Method for controlling motor cooling of a compressor of a refrigeration unit and refrigeration unit

Abstract

The application provides a control method for motor cooling of a compressor of a refrigerating unit. The refrigerating unit comprises a compressor, a condenser and an evaporator, or comprises a compressor, a condenser, an economizer and an evaporator. The control method for motor cooling of the compressor of the refrigerating unit comprises the following steps: obtaining an operating state parameter of a component of the refrigerating unit; obtaining a target value of superheat of a return gas position of the motor cooling based on the obtained operating state parameter; and controlling the refrigerating unit to cool the motor based on the obtained target value of superheat. According to the application, the target value of superheat in the control is corrected according to the change of the operating state parameter of the unit, so that the amount of liquid refrigerant in the motor cavity is optimal and the motor temperature meets the requirements in the whole operating range of the unit.

Description

Technical Field

[0001] This application relates to a control method for motor cooling, and more particularly to a control method for motor cooling of a compressor in a refrigeration unit. Background Technology

[0002] A refrigeration unit includes a compressor, condenser, flow control valve, and evaporator. When the refrigeration unit is operating, the compressor draws in low-pressure gaseous refrigerant from the evaporator, increases its pressure, and sends it to the condenser. In the condenser, the higher-pressure gaseous refrigerant exchanges heat with the cooling fluid, condensing into a higher-pressure liquid refrigerant, which is then sent to the expansion valve. The higher-pressure liquid refrigerant, after being throttled by the expansion valve, becomes a lower-pressure two-phase refrigerant, which is then sent to the evaporator. In the evaporator, the lower-pressure two-phase refrigerant exchanges heat with the chilled fluid, absorbing heat and evaporating into a lower-pressure gaseous refrigerant, which is then sent back to the compressor inlet, thus completing the refrigeration cycle. Two-stage or multi-stage refrigeration units also include an economizer. Summary of the Invention

[0003] During motor operation, heat is generated because the motor's efficiency is less than 100%. To prevent the motor from overheating, cooling is usually required to remove this heat. When cooling the compressor motor, subcooled or saturated refrigerant (e.g., cold water) is typically obtained from the condenser or economizer in the refrigeration unit to cool the motor. Refrigeration units include water-cooled, air-cooled, single-cooling, and heat pump units, etc. Compressors include centrifugal, screw, and scroll compressors, etc.

[0004] In existing technologies, one approach involves using a semi-hermetic compressor in a refrigeration unit that employs refrigerant to cool the motor and utilizes various control methods for motor cooling. One implementation method for controlling motor cooling involves using an electronic expansion valve to control the refrigerant supply to the motor and employing PI control based on a fixed superheat target value for the refrigerant in the motor cavity at the return gas position, thereby controlling the opening of the electronic expansion valve. In this implementation, under normal operating conditions, the amount of liquid refrigerant in the motor cavity is optimal, while ensuring that the motor temperature meets requirements. However, when the unit's operating pressure ratio and load change, using a fixed superheat target value can lead to an excess or deficiency of liquid refrigerant in the motor cavity, resulting in increased agitation losses, decreased unit operating efficiency, or excessively high motor winding temperatures. This implementation method is relatively simple to control, but it sacrifices unit operating efficiency and stability.

[0005] To address the aforementioned issues, this application modifies the target value of superheat in the control based on changes in the unit's operating status parameters, thereby ensuring that the amount of liquid refrigerant in the motor cavity is optimal throughout the entire operating range of the unit, while simultaneously meeting the motor temperature requirements.

[0006] According to a first aspect of this application, this application provides a control method for cooling the motor of a compressor in a refrigeration unit. The refrigeration unit includes a compressor, a condenser, and an evaporator, or includes a compressor, a condenser, an economizer, and an evaporator. The control method for cooling the motor of the compressor in the refrigeration unit includes the following steps: acquiring operating state parameters of the components of the refrigeration unit; acquiring a target value of superheat at the return gas location for motor cooling based on the acquired operating state parameters; and controlling the cooling of the motor by the refrigeration unit based on the acquired target value of superheat.

[0007] According to the first aspect of this application, when the condenser is used as a cooling source for the motor, the return gas location is either at the economizer or the evaporator. When the economizer is used as a cooling source for the motor, the return gas location is at the evaporator.

[0008] According to the first aspect of this application, obtaining a target value of superheat at the return gas location of the motor cooling system based on the acquired operating state parameters includes the following steps: obtaining a superheat reference value SH. r The superheat bias step width C is used; the superheat correction coefficient K is obtained based on the acquired operating state parameters; the superheat correction value SH is obtained by multiplying the superheat bias step width C and the superheat correction coefficient K. c ; and at the superheat reference value SH r The superheat correction value SH is superimposed on it. c To obtain the target value SH of superheat at the return gas location. target .

