CN-116772469-B - Control method for opening degree of expansion valve in starting-up and frequency-raising of heat pump host and heat pump system

CN116772469BCN 116772469 BCN116772469 BCN 116772469BCN-116772469-B

Abstract

The invention relates to a control method of the opening of an expansion valve in the startup and frequency raising of a heat pump host, comprising the following steps of obtaining the backwater temperature and the environment temperature of the startup of a heat pump system, and correcting the backwater temperature and the environment temperature to obtain the reference opening of the expansion valve of the startup of the heat pump host; the method comprises the steps of obtaining a current compressor frequency value of a heat pump host machine every one valve regulating period, calculating to obtain a current compressor frequency rising value according to the compressor frequency value of the last valve regulating period, correcting the compressor frequency rising value, and determining the current opening value of the expansion valve according to the reference opening of the expansion valve, the corrected compressor frequency rising value and the frequency change coefficient. The control method of the opening of the expansion valve in the startup and frequency raising of the heat pump host can enable the setting of the opening of the expansion valve to be more in line with the variation of the flow of the system refrigerant under different frequencies in the startup stage of the compressor, so that the control of the flow of the refrigerant is more accurate, the problem that the opening of the expansion valve is not matched with the flow of the system refrigerant in the startup stage of the unit can be effectively avoided, and the problem that the liquid return phenomenon of the compressor occurs is further avoided.

Inventors

WU JINGLONG
TONG FENGXI
ZHENG SHUANGMING

Assignees

中山市爱美泰电器有限公司
热立方科技(佛山市)有限公司

Dates

Publication Date: 20260508
Application Date: 20230621

Claims (9)

1. The method for controlling the opening of the expansion valve in the startup and frequency raising of the heat pump host is characterized by comprising the following steps: S10, acquiring a return water temperature T RW and an environment temperature T E when the heat pump system is started, correcting the return water temperature T RW and the environment temperature T E , and determining a reference opening degree C1 of the expansion valve according to the corrected return water temperature T RW and the corrected environment temperature T E , wherein the C1 satisfies the following relation: C1=MAX[a*T′ RW ,0]+MAX[bT′ E ,0]+c 1 Wherein T ' RW denotes a corrected return water temperature, a denotes a control coefficient of the corrected return water temperature, T' E denotes a corrected ambient temperature, b denotes a control coefficient of the corrected ambient temperature, c 1 denotes a compensation value of the expansion valve reference opening degree, and MAX denotes a function formula taking the maximum value; s20, acquiring a current compressor frequency value F N of a heat pump host machine every time delta t, and calculating to obtain a current compressor frequency rising value delta F according to a compressor frequency value F L of a last valve regulating period, wherein delta t is the valve regulating period; s30, correcting the frequency rising value delta F of the compressor to obtain a corrected frequency rising value delta F' of the compressor; S40, calculating according to the expansion valve reference opening C1, the corrected compressor frequency rising value delta F 'and the frequency change coefficient Q to obtain the expansion valve current opening value C1'.
2. The control method according to claim 1, wherein the compressor frequency rise value Δf in step S20 satisfies the following equation: ΔF=F N -F L Wherein, F N represents the current compressor frequency value of the heat pump host, F L represents the compressor frequency value of the one-valve-adjusting period on the heat pump host; Wherein, the valve adjusting period is set to Δt=5 seconds in the start-up phase, and is set to Δt=20 seconds thereafter.
3. The control method according to claim 2, wherein the compressor frequency rise Δf is corrected in step S30 by means of constant value compensation, and the corrected compressor frequency rise Δf' satisfies the following equation: ΔF′=ΔF-A In the formula, A represents a compensation value of a compressor frequency rising value.
4. A control method according to any one of claims 1 to 3, wherein the current opening value C1' of the expansion valve in step S40 satisfies the following relation: C1′=Q*ΔF′+C1 where Δf' represents a corrected compressor frequency rise value, Q represents a frequency change coefficient, and C1 represents a reference opening degree of the expansion valve.
5. The control method according to claim 4, wherein the frequency variation coefficient Q is determined by: when the frequency rising value of the adjacent valve regulating period is smaller than 48Hz, the frequency change coefficient Q=1; when the frequency rising value of the adjacent valve regulating period is more than or equal to 48Hz and less than 65Hz, the frequency change coefficient Q=1.5; When the frequency rising value of the adjacent valve adjusting period is larger than 65Hz, the frequency change coefficient q=2.
6. The control method according to claim 1, wherein in step S10, the return water temperature T RW and the ambient temperature T E are corrected by means of constant compensation, and the corrected return water temperature T' RW is expressed as: T′ RW ＝T RW -B wherein B represents a compensation value of the backwater temperature T RW ; the corrected ambient temperature T E ' is expressed as: T E ′＝-(T E -C) Where C represents a compensation value for the ambient temperature T E .
7. The control method according to claim 1, wherein the numerical range of the control coefficient a of the corrected return water temperature is 0.5-2, and the numerical range of the control coefficient b of the corrected ambient temperature is 0.5-2.
8. The heat pump system comprises a compressor, a condenser, an expansion valve, an evaporator, a water circulation unit and a control unit, wherein the compressor, the condenser, the expansion valve and the evaporator are sequentially connected in a circulating way through a refrigerant pipeline; the control unit is electrically connected with the compressor and the expansion valve, and is characterized by comprising a temperature measuring component and a controller, wherein the temperature measuring component collects ambient temperature and backwater temperature of the water circulation unit and transmits collected temperature signals to the controller, the controller collects frequency signals of the compressor, and after a current opening value of the expansion valve is calculated by a program stored on the controller and used for controlling the opening of the expansion valve in the starting-up and frequency raising of the heat pump host according to any one of claims 1-7, the control unit sends a signal for adjusting the opening to the expansion valve, and further controls the opening adjustment of the expansion valve.
9. The heat pump system of claim 8, wherein the temperature measurement component comprises a first temperature sensor and a second temperature sensor, the first temperature sensor is disposed in a water return line of the water circulation unit for detecting a return water temperature and transmitting a return water temperature signal to the controller, and the second temperature sensor is configured to detect an ambient temperature and transmitting an ambient temperature signal to the controller.

