CN103486692A - Load self-adaptation variable-frequency multi-connection heat pump system and method for controlling compressor frequency - Google Patents

Abstract

The invention discloses a load self-adaptation variable-frequency multi-connection heat pump system and method for controlling compressor frequency. The system comprises indoor units, outdoor units, a frequency control device, and pipes connecting the indoor units and the outdoor units. Each indoor unit is provided with an indoor heat exchanger for indoor heat exchanger. Each outdoor unit is provided with a compressor. The frequency control device is used for controlling compressor frequency. The frequency control device is also used for acquiring actual measured return air temperature of the operating indoor units when number of the operating indoor units is unchanged and intaking temperature of indoor units indicating indoor load changes. Heat exchange target parameters are determined according to difference of set indoor temperature and actual measured return air temperature. Actual measured heat exchange parameters corresponding to the heat exchange target parameters are acquired, and the difference of the actual measured heat exchange parameters and the heat exchange target parameters is applied to a preset frequency control function to control the frequency of the compressors. By the system and the method, frequency control precision under refrigerating work conditions can be increased.

Description

The method of load self-adapting variable-frequency multi-connection type heat pump and control compressor frequency

Technical field

The present invention relates to variable-frequency multi-connection type heat pump control technology, relate in particular to a kind of method of load self-adapting variable-frequency multi-connection type heat pump and control compressor frequency.

Background technology

The variable-frequency multi-connection type heat pump is that a kind of complex structure, system are huge, the inner parameter height is coupled, the various complicated refrigeration system of boundary condition, has the workload demand of covering and changes greatly, connects the characteristics such as indoor set quantity is many, service condition is complicated and changeable.

Fig. 1 is existing variable-frequency multi-connection type heat pump structural representation.As shown in Figure 1, the variable-frequency multi-connection type heat pump generally is comprised of one or more off-premises station 01, one or more indoor set 02, center-control network (CS-NET) device 03, refrigerant line 04, one or more branch pipe 05 and order wire 06.Many off-premises stations 01 form outdoor unit, and center-control Network device 03 is controlled by 06 pair of outdoor unit of order wire, and off-premises station 01 is connected with indoor set 02 by refrigerant line 04 and branch pipe 05.

Off-premises station 01 generally is comprised of outdoor heat exchanger, compressor and other refrigeration annex, and outdoor heat exchanger generally adopts air-cooled or water-cooled heat exchange form; Indoor set 02 is comprised of blower fan and indoor heat exchanger etc., and indoor heat exchanger adopts the form of direct evaporation and heat-exchange.With many domestic air conditionings, compare, the off-premises station 01 of variable-frequency multi-connection type heat pump can share, thereby can effectively reduce equipment cost, and can realize the centralized management of each indoor set 02, can start separately an indoor set operation, also can start operation by many indoor sets simultaneously, make control more flexible.

In high-end field of air conditioning, the variable-frequency multi-connection type heat pump has many leading technologies such as indoor set connection, multicapacity off-premises station independent assortment of applicable changeable workload demand, many ends with it and becomes the focus of industry research.Because form, the service condition of many terminal indoor machines 02 of variable-frequency multi-connection type heat pump are complicated and changeable, the load of each indoor set will directly affect the operation at part load performance of variable-frequency multi-connection type heat pump in the reality building.Therefore, for effective energy-conservation and safeguards system reliability of operation, the part throttle characteristics of variable-frequency multi-connection type heat pump has become the important optimization direction of current research.

For meeting in real time the variation of variable-frequency multi-connection type heat pump sub-load, need be by regulating the compressor frequency in off-premises station and combining to realize compressor capacity control by the keying of multiple compressors, coordinate again the electronic expansion valve opening in indoor set, off-premises station to regulate and the rotation speed of the fan adjusting, thereby realize the control of variable-frequency multi-connection type heat pump refrigerating capacity or heating capacity, make it to adapt to the variation of sub-load.

Existing variable-frequency multi-connection type heat pump, under cooling condition, control the method for compressor frequency, the general indoor set capacity according to cooling operation, horsepower number (HP_Con (i)) is controlled compressor cooling frequency (Fc), and the formula of controlling the compressor cooling frequency is as follows:

$\mathrm{Fc}=f_1(\underset{i=1}{\overset{N}{\mathrm{\Σ}}}\mathrm{HP}\_\mathrm{Con}\left(i\right)),$

Wherein,

The indoor set horsepower number (capacity) that HP_Con (i) is i platform cooling operation;

Fc is the compressor cooling frequency, i.e. the running frequency of compressor under cooling condition;

The indoor set quantity that N is cooling operation;

F ₁() is indoor set capacity-compressor cooling FREQUENCY CONTROL function.

Under heating condition, based on three grades of target exhaust pressure maximums (Pdomax), compressor is heated to frequency (Fh) and controlled, controlling compressor, to heat the formula of frequency as follows:

Fh=f ₂(Pdo-Pd)，

Pdo=f ₃(Ps),(2.2MPa≤Pdo≤Pdomax)，

Wherein,

Fh is that compressor heats frequency;

Pdo is compressor target exhaust pressure;

Pd is the Compressor Discharge Pressure of actual measurement;

Ps is the suction pressure of compressor of actual measurement;

F ₂(), f ₃() is corresponding control function;

Pdomax is target exhaust pressure maximum, and the difference according to indoor design temperature and indoor set inlet temperature, can be divided into three grades, as shown in table 1.

The value of three grades of target exhaust pressure maximum Pdomax of table 1

Condition	Pdomax
		△Th>3	2.90MPa
1<△Th≤3	2.65MPa
		△Th≤1	2.40MPa

Wherein,

△Th=T _iset-T _i

T _isetfor indoor design temperature;

T _ifor the inlet temperature of the indoor heat exchanger in indoor set, referred to as the indoor set inlet temperature.

From above-mentioned, existing variable-frequency multi-connection type heat pump, under cooling condition, control compressor cooling frequency Fc according to the indoor set running capacity, and, under heating condition, control compressor according to variable-frequency multi-connection type heat pump pressure at expulsion, pressure of inspiration(Pi) and heat frequency Fh.Although this compressor frequency control method can adapt to preferably sub-load between each indoor set of variable-frequency multi-connection type heat pump and the scene changed occur, when each indoor set running capacity changes, the demand that the variable-frequency multi-connection type heat pump changes refrigerant flow rate.But while occurring changing for hot and cold load in single ventricle, the existing method of controlling compressor frequency, during due to refrigeration, the observed temperature parameter of indoor set is not embodied in the control strategy of compressor cooling frequency Fc, make compressor cooling FREQUENCY CONTROL precision not high, thus cause compressor volume efficiency and system energy efficiency lower; And while heating, target exhaust pressure maximum Pdomax only has three grades of values, and control accuracy is also lower.

Further, the variable-frequency multi-connection type heat pump is in actual motion, the probability of operation 100% load is less, in most of situation, operate under the little load scenarios of 50%～75% load, when little load operation, need to guarantee compressor in, the operation of low frequency section, to realize than small reduction ratio, thereby guarantee that compressor volume efficiency and system energy efficiency are higher, and existing compressor frequency control method, regulate quickly and accurately compressor frequency in the time of can not realizing load variations and control refrigerant flow rate, thereby reach the purpose of load self-adapting.

Summary of the invention

Embodiments of the invention provide a kind of load self-adapting variable-frequency multi-connection type heat pump, promote cooling condition lower compression unit frequency control accuracy.

Embodiments of the invention also provide a kind of method of controlling compressor frequency, promote cooling condition lower compression unit frequency control accuracy.

For achieving the above object, a kind of load self-adapting variable-frequency multi-connection type heat pump that the embodiment of the present invention provides, comprise: dispose the indoor set for the indoor heat exchanger of indoor heat exchange, dispose the off-premises station of compressor, for the frequency control apparatus that compressor frequency is controlled, connect the pipe arrangement of indoor set and off-premises station;

When described frequency control apparatus also means for the indoor set quantity that monitors operation does not change that the indoor set inlet temperature of indoor load changes, obtain the actual measurement return air temperature of the indoor set of operation; Determine the heat exchange target component according to the difference of described indoor design temperature and actual measurement return air temperature; Obtain the actual measurement heat exchange parameter corresponding with the heat exchange target component, and described heat exchange target component and the difference of actual measurement heat exchange parameter are applied to the frequency that default FREQUENCY CONTROL function is controlled compressor.

Preferably, if under cooling condition, described indoor load is the Indoor Thermal load, described heat exchange target component is that Indoor Thermal is handed over target temperature, described actual measurement heat exchange parameter is refrigerating operaton indoor heat exchanger liquid pipe end temperature, describedly obtain the actual measurement heat exchange parameter corresponding with the heat exchange target component, and the difference of described heat exchange target component and actual measurement heat exchange parameter is applied to default FREQUENCY CONTROL function controls the frequency of compressor and comprise:

According to definite heat exchange target component, inquire about pre-stored Indoor Thermal load correction value and the corresponding relation of heat exchange target component, obtain Indoor Thermal load correction value corresponding to definite heat exchange target component;

By the control constant set in advance and the Indoor Thermal load correction value addition of obtaining, obtain Indoor Thermal and hand over target temperature;

Calculate liquid pipe end temperature and hand over the poor of target temperature with the Indoor Thermal obtained, obtain the first difference; The liquid pipe end temperature and the Indoor Thermal that calculate in a collection period are handed over the poor of target temperature, obtain the second difference; Calculate the difference of long-pending and the second difference of the first difference of twice, then with a upper collection period in the addition of compressor cooling frequency, obtain the compressor cooling frequency.

Preferably, described frequency control apparatus comprises: monitoring modular, the first acquisition module and refrigeration frequency control module, wherein,

Whether monitoring modular, change for the indoor set quantity of moving in monitoring variable-frequency multi-connection type heat pump under cooling condition, and if so, notice refrigeration frequency control module is controlled compressor frequency according to the indoor set capacity; If indoor set quantity does not change, generate the second refrigeration trigger message;

The first acquisition module, for the second refrigeration trigger message according to from monitoring modular, monitoring means whether the indoor set inlet temperature of indoor load changes, and after monitoring the Indoor Thermal load and changing, obtains the actual measurement return air temperature of the indoor set of operation; Determine the heat exchange target component according to the difference of described actual measurement return air temperature and indoor design temperature; Obtain the actual measurement heat exchange parameter corresponding with the heat exchange target component;

The refrigeration frequency control module, for according to described heat exchange target component and the difference of actual measurement heat exchange parameter and default FREQUENCY CONTROL function, control the compressor cooling frequency.