[0009] According to the first aspect of this application, the superheat correction factor K is the sum of the cooling flow correction factor X and the motor heating correction factor Y. This is based on the pressure P of the motor's cooling source. cool and the pressure P at the return gas position ret To obtain the cooling flow correction factor X. Based on the motor's input power P. motor P motor 'and the rated power P of the motor rated P rated To obtain the motor heating correction coefficient Y.

[0010] According to the first aspect of this application, based on the pressure P of the cooling source of the motor... cool and the pressure P at the return gas position ret The cooling flow correction factor X is obtained based on the following formula: X = (P cool –P ret ) / A-1, where A is a constant. Based on the input power P of the motor. motor P motor 'and the rated power P of the motor rated P ratedThe motor heating correction factor Y is obtained based on the following formula: Y = 1 - P motor / (B*P rated ), or Y = 1 - P motor ' / (B*P rated '), where B is a constant.

[0011] According to the first aspect of this application, the overheat correction factor K is the motor heating and cooling correction factor Z. This is based on the temperature T of the motor windings. winding T winding 'and the temperature threshold T of the motor windings thre T thre To obtain the motor heating and cooling correction coefficient Z.

[0012] According to the first aspect of this application, based on the temperature T of the motor windings... winding T winding 'and the temperature threshold T of the motor windings thre T thre The motor heating and cooling correction factor Z is obtained based on the following formula: Z = 1 / (D*(T)) winding –T thre )), or Z = 1 / (D*(T) winding '–T thre ')), where D is a constant.

[0013] According to the first aspect of this application, the superheat offset step width is different under different operating conditions of the refrigeration unit.

[0014] According to the first aspect of this application, the target value of the superheat at the return gas location of the motor cooling is greater than the minimum superheat threshold.

[0015] According to a second aspect of this application, a refrigeration unit is provided. The refrigeration unit includes a compressor, a condenser, and an evaporator, or includes a compressor, a condenser, an economizer, and an evaporator. The refrigeration unit also includes several detection devices and a control device. The detection devices are configured to detect operating status parameters of the components of the refrigeration unit. The control device includes a processor. The control device is configured to execute the aforementioned control method for cooling the motor of the compressor in the refrigeration unit. Attached Figure Description

[0016] The accompanying drawings are not to scale. In the drawings, each identical or nearly identical component shown in different figures is indicated by the same reference numerals. For clarity, not every component may be labeled in every drawing. In the drawings:

[0017] Figure 1AA block diagram of a refrigeration unit according to an embodiment of this application is shown;

[0018] Figure 1B A block diagram of a refrigeration unit according to another embodiment of this application is shown;

[0019] Figure 2 A flowchart illustrating the control method for cooling the compressor motor in a refrigeration unit is shown.

[0020] Figure 3 It shows Figure 2 The detailed flowchart of step 206 in the flowchart shown in the figure;

[0021] Figure 4A It shows Figure 3 The flowchart shown in the figure is a flowchart of the first embodiment of step 306;

[0022] Figure 4B It shows Figure 3 The flowchart shown in the figure is a flowchart of the first embodiment of step 306;

[0023] Figure 5A A graph showing the temperature of the motor windings over time is shown as an embodiment of the motor cooling control method of this application.

[0024] Figure 5B It shows the relationship with Figure 5A The curve of the motor winding corresponds to the curve of the motor cavity overheat setting value changing over time;

[0025] Figure 5C It shows the relationship with Figure 5A The curve of the motor winding corresponds to the curve of the motor cooling EEV opening changing over time.

[0026] Figure 5D It shows the relationship with Figure 5A The curve of the motor winding corresponds to the curve of the motor current changing over time.

[0027] Figure 6A It shows Figure 1A A block diagram of the control unit in the refrigeration unit is shown; and

[0028] Figure 6B It shows Figure 1B The diagram shows a block diagram of the control unit in the refrigeration unit. Detailed Implementation

[0029] Specific embodiments of this application will now be described with reference to the accompanying drawings. It should be understood that, where possible, the same or similar reference numerals used in this application refer to the same parts.

[0030] Figure 1A A block diagram of a refrigeration unit 100 according to one embodiment of this application is shown. Figure 1B A block diagram of a refrigeration unit 100' according to another embodiment of this application is shown.

