Control method of heat pump system

Abstract

The invention provides a control method of a heat pump system, which comprises the following steps of: determining a control parameter for a main electronic expansion valve 8 based on a working parameter in combination with a current value of a compressor 1, and determining a control parameter for an auxiliary electronic expansion valve 4 based on the working parameter in combination with the current value of the compressor 1 and the opening degree of the main electronic expansion valve 8. The problems that due to the fact that the target return air superheat degree is set unreasonably, the opening degree of a main path electronic expansion valve is too large, the auxiliary path flow is small, the heating capacity is poor, or compressor exhaust high temperature protection shutdown is generated under the high pressure ratio are solved. The problems that due to the fact that the target return air superheat degree is set unreasonably, the opening degree of a main path electronic expansion valve is too small, too much refrigerants are accumulated in a condenser, the compressor exhaust pressure is too high, and shutdown is protected, or due to the fact that the auxiliary path flow is too large, the compressor works in a heavy load mode, the compressor current is too high, and shutdown is protected are solved. The fault shutdown probability and the maintenance rate of a unit are greatly reduced, and the product reliability is improved.

Description

Technical Field

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

[0002] For low-temperature air source heat pumps, due to the low external ambient temperature in cold weather, the evaporation pressure is low when the heat pump is running for heating, resulting in a significant decrease in heating capacity. To solve this problem, the industry generally uses the method of jet enthalpy increase to increase the heating capacity of the heat pump system at low temperatures.

[0003] When the heat pump is in heating operation, the economizer is used as the intermediate heat exchanger, the main electronic expansion valve is used to control the refrigerant flow supplied to the evaporator, and the auxiliary electronic expansion valve is used to control the refrigerant injection amount into the compressor. At present, the main electronic expansion valve is mainly controlled according to the target return gas superheat, and the auxiliary electronic expansion valve is controlled according to the auxiliary superheat and the compressor exhaust temperature; the target return gas superheat is generally a fixed value that can be manually set in the control software. Once the target return gas superheat is set, it remains unchanged, but due to factors such as changes in operating conditions, the target superheat after setting a certain value is difficult to apply to all operating conditions, which will cause the main electronic expansion valve to open too large or too small; when the main electronic expansion valve is opened too large, the auxiliary flow will be small, resulting in poor heating capacity or compressor exhaust high temperature protection shutdown problem under high pressure ratio; when the main electronic expansion valve is opened too small, too much refrigerant will accumulate in the condenser, resulting in the compressor exhaust pressure too high protection shutdown problem, or the auxiliary flow will be large, and the compressor will be overloaded to work, resulting in the compressor current too high protection shutdown problem. The above problems are particularly prominent for heat pump systems using fixed-frequency compressors. Summary of the invention

[0004] The present invention provides a control method for a heat pump system, so as to solve the problems mentioned in the background technology.

[0005] A control method for a heat pump system, comprising:

[0006] S1: Obtain the structural distribution of the heat pump system, and collect the working parameters of the heat pump system from the structural distribution;

[0007] S2: Based on the working parameters and in combination with the current value of the compressor, determining control parameters for the main electronic expansion valve;

[0008] S3: Based on the working parameters, combined with the current value of the compressor and the opening of the main electronic expansion valve, determine the control parameters of the auxiliary electronic expansion valve.

[0009] Preferably, in S1, the structural distribution of the heat pump system is obtained, including a compressor, a liquid supply pipe is connected to the compressor, the other end of the liquid supply pipe is connected to the economizer, an auxiliary output temperature sensor is also provided on the liquid supply pipe, one end of the economizer is also connected to a connecting pipe, the other end of the connecting pipe is connected to the water side heat exchanger, one end of the water side heat exchanger is connected to the C valve of the four-way valve through the connecting pipe, the E valve of the four-way valve is connected to the fin-tube heat exchanger through the connecting pipe, an ambient temperature sensor is provided on the fin-tube heat exchanger, the other end of the fin-tube heat exchanger is connected to the economizer through the connecting pipe, a main circuit electronic expansion valve is provided on the connecting pipe between the fin-tube heat exchanger and the economizer, a branch connecting pipe is provided on the connecting pipe between the fin-tube heat exchanger and the economizer, the other end of the branch connecting pipe is connected back to the other end of the economizer, and an auxiliary circuit electronic expansion valve and an auxiliary input temperature sensor are provided on the branch connecting pipe.

[0010] Preferably, the D valve of the four-way valve is connected to the compressor through a first connecting pipeline, and an exhaust temperature sensor is arranged on the connecting pipeline. The D valve of the four-way valve is connected to the compressor through a second connecting pipeline, and a return air temperature sensor and a low pressure sensor are arranged in sequence on the second connecting pipeline.

[0011] Preferably, in S1, the operating parameters of the heat pump system are collected from the structural distribution, including:

[0012] The return air pressure of the heat pump system is collected from the low-pressure sensor, the return air temperature value is collected from the return air temperature sensor 3, the ambient temperature value is collected from the ambient temperature sensor, the auxiliary output temperature value is collected from the auxiliary output temperature sensor, the auxiliary input temperature value is collected from the auxiliary input temperature sensor, and the exhaust temperature value is collected from the exhaust temperature sensor.

