CN115307352A

CN115307352A - Double electronic expansion valve control method of air-supplementing enthalpy-increasing heat pump system

Info

Publication number: CN115307352A
Application number: CN202210979177.5A
Authority: CN
Inventors: 田龙飞; 赵军; 张少龙; 李波
Original assignee: Sichuan Changhong Air Conditioner Co Ltd
Current assignee: Sichuan Changhong Air Conditioner Co Ltd
Priority date: 2022-08-16
Filing date: 2022-08-16
Publication date: 2022-11-08

Abstract

The invention relates to the field of air-supplementing enthalpy-increasing control, in particular to a control method for double electronic expansion valves of an air-supplementing enthalpy-increasing heat pump system, which can improve the heat exchange efficiency of an evaporator while stabilizing the exhaust temperature, accurately control the air-supplementing quantity and solve the problem of large deviation of heat production in the repeated operation process. The control method of the double electronic expansion valves of the air-supplementing enthalpy-increasing heat pump system adopts a mode of combining air suction superheat degree control and exhaust superheat control to control, judges the priority of air suction superheat degree control and exhaust superheat control according to the heat exchange condition of an evaporator in the control process, gives full play to the evaporation efficiency of the evaporator, and improves the stability of the air-supplementing enthalpy-increasing heat pump system; by introducing the temperature control of the target inlet of the economic auxiliary road and combining the control of the air suction superheat degree and the exhaust superheat degree of the auxiliary road of the economizer, the control precision of the air supplement amount is improved while the air supplement amount is limited in a safety range, and meanwhile, the deviation of heat production in the repeated operation process is reduced. The invention is suitable for supplementing air and increasing enthalpy.

Description

Double electronic expansion valve control method of air-supplementing enthalpy-increasing heat pump system

Technical Field

The invention relates to the field of air-supply enthalpy-increasing control, in particular to a control method of a double electronic expansion valve of an air-supply enthalpy-increasing heat pump system.

Background

In recent years, the air-supplementing enthalpy-increasing heat pump system is widely applied to the field of low-temperature heating, and compared with the traditional heat pump system, the air-supplementing enthalpy-increasing heat pump system has the advantages of less heating capacity attenuation in low-temperature operation, stable unit operation and the like. The air-supplementing enthalpy-increasing heat pump system is provided with two refrigeration circulation loops, wherein an evaporator, a low-pressure cavity and a high-pressure cavity of a compressor, a condenser, a main loop of an economizer and a main electronic expansion valve form the main circulation loop, and the condenser, an auxiliary loop of the economizer, an auxiliary electronic expansion valve, a middle-pressure cavity of the compressor and the high-pressure cavity form the auxiliary circulation loop. The control method of the vapor-supplementing enthalpy-increasing heat pump system mainly comprises the steps of controlling a main electronic expansion valve and an auxiliary electronic expansion valve, wherein the traditional vapor-supplementing enthalpy-increasing control mainly comprises the steps of controlling the suction superheat degree of a main loop and the suction superheat degree of an auxiliary loop or controlling a double-electronic expansion valve by controlling the exhaust superheat degree.

Disclosure of Invention

The invention aims to provide a control method of double electronic expansion valves of a gas-supplementing enthalpy-increasing heat pump system, which improves the heat exchange efficiency of an evaporator while stabilizing the exhaust temperature, accurately controls the gas supplementing quantity and solves the problem of large deviation of heat production in the repeated operation process.

The invention adopts the following technical scheme to realize the aim, and a control method of a double electronic expansion valve of a gas-supplementing enthalpy-increasing heat pump system comprises the following steps:

step 1, judging whether the compressor receives a starting instruction, if not, executing step 2, otherwise, executing step 3;

step 2, keeping the standby opening of the main electronic expansion valve, wherein the standby opening is a1, and a1 is more than 0; the auxiliary electronic expansion valve keeps a closed state, and the operation is finished;

3, resetting the closing valve of the main electronic expansion valve, judging whether the auxiliary electronic expansion valve needs to be opened or not, and if T1 is larger than d1, setting the opening of the auxiliary electronic expansion valve to be 0, and ending; if T1 is less than d2, executing step 4; if d2 is not less than T1 and not more than d1, the auxiliary electronic expansion valve keeps the state of the last period, T1 is the outdoor environment temperature, and d1 and d2 are set values of a user;

step 4, judging whether the operation of the compressor exceeds the set threshold time, if not, executing step 5, otherwise, executing step 6;

step 5, the main electronic expansion valve maintains the initial opening degree ZKD, ZKD = (a 2 x T1-a3 x T2+ a 4), the auxiliary electronic expansion valve maintains the initial opening degree FKD, and the process is finished, wherein FKD = (-1 x d3 x T1+ d4 x T2+ d 5), a2, a3 and a4 are all positive values, d3, d4 and d5 are all positive values, and T2 is the water outlet temperature;

