Heat pump system with ultrasonic defrosting control based on wind feeling

Abstract

The invention relates to a wind-feeling-based heat pump system with an ultrasonic defrosting control function. Whether the system needs to start ultrasonic defrosting or not is judged according to the heating operation duration and the PWM difference value between the PWM average value of the direct-current fan gear wind speed and the PWM reference value; according to the correlation between the change rate of the PWM difference value of the direct current fan and the frosting rate and the frosting thickness of the system; an ultrasonic defrosting working mode is carried out by adopting the change rate of the PWM difference value; more accurate, efficient and reliable defrosting is achieved, the comfort requirement of a user for heating and refrigerating is met, and the good energy-saving and consumption-reducing effects are achieved; meanwhile, the ultrasonic generator can be reasonably started, and the problems of power output efficiency reduction, damage and the like caused by long-time use are avoided.

Description

Technical Field

[0001] The invention relates to the field of heat pump system control, and in particular to a heat pump system with ultrasonic defrosting control based on wind sensing. Background Art

[0002] The heat pump system is an efficient and environmentally friendly energy utilization technology. Its core working principle is the reverse Carnot cycle. It transfers the heat energy in the low-temperature heat source to the high-temperature environment by consuming a small amount of electricity or other energy to achieve the purpose of heating or cooling. The heat pump system absorbs the low-temperature heat energy in the air with very little electricity, converts it into high-temperature heat energy after compression by the compressor, and then transmits it to the place that needs heating or cooling. It is highly favored by consumers and users and has been widely used for refrigeration and hot water supply in hotels, schools, hospitals, saunas, beauty salons, swimming pools, laundries and other places.

[0003] When the heat pump system is operating in a cold and humid area, its finned air-side heat exchanger is very prone to frost, causing the frost to block the fin gaps, obstruct the air passage, reduce the air flow between the fins, increase the thermal resistance of the heat exchanger, reduce the efficiency of evaporative heat exchange, and even cause unit operation failure.

[0004] At present, the defrosting methods of refrigeration equipment such as air conditioners and heat pump systems are mostly based on the reverse defrosting of the traditional four-way valve working valve port. This defrosting method has high energy consumption, low efficiency, and poor user experience of heat and cooling. In order to avoid the defrosting of the four-way valve reversing, suppliers use technologies such as double evaporator cross defrosting and ultrasonic defrosting to ensure that users' heating and cooling needs are not interrupted and the user's comfort is guaranteed. The research on existing ultrasonic defrosting technology mainly includes two types: one is to rely on the propagation of ultrasonic waves in the air to form turbulent fluctuations of water vapor near the evaporator fins, which interferes with the frosting of water vapor on the evaporator fins; the other is to rely on the propagation of ultrasonic waves in the solid to induce mechanical vibration and shake off the frost on the surface of the evaporator fins. However, when the ultrasonic generator works continuously at high power, it will heat up sharply, causing the resonant frequency of the transducer to drift significantly, the power output efficiency to decrease, and even cause damage to the transducer and ultrasonic power supply. Therefore, it is very important to control the ultrasonic wave to start defrosting according to the frosting situation of the heat pump system. Summary of the invention

[0005] Based on this, the purpose of the present invention is to provide a heat pump system with ultrasonic defrost control based on wind sensing. According to the correlation between the change rate of the DC fan PWM value and the system frosting rate and frosting thickness, the frosting condition of the system can be accurately judged by monitoring the change rate of the DC fan PWM value, and the start-up and operation mode of the ultrasonic generator can be controlled according to the frosting condition.

[0006] A heat pump system with ultrasonic defrosting control based on wind sensing comprises a compressor, a four-way valve, a water-side heat exchanger, an electronic expansion valve, an air-side heat exchanger connected in sequence through a refrigerant circulation pipeline, and a DC fan arranged on one side of the air-side heat exchanger, and an ultrasonic generator arranged on the other side of the air-side heat exchanger, and a temperature detection module, and a controller electrically and / or communicatively connected to the compressor, the DC fan, the ultrasonic generator, and the temperature detection module. The controller controls the defrosting of the heat pump system in the following manner:

[0007] Get the system's current continuous heating operation time and cumulative heating operation time:

[0008] If the continuous heating operation time is greater than the set continuous heating time threshold, and the accumulated heating operation time is greater than the set second defrosting interval time threshold;