[0031] like Figure 1A As shown, the refrigeration unit 100 of this application includes the following components: a compressor 101, a condenser 102, a first flow regulating valve 106, an economizer 103, a second flow regulating valve 107, and an evaporator 104. The compressor 101 includes a motor 105. The refrigeration unit 100 is a two-stage or multi-stage refrigeration unit. When the refrigeration unit 100 is running, the refrigerant (e.g., a cooling medium) flows sequentially through the compressor 101, condenser 102, first flow regulating valve 106, economizer 103, second flow regulating valve 107, and evaporator 104, and then returns to the compressor 101 for circulation. In the motor cooling circuit, the refrigerant (e.g., a cooling medium) is output from a cooling source (e.g., condenser 102 or economizer 103) through a flow regulating valve 130, which regulates the flow rate of the refrigerant to be delivered to the motor 105 to regulate the cooling effect of the refrigerant on the motor 105. After cooling the motor 105, the refrigerant becomes gaseous, and then the gaseous refrigerant is transported from the motor 105 back to the return gas location of the refrigeration unit (e.g., at the economizer 103 or the evaporator 104). In one embodiment, the flow control valve 130 is an electronic expansion valve. In other embodiments, the flow control valve 130 includes other suitable valves. Pressure detection devices, temperature detection devices, and power detection devices are provided on various components of the refrigeration unit 100 to detect the parameters of each component and obtain the operating status of each component. The detection devices include sensors.

[0032] The refrigeration unit 100 also includes a control device 108, which includes a processor 109. The control device 108 can acquire the parameters of the aforementioned components of the refrigeration unit 100, and process these parameters through the processor 109 to output a control signal for adjusting the opening of the flow regulating valve. This control signal is then output to the flow regulating valve 130 in the motor cooling circuit to adjust the opening of the flow regulating valve 130, thereby optimizing the cooling control of the motor 105.

[0033] like Figure 1A As shown, the motor 105 of the compressor 101 is equipped with a temperature detection device 114 and a power detection device 113. The temperature detection device 114 is used to detect the temperature T of the windings of the motor 105. windingThe temperature T of the windings of the motor 105 being detected is transmitted via connecting wire 124. winding The signal is transmitted to the control device 108. The power detection device 113 is used to detect the input power P of the motor 105. motor The input power P of the detected motor 105 is transmitted via connection line 123. motor The signal is transmitted to the control device 108. A pressure detection device 110 is installed on the condenser 102. The pressure detection device 110 is used to detect the pressure P of the condenser 102. cond The pressure P of the condenser 102 being detected is transmitted via the connecting line 120. cond The data is transmitted to the control device 108. A pressure detection device 111 is installed on the economizer 103. The pressure detection device 111 is used to detect the pressure P of the economizer 103. eco The pressure P of the detected economizer 103 is transmitted via connecting line 121. eco The signal is transmitted to the control device 108. A pressure detection device 112 is installed on the evaporator 104. The pressure detection device 112 is used to detect the pressure P of the evaporator 104. eva The pressure P of the evaporator 104 being detected is transmitted via connection line 122. eva Transmitted to control device 108.

[0034] The control device 108 controls the temperature T of the windings of the motor 105 received. winding The input power P of motor 105 motor The pressure P of condenser 102 cond The pressure P of the economic instrument 103 eco and / or the pressure P of evaporator 104 eva The signal is processed to output a control signal for adjusting the opening of the flow regulating valve, and this control signal is output to the flow regulating valve 130 via connection line 131. The flow regulating valve 130 adjusts its opening according to the control signal for adjusting the opening, thereby optimizing the cooling control of the motor 105. For example, it ensures that the amount of liquid refrigerant in the motor cavity is optimal throughout the entire operating range of the unit, while the motor temperature meets the requirements.

[0035] like Figure 1BAs shown, the refrigeration unit 100' of this application includes the following components: a compressor 101', a condenser 102', a flow regulating valve 106', and an evaporator 104'. The compressor 101' includes a motor 105'. The refrigeration unit 100' is a single-stage refrigeration unit. When the refrigeration unit 100' is running, the refrigerant (e.g., a cooling medium) flows sequentially through the compressor 101', condenser 102', flow regulating valve 106', and evaporator 104', and then returns to the compressor 101' for circulation. In the motor cooling circuit, the refrigerant (e.g., a cooling medium) is output from a cooling source (e.g., condenser 102') through the flow regulating valve 130', which regulates the flow rate of the refrigerant to be delivered to the motor 105' to regulate the cooling effect of the refrigerant on the motor 105'. After cooling the motor 105', the refrigerant becomes gaseous, and then the gaseous refrigerant is transported from the motor 105' back to the return gas location of the refrigeration unit (e.g., at the evaporator 104'). In one embodiment, the flow control valve 130' is an electronic expansion valve. In other embodiments, the flow control valve 130' includes other suitable valves. Pressure detection devices, temperature detection devices, and power detection devices are also provided on various components of the refrigeration unit 100' to detect the parameters of each component and obtain the operating status of each component. The detection devices include sensors.