[0013] Preferably, in S2, based on the working parameters and in combination with the current value of the compressor, determining the control parameters of the main electronic expansion valve includes:

[0014] When the auxiliary electronic expansion valve is opened, the control method of the main electronic expansion valve is as follows:

[0015] When the current value of the compressor is greater than or equal to the first preset current, the main electronic expansion valve is gradually opened in each adjustment cycle, and the step size of each action does not exceed 2% of the maximum opening of the main electronic expansion valve;

[0016] When the current value of the compressor is less than the first preset current and greater than or equal to the second preset current, the main circuit electronic expansion valve is controlled according to the target return air superheat and is not allowed to be closed down;

[0017] When the current value of the compressor is less than the second preset current, the main electronic expansion valve is controlled according to the target return air superheat.

[0018] Preferably, the actual value of the target return air superheat is the difference between the return air pressure temperature value and the return air pressure saturation temperature value. The correction method of the actual value of the target return air superheat is as follows:

[0019] When the exhaust gas temperature value is greater than the first preset exhaust gas temperature, and the opening of the auxiliary electronic expansion valve exceeds eighty percent of its maximum opening, or the current value of the compressor limits the auxiliary electronic expansion valve to open wide, the target return air superheat is corrected and increased by 2°C in each judgment cycle based on the actual value, and the corrected target return air superheat value is less than or equal to the sum of the default setting value and 4°C;

[0020] When the ambient temperature value is lower than the first preset ambient temperature, and the exhaust temperature value is lower than or equal to the first preset exhaust temperature and higher than or equal to the second preset exhaust temperature, the target return air superheat value keeps the actual value unchanged;

[0021] When the ambient temperature value is lower than the first preset ambient temperature, and the exhaust temperature value is lower than the second preset exhaust temperature, the target return air superheat value is corrected and reduced by 1°C in each judgment cycle based on the actual value, and the corrected target return air superheat value is greater than or equal to the difference between the default value and 4°C;

[0022] When the ambient temperature value is greater than or equal to the first preset ambient temperature, and the exhaust temperature value is less than or equal to the first preset exhaust temperature and greater than or equal to the third preset exhaust temperature, the target return air superheat value keeps the actual value unchanged;

[0023] When the ambient temperature value is greater than or equal to the first preset ambient temperature, and the exhaust temperature value is less than the third preset exhaust temperature, the target return air superheat value is corrected and reduced by 1°C in each judgment cycle based on the actual value, and the corrected target return air superheat value is greater than or equal to the difference between the default value and 4°C.

[0024] Preferably, in S3, based on the working parameters, combined with the current value of the compressor and the opening of the main electronic expansion valve, the control parameters of the auxiliary electronic expansion valve are determined, including:

[0025] When the current value of the compressor is greater than or equal to the first preset current, and the opening of the main electronic expansion valve exceeds 80% of its maximum opening, the auxiliary electronic expansion valve is gradually closed in each adjustment cycle, and the step size of each action does not exceed 2% of the maximum opening of the auxiliary electronic expansion valve;

[0026] When the current value of the compressor is less than the first preset current and greater than or equal to the second preset current, the auxiliary circuit electronic expansion valve is controlled according to the target injection superheat or the target exhaust gas temperature, and is not allowed to be opened wide;

[0027] When the current value of the compressor is less than the second preset current, the auxiliary circuit electronic expansion valve is controlled according to the target injection superheat or the target exhaust gas temperature;

[0028] The target injection superheat is determined by the difference between the auxiliary outlet temperature and the auxiliary inlet temperature.

[0029] Preferably, the specific options for controlling according to the target injection superheat or the target exhaust temperature are as follows:

[0030] When the exhaust temperature value is greater than the first preset exhaust temperature, the auxiliary circuit electronic expansion valve is controlled according to the target exhaust temperature;

[0031] When the exhaust temperature value is less than or equal to the first preset exhaust temperature and greater than or equal to the fourth preset exhaust temperature, the auxiliary circuit electronic expansion valve is controlled according to the target injection superheat;

[0032] When the exhaust temperature value is less than the fourth preset exhaust temperature, the auxiliary electronic expansion valve is gradually closed in each adjustment cycle, and the step size of each action does not exceed 2% of the maximum opening of the auxiliary electronic expansion valve.

[0033] Preferably, the method further includes: obtaining a refrigerant flow rate controlled by a main electronic expansion valve of the heat pump system and a refrigerant injection amount determined by an auxiliary electronic expansion valve when the heat pump system is controlled according to S1-S3;

[0034] Obtaining a flow-injection amount correspondence relationship between the refrigerant flow rate and the refrigerant injection amount in the same time series, and obtaining a main control parameter and an auxiliary control parameter under the flow-injection amount correspondence relationship;

[0035] Based on the flow-injection amount correspondence, in combination with the main control parameter and the auxiliary control parameter, the secondary adjustment parameters of the main control parameter and the auxiliary control parameter are determined.

