Air conditioner heat pump system capable of preventing compressor from being frequently started and stopped

Abstract

The invention relates to an air conditioner heat pump system capable of preventing frequent start and stop of a compressor, which comprises the following steps: acquiring an actual temperature Tc, calculating an actual temperature difference Tc between the actual temperature Tc and a set temperature Tset, and judging the size relationship between the actual temperature difference Tc and a set frequency conversion return difference Tb: if Tc is greater than Tb, controlling the compressor to work at the highest gear; if Tc belongs to [-Tb, Tb], controlling the gear Fn of the compressor to be determined through a formula; and if Tc is smaller than-Tb, the compressor is controlled to work or stop at the lowest gear. The working gear change of the compressor is smoother, the impact caused by state switching is reduced, the temperature is kept close to the set value, meanwhile, the compressor is prevented from being started and stopped frequently when the temperature difference is close to the set value, and therefore energy is saved.

Description

Technical Field

[0001] The invention relates to the technical field of air-conditioning heat pumps, and in particular to an air-conditioning heat pump system capable of preventing a compressor from being frequently started and stopped. Background Art

[0002] As an energy-efficient heat conversion device, air conditioning heat pump system is widely used in hot water supply, heating and cooling. Traditional air conditioning heat pump system usually includes core components such as compressor, first heat exchanger, throttling assembly and second heat exchanger, and realizes heat transfer through the circulation of refrigerant. In actual operation, the performance of air conditioning heat pump system depends largely on the operating frequency of the compressor, and the frequency adjustment of the compressor directly affects the energy efficiency and stability of the system.

[0003] In the prior art, especially in air conditioning heat pump systems, the compressor may temporarily shut down when the temperature reaches the set temperature. Specifically, when the compressor starts to work, it will first run at a lower starting frequency, and then quickly increase the frequency to the set higher or highest operating frequency (target frequency). The temperature continues to rise in this process. Once the temperature reaches the set temperature, the compressor will reduce the frequency and work at a lower operating frequency to maintain the temperature. However, in most cases, when the compressor works at the highest operating frequency, the temperature will rise rapidly and the temperature difference between the set temperature and the set temperature will be too high, which can easily trigger a temperature shutdown. The compressor will stop working. As the temperature gradually drops and falls below the set value, the compressor will restart.

[0004] However, the frequent start and stop of the compressor will aggravate the wear of mechanical and electrical components in the air conditioning heat pump unit, shorten the life of the equipment, increase energy consumption, reduce system energy efficiency, and will inevitably lead to large temperature fluctuations and increased noise during the frequent start and stop process, affecting user comfort. In order to solve the above problems, the present invention proposes an air conditioning heat pump system with anti-frequent start and stop of the compressor, which realizes smooth gear switching and precise temperature control by dynamically adjusting the working gear of the compressor, thereby improving the energy efficiency and stability of the system. Summary of the invention

[0005] Based on this, the purpose of the present invention is to overcome the defects or shortcomings of the prior art and provide an air conditioning heat pump system that can prevent the compressor from being frequently started and stopped.

[0006] An air conditioning heat pump system with the function of preventing the compressor from starting and stopping frequently comprises a compressor, a four-way valve, a first heat exchanger, a throttling assembly and a second heat exchanger connected in sequence by a refrigerant circulation pipeline, wherein the first heat exchanger exchanges heat with a user end; further comprising a temperature sensor for detecting the temperature of the user end, and a controller, wherein the temperature sensor, the compressor and the controller are connected electrically or by communication; characterized in that the controller controls the working gear of the compressor in the following manner:

[0007] Get the actual temperature Tc, calculate the actual temperature difference △Tc between the actual temperature Tc and the set temperature Tset, and determine the size relationship between the actual temperature difference △Tc and the set frequency conversion hysteresis △Tb:

[0008] If △Tc>△Tb, the compressor is controlled to operate at the highest gear;

[0009] If △Tc∈[-△Tb,△Tb], the gear position Fn of the compressor is determined by the following formula:

[0010]

[0011] Where a is the adjustment coefficient, and the value range of a is a∈(0,5); n represents the gear value, n∈{1,2,…,10}; represents the ceiling function;

[0012] If △Tc<-△Tb, control the compressor to operate at the lowest gear or stop.

