the variable frequency centrifuge.
In addition, the control method for the hot gas bypass valve in the variable frequency centrifuge, which is proposed according to the above embodiment of the invention, may further have the following additional technical features:
according to an embodiment of the invention, the calculating the critical frequency of the inverter centrifuge according to the guide vane opening and the operation pressure ratio comprises: calculating a pressure ratio correction coefficient of the compressor according to the guide vane opening; calculating a critical pressure ratio of the compressor according to the pressure ratio correction coefficient and the operation pressure ratio; and calculating the critical frequency of the variable frequency centrifuge according to the critical pressure ratio.
According to one embodiment of the present invention, the pressure ratio correction coefficient is calculated by the following formula: k-a 1D3+a2*D2+ a3 × D + a4, where K is a pressure ratio correction coefficient, D is a guide vane opening degree, and a1-a4 is a first coefficient.
According to one embodiment of the invention, the critical pressure ratio is calculated by the following formula: 1/K, wherein the critical pressure ratio is obtained, and the K is a pressure ratio correction coefficient.
According to one embodiment of the invention, the critical frequency of the variable frequency centrifuge is calculated by the following formula: y-b 12+ b2 + b3, wherein Y is the critical frequency of the variable frequency centrifuge and the critical pressure ratio, and b1-b3 is the second coefficient.
According to an embodiment of the present invention, the controlling the opening degree of the hot gas bypass valve according to the critical frequency and the upper limit of the operating frequency includes: judging whether the critical frequency is greater than or equal to a first upper running frequency limit, wherein the first upper running frequency limit is equal to the product of the upper running frequency limit and the first control coefficient; if the critical frequency is greater than or equal to a first upper running frequency limit, gradually increasing the opening of the hot gas bypass valve until the critical frequency is less than or equal to a second upper running frequency limit, and stopping increasing the opening of the hot gas bypass valve, wherein the second upper running frequency limit is equal to the product of the upper running frequency limit and a second control coefficient, and the second control coefficient is less than the first control coefficient; judging whether the critical frequency is less than or equal to a third upper running frequency limit, wherein the third upper running frequency limit is equal to the product of the upper running frequency limit and a third control coefficient, and the third control coefficient is less than the second control coefficient; and if the critical frequency is less than or equal to the upper limit of the third operating frequency, controlling the hot gas bypass valve to be closed.
In order to achieve the above object, a second aspect of the present invention provides a non-transitory computer-readable storage medium, on which a computer program is stored, wherein the computer program, when executed by a processor, implements a method for controlling a hot gas bypass valve in a variable frequency centrifuge according to the first aspect of the present invention.
According to the non-transitory computer readable storage medium provided by the embodiment of the invention, when the variable frequency centrifuge is in an operating state, the guide vane opening degree, the operating pressure ratio and the operating frequency upper limit of the compressor are obtained, then the critical frequency of the variable frequency centrifuge is calculated according to the guide vane opening degree and the operating pressure ratio, and then the opening degree of the hot gas bypass valve is controlled according to the critical frequency and the operating frequency upper limit, so that the variable frequency centrifuge can safely operate under a low load under the conditions of high ambient temperature and high pressure ratio, meanwhile, the compressor surge phenomenon cannot occur under the condition of low load operation, and the operation reliability of the variable frequency centrifuge is improved.
In order to achieve the above object, a third aspect of the present invention provides a variable frequency centrifuge, including: a compressor; a hot gas bypass valve disposed between a gas suction pipe and a gas discharge pipe of the compressor; the controller is used for obtaining the guide vane opening degree, the operation pressure ratio and the operation frequency upper limit of the compressor when the variable frequency centrifuge is in an operation state, calculating the critical frequency of the variable frequency centrifuge according to the guide vane opening degree and the operation pressure ratio, and controlling the opening degree of the hot gas bypass valve according to the critical frequency and the operation frequency upper limit, wherein the operation pressure ratio is the ratio of the exhaust absolute pressure and the suction absolute pressure of the compressor.
