A heat pump system with start-up control

Abstract

The present application relates to a kind of hot pump systems with start-up control, the system carries out real-time monitoring to exhaust temperature and high pressure in the whole start-up phase, when exhaust temperature and high pressure are abnormal, then further according to the change value of exhaust superheat and the change amount of high pressure to adjust the opening of electronic expansion valve and the operating frequency of compressor;When exhaust temperature and high pressure are in the allowed range, the opening of electronic expansion valve and the frequency of compressor are controlled according to normal start-up procedure, to meet the system refrigerant circulation amount demand in start-up phase.The system acquires unit working condition parameters in real time, with the change trend of working condition parameters as control parameter, to control the opening of electronic expansion valve in advance, so that the system avoids the problem that exhaust superheat is insufficient in the early stage of start-up phase, and exhaust temperature is too high or pressure is too high in the late stage of start-up phase.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heat pump control, in particular to a heat pump system with start-up control. BACKGROUND

[0002] The heat pump system is a kind of high-efficiency, environmentally friendly energy utilization technology, and its core working principle is the reverse Carnot cycle, which converts the heat energy in the low-temperature heat source to the high-temperature environment by consuming a small amount of electric energy or other energy, to achieve the purpose of heating or refrigeration. As a kind of heat pump system, the air source heat pump system absorbs the low-temperature heat energy in the air with very little electric energy, and through the compression of the compressor, it becomes high-temperature heat energy, which is then transmitted to the place where heating or refrigeration is needed. It is favored by consumers and users, and has been widely used in hotels, schools, hospitals, saunas, beauty salons, swimming pools, laundry rooms and other places for refrigeration and hot water supply.

[0003] The existing heat pump system can operate in the interactive limit working condition of ultra-wide environmental temperature-35℃~45℃ and hot water temperature 15℃~55℃, but during the start-up stage of the system, the exhaust temperature is often too low, the exhaust temperature is too high, and the high pressure is too high, which affects the reliability of the unit.

[0004] The existing start-up control scheme mainly sets one or more low-frequency and medium-frequency running platforms during the start-up stage. After starting, the frequency of the compressor increases from low to high, and the electronic expansion valve adjusts to the low-frequency and medium-frequency running with an initial opening degree. Since the system is in a non-steady state process during the start-up stage, it is the stage with the largest system fluctuation. Adjusting with the initial opening degree cannot adapt to the changes of the system working condition parameters, resulting in insufficient exhaust overheating degree in the early stage of the start-up stage, and excessive exhaust temperature or high pressure in the late stage of the start-up stage, which even triggers a fault shutdown. SUMMARY

[0005] Therefore, the purpose of the present application is to provide a heat pump system with start-up control, which adjusts the opening degree of the electronic expansion valve in advance according to the trend of the key parameters of the unit, to solve the problems of insufficient exhaust overheating degree in the early stage of the start-up stage and excessive exhaust temperature or high pressure in the late stage of the start-up stage.

[0006] A heat pump system with start-up control, comprising a compressor, a four-way valve, a water-side heat exchanger, an electronic expansion valve, an air-side heat exchanger, a pressure monitoring module, a temperature monitoring module, and a controller electrically connected and / or communicatively connected to the compressor, the electronic expansion valve, the pressure monitoring module and the temperature monitoring module, characterized in that the controller controls the start-up of the heat pump system by the following method:

[0007] Obtain the exhaust temperature at the current time Determine the exhaust temperature at the current time relationship with a set exhaust temperature threshold value

[0008] If the current exhaust temperature is less than the exhaust temperature threshold value , the current high-pressure pressure F t and its corresponding condensation temperature are obtained According to the current exhaust temperature and the condensation temperature , the exhaust superheat degree is calculated The exhaust superheat degree belongs to the superheat degree interval; and according to the superheat degree interval, it is further determined whether the high-pressure pressure F t is greater than the set high-pressure pressure threshold value F TV ; and based on the pressure determination result, the high-pressure pressure change amount and the exhaust superheat degree change value are further obtained; and based on the high-pressure pressure change amount or the exhaust superheat degree change value, the opening of the electronic expansion valve is controlled or the normal start-up program control is performed, and the frequency of the compressor is controlled or the normal start-up program control is performed.

[0009] If the current exhaust temperature is greater than or equal to the exhaust temperature threshold value , it is determined whether the high-pressure pressure F t is greater than the set high-pressure pressure threshold value F TV ; and based on the pressure determination result, the high-pressure pressure change amount and the exhaust superheat degree change value are further obtained; and based on the high-pressure pressure change amount or the exhaust superheat degree change value, the opening of the electronic expansion valve is controlled or the normal start-up program control is performed, and the frequency of the compressor is controlled or the normal start-up program control is performed.

