Control method and system of heat pump system

Abstract

The invention relates to the technical field of heat pump equipment, and discloses a control method and system for a heat pump system.The control method comprises the steps that in response to a shutdown instruction, if an enthalpy increasing electronic expansion valve is opened, the expected fluctuation intensity corresponding to a compressor is determined based on the current environment temperature, the current water inlet temperature and the current compression frequency of the compressor; based on the expected fluctuation intensity, the closing rate of the enthalpy-increasing electronic expansion valve and the frequency reduction rate of the compressor are determined; and controlling the enthalpy-increasing electronic expansion valve and the compressor based on the closing rate and the frequency reduction rate. Thus, when the heat pump system receives a shutdown instruction but the enthalpy-increasing electronic expansion valve is opened, the influence of closing of the enthalpy-increasing electronic expansion valve on the compressor is divided into different expected fluctuation intensities according to different working conditions, and therefore the closing rate of the enthalpy-increasing electronic expansion valve and the frequency reduction rate of the compressor are adjusted; and excessive influence on the compressor when the enthalpy-increasing electronic expansion valve is closed is avoided, normal pressure relief of the compressor is guaranteed, and therefore the reliability of the system is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of heat pump equipment, and in particular to a control method and system for a heat pump system. Background Art

[0002] When a heat pump unit with jet reheat receives a shutdown command, its reheat electronic expansion valve will be closed directly, while the compressor is still in the frequency reduction process. This means that the system pressure may not be released in time and the compression ratio may be too high. When the compression ratio exceeds the reliable operating range of the compressor, it will affect the service life of the compressor and greatly reduce its reliability. Summary of the invention

[0003] The first technical problem solved by the present invention is to provide a control method for a heat pump system, which effectively solves the problem that the shutdown process of the current heat pump unit will reduce the reliability of the system.

[0004] The second technical problem solved by the present invention is to provide a control system for a heat pump system, which effectively solves the problem that the shutdown process of the current heat pump unit will reduce the reliability of the system.

[0005] The first technical problem mentioned above is solved by the following technical solution:

[0006] A control method for a heat pump system, comprising:

[0007] In response to a shutdown instruction for the heat pump system, if the enthalpy-increasing electronic expansion valve is opened, the expected fluctuation intensity corresponding to the compressor is determined based on the current ambient temperature, the current inlet water temperature and the current compression frequency of the compressor; the expected fluctuation intensity is used to characterize the impact of the closing of the enthalpy-increasing electronic expansion valve on the compressor;

[0008] Based on the expected fluctuation intensity, determine the closing rate of the enthalpy-increasing electronic expansion valve and the frequency reduction rate of the compressor;

[0009] The enthalpy-increasing electronic expansion valve and the compressor are controlled based on the closing rate and the frequency reduction rate.

[0010] Compared with the background technology, the control method of the heat pump system of the present invention has the following beneficial effects: when the heat pump system receives a shutdown command but the reheat electronic expansion valve is open, the expected fluctuation intensity corresponding to the compressor is determined based on the current ambient temperature, the current water inlet temperature and the current compression frequency of the compressor, and the closing rate of the reheat electronic expansion valve and the frequency reduction rate of the compressor are determined according to the expected fluctuation intensity of the compressor, that is, the impact of the closing of the reheat electronic expansion valve on the compressor under different working conditions is divided into different expected fluctuation intensities, and the closing rate of the reheat electronic expansion valve and the frequency reduction rate of the compressor are adjusted accordingly to ensure that the compressor can relieve pressure normally, avoid low system reliability caused by the shutdown process of the heat pump system, and thus ensure system reliability.

[0011] In one embodiment, determining the expected fluctuation intensity corresponding to the compressor based on the current ambient temperature, the current water inlet temperature, and the current compression frequency of the compressor includes:

[0012] If the current ambient temperature is greater than the first preset temperature, the current water inlet temperature is less than the second preset temperature, and the current compression frequency is less than the preset frequency, then the expected fluctuation intensity is determined to be the first intensity;

[0013] If the current ambient temperature is less than or equal to the first preset temperature, and / or the current water inlet temperature is greater than or equal to the second preset temperature, and / or the current compression frequency is greater than or equal to the preset frequency, the expected fluctuation intensity is determined to be the second intensity; the first intensity is less than the second intensity.

