CN117329746A - Control method of electronic expansion valve, controller and heat pump equipment - Google Patents
Control method of electronic expansion valve, controller and heat pump equipment Download PDFInfo
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- CN117329746A CN117329746A CN202311560109.6A CN202311560109A CN117329746A CN 117329746 A CN117329746 A CN 117329746A CN 202311560109 A CN202311560109 A CN 202311560109A CN 117329746 A CN117329746 A CN 117329746A
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- 238000000034 method Methods 0.000 title claims abstract description 40
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 28
- 239000007788 liquid Substances 0.000 claims abstract description 14
- 239000003507 refrigerant Substances 0.000 claims description 24
- 238000004364 calculation method Methods 0.000 claims description 18
- 238000009833 condensation Methods 0.000 claims description 16
- 230000005494 condensation Effects 0.000 claims description 7
- 230000033228 biological regulation Effects 0.000 claims description 6
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- 238000007906 compression Methods 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 239000008358 core component Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000014509 gene expression Effects 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 238000005057 refrigeration Methods 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- 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
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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
- F25B30/00—Heat pumps
- F25B30/02—Heat pumps of the compression type
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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
- F25B2600/00—Control issues
- F25B2600/25—Control of valves
- F25B2600/2513—Expansion valves
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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
- F25B2700/00—Sensing or detecting of parameters; Sensors therefor
- F25B2700/17—Speeds
- F25B2700/171—Speeds of the compressor
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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
- F25B2700/00—Sensing or detecting of parameters; Sensors therefor
- F25B2700/21—Temperatures
- F25B2700/2106—Temperatures of fresh outdoor air
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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
- F25B2700/00—Sensing or detecting of parameters; Sensors therefor
- F25B2700/21—Temperatures
- F25B2700/2115—Temperatures of a compressor or the drive means therefor
- F25B2700/21152—Temperatures of a compressor or the drive means therefor at the discharge side of the compressor
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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
- F25B2700/00—Sensing or detecting of parameters; Sensors therefor
- F25B2700/21—Temperatures
- F25B2700/2116—Temperatures of a condenser
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Mechanical Engineering (AREA)
- Thermal Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Air Conditioning Control Device (AREA)
Abstract
The invention provides a control method, a controller and heat pump equipment of an electronic expansion valve, which comprise the steps of obtaining the ambient temperature Ta, the water temperature Tw, the current frequency F and the target frequency Ft of a heat pump system during operation, calculating a first opening K1 according to the ambient temperature, the water temperature and the current frequency, calculating a second opening K2 according to the ambient temperature, the water temperature and the target frequency, and obtaining a target opening Kt according to the sum of the difference value of the first opening and the second opening and the opening K of the current electronic expansion valve; the opening degree of the corresponding electronic expansion valve is adjusted to the target opening degree, and the target opening degree is calculated through the compressor running frequency of the heat pump system, so that the opening degree of the electronic expansion valve is synchronously adjusted while the compressor frequency is changed, and the problems of compressor liquid impact and high-pressure protection caused by the discharge superheat degree and the return air superheat degree of the original system after the system stably runs are solved.
Description
Technical Field
The invention relates to the field of air conditioner heat pump systems, in particular to a control method of an electronic expansion valve, a controller and the field of heat pump equipment.
Background
The existing heat pump system has large change of environment and use condition of users, and large change of system frequency and system pressure. Switching of the heat pump system frequency from high to low frequency often occurs; in the frequency switching process, the control of the electronic expansion valve in the prior art calculates the opening of the electronic expansion valve through the target exhaust superheat degree and the return superheat degree, and the corresponding opening is relatively smaller when the frequency of the compressor is high, and the opening is larger when the frequency is low. However, in the prior art, the waiting period for adjusting the opening of the electronic expansion valve is a fixed value, when the frequency is changed from low frequency to high frequency, the electronic expansion valve calculates and adjusts the opening according to the superheat degree of the return air, and as a certain time process is needed for stabilizing the system, the calculated opening is inaccurate, and the continuous adjustment is needed, so that the problems of liquid impact and high-pressure protection of the compressor are easy to occur in the process. The superheat degree of the exhaust gas refers to the temperature difference between the exhaust pipe of the compressor or the saturation temperature corresponding to the actual condensing pressure, and the actual temperature is a few degrees higher than the saturation temperature corresponding to the actual pressure at present. The superheat degree of the return air refers to the superheat degree of the return air pipe (air suction pipe) between the evaporator and the compressor, namely the temperature difference between the section of pipeline and the outside heat due to the factors of heat preservation, heat insulation, length and the like.