[0010] Further, the superheat degree interval of the exhaust superheat degree includes:

[0011] The first superheat degree interval is greater than or equal to the first exhaust superheat degree threshold value

[0012] The second superheat degree interval is less than the first exhaust superheat degree threshold value and greater than or equal to the second exhaust superheat degree threshold value

[0013]

[0014] The third superheat degree interval is less than the second exhaust superheat degree threshold value

[0015] Further, the exhaust superheat degree belongs to the first superheat degree interval, the current exhaust temperature is greater than or equal to the exhaust temperature threshold value​ Both perform the following steps:

[0016] S30 judges whether the high-pressure pressure F t is greater than the high-pressure pressure threshold F TV :

[0017] If the high-pressure pressure F t is greater than the high-pressure pressure threshold F TV , the compressor is prohibited from increasing the frequency, the electronic expansion valve is controlled to open by 20 pulses at the first valve opening rate, and the high-pressure pressure change amount ΔF t～t+T in the current valve opening period T is calculated:

[0018] If the high-pressure pressure change amount ΔF t～t+T is greater than or equal to 0, the electronic expansion valve is controlled to open by 20 pulses at the first valve opening rate, the compressor is controlled to decrease the frequency at the first frequency adjustment rate, and the high-pressure pressure in the next valve opening period is continuously obtained;

[0019] If the high-pressure pressure change amount ΔF t-1～t is less than 0, the electronic expansion valve is controlled to open by 20 pulses at the first valve opening rate, and the compressor performs the normal start-up procedure;

[0020] If the high-pressure pressure F t is less than or equal to the high-pressure pressure threshold F TV , the electronic expansion valve is controlled to open by 20 pulses at the first valve opening rate, the exhaust gas superheat degree in the current valve opening period T is calculated: and the change value of the exhaust gas superheat degree in the previous valve opening period T-1 is greater than or equal to 0:

[0021] If the exhaust gas superheat degree change value is greater than or equal to 0, the electronic expansion valve is controlled to open by 20 pulses at the first valve opening rate, and the compressor performs the normal start-up procedure;

[0022] If the exhaust gas superheat degree change value is less than 0, the electronic expansion valve is controlled to maintain the current opening degree, and the compressor performs the normal start-up procedure.

[0023] Further, if the exhaust gas superheat degree belongs to the second superheat degree interval, the following steps are performed:

[0024] S40 judges whether the high-pressure pressure F t is greater than the high-pressure pressure threshold F TV :

[0025] If the high-pressure pressure F t is greater than the high-pressure pressure threshold F TV, control the electronic expansion valve to open up 20 pulse at the first valve adjusting rate, and calculate the high-pressure pressure change value t～t+T whether greater than or equal to 0:

[0026] if the high-pressure pressure change value t～t+T is greater than or equal to 0, control the electronic expansion valve to keep the current opening degree, and control the compressor to reduce the frequency at the first frequency adjusting rate, and continue to acquire the high-pressure pressure of the next valve adjusting period;

[0027] if the high-pressure pressure change value t～t+T is less than 0, control the electronic expansion valve to keep the current opening degree, and control the compressor to perform the normal starting program;

[0028] if the high-pressure pressure F t is less than or equal to the high-pressure pressure threshold value F TV , control the electronic expansion valve and the compressor to perform the normal starting program.

[0029] further, the exhaust gas superheat degree belongs to the third superheat degree interval, and the following steps are performed:

[0030] S50 judges whether the high-pressure pressure F t is greater than the high-pressure pressure threshold value F TV :

[0031] if the high-pressure pressure F t is greater than the high-pressure pressure threshold value F TV , control the electronic expansion valve to keep the current opening degree, calculate the high-pressure pressure change value t～t+T of the current valve adjusting period T whether greater than or equal to 0:

[0032] if the high-pressure pressure change value t～t+T is greater than or equal to 0, control the compressor to prohibit frequency increase, and control the electronic expansion valve to perform the normal starting program;

[0033] if the high-pressure pressure change value t～t+T is less than 0, control the compressor to increase the frequency at the first frequency adjusting rate, and control the electronic expansion valve to perform the normal starting program;

[0034] if the high-pressure pressure F t is less than or equal to the high-pressure pressure threshold value F TV , control the electronic expansion valve to close 20 pulse at the first valve adjusting rate, calculate the exhaust gas superheat degree of the current valve adjusting period T and the change value of the exhaust gas superheat degree of the previous valve adjusting period T-1 belong to the interval:

[0035] if the exhaust gas superheat degree change value is greater than or equal to 2, control the electronic expansion valve to keep the current opening degree, and control the compressor to perform the normal starting program;

[0036] If the change in exhaust superheat is greater than or equal to 1 and less than 2, the opening of the electronic expansion valve is reduced by 5 pulses, and the compressor is controlled to execute the normal start-up procedure.

