Compressor frequency control method and air conditioner heat pump system with same

Abstract

The invention relates to a compressor frequency control method which comprises the following steps: S10, acquiring the shutdown times of a compressor from power-on to the current moment, and determining the initial working frequency F0 of the compressor according to the shutdown times of the compressor; s20, the actual operation time t of the compressor in the current operation cycle is obtained; s30, the working mode and the water outlet temperature Tout of the system at the current moment are obtained, and the temperature difference T between the water outlet temperature Tout and the set water outlet temperature Tset is calculated according to the working mode of the system; s40, the target working frequency F of the compressor is calculated according to the initial working frequency F0, the actual operation time t and the temperature difference T of the compressor; and S50, the compressor is controlled to work at the target working frequency F. The target working frequency F of the compressor is dynamically adjusted through the temperature difference T and the actual operation time t of the compressor, the start-stop frequency of the compressor can be remarkably reduced, the mechanical life of the compressor is prolonged, meanwhile, the fluctuation range of the outlet water temperature is narrowed, and the user comfort is improved.

Description

Technical Field

[0001] This invention relates to the field of heat pump system technology, and in particular to a method for controlling compressor frequency and an air conditioning heat pump system having the control. Background Technology

[0002] Air conditioning heat pump systems use variable frequency heat pump units to transfer low-grade outdoor heat energy to indoor spaces or water tanks. They are suitable for buildings such as residences, apartments, hotels, and hospitals, providing a stable heat or cold source for users such as fan coil units, indoor spaces, or domestic water users.

[0003] In the actual operation of air conditioning heat pump systems, once the user-end temperature approaches the set value, the system often experiences a so-called "temperature-reaching shutdown." This means that when the compressor heats at its highest frequency, the inertial temperature rise causes the water temperature to momentarily exceed the target, at which point the compressor immediately stops. After the heat dissipates and the user-end temperature drops, the compressor restarts. This high-frequency start-stop not only consumes a lot of energy and generates a lot of noise, accelerating the wear and tear of core components, but also causes large fluctuations in the user-end temperature, affecting user comfort. Summary of the Invention

[0004] Therefore, the purpose of this invention is to overcome the defects or deficiencies of the prior art and provide an air conditioning heat pump system with compressor frequency control.

[0005] An air conditioning heat pump system with compressor frequency control includes a compressor, a reversing four-way valve, a water-side heat exchanger, a throttling component, and an air-side heat exchanger connected in sequence by a refrigerant circulation pipeline; it also includes a first temperature sensor for obtaining the outlet water temperature Tout; and a controller, which is communicatively connected to the first temperature sensor and the compressor; the controller includes a compressor initial operating frequency acquisition unit, a compressor running time acquisition unit, a temperature difference calculation unit, a compressor target operating frequency calculation unit, and a compressor operating frequency control unit;

[0006] The compressor initial operating frequency acquisition unit is used to acquire the number of times the compressor has stopped since power-on to the current time, and to determine the compressor initial operating frequency F0 based on the number of times the compressor has stopped.

[0007] The compressor running time acquisition unit is used to acquire the actual running time t of the compressor in the current running cycle;

[0008] The temperature difference calculation unit is used to obtain the current system operating mode and outlet water temperature Tout, and calculate the temperature difference ΔT between the outlet water temperature Tout and the set outlet water temperature Tset according to the system operating mode.

[0009] The compressor target operating frequency calculation unit is used to calculate the compressor target operating frequency F based on the compressor initial operating frequency F0, actual running time t, and temperature difference ΔT.

[0010] The compressor operating frequency control unit is used to control the compressor to operate at the target operating frequency F.

[0011] In one embodiment, determining the initial operating frequency F0 of the compressor based on the number of compressor shutdowns includes:

[0012] Determine if the number of downtimes is greater than or equal to 1:

[0013] If satisfied, the maximum operating frequency reached by the compressor in the previous operating cycle is obtained, and the initial operating frequency F0 of the compressor is taken as the maximum operating frequency;

[0014] If the conditions are not met, the current ambient temperature Ta is obtained, and the initial operating frequency F0 of the compressor is determined, wherein the ambient temperature Ta is collected by the second temperature sensor.

