Control method for defrosting of air source heat pump

Abstract

A control method for defrosting of an air source heat pump comprises the following steps that firstly, the heat pump is powered on for operation for the first time, and then the second step is executed; secondly, the heat pump enters defrosting operation for the first time, and the third step is executed; thirdly, the average voltage value V0 of the fan motor and the total defrosting time T are recorded, the fourth step is executed, the unit of V0 is volt, and the unit of T is second; fourthly, the first defrosting is quitted, and the fifth step is executed; and 5, a reference value F0 of the PWM feedback value of the fan motor is obtained through calculation and stored, the step 6 is executed, F0 = A + (60000 * V0) / B, and A is a compensation constant. On the basis of the existing defrosting time, the PWM feedback value of the fan motor is introduced to adjust the defrosting time, so that the defrosting time can be more accurately controlled, frequent defrosting caused by too short defrosting time or heat efficiency reduction caused by too long defrosting time is avoided, and stable and reliable operation of the heat pump is ensured.

Description

Technical Field

[0001] The invention relates to an air source heat pump, and in particular to a defrosting control method for an air source heat pump. Background Art

[0002] Air source heat pumps have been widely popularized due to their environmental protection, comfortable use, high energy utilization, and simple installation conditions. However, when the air source heat pump is running in winter, the frosting of its evaporator will have a serious adverse effect on the performance of the air source heat pump. Therefore, how to effectively defrost is the key to solving the winter operation of the air source heat pump. Nowadays, most air source heat pump manufacturers use the detection of coil temperature as the judgment condition for entering and exiting defrosting, but in the actual operation of the heat pump, problems such as uneven frosting or unclean defrosting may occur. These problems will cause the evaporation temperature of the heating operation to be low, which will then affect the next defrosting time in advance, and the energy efficiency of the air source heat pump will be greatly reduced.

[0003] In response to this situation, some manufacturers have made some improvements. For example, Chinese patent document number CN 118532853A disclosed a heat pump defrosting control system on August 23, 2024, including a heat pump unit, wherein the heat pump unit is provided with a compressor, a four-way valve, a plate heat exchanger, an auxiliary heat exchanger and a fan. When the heat pump unit needs to be defrosted after a period of heating operation, the control system is controlled as follows: the compressor runs to the defrosting frequency, the four-way valve is powered on, the fan is powered off, the first solenoid valve is powered on, the second solenoid valve is not powered on, and the electronic expansion valve is powered on. The bottom and the upper part of the bottom of the auxiliary heat exchanger are first defrosted, and the defrosting time of this part is controlled to be one-third of the total defrosting time; when the defrosting action is completed according to the set defrosting time, the second solenoid valve is powered on, the first solenoid valve is not powered on, and the secondary defrosting is entered at this time. In actual use, the defrosting effect of this heat pump defrosting control system is still not ideal and needs to be improved. Summary of the invention

[0004] The object of the present invention is to provide a control method for defrosting an air source heat pump with accurate defrosting time, so as to overcome the shortcomings of the prior art.

[0005] A control method for defrosting an air source heat pump designed for this purpose is characterized by comprising the following steps:

[0006] Step 1: The heat pump is powered on for the first time and then goes to step 2;

[0007] Step 2: The heat pump enters defrosting operation for the first time, and then proceeds to step 3;

[0008] Step 3, record the average value V0 of the fan motor voltage and the total defrosting time T, and proceed to step 4, where V0 is in volts and T is in seconds;

[0009] Step 4, exit the first defrost and enter step 5;

[0010] Step 5, calculate and store the reference value F0 of the fan motor PWM feedback value, and enter step 6, wherein F0=A+(60000*V0) / B, A is a compensation constant, the value range of A is 300-500, and B=6.5 volts;

[0011] Step 6: The heat pump is in heating operation, and then proceeds to step 7;

[0012] Step 7, collect the fan motor PWM feedback value, and take the average value of the fan motor PWM feedback value within 1 minute before defrosting as the actual value Fn, record the fan motor voltage average value V1 within 1 minute before defrosting, calculate the actual value Fn of the current fan motor PWM feedback value before defrosting, and enter step 8, wherein Fn = (60000*V1) / B, and the unit of V1 is volt;

[0013] Step 8, enter defrosting, and then enter step 9;

[0014] Step nine, calculate the difference Fc, Fc = Fn - F0, and go to step ten;

[0015] Step 10, the central controller of the heat pump determines whether -400≤Fc<-300 is established, if it is true, it goes to step 19, otherwise it goes to step 11;

[0016] Step 11, the central controller of the heat pump determines whether -300≤Fc<-200 is established, if it is yes, it goes to step 20, otherwise it goes to step 12;