[0037] If the change in exhaust superheat is less than 1, the electronic expansion valve is closed by 20 pulses at the first regulating rate, and the compressor is controlled to execute the normal start-up procedure.

[0038] Furthermore, the normal startup procedure for the compressor is as follows:

[0039] Get the compressor's operating frequency P at the current moment. t :

[0040] If the compressor's operating frequency P at the current moment t If the frequency is less than the first frequency threshold, control the compressor to increase the frequency to the first frequency threshold at the first frequency increase rate and maintain it for a first time period t1.

[0041] If the compressor's operating frequency P at the current moment t If the frequency is greater than or equal to the first frequency threshold and less than the second frequency threshold, control the compressor to increase the frequency to the second frequency threshold at the second frequency increase rate and maintain operation for the second time period t2.

[0042] If the compressor's operating frequency P at the current moment t The frequency is equal to the highest frequency under the current operating conditions. Stop increasing the frequency and control the compression to operate at a constant frequency.

[0043] Furthermore, the normal start-up procedure for the electronic expansion valve is as follows:

[0044] Obtain the current compressor frequency operating status:

[0045] If it is in frequency-increase operation mode, then obtain the compressor's operating frequency P at the current moment within the current valve control cycle T. t Return water temperature Ambient temperature Adjust the opening K of the electronic expansion valve at the current moment according to the above parameters. t The K t satisfy:

[0046] K t =K0+α*β*ΔP t-1～t

[0047] Where K0 is the initial opening of the electronic expansion valve, which is 60 pulses; α is the current return water temperature of the system. The opening correction factor corresponding to the temperature zone; β is the ambient temperature of the system at the current moment. The opening correction factor corresponding to the temperature zone; ΔP t-1～tis the variation of the running frequency of the compressor at the previous time and the current time;

[0048] If it is the constant frequency operation mode, the superheat of the return gas of the system at the current time in the current valve adjustment period T is obtained, and the opening of the electronic expansion valve at the current time is adjusted according to the existing superheat of the return gas.

[0049] Compared with the prior art, the heat pump system with start-up control has the advantages that the working condition parameters of the unit are collected in real time, the variation trend of the working condition parameters is taken as the control parameter, the opening of the electronic expansion valve is controlled in advance, the system avoids the problems that the exhaust gas superheat is insufficient at the initial stage of the start-up phase and the exhaust gas temperature is too high or the pressure is too high at the later stage of the start-up phase.

[0050] In order to better understand and implement, the application will be described in detail below with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0051] Figure 1 It is a system structure schematic diagram of an embodiment of the application.

[0052] Figure 2 It is a flow chart of the electronic expansion valve control method of an embodiment of the application. DETAILED DESCRIPTION

[0053] The technical solutions of the application will be described in detail below with reference to the drawings of the embodiments of the application.

[0054] In order to solve the problems that the existing heat pump system adopts the inherent initial opening to adjust the electronic expansion valve at the start-up phase, the exhaust gas superheat is insufficient at the initial stage of the start-up phase, the exhaust gas temperature is too high or the pressure is too high at the later stage of the start-up phase, and even the problem that the fault shutdown is triggered, the application provides a heat pump system with start-up control, and a start-up control method of the system. The start-up control method of the system implements real-time monitoring of the exhaust gas temperature and the high pressure during the entire start-up phase. When the exhaust gas temperature and the high pressure are abnormal, the opening of the electronic expansion valve and the running frequency of the compressor are further adjusted according to the variation value of the exhaust gas superheat and the variation of the high pressure. When the exhaust gas temperature and the high pressure are within the allowable range, the opening of the electronic expansion valve and the frequency of the compressor are controlled according to the normal start-up program, so as to meet the demand of the refrigerant circulation amount of the system at the start-up phase. The start-up control method of the system collects the working condition parameters of the unit in real time, takes the variation trend of the working condition parameters as the control parameter, controls the opening of the electronic expansion valve in advance, and avoids the problems that the exhaust gas superheat is insufficient at the initial stage of the start-up phase and the exhaust gas temperature is too high or the pressure is too high at the later stage of the start-up phase.

[0055] In the specific implementation, please refer to Figure 1The heat pump system with start-up control proposed in this invention includes a compressor 10, a four-way valve 20, a water-side heat exchanger 30, an electronic expansion valve 40, an air-side heat exchanger 50, a pressure detection module 60, a temperature detection module 70, a controller (not shown), and other auxiliary pipes, all connected via refrigerant piping. The controller is electrically or communicatively connected to the compressor 10, the electronic expansion valve 40, the pressure detection module 60, and the temperature detection module 70.