Preferably, described refrigeration frequency control module comprises: the poor acquiring unit of return air temperature, Indoor Thermal load amending unit, Indoor Thermal are handed over target temperature computing unit, history parameters memory cell and compressor cooling frequency computation part unit, wherein,

The poor acquiring unit of return air temperature, for the indoor design temperature according in the inlet temperature of the indoor heat exchanger collected in n collection period and n collection period setting in advance, calculate both differences, obtain the maximum of both differences in n collection period, export Indoor Thermal load amending unit to;

Indoor Thermal load amending unit, for the maximum of the difference according to receiving, inquire about pre-stored Indoor Thermal load correction value and the peaked corresponding relation of difference, obtains the Indoor Thermal load correction value corresponding to maximum of the difference of reception;

Indoor Thermal is handed over the target temperature computing unit, the Indoor Thermal load correction value addition for the control constant by setting in advance with the amending unit of loading from Indoor Thermal, and the Indoor Thermal obtained in n collection period is handed over target temperature;

Compressor cooling frequency computation part unit, hand over the poor of target temperature for calculating from the liquid pipe end temperature in n collection period of the first acquisition module with hand over the Indoor Thermal of target temperature computing unit from Indoor Thermal, obtains the first difference; Read the history parameters memory cell, the compressor cooling frequency, liquid pipe end temperature and the Indoor Thermal that obtain in n-1 collection period are handed over target temperature, calculate the liquid pipe end temperature and the Indoor Thermal that read and hand over the poor of target temperature, obtain the second difference; Calculate the difference of long-pending and the second difference of the first difference of twice, then with n-1 collection period in the addition of compressor cooling frequency, obtain the interior compressor cooling frequency of n collection period;

After obtaining n the compressor cooling frequency in collection period, the compressor cooling frequency of handing over target temperature and calculating according to the liquid pipe end temperature in n the collection period received, Indoor Thermal, upgrade the corresponding information of storing in the history parameters memory cell.

Preferably, if under heating condition, described indoor load is indoor refrigeration duty, and described heat exchange target component is target exhaust pressure, the refrigerant pressure maximum that described actual measurement heat exchange parameter is oil eliminator output, describedly obtain the actual measurement heat exchange parameter corresponding with the heat exchange target component; And described heat exchange target component and the difference of actual measurement heat exchange parameter are applied to default FREQUENCY CONTROL function, the frequency of controlling compressor comprises:

According to definite heat exchange target component, inquire about the corresponding relation of pre-stored target exhaust pressure maximum and heat exchange target component, obtain target exhaust pressure maximum corresponding to definite heat exchange target component;

Obtain the refrigerant pressure minimum of a value that flows into gas-liquid separator in off-premises station, according to the refrigerant pressure minimum of a value of obtaining and the target exhaust pressure maximum obtained, calculate target exhaust pressure;

Obtain the refrigerant pressure maximum of oil eliminator output, read history parameters, the refrigerant pressure maximum, target exhaust pressure and the compressor that obtain in a collection period heat frequency, according to the refrigerant pressure maximum of obtaining from oil eliminator, the target exhaust pressure of calculating and the information read from history parameters, obtain compressor and heat frequency.

Preferably, described frequency control apparatus comprises: monitoring modular, the first acquisition module, the second acquisition module, first heat frequency control module and second and heat frequency control module, wherein,

Whether monitoring modular, change for indoor set quantity in the variable-frequency multi-connection type heat pump of monitoring heating operation, if so, heats frequency control module output first to first and heat trigger message; If indoor set quantity does not change, to the second acquisition module output second, heat trigger message;

The second acquisition module, for according to from second of monitoring modular, heating trigger message, monitor indoor refrigeration duty and whether change, after monitoring indoor refrigeration duty and changing, obtain the refrigerant pressure of oil eliminator output, export second to and heat frequency control module;

First heats frequency control module, for according to from first of monitoring modular, heating trigger message, obtains the indoor set capacity that heats running, according to the indoor set volume controlled compressor that heats running obtained, heats frequency;

Second heats frequency control module, for the target exhaust pressure according to setting in advance and the refrigerant pressure of reception, controls compressor and heats frequency.

Preferably, described second heats frequency control module comprises: the poor acquiring unit of return air temperature, target exhaust pressure correction unit, target exhaust calculation of pressure unit, history parameters memory cell and compressor heat the frequency computation part unit, wherein,

The poor acquiring unit of return air temperature, for the return air temperature collected in the indoor design temperature interior according to n collection period setting in advance and n collection period, calculate both differences, obtain the maximum of both differences in n collection period, export target exhaust pressure correction unit to;

Target exhaust pressure correction unit, maximum for the difference according to receiving, the peaked corresponding relation of query aim pressure at expulsion maximum and difference, obtain the target exhaust pressure maximum corresponding to maximum of the difference of reception, exports target exhaust calculation of pressure unit to;

Target exhaust calculation of pressure unit, for obtaining the dirty refrigerant pressure minimum of a value that enters the off-premises station gas-liquid separator of heating condition, target exhaust pressure maximum according to the refrigerant pressure minimum of a value of obtaining and reception, calculate n the target exhaust pressure that collection period is interior under heating condition, export compressor to and heat the frequency computation part unit;

Compressor heats the frequency computation part unit, for obtaining the refrigerant pressure maximum of oil eliminator output in n collection period; Read the history parameters memory cell, the refrigerant pressure maximum, the target exhaust pressure in a n-1 collection period and n-1 the interior compressor of collection period that obtain in n-1 collection period heat frequency, according to the target exhaust pressure of the refrigerant pressure maximum of obtaining, reception and the information read from the history parameters memory cell, the compressor obtained in n collection period heats frequency;

After obtaining n the compressor in collection period and heating frequency, heat frequency, the corresponding information of storing in renewal history parameters memory cell according to the refrigerant pressure maximum in the target exhaust pressure in n the collection period received, n collection period obtaining and the compressor calculated.

Preferably, described off-premises station further comprises: check valve, oil eliminator, four-way change-over valve, outdoor heat exchanger, outside fan, outside electric expansion valve, gas-liquid separator, gas side stop valve and liquid side stop valve, wherein,

The exhaust outlet of compressor is connected with the input of check valve;

The output of check valve is connected with the input of oil eliminator;

The first output of oil eliminator is connected with the first end of four-way change-over valve;

The second end of four-way change-over valve is connected with an end of outdoor heat exchanger, and the 3rd end is connected with the input of gas-liquid separator, and the 4th end is connected with an end of gas side stop valve, and the other end of gas side stop valve is connected with an end of indoor set;

The other end of outdoor heat exchanger is connected with an end of outside electric expansion valve;

The outside fan is arranged on outdoor heat exchanger one side, for by air cooling way and outdoor heat exchanger, carrying out heat exchange;

The other end of outside electric expansion valve is connected with an end of liquid side stop valve, and the other end of liquid side stop valve is connected with the other end of indoor set;

The output of gas-liquid separator is connected with the air entry of compressor.

Preferably, described off-premises station further comprises: oil return capillary and oil return solenoid valve, wherein,

The second output of oil eliminator is connected with an end of oil return solenoid valve, and the other end of oil return solenoid valve is connected with an oil return end capillaceous;

The oil return other end capillaceous is connected with the input of gas-liquid separator.

Preferably, described off-premises station further comprises: high-pressure sensor, low-pressure sensor and outdoor liquid pipe temperature sensor, wherein,

The high-pressure sensor setting is on the first output pipeline of oil eliminator;

Low-pressure sensor is arranged on the pipeline between oil return capillary and gas-liquid separator;

Outdoor liquid pipe temperature sensor is arranged on the pipeline between outdoor heat exchanger and outside electric expansion valve.

Preferably, described indoor set further comprises: indoor fan, indoor electric expansion valve, return air temperature sensor and liquid pipe end temperature sensor, wherein,

One end of indoor electric expansion valve is connected with the other end of liquid side stop valve, and the other end is connected with an end of indoor heat exchanger;

The other end of indoor heat exchanger is connected with the other end of gas side stop valve;

The indoor fan, carry out heat exchange by air-cooled mode and indoor heat exchanger;

Liquid pipe end temperature sensor, be arranged on the pipeline between an end of indoor electric expansion valve and indoor heat exchanger;

Return air temperature sensor, be arranged on the return air inlet place of indoor heat exchanger.

Preferably, described compressor is constant speed compressor or variable speed compressor; Described outdoor heat exchanger and indoor heat exchanger are aluminium foil copper tube with fins heat exchanger or the aluminum fin channel heat exchanger that declines; Described outside fan is aerofoil fan; Described indoor fan is centrifugal fan or perfusion fan.

A kind of method of controlling compressor frequency, the method comprises:

The indoor set quantity that monitors operation does not change and the indoor set inlet temperature that means indoor load while changing, and obtains the actual measurement return air temperature of the indoor set of operation;

Determine the heat exchange target component according to the difference of described indoor design temperature and actual measurement return air temperature;

Obtain the actual measurement heat exchange parameter corresponding with the heat exchange target component;

Described heat exchange target component and the difference of actual measurement heat exchange parameter are applied to default FREQUENCY CONTROL function, control the frequency of compressor.

Wherein, if under cooling condition, described indoor load is the Indoor Thermal load, and described default FREQUENCY CONTROL function is:

Fc(n)=Fc(n-1)+2{TrLave(n)-Teo(n)}-{TrLave(n-1)-Teo(n-1)}，

Wherein,

The compressor cooling frequency that Fc (n) is n collection period under cooling condition, n is natural number;

The compressor cooling frequency that Fc (n-1) is (n-1) individual collection period under cooling condition;

TrLave (n) is n collection period under cooling condition, refrigerating operaton indoor heat exchanger liquid pipe end temperature;

TrLave (n-1) is (n-1) individual collection period under cooling condition, refrigerating operaton indoor heat exchanger liquid pipe end temperature;

The Indoor Thermal that Teo (n) is n collection period under cooling condition is handed over target temperature;

The Indoor Thermal that Teo (n-1) is (n-1) individual collection period under cooling condition is handed over target temperature.

Wherein, described Indoor Thermal hands over the computing formula of target temperature to be:

Teo(n)=Pso(n)+Kt，

Wherein,

The control constant that Pso (n) is n collection period under cooling condition;

Kt is Indoor Thermal load correction value.

