Defrosting control method based on evaporation temperature change rate and heat pump system

Abstract

The invention relates to a defrosting control method based on the evaporation temperature change rate and a heat pump system. The control method comprises the steps that the evaporation temperature drop rate is calculated, and the situation that the evaporation temperature drop rate is larger than the set evaporation temperature drop rate is counted; calculating the temperature difference between the environment temperature and the evaporation temperature, counting the cumulative duration of the temperature difference belonging to different driving temperature difference sections, and calculating the time ratio, and if the evaporation temperature drop rate is greater than the set evaporation temperature drop rate for three continuous times and the sum of the time ratios corresponding to the cumulative duration of each driving temperature difference section is greater than or equal to 1, determining that the temperature difference is greater than the set evaporation temperature drop rate; if yes, the heat pump system is controlled to defrost, and the four-way valve is controlled to reverse. Whether the air side heat exchanger of the heat pump system is frosted or not is jointly judged in the mode, so that defrosting is more accurate, and the problems that when the heat pump system is controlled to be defrosted through the evaporation temperature and the defrosting interval time in the prior art, frost cannot be removed, defrosting is conducted without frost, the energy efficiency is reduced, and the heat use experience of a user is reduced are effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of heat pump control, and in particular to a defrosting control method based on evaporation temperature change rate and a heat pump system. Background Art

[0002] A heat pump system is a highly efficient and environmentally friendly energy utilization technology. Its core operating principle is the reverse Carnot cycle. By consuming a small amount of electricity or other energy, it transfers heat energy from a low-temperature heat source to a high-temperature environment, achieving heating or cooling. Air-source heat pump systems, as a type of heat pump system, absorb low-temperature heat energy from the air using minimal electricity, compress it into high-temperature heat energy, and then transfer it to the location requiring heating or cooling. They are highly favored by consumers and users, and are widely used for cooling and hot water supply in hotels, schools, hospitals, saunas, beauty salons, swimming pools, laundries, and other places.

[0003] Currently, defrost control for heat pump units primarily relies on two conditions to determine whether to control the unit to enter defrost: first, the operating time of the heat pump unit in its current operating state reaches the set defrost time; and second, the difference between the heat pump unit's evaporating temperature (or external coil temperature) and the ambient temperature reaches the set difference value, ΔT. When these two defrost conditions are met, the heat pump unit enters defrost.

[0004] However, in actual use, firstly, there is an error in the conversion of the evaporation pressure of the heat pump unit into the evaporation temperature, and the related errors also vary depending on the configuration of the heat pump unit, the refrigerant, etc., which may result in some heat pump units not frosting at the same evaporation temperature, while other heat pump units are frosted; secondly, the opening of the electronic expansion valve is unreasonable, and when the evaporation temperature is low, the set defrost time has been reached, but the heat pump unit has not frosted but enters defrost mode, resulting in frost-free defrosting that wastes capacity and reduces energy efficiency. Summary of the Invention

[0005] Based on this, the purpose of the present invention is to provide a defrost control method based on the evaporation temperature change rate to solve the problems of frost not being removed, defrosting without frost, reduced energy efficiency, and reduced user heating experience in the heat pump system under the defrost control based on the evaporation temperature and the set defrost interval time.

[0006] A defrost control method based on evaporation temperature change rate includes the following steps: S1: obtaining the current ambient temperature within the current defrost interval period Current evaporation temperature

[0007] S2A: Calculate the current evaporation temperature Evaporation temperature at the previous moment The evaporation temperature drop rate R is greater than the set evaporation temperature drop rate R during the current defrost interval. set situation;

[0008] S2B: Calculate the current ambient temperature and the current evaporation temperature Temperature difference Statistical temperature difference Belong to different driving temperature difference ΔT 驱动 The cumulative duration of each segment and the calculation of the driving temperature difference ΔT 驱动 The time ratio of the cumulative duration of the segment to the set cumulative duration;

[0009] S3: If the evaporation temperature drop rate R is greater than the set evaporation temperature drop rate R for three consecutive times set And each driving temperature difference ΔT 驱动 If the sum of the time ratios of the accumulated duration of the segment and the set accumulated duration is greater than or equal to 1, the heat pump system is controlled to enter defrosting and the four-way valve is controlled to reverse.

