A control method, device, air conditioning system and storage medium of an air conditioning system

Abstract

The present invention discloses a control method, device, air conditioning system and storage medium for an air conditioning system. The method includes: when the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger is less than a set pressure difference threshold, and the water side inlet temperature change rate of the plate heat exchanger is greater than a set temperature change threshold, determining whether there is an internal leakage in the plate heat exchanger according to at least one of the frequency type of the water pump, the frequency type of the compressor, the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger, the water side inlet temperature change rate and the ambient temperature; and, when it is determined that there is an internal leakage in the plate heat exchanger, sending a reminder message indicating that there is an internal leakage in the plate heat exchanger. With this solution, by identifying the state of the plate heat exchanger and taking corresponding measures in advance, it is possible to avoid affecting the heat exchange effect of the plate heat exchanger or even damaging the compressor due to internal leakage of the plate heat exchanger, and ensure the normal operation of the air conditioning system.

Description

Technical Field

[0001] The present invention belongs to the technical field of air conditioning systems, and particularly relates to a control method, device, air conditioning system and storage medium for an air conditioning system, and more particularly to a control method, device, air conditioning system and storage medium for preventing leakage of a plate heat exchanger in an air conditioning system. Background Art

[0002] An air conditioning system has a heat exchanger and a compressor, and a plate heat exchanger can be used as the heat exchanger in the air conditioning system. The plate heat exchanger has plates, and the thickness of the plates of the plate heat exchanger is extremely thin. For example, the thickness of the plates of the plate heat exchanger is generally 0.25 mm to 0.3 mm. However, due to the extremely thin thickness of the plates, the plate heat exchanger is extremely likely to leak under the impact of the refrigerant for a long time. When there is an internal leak in the plate heat exchanger, the refrigerant inside the plate heat exchanger will be mixed with water, affecting the heat exchange effect of the plate heat exchanger; in severe cases, some of the mixture of the refrigerant and water will enter the compressor, causing the compressor to experience a liquid slugging phenomenon, thereby damaging the compressor and causing the air conditioning system to fail to work properly.

[0003] The above content is only used to assist in understanding the technical solution of the present invention, and does not represent an admission that the above content is prior art. Summary of the Invention

[0004] The object of the present invention is to provide a control method, device, air conditioning system and storage medium for an air conditioning system, so as to solve the problem that the plate heat exchanger in the air conditioning system is extremely likely to leak under the impact of the refrigerant for a long time, and when there is an internal leak in the plate heat exchanger, the refrigerant will be mixed with water, affecting the heat exchange effect of the plate heat exchanger, and in severe cases, it will also cause liquid accumulation in the compressor and damage the compressor, resulting in the failure of the air conditioning system to work properly, and achieve the effect of identifying the state of the plate heat exchanger and taking corresponding measures in advance to avoid affecting the heat exchange effect of the plate heat exchanger or even damaging the compressor due to an internal leak in the plate heat exchanger, and ensuring the normal operation of the air conditioning system.

[0005] In a control method of an air conditioning system provided by the present invention, the air conditioning system includes a compressor, an outdoor heat exchanger, and an indoor heat exchanger; the indoor heat exchanger is a plate heat exchanger, and the plate heat exchanger has a refrigerant heat exchange pipeline and a water heat exchange pipeline, and heat exchange can be carried out between the refrigerant heat exchange pipeline and the water heat exchange pipeline; the compressor, the outdoor heat exchanger, and the refrigerant heat exchange pipeline form a refrigerant heat exchange loop through a refrigerant circulation pipeline; the water heat exchange pipeline, together with a water pump, a water tank, and a heat-using device arranged in the space where the air conditioning system is located, forms a water heat exchange loop through a water circulation pipeline; the control method of the air conditioning system includes: when the air conditioning system is started and running, obtaining the pressure difference between the inlet and outlet of the refrigerant heat exchange pipeline in the plate heat exchanger, denoted as the refrigerant-side pressure difference of the plate heat exchanger; obtaining the pressure difference between the inlet and outlet of the water heat exchange pipeline in the plate heat exchanger, denoted as the water-side pressure difference of the plate heat exchanger; obtaining the change rate of the inlet water temperature of the water heat exchange pipeline in the plate heat exchanger, denoted as the water-side inlet water temperature change rate of the plate heat exchanger; and obtaining the ambient temperature of the air conditioning system; when the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is less than a set pressure difference threshold, and the water-side inlet water temperature change rate of the plate heat exchanger is greater than a set temperature change threshold, determining whether there is a leak inside the plate heat exchanger according to at least one of the frequency type of the water pump, the frequency type of the compressor, the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger, the water-side inlet water temperature change rate of the plate heat exchanger, and the ambient temperature of the air conditioning system; and, when it is determined that there is a leak inside the plate heat exchanger, sending a reminder message that there is a leak inside the plate heat exchanger.

[0006] In some embodiments, determining whether there is a leak inside the plate heat exchanger according to at least one of the frequency type of the water pump, the frequency type of the compressor, the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger, the water-side inlet water temperature change rate of the plate heat exchanger, and the ambient temperature of the air conditioning system includes: when the water pump is a constant-frequency water pump and the compressor is a constant-frequency compressor, when the water pump operates at its own fixed frequency, as the operation time of the air conditioning system progresses, if the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold, the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger gradually approaches 0, and the water-side inlet water temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, it is determined that there is a leak inside the plate heat exchanger.

[0007] In some embodiments, based on at least one of the frequency type of the water pump, the frequency type of the compressor, the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger, the water-side inlet temperature change rate of the plate heat exchanger, and the ambient temperature of the air-conditioning system, it is determined whether there is a leak inside the plate heat exchanger. It further includes: when the water pump is a constant-frequency water pump and the compressor is a constant-frequency compressor, as the operation time of the air-conditioning system progresses, if the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold and the water-side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, it is determined whether the operating frequency of the compressor is greater than the first set frequency and less than or equal to the maximum set frequency; if it is determined that the operating frequency of the compressor is greater than the first set frequency and less than or equal to the maximum set frequency, based on the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger, it is determined whether there is a leak inside the plate heat exchanger.

[0008] In some embodiments, based on at least one of the frequency type of the water pump, the frequency type of the compressor, the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger, the water-side inlet temperature change rate of the plate heat exchanger, and the ambient temperature of the air conditioning system, it is determined whether there is a leak inside the plate heat exchanger. It further includes: when the water pump is a variable-frequency water pump and the compressor is a fixed-frequency compressor, as the operation time of the air conditioning system progresses, if the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold and the water-side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, then according to the ambient temperature range in which the ambient temperature of the air conditioning system is located, the operating frequency of the water pump is controlled to be fixed at the fixed frequency value corresponding to this ambient temperature range to obtain the current operating frequency of the water pump; wherein, the ambient temperature range in which the ambient temperature of the air conditioning system is located includes any one of the first ambient temperature range, the second ambient temperature range, and the third ambient temperature range; the first ambient temperature range corresponds to the first set fixed frequency value, the second ambient temperature range corresponds to the second set fixed frequency value, and the third ambient temperature range corresponds to the third set fixed frequency value; controlling the water pump to operate at the current operating frequency of the water pump. As the operation time of the air conditioning system progresses, if the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold, the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger gradually approaches 0, and the water-side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, then it is determined that there is a leak inside the plate heat exchanger.

[0009] In some embodiments, based on at least one of the frequency type of the water pump and the frequency type of the compressor, in combination with the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger, the water side inlet temperature change rate of the plate heat exchanger, and the ambient temperature of the air conditioning system, it is determined whether there is a leak inside the plate heat exchanger, and it further includes: when the water pump is a variable frequency water pump and the compressor is a fixed frequency compressor, as the operation time of the air conditioning system progresses, if the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold and the water side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, then according to the ambient temperature range in which the ambient temperature of the air conditioning system is located, the operating frequency of the water pump is controlled to be fixed at the fixed frequency value corresponding to this ambient temperature range to obtain the current operating frequency of the water pump; wherein, the ambient temperature range in which the ambient temperature of the air conditioning system is located includes any one of the first ambient temperature range, the second ambient temperature range, and the third ambient temperature range; the first ambient temperature range corresponds to the first set fixed frequency value, the second ambient temperature range corresponds to the second set fixed frequency value, and the third ambient temperature range corresponds to the third set fixed frequency value; controlling the water pump to operate at the current operating frequency of the water pump; when the water pump operates at the current operating frequency of the water pump, it is determined whether there is a leak inside the plate heat exchanger according to the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger.

[0010] In some embodiments, determining whether there is a leak inside the plate heat exchanger according to the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger includes: controlling the operating frequency of the compressor to increase by a set frequency corresponding to the pressure range based on the current frequency of the compressor according to the pressure range in which the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is located, to obtain the first current frequency of the compressor; wherein, the pressure range in which the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is located includes any one of a first pressure range, a second pressure range, and a third pressure range; the first pressure range corresponds to a first set frequency by which the operating frequency of the compressor needs to be increased, the second pressure range corresponds to a second set frequency by which the operating frequency of the compressor needs to be increased, and the third pressure range corresponds to a third set frequency by which the operating frequency of the compressor needs to be increased; controlling the compressor to operate at the first current frequency of the compressor; and after the compressor operates at the first current frequency of the compressor for a first set time, determining the change rate of the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger within the first set time, denoted as the pressure difference change rate of the plate heat exchanger; and determining whether there is a leak inside the plate heat exchanger according to the pressure difference change rate of the plate heat exchanger.

[0011] In some embodiments, determining whether there is a leak inside the plate heat exchanger according to the pressure difference change rate of the plate heat exchanger includes: controlling the operating frequency of the compressor to decrease by a set frequency corresponding to the pressure change range based on the first current frequency of the compressor according to the pressure change range in which the pressure difference change rate of the plate heat exchanger is located, to obtain the second current frequency of the compressor; wherein, the pressure change range in which the pressure difference change rate of the plate heat exchanger is located includes any one of a first pressure change range, a second pressure change range, and a third pressure change range; the first pressure change range corresponds to a fourth set frequency by which the operating frequency of the compressor needs to be decreased, the second pressure change range corresponds to a fifth set frequency by which the operating frequency of the compressor needs to be decreased, and the third pressure change range corresponds to a sixth set frequency by which the operating frequency of the compressor needs to be decreased; controlling the compressor to operate at the second current frequency of the compressor; and after the compressor operates at the second current frequency of the compressor for a second set time, if the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is still less than a set pressure difference threshold and the change rate of the water-side inlet temperature of the plate heat exchanger is still greater than a set temperature change threshold, it is determined that there is a leak inside the plate heat exchanger.

[0012] Matched with the above method, on the other hand, the present invention provides a control device for an air-conditioning system. The air-conditioning system has a compressor, an outdoor heat exchanger, and an indoor heat exchanger; the indoor heat exchanger is a plate heat exchanger, and the plate heat exchanger has a refrigerant heat exchange pipeline and a water heat exchange pipeline, and heat exchange can be carried out between the refrigerant heat exchange pipeline and the water heat exchange pipeline; the compressor, the outdoor heat exchanger, and the refrigerant heat exchange pipeline form a refrigerant heat exchange loop through a refrigerant circulation pipeline; the water heat exchange pipeline, together with a water pump, a water tank, and a heat-using device arranged in the space where the air-conditioning system is located, forms a water heat exchange loop through a water circulation pipeline; the control device of the air-conditioning system includes: an acquisition unit configured to, when the air-conditioning system is started and running, acquire the inlet and outlet pressure difference of the refrigerant heat exchange pipeline in the plate heat exchanger, denoted as the refrigerant-side pressure difference of the plate heat exchanger; acquire the inlet and outlet pressure difference of the water heat exchange pipeline in the plate heat exchanger, denoted as the water-side pressure difference of the plate heat exchanger; acquire the change rate of the inlet water temperature of the water heat exchange pipeline in the plate heat exchanger, denoted as the change rate of the water-side inlet water temperature of the plate heat exchanger; and acquire the ambient temperature of the air-conditioning system; a control unit configured to, when the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is less than a set pressure difference threshold, and the change rate of the water-side inlet water temperature of the plate heat exchanger is greater than a set temperature change threshold, determine whether there is a leak inside the plate heat exchanger according to at least one of the frequency type of the water pump, the frequency type of the compressor, the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger, the change rate of the water-side inlet water temperature of the plate heat exchanger, and the ambient temperature of the air-conditioning system; and, when it is determined that there is a leak inside the plate heat exchanger, send a reminder message that there is a leak inside the plate heat exchanger.

[0013] In some embodiments, the control unit determines whether there is a leak inside the plate heat exchanger according to at least one of the frequency type of the water pump, the frequency type of the compressor, the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger, the change rate of the water-side inlet water temperature of the plate heat exchanger, and the ambient temperature of the air-conditioning system, including: when the water pump is a fixed-frequency water pump and the compressor is a fixed-frequency compressor, when the water pump operates at its own fixed frequency, as the running time of the air-conditioning system progresses, if the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold, the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger gradually approaches 0, and the change rate of the water-side inlet water temperature of the plate heat exchanger is still greater than the set temperature change threshold, it is determined that there is a leak inside the plate heat exchanger.

[0014] In some embodiments, the control unit determines whether there is a leak inside the plate heat exchanger according to at least one of the frequency type of the water pump, the frequency type of the compressor, the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger, the water side inlet temperature change rate of the plate heat exchanger, and the ambient temperature of the air conditioning system. It further includes: when the water pump is a constant frequency water pump and the compressor is a constant frequency compressor, as the operation time of the air conditioning system progresses, if the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold and the water side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, it is determined whether the operating frequency of the compressor is greater than the first set frequency and less than or equal to the maximum set frequency; if it is determined that the operating frequency of the compressor is greater than the first set frequency and less than or equal to the maximum set frequency, it is determined whether there is a leak inside the plate heat exchanger according to the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger.

[0015] In some embodiments, the control unit determines whether there is a leak inside the plate heat exchanger based on at least one of the frequency type of the water pump, the frequency type of the compressor, the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger, the water-side inlet temperature change rate of the plate heat exchanger, and the ambient temperature of the air-conditioning system. It further includes: when the water pump is a variable-frequency water pump and the compressor is a fixed-frequency compressor, as the operation time of the air-conditioning system progresses, if the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold and the water-side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, then according to the ambient temperature range in which the ambient temperature of the air-conditioning system is located, control the operating frequency of the water pump to be fixed at the fixed frequency value corresponding to this ambient temperature range to obtain the current operating frequency of the water pump; wherein, the ambient temperature range in which the ambient temperature of the air-conditioning system is located includes any one of the first ambient temperature range, the second ambient temperature range, and the third ambient temperature range; the first ambient temperature range corresponds to a first set fixed frequency value, the second ambient temperature range corresponds to a second set fixed frequency value, and the third ambient temperature range corresponds to a third set fixed frequency value; control the water pump to operate at the current operating frequency of the water pump. As the operation time of the air-conditioning system progresses, if the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold, the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger gradually approaches 0, and the water-side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, then determine that there is a leak inside the plate heat exchanger.

[0016] In some embodiments, the control unit determines whether there is a leak inside the plate heat exchanger based on at least one of the frequency type of the water pump, the frequency type of the compressor, the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger, the water side inlet temperature change rate of the plate heat exchanger, and the ambient temperature of the air conditioning system. It further includes: when the water pump is a variable frequency water pump and the compressor is a fixed frequency compressor, as the operation time of the air conditioning system progresses, if the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold and the water side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, then according to the ambient temperature range in which the ambient temperature of the air conditioning system is located, the operation frequency of the water pump is controlled to be fixed at the fixed frequency value corresponding to this ambient temperature range to obtain the current operation frequency of the water pump; wherein, the ambient temperature range in which the ambient temperature of the air conditioning system is located includes any one of the first ambient temperature range, the second ambient temperature range, and the third ambient temperature range; the first ambient temperature range corresponds to the first set fixed frequency value, the second ambient temperature range corresponds to the second set fixed frequency value, and the third ambient temperature range corresponds to the third set fixed frequency value; control the water pump to operate at the current operation frequency of the water pump; when the water pump operates at the current operation frequency of the water pump, determine whether there is a leak inside the plate heat exchanger according to the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger.

[0017] In some embodiments, the control unit determines whether there is a leakage inside the plate heat exchanger according to the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger, including: controlling the operating frequency of the compressor to increase by a set frequency corresponding to the pressure range based on the current frequency of the compressor according to the pressure range where the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is located, to obtain the first current frequency of the compressor; wherein, the pressure range where the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is located includes any one of a first pressure range, a second pressure range, and a third pressure range; the first pressure range corresponds to a first set frequency by which the operating frequency of the compressor needs to be increased, the second pressure range corresponds to a second set frequency by which the operating frequency of the compressor needs to be increased, and the third pressure range corresponds to a third set frequency by which the operating frequency of the compressor needs to be increased; controlling the compressor to operate at the first current frequency of the compressor; and after the compressor operates at the first current frequency of the compressor for a first set time, determining the change rate of the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger within the first set time, which is denoted as the pressure difference change rate of the plate heat exchanger; and determining whether there is a leakage inside the plate heat exchanger according to the pressure difference change rate of the plate heat exchanger.