According to the frequency conversion centrifugal machine provided by the embodiment of the invention, when the frequency conversion centrifugal machine is in an operating state, the controller acquires the guide vane opening, the operating pressure ratio and the operating frequency upper limit of the compressor, calculates the critical frequency of the frequency conversion centrifugal machine according to the guide vane opening and the operating pressure ratio, and controls the opening of the hot gas bypass valve according to the critical frequency and the operating frequency upper limit. Therefore, the variable frequency centrifuge can safely operate under the conditions of high ambient temperature and high pressure ratio under a small load, and meanwhile, the phenomenon of compressor surge cannot occur under the operation of the small load, so that the operation reliability of the variable frequency centrifuge is improved.
In addition, the variable frequency centrifuge provided by the embodiment of the invention can also have the following additional technical characteristics:
according to an embodiment of the present invention, when the maximum exhaust port temperature difference is smaller than a preset value, the control module is further configured to maintain a preset timing sequence to control the oil return valve.
According to an embodiment of the invention, the controller is further configured to calculate a pressure ratio correction coefficient of the compressor according to the opening degree of the guide vane, calculate a critical pressure ratio of the compressor according to the pressure ratio correction coefficient and the operating pressure ratio, and calculate a critical frequency of the inverter centrifuge according to the critical pressure ratio.
According to an embodiment of the present invention, the controller calculates the pressure ratio correction coefficient by the following formula: k-a 1D3+a2*D2+ a3 × D + a4, where K is a pressure ratio correction coefficient, D is a guide vane opening degree, and a1-a4 is a first coefficient.
According to one embodiment of the present invention, the controller calculates the critical pressure ratio by the following formula: 1/K, wherein the critical pressure ratio is obtained, and the K is a pressure ratio correction coefficient.
According to one embodiment of the invention, the controller calculates the critical frequency of the variable frequency centrifuge by the following formula: y-b 12+ b2 + b3, wherein Y is the critical frequency of the variable frequency centrifuge and the critical pressure ratio, and b1-b3 is the second coefficient.
According to an embodiment of the present invention, when the controller controls the opening degree of the hot gas bypass valve according to the critical frequency and an upper operating frequency limit, if the critical frequency is greater than or equal to a first upper operating frequency limit, the opening degree of the hot gas bypass valve is gradually increased until the critical frequency is less than or equal to a second upper operating frequency limit, the opening degree of the hot gas bypass valve is stopped being increased, and if the critical frequency is less than or equal to a third upper operating frequency limit, the hot gas bypass valve is controlled to be closed, wherein the first upper operating frequency limit is equal to a product of the upper operating frequency limit and the first control coefficient, the second upper operating frequency limit is equal to a product of the upper operating frequency limit and the second control coefficient, the second control coefficient is less than the first control coefficient, and the third upper operating frequency limit is equal to a product of the upper operating frequency limit and the third control coefficient, the third control coefficient is less than the second control coefficient.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which,
FIG. 1 is a flow chart of a method for controlling a hot gas bypass valve in a variable frequency centrifuge according to one embodiment of the invention;
FIG. 2 is a schematic diagram of a variable frequency centrifuge according to one embodiment of the present invention; and
FIG. 3 is a flow chart of a control method of a hot gas bypass valve in a variable frequency centrifuge according to another embodiment of the invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
The following describes a control method of a hot gas bypass valve in a variable frequency centrifuge, a non-transitory computer readable storage medium, and a variable frequency centrifuge according to an embodiment of the present invention with reference to the drawings.
FIG. 1 is a flow chart of a control method of a hot gas bypass valve in a variable frequency centrifuge according to one embodiment of the invention. As shown in fig. 2, the inverter centrifuge includes a compressor, and a hot gas bypass valve is disposed between a gas suction pipe and a gas discharge pipe of the compressor; as shown in fig. 1, the method comprises the steps of:
and S1, when the variable frequency centrifuge is in the running state, obtaining the guide vane opening D, the running pressure ratio 1 and the running frequency upper limit Fmax of the compressor. The operation pressure ratio 1 is a ratio of an exhaust absolute pressure to an intake absolute pressure of the compressor, and further, the exhaust absolute pressure is equal to an exhaust pipe pressure + an atmospheric pressure, and the intake absolute pressure is equal to an intake pipe pressure + the atmospheric pressure. The upper limit Fmax of the operating frequency is the maximum operating frequency of the compressor, and can be obtained through actual measurement according to the characteristics of the compressor.
And S2, calculating the critical frequency Y of the variable frequency centrifuge according to the guide vane opening D and the operation pressure ratio 1.
