CN115143657A - Control method and control device for variable frequency compressor system - Google Patents
Control method and control device for variable frequency compressor system Download PDFInfo
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- CN115143657A CN115143657A CN202210672557.4A CN202210672557A CN115143657A CN 115143657 A CN115143657 A CN 115143657A CN 202210672557 A CN202210672557 A CN 202210672557A CN 115143657 A CN115143657 A CN 115143657A
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- 238000000034 method Methods 0.000 title claims abstract description 51
- 230000008569 process Effects 0.000 claims abstract description 9
- 239000007788 liquid Substances 0.000 claims description 55
- 230000008859 change Effects 0.000 claims description 5
- 230000003247 decreasing effect Effects 0.000 claims description 3
- 239000003507 refrigerant Substances 0.000 description 16
- 230000003111 delayed effect Effects 0.000 description 9
- 238000004378 air conditioning Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 230000004044 response Effects 0.000 description 3
- 238000004364 calculation method Methods 0.000 description 2
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- 238000006243 chemical reaction Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 238000005057 refrigeration Methods 0.000 description 1
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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
- F25B1/00—Compression machines, plants or systems with non-reversible cycle
- F25B1/10—Compression machines, plants or systems with non-reversible cycle with multi-stage compression
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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
- F25B41/00—Fluid-circulation arrangements
- F25B41/30—Expansion means; Dispositions thereof
- F25B41/31—Expansion valves
- F25B41/34—Expansion valves with the valve member being actuated by electric means, e.g. by piezoelectric actuators
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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
- F25B2500/00—Problems to be solved
- F25B2500/24—Low amount of refrigerant in the system
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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
- F25B2600/00—Control issues
- F25B2600/25—Control of valves
- F25B2600/2513—Expansion valves
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Abstract
The embodiment of the invention provides a control method and a control device for an inverter compressor system. The variable-frequency compressor system comprises a variable-frequency compressor, an evaporator, an electronic expansion valve and a condenser, wherein the variable-frequency compressor comprises a leading compressor and one or more lagging compressors connected with the leading compressor in parallel. The control method comprises the following steps: in the operation process of the variable-frequency compressor system, calculating the mass flow of the currently operated compressor; judging whether a lag compressor is started or not; when the lag compressor is started, the mass flow required by the lag compressor to be started is obtained based on the mass flow of the currently operated compressor; obtaining a feed-forward flow instruction of the variable-frequency compressor system based on the mass flow of the currently operated compressor and the mass flow required by the lag compressor to be started; obtaining a feedback flow instruction of the variable frequency compressor system; and controlling the opening degree of the electronic expansion valve based on the feedforward flow instruction and the feedback flow instruction of the variable-frequency compressor system.
Description
Technical Field
The embodiment of the invention relates to the technical field of air conditioner control, in particular to a control method and a control device for a variable frequency compressor system.
Background
Fig. 1 discloses a simplified schematic diagram of an air conditioning system 1. As shown in fig. 1, the air conditioning system 1 generally comprises four main functional components, respectively: a compressor 10, a condenser 15, a throttle device 14 and an evaporator 13. In the process of refrigerating the air conditioning system 1, the refrigerant actually circulates in four major components: the compressor 10 sucks a low-temperature and low-pressure gaseous refrigerant, and discharges the high-temperature and high-pressure gaseous refrigerant after compression; after the refrigerant reaches the condenser 15, the refrigerant releases liquid refrigerant with heat changing to medium temperature and high pressure into air; after reaching the throttling device 14, the refrigerant is subjected to pressure reduction and throttling to be changed into a low-temperature and low-pressure liquid refrigerant; the refrigerant reaches the evaporator 13, absorbs heat in the air, turns into a low-temperature and low-pressure gaseous refrigerant, and finally returns to the compressor 10. The throttle device 14 is typically a TXV (Thermal Expansion Valve) or an EXV (Electronic Expansion Valve). The operation principle of the thermostatic expansion valve is that a temperature sensing bulb arranged at the outlet of the evaporator 13 is used for sensing the superheat degree of refrigerant vapor (the superheat degree refers to a numerical value that the actual temperature of the vapor is higher than the evaporation temperature), so as to adjust the opening degree of the thermostatic expansion valve, thereby controlling the flow rate of liquid refrigerant entering the evaporator 13, and the control is simple but the control precision is not high. The electronic expansion valve is controlled by the main controller, so that the control is more accurate, the effect is better, and therefore, a system needing more accurate control generally adopts an EXV.
