Control method for variable-frequency defrosting of air energy heat pump

Abstract

According to the variable-frequency defrosting control method for the air energy heat pump, the air energy heat pump comprises a variable-frequency compressor, and during operation, the method comprises the following steps that firstly, the heat pump operates in a heating mode, and then the second step is executed; (2) defrosting is started, timing of Tk is started, Tk is the current defrosting operation total time, and the step (3) is executed; 3, the central controller of the heat pump judges whether th is smaller than or equal to ts or not, if yes, the fourth step is executed, and if not, the sixth step is executed, th is the current environment temperature, ts is the preset temperature, and the value range of ts is-2 DEG C to 5 DEG C; fourthly, the central controller controls the compressor to operate at the first defrosting frequency P1, the fifth step is executed, and the value range of P1 ranges from 70 Hz to 85 Hz; and step 5, running for a first period T1. The method has the characteristics that the defrosting efficiency is improved, the defrosting time is shortened, and the operation stability and the heating efficiency of the air energy heat pump are improved.

Description

Technical Field

[0001] The invention relates to an air energy heat pump, in particular to a control method for variable frequency defrosting of an air energy heat pump. Background Art

[0002] Air-energy heat pumps currently on the market usually use outdoor temperature detection for defrost control, or use fixed time, fixed compressor operating frequency and fixed electronic expansion valve opening to control the defrost process. However, these control methods can easily cause the air-energy heat pump to frequently enter defrost or defrost by mistake, reducing its heating effect and seriously affecting user experience and product reliability.

[0003] In response to this situation, some manufacturers have made some improvements. For example, Chinese patent document No. CN 116294321A disclosed a variable frequency defrosting method for an air source heat pump on June 23, 2023. The controller detects that the heat pump is in heating mode, the temperature sensor detects that the ambient temperature is 5℃~10℃ and the evaporator temperature is 0℃~2℃, and the heat pump enters the defrost mode. At this time, the controller controls the compressor operating frequency to drop to the medium frequency band and the evaporator power is increased; the controller detects that the heat pump is in heating mode, the temperature sensor detects that the ambient temperature is 5℃~10℃ and the evaporator temperature is -2℃~0℃, and the heat pump enters the defrost mode. The controller controls the compressor operating frequency to drop to the low frequency band and the evaporator power is increased; the controller detects that the heat pump is in heating mode, the temperature sensor detects that the ambient temperature is 3℃~5℃ and the evaporator temperature is -7℃~-2℃, and the heat pump enters the defrost mode, the controller controls the compressor to stop and the evaporator power is increased; the controller detects that the heat pump is in heating mode, the temperature sensor detects that the ambient temperature is 3℃~5℃ and the evaporator temperature is -7℃~-2℃, and the heat pump enters the defrost mode, the controller controls the compressor to stop and the evaporator power is increased; the controller detects that the heat pump is in heating mode, the temperature When the sensor detects that the ambient temperature is -5℃~7℃ and the evaporator temperature is lower than -7℃, the heat pump enters the defrost mode, the controller controls the four-way reversing valve and the compressor to run at high frequency, and the evaporator motor does not run; when the controller detects that the heat pump is in the heating mode, the temperature sensor detects that the ambient temperature is -15℃~-5℃ and the evaporator temperature is more than 5℃ lower than the ambient temperature, the heat pump enters the defrost mode, the controller controls the four-way reversing valve and the compressor to run at high frequency, and the evaporator motor does not run; when the controller detects that the heat pump is in the heating mode; when the temperature sensor detects that the ambient temperature is -15℃~0℃, the heat pump does not enter the defrost mode for two consecutive defrost cycles, or when the temperature sensor detects that the evaporator temperature is lower than -7℃, the heat pump does not enter the defrost mode for two consecutive defrost cycles; then the controller controls the heat pump to enter the defrost mode, the controller controls the start of the four-way reversing valve, the compressor to run at high frequency, and the evaporator motor does not run. However, when this air source heat pump variable frequency defrosting method is actually used, the heat pump is in the defrost state most of the time and can hardly heat, so it needs to be improved. Summary of the invention

[0004] The object of the present invention is to provide a control method for variable frequency defrosting of an air energy heat pump with stable and reliable operation, so as to overcome the shortcomings of the prior art.

[0005] A control method for variable frequency defrosting of an air energy heat pump designed for this purpose, the air energy heat pump includes a variable frequency compressor, and is characterized in that the operation includes the following steps:

[0006] Step 1: Heat pump heating operation, proceed to step 2;

[0007] Step 2: Enter defrost, Tk timing starts, where Tk is the total time of current defrost operation, and then enter step 3;

[0008] Step 3: The central controller of the heat pump determines whether th≤ts is established. If yes, it proceeds to step 4; otherwise, it proceeds to step 6, where th is the current ambient temperature, ts is the preset temperature, and the value range of ts is -2°C to 5°C;

[0009] Step 4: The central controller controls the compressor to operate at the first defrosting frequency P1, and then proceeds to step 5, wherein the value range of P1 is 70 Hz to 85 Hz;