[0018] In some embodiments, the control unit determines whether there is a leakage inside the plate heat exchanger according to the pressure difference change rate of the plate heat exchanger, including: controlling the operating frequency of the compressor to decrease by a set frequency corresponding to the pressure change range based on the first current frequency of the compressor according to the pressure change range where the pressure difference change rate of the plate heat exchanger is located, to obtain the second current frequency of the compressor; wherein, the pressure change range where the pressure difference change rate of the plate heat exchanger is located includes any one of a first pressure change range, a second pressure change range, and a third pressure change range; the first pressure change range corresponds to a fourth set frequency by which the operating frequency of the compressor needs to be decreased, the second pressure change range corresponds to a fifth set frequency by which the operating frequency of the compressor needs to be decreased, and the third pressure change range corresponds to a sixth set frequency by which the operating frequency of the compressor needs to be decreased; controlling the compressor to operate at the second current frequency of the compressor; and after the compressor operates at the second current frequency of the compressor for a second set time, if the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is still less than a set pressure difference threshold and the change rate of the water-side inlet temperature of the plate heat exchanger is still greater than a set temperature change threshold, it is determined that there is a leakage inside the plate heat exchanger.

[0019] Matched with the above device, on another aspect, the present invention provides an air conditioning system, including: the control device of the above-described air conditioning system.

[0020] Matched with the above method, on another aspect, the present invention provides a storage medium, the storage medium including a stored program, wherein when the program runs, it controls the device where the storage medium is located to execute the control method of the above-described air conditioning system.

[0021] Thus, in the solution of the present invention, by detecting the refrigerant-side pressure difference ΔPr of the plate heat exchanger, the water-side pressure difference ΔPw of the plate heat exchanger, and the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger, when it is detected that the difference between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger is less than the pressure difference β under normal working conditions, and the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger is greater than the change rate Tс under normal conditions, according to whether the water pump is a fixed-frequency water pump or a variable-frequency water pump, and whether the compressor is a fixed-frequency compressor or a variable-frequency compressor, the leakage situation inside the plate heat exchanger is determined. If it is determined that there is a leakage inside the plate heat exchanger, a reminder message (such as an alarm) is sent. If it is determined that there is no leakage inside the plate heat exchanger, the frequency of the compressor is adjusted to avoid the occurrence of leakage inside the plate heat exchanger or further improve the confirmation accuracy of the leakage situation inside the plate heat exchanger. Thus, by identifying the state of the plate heat exchanger and taking corresponding measures in advance, it is possible to avoid the influence on the heat exchange effect of the plate heat exchanger or even damage to the compressor due to serious internal leakage of the plate heat exchanger, and ensure the normal operation of the air conditioning system.

[0022] Other features and advantages of the present invention will be described in the subsequent description, and, in part, will be obvious from the description or understood by implementing the present invention.

[0023] The technical solution of the present invention will be further described in detail below with reference to the drawings and embodiments. Description of the Drawings

[0024] Figure 1 It is a schematic flowchart of an embodiment of the control method of the air conditioning system of the present invention;

[0025] Figure 2 It is a schematic flowchart of an embodiment of determining whether there is a leakage inside the plate heat exchanger when the water pump is a fixed-frequency water pump and the compressor is a variable-frequency compressor in the method of the present invention;

[0026] Figure 3 It is a schematic flowchart of an embodiment of determining whether there is a leakage inside the plate heat exchanger when the water pump is a variable-frequency water pump and the compressor is a fixed-frequency compressor in the method of the present invention;

[0027] Figure 4 Schematic flow chart of an embodiment for determining whether there is a leak inside a plate heat exchanger when the water pump in the method of the present invention is a variable-frequency water pump and the compressor is a variable-frequency compressor;

[0028] Figure 5 Schematic flow chart of an embodiment for determining whether there is a leak inside the plate heat exchanger according to the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger in the method of the present invention;

[0029] Figure 6 Schematic flow chart of an embodiment for determining whether there is a leak inside the plate heat exchanger according to the pressure difference change rate of the plate heat exchanger in the method of the present invention;

[0030] Figure 7 Schematic structural diagram of an embodiment of the control device of the air-conditioning system of the present invention;

[0031] Figure 8 Schematic structural diagram of an embodiment of an air-conditioning system;

[0032] Figure 9 Schematic flow chart of an embodiment of the leak prevention control method for a plate heat exchanger in an air-conditioning system.

[0033] In combination with the accompanying drawings, the reference numerals in the embodiments of the present invention are as follows:

[0034] 102 - acquisition unit; 104 - control unit. Detailed implementation manners

[0035] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0036] Considering that the plate heat exchanger in the air conditioning system is extremely prone to leakage under the stamping of the refrigerant for a long time. When there is an internal leakage in the plate heat exchanger, the refrigerant will be mixed with water, affecting the heat exchange effect of the plate heat exchanger. In severe cases, liquid accumulation may occur in the compressor, damaging the compressor and causing the air conditioning system to malfunction. The solution of the present invention proposes a control method for an air conditioning system, specifically a control method for preventing leakage of the plate heat exchanger in the air conditioning system. By timely identifying the state of the plate heat exchanger and taking corresponding measures in advance, it is possible to avoid leakage of the plate heat exchanger under the stamping of the refrigerant for a long time, thereby avoiding the influence on the heat exchange effect of the plate heat exchanger due to internal leakage of the plate heat exchanger, and also avoiding damage to the compressor caused by liquid accumulation in the compressor due to severe internal leakage of the plate heat exchanger, thus avoiding damage to the air conditioning system and being beneficial to extending the service life of the air conditioning system.

[0037] According to an embodiment of the present invention, there is provided a control method for an air conditioning system, as Figure 1 shown in the flowchart of an embodiment of the method of the present invention. The air conditioning system has a compressor, an outdoor heat exchanger, and an indoor heat exchanger; the indoor heat exchanger is a plate heat exchanger, and the plate heat exchanger has a refrigerant heat exchange pipeline and a water heat exchange pipeline, and heat exchange can occur between the refrigerant heat exchange pipeline and the water heat exchange pipeline; the compressor, the outdoor heat exchanger, and the refrigerant heat exchange pipeline form a refrigerant heat exchange loop through a refrigerant circulation pipeline. For example: one port of the compressor is connected to the other port of the compressor after passing through the outdoor heat exchanger and the refrigerant heat exchange pipeline. The water heat exchange pipeline forms a water heat exchange loop with a water pump, a water tank, and a heat-using device arranged in the space where the air conditioning system is located through a water circulation pipeline. For example: one end of the water heat exchange pipeline is connected to the other end of the water heat exchange pipeline after passing through the water pump, the water tank, and the heat-using device arranged in the space where the air conditioning system is located. Specifically, Figure 8 is a schematic structural diagram of an embodiment of the air conditioning system. As Figure 8 shown, the air conditioning system includes: a compressor, an outdoor heat exchanger, an indoor heat exchanger, a throttle valve, water-using devices such as a floor heating system, a water tank, and a water pump. The indoor heat exchanger uses a plate heat exchanger, and the plate heat exchanger has a refrigerant heat exchange pipeline on the refrigerant side and a water heat exchange pipeline on the water side. Among them, one port of the compressor is connected to the other port of the compressor after passing through the first port of the refrigerant heat exchange pipeline of the plate heat exchanger, the second port of the refrigerant heat exchange pipeline of the plate heat exchanger, the throttle valve, and the outdoor heat exchanger. One port of the water heat exchange pipeline of the plate heat exchanger is connected to the other port of the water heat exchange pipeline of the plate heat exchanger after passing through water-using devices such as a floor heating system, the water tank, the first port of the water pump, and the second port of the water pump.

[0038] See Figure 8In the example shown, a pressure sensor P is provided on the pipeline where the first port of the refrigerant heat exchange pipeline of the plate heat exchanger is located. A temperature sensor T is provided on the pipeline where the second port of the refrigerant heat exchange pipeline of the plate heat exchanger is located. A temperature sensor T is provided on the pipeline where the second port of the water pump is located. A differential pressure sensor ΔP is installed on the pipeline where the inlet and outlet of the water heat exchange pipeline of the plate heat exchanger are located. The control method of the air-conditioning system includes: step S110 to step S120.

[0039] At step S110, when the air-conditioning system is started and running, obtain the differential pressure between the inlet and outlet of the refrigerant heat exchange pipeline in the plate heat exchanger, denoted as the refrigerant side differential pressure of the plate heat exchanger, that is, the differential pressure ΔPr on the refrigerant side of the plate heat exchanger. Obtain the differential pressure between the inlet and outlet of the water heat exchange pipeline in the plate heat exchanger, denoted as the water side differential pressure of the plate heat exchanger, that is, the differential pressure ΔPw on the water side of the plate heat exchanger. Obtain the change rate of the inlet water temperature of the water heat exchange pipeline in the plate heat exchanger, denoted as the change rate of the inlet water temperature on the water side of the plate heat exchanger, that is, the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger. And obtain the ambient temperature of the air-conditioning system, such as sampling the ambient temperature of the air-conditioning system using an ambient temperature sensor to obtain the ambient temperature of the air-conditioning system.

[0040] Specifically, Figure 9 is a schematic flow chart of an embodiment of the anti-leakage control method for a plate heat exchanger in an air-conditioning system. As Figure 9 shown, the anti-leakage control method for a plate heat exchanger in an air-conditioning system includes: Step 1, obtain the differential pressure between the inlet of the refrigerant heat exchange pipeline of the plate heat exchanger and the outlet of the refrigerant heat exchange pipeline of the plate heat exchanger, denoted as the refrigerant side differential pressure ΔPr of the plate heat exchanger. Obtain the differential pressure between the inlet and outlet of the water heat exchange pipeline of the plate heat exchanger, denoted as the water side differential pressure ΔPw of the plate heat exchanger. And obtain the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger (that is, the change rate ΔT_w_in / Δt of the inlet water temperature of the water heat exchange pipeline of the plate heat exchanger), where ΔT_w_in is the change amount of the inlet water temperature of the water heat exchange pipeline of the plate heat exchanger within the time Δt.

[0041] Among them, obtaining the pressure difference between the inlet and outlet of the refrigerant heat exchange pipeline in the plate heat exchanger, which is denoted as the refrigerant side pressure difference of the plate heat exchanger, includes: If the air-conditioning system operates in the heating mode, the pressure at the inlet and outlet of the refrigerant heat exchange pipeline in the plate heat exchanger is sampled to obtain the pressure difference between the inlet and outlet of the refrigerant heat exchange pipeline in the plate heat exchanger, which is denoted as the refrigerant side pressure difference of the plate heat exchanger. If the air-conditioning system operates in the cooling mode, the temperature at the inlet and outlet of the refrigerant heat exchange pipeline in the plate heat exchanger is sampled, and the pressure difference between the inlet and outlet of the refrigerant heat exchange pipeline in the plate heat exchanger is calculated to be denoted as the refrigerant side pressure difference of the plate heat exchanger.

[0042] Since in the heating mode of the air-conditioning system, the indoor heat exchanger such as the plate heat exchanger is used as a condenser, and the outdoor heat exchanger is used as an evaporator. In the cooling mode of the air-conditioning system, the indoor heat exchanger such as the plate heat exchanger is used as an evaporator, and the outdoor heat exchanger is used as a condenser. Therefore, referring to Figure 8 the example shown, when the plate heat exchanger is used as a condenser in the heating mode, a pressure sensor P is installed at the front end of the plate heat exchanger (such as the pipeline where the first port of the refrigerant heat exchange pipeline of the plate heat exchanger is located), and the pressure of the first port of the refrigerant heat exchange pipeline of the plate heat exchanger can be detected. Since the plate heat exchanger is used as an evaporator in the cooling mode, and the inlet of the evaporator is a two-phase region, a temperature sensor T needs to be installed at the pipeline where the second port of the refrigerant heat exchange pipeline of the plate heat exchanger is located to indirectly calculate the pressure of the second port of the refrigerant heat exchange pipeline of the plate heat exchanger. Thus, based on the pressure of the first port of the refrigerant heat exchange pipeline of the plate heat exchanger and the pressure of the second port of the refrigerant heat exchange pipeline of the plate heat exchanger, the pressure difference between the pressure of the first port of the refrigerant heat exchange pipeline of the plate heat exchanger and the pressure of the second port of the refrigerant heat exchange pipeline of the plate heat exchanger is calculated as the pressure difference between the inlet and the outlet of the refrigerant heat exchange pipeline of the plate heat exchanger, which is denoted as the refrigerant side pressure difference ΔPr of the plate heat exchanger. Among them, when the plate heat exchanger is used as a condenser, the inlet refrigerant state of the plate heat exchanger is gaseous, and the pressure sensor can detect the pressure at this inlet; the outlet refrigerant state of the plate heat exchanger is subcooled, and the pressure sensor can detect the pressure at this outlet. Considering the cooling mode, when the plate heat exchanger is used as an evaporator, the refrigerant state is two-phase; the inlet refrigerant state of the evaporator is a gas-liquid mixture, collectively referred to as the two-phase region; when the plate heat exchanger is used as an evaporator, the inlet refrigerant state of the plate heat exchanger is a gas-liquid mixture, and the pressure sensor cannot accurately detect it. The temperature sensor can be used to detect the temperature at the inlet of the plate heat exchanger to indirectly calculate the pressure at the inlet of the plate heat exchanger. The outlet refrigerant state of the plate heat exchanger is generally superheated, and the pressure sensor can be used to detect the outlet pressure, and the difference between the two is the pressure difference.

[0043] Similarly, obtain the pressure difference between the inlet and outlet of the water heat exchange pipeline of the plate heat exchanger, which is denoted as the water side pressure difference of the plate heat exchanger. Specifically, it can be: Refer to Figure 8 the example shown. Install a differential pressure sensor ΔP at the inlet and outlet of the water side heat exchange pipeline of the plate heat exchanger. Through the differential pressure sensor ΔP, the pressure difference between the inlet and outlet of the water heat exchange pipeline of the plate heat exchanger can be detected, which is denoted as the water side pressure difference ΔPw of the plate heat exchanger.

[0044] In addition, obtain the change rate of the inlet water temperature of the water heat exchange pipeline of the plate heat exchanger, which is denoted as the change rate of the inlet water temperature on the water side of the plate heat exchanger. Specifically, it can be: The change rate of the inlet water temperature on the water side of the plate heat exchanger, ΔT_w_in / Δt, can be calculated by detecting the change amount ΔT_w_in of the inlet water temperature of the water heat exchange pipeline of the plate heat exchanger within the time Δt, and taking the ratio of the change amount ΔT_w_in of the inlet water temperature of the water heat exchange pipeline of the plate heat exchanger to the time Δt as the change rate of the inlet water temperature on the water side of the plate heat exchanger.

[0045] At step S120, when the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger is less than the set pressure difference threshold, and the change rate of the inlet water temperature on the water side of the plate heat exchanger is greater than the set temperature change threshold, start the preset anti-leakage control logic of the plate heat exchanger to achieve anti-leakage control of the plate heat exchanger. In the anti-leakage control logic of the plate heat exchanger, specifically, based on the frequency type of the water pump and the frequency type of the compressor, in combination with at least one of the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger, the change rate of the inlet water temperature on the water side of the plate heat exchanger, and the ambient temperature of the air conditioning system, determine whether there is a leakage inside the plate heat exchanger; and, when it is determined that there is a leakage inside the plate heat exchanger, send a reminder message that there is a leakage inside the plate heat exchanger to remind the user to maintain in time or control the air conditioning system to stop to avoid affecting the heat exchange efficiency of the plate heat exchanger and even damaging the compressor, which is beneficial to protecting the air conditioning system. Among them, the set pressure difference threshold is the normal difference between the pressure difference on the refrigerant side and the pressure difference on the water side under the normal working conditions of the plate heat exchanger, such as the pressure difference β under normal working conditions. The set temperature change threshold is the normal change rate of the inlet water temperature on the water side of the plate heat exchanger under the normal working conditions of the plate heat exchanger, such as the change rate Tс under normal conditions. The frequency type of the water pump is fixed frequency or variable frequency. The frequency type of the compressor is fixed frequency or variable frequency.