[0015] In one embodiment, the temperature difference ΔT between the outlet water temperature Tout and the set outlet water temperature Tset is calculated based on the system's operating mode, including:

[0016] If the system is in heating mode, then ΔT = Tset - Tout;

[0017] If the system is in cooling mode, then ΔT = Tout - Tset.

[0018] In one embodiment, the target operating frequency F of the compressor is calculated based on the compressor's initial operating frequency F0, the compressor's actual operating time t, and the temperature difference ΔT, including calculation using the following formula:

[0019]

[0020] Among them, t set For the set target runtime, ΔT set K1 is the set shutdown hysteresis, K2 is the time coefficient, and K2 is the temperature difference coefficient.

[0021] In one embodiment, the time coefficient K1 ranges from K1∈(0,0.5], the temperature difference coefficient K2 ranges from K2∈(0,0.3), and the set shutdown hysteresis ΔT set The range of values ​​for is ΔT set ∈[2,3].

[0022] In one embodiment, it further includes a comparison between the actual compressor running time t and the set target running time t. setThe time coefficient K1 is determined by the size relationship between them.

[0023] Determine whether the actual running time t of the compressor is less than 1.2 times the set target running time t. set :

[0024] If this condition is met, then the time coefficient K1 takes the value of 0.3;

[0025] If this condition is not met, the time coefficient K1 is set to 0.5.

[0026] In one embodiment, it further includes a method based on the temperature difference ΔT and a set shutdown hysteresis ΔT. set The relationship between their magnitudes determines the temperature difference coefficient K2:

[0027] Determine if the temperature difference ΔT is less than twice the set shutdown hysteresis ΔT set :

[0028] If this condition is met, then the temperature difference coefficient K2 is set to 0.1.

[0029] If this condition is not met, the temperature difference coefficient K2 is set to 0.2.

[0030] Furthermore, the present invention also provides a method for controlling the frequency of a compressor, comprising the following steps:

[0031] S10: Obtain the number of compressor shutdowns since power-on, and determine if the number of shutdowns is greater than or equal to 1.

[0032] If satisfied, the maximum operating frequency reached by the compressor in the previous operating cycle is obtained, and the initial operating frequency F0 of the compressor is taken as the maximum operating frequency;

[0033] If the conditions are not met, the current ambient temperature Ta is obtained, and the initial operating frequency F0 of the compressor is determined.

[0034] S20: Obtain the actual running time t of the compressor in the current operating cycle.

[0035] S30: Obtain the current system operating mode and outlet water temperature Tout, and calculate the temperature difference ΔT between the outlet water temperature Tout and the set outlet water temperature Tset based on the system operating mode.

[0036] If the system is in heating mode, then ΔT = Tset - Tout;

[0037] If the system is in cooling mode, then ΔT = Tout - Tset.

[0038] S40: The target operating frequency F of the compressor is calculated using the following formula based on the compressor's initial operating frequency F0, actual operating time t, and temperature difference ΔT:

[0039]

[0040] Among them, t set For the set target runtime, ΔT set The set shutdown hysteresis is defined by K1 as a time coefficient and K2 as a temperature difference coefficient. The time coefficient K1 ranges from 0 to 0.5, and the temperature difference coefficient K2 ranges from 0 to 0.3. The set shutdown hysteresis is defined as ΔT. set The range of values ​​for is ΔT set ∈[2,3].

[0041] S50: Controls the compressor to operate at the target operating frequency F.

[0042] In one embodiment, step S40 further includes comparing the actual compressor running time t with the set target running time t. set The time coefficient K1 is determined by the size relationship between them.