step 6, judging whether the difference value of the actual air suction superheat degree of the evaporator and the target air suction superheat degree and the economizer auxiliary circuit are seriously overheated or not, and executing a step 7 if TH1 is more than TH + b1 or TH1 is less than TH-b2 or TS1 is more than e 1; otherwise, executing step 8; TH1 is the actual superheat degree of the evaporator, TH is the target suction superheat degree of the evaporator, b1, b2 and e1 are set values of a user, and TS1 is the actual inlet-outlet superheat degree of the economizer auxiliary circuit;

and 7, calculating the variation of the main electronic expansion valve by adopting suction superheat control, which specifically comprises the following steps: if TH1> TH + b1, the main electronic expansion valve variation ZKDB = b3 (TH 1-TH-b 1) + b4 (TH 1-TH 0); ZKDB = b3 (TH 1-TH + b 2) + b4 (TH 1-TH 0) if TH1< TH-b 2;

calculate the auxiliary electronic expansion valve variable quantity simultaneously, specifically include: the auxiliary electronic expansion valve variable quantity FKDB = e2 (TS 1-e 1) + e3 (TS 1-TS), b3, b4, e2 and e3 are user set values and are all larger than 0, TS is the actual superheat degree of the auxiliary circuit of the economizer in the previous period, and TH0 is the actual suction superheat degree of the previous period;

and 8, calculating the variable quantity of the main electronic expansion valve by adopting exhaust superheat control, and specifically comprising the following steps of: ZKDB = -1 × c2 (TP 1-TP) -c3 (TP 1-TP 0) if TP 1> TP + c1 or TP1< TP-c 1; ZKDB = -1 × c5 (TP 1-TP) -c6 (TP 1-TP 0) if TP 1> TP + c4 or TP1< TP-c 4; c1, c2, c3, c4, c5 and c6 are set values of a user, are all larger than 0, TP is a target exhaust superheat degree, TP1 is an actual exhaust superheat degree, and TP0 is an exhaust superheat degree of a previous period;

simultaneously judging the upper limit value of the auxiliary gas quantity of the economizer, if TP1 is less than d6, reducing the auxiliary gas quantity of the economizer, after reducing the auxiliary gas quantity of the economizer, if TP1 is less than d6, and TH1 is more than or equal to TH-b2, FKDB = e4 (TP 1-d 6), wherein e4 is a positive value, otherwise, judging the actual inlet temperature of the auxiliary gas of the economizer and the target inlet temperature of the auxiliary gas of the economizer, if-e 5 is less than or equal to TJ1-TJ is less than or equal to e5, FKDB =0, otherwise, FKDB = e9 (TJ-TJ 1) + e10 (TJ 0-TJ 1), wherein e9 and e10 are user set values, the values are positive values, TJ is the target inlet temperature of the auxiliary gas of the economizer, TJ1 is the actual inlet temperature of the auxiliary gas of the economizer, and TJ0 is the actual superheat degree of the auxiliary gas of the economizer in one cycle;

step 9, judging the calculated variation of the main electronic expansion valve and the calculated variation of the auxiliary electronic expansion valve, if the variation of the main electronic expansion valve is ZKDB & gt c7, making ZKDB = c7, if ZKDB & lt-c 7, making ZKDB = -c7, wherein c7 is a user set value and is a positive value;

let FKDB = e11 if FKDB ≧ e11, and FKDB = -e11 if FKDB ≦ -e11, e11 is user set value and is positive value.

Further, the control method further comprises the step 10 of: and calculating the opening degree of a main electronic expansion valve in the current period and the current opening degree of an auxiliary electronic expansion valve, wherein the opening degree of the main electronic expansion valve in the current period ZKD = ZKD1+ ZKDB, the opening degree of the auxiliary electronic expansion valve in the current period FKD = FKDB + FKD1, ZKD1 is the opening degree of the main electronic expansion valve in the previous period, and FKD1 is the opening degree of the electronic expansion valve in the previous period.

Further, in step 6, TH1= Tb-Ta, where Ta and Tb are actual inlet and outlet temperatures of the evaporator, and are respectively collected by temperature sensors at the inlet and outlet of the evaporator.

Further, in step 7, the calculation result of the variation of the main electronic expansion valve is rounded down, and the remainder is accumulated in the next control cycle.

Further, in step 7, the calculation result of the variation of the auxiliary electronic expansion valve is rounded down, and the remainder is accumulated to the next control period.