[0014] In one embodiment, based on the expected fluctuation intensity, determining the closing rate of the enthalpy-increasing electronic expansion valve and the frequency reduction rate of the compressor includes:

[0015] If the expected fluctuation intensity is the second intensity, the closing rate is determined to be the first closing rate, and the frequency reduction rate is determined to be the first frequency reduction rate; the first closing rate is determined based on the current opening degree, frequency reduction rate and current compression frequency of the enthalpy increase electronic expansion valve.

[0016] In one embodiment, the first closing rate is determined based on the current opening degree, frequency reduction rate and current compression frequency of the enthalpy increasing electronic expansion valve, including:

[0017] Based on the current opening, the current compression frequency and the target compression frequency, a mapping ratio corresponding to the closing rate and the frequency reduction rate is determined; the target compression frequency is the compression frequency of the compressor when the preset enthalpy-increasing electronic expansion valve is closed;

[0018] Based on the mapping ratio and the frequency reduction rate, a first shutdown rate is determined.

[0019] In one embodiment, based on the current opening degree, the current compression frequency and the target compression frequency, determining a mapping ratio corresponding to the closing rate and the frequency reduction rate includes:

[0020] Subtract the current compression frequency from the target compression frequency to obtain a frequency difference;

[0021] Divide the current opening by the frequency difference to obtain the mapping ratio.

[0022] In one embodiment, based on the expected fluctuation intensity, determining the closing rate of the enthalpy-increasing electronic expansion valve and the frequency reduction rate of the compressor includes:

[0023] If the expected fluctuation intensity is the first intensity, the closing rate is determined to be the second closing rate, and the frequency reduction rate is the second frequency reduction rate; the second frequency reduction rate is greater than the first frequency reduction rate.

[0024] In one embodiment, the enthalpy increasing electronic expansion valve and the compressor are controlled based on the closing rate and the frequency reduction rate, including:

[0025] The enthalpy increase electronic expansion valve is controlled to close at a closing rate, and the compressor is controlled to reduce frequency at a frequency reduction rate until it is closed.

[0026] In one embodiment, the method further comprises:

[0027] In response to the shutdown command, if the enthalpy-increasing electronic expansion valve is closed, determining the frequency reduction rate of the compressor to be a third frequency reduction rate;

[0028] Control the compressor to reduce frequency according to the frequency reduction rate until it is turned off.

[0029] In one embodiment, after controlling the compressor to reduce the frequency according to the frequency reduction rate to shut down, the method further includes:

[0030] Control the fan to stop running;

[0031] Adjust the opening of the thermostatic expansion valve to the preset opening.

[0032] The above second technical problem is solved by the following technical solution:

[0033] A control system for a heat pump system comprises a controller, wherein the controller is used to execute any of the control methods for the heat pump system as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0035] Figure 1It is a structural schematic diagram of a heat pump unit;

[0036] Figure 2 is a flow chart of a control method of a heat pump system according to an embodiment of the present invention;

[0037] Figure 3 is a flow chart of determining expected fluctuation intensity in a control method of a heat pump system according to an embodiment of the present invention;

[0038] Figure 4 It is a flow chart of determining a first closing rate in a control method of a heat pump system according to an embodiment of the present invention.

[0039] Description of reference numerals:

[0040] 1. Compressor; 2. Enthalpy-increasing electronic expansion valve; 3. Temperature-regulating expansion valve; 4. Enthalpy-increasing plate heat exchanger; 5. Air-side heat exchanger; 6. Fan; 7. Water-side heat exchanger; 8. Liquid storage tank; 9. Four-way valve; 10. Gas-liquid separator. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0042] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the feature. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0043] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0044] As described in the background technology, when a heat pump unit with jet reheat receives a shutdown command, the reheat electronic expansion valve is directly closed, resulting in a situation where the system pressure cannot be released in time and the compression ratio is too high, resulting in reduced system reliability.