[0043] Determine whether the actual running time t of the compressor is less than 1.2 times the set target running time t. set :

[0044] If this condition is met, then the time coefficient K1 takes the value of 0.3;

[0045] If this condition is not met, the time coefficient K1 is set to 0.5.

[0046] In one embodiment, step S40 further includes using the temperature difference ΔT and a set shutdown hysteresis ΔT as a reference. set The relationship between their magnitudes determines the temperature difference coefficient K2:

[0047] Determine if the temperature difference ΔT is less than twice the set shutdown hysteresis ΔT set :

[0048] If this condition is met, then the temperature difference coefficient K2 is set to 0.1.

[0049] If this condition is not met, the temperature difference coefficient K2 is set to 0.2.

[0050] To better understand and implement this invention, the following detailed description is provided in conjunction with the accompanying drawings. Attached Figure Description

[0051] Figure 1 This is a schematic diagram of the air conditioning heat pump system of the present invention;

[0052] Figure 2 This is a schematic diagram of the components in the controller of the present invention;

[0053] Figure 3This is a flowchart illustrating the control method of the present invention.

[0054] Reference numerals: compressor 11, reversing four-way valve 12, water-side heat exchanger 13, throttling assembly 14, air-side heat exchanger 15, first temperature sensor 21, second temperature sensor 22, compressor initial operating frequency acquisition unit 31, compressor running time acquisition unit 32, temperature difference calculation unit 33, compressor target operating frequency calculation unit 34, compressor operating frequency control unit 35. Detailed Implementation

[0055] The present invention will now be described in detail with reference to the accompanying drawings.

[0056] like Figure 1 As shown, an air conditioning heat pump system 10 with compressor frequency control according to the present invention includes a compressor 11, a reversing four-way valve 12, a water-side heat exchanger 13, a throttling assembly 14 and an air-side heat exchanger 15 connected in sequence by a refrigerant circulation pipeline.

[0057] Specifically, the compressor 11 can be either a fixed-frequency compressor or a variable-frequency compressor; the water-side heat exchanger 13 is a heat exchanger that exchanges heat with water. After the refrigerant flows out of the compressor 11, it passes through the reversing four-way valve and then flows through the condenser 12 to exchange heat with the external water; the throttling component 14 is an electronic expansion valve; the air-side heat exchanger 15 can be either a water-source heat exchanger or an air-source heat exchanger. In this application, the air-side heat exchanger 15 is a heat exchanger that exchanges heat with air. After the refrigerant flows out of the throttling component 13, it flows through the air-side heat exchanger 15 to exchange heat with the external air.

[0058] In heating mode, the refrigerant passes through the compressor 11, the reversing four-way valve 12, the water-side heat exchanger 13, the throttling component 14 and the air-side heat exchanger 15 in sequence. At this time, the water-side heat exchanger 13 acts as a condenser to release heat and raise the temperature of the external water.

[0059] In cooling mode, the refrigerant passes sequentially through the compressor 11, the reversing four-way valve 12, the air-side heat exchanger 15, the throttling component 14, and the water-side heat exchanger 13. At this time, the water-side heat exchanger 13 acts as an evaporator to absorb heat and cause the external water temperature to drop.

[0060] The heat pump system further includes a first temperature sensor 21 for detecting the system outlet water temperature Tout, and a second temperature sensor 22 for detecting the ambient temperature Ta.

[0061] Specifically, the first temperature sensor 21 is installed on the outlet water pipe of the condenser 12 to obtain the outlet water temperature Tout; the location of the second temperature sensor 22 is not specifically limited in this invention, and is only used to collect the ambient temperature Ta of the water-side heat exchanger 13.

[0062] Specifically, it also includes a controller, which is communicatively connected to the first temperature sensor 21 and the compressor 11.

[0063] like Figure 2 and Figure 3 As shown, the controller includes: a compressor initial operating frequency acquisition unit 31, a compressor running time acquisition unit 32, a temperature difference calculation unit 33, a compressor target operating frequency calculation unit 34, and a compressor operating frequency control unit 35.