[0056] An electromagnetic expansion valve 40 is installed on the refrigerant pipeline between the water-side heat exchanger 30 and the air-side heat exchanger 50 to throttle the medium-temperature, high-pressure liquid refrigerant into a low-temperature, low-pressure refrigerant. Furthermore, the electromagnetic expansion valve 40 is also equipped with a filter.

[0057] The pressure detection module 60 includes a first pressure sensor 61 and a second pressure sensor 62. The first pressure sensor 61 is located between the exhaust end of the compressor 10 and the inlet of the four-way valve, and is used to collect the pressure signal of the high-temperature and high-pressure gaseous refrigerant discharged by the compressor 10, and to convert the refrigerant high pressure P H The corresponding condensation temperature T C The signal is transmitted to the controller. The second pressure sensor 62 is located between the inlet of the compressor 10 and the outlet of the four-way valve. It is used to collect the pressure signal of the low-temperature, low-pressure gaseous refrigerant drawn into the compressor 10 and to transmit the refrigerant low-pressure P signal to the controller. D The corresponding evaporation temperature T E Transmitted to the controller.

[0058] The temperature detection module 70 includes a first temperature sensor 71, a second temperature sensor 72, a third temperature sensor 73, and a fourth temperature sensor 74. The first temperature sensor 71 is located at the discharge end of the compressor 10 and is used to collect the actual discharge temperature of the compressor 10. and the actual exhaust temperature The data is transmitted to the controller. The second temperature sensor 72 is located at the return gas end of the compressor 10 and is used to collect the actual return gas temperature T of the compressor 10. B and the actual return gas temperature T B The data is transmitted to the controller. A third temperature sensor 73 is located at the return water end of the water-side heat exchanger 30 to collect the return water temperature. and return water temperature The data is transmitted to the controller. The fourth temperature sensor 74 is used to collect ambient temperature data. and ambient temperature The data is transmitted to the controller. The fourth temperature sensor 74 can be located on the outside of the air-side heat exchanger 30 or on the heat pump system casing. This application does not impose any restrictions.

[0059] The controller comprises a storage unit and a processing unit, the storage unit is used for receiving the pressure and temperature signals collected by the pressure detection module 60 and the temperature detection module 70, the operating frequency of the compressor 10, and various set threshold values and coefficients; the processing unit is used for calculation, logical judgment and control according to the collected signals and information.

[0060] Specifically, please refer to Figure 2 The controller of the heat pump system of the present application carries out start-up control by the following method.

[0061] S10 obtains the exhaust temperature at the current time judges whether the exhaust temperature at the current time is greater than or equal to the set exhaust temperature threshold value

[0062] If the exhaust temperature at the current time is less than the exhaust temperature threshold value then step S20 is executed;

[0063] If the exhaust temperature at the current time is greater than or equal to the exhaust temperature threshold value then step S30 is executed.

[0064] The exhaust temperature threshold value is 95℃.

[0065] S20 obtains the system high-pressure F at the current time t and the corresponding condensing temperature According to the exhaust temperature at the current time and the condensing temperature the exhaust superheat degree is calculated The exhaust superheat degree is determined The superheat degree interval is determined

[0066] If the exhaust superheat degree is greater than or equal to the first exhaust superheat degree threshold value that is, the exhaust superheat degree is in the first superheat degree interval: then step S30 is executed;

[0067] If the exhaust superheat degree is less than the first exhaust superheat degree threshold value and greater than or equal to the second exhaust superheat degree threshold value that is, the exhaust superheat degree is in the second superheat degree interval: and then step S40 is executed;

[0068] If the exhaust superheat degree is less than the second exhaust superheat degree threshold value i.e. exhaust gas superheat in a third superheat range: Step S50 is performed.

[0069] said first exhaust gas superheat threshold value is 40℃. Said second exhaust gas superheat threshold value is 10℃.

[0070] S30 judges whether the high pressure F t is greater than a high pressure threshold value F TV :

[0071] If the high pressure F t is greater than the high pressure threshold value F TV , the compressor is prohibited from increasing frequency, the electronic expansion valve is controlled to open by 20 pulses at a first valve adjustment rate, and the change amount ΔF t～t+T of the high pressure in the current valve adjustment period T is calculated:

[0072] If the change amount ΔF t～t+T of the high pressure is greater than or equal to 0, the electronic expansion valve is controlled to open by 20 pulses at the first valve adjustment rate, the compressor is controlled to decrease frequency at a first frequency adjustment rate, and the high pressure of the next valve adjustment period is continuously obtained.

[0073] If the change amount ΔF t-1～t of the high pressure is less than 0, the electronic expansion valve is controlled to open by 20 pulses at the first valve adjustment rate, and the compressor is controlled to perform a normal start-up procedure.