And S3, controlling the opening of the hot gas bypass valve according to the critical frequency Y and the upper limit Fmax of the operating frequency.
Specifically, when the inverter centrifuge is operated at a high ambient temperature, the operating pressure ratio is greater than 1, and if the inverter centrifuge is operated at a low load, the inverter centrifuge may have a surge phenomenon. Therefore, when the variable frequency centrifuge is in an operating state, the critical frequency Y of the variable frequency centrifuge can be calculated according to the guide vane opening D and the operating pressure ratio 1, and then the opening of the hot gas bypass valve is controlled according to the critical frequency Y and the operating frequency upper limit Fmax, so that when the operating pressure ratio 1 of the variable frequency centrifuge is larger, the operating pressure ratio 1 can be reduced by adjusting the opening of the hot gas bypass valve, and the variable frequency centrifuge can stably operate under a small load. Therefore, the opening of the hot gas bypass valve is controlled, so that the variable frequency centrifuge can safely operate under the conditions of high ambient temperature and high pressure ratio under a small load, the phenomenon of compressor surge cannot occur under the operation of the small load, and the operation reliability of the variable frequency centrifuge is improved.
According to an embodiment of the invention, as shown in fig. 3, calculating the critical frequency Y of the variable frequency centrifuge according to the guide vane opening D and the operation pressure ratio 1 comprises:
s201, calculating a pressure ratio correction coefficient K of the compressor according to the guide vane opening degree D.
Further, the pressure ratio correction coefficient K may be calculated by the following formula (1):
K＝a1*D3+a2*D2+a3*D+a4 (1)
k is a pressure ratio correction coefficient, D is a guide vane opening degree, and a1-a4 is a first coefficient. The size of a1-a4 is related to the impeller of the frequency conversion centrifugal machine, and the value range can be (-5, 5).
And S202, calculating the critical pressure ratio of the compressor according to the pressure ratio correction coefficient K and the operation pressure ratio 1.
Further, the critical pressure ratio can be calculated by the following formula (2):
＝1/K (2)
wherein, the critical pressure ratio, K is the pressure ratio correction coefficient, and 1 is the running pressure ratio.
And S203, calculating the critical frequency Y of the variable frequency centrifuge according to the critical pressure ratio.
Further, the critical frequency Y of the variable frequency centrifuge can be calculated by the following equation (3):
Y＝b1*2+b2*+b3 (3)
wherein, Y is the critical frequency of the frequency conversion centrifuge and is the critical pressure ratio, and b1-b3 is the second coefficient. b1-b3 is related to the characteristics of the compressor, and the value range can be (-150, 150).
Specifically, when the variable frequency centrifuge is in an operating state, the guide vane opening degree D and the operating pressure ratio 1 of the compressor are obtained, and then the pressure ratio correction coefficient K of the compressor is calculated according to the guide vane opening degree D through the formula (1). And calculating the critical pressure ratio of the compressor according to the pressure ratio correction coefficient K and the operation pressure ratio 1 by a formula (2), and calculating the critical frequency Y of the variable frequency centrifuge according to the critical pressure ratio by a formula (3).
In the embodiment of the invention, as shown in fig. 3, the controlling the opening degree of the hot gas bypass valve according to the critical frequency Y and the operating frequency upper limit Fmax comprises:
s301, it is determined whether the critical frequency Y is equal to or greater than the first operating frequency upper limit Fmax 1. The first upper operating frequency limit Fmax1 is equal to the product of the upper operating frequency limit Fmax and the first control coefficient η 1, that is, Fmax1 ═ Fmax · η 1.
And S302, if the critical frequency Y is greater than or equal to the first operating frequency upper limit Fmax1, gradually increasing the opening degree of the hot gas bypass valve, and stopping increasing the opening degree of the hot gas bypass valve until the critical frequency Y is less than or equal to the second operating frequency upper limit Fmax 2. The second upper operating frequency limit Fmax2 is equal to the product of the upper operating frequency limit Fmax and a second control coefficient η 2, and the second control coefficient η 2 is smaller than the first control coefficient η 1. That is, Fmax2 ═ Fmax ×. η 2, and η 1 > η 2, Fmax1 > Fmax 2.