Air conditioning refrigeration systems are typically comprised of multiple compressors connected in parallel, with the compressor started first generally being referred to as the Lead (Lead) compressor and the compressor started later generally being referred to as the Lag (Lag) compressor. However, during the lag compressor start-up, for example, by controlling the evaporator 13 liquid level (condenser 15 liquid level is reversed), the liquid level is already low at the lag compressor start-up. Now to reload a compressor, more refrigerant flow will actually be required, i.e., a higher liquid level will be required. Failure to follow the speed of the EXV control algorithm results in insufficient liquid supply to the evaporator 13 and a lack of liquid resulting in too low a pressure in the evaporator 13 and further in too high a compressor operating pressure ratio.
Disclosure of Invention
An object of the embodiments of the present invention is to provide a control method and a control apparatus for an inverter compressor system, which can effectively solve the risk of shutdown caused by too low a liquid level during the delayed compressor start.
One aspect of an embodiment of the present invention provides a control method for an inverter compressor system. The variable frequency compressor system comprises a variable frequency compressor, an evaporator, an electronic expansion valve and a condenser which are connected through pipelines, wherein the variable frequency compressor comprises a leading compressor which is started in advance and one or more lagging compressors which are started in the later period, and the one or more lagging compressors are connected with the leading compressor in parallel. The control method comprises the following steps: calculating the mass flow of a currently operated compressor in the variable frequency compressor system in the operation process of the variable frequency compressor system; judging whether a lag compressor is started or not; when the lag compressor is started, obtaining the mass flow required by the lag compressor to be started based on the mass flow of the currently operated compressor; obtaining a feed-forward flow command of the variable frequency compressor system based on a mass flow of a currently operated compressor and a mass flow required by the lag compressor to be started; obtaining a feedback flow instruction of the variable frequency compressor system; and controlling the opening degree of the electronic expansion valve based on the feed-forward flow command and the feedback flow command of the inverter compressor system.
Further, the obtaining the mass flow required by the lag compressor to be started based on the mass flow of the currently operated compressor comprises: the mass flow of the compressor which is currently operated and is the same as the lag compressor to be started is used as the mass flow required by the lag compressor to be started.
Further, the obtaining the feed-forward flow command of the inverter compressor system based on the mass flow of the currently operated compressor and the mass flow required by the lag compressor to be started comprises: adding the mass flow of the currently operated compressor and the mass flow required by the started lag compressor to obtain the feed-forward flow of the variable-frequency compressor system; and calculating to obtain a feedforward flow instruction of the variable frequency compressor system based on the feedforward flow of the variable frequency compressor system and the maximum flow of the electronic expansion valve.
Further, the obtaining the feedback flow instruction of the inverter compressor system includes: calculating a liquid level error of one of the evaporator and the condenser; obtaining the feedback flow of the variable-frequency compressor system by adopting PI regulation based on the calculated liquid level error; and obtaining a feedback flow instruction of the variable frequency compressor system based on the feedback flow of the variable frequency compressor system.
Further, the calculating a liquid level error of one of the evaporator and the condenser comprises: a liquid level error of one of the evaporator and the condenser is calculated based on a liquid level set point of the one of the evaporator and the condenser, a measured actual liquid level, and a product of a differential component and a rate of liquid level change.
Further, the obtaining the feedback flow instruction of the inverter compressor system includes: calculating the accumulated feedback flow of the variable frequency compressor system; determining a settable scaling factor; multiplying the feedback flow accumulated by the variable-frequency compressor system by the proportionality coefficient to serve as the current feedback flow of the variable-frequency compressor system; and obtaining a feedback flow instruction of the inverter compressor system based on the current feedback flow of the inverter compressor system.