[0036] Preferably, the method of determining the secondary adjustment parameters of the main control parameters and the auxiliary control parameters based on the flow-injection amount correspondence relationship in combination with the main control parameters and the auxiliary control parameters includes:

[0037] Determine a difference curve between flow rate and injection amount from the flow rate-injection amount correspondence, obtain a first time range in which the difference is greater than a first preset difference from the difference curve, and obtain a second time range in which the difference is less than the first preset difference;

[0038] Acquire a second opening relationship between the main opening and the auxiliary opening corresponding to the second time range from the main control parameter and the auxiliary control parameter, and determine a reference optimal opening ratio between the main opening and the auxiliary opening based on the second opening relationship;

[0039] Acquire a first opening relationship between the main opening and the auxiliary opening corresponding to the first time range from the main control parameter and the auxiliary control parameter, and establish a corresponding relationship between the first opening relationship and a difference greater than a first preset difference;

[0040] Based on the corresponding relationship, a proportional curve between the opening and the difference is obtained, based on the wave degree of the proportional curve, a correction weight for the reference optimal opening ratio is determined, and the reference optimal opening ratio is corrected according to the correction weight to obtain a target optimal opening ratio;

[0041] When the difference between the real-time detected flow rate and the injection amount is greater than the first preset difference, the main control parameter and the auxiliary control parameter are adjusted secondary according to the target optimal opening ratio.

[0042] Compared with the prior art, the present invention has achieved the following beneficial effects:

[0043] By acquiring the structural distribution of the heat pump system and collecting the working parameters of the heat pump system from the structural distribution, based on the working parameters and in combination with the current value of the compressor, the control parameters of the main electronic expansion valve are determined; based on the working parameters and in combination with the current value of the compressor and the opening of the main electronic expansion valve, the control parameters of the auxiliary electronic expansion valve are determined, so as to solve the problem that the target return air superheat is set unreasonably, which makes the main electronic expansion valve opening too large, resulting in a small auxiliary flow, leading to poor heating capacity or the compressor exhaust high temperature protection shutdown problem under high pressure ratio; the target return air superheat is set unreasonably, which makes the main electronic expansion valve opening too small, resulting in excessive accumulation of refrigerant in the condenser, resulting in the compressor exhaust pressure being too high and the protection shutdown problem, or the auxiliary flow is too large, and the compressor is overloaded and works, resulting in the compressor current being too high and the protection shutdown problem; the failure shutdown probability and maintenance rate of the unit are greatly reduced, and the product reliability is improved.

[0044] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures specifically pointed out in this application document.

[0045] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0047] Figure 1 is a flow chart of a control method of a heat pump system in an embodiment of the present invention;

[0048] Figure 2 A structural diagram of a heat pump system in an embodiment of the present invention;

[0049] Figure 3 The present invention is a flowchart for determining control parameters of an auxiliary electronic expansion valve in an embodiment of the present invention. DETAILED DESCRIPTION

[0050] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0051] Embodiment 1:

[0052] The embodiment of the present invention provides a control method for a heat pump system. Figure 1 As shown, including:

[0053] S1: Obtain the structural distribution of the heat pump system, and collect the working parameters of the heat pump system from the structural distribution;

[0054] S2: Based on the working parameters and in combination with the current value of the compressor 1, determining the control parameters of the main electronic expansion valve 8;

[0055] S3: Based on the working parameters, combined with the current value of the compressor 1 and the opening degree of the main electronic expansion valve 8, the control parameters of the auxiliary electronic expansion valve 4 are determined.

[0056] In this embodiment, the operating parameters of the heat pump system include detection parameters of various sensors.

[0057] In this embodiment, the control parameter of the main electronic expansion valve 8 is the control of the opening degree.

[0058] In this embodiment, the control parameter of the auxiliary electronic expansion valve 4 is the control of the opening degree.

[0059] The beneficial effects of the above design scheme are: by obtaining the structural distribution of the heat pump system and collecting the working parameters of the heat pump system from the structural distribution, based on the working parameters, combined with the current value of the compressor 1, the control parameters of the main electronic expansion valve 8 are determined; based on the working parameters, combined with the current value of the compressor 1 and the opening of the main electronic expansion valve 8, the control parameters of the auxiliary electronic expansion valve 4 are determined, so as to solve the problem that the target return air superheat setting is unreasonable, which makes the main electronic expansion valve opening too large, which will make the auxiliary flow small, resulting in poor heating capacity or compressor exhaust high temperature protection shutdown problem under high pressure ratio; solve the problem that the target return air superheat setting is unreasonable, which makes the main electronic expansion valve opening too small, which will cause excessive accumulation of refrigerant in the condenser, resulting in the compressor exhaust pressure too high protection shutdown problem, or the auxiliary flow is too large, the compressor is overloaded and works, resulting in the compressor current too high protection shutdown problem; it can greatly reduce the failure shutdown probability and maintenance rate of the unit and improve product reliability.