S303, determine whether the critical frequency Y is less than or equal to the third operating frequency upper limit Fmax 3. Wherein the third upper operating frequency limit Fmax3 is equal to the product of the upper operating frequency limit Fmax and a third control coefficient η 3, the third control coefficient η 3 being less than the second control coefficient η 2. That is, Fmax3 ═ Fmax ×) η 3, and η 1 > η 2 > η 3, Fmax1 > Fmax2 > Fmax 3.
And S304, if the critical frequency Y is less than or equal to the third operating frequency upper limit Fmax3, controlling the hot gas bypass valve to be closed.
Specifically, η 1, η 2, and η 3 are control coefficients, which can be actually measured according to the characteristics of the compressor, and the values of > η 2 > η 3, and η 1, η 2, and η 3 may range from (0.85, 0.99), for example, η 1 may be 0.99, η 2 may be 0.95, and η 3 may be 0.9.
When the variable frequency centrifuge is in the running state, judging whether Y is larger than or equal to Fmax eta 1, if so, controlling the opening degree of the hot gas bypass valve to gradually increase according to a fixed step number of one step per second, stopping increasing the opening degree of the hot gas bypass valve until Y is smaller than or equal to Fmax eta 2, keeping the hot gas bypass valve at the current opening degree, reducing the running pressure ratio of the variable frequency centrifuge to 1, and stably running the variable frequency centrifuge under the condition of small load. And then, continuously judging whether Y is less than or equal to Fmax eta 3 in real time, if so, indicating that the current variable frequency centrifuge completely avoids a surge region, controlling the hot gas bypass valve to be closed in order to avoid the capacity reduction caused by hot gas bypass, and if not, keeping the hot gas bypass valve at the current opening. And when the variable frequency centrifuge is not in the running state, the hot gas bypass valve is in the closing state.
In an embodiment of the invention, the hot gas bypass valve is in the form of an analog quantity.
In summary, according to the control method of the hot gas bypass valve in the variable frequency centrifuge of the embodiment of the present invention, when the variable frequency centrifuge is in the operating state, the guide vane opening degree, the operating pressure ratio, and the operating frequency upper limit of the compressor are obtained, then the critical frequency of the variable frequency centrifuge is calculated according to the guide vane opening degree and the operating pressure ratio, and then the opening degree of the hot gas bypass valve is controlled according to the critical frequency and the operating frequency upper limit. The method can ensure that the variable frequency centrifuge can safely operate under the conditions of high ambient temperature and high pressure ratio by controlling the opening of the hot gas bypass valve, and meanwhile, the surge phenomenon of a compressor can not occur under the operation of small load, thereby improving the operation reliability of the variable frequency centrifuge.
Embodiments of the present invention also provide a non-transitory computer-readable storage medium having stored thereon a computer program, which when executed by a processor, implements the above-described method for controlling a hot gas bypass valve in a variable frequency centrifuge.
According to the non-transitory computer readable storage medium provided by the embodiment of the invention, when the variable frequency centrifuge is in an operating state, the guide vane opening degree, the operating pressure ratio and the operating frequency upper limit of the compressor are obtained, then the critical frequency of the variable frequency centrifuge is calculated according to the guide vane opening degree and the operating pressure ratio, and then the opening degree of the hot gas bypass valve is controlled according to the critical frequency and the operating frequency upper limit, so that the variable frequency centrifuge can safely operate under a low load under the conditions of high ambient temperature and high pressure ratio, meanwhile, the compressor surge phenomenon cannot occur under the condition of low load operation, and the operation reliability of the variable frequency centrifuge is improved.
FIG. 2 is a schematic structural diagram of a variable frequency centrifuge according to one embodiment of the present invention. As shown in fig. 2, the variable frequency centrifuge includes: a compressor 1, a hot gas bypass valve 2, and a controller 3.
The hot gas bypass valve 2 is disposed between the intake pipe L1 and the exhaust pipe L2 of the compressor 1. The controller 3 is used for acquiring the guide vane opening D, the operation pressure ratio 1 and the operation frequency upper limit Fmax of the compressor when the variable frequency centrifuge is in an operation state, calculating the critical frequency Y of the variable frequency centrifuge according to the guide vane opening D and the operation pressure ratio 1, and controlling the opening of the hot gas bypass valve 2 according to the critical frequency Y and the operation frequency upper limit Fmax, wherein the operation pressure ratio 1 is the ratio of the exhaust absolute pressure to the suction absolute pressure of the compressor.