Further, in step 8, TP1= Tm-Tn, and Tm and Tn are the compressor discharge temperature and the condenser outlet temperature, respectively.

Further, in step 8, TJ = e6 × Tn + e7 × Ta + e8, e6, e7, and e8 are user setting values, and e6 and e7 are positive values.

The invention has the beneficial effects that:

meanwhile, the control is carried out in a mode of combining suction superheat control and exhaust superheat control, the priority of suction superheat control and exhaust superheat control is judged according to the heat exchange condition of the evaporator in the control process, the evaporation efficiency of the evaporator is fully exerted, and the stability of the air-supply enthalpy-increasing heat pump system is improved;

by introducing the target inlet temperature control of the economic auxiliary road, combining the inspiration superheat degree control and the exhaust superheat degree control of the economizer auxiliary road, the gas supplementing quantity is limited in a safety range, the gas supplementing quantity control precision is improved, the stability of the gas supplementing enthalpy increasing heat pump system is further improved, the heat production quantity deviation in the repeated operation process is reduced, and the unit consistency is improved.

Drawings

Fig. 1 is a structural diagram of a vapor-supplementing enthalpy-increasing heat pump system provided by an embodiment of the invention;

FIG. 2 is a flow chart of a method for controlling a main electronic expansion valve according to an embodiment of the present invention;

FIG. 3 is a flow chart of an auxiliary electronic expansion valve control method provided by an embodiment of the invention;

in the attached drawing, 1-an evaporator, 2-a gas-liquid separator, 3-an air-supplying enthalpy-increasing compressor, 4-a condenser, 5-an economizer, 6-a main electronic expansion valve, 7-an auxiliary electronic expansion valve, 8-an evaporator inlet temperature sensor, 9-an evaporator outlet temperature sensor, 10-an economizer inlet temperature sensor, 11-an economizer outlet temperature sensor, 12-an exhaust temperature, 13-a condenser outlet superheat degree, 14-a backwater temperature sensor and 15-a water outlet temperature sensor.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.

The invention discloses a double-electronic expansion valve control method of a gas-supplementing enthalpy-increasing heat pump system, which is used for controlling an electronic expansion valve in the gas-supplementing enthalpy-increasing heat pump system, and the gas-supplementing enthalpy-increasing heat pump system is shown in figure 1 and comprises an evaporator 1, a gas-liquid separator 2, a compressor 3, a condenser 4, an economizer 5, a main electronic expansion valve 6, an auxiliary electronic expansion valve 7, an evaporator inlet temperature sensor 8, an evaporator outlet temperature sensor 9, an economizer auxiliary circuit inlet temperature sensor 10, an economizer auxiliary circuit outlet temperature sensor 11, a compressor exhaust temperature sensor 12, a condenser outlet temperature sensor 13, a return water temperature sensor 14 and an outlet water temperature sensor 15. Wherein the outlet of the evaporator 1 is connected with the inlet of the gas-liquid separator 2, the outlet of the gas-liquid separator 2 is connected with the inlet of the low-pressure cavity of the compressor 3, the exhaust port of the compressor 3 is connected with the inlet of the condenser 4, the outlet of the condenser 4 is connected with the inlet of the main circuit of the economizer 5, the outlet of the main circuit of the economizer 5 is connected with the inlet of the main electronic expansion valve 6, the outlet of the main electronic expansion valve 6 is connected with the inlet of the evaporator 1, and the refrigerant flows according to the connection sequence of the above elements to form the main circulation process; the outlet of the auxiliary electronic expansion valve 7 is connected with the inlet of an auxiliary circuit of the economizer 5, the outlet of the auxiliary circuit of the economizer 5 is connected with the inlet of a middle pressure cavity of the compressor 3, the exhaust port of the compressor 3 is connected with the inlet of the condenser 4, the outlet of the condenser 4 is connected with the inlet of a main circuit of the economizer 5, the outlet of the main circuit of the economizer 5 is connected with the inlet of the auxiliary electronic expansion valve 7, and the refrigerant flows according to the connection sequence of the elements to form an auxiliary circulation process.

An evaporator inlet temperature sensor 8 and an evaporator outlet temperature sensor 9 are respectively arranged at the inlet and the outlet of the evaporator 1 and used for collecting the temperature of the inlet and the outlet of the evaporator. The economizer auxiliary road inlet temperature sensor 10 and the economizer auxiliary road outlet temperature sensor 11 are respectively arranged at an economizer auxiliary road inlet and outlet and are used for collecting the temperature of the economizer auxiliary road inlet and outlet; the compressor exhaust temperature sensor 12 and the condenser outlet temperature sensor 13 are respectively arranged at the compressor exhaust port and the condenser outlet and used for collecting the compressor exhaust temperature and the condenser outlet temperature; the backwater temperature sensor 14 and the water outlet temperature sensor 15 are respectively arranged at the water path inlet and the water path outlet of the condenser 4 and used for collecting the temperature of the inlet water and the outlet water of the condenser. Besides, an ambient temperature sensor is also arranged for acquiring the outdoor ambient temperature.