[0046] Specifically, when the difference between the pressure difference on the refrigerant side and the pressure difference on the water side of the plate heat exchanger is less than the set pressure difference threshold, and the rate of change of the inlet water temperature on the water side of the plate heat exchanger is greater than the set temperature change threshold, the anti-leakage control logic of the preset plate heat exchanger is activated to achieve anti-leakage control of the plate heat exchanger. In the anti-leakage control logic of the plate heat exchanger, first determine the fixed operating frequency of the water pump according to the frequency type of the water pump and in combination with the ambient temperature of the air conditioning system, and control the water pump to operate at the fixed operating frequency of the water pump. Furthermore, in the anti-leakage control logic of the plate heat exchanger, when the water pump operates at the fixed operating frequency of the water pump, then determine whether there is a leak inside the plate heat exchanger according to the frequency type of the compressor, and when it is determined that there is a leak inside the plate heat exchanger, send a reminder message that there is a leak inside the plate heat exchanger to remind the user to perform maintenance in a timely manner or control the air conditioning system to shut down to avoid affecting the heat exchange efficiency of the plate heat exchanger or even damaging the compressor, which is beneficial to protecting the air conditioning system.

[0047] As Figure 9 shown, the anti-leakage control method for the plate heat exchanger in the air conditioning system further includes: Step 2, according to Figure 8 whether the water pump in the shown air conditioning system is a fixed-frequency water pump or a variable-frequency water pump, and whether the compressor is a fixed-frequency compressor or a variable-frequency compressor, in combination with the pressure difference ΔPr on the refrigerant side and the pressure difference ΔPw on the water side of the plate heat exchanger, and the rate of change of the inlet water temperature on the water side of the plate heat exchanger ΔT_w_in / Δt, determine the leakage situation inside the plate heat exchanger. If it is determined that there is a leak inside the plate heat exchanger, send a reminder message (such as an alarm). If it is determined that there is no leak inside the plate heat exchanger, adjust the frequency of the compressor to avoid a leak inside the plate heat exchanger or further improve the accuracy of confirming the leakage situation inside the plate heat exchanger. Among them, in the anti-leakage control, the water pump is judged first to determine the operating frequency of the water pump. The water pump is always started first in the operation of the air conditioning system to avoid no heat exchange or insufficient heat exchange in the air conditioning system, causing high-pressure protection of the compressor. Adjusting the compressor frequency is because it is not certain whether it is due to the low operating frequency of the compressor or the leakage of the plate heat exchanger, so the compressor frequency needs to be adjusted for further determination.

[0048] That is, it is necessary to detect whether the difference between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger is less than the pressure difference β under normal operating conditions, and detect whether the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger is greater than the change rate Tс under normal conditions. When it is detected that the difference between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger is less than the pressure difference β under normal operating conditions, and the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger is greater than the change rate Tс under normal conditions, according to Figure 8 whether the water pump in the air-conditioning system shown is a fixed-frequency water pump or a variable-frequency water pump, and whether the compressor is a fixed-frequency compressor or a variable-frequency compressor, determine the leakage situation inside the plate heat exchanger. If it is determined that there is a leakage inside the plate heat exchanger, a reminder message (such as an alarm) is sent. If it is determined that there is no leakage inside the plate heat exchanger, the frequency of the compressor is adjusted to avoid leakage inside the plate heat exchanger or further improve the accuracy of confirming the leakage situation inside the plate heat exchanger. Among them, ΔPr, ΔPw, and β represent different pressure values, ΔT_w_in represents the temperature difference, Δt represents the time difference, and Tс represents the temperature change rate. Among them, ΔPr, ΔPw, and ΔT_w_in are real-time detected values and are dynamically changing. Taking a 6kW water heater as an example, 6000 < β <= 15000, and 10000 is taken here; Tс >= 4, and 6 is taken here.

[0049] A control method for preventing leakage of a plate heat exchanger in an air-conditioning system according to the solution of the present invention diagnoses the leakage situation inside the plate heat exchanger by detecting the pressure difference on the refrigerant side and the water side of the plate heat exchanger, and the change rate of the inlet water temperature on the water side of the plate heat exchanger. Furthermore, the operating strategy of the compressor is adjusted hierarchically and in real time using the pressure difference ranges of the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger. By increasing the change rate of the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger and finely adjusting the operating strategy of the compressor, the leakage state inside the plate heat exchanger can be accurately identified. In this way, by timely identifying the state of the plate heat exchanger and taking corresponding measures in advance, it is possible to avoid leakage of the plate heat exchanger under the impact of the refrigerant for a long time, avoid affecting the heat exchange effect of the plate heat exchanger due to internal leakage of the plate heat exchanger, and also avoid liquid accumulation in the compressor and damage to the compressor due to serious internal leakage of the plate heat exchanger, thereby avoiding damage to the air-conditioning system and also being beneficial to extending the service life of the air-conditioning system.

[0050] In some embodiments, in step S120, according to the frequency type of the water pump and the frequency type of the compressor, in combination with at least one of the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger, the water-side inlet temperature change rate of the plate heat exchanger, and the ambient temperature of the air-conditioning system, it is determined whether there is a leak inside the plate heat exchanger, including: a first judgment process for determining whether there is a leak inside the plate heat exchanger when the water pump is a constant-frequency water pump and the compressor is a constant-frequency compressor, specifically including: when the water pump is a constant-frequency water pump and the compressor is a constant-frequency compressor, when the water pump operates at its own fixed frequency, as the operation time of the air-conditioning system progresses, if the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold, the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger gradually approaches 0, and the water-side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, it is determined that there is a leak inside the plate heat exchanger; and, a reminder message that there is a leak inside the plate heat exchanger is sent to remind the user to perform maintenance in a timely manner or control the air-conditioning system to shut down to avoid affecting the heat exchange efficiency of the plate heat exchanger and even damaging the compressor, which is beneficial to protecting the air-conditioning system.

[0051] As Figure 9 shown, step 2 specifically includes: when the water pump is a constant-frequency water pump and the compressor is a constant-frequency compressor, the anti-leakage measure of the plate heat exchanger, denoted as the first anti-leakage measure, specifically includes steps 31 to 32.

[0052] Step 31: If the water pump used by the user is a constant-frequency water pump and the compressor is a constant-frequency compressor, detect whether the difference between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger is less than the pressure difference β under normal working conditions, detect whether the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger gradually approach equality over time, and detect whether the change rate ΔT_w_in / Δt of the inlet temperature of the water side of the plate heat exchanger is greater than the change rate Tс under normal conditions: If so, execute step 32, otherwise continue to wait in step 31.

[0053] Step 32: When it is detected that the difference between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger is less than the pressure difference β under normal operating conditions, and as time goes by, the two (i.e., the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger) gradually approach equality, and at the same time, the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger is greater than the change rate Tс under normal conditions, it can be determined that an internal leak has occurred in the plate heat exchanger, and an alarm prompt is issued. Among them, in the first step after the start of leak prevention control, it has been determined that ΔPr - ΔPw < β and ΔT_w_in / Δt > Tс. The purpose of making this judgment in the subsequent steps is to monitor and judge in real time. When it is detected that this condition is met, it is necessary to further determine whether it is caused by a low compressor operating frequency to prevent misjudgment. If the compressor is a fixed-frequency compressor, there is no need to make a further judgment later. When it is detected that the condition is met, it can be determined that the plate heat exchanger is leaking.

[0054] In some embodiments, in step S120, according to the frequency type of the water pump and the frequency type of the compressor, in combination with at least one of the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger, the change rate of the inlet water temperature on the water side of the plate heat exchanger, and the ambient temperature of the air conditioning system, to determine whether an internal leak has occurred in the plate heat exchanger, further includes: a second judgment process for determining whether an internal leak has occurred in the plate heat exchanger when the water pump is a fixed-frequency water pump and the compressor is a variable-frequency compressor.

[0055] The following combines Figure 2 FIG. [FIGURE NUMBER] shows a schematic flow chart of an embodiment for determining whether an internal leak has occurred in the plate heat exchanger when the water pump is a fixed-frequency water pump and the compressor is a variable-frequency compressor in the method of the present invention, and further illustrates the specific process of determining whether an internal leak has occurred in the plate heat exchanger when the water pump is a fixed-frequency water pump and the compressor is a variable-frequency compressor in step S120, including: steps S210 to S220.

[0056] In step S210, when the water pump is a fixed-frequency water pump and the compressor is a fixed-frequency compressor, as the operating time of the air conditioning system goes by, if the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold, and the change rate of the inlet water temperature on the water side of the plate heat exchanger is still greater than the set temperature change threshold, then determine whether the operating frequency of the compressor is greater than the first set frequency and less than or equal to the maximum set frequency. Among them, the first set frequency is, for example, frequency b, and the maximum set frequency is, for example, maximum frequency fmax.

[0057] At step S220, if it is determined that the operating frequency of the compressor is greater than the first set frequency and less than or equal to the maximum set frequency, then, based on the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger, it is determined whether there is a leak inside the plate heat exchanger. And, when it is determined that there is a leak inside the plate heat exchanger, a reminder message indicating that there is a leak inside the plate heat exchanger is sent to remind the user to perform maintenance in a timely manner or control the air-conditioning system to shut down to avoid affecting the heat exchange efficiency of the plate heat exchanger or even damaging the compressor, which is beneficial to protecting the air-conditioning system. More specifically, based on the pressure range in which the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger lies, it is determined whether the reason that the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold and the water-side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold is that there is a leak inside the plate heat exchanger or the operating frequency of the compressor is too low. And, when it is determined that there is a leak inside the plate heat exchanger, a reminder message indicating that there is a leak inside the plate heat exchanger is sent to remind the user to perform maintenance in a timely manner or control the air-conditioning system to shut down to avoid affecting the heat exchange efficiency of the plate heat exchanger or even damaging the compressor, which is beneficial to protecting the air-conditioning system.

[0058] In some embodiments, in step S220, determining whether there is a leak inside the plate heat exchanger based on the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger includes: based on the pressure range in which the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger lies, that is, based on the pressure range in which the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger lies in the first pressure range, the second pressure range, and the third pressure range, controlling the operating frequency of the compressor to increase by the set frequency corresponding to this pressure range on the basis of the current frequency of the compressor to obtain the first current frequency of the compressor. Wherein, the pressure range in which the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger lies includes any one of the first pressure range, the second pressure range, and the third pressure range. The first pressure range corresponds to the first set frequency by which the operating frequency of the compressor needs to be increased, the second pressure range corresponds to the second set frequency by which the operating frequency of the compressor needs to be increased, and the third pressure range corresponds to the third set frequency by which the operating frequency of the compressor needs to be increased. The specific functions and processes of this step can also be referred to in step S510.

[0059] In step S220, determining whether there is a leak inside the plate heat exchanger based on the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger further includes: furthermore, controlling the compressor to operate at the first current frequency of the compressor. And after the compressor operates at the first current frequency of the compressor for a first set time, determining the change rate of the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger within the first set time, which is denoted as the pressure difference change rate of the plate heat exchanger. The first set time is such as time tcmin. The specific functions and processing of this step can also be referred to in step S520.

[0060] In step S220, determining whether there is a leak inside the plate heat exchanger based on the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger further includes: furthermore, determining whether there is a leak inside the plate heat exchanger according to the pressure difference change rate of the plate heat exchanger; and, in the case of determining that there is a leak inside the plate heat exchanger, sending a reminder message that there is a leak inside the plate heat exchanger to remind the user to maintain it in time or control the air-conditioning system to stop running to avoid affecting the heat exchange efficiency of the plate heat exchanger or even damaging the compressor, which is beneficial to protecting the air-conditioning system. The specific functions and processing of this step can also be referred to in step S530.

[0061] In some embodiments, the above determining whether there is a leak inside the plate heat exchanger according to the pressure difference change rate of the plate heat exchanger includes: according to the pressure change interval where the pressure difference change rate of the plate heat exchanger is located, that is, according to the pressure change interval where the pressure difference change rate of the plate heat exchanger is located in the first pressure change interval, the second pressure change interval, and the third pressure change interval, controlling the operating frequency of the compressor to decrease the set frequency corresponding to the pressure change interval on the basis of the first current frequency of the compressor, so as to obtain the second current frequency of the compressor. Wherein, the pressure change interval where the pressure difference change rate of the plate heat exchanger is located includes any one of the pressure change intervals in the first pressure change interval, the second pressure change interval, and the third pressure change interval. The first pressure change interval corresponds to a fourth set frequency by which the operating frequency of the compressor needs to be decreased, the second pressure change interval corresponds to a fifth set frequency by which the operating frequency of the compressor needs to be decreased, and the third pressure change interval corresponds to a sixth set frequency by which the operating frequency of the compressor needs to be decreased. The specific functions and processing of this step can also be referred to in step S610.

[0062] Determining whether there is a leak inside the plate heat exchanger according to the differential pressure change rate of the plate heat exchanger further includes: furthermore, controlling the compressor to operate at the second current frequency of the compressor. And after the compressor operates at the second current frequency of the compressor for a second set time, if the difference between the refrigerant side differential pressure and the water side differential pressure of the plate heat exchanger is still less than the set differential pressure threshold, and the water side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, it is determined that there is a leak inside the plate heat exchanger; otherwise, it is considered that there is no leak inside the plate heat exchanger and the operating frequency of the compressor is too low. That is, if the difference between the refrigerant side differential pressure and the water side differential pressure of the plate heat exchanger is still less than the set differential pressure threshold, and the water side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, it is determined that the reason why the difference between the refrigerant side differential pressure and the water side differential pressure of the plate heat exchanger is still less than the set differential pressure threshold, and the water side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold is that there is a leak inside the plate heat exchanger; and, in the case of determining that there is a leak inside the plate heat exchanger, sending a reminder message that there is a leak inside the plate heat exchanger to remind the user to maintain in time or control the air-conditioning system to stop to avoid affecting the heat exchange efficiency of the plate heat exchanger and even damaging the compressor, which is beneficial to protecting the air-conditioning system. Otherwise, if the difference between the refrigerant side differential pressure and the water side differential pressure of the plate heat exchanger is not still less than the set differential pressure threshold, and the water side inlet temperature change rate of the plate heat exchanger is not still greater than the set temperature change threshold, it is determined that the reason why the difference between the refrigerant side differential pressure and the water side differential pressure of the plate heat exchanger is still less than the set differential pressure threshold, and the water side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold is that the operating frequency of the compressor is too low. Among them, the first set time is like time tkmin. The specific functions and processing of this step can also refer to step S620.

[0063] As Figure 9 As shown, step 2 specifically further includes: in the case where the water pump is a constant frequency water pump and the compressor is a variable frequency compressor, the anti-leakage measure of the plate heat exchanger, denoted as the second anti-leakage measure, specifically includes steps 41 to 42.

[0064] Step 41: If the water pump used by the user is a constant frequency water pump and the compressor is a variable frequency compressor, detect whether the difference between the refrigerant side differential pressure ΔPr and the water side differential pressure ΔPw of the plate heat exchanger is less than the differential pressure β under normal working conditions, and detect whether the change rate ΔT_w_in / Δt of the inlet temperature of the water side of the plate heat exchanger is greater than the change rate Tс under normal conditions: if so, execute step 42; otherwise, continue to wait in step 41.

[0065] Step 42: When the difference between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger is less than the pressure difference β under normal operating conditions, and the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger is greater than the change rate Tс under normal conditions, there are two possibilities: one is that the compressor operating frequency is low, and the other is that the plate heat exchanger leaks. At this time, it is necessary to compare whether the operating frequency of the compressor is within the set frequency range (b, fmax], that is, to determine whether the operating frequency of the compressor is greater than frequency b and less than the maximum frequency fmax: If it is, it is determined that the plate heat exchanger leaks and an alarm prompt is issued. If not, step 43 is executed.

[0066] Step 43: Specifically, it is controlled according to the following method, which includes step 431 and step 432.

[0067] Step 431: According to the interval where the difference between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger is located, the operating frequency of the compressor is increased to different degrees.

[0068] Specifically, if ΔPr - ΔPw ∈ (0, δ], the operating frequency of the compressor is controlled to increase by frequency fc0. If ΔPr - ΔPw ∈ (δ, θ], the operating frequency of the compressor is controlled to increase by frequency fc1. If ΔPr - ΔPw ∈ (θ, β], the operating frequency of the compressor is controlled to increase by frequency fc2. Among them, δ, θ, and β respectively represent different pressure values, and fc0, fc1, and fc2 respectively represent different frequency values. Among them, taking a 6kW water heater as an example, 0 < δ <= 3000, and here 2000 is taken; 3000 < θ <= 6000, and here 4000 is taken; 6000 < β <= 15000, and here 10000 is taken; fc0 = 12Hz, fc1 = 8Hz, fc2 = 4Hz.

[0069] Step 432: After running for time tcmin, determine the change rate (ΔPr - ΔPw) / Δt of the difference between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger within time Δt, that is, judge the pressure difference change rate between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger, and make appropriate adjustments to the operating frequency of the compressor.