[0010] Step 5: After running the first cycle T1, where the value range of T1 is 0.1 minutes to 20 minutes, proceed to step 6;

[0011] Step 6, the central controller determines whether hp2≥hp1 or a2≥a1 is established. If it is, it goes to step 7, otherwise, it goes to step 5, where hp2 is the current high-pressure side pressure, hp1 is the preset high-pressure side pressure, hp1 is in the range of 3.5Mpa to 4.2Mpa, a2 is the whole current value of the current heat pump, a1 is the whole current value of the preset heat pump, and the value range of a1 for a 3-hp to 8-hp air energy heat pump using single-phase electricity is 8A to 25A;

[0012] Step 7: The central controller controls the compressor to operate at the second defrosting frequency P3, and then enters step 8, wherein the value range of P3 is 50 Hz to 60 Hz;

[0013] Step 8: After running the third cycle T3, where the value range of T3 is 0.1 minutes to 20 minutes, proceed to step 9;

[0014] Step 9, the central controller determines whether hp2≥hp1 or a2≥a1 is established. If yes, it goes to step 10, otherwise, it goes to step 8;

[0015] Step 10, the central controller controls the compressor to operate at the fourth defrosting frequency P4, the value range of P4 is 40Hz~50Hz, and then proceeds to step 11;

[0016] Step 11: After running the fourth cycle T4, where the value range of T4 is 0.1 minutes to 20 minutes, proceed to step 12;

[0017] Step 12, the central controller determines whether Tk≥Tm is established. If yes, it goes to step 13, otherwise, it goes to step 11; wherein Tm is the preset defrost time, and the value range of Tm is 5 minutes to 60 minutes;

[0018] Step 13, exit defrosting and enter step 1;

[0019] Step 14: the central controller controls the compressor to operate at the second defrosting frequency P2, the value range of P2 is 60Hz to 70Hz, and then proceeds to step 15;

[0020] Step 15, after running the second cycle T2, wherein the value range of T2 is 0.1 minutes to 20 minutes, proceed to step 16;

[0021] In step 16, the central controller determines whether hp2≥hp1 or a2≥a1 is established. If yes, it proceeds to step 7; otherwise, it proceeds to step 15.

[0022] After the present invention adopts the above-mentioned technical scheme, when the heat pump is defrosted, the pressure value and current value of the air energy heat pump during operation are monitored and collected, and then the variable frequency compressor is controlled to prevent the air energy heat pump from having problems such as defrosting high pressure protection, overcurrent protection, long defrosting time, and low heating efficiency. The defrost frequency and defrost operation time and other parameters of the air energy heat pump are changed in real time, thereby improving the defrost efficiency, shortening the defrost time, and improving the stability of the operation of the air energy heat pump and the heating efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 FIG. 4 is a control flow chart of an embodiment of the present invention. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0025] See also Figure 1 , a control method for variable frequency defrosting of an air energy heat pump, wherein the air energy heat pump comprises a variable frequency compressor, and the operation comprises the following steps:

[0026] Step 1: Heat pump heating operation, proceed to step 2;

[0027] Step 2: Enter defrost, Tk timing starts, where Tk is the total time of current defrost operation, and then enter step 3;

[0028] Step 3: The central controller of the heat pump determines whether th≤ts is established. If yes, it proceeds to step 4; otherwise, it proceeds to step 6, where th is the current ambient temperature, ts is the preset temperature, and the value range of ts is -2°C to 5°C;

[0029] Step 4: The central controller controls the compressor to operate at the first defrosting frequency P1, and then proceeds to step 5, wherein the value range of P1 is 70 Hz to 85 Hz;

[0030] Step 5: After running the first cycle T1, where the value range of T1 is 0.1 minutes to 20 minutes, proceed to step 6;

[0031] Step six, the central controller determines whether hp2≥hp1 or a2≥a1 is established. When it is yes, it goes to step seven, otherwise, it goes to step five, wherein hp2 is the current high-pressure side pressure, hp1 is the preset high-pressure side pressure, hp1 is an absolute pressure value in the range of 3.5Mpa to 4.2Mpa, a2 is the whole current value of the current heat pump, a1 is the whole current value of the preset heat pump, and the value range of a1 for the 3-hp to 8-hp air-to-air heat pump using single-phase electricity is 8A to 25A.

[0032] When the central controller determines that hp2≥hp1 or a2≥a1 is established, it indicates that the defrost pressure and current are both reduced and the defrost is proceeding normally. Therefore, the central controller reduces the operating frequency of the variable frequency compressor from the first defrost frequency P1 to the second defrost frequency P3 based on the judgment that the air energy heat pump is currently operating reliably.

[0033] When the current ambient temperature th is high and the water temperature rises, the main changes in the heat pump are reflected in increased pressure or excessive module drive current. Therefore, by controlling the two parameters of pressure and current together, the operation of the heat pump, including defrosting, can be made more stable and reliable.