[0045] Based on this, an embodiment of the present invention provides a control method for a heat pump system. In response to a shutdown instruction for the heat pump system, if the enthalpy increasing electronic expansion valve is opened, the expected fluctuation intensity corresponding to the compressor is determined based on the current ambient temperature, the current water inlet temperature and the current compression frequency of the compressor; the expected fluctuation intensity is used to characterize the impact of the closing of the enthalpy increasing electronic expansion valve on the compressor; based on the expected fluctuation intensity, the closing rate of the enthalpy increasing electronic expansion valve and the frequency reduction rate of the compressor are determined; based on the closing rate and the frequency reduction rate, the enthalpy increasing electronic expansion valve and the compressor are controlled. In this way, when the heat pump system receives a shutdown command but the reheat electronic expansion valve is open, the expected fluctuation intensity corresponding to the compressor is determined based on the current ambient temperature, the current inlet water temperature and the current compression frequency of the compressor, and the closing rate of the reheat electronic expansion valve and the frequency reduction rate of the compressor are determined according to the expected fluctuation intensity of the compressor. That is, the impact of the closing of the reheat electronic expansion valve on the compressor under different working conditions is divided into different expected fluctuation intensities, and the closing rate of the reheat electronic expansion valve and the frequency reduction rate of the compressor are adjusted accordingly to ensure that the compressor can relieve pressure normally, avoid low system reliability caused by the shutdown process of the heat pump system, and thus ensure system reliability.

[0046] Combine the following Figures 1 to 4 , describing an embodiment of the present invention.

[0047] The control method of the heat pump system provided in the embodiment of the present invention can be applied to a heat pump unit with jet enthalpy increase. Figure 1 is a schematic diagram of the structure of a heat pump unit. The control method of the heat pump system provided by the embodiment of the present invention can be applied to Figure 1 In the heat pump unit shown in Figure 1 As shown, the heat pump unit includes: a compressor 1, an enthalpy-increasing electronic expansion valve 2, a temperature-regulating expansion valve 3, an enthalpy-increasing plate heat exchanger 4, an air-side heat exchanger 5, a fan 6, a water-side heat exchanger 7, and a liquid storage tank 8. Among them, the compressor 1, the water-side heat exchanger 7, the liquid storage tank 8, the enthalpy-increasing plate heat exchanger 4, the enthalpy-increasing electronic expansion valve 2, the temperature-regulating expansion valve 3, the air-side heat exchanger 5, and the compressor 1 are connected in sequence to form a temperature-regulating cycle.

[0048] In the embodiment of the present invention, one of the enthalpy-increasing temperature inlets of the enthalpy-increasing plate heat exchanger 4 is connected to one end of the temperature-regulating expansion valve 3, and the other end of the temperature-regulating expansion valve 3 is connected to the air-side heat exchanger 5. The enthalpy-increasing electronic expansion valve 2 is connected between the enthalpy-increasing plate heat exchanger 4 and the temperature-regulating expansion valve 3, wherein the enthalpy-increasing electronic expansion valve 2 is connected to another enthalpy-increasing temperature inlet of the enthalpy-increasing plate heat exchanger 4. The fan 6 is connected to the air-side heat exchanger 5.

[0049] In one embodiment, Figure 1As shown, the heat pump unit further includes a four-way valve 9 and a gas-liquid separator 10. The four-way valve 9 is respectively connected to the air side heat exchanger 5, the compressor 1, the gas-liquid separator 10 and the water side heat exchanger 7; the gas-liquid separator 10 is connected to the compressor 1.

[0050] According to an embodiment of the present invention, on the one hand, a control method for a heat pump system is provided. Figure 2 is a flow chart of a control method of a heat pump system according to an embodiment of the present invention, such as Figure 2 As shown, the method includes:

[0051] Step 210: In response to a shutdown command for the heat pump system, if the enthalpy-increasing electronic expansion valve is opened, the expected fluctuation intensity corresponding to the compressor is determined based on the current ambient temperature, the current inlet water temperature and the current compression frequency of the compressor.

[0052] In the embodiment of the present invention, the shutdown command triggers the shutdown process of the heat pump system, and shuts down all components in the heat pump system; among them, since improper closure of the enthalpy-increasing electronic expansion valve will affect the compressor, it is divided into two different shutdown processes according to whether the enthalpy-increasing electronic expansion valve is opened. If the enthalpy-increasing electronic expansion valve is opened, the expected fluctuation intensity corresponding to the compressor is determined based on the current ambient temperature, the current inlet water temperature and the current compression frequency of the compressor, and the frequency reduction rate of the compressor is determined according to the expected fluctuation intensity; if the enthalpy-increasing electronic expansion valve is closed, the compressor can be directly controlled to reduce the frequency to shutdown according to the set frequency reduction rate.