Disclosure of Invention
Based on the problems, the invention provides a control method of an electronic expansion valve, which calculates the target opening degree through the operation frequency of a compressor of a heat pump system, the ambient temperature and the water temperature, adjusts the opening degree of the electronic expansion valve in real time, avoids the serious mismatch problem between the opening degree of the electronic expansion valve and the current operation frequency, and effectively prevents the liquid impact and the high-pressure protection of the compressor.
The invention is realized by the following technical scheme:
in one aspect, the present invention provides a control method of an electronic expansion valve, including the steps of:
acquiring the ambient temperature Ta, the water temperature Tw, the current frequency F and the target frequency Ft when the heat pump system is operated, calculating a first opening K1 according to the ambient temperature, the water temperature and the current frequency, and calculating a second opening K2 according to the ambient temperature, the water temperature and the target frequency;
the opening calculation formula specifically comprises the following steps:
K＝a*F+c*Tw+d*Ta+b
wherein K is the opening degree of the electronic expansion valve, F is the running frequency of the compressor, ta is the ambient temperature, and Tw is the water temperature; a. b, c and d are coefficients calculated by drawing point approximate straight line functions according to opening degrees K corresponding to different working conditions of the system at different frequencies;
obtaining a target opening Kt according to the sum of the difference between the first opening and the second opening and the opening K of the current electronic expansion valve;
and adjusting the opening of the corresponding electronic expansion valve to the target opening.
Further, after reaching the target opening, the heat pump system stably operates for a first time T1 and then enters PID regulation, and whether the state of the heat pump system meets a first preset condition is judged;
if the first preset condition is met, judging whether the state of the heat pump system meets the second preset condition according to the exhaust superheat degree and the exhaust target superheat degree, acquiring a plurality of preset value range intervals, and calculating the target return air superheat degree according to a preset calculation formula when the difference value between the exhaust superheat degree and the exhaust target superheat degree is positioned in the corresponding value range interval;
and calculating opening variation according to a preset P, I, D coefficient, the air return superheat degree increment and the target difference value of the current superheat degree domain, and finishing fine adjustment of the electronic expansion valve according to the opening variation.
Further, the specific calculation formula of the opening degree variation is as follows:
Δk=p×return air superheat increment+i×difference between the current return air superheat and the target return air superheat+d×return air superheat increment.
The delta K is opening variation, the return air superheat degree increment is calculated by comparing the detected current return air superheat degree of the heat pump system with the last return air superheat degree, and the return air superheat degree increment rate is calculated by comparing the difference between the current return air superheat degree and the last return air superheat degree and the difference between the last return air superheat degree and the last return air superheat degree; and P, I, D coefficients are set according to the time-varying curve of each system electronic expansion valve.
Further, the first preset condition is specifically:
the running time of the compressor is less than or equal to 15min, the ambient temperature is more than or equal to 5 ℃, or the ambient temperature is less than 3.5 ℃ or the storage gear of the compressor is more than or equal to 8.
Further, the second preset condition is specifically:
when the discharge superheat degree gE is less than the discharge target superheat degree eov, the following judgment is made;
if eov-gE >3 x l, go=5go1;
if 3*L is greater than or equal to eov-gE >2 x L, go=go=5go1-3.5 x (3*L- (eov-gE))/L;
if 2*L is greater than or equal to eov-gE >1 x L, go=5go1-3.5-2.5 x (2*L- (eov-gE))/L;
if 1*L is greater than or equal to eov-gE >0, go=5go1-6-2 (L- (eov-gE))/L;
wherein eov is the target superheat degree of the exhaust gas, gE is the superheat degree of the exhaust gas, gO is the target superheat degree of the return gas, and gO1 is a preset superheat degree parameter of the return gas; l is a scaling factor, L >2.