The invention calculates the variable quantity of the electronic expansion valve by judging and processing the difference values of the target exhaust superheat degree and the actual exhaust superheat degree of the compressor, the target inlet temperature of the economizer and the actual inlet temperature of the economizer, and the target suction superheat degree of the evaporator and the actual suction superheat degree of the evaporator, thereby controlling the action of the electronic expansion valve.

The invention relates to a double-electronic expansion valve control method of a gas-supplementing enthalpy-increasing heat pump system, which comprises the following steps:

step 2, keeping the standby opening of the main electronic expansion valve, wherein the standby opening is a1, and a1 is more than 0; the auxiliary electronic expansion valve keeps a closed state, and the process is finished;

step 6, judging whether the difference value of the actual air suction superheat degree of the evaporator and the target air suction superheat degree and the economizer auxiliary circuit are seriously overheated or not, and executing step 7 if TH1 is more than TH + b1 or TH1 is less than TH-b2 or TS1 is more than e 1; otherwise, executing step 8; TH1 is the actual superheat degree of the evaporator, TH is the target suction superheat degree of the evaporator, b1, b2 and e1 are set values of a user, and TS1 is the actual inlet and outlet superheat degree of the auxiliary passage of the economizer;

and 7, calculating the variable quantity of the main electronic expansion valve by adopting suction superheat control, and specifically comprising the following steps of: if TH1> TH + b1, the main electronic expansion valve variation ZKDB = b3 (TH 1-TH-b 1) + b4 (TH 1-TH 0); ZKDB = b3 (TH 1-TH + b 2) + b4 (TH 1-TH 0) if TH1< TH-b 2;

meanwhile, calculating the variable quantity of the auxiliary electronic expansion valve, specifically comprising: the variable quantity FKDB = e2 (TS 1-e 1) + e3 (TS 1-TS) of the auxiliary electronic expansion valve, b3, b4, e2 and e3 are set values of a user, are all larger than 0, TS is the actual superheat degree of the auxiliary economizer auxiliary circuit in the previous period, and TH0 is the actual suction superheat degree in the previous period;

and 8, calculating the variable quantity of the main electronic expansion valve by adopting exhaust superheat control, and specifically comprising the following steps of: ZKDB = -1 × c2 (TP 1-TP) -c3 (TP 1-TP 0) if TP 1> TP + c1 or TP1< TP-c 1; ZKDB = -1 × c5 (TP 1-TP) -c6 (TP 1-TP 0) if TP 1> TP + c4 or TP1< TP-c 4; c1, c2, c3, c4, c5 and c6 are set values by a user, are all larger than 0, TP is a target exhaust superheat degree, TP1 is an actual exhaust superheat degree, and TP0 is an exhaust superheat degree in the previous period;

if the FKDB is more than or equal to e11, letting the FKDB = e11, if the FKDB is less than or equal to-e 11, letting the FKDB = -e11, and making the e11 be a user set value and a positive value;

and 10, calculating the opening degree of a main electronic expansion valve and the current opening degree of an auxiliary electronic expansion valve in the current period, wherein the opening degree of the main electronic expansion valve in the current period ZKD = ZKD1+ ZKDB, the opening degree of the auxiliary electronic expansion valve in the current period FKD = FKDB + FKD1, ZKD1 is the opening degree of the main electronic expansion valve in the previous period, and FKD1 is the opening degree of the electronic expansion valve in the previous period.

In an embodiment of the present invention, a control method of a main electronic expansion valve is shown in fig. 2, and includes:

step S101 determines whether a power-on command is received, if not, step S102 is executed, otherwise, step S103 is executed.

Step S102, the main electronic expansion valve keeps a standby opening degree, the standby opening degree value is a1, the value a1 is a user set value, and the value range is 0-500 steps.

Step S103 is a step of resetting the main electronic expansion valve closing valve and the main electronic expansion closing standby opening a1+ 30.

Step S104 judges whether the compressor has run for more than S seconds, if not, step S105 is executed, otherwise, step S106 is executed, wherein S is a user set value, the value is more than or equal to 0 and is an integer.

Step S105 is to maintain the initial opening ZKD, ZKD = (a 2 x T1-a3 x T2+ a 4), where a2, a3, and a4 are user setting values, a2, a3, and a4 are positive values, T1 is the outdoor ambient temperature, T2 is the leaving water temperature, ZKD =500 when the calculated ZKD is greater than 500, and ZKD =50 when the calculated ZKD is less than 50.