[0010] Furthermore, step S2B includes the following sub-steps:

[0011] S2B1: Calculate the current ambient temperature and the current evaporation temperature Temperature difference

[0012]

[0013] S2B2: Statistical temperature difference Greater than or equal to the first set driving temperature difference The first cumulative duration And calculate the first driving temperature difference time ratio α:

[0014]

[0015] Indicates the first set driving temperature difference The corresponding first setting cumulative duration;

[0016] S2B3: Statistical temperature difference Greater than or equal to the second set driving temperature difference And is less than the first set driving temperature difference The second cumulative duration And calculate the second driving temperature difference time ratio β:

[0017]

[0018] Indicates the second set driving temperature difference The corresponding second setting cumulative duration;

[0019] S2B4: Statistical temperature difference Greater than or equal to the third set driving temperature difference And less than the second set driving temperature difference The third cumulative duration And calculate the third driving temperature difference time ratio γ:

[0020]

[0021] Indicates the third set driving temperature difference The corresponding third setting cumulative duration;

[0022]

[0023] Furthermore, the step S2A includes the following sub-steps:

[0024] S2A1: Get the current evaporation temperature within the current defrost interval Evaporation temperature at the previous moment

[0025] S2A2: Calculate the evaporation temperature drop rate R at the current moment t :

[0026]

[0027] S2A3: Determine the current evaporation temperature drop rate R t Is it greater than the set evaporation temperature drop rate R? set :

[0028] If yes, then record the current evaporation temperature drop rate R t , and count 1 time;

[0029] If not, continue to monitor the evaporation temperature drop rate R at the next moment t+1 .

[0030] Furthermore, the current evaporation temperature Obtained through:

[0031] SA1 obtains the current low pressure According to the current low pressure Check the refrigerant saturation temperature

[0032] SA2 obtains the current refrigerant outlet temperature Calculate the refrigerant outlet temperature at the current moment and refrigerant saturation temperature The difference between the two values ​​is used to get the actual superheat at the current moment.

[0033] in,

[0034] SA3 obtains the current coil temperature and the set target superheat According to the current coil temperature Actual superheat at the current moment Target superheat Calculate the evaporation temperature at the current moment

[0035] in,

[0036] Furthermore, the method further comprises step S4:

[0037] Get the defrost time t 除霜 and / or coil temperature If any of the following conditions is met, the heat pump system will be controlled to exit defrosting and the four-way valve will be controlled to switch direction:

[0038] Coil temperature Greater than or equal to the set defrost end temperature T P ;

[0039] Defrost time t 除霜 Greater than or equal to the set maximum defrost time

[0040] Compared with the existing technology, the defrost control method based on the evaporation temperature change rate proposed in the present invention determines whether frost is formed on the air-side heat exchanger of the heat pump system through the change of the evaporation temperature drop rate combined with the cumulative duration of the temperature difference between the evaporation temperature and the ambient temperature, making defrosting more accurate and effectively solving the problems of frost not being removed, defrosting without frost, reduced energy efficiency and reduced user heating experience when controlling the defrost of the heat pump system by the evaporation temperature and the defrost interval time.

[0041] At the same time, the present invention also provides a heat pump system.

[0042] A heat pump system comprises: a compressor, a four-way valve, a water-side heat exchanger, an electronic expansion valve, an air-side heat exchanger, and a sensor module connected in sequence through a refrigerant circulation pipeline; and a controller electrically and / or communicatively connected to the four-way valve and the sensor module, the controller comprising: a temperature acquisition unit, an evaporation temperature drop rate statistics unit, a temperature difference cumulative duration statistics unit, and a defrost entry control unit; wherein:

[0043] Temperature acquisition unit, used to obtain the current ambient temperature within the current defrost interval Current evaporation temperature

[0044] Evaporation temperature drop rate statistics unit, used to calculate the current evaporation temperature Evaporation temperature at the previous moment The evaporation temperature drop rate R is greater than the set evaporation temperature drop rate R during the current defrost interval. set situation;

[0045] Temperature difference cumulative duration statistics unit, used to calculate the current ambient temperature and the current evaporation temperature Temperature difference Statistical temperature difference Belong to different driving temperature difference ΔT 驱动 The cumulative duration of each segment and the calculation of the driving temperature difference ΔT 驱动 The time ratio of the cumulative duration of the segment to the set cumulative duration;

[0046] Enter the defrost control unit, if the evaporation temperature drop rate R is greater than the set evaporation temperature drop rate R for three consecutive times set And each driving temperature difference ΔT 驱动 If the sum of the time ratios of the accumulated duration of the segment and the set accumulated duration is greater than or equal to 1, the heat pump system is controlled to enter defrosting and the four-way valve is controlled to reverse.