Further, the control method further includes: calculating a difference value of the feedforward flow of the variable-frequency compressor system; judging whether the difference value of the feedforward flow is larger than or smaller than a preset threshold value; and correspondingly processing the current feedback flow based on the judgment result.
Further, the performing, based on the result of the determination, corresponding processing on the current feedback traffic includes: when the difference value of the feedforward flow is larger than or smaller than the preset threshold value, clearing the current feedback flow or decreasing the current feedback flow according to steps; and when the difference value of the feedforward flow rate is not larger than or smaller than the preset threshold value, keeping the current feedback flow rate unchanged.
Further, the control method further includes: calculating the mass flow rate of the lag compressor in the actual running state during starting; and when the mass flow of the lag compressor in starting is greater than or equal to the mass flow of the same compressor which is already operated, the lag compressor uses the mass flow in the actual operation state of the lag compressor, and the variable frequency compressor system enters a stable state.
Another aspect of an embodiment of the present invention also provides a control apparatus for an inverter compressor system. The control apparatus includes one or more processors for implementing the control method for the inverter compressor system as described in the various embodiments above.
The control method and the control device for the variable-frequency compressor system can solve the problem of response speed of the electronic expansion valve, so that the liquid level can be controlled at a reasonable position before the start of the lag compressor, and the risk of shutdown caused by too low liquid level during the start of the lag compressor is solved.
Drawings
FIG. 1 is a simplified schematic diagram of an air conditioning system;
FIG. 2 is a simplified schematic diagram of an inverter compressor system according to one embodiment of the present invention;
FIG. 3 is a flow chart of a control method for an inverter compressor system in accordance with one embodiment of the present invention;
FIG. 4 is a step of performing corresponding processing on the current feedback flow based on the difference of the feed forward flow of the inverter compressor system according to an embodiment of the present invention;
FIG. 5 is a graph of a control method for an inverter compressor system without employing an embodiment of the present invention;
FIG. 6 is a graph illustrating a control method for an inverter compressor system employing an embodiment of the present invention.
Detailed Description
Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatus consistent with certain aspects of the invention, as detailed in the appended claims.
The terminology used in the embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Unless otherwise defined, technical or scientific terms used in the embodiments of the present invention should have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. The use of "first," "second," and similar terms in the description and in the claims does not indicate any order, quantity, or importance, but rather is used to distinguish one element from another. Also, the use of the terms "a" or "an" and the like do not denote a limitation of quantity, but rather denote the presence of at least one. "plurality" or "a number" means two or more. Unless otherwise indicated, "front," "back," "lower," and/or "upper," and the like are for convenience of description, and are not limited to one position or one spatial orientation. The word "comprising" or "comprises", and the like, means that the element or item listed as preceding "comprising" or "includes" covers the element or item listed as following "comprising" or "includes" and its equivalents, and does not exclude other elements or items. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect. As used in this specification 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.
Fig. 2 discloses a simplified schematic diagram of an inverter compressor system 2 according to an embodiment of the present invention. As shown in fig. 2, the inverter compressor system 2 according to an embodiment of the present invention may include an inverter compressor 20, an evaporator 23, an electronic expansion valve (EXV) 24, and a condenser 25 connected by pipes. The inverter compressor 20 may include a Lead (Lead) compressor 21 of a prior start and one or more Lag (Lag) compressors 22 of a later start, wherein the one or more Lag compressors 22 are connected in parallel with the Lead compressor 21, respectively.
In the inverter compressor system 2 according to the embodiment of the present invention, the opening degree of the electronic expansion valve 24 may be used for controlling the flow rate of the refrigerant, and the refrigerant is stored in the condenser 25 and the evaporator 23, so that the liquid levels of the evaporator 23 and the condenser 25 need to be controlled, and the controlled liquid level may be the liquid level of the evaporator 23 or the liquid level of the condenser 25. The purpose of the level control is to try to control the liquid level near the set liquid level, balancing the suction flow rate of the compressor 20 and the feed flow rate of the evaporator 23. However, when the inverter compressor system 2 has a delayed start-up access of the compressor 22, the inverter compressor system 2 will require more refrigerant to flow through, i.e., the evaporator 23 requires a higher liquid level. However, the slow response speed of the electronic expansion valve 24 may result in insufficient liquid supply to the evaporator 23.