Further, before judging whether the heat pump system state meets the second preset condition, the method further comprises:
acquiring a preset exhaust protection frequency-limiting temperature value and a real-time condensation temperature, and calculating the difference value of the two temperatures; if the temperature TP 2-condensation temperature is greater than 45 ℃, gE is greater than 45 ℃, or the temperature TP 2-condensation temperature is less than 45 ℃, gE is greater than the temperature TP 2-condensation temperature, gO=0, otherwise, whether the state of the heat pump system meets the second preset condition is continuously judged.
In another aspect, the present invention also provides an electronic expansion valve controller comprising:
frequency opening degree calculation unit: acquiring the ambient temperature Ta, the water temperature Tw, the current frequency F and the target frequency Ft when the heat pump system is operated, calculating a first opening K1 according to the ambient temperature, the water temperature and the current frequency, and calculating a second opening K2 according to the ambient temperature, the water temperature and the target frequency;
the opening calculation formula specifically comprises the following steps:
K＝a*F+c*Tw+d*Ta+b
wherein K is the opening degree of the electronic expansion valve, F is the running frequency of the compressor, ta is the ambient temperature, and Tw is the water temperature; a. b, c and d are coefficients calculated by drawing point approximate straight line functions according to opening degrees K corresponding to different working conditions of the system at different frequencies;
target opening degree calculating means: obtaining a target opening Kt according to the sum of the difference between the first opening and the second opening and the opening K of the current electronic expansion valve;
opening degree adjusting means: and adjusting the opening of the corresponding electronic expansion valve to the target opening.
Further, the method further comprises the following steps:
PID regulating unit: after reaching the target opening, the heat pump system stably operates for a first time T1 and then enters PID regulation, and whether the state of the heat pump system meets a first preset condition is judged;
target return air superheat degree calculating unit: if the first preset condition is met, judging whether the state of the heat pump system meets the second preset condition according to the exhaust superheat degree and the exhaust target superheat degree, acquiring a plurality of preset value range intervals, and calculating the target return air superheat degree according to a preset calculation formula when the difference value between the exhaust superheat degree and the exhaust target superheat degree is positioned in the corresponding value range interval;
opening fine adjustment unit: and calculating opening variation according to a preset P, I, D coefficient, the air return superheat degree increment and the target difference value of the current superheat degree domain, and finishing fine adjustment of the electronic expansion valve according to the opening variation.
In another aspect, the present invention is a heat pump apparatus characterized in that: comprises a heat pump system and a controller;
the heat pump system includes: an evaporator, a compressor, a condenser, an electronic expansion valve, and a refrigerant;
the evaporator is used for evaporating the refrigerant liquid flowing in through the electronic expansion valve to obtain low-pressure refrigerant gas;
the compressor is used for pressurizing the low-pressure refrigerant gas flowing out of the evaporator to obtain high-temperature high-pressure refrigerant gas;
the condenser is used for radiating heat outwards from the high-temperature high-pressure refrigerant gas to raise the temperature of the medium and reducing the temperature and the pressure of the high-temperature high-pressure refrigerant gas to obtain refrigerant liquid;
the electronic expansion valve controls the flow of the refrigerant through valve opening adjustment;
the controller is used for controlling the opening degree adjustment of the electronic expansion valve according to the control method of the electronic expansion valve.
In summary, according to the control method of the electronic expansion valve provided by the invention, the target opening degree is calculated through the compressor operation frequency of the heat pump system, so that the opening degree of the electronic expansion valve is synchronously adjusted while the compressor frequency is changed, and the problems of compressor liquid impact and high-pressure protection caused by the discharge superheat degree and the return air superheat degree after the original system is stably operated are solved. After the compressor stably operates, the opening degree of the electronic expansion valve is finely adjusted to the optimal state through the exhaust superheat degree and the return air superheat degree, so that the overall energy efficiency of the heat pump system is further improved, and the real-time high-energy efficiency output is achieved. For a better understanding and implementation, the present invention is described in detail below with reference to the drawings.