[0074] If the high pressure F t is less than or equal to the high pressure threshold value F TV , the electronic expansion valve is controlled to open by 20 pulses at the first valve adjustment rate, and the change value of the exhaust gas superheat in the current valve adjustment period T and the exhaust gas superheat in the previous valve adjustment period T-1 is calculated:

[0075] If the change value of the exhaust gas superheat is greater than or equal to 0, the electronic expansion valve is controlled to open by 20 pulses at the first valve adjustment rate, and the compressor is controlled to perform a normal start-up procedure.

[0076] If the change value of the exhaust gas superheat is less than 0, the electronic expansion valve is controlled to maintain the current opening degree, and the compressor is controlled to perform a normal start-up procedure.

[0077] Said high pressure threshold value F TV is 3.6 MPa, and different high pressure threshold values can be set according to the properties of different refrigerants.

[0078] Said first valve adjustment rate is 1 pulse / s.

[0079] The first frequency modulation rate is 1 Hz / 10 s.

[0080] S40 judges high-pressure pressure F t whether greater than high-pressure pressure threshold F TV :

[0081] If the high-pressure pressure F t is greater than the high-pressure pressure threshold F TV , the compressor is prohibited from increasing the frequency, the electronic expansion valve is controlled to open by 20 pulses at the first valve modulation rate, and the high-pressure pressure change amount ΔF in the current valve modulation period T is calculated. t～t+T whether greater than or equal to 0:

[0082] If the high-pressure pressure change amount ΔF t～t+T is greater than or equal to 0, the electronic expansion valve is controlled to maintain the current opening degree, the compressor is controlled to decrease the frequency at the first frequency modulation rate, and the high-pressure pressure in the next valve modulation period is continuously acquired.

[0083] If the high-pressure pressure change amount ΔF t～t+T is less than 0, the electronic expansion valve is controlled to maintain the current opening degree, and the compressor is controlled to perform a normal start-up program.

[0084] If the high-pressure pressure F t is less than or equal to the high-pressure pressure threshold F TV , the electronic expansion valve and the compressor are controlled to perform a normal start-up program.

[0085] S50 judges high-pressure pressure F t whether greater than high-pressure pressure threshold F TV :

[0086] If the high-pressure pressure F t is greater than the high-pressure pressure threshold F TV , the electronic expansion valve is controlled to maintain the current opening degree, and the high-pressure pressure change amount ΔF in the current valve modulation period T is calculated. t～t+T whether greater than or equal to 0:

[0087] If the high-pressure pressure change amount ΔF t～t+T is greater than or equal to 0, the compressor is prohibited from increasing the frequency, and the electronic expansion valve is controlled to perform a normal start-up program.

[0088] If the high-pressure pressure change amount ΔF t～t+T is less than 0, the compressor is controlled to increase the frequency at the first frequency modulation rate, and the electronic expansion valve is controlled to perform a normal start-up program.

[0089] If the high-pressure pressure F t is less than or equal to the high-pressure pressure threshold F TV , the electronic expansion valve is controlled to close by 20 pulses at the first valve modulation rate, and the exhaust superheat degree in the current valve modulation period T is calculated. the exhaust gas superheat degree of the previous valve adjustment period T-1 the change value of the exhaust gas superheat degree belongs to:

[0090] If the change value of the exhaust gas superheat degree is greater than or equal to 2, the electronic expansion valve is controlled to maintain the current opening degree, and the compressor is controlled to perform a normal start-up procedure.

[0091] If the change value of the exhaust gas superheat degree is greater than or equal to 1 and less than 2, the opening degree of the electronic expansion valve is controlled to decrease by 5 pulses, and the compressor is controlled to perform a normal start-up procedure.

[0092] If the change value of the exhaust gas superheat degree is less than 1, the electronic expansion valve is controlled to decrease by 20 pulses at a first valve adjustment rate, and the compressor is controlled to perform a normal start-up procedure.

[0093] In the present application, the normal start-up control procedure of the compressor frequency control is SOA, and the normal start-up control procedure of the opening degree control of the electronic expansion valve is SOB.

[0094] SOA obtains the operating frequency P of the compressor at the current time t , determines the control frequency interval of the operating frequency P of the compressor at the current time t , and performs corresponding frequency control according to the control frequency interval.

[0095] If the operating frequency P of the compressor at the current time t is less than a first frequency threshold, the compressor is controlled to increase in frequency to the first frequency threshold at a first frequency increase rate and maintain operation for a first time period t1.

[0096] If the operating frequency P of the compressor at the current time t is greater than or equal to the first frequency threshold and less than a second frequency threshold, the compressor is controlled to increase in frequency to the second frequency threshold at a second frequency increase rate and maintain operation for a second time period t2.

[0097] If the operating frequency P of the compressor at the current time t is equal to the highest frequency under the current working condition, the frequency increase is stopped, and the compressor is controlled to operate at a constant frequency.

[0098] The first frequency threshold is 45 Hz.

[0099] The first frequency increase rate is 2 Hz / s.