[0009] Then obtain the PWM average value of the DC fan gear speed in the current period, and calculate the PWM difference between the PWM average value and the PWM benchmark average value;

[0010] If the PWM difference is greater than or equal to the PWM difference threshold, the wind-sensing defrost control mode is entered; the change rate r of the DC fan PWM difference in the current period is calculated, and the ultrasonic generator is controlled to start the intermittent defrost or continuous defrost mode according to the change rate interval to which the change rate r belongs, where the change rate r satisfies:

[0011]

[0012] Where: ΔPWM t Indicates the DC fan PWM difference in the current period, ΔPWM t-1 Indicates the DC fan PWM difference in the previous period.

[0013] Furthermore, the PWM difference satisfies:

[0014]

[0015] Where: ΔPWM represents the PWM difference, Indicates the wind speed F of the DC fan in the i-th gear in the current period i The average value of PWM, Indicates the wind speed F of the DC fan at the i-th gear measured after the last defrost cycle. i The PWM average value.

[0016] Furthermore, the change rate interval and its corresponding ultrasonic defrosting mode are:

[0017] In the first change rate interval, 0≤r<the first change rate threshold, the ultrasonic intermittent defrosting mode is turned on, and the defrosting is paused for 2 minutes every 1 minute;

[0018] In the second change rate interval, the first change rate threshold ≤ r < the second change rate threshold, the ultrasonic intermittent defrosting mode is turned on, and the defrosting is paused for 2 minutes every 2 minutes;

[0019] In the third change rate interval, the second change rate threshold ≤ r < the third change rate threshold, the ultrasonic intermittent defrosting mode is turned on, and the defrosting is paused for 1 minute every 2 minutes;

[0020] In the fourth change rate interval, the third change rate threshold ≤ r < the fourth change rate threshold, the ultrasonic intermittent defrosting mode is turned on, and the defrosting is paused for 1 minute every 3 minutes;

[0021] In the fifth change rate interval, r ≥ the fourth change rate threshold, the ultrasonic continuous defrosting mode is turned on.

[0022] Furthermore, the PWM average value of the DC fan speed in the current period is obtained by:

[0023] SA1 monitors the current DC fan speed F i t Wind speed F t :

[0024] If the wind speed F t In gear position wind speed F i t Within the allowed fluctuation range, that is, F∈(F i ±ΔF i ), and this condition continues for a second period of time t2, executing step SA2;

[0025] If it is other cases, continue to monitor the wind speed F t ;

[0026] SA2 collects the PWM value of the DC fan for a period of time at a certain collection frequency, and calculates the average PWM value of the DC fan collected PWM average value satisfy:

[0027]

[0028] In the formula, j represents the sampling number, and n represents the total number of samples.

[0029] Furthermore, the PWM reference average value is obtained by:

[0030] After the defrost cycle is over, monitor the current DC fan speed F i t Wind speed F t :

[0031] If the wind speed F t In gear position wind speed Fi t Within the allowed fluctuation range, that is, F∈(F i ±ΔF i ), and this condition continues for a second period of time t2;

[0032] Collect the PWM value of the DC fan for a period of time at a certain collection frequency, and calculate the average PWM value of the DC fan collected PWM average value satisfy:

[0033]

[0034] In the formula, j represents the sampling number, and n represents the total number of samples;

[0035] The PWM average value Set the wind speed F for the next defrost cycle i The PWM reference average value

[0036]

[0037] Furthermore, after the ultrasonic intermittent defrosting mode is turned on, the following logic control is also included:

[0038] Get the defrost run time of an ultrasonic generator or the coil temperature of a system air-side heat exchanger:

[0039] If the defrost operation time is greater than or equal to the defrost operation time threshold, or the coil temperature is greater than or equal to the defrost exit temperature threshold, the ultrasonic defrost mode is exited and the ultrasonic generator is turned off.

[0040] Furthermore, before obtaining the continuous heating operation time and the accumulated heating operation time of the system at the current moment, the following logical judgment is also included:

[0041] Get the system power-on status:

[0042] If it is the first time to power on, get the current ambient temperature of the system If the ambient temperature Lower than the set ambient temperature defrost threshold Then obtain the system's current continuous heating operation time and cumulative heating operation time;

[0043] If it is not the first power-on, the continuous heating operation time and the cumulative heating operation time of the system at the current moment are obtained.