[0013] Compared with the prior art, the control method of the present invention achieves smoother gear changes in the compressor working gear, reduces the impact of state switching, keeps the temperature close to the set value, and avoids frequent starting and stopping of the compressor when the temperature difference is close to the set value, thereby achieving energy saving.

[0014] In one embodiment, if ΔTc<-ΔTb, it is further determined whether the set frequency conversion hysteresis ΔTb is less than the set shutdown hysteresis ΔTt:

[0015] If so, control the compressor to work at the lowest gear;

[0016] If not, control the compressor to stop.

[0017] In one embodiment, in order to eliminate the influence of normal temperature fluctuation on the calculation of the compressor working gear, the following control method is also included:

[0018] Get the average temperature Tc1 within t seconds before switching gears and the average temperature Tc2 within t seconds after switching gears, and determine the relationship between the average temperature Tc1 and the average temperature Tc2:

[0019] If the average temperature Tc1 is less than the average temperature Tc2, the gear position Fn of the compressor is determined by the following formula:

[0020]

[0021] If the average temperature Tc1> the average temperature Tc2, the gear position Fn of the compressor is determined by the following formula:

[0022]

[0023] If the average temperature Tc1 = the average temperature Tc2, the formula for determining the compressor gear position Fn remains unchanged;

[0024] Among them, △T0 is the temperature fluctuation threshold.

[0025] In one embodiment, a control method for restarting the compressor after stopping is also included:

[0026] Get the actual temperature Tc, calculate the actual temperature difference △Tc between the actual temperature Tc and the set temperature Tset, and determine the difference between the actual temperature difference △Tc and the set restart hysteresis △Tq. If the actual temperature difference △Tc is greater than the set restart hysteresis △Tq, control the compressor to restart.

[0027] The set restart hysteresis ΔTq is greater than or equal to the set frequency conversion hysteresis ΔTb.

[0028] In one embodiment, the adjustment coefficient a is 4.5, the frequency conversion hysteresis △Tb is set to 2°C, the shutdown hysteresis △Tt is set to 2°C, and the temperature fluctuation threshold △T0 is set to 0.2°C.

[0029] In addition, the present invention also provides a compressor frequency control method for preventing frequent start and stop, comprising the following steps:

[0030] Get the actual temperature Tc, calculate the actual temperature difference △Tc between the actual temperature Tc and the set temperature Tset, and determine the size relationship between the actual temperature difference △Tc and the set frequency conversion hysteresis △Tb:

[0031] If △Tc>△Tb, the compressor is controlled to operate at the highest gear;

[0032] If △Tc∈[-△Tb,△Tb], the gear position Fn of the compressor is determined by the following formula:

[0033]

[0034] Where a is the adjustment coefficient, and the value range of a is a∈(0,5); n represents the gear value, n∈{1,2,…,10}; represents the ceiling function;

[0035] If △Tc<-△Tb, control the compressor to operate at the lowest gear or stop.

[0036] In one embodiment, if ΔTc<-ΔTb, it is further determined whether the set frequency conversion hysteresis ΔTb is less than the set shutdown hysteresis ΔTt:

[0037] If so, control the compressor to work at the lowest gear;

[0038] If not, control the compressor to stop.