[0100] The first time period t1 is 1 min.

[0101] The second frequency threshold is 62 Hz.

[0102] The second frequency increase rate is 1 Hz / s.

[0103] The second time period t2 is 1 min.

[0104] S0B obtains the current compressor frequency operating status:

[0105] If it is in frequency-increase operation mode, then obtain the compressor's operating frequency P at the current moment within the current valve control cycle T. t Return water temperature Ambient temperature Adjust the opening K of the electronic expansion valve at the current moment according to the above parameters. t ;

[0106] If it is in constant frequency operation mode, the system return gas superheat is obtained within the current valve control cycle T at the current moment, and the opening of the electronic expansion valve at the current moment is adjusted according to the existing return gas superheat.

[0107] In one embodiment, during the entire startup phase, the basic principle for increasing the compressor frequency to the target frequency is to adjust the opening of the electronic expansion valve according to the frequency change, wherein K t satisfy:

[0108] K t =K0+α*β*ΔP t-1～t

[0109] Where K0 is the initial opening of the electronic expansion valve, which is 60 pulses; α is the current return water temperature of the system. The opening correction factor corresponding to the temperature zone is shown in Table 1; β is the ambient temperature of the system at the current moment. The opening correction factor corresponding to the temperature zone is shown in Table 2; ΔP t-1～t It is the change in the compressor's operating frequency between the previous moment and the current moment.

[0110] Table 1 Return Water Temperature Temperature range corresponding to the opening correction factor

[0111]

[0112] Table 2 Ambient Temperature Temperature range corresponding to the opening correction factor

[0113]

[0114] The application implements real-time monitoring of exhaust temperature and high pressure during the whole start-up stage, and when the exhaust temperature and high pressure are abnormal, the opening degree of the electronic expansion valve and the operating frequency of the compressor are further adjusted according to the exhaust superheat change value and the high pressure change amount; when the exhaust temperature and high pressure are in the allowable range, the initial opening degree of the electronic expansion valve is taken as the basic opening valve position, the unit operating inlet water temperature, the ambient temperature and the frequency change of the compressor are taken as the opening degree adjustment parameters, so that the opening degree adjustment of the electronic expansion valve corresponds to the unit frequency change, the system refrigerant circulation amount demand in the start-up stage is met, and the problems of insufficient exhaust superheat at the initial stage of the start-up stage and excessively high exhaust temperature or high pressure at the late stage of the start-up stage are solved, and even the fault shutdown is triggered. The whole start-up control idea is based on the fact that the compressor frequency is gradually increased during the start-up stage, and the unit refrigerant and the system are in a fluctuating state or a shock period, and the control idea is to control the operating parameters to meet the safety bottom limit of the unit operation, and then the electronic expansion valve opening degree is controlled according to the control unit back gas superheat idea when the compressor reaches the target frequency.

[0115] The terms used in the embodiments of the present application are merely for the purpose of describing specific embodiments and are not intended to limit the embodiments of the present application. The singular forms "a", "an" and "the" used in the embodiments of the present application and the claims are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that "multiple" and "several" refer to two or more, unless otherwise stated; "and / or" means any or all possible combinations of one or more associated listed items; "first", "second", "third", etc. are only used for distinction, not for describing a specific order or sequence, and cannot be understood as indicating or implying relative importance. When the above description refers to the drawings, the same numbers in different drawings represent the same or similar elements, unless otherwise indicated. In the description of the present application, the specific meanings of the above terms in the present application can be understood by those skilled in the art according to the specific circumstances.

[0116] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as limiting the scope of the patent. It should be noted that for those skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, and the present application also intends to include these modifications and improvements.

