A kind of method for controlling machine room air conditioner based on frequency-changeable compressor
Technical field
The present invention relates to refrigeration system, more particularly, relate to a kind of method for controlling machine room air conditioner based on frequency-changeable compressor.
Background technology
Precise machine room air conditioner is the special air conditioner for the modern electronic equipment Design of Machine Room, and its operating accuracy and reliability are all much higher than common air-conditioning.Put computer equipment and programme-controlled exchange product etc. in computer room, formed by a large amount of intensive electronic components.Improve the stable and reliability that these equipment are used, the temperature humidity of environment need be strict controlled in to particular range.
Special air conditioning for device room adopts evaporating pressure in strict control evaporimeter in design, increasing air output makes the evaporator surface temperature not dehumidify higher than the air dew point temperature, the cold produced all is used for lowering the temperature, improved operating efficiency, reduced wet amount loss (air output is large, and the air-supply enthalpy difference reduces).
Because the electronic equipment in most of machine rooms is all continuously operations, longevity of service, therefore require the special air conditioning for device room long-term continuous operation of can loading greatly in design, and will keep high reliability.Comfort air conditioning system is more difficult to meet the demands, especially in the winter time, computer room is many again because of its good airproof performance heat-producing device, still need the normal refrigeration work of air-conditioning unit, now, general comfort air conditioning system has been difficult to normal operation because outdoor condensing pressure is too low, and special air conditioning for device room, by controlled outdoor condenser, still can normally guarantee kind of refrigeration cycle work.
The air conditioner refrigerating technology belongs to common refrigeration scope, is mainly to adopt the liquid gasification refrigerating method, utilizes the liquid gasification process will absorb heat, and liquid surface pressure difference, and its boiling point is also different, and pressure is lower, and boiling point is lower.Its operation principle is exactly to make that cold-producing medium is compressed in the heat power equipments such as compressor, condenser, expansion valve and evaporimeter, heat release, connect stream and four the main thermal processions of absorbing heat, to complete kind of refrigeration cycle.The process of refrigerastion of air-conditioning is the process of another environment that heat is moved from an environment.The line voltage of China is 220 volts, 50 hertz, and the air-conditioning of working under this condition is referred to as " fixed frequency air conditioner ".Because frequency of supply can not change, the compressor rotary speed of traditional fixed frequency air conditioner is substantially constant, rely on it constantly " to drive, stop " compressor and adjust indoor temperature, one is opened one and is easily caused room temperature sometimes hot and sometimes cold between stopping, and consume more electric energy, as shown in Figure 1, room temperature changes fluctuation greatly, be very unfavorable to those sophisticated electronicses like this, affect service life.In traditional air-conditioning is controlled, pressure of inspiration(Pi) and suction temperature by detection system, can obtain by the mode of tabling look-up the degree of superheat of system, the independent degree of superheat of passing through system is controlled the aperture of electric expansion valve, can make the control of system overheat degree relatively lag behind, be difficult to make the degree of superheat to be stabilized near the set goal value.
Summary of the invention
The technical problem to be solved in the present invention is, regulating temperature for the fixed frequency air conditioner of prior art easily causes room temperature sometimes hot and sometimes cold, and consume more electric energy, and rely on separately the degree of superheat to control the aperture of electric expansion valve, the defect that the control of the degree of superheat of system is relatively lagged behind, provide a kind of method for controlling machine room air conditioner based on frequency-changeable compressor overcome the above problems.
The technical solution adopted for the present invention to solve the technical problems is: a kind of method for controlling machine room air conditioner based on frequency-changeable compressor is provided, and described air conditioner in machine room comprises frequency-changeable compressor, condenser, electric expansion valve, evaporimeter, said method comprising the steps of:
S1, air conditioner in machine room initialize, and electric expansion valve is carried out to rezero operation;
S2, unlatching evaporimeter, according to the blower fan wind speed of pressure of inspiration(Pi) Ps adjustment evaporimeter;
S3, unlatching frequency-changeable compressor, per interval t, according to indoor temperature T
0with preset temperature T
a, the frequency H of adjusting frequency-changeable compressor;
S4, after frequency-changeable compressor is opened elapsed time T2 open cold condenser, and open the atomization motor simultaneously; Every time T 3, according to pressure at expulsion P
dwith EAT T
dblower fan wind speed to condenser is controlled;
S5, control the aperture Pm of electric expansion valve, adopt PI to control the aperture of electric expansion valve, simultaneously, to the change of frequency-changeable compressor frequency, the aperture Pm of electric expansion valve is made to corresponding compensation.