[0044] Compared with the prior art, the heat pump system provided by the present invention determines whether the system needs to start ultrasonic defrosting by the PWM difference between the heating operation time, the PWM average value of the DC fan gear wind speed and the PWM reference value; and according to the correlation between the change rate of the PWM difference of the DC fan and the system frosting rate and frosting thickness, a defrosting method of intermittent ultrasonic loading based on a time mechanism is provided, which uses power ultrasonic waves to generate low-amplitude, high-frequency, and high-acceleration vibrations applied to the evaporator surface to defrost or inhibit frosting. The specific intermittent cycle and the time for applying ultrasonic waves are controlled according to the change rate of the PWM difference, so as to achieve more accurate, efficient and reliable defrosting, meet the user's comfort requirements for heating and cooling, and have good energy-saving and consumption-reducing effects; at the same time, the ultrasonic generator can be reasonably activated to avoid problems such as decreased power output efficiency and damage caused by long-term use.

[0045] For better understanding and implementation, the present invention is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 A schematic diagram of the system structure of an embodiment of the present invention;

[0047] Figure 2 is a flow chart of a control method according to an embodiment of the present invention;

[0048] Figure 3 The figure is a flow chart of defrost entry judgment and defrost control according to an embodiment of the present invention. DETAILED DESCRIPTION

[0049] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention.

[0050] In order to solve the problems that the ultrasonic generator is turned on for a long time to defrost, or the defrosting is not timely, or the defrosting is not complete, etc. when the existing heat pump system adopts ultrasonic defrosting, the present invention proposes a heat pump system with ultrasonic defrosting control based on wind sensing, which includes an ultrasonic defrosting control method based on wind sensing. The control method accurately judges the frosting situation of the system by monitoring the change rate of the PWM signal value feedback from the DC fan according to the correlation between the change rate of the DC fan feedback PWM signal value and the frosting rate and frosting thickness of the system, and controls the start of the ultrasonic generator according to the frosting situation, and activates the intermittent defrosting working mode. The control method can use ultrasonic waves for precise defrosting, achieve effective frost suppression and defrosting effects, meet the user's heating and cooling comfort requirements, have good energy-saving and consumption-reducing effects, and can reasonably activate the ultrasonic generator at the same time to avoid problems such as power output efficiency reduction and damage caused by long-term use.

[0051] For specific implementation, please refer to Figure 1The heat pump system with ultrasonic defrosting control based on wind sensing proposed by the present invention comprises a compressor 10, a four-way valve 20, a water-side heat exchanger 30, an electronic expansion valve 40, an air-side heat exchanger 50, and a DC fan 60 arranged on one side of the air-side heat exchanger 50, and an ultrasonic generator 70 arranged on the other side of the air-side heat exchanger 50, and a temperature detection module 80, and a controller (not shown), and other auxiliary pipes. The controller is electrically connected or communicatively connected with the compressor 10, the DC fan 60, the ultrasonic generator 70 and the temperature detection module 80.

[0052] The temperature detection module 80 includes a first temperature sensor 81 and a second temperature sensor 82. The first temperature sensor 81 is disposed on the outer coil of the air side heat exchanger 50, and is used to collect the temperature signal of the coil and convert the coil temperature into a value. The second temperature sensor 82 is used to collect the ambient temperature. And the ambient temperature The second temperature sensor 82 can be arranged on the outside of the air-side heat exchanger 50 or on the casing of the heat pump system, which is not limited in the present application.

[0053] The controller receives the PWM value of the DC fan 60 and the temperature signal collected by the temperature detection module 80, and judges the defrosting of the system according to the stored calculation and judgment program, and controls the ultrasonic generator 70 to enter the defrosting control.

[0054] For details, please refer to Figure 2 The wind-sensing-based ultrasonic defrosting control method of the present invention includes the following steps.

[0055] (I) Determination of defrosting entry conditions

[0056] S10 obtains the system power-on status:

[0057] If it is the first time to power on, execute step S20;

[0058] If it is not the first power-on, step S30 is executed.