[0070] Specifically, if (ΔPr - ΔPw) / Δt > the pressure change value vc, the operating frequency of the compressor is controlled to decrease by frequency fd0. If (ΔPr - ΔPw) / Δt ∈ (vd, vc), the operating frequency of the compressor is controlled to maintain the current frequency unchanged. If (ΔPr - ΔPw) / Δt < the pressure change value vd, the operating frequency of the compressor is controlled to increase by frequency fd2.

[0071] The running time is tkmin. If the difference between the refrigerant side pressure difference ΔPr and the water side pressure difference ΔPw of the plate heat exchanger, ΔPr - ΔPw > the pressure difference β under normal working conditions, or the change rate of the inlet water temperature on the water side of the plate heat exchanger, ΔT_w_in / Δt < the change rate Tс under normal conditions, it is considered that the reason why the difference between the refrigerant side pressure difference ΔPr and the water side pressure difference ΔPw of the plate heat exchanger in step 42 is less than the pressure difference β under normal working conditions, and the change rate of the inlet water temperature on the water side of the plate heat exchanger, ΔT_w_in / Δt > the change rate Tс under normal conditions, is due to the low operating frequency of the compressor. Conversely, if it is detected that the difference between the refrigerant side pressure difference ΔPr and the water side pressure difference ΔPw of the plate heat exchanger, ΔPr - ΔPw < the pressure difference β under normal working conditions, and the change rate of the inlet water temperature on the water side of the plate heat exchanger, ΔT_w_in / Δt > the change rate Tс under normal conditions, it is considered that the reason why the difference between the refrigerant side pressure difference ΔPr and the water side pressure difference ΔPw of the plate heat exchanger in step 42 is less than the pressure difference β under normal working conditions, and the change rate of the inlet water temperature on the water side of the plate heat exchanger, ΔT_w_in / Δt > the change rate Tс under normal conditions, is an internal leak of the plate heat exchanger, and an alarm prompt is issued.

[0072] Among them, tc and tk represent different time values, vd and vc represent different pressure change values, and fd0 and fd2 represent different frequency values. Taking a 6kW water heater as an example, tc >= 3min, and here 3min is taken; tk >= 6min, and here 6min is taken; 90 < vd <= 210, and here 180 is taken; 210 < vc <= 400, and here 390 is taken; fd0 = 8Hz, fd2 = 6Hz.

[0073] In some embodiments, in step S120, according to the frequency type of the water pump and the frequency type of the compressor, in combination with at least one of the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger, the change rate of the inlet water temperature on the water side of the plate heat exchanger, and the ambient temperature of the air conditioning system, it is determined whether there is an internal leak in the plate heat exchanger, and it further includes: a third judgment process for determining whether there is an internal leak in the plate heat exchanger when the water pump is a variable frequency water pump and the compressor is a fixed frequency compressor.

[0074] The following combines Figure 3 shown in a schematic flowchart of an embodiment for determining whether there is an internal leak in the plate heat exchanger when the water pump is a variable frequency water pump and the compressor is a fixed frequency compressor in the method of the present invention, and further illustrates the specific process of determining whether there is an internal leak in the plate heat exchanger when the water pump is a variable frequency water pump and the compressor is a fixed frequency compressor in step S120, including: step S310 and step S320.

[0075] Step S310: When the water pump is a variable-frequency water pump and the compressor is a fixed-frequency compressor, as the operation time of the air-conditioning system progresses, if the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold, and the water-side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, then according to the ambient temperature range in which the ambient temperature of the air-conditioning system is located, control the operating frequency of the water pump to be fixed at the fixed frequency value corresponding to this ambient temperature range, and obtain the current operating frequency of the water pump. Among them, the ambient temperature range in which the ambient temperature of the air-conditioning system is located includes any one of the first ambient temperature range, the second ambient temperature range, and the third ambient temperature range. The first ambient temperature range corresponds to the first set fixed frequency value, the second ambient temperature range corresponds to the second set fixed frequency value, and the third ambient temperature range corresponds to the third set fixed frequency value.

[0076] Step S320: Control the water pump to operate at the current operating frequency of the water pump. As the operation time of the air-conditioning system progresses, if the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold, the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger gradually approaches 0, and the water-side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, then it is determined that a leakage has occurred inside the plate heat exchanger; and, in the case of determining that a leakage has occurred inside the plate heat exchanger, send a reminder message that a leakage has occurred inside the plate heat exchanger to remind the user to perform maintenance in a timely manner or control the air-conditioning system to stop operating to avoid affecting the heat exchange efficiency of the plate heat exchanger and even damaging the compressor, which is beneficial to protecting the air-conditioning system.

[0077] As Figure 9 shown, step 2 specifically further includes: When the water pump is a variable-frequency water pump and the compressor is a fixed-frequency compressor, the anti-leakage measure of the plate heat exchanger, denoted as the third anti-leakage measure, specifically includes steps 51 to 53.

[0078] Step 51: If the water pump used by the user is a variable-frequency water pump and the compressor is a fixed-frequency compressor, then detect whether the difference between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger is less than the pressure difference β under normal working conditions, and detect whether the change rate ΔT_w_in / Δt of the inlet temperature of the water side of the plate heat exchanger is greater than the change rate Tс under normal conditions: If so, execute step 52, otherwise continue to wait in step 51.

[0079] Step 52: When the difference between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger is less than the pressure difference β under normal operating conditions, and the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger is greater than the change rate Tс under normal conditions, it is necessary to obtain the ambient temperature of the air-conditioning system and fix the operating frequency of the water pump according to the ambient temperature range. Here, the ambient temperature refers to the outdoor temperature, and the ambient temperature range of the ambient temperature range is [-20°C, 52°C].

[0080] Specifically, if the ambient temperature range of the air-conditioning system is [Ta, T0), then fix the operating frequency of the water pump as the frequency fb0 and control the water pump to operate at the frequency fb0. If the ambient temperature range of the air-conditioning system is [Tb, Ta), then fix the operating frequency of the water pump as the frequency fb1 and control the water pump to operate at the frequency fb1. If the ambient temperature range of the air-conditioning system is [Tmin, Tb), then fix the operating frequency of the water pump as the frequency fb2 and control the water pump to operate at the frequency fb2. Then perform Step 53.

[0081] Among them, Ta, T0, Tb, and Tmin represent different temperature values, and fb0, fb1, and fb2 represent different frequency values. Taking a 6kW water heater as an example, Ta = 23°C, T0 = 52°C, Tb = -7°C, Tmin = -20°C, fb0 = 40Hz, fb1 = 55Hz, fb2 = 60Hz.

[0082] Step 53: When it is detected that the difference between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger is less than the pressure difference β under normal operating conditions, and as time goes by, the two (i.e., the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger) gradually approach equality, and at the same time, the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger is greater than the change rate Tс under normal conditions, it can be determined that the plate heat exchanger has an internal leak and an alarm prompt is issued. Among them, the control of Step 53 is the same as the control of Step 32.

[0083] In some embodiments, in Step S120, according to the frequency type of the water pump and the frequency type of the compressor, in combination with at least one of the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger, the change rate of the water-side inlet temperature of the plate heat exchanger, and the ambient temperature of the air-conditioning system, to determine whether there is an internal leak in the plate heat exchanger, further includes: a third determination process for determining whether there is an internal leak in the plate heat exchanger when the water pump is a variable-frequency water pump and the compressor is a variable-frequency compressor.

[0084] The following is combined with Figure 4Schematic flowchart of an embodiment for determining whether there is a leak inside the plate heat exchanger when the water pump in the method of the present invention is a variable-frequency water pump and the compressor is a variable-frequency compressor, further illustrating the specific process of determining whether there is a leak inside the plate heat exchanger when the water pump is a variable-frequency water pump and the compressor is a variable-frequency compressor in step S120, including: step S410 to step S430.

[0085] Step S410, when the water pump is a variable-frequency water pump and the compressor is a fixed-frequency compressor, as the operation time of the air-conditioning system progresses, if the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold, and the water-side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, then according to the ambient temperature range of the air-conditioning system, control the operating frequency of the water pump to be fixed at the fixed frequency value corresponding to this ambient temperature range, to obtain the current operating frequency of the water pump. Among them, the ambient temperature range of the air-conditioning system includes any one of the first ambient temperature range, the second ambient temperature range, and the third ambient temperature range. The first ambient temperature range corresponds to the first set fixed frequency value, the second ambient temperature range corresponds to the second set fixed frequency value, and the third ambient temperature range corresponds to the third set fixed frequency value.

[0086] Step S420, control the water pump to operate at the current operating frequency of the water pump.

[0087] Step S430, when the water pump operates at the current operating frequency of the water pump, determine whether there is a leak inside the plate heat exchanger according to the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger; and, when it is determined that there is a leak inside the plate heat exchanger, send a reminder message that there is a leak inside the plate heat exchanger to remind the user to perform maintenance in a timely manner or control the air-conditioning system to stop to avoid affecting the heat exchange efficiency of the plate heat exchanger and even damaging the compressor, which is beneficial to protecting the air-conditioning system.

[0088] In some embodiments, for the specific process of determining whether there is a leak inside the plate heat exchanger according to the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger in step S430, refer to the following exemplary description.

[0089] The following combination Figure 5Schematic diagram of a flowchart of an embodiment for determining whether a leak has occurred inside the plate heat exchanger according to the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger in the method of the present invention, further illustrating the specific process of determining whether a leak has occurred inside the plate heat exchanger according to the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger in step S430, including: step S510 to step S530.

[0090] Step S510, according to the pressure range in which the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is located, that is, according to the pressure range in which the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is located in the first pressure range, the second pressure range, and the third pressure range, control the operating frequency of the compressor to increase the set frequency corresponding to this pressure range on the basis of the current frequency of the compressor, and obtain the first current frequency of the compressor. Among them, the pressure range in which the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is located includes any one of the first pressure range, the second pressure range, and the third pressure range. The first pressure range corresponds to the first set frequency by which the operating frequency of the compressor needs to be increased, the second pressure range corresponds to the second set frequency by which the operating frequency of the compressor needs to be increased, and the third pressure range corresponds to the third set frequency by which the operating frequency of the compressor needs to be increased.

[0091] Step S520, control the compressor to operate at the first current frequency of the compressor. And after the compressor operates at the first current frequency of the compressor for a first set time, determine the change rate of the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger within the first set time, which is recorded as the pressure difference change rate of the plate heat exchanger. The first set time is, for example, time tcmin, such as 30 s.

[0092] Step S530, determine whether a leak has occurred inside the plate heat exchanger according to the pressure difference change rate of the plate heat exchanger; and, in the case where it is determined that a leak has occurred inside the plate heat exchanger, send a reminder message that a leak has occurred inside the plate heat exchanger to remind the user to perform maintenance in time or control the air-conditioning system to stop running to avoid affecting the heat exchange efficiency of the plate heat exchanger or even damaging the compressor, which is beneficial to protecting the air-conditioning system.

[0093] In some embodiments, for the specific process of determining whether a leak has occurred inside the plate heat exchanger according to the pressure difference change rate of the plate heat exchanger in step S530, refer to the following exemplary description.

[0094] The following combines Figure 6Schematic diagram of an embodiment of the method of the present invention for determining whether there is a leakage inside the plate heat exchanger according to the pressure difference change rate of the plate heat exchanger, further illustrating the specific process of determining whether there is a leakage inside the plate heat exchanger according to the pressure difference change rate of the plate heat exchanger in step S530, including: step S610 to step S620.

[0095] Step S610, according to the pressure change interval where the pressure difference change rate of the plate heat exchanger is located, that is, according to the pressure change interval where the pressure difference change rate of the plate heat exchanger is located in the first pressure change interval, the second pressure change interval, and the third pressure change interval, control the operating frequency of the compressor to decrease the set frequency corresponding to this pressure change interval on the basis of the first current frequency of the compressor, and obtain the second current frequency of the compressor. Wherein, the pressure change interval where the pressure difference change rate of the plate heat exchanger is located includes any one of the pressure change intervals in the first pressure change interval, the second pressure change interval, and the third pressure change interval. The first pressure change interval corresponds to the fourth set frequency by which the operating frequency of the compressor needs to be decreased, the second pressure change interval corresponds to the fifth set frequency by which the operating frequency of the compressor needs to be decreased, and the third pressure change interval corresponds to the sixth set frequency by which the operating frequency of the compressor needs to be decreased.

[0096] Step S620, control the compressor to operate at the second current frequency of the compressor. After the compressor operates at the second current frequency of the compressor for a second set time, if the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold, and the water side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, it is determined that a leak has occurred inside the plate heat exchanger. And, in the case where it is determined that a leak has occurred inside the plate heat exchanger, a reminder message indicating that a leak has occurred inside the plate heat exchanger is sent to remind the user to perform maintenance in a timely manner or control the air-conditioning system to stop running to avoid affecting the heat exchange efficiency of the plate heat exchanger or even damaging the compressor, which is beneficial to protecting the air-conditioning system; otherwise, it is considered that no leak has occurred inside the plate heat exchanger and the operating frequency of the compressor is too low. That is, if the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold, and the water side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, it is determined that the reason why the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold, and the water side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, is that a leak has occurred inside the plate heat exchanger. And, in the case where it is determined that a leak has occurred inside the plate heat exchanger, a reminder message indicating that a leak has occurred inside the plate heat exchanger is sent to remind the user to perform maintenance in a timely manner or control the air-conditioning system to stop running to avoid affecting the heat exchange efficiency of the plate heat exchanger or even damaging the compressor, which is beneficial to protecting the air-conditioning system. Otherwise, if the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger is not still less than the set pressure difference threshold, and the water side inlet temperature change rate of the plate heat exchanger is not still greater than the set temperature change threshold, it is determined that the reason why the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold, and the water side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, is that the operating frequency of the compressor is too low. Among them, the first set time is like time tkmin.

[0097] As Figure 9 As shown, step 2 specifically further includes: in the case where the water pump is a variable-frequency water pump and the compressor is a variable-frequency compressor, the anti-leakage measure of the plate heat exchanger, denoted as the fourth anti-leakage measure, specifically includes steps 61 to 62.

[0098] Step 61: If the water pump used by the user is a variable-frequency water pump and the compressor is a variable-frequency compressor, then detect whether the difference between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger is less than the pressure difference β under normal operating conditions, and detect whether the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger is greater than the change rate Tс under normal conditions. If so, execute Step 62; otherwise, continue to wait in Step 61.

[0099] Step 62: When it is detected that the difference between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger is less than the pressure difference β under normal operating conditions, and the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger is greater than the change rate Tс under normal conditions, it is necessary to obtain the ambient temperature of the air-conditioning system and fix the operating frequency of the water pump according to the ambient temperature range.

[0100] Specifically, if the ambient temperature range of the air-conditioning system is [Ta, T0), then fix the operating frequency of the water pump as frequency fb0 and control the water pump to operate at frequency fb0. If the ambient temperature range of the air-conditioning system is [Tb, Ta), then fix the operating frequency of the water pump as frequency fb1 and control the water pump to operate at frequency fb1. If the ambient temperature range of the air-conditioning system is [Tmin, Tb), then fix the operating frequency of the water pump as frequency fb2 and control the water pump to operate at frequency fb2. Then execute Step 63.

[0101] Step 63: When it is detected that the difference between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger is less than the pressure difference β under normal operating conditions, and the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger is greater than the change rate Tс under normal conditions, there are two possibilities: one is that the compressor operating frequency is low, and the other is that the plate heat exchanger leaks. At this time, it is necessary to compare whether the operating frequency of the compressor is within the interval of the set frequency range (b, fmax], that is, to judge whether the operating frequency of the compressor is greater than the set frequency b and less than the set maximum frequency fmax. If so, it is determined that the plate heat exchanger leaks and an alarm prompt is issued. If not, execute Step 64.

[0102] Step 64: Specifically, it is controlled according to the following method, that is, it includes Step 641 and Step 642.

[0103] Step 641: According to the interval where the difference between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger is located, the operating frequency of the compressor is increased to different degrees.

[0104] Specifically, if ΔPr - ΔPw ∈ (0, δ], then control the operating frequency of the compressor to increase the frequency by fc0. If ΔPr - ΔPw ∈ (δ, θ], then control the operating frequency of the compressor to increase the frequency by fc1. If ΔPr - ΔPw ∈ (θ, β], then control the operating frequency of the compressor to increase the frequency by fc2. Wherein, δ, θ, and β respectively represent different pressure values, and fc0, fc1, and fc2 respectively represent different frequency values.

[0105] Step 642: After the running time tcmin, determine the change rate (ΔPr - ΔPw) / Δt of the difference between the refrigerant side pressure difference ΔPr and the water side pressure difference ΔPw of the plate heat exchanger within the time Δt, that is, judge the pressure difference change rate of the refrigerant side pressure difference ΔPr and the water side pressure difference ΔPw of the plate heat exchanger, and make appropriate adjustments to the operating frequency of the compressor.