[0036] The refrigeration unit 100' also includes a control device 108', which includes a processor 109'. The control device 108' can acquire the parameters of the aforementioned components of the refrigeration unit 100' and process these parameters through the processor 109' to output a control signal for adjusting the opening of the flow regulating valve. This control signal is then output to the flow regulating valve 130' in the motor cooling circuit to adjust the opening of the flow regulating valve 130', thereby optimizing the cooling control of the motor 105'.

[0037] like Figure 1B As shown, the compressor 101' has a temperature detection device 114' and a power detection device 113' installed on its motor 105'. The temperature detection device 114' is used to detect the temperature T of the windings of the motor 105'. winding The temperature T of the windings of the motor 105' is detected via connecting wire 124'. winding 'Transmitted to control device 108'. Power detection device 113' is used to detect the input power P of motor 105'. motor The input power P of the detected motor 105' is transmitted via connection line 123'. motor 'Transmitted to control device 108'. A pressure detection device 110' is installed on the condenser 102'. The pressure detection device 110' is used to detect the pressure P of the condenser 102'. condThe pressure P of the condenser 102' being tested is transmitted via connecting line 120'. cond 'Transmitted to control device 108'. A pressure detection device 112' is installed on the evaporator 104'. The pressure detection device 112' is used to detect the pressure P of the evaporator 104'. eva The pressure P of the evaporator 104' being monitored is transmitted via connection line 122'. eva 'Transmit to control device 108'.

[0038] The control device 108' controls the temperature T of the windings of the received motor 105'. winding The input power P of motor 105 motor The pressure P of 'condenser 102' cond Pressure P of 'and / or evaporator 104' eva The process is performed to output a control signal for adjusting the opening of the flow regulating valve, and this control signal is output to the flow regulating valve 130' via connection line 131'. The flow regulating valve 130' adjusts its opening according to the control signal for adjusting the opening, thereby optimizing the cooling control of the motor 105', for example, ensuring that the amount of liquid refrigerant in the motor cavity is optimal throughout the entire operating range of the unit, while the motor temperature meets the requirements.

[0039] Figure 2 A flowchart of a control method 200 for cooling the motors 105 and 105' of compressors 101 and 101' in a refrigeration unit is shown.

[0040] like Figure 2 As shown, at step 202, the compressor motor cooling control method 200 begins to be executed, and then the process proceeds from step 202 to step 204.

[0041] At step 204, the operating status parameters of the components of refrigeration units 100 and 100' are obtained, and then the process proceeds to step 206. The components of refrigeration unit 100 include compressor 101 (including motor 105), condenser 102, economizer 103, and evaporator 104. The operating status parameters of the components of refrigeration unit 100 include the input power P of motor 105. motor The temperature T of the winding of motor 105 winding The pressure P of condenser 102 cond The pressure P of the economic instrument 103 eco and the pressure P of evaporator 104 eva The components of the refrigeration unit 100' include a compressor 101' (including a motor 105'), a condenser 102', and an evaporator 104'. The operating parameters of the components of the refrigeration unit 100' include the input power P of the motor 105'. motor The temperature T of the winding of motor 105winding The pressure P of 'condenser 102' cond Pressure P of 'and evaporator 104' eva '.

[0042] In step 206, the target value SH of the superheat at the return gas location for motor cooling is obtained based on the acquired operating state parameters. target Then, the process proceeds from step 206 to step 208. During motor cooling, subcooled or saturated refrigerant (e.g., refrigerant) is obtained from the condenser or economizer and delivered to the motor cavity to cool the motor. After cooling the motor, the subcooled or saturated refrigerant (e.g., refrigerant) is returned to the refrigeration unit for circulation, typically in a gaseous state. The component where the refrigerant is returned to the refrigeration unit is called the return gas location for motor cooling. For refrigeration unit 100, when condenser 102 is used as the cooling source for motor 105, the return gas location is at economizer 103 or evaporator 104. When economizer 103 is used as the cooling source for motor 105, the return gas location is at evaporator 104. For refrigeration unit 100', condenser 102' is used as the cooling source for motor 105', and the return gas location is at evaporator 104'.