[0064] The compressor initial operating frequency acquisition unit 31 is used to perform step S10: acquire the number of times the compressor has stopped since power-on, and determine the acquisition method of the compressor initial operating frequency F0 based on the number of times the compressor has stopped.

[0065] Specifically, the method for determining the initial operating frequency F0 of the compressor based on the number of compressor shutdowns includes:

[0066] Get the current number of compressor shutdowns and determine if the number of shutdowns is greater than or equal to 1:

[0067] If satisfied, the maximum operating frequency reached by the compressor in the previous operating cycle is obtained, and the initial operating frequency F0 of the compressor is taken as the maximum operating frequency;

[0068] If the conditions are not met, the ambient temperature Ta of the system at the current moment is obtained, and the initial operating frequency F0 of the compressor is determined based on the ambient temperature Ta.

[0069] The compressor running time acquisition unit 32 is used to perform step S20: acquire the actual running time t of the compressor in the current running cycle.

[0070] The temperature difference calculation unit 33 is used to perform step S30: obtain the current system working mode and outlet water temperature Tout, and calculate the temperature difference ΔT between the outlet water temperature Tout and the set outlet water temperature Tset according to the system working mode.

[0071] Specifically, the temperature difference ΔT between the outlet water temperature Tout and the set outlet water temperature Tset is calculated based on the system's operating mode, including:

[0072] If the system is in heating mode, then ΔT = Tset - Tout;

[0073] If the system is in cooling mode, then ΔT = Tout - Tset.

[0074] The compressor target operating frequency calculation unit 34 is used to perform step S40: calculate the compressor target operating frequency F based on the compressor initial operating frequency F0, actual running time t, and temperature difference ΔT.

[0075] Specifically, the target operating frequency F of the compressor is calculated using the following formula:

[0076]

[0077] Among them, t set For the set target runtime, ΔT set K1 is the set shutdown hysteresis, K2 is the time coefficient, and K2 is the temperature difference coefficient.

[0078] Specifically, the set target duration t set Determined based on the system's operating mode and the ambient temperature range:

[0079] When the system is in heating mode, if Ta ≤ -15℃, then t set The value is taken as 150 min. If -15℃ < Ta ≤ -5℃, then t set The value is taken as 120 min; if -5℃ < Ta ≤ 8℃, then t set The value is 90 min; if 8℃ < Ta, then t set The value is 120 min;

[0080] When the system is in cooling mode, if Ta ≤ 20℃, then t set The value is taken as 90 min. If 20℃ < Ta ≤ 38℃, then t set The value is taken as 120 min. If 38℃ < Ta, then t set The value is 150min.

[0081] Specifically, the time coefficient K1 ranges from K1∈(0,0.5], the temperature difference coefficient K2 ranges from K2∈(0,0.3), and the set shutdown hysteresis ΔT set The range of values ​​for is ΔT set ∈[2,3].

[0082] Furthermore, it also includes the actual compressor running time t and the set target running time t. set The time coefficient K1 is determined by the size relationship between them.

[0083] Determine whether the actual running time t of the compressor is less than 1.2 times the set target running time t. set :

[0084] If this condition is met, then the time coefficient K1 takes the value of 0.3;

[0085] If this condition is not met, the time coefficient K1 is set to 0.5.

[0086] Furthermore, it also includes the relationship between the temperature difference ΔT and the set shutdown hysteresis ΔT. set The relationship between their magnitudes determines the temperature difference coefficient K2:

[0087] Determine if the temperature difference ΔT is less than twice the set shutdown hysteresis ΔT set :

[0088] If this condition is met, then the temperature difference coefficient K2 is set to 0.1.

[0089] If this condition is not met, the temperature difference coefficient K2 is set to 0.2.