[0060] Embodiment 2:

[0061] Based on Example 1, the present invention provides a control method for a heat pump system, such as Figure 2 As shown, in S1, the structural distribution of the heat pump system is obtained, including a compressor 1, a liquid supply pipe is connected to the compressor 1, the other end of the liquid supply pipe is connected to the economizer 9, an auxiliary output temperature sensor 10 is also provided on the liquid supply pipe, one end of the economizer 9 is also connected to a connecting pipe, the other end of the connecting pipe is connected to the water side heat exchanger 7, one end of the water side heat exchanger 7 is connected to the C valve of the four-way valve 12 through the connecting pipe, the E valve of the four-way valve 12 is connected to the fin-tube heat exchanger 5 through the connecting pipe, the fin-tube heat exchanger 5 is provided with an ambient temperature sensor 6, the other end of the fin-tube heat exchanger 5 is connected to the economizer 9 through the connecting pipe, a main circuit electronic expansion valve 8 is provided on the connecting pipe between the fin-tube heat exchanger 5 and the economizer 9, a branch connecting pipe is provided on the connecting pipe between the fin-tube heat exchanger 5 and the economizer 9, the other end of the branch connecting pipe is connected back to the other end of the economizer 9, and an auxiliary circuit electronic expansion valve 4 and an auxiliary input temperature sensor 11 are provided on the branch connecting pipe.

[0062] The beneficial effects of the above design scheme are: providing a structural distribution of the heat pump system and providing a structural basis for the control of the heat pump system.

[0063] Embodiment 3:

[0064] Based on Example 2, the present invention provides a control method for a heat pump system, such as Figure 2As shown, the D valve of the four-way valve 12 is connected to the compressor 1 through a first connecting pipeline, and an exhaust temperature sensor 13 is arranged on the connecting pipeline. The D valve of the four-way valve 12 is connected to the compressor 1 through a second connecting pipeline, and a return air temperature sensor 3 and a low pressure sensor 2 are arranged in sequence on the second connecting pipeline.

[0065] The beneficial effects of the above design scheme are: providing a structural distribution of the heat pump system and providing a structural basis for the control of the heat pump system.

[0066] Embodiment 4:

[0067] Based on Example 1, the embodiment of the present invention provides a control method for a heat pump system. In S1, the operating parameters of the heat pump system are acquired from the structural distribution, including:

[0068] The return air pressure of the heat pump system is collected from the low pressure sensor 2, the return air temperature value is collected from the return air temperature sensor 3, the ambient temperature value is collected from the ambient temperature sensor 6, the auxiliary output temperature value is collected from the auxiliary output temperature sensor 10, the auxiliary input temperature value is collected from the auxiliary input temperature sensor 11, and the exhaust temperature value is collected from the exhaust temperature sensor 13.

[0069] The beneficial effect of the above design scheme is that the working parameters are obtained by collecting the parameters of each sensor, thereby providing a parameter basis for the control of the heat pump system.

[0070] Embodiment 5:

[0071] Based on Example 1, the embodiment of the present invention provides a control method for a heat pump system. In S2, based on the working parameters and in combination with the current value of the compressor 1, the control parameters of the main electronic expansion valve 8 are determined, including:

[0072] When the auxiliary electronic expansion valve 4 is opened, the control method of the main electronic expansion valve 8 is as follows:

[0073] When the current value of the compressor 1 is greater than or equal to the first preset current, the main electronic expansion valve 8 is gradually opened in each adjustment cycle, and the step size of each action does not exceed 2% of the maximum opening of the main electronic expansion valve 8;

[0074] When the current value of the compressor 1 is less than the first preset current and greater than or equal to the second preset current, the main circuit electronic expansion valve 8 is controlled according to the target return air superheat and is not allowed to be closed;

[0075] When the current value of the compressor 1 is less than the second preset current, the main electronic expansion valve 8 is controlled according to the target return air superheat.

[0076] In this embodiment, the first preset current is generally the maximum operating current allowed by the compressor technical specification minus 1 to 2A, and the difference between the first preset current and the second preset current is generally between 1 and 3A.

[0077] In this embodiment, the return gas superheat is the difference between the return gas temperature and the return gas pressure saturation temperature, and the return gas pressure saturation temperature is obtained by converting the return gas pressure.

[0078] In this embodiment, the target return air superheat is adjustable.

[0079] The beneficial effect of the above design scheme is: by controlling the opening based on the target return air superheat, the problem of unreasonable setting of the target return air superheat causing the main electronic expansion valve to open too large, which will cause the auxiliary flow to be small, resulting in poor heating capacity or the compressor exhaust high temperature protection shutdown problem under high pressure ratio; the unreasonable setting of the target return air superheat causing the main electronic expansion valve to open too small, which will cause excessive accumulation of refrigerant in the condenser, resulting in the compressor exhaust pressure being too high and shutting down for protection; or the auxiliary flow being too large, causing the compressor to be overloaded and working, resulting in the compressor current being too high and shutting down for protection.