[0043] At step 208, based on the obtained target value SH of superheat... target The cooling of motors 105 and 105' by refrigeration units 100 and 100' is controlled, and then the process proceeds from step 208 to step 210. Controlling the cooling of motors 105 and 105' by refrigeration units 100 and 100' also includes controlling the cooling of motors 105 and 105' by the acquired target value SH of superheat. target To obtain, for example, the control signals of the corresponding flow regulating valves 130 and 130' can be obtained through a processor, and the opening degree of the flow regulating valves 130 and 130' can be controlled based on the control signals.

[0044] At step 210, the execution of the compressor motor cooling control method 200 is terminated.

[0045] Figure 3 It shows Figure 2 The detailed flowchart of step 206 in the flowchart shown is shown below.

[0046] like Figure 3 As shown, by Figure 2 Step 204 in the middle goes to Figure 3 Step 302. At step 302, the superheat reference value SH is obtained. r Then, proceed from step 302 to step 304. In one embodiment, the superheat reference value SH r The range is 0.1-10℃. The superheat reference value SH r The default value can be set to 5°C. In other embodiments, the superheat reference value SHr It includes other suitable values, and can set other suitable default values.

[0047] At step 304, the superheat bias step width C is obtained, and then the process proceeds to step 306. In one embodiment, the superheat bias step width C is 0-10°C. The default value of the superheat bias step width C can be set to 2°C. The superheat bias step width C is set differently under different operating conditions of the refrigeration unit. In other embodiments, the superheat bias step width C includes other suitable values, and other suitable default values ​​can be set.

[0048] At step 306, the superheat correction coefficient K is obtained based on the acquired operating state parameters, and then the process proceeds to step 308. In one embodiment, the superheat correction coefficient K is the sum of the cooling flow correction coefficient X and the motor heating correction coefficient Y, i.e., K = X + Y. The cooling flow correction coefficient X is a superheat correction coefficient that corrects the target value of superheat at the return gas position based on the motor's cooling fluid supply. The motor heating correction coefficient Y is a superheat correction coefficient that corrects the target value of superheat at the return gas position based on the motor power. In another embodiment, the superheat correction coefficient K is the motor heating and cooling correction coefficient Z, i.e., K = Z. The superheat correction coefficient K can be any other suitable correction coefficient. The superheat correction coefficient K can also be a superheat correction coefficient that corrects the target value of superheat at the return gas position based on the motor winding temperature.

[0049] At step 308, the superheat correction value SH is obtained by multiplying the superheat bias step width C and the superheat correction coefficient K. c That is, SH c =K*C, then proceed from step 308 to step 310. In one embodiment, the superheat correction value SH is obtained based on the cooling flow correction coefficient X and the motor heating correction coefficient Y. c :SH c =K*C=(X+Y)*C=X*C+Y*C. In another embodiment, the overheat correction value SH is obtained based on the motor heating and cooling correction coefficient Z. c :SH c =K*C=Z*C.

[0050] At step 310, at the superheat reference value SH r Superheat correction value SH c To obtain the target value SH of superheat at the return gas location. target That is, SH target =SH r +SH c Then proceed from step 310 to Figure 2Step 208. In one embodiment, the superheat reference value SH is determined using the following formula. r and superheat correction value SH c Obtain the target value SH of the superheat at the return gas location. target :SH target =SH r +SH c =SH r +X*C+Y*C. In another embodiment, the superheat baseline value SH is determined by the following formula. r and superheat correction value SH c Obtain the target value SH of the superheat at the return gas location. target :SH target =SH r +SH c =SH r +Z*C.

[0051] To ensure the target value of superheat SH target Within a reasonable range, set the minimum superheat threshold SH. thre The target value of superheat SH obtained. target Not exceeding the minimum superheat threshold SH thre In one embodiment, the minimum superheat threshold SH thre The minimum superheat threshold is 0-5℃. thre The default value can be set to 1°C. In other embodiments, the minimum superheat threshold SH thre It includes other suitable values, and can set other suitable default values.

[0052] Figure 4A It shows Figure 3 The flowchart shown in the figure is a flowchart of the first embodiment of step 306. Figure 4B It shows Figure 3 The flowchart shown is a flowchart of the first embodiment of step 306.

[0053] like Figure 4A As shown, by Figure 3 Step 304 in the middle goes to Figure 4A Step 402. At step 402, based on the pressure P of the motor's cooling source. cool and the pressure P at the return gas position ret To obtain the cooling flow correction factor X, proceed from step 402 to step 404. Specifically, it is determined based on the pressure P of the motor's cooling source using the following formula. cool and the pressure P at the return gas position ret Obtain the cooling flow correction factor X: X = (P cool –P ret) / A-1, where A is a constant. In other embodiments, the cooling flow correction factor X can be obtained by other suitable methods.