[0053] In the embodiment of the present invention, the expected fluctuation intensity is used to characterize the impact of the closing of the enthalpy-increasing electronic expansion valve on the compressor; the expected fluctuation intensity can be determined according to the current working state of the heat pump system. Generally speaking, the workload of the compressor is positively correlated with the expected fluctuation intensity, that is, the greater the workload of the compressor, the greater the expected fluctuation intensity, and the smaller the workload of the compressor, the smaller the expected fluctuation intensity; the working parameters of the compressor may include the compression ratio and / or phase current of the compressor.

[0054] In the embodiment of the present invention, the influence of closing the enthalpy-increasing electronic expansion valve on the compressor is mainly reflected in the fluctuation and influence on the compression ratio and / or phase current of the compressor. Taking the compression ratio as an example, the compression ratio of the compressor is related to the evaporation temperature, the condensation temperature and the ambient temperature.

[0055] In the embodiment of the present invention, the evaporation temperature is the temperature of the refrigerant at the compressor inlet, and the lower the evaporation temperature, the higher the compression ratio; the condensation temperature is the temperature of the refrigerant at the compressor outlet, and the higher the condensation temperature, the higher the compression ratio.

[0056] In the embodiment of the present invention, the condensation temperature is usually the temperature after heat exchange with cooling water. Therefore, when the inlet water temperature is low, the condenser can cool the high-temperature and high-pressure refrigerant gas more effectively, making it easier to condense into liquid. At the same time, when the condensation temperature drops, the pressure required by the compressor to compress the refrigerant will also decrease accordingly, thereby reducing the compression ratio. At the same time, since the cooling efficiency of the condenser is higher when the inlet water temperature is lower, the enthalpy-increasing electronic expansion valve will also reduce its opening accordingly to reduce the refrigerant flow rate.

[0057] In the embodiment of the present invention, the influence of the ambient temperature on the compression ratio is mainly an indirect influence caused by affecting the evaporation temperature and the condensation temperature. When the ambient temperature is low, the evaporation temperature and the condensation temperature will be reduced, thereby increasing the compression ratio. At the same time, when the ambient temperature is low, the cooling capacity or heating capacity required by the system is low, so the enthalpy-increasing electronic expansion valve will also reduce the opening accordingly to reduce the refrigerant flow, thereby reducing the cooling efficiency or heating efficiency of the system. When the ambient temperature is high, the evaporation temperature and the condensation temperature will increase, thereby reducing the compression ratio; at the same time, when the ambient temperature is high, the cooling capacity or heating capacity required by the system is high, so the enthalpy-increasing electronic expansion valve will also increase the opening accordingly to increase the refrigerant flow, thereby improving the cooling efficiency or heating efficiency of the system.

[0058] In the embodiment of the present invention, the compression frequency of the compressor can reflect the cooling capacity or heating capacity of the heat pump system. The higher the compression frequency, the stronger the cooling capacity or heating capacity of the heat pump system, and the greater the compression ratio of the corresponding compressor.

[0059] In an embodiment of the present invention, the current opening of the enthalpy-increasing electronic expansion valve can be determined by combining the current ambient temperature and the current water inlet temperature, and the fluctuations and influences that the compressor can accept can be determined based on the current compression frequency of the compressor; the fluctuation intensity can be predicted by combining the current ambient temperature, the current water inlet temperature and the current compression frequency of the compressor.

[0060] Step 220: Based on the expected fluctuation intensity, determine the closing rate of the enthalpy-increasing electronic expansion valve and the frequency reduction rate of the compressor.

[0061] In the embodiment of the present invention, the closing rate of the enthalpy-increasing electronic expansion valve represents the decreasing rate of the opening degree of the enthalpy-increasing electronic expansion valve, and the frequency reduction rate of the compressor represents the decreasing rate of the compression frequency of the compressor.