Drawings
FIG. 1 is a flow chart of a control method of an electronic expansion valve provided by the invention;
fig. 2 is a block diagram of a controller performing a control method of the electronic expansion valve shown in fig. 1;
Detailed Description
In a heat pump system of an air conditioner, a device for converting low-temperature heat energy in an environment into high-temperature heat energy is a complete heat pump system, which generally comprises the following components: an evaporator, a compressor, a condenser, an electronic expansion valve, some other auxiliary equipment, etc. The compressor is a core component of a heat pump system, and is responsible for sucking and pressurizing refrigerant from an evaporator, and the temperature and the pressure of the refrigerant are increased through compression to form high-temperature and high-pressure gas. The electronic expansion valve is a key component in the heat pump system, the control unit in the heat pump system controls the refrigeration cycle by adjusting the opening of the electronic expansion valve to adjust the flow and the pressure of the refrigerant, the electronic expansion valve introduces the high-pressure liquid refrigerant into the evaporator to expand the high-pressure liquid refrigerant into low-pressure gas, so that heat absorption and temperature rise are realized, the frequency of the compressor refers to the working times of the compressor in unit time, the refrigerant is sucked and pressurized from the evaporator, the opening value is opposite to the actual opening, namely, the higher the frequency is, the smaller the opening of the required electronic expansion valve is, and the lower the frequency is, the larger the opening of the required electronic expansion valve is.
In the switching process, the opening corresponding to the electronic expansion after the frequency switching is calculated by calculating the exhaust superheat degree and the return air superheat degree, but the existing opening adjustment method needs to measure the exhaust superheat degree and the return air superheat degree to adjust the opening of the electronic expansion valve after the heat pump system stably operates for a period of time after the frequency switching, and the inventor finds that if the frequency switching amplitude is overlarge in the production process, if the opening of the electronic expansion valve is also adjusted by the existing technology, the compressor frequency and the opening of the electronic expansion valve are seriously not matched in the period of waiting for the heat pump system to stably operate, and the compressor liquid impact or the high-pressure protection condition possibly occurs, so that the risk of damaging the heat pump system exists.
The inventors have solved the above problems by the following means. Referring to fig. 1 and 2, fig. 1 is a flowchart of a control method of an electronic expansion valve according to the present invention, and fig. 2 is a block diagram of a controller for executing the control method of the electronic expansion valve shown in fig. 1; the control method of the electronic expansion valve comprises the following specific steps:
s10: the method comprises the steps of obtaining the ambient temperature Ta, the water temperature Tw, the current frequency F and the target frequency Ft when the heat pump system is in operation, calculating a first opening K1 according to the ambient temperature, the water temperature and the current frequency, and calculating a second opening K2 according to the ambient temperature, the water temperature and the target frequency. Step S10 is performed by the frequency opening degree calculation unit 10.
In this embodiment, the ambient temperature Ta and the water temperature Tw in the current operation state of the heat pump and heat pump system and the current frequency F of the operation of the compressor are first obtained, and the opening degree of the electronic expansion valve is calculated under this condition, and this opening degree is taken as the first opening degree K1, specifically, the opening degree calculation formula thereof is as follows:
K＝a*F+c*Tw+d*Ta+b
wherein K is the opening degree of the electronic expansion valve, F is the running frequency of the compressor, ta is the ambient temperature, and Tw is the water temperature; a is a frequency coefficient, b is a constant, c is an ambient temperature coefficient, and d is a water temperature coefficient.
In the invention, the inventor obtains a plurality of groups of quaternary one-time equations of opening and environmental conditions by presetting operation conditions of different heat pump systems for a plurality of times, screens out a plurality of groups of data with optimal opening adjustment, obtains a group of relational expressions, and obtains corresponding a, b, c, d four coefficients by simultaneous solution.
And substituting the ambient temperature, the water temperature and the target frequency Ft into an opening calculation formula in the same way, obtaining the ideal electronic expansion valve opening at the target frequency of the operation of the compressor, and taking the opening as a second opening.
S20: and obtaining a target opening Kt according to the sum of the difference between the first opening and the second opening and the opening K of the current electronic expansion valve. Step S20 is performed by the target opening degree calculation unit 10.