Wherein, if the return air temperature of operation indoor set and the return air temperature maximum difference of indoor design temperature are more than or equal to 4, described Indoor Thermal load correction value is 0;

If the return air temperature of operation indoor set and the return air temperature maximum difference of indoor design temperature equal 3, described Indoor Thermal load correction value is 1;

If the return air temperature of operation indoor set and the return air temperature maximum difference of indoor design temperature equal 2, described Indoor Thermal load correction value is 2;

If the return air temperature of operation indoor set and the return air temperature maximum difference of indoor design temperature equal 1, described Indoor Thermal load correction value is 3;

If the return air temperature of operation indoor set and the return air temperature maximum difference of indoor design temperature are less than or equal to 0, described Indoor Thermal load correction value is 5.

Wherein, described method further comprises:

Judge compressor frequency whether under lower than the compressor frequency threshold value continuous operation surpass the time threshold set in advance, if, according to the strategy set in advance, compressor frequency is promoted to the compressor frequency threshold value, after the second time threshold that continuous service sets in advance, then compressor frequency is reverted to the frequency before promoting.

Wherein, if under heating condition, described indoor load is indoor refrigeration duty, and described default FREQUENCY CONTROL function is:

Fh(n)=Fh(n-1)+25{Pdo(n)-Pdmax(n)}-15{Pdo(n-1)-Pdmax(n-1)}

Wherein,

Fh (n) heats frequency for the compressor of n collection period under heating condition;

Fh (n-1) heats frequency for the compressor of (n-1) individual collection period under heating condition;

Pdo (n) is n the interior target exhaust pressure arranged of collection period under heating condition;

Pdo (n-1) is the target exhaust pressure arranged in (n-1) individual collection period under heating condition;

The refrigerant pressure maximum that Pdmax (n) is n the interior oil eliminator output of collection period under heating condition;

Pdmax (n-1) is the refrigerant pressure maximum that under heating condition, in (n-1) individual collection period, oil eliminator is exported.

Wherein, the computing formula of described target exhaust pressure is:

$\left\{\begin{array}{c}\mathrm{Pdo}=7.7\mathrm{Ps}\min +0.4\\ 2.2\mathrm{MPa}\≤\mathrm{Pdo}\≤\mathrm{Pdo}\max \end{array}\right.$

Wherein,

Pdo is target exhaust pressure;

Psmin flows into the refrigerant pressure minimum of a value of gas-liquid separator under heating condition;

Pdomax is target exhaust pressure maximum default under heating condition, relevant to return air temperature and the indoor design temperature of operation indoor set.

As seen from the above technical solution, the method of a kind of variable-frequency multi-connection type heat pump that the embodiment of the present invention provides and control compressor frequency, control by the inlet temperature by indoor heat exchanger and liquid pipe end temperature pull-in frequency, can promote cooling condition lower compression unit frequency control accuracy; Further, increase thermic load and change the Indoor Thermal load correction value caused in the compressor frequency control strategy, realize the Indoor Thermal load self-adapting of variable-frequency multi-connection type heat pump, guarantee high energy efficiency and the low noise characteristic of compressor and system.

The accompanying drawing explanation

In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, below will the accompanying drawing of required use in embodiment or description of the Prior Art be briefly described.Apparently, the accompanying drawing in below describing is only some embodiments of the present invention, for those of ordinary skills, can also obtain according to these accompanying drawing illustrated embodiments other embodiment and accompanying drawing thereof.

Fig. 1 is existing variable-frequency multi-connection type heat pump structural representation.

Fig. 2 is embodiment of the present invention variable-frequency multi-connection type heat pump structural representation.

Fig. 3 is the method flow schematic diagram that the embodiment of the present invention is controlled compressor frequency.

The specific embodiment

Below with reference to accompanying drawing, the technical scheme of various embodiments of the present invention is carried out to clear, complete description, obviously, described embodiment is only a part of embodiment of the present invention, rather than whole embodiment.Embodiment based in the present invention, those of ordinary skills are resulting all other embodiment under the prerequisite of not making creative work, all belong to the scope that the present invention protects.

Existing variable-frequency multi-connection type heat pump, when compressor frequency is controlled, while occurring changing for the hot and cold load of single indoor set, during due to refrigeration, the observed temperature parameter of indoor set is not embodied in the control strategy of compressor frequency Fc, and while heating, target exhaust pressure maximum Pdomax only has three grades of values, makes the control accuracy of compressor frequency poor; Further, compressor volume efficiency and systematic energy efficiency ratio while not considering little load operation, make compressor volume efficiency and system energy efficiency in the variable-frequency multi-connection type heat pump lower.

In the embodiment of the present invention, for overcoming the above-mentioned deficiency of prior art, cold at single indoor set, when changing appears in thermic load, consider the observed temperature of indoor set and the impact that Indoor Thermal is handed over target temperature, a kind of load self-adapting variable-frequency multi-connection type heat pump and compressor frequency control method are proposed, on the one hand, while guaranteeing the little load operation of variable-frequency multi-connection type heat pump, compressor in, the low frequency section moves to obtain high energy efficiency and low noise characteristic, on the other hand, guarantee that the variable-frequency multi-connection type heat pump is when indoor load changes, regulate quickly and accurately compressor frequency and control refrigerant flow rate, improve the compressor frequency control accuracy, thereby reach the purpose of load self-adapting.

Fig. 2 is embodiment of the present invention variable-frequency multi-connection type heat pump structural representation.As shown in Figure 2, the variable-frequency multi-connection type heat pump adopts load self-adapting, one or more off-premises station 01, one or more indoor set 02 and frequency control apparatus 07, consists of.Wherein,

Indoor set 02 disposes the indoor heat exchanger for indoor heat exchange, off-premises station 01 disposes compressor, indoor set is connected by pipe arrangement with off-premises station, when frequency control apparatus 07 means that for the indoor set quantity that monitors operation does not change the indoor set inlet temperature of indoor load changes, obtain the actual measurement return air temperature of the indoor set of operation; Determine the heat exchange target component according to the difference of described indoor design temperature and actual measurement return air temperature; Obtain the actual measurement heat exchange parameter corresponding with the heat exchange target component; Described heat exchange target component and the difference of actual measurement heat exchange parameter are applied to default FREQUENCY CONTROL function, control the frequency of compressor.Wherein, under cooling condition, frequency control apparatus 07 comprises refrigeration FREQUENCY CONTROL first module and frequency control unit (not shown), and refrigeration FREQUENCY CONTROL first module, for being controlled compressor frequency according to the indoor set capacity under cooling condition; Frequency control unit, for monitor the indoor set quantity of operation under cooling condition: if the indoor set quantity of operation changes, notice refrigeration frequency control module is controlled compressor frequency according to the indoor set capacity; If the indoor set quantity of operation does not change, when monitoring Indoor Thermal load and change, obtain the inlet temperature of the indoor heat exchanger in the indoor set of operation and the liquid pipe end temperature of indoor heat exchanger, according to the inlet temperature of obtaining, liquid pipe end temperature and the refrigeration FREQUENCY CONTROL function that sets in advance, control the compressor cooling frequency.

Specifically,

Off-premises station 01 comprises: compressor 1, check valve 2, oil eliminator 3, four-way change-over valve 4, outdoor heat exchanger 5, outside fan 6, outside electric expansion valve 7, oil return capillary 8, oil return solenoid valve 9, gas-liquid separator 10, gas side stop valve 11 and liquid side stop valve 12.Wherein,

The exhaust outlet of compressor 1 is connected with the input of check valve 2;

The output of check valve 2 is connected with the input of oil eliminator;

The first output of oil eliminator is connected with the first end of four-way change-over valve 4 (A end), and the second output is connected with an end of oil return solenoid valve 9;

The second end of four-way change-over valve 4 (B end) is connected with an end of outdoor heat exchanger 5, the 3rd end (C end) is connected with the input of gas-liquid separator 10, the 4th end (D end) is connected with an end of gas side stop valve 11, and the other end of gas side stop valve 11 is connected with an end of indoor set 02;

The other end of outdoor heat exchanger 5 is connected with an end of outside electric expansion valve 7;

Outside fan 6 is arranged on outdoor heat exchanger 5 one sides, for by air cooling way and outdoor heat exchanger 5, carrying out heat exchange;

The other end of outside electric expansion valve 7 is connected with an end of liquid side stop valve 12, and the other end of liquid side stop valve 12 is connected with the other end of indoor set 02;

The other end of oil return solenoid valve 9 is connected with an end of oil return capillary 8;

The other end of oil return capillary 8 is connected with the input of gas-liquid separator 10;

The output of gas-liquid separator 10 is connected with the air entry of compressor 1.

In the embodiment of the present invention, oil return capillary 8 is selectable unit with oil return solenoid valve 9.

Preferably, off-premises station 01 also comprises: high-pressure sensor 60, low-pressure sensor 62 and outdoor liquid pipe temperature sensor 80.Wherein,

High-pressure sensor 60 is arranged on the first output pipeline of oil eliminator 3;

Low-pressure sensor 62 is arranged on the pipeline between oil return capillary 8 and gas-liquid separator 10;

Outdoor liquid pipe temperature sensor 80 is arranged on the pipeline between outdoor heat exchanger 5 and outside electric expansion valve 7.

Preferably, high-pressure sensor 60 is arranged in the first output of oil eliminator 3, low-pressure sensor 62 is arranged in the input (entrance) of gas-liquid separator 10 and locates, and outdoor liquid pipe temperature sensor 80 is arranged in the liquid pipe side (other end) of outdoor heat exchanger 5.

Indoor set 02 comprises: indoor fan 13, indoor electric expansion valve 14, indoor heat exchanger 15, return air temperature sensor 82, liquid pipe end temperature sensor 84.Wherein,

One end of indoor electric expansion valve 14 is connected with the other end of liquid side stop valve 12, and the other end is connected with an end of indoor heat exchanger 15;

The other end of indoor heat exchanger 15 is connected with the other end of gas side stop valve 11;

Indoor fan 13, carry out heat exchange by air-cooled mode and indoor heat exchanger 15;

Liquid pipe end temperature sensor 84, be arranged on the pipeline between an end of indoor electric expansion valve 14 and indoor heat exchanger 15;

Return air temperature sensor 82, be arranged on the return air inlet place of indoor heat exchanger 15.