In the method for controlling machine room air conditioner based on frequency-changeable compressor of the present invention, in described step 1, also comprise: temperature sensor, pressure sensor, fault input to described air conditioner in machine room are detected, and if any extremely, make corresponding warning and action.
In the method for controlling machine room air conditioner based on frequency-changeable compressor of the present invention, described step S2 specifically comprises:
As pressure of inspiration(Pi) Ps, during lower than PL1, evaporimeter is opened maximum air output, and the blower fan wind speed of evaporimeter is adjusted to the most at a high speed;
As pressure of inspiration(Pi) Ps, higher than PL1 during lower than PL2, every the T1 time, evaporimeter increases certain air output, and the blower fan wind speed rising one-level of evaporimeter, make pressure of inspiration(Pi) Ps rise to a rational value;
As pressure of inspiration(Pi) Ps, during higher than PL3, the wind speed of evaporimeter is switched according to the frequency of frequency-changeable compressor, every the T1 time, judges once, and low frequency is opened low speed, and high frequency is opened at a high speed, and blower fan and FREQUENCY CONTROL are directly proportional;
Described PL1<PL2<PL3, T1 are Preset Times.
In the method for controlling machine room air conditioner based on frequency-changeable compressor of the present invention, described step S3 specifically comprises: frequency-changeable compressor can carry out frequency H adjusting move a period of time under CF H1 after, and the frequency H of frequency-changeable compressor is calculated as follows:
H=H1+Kp*Error+Ki*I(Error),
H1 is CF, and Kp is proportionality coefficient, and ki is integration time constant, and Error is indoor temperature T
0with preset temperature T
aerror amount, I (Error) be error amount in the past a period of time error and.
In the method for controlling machine room air conditioner based on frequency-changeable compressor of the present invention, described step S4 specifically comprises following:
As pressure at expulsion P
dduring higher than PH1 or EAT T
dduring higher than Temp1, open the high speed condensation fan, otherwise open the low speed condensation fan.
In the method for controlling machine room air conditioner based on frequency-changeable compressor of the present invention, in described step 5, the Pm specific algorithm of electric expansion valve is as follows:
Pm=E1+Kp*Error+Ki*I(Error)+Kx*(ΔCompressorHz)
Wherein, the aperture that E1=600 is electronic expansion valve controls, Kp is proportionality coefficient, ki is integration time constant, the error amount that Error is twice degree of superheat in front and back, I (Error) be degree of superheat error amount in the past a period of time error and, Δ CompressorHz is frequency-changeable compressor frequency-splitting in twice control, Kx* (Δ CompressorHz) is the correction that electronic expansion valve opening changes compressor frequency, the principal function that Kp*Error+Ki*I (Error) carries out PI control for electric expansion valve.
Implement the method for controlling machine room air conditioner based on frequency-changeable compressor of the present invention, there is following beneficial effect: according to the frequency of indoor temperature and preset temperature adjusting frequency-changeable compressor, regulate the rotating speed of frequency-changeable compressor, rely on the speed of frequency-changeable compressor rotating speed to reach the purpose of controlling room temperature, indoor temperature fluctuation is little, power consumption is few, and comfort level improves greatly; To the change of compressor frequency, the aperture of electric expansion valve is made to corresponding compensation simultaneously, make the degree of superheat be stabilized in set-point, improve the refrigerating efficiency COP of air conditioner in machine room.
The accompanying drawing explanation
Below in conjunction with drawings and Examples, the invention will be further described, in accompanying drawing:
Fig. 1 is existing fixed air conditioner in machine room temperature profile frequently;
Fig. 2 is the structure chart of the air conditioner in machine room based on frequency-changeable compressor of the embodiment of the present invention;
Fig. 3 is the method for controlling machine room air conditioner flow chart based on frequency-changeable compressor of the embodiment of the present invention;
Fig. 4 is the indoor temperature curve map of the method for controlling machine room air conditioner based on frequency-changeable compressor of the embodiment of the present invention;
Fig. 5 is the degree of superheat curve map of the method for controlling machine room air conditioner based on frequency-changeable compressor of the embodiment of the present invention.
The specific embodiment
In order to make purpose of the present invention clearer, below in conjunction with drawings and Examples, the present invention is further elaborated.Should be appreciated that specific embodiment described herein, only in order to explain the present invention, is not intended to limit the present invention.