[0047] Furthermore, the temperature difference cumulative duration statistics unit includes: a temperature difference calculation subunit, a first driving temperature difference time ratio calculation subunit, a second driving temperature difference time ratio calculation subunit, and a third driving temperature difference time ratio calculation subunit, wherein:

[0048] Temperature difference calculation subunit, used to calculate the current ambient temperature and the current evaporation temperature Temperature difference

[0049] The first driving temperature difference time ratio calculation subunit is used to calculate the temperature difference Greater than or equal to the first set driving temperature difference The first cumulative duration And calculate the first driving temperature difference time ratio α:

[0050]

[0051] Indicates the first set driving temperature difference The corresponding first setting cumulative duration;

[0052] The second driving temperature difference time ratio calculation subunit is used to calculate the temperature difference Greater than or equal to the second set driving temperature difference And is less than the first set driving temperature difference The second cumulative duration And calculate the second driving temperature difference time ratio β:

[0053]

[0054] Indicates the second set driving temperature difference The corresponding second setting cumulative duration;

[0055] The third driving temperature difference time ratio calculation subunit is used to calculate the temperature difference Greater than or equal to the third set driving temperature difference And less than the second set driving temperature difference The third cumulative duration And calculate the third driving temperature difference time ratio γ:

[0056]

[0057] Indicates the third set driving temperature difference The corresponding third setting cumulative duration;

[0058]

[0059] Furthermore, the evaporation temperature drop rate statistics unit includes: an evaporation temperature acquisition subunit, an evaporation temperature drop rate calculation subunit, and a subunit for counting the number of times the evaporation temperature drop rate exceeds the set value, wherein:

[0060] The evaporation temperature acquisition subunit is used to obtain the current evaporation temperature within the current defrost interval. Evaporation temperature at the previous moment

[0061] The evaporation temperature drop rate calculation subunit is used to calculate the evaporation temperature drop rate R at the current moment t :

[0062]

[0063] The sub-unit for counting the number of times the set evaporation temperature drop rate is exceeded is used to determine the current evaporation temperature drop rate R t Is it greater than the set evaporation temperature drop rate R? set :

[0064] If yes, then record the current evaporation temperature drop rate R t , and count 1 time;

[0065] If not, continue to monitor the evaporation temperature drop rate R at the next moment t+1 .

[0066] Furthermore, it also includes:

[0067] Exit the defrost control unit to obtain the defrost time t 除霜 and / or coil temperature If any of the following conditions are met, the heat pump system will be controlled to exit defrosting and the four-way valve will be controlled to switch direction:

[0068] Coil temperature Greater than or equal to the set defrost end temperature T P ;

[0069] Defrost time t 除霜 Greater than or equal to the set maximum defrost time

[0070] The beneficial effects of the heat pump system proposed in the present invention are the same as those of the above-mentioned defrost control method based on the evaporation temperature change rate, and will not be described in detail here.

[0071] For better understanding and implementation, the present invention is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 A schematic diagram of the system structure of an embodiment of the present invention;

[0073] Figure 2 A schematic diagram of the controller structure according to an embodiment of the present invention;

[0074] Figure 3 Flowchart of a defrost control method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0075] 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.

[0076] In order to solve the problem that the existing heat pump system cannot accurately judge whether the heat pump system is frosted under the defrost control based on the evaporating temperature and the set defrost time, and the situation of not removing frost when there is frost or defrosting without frost occurs, which further leads to reduced energy efficiency of the heat pump system, the present invention proposes a defrost control method based on the evaporating temperature change rate. The control method improves the accuracy of judging whether the heat pump system is frosted, realizes the efficient operation of the heat pump system with defrost when there is frost and not defrost when there is no frost, and improves the energy efficiency of the heat pump system.

[0077] For specific implementation, please refer to Figure 1 and Figure 2 The heat pump system proposed in the present invention includes 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, a sensor module 60, a controller 70, and other auxiliary pipes, which are connected in a refrigerant pipeline loop. The controller 70 is electrically and / or communicatively connected to the electronic expansion valve 40 and the sensor module 60.