The opening K of the current electronic expansion valve is not necessarily the same as the first opening, because there may be a plurality of operations of switching the compressor gear in a short time during the operation of the heat pump system, at this time, during the process of switching the compressor gear, there may be a certain difference between the opening of the current electronic expansion valve and the current operation frequency of the compressor, in order to avoid this difference value, the difference value between the first opening and the second opening is taken as the opening adjustment amount, and then the sum of the opening of the current electronic expansion valve and the opening adjustment amount is taken as the target opening.
S30: and adjusting the opening of the corresponding electronic expansion valve to the target opening. Step S30 is performed by the opening degree adjustment unit 30.
In another preferred embodiment, if the frequency of the target frequency Ft exceeds the threshold value of the compressor frequency in the current operating environment, the target opening degree is calculated with the threshold frequency as the target frequency.
Frequency limiting refers to: the limiting frequency exceeds a certain preset threshold, for example, when the ambient temperature is high, the frequency cannot be opened too high, at which time the frequency range needs to be controlled by limiting the frequency.
By the method, the opening degree of the electronic expansion valve can be adjusted timely when the compressor shifts according to the current environment temperature, the water temperature, the current operating frequency and the target operating frequency of the compressor in the operation process of the heat pump system, so that the operating frequency of the compressor is matched with the opening degree of the electronic expansion valve, and the problems of liquid impact and high-pressure protection of the compressor are prevented.
In addition, in the actual operation process of the heat pump system of the heat pump, the inventor adopts the frequency of the compressor to adjust, so that the system can calculate the opening according to the superheat degree of the exhaust gas and the superheat degree of the return gas after the system does not need to wait for stabilization, thereby accelerating the matching speed of the opening of the electronic expansion valve and the current operation frequency, avoiding the problems of liquid impact of the compressor and high-pressure protection, but having certain defect in the adjustment precision, namely the target opening kt is not completely matched with the operation state of the heat pump system, and influencing the efficiency of the heat pump system. Based on this, the inventors further studied to fine-tune the opening degree of the electronic expansion valve to an optimal state in combination of the air superheat degree and the return air superheat degree. The method comprises the following specific steps:
s40: after reaching the target opening, the heat pump system stably runs for a first time T1, enters PID regulation (proportional, integral and differential control regulation), and judges whether the state of the heat pump system meets a first preset condition. Step S40 is performed by the PID adjusting unit 40.
When the target opening is reached, the heat pump system needs to continuously run for a period of time, and after the stable running state of the heat pump system is ensured, the electronic expansion valve opening can be finely adjusted according to the running environment parameters of the heat pump system at the moment. The running time of the compressor is less than or equal to 15min, the ambient temperature is more than or equal to 5 ℃, or the ambient temperature is less than 3.5 ℃ or the storage gear of the compressor is more than or equal to 8; when the heat pump system state meets the first preset condition, whether the heat pump system state meets the second preset condition is judged.
S50: if the first preset condition is met, judging whether the state of the heat pump system meets the second preset condition according to the exhaust superheat degree and the exhaust target superheat degree, acquiring a plurality of preset value range intervals, and calculating the target return air superheat degree according to a preset calculation formula when the difference value between the exhaust superheat degree and the exhaust target superheat degree is located in the corresponding value range interval. Step S50 is performed by the target return air superheat calculation unit 50.
The preset value range interval is set according to different heat pump systems, and in the invention, the specific setting is as follows:
when the discharge superheat degree gE is less than the discharge target superheat degree eov, the following judgment is made;
if eov-gE >3 x l, go=5go1;
if 3*L is greater than or equal to eov-gE >2 x L, go=go=5go1-3.5 x (3*L- (eov-gE))/L;
if 2*L is greater than or equal to eov-gE >1 x L, go=5go1-3.5-2.5 x (2*L- (eov-gE))/L;
if 1*L is greater than or equal to eov-gE >0, go=5go1-6-2 (L- (eov-gE))/L;
wherein eov is the target superheat degree of the exhaust gas, gE is the superheat degree of the exhaust gas, gO is the target superheat degree of the return gas, and gO1 is a preset superheat degree parameter of the return gas; l is a scaling factor, L >2.