[0034] Step 7: The central controller controls the compressor to operate at the second defrosting frequency P3, and then enters step 8, wherein the value range of P3 is 50 Hz to 60 Hz;

[0035] Step 8: After running the third cycle T3, where the value range of T3 is 0.1 minutes to 20 minutes, proceed to step 9;

[0036] Step 9, the central controller determines whether hp2≥hp1 or a2≥a1 is established. If yes, it goes to step 10, otherwise, it goes to step 8;

[0037] Step 10, the central controller controls the compressor to operate at the fourth defrosting frequency P4, the value range of P4 is 40Hz~50Hz, and then proceeds to step 11;

[0038] Step 11: After running the fourth cycle T4, where the value range of T4 is 0.1 minutes to 20 minutes, proceed to step 12;

[0039] Step 12, the central controller determines whether Tk≥Tm is established. If yes, it goes to step 13, otherwise, it goes to step 11; wherein Tm is the preset defrost time, and the value range of Tm is 5 minutes to 60 minutes;

[0040] Step 13, exit defrosting and enter step 1;

[0041] Step 14: the central controller controls the compressor to operate at the second defrosting frequency P2, the value range of P2 is 60Hz to 70Hz, and then proceeds to step 15;

[0042] Step 15, after running the second cycle T2, wherein the value range of T2 is 0.1 minutes to 20 minutes, proceed to step 16;

[0043] In step 16, the central controller determines whether hp2≥hp1 or a2≥a1 is established. If yes, it proceeds to step 7; otherwise, it proceeds to step 15.

[0044] When setting the above parameters, it is necessary to pay attention to P1>P2>P3>P4.

[0045] Application example: Single-phase 15KW air energy heat pump heating operation, the preset values ​​ts is 0℃, a1 is 18A, and hp1 is 3.7Mpa.

[0046] During operation, the detected ambient temperature th is -2°C, th<ts, the outdoor coil temperature is -12°C, the air energy heat pump meets the defrosting conditions and enters defrosting. At this time, the defrosting frequency is 72Hz.

[0047] During operation, the air energy heat pump detects that the current value a2 of the heat pump is 20A, and a2>a1. Therefore, the defrost frequency is reduced from 72Hz to 68Hz and the defrost operation continues.

[0048] When the air energy heat pump system detects again that the current high-pressure side pressure hp2 is 3.8MPa, hp2>hp1, the defrost frequency is reduced from the original 68Hz to 63Hz and continues to defrost until the defrost is completed.

[0049] In the description of the present invention, it should be understood that the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features.

[0050] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A control method for variable frequency defrosting of an air energy heat pump, wherein the air energy heat pump comprises a variable frequency compressor, characterized in that The operation includes the following steps: Step 1: Heat pump heating operation, proceed to step 2; Step 2: Enter defrost, Tk timing starts, where Tk is the total time of current defrost operation, and then enter step 3; Step 3: The central controller of the heat pump determines whether th≤ts is established. If yes, it proceeds to step 4; otherwise, it proceeds to step 6, where th is the current ambient temperature, ts is the preset temperature, and the value range of ts is -2°C to 5°C; Step 4: The central controller controls the compressor to operate at the first defrosting frequency P1, and then proceeds to step 5, wherein the value range of P1 is 70 Hz to 85 Hz; Step 5: After running the first cycle T1, where the value range of T1 is 0.1 minutes to 20 minutes, proceed to step 6; Step 6, the central controller determines whether hp2≥hp1 or a2≥a1 is established. If it is, it goes to step 7, otherwise, it goes to step 5, where hp2 is the current high-pressure side pressure, hp1 is the preset high-pressure side pressure, hp1 is in the range of 3.5Mpa to 4.2Mpa, a2 is the whole current value of the current heat pump, a1 is the whole current value of the preset heat pump, and the value range of a1 for a 3-hp to 8-hp air energy heat pump using single-phase electricity is 8A to 25A; Step 7: The central controller controls the compressor to operate at the second defrosting frequency P3, and then enters step 8, wherein the value range of P3 is 50 Hz to 60 Hz; Step 8: After running the third cycle T3, where the value range of T3 is 0.1 minutes to 20 minutes, proceed to step 9; Step 9, the central controller determines whether hp2≥hp1 or a2≥a1 is established. If yes, it goes to step 10, otherwise, it goes to step 8; Step 10, the central controller controls the compressor to operate at the fourth defrosting frequency P4, the value range of P4 is 40Hz~50Hz, and then proceeds to step 11; Step 11: After running the fourth cycle T4, where the value range of T4 is 0.1 minutes to 20 minutes, proceed to step 12; Step 12, the central controller determines whether Tk≥Tm is established. If yes, it goes to step 13, otherwise, it goes to step 11; wherein Tm is the preset defrost time, and the value range of Tm is 5 minutes to 60 minutes; Step 13, exit defrosting and enter step 1; Step 14: the central controller controls the compressor to operate at the second defrosting frequency P2, the value range of P2 is 60Hz to 70Hz, and then proceeds to step 15; Step 15, after running the second cycle T2, wherein the value range of T2 is 0.1 minutes to 20 minutes, proceed to step 16; In step 16, the central controller determines whether hp2≥hp1 or a2≥a1 is established. If yes, it proceeds to step 7; otherwise, it proceeds to step 15.

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