[0078] The sensor module 60 includes a first temperature sensor 61 , a second temperature sensor 62 , a third temperature sensor 63 and a first pressure sensor 64 .

[0079] The first temperature sensor 61 is used to collect the ambient temperature of the environment where the heat pump system is located. And the measured ambient temperature Transmitted to the controller, the setting location of which is not limited in this application.

[0080] The second temperature sensor 62 is provided at the outlet of one end of the air side heat exchanger 50, which is connected to the return air port of the compressor 10; it is used to collect the refrigerant outlet temperature. And the measured refrigerant outlet temperature Transmitted to the controller.

[0081] The third temperature sensor 63 is located in the middle of the outer coil of the air side heat exchanger 50 and is used to collect the coil temperature. The measured coil temperature Transmitted to the controller.

[0082] The first pressure sensor 64 is installed on the refrigerant pipeline connecting the air side heat exchanger 50 and the compressor 10, and is close to the straight pipe section of the return air port of the compressor 10, and is used to collect the low pressure of the refrigerant. And the measured low pressure Transmitted to the controller.

[0083] The controller 70 includes a temperature acquisition unit 100 , an evaporation temperature drop rate statistics unit 200 , a temperature difference cumulative duration statistics unit 300 , enters a defrost control unit 400 , and exits a defrost control unit 500 .

[0084] Specifically, the temperature acquisition unit 100 is used to execute step S1: obtain the current ambient temperature within the current defrost interval period Current evaporation temperature

[0085] In specific implementation, the evaporation temperature at the current moment Obtained through:

[0086] SA1 obtains the current low pressure According to the current low pressure Check the refrigerant saturation temperature

[0087] SA2 obtains the current refrigerant outlet temperature Calculate the refrigerant outlet temperature at the current moment and refrigerant saturation temperature The difference between the two values ​​is used to get the actual superheat at the current moment.

[0088] in,

[0089] SA3 obtains the current coil temperature and the set target superheat According to the current coil temperature Actual superheat at the current moment Target superheat Calculate the evaporation temperature at the current moment

[0090] in,

[0091] In some embodiments, the current low pressure The refrigerant saturation temperature is checked As the current evaporation temperature

[0092] In some embodiments, the current coil temperature is obtained Subtract the heat transfer temperature difference ΔT to get the current evaporation temperature

[0093]

[0094] Among them, the heat transfer temperature difference ΔT is an empirical value. If the coil temperature at the current moment is When the temperature is greater than the dew point temperature, ΔT is 2°C to 3°C. If the current coil temperature is less than or equal to the dew point temperature and greater than or equal to 0°C, ΔT is 4°C to 5°C. If the current coil temperature is less than 0°C, ΔT is 6°C to 8°C.

[0095] The evaporation temperature drop rate statistics unit 200 is used to execute step S2A: calculate the current evaporation temperature Evaporation temperature at the previous moment The evaporation temperature drop rate R is greater than the set evaporation temperature drop rate R during the current defrost interval. set situation.

[0096] Specifically, the evaporation temperature drop rate statistics unit 200 includes an evaporation temperature acquisition subunit, an evaporation temperature drop rate calculation subunit, and a subunit for counting the number of times the evaporation temperature drop rate exceeds the set value.

[0097] The evaporation temperature acquisition subunit is used to execute step S2A1: obtain the current coil temperature within the current defrost interval period. Coil temperature at the previous moment

[0098] The evaporation temperature drop rate calculation subunit is used to execute step S2A2: calculate the evaporation temperature drop rate R at the current moment t :

[0099]

[0100] The subunit for counting the number of times the set evaporation temperature drop rate is exceeded is used to execute step S2A3: determine the current evaporation temperature drop rate R t Is it greater than the set evaporation temperature drop rate R? set :

[0101] If yes, then record the current evaporation temperature drop rate R t , and count 1 time;

[0102] If not, continue to monitor the evaporation temperature drop rate R at the next moment t+1 .

[0103] The temperature difference cumulative duration statistics unit 300 is used to execute step S2B: calculate the current ambient temperature and the current evaporation temperature Temperature difference Statistical temperature difference Belong to different driving temperature difference ΔT 驱动 The cumulative duration of each segment and the calculation of the driving temperature difference ΔT 驱动 The time ratio of the accumulated duration of the segment to the set accumulated duration.