Specifically, as shown in fig. 2, the variable frequency centrifuge may further include an evaporator 4, a condenser 5, and the like, which is specifically shown in fig. 2 and will not be described herein again. When the frequency conversion centrifugal machine operates at a higher ambient temperature, the operation pressure ratio is larger than 1, and if the frequency conversion centrifugal machine operates at a small load, the frequency conversion centrifugal machine can generate a surge phenomenon. Therefore, when the variable frequency centrifuge is in an operating state, the controller 3 can calculate the critical frequency Y of the variable frequency centrifuge according to the guide vane opening D and the operating pressure ratio 1, and then control the opening of the hot gas bypass valve 2 according to the critical frequency Y and the operating frequency upper limit Fmax, so that when the operating pressure ratio 1 of the variable frequency centrifuge is larger, the operating pressure ratio 1 can be reduced by adjusting the opening of the hot gas bypass valve 2, and the variable frequency centrifuge can stably operate under a small load. Therefore, the opening of the hot gas bypass valve is controlled, so that the variable frequency centrifuge can safely operate under the conditions of high ambient temperature and high pressure ratio under a small load, the phenomenon of compressor surge cannot occur under the operation of the small load, and the operation reliability of the variable frequency centrifuge is improved.
How to calculate the critical frequency Y of the variable frequency centrifuge is described below with reference to specific examples.
According to an embodiment of the invention, the controller 3 is further configured to calculate a pressure ratio correction coefficient K of the compressor according to the guide vane opening D, calculate a critical pressure ratio of the compressor according to the pressure ratio correction coefficient K and the operating pressure ratio 1, and calculate a critical frequency Y of the inverter centrifuge according to the critical pressure ratio
Further, the controller 3 may calculate the pressure ratio correction coefficient K by the following formula (1):
K＝a1*D3+a2*D2+a3*D+a4 (1)
k is a pressure ratio correction coefficient, D is a guide vane opening degree, and a1-a4 is a first coefficient. The size of a1-a4 is related to the impeller of the frequency conversion centrifugal machine, and the value range can be (-5, 5).
The controller 3 may calculate the critical pressure ratio by the following equation (2):
＝1/K (2)
wherein, the critical pressure ratio, K is the pressure ratio correction coefficient, and 1 is the running pressure ratio.
The controller 3 may calculate the critical frequency Y of the variable frequency centrifuge by the following equation (3):
Y＝b1*2+b2*+b3 (3)
wherein, Y is the critical frequency of the frequency conversion centrifuge and is the critical pressure ratio, and b1-b3 is the second coefficient. b1-b3 is related to the characteristics of the compressor, and the value range can be (-150, 150).
Specifically, when the variable frequency centrifuge is in an operating state, the controller 3 obtains a guide vane opening D and an operating pressure ratio 1 of the compressor, calculates a pressure ratio correction coefficient K of the compressor according to the guide vane opening D through formula (1), calculates a critical pressure ratio of the compressor according to the pressure ratio correction coefficient K and the operating pressure ratio 1 through formula (2), and calculates a critical frequency Y of the variable frequency centrifuge according to the critical pressure ratio through formula (3).
How the opening degree of the hot gas bypass valve is controlled according to the critical frequency Y and the operating frequency upper limit Fmax is described below in connection with specific embodiments.
According to one embodiment of the invention, when the controller 3 controls the opening degree of the hot gas bypass valve according to the critical frequency Y and the operating frequency upper limit Fmax, if the critical frequency Y is greater than or equal to the first operating frequency upper limit Fmax1, the opening degree of the hot gas bypass valve is gradually increased, and the increase of the opening degree of the hot gas bypass valve is stopped until the critical frequency Y is less than or equal to the second operating frequency upper limit Fmax 2. And if the critical frequency Y is less than or equal to the third operating frequency upper limit Fmax3, controlling the hot gas bypass valve 2 to be closed. The first upper operating frequency limit Fmax1 is equal to the product of the upper operating frequency limit Fmax and a first control coefficient η 1, the second upper operating frequency limit Fmax2 is equal to the product of the upper operating frequency limit Fmax and a second control coefficient η 2, the second control coefficient η 2 is smaller than the first control coefficient η 1, the third upper operating frequency limit Fmax3 is equal to the product of the upper operating frequency limit Fmax and a third control coefficient η 3, and the third control coefficient η 3 is smaller than the second control coefficient η 2.