[0054] At step 404, based on the input power P of motors 105 and 105' motor P motor Rated power P of motor 105, 105 rated P rated To obtain the motor heating correction coefficient Y, then proceed from step 404 to... Figure 3 Step 308 in the process. Specifically, the input power P of the motor is determined using the following formula. motor P motor 'and the rated power P of the motor motor P motor Obtain the motor heating correction coefficient Y: Y = 1 - P motor / (B*P rated ), or Y = 1 - P motor ' / (B*P rated '), where B is a constant. In other embodiments, the motor heating correction coefficient Y can be obtained through other suitable methods.

[0055] In specific embodiments of the motor cooling source and return gas location, for the refrigeration unit 100', the condenser 102' serves as the cooling source for the motor 105', and the return gas location is at the evaporator 104', i.e., the first embodiment. For the refrigeration unit 100, when the condenser 102 serves as the cooling source for the motor 105, the return gas location is at the evaporator 104, i.e., the second embodiment. When the condenser 102 serves as the cooling source for the motor 105, the return gas location is at the economizer 103, i.e., the third embodiment. When the economizer 103 serves as the cooling source for the motor 105, the return gas location is at the evaporator 104, i.e., the fourth embodiment.

[0056] In the first embodiment (where the condenser 102' is the cooling source for the motor 105', and the return gas location is at the evaporator 104'), the pressure P of the condenser 102' is determined using the following formula. cond Pressure P of 'and evaporator 104' eva 'Obtain the cooling flow correction factor X: X = (P) cond '–P eva ') / A-1, where A is a constant and the default value is 512kPa.

[0057] In the second embodiment (where the condenser 102 is the cooling source for the motor 105, and the return gas location is at the evaporator 104), the pressure P of the condenser 102 is determined using the following formula. cond and the pressure P of evaporator 104 eva Obtain the cooling flow correction factor X: X = (Pcond –P eva ) / A-1, where A is a constant and the default value is 512kPa.

[0058] In the third embodiment (condenser 102 is the cooling source for motor 105, and the return gas location is at economizer 103), the following formula is used to determine the pressure P of condenser 102. cond And the pressure P of the economic instrument 103 eco Obtain the cooling flow correction factor X: X = (P cond –P eco ) / A-1, where A is a constant and the default value is 206kPa.

[0059] In the fourth embodiment (where the economizer 103 is the cooling source for the motor 105, and the return gas location is at the evaporator 104), the following formula is used to determine the pressure P of the economizer 103. eco and the pressure P of evaporator 104 eva Obtain the cooling flow correction factor X: X = (P eco –P eva ) / A-1, where A is a constant and the default value is 206kPa.

[0060] The input power P of motor 105 is determined using the following formula. motor The rated power P of motor 105 rated Obtain the motor heating correction coefficient Y: Y = 1 - P motor / (B*P rated ), where B is a constant and has a default value of 80%. The following formula is used to determine the input power P of motor 105'. motor Rated power P of 'And motor 105' rated Obtain the motor heating correction coefficient Y: Y = 1 - P motor ' / (B*P rated '), where B is a constant and its default value is 80%.

[0061] In the first embodiment described above, the target value SH of the superheat at the return gas location is obtained using the following formula. target :SH target =SH r +SH c =SH r +X*C+Y*C=SH r +[(P cond '–P eva ') / A-1]*C+[1-P motor ' / (B*P rated In the second embodiment described above, the target value SH of the superheat at the return gas location is obtained using the following formula.target :SH target =SH r +SH c =SH r +X*C+Y*C=SH r +[(P cond –P eva ) / A-1]*C+[1-P motor / (B*P rated In the third embodiment described above, the target value SH of the superheat at the return gas location is obtained using the following formula. target :SH target =SH r +SH c =SH r +X*C+Y*C=SH r +[(P cond –P eco ) / A-1]*C+[1-P motor / (B*P rated In the fourth embodiment described above, the target value SH of the superheat at the return gas location is obtained using the following formula. target :SH target =SH r +SH c =SH r +X*C+Y*C=SH r +[(P eco –P eva ) / A-1]*C+[1-P motor / (B*P rated )]*C.