[0104] The temperature difference cumulative duration statistics unit 300 includes: a temperature difference calculation subunit, a first driving temperature difference time ratio calculation subunit, a second driving temperature difference time ratio calculation subunit and a third driving temperature difference time ratio calculation subunit.

[0105] in,

[0106] The temperature difference calculation subunit is used to execute step S2B1: calculate the current ambient temperature and the current evaporation temperature Temperature difference

[0107]

[0108] The first driving temperature difference time ratio calculation subunit is used to execute step S2B2: Counting the temperature difference Greater than or equal to the first set driving temperature difference The first cumulative duration And calculate the first driving temperature difference time ratio α:

[0109]

[0110] Indicates the first set driving temperature difference The corresponding first setting cumulative duration.

[0111] The second driving temperature difference time ratio calculation subunit is used to execute step S2B3: Statistical temperature difference Greater than or equal to the second set driving temperature difference And is less than the first set driving temperature difference The second cumulative duration And calculate the second driving temperature difference time ratio β:

[0112]

[0113] Indicates the second set driving temperature difference The corresponding second setting cumulative duration.

[0114] The third driving temperature difference time ratio calculation subunit is used to execute step S2B4: Counting the temperature difference Greater than or equal to the third set driving temperature difference And less than the second set driving temperature difference The third cumulative duration And calculate the third driving temperature difference time ratio γ:

[0115]

[0116] Indicates the third set driving temperature difference The corresponding third setting accumulates the duration.

[0117] in,

[0118] The driving temperature difference refers to the difference between the heat source temperature and the evaporation temperature of the heat pump system. The set driving temperature difference is the driving temperature difference point set by the heat pump system. For example, the first set driving temperature difference is set to The second setting driving temperature difference is 10℃ The third setting driving temperature difference is 8℃ is 4℃.

[0119] Enter the defrost control unit 400 to execute step S3: If the evaporation temperature drop rate R is greater than the set evaporation temperature drop rate R for three consecutive times set And each driving temperature difference ΔT 驱动 If the sum of the time ratios of the accumulated duration of the segment and the set accumulated duration is greater than or equal to 1, the heat pump system is controlled to enter defrosting and the four-way valve is controlled to reverse.

[0120] That is, α+β+γ≥1.

[0121] Exit the defrost control unit 500 to execute step S4: obtain the defrost time t 除霜 and / or coil temperature If any of the following conditions are met, the heat pump system will be controlled to exit defrosting and the four-way valve will be controlled to switch direction:

[0122] Coil temperature Greater than or equal to the set defrost end temperature T P ;

[0123] Defrost time t 除霜 Greater than or equal to the set maximum defrost time

[0124] In specific implementation, the defrost end temperature T P The value range is 8~16℃, the maximum defrost time The value range is 5 to 12 minutes.

[0125] In a specific implementation, the controller is an electronic device, which includes but is not limited to: a memory, a processor, and a network interface that can be communicatively connected to each other via a system bus.

[0126] The memory includes at least one type of readable storage medium, and the readable storage medium includes a flash memory, a hard disk, a multimedia card, a card-type memory (e.g., SD or DX memory), a random access memory (RAM), a static random access memory (SRAM), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), a programmable read-only memory (PROM), a magnetic memory, a magnetic disk, an optical disk, etc. The memory can be an internal storage unit of the electronic device, such as a hard disk or memory of the electronic device. The memory can also be an external storage device of the electronic device, such as a plug-in hard disk equipped on the electronic device, a smart memory card (SMC), a secure digital (SD) card, a flash card, etc. The memory can also include both an internal storage unit of the electronic device and its external storage device.

[0127] The processor may be a central processing unit (CPU), a microprocessor, or other data processing chip. The processor is typically used to control the overall operation of the electronic device, such as performing control and processing related to data interaction or communication with the electronic device. The processor is used to execute program code stored in the memory or process data, such as executing the defrost control method based on the evaporation temperature change rate.

[0128] The network interface may include a wireless network interface or a wired network interface, which is generally used to establish a communication connection between the electronic device and other electronic devices. For example, the network interface is used to connect the electronic device to an external data platform via a network, and to establish a data transmission channel and a communication connection between the electronic device and the external data platform. The network may be a wireless or wired network such as an intranet, the Internet, a global system of mobile communications (GSM), wideband code division multiple access (WCDMA), a 4G network, a 5G network, Bluetooth, or Wi-Fi.