In the embodiment of the present invention, return air temperature sensor 82 is arranged in the upstream of indoor heat exchanger 15, and liquid pipe end temperature sensor 84 is arranged in the liquid pipe side of indoor heat exchanger 15.

Preferably, compressor 1 is constant speed compressor or variable speed compressor, can constitute compressor bank with form in parallel by one or more.

Outdoor heat exchanger 5 and indoor heat exchanger 15 is aluminium foil copper tube with fins heat exchanger or the aluminum fin channel heat exchanger that declines.

Outside fan 6 is aerofoil fan, and the rotation of aerofoil fan makes the outdoor air outdoor heat exchanger 5 of flowing through, thereby realizes the heat exchange with outdoor heat exchanger 5.

Indoor fan 13 is centrifugal fan or perfusion fan, and the rotation of indoor fan 13 makes indoor return through indoor heat exchanger 15, thus the heat exchange of realization and indoor heat exchanger 15.

Oil return solenoid valve 9 is normal-closed electromagnetic valve, and when load self-adapting variable-frequency multi-connection type heat pump moves, oil return solenoid valve 9 energisings are opened; When load self-adapting variable-frequency multi-connection type heat pump is out of service, oil return solenoid valve 9 outages are closed.

In practical application, the frequency control apparatus of the variable-frequency multi-connection type heat pump of the embodiment of the present invention can also be further used for the indoor set quantity of monitoring operation under heating condition, if the indoor set quantity of operation changes, when monitoring indoor refrigeration duty and change, obtain the refrigerant pressure of oil eliminator output in off-premises station, according to the target exhaust pressure set in advance and the refrigerant pressure that obtains, control compressor and heat frequency.

In the embodiment of the present invention, the refrigerating function in frequency control apparatus 07 and heat-production functions are integrated in Same Physical equipment, that is:

Frequency control apparatus, for the indoor set quantity in operation, do not change, when monitoring Indoor Thermal load (cooling condition) while changing, obtain the liquid pipe end temperature of the indoor heat exchanger in the refrigerating operaton indoor set, the liquid pipe end temperature of handing over target temperature and obtaining according to the Indoor Thermal set in advance, control the compressor cooling frequency; When monitoring indoor refrigeration duty and change, obtain the refrigerant pressure of oil eliminator output, according to the target exhaust pressure set in advance and the refrigerant pressure that obtains, control compressor and heat frequency.

In the embodiment of the present invention, whether the indoor set quantity of frequency control apparatus monitoring system cold operation changes, if change, adopt the existing method of controlling compressor frequency to be controlled compressor frequency (compressor cooling frequency and compressor heat frequency); If the indoor set quantity of refrigerating operaton does not change, just monitor Indoor Thermal load or indoor refrigeration duty and change, adopt the compressor frequency control method of the embodiment of the present invention.

In practical application, when indoor load is the Indoor Thermal load, described heat exchange target component is that Indoor Thermal is handed over target temperature, and described actual measurement heat exchange parameter is refrigerating operaton indoor heat exchanger liquid pipe end temperature, describedly obtains the actual measurement heat exchange parameter corresponding with the heat exchange target component; Described heat exchange target component and the difference of actual measurement heat exchange parameter are applied to default FREQUENCY CONTROL function, and the frequency of controlling compressor comprises:

According to definite heat exchange target component, inquire about pre-stored Indoor Thermal load correction value and the corresponding relation of heat exchange target component, obtain Indoor Thermal load correction value corresponding to definite heat exchange target component;

By the control constant set in advance and the Indoor Thermal load correction value addition of obtaining, obtain Indoor Thermal and hand over target temperature;

Calculate liquid pipe end temperature and hand over the poor of target temperature with the Indoor Thermal obtained, obtain the first difference; The liquid pipe end temperature and the Indoor Thermal that calculate in a collection period are handed over the poor of target temperature, obtain the second difference; Calculate the difference of long-pending and the second difference of the first difference of twice, then with a upper collection period in the addition of compressor cooling frequency, obtain the compressor cooling frequency.

Preferably, obtain the liquid pipe end temperature of the indoor heat exchanger in the refrigerating operaton indoor set according to the collection period set in advance, the formula of controlling the compressor cooling frequency is:

Fc(n)=Fc(n-1)+2{TrLave(n)-Teo(n)}-{TrLave(n-1)-Teo(n-1)}，

Wherein,

The compressor cooling frequency that Fc (n) is n collection period under cooling condition, n is natural number;

The compressor cooling frequency that Fc (n-1) is (n-1) individual collection period under cooling condition;

TrLave (n) is n collection period under cooling condition, the liquid pipe end temperature of the indoor heat exchanger in the refrigerating operaton indoor set; The temperature information that liquid pipe end temperature can gather in a collection period by liquid pipe end temperature sensor 84, average and obtain the temperature-averaging value, as liquid pipe end temperature.

TrLave (n-1) is (n-1) individual collection period under cooling condition, the liquid pipe end temperature of the indoor heat exchanger in the refrigerating operaton indoor set;

The Indoor Thermal that Teo (n) is n collection period under cooling condition is handed over target temperature;

The Indoor Thermal that Teo (n-1) is (n-1) individual collection period under cooling condition is handed over target temperature; Usually, Teo (n)=Teo (n-1) can be set.Teo (n), Teo (n-1) are referred to as Indoor Thermal and hand over target temperature Teo.

Under cooling condition, Indoor Thermal hands over the computing formula of target temperature Teo as follows:

Teo=Pso+Kt，

Wherein,

Pso is control constant, Pso=8.0 during refrigeration stable operation;

Kt is Indoor Thermal load correction value, relevant to return air temperature (inlet temperature of the indoor heat exchanger in the operation indoor set) and the indoor design temperature of operation indoor set.

At n collection period, the return air temperature of operation indoor set and the difference computing formula of indoor design temperature are:

△Tc(n)=T _i(n)-T _iset(n)

Wherein,

△ Tc (n) is n the return air temperature difference that collection period is interior under cooling condition;

T _iset(n) be n the indoor design temperature that collection period is interior under cooling condition;

T _i(n) be n the return air temperature that collection period is interior under cooling condition, move the inlet temperature of the indoor heat exchanger of indoor set, the temperature information that can gather in a collection period by return air temperature temperature sensor 82 obtains.

If:

△Tcmax=Max(△Tc(n))

Wherein,

△ Tcmax is n the return air temperature maximum difference that collection period is interior under cooling condition.

The corresponding relation of Indoor Thermal load correction value Kt and △ Tcmax is set as table 2.

Table 2 is the corresponding relation of Pyatyi Indoor Thermal load correction value Kt and △ Tcmax

Condition	Kt
		△Tcmax≥4	0
△Tcmax=3	1
		△Tcmax=2	2
△Tcmax=1	3
		△Tcmax≤0	5

In practical application, when indoor load is indoor refrigeration duty, described heat exchange target component is target exhaust pressure, and the refrigerant pressure maximum that described actual measurement heat exchange parameter is oil eliminator output is describedly obtained the actual measurement heat exchange parameter corresponding with the heat exchange target component; Described heat exchange target component and the difference of actual measurement heat exchange parameter are applied to default FREQUENCY CONTROL function, and the frequency of controlling compressor comprises:

According to definite heat exchange target component, inquire about the corresponding relation of pre-stored target exhaust pressure maximum and heat exchange target component, obtain target exhaust pressure maximum corresponding to definite heat exchange target component;

Obtain the refrigerant pressure minimum of a value that flows into gas-liquid separator in off-premises station, according to the refrigerant pressure minimum of a value of obtaining and the target exhaust pressure maximum obtained, calculate target exhaust pressure;

Obtain the refrigerant pressure maximum of oil eliminator output, read history parameters, the refrigerant pressure maximum, target exhaust pressure and the compressor that obtain in a collection period heat frequency, according to the refrigerant pressure maximum of obtaining from oil eliminator, the target exhaust pressure of calculating and the information read from history parameters, obtain compressor and heat frequency.

With controlling, the compressor cooling frequency is similar, in the embodiment of the present invention, can obtain refrigerant pressure according to the collection period set in advance, and controls the formula that compressor heats frequency to be:

Fh(n)=Fh(n-1)+25{Pdo(n)-Pdmax(n)}-15{Pdo(n-1)-Pdmax(n-1)}

Wherein,

Fh (n) heats frequency for the compressor of n collection period under heating condition;

Fh (n-1) heats frequency for the compressor of (n-1) individual collection period under heating condition;

Pdo (n) is n the interior target exhaust pressure arranged of collection period under heating condition;

Pdo (n-1) is the target exhaust pressure arranged in (n-1) individual collection period under heating condition; Pdo (n) and Pdo (n-1) are referred to as target exhaust pressure (Pdo).

The refrigerant pressure maximum that Pdmax (n) is n the interior oil eliminator output of collection period under heating condition, in the embodiment of the present invention, can obtain refrigerant pressure maximum by 60 actual measurements of high-pressure sensor;

Pdmax (n-1) is the refrigerant pressure maximum that under heating condition, in (n-1) individual collection period, oil eliminator is exported.

Under heating condition, the computing formula of target exhaust pressure P do is as follows:

$\left\{\begin{array}{c}\mathrm{Pdo}=7.7\mathrm{Ps}\min +0.4\\ 2.2\mathrm{MPa}\≤\mathrm{Pdo}\≤\mathrm{Pdo}\max \end{array}\right.$

Wherein,

Psmin flows into the refrigerant pressure minimum of a value of gas-liquid separator under heating condition, can survey in collection period and obtain refrigerant pressure minimum of a value by low-pressure sensor 62;

Pdomax is target exhaust pressure maximum default under heating condition, and under heating condition, return air temperature and the indoor design temperature of operation indoor set are relevant.Wherein,

△Th(n)=T _is′ _et(n)-T _i′(n)

Wherein,

△ Th (n) is n the return air temperature difference that collection period is interior under heating condition;

T _is' _et(n) be n the indoor design temperature that collection period is interior under heating condition;

T _i' (n) be the return air temperature in n collection period under heating condition, move the inlet temperature of indoor set, the temperature information that can gather in a collection period by return air temperature temperature sensor 82 obtains.

If:

△Thmax=Max(△Th(n))

Wherein,

△ Thmax is n the return air temperature maximum difference that collection period is interior under heating condition.

The corresponding relation of default target exhaust pressure maximum Pdomax and return air temperature maximum difference △ Thmax is set as table 3.