And S106, judging the difference state of the actual suction superheat and the target suction superheat of the evaporator, if TH1 is more than TH + b1 or TH1 is less than TH-b2, executing S107 to adopt suction superheat control, and otherwise executing S108 to adopt exhaust superheat control. TH1 is the actual degree of superheat of the evaporator, TH1= Tb-Ta, and Ta, tb are the actual import and export temperature of the evaporator, and are respectively collected by the import and export temperature sensors of the evaporator. TH is the target suction superheat of the evaporator, and the value range is-10. b1, b2 are set by a user that the value ranges are 0-5, TH1, TH, b1, b2 are used for judging the heat exchange state of the evaporator, when TH1 is more than TH + b1 or TH1 is less than TH-b2, the superheat degree of the evaporator is not in the preset target suction superheat degree deviation range, when TH1 is more than TH + b1, the evaporator is seriously overheated, when TH1 is less than TH-b2, the evaporator is incomplete, liquid impact risks exist in a large amount of sucked liquid, the heat exchange efficiency of the evaporator is low in the two conditions, the heat exchange state of the evaporator is firstly improved, and the suction superheat degree is adopted to control and calculate the variable quantity of a main electronic expansion valve; when TH1< = TH + b1 and TH1> = TH-b2, indicate that the evaporimeter superheat degree has been in the predetermined target suction superheat degree deviation scope, the evaporimeter heat transfer state is good, can adopt the stable exhaust temperature control of exhaust superheat degree control.

Step S107, calculating the variation of the main electronic expansion valve by adopting suction superheat control, such as TH1> TH + b1, ZKDB = b3 (TH 1-TH-b 1) + b4 (TH 1-TH 0), rounding the calculation result downwards, and accumulating the remainder to the next control period; if TH1< TH-b2, ZKDB = b3 (TH 1-TH + b 2) + b4 (TH 1-TH 0), the calculation is rounded down and the remainder is accumulated for the next control cycle. ZKDB is the variation of the main electronic expansion valve, TH0 is the actual suction superheat degree of the previous period, b3 and b4 are user set values, and the value range is 0-10.

Step S108, calculating the variation of the main electronic expansion valve by adopting exhaust superheat control, if TP1 is more than TP + c1 or TP1 is less than TP-c1, ZKDB = -1 × c2 (TP 1-TP) -c3 (TP 1-TP 0), rounding the calculation result downwards, and accumulating the remainder to the next control period; for example, TP 1> TP + c4 or TP1< TP-c4, ZKDB = -1 x c5 (TP 1-TP) -c6 (TP 1-TP 0), the calculation result is rounded down, and the remainder is accumulated to the next control period. Wherein TP1= Tm-Tn, TP1 is the actual exhaust superheat, and Tm and Tn are the compressor exhaust temperature and the condenser outlet temperature, respectively. TP0 is the exhaust superheat degree of the previous period, TP is the target exhaust superheat degree which is a user set value and has a value range of 20-40. c1, c2, c3, c4, c5 and c6 are user set values, and the value range is 0-10.

Step S109 limits the variation of the main electronic expansion valve, for example, ZKDB = c7 when the calculated variation ZKDB > c7 of the main electronic expansion valve is calculated, or ZKDB = -c7 when the calculated variation ZKDB < -c7 of the main electronic expansion valve is calculated, where c7 is a user setting value, and the value range is 1 to 20.

Step S110 calculates the main electronic expansion valve opening in the current cycle, where the main electronic expansion valve opening in the current cycle ZKD = ZKD1+ ZKDB, and ZKD1 is the main electronic expansion valve opening in the previous cycle, and when calculated ZKD > =500, ZKD =500, and when calculated ZKD < =50, ZKD =50.

The following are examples of main electronic expansion valve control

1. Basic information of the system:

the method comprises the steps of 500 steps of the maximum opening of a main electronic expansion valve, 0-500 step of the adjusting range, 180 seconds of the starting operation of a unit, 230 steps of the upper cycle opening of the main electronic expansion valve, 17 ℃ below zero of the current inlet temperature of an evaporator, 15 ℃ below zero of the current outlet temperature of the evaporator, 16.5 ℃ below zero of the upper cycle inlet temperature of the evaporator, 15.5 ℃ below zero of the upper cycle outlet temperature of the evaporator, 78 ℃ below zero of the current exhaust temperature of a compressor, 41 ℃ below zero of the current outlet temperature of a condenser, 76.5 ℃ below zero of the upper cycle exhaust temperature of the compressor, 40.3 ℃ below zero of the upper cycle outlet temperature of the condenser, 12 ℃ below zero of the outdoor environment temperature, 39 ℃ of the outlet water temperature, and 30 seconds of the control cycle.