[0106] Specifically, if (ΔPr - ΔPw) / Δt > the pressure vc, then control the operating frequency of the compressor to decrease the frequency by fd0. If (ΔPr - ΔPw) / Δt ∈ (vd, vc), then control the operating frequency of the compressor to maintain the current frequency unchanged. If (ΔPr - ΔPw) / Δt < the pressure vd, control the operating frequency of the compressor to increase the frequency by fd2.

[0107] During the running time tkmin, if it is detected that the difference ΔPr - ΔPw between the refrigerant side pressure difference ΔPr and the water side pressure difference ΔPw of the plate heat exchanger > the pressure difference β under normal operating conditions or the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger < the change rate Tс under normal conditions, then it is considered that the reason for the difference between the refrigerant side pressure difference ΔPr and the water side pressure difference ΔPw of the plate heat exchanger in step 42 being less than the pressure difference β under normal operating conditions and the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger being greater than the change rate Tс under normal conditions is due to the low operating frequency of the compressor. On the contrary, if it is detected that the difference ΔPr - ΔPw between the refrigerant side pressure difference ΔPr and the water side pressure difference ΔPw of the plate heat exchanger < the pressure difference β under normal operating conditions and the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger > the change rate Tс under normal conditions, then it is considered that the reason for the difference between the refrigerant side pressure difference ΔPr and the water side pressure difference ΔPw of the plate heat exchanger in step 42 being less than the pressure difference β under normal operating conditions and the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger being greater than the change rate Tс under normal conditions is due to an internal leak in the plate heat exchanger, and an alarm prompt is issued. Among them, the control of steps 63 and 64 is the same as the control of steps 42 and 43.

[0108] Adopting the technical solution of this embodiment, by detecting the refrigerant side pressure difference ΔPr of the plate heat exchanger, the water side pressure difference ΔPw of the plate heat exchanger, and the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger, when it is detected that the difference between the refrigerant side pressure difference ΔPr and the water side pressure difference ΔPw of the plate heat exchanger is less than the pressure difference β under normal working conditions, and the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger is greater than the change rate Tс under normal conditions, according to whether the water pump is a fixed-frequency water pump or a variable-frequency water pump, and whether the compressor is a fixed-frequency compressor or a variable-frequency compressor, determine the leakage situation inside the plate heat exchanger. If it is determined that there is a leakage inside the plate heat exchanger, a reminder message (such as an alarm) is sent. If it is determined that there is no leakage inside the plate heat exchanger, adjust the frequency of the compressor to avoid leakage inside the plate heat exchanger or further improve the confirmation accuracy of the leakage situation inside the plate heat exchanger. Thus, by identifying the state of the plate heat exchanger and taking corresponding measures in advance, it is possible to avoid the heat exchange effect of the plate heat exchanger being affected or even the compressor being damaged due to serious internal leakage of the plate heat exchanger, and ensure the normal operation of the air-conditioning system.

[0109] According to an embodiment of the present invention, there is also provided a control device for an air-conditioning system corresponding to the control method of the air-conditioning system. Refer to Figure 7 The structural schematic diagram of an embodiment of the device of the present invention shown. The air-conditioning system has a compressor, an outdoor heat exchanger, and an indoor heat exchanger. The indoor heat exchanger is a plate heat exchanger, and the plate heat exchanger has a refrigerant heat exchange pipeline and a water heat exchange pipeline, and heat exchange can be carried out between the refrigerant heat exchange pipeline and the water heat exchange pipeline. The compressor, the outdoor heat exchanger, and the refrigerant heat exchange pipeline form a refrigerant heat exchange loop through a refrigerant circulation pipeline. For example: one port of the compressor is connected to the other port of the compressor after passing through the outdoor heat exchanger and the refrigerant heat exchange pipeline. The water heat exchange pipeline, together with a water pump, a water tank, and a heat-using device arranged in the space where the air-conditioning system is located, forms a water heat exchange loop through a water circulation pipeline. For example: one end of the water heat exchange pipeline is connected to the other end of the water heat exchange pipeline after passing through the water pump, the water tank, and the heat-using device arranged in the space where the air-conditioning system is located. Specifically, Figure 8 It is the structural schematic diagram of an embodiment of the air-conditioning system. As Figure 8As shown, an air conditioning system includes: a compressor, an outdoor heat exchanger, an indoor heat exchanger, a throttle valve, water-using devices such as a floor heating system, a water tank, and a water pump. The indoor heat exchanger is a plate heat exchanger, which has a refrigerant heat exchange pipeline on the refrigerant side and a water heat exchange pipeline on the water side. Among them, one port of the compressor is connected to the other port of the compressor through the first port of the refrigerant heat exchange pipeline of the plate heat exchanger, the second port of the refrigerant heat exchange pipeline of the plate heat exchanger, the throttle valve, and the outdoor heat exchanger. One port of the water heat exchange pipeline of the plate heat exchanger is connected to the other port of the water heat exchange pipeline of the plate heat exchanger through water-using devices such as a floor heating system, the water tank, the first port of the water pump, and the second port of the water pump.

[0110] See Figure 8 In the example shown, a pressure sensor P is provided on the pipeline where the first port of the refrigerant heat exchange pipeline of the plate heat exchanger is located. A temperature sensor T is provided on the pipeline where the second port of the refrigerant heat exchange pipeline of the plate heat exchanger is located. A temperature sensor T is provided on the pipeline where the second port of the water pump is located. A differential pressure sensor ΔP is installed on the pipeline where the inlet and outlet of the water heat exchange pipeline of the plate heat exchanger are located. The control device of the air conditioning system includes: an acquisition unit 102 and a control unit 104.

[0111] Among them, the acquisition unit 102 is configured to, when the air conditioning system is started and running, acquire the differential pressure between the inlet and outlet of the refrigerant heat exchange pipeline in the plate heat exchanger, denoted as the refrigerant side differential pressure of the plate heat exchanger, that is, the differential pressure ΔPr on the refrigerant side of the plate heat exchanger. Acquire the differential pressure between the inlet and outlet of the water heat exchange pipeline in the plate heat exchanger, denoted as the water side differential pressure of the plate heat exchanger, that is, the differential pressure ΔPw on the water side of the plate heat exchanger. Acquire the change rate of the inlet water temperature of the water heat exchange pipeline in the plate heat exchanger, denoted as the change rate of the inlet water temperature on the water side of the plate heat exchanger, that is, the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger. And acquire the ambient temperature of the air conditioning system, for example, sample the ambient temperature of the air conditioning system using an ambient temperature sensor to obtain the ambient temperature of the air conditioning system. The specific functions and processes of this acquisition unit 102 are shown in step S110.

[0112] Specifically, Figure 9 It is a schematic flowchart of an embodiment of the leak prevention control device for the plate heat exchanger in the air conditioning system. As Figure 9As shown, the leak prevention control device of the plate heat exchanger in the air conditioning system includes: Step 1, obtain the pressure difference between the inlet and the outlet of the refrigerant heat exchange pipeline of the plate heat exchanger, denoted as the refrigerant side pressure difference ΔPr of the plate heat exchanger. Obtain the pressure difference between the inlet and the outlet of the water heat exchange pipeline of the plate heat exchanger, denoted as the water side pressure difference ΔPw of the plate heat exchanger. And obtain the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger (i.e., the change rate ΔT_w_in / Δt of the inlet water temperature of the water heat exchange pipeline of the plate heat exchanger), where ΔT_w_in is the change amount of the inlet water temperature of the water heat exchange pipeline of the plate heat exchanger within the time Δt.

[0113] Among them, obtaining the pressure difference between the inlet and the outlet of the refrigerant heat exchange pipeline in the plate heat exchanger, denoted as the refrigerant side pressure difference of the plate heat exchanger, includes: If the air conditioning system operates in the heating mode, sample the pressures at the inlet and the outlet of the refrigerant heat exchange pipeline in the plate heat exchanger to obtain the pressure difference between the inlet and the outlet of the refrigerant heat exchange pipeline in the plate heat exchanger, denoted as the refrigerant side pressure difference of the plate heat exchanger. If the air conditioning system operates in the cooling mode, sample the temperatures at the inlet and the outlet of the refrigerant heat exchange pipeline in the plate heat exchanger, and calculate to obtain the pressure difference between the inlet and the outlet of the refrigerant heat exchange pipeline in the plate heat exchanger, denoted as the refrigerant side pressure difference of the plate heat exchanger.

[0114] Since in the heating mode of the air conditioning system, the indoor heat exchanger such as the plate heat exchanger is used as a condenser, and the outdoor heat exchanger is used as an evaporator. In the cooling mode of the air conditioning system, the indoor heat exchanger such as the plate heat exchanger is used as an evaporator, and the outdoor heat exchanger is used as a condenser. Therefore, referring to Figure 8 the example shown, when the plate heat exchanger is used as a condenser in the heating mode, install a pressure sensor P at the front end of the plate heat exchanger (such as the pipeline where the first port of the refrigerant heat exchange pipeline of the plate heat exchanger is located), and the pressure of the first port of the refrigerant heat exchange pipeline of the plate heat exchanger can be detected. Since the plate heat exchanger is used as an evaporator in the cooling mode, and the inlet of the evaporator is a two-phase region, a temperature sensor T needs to be installed at the pipeline where the second port of the refrigerant heat exchange pipeline of the plate heat exchanger is located to indirectly calculate the pressure of the second port of the refrigerant heat exchange pipeline of the plate heat exchanger. Thus, based on the pressure of the first port of the refrigerant heat exchange pipeline of the plate heat exchanger and the pressure of the second port of the refrigerant heat exchange pipeline of the plate heat exchanger, calculate the pressure difference between the pressure of the first port of the refrigerant heat exchange pipeline of the plate heat exchanger and the pressure of the second port of the refrigerant heat exchange pipeline of the plate heat exchanger, as the pressure difference between the inlet and the outlet of the refrigerant heat exchange pipeline of the plate heat exchanger, denoted as the refrigerant side pressure difference ΔPr of the plate heat exchanger.

[0115] Similarly, obtain the pressure difference between the inlet and outlet of the water heat exchange pipeline of the plate heat exchanger, which is denoted as the water side pressure difference of the plate heat exchanger. Specifically, it can be: Refer to Figure 8 the example shown in Figure 8 . Install a pressure difference sensor ΔP at the inlet and outlet of the water side heat exchange pipeline of the plate heat exchanger. Through the pressure difference sensor ΔP, the pressure difference between the inlet and outlet of the water heat exchange pipeline of the plate heat exchanger can be detected, which is denoted as the water side pressure difference ΔPw of the plate heat exchanger.

[0116] In addition, obtain the change rate of the inlet water temperature of the water heat exchange pipeline of the plate heat exchanger, which is denoted as the change rate of the inlet water temperature on the water side of the plate heat exchanger. Specifically, it can be: The change rate of the inlet water temperature on the water side of the plate heat exchanger, ΔT_w_in / Δt, can be calculated by detecting the change amount ΔT_w_in of the inlet water temperature of the water heat exchange pipeline of the plate heat exchanger within the time Δt, and calculating the ratio of the change amount ΔT_w_in of the inlet water temperature of the water heat exchange pipeline of the plate heat exchanger to the time Δt, which is used as the change rate of the inlet water temperature on the water side of the plate heat exchanger.

[0117] The control unit 104 is configured to start the preset anti-leakage control logic of the plate heat exchanger when the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger is less than the set pressure difference threshold and the change rate of the inlet water temperature on the water side of the plate heat exchanger is greater than the set temperature change threshold, so as to achieve the anti-leakage control of the plate heat exchanger. In the anti-leakage control logic of the plate heat exchanger, specifically, according to the frequency type of the water pump and the frequency type of the compressor, in combination with at least one of the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger, the change rate of the inlet water temperature on the water side of the plate heat exchanger, and the ambient temperature of the air conditioning system, it is determined whether there is a leakage inside the plate heat exchanger; and, when it is determined that there is a leakage inside the plate heat exchanger, a reminder message that there is a leakage inside the plate heat exchanger is sent to remind the user to maintain in time or control the air conditioning system to stop to avoid affecting the heat exchange efficiency of the plate heat exchanger and even damaging the compressor, which is beneficial to protecting the air conditioning system. The specific functions and processes of this control unit 104 are referred to step S120. Among them, the set pressure difference threshold is the normal difference between the pressure difference on the refrigerant side and the pressure difference on the water side under the normal working conditions of the plate heat exchanger, such as the pressure difference β under normal working conditions. The set temperature change threshold is the normal change rate of the inlet water temperature on the water side of the plate heat exchanger under the normal working conditions of the plate heat exchanger, such as the change rate Tс under normal conditions. The frequency type of the water pump is fixed frequency or variable frequency. The frequency type of the compressor is fixed frequency or variable frequency.

[0118] Specifically, when the difference between the pressure difference on the refrigerant side and the pressure difference on the water side of the plate heat exchanger is less than the set pressure difference threshold, and the rate of change of the inlet water temperature on the water side of the plate heat exchanger is greater than the set temperature change threshold, the anti-leakage control logic of the preset plate heat exchanger is started to achieve anti-leakage control of the plate heat exchanger. In the anti-leakage control logic of the plate heat exchanger, first, the fixed operating frequency of the water pump is determined according to the frequency type of the water pump and in combination with the ambient temperature of the air conditioning system, and the water pump is controlled to operate at the fixed operating frequency of the water pump. Furthermore, in the anti-leakage control logic of the plate heat exchanger, when the water pump operates at the fixed operating frequency of the water pump, it is then determined whether there is a leakage inside the plate heat exchanger according to the frequency type of the compressor, and when it is determined that there is a leakage inside the plate heat exchanger, a reminder message that there is a leakage inside the plate heat exchanger is sent to remind the user to perform maintenance in a timely manner or control the air conditioning system to shut down to avoid affecting the heat exchange efficiency of the plate heat exchanger and even damaging the compressor, which is beneficial to protecting the air conditioning system.

[0119] As Figure 9 shown, the anti-leakage control device of the plate heat exchanger in the air conditioning system further includes: Step 2. According to Figure 8 whether the water pump in the air conditioning system shown is a fixed-frequency water pump or a variable-frequency water pump, and whether the compressor is a fixed-frequency compressor or a variable-frequency compressor, in combination with the pressure difference ΔPr on the refrigerant side and the pressure difference ΔPw on the water side of the plate heat exchanger, and the rate of change ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger, determine the leakage situation inside the plate heat exchanger. If it is determined that there is a leakage inside the plate heat exchanger, a reminder message (such as an alarm) is sent. If it is determined that there is no leakage inside the plate heat exchanger, the frequency of the compressor is adjusted to avoid leakage inside the plate heat exchanger or further improve the confirmation accuracy of the leakage situation inside the plate heat exchanger.

[0120] That is to say, it is detected whether the difference between the pressure difference ΔPr on the refrigerant side and the pressure difference ΔPw on the water side of the plate heat exchanger is less than the pressure difference β under normal working conditions, and it is detected whether the rate of change ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger is greater than the rate of change Tс under normal conditions. When it is detected that the difference between the pressure difference ΔPr on the refrigerant side and the pressure difference ΔPw on the water side of the plate heat exchanger is less than the pressure difference β under normal working conditions, and the rate of change ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger is greater than the rate of change Tс under normal conditions, according to Figure 8In the air conditioning system shown, determine whether the water pump is a fixed-frequency water pump or a variable-frequency water pump, and whether the compressor is a fixed-frequency compressor or a variable-frequency compressor, to determine the leakage situation inside the plate heat exchanger. If it is determined that there is a leakage inside the plate heat exchanger, a reminder message (such as an alarm) is sent. If it is determined that there is no leakage inside the plate heat exchanger, the frequency of the compressor is adjusted to avoid leakage inside the plate heat exchanger or to further improve the accuracy of confirming the leakage situation inside the plate heat exchanger. Among them, ΔPr, ΔPw, and β represent different pressure values, ΔT_w_in represents the temperature difference, Δt represents the time difference, and Tс represents the temperature change rate.

[0121] A control device for preventing leakage of a plate heat exchanger in an air conditioning system according to the solution of the present invention diagnoses the leakage situation inside the plate heat exchanger by detecting the pressure difference on the refrigerant side and the pressure difference on the water side of the plate heat exchanger, and the change rate of the inlet water temperature on the water side of the plate heat exchanger. Furthermore, the operating strategy of the compressor is adjusted hierarchically and in real time by using the pressure difference range between the pressure difference on the refrigerant side and the pressure difference on the water side of the plate heat exchanger, so as to increase the change rate of the pressure difference on the refrigerant side and the pressure difference on the water side of the plate heat exchanger and finely adjust the operating strategy of the compressor, and the leakage state inside the plate heat exchanger can be accurately identified. In this way, by timely identifying the state of the plate heat exchanger and taking corresponding measures in advance, it is possible to avoid leakage of the plate heat exchanger under the pressure of the refrigerant for a long time, avoid the influence on the heat exchange effect of the plate heat exchanger due to internal leakage of the plate heat exchanger, and also avoid damage to the compressor due to liquid accumulation caused by serious internal leakage of the plate heat exchanger, thereby avoiding damage to the air conditioning system and being beneficial to extending the service life of the air conditioning system.