The corresponding relation of table 3 Pyatyi Pdomax and △ Thmax

Condition	Pdomax
		△Thmax>4	2.85
△Thmax=4	2.70
		△Thmax=3	2.65
△Thmax=2	2.50
		△Thmax≤1	2.40

Certainly, in practical application, the corresponding relation of more multistage Pdomax and △ Thmax can also be set.

Whether the indoor set quantity about the monitoring operation changes, and whether Indoor Thermal load or indoor refrigeration duty change, and are known technology, at this, omit detailed description.

In the embodiment of the present invention, under cooling condition, frequency control apparatus comprises: monitoring modular, the first acquisition module and refrigeration frequency control module (not shown), wherein,

Whether monitoring modular, change for the indoor set quantity of moving in monitoring variable-frequency multi-connection type heat pump under cooling condition, and if so, notice refrigeration frequency control module is controlled compressor frequency according to the indoor set capacity; If indoor set quantity does not change, generate the second refrigeration trigger message;

The first acquisition module, for the second refrigeration trigger message according to from monitoring modular, whether monitoring Indoor Thermal load changes, after monitoring Indoor Thermal load and changing, obtain the inlet temperature of the indoor heat exchanger in the indoor set of operation and the liquid pipe end temperature of indoor heat exchanger; Determine the heat exchange target component according to the difference of described actual measurement return air temperature and indoor design temperature; Obtain the actual measurement heat exchange parameter corresponding with the heat exchange target component;

The refrigeration frequency control module, be used for basis from inlet temperature, the liquid pipe end temperature of the first acquisition module and the refrigeration FREQUENCY CONTROL function set in advance, control the compressor cooling frequency, according to described heat exchange target component and the difference of actual measurement heat exchange parameter and default FREQUENCY CONTROL function, control the compressor cooling frequency.

In the embodiment of the present invention, after refrigeration frequency control module reception notification, according to the indoor set capacity, compressor frequency is controlled, its formula is:

$\mathrm{Fc}=f_1(\underset{i=1}{\overset{N}{\mathrm{\Σ}}}\mathrm{HP}\_\mathrm{Con}\left(i\right)),$

Wherein,

The indoor set horsepower number (capacity) that HP_Con (i) is i platform cooling operation;

Fc is the compressor cooling frequency, i.e. the running frequency of compressor under cooling condition;

The indoor set quantity that N is cooling operation;

F ₁() is indoor set capacity-compressor cooling FREQUENCY CONTROL function.

Preferably, the refrigeration frequency control module comprises: the poor acquiring unit of return air temperature, Indoor Thermal load amending unit, Indoor Thermal are handed over target temperature computing unit, history parameters memory cell and compressor cooling frequency computation part unit, wherein,

The poor acquiring unit of return air temperature, for the indoor design temperature according in the inlet temperature of the indoor heat exchanger collected in n collection period and n collection period setting in advance, calculate both differences, obtain the maximum of both differences in n collection period, export Indoor Thermal load amending unit to;

Indoor Thermal load amending unit, for the maximum of the difference according to receiving, inquire about pre-stored Indoor Thermal load correction value and the peaked corresponding relation of difference, obtains the Indoor Thermal load correction value corresponding to maximum of the difference of reception;

Indoor Thermal is handed over the target temperature computing unit, the Indoor Thermal load correction value addition for the control constant by setting in advance with the amending unit of loading from Indoor Thermal, and the Indoor Thermal obtained in n collection period is handed over target temperature;

Compressor cooling frequency computation part unit, hand over the poor of target temperature for calculating from the liquid pipe end temperature in n collection period of the first acquisition module with hand over the Indoor Thermal of target temperature computing unit from Indoor Thermal, obtains the first difference; Read the history parameters memory cell, the compressor cooling frequency, liquid pipe end temperature and the Indoor Thermal that obtain in n-1 collection period are handed over target temperature, calculate the liquid pipe end temperature and the Indoor Thermal that read and hand over the poor of target temperature, obtain the second difference; Calculate the difference of long-pending and the second difference of the first difference of twice, then with n-1 collection period in the addition of compressor cooling frequency, obtain the interior compressor cooling frequency of n collection period;

After obtaining n the compressor cooling frequency in collection period, the compressor cooling frequency of handing over target temperature and calculating according to the liquid pipe end temperature in n the collection period received, Indoor Thermal, upgrade the corresponding information of storing in the history parameters memory cell.

Under heating condition, frequency control apparatus comprises: monitoring modular, the first acquisition module, the second acquisition module, first heat frequency control module and second and heat frequency control module, wherein,

Whether monitoring modular, change for indoor set quantity in the variable-frequency multi-connection type heat pump of monitoring heating operation, if so, heats frequency control module output first to first and heat trigger message; If indoor set quantity does not change, to the second acquisition module output second, heat trigger message;

The second acquisition module, for according to from second of monitoring modular, heating trigger message, monitor indoor refrigeration duty and whether change, after monitoring indoor refrigeration duty and changing, obtain the refrigerant pressure of oil eliminator output, export second to and heat frequency control module;

First heats frequency control module, for according to from first of monitoring modular, heating trigger message, obtains the indoor set capacity that heats running, according to the indoor set volume controlled compressor that heats running obtained, heats frequency;

Second heats frequency control module, for the target exhaust pressure according to setting in advance and the refrigerant pressure of reception, controls compressor and heats frequency.

In the embodiment of the present invention, frequency control apparatus heats frequency formula according to the pressure at expulsion of obtaining, pressure of inspiration(Pi) and indoor set inlet temperature control compressor and is:

Fh=f ₂(Pdo-Pd)，

$\left\{\begin{array}{c}\mathrm{Pdo}=f_3\left(\mathrm{Ps}\right)\\ 2.2\mathrm{MPa}\≤\mathrm{Pdo}\≤\mathrm{Pdo}\max \end{array}\right.,$

Wherein,

Fh is that compressor heats frequency, and the compressor under heating condition heats frequency;

Pdo is target exhaust pressure;

Pd is the actual measurement pressure at expulsion;

Ps is the actual measurement pressure of inspiration(Pi);

F ₂(), f ₃() is corresponding control function;

Pdomax is target exhaust pressure maximum.

Wherein,

△Th=T _iset-T _i

T _isetfor indoor design temperature;

T _ifor the indoor set inlet temperature;

$\mathrm{Pdo}\max =\left\{\begin{array}{c}2.90;\mathrm{\&Delta;Th}>3\\ 2.65;1<\mathrm{\&Delta;Th}\&le;3\\ 2.40;\mathrm{\&Delta;Th}\&le;1\end{array}\right.$

Preferably, second heats frequency control module, comprising: the poor acquiring unit of return air temperature, target exhaust pressure correction unit, target exhaust calculation of pressure unit, history parameters memory cell and compressor heat the frequency computation part unit, wherein,

The poor acquiring unit of return air temperature, for the return air temperature collected in the indoor design temperature interior according to n collection period setting in advance and n collection period, calculate both differences, obtain the maximum of both differences in n collection period, export target exhaust pressure correction unit to;

Target exhaust pressure correction unit, maximum for the difference according to receiving, inquire about the peaked corresponding relation of indoor refrigeration duty correction value and difference, obtain the target exhaust pressure maximum corresponding to maximum of the difference of reception, export target exhaust calculation of pressure unit to;

Target exhaust calculation of pressure unit, for obtaining the refrigerant pressure minimum of a value that flows into gas-liquid separator under heating condition, target exhaust pressure maximum according to the refrigerant pressure minimum of a value of obtaining and reception, calculate n the target exhaust pressure that collection period is interior under heating condition, export compressor to and heat the frequency computation part unit;

Compressor heats the frequency computation part unit, for obtaining the refrigerant pressure maximum of oil eliminator output in n collection period; Read the history parameters memory cell, the refrigerant pressure maximum, the target exhaust pressure in a n-1 collection period and n-1 the interior compressor of collection period that obtain in n-1 collection period heat frequency, according to the target exhaust pressure of the refrigerant pressure maximum of obtaining, reception and the information read from the history parameters memory cell, the compressor obtained in n collection period heats frequency;

After obtaining n the compressor in collection period and heating frequency, heat frequency, the corresponding information of storing in renewal history parameters memory cell according to the refrigerant pressure maximum in the target exhaust pressure in n the collection period received, n collection period obtaining and the compressor calculated.

Preferably, on the pipeline between off-premises station and indoor set, also be provided with the first branch pipe 05a and the second branch pipe 05b, the other end of liquid side stop valve 12 is connected with the input of the second branch pipe 05b, and the output of the second branch pipe 05b is connected with an end of indoor electric expansion valve 14;

The input of the first branch pipe 05a is connected with the other end of gas side stop valve 11, and output is connected with the other end of indoor heat exchanger 15.

For the load self-adapting variable-frequency multi-connection type heat pump that comprises an off-premises station and a plurality of indoor sets, correspondingly, the first branch pipe 05a and the second branch pipe 05b, towards a side of indoor set, have a plurality of ports.For example, for the load self-adapting variable-frequency multi-connection type heat pump that comprises an off-premises station, the first indoor set and the second indoor set, the input of the first branch pipe 05a is connected with the other end of gas side stop valve 11, the first output is connected with the other end of indoor heat exchanger 15 in the first indoor set, and the second output is connected with the other end of indoor heat exchanger 15 in the second indoor set;

The input of the second branch pipe 05b is connected with the other end of liquid side stop valve 12, and the first output is connected with an end of indoor electric expansion valve 14 in the first indoor set, and the second output is connected with an end of indoor electric expansion valve 14 in the second indoor set.

Below the workflow of the load self-adapting variable-frequency multi-connection type heat pump of the embodiment of the present invention is described.