[0017] Step 12, the central controller of the heat pump determines whether -200≤Fc<-100 is established, and if so, proceeds to step 21, otherwise proceeds to step 13;

[0018] Step 13, the central controller of the heat pump determines whether -100≤Fc<0 is established, and if so, proceeds to step 22, otherwise proceeds to step 14;

[0019] Step 14, the central controller of the heat pump determines whether 0≤Fc<100 is established, and if so, proceeds to step 23, otherwise proceeds to step 15;

[0020] Step 15, the central controller of the heat pump determines whether 100≤Fc<200 is established, and if so, proceeds to step 24, otherwise proceeds to step 16;

[0021] Step 16, the central controller of the heat pump determines whether 200≤Fc<300 is established, and if so, proceeds to step 25, otherwise, proceeds to step 17;

[0022] Step 17, the central controller of the heat pump determines whether 300≤Fc<400 is established, if it is yes, it goes to step 26, otherwise it goes to step 18;

[0023] Step 18, executing defrost time T;

[0024] Step 19, T=T-60, proceed to step 18;

[0025] Step 20, T=T-45, proceed to step 18;

[0026] Step 21, T=T-30, proceed to step 18;

[0027] Step 22, T=T-15, go to step 18;

[0028] Step 23, T=T, go to step 18;

[0029] Step 24, T=T+15, proceed to step 18;

[0030] Step 25, T=T+30, proceed to step 18;

[0031] Step 26, T=T+45, proceed to step 18;

[0032] Step 27, T=T+60, proceed to step 18.

[0033] On the basis of the existing defrost time, the present invention introduces the fan motor PWM feedback value to adjust the defrost time, so that the defrost time can be controlled more accurately, avoiding frequent defrosting due to too short defrost time or reduced thermal efficiency due to too long defrost time, thereby ensuring stable and reliable operation of the heat pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 FIG. 4 is a control flow chart of an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0036] See also Figure 1 , a control method for defrosting an air source heat pump, comprising the following steps:

[0037] Step 1: The heat pump is powered on for the first time and then goes to step 2;

[0038] Step 2: The heat pump enters defrosting operation for the first time, and then proceeds to step 3;

[0039] Step 3, record the average value V0 of the fan motor voltage and the total defrosting time T, and proceed to step 4, where V0 is in volts and T is in seconds;

[0040] Step 4, exit the first defrost and enter step 5;

[0041] Step 5, calculate and store the reference value F0 of the fan motor PWM feedback value, and enter step 6, wherein F0=A+(60000*V0) / B, A is the compensation constant, the value range of A is 300-500, and B=6.5 volts.

[0042] When a specific speed value is set for the fan, a specific input voltage needs to be provided to the motor used to drive the fan to rotate so that the fan speed reaches the set speed. At this time, the fan motor will have a feedback voltage.

[0043] When frosting occurs, the load of the fan will gradually increase, and the input voltage must continue to increase to make the fan run stably at the set speed. At this time, the feedback voltage of the fan motor will also continue to increase.

[0044] When the heat pump is running in heating mode, the surface of the outdoor heat exchanger will gradually frost. As the frost layer gradually increases, the fan motor PWM feedback value will also continue to increase.

[0045] During defrosting, the fan motor will stop and the fan motor PWM feedback value will become zero. After defrosting, when the fan motor is turned on again, the fan motor PWM feedback value will gradually increase from zero.

[0046] The feedback voltage of the fan motor is fed back once per second.

[0047] Example: The average voltage V0 of the fan motor of the heat pump one minute before exiting the first defrost is 5 volts, so the reference value F0 is 500+(60000*5) / 6.5=46653.

[0048] Due to the choices of different users, the heat pump will be in different working environments with large differences in temperature, humidity, etc. After the first defrost and completion, an actual total defrost time T will be obtained.

[0049] Step 6: The heat pump is in heating operation, and then proceeds to step 7;

[0050] Step seven, collect the fan motor PWM feedback value, and take the average value of the fan motor PWM feedback value within 1 minute before defrosting as the actual value Fn, record the fan motor voltage average value V1 within 1 minute before defrosting, calculate the actual value Fn of the current fan motor PWM feedback value before defrosting, and enter step eight, wherein Fn = (60000*V1) / B, and the unit of V1 is volt.

[0051] Example: The average voltage of the fan motor V1 within 1 minute before defrosting = 5.3 volts,

[0052] Fn=(60000*V1) / B=(60000*5.3) / 6.5=48923.

[0053] Step 8, enter defrosting, and then enter step 9;

[0054] Step nine, calculate the difference Fc, Fc = Fn - F0, and go to step ten;

[0055] Example: Fc=Fn-F0=48923-46653=2270.