2. User setting parameter values

Serial number	Name (R)	Set value	Set range
				1	a1	500	0～500
2	a2	8.9	>0
				3	a3	3.5	>0
4	a4	423	>0
				5	s	60	>0 and is an integer
6	TH	0	-10～10
				7	b1	3	0～5
8	b2	2.5	0～5
				9	b3	0.7	0～10
10	b4	2.2	0～10
				11	c1	3	0～10
12	c2	2	0～10
				13	c3	1.5	0～10
14	c4	5	0 to 10, and c4>c1
				15	c5	0.9	0～10
16	c6	0.7	0～10
				17	c7	8	1～20
18	TP	30	20～40

3. Main valve opening calculation

Because the compressor is started and operated for 180 seconds and exceeds the set value S =60 seconds, the step S106 is directly executed;

since TH1= Tb-Ta = -15+17=2, TH =0, TH + b1= -0 +3, TH-b2=0-2.5= -2.5, th1> = TH-b2, and TH1= < TH + b1, step S108 is performed;

because TP1= Tm-Tn =78-41=37, TP + c4=30+5=35, ZKDB = -1 × c 5= -1 × 1 TP-TP) -c 6= -1 × 1 TP0 = -1 × 1.8 = -30) -0.7 = -6.86 (37- (76.5-40.3)) = -6.86, ZKDB = -6 after rounding;

ZKDB = = -6 because ZKDB > -c7 and ZKDB < c 7;

since ZKD1=230 steps, ZKD = ZKD1+ ZKDB =230-6=224 steps.

The main electronic expansion valve is adjusted, the auxiliary electronic expansion valve is adjusted together, and the auxiliary electronic expansion valve is mainly controlled in a mode of combining the inlet temperature of the auxiliary economizer target, the superheat degree of the auxiliary economizer and the exhaust superheat degree of the compressor.

As shown in fig. 3, a control method of an auxiliary electronic expansion valve according to an embodiment of the present invention includes:

step S201, determining whether the compressor receives the power-on command, if not, executing step S202, otherwise, executing step S203.

Step S202, the auxiliary electronic expansion valve keeps a closed state.

Step S203, judging whether the auxiliary electronic expansion valve needs to be opened, if T1 is larger than d1, executing step S204, if T1 is larger than d2, executing step S205 by the auxiliary electronic expansion valve, if d2 is larger than or equal to T1 and is smaller than or equal to d1, keeping the auxiliary electronic expansion valve in the state of the previous period, wherein d1 and d2 are user set values, the value range is-5-20, and d2 is required to be larger than d1.

Step S204, the auxiliary electronic expansion valve opening FKD =0.

And S205, judging whether the compressor runs for more than T seconds, if not, executing S206, otherwise, executing S207, wherein T is a user set value, and the value range of T is 0-10 and is an integer.

Step S206, the opening FKD =0 of the auxiliary electronic expansion valve.

Step S207, determining whether the compressor runs for more than G seconds, if not, executing step S208, otherwise, executing step S209, where G is a user set value, is an integer with a value range of 0 to 180, and needs to satisfy G > T.

Step S208, calculating initial opening FKD of auxiliary electronic expansion valve, FKD = (-1 × d3 × t1+ d4 × t2+ d 5), d3, d4, d5 are user setting values, which are positive values, FKD =500 when calculated FKD is greater than 500, and FKD =50 when calculated FKD < 50.

And S209, judging whether the economizer auxiliary road is seriously overheated or not, if TS1 is more than e1, executing S210, and if not, executing S211.TS1 is the superheat degree of an actual inlet and outlet of the auxiliary road of the economizer, TS1= Tf-Te, and Te and Tf are sampling temperatures of the inlet and outlet of the auxiliary road of the economizer. e1 is a user set value, and the value range is 4-8. TS1, te, tf and e1 are used for judging the heat exchange condition of the economizer auxiliary circuit, if TS1> e1 indicates that the economizer auxiliary circuit is in a severe overheating state at the moment, the circulation flow of the auxiliary circuit is too little at the moment, the heat exchange performance of the economizer is not fully exerted, and the phenomena of high exhaust temperature of a compressor, small supercooling degree of the economizer, low heat production quantity of a heat pump and the like are simultaneously accompanied, at the moment, the circulation flow of a refrigerant of the economizer auxiliary circuit is increased and the heat exchange state of the economizer is improved due to the execution of the step S208.

And step S210, the calculation result is rounded downwards, and the remainder is accumulated to the next control period, wherein TS is the actual superheat degree of the auxiliary circuit of the economizer in the previous period, and e2 and e3 are user set values, and the value range of the user set values is 0-10.