[0080] Embodiment 6:

[0081] Based on Example 5, the embodiment of the present invention provides a control method for a heat pump system, wherein the actual value of the target return air superheat is the difference between the return air pressure temperature value and the return air pressure saturation temperature value, and the correction method of the actual value of the target return air superheat is as follows:

[0082] When the exhaust gas temperature value is greater than the first preset exhaust gas temperature, and the opening of the auxiliary circuit electronic expansion valve 4 exceeds eighty percent of its maximum opening, or the current value of the compressor 1 limits the auxiliary circuit electronic expansion valve 4 to open wide, the target return air superheat is corrected and increased by 2°C in each judgment cycle based on the actual value, and the corrected target return air superheat value is less than or equal to the sum of the default setting value and 4°C;

[0083] When the ambient temperature value is lower than the first preset ambient temperature, and the exhaust temperature value is lower than or equal to the first preset exhaust temperature and higher than or equal to the second preset exhaust temperature, the target return air superheat value keeps the actual value unchanged;

[0084] When the ambient temperature value is lower than the first preset ambient temperature, and the exhaust temperature value is lower than the second preset exhaust temperature, the target return air superheat value is corrected and reduced by 1°C in each judgment cycle based on the actual value, and the corrected target return air superheat value is greater than or equal to the difference between the default value and 4°C;

[0085] When the ambient temperature value is greater than or equal to the first preset ambient temperature, and the exhaust temperature value is less than or equal to the first preset exhaust temperature and greater than or equal to the third preset exhaust temperature, the target return air superheat value keeps the actual value unchanged;

[0086] When the ambient temperature value is greater than or equal to the first preset ambient temperature, and the exhaust temperature value is less than the third preset exhaust temperature, the target return air superheat value is corrected and reduced by 1°C in each judgment cycle based on the actual value, and the corrected target return air superheat value is greater than or equal to the difference between the default value and 4°C.

[0087] In this embodiment, the first preset temperature is generally the maximum exhaust temperature allowed by the compressor technical specification minus 5 to 10°C; the difference between the first preset temperature and the second preset temperature is generally between 10 and 20; the third preset temperature is greater than the second preset temperature, and the difference between the third preset temperature and the second preset temperature is generally between 5 and 10, to prevent the main electronic expansion valve from opening too small when the ambient temperature is high, resulting in high-pressure protection or current protection problems of the compressor; the value of the first preset ambient temperature is generally between -10 and -15.

[0088] The beneficial effect of the above design scheme is: by adjusting the target return air superheat based on the exhaust temperature value and the ambient temperature value, the problem of unreasonable setting of the target return air superheat causing the main electronic expansion valve to open too large, resulting in a small auxiliary flow, leading to poor heating capacity or the compressor exhaust high temperature protection shutdown problem under high pressure ratio; the problem of unreasonable setting of the target return air superheat causing the main electronic expansion valve to open too small, causing excessive accumulation of refrigerant in the condenser, resulting in the compressor exhaust pressure being too high and shutting down for protection; or causing the auxiliary flow to be too large, causing the compressor to be overloaded and shutting down for protection due to excessive current.

[0089] Embodiment 7:

[0090] Based on Example 1, the present invention provides a control method for a heat pump system, wherein in S3, Figure 3 As shown, based on the working parameters, combined with the current value of the compressor 1 and the opening of the main electronic expansion valve 8, the control parameters of the auxiliary electronic expansion valve 4 are determined, including:

[0091] When the current value of the compressor 1 is greater than or equal to the first preset current, and the opening of the main electronic expansion valve 8 exceeds 80% of its maximum opening, the auxiliary electronic expansion valve 4 is gradually closed in each adjustment cycle, and the step size of each action does not exceed 2% of the maximum opening of the auxiliary electronic expansion valve 4;

[0092] When the current value of the compressor 1 is less than the first preset current and greater than or equal to the second preset current, the auxiliary electronic expansion valve 4 is controlled according to the target injection superheat or the target exhaust gas temperature, and is not allowed to be opened wide;

[0093] When the current value of the compressor 1 is less than the second preset current, the auxiliary circuit electronic expansion valve 4 is controlled according to the target injection superheat or the target exhaust gas temperature;

[0094] The target injection superheat is determined by the difference between the auxiliary outlet temperature and the auxiliary inlet temperature.

[0095] The beneficial effect of the above design scheme is: by controlling the auxiliary electronic expansion valve 4 according to the target injection superheat or the target exhaust temperature, wherein the target exhaust temperature is adjustable, the problem that the target return air superheat is set unreasonably, resulting in the main electronic expansion valve opening being too large, will make the auxiliary flow small, resulting in poor heating capacity or the compressor exhaust high temperature protection shutdown problem under high pressure ratio; the target return air superheat is set unreasonably, resulting in the main electronic expansion valve opening being too small, which will cause excessive accumulation of refrigerant in the condenser, resulting in the compressor exhaust pressure being too high and shutting down for protection; or the auxiliary flow is too large, and the compressor is overloaded with work, resulting in the compressor current being too high and shutting down for protection.