[0122] In some embodiments, the control unit 104 determines whether there is leakage inside the plate heat exchanger according to at least one of the frequency type of the water pump, the frequency type of the compressor, the difference between the pressure difference on the refrigerant side and the pressure difference on the water side of the plate heat exchanger, the change rate of the inlet water temperature on the water side of the plate heat exchanger, and the ambient temperature of the air conditioning system, including: a first judgment process for determining whether there is leakage inside the plate heat exchanger when the water pump is a fixed-frequency water pump and the compressor is a fixed-frequency compressor, specifically as follows:

[0123] The control unit 104 is further specifically configured such that when the water pump is a fixed-frequency water pump and the compressor is a fixed-frequency compressor, and when the water pump operates at its own fixed frequency, as the operation time of the air-conditioning system elapses, if the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold, the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger gradually approaches 0, and the change rate of the water-side inlet temperature of the plate heat exchanger is still greater than the set temperature change threshold, it is determined that a leakage has occurred inside the plate heat exchanger; and a reminder message indicating that a leakage has occurred inside the plate heat exchanger is sent to remind the user to perform maintenance in a timely manner or control the air-conditioning system to stop operating to avoid affecting the heat exchange efficiency of the plate heat exchanger or even damaging the compressor, which is beneficial to protecting the air-conditioning system.

[0124] As Figure 9 shown, step 2 specifically includes: when the water pump is a fixed-frequency water pump and the compressor is a fixed-frequency compressor, the anti-leakage measure for the plate heat exchanger, denoted as the first anti-leakage measure, specifically includes steps 31 to 32.

[0125] Step 31: If the water pump used by the user is a fixed-frequency water pump and the compressor is a fixed-frequency compressor, detect whether the difference between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger is less than the pressure difference β under normal operating conditions, detect whether the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger gradually approach equality over time, and detect whether the change rate ΔT_w_in / Δt of the inlet temperature of the water side of the plate heat exchanger is greater than the change rate Tс under normal conditions: If so, execute step 32; otherwise, continue to wait in step 31.

[0126] Step 32: When it is detected that the difference between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger is less than the pressure difference β under normal operating conditions, and the two (i.e., the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger) gradually approach equality over time, and at the same time the change rate ΔT_w_in / Δt of the inlet temperature of the water side of the plate heat exchanger is greater than the change rate Tс under normal conditions, it can be determined that an internal leakage has occurred in the plate heat exchanger, and an alarm prompt is issued.

[0127] In some embodiments, the control unit 104 determines whether there is a leak inside the plate heat exchanger based on at least one of the frequency type of the water pump, the frequency type of the compressor, the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger, the water-side inlet temperature change rate of the plate heat exchanger, and the ambient temperature of the air conditioning system. It further includes a second determination process for determining whether there is a leak inside the plate heat exchanger when the water pump is a fixed-frequency water pump and the compressor is a variable-frequency compressor, specifically as follows:

[0128] Specifically, the control unit 104 is further configured such that when the water pump is a fixed-frequency water pump and the compressor is a fixed-frequency compressor, as the operation time of the air conditioning system elapses, if the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is still less than a set pressure difference threshold and the water-side inlet temperature change rate of the plate heat exchanger is still greater than a set temperature change threshold, it determines whether the operating frequency of the compressor is greater than a first set frequency and less than or equal to the maximum set frequency. For the specific functions and processing of this control unit 104, refer to step S210. Here, the first set frequency is, for example, frequency b, and the maximum set frequency is, for example, maximum frequency fmax.

[0129] Specifically, the control unit 104 is further configured such that if it determines that the operating frequency of the compressor is greater than the first set frequency and less than or equal to the maximum set frequency, it determines whether there is a leak inside the plate heat exchanger based on the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger. And, when it determines that there is a leak inside the plate heat exchanger, it sends a reminder message indicating that there is a leak inside the plate heat exchanger to remind the user to perform maintenance in a timely manner or control the air conditioning system to stop operating to avoid affecting the heat exchange efficiency of the plate heat exchanger or even damaging the compressor, which is beneficial to protecting the air conditioning system. More specifically, it determines whether the reason for the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger still being less than the set pressure difference threshold and the water-side inlet temperature change rate of the plate heat exchanger still being greater than the set temperature change threshold is that there is a leak inside the plate heat exchanger or that the operating frequency of the compressor is too low according to the pressure range in which the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is located. And, when it determines that there is a leak inside the plate heat exchanger, it sends a reminder message indicating that there is a leak inside the plate heat exchanger to remind the user to perform maintenance in a timely manner or control the air conditioning system to stop operating to avoid affecting the heat exchange efficiency of the plate heat exchanger or even damaging the compressor, which is beneficial to protecting the air conditioning system. For the specific functions and processing of this control unit 104, refer to step S220.

[0130] In some embodiments, the control unit 104 determines whether there is a leak inside the plate heat exchanger according to the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger, including: specifically, the control unit 104 is further configured to control the operating frequency of the compressor to increase by a set frequency corresponding to the pressure range based on the current frequency of the compressor according to the pressure range in which the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is located, that is, according to the pressure range in which the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is located in the first pressure range, the second pressure range, and the third pressure range, to obtain the first current frequency of the compressor. Wherein, the pressure range in which the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is located includes any one of the first pressure range, the second pressure range, and the third pressure range. The first pressure range corresponds to a first set frequency by which the operating frequency of the compressor needs to be increased, the second pressure range corresponds to a second set frequency by which the operating frequency of the compressor needs to be increased, and the third pressure range corresponds to a third set frequency by which the operating frequency of the compressor needs to be increased. For the specific functions and processes of this control unit 104, refer to step S510

[0131] The control unit 104 determines whether there is a leak inside the plate heat exchanger according to the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger, and further includes: furthermore, the control unit 104 is specifically further configured to control the compressor to operate at the first current frequency of the compressor. And after the compressor operates at the first current frequency of the compressor for a first set time, determine the change rate of the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger within the first set time, which is denoted as the pressure difference change rate of the plate heat exchanger. The first set time is, for example, time tcmin. For the specific functions and processes of this control unit 104, refer to step S520

[0132] The control unit 104 determines whether there is a leak inside the plate heat exchanger according to the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger, and further includes: Furthermore, the control unit 104 is specifically configured to determine whether there is a leak inside the plate heat exchanger according to the pressure difference change rate of the plate heat exchanger; and, when it is determined that there is a leak inside the plate heat exchanger, send a reminder message that there is a leak inside the plate heat exchanger to remind the user to perform maintenance in a timely manner or control the air conditioning system to shut down to avoid affecting the heat exchange efficiency of the plate heat exchanger and even damaging the compressor, which is beneficial to protecting the air conditioning system. For the specific functions and processing of this control unit 104, refer to step S530

[0133] In some embodiments, the control unit 104 determines whether there is a leak inside the plate heat exchanger according to the pressure difference change rate of the plate heat exchanger, including: The control unit 104 is specifically configured to control the operating frequency of the compressor to decrease the set frequency corresponding to the pressure change interval based on the first current frequency of the compressor according to the pressure change interval in which the pressure difference change rate of the plate heat exchanger is located, that is, according to the pressure change interval in which the pressure difference change rate of the plate heat exchanger is located in the first pressure change interval, the second pressure change interval, and the third pressure change interval, to obtain the second current frequency of the compressor. Wherein, the pressure change interval in which the pressure difference change rate of the plate heat exchanger is located includes any one of the pressure change intervals in the first pressure change interval, the second pressure change interval, and the third pressure change interval. The first pressure change interval corresponds to the fourth set frequency by which the operating frequency of the compressor needs to be decreased, the second pressure change interval corresponds to the fifth set frequency by which the operating frequency of the compressor needs to be decreased, and the third pressure change interval corresponds to the sixth set frequency by which the operating frequency of the compressor needs to be decreased. For the specific functions and processing of this control unit 104, refer to step S610.

[0134] The control unit 104 determines whether there is a leak inside the plate heat exchanger according to the differential pressure change rate of the plate heat exchanger, and further includes: furthermore, the control unit 104 is specifically configured to control the compressor to operate at the second current frequency of the compressor. After the compressor operates at the second current frequency of the compressor for a second set time, if the difference between the refrigerant-side differential pressure and the water-side differential pressure of the plate heat exchanger is still less than the set differential pressure threshold, and the water-side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, it is determined that there is a leak inside the plate heat exchanger; otherwise, it is considered that there is no leak inside the plate heat exchanger and the operating frequency of the compressor is too low. That is, if the difference between the refrigerant-side differential pressure and the water-side differential pressure of the plate heat exchanger is still less than the set differential pressure threshold, and the water-side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, it is determined that the reason why the difference between the refrigerant-side differential pressure and the water-side differential pressure of the plate heat exchanger is still less than the set differential pressure threshold, and the water-side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold is that there is a leak inside the plate heat exchanger; and, in the case of determining that there is a leak inside the plate heat exchanger, a reminder message that there is a leak inside the plate heat exchanger is sent to remind the user to maintain in time or control the air-conditioning system to stop to avoid affecting the heat exchange efficiency of the plate heat exchanger or even damaging the compressor, which is beneficial to protecting the air-conditioning system. Otherwise, if the difference between the refrigerant-side differential pressure and the water-side differential pressure of the plate heat exchanger is not still less than the set differential pressure threshold, and the water-side inlet temperature change rate of the plate heat exchanger is not still greater than the set temperature change threshold, it is determined that the reason why the difference between the refrigerant-side differential pressure and the water-side differential pressure of the plate heat exchanger is still less than the set differential pressure threshold, and the water-side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold is that the operating frequency of the compressor is too low. Among them, the first set time is such as time tkmin. For the specific functions and processes of this control unit 104, refer to step S620

[0135] As Figure 9 As shown, step 2 specifically further includes: in the case where the water pump is a constant-frequency water pump and the compressor is a variable-frequency compressor, the anti-leakage measures of the plate heat exchanger, denoted as the second anti-leakage measures, specifically include steps 41 to 42

[0136] Step 41: If the water pump used by the user is a fixed-frequency water pump and the compressor is a variable-frequency compressor, detect whether the difference between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger is less than the pressure difference β under normal operating conditions, and detect whether the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger is greater than the change rate Tс under normal conditions. If so, execute Step 42; otherwise, continue to wait in Step 41.

[0137] Step 42: When it is detected that the difference between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger is less than the pressure difference β under normal operating conditions, and the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger is greater than the change rate Tс under normal conditions, there are two possibilities: one is that the operating frequency of the compressor is low, and the other is that the plate heat exchanger leaks. At this time, it is necessary to compare whether the operating frequency of the compressor is within the set frequency range (b, fmax], that is, to determine whether the operating frequency of the compressor is greater than the frequency b and less than the maximum frequency fmax. If it is within, it is determined that the plate heat exchanger leaks and an alarm prompt is issued. If not, execute Step 43.

[0138] Step 43: Specifically, it is controlled according to the following device, which includes Step 431 and Step 432.

[0139] Step 431: According to the interval where the difference between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger is located, the operating frequency of the compressor is increased to different degrees.

[0140] Specifically, if ΔPr - ΔPw ∈ (0, δ], control the operating frequency of the compressor to increase by the frequency fc0. If ΔPr - ΔPw ∈ (δ, θ], control the operating frequency of the compressor to increase by the frequency fc1. If ΔPr - ΔPw ∈ (θ, β], control the operating frequency of the compressor to increase by the frequency fc2. Where δ, θ, and β respectively represent different pressure values, and fc0, fc1, and fc2 respectively represent different frequency values.

[0141] Step 432: After running for the time tcmin, determine the change rate (ΔPr - ΔPw) / Δt of the difference between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger within the time Δt, that is, judge the pressure difference change rate between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger, and make appropriate adjustments to the operating frequency of the compressor.

[0142] Specifically, if (ΔPr - ΔPw) / Δt > the pressure change value vc, control the operating frequency of the compressor to decrease by the frequency fd0. If (ΔPr - ΔPw) / Δt ∈ (vd, vc), control the operating frequency of the compressor to maintain the current frequency unchanged. If (ΔPr - ΔPw) / Δt < the pressure change value vd, control the operating frequency of the compressor to increase by the frequency fd2.

[0143] The running time is tkmin. If the difference ΔPr - ΔPw between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger is greater than the pressure difference β under normal operating conditions, or the change rate ΔTw_in / Δt of the inlet water temperature on the water side of the plate heat exchanger is less than the change rate Tс under normal conditions, it is considered that the reason why the difference between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger in step 42 is less than the pressure difference β under normal operating conditions, and the change rate ΔTw_in / Δt of the inlet water temperature on the water side of the plate heat exchanger is greater than the change rate Tс under normal conditions is due to the low operating frequency of the compressor. Conversely, if it is detected that the difference ΔPr - ΔPw between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger is less than the pressure difference β under normal operating conditions and the change rate ΔTw_in / Δt of the inlet water temperature on the water side of the plate heat exchanger is greater than the change rate Tс under normal conditions, it is considered that the reason why the difference between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger in step 42 is less than the pressure difference β under normal operating conditions, and the change rate ΔTw_in / Δt of the inlet water temperature on the water side of the plate heat exchanger is greater than the change rate Tс under normal conditions is due to an internal leak in the plate heat exchanger, and an alarm prompt is issued.

[0144] Among them, tc and tk represent different time values, vd and vc represent different pressure change values, and fd0 and fd2 represent different frequency values.

[0145] In some embodiments, the control unit 104 determines whether an internal leak has occurred in the plate heat exchanger according to at least one of the frequency type of the water pump, the frequency type of the compressor, the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger, the change rate of the inlet water temperature on the water side of the plate heat exchanger, and the ambient temperature of the air conditioning system. It further includes: a third determination process for determining whether an internal leak has occurred in the plate heat exchanger when the water pump is a variable-frequency water pump and the compressor is a fixed-frequency compressor, specifically as follows:

[0146] The control unit 104 is further specifically configured such that when the water pump is a variable-frequency water pump and the compressor is a fixed-frequency compressor, as the operation time of the air-conditioning system elapses, if the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is still less than a set pressure difference threshold value, and the water-side inlet temperature change rate of the plate heat exchanger is still greater than a set temperature change threshold value, then according to the ambient temperature range in which the ambient temperature of the air-conditioning system is located, the operation frequency of the water pump is controlled to be fixed at the fixed frequency value corresponding to this ambient temperature range, thereby obtaining the current operation frequency of the water pump. Among them, the ambient temperature range in which the ambient temperature of the air-conditioning system is located includes any one of the first ambient temperature range, the second ambient temperature range, and the third ambient temperature range. The first ambient temperature range corresponds to a first set fixed frequency value, the second ambient temperature range corresponds to a second set fixed frequency value, and the third ambient temperature range corresponds to a third set fixed frequency value. For the specific functions and processing of this control unit 104, refer to step S310 for details.

[0147] The control unit 104 is further specifically configured to control the water pump to operate at the current operation frequency of the water pump. As the operation time of the air-conditioning system elapses, if the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold value, the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger gradually approaches 0, and the water-side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold value, then it is determined that a leakage has occurred inside the plate heat exchanger; and, in the case where it is determined that a leakage has occurred inside the plate heat exchanger, a reminder message indicating that a leakage has occurred inside the plate heat exchanger is sent to remind the user to perform maintenance in a timely manner or control the air-conditioning system to stop running to avoid affecting the heat exchange efficiency of the plate heat exchanger or even damaging the compressor, which is beneficial to protecting the air-conditioning system. For the specific functions and processing of this control unit 104, refer to step S320 for details.

[0148] As Figure 9 shown, step 2 further specifically includes: when the water pump is a variable-frequency water pump and the compressor is a fixed-frequency compressor, the anti-leakage measure for the plate heat exchanger, denoted as the third anti-leakage measure, specifically includes steps 51 to 53.

[0149] Step 51: If the water pump used by the user is a variable-frequency water pump and the compressor is a fixed-frequency compressor, then detect whether the difference between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger is less than the pressure difference β under normal working conditions, and detect whether the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger is greater than the change rate Tс under normal conditions: if so, execute step 52, otherwise continue to wait in step 51.