As shown in Figure 2, use the air conditioner in machine room of the method for controlling machine room air conditioner based on frequency-changeable compressor of the present invention to comprise: frequency-changeable compressor 1, condenser 2, electric expansion valve 3, evaporimeter 4, form the refrigeration system of " compression, condensation, expansion step-down, a heat absorption evaporation " iterative cycles, adopt frequency-changeable compressor 1 in air conditioner in machine room, by changing the frequency of supply of compressor 1 frequently, regulate frequency-changeable compressor 1 rotating speed, rely on the speed of frequency-changeable compressor 1 rotating speed to reach the purpose of controlling room temperature, indoor temperature fluctuation is little, power consumption is few, and its comfort level improves greatly.Be provided with inspiratory pressure sensor on evaporimeter 4, for measuring the pressure of inspiration(Pi) Ps of evaporimeter 4; Also be provided with the suction temperature sensor on evaporimeter 4, for measuring the suction temperature Ts of evaporimeter 4.Be provided with back pressure transducer on condenser 2, for measuring the pressure at expulsion Pd of condenser 2, also be provided with the EAT sensor on condenser 2, for measuring the EAT Td of condenser 2.
As shown in Figure 3, the method for controlling machine room air conditioner flow chart based on frequency-changeable compressor of the embodiment of the present invention comprises the following steps:
S1, air conditioner in machine room initialize, and electric expansion valve 3 is carried out to rezero operation.
Initialized process is mainly that electric expansion valve is carried out to rezero operation, the position deviation of generation that rezero operation can be eliminated electric expansion valve 3 because stepper motor lacks step, and the aperture of later electric expansion valve 3 is controlled to be adjusted to concrete aperture Pm this zero point.In initialization also the miscellaneous part to air conditioner in machine room as temperature sensor, pressure sensor, fault input etc., detected, if any extremely, make corresponding warning and action.Pm is the concrete aperture that electric expansion valve 3 is controlled.
S2, unlatching evaporator fan 4, according to the blower fan wind speed of pressure of inspiration(Pi) Ps adjustment evaporimeter 3.The concrete control of evaporimeter is as follows: as evaporimeter pressure of inspiration(Pi) value Ps, during lower than PL1, evaporimeter 3 is opened maximum air output, and the blower fan wind speed of evaporimeter 3 is adjusted to the most at a high speed; As evaporimeter 3 pressure of inspiration(Pi) value Ps, higher than PL1 during lower than PL2, evaporimeter 3, every the T1 time, increases the blower fan air output of certain evaporimeter 3, and the blower fan wind speed rising one-level of evaporimeter 3, make evaporimeter 3 pressures of inspiration(Pi) rise to a rational value; As evaporimeter 3 pressure of inspiration(Pi) Ps during higher than PL3, the blower fan wind speed of evaporimeter 3 is switched according to the frequency of frequency-changeable compressor 1, every the T1 time, judge once, low frequency is opened low speed, high frequency is opened at a high speed, wind speed and FREQUENCY CONTROL are directly proportional, and reach the device leaving air temp that avoids evaporating too low, realize the control requirement of the little enthalpy difference of air conditioner in machine room Wind Volume.In the present embodiment, PL1=0.6MP, PL2=0.7MP, PL3=0.8MP T1=30S.
S3, unlatching frequency-changeable compressor 1, per interval t, according to indoor temperature T
0with preset temperature T
a, the frequency H of adjusting frequency-changeable compressor 1, preset temperature T
ait is the temperature that hope that the user arranges as required is adjusted to.By temperature T in temperature sensor device measuring chamber
0, preset temperature T
athe temperature that the hope arranged as required for the user is adjusted to.When frequency-changeable compressor 1 is opened, must, under specific frequency H1 after operation a period of time, can carry out frequency adjustment control, to reach the effect of protection frequency-changeable compressor 1, in the present embodiment, adopt H1=57HZ.The frequency adjustment of frequency-changeable compressor 1 is specific as follows:
According to indoor temperature T
0with preset temperature T
a, per interval t (2S) is regulated frequency-changeable compressor 1 frequency, as indoor temperature T
0be greater than preset temperature T
athe time, the frequency H of frequency-changeable compressor 1 rises; As indoor temperature T
0be less than preset temperature T
athe time, the frequency H of frequency-changeable compressor 1 descends; As indoor temperature T
0with preset temperature T
awhile equating, keep the frequency H of frequency-changeable compressor 1 constant.