[0096] Embodiment 8:

[0097] Based on Example 7, the present invention provides a control method for a heat pump system. The specific options for controlling according to the target injection superheat or the target exhaust temperature are as follows:

[0098] When the exhaust temperature value is greater than the first preset exhaust temperature, the auxiliary circuit electronic expansion valve 4 is controlled according to the target exhaust temperature;

[0099] When the exhaust temperature value is less than or equal to the first preset exhaust temperature and greater than or equal to the fourth preset exhaust temperature, the auxiliary electronic expansion valve 4 is controlled according to the target injection superheat;

[0100] When the exhaust temperature value is lower than the fourth preset exhaust temperature, the auxiliary electronic expansion valve 4 is gradually closed in each adjustment cycle, and the step size of each action does not exceed 2% of the maximum opening of the auxiliary electronic expansion valve 4.

[0101] In this embodiment, the fourth preset exhaust temperature is generally between 55 and 65 degrees Celsius.

[0102] The beneficial effects of the above design scheme are: when the exhaust temperature value is greater than the first preset exhaust temperature, the auxiliary electronic expansion valve 4 is controlled according to the target exhaust temperature; when the exhaust temperature value is less than or equal to the first preset exhaust temperature and greater than or equal to the fourth preset exhaust temperature, the auxiliary electronic expansion valve 4 is controlled according to the target injection superheat; when the exhaust temperature value is less than the fourth preset exhaust temperature, the auxiliary electronic expansion valve 4 is gradually closed in each adjustment cycle, and the step size of each action does not exceed 2% of the maximum opening of the auxiliary electronic expansion valve 4, thereby realizing the control of the auxiliary electronic expansion valve 4.

[0103] Embodiment 9:

[0104] Based on Example 1, an embodiment of the present invention provides a control method for a heat pump system, further comprising: obtaining a refrigerant flow rate controlled by a main electronic expansion valve 8 of the heat pump system and a refrigerant injection amount determined by an auxiliary electronic expansion valve 4 when the heat pump system is controlled according to S1-S3;

[0105] Obtaining a flow-injection amount correspondence relationship between the refrigerant flow rate and the refrigerant injection amount in the same time series, and obtaining a main control parameter and an auxiliary control parameter under the flow-injection amount correspondence relationship;

[0106] Based on the flow-injection amount correspondence, in combination with the main control parameter and the auxiliary control parameter, the secondary adjustment parameters of the main control parameter and the auxiliary control parameter are determined.

[0107] In this embodiment, the main control parameter is a control parameter for the main electronic expansion valve 8 , and the auxiliary control parameter is a control parameter for the auxiliary electronic expansion valve 4 .

[0108] The beneficial effects of the above design scheme are: by obtaining the flow-injection amount correspondence between the refrigerant flow rate and the refrigerant injection amount in the same time series, and obtaining the main control parameters and auxiliary control parameters under the flow-injection amount correspondence; based on the flow-injection amount correspondence, combined with the main control parameters and the auxiliary control parameters, determine the secondary adjustment parameters of the main control parameters and the auxiliary control parameters, and realize real-time adjustment of the main control parameters and the auxiliary control parameters.

[0109] Embodiment 10:

[0110] Based on Example 9, an embodiment of the present invention provides a control method for a heat pump system, wherein the method determines secondary adjustment parameters for the main control parameters and the auxiliary control parameters based on the flow-injection amount correspondence relationship and in combination with the main control parameters and the auxiliary control parameters, including:

[0111] Determine a difference curve between flow rate and injection amount from the flow rate-injection amount correspondence, obtain a first time range in which the difference is greater than a first preset difference from the difference curve, and obtain a second time range in which the difference is less than the first preset difference;

[0112] Acquire a second opening relationship between the main opening and the auxiliary opening corresponding to the second time range from the main control parameter and the auxiliary control parameter, and determine a reference optimal opening ratio between the main opening and the auxiliary opening based on the second opening relationship;

[0113] Acquire a first opening relationship between the main opening and the auxiliary opening corresponding to the first time range from the main control parameter and the auxiliary control parameter, and establish a corresponding relationship between the first opening relationship and a difference greater than a first preset difference;

[0114] Based on the corresponding relationship, a proportional curve between the opening and the difference is obtained, based on the wave degree of the proportional curve, a correction weight for the reference optimal opening ratio is determined, and the reference optimal opening ratio is corrected according to the correction weight to obtain a target optimal opening ratio;

[0115] When the difference between the flow rate and the injection amount detected in real time is greater than the first preset difference, the main control parameter and the auxiliary control parameter are adjusted secondary according to the target optimal opening ratio.