S60: and calculating opening variation according to a preset P, I, D coefficient, the air return superheat degree increment and the target difference value of the current superheat degree domain, and finishing fine adjustment of the electronic expansion valve according to the opening variation. Step S60 is performed by the opening degree fine adjustment unit 60.
The opening degree variation is calculated according to the following formula:
delta k=p×return air superheat increment+i×difference between the current return air superheat and the target return air superheat+d×return air superheat increment;
the return air superheat degree increment is calculated by comparing the detected return air superheat degree of the heat pump system with the previous return air superheat degree, and the return air superheat degree increment rate is calculated by comparing the difference between the current return air superheat degree and the previous return air superheat degree and the difference between the previous return air superheat degree and the previous return air superheat degree; and P, I, D coefficients are set according to the time-varying curve of each system electronic expansion valve.
At the moment, the opening degree of the electronic expansion valve is finely adjusted according to the calculated opening degree variation, the overall energy efficiency of the heat pump system is improved, and the real-time high-energy efficiency output is achieved.
In another embodiment, before determining whether the state of the heat pump system satisfies the first preset condition, the method further includes obtaining an exhaust temperature value and a condensation temperature, if the operation time of the heat pump system is greater than a preset value, if the difference between the average value of the exhaust temperature and the condensation temperature is less than 3 ℃, calculating the target superheat degree gO of the return air by using the following formula
gO＝10-8.0*Count/T
Wherein T is a statistical period, and the unit of Count is once 1 second;
and calculating the opening variation according to the corresponding parameters to finish the fine adjustment of the electronic expansion valve.
In another embodiment, before determining whether the heat pump system state meets the second preset condition, the method further includes: and acquiring a preset exhaust protection frequency-limiting temperature value and a real-time condensation temperature, and calculating the difference value of the two temperatures.
If the temperature of the exhaust protection frequency limit value TP 2-condensation is more than 45 ℃, gE is more than 45 ℃, or the temperature of the exhaust protection frequency limit value TP 2-condensation is less than 45 ℃, gE is more than the temperature of the exhaust protection frequency limit value TP 2-condensation. And gO=0, otherwise, continuing to judge whether the state of the heat pump system meets a second preset condition.
In summary, the invention provides a control method of an electronic expansion valve, which firstly calculates a target opening degree through the operation frequency of a compressor of a heat pump system, so that the opening degree of the electronic expansion valve is synchronously adjusted while the frequency of the compressor is changed, and the problems of liquid impact and high-pressure protection of the compressor caused by the discharge superheat degree and the return air superheat degree of the original system after the system stably operates are solved. After the compressor stably operates, the opening degree of the electronic expansion valve is finely adjusted to the optimal state through the exhaust superheat degree and the return air superheat degree, so that the overall energy efficiency of the heat pump system is further improved, and the real-time high-energy efficiency output is achieved.
Based on the same inventive concept, the present invention further provides an electronic device, which may be a terminal device such as a server, a desktop computing device, or a mobile computing device (e.g., a laptop computing device, a handheld computing device, a tablet computer, a netbook, etc.). The device comprises one or more processors and a memory, wherein the processors are used for executing programs to realize the control method of the electronic expansion valve; the memory is used for storing a computer program executable by the processor.
Based on the same inventive concept, the present invention also provides a computer-readable storage medium, corresponding to the embodiment of the control method of an electronic expansion valve described above, having stored thereon a computer program which, when executed by a processor, implements the steps described in any of the embodiments described above.
The present invention may take the form of a computer program product embodied on one or more storage media (including, but not limited to, magnetic disk storage, CD-ROM, optical storage, etc.) having program code embodied therein. Computer-usable storage media include both permanent and non-permanent, removable and non-removable media, and information storage may be implemented by any method or technology. The information may be computer readable instructions, data structures, modules of a program, or other data. Examples of storage media for a computer include, but are not limited to: phase change memory (PRAM), static Random Access Memory (SRAM), dynamic Random Access Memory (DRAM), other types of Random Access Memory (RAM), read Only Memory (ROM), electrically Erasable Programmable Read Only Memory (EEPROM), flash memory or other memory technology, compact disc read only memory (CD-ROM), digital Versatile Disks (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices, or any other non-transmission medium, may be used to store information that may be accessed by the computing device.