[0090] Furthermore, it also includes upper and lower limit control of the compressor's target operating frequency F. The target operating frequency F ranges from F ∈ [min, max] Hz, where min is the minimum threshold and max is the maximum threshold. If the calculated target operating frequency F is lower than its minimum threshold min, then the target operating frequency F is set to the minimum threshold min; if the calculated target operating frequency F is higher than its maximum threshold max, then the target operating frequency F is set to the maximum threshold max. In this application, to prevent the compressor from operating at low frequencies for a long time, which could lead to poor lubrication or difficulty in oil return, the minimum threshold min is 40 Hz; the maximum threshold max usually needs to be determined based on the system design, and its specific value is 90 Hz.

[0091] The compressor operating frequency control unit 35 is used to execute step S50: control the compressor to operate at the target operating frequency F.

[0092] Compared to existing technologies, the present invention provides an air conditioning heat pump system with compressor frequency control, which uses the temperature difference ΔT and the set shutdown hysteresis ΔT... set By dynamically adjusting the ratio between the two values ​​to the target operating frequency F of the compressor, temperature overshoot caused by excessive heat absorption or release from the air conditioning heat pump system can be suppressed, thereby reducing the number of compressor start-stop cycles. Furthermore, since the actual operating time of the system is very short, this invention sets a target operating time t. set This can effectively extend the actual running time t to the target running time t. set This directly reduces the number of times the compressor starts and stops.

[0093] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of this application. The singular forms “a,” “the,” and “the” used in the embodiments and claims of this application are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that, unless otherwise stated, “a plurality” means two or more; the terms “first,” “second,” “third,” etc., are used only to distinguish and not to describe a particular order or sequence, nor should they be construed as indicating or implying relative importance. The term “and / or” as used herein refers to and includes any or all possible combinations of one or more associated listed items. When the above description relates to drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. In the description of this application, those skilled in the art will understand the specific meaning of the above terms in this application according to the specific circumstances.

[0094] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. An air conditioning heat pump system with compressor frequency control, comprising a compressor, a reversing four-way valve, a water-side heat exchanger, a throttling assembly, and an air-side heat exchanger connected sequentially by a refrigerant circulation pipeline; further comprising a first temperature sensor for obtaining the outlet water temperature Tout; and further comprising a controller, the controller being communicatively connected to the first temperature sensor and the compressor; characterized in that: The controller includes a compressor initial operating frequency acquisition unit, a compressor running time acquisition unit, a temperature difference calculation unit, a compressor target operating frequency calculation unit, and a compressor operating frequency control unit; The compressor initial operating frequency acquisition unit is used to acquire the number of times the compressor has stopped since power-on to the current time, and to determine the compressor initial operating frequency F0 based on the number of times the compressor has stopped. The compressor running time acquisition unit is used to acquire the actual running time t of the compressor in the current running cycle; The temperature difference calculation unit is used to obtain the current system operating mode and outlet water temperature Tout, and calculate the temperature difference ΔT between the outlet water temperature Tout and the set outlet water temperature Tset according to the system operating mode. The compressor target operating frequency calculation unit is used to calculate the compressor target operating frequency F based on the compressor initial operating frequency F0, actual running time t, and temperature difference ΔT. The compressor operating frequency control unit is used to control the compressor to operate at the target operating frequency F.

2. The air conditioning heat pump system according to claim 1, characterized in that, The initial operating frequency F0 of the compressor is determined based on the number of times the compressor stops, including: Determine if the number of downtimes is greater than or equal to 1: If satisfied, the maximum operating frequency reached by the compressor in the previous operating cycle is obtained, and the initial operating frequency F0 of the compressor is taken as the maximum operating frequency; If the conditions are not met, the current ambient temperature Ta is obtained, and the initial operating frequency F0 of the compressor is determined, wherein the ambient temperature Ta is collected by the second temperature sensor.

3. The air conditioning heat pump system according to claim 1, characterized in that, The temperature difference ΔT between the outlet water temperature Tout and the set outlet water temperature Tset is calculated based on the system's operating mode, including: If the system is in heating mode, then ΔT = Tset - Tout; If the system is in cooling mode, then ΔT = Tout - Tset.