[0039] In one embodiment, in order to eliminate the influence of normal temperature fluctuation on the calculation of the compressor working gear, the following control method is also included:

[0040] Get the average temperature Tc1 within t seconds before switching gears and the average temperature Tc2 within t seconds after switching gears, and determine the relationship between the average temperature Tc1 and the average temperature Tc2:

[0041] If the average temperature Tc1 is less than the average temperature Tc2, the gear position Fn of the compressor is determined by the following formula:

[0042]

[0043] If the average temperature Tc1> the average temperature Tc2, the gear position Fn of the compressor is determined by the following formula:

[0044]

[0045] If the average temperature Tc1 = the average temperature Tc2, the formula for determining the compressor gear position Fn remains unchanged;

[0046] Among them, △T0 is the temperature fluctuation threshold.

[0047] In one embodiment, a control method for restarting the compressor after stopping is also included:

[0048] Get the actual temperature Tc, calculate the actual temperature difference △Tc between the actual temperature Tc and the set temperature Tset, and determine the difference between the actual temperature difference △Tc and the set restart hysteresis △Tq. If the actual temperature difference △Tc is greater than the set restart hysteresis △Tq, control the compressor to restart.

[0049] The set restart hysteresis ΔTq is greater than or equal to the set frequency conversion hysteresis ΔTb.

[0050] In one embodiment, the adjustment coefficient a is 4.5, the frequency conversion hysteresis △Tb is set to 2°C, the shutdown hysteresis △Tt is set to 2°C, and the temperature fluctuation threshold △T0 is set to 0.2°C.

[0051] For better understanding and implementation, the present invention is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 It is a structural schematic diagram of the air conditioning heat pump system of the present invention;

[0053] Figure 2 The schematic diagram of the refrigerant flow of the air-conditioning heat pump system of the present invention in the heating mode;

[0054] Figure 3 The schematic diagram of the refrigerant flow of the air conditioning heat pump system of the present invention in the cooling mode;

[0055] Figure 4 The present invention is a flow chart of an air conditioning heat pump system capable of preventing the compressor from being frequently started and stopped. DETAILED DESCRIPTION

[0056] The scheme of the present invention is described in detail below with reference to the accompanying drawings.

[0057] See also Figure 1 The air conditioning heat pump system 10 includes a compressor 11, a four-way valve 12, a first heat exchanger 13, a throttling assembly 14 and a second heat exchanger 15 which are sequentially connected by a refrigerant circulation pipeline, wherein the first heat exchanger 13 is a heat exchanger for exchanging heat with a user end;

[0058] In some embodiments, when the air conditioning heat pump system is in heating mode, the first heat exchanger 13 can exchange heat with water or air to achieve heating or hot water supply; when the air conditioning heat pump system is in cooling mode, the first heat exchanger 13 can exchange heat with air or water to achieve room cooling or cooling requirements.

[0059] It also includes a temperature sensor 17 for detecting the temperature of the user end, and a controller. The temperature sensor 17, the compressor 11 and the controller (not shown) are electrically connected or communicatively connected. The position of the temperature sensor 17 is not specifically limited in the present invention, and it is only used to collect the temperature of the user end after being heated or cooled under the action of the air conditioning heat pump system to obtain the actual temperature Tc.

[0060] Specifically, the compressor frequency of the existing variable frequency air conditioning heat pump system 10 is divided into 11 gears from F0 to F10, and each gear corresponds to a certain frequency range. The frequency is adjusted to adapt to different operating requirements. Gear F10 represents the highest operating frequency of the compressor at this time, gear F1 represents the lowest operating frequency of the compressor at this time, and gear F0 represents the compressor is stopped at this time. When the system requires a higher heating or cooling capacity, the compressor will increase the frequency to a higher gear; when the system load is low, the compressor will reduce the frequency to a lower gear.

[0061] As shown in Table 1 below, the symbols, specific meanings and value ranges used in this control method are as follows:

[0062]

[0063]

[0064] Specifically, the set restart hysteresis △Tq is usually determined by the system thermal load characteristics, energy efficiency and stability balance, compressor performance, user needs, environmental factors and system design parameters. The thermal load variation range, water tank thermal inertia, compressor frequency adjustment capability and user requirements for temperature control accuracy will affect the value of the frequency conversion hysteresis. A smaller frequency conversion hysteresis can improve energy efficiency and temperature control accuracy, but may lead to frequent adjustments of the compressor; a larger frequency conversion hysteresis can help improve system stability and reduce equipment wear, but may increase temperature fluctuations. In this embodiment, the set restart hysteresis △Tq is preferably 2°C.