[0062] In the embodiment of the present invention, the greater the expected fluctuation intensity, the greater the impact of directly closing the enthalpy-increasing electronic expansion valve on the compressor; the smaller the expected fluctuation intensity, the smaller the impact of directly closing the enthalpy-increasing electronic expansion valve on the compressor. According to the magnitude of the expected fluctuation intensity, the closing rate of the enthalpy-increasing electronic expansion valve is determined to ensure that the closing rate of the enthalpy-increasing electronic expansion valve is relatively small when the expected fluctuation intensity is large, so as to avoid the situation where the enthalpy-increasing electronic expansion valve is quickly closed and causes large fluctuations to the compressor.

[0063] In one embodiment, if the compressor is closed during the closing process of the enthalpy increasing electronic expansion valve, liquid refrigerant may enter the compressor, causing liquid hammer, so the compressor needs to maintain a low-frequency operation state when the enthalpy increasing electronic expansion valve is closed. In order to ensure that the compressor is still in a low-frequency operation state when the enthalpy increasing electronic expansion valve is closed, the frequency reduction rate of the compressor can be determined first, and then the closing rate of the enthalpy increasing electronic expansion valve can be determined according to the frequency reduction rate of the compressor to ensure that the operating rate of the compressor is not 0 when the opening of the enthalpy increasing electronic expansion valve is 0.

[0064] Step 230: Control the enthalpy-increasing electronic expansion valve and the compressor based on the closing rate and the frequency reduction rate.

[0065] In the embodiment of the present invention, the closing of the enthalpy-increasing electronic expansion valve is controlled based on the closing rate, and the closing of the compressor is controlled based on the frequency reduction rate. Specifically, the enthalpy-increasing electronic expansion valve is controlled to close according to the closing rate, and the compressor is controlled to reduce the frequency to close according to the frequency reduction rate.

[0066] In one embodiment, in order to simplify the quantification of the expected fluctuation intensity and reduce the amount of data processing to achieve rapid shutdown of the heat pump system, the expected fluctuation intensity can be divided into two intensities, namely, the first intensity and the second intensity, according to the current working state of the heat pump system, and different shutdown rates and frequency reduction rates are set for the two intensities. Specifically, Figure 3 is a flow chart of determining the expected fluctuation intensity in a control method of a heat pump system according to an embodiment of the present invention. Figure 3 As shown, the above step 210 may include:

[0067] Step 310: If the current ambient temperature is greater than the first preset temperature, the current water inlet temperature is less than the second preset temperature, and the current compression frequency is less than the preset frequency, then the expected fluctuation intensity is determined to be the first intensity.

[0068] In the embodiment of the present invention, if the current ambient temperature is greater than the first preset temperature, it indicates that the current ambient temperature will drive the compression ratio to decrease, and the current opening of the enthalpy-increasing electronic expansion valve is relatively small; if the current inlet water temperature is less than the second preset temperature, it indicates that the current inlet water temperature will drive the compression ratio to decrease, and the current opening of the enthalpy-increasing electronic expansion valve is relatively small; if the current compression frequency is less than the preset frequency, it indicates that the current compression ratio of the compressor is relatively small. Therefore, on the one hand, the current opening ratio of the enthalpy-increasing electronic expansion valve is relatively small, which will have a relatively small impact on the compressor. On the other hand, the compression ratio of the compressor is relatively small, and the relatively acceptable impact is relatively large. At this time, the expected fluctuation intensity is determined to be the first intensity.

[0069] Step 320: If the current ambient temperature is less than or equal to the first preset temperature, and / or the current water inlet temperature is greater than or equal to the second preset temperature, and / or the current compression frequency is greater than or equal to the preset frequency, then the expected fluctuation intensity is determined to be the second intensity.

[0070] In an embodiment of the present invention, the first intensity is less than the second intensity. If the current ambient temperature is less than or equal to the first preset temperature, it indicates that the current ambient temperature will drive the compression ratio to increase, and the current enthalpy-increasing electronic expansion valve has a larger opening; if the current water inlet temperature is greater than or equal to the second preset temperature, it indicates that the current ambient temperature will drive the compression ratio to increase, and the current enthalpy-increasing electronic expansion valve has a larger opening; if the current compression frequency is greater than or equal to the preset frequency, it indicates that the current compression ratio of the compressor is relatively large. If any one of the above conditions is met, it can be determined that the current enthalpy-increasing electronic expansion valve has a larger opening, which will have a greater impact on the compressor, the compression ratio of the compressor is relatively large, and the relatively acceptable impact is relatively small. At this time, the expected fluctuation intensity is determined to be the second intensity.