[0059] S20 obtains the current ambient temperature of the system Continuous heating operation time Cumulative heating operation time

[0060] If the ambient temperature Lower than the set ambient temperature defrost threshold Continuous heating operation time Greater than the set continuous heating time threshold And the cumulative heating operation time Greater than the set first defrost interval time threshold Then execute step S40;

[0061] If it is other cases, continue to monitor the ambient temperature at the next moment Continuous heating operation time Cumulative heating operation time

[0062] In specific implementation, the ambient temperature defrost threshold The setting range is 6°C to 8°C, preferably 7°C.

[0063] The continuous heating time threshold The setting range is 5min to 180min, which is set according to the ambient temperature of the system operating conditions, and 45min is preferred.

[0064] The first defrost interval time threshold The setting range is 20min to 30min, preferably 25min.

[0065] S30 obtains the system's current continuous heating operation time Cumulative heating operation time

[0066] If continuous heating operation time Greater than the set continuous heating time threshold And the cumulative heating operation time Greater than the set second defrost interval time threshold Then execute step S40;

[0067] If it is other cases, continue to monitor the continuous heating operation time at the next moment Cumulative heating operation time

[0068] In a specific implementation, the second defrosting interval time threshold The setting range is 40min to 50min, preferably 45min.

[0069] S40 obtains the DC fan speed F in the current period i t The average value of PWM Calculate PWM average value With PWM reference average PWM difference ΔPWM t :

[0070] If the PWM difference ΔPWM t Greater than or equal to the PWM difference threshold ΔPWM TD, then enter the wind-sensing defrost control mode and execute step S50;

[0071] If it is other cases, after the first time period t1 (1min), the wind speed F of the DC fan gear in the next time period is continuously obtained. i t+1 The average value of PWM

[0072] In specific implementation, the PWM difference ΔPWM t satisfy:

[0073]

[0074] In the formula, i represents the i-th wind speed level. For example, a DC fan has 9 wind speed levels (F 1 ,F 2 ,...,F 9 ), then i∈(1,9).

[0075] The DC fan gear wind speed F in the current period i t The average value of PWM Obtained through:

[0076] SA1 monitors the current DC fan speed F i t Wind speed F t :

[0077] If the wind speed F t In gear position wind speed F i t Within the allowed fluctuation range, that is, F∈(F i ±ΔF i ), and this condition lasts for a second time period t2, it is considered that the DC fan is running stably, and step SA2 is executed;

[0078] If it is other cases, continue to monitor the wind speed F t .

[0079] SA2 collects the PWM value of the DC fan for a period of time at a certain collection frequency, and calculates the average PWM value of the DC fan collected PWM average value satisfy:

[0080]

[0081] In the formula, j represents the sampling number, and n represents the total number of samples.

[0082] Specifically, the acquisition frequency is 60 times / min; the acquisition time is 1 min. Fluctuation value ΔF iFor example, the wind speed fluctuation range corresponding to the gear wind speed of 720RPM is between 710RPM and 730RPM.

[0083] The second time period t2 is 50s to 60s.

[0084] The PWM reference average value Obtained through:

[0085] After the defrost cycle is over, monitor the current DC fan speed F i t Wind speed F t :

[0086] If the wind speed F t In gear position wind speed F i t Within the allowed fluctuation range, that is, F∈(F i ±ΔF i ), and this condition continues for a second period of time t2;

[0087] Collect the PWM value of the DC fan for a period of time at a certain collection frequency, and calculate the average PWM value of the DC fan collected PWM average value satisfy:

[0088]

[0089] In the formula, j represents the sampling number, and n represents the total number of samples;

[0090] The PWM average value Set the wind speed F for the next defrost cycle i The PWM reference average value

[0091]

[0092] That is to say, the DC fan speed F in the current defrost cycle is i t The average value of PWM The difference calculation is the DC fan speed F at the end of the defrost cycle. i The average value of PWM

[0093] The PWM difference threshold ΔPWM TD The setting range is 490 to 510, preferably 500.

[0094] (II) Ultrasonic defrosting control

[0095] S50 calculates the DC fan PWM difference ΔPWM in the current periodt The change rate r is used to control the ultrasonic generator to start the intermittent defrosting or continuous defrosting mode according to the change rate interval to which the change rate r belongs, where the change rate r satisfies:

[0096]

[0097] Where: ΔPWM t-1 Indicates the DC fan PWM difference in the previous period.