Can being undertaken by revising Kp and two parameters of Ki of the frequency adjustment of frequency-changeable compressor 1, concrete control algolithm is as follows:
H=H1+Kp*Error+Ki*I(Error)
Wherein Kp is proportionality coefficient, and Ki is integration time constant; Kp controls current, and error amount and a negative constant P (expression ratio) multiply each other, then with predetermined value addition; Ki controls in the past, error amount be the past period error and, then be multiplied by a negative constant I, then with the predetermined value addition.I finds the Output rusults of air conditioner in machine room and the mean error of predetermined value from the mean error value in past; Error is error amount (being the difference of indoor temperature and preset temperature), I (Error) be error amount in the past a period of time error and.
The control interval of this algorithm is t, and air conditioner in machine room is carried out once this algorithm every t.In the present embodiment, Kp=0.5, Ki=10, t=2s.
By adjusting the frequency H of frequency-changeable compressor 1, can make to control temperature constant, reduce the number of times of frequency-changeable compressor 1 start-stop, make frequency-changeable compressor 1 finally be stabilized in a specific frequency.As shown in Figure 4, indoor temperature curve map, indoor temperature T as can be seen from Figure
0finally be stabilized near preset temperature.
S4, after frequency-changeable compressor 1 is opened elapsed time T2 open cold condenser 2, and open the atomization motor simultaneously; Every time T 3, according to pressure at expulsion P
dwith EAT T
dblower fan wind speed to condenser 2 is controlled.The concrete control of condenser 2 is as follows:
After frequency-changeable compressor 1 is opened, every the T3 time, according to pressure at expulsion P
dwith condenser 2 EAT T
dblower fan wind speed to condenser 2 is controlled.As pressure at expulsion P
dhigher than PH1 or condenser 2 EAT P
dduring higher than Temp1, open the high speed condensation fan, otherwise open the low speed condensation fan.In the present embodiment, T2=5S, T3=30S, PH1=3.2MP, Temp1=25 ℃.
S5, control the aperture Pm of electric expansion valve 3, adopt PI to control the aperture of (fuzzy control) electric expansion valve 3, simultaneously, to the change of frequency-changeable compressor 1 frequency, the aperture Pm of electric expansion valve 3 is made to corresponding compensation.By controlling the aperture of electric expansion valve (EEV), the degree of superheat (superheat) is fluctuateed near desired value, (degree of superheat obtains by tabling look-up by pressure of inspiration(Pi) and the suction temperature that gathers air conditioner in machine room) is the important means that improves air conditioner in machine room COP.Because in this air conditioner in machine room, two control object frequency-changeable compressor 1 frequencies and electric expansion valve 3 apertures are all influential to the degree of superheat, control the degrees of superheat so simple with electric expansion valve 3 and are difficult to make near the set goal value that the degree of superheat is stable.Therefore, we adopt PI to control the aperture of (fuzzy control) electric expansion valve to super heat value, simultaneously to the change of frequency-changeable compressor 1 frequency, the aperture Pm of electric expansion valve 3 are made to corresponding compensation.The aperture Pm control algolithm of electric expansion valve 3 is specially:
Pm=E1+Kp*Error+Ki*I(Error)+Kx*(ΔCompressorHz)
Wherein: the aperture that E1=600 is electronic expansion valve controls,
Kp is proportionality coefficient, and ki is integration time constant; Kp controls current, and error amount and a negative constant P (expression ratio) multiply each other, then with predetermined value addition; Ki controls in the past, error amount be the past period error and, then be multiplied by a negative constant I, then with the predetermined value addition.I finds the Output rusults of air conditioner in machine room and the mean error of predetermined value from the mean error value in past; Error is error amount (difference of indoor temperature and preset temperature), I (Error) be error amount in the past a period of time error and.
The error amount that Error is twice degree of superheat in front and back; I (Error) be degree of superheat error amount in the past a period of time error and; CompressorHz is compressor frequency difference in twice control; Kx* (Δ CompressorHz) is the correction that the EEV aperture changes compressor frequency; The principal function that Kp*Error+Ki*I (Error) carries out PI control for EEV.In the present embodiment, Kp=0.8, Ki=25, Kx=5.By this algorithm, obtain degree of superheat curve map as shown in Figure 5, under the common adjusting of electric expansion valve and frequency-changeable compressor, the degree of superheat is stabilized near the set goal value.
The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, all any modifications of doing within the spirit and principles in the present invention, be equal to and replace and improvement etc., within all should being included in protection scope of the present invention.