[0062] When the pressure difference decreases, the coolant supply to the motor decreases. X < 0, and the smaller the pressure difference, the closer X is to -1. The target value for actual superheat decreases, thus compensating for increased coolant supply. When the motor's input power decreases, the motor's cooling demand decreases. Y > 0, and the smaller the power, the closer Y is to 1. The target value for actual superheat increases, thus compensating for reduced coolant supply. This implementation method controls the target value of motor cooling superheat based on changes in pressure difference and motor input power, resulting in more stable unit operation.

[0063] like Figure 4B As shown, by Figure 3 Step 304 in the middle goes to Figure 4B Step 406. At step 406, the temperature T of the windings of motors 105 and 105' is determined. winding T winding 'and the temperature threshold T of the motor windings thre T threTo obtain the motor heating and cooling correction coefficient Z, then proceed from step 406 to... Figure 3 Step 308. Specifically, the temperature T of the windings of motors 105 and 105' is determined using the following formula. winding T winding 'and the temperature threshold T of the motor windings thre T thre 'Obtain the motor heating and cooling correction coefficient Z: Z = 1 / (D*(T) winding –T thre )), or Z = 1 / (D*(T) winding '–T thre ')), where D is a constant and has a default value of 0.5. In other embodiments, the motor heating and cooling correction coefficient Z can be obtained through other suitable methods. The target value SH of the superheat at the return gas location is obtained using the following formula. target :SH target =SH r +SH c =SH r +Z*C=SH r +C / (D*(T winding –T thre )), or SH target =SH r +SH c =SH r +Z*C=SH r +C / (D*(T winding '–T thre This implementation method controls the target value of motor cooling overheat based on the motor winding temperature. Its control logic is simple and reduces the workload of testing and verification.

[0064] Figure 5A The diagram illustrates a graph showing the temperature change of the motor windings over time according to an embodiment of the motor cooling control method of this application. Figure 5B It shows the relationship with Figure 5A The graph showing the change of the motor cavity superheat setpoint over time corresponds to the graph showing the curve of the motor winding. Figure 5C It shows the relationship with Figure 5A The graph of the motor windings corresponds to the graph of the motor cooling EEV opening changing over time. Figure 5D It shows the relationship with Figure 5A The curve of the motor winding corresponds to the curve of the motor current changing over time.

[0065] like Figures 5A-5D As shown, based on the unit's operating status, the target value (superheat setpoint) of the superheat at the return gas location for motor cooling is corrected to a setpoint of 3°C (see...). Figure 5BAt high motor current (see...) Figure 5D Under these operating conditions, the motor temperature is more stable (see...). Figure 5A The motor cooling EEV opening showed no drastic fluctuations, and the refrigerant level in the motor cavity appeared normal. Figure 5B The superheat setting value is corrected to the value corresponding to 3°C. Figure 5A The motor temperature has stabilized at 80°C. Figure 5C The motor cooling EEV opening is basically stable. Figure 5D The high motor current shown is 100A.

[0066] This application corrects the target value of superheat in the control by changing the operating state parameters of the unit, thereby ensuring that the amount of liquid refrigerant in the motor cavity is optimal throughout the entire operating range of the unit, while ensuring stable motor temperature, high unit operating efficiency and stable operation.

[0067] Figure 6A It shows Figure 1A The block diagram shown is of the control device 108 in the refrigeration unit 100. Figure 6B It shows Figure 1B A block diagram of the control device 108' in the refrigeration unit 100' is shown.

[0068] like Figure 6A As shown, the control device 108 includes a bus 601, a processor 602, a memory 603, an input interface 604, and an output interface 605. The processor 602 is... Figure 1A The processor 109 is shown in the diagram. Processor 602, memory 603, input interface 604, and output interface 605 are connected to bus 601. Processor 602 can read programs (or instructions) from memory 603 and execute them to perform data processing and control functions on various components of the refrigeration unit 100. Processor 602 can also write data or programs (or instructions) into memory 603. Memory 603 can store programs (instructions) or data. By executing instructions in memory 603, processor 602 can control memory 603, input interface 604, and output interface 605.

[0069] Input interface 604 is configured to receive pressure P from condenser 102 of pressure sensing device 110 via connection line 120. cond The pressure P received from the economizer 103 of the pressure detection device 111 is received via the connecting line 121. eco The pressure P from the evaporator 104 of the pressure detection device 112 is received via the connecting line 122. eva The input power P of the motor 105 is received from the power detection device 113 via the connection line 123. motorand the temperature T of the windings of the motor 105 received from the temperature detection device 114 via the connecting line 124. winding The input interface 604 is also configured to convert the received parameters into signals recognizable by the processor 602 and output such signals to the processor 602. The processor 602 is configured to process (e.g., calculate) the received signals to output control signals for the flow control valve 130.