[0129] 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" and the like are only used to distinguish, and are not used to describe a specific order or sequence, nor can they be understood as indicating or implying relative importance. When the above description refers 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.

[0130] The above-described embodiments merely represent several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous modifications and improvements without departing from the spirit of the present invention, and the present invention is intended to encompass such modifications and variations.

Claims

1. A defrost control method based on evaporation temperature change rate, characterized in that: include: S1: Get the current ambient temperature within the current defrost interval Current evaporation temperature S2A: Calculate the current evaporation temperature Evaporation temperature at the previous moment The evaporation temperature drop rate R is greater than the set evaporation temperature drop rate R during the current defrost interval. set situation; S2B: Calculate the current ambient temperature and the current evaporation temperature Temperature difference Statistical temperature difference Belong to different driving temperature difference ΔT 驱动 The cumulative duration of each segment and the calculation of the driving temperature difference ΔT 驱动 The time ratio of the cumulative duration of the segment to the set cumulative duration; S3: If the evaporation temperature drop rate R is greater than the set evaporation temperature drop rate R for three consecutive times set And each driving temperature difference ΔT 驱动 If the sum of the time ratios of the accumulated duration of the segment and the set accumulated duration is greater than or equal to 1, the heat pump system is controlled to enter defrosting and the four-way valve is controlled to reverse.

2. The defrosting control method based on the evaporation temperature change rate according to claim 1, characterized in that: The step S2B includes the following sub-steps: S2B1: Calculate the current ambient temperature and the current evaporation temperature Temperature difference S2B2: Statistical temperature difference Greater than or equal to the first set driving temperature difference The first cumulative duration And calculate the first driving temperature difference time ratio α: Indicates the first set driving temperature difference The corresponding first setting cumulative duration; S2B3: Statistical temperature difference Greater than or equal to the second set driving temperature difference And is less than the first set driving temperature difference The second cumulative duration And calculate the second driving temperature difference time ratio β: Indicates the second set driving temperature difference The corresponding second setting cumulative duration; S2B4: Statistical temperature difference Greater than or equal to the third set driving temperature difference And less than the second set driving temperature difference The third cumulative duration And calculate the third driving temperature difference time ratio γ: Indicates the third set driving temperature difference The corresponding third setting cumulative duration; First set driving temperature difference > Second setting driving temperature difference >The third setting driving temperature difference First setting cumulative duration >Second setting cumulative duration >The third setting is the cumulative duration.

3. The defrosting control method based on the evaporation temperature change rate according to claim 2, characterized in that: The step S2A includes the following sub-steps: S2A1: Get the current evaporation temperature within the current defrost interval Evaporation temperature at the previous moment S2A2: Calculate the evaporation temperature drop rate R at the current moment t : S2A3: Determine the current evaporation temperature drop rate R t Is it greater than the set evaporation temperature drop rate R? set : If yes, then record the current evaporation temperature drop rate R t , and count 1 time; If not, continue to monitor the evaporation temperature drop rate R at the next moment t+1 .

4. The defrosting control method based on the evaporation temperature change rate according to claim 1, characterized in that: The current evaporation temperature Obtained through: SA1 obtains the current low pressure According to the current low pressure Check the refrigerant saturation temperature SA2 obtains the current refrigerant outlet temperature Calculate the refrigerant outlet temperature at the current moment and refrigerant saturation temperature The difference between the two values ​​is used to get the actual superheat at the current moment. in, SA3 obtains the current coil temperature and the set target superheat According to the current coil temperature Actual superheat at the current moment Target superheat Calculate the evaporation temperature at the current moment in, 5. The defrosting control method based on the evaporation temperature change rate according to any one of claims 1 to 4, characterized in that: Also includes step S4: Get the defrost time t 除霜 and / or coil temperature If any of the following conditions is met, the heat pump system will be controlled to exit defrosting and the four-way valve will be controlled to switch direction: Coil temperature Greater than or equal to the set defrost end temperature T P ; Defrost time t 除霜 Greater than or equal to the set maximum defrost time 6. A heat pump system comprising: A compressor, a four-way valve, a water-side heat exchanger, an electronic expansion valve, an air-side heat exchanger, and a sensor module are sequentially connected through a refrigerant circulation pipeline, and a controller electrically and / or communicatively connected to the four-way valve and the sensor module, characterized in that the controller includes: a temperature acquisition unit, an evaporation temperature drop rate statistics unit, a temperature difference cumulative duration statistics unit, and a defrost entry control unit; wherein: Temperature acquisition unit, used to obtain the current ambient temperature within the current defrost interval Current evaporation temperature Evaporation temperature drop rate statistics unit, used to calculate the current evaporation temperature Evaporation temperature at the previous moment The evaporation temperature drop rate R is greater than the set evaporation temperature drop rate R during the current defrost interval. set situation; Temperature difference cumulative duration statistics unit, used to calculate the current ambient temperature and the current evaporation temperature Temperature difference Statistical temperature difference Belong to different driving temperature difference ΔT 驱动 The cumulative duration of each segment and the calculation of the driving temperature difference ΔT 驱动 The time ratio of the cumulative duration of the segment to the set cumulative duration; Enter the defrost control unit, if the evaporation temperature drop rate R is greater than the set evaporation temperature drop rate R for three consecutive times set And each driving temperature difference ΔT 驱动 If the sum of the time ratios of the accumulated duration of the segment and the set accumulated duration is greater than or equal to 1, the heat pump system is controlled to enter defrosting and the four-way valve is controlled to reverse.