Claims

1. A heat pump system with start-up control, comprising a compressor, a four-way valve, a water-side heat exchanger, an electronic expansion valve, an air-side heat exchanger, a pressure monitoring module, a temperature monitoring module, and a controller electrically connected and / or communicatively connected to the compressor, the electronic expansion valve, the pressure monitoring module, and the temperature monitoring module, characterized in that, The controller controls the start of the heat pump system in the following manner: acquiring the current exhaust temperature judging the relationship between the current exhaust temperature and a set exhaust temperature threshold ​ If the exhaust gas temperature at the current time is less than an exhaust gas temperature threshold , then the high-pressure pressure at the current time and its corresponding condensing temperature are obtained, and the exhaust gas superheat degree is calculated according to the exhaust gas temperature at the current time and the condensing temperature . when the exhaust gas superheat degree ≥ the first exhaust gas superheat degree threshold value : If high pressure High pressure threshold , prohibit compressor frequency increase, control electronic expansion valve to open at a first valve adjustment rate, and calculate the high pressure change in the current valve adjustment period T If the high pressure change ≥ 0, control the electronic expansion valve to open at a first valve adjustment rate, and the compressor to decrease at a first frequency adjustment rate If the high pressure change < 0, control the electronic expansion valve to open at a first valve adjustment rate, and the compressor to execute a normal start-up procedure if high pressure pressure ≤ high pressure pressure threshold value , control the electronic expansion valve to open at a first valve adjustment rate, and calculate the exhaust gas superheat degree of the current valve adjustment period T and the exhaust gas superheat degree of the last valve adjustment period T-1 , if the change value ≥ 0, control the electronic expansion valve to open at a first valve adjustment rate, and the compressor executes a normal start-up procedure, if the change value < 0, control the electronic expansion valve to maintain the current opening degree, and the compressor executes a normal start-up procedure; when the second exhaust gas superheat threshold ≤ exhaust gas superheat < first exhaust gas superheat threshold : If high pressure High pressure threshold , prohibit compressor frequency increase, control electronic expansion valve to open at the first valve speed, and calculate the high pressure change in the current valve period T , such as high pressure change ≥ 0, control electronic expansion valve to maintain the current opening, compressor to reduce the first frequency rate, such as high pressure change <0, control electronic expansion valve to maintain the current opening, compressor to execute normal start-up procedure; if high pressure pressure ≤ high pressure pressure threshold , control the electronic expansion valve and the compressor to perform a normal start-up procedure; When the exhaust gas superheat degree < Second exhaust gas superheat degree threshold value : If high pressure High pressure threshold , control electronic expansion valve to keep the current opening, and calculate the current valve period T high pressure change , such as high pressure change ≥ 0, prohibit the compressor frequency, control electronic expansion valve to perform normal start procedure, such as high pressure change <0, control compressor to the first frequency rate, electronic expansion valve to perform normal start procedure; if high pressure pressure ≤ high pressure pressure threshold value , control the electronic expansion valve to close at a first valve adjustment rate, and calculate the exhaust gas superheat degree of the current valve adjustment period T and the change value of the exhaust gas superheat degree of the last valve adjustment period T-1 , if the change value ≥ 2, control the electronic expansion valve to keep the current opening degree, and the compressor executes a normal start-up procedure, if the change value ≥ 1 and < 2, control the opening degree of the electronic expansion valve to close, and the compressor executes a normal start-up procedure, if the change value < 1, control the electronic expansion valve to close at a first valve adjustment rate, and the compressor executes a normal start-up procedure; If the exhaust gas temperature at the current time is greater than or equal to an exhaust gas temperature threshold value , then the opening of the electronic expansion valve is controlled according to the exhaust gas superheat ≥ a first exhaust gas superheat threshold value , or the frequency of the compressor is controlled according to the frequency or normal startup program control.

2. The heat pump system of claim 1, wherein, when the exhaust gas superheat degree ≥ the first exhaust gas superheat degree threshold value , or the exhaust gas temperature at the current time is greater than or equal to the exhaust gas temperature threshold value , both perform the following steps: S30 Determine if high pressure is greater than high pressure threshold :​ If the high pressure is greater than the high pressure threshold , the compressor is prohibited from increasing the frequency, the electronic expansion valve is controlled to open at a first valve opening rate, and the change in the high pressure in a current valve opening period T is calculated whether the change in the high pressure is greater than or equal to 0:​ As the high-pressure pressure variation amount If the high-pressure pressure variation amount is greater than 0, the electronic expansion valve is controlled to open at a first valve speed of 20 pulses, the compressor is controlled to reduce the frequency at a first frequency speed, and the high-pressure pressure of the next valve period is continuously acquired. As the high pressure pressure variation amount Less than 0, control the electronic expansion valve to open 20 pulse at the first valve opening rate, and control the compressor to execute the normal start-up procedure; If the high pressure is Less than or equal to a high pressure threshold value , control the electronic expansion valve to open at a first valve rate of 20 pulse, calculate the exhaust gas superheat degree of the current valve period T The change value of the exhaust gas superheat degree of the last valve period T-1 Whether it is greater than or equal to 0: If the change value of the exhaust gas superheat is greater than or equal to 0, the electronic expansion valve is controlled to open by 20 pulse at a first valve adjusting rate, and the compressor is controlled to execute a normal start procedure; If the change value of the exhaust gas superheat is less than 0, the electronic expansion valve is controlled to maintain the current opening degree, and the compressor is controlled to execute a normal start procedure.