In view of this, the present invention provides a control method for the inverter compressor system 2. The control method for the inverter compressor system 2 of the embodiment of the invention can solve the problem of the response speed of the electronic expansion valve 24, so that the liquid level can be controlled at a reasonable position before the start of the lag compressor 22, thereby solving the risk of shutdown caused by too low liquid level during the start of the lag compressor 22.
A control method for the inverter compressor system 2 according to an embodiment of the present invention will be described in detail with reference to fig. 3.
Fig. 3 discloses a flow chart of a control method for the inverter compressor system 2 according to an embodiment of the present invention. As shown in fig. 3, the control method for the inverter compressor system 2 according to one embodiment of the present invention may include steps S1 to S6.
In step S1, during the operation of the inverter compressor system 2, the mass flow of the currently operated compressor in the inverter compressor system 2 is calculated.
The mass flow of the compressor depends on the operating state of the compressor. Therefore, the mass flow rate of the currently operated compressor can be calculated according to the operation state of the currently operated compressor.
In step S2, it is determined whether there is a lag in the start of the compressor 22. In the case where the determination result is yes, the process proceeds to step S3.
In step S3, when there is a lag compressor 22 to start, the mass flow required for the lag compressor 22 to be started may be obtained based on the mass flow of the currently operated compressor obtained in step S2.
In one embodiment, the mass flow of the same compressor that is currently running as the lag compressor 22 to be started may be used as the mass flow required by the lag compressor 22 to be started.
Of course, if there is no compressor in the inverter compressor system 2 that is the same as the lag compressor 22 to be started, a corresponding reduction may be made based on the power levels of the currently operated compressor and the lag compressor 22 to be started.
In step S4, a feed forward flow command for the inverter compressor system 2 is obtained based on the mass flow of the currently operating compressor obtained in step S2 and the mass flow required for the lag compressor 22 to be started obtained in step S3.
In some embodiments, step S4 may further include step S41 and step S42.
In step S41, the mass flow rate of the currently operated compressor and the mass flow rate required by the delayed compressor 22 to be started may be added to obtain the feed forward flow rate of the inverter compressor system 2.
In step S42, a feed-forward flow rate command of the inverter compressor system 2 may be calculated and obtained based on the feed-forward flow rate of the inverter compressor system 2 and the maximum flow rate of the electronic expansion valve 24 obtained in step S41.
In one embodiment, the feed forward flow command for the inverter compressor system 2 may be calculated according to the following equation:
feed forward flow command =100 × maximum flow of feed forward flow/EXV
In step S5, a feedback flow command of the inverter compressor system 2 is obtained.
In some embodiments, step S5 may further include step S51 to step S53.
In step S51, a liquid level error of one of the evaporator 23 and the condenser 25 is calculated.
For example, in the embodiment of the present invention, the liquid level error of the evaporator 23 can be calculated by taking the liquid level control of the evaporator 23 as an example.
In step S52, a feedback flow rate of the inverter compressor system 2 may be derived using PI regulation based on the calculated level error.
In the embodiment of the present invention, in consideration of the stability of the control, a standard PID (Proportional, integral, derivative) control algorithm is not used, and PI regulation is adopted to obtain the feedback flow of the inverter compressor system 2.
In some embodiments, the feedback flow of the inverter compressor system 2 is calculated, for example, as shown in the following equation:
incremental feedback flow = (Kp + Ki) × current level error-Kp × previous level error
Where Kp is the proportional gain and Ki is the integral gain.
In an embodiment of the invention, the differential component is reflected in the calculated level error.
In step S51, a liquid level error of one of the evaporator 23 and the condenser 25 may be calculated based on the liquid level set point of the one of the evaporator 23 and the condenser 25 (e.g., the evaporator 23), the measured actual liquid level, and the product of the differential component and the liquid level change rate.