Description

Control method for opening degree of expansion valve in starting-up and frequency-raising of heat pump host and heat pump system Technical Field The invention relates to the field of heat pumps, in particular to a control method for opening of an expansion valve in starting up and frequency raising of a heat pump host and a heat pump system. Background The existing air source heat pump host sets a reference opening degree for the expansion valve at the initial starting-up stage of the operation of the heat pump host so as to meet the normal operation of the unit. The accuracy that the benchmark aperture set up can directly influence stability and the energy-conserving nature of unit system, and improper benchmark aperture can influence the operation of unit, and even the unit has liquid return and oil return risk, influences the unit reliability, brings the potential safety hazard for the quality of unit, can increase the probability that the unit burns out in the frequent application that opens of unit especially. At present, a unit control scheme of a starting-up process of most frequency conversion systems operates under a fixed reference opening degree (an expansion valve opening degree fixed at the initial stage of starting up) by setting a unit. In the heating mode, the opening value of the expansion valve is determined according to the range of the ambient temperature (T E) and the backwater temperature (T RW) after the compressor is started, so that the basic operation of the unit is met. An expansion valve opening value table (confirmed by laboratory tests) preset according to the corresponding ambient temperature and backwater temperature is shown in table 1, which is an initial value corresponding to the ambient temperature range and backwater temperature range, and is not accurate compared with the refrigerant flow control. Because the air conditioning unit is different in optimal refrigerant flow control under different ambient temperatures and water temperatures, the opening values of the corresponding expansion valves are also different. TABLE 1 expansion valve reference opening degree table for common start-up stage On the other hand, referring to fig. 1, since the compressor needs to be kept at 2 platform frequency points for 1 to 2 minutes during the starting process, the frequency raising logic of the compressor under the condition that the common unit is started is as follows: 1) When the target frequency is smaller than the platform 1, the compressor frequency is increased to the target frequency after the platform 1 operates for 1 to 2 minutes; 2) When the target frequency is greater than or equal to the platform 1 and less than the platform 2, the compressor frequency is increased to the target frequency after the platform 1 operates for 1 to 2 minutes; 3) When the target frequency is greater than or equal to the platform 2, the compressor frequency is increased to the target frequency after the platform 1 operates for 1 minute and is increased to the platform 2 operates for 1 to 2 minutes. In the process, the frequency of the compressor is gradually increased, the circulation quantity of the refrigerant is always increased, the opening of the expansion valve is always a fixed reference opening, at the moment, the refrigerant flow of the system is extremely mismatched with the opening of the expansion valve, and the problem of liquid return of the compressor is greatly probability. Therefore, it is necessary to study how to accurately control the opening of the expansion valve to match the flow of the refrigerant in the startup and frequency raising stage of the compressor, so as to avoid the problem of liquid return of the compressor. Disclosure of Invention Based on the above, the invention aims to provide a control method for the opening of the expansion valve in the starting-up and frequency-raising of the heat pump host, which can accurately control the refrigerant flow to meet the requirement of target frequency by accurately controlling the opening of the expansion valve in the starting-up and frequency-raising stage of the compressor, thereby avoiding the problem of liquid return of the compressor. A control method for opening of expansion valve in starting up and raising frequency of heat pump host includes the following steps: S10, acquiring a return water temperature T RW and an environment temperature T E when the heat pump system is started, correcting the return water temperature T RW and the environment temperature T E, and determining a reference opening degree C1 of the expansion valve according to the corrected return water temperature T RW and the corrected environment temperature T E; s20, acquiring a current compressor frequency value F N of a heat pump host machine every time delta t, and calculating to obtain a current compressor frequency rising value delta F according to a compressor frequency value F L of a last valve regulating period, wherein delta t is the