4. The air conditioning heat pump system according to claim 1, characterized in that, The target operating frequency F of the compressor is calculated based on the compressor's initial operating frequency F0, the compressor's actual operating time t, and the temperature difference ΔT, including the following formula: Among them, t set For the set target runtime, ΔT set K1 is the set shutdown hysteresis, K2 is the time coefficient, and K2 is the temperature difference coefficient.

5. The air conditioning heat pump system according to claim 4, characterized in that: The time coefficient K1 ranges from K1∈(0,0.5], the temperature difference coefficient K2 ranges from K2∈(0,0.3), and the set shutdown hysteresis ΔT set The range of values ​​for is ΔT set ∈[2,3].

6. The air conditioning heat pump system according to claim 4, characterized in that: It also includes the compressor's actual running time t and the set target running time t. set The time coefficient K1 is determined by the size relationship between them. Determine whether the actual running time t of the compressor is less than 1.2 times the set target running time t. set : If this condition is met, then the time coefficient K1 takes the value of 0.3; If this condition is not met, the time coefficient K1 is set to 0.

5.

7. The air conditioning heat pump system according to claim 4, characterized in that: It also includes the temperature difference ΔT and the set shutdown hysteresis ΔT. set The relationship between their magnitudes determines the temperature difference coefficient K2: Determine if the temperature difference ΔT is less than twice the set shutdown hysteresis ΔT set : If this condition is met, then the temperature difference coefficient K2 is set to 0.

1. If this condition is not met, the temperature difference coefficient K2 is set to 0.

2.

8. A method for controlling the frequency of a compressor, characterized in that, Includes the following steps: S10: Obtain the number of compressor shutdowns since power-on, and determine if the number of shutdowns is greater than or equal to 1. If satisfied, the maximum operating frequency reached by the compressor in the previous operating cycle is obtained, and the initial operating frequency F0 of the compressor is taken as the maximum operating frequency; If not satisfied, the current ambient temperature Ta is obtained, and the initial operating frequency F0 of the compressor is determined. S20: Obtain the actual running time t of the compressor in the current operating cycle; S30: Obtain the current system operating mode and outlet water temperature Tout, and calculate the temperature difference ΔT between the outlet water temperature Tout and the set outlet water temperature Tset based on the system operating mode. If the system is in heating mode, then ΔT = Tset - Tout; If the system is in cooling mode, then ΔT = Tout - Tset; S40: The target operating frequency F of the compressor is calculated using the following formula based on the compressor's initial operating frequency F0, actual operating time t, and temperature difference ΔT: Among them, t set For the set target runtime, ΔT set The set shutdown hysteresis is defined by K1 as a time coefficient and K2 as a temperature difference coefficient. The time coefficient K1 ranges from 0 to 0.5, and the temperature difference coefficient K2 ranges from 0 to 0.

3. The set shutdown hysteresis is defined as ΔT. set The range of values ​​for is ΔT set ∈[2,3]; S50: Controls the compressor to operate at the target operating frequency F.

9. The control method according to claim 8, characterized in that: Step S40 also includes comparing the actual compressor running time t with the set target running time t set The time coefficient K1 is determined by the size relationship between them. Determine whether the actual running time t of the compressor is less than 1.2 times the set target running time t. set : If this condition is met, then the time coefficient K1 takes the value of 0.3; If this condition is not met, the time coefficient K1 is set to 0.

5.

10. The control method according to claim 9, characterized in that: Step S40 also includes the temperature difference ΔT and the set shutdown hysteresis ΔT. set The relationship between their magnitudes determines the temperature difference coefficient K2: Determine if the temperature difference ΔT is less than twice the set shutdown hysteresis ΔT set : If this condition is met, then the temperature difference coefficient K2 is set to 0.

1. If this condition is not met, the temperature difference coefficient K2 is set to 0.2.

Images