[0071] In one embodiment, according to the classification of the expected fluctuation intensity in the above embodiment, the above step 220 determines the closing rate of the enthalpy increasing electronic expansion valve and the frequency reduction rate of the compressor based on the expected fluctuation intensity, which can be correspondingly divided into the following two cases:

[0072] The first case: if the expected fluctuation intensity is the second intensity, the enthalpy-increasing electronic expansion valve has a greater impact on the compressor at this time, and the enthalpy-increasing electronic expansion valve cannot be closed directly or at a faster rate. Therefore, the frequency reduction rate is determined to be the first frequency reduction rate, and the closing rate is determined to be the first closing rate. In order to ensure that the compressor is still in a low-frequency operation state when the enthalpy-increasing electronic expansion valve is closed, the first closing rate is determined based on the current opening of the enthalpy-increasing electronic expansion valve, the frequency reduction rate, and the current compression frequency.

[0073] In one embodiment, Figure 4 is a flow chart of determining a first closing rate in a control method of a heat pump system according to an embodiment of the present invention, such as Figure 4As shown, the first closing rate is determined based on the current opening degree, frequency reduction rate and current compression frequency of the enthalpy increasing electronic expansion valve, including:

[0074] Step 410: Determine a mapping ratio corresponding to a closing rate and a frequency reduction rate based on the current opening degree, the current compression frequency and the target compression frequency.

[0075] In the embodiment of the present invention, the target compression frequency is the compression frequency of the compressor when the preset enthalpy-increasing electronic expansion valve is closed. The target compression frequency is a compression frequency set to ensure the stability of the heat pump system, which is used to ensure that the compressor is still in a low-frequency operation state when the enthalpy-increasing electronic expansion valve is closed. Different working conditions of the heat pump system have different corresponding target compression frequencies that can ensure the stability of the heat pump system. Therefore, the corresponding target compression frequency can be pre-set for different working conditions. During the shutdown process of the heat pump system, the corresponding target compression frequency is selected according to the current working condition of the heat pump system.

[0076] In the embodiment of the present invention, the mapping ratio is used to characterize the ratio of the closing rate to the frequency reduction rate, which corresponds to the ratio of the opening change of the enthalpy-increasing electronic expansion valve to the compression frequency change of the compressor per unit time. The mapping ratio is determined based on the current opening, the current compression frequency and the target compression frequency, and the ratio of the closing rate to the frequency reduction rate is limited by the mapping ratio to ensure that the opening of the enthalpy-increasing electronic expansion valve is 0, that is, when it is closed, the compression frequency of the compressor is exactly the target compression frequency.

[0077] In one embodiment, a specific method for determining a mapping ratio based on a current opening, a current compression frequency, and a target compression frequency is as follows: subtract the current compression frequency from the target compression frequency to obtain a frequency difference; and divide the current opening by the frequency difference to obtain a mapping ratio.

[0078] Step 420: Determine a first shutdown rate based on the mapping ratio and the frequency reduction rate.

[0079] In the embodiment of the present invention, the mapping ratio is multiplied by the frequency reduction rate to obtain the first shutdown rate; wherein the frequency reduction rate is the first frequency reduction rate at this time, that is, the mapping ratio is multiplied by the first frequency reduction rate to obtain the first shutdown rate.

[0080] In one embodiment, the method for determining the first closing rate can be specifically shown as the following formula (1):

[0081]

[0082] Among them, v1 is the first closing rate, n1 is the frequency reduction rate, which is the first frequency reduction rate here; p is the current opening, f1 is the current compression frequency, and f2 is the target compression frequency.