A specific calculation formula of the liquid level error of one of the evaporator 23 and the condenser 25 is, for example, as follows:
liquid level error = liquid level set point-actual liquid level-Kd x liquid level change rate
Where Kd is the differential component.
In step S53, a feedback flow rate command of the inverter compressor system 2 may be obtained based on the feedback flow rate of the inverter compressor system 2.
The feedback flow command of the inverter compressor system 2 may be similarly derived based on the feedback flow of the inverter compressor system 2, see the above-described calculation formula for deriving the feed forward flow command of the inverter compressor system 2 based on the feed forward flow of the inverter compressor system 2.
In step S6, the opening degree of the electronic expansion valve 24 may be controlled based on the feed-forward flow rate command of the inverter compressor system 2 obtained in step S4 and the feedback flow rate command obtained in step S5.
In some embodiments, the EXV flow command for the inverter compressor system 2 may be calculated according to the following equation:
then, the opening degree of the electronic expansion valve 24 is obtained through conversion according to the obtained EXV flow command, and the opening degree of the electronic expansion valve 24 can be controlled, so that the liquid level can be controlled at a reasonable position, and the risk of shutdown caused by too low liquid level of the evaporator 23 during the start-up of the lag compressor 22 is avoided.
Additionally, considering that there is a large change in the feed forward flow of the inverter compressor system 2 when the delayed compressor 22 is loaded into the inverter compressor system 2, two situations may occur: firstly, the feedback flow is large, and after the feedback flow and the feedforward flow are added, the opening degree of the electronic expansion valve 24 is too large, so that the risk of belt liquid exists; secondly, the feedback flow is small, the feedforward flow and the feedback flow are added together, the obtained total flow value of the electronic expansion valve 24 is still small, the opening degree of the electronic expansion valve 24 is small, the liquid level is not ready to be pulled up, and the compressor overcurrent alarm is caused.
Therefore, in some embodiments of the present invention, the obtaining the feedback flow instruction of the inverter compressor system 2 in step S5 may further include: calculating the accumulated feedback flow of the variable-frequency compressor system 2; determining a settable scaling factor; multiplying the feedback flow accumulated by the variable frequency compressor system 2 by a proportionality coefficient to be used as the current feedback flow of the variable frequency compressor system 2; and obtaining a feedback flow instruction of the inverter compressor system 2 based on the current feedback flow of the inverter compressor system 2.
Fig. 4 discloses the steps of processing the current feedback flow based on the difference of the feed forward flows of the inverter compressor system 2 according to an embodiment of the present invention. As shown in fig. 4, the control method for the inverter compressor system 2 according to the embodiment of the present invention may further include steps S7 to S9.
In step S7, a difference in the feed forward flow of the inverter compressor system 2 is calculated.
The difference between the current feed forward flow rate and the previous feed forward flow rate of the inverter compressor system 2 may be calculated.
In step S8, it is determined whether the difference in the feedforward flow rates calculated in step S7 is greater than or less than a predetermined threshold.
In step S9, the current feedback flow rate may be processed accordingly based on the result of the determination in step S8. In the case where the result of the determination is yes, the process proceeds to step S91. In the case where the result of the determination is no, the process proceeds to step S92.
In step S91, in an embodiment, when the difference of the current feedback flow rates is greater than or less than a predetermined threshold, the current feedback flow rate may be cleared. In another embodiment, when the difference of the current feedback flow rates is greater than or less than a predetermined threshold, the current feedback flow rate may be decreased in steps, so that abrupt changes may be prevented.
In step S92, when the difference between the current feedback flow rates is not greater than or less than the predetermined threshold, the current feedback flow rate is kept unchanged.
In the control method for the inverter compressor system 2 of the embodiment of the present invention, the mass flow rate in the actual operation state of the delayed compressor 22 in the starting can be calculated in real time. When the mass flow of the delayed compressor 22 in starting is greater than or equal to the mass flow of the same compressor already in operation, the delayed compressor 22 will use the mass flow in its actual operation state, and the inverter compressor system 2 enters a steady state.