[0098] In specific implementation, according to the correlation between the change rate r of the PWM difference ΔPWM and the system frosting rate and frosting thickness, the change rate r is divided into 5 levels, and different ultrasonic defrosting modes are set according to each level:

[0099] Specifically:

[0100] In the first change rate range, 0≤r<10, the ultrasonic intermittent defrosting mode is turned on, and the defrosting is paused for 2 minutes every 1 minute;

[0101] In the second change rate range, 10≤r<20, the ultrasonic intermittent defrosting mode is turned on, and the defrosting is paused for 2 minutes every 2 minutes;

[0102] In the third change rate range, 20≤r<30, the ultrasonic intermittent defrosting mode is turned on, and the defrosting is paused for 1 minute every 2 minutes;

[0103] In the fourth change rate range, 30≤r<40, the ultrasonic intermittent defrosting mode is turned on, and the defrosting is paused for 1 minute every 3 minutes;

[0104] In the fifth change rate range, r≥40, the ultrasonic continuous defrosting mode is turned on.

[0105] (III) Defrost Exit

[0106] S60 obtains the defrost operation time of the ultrasonic generator or the coil temperature of the air side heat exchanger of the system

[0107] If the defrost operation time is greater than or equal to the defrost operation time threshold, or the coil temperature Greater than or equal to the defrost exit temperature threshold Exit ultrasonic defrost mode and turn off the ultrasonic generator.

[0108] In a specific implementation, the defrosting operation time threshold is set in a range of 7 minutes to 9 minutes, preferably 8 minutes.

[0109] The defrost exit temperature threshold The setting range is 24-26°C, preferably 25°C.

[0110] S70 collects the PWM value of the DC fan for a period of time at a certain collection frequency, and calculates the average PWM value of the collected DC fan The PWM average value Set as the PWM reference average value for the next defrost cycle

[0111] Compared with the prior art, the wind-sensing-based heat pump system with ultrasonic defrost control mode of the present invention determines whether the system needs to start ultrasonic defrosting by the PWM difference between the heating operation time, the PWM average value of the DC fan gear wind speed and the PWM reference value; and based on the correlation between the change rate of the PWM difference of the DC fan and the system frosting rate and frosting thickness; the ultrasonic defrost working mode is performed using the change rate of the PWM difference; more accurate, efficient and reliable defrosting is achieved, meeting the user's comfort requirements for heating and cooling, and having good energy-saving and consumption-reducing effects; at the same time, the ultrasonic generator can be reasonably activated to avoid problems such as decreased power output efficiency and damage caused by long-term use.

[0112] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the embodiments of the present application. The singular forms of "a", "said" and "the" used in the embodiments of the present application and the claims are also intended to include plural forms, unless the context clearly indicates other meanings. It should also be understood that, unless otherwise specified, "multiple" and "several" refer to two or more; "and / or" refers to and includes any or all possible combinations of one or more associated listed items; "first", "second", "third", etc. are only used to distinguish, rather than to describe a specific order or sequence, and cannot be understood as indicating or implying relative importance. When the above description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. In the description of the present application, for those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0113] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, and the present invention is also intended to include these modifications and modifications.

Claims

1. A heat pump system with ultrasonic defrost control based on wind sensing, comprising a compressor, a four-way valve, a water-side heat exchanger, an electronic expansion valve, an air-side heat exchanger, and a DC fan arranged on one side of the air-side heat exchanger, and an ultrasonic generator arranged on the other side of the air-side heat exchanger, and a temperature detection module, and a controller electrically connected and / or communicatively connected to the compressor, the DC fan, the ultrasonic generator, and the temperature detection module, characterized in that: The controller controls the defrost of the heat pump system in the following ways: Get the system's current continuous heating operation time and cumulative heating operation time: If the continuous heating operation time is greater than the set continuous heating time threshold, and the accumulated heating operation time is greater than the set second defrosting interval time threshold; Then obtain the PWM average value of the DC fan gear speed in the current period, and calculate the PWM difference between the PWM average value and the PWM benchmark average value; If the PWM difference is greater than or equal to the PWM difference threshold, the wind-sensing defrost control mode is entered; the change rate r of the DC fan PWM difference in the current period is calculated, and the ultrasonic generator is controlled to start the intermittent defrost or continuous defrost mode according to the change rate interval to which the change rate r belongs, where the change rate r satisfies: Where: ΔPWM t Indicates the DC fan PWM difference in the current period, ΔPWM t-1 Indicates the DC fan PWM difference in the previous period.