The refrigerant vapour of HTHP is flowed out by the exhaust outlet of compressor 1, the check valve 2 of flowing through, flow into oil eliminator 3 from the input of oil eliminator 3, after oil eliminator 3 separating treatment, the lubricating oil carried in the refrigerant vapour of HTHP is deposited on oil eliminator 3 bottoms, when oil return solenoid valve 9 is opened, be deposited on the lubricating oil of oil eliminator 3 bottoms by the second output outflow of oil eliminator 3, the oil return solenoid valve 9 of flowing through, and, after the reducing pressure by regulating flow of oil return capillary 8, flow into gas-liquid separator 10 and finally by the air entry of compressor 1, flow back into compressor 1;

High-temperature high-pressure refrigerant steam after oil eliminator 3 separating treatment flows into the first end (A end) of four-way change-over valve 4 by the first output of oil eliminator 3:

When load self-adapting variable-frequency multi-connection type heat pump in summer during cooling condition, the first end of four-way change-over valve 4 is communicated with the second end (A end and B end), and the 3rd end is communicated with outside electric expansion valve 7 standard-sized sheets, 14 throttlings of indoor electric expansion valve with the 4th end (C end and D end).The refrigerant vapour of HTHP enters outdoor heat exchanger 5 by the B end of four-way change-over valve 4, rotation due to outside fan 6, make the outdoor air outdoor heat exchanger 5 of flowing through, thereby realize the heat exchange of refrigerant vapour and the outdoor heat exchanger 5 of HTHP, after the refrigerant vapour of HTHP enters outdoor air by heat, be condensed into the liquid refrigerant of high pressure, from the liquid pipe end of outdoor heat exchanger 5, flow out, the outside electric expansion valve 7 of flowing through successively, liquid side stop valve 12 and the second branch pipe 05b enter indoor set 02, the liquid refrigerant of high pressure is through indoor electric expansion valve 14 reducing pressure by regulating flows, become the gas-liquid two-phase cold-producing medium of low-temp low-pressure, the indoor heat exchanger 15 of flowing through, the rotation of indoor fan 13 makes indoor return through indoor heat exchanger 15, to room air, carry out cooling, thereby realize the heat exchange of gas-liquid two-phase cold-producing medium and the indoor heat exchanger 15 of low-temp low-pressure, after the gas-liquid two-phase cold-producing medium of low-temp low-pressure absorbs the room air heat, become low-pressure gaseous refrigerant, from the other end of indoor heat exchanger 15, flow out, the first branch pipe 05a more successively flows through, gas side stop valve 11, the D end of four-way change-over valve 4 and C end, enter gas-liquid separator 10, with the lubricating oil that flows into gas-liquid separator 10 after oil return capillary 8 reducing pressure by regulating flows, mix, after the gas-liquid separation of gas-liquid separator 10, low-pressure gaseous refrigerant flows back into compressor 1 by the air entry of compressor 1.

So far, complete circulating of cold-producing medium under cooling condition.

Under cooling condition, when the indoor set quantity of refrigerating operaton changes, compressor frequency Fc controls same as the prior art, adopts equally the indoor set capacity HP_Con (i) of cooling operation to control compressor cooling frequency Fc.Control strategy is HP_Con (i) while reducing, and Fc reduces.

Only, when changing appears in the Indoor Thermal load, compressor frequency Fc hands over the difference of target temperature Teo (n) to determine by TrLave (n) with Indoor Thermal, the function that Fc is (TrLave (n)-Teo (n)):

Fc(n)=Fc(n-1)+2{TrLave(n)-Teo(n)}-{TrLave(n-1)-Teo(n-1)}，

Wherein,

The compressor cooling frequency that Fc (n) is n data collection period;

The liquid pipe end temperature sensor observed temperature mean value that TrLave (n) is the refrigerating operaton indoor set;

The Indoor Thermal that Teo (n) is n data collection period is handed over target temperature, by following formula, is determined:

Teo=Pso+Kt，

Wherein, Pso is control constant, Pso=8.0 during refrigeration stable operation;

Kt is Indoor Thermal load correction value, is divided into the Pyatyi correction according to the variation of △ Tcmax, in Table 2.

The maximum that △ Tcmax is △ Tc;

△Tc=T _i-T _iset

Wherein,

T _ireturn air temperature for the return air temperature sensor actual measurement of operation indoor set;

T _isetfor indoor design temperature.

Like this, under cooling condition, when Indoor Thermal load reduces, i.e. T _ireduce, △ Tc reduces, according to table 2, thermic load correction value Kt increases, thereby the Indoor Thermal that makes n data collection period hands over target temperature Teo (n) to increase, and then make the difference of TrLave (n)-Teo (n) reduce, and cause compressor frequency Fc to reduce, realize load self-adapting.

In practical application, when components of system as directed load or Indoor Thermal load when very little, will occur that compressor is for a long time in the situation of low-frequency operation, and then cause the cold-producing medium flow velocity in load self-adapting variable-frequency multi-connection type heat pump pipeline lower, make the oil return characteristic poor.If long time running, may cause low on fuel in compressor, in the embodiment of the present invention, under cooling condition, further compressor frequency is carried out judging:

Judge compressor frequency whether under lower than the compressor frequency threshold value continuous operation surpass the time threshold set in advance, if, according to the strategy set in advance, compressor frequency is promoted to the compressor frequency threshold value, after the second time threshold that continuous service sets in advance, then compressor frequency is reverted to the frequency before promoting.

In the embodiment of the present invention, for instance, if compressor frequency Fc<35Hz continuous operation surpasses 60min, Fc is promoted to 35Hz with the speed of 2.0Hz/s, continuous service 60s, then compressor frequency is returned to stable refrigeration control frequency, the frequency before promoting, thereby realize the compressor oil return control under cooling condition, ensure the oil return characteristic of load self-adapting variable-frequency multi-connection type heat pump low-frequency operation, make oil mass abundance in compressor.

From above-mentioned, the compressor frequency control method under embodiment of the present invention cooling condition, change owing to having increased thermic load in the compressor frequency control strategy Indoor Thermal load correction value (Kt) caused, and by indoor set observed temperature parameter (TrLave and T _i) pull-in frequency control.Thereby, when Indoor Thermal load reduction or the little load operation of system, compressor frequency can be regulated quickly and accurately, make compressor cooling frequency Fc reduce, thereby make compressor operating in, the low frequency section, realize the Indoor Thermal load self-adapting of variable-frequency multi-connection type heat pump, guarantee high energy efficiency and the low noise characteristic of compressor and system.

In the embodiment of the present invention, when load self-adapting variable-frequency multi-connection type heat pump during in winter heating's operating mode, the first end of four-way change-over valve 4 is communicated with the 4th end (A end and D end), and the second end is communicated with the 3rd end (B end and C end), the effect of step-down and throttling is played in outside electric expansion valve 7 and the equal throttling of indoor electric expansion valve 14 simultaneously.

The refrigerant vapour of HTHP is flowed into by the A end of four-way change-over valve 4, from the D end be communicated with, flow out, the gas side of flowing through successively stop valve 11 and the first branch pipe 05a, the other end by indoor heat exchanger 15 enters indoor heat exchanger 15, the refrigerant vapour of HTHP enters room air by heat, to be heated indoor, the inboard cold of the refrigerant vapour absorption chamber of HTHP, become the liquid refrigerant of HTHP, from an end of indoor heat exchanger 15, flow out, flow into indoor electric expansion valve 14, the second branch pipe 05b more successively flows through, liquid side stop valve 12 and outside electric expansion valve 7, after the reducing pressure by regulating flow of indoor electric expansion valve 14 and outside electric expansion valve 7, become the gas-liquid two-phase cold-producing medium of low-temp low-pressure, the heat of outdoor heat exchanger 5 with extraction chamber's outer air of flowing through again, become low-pressure gaseous refrigerant, low-pressure gaseous refrigerant flow through successively again the second end of four-way change-over valve 4 and the 3rd end (B end and C end) and gas-liquid separator 10, after the gas-liquid separation of gas-liquid separator 10, low-pressure gaseous refrigerant flows back into compressor 1 by the air entry of compressor 1.

So far, complete circulating of cold-producing medium under heating condition.

Under heating condition, when the indoor set quantity of heating operation changes, it is same as the prior art that compressor heats frequency Fh control, and the indoor set capacity HP_Hon (i) that same employing heats running controls compressor and heats frequency Fh.Control strategy is HP_Hon (i) while reducing, and Fh reduces.

Only when changing appears in indoor refrigeration duty, than prior art, the present invention is based on Pyatyi target exhaust pressure maximum Pdomax technology and control compressor and heat frequency Fh:

Fh(n)=Fh(n-1)+25{Pdo(n)-Pdmax(n)}-15{Pdo(n-1)-Pdmax(n-1)}

Wherein,

The compressor frequency that Fh (n) is n data collection period;

Pdmax is high-pressure sensor observed pressure maximum;

Pdo is target exhaust pressure, by following formula, is determined:

Pdo=7.7Psmin+0.4,(2.2MPa≤Pdo≤Pdomax)

Wherein,

Psmin is low-pressure sensor observed pressure minimum of a value;

Pdomax is target exhaust pressure maximum, and the variation of Gen Ju ⊿ Thmax is divided into the Pyatyi value, in Table 3.

The maximum of ⊿ Thmax Wei ⊿ Th, and:

△Th(n)=T _is′ _et-T _i′

Wherein,

T _i' be the return air temperature of the return air temperature sensor actual measurement of operation indoor set;

T _is' _etfor indoor design temperature.

Like this, under heating condition, when indoor refrigeration duty reduces, T _i' increasing ， Ze ⊿ Th to reduce, the target exhaust pressure maximum Pdomax corresponding according to table 3 ， ⊿ Th reduces, and during stable operation, makes Pdo reduce, and finally causes compressor frequency Fh to reduce.

In practical application, when components of system as directed load or indoor refrigeration duty when very little, there will be the long-term low-frequency operation of compressor frequency, and then cause the cold-producing medium flow velocity in system pipeline lower, the system oil return characteristic is poor, and long time running may cause low on fuel in compressor, in the embodiment of the present invention, under heating condition, further compressor frequency is carried out judging:

Judge compressor frequency whether under lower than the compressor frequency threshold value continuous operation surpass the time threshold set in advance, if, according to the strategy set in advance, compressor frequency is promoted to the compressor frequency threshold value, the 3rd time threshold that continuous service sets in advance, then compressor frequency is reverted to the frequency before promoting.

In the embodiment of the present invention, for instance, under heating condition, if Fh<35Hz continuous operation surpasses 60min, Fh is promoted to 35Hz with the speed of 2.0Hz/s, continuous service 120s, again compressor frequency is returned to the stable controlled frequency that heats, the frequency before promoting, thus realize the compressor oil return control under heating condition, ensure the oil return characteristic of load self-adapting variable-frequency multi-connection type heat pump low-frequency operation, make oil mass abundance in compressor.