It should be noted that the above description describes certain embodiments of the present disclosure. Other embodiments are within the scope of the following claims. In some cases, the actions or steps recited in the claims can be performed in a different order than in the embodiments and still achieve desirable results. In addition, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In some embodiments, multitasking and parallel processing may also be possible or may be advantageous.
FIG. 5 discloses a graph of a control method for an inverter compressor system without employing an embodiment of the present invention. The solid arrows in fig. 5 show the position of the delayed compressor start. As shown in fig. 5, in the case of not adopting the control method for the inverter compressor system according to the embodiment of the present invention, when the lag compressor is started, since the variation of the EXV opening is not significant, the suction flow of the compressor is increased too fast, resulting in the evaporator being starved.
FIG. 6 discloses a graph of a control method for an inverter compressor system employing an embodiment of the present invention. As shown in fig. 6, after the control method for the inverter compressor system according to the embodiment of the present invention is adopted, while the start-delayed compressor command is issued, the mass flow rate required by the delayed compressor to be started is obtained based on the mass flow rate of the currently operated compressor, and further, the feed-forward flow rate command of the inverter compressor system is obtained, and the opening degree of the EXV is controlled based on the feed-forward flow rate command and the feedback flow rate command. And recovering normal control after the current feed flow instruction meets the judgment condition. It can be observed from fig. 6 that the liquid level fluctuates for a short period of time, but the amplitude of the fluctuation is acceptable, i.e. the liquid level is not too low for a long time, and the liquid level is not too high for a long time. In the process, the system pressure ratio of the variable frequency compressor is effectively controlled, and the overcurrent phenomenon is not triggered. Therefore, the effectiveness of the control method for the inverter compressor system of the embodiment of the present invention was verified.
The embodiment of the invention also provides a control device (not shown) for the inverter compressor system. The control apparatus for the inverter compressor system may include one or more processors (not shown) for implementing the control method for the inverter compressor system as described in the various embodiments above.
The control device for the inverter compressor system according to the embodiment of the present invention has similar advantageous technical effects to the control method for the inverter compressor system described above, and therefore, the detailed description thereof is omitted.
The control method and the control device for the inverter compressor system according to the embodiment of the present invention are described in detail above. The control method and the control device for the inverter compressor system according to the embodiments of the present invention are described herein by using specific examples, and the above description of the embodiments is only for helping understanding the core idea of the present invention and is not intended to limit the present invention. It should be noted that, for those skilled in the art, various improvements and modifications can be made without departing from the spirit and principle of the present invention, and these improvements and modifications should fall within the scope of the appended claims.
Claims (10)
1. A control method for an inverter compressor system comprising an inverter compressor, an evaporator, an electronic expansion valve and a condenser connected by piping, said inverter compressor comprising a leading compressor of a preceding start and one or more lagging compressors of a following start, one or more of said lagging compressors being connected in parallel with said leading compressor, said control method comprising:
calculating the mass flow of a currently operated compressor in the inverter compressor system in the operation process of the inverter compressor system;
judging whether a lag compressor is started or not;
when the lag compressor is started, obtaining the mass flow required by the lag compressor to be started based on the mass flow of the currently operated compressor;
obtaining a feed-forward flow command of the variable frequency compressor system based on a mass flow of a currently operated compressor and a mass flow required by the lag compressor to be started;
obtaining a feedback flow instruction of the variable frequency compressor system; and
controlling an opening degree of the electronic expansion valve based on the feed-forward flow command and the feedback flow command of the inverter compressor system.
2. The control method according to claim 1, characterized in that: the obtaining a mass flow required for the lag compressor to be started based on a mass flow of a currently operated compressor comprises:
the mass flow of the compressor which is currently operated and is the same as the lag compressor to be started is used as the mass flow required by the lag compressor to be started.