[0083] The second case: if the expected fluctuation intensity is the first intensity, then the effect of the enthalpy-increasing electronic expansion valve on the compressor is small, and the enthalpy-increasing electronic expansion valve can be closed directly or at a faster rate, so the closing rate can be determined to be the second closing rate, and the frequency reduction rate can be determined to be the second frequency reduction rate. Among them, the second frequency reduction rate is greater than the first frequency reduction rate, so that the compressor can be quickly closed when the enthalpy-increasing electronic expansion valve can be directly closed, thereby realizing the rapid shutdown of the heat pump system. The second closing rate can be set to a larger rate to ensure that the enthalpy-increasing electronic expansion valve can be closed quickly.

[0084] In one embodiment, if the enthalpy-increasing electronic expansion valve is closed, the shutdown process of the heat pump system will not affect the compressor, and the compressor can be directly shut down according to the set frequency reduction rate. Specifically, in this case, the shutdown process of the heat pump system after responding to the shutdown command is as follows: in response to the shutdown command, if the enthalpy-increasing electronic expansion valve is closed, the frequency reduction rate of the compressor is determined to be the third frequency reduction rate; the compressor is controlled to reduce the frequency to shutdown according to the frequency reduction rate.

[0085] In one embodiment, the third frequency reduction rate is the set rate of decrease of the compression frequency of the compressor without external interference. The third frequency reduction rate can be set to a larger value, for example, it can be set to the maximum safe rate that can ensure the safe operation of the compressor, so as to achieve rapid shutdown of the heat pump system. Correspondingly, the first frequency reduction rate, the second frequency reduction rate and the third frequency reduction rate have the following magnitude relationship: the first frequency reduction rate is less than the second frequency reduction rate, and the second frequency reduction rate is less than or equal to the third frequency reduction rate.

[0086] In one embodiment, after the compressor is controlled to be turned off at a frequency reduction rate, the enthalpy increasing electronic expansion valve and the compressor are both in a closed state, and other components in the heat pump system are further turned off to complete the shutdown of the heat pump system. Specifically, the fan is controlled to stop running, and the opening of the temperature regulating expansion valve is adjusted to a preset opening. Among them, the preset opening of the temperature regulating expansion valve can be the initial opening adopted by the temperature regulating expansion valve when the heat pump system is initially operated; the initial opening is related to the ambient temperature, and the corresponding initial opening is selected according to the ambient temperature, and the opening of the temperature regulating expansion valve is adjusted to the corresponding initial opening.

[0087] The control method of the heat pump system provided in an embodiment of the present invention responds to a shutdown instruction for the heat pump system. If the enthalpy increasing electronic expansion valve is opened, the expected fluctuation intensity corresponding to the compressor is determined based on the current ambient temperature, the current water inlet temperature and the current compression frequency of the compressor; the expected fluctuation intensity is used to characterize the impact of the closing of the enthalpy increasing electronic expansion valve on the compressor; based on the expected fluctuation intensity, the closing rate of the enthalpy increasing electronic expansion valve and the frequency reduction rate of the compressor are determined; based on the closing rate and the frequency reduction rate, the enthalpy increasing electronic expansion valve and the compressor are controlled. In this way, when the heat pump system receives a shutdown command but the reheat-increasing electronic expansion valve is open, the expected fluctuation intensity corresponding to the compressor is determined based on the current ambient temperature, the current inlet water temperature and the current compression frequency of the compressor, and the closing rate of the reheat-increasing electronic expansion valve and the frequency reduction rate of the compressor are determined according to the expected fluctuation intensity of the compressor. That is, the impact of the closing of the reheat-increasing electronic expansion valve on the compressor under different working conditions is divided into different expected fluctuation intensities, and the closing rate of the reheat-increasing electronic expansion valve and the frequency reduction rate of the compressor are adjusted accordingly, so as to avoid excessive impact on the compressor when the reheat-increasing electronic expansion valve is closed, ensure that the compressor can relieve pressure normally, avoid low system reliability caused by the shutdown process of the heat pump system, and thus ensure system reliability.

[0088] According to an embodiment of the present invention, on the other hand, a control system of a heat pump system is provided, including a controller, wherein the controller is used to execute the control method of the heat pump system as described in any of the above embodiments.

[0089] In the specific contents of the above-mentioned specific implementation methods, the various technical features can be combined in any non-contradictory manner. In order to make the description concise, not all possible combinations of the above-mentioned technical features are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0090] The specific contents of the above specific implementations only express several implementations of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention.