[0065] Specifically, the shutdown hysteresis △Tt is set to determine the degree of temperature difference at which the compressor stops running to avoid frequent start and stop, which is determined by the system heat load characteristics, compressor performance, energy efficiency requirements and user requirements for temperature stability. Similarly, a smaller shutdown hysteresis can improve the temperature control accuracy, but may cause the compressor to start and stop frequently, increase energy consumption and equipment wear; a larger shutdown hysteresis helps to reduce the number of starts and stops and improve system stability, but may increase temperature fluctuations. In this embodiment, the set shutdown hysteresis △Tt is preferably 2°C.

[0066] Specifically, the restart hysteresis △Tq is set to determine when the compressor restarts after shutdown to restore the temperature to the set value. Similarly, a smaller restart hysteresis can restore the temperature faster, but may cause the compressor to start and stop frequently, increase energy consumption and equipment wear; a larger restart hysteresis helps to reduce the number of starts and stops and improve system stability, but may prolong the temperature recovery time. In this embodiment, the restart hysteresis △Tq is preferably set to 5°C.

[0067] Specifically, Figure 2 As shown, Figure 2 It indicates the refrigerant flow direction when the air conditioning heat pump system 10 is in the heating mode. When the air conditioning heat pump system 10 is in the cooling mode, since the actual temperature Tc is greater than the set temperature Tset, the actual temperature difference ΔTc is equal to the actual temperature Tc minus the set temperature Tset.

[0068] Specifically, Figure 3 As shown, Figure 3 It indicates the refrigerant flow direction when the air conditioning heat pump system 10 is in cooling mode. When the air conditioning heat pump system 10 is in heating mode, since the actual temperature Tc is less than the set temperature Tset, the actual temperature difference ΔTc is equal to the set temperature Tset minus the actual temperature Tc.

[0069] See also Figure 4 , the controller of the present invention controls the working gear of the compressor in the following manner;

[0070] S10: Obtaining the actual temperature Tc.

[0071] S20: Calculate the actual temperature difference ΔTc between the set temperature Tset and the actual temperature Tc.

[0072] S30: Determine the relationship between the actual temperature difference △Tc and the set frequency conversion hysteresis △Tb:

[0073] If ΔTc>ΔTb, the system is in a high load state, and step S40 is executed;

[0074] If △Tc∈[-△Tb,△Tb], the system is in a medium-low load state, and step S50 is executed;

[0075] If ΔTc<-ΔTb, the system is in an overload state, and step S60 is executed.

[0076] S40: Control the compressor to operate at the highest gear F10.

[0077] S50: Calculate the gear position Fn of the compressor, and control the compressor to work at the gear position Fn, wherein the gear position Fn is determined by the following formula:

[0078]

[0079] Where a is the adjustment coefficient, and the value range of a is a∈(0,5); n represents the gear value, n∈{1,2,…,10}; represents a round-up function; specifically, in this embodiment, the adjustment coefficient a is preferably 4.5.

[0080] S60: Control the compressor to operate at the lowest gear F1 or stop.

[0081] Specifically, S60 includes:

[0082] S61: Determine whether the set frequency conversion hysteresis △Tb is less than the set shutdown hysteresis △Tt:

[0083] If yes, execute step S62;

[0084] If not, execute step S63;

[0085] S62: Control the compressor to work at the lowest gear F1;

[0086] S63: Control the compressor to stop.

[0087] Compared with the prior art, the control method of the present invention achieves smoother gear changes in the compressor working gear, reduces the impact of state switching, keeps the temperature close to the set value, and avoids frequent starting and stopping of the compressor when the temperature difference is close to the set value, thereby achieving energy saving.