And step S211, determining an upper limit value of the auxiliary road gas supplement amount of the economizer, executing step S212 if TP1< d6 indicates that the auxiliary road gas supplement amount of the economizer possibly has excess, otherwise executing step S213, wherein d6 is a user set value and the value range is 10-20.

And step S212, reducing the economizer air supplement amount, if TP1 is less than d6 and TH1 is more than or equal to TH-b2, at the moment, when the main circulation loop does not carry a large amount of liquid but the exhaust temperature is too low, the auxiliary loop liquid supplement amount is too much at the moment, the risk of pressure cavity liquid compression in the compressor is easily caused, and the opening degree of an auxiliary electronic expansion valve of the economizer needs to be rapidly reduced, so that FKDB = e4 (TP 1-d 6), e4 is a user set value, and the value is a positive value.

Step S213, if TJ1 is more than or equal to-e 5 and TJ is more than or equal to e5, step S214 is executed, otherwise step S215 is executed, TJ1 is the actual inlet temperature of the economizer auxiliary, and the value of the actual inlet temperature is close to the middle pressure cavity air supplement pressure corresponding to the evaporation temperature of the economizer auxiliary. TJ is the target inlet temperature of the auxiliary circuit of the economizer and is used for accurately controlling the auxiliary circuit gas supplement amount, the higher the target inlet temperature of the auxiliary circuit of the economizer is, the more the liquid phase ratio in the refrigerant of the auxiliary circuit is, and the larger the gas supplement amount of the economizer is. The economizer auxiliary road target inlet temperature TJ = e6 + Tn + e7 + Ta + e8, where e6, e7, e8 are user set values, e6, e7 are positive values, e8 has no limit, and TJ = Tn when TJ > = Tn, and TJ = Ta when TJ < = Tn. e5 is a user set value, the value range is 0-3, and the upper deviation and the lower deviation of the air supplement amount are limited, so that the smaller the value is, the smaller the upper deviation and the lower deviation of the air supplement amount is.

Step S214, FKDB =0.

And S215, FKDB = e9 (TJ-TJ 1) + e10 (TJ 0-TJ 1), rounding down the calculation result, accumulating the remainder to the next control period, wherein TJ0 is the actual superheat degree of the auxiliary road of the economizer in the previous period, and e9 and e10 are user set values which are positive values.

Step S216, defining a maximum change amount of the auxiliary electronic expansion valve, wherein FKDB = e11 if the calculated change amount FKDB > = e11 of the auxiliary electronic expansion valve, and wherein FKDB = -e11 if the calculated change amount FKDB < = -e11 of the auxiliary electronic expansion valve. e11 is a user set value, and the value range is 1-20.

And step S217, calculating the current opening degree of the auxiliary electronic expansion valve, wherein FKD = FKDB + FKD1, FKD1 is the opening degree of the electronic expansion valve in the last period, FKD =500 when FKD > =500, and FKD =0 when FKD < =0.

The following are examples of the control of the auxiliary electronic expansion valve

1. Basic information of the system:

the maximum opening of the auxiliary electronic expansion valve is 500 steps, the adjusting range is 0-500 steps, and the ambient temperature is as follows: the method comprises the steps of starting the unit for 300 seconds at minus 12 ℃, operating the unit for 300 seconds at the upper period of opening ZKD1=253 by an auxiliary electronic expansion valve, controlling the current inlet temperature of an economizer to be 18 ℃ at the current inlet of the economizer, controlling the current outlet temperature of the economizer to be 18.5 ℃, controlling the upper period of the economizer to be 19.1 ℃, controlling the current exhaust temperature of a compressor to be 70 ℃, controlling the current outlet temperature of a condenser to be 44 ℃, controlling the outlet temperature of water to be 41 ℃, controlling the inlet temperature of an evaporator to be minus 18 ℃ at the control period of 20 seconds.

2. User setting parameter values

Serial number	Name (R)	Set value	Set range
				1	d1	7	-5～20
2	d2	5	-5～20
				3	T	5	0～10
4	G	60	0～180
				5	d3	10	>0
6	d4	3	>0
				7	d5	300	>0
8	e1	5	4～10
				9	e2	1.2	0～10
10	e3	2.1	0～10
				11	d6	18	10～20
12	b2	2.5	0～5
				14	e4	3	>0
16	e5	1.5	0～3
				17	e6	0.86	>0
18	e7	0.28	>0
				19	e8	-19.5	/
20	e9	1.5	>0
				21	e10	2	>0
22	e11	15	1～20