7. The heat pump system according to claim 6, characterized in that The temperature difference cumulative duration statistics unit includes: a temperature difference calculation subunit, a first driving temperature difference time ratio calculation subunit, a second driving temperature difference time ratio calculation subunit, and a third driving temperature difference time ratio calculation subunit, wherein: Temperature difference calculation subunit, used to calculate the current ambient temperature and the current evaporation temperature Temperature difference The first driving temperature difference time ratio calculation subunit is used to calculate the temperature difference Greater than or equal to the first set driving temperature difference The first cumulative duration And calculate the first driving temperature difference time ratio α: Indicates the first set driving temperature difference The corresponding first setting cumulative duration; The second driving temperature difference time ratio calculation subunit is used to calculate the temperature difference Greater than or equal to the second set driving temperature difference And is less than the first set driving temperature difference The second cumulative duration And calculate the second driving temperature difference time ratio β: Indicates the second set driving temperature difference The corresponding second setting cumulative duration; The third driving temperature difference time ratio calculation subunit is used to calculate the temperature difference Greater than or equal to the third set driving temperature difference And less than the second set driving temperature difference The third cumulative duration And calculate the third driving temperature difference time ratio γ: Indicates the third set driving temperature difference The corresponding third setting cumulative duration; First set driving temperature difference > Second setting driving temperature difference >The third setting driving temperature difference First setting cumulative duration >Second setting cumulative duration >The third setting is the cumulative duration.

8. The heat pump system according to claim 7, characterized in that The evaporation temperature drop rate statistics unit includes: an evaporation temperature acquisition subunit, an evaporation temperature drop rate calculation subunit, and a subunit for counting the number of times the evaporation temperature drop rate exceeds the set value, wherein: The evaporation temperature acquisition subunit is used to obtain the current evaporation temperature within the current defrost interval. Evaporation temperature at the previous moment The evaporation temperature drop rate calculation subunit is used to calculate the evaporation temperature drop rate R at the current moment t : The sub-unit for counting the number of times the set evaporation temperature drop rate is exceeded is used to determine the current evaporation temperature drop rate R t Is it greater than the set evaporation temperature drop rate R? set : If yes, then record the current evaporation temperature drop rate R t , and count 1 time; If not, continue to monitor the evaporation temperature drop rate R at the next moment t+1 .

9. The heat pump system according to claim 6, characterized in that The current evaporation temperature in the temperature acquisition unit Obtained through: SA1 obtains the current low pressure According to the current low pressure Check the refrigerant saturation temperature SA2 obtains the current refrigerant outlet temperature Calculate the refrigerant outlet temperature at the current moment and refrigerant saturation temperature The difference between the two values ​​is used to get the actual superheat at the current moment. in, SA3 obtains the current coil temperature and the set target superheat According to the current coil temperature Actual superheat at the current moment Target superheat Calculate the evaporation temperature at the current moment in, 10. The heat pump system according to claim 6, characterized in that Also includes: Exit the defrost control unit to obtain the defrost time t 除霜 and / or coil temperature If any of the following conditions are met, the heat pump system will be controlled to exit defrosting and the four-way valve will be controlled to switch direction: Coil temperature Greater than or equal to the set defrost end temperature T P ; Defrost time t 除霜 Greater than or equal to the set maximum defrost time

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