[0088] Furthermore, the invention also includes a control method for restarting the compressor after stopping:

[0089] Get the actual temperature Tc, calculate the actual temperature difference △Tc between the actual temperature Tc and the set temperature Tset, and determine the difference between the actual temperature difference △Tc and the set restart hysteresis △Tq. If the actual temperature difference △Tc is greater than the set restart hysteresis △Tq, control the compressor to restart.

[0090] The set restart hysteresis ΔTq is greater than or equal to the set frequency conversion hysteresis ΔTb.

[0091] Furthermore, in order to eliminate the influence of normal temperature fluctuation on the calculation of the compressor working gear, the following control method is also included:

[0092] Get the average temperature Tc1 within t seconds before switching gears and the average temperature Tc2 within t seconds after switching gears, and determine the relationship between the average temperature Tc1 and the average temperature Tc2:

[0093] If the average temperature Tc1 is less than the average temperature Tc2, the gear position Fn of the compressor is determined by the following formula:

[0094]

[0095] If the average temperature Tc1> the average temperature Tc2, the gear position Fn of the compressor is determined by the following formula:

[0096]

[0097] If the average temperature Tc1 = the average temperature Tc2, the formula for determining the compressor gear position Fn remains unchanged.

[0098] Specifically, ΔT0 is a temperature fluctuation threshold value, which is determined by the user according to the use environment conditions and actual needs of the device. In this embodiment, it is preferably 0.2.

[0099] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the embodiments of the present application. The singular forms of "a", "said" and "the" used in the embodiments of the present application and the claims are also intended to include plural forms, unless the context clearly indicates other meanings. It should also be understood that, unless otherwise specified, "multiple" refers to two or more; the terms "first", "second", "third", etc. are only used to distinguish, rather than to describe a specific order or sequence, and cannot be understood as indicating or implying relative importance. The term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items. When the above description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. In the description of the present application, for those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0100] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. An air conditioning heat pump system with a function of preventing the compressor from starting and stopping frequently, comprising a compressor, a four-way valve, a first heat exchanger, a throttling assembly and a second heat exchanger connected in sequence by a refrigerant circulation pipeline, wherein the first heat exchanger exchanges heat with a user end; further comprising a temperature sensor for detecting the temperature of the user end, and a controller, wherein the temperature sensor, the compressor and the controller are connected electrically or by communication; characterized in that: The controller controls the working gear of the compressor in the following manner: Get the actual temperature Tc, calculate the actual temperature difference △Tc between the actual temperature Tc and the set temperature Tset, and determine the size relationship between the actual temperature difference △Tc and the set frequency conversion hysteresis △Tb: If △Tc>△Tb, the compressor is controlled to operate at the highest gear; If △Tc∈[-△Tb,△Tb], the gear position Fn of the compressor is determined by the following formula: Where a is the adjustment coefficient, and the value range of a is a∈(0,5); n represents the gear value, n∈{1,2,…,10}; represents the ceiling function; If △Tc<-△Tb, control the compressor to operate at the lowest gear or stop.

2. The air conditioning heat pump system with the function of preventing the compressor from starting and stopping frequently according to claim 1, characterized in that: If △Tc<-△Tb, then further determine whether the set frequency conversion hysteresis △Tb is less than the set shutdown hysteresis △Tt: If so, control the compressor to work at the lowest gear; If not, control the compressor to stop.

3. The air conditioning heat pump system with the function of preventing the compressor from frequently starting and stopping according to claim 2, characterized in that: In order to eliminate the influence of normal temperature fluctuations on the calculation of the compressor working gear, the following control methods are also included: Get the average temperature Tc1 within t seconds before switching gears and the average temperature Tc2 within t seconds after switching gears, and determine the relationship between the average temperature Tc1 and the average temperature Tc2: If the average temperature Tc1 is less than the average temperature Tc2, the gear position Fn of the compressor is determined by the following formula: If the average temperature Tc1> the average temperature Tc2, the gear position Fn of the compressor is determined by the following formula: If the average temperature Tc1 = the average temperature Tc2, the formula for determining the compressor gear position Fn remains unchanged; Among them, △T0 is the temperature fluctuation threshold.