From above-mentioned, compressor frequency control method under embodiment of the present invention heating condition, change owing to having increased refrigeration duty in the compressor frequency control strategy Correction and Control (⊿ Th caused), target exhaust pressure maximum Pdomax is subdivided into to the Pyatyi value, and by indoor set observed temperature parameter (Pd, Ps and T _i') pull-in frequency control.Therefore, when indoor refrigeration duty reduction or the little load operation of system, compressor frequency can be regulated quickly and accurately, make Fh reduce, thereby make compressor operating in, the low frequency section, realize the indoor refrigeration duty self adaptation of heat pump, guarantee high energy efficiency and the low noise characteristic of compressor and system.

In the embodiment of the present invention, under refrigeration and heating condition, increased the Correction and Control that hot and cold load variations causes in the compressor frequency control strategy, and indoor set observed temperature parameter pull-in frequency has been controlled.When reduction or little load operation appear in indoor hot and cold load, compressor frequency can be regulated fast and accurately, guarantee that compressor frequency Fc and Fh regulate fast and accurately, make compressor operating in, the low frequency section, realize the indoor load self adaptation of heat pump, guarantee high energy efficiency and the low noise characteristic of compressor and system.

In the embodiment of the present invention, comprise that the method flow of the control compressor frequency that freezes and heat comprises:

The indoor set quantity that monitors operation does not change and the indoor set inlet temperature that means indoor load while changing, and obtains the actual measurement return air temperature of the indoor set of operation;

Determine the heat exchange target component according to the difference of described indoor design temperature and actual measurement return air temperature;

Obtain the actual measurement heat exchange parameter corresponding with the heat exchange target component;

Described heat exchange target component and the difference of actual measurement heat exchange parameter are applied to default FREQUENCY CONTROL function, control the frequency of compressor.

In the embodiment of the present invention, if under cooling condition, described indoor load is the Indoor Thermal load, described heat exchange target component is that Indoor Thermal is handed over target temperature, described actual measurement heat exchange parameter is refrigerating operaton indoor heat exchanger liquid pipe end temperature, describedly obtain the actual measurement heat exchange parameter corresponding with the heat exchange target component, and the difference of described heat exchange target component and actual measurement heat exchange parameter is applied to default FREQUENCY CONTROL function controls the frequency of compressor and comprise:

According to definite heat exchange target component, inquire about pre-stored Indoor Thermal load correction value and the corresponding relation of heat exchange target component, obtain Indoor Thermal load correction value corresponding to definite heat exchange target component;

By the control constant set in advance and the Indoor Thermal load correction value addition of obtaining, obtain Indoor Thermal and hand over target temperature;

Calculate liquid pipe end temperature and hand over the poor of target temperature with the Indoor Thermal obtained, obtain the first difference; The liquid pipe end temperature and the Indoor Thermal that calculate in a collection period are handed over the poor of target temperature, obtain the second difference; Calculate the difference of long-pending and the second difference of the first difference of twice, then with a upper collection period in the addition of compressor cooling frequency, obtain the compressor cooling frequency.

If under heating condition, described indoor load is indoor refrigeration duty, described heat exchange target component is target exhaust pressure, and the refrigerant pressure maximum that described actual measurement heat exchange parameter is oil eliminator output is describedly obtained the actual measurement heat exchange parameter corresponding with the heat exchange target component; And described heat exchange target component and the difference of actual measurement heat exchange parameter are applied to default FREQUENCY CONTROL function, the frequency of controlling compressor comprises:

According to definite heat exchange target component, inquire about the corresponding relation of pre-stored target exhaust pressure maximum and heat exchange target component, obtain target exhaust pressure maximum corresponding to definite heat exchange target component;

Obtain the refrigerant pressure minimum of a value that flows into gas-liquid separator in off-premises station, according to the refrigerant pressure minimum of a value of obtaining and the target exhaust pressure maximum obtained, calculate target exhaust pressure;

Obtain the refrigerant pressure maximum of oil eliminator output, read history parameters, the refrigerant pressure maximum, target exhaust pressure and the compressor that obtain in a collection period heat frequency, according to the refrigerant pressure maximum of obtaining from oil eliminator, the target exhaust pressure of calculating and the information read from history parameters, obtain compressor and heat frequency.

The control compressor cooling frequency of below take is example, and flow process is described in detail.

Fig. 3 is the method flow schematic diagram that the embodiment of the present invention is controlled compressor frequency.Referring to Fig. 3, the method comprises:

Step 31, obtain the indoor set quantity of moving under cooling condition, if the indoor set quantity of operation changes, performs step 32, if the indoor set quantity of operation does not change, performs step 33;

Step 32, trigger and according to the indoor set capacity, compressor frequency controlled;

Step 33, whether monitoring Indoor Thermal load changes, when definite Indoor Thermal load changes, obtain the inlet temperature of indoor heat exchanger of indoor set of operation and the liquid pipe end temperature of indoor heat exchanger, according to the inlet temperature of obtaining, liquid pipe end temperature and the refrigeration FREQUENCY CONTROL function that sets in advance, control the compressor cooling frequency.

In this step, according to the inlet temperature of obtaining, liquid pipe end temperature and the refrigeration FREQUENCY CONTROL function that sets in advance, the computing formula of controlling the compressor cooling frequency is:

Fc(n)=Fc(n-1)+2{TrLave(n)-Teo(n)}-{TrLave(n-1)-Teo(n-1)}，

Wherein,

The compressor cooling frequency that Fc (n) is n collection period under cooling condition, n is natural number;

The compressor cooling frequency that Fc (n-1) is (n-1) individual collection period under cooling condition;

TrLave (n) is n collection period under cooling condition, refrigerating operaton indoor heat exchanger liquid pipe end temperature;

TrLave (n-1) is (n-1) individual collection period under cooling condition, refrigerating operaton indoor heat exchanger liquid pipe end temperature;

The Indoor Thermal that Teo (n) is n collection period under cooling condition is handed over target temperature;

The Indoor Thermal that Teo (n-1) is (n-1) individual collection period under cooling condition is handed over target temperature.

Wherein, Indoor Thermal hands over the computing formula of target temperature to be:

Teo(n)=Pso(n)+Kt，

Wherein,

The control constant that Pso (n) is n collection period under cooling condition;

Kt is Indoor Thermal load correction value, relevant to return air temperature and the indoor design temperature of operation indoor set.

Indoor Thermal load correction value is with the return air temperature that moves indoor set and indoor design temperature is relevant specifically comprises:

If the return air temperature of operation indoor set and the return air temperature maximum difference of indoor design temperature are more than or equal to 4, described Indoor Thermal load correction value is 0;

If the return air temperature of operation indoor set and the return air temperature maximum difference of indoor design temperature equal 3, described Indoor Thermal load correction value is 1;

If the return air temperature of operation indoor set and the return air temperature maximum difference of indoor design temperature equal 2, described Indoor Thermal load correction value is 2;

If the return air temperature of operation indoor set and the return air temperature maximum difference of indoor design temperature equal 1, described Indoor Thermal load correction value is 3;

If the return air temperature of operation indoor set and the return air temperature maximum difference of indoor design temperature are less than or equal to 0, described Indoor Thermal load correction value is 5.

In practical application, the method can further include:

The indoor set quantity of monitoring operation under heating condition, if the indoor set quantity of operation changes, when monitoring indoor refrigeration duty and change, obtain the refrigerant pressure of oil eliminator output in off-premises station, according to the target exhaust pressure set in advance and the refrigerant pressure that obtains, control compressor and heat frequency.

In this step, the correlation formula that the control compressor heats frequency is:

Fh(n)=Fh(n-1)+25{Pdo(n)-Pdmax(n)}-15{Pdo(n-1)-Pdmax(n-1)}

$\left\{\begin{array}{c}\mathrm{Pdo}=7.7\mathrm{Ps}\min +0.4\\ 2.2\mathrm{MPa}\&le;\mathrm{Pdo}\&le;\mathrm{Pdo}\max \end{array}\right.$

△Th(n)=T _is′ _et(n)-T _i′(n)

△Thmax=Max(△Th(n))。

The corresponding relation of target exhaust pressure maximum Pdomax and return air temperature maximum difference △ Thmax specifically comprises:

If return air temperature maximum difference △ Thmax is greater than 4, described target exhaust pressure maximum Pdomax is 2.85;

If return air temperature maximum difference △ Thmax equals 4, described target exhaust pressure maximum Pdomax is 2.70;

If return air temperature maximum difference △ Thmax equals 3, described target exhaust pressure maximum Pdomax is 2.65;

If return air temperature maximum difference △ Thmax equals 2, described target exhaust pressure maximum Pdomax is 2.50;

If return air temperature maximum difference △ Thmax is less than or equal to 1, described target exhaust pressure maximum Pdomax is 2.40.

Preferably, in order to ensure the oil return characteristic of compressor when the low-frequency operation, described method further comprises:

Judge compressor frequency whether under lower than the compressor frequency threshold value continuous operation surpass the time threshold set in advance, if, according to the strategy set in advance, compressor frequency is promoted to the compressor frequency threshold value, after the second time threshold that continuous service sets in advance, then compressor frequency is reverted to the frequency before promoting.

Obviously, those skilled in the art can carry out various changes and modification and not break away from the spirit and scope of the present invention the present invention.Like this, if of the present invention these are revised and within modification belongs to the scope of the claims in the present invention and equivalent technologies thereof, the present invention also comprises these changes and modification interior.

Claims (10)

1. a load self-adapting variable-frequency multi-connection type heat pump, this system comprises: dispose the indoor set for the indoor heat exchanger of indoor heat exchange, dispose the off-premises station of compressor, for the frequency control apparatus that compressor frequency is controlled, the pipe arrangement that connects indoor set and off-premises station, it is characterized in that

When described frequency control apparatus also means for the indoor set quantity that monitors operation does not change that the indoor set inlet temperature of indoor load changes, obtain the actual measurement return air temperature of the indoor set of operation; Determine the heat exchange target component according to the difference of indoor design temperature and actual measurement return air temperature; Obtain the actual measurement heat exchange parameter corresponding with the heat exchange target component, and described heat exchange target component and the difference of actual measurement heat exchange parameter are applied to the frequency that default FREQUENCY CONTROL function is controlled compressor.