[0056] Step 10, the central controller of the heat pump determines whether -400≤Fc<-300 is established, if it is true, it goes to step 19, otherwise it goes to step 11;

[0057] Step 11, the central controller of the heat pump determines whether -300≤Fc<-200 is established, if it is yes, it goes to step 20, otherwise it goes to step 12;

[0058] Step 12, the central controller of the heat pump determines whether -200≤Fc<-100 is established, and if so, proceeds to step 21, otherwise proceeds to step 13;

[0059] Step 13, the central controller of the heat pump determines whether -100≤Fc<0 is established, and if so, proceeds to step 22, otherwise proceeds to step 14;

[0060] Step 14, the central controller of the heat pump determines whether 0≤Fc<100 is established, and if so, proceeds to step 23, otherwise proceeds to step 15;

[0061] Step 15, the central controller of the heat pump determines whether 100≤Fc<200 is established, and if so, proceeds to step 24, otherwise proceeds to step 16;

[0062] Step 16, the central controller of the heat pump determines whether 200≤Fc<300 is established, and if so, proceeds to step 25, otherwise, proceeds to step 17;

[0063] Step 17, the central controller of the heat pump determines whether 300≤Fc<400 is established, if it is yes, it goes to step 26, otherwise it goes to step 18;

[0064] Step 18, executing defrost time T;

[0065] Step 19, T=T-60, proceed to step 18;

[0066] Step 20, T=T-45, proceed to step 18;

[0067] Step 21, T=T-30, proceed to step 18;

[0068] Step 22, T=T-15, go to step 18;

[0069] Step 23, T=T, go to step 18;

[0070] Step 24, T=T+15, proceed to step 18;

[0071] Step 25, T=T+30, proceed to step 18;

[0072] Step 26, T=T+45, proceed to step 18;

[0073] Step 27, T=T+60, proceed to step 18.

[0074] Since Fc=2270, the process goes to step 27. The total duration of the actual defrosting operation this time is longer than the total duration of the first defrosting operation, that is, T=T+60 seconds.

[0075] 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.

[0076] 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 defrosting an air source heat pump, characterized in that The following steps are involved: Step 1: The heat pump is powered on for the first time and then goes to step 2; Step 2: The heat pump enters defrosting operation for the first time, and then proceeds to step 3; Step 3, record the average value of the fan motor voltage V0 and the total defrosting time T, and proceed to step 4, where V0 is in volts and T is in seconds; Step 4, exit the first defrost and enter step 5; Step 5, calculate and store the reference value F0 of the fan motor PWM feedback value, and enter step 6, wherein F0=A+(60000*V0) / B, A is a compensation constant, the value range of A is 300-500, and B=6.5 volts; Step 6: The heat pump is in heating operation, and then proceeds to step 7; Step 7, collect the fan motor PWM feedback value, and take the average value of the fan motor PWM feedback value within 1 minute before defrosting as the actual value Fn, record the fan motor voltage average value V1 within 1 minute before defrosting, calculate the actual value Fn of the current fan motor PWM feedback value before defrosting, and enter step 8, wherein Fn = (60000*V1) / B, and the unit of V1 is volt; Step 8, enter defrosting, and then enter step 9; Step nine, calculate the difference Fc, Fc = Fn - F0, and go to step ten; Step 10, the central controller of the heat pump determines whether -400≤Fc<-300 is established, if it is true, it goes to step 19, otherwise it goes to step 11; Step 11, the central controller of the heat pump determines whether -300≤Fc<-200 is established, if it is yes, it goes to step 20, otherwise it goes to step 12; Step 12, the central controller of the heat pump determines whether -200≤Fc<-100 is established, and if so, proceeds to step 21, otherwise, proceeds to step 13; Step 13, the central controller of the heat pump determines whether -100≤Fc<0 is established, and if so, proceeds to step 22, otherwise proceeds to step 14; Step 14, the central controller of the heat pump determines whether 0≤Fc<100 is established, and if so, proceeds to step 23, otherwise proceeds to step 15; Step 15, the central controller of the heat pump determines whether 100≤Fc<200 is established, and if so, proceeds to step 24, otherwise proceeds to step 16; Step 16, the central controller of the heat pump determines whether 200≤Fc<300 is established, and if so, proceeds to step 25, otherwise, proceeds to step 17; Step 17, the central controller of the heat pump determines whether 300≤Fc<400 is established, and if so, proceeds to step 26, otherwise proceeds to step 18; Step 18, executing defrost time T; Step 19, T=T-60, proceed to step 18; Step 20, T=T-45, proceed to step 18; Step 21, T=T-30, proceed to step 18; Step 22, T=T-15, go to step 18; Step 23, T=T, go to step 18; Step 24, T=T+15, proceed to step 18; Step 25, T=T+30, proceed to step 18; Step 26, T=T+45, proceed to step 18; Step 27, T=T+60, proceed to step 18.

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