The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that modifications and improvements can be made by those skilled in the art without departing from the spirit of the invention, and the invention is intended to encompass such modifications and improvements.
Claims (10)
1. A control method of an electronic expansion valve, applied to a heat pump system, comprising the steps of:
acquiring the ambient temperature Ta, the water temperature Tw, the current frequency F and the target frequency Ft when the heat pump system is operated, calculating a first opening K1 according to the ambient temperature, the water temperature and the current frequency, and calculating a second opening K2 according to the ambient temperature, the water temperature and the target frequency;
the opening calculation formula specifically comprises the following steps:
K＝a*F+c*Tw+d*Ta+b
wherein K is the opening degree of the electronic expansion valve, F is the running frequency of the compressor, ta is the ambient temperature, and Tw is the water temperature; a. b, c and d are coefficients calculated by drawing point approximate straight line functions according to opening degrees K corresponding to different working conditions of the system at different frequencies;
obtaining a target opening Kt according to the sum of the difference between the first opening and the second opening and the opening K of the current electronic expansion valve;
and adjusting the opening of the corresponding electronic expansion valve to the target opening.
2. The control method of an electronic expansion valve according to claim 1, characterized by further comprising:
after reaching the target opening, the heat pump system stably operates for a first time T1 and then enters PID regulation, and whether the state of the heat pump system meets a first preset condition is judged;
if the first preset condition is met, judging whether the state of the heat pump system meets the second preset condition according to the exhaust superheat degree and the exhaust target superheat degree, acquiring a plurality of preset value range intervals, and calculating the target return air superheat degree according to a preset calculation formula when the difference value between the exhaust superheat degree and the exhaust target superheat degree is positioned in the corresponding value range interval;
and calculating opening variation according to a preset P, I, D coefficient, the air return superheat degree increment and the target difference value of the current superheat degree domain, and finishing fine adjustment of the electronic expansion valve according to the opening variation.
3. The control method of an electronic expansion valve according to claim 2, wherein the specific calculation formula of the opening degree variation is as follows:
Δk=p×return air superheat increment+i×difference between the current return air superheat and the target return air superheat+d×return air superheat increment.
The delta K is opening variation, the return air superheat degree increment is calculated by comparing the detected current return air superheat degree of the heat pump system with the last return air superheat degree, and the return air superheat degree increment rate is calculated by comparing the difference between the current return air superheat degree and the last return air superheat degree and the difference between the last return air superheat degree and the last return air superheat degree; and P, I, D coefficients are set according to the time-varying curve of each system electronic expansion valve.
4. The control method of an electronic expansion valve according to claim 2, wherein the first preset condition is specifically:
the running time of the compressor is less than or equal to 15min, the ambient temperature is more than or equal to 5 ℃, or the ambient temperature is less than 3.5 ℃ or the storage gear of the compressor is more than or equal to 8.
5. The control method of an electronic expansion valve according to claim 2, wherein the second preset condition is specifically:
when the discharge superheat degree gE is less than the discharge target superheat degree eov, the following judgment is made;
if eov-gE >3 x l, go=5go1;
if 3*L is greater than or equal to eov-gE >2 x L, go=go=5go1-3.5 x (3*L- (eov-gE))/L;
if 2*L is greater than or equal to eov-gE >1 x L, go=5go1-3.5-2.5 x (2*L- (eov-gE))/L;
if 1*L is greater than or equal to eov-gE >0, go=5go1-6-2 (L- (eov-gE))/L;
wherein eov is the target superheat degree of the exhaust gas, gE is the superheat degree of the exhaust gas, gO is the target superheat degree of the return gas, and gO1 is a preset superheat degree parameter of the return gas; l is a scaling factor, L >2.