2. system according to claim 1, it is characterized in that, if under cooling condition, described indoor load is the Indoor Thermal load, described heat exchange target component is that Indoor Thermal is handed over target temperature, described actual measurement heat exchange parameter is refrigerating operaton indoor heat exchanger liquid pipe end temperature, describedly obtain the actual measurement heat exchange parameter corresponding with the heat exchange target component, and the difference of described heat exchange target component and actual measurement heat exchange parameter is applied to default FREQUENCY CONTROL function controls the frequency of compressor and comprise:

According to definite heat exchange target component, inquire about pre-stored Indoor Thermal load correction value and the corresponding relation of heat exchange target component, obtain Indoor Thermal load correction value corresponding to definite heat exchange target component;

By the control constant set in advance and the Indoor Thermal load correction value addition of obtaining, obtain Indoor Thermal and hand over target temperature;

Calculate liquid pipe end temperature and hand over the poor of target temperature with the Indoor Thermal obtained, obtain the first difference; The liquid pipe end temperature and the Indoor Thermal that calculate in a collection period are handed over the poor of target temperature, obtain the second difference; Calculate the difference of long-pending and the second difference of the first difference of twice, then with a upper collection period in the addition of compressor cooling frequency, obtain the compressor cooling frequency.

3. system according to claim 2, is characterized in that, described frequency control apparatus comprises: monitoring modular, the first acquisition module and refrigeration frequency control module, wherein,

Whether monitoring modular, change for the indoor set quantity of moving in monitoring variable-frequency multi-connection type heat pump under cooling condition, and if so, notice refrigeration frequency control module is controlled compressor frequency according to the indoor set capacity; If indoor set quantity does not change, generate the second refrigeration trigger message;

The first acquisition module, for the second refrigeration trigger message according to from monitoring modular, monitoring means whether the indoor set inlet temperature of indoor load changes, and after monitoring the Indoor Thermal load and changing, obtains the actual measurement return air temperature of the indoor set of operation; Determine the heat exchange target component according to the difference of described actual measurement return air temperature and indoor design temperature; Obtain the actual measurement heat exchange parameter corresponding with the heat exchange target component;

The refrigeration frequency control module, for according to described heat exchange target component and the difference of actual measurement heat exchange parameter and default FREQUENCY CONTROL function, control the compressor cooling frequency.

4. system according to claim 3, it is characterized in that, described refrigeration frequency control module comprises: the poor acquiring unit of return air temperature, Indoor Thermal load amending unit, Indoor Thermal are handed over target temperature computing unit, history parameters memory cell and compressor cooling frequency computation part unit, wherein

The poor acquiring unit of return air temperature, for the indoor design temperature according in the inlet temperature of the indoor heat exchanger collected in n collection period and n collection period setting in advance, calculate both differences, obtain the maximum of both differences in n collection period, export Indoor Thermal load amending unit to;

Indoor Thermal load amending unit, for the maximum of the difference according to receiving, inquire about pre-stored Indoor Thermal load correction value and the peaked corresponding relation of difference, obtains the Indoor Thermal load correction value corresponding to maximum of the difference of reception;

Indoor Thermal is handed over the target temperature computing unit, the Indoor Thermal load correction value addition for the control constant by setting in advance with the amending unit of loading from Indoor Thermal, and the Indoor Thermal obtained in n collection period is handed over target temperature;

Compressor cooling frequency computation part unit, hand over the poor of target temperature for calculating from the liquid pipe end temperature in n collection period of the first acquisition module with hand over the Indoor Thermal of target temperature computing unit from Indoor Thermal, obtains the first difference; Read the history parameters memory cell, the compressor cooling frequency, liquid pipe end temperature and the Indoor Thermal that obtain in n-1 collection period are handed over target temperature, calculate the liquid pipe end temperature and the Indoor Thermal that read and hand over the poor of target temperature, obtain the second difference; Calculate the difference of long-pending and the second difference of the first difference of twice, then with n-1 collection period in the addition of compressor cooling frequency, obtain the interior compressor cooling frequency of n collection period;

After obtaining n the compressor cooling frequency in collection period, the compressor cooling frequency of handing over target temperature and calculating according to the liquid pipe end temperature in n the collection period received, Indoor Thermal, upgrade the corresponding information of storing in the history parameters memory cell.

5. system according to claim 1 and 2, it is characterized in that, if under heating condition, described indoor load is indoor refrigeration duty, described heat exchange target component is target exhaust pressure, the refrigerant pressure maximum that described actual measurement heat exchange parameter is oil eliminator output, describedly obtain the actual measurement heat exchange parameter corresponding with the heat exchange target component; And described heat exchange target component and the difference of actual measurement heat exchange parameter are applied to default FREQUENCY CONTROL function, the frequency of controlling compressor comprises:

According to definite heat exchange target component, inquire about the corresponding relation of pre-stored target exhaust pressure maximum and heat exchange target component, obtain target exhaust pressure maximum corresponding to definite heat exchange target component;

Obtain the refrigerant pressure minimum of a value that flows into gas-liquid separator in off-premises station, according to the refrigerant pressure minimum of a value of obtaining and the target exhaust pressure maximum obtained, calculate target exhaust pressure;

Obtain the refrigerant pressure maximum of oil eliminator output, read history parameters, the refrigerant pressure maximum, target exhaust pressure and the compressor that obtain in a collection period heat frequency, according to the refrigerant pressure maximum of obtaining from oil eliminator, the target exhaust pressure of calculating and the information read from history parameters, obtain compressor and heat frequency.

6. system according to claim 5, is characterized in that, described frequency control apparatus comprises: monitoring modular, the first acquisition module, the second acquisition module, first heat frequency control module and second and heat frequency control module, wherein,

Whether monitoring modular, change for indoor set quantity in the variable-frequency multi-connection type heat pump of monitoring heating operation, if so, heats frequency control module output first to first and heat trigger message; If indoor set quantity does not change, to the second acquisition module output second, heat trigger message;

The second acquisition module, for according to from second of monitoring modular, heating trigger message, monitor indoor refrigeration duty and whether change, after monitoring indoor refrigeration duty and changing, obtain the refrigerant pressure of oil eliminator output, export second to and heat frequency control module;

First heats frequency control module, for according to from first of monitoring modular, heating trigger message, obtains the indoor set capacity that heats running, according to the indoor set volume controlled compressor that heats running obtained, heats frequency;

Second heats frequency control module, for the target exhaust pressure according to setting in advance and the refrigerant pressure of reception, controls compressor and heats frequency.

7. system according to claim 6, it is characterized in that, described second heats frequency control module comprises: the poor acquiring unit of return air temperature, target exhaust pressure correction unit, target exhaust calculation of pressure unit, history parameters memory cell and compressor heat the frequency computation part unit, wherein

The poor acquiring unit of return air temperature, for the return air temperature collected in the indoor design temperature interior according to n collection period setting in advance and n collection period, calculate both differences, obtain the maximum of both differences in n collection period, export target exhaust pressure correction unit to;

Target exhaust pressure correction unit, maximum for the difference according to receiving, the peaked corresponding relation of query aim pressure at expulsion maximum and difference, obtain the target exhaust pressure maximum corresponding to maximum of the difference of reception, exports target exhaust calculation of pressure unit to;

Target exhaust calculation of pressure unit, for obtaining the dirty refrigerant pressure minimum of a value that enters the off-premises station gas-liquid separator of heating condition, target exhaust pressure maximum according to the refrigerant pressure minimum of a value of obtaining and reception, calculate n the target exhaust pressure that collection period is interior under heating condition, export compressor to and heat the frequency computation part unit;

Compressor heats the frequency computation part unit, for obtaining the refrigerant pressure maximum of oil eliminator output in n collection period; Read the history parameters memory cell, the refrigerant pressure maximum, the target exhaust pressure in a n-1 collection period and n-1 the interior compressor of collection period that obtain in n-1 collection period heat frequency, according to the target exhaust pressure of the refrigerant pressure maximum of obtaining, reception and the information read from the history parameters memory cell, the compressor obtained in n collection period heats frequency;

After obtaining n the compressor in collection period and heating frequency, heat frequency, the corresponding information of storing in renewal history parameters memory cell according to the refrigerant pressure maximum in the target exhaust pressure in n the collection period received, n collection period obtaining and the compressor calculated.

8. system according to claim 5, it is characterized in that, described off-premises station further comprises: check valve, oil eliminator, four-way change-over valve, outdoor heat exchanger, outside fan, outside electric expansion valve, gas-liquid separator, gas side stop valve and liquid side stop valve, wherein

The exhaust outlet of compressor is connected with the input of check valve;

The output of check valve is connected with the input of oil eliminator;

The first output of oil eliminator is connected with the first end of four-way change-over valve;

The second end of four-way change-over valve is connected with an end of outdoor heat exchanger, and the 3rd end is connected with the input of gas-liquid separator, and the 4th end is connected with an end of gas side stop valve, and the other end of gas side stop valve is connected with an end of indoor set;

The other end of outdoor heat exchanger is connected with an end of outside electric expansion valve;

The outside fan is arranged on outdoor heat exchanger one side, for by air cooling way and outdoor heat exchanger, carrying out heat exchange;

The other end of outside electric expansion valve is connected with an end of liquid side stop valve, and the other end of liquid side stop valve is connected with the other end of indoor set;

The output of gas-liquid separator is connected with the air entry of compressor.

9. a method of controlling compressor frequency, the method comprises:

The indoor set quantity that monitors operation does not change and the indoor set inlet temperature that means indoor load while changing, and obtains the actual measurement return air temperature of the indoor set of operation;

Determine the heat exchange target component according to the difference of described indoor design temperature and actual measurement return air temperature;

Obtain the actual measurement heat exchange parameter corresponding with the heat exchange target component;

Described heat exchange target component and the difference of actual measurement heat exchange parameter are applied to default FREQUENCY CONTROL function, control the frequency of compressor.

10. method according to claim 9, wherein, if under cooling condition, described indoor load is the Indoor Thermal load, described default FREQUENCY CONTROL function is:

Fc(n)=Fc(n-1)+2{TrLave(n)-Teo(n)}-{TrLave(n-1)-Teo(n-1)}，

Wherein,

The compressor cooling frequency that Fc (n) is n collection period under cooling condition, n is natural number;

The compressor cooling frequency that Fc (n-1) is (n-1) individual collection period under cooling condition;

TrLave (n) is n collection period under cooling condition, refrigerating operaton indoor heat exchanger liquid pipe end temperature;

TrLave (n-1) is (n-1) individual collection period under cooling condition, refrigerating operaton indoor heat exchanger liquid pipe end temperature;

The Indoor Thermal that Teo (n) is n collection period under cooling condition is handed over target temperature;

The Indoor Thermal that Teo (n-1) is (n-1) individual collection period under cooling condition is handed over target temperature.

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