That is, Fmax1 ═ Fmax η 1, Fmax2 ═ Fmax η 2, Fmax3 ═ Fmax η 3, and η 1 > η 2 > η 3, Fmax1 > Fmax2 > Fmax 3.
Specifically, η 1, η 2, and η 3 are control coefficients, which can be actually measured according to the characteristics of the compressor, and the values of > η 2 > η 3, and η 1, η 2, and η 3 may range from (0.85, 0.99), for example, η 1 may be 0.99, η 2 may be 0.95, and η 3 may be 0.9.
When the variable frequency centrifuge is in a running state, the controller 3 judges whether Y is larger than or equal to Fmax eta 1, if so, the opening degree of the hot gas bypass valve can be controlled to gradually increase according to a fixed step number of one step per second, and when Y is smaller than or equal to Fmax eta 2, the opening degree of the hot gas bypass valve is stopped increasing, the hot gas bypass valve is kept at the current opening degree, at the moment, the running pressure ratio of the variable frequency centrifuge is reduced from 1, and the variable frequency centrifuge can stably run under a small load. And then, the controller 3 continuously judges whether Y is less than or equal to Fmax eta 3 in real time, if so, the current variable frequency centrifuge completely avoids a surge area, and in order to avoid the capacity reduction caused by hot gas bypass, the controller 3 controls the hot gas bypass valve 2 to be closed, and if not, the controller 3 keeps the hot gas bypass valve 2 at the current opening degree. And when the variable frequency centrifuge is not in the running state, the hot gas bypass valve is in the closing state.
In an embodiment of the invention, the hot gas bypass valve is in the form of an analog quantity.
In summary, according to the variable frequency centrifuge of the embodiment of the present invention, when the variable frequency centrifuge is in the operating state, the controller obtains the guide vane opening degree, the operating pressure ratio, and the upper operating frequency limit of the compressor, calculates the critical frequency of the variable frequency centrifuge according to the guide vane opening degree and the operating pressure ratio, and controls the opening degree of the hot gas bypass valve according to the critical frequency and the upper operating frequency limit. Therefore, the variable frequency centrifuge can safely operate under the conditions of high ambient temperature and high pressure ratio under a small load, and meanwhile, the phenomenon of compressor surge cannot occur under the operation of the small load, so that the operation reliability of the variable frequency centrifuge is improved.
In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the invention.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (3)
1. A control method of a hot gas bypass valve in a variable frequency centrifuge is characterized in that the variable frequency centrifuge comprises a compressor, the hot gas bypass valve is arranged between a gas suction pipe and a gas discharge pipe of the compressor, and the method comprises the following steps:
when the variable-frequency centrifuge is in an operating state, acquiring the guide vane opening degree, the operating pressure ratio and the operating frequency upper limit of the compressor, wherein the operating pressure ratio is the ratio of the exhaust absolute pressure and the suction absolute pressure of the compressor;
calculating a pressure ratio correction coefficient of the compressor according to the guide vane opening;
calculating a critical pressure ratio of the compressor according to the pressure ratio correction coefficient and the operation pressure ratio;
calculating the critical frequency of the variable frequency centrifuge according to the critical pressure ratio;
judging whether the critical frequency is greater than or equal to a first upper running frequency limit, wherein the first upper running frequency limit is equal to the product of the upper running frequency limit and a first control coefficient;
if the critical frequency is greater than or equal to a first upper running frequency limit, gradually increasing the opening of the hot gas bypass valve until the critical frequency is less than or equal to a second upper running frequency limit, and stopping increasing the opening of the hot gas bypass valve, wherein the second upper running frequency limit is equal to the product of the upper running frequency limit and a second control coefficient, and the second control coefficient is less than the first control coefficient;
judging whether the critical frequency is smaller than or equal to a third operation frequency upper limit, wherein the third operation frequency upper limit is equal to the product of the operation frequency upper limit and a third control coefficient, the third control coefficient is smaller than the second control coefficient, and the first control coefficient, the second control coefficient and the third control coefficient are all values which are actually measured according to the characteristics of the compressor and are smaller than 1;
if the critical frequency is less than or equal to a third upper running frequency limit, controlling the hot gas bypass valve to be closed; wherein,
calculating the pressure ratio correction coefficient by the following formula:
K＝a1*D3+a2*D2+a3*D+a4，
the K is a pressure ratio correction coefficient, the D is a guide vane opening degree, and a1-a4 is a first coefficient;
calculating the critical pressure ratio by the following formula:
＝1/K，
wherein, the critical pressure ratio is defined, the K is a pressure ratio correction coefficient, and the 1 is an operating pressure ratio;
calculating the critical frequency of the variable frequency centrifuge by the following formula:
Y＝b1*2+b2*+b3，
wherein Y is the critical frequency of the variable frequency centrifuge and is the critical pressure ratio, and b1-b3 is a second coefficient.