3. The control method according to claim 1, characterized in that: the obtaining the feed forward flow command of the inverter compressor system based on the mass flow of the currently operated compressor and the mass flow required by the lag compressor to be started comprises:
adding the mass flow of the currently operated compressor and the mass flow required by the started lag compressor to obtain the feed-forward flow of the variable-frequency compressor system; and
and calculating to obtain a feed-forward flow instruction of the variable-frequency compressor system based on the feed-forward flow of the variable-frequency compressor system and the maximum flow of the electronic expansion valve.
4. The control method according to claim 1, characterized in that: the obtaining of the feedback flow instruction of the inverter compressor system comprises:
calculating a liquid level error of one of the evaporator and the condenser;
obtaining the feedback flow of the variable-frequency compressor system by adopting PI regulation based on the calculated liquid level error; and
and obtaining a feedback flow instruction of the variable frequency compressor system based on the feedback flow of the variable frequency compressor system.
5. The control method according to claim 4, characterized in that: the calculating of the liquid level error of one of the evaporator and the condenser comprises:
calculating a liquid level error for one of the evaporator and the condenser based on a liquid level set point for the one of the evaporator and the condenser, a measured actual liquid level, and a product of a differential component and a rate of liquid level change.
6. The control method according to claim 1, characterized in that: the obtaining of the feedback flow instruction of the inverter compressor system comprises:
calculating the accumulated feedback flow of the variable frequency compressor system;
determining a settable scaling factor;
multiplying the feedback flow accumulated by the variable-frequency compressor system by the proportionality coefficient to serve as the current feedback flow of the variable-frequency compressor system; and
and obtaining a feedback flow instruction of the variable frequency compressor system based on the current feedback flow of the variable frequency compressor system.
7. The control method according to claim 6, characterized in that: further comprising:
calculating a difference value of the feedforward flow of the variable-frequency compressor system;
judging whether the difference value of the feedforward flow is larger than or smaller than a preset threshold value or not; and
and correspondingly processing the current feedback flow based on the judgment result.
8. The control method according to claim 7, characterized in that: the correspondingly processing the current feedback flow based on the judgment result comprises:
when the difference value of the feedforward flow is larger than or smaller than the preset threshold value, clearing the current feedback flow or decreasing the current feedback flow according to steps; and
and when the difference value of the feedforward flow rate is not larger than or smaller than the preset threshold value, keeping the current feedback flow rate unchanged.
9. A control method according to claim 3, characterized in that: further comprising:
calculating the mass flow rate of the lag compressor in the actual running state during starting;
and when the mass flow of the lag compressor in starting is greater than or equal to the mass flow of the same compressor which is already operated, the lag compressor uses the mass flow in the actual operation state of the lag compressor, and the variable frequency compressor system enters a stable state.
10. A control device for an inverter compressor system, characterized by: comprising one or more processors for implementing a control method for an inverter compressor system according to any one of claims 1-9.
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|---|---|---|---|---|
| US4262493A (en) * | 1979-08-02 | 1981-04-21 | Westinghouse Electric Corp. | Heat pump |
| DE69204723D1 (en) * | 1991-04-23 | 1995-10-19 | Asahi Breweries Ltd | Refrigeration device consisting of a plurality of refrigeration circuits. |
| CN103946646A (en) * | 2011-11-18 | 2014-07-23 | 三洋电机株式会社 | Refrigeration unit |
| CN112728798A (en) * | 2021-02-05 | 2021-04-30 | 青岛海信日立空调系统有限公司 | Centrifugal compressor system and machine head adding control method thereof |
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2022
- 2022-06-14 CN CN202210672557.4A patent/CN115143657B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4262493A (en) * | 1979-08-02 | 1981-04-21 | Westinghouse Electric Corp. | Heat pump |
| DE69204723D1 (en) * | 1991-04-23 | 1995-10-19 | Asahi Breweries Ltd | Refrigeration device consisting of a plurality of refrigeration circuits. |
| CN103946646A (en) * | 2011-11-18 | 2014-07-23 | 三洋电机株式会社 | Refrigeration unit |
| CN112728798A (en) * | 2021-02-05 | 2021-04-30 | 青岛海信日立空调系统有限公司 | Centrifugal compressor system and machine head adding control method thereof |
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