[0116] The beneficial effects of the above design scheme are: by obtaining the flow-injection amount correspondence between the refrigerant flow rate and the refrigerant injection amount in the same time series, and obtaining the main control parameters and auxiliary control parameters under the flow-injection amount correspondence; based on the flow-injection amount correspondence, combined with the main control parameters and the auxiliary control parameters, the secondary adjustment parameters of the main control parameters and the auxiliary control parameters are determined, and real-time adjustment of the main control parameters and the auxiliary control parameters is achieved, which greatly reduces the failure shutdown probability and maintenance rate of the heat pump system and improves product reliability.

[0117] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention belong to the scope of this application document and its equivalent technology, the present invention is also intended to include these changes and variations.

Claims

1. A control method for a heat pump system, characterized in that: include: S1: Obtain the structural distribution of the heat pump system, and collect the working parameters of the heat pump system from the structural distribution; S2: Based on the working parameters and in combination with the current value of the compressor (1), determining control parameters for the main circuit electronic expansion valve (8); S3: Based on the working parameters, combined with the current value of the compressor (1) and the opening degree of the main electronic expansion valve (8), the control parameters of the auxiliary electronic expansion valve (4) are determined.

2. A control method for a heat pump system according to claim 1, characterized in that: In the S1, the structural distribution of the heat pump system is obtained, including a compressor (1), a liquid supply pipe is connected to the compressor (1), the other end of the liquid supply pipe is connected to the economizer (9), an auxiliary output temperature sensor (10) is also provided on the liquid supply pipe, one end of the economizer (9) is also connected to a connecting pipe, the other end of the connecting pipe is connected to the water side heat exchanger (7), one end of the water side heat exchanger (7) is connected to the C valve of the four-way valve (12) through the connecting pipe, and the E valve of the four-way valve (12) is connected to the fin-tube heat exchanger (5) through the connecting pipe. The fin-tube heat exchanger (5) is provided with an ambient temperature sensor (6); the other end of the fin-tube heat exchanger (5) is connected to the economizer (9) via a connecting pipe; a main circuit electronic expansion valve (8) is provided on the connecting pipe between the fin-tube heat exchanger (5) and the economizer (9); a branch circuit connecting pipe is provided on the connecting pipe between the fin-tube heat exchanger (5) and the economizer (9); the other end of the branch circuit connecting pipe is connected back to the other end of the economizer (9); an auxiliary circuit electronic expansion valve (4) and an auxiliary inlet temperature sensor (11) are provided on the branch circuit connecting pipe.

3. A control method for a heat pump system according to claim 2, characterized in that: The D valve of the four-way valve (12) is connected to the compressor (1) via a first connecting pipeline, and an exhaust temperature sensor (13) is arranged on the connecting pipeline. The D valve of the four-way valve (12) is connected to the compressor (1) via a second connecting pipeline, and a return air temperature sensor (3) and a low pressure sensor (2) are arranged in sequence on the second connecting pipeline.

4. A control method for a heat pump system according to claim 3, characterized in that: In S1, the operating parameters of the heat pump system are collected from the structural distribution, including: The return air pressure of the heat pump system is acquired from the low pressure sensor (2), the return air temperature value is acquired from the return air temperature sensor (3), the ambient temperature value is acquired from the ambient temperature sensor (6), the auxiliary outlet temperature value is acquired from the auxiliary outlet temperature sensor (10), the auxiliary inlet temperature value is acquired from the auxiliary inlet temperature sensor (11), and the exhaust temperature value is acquired from the exhaust temperature sensor (13).

5. The control method of a heat pump system according to claim 1, characterized in that: In S2, based on the working parameters and in combination with the current value of the compressor (1), the control parameters of the main circuit electronic expansion valve (8) are determined, including: When the auxiliary electronic expansion valve (4) is opened, the main electronic expansion valve (8) is controlled as follows: When the current value of the compressor (1) is greater than or equal to a first preset current, the main electronic expansion valve (8) is gradually opened in each adjustment cycle, and the step width of each action does not exceed 2 percent of the maximum opening of the main electronic expansion valve (8); When the current value of the compressor (1) is less than the first preset current and greater than or equal to the second preset current, the main circuit electronic expansion valve (8) is controlled according to the target return air superheat and is not allowed to be closed down; When the current value of the compressor (1) is less than the second preset current, the main circuit electronic expansion valve (8) is controlled according to the target return air superheat.