3. The heat pump system of claim 2, wherein, when the second exhaust gas superheat threshold ≤ exhaust gas superheat < first exhaust gas superheat threshold the following steps are performed: S40 determining whether the high pressure is greater than a high pressure threshold :​ If the high pressure is greater than the high pressure threshold If the high pressure is greater than the high pressure threshold If the high pressure is greater than the high pressure threshold If the high pressure is greater than the high pressure threshold As the high-pressure pressure variation amount Greater than or equal to 0, the control electronic expansion valve maintains the current opening degree, the compressor reduces the frequency at the first frequency modulation rate, and the high-pressure pressure of the next valve period is continuously acquired; As the high pressure pressure change amount Less than 0, control electronic expansion valve to maintain the current opening, control compressor to perform normal start-up procedure; If the high pressure is less than or equal to a high pressure threshold value , control the electronic expansion valve and the compressor to perform a normal start-up procedure.

4. The heat pump system of claim 3, wherein, when the exhaust gas superheat degree < second exhaust gas superheat degree threshold value the following steps are performed: S50 Determine if high pressure is greater than high pressure threshold :​ If the high pressure is greater than the high pressure threshold If the high pressure is greater than the high pressure threshold If the high pressure is greater than the high pressure threshold If the high pressure is greater than the high pressure threshold As the high pressure pressure change amount Greater than or equal to 0, prohibit the compressor frequency rise, control electronic expansion valve to perform normal start-up procedure; As the high pressure pressure variation amount Less than 0, control the compressor to increase frequency at a first frequency modulation rate, and control the electronic expansion valve to execute a normal starting procedure; If high pressure pressure Less than or equal to high pressure pressure threshold value , control electronic expansion valve to close 20 pulse at first valve opening rate, calculate exhaust gas superheat degree of current valve opening period T Change value of exhaust gas superheat degree of last valve opening period T-1 Belongs to interval: If the change value of the exhaust gas superheat is greater than or equal to 2, the electronic expansion valve is controlled to maintain the current opening degree, and the compressor is controlled to execute a normal start procedure; If the change value of the exhaust gas superheat is greater than or equal to 1 and less than 2, the opening degree of the electronic expansion valve is controlled to close by 5 pulse, and the compressor is controlled to execute a normal start procedure; If the change value of the exhaust gas superheat is less than 1, the electronic expansion valve is controlled to close by 20 pulse at a first valve adjusting rate, and the compressor is controlled to execute a normal start procedure.

5. The heat pump system of claim 1, wherein, The normal start procedure of the compressor is as follows: obtaining a current compressor operating frequency : If the compressor's operating frequency at the current moment If the frequency is less than the first frequency threshold, control the compressor to increase the frequency to the first frequency threshold at the first frequency increase rate and maintain it for a first time period t1. If the compressor's operating frequency at the current moment If the frequency is greater than or equal to the first frequency threshold and less than the second frequency threshold, control the compressor to increase the frequency to the second frequency threshold at the second frequency increase rate and maintain operation for the second time period t2. If the compressor's operating frequency at the current time equals the highest frequency at the current operating condition, stop increasing the frequency, and control the compressor to operate at a constant frequency.

6. The heat pump system of claim 1, wherein, The normal start procedure of the electronic expansion valve is as follows: The frequency running state of the compressor at the current time is obtained: If the frequency raising operation mode, the current compressor operation frequency in the current valve adjustment period T is obtained , return water temperature , ambient temperature , the opening of the electronic expansion valve at the current time is adjusted according to the above parameters , the satisfy: wherein, is the initial opening degree of the electronic expansion valve, 60 pulse; is the return water temperature of the system at the current time is the opening degree correction coefficient corresponding to the temperature zone where the system is located; is the ambient temperature of the system at the current time is the opening degree correction coefficient corresponding to the temperature zone where the system is located; is the change amount of the operating frequency of the compressor between the previous time and the current time; If it is a constant frequency running mode, the back gas superheat of the system at the current time within the current valve adjusting period T is obtained, and the opening degree of the electronic expansion valve at the current time is adjusted according to the existing back gas superheat.

7. The heat pump system of claim 6, wherein, Return water temperature The opening correction coefficient corresponding to the temperature zone The value is as follows: when the backwater temperature is less than or equal to 30°C, = 1.5; when the backwater temperature is greater than 30°C and less than 45°C, = 2; When the backwater temperature is greater than or equal to 45°C, = 2.

5.

8. Heat pump system according to claim 6 or 7, characterized in that, Ambient temperature The opening degree correction coefficient corresponding to the temperature zone The value is as follows: When the ambient temperature is less than or equal to -15°C, = 1 ; When the ambient temperature is greater than -15°C and less than 0°C, = 1.5; When the ambient temperature is greater than or equal to 0°C and less than or equal to 15°C, = 2.0; When the ambient temperature is greater than 15°C and less than 30°C, = 2.5; When the ambient temperature is greater than or equal to 30°C, = 3.

9. The heat pump system of claim 8, wherein, the exhaust gas temperature threshold is 95°C; the first exhaust gas superheat threshold is 40°C; the second exhaust gas superheat threshold is 10°C; the high pressure threshold is 3.6 MPa.

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