Claims

1. A control method for a heat pump system, characterized in that: The method comprises: In response to a shutdown instruction for the heat pump system, if the enthalpy-increasing electronic expansion valve is opened, an expected fluctuation intensity corresponding to the compressor is determined based on the current ambient temperature, the current water inlet temperature and the current compression frequency of the compressor; the expected fluctuation intensity is used to characterize the impact of the closing of the enthalpy-increasing electronic expansion valve on the compressor; Based on the expected fluctuation intensity, determining a closing rate of the enthalpy-increasing electronic expansion valve and a frequency reduction rate of the compressor; Based on the closing rate and the frequency reduction rate, the enthalpy increasing electronic expansion valve and the compressor are controlled.

2. The method according to claim 1, characterized in that The determining the expected fluctuation intensity corresponding to the compressor based on the current ambient temperature, the current water inlet temperature and the current compression frequency of the compressor includes: If the current ambient temperature is greater than a first preset temperature, the current water inlet temperature is less than a second preset temperature, and the current compression frequency is less than a preset frequency, then determining that the expected fluctuation intensity is a first intensity; If the current ambient temperature is less than or equal to the first preset temperature, and / or the current water inlet temperature is greater than or equal to the second preset temperature, and / or the current compression frequency is greater than or equal to the preset frequency, then the expected fluctuation intensity is determined to be the second intensity; the first intensity is less than the second intensity.

3. The method according to claim 2, characterized in that The determining, based on the expected fluctuation intensity, a closing rate of the enthalpy-increasing electronic expansion valve and a frequency reduction rate of the compressor comprises: If the expected fluctuation intensity is the second intensity, the closing rate is determined to be the first closing rate, and the frequency reduction rate is determined to be the first frequency reduction rate; the first closing rate is determined based on the current opening of the enthalpy increasing electronic expansion valve, the frequency reduction rate and the current compression frequency.

4. The method according to claim 3, characterized in that The first closing rate is determined based on the current opening degree of the enthalpy-increasing electronic expansion valve, the frequency reduction rate, and the current compression frequency, including: Based on the current opening degree, the current compression frequency and the target compression frequency, a mapping ratio corresponding to the closing rate and the frequency reduction rate is determined; the target compression frequency is the preset compression frequency of the compressor when the enthalpy increasing electronic expansion valve is closed; The first shutdown rate is determined based on the mapping ratio and the frequency reduction rate.

5. The method according to claim 4, characterized in that The determining, based on the current opening degree, the current compression frequency and the target compression frequency, a mapping ratio corresponding to the closing rate and the frequency reduction rate comprises: Subtracting the current compression frequency from the target compression frequency to obtain a frequency difference; The current opening is divided by the frequency difference to obtain the mapping ratio.

6. The method according to claim 2, characterized in that The determining, based on the expected fluctuation intensity, a closing rate of the enthalpy-increasing electronic expansion valve and a frequency reduction rate of the compressor comprises: If the expected fluctuation intensity is the first intensity, the closing rate is determined to be the second closing rate, and the frequency reduction rate is the second frequency reduction rate; the second frequency reduction rate is greater than the first frequency reduction rate.

7. The method according to any one of claims 1 to 6, characterized in that: The controlling of the enthalpy increasing electronic expansion valve and the compressor based on the closing rate and the frequency reduction rate includes: The enthalpy-increasing electronic expansion valve is controlled to close at the closing rate, and the compressor is controlled to reduce the frequency to close at the frequency reduction rate.

8. The method according to claim 1, characterized in that The method further comprises: In response to the shutdown instruction, if the enthalpy-increasing electronic expansion valve is closed, determining the frequency reduction rate of the compressor to be a third frequency reduction rate; The compressor is controlled to reduce frequency according to the frequency reduction rate until it is turned off.

9. The method according to claim 7 or 8, characterized in that: After controlling the compressor to be turned off at the frequency reduction rate, the method further includes: Control the fan to stop running; Adjust the opening of the thermostatic expansion valve to the preset opening.

10. A control system for a heat pump system, characterized in that: It comprises a controller, wherein the controller is used to execute the control method of the heat pump system as described in any one of claims 1-9.

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