6. The control method of an electronic expansion valve according to any of claims 1 to 5, further comprising, before determining whether the state of the heat pump system satisfies the first preset condition:
acquiring an exhaust temperature value and a condensation temperature, if the running time of the heat pump system is greater than a preset value, if the difference between the average value of the exhaust temperature and the condensation temperature is less than 3 ℃, calculating the target return air superheat degree gO by adopting the following formula
gO＝10-8.0*Count/T
Where T is the statistical period and Count is in 1 second.
7. The control method of an electronic expansion valve according to claim 6, further comprising, before determining whether the heat pump system state satisfies the second preset condition:
acquiring a preset exhaust protection frequency-limiting temperature value and a real-time condensation temperature, and calculating the difference value of the two temperatures; if the temperature TP 2-condensation temperature is greater than 45 ℃, gE is greater than 45 ℃, or the temperature TP 2-condensation temperature is less than 45 ℃, gE is greater than the temperature TP 2-condensation temperature, gO=0, otherwise, whether the state of the heat pump system meets the second preset condition is continuously judged.
8. An electronic expansion valve controller, comprising:
frequency opening degree calculation unit: acquiring the ambient temperature Ta, the water temperature Tw, the current frequency F and the target frequency Ft when the heat pump system is operated, calculating a first opening K1 according to the ambient temperature, the water temperature and the current frequency, and calculating a second opening K2 according to the ambient temperature, the water temperature and the target frequency;
the opening calculation formula specifically comprises the following steps:
K＝a*F+c*Tw+d*Ta+b
wherein K is the opening degree of the electronic expansion valve, F is the running frequency of the compressor, ta is the ambient temperature, and Tw is the water temperature; a. b, c and d are coefficients calculated by drawing point approximate straight line functions according to opening degrees K corresponding to different working conditions of the system at different frequencies;
target opening degree calculating means: obtaining a target opening Kt according to the sum of the difference between the first opening and the second opening and the opening K of the current electronic expansion valve;
opening degree adjusting means: and adjusting the opening of the corresponding electronic expansion valve to the target opening.
9. The electronic expansion valve controller of claim 8, further comprising:
PID regulating unit: after reaching the target opening, the heat pump system stably operates for a first time T1 and then enters PID regulation, and whether the state of the heat pump system meets a first preset condition is judged;
target return air superheat degree calculating unit: if the first preset condition is met, judging whether the state of the heat pump system meets the second preset condition according to the exhaust superheat degree and the exhaust target superheat degree, acquiring a plurality of preset value range intervals, and calculating the target return air superheat degree according to a preset calculation formula when the difference value between the exhaust superheat degree and the exhaust target superheat degree is positioned in the corresponding value range interval;
opening fine adjustment unit: and calculating opening variation according to a preset P, I, D coefficient, the air return superheat degree increment and the target difference value of the current superheat degree domain, and finishing fine adjustment of the electronic expansion valve according to the opening variation.
10. A heat pump apparatus, characterized in that: comprises a heat pump system and a controller;
the heat pump system includes: an evaporator, a compressor, a condenser, an electronic expansion valve, and a refrigerant;
the evaporator is used for evaporating the refrigerant liquid flowing in through the electronic expansion valve to obtain low-pressure refrigerant gas;
the compressor is used for pressurizing the low-pressure refrigerant gas flowing out of the evaporator to obtain high-temperature high-pressure refrigerant gas;
the condenser is used for radiating heat outwards from the high-temperature high-pressure refrigerant gas to raise the temperature of the medium and reducing the temperature and the pressure of the high-temperature high-pressure refrigerant gas to obtain refrigerant liquid;
the electronic expansion valve controls the flow of the refrigerant through valve opening adjustment;
the controller is configured to control the opening degree adjustment of the electronic expansion valve according to a control method of the electronic expansion valve according to any one of claims 1 to 7.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311560109.6A CN117329746A (en) | 2023-11-21 | 2023-11-21 | Control method of electronic expansion valve, controller and heat pump equipment |
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| CN202311560109.6A CN117329746A (en) | 2023-11-21 | 2023-11-21 | Control method of electronic expansion valve, controller and heat pump equipment |
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| CN202311560109.6A Pending CN117329746A (en) | 2023-11-21 | 2023-11-21 | Control method of electronic expansion valve, controller and heat pump equipment |
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