2. A non-transitory computer readable storage medium having stored thereon a computer program, wherein the program when executed by a processor implements a method for controlling a hot gas bypass valve in a variable frequency centrifuge as claimed in claim 1.
3. A variable frequency centrifuge, comprising:
a compressor;
a hot gas bypass valve disposed between a gas suction pipe and a gas discharge pipe of the compressor;
a controller, configured to, when the inverter centrifuge is in an operating state, obtain a guide vane opening, an operating pressure ratio, and an operating frequency upper limit of the compressor, calculate a pressure ratio correction coefficient of the compressor according to the guide vane opening, calculate a critical pressure ratio of the compressor according to the pressure ratio correction coefficient and the operating pressure ratio, calculate a critical frequency of the inverter centrifuge according to the critical pressure ratio, if the critical frequency is greater than or equal to a first operating frequency upper limit, gradually increase the opening of the hot gas bypass valve until the critical frequency is less than or equal to a second operating frequency upper limit, stop increasing the opening of the hot gas bypass valve, and if the critical frequency is less than or equal to a third operating frequency upper limit, control the hot gas bypass valve to close, where the first operating frequency upper limit is equal to a product of the operating frequency upper limit and a first control coefficient, the second upper operating frequency limit is equal to the product of the upper operating frequency limit and a second control coefficient, the second control coefficient is smaller than the first control coefficient, the third upper operating frequency limit is equal to the product of the upper operating frequency limit and a third control coefficient, the third control coefficient is smaller than the second control coefficient, the first control coefficient, the second control coefficient and the third control coefficient are all values which are actually measured according to the characteristics of the compressor and are smaller than 1, wherein the operating pressure ratio is the ratio of the exhaust absolute pressure and the suction absolute pressure of the compressor, and the controller calculates the pressure ratio correction coefficient by the following formula:
K＝a1*D3+a2*D2+a3*D+a4，
the K is a pressure ratio correction coefficient, the D is a guide vane opening degree, and a1-a4 is a first coefficient;
the controller calculates the critical pressure ratio by the following formula:
＝1/K，
wherein, the critical pressure ratio is defined, the K is a pressure ratio correction coefficient, and the 1 is an operating pressure ratio;
the controller calculates the critical frequency of the variable frequency centrifuge by the following formula:
Y＝b1*2+b2*+b3，
wherein Y is the critical frequency of the variable frequency centrifuge and is the critical pressure ratio, and b1-b3 is a second coefficient.
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| CN110529991B (en) * | 2019-09-10 | 2020-11-17 | 重庆美的通用制冷设备有限公司 | Control method and system of air conditioner, air conditioner and computer readable storage medium |
| CN112303826B (en) * | 2020-10-22 | 2022-05-20 | 青岛海尔空调电子有限公司 | Control method of air conditioning unit and air conditioning unit |
| CN112629053B (en) * | 2020-12-25 | 2023-06-13 | 青岛海信日立空调系统有限公司 | Water chilling unit and air supplementing control method |
| CN112728798B (en) * | 2021-02-05 | 2022-06-17 | 青岛海信日立空调系统有限公司 | Centrifugal compressor system and machine head adding control method thereof |
| CN113945029B (en) * | 2021-10-19 | 2023-04-25 | 青岛海尔空调电子有限公司 | Method and device for controlling refrigerant circulation system and refrigerant circulation system |
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