[0150] Step 52: When the difference between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger is less than the pressure difference β under normal operating conditions, and the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger is greater than the change rate Tс under normal conditions, it is necessary to obtain the ambient temperature of the air-conditioning system and fix the operating frequency of the water pump according to the ambient temperature range.

[0151] Specifically, if the ambient temperature range of the air-conditioning system is [Ta, T0), the operating frequency of the water pump is fixed at the frequency fb0, and the water pump is controlled to operate at the frequency fb0. If the ambient temperature range of the air-conditioning system is [Tb, Ta), the operating frequency of the water pump is fixed at the frequency fb1, and the water pump is controlled to operate at the frequency fb1. If the ambient temperature range of the air-conditioning system is [Tmin, Tb), the operating frequency of the water pump is fixed at the frequency fb2, and the water pump is controlled to operate at the frequency fb2. Then step 53 is executed.

[0152] Among them, Ta, T0, Tb, and Tmin represent different temperature values, and fb0, fb1, and fb2 represent different frequency values.

[0153] Step 53: When it is detected that the difference between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger is less than the pressure difference β under normal operating conditions, and as time goes by, the two (i.e., the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger) gradually approach equality, and at the same time, the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger is greater than the change rate Tс under normal conditions, it can be determined that the plate heat exchanger has an internal leak, and an alarm prompt is issued. Among them, the control of step 53 is the same as the control of step 32.

[0154] In some embodiments, the control unit 104 determines whether there is an internal leak in the plate heat exchanger according to at least one of the frequency type of the water pump, the frequency type of the compressor, the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger, the change rate of the water-side inlet water temperature of the plate heat exchanger, and the ambient temperature of the air-conditioning system. It further includes: a third judgment process for determining whether there is an internal leak in the plate heat exchanger when the water pump is a variable-frequency water pump and the compressor is a variable-frequency compressor, which is specifically as follows:

[0155] The control unit 104 is further specifically configured that when the water pump is a variable-frequency water pump and the compressor is a fixed-frequency compressor, as the operation time of the air-conditioning system elapses, if the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold, and the water-side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, then according to the ambient temperature range in which the ambient temperature of the air-conditioning system is located, the operation frequency of the water pump is controlled to be fixed at the fixed frequency value corresponding to this ambient temperature range, so as to obtain the current operation frequency of the water pump. Wherein, the ambient temperature range in which the ambient temperature of the air-conditioning system is located includes any one of the first ambient temperature range, the second ambient temperature range, and the third ambient temperature range. The first ambient temperature range corresponds to a first set fixed frequency value, the second ambient temperature range corresponds to a second set fixed frequency value, and the third ambient temperature range corresponds to a third set fixed frequency value. For the specific functions and processing of this control unit 104, please also refer to step S410.

[0156] The control unit 104 is further specifically configured to control the water pump to operate at the current operation frequency of the water pump. For the specific functions and processing of this control unit 104, please also refer to step S420.

[0157] The control unit 104 is further specifically configured that when the water pump operates at the current operation frequency of the water pump, determine whether there is a leakage inside the plate heat exchanger according to the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger; and, when it is determined that there is a leakage inside the plate heat exchanger, send a reminder message that there is a leakage inside the plate heat exchanger to remind the user to maintain in time or control the air-conditioning system to stop operating to avoid affecting the heat exchange efficiency of the plate heat exchanger or even damaging the compressor, which is beneficial to protecting the air-conditioning system. For the specific functions and processing of this control unit 104, please also refer to step S430.

[0158] In some embodiments, the control unit 104 determines whether there is a leakage inside the plate heat exchanger according to the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger, including:

[0159] The control unit 104 is specifically further configured to control the operating frequency of the compressor to increase by a set frequency corresponding to the pressure range based on the current frequency of the compressor according to the pressure range in which the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger lies, that is, according to the pressure range in which the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger lies among the first pressure range, the second pressure range, and the third pressure range, so as to obtain the first current frequency of the compressor. Wherein, the pressure range in which the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger lies includes any one of the first pressure range, the second pressure range, and the third pressure range. The first pressure range corresponds to a first set frequency by which the operating frequency of the compressor needs to be increased, the second pressure range corresponds to a second set frequency by which the operating frequency of the compressor needs to be increased, and the third pressure range corresponds to a third set frequency by which the operating frequency of the compressor needs to be increased. For the specific functions and processing of this control unit 104, refer to step S510 for details.

[0160] The control unit 104 is specifically further configured to control the compressor to operate at the first current frequency of the compressor. And after the compressor operates at the first current frequency of the compressor for a first set time, determine the change rate of the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger within the first set time, which is denoted as the pressure difference change rate of the plate heat exchanger. The first set time is, for example, time tcmin. For the specific functions and processing of this control unit 104, refer to step S520 for details.

[0161] The control unit 104 is specifically further configured to determine whether there is a leak inside the plate heat exchanger according to the pressure difference change rate of the plate heat exchanger; and, in the case of determining that there is a leak inside the plate heat exchanger, send a reminder message that there is a leak inside the plate heat exchanger to remind the user to perform maintenance in a timely manner or control the air-conditioning system to shut down to avoid affecting the heat exchange efficiency of the plate heat exchanger or even damaging the compressor, which is beneficial to protecting the air-conditioning system. For the specific functions and processing of this control unit 104, refer to step S530 for details.

[0162] In some embodiments, the control unit 104 determines whether there is a leak inside the plate heat exchanger according to the pressure difference change rate of the plate heat exchanger, including:

[0163] The control unit 104 is specifically further configured to control the operating frequency of the compressor to decrease the set frequency corresponding to the pressure change range on the basis of the first current frequency of the compressor according to the pressure change range in which the pressure difference change rate of the plate heat exchanger is located, that is, according to the pressure change range in which the pressure difference change rate of the plate heat exchanger is located in the first pressure change range, the second pressure change range, and the third pressure change range, so as to obtain the second current frequency of the compressor. Wherein, the pressure change range in which the pressure difference change rate of the plate heat exchanger is located includes any one of the pressure change ranges in the first pressure change range, the second pressure change range, and the third pressure change range. The first pressure change range corresponds to a fourth set frequency by which the operating frequency of the compressor needs to be decreased, the second pressure change range corresponds to a fifth set frequency by which the operating frequency of the compressor needs to be decreased, and the third pressure change range corresponds to a sixth set frequency by which the operating frequency of the compressor needs to be decreased. For the specific functions and processes of this control unit 104, refer to step S610 for details.

[0164] The control unit 104 is specifically further configured to control the compressor to operate at the second current frequency of the compressor. After the compressor operates at the second current frequency of the compressor for a second set time, if the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold, and the water side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, it is determined that a leak has occurred inside the plate heat exchanger. And, in the case where it is determined that a leak has occurred inside the plate heat exchanger, a reminder message indicating that a leak has occurred inside the plate heat exchanger is sent to remind the user to perform maintenance in a timely manner or control the air conditioning system to shut down to avoid affecting the heat exchange efficiency of the plate heat exchanger or even damaging the compressor, which is beneficial to protecting the air conditioning system; otherwise, it is considered that no leak has occurred inside the plate heat exchanger and the operating frequency of the compressor is too low. That is, if the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold, and the water side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, it is determined that the reason why the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold, and the water side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold is that a leak has occurred inside the plate heat exchanger. And, in the case where it is determined that a leak has occurred inside the plate heat exchanger, a reminder message indicating that a leak has occurred inside the plate heat exchanger is sent to remind the user to perform maintenance in a timely manner or control the air conditioning system to shut down to avoid affecting the heat exchange efficiency of the plate heat exchanger or even damaging the compressor, which is beneficial to protecting the air conditioning system. Otherwise, if the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger is not still less than the set pressure difference threshold, and the water side inlet temperature change rate of the plate heat exchanger is not still greater than the set temperature change threshold, it is determined that the reason why the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold, and the water side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold is that the operating frequency of the compressor is too low. Among them, the first set time is such as time tkmin. For the specific functions and processes of this control unit 104, refer to step S620

[0165] As Figure 9 As shown, step 2 specifically further includes: in the case where the water pump is a variable frequency water pump and the compressor is a variable frequency compressor, the anti-leakage measure of the plate heat exchanger, denoted as the fourth anti-leakage measure, specifically includes steps 61 to 62.

[0166] Step 61: If the water pump used by the user is a variable-frequency water pump and the compressor is a variable-frequency compressor, then detect whether the difference between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger is less than the pressure difference β under normal operating conditions, and detect whether the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger is greater than the change rate Tс under normal conditions. If so, execute Step 62; otherwise, continue to wait in Step 61.

[0167] Step 62: When it is detected that the difference between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger is less than the pressure difference β under normal operating conditions, and the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger is greater than the change rate Tс under normal conditions, it is necessary to obtain the ambient temperature of the air-conditioning system and fix the operating frequency of the water pump according to the ambient temperature range.

[0168] Specifically, if the ambient temperature range of the air-conditioning system is [Ta, T0), then fix the operating frequency of the water pump as frequency fb0 and control the water pump to operate at frequency fb0. If the ambient temperature range of the air-conditioning system is [Tb, Ta), then fix the operating frequency of the water pump as frequency fb1 and control the water pump to operate at frequency fb1. If the ambient temperature range of the air-conditioning system is [Tmin, Tb), then fix the operating frequency of the water pump as frequency fb2 and control the water pump to operate at frequency fb2. Then execute Step 63.

[0169] Step 63: When it is detected that the difference between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger is less than the pressure difference β under normal operating conditions, and the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger is greater than the change rate Tс under normal conditions, there are two possibilities: one is that the compressor operating frequency is low, and the other is that the plate heat exchanger leaks. At this time, it is necessary to compare whether the operating frequency of the compressor is within the interval of the set frequency interval (b, fmax], that is, to determine whether the operating frequency of the compressor is greater than the set frequency b and less than the set maximum frequency fmax. If so, it is determined that the plate heat exchanger leaks and an alarm prompt is issued. If not, execute Step 64.

[0170] Step 64: Specifically, it is controlled according to the following device, that is, it includes Step 641 and Step 642.

[0171] Step 641: According to the interval where the difference between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger is located, the operating frequency of the compressor is increased to different degrees.

[0172] Specifically, if ΔPr - ΔPw ∈ (0, δ], the operating frequency of the compressor is controlled to increase by frequency fc0. If ΔPr - ΔPw ∈ (δ, θ], the operating frequency of the compressor is controlled to increase by frequency fc1. If ΔPr - ΔPw ∈ (θ, β], the operating frequency of the compressor is controlled to increase by frequency fc2. Wherein, δ, θ, and β respectively represent different pressure values, and fc0, fc1, and fc2 respectively represent different frequency values.

[0173] Step 642: After the running time tcmin, determine the change rate (ΔPr - ΔPw) / Δt of the difference between the refrigerant side pressure difference ΔPr and the water side pressure difference ΔPw of the plate heat exchanger within the time Δt, that is, judge the pressure difference change rate of the refrigerant side pressure difference ΔPr and the water side pressure difference ΔPw of the plate heat exchanger, and make appropriate adjustments to the operating frequency of the compressor.

[0174] Specifically, if (ΔPr - ΔPw) / Δt > pressure vc, the operating frequency of the compressor is controlled to decrease by frequency fd0. If (ΔPr - ΔPw) / Δt ∈ (vd, vc), the operating frequency of the compressor is controlled to maintain the current frequency unchanged. If (ΔPr - ΔPw) / Δt < pressure vd, the operating frequency of the compressor is controlled to increase by frequency fd2.

[0175] After the running time tkmin, if it is detected that the difference ΔPr - ΔPw between the refrigerant side pressure difference ΔPr and the water side pressure difference ΔPw of the plate heat exchanger is greater than the pressure difference β under normal working conditions or the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger is less than the change rate Tс under normal conditions, it is considered that the reason for the difference between the refrigerant side pressure difference ΔPr and the water side pressure difference ΔPw of the plate heat exchanger in step 42 being less than the pressure difference β under normal working conditions and the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger being greater than the change rate Tс under normal conditions is due to the low operating frequency of the compressor. On the contrary, if it is detected that the difference ΔPr - ΔPw between the refrigerant side pressure difference ΔPr and the water side pressure difference ΔPw of the plate heat exchanger is less than the pressure difference β under normal working conditions and the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger is greater than the change rate Tс under normal conditions, it is considered that the reason for the difference between the refrigerant side pressure difference ΔPr and the water side pressure difference ΔPw of the plate heat exchanger in step 42 being less than the pressure difference β under normal working conditions and the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger being greater than the change rate Tс under normal conditions is due to internal leakage of the plate heat exchanger, and an alarm prompt is issued. Among them, the control of steps 63 and 64 is the same as the control of steps 42 and 43.

[0176] Since the processing and functions implemented by the device in this embodiment are basically corresponding to the embodiments, principles and examples of the foregoing method, for the details not described in this embodiment, reference may be made to the relevant descriptions in the foregoing embodiments and will not be elaborated here.

[0177] By adopting the technical solution of the present invention, by detecting the refrigerant-side pressure difference ΔPr of the plate heat exchanger, the water-side pressure difference ΔPw of the plate heat exchanger, and the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger, when it is detected that the difference between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger is less than the pressure difference β under normal working conditions, and the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger is greater than the change rate Tс under normal conditions, according to whether the water pump is a fixed-frequency water pump or a variable-frequency water pump, and whether the compressor is a fixed-frequency compressor or a variable-frequency compressor, the leakage situation inside the plate heat exchanger is determined. If it is determined that there is a leakage inside the plate heat exchanger, a reminder message (such as an alarm) is sent. If it is determined that there is no leakage inside the plate heat exchanger, the frequency of the compressor is adjusted to avoid leakage inside the plate heat exchanger or further improve the confirmation accuracy of the leakage situation inside the plate heat exchanger, thereby avoiding damage to the compressor caused by liquid accumulation due to serious internal leakage of the plate heat exchanger, and thus avoiding damage to the air-conditioning system.

[0178] According to an embodiment of the present invention, there is also provided an air-conditioning system corresponding to the control device of the air-conditioning system. The air-conditioning system may include: the control device of the air-conditioning system described above.

[0179] Since the processing and functions implemented by the air-conditioning system in this embodiment are basically corresponding to the embodiments, principles and examples of the foregoing device, for the details not described in this embodiment, reference may be made to the relevant descriptions in the foregoing embodiments and will not be elaborated here.

[0180] Adopting the technical solution of the present invention, by detecting the refrigerant-side pressure difference ΔPr of the plate heat exchanger, the water-side pressure difference ΔPw of the plate heat exchanger, and the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger, when it is detected that the difference between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger is less than the pressure difference β under normal working conditions, and the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger is greater than the change rate Tс under normal conditions, according to whether the water pump is a fixed-frequency water pump or a variable-frequency water pump, and whether the compressor is a fixed-frequency compressor or a variable-frequency compressor, determine the leakage situation inside the plate heat exchanger. If it is determined that there is a leakage inside the plate heat exchanger, a reminder message (such as an alarm) is sent. If it is determined that there is no leakage inside the plate heat exchanger, the frequency of the compressor is adjusted to avoid leakage inside the plate heat exchanger or further improve the accuracy of confirming the leakage situation inside the plate heat exchanger, avoid the plate heat exchanger from leaking under the impact of the refrigerant for a long time, and avoid affecting the heat exchange effect of the plate heat exchanger due to internal leakage of the plate heat exchanger.

[0181] According to an embodiment of the present invention, there is also provided a storage medium corresponding to the control method of the air-conditioning system. The storage medium includes a stored program, wherein when the program runs, it controls the device where the storage medium is located to execute the control method of the air-conditioning system described above.

[0182] Since the processing and functions implemented by the storage medium of this embodiment are basically corresponding to the embodiments, principles, and examples of the foregoing method, for the details not described in the description of this embodiment, reference may be made to the relevant descriptions in the foregoing embodiments, and no further elaboration will be provided here.

[0183] Adopting the technical solution of the present invention, by detecting the refrigerant-side pressure difference ΔPr of the plate heat exchanger, the water-side pressure difference ΔPw of the plate heat exchanger, and the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger, when it is detected that the difference between the refrigerant-side pressure difference ΔPr and the water-side pressure difference ΔPw of the plate heat exchanger is less than the pressure difference β under normal working conditions, and the change rate ΔT_w_in / Δt of the inlet water temperature on the water side of the plate heat exchanger is greater than the change rate Tс under normal conditions, according to whether the water pump is a fixed-frequency water pump or a variable-frequency water pump, and whether the compressor is a fixed-frequency compressor or a variable-frequency compressor, determine the leakage situation inside the plate heat exchanger. If it is determined that there is a leakage inside the plate heat exchanger, a reminder message (such as an alarm) is sent. If it is determined that there is no leakage inside the plate heat exchanger, the frequency of the compressor is adjusted to avoid leakage inside the plate heat exchanger or further improve the accuracy of confirming the leakage situation inside the plate heat exchanger. By timely identifying the state of the plate heat exchanger and taking corresponding measures in advance, avoid the plate heat exchanger from leaking under the impact of the refrigerant for a long time.