4. The air conditioning heat pump system with the function of preventing the compressor from frequently starting and stopping according to claim 3, characterized in that: It also includes the control method for restarting the compressor after shutdown: Get the actual temperature Tc, calculate the actual temperature difference △Tc between the actual temperature Tc and the set temperature Tset, and determine the difference between the actual temperature difference △Tc and the set restart hysteresis △Tq. If the actual temperature difference △Tc is greater than the set restart hysteresis △Tq, control the compressor to restart. The set restart hysteresis ΔTq is greater than or equal to the set frequency conversion hysteresis ΔTb.

5. The air conditioning heat pump system with the function of preventing the compressor from frequently starting and stopping according to claim 4, characterized in that: The adjustment coefficient a is 4.5, the frequency conversion hysteresis △Tb is set to 2℃, the shutdown hysteresis △Tt is set to 2℃, and the temperature fluctuation threshold △T0 is set to 0.2℃.

6. A compressor frequency control method for preventing frequent start and stop, characterized in that: Get the actual temperature Tc, calculate the actual temperature difference △Tc between the actual temperature Tc and the set temperature Tset, and determine the size relationship between the actual temperature difference △Tc and the set frequency conversion hysteresis △Tb: If △Tc>△Tb, the compressor is controlled to operate at the highest gear; If △Tc∈[-△Tb,△Tb], the gear position Fn of the compressor is determined by the following formula: Where a is the adjustment coefficient, and the value range of a is a∈(0,5); n represents the gear value, n∈{1,2,…,10}; represents the ceiling function; If △Tc<-△Tb, control the compressor to operate at the lowest gear or stop.

7. The compressor frequency control method for preventing frequent starts and stops according to claim 6, characterized in that: If △Tc<-△Tb, then further determine whether the set frequency conversion hysteresis △Tb is less than the set shutdown hysteresis △Tt: If so, control the compressor to work at the lowest gear; If not, control the compressor to stop.

8. The compressor frequency control method for preventing frequent starts and stops according to claim 7, characterized in that: In order to eliminate the influence of normal temperature fluctuations on the calculation of the compressor working gear, the following control methods are also included: Get the average temperature Tc1 within t seconds before switching gears and the average temperature Tc2 within t seconds after switching gears, and determine the relationship between the average temperature Tc1 and the average temperature Tc2: If the average temperature Tc1 is less than the average temperature Tc2, the gear position Fn of the compressor is determined by the following formula: If the average temperature Tc1> the average temperature Tc2, the gear position Fn of the compressor is determined by the following formula: If the average temperature Tc1 = the average temperature Tc2, the formula for determining the compressor gear position Fn remains unchanged; Among them, △T0 is the temperature fluctuation threshold.

9. The compressor frequency control method for preventing frequent starts and stops according to claim 8, characterized in that: It also includes the control method for restarting the compressor after shutdown: Get the actual temperature Tc, calculate the actual temperature difference △Tc between the actual temperature Tc and the set temperature Tset, and determine the difference between the actual temperature difference △Tc and the set restart hysteresis △Tq. If the actual temperature difference △Tc is greater than the set restart hysteresis △Tq, control the compressor to restart. The set restart hysteresis ΔTq is greater than or equal to the set frequency conversion hysteresis ΔTb.

10. The compressor frequency control method for preventing frequent starts and stops according to claim 9, characterized in that: The adjustment coefficient a is 4.5, the frequency conversion hysteresis △Tb is set to 2℃, the shutdown hysteresis △Tt is set to 2℃, and the temperature fluctuation threshold △T0 is set to 0.2℃.

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