6. A control method for a heat pump system according to claim 5, characterized in that: The actual value of the target return air superheat is the difference between the return air pressure temperature value and the return air pressure saturation temperature value. The correction method of the actual value of the target return air superheat is as follows: When the exhaust gas temperature value is greater than the first preset exhaust gas temperature, and the opening of the auxiliary circuit electronic expansion valve (4) exceeds eighty percent of its maximum opening, or the current value of the compressor (1) limits the auxiliary circuit electronic expansion valve (4) to open wider, the target return air superheat is corrected by increasing 2°C in each judgment cycle based on the actual value, and the corrected target return air superheat value is less than or equal to the sum of the default setting value and 4°C; When the ambient temperature value is lower than the first preset ambient temperature, and the exhaust temperature value is lower than or equal to the first preset exhaust temperature and higher than or equal to the second preset exhaust temperature, the target return air superheat value keeps the actual value unchanged; When the ambient temperature value is lower than the first preset ambient temperature, and the exhaust temperature value is lower than the second preset exhaust temperature, the target return air superheat value is corrected and reduced by 1°C in each judgment cycle based on the actual value, and the corrected target return air superheat value is greater than or equal to the difference between the default value and 4°C; When the ambient temperature value is greater than or equal to the first preset ambient temperature, and the exhaust temperature value is less than or equal to the first preset exhaust temperature and greater than or equal to the third preset exhaust temperature, the target return air superheat value keeps the actual value unchanged; When the ambient temperature value is greater than or equal to the first preset ambient temperature, and the exhaust temperature value is less than the third preset exhaust temperature, the target return air superheat value is corrected and reduced by 1°C in each judgment cycle based on the actual value, and the corrected target return air superheat value is greater than or equal to the difference between the default value and 4°C.

7. A heat pump system control method according to claim 1, characterized in that: In S3, based on the working parameters, combined with the current value of the compressor (1) and the opening degree of the main electronic expansion valve (8), the control parameters of the auxiliary electronic expansion valve (4) are determined, including: When the current value of the compressor (1) is greater than or equal to a first preset current, and the opening of the main electronic expansion valve (8) exceeds eighty percent of its maximum opening, the auxiliary electronic expansion valve (4) is gradually closed in each adjustment cycle, and the step size of each action does not exceed two percent of the maximum opening of the auxiliary electronic expansion valve (4); When the current value of the compressor (1) is less than the first preset current and greater than or equal to the second preset current, the auxiliary circuit electronic expansion valve (4) is controlled according to the target injection superheat or the target exhaust gas temperature and is not allowed to be opened wide; When the current value of the compressor (1) is less than a second preset current, the auxiliary circuit electronic expansion valve (4) is controlled according to a target injection superheat or a target exhaust gas temperature; The target injection superheat is determined by the difference between the auxiliary outlet temperature and the auxiliary inlet temperature.

8. A control method for a heat pump system according to claim 7, characterized in that: The specific options for control according to target injection superheat or target exhaust temperature are as follows: When the exhaust temperature value is greater than a first preset exhaust temperature, the auxiliary circuit electronic expansion valve (4) is controlled according to the target exhaust temperature; When the exhaust gas temperature value is less than or equal to the first preset exhaust gas temperature and greater than or equal to the fourth preset exhaust gas temperature, the auxiliary circuit electronic expansion valve (4) is controlled according to the target injection superheat; When the exhaust temperature value is less than the fourth preset exhaust temperature, the auxiliary circuit electronic expansion valve (4) is gradually closed in each adjustment cycle, and the step size of each action does not exceed 2 percent of the maximum opening of the auxiliary circuit electronic expansion valve (4).

9. The control method of a heat pump system according to claim 1, characterized in that: Also includes: Acquire the refrigerant flow rate controlled by the main electronic expansion valve (8) of the heat pump system and the refrigerant injection amount determined by the auxiliary electronic expansion valve (4) when the heat pump system is controlled according to S1-S3; Obtaining a flow-injection amount correspondence relationship between the refrigerant flow rate and the refrigerant injection amount in the same time series, and obtaining a main control parameter and an auxiliary control parameter under the flow-injection amount correspondence relationship; Based on the flow-injection amount correspondence, in combination with the main control parameter and the auxiliary control parameter, the secondary adjustment parameters of the main control parameter and the auxiliary control parameter are determined.

10. A control method for a heat pump system according to claim 9, characterized in that: The method of determining the secondary adjustment parameters of the main control parameters and the auxiliary control parameters based on the flow-injection amount correspondence relationship and combining the main control parameters and the auxiliary control parameters includes: Determine a difference curve between flow rate and injection amount from the flow rate-injection amount correspondence, obtain a first time range in which the difference is greater than a first preset difference from the difference curve, and obtain a second time range in which the difference is less than the first preset difference; Acquire a second opening relationship between the main opening and the auxiliary opening corresponding to the second time range from the main control parameter and the auxiliary control parameter, and determine a reference optimal opening ratio between the main opening and the auxiliary opening based on the second opening relationship; Acquire a first opening relationship between the main opening and the auxiliary opening corresponding to the first time range from the main control parameter and the auxiliary control parameter, and establish a corresponding relationship between the first opening relationship and a difference greater than a first preset difference; Based on the corresponding relationship, a proportional curve between the opening and the difference is obtained, based on the wave degree of the proportional curve, a correction weight for the reference optimal opening ratio is determined, and the reference optimal opening ratio is corrected according to the correction weight to obtain a target optimal opening ratio; When the difference between the real-time detected flow rate and the injection amount is greater than the first preset difference, the main control parameter and the auxiliary control parameter are adjusted secondary according to the target optimal opening ratio.

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