[0184] In summary, it is easily understandable to those skilled in the art that, on the premise of no conflict, the above-mentioned advantageous ways can be freely combined and superimposed.

[0185] The above are only embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the scope of the claims of the present invention.

Claims

1. A control method for an air conditioning system, characterized in that, The air conditioning system has a compressor, an outdoor heat exchanger, and an indoor heat exchanger; the indoor heat exchanger is a plate heat exchanger, the plate heat exchanger has a refrigerant heat exchange pipeline and a water heat exchange pipeline, and heat exchange can be carried out between the refrigerant heat exchange pipeline and the water heat exchange pipeline; the compressor, the outdoor heat exchanger, and the refrigerant heat exchange pipeline form a refrigerant heat exchange loop through a refrigerant circulation pipeline; the water heat exchange pipeline and a water pump, a water tank, and a heat-using device arranged in the space where the air conditioning system is located form a water heat exchange loop through a water circulation pipeline; the control method of the air conditioning system includes: When the air conditioning system is running after startup, obtain the inlet and outlet pressure difference of the refrigerant heat exchange pipeline in the plate heat exchanger, which is recorded as the refrigerant side pressure difference of the plate heat exchanger; obtain the inlet and outlet pressure difference of the water heat exchange pipeline in the plate heat exchanger, which is recorded as the water side pressure difference of the plate heat exchanger; obtain the change rate of the inlet water temperature of the water heat exchange pipeline in the plate heat exchanger, which is recorded as the water side inlet water temperature change rate of the plate heat exchanger; and obtain the ambient temperature of the air conditioning system. When the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger is less than a set pressure difference threshold, and the water side inlet water temperature change rate of the plate heat exchanger is greater than a set temperature change threshold, determine whether there is a leak inside the plate heat exchanger according to at least one of the frequency type of the water pump, the frequency type of the compressor, the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger, the water side inlet water temperature change rate of the plate heat exchanger, and the ambient temperature of the air conditioning system; and, when it is determined that there is a leak inside the plate heat exchanger, send a reminder message that there is a leak inside the plate heat exchanger; the frequency type of the water pump is fixed frequency or variable frequency; the frequency type of the compressor is fixed frequency or variable frequency.

2. The control method of the air conditioning system according to claim 1, wherein, Determine whether there is a leak inside the plate heat exchanger according to at least one of the frequency type of the water pump, the frequency type of the compressor, the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger, the water side inlet water temperature change rate of the plate heat exchanger, and the ambient temperature of the air conditioning system, including: When the water pump is a fixed-frequency water pump and the compressor is a fixed-frequency compressor, when the water pump runs at its own fixed frequency, as the running time of the air conditioning system progresses, if the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold, the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger gradually approaches 0, and the water side inlet water temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, it is determined that there is a leak inside the plate heat exchanger.

3. The control method of the air conditioning system according to claim 1, wherein Determine whether there is a leakage inside the plate heat exchanger based on at least one of the frequency type of the water pump, the frequency type of the compressor, the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger, the water-side inlet temperature change rate of the plate heat exchanger, and the ambient temperature of the air-conditioning system, further including: When the water pump is a constant-frequency water pump and the compressor is a constant-frequency compressor, as the operation time of the air-conditioning system progresses, if the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold and the water-side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, determine whether the operating frequency of the compressor is greater than the first set frequency and less than or equal to the maximum set frequency; If it is determined that the operating frequency of the compressor is greater than the first set frequency and less than or equal to the maximum set frequency, determine whether there is a leakage inside the plate heat exchanger based on the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger.

4. The control method of the air conditioning system according to claim 1, wherein, Determine whether there is a leakage inside the plate heat exchanger based on at least one of the frequency type of the water pump, the frequency type of the compressor, the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger, the water-side inlet temperature change rate of the plate heat exchanger, and the ambient temperature of the air-conditioning system, further including: When the water pump is a variable-frequency water pump and the compressor is a constant-frequency compressor, as the operation time of the air-conditioning system progresses, if the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold and the water-side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, control the operating frequency of the water pump to be fixed at the fixed frequency value corresponding to the ambient temperature range where the ambient temperature of the air-conditioning system is located, to obtain the current operating frequency of the water pump; wherein, the ambient temperature range where the ambient temperature of the air-conditioning system is located includes any one of the first ambient temperature range, the second ambient temperature range, and the third ambient temperature range; the first ambient temperature range corresponds to the first set fixed frequency value, the second ambient temperature range corresponds to the second set fixed frequency value, and the third ambient temperature range corresponds to the third set fixed frequency value; Control the water pump to operate at the current operating frequency of the water pump. As the operation time of the air-conditioning system progresses, if the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold, the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger gradually approaches 0, and the water-side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, determine that there is a leakage inside the plate heat exchanger.

5. The control method of the air conditioning system according to claim 1, characterized in that, Based on at least one of the frequency type of the water pump, the frequency type of the compressor, the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger, the water side inlet temperature change rate of the plate heat exchanger, and the ambient temperature of the air conditioning system, it is determined whether there is a leak inside the plate heat exchanger, and it further includes: When the water pump is a variable frequency water pump and the compressor is a fixed frequency compressor, as the operation time of the air conditioning system progresses, if the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold and the water side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, then according to the ambient temperature range in which the ambient temperature of the air conditioning system is located, the operation frequency of the water pump is controlled to be fixed at the fixed frequency value corresponding to this ambient temperature range, and the current operation frequency of the water pump is obtained; wherein, the ambient temperature range in which the ambient temperature of the air conditioning system is located includes any one of the first ambient temperature range, the second ambient temperature range, and the third ambient temperature range; the first ambient temperature range corresponds to the first set fixed frequency value, the second ambient temperature range corresponds to the second set fixed frequency value, and the third ambient temperature range corresponds to the third set fixed frequency value; Control the water pump to operate at the current operation frequency of the water pump; When the water pump operates at the current operation frequency of the water pump, determine whether there is a leak inside the plate heat exchanger according to the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger.

6. The control method of the air-conditioning system according to claim 3 or 5, characterized in that, Determining whether there is a leak inside the plate heat exchanger according to the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger includes: According to the pressure range of the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger, control the operation frequency of the compressor to increase by the set frequency corresponding to this pressure range on the basis of the current frequency of the compressor, and obtain the first current frequency of the compressor; wherein, the pressure range of the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger includes any one of the first pressure range, the second pressure range, and the third pressure range; the first pressure range corresponds to the first set frequency by which the operation frequency of the compressor needs to be increased, the second pressure range corresponds to the second set frequency by which the operation frequency of the compressor needs to be increased, and the third pressure range corresponds to the third set frequency by which the operation frequency of the compressor needs to be increased; Control the compressor to operate at the first current frequency of the compressor; and after the compressor operates at the first current frequency of the compressor for the first set time, determine the change rate of the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger within the first set time, and record it as the pressure difference change rate of the plate heat exchanger; Determine whether there is a leakage inside the plate heat exchanger according to the pressure difference change rate of the plate heat exchanger.

7. The control method of the air conditioning system according to claim 6, characterized in that, Determine whether there is a leakage inside the plate heat exchanger according to the pressure difference change rate of the plate heat exchanger, including: According to the pressure change interval where the pressure difference change rate of the plate heat exchanger is located, control the operating frequency of the compressor to decrease the set frequency corresponding to this pressure change interval based on the first current frequency of the compressor, so as to obtain the second current frequency of the compressor; wherein, the pressure change interval where the pressure difference change rate of the plate heat exchanger is located includes any one of the first pressure change interval, the second pressure change interval, and the third pressure change interval; the first pressure change interval corresponds to the fourth set frequency by which the operating frequency of the compressor needs to be decreased, the second pressure change interval corresponds to the fifth set frequency by which the operating frequency of the compressor needs to be decreased, and the third pressure change interval corresponds to the sixth set frequency by which the operating frequency of the compressor needs to be decreased; Control the compressor to operate at the second current frequency of the compressor; and after the compressor operates at the second current frequency of the compressor for a second set time, if the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold, and the water side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, then determine that there is a leakage inside the plate heat exchanger.

8. A control device for an air conditioning system, characterized in that, The air conditioning system has a compressor, an outdoor heat exchanger, and an indoor heat exchanger; the indoor heat exchanger is a plate heat exchanger, the plate heat exchanger has a refrigerant heat exchange pipeline and a water heat exchange pipeline, and heat exchange can be carried out between the refrigerant heat exchange pipeline and the water heat exchange pipeline; the compressor, the outdoor heat exchanger, and the refrigerant heat exchange pipeline form a refrigerant heat exchange loop through a refrigerant circulation pipeline; the water heat exchange pipeline forms a water heat exchange loop through a water circulation pipeline with a water pump, a water tank, and a heat-using device arranged in the space where the air conditioning system is located; the control device of the air conditioning system includes: An acquisition unit, configured to, when the air conditioning system is started and running, acquire the inlet and outlet pressure difference of the refrigerant heat exchange pipeline in the plate heat exchanger, denoted as the refrigerant side pressure difference of the plate heat exchanger; acquire the inlet and outlet pressure difference of the water heat exchange pipeline in the plate heat exchanger, denoted as the water side pressure difference of the plate heat exchanger; acquire the change rate of the inlet water temperature of the water heat exchange pipeline in the plate heat exchanger, denoted as the water side inlet temperature change rate of the plate heat exchanger; and acquire the ambient temperature of the air conditioning system. The control unit is configured to determine whether there is a leak inside the plate heat exchanger based on at least one of the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger, the water side inlet temperature change rate of the plate heat exchanger, and the ambient temperature of the air conditioning system, when the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger is less than a set pressure difference threshold value and the water side inlet temperature change rate of the plate heat exchanger is greater than a set temperature change threshold value; and, when it is determined that there is a leak inside the plate heat exchanger, send a reminder message indicating that there is a leak inside the plate heat exchanger; the frequency type of the water pump is fixed frequency or variable frequency; the frequency type of the compressor is fixed frequency or variable frequency.

9. The control device of the air conditioning system according to claim 8, characterized in that, The control unit determines whether there is a leak inside the plate heat exchanger based on at least one of the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger, the water side inlet temperature change rate of the plate heat exchanger, and the ambient temperature of the air conditioning system, according to the frequency type of the water pump and the frequency type of the compressor, including: When the water pump is a fixed-frequency water pump and the compressor is a fixed-frequency compressor, when the water pump operates at its own fixed frequency, as the operation time of the air conditioning system progresses, if the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold value, the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger gradually approaches 0, and the water side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold value, it is determined that there is a leak inside the plate heat exchanger.

10. The control device of the air conditioning system according to claim 8, characterized in that, The control unit determines whether there is a leak inside the plate heat exchanger based on at least one of the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger, the water side inlet temperature change rate of the plate heat exchanger, and the ambient temperature of the air conditioning system, according to the frequency type of the water pump and the frequency type of the compressor, and further includes: When the water pump is a fixed-frequency water pump and the compressor is a fixed-frequency compressor, as the operation time of the air conditioning system progresses, if the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold value and the water side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold value, it is determined whether the operating frequency of the compressor is greater than a first set frequency and less than or equal to the maximum set frequency; If it is determined that the operating frequency of the compressor is greater than the first set frequency and less than or equal to the maximum set frequency, determine whether there is a leak inside the plate heat exchanger according to the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger.

11. The control device of the air-conditioning system according to claim 8, characterized in that, The control unit determines whether there is a leak inside the plate heat exchanger based on at least one of the frequency type of the water pump, the frequency type of the compressor, the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger, the water-side inlet temperature change rate of the plate heat exchanger, and the ambient temperature of the air conditioning system, and further includes: When the water pump is a variable-frequency water pump and the compressor is a fixed-frequency compressor, as the operation time of the air conditioning system progresses, if the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold and the water-side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, then according to the ambient temperature range in which the ambient temperature of the air conditioning system is located, control the operation frequency of the water pump to be fixed at the fixed frequency value corresponding to this ambient temperature range to obtain the current operation frequency of the water pump; wherein, the ambient temperature range in which the ambient temperature of the air conditioning system is located includes any one of the first ambient temperature range, the second ambient temperature range, and the third ambient temperature range; the first ambient temperature range corresponds to a first set fixed frequency value, the second ambient temperature range corresponds to a second set fixed frequency value, and the third ambient temperature range corresponds to a third set fixed frequency value; Control the water pump to operate at the current operation frequency of the water pump. As the operation time of the air conditioning system progresses, if the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold, the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger gradually approaches 0, and the water-side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, then determine that there is a leak inside the plate heat exchanger.

12. The control device of the air conditioning system according to claim 8, characterized in that, The control unit determines whether there is a leak inside the plate heat exchanger based on at least one of the frequency type of the water pump, the frequency type of the compressor, the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger, the water-side inlet temperature change rate of the plate heat exchanger, and the ambient temperature of the air conditioning system, and further includes: When the water pump is a variable-frequency water pump and the compressor is a fixed-frequency compressor, as the operation time of the air-conditioning system progresses, if the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold, and the water-side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, then according to the ambient temperature range in which the ambient temperature of the air-conditioning system is located, control the operating frequency of the water pump to be fixed at the fixed frequency value corresponding to this ambient temperature range to obtain the current operating frequency of the water pump; wherein, the ambient temperature range in which the ambient temperature of the air-conditioning system is located includes any one of the ambient temperature ranges of the first ambient temperature range, the second ambient temperature range, and the third ambient temperature range; the first ambient temperature range corresponds to the first set fixed frequency value, the second ambient temperature range corresponds to the second set fixed frequency value, and the third ambient temperature range corresponds to the third set fixed frequency value; Control the water pump to operate at the current operating frequency of the water pump; When the water pump operates at the current operating frequency of the water pump, determine whether there is a leakage inside the plate heat exchanger according to the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger.

13. The control device of the air conditioning system according to claim 10 or 12, characterized in that, The control unit determines whether there is a leakage inside the plate heat exchanger according to the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger, including: According to the pressure range of the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger, control the operating frequency of the compressor to increase by the set frequency corresponding to this pressure range on the basis of the current frequency of the compressor to obtain the first current frequency of the compressor; wherein, the pressure range of the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger includes any one of the first pressure range, the second pressure range, and the third pressure range; the first pressure range corresponds to the first set frequency by which the operating frequency of the compressor needs to be increased, the second pressure range corresponds to the second set frequency by which the operating frequency of the compressor needs to be increased, and the third pressure range corresponds to the third set frequency by which the operating frequency of the compressor needs to be increased; Control the compressor to operate at the first current frequency of the compressor; and after the compressor operates at the first current frequency of the compressor for the first set time, determine the change rate of the difference between the refrigerant-side pressure difference and the water-side pressure difference of the plate heat exchanger within the first set time, and record it as the pressure difference change rate of the plate heat exchanger; Determine whether there is a leakage inside the plate heat exchanger according to the pressure difference change rate of the plate heat exchanger.

14. The control device of the air conditioning system according to claim 13, characterized in that, The control unit determines whether there is a leakage inside the plate heat exchanger according to the pressure difference change rate of the plate heat exchanger, including: According to the pressure change interval in which the pressure difference change rate of the plate heat exchanger is located, control the operating frequency of the compressor to decrease the set frequency corresponding to this pressure change interval based on the first current frequency of the compressor, so as to obtain the second current frequency of the compressor; wherein, the pressure change interval in which the pressure difference change rate of the plate heat exchanger is located includes any one of the pressure change intervals: the first pressure change interval, the second pressure change interval, and the third pressure change interval; the first pressure change interval corresponds to a fourth set frequency by which the operating frequency of the compressor needs to be decreased, the second pressure change interval corresponds to a fifth set frequency by which the operating frequency of the compressor needs to be decreased, and the third pressure change interval corresponds to a sixth set frequency by which the operating frequency of the compressor needs to be decreased; Control the compressor to operate at the second current frequency of the compressor; and after the compressor operates at the second current frequency of the compressor for a second set time, if the difference between the refrigerant side pressure difference and the water side pressure difference of the plate heat exchanger is still less than the set pressure difference threshold, and the water side inlet temperature change rate of the plate heat exchanger is still greater than the set temperature change threshold, then determine that a leakage has occurred inside the plate heat exchanger.

15. An air conditioning system, characterized in that, Comprising: The control device of the air conditioning system according to any one of claims 8 to 14.

16. A storage medium, characterized in that, The storage medium includes a stored program, wherein when the program runs, it controls the device where the storage medium is located to execute the control method of the air conditioning system according to any one of claims 1 to 7.

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