3. Auxiliary valve opening calculation

Because the compressor is started and operated for 300 seconds, the set value G =60 seconds is exceeded, and the ambient temperature is-12 ℃ < d1=7, the step S209 is directly executed;

since TS1= Tf-Te =18.5-18=0.5, e1=5, tf-Te < e1, step S211 is performed;

since TP1= Tm-Tn =70-44=26> -d6, step S213 is performed;

TJ = e6 + Tn + e7 + Ta + e8=0.86 + 44+0.28 (-17) -19.5=13.58, TJ1-TJ =18-13.58=4.42, e5=1.5, TJ1-TJ > e5, so step S215 is performed with FKDB = e9 (TJ-TJ 1) + e10 (TJ 0-TJ 1) =1.2 (-4.42) +2 (0.5) = -5.63, and FKDB-5 after the round;

because e11=15,fkdb are-woven as e11, FKDB = -5;

because FKD1=253, FKD = FKD1+ FKDB =253-5=248.

In conclusion, the gas supplementing quantity control precision is improved, the stability of the gas supplementing enthalpy-increasing heat pump system is improved step by step, the deviation of heat production quantity in the repeated operation process is reduced, and the consistency of the unit is improved.

Claims

1. A double electronic expansion valve control method of a gas-supplementing enthalpy-increasing heat pump system is characterized by comprising the following steps:

3, resetting the closing valve of the main electronic expansion valve, judging whether the auxiliary electronic expansion valve needs to be opened or not, and if T1 is larger than d1, setting the opening of the auxiliary electronic expansion valve to be 0, and ending; if T1 is less than d2, executing step 4; if d2 is not less than T1 is not less than d1, the auxiliary electronic expansion valve keeps the state of the previous period, T1 is the outdoor environment temperature, and d1 and d2 are set values of a user;

step 6, judging whether the difference value of the actual air suction superheat degree of the evaporator and the target air suction superheat degree and the economizer auxiliary circuit are seriously overheated or not, and executing a step 7 if TH1 is more than TH + b1 or TH1 is less than TH-b2 or TS1 is more than e 1; otherwise, executing step 8; TH1 is the actual superheat degree of the evaporator, TH is the target suction superheat degree of the evaporator, b1, b2 and e1 are set values of a user, and TS1 is the actual inlet and outlet superheat degree of the auxiliary passage of the economizer;

meanwhile, calculating the variable quantity of the auxiliary electronic expansion valve, specifically comprising: the auxiliary electronic expansion valve variable quantity FKDB = e2 (TS 1-e 1) + e3 (TS 1-TS), b3, b4, e2 and e3 are user set values and are all larger than 0, TS is the actual superheat degree of the auxiliary circuit of the economizer in the previous period, and TH0 is the actual suction superheat degree of the previous period;

step 9, judging the calculated variation of the main electronic expansion valve and the calculated variation of the auxiliary electronic expansion valve, if the variation of the main electronic expansion valve is ZKDB & gt c7, making ZKDB = c7, if ZKDB & lt-c 7, making ZKDB = -c7, and if c7 is a user setting value, making the value of c7 be a positive value;

2. The method for controlling the double electronic expansion valves of the air-supplementing enthalpy-increasing heat pump system according to claim 1, further comprising the step 10 of: and calculating the opening degree of a main electronic expansion valve in the current period and the current opening degree of an auxiliary electronic expansion valve, wherein the opening degree of the main electronic expansion valve in the current period ZKD = ZKD1+ ZKDB, the opening degree of the auxiliary electronic expansion valve in the current period FKD = FKDB + FKD1, ZKD1 is the opening degree of the main electronic expansion valve in the previous period, and FKD1 is the opening degree of the electronic expansion valve in the previous period.

3. The method for controlling the double electronic expansion valves of the air-supplementing enthalpy-increasing heat pump system according to claim 1, characterized in that in step 6, TH1= Tb-Ta, tb are actual inlet and outlet temperatures of the evaporator, and are respectively collected by temperature sensors at the inlet and outlet of the evaporator.

4. The method as claimed in claim 1, wherein in step 7, the calculation result of the variation of the main electronic expansion valve is rounded down, and the remainder is accumulated to the next control period.

5. The method as claimed in claim 1, wherein in step 7, the calculation result of the variation of the auxiliary electronic expansion valve is rounded down, and the remainder is accumulated to the next control period.

6. The method for controlling the dual electronic expansion valves of the air-supplementing enthalpy-increasing heat pump system according to claim 1, wherein in step 8, TP1= Tm-Tn, tm and Tn are the compressor discharge temperature and the condenser outlet temperature, respectively.

7. The method as claimed in claim 6, wherein in step 8, TJ = e6 × Tn + e7 × Ta + e8, e6, e7, e8 are set by the user, and e6, e7 are positive values.