2. The heat pump system according to claim 1, characterized in that: The PWM difference satisfies: Where: ΔPWM represents the PWM difference, Indicates the wind speed F of the DC fan in the i-th gear in the current period i The average value of PWM, Indicates the wind speed F of the DC fan at the i-th gear measured after the last defrost cycle. i The PWM average value.

3. The heat pump system according to claim 2, characterized in that: The change rate range and its corresponding ultrasonic defrosting mode are: In the first change rate interval, 0≤r<the first change rate threshold, the ultrasonic intermittent defrosting mode is turned on, and the defrosting is paused for 2 minutes every 1 minute; In the second change rate interval, the first change rate threshold ≤ r < the second change rate threshold, the ultrasonic intermittent defrosting mode is turned on, and the defrosting is paused for 2 minutes every 2 minutes; In the third change rate interval, the second change rate threshold ≤ r < the third change rate threshold, the ultrasonic intermittent defrosting mode is turned on, and the defrosting is paused for 1 minute every 2 minutes; In the fourth change rate interval, the third change rate threshold ≤ r < the fourth change rate threshold, the ultrasonic intermittent defrosting mode is turned on, and the defrosting is paused for 1 minute every 3 minutes; In the fifth change rate interval, r ≥ the fourth change rate threshold, the ultrasonic continuous defrosting mode is turned on.

4. The heat pump system according to claim 3, characterized in that: The first change rate threshold is 10; the second change rate threshold is 20; the third change rate threshold is 30; and the fourth change rate threshold is 40.

5. The heat pump system according to any one of claims 2 to 4, characterized in that: The PWM average value of the DC fan speed in the current period is obtained by: SA1 monitors the current DC fan speed F i t Wind speed F t : If the wind speed F t In gear position wind speed F i t Within the allowed fluctuation range, that is, F∈(F i ±ΔF i ), and this condition continues for a second period of time t2, executing step SA2; If it is other cases, continue to monitor the wind speed F t ; SA2 collects the PWM value of the DC fan for a period of time at a certain collection frequency, and calculates the average PWM value of the DC fan collected PWM average value satisfy: In the formula, j represents the sampling number, and n represents the total number of samples.

6. The heat pump system according to claim 5, characterized in that: The acquisition frequency is 60 times / min; the acquisition time is 1min, and the fluctuation value ΔF i is 10RPM.

7. The heat pump system according to any one of claims 2, 3, 4 and 6, characterized in that: The PWM reference average value is obtained by: After the defrost cycle is over, monitor the current DC fan speed F i t Wind speed F t : If the wind speed F t In gear position wind speed F i t Within the allowed fluctuation range, that is, F∈(F i ±ΔF i ), and this condition continues for a second period of time t2; Collect the PWM value of the DC fan for a period of time at a certain collection frequency, and calculate the average PWM value of the DC fan collected PWM average value satisfy: In the formula, j represents the sampling number, and n represents the total number of samples; The PWM average value Set the wind speed F for the next defrost cycle i The PWM reference average value 8. The heat pump system according to claim 6, characterized in that: The PWM difference threshold ΔPWM TD The setting range is 490 to 510.

9. The heat pump system according to any one of claims 1, 2, 3, 4, 6 and 8, characterized in that: After the ultrasonic intermittent defrost mode is turned on, the following logic controls are also included: Get the defrost run time of an ultrasonic generator or the coil temperature of a system air-side heat exchanger: If the defrost operation time is greater than or equal to the defrost operation time threshold, or the coil temperature is greater than or equal to the defrost exit temperature threshold, the ultrasonic defrost mode is exited and the ultrasonic generator is turned off.

10. The heat pump system according to claim 9, characterized in that: Before obtaining the system's current continuous heating operation time and cumulative heating operation time, the following logical judgment is also required: Get the system power-on status: If it is the first time to power on, get the current ambient temperature of the system If the ambient temperature Lower than the set ambient temperature defrost threshold Then obtain the system's current continuous heating operation time and cumulative heating operation time; If it is not the first power-on, the continuous heating operation time and the cumulative heating operation time of the system at the current moment are obtained.

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