[0070] The output interface 605 is configured to receive a control signal from the processor 602, convert the control signal into an output signal suitable for the flow control valve 130, and send the output signal to the flow control valve 130 via the connection line 131, so that the flow control valve 130 can adjust its opening based on the received output signal.

[0071] like Figure 6B As shown, the control device 108' includes a bus 601', a processor 602', a memory 603', an input interface 604', and an output interface 605'. The processor 602' is... Figure 1B The processor 109' is shown in the diagram. Processor 602', memory 603', input interface 604', and output interface 605' are connected to bus 601'. Processor 602' can read programs (or instructions) from memory 603' and execute them to perform data processing and control functions on various components of the refrigeration unit 100'. Processor 602' can also write data or programs (or instructions) into memory 603'. Memory 603' can store programs (instructions) or data. By executing instructions in memory 603', processor 602' can control memory 603', input interface 604', and output interface 605'.

[0072] Input interface 604' is configured to receive pressure P from condenser 102' via connection line 120'. cond The pressure P from the evaporator 104' is received via the connection line 122'. eva The input power P from the motor 105' is received from the power detection device 113' via the connection line 123'. motor The temperature T of the windings of the motor 105' is received from the temperature sensing device 114' via the connecting line 124'. winding The input interface 604 is also configured to convert the received parameters into signals recognizable by the processor 602 and output those signals to the processor 602. The processor 602 is configured to process (e.g., calculate) the received signals to output control signals for the flow control valve 130.

[0073] The output interface 605' is configured to receive a control signal from the processor 602', convert the control signal into an output signal suitable for the flow control valve 130', and send the output signal to the flow control valve 130' via the connection line 131', so that the flow control valve 130' can adjust its opening based on the received output signal.

[0074] Although this application has been described with reference to examples of the embodiments outlined above, various alternatives, modifications, variations, improvements, and / or substantially equivalents, whether known or currently or soon to be foreseen, will likely be apparent to those skilled in the art. Furthermore, the technical effects and / or technical problems described herein are exemplary and not limiting; therefore, the disclosures herein may be used to solve other technical problems and have other technical effects and / or can solve other technical problems. Thus, the examples of embodiments of this application as set forth above are intended to be illustrative and not limiting. Various changes can be made without departing from the spirit or scope of this application. Therefore, this application is intended to include all known or previously developed alternatives, modifications, variations, improvements, and / or substantially equivalents.

Claims

1. A control method for cooling the motor of a compressor in a refrigeration unit, the refrigeration unit (100, 100') comprising: the compressor (101'), condenser (102'), and evaporator (104'), or the compressor (101), condenser (102), economizer (103), and evaporator (104'), characterized in that, The control method for cooling the motor of the compressor in the refrigeration unit includes: Obtain the operating status parameters of the components of the refrigeration unit (100, 100'); The target value of superheat at the return gas location of the motor (105, 105') cooling system is obtained based on the acquired operating state parameters; and The cooling of the motor (105, 105') by the refrigeration unit (100, 100') is controlled based on the obtained target value of superheat. The target value for obtaining the superheat at the return gas location of the motor (105, 105') includes: Obtain the superheat baseline value SH r and superheat bias step width C; The superheat correction coefficient K is obtained based on the acquired operating status parameters; The superheat correction value SH is obtained by multiplying the superheat bias step width C and the superheat correction coefficient K. c ;as well as The superheat reference value SH r The superheat correction value SH is superimposed on it. c To obtain the target value SH of superheat at the return gas location. target .

2. The control method for motor cooling of a compressor in a refrigeration unit according to claim 1, characterized in that, When the condenser (102, 102') is used as the cooling source for the motor (105, 105'), the return gas location is at the economizer (103) or at the evaporator (104, 104'); and When the economizer (103) is used as a cooling source for the motor (105), the return gas location is at the evaporator (104).

3. The control method for motor cooling of a compressor in a refrigeration unit according to claim 1, characterized in that, The superheat correction factor K is the sum of the cooling flow correction factor X and the motor heating correction factor Y. Among them, the pressure P of the cooling source based on the motor (105, 105') cool and the pressure P at the return gas position ret To obtain the cooling flow correction coefficient X; and Based on the input power P of the motor (105, 105') motor P motor The rated power P of the motor (105, 105') rated P rated To obtain the motor heating correction coefficient Y.

4. The control method for motor cooling of a compressor in a refrigeration unit according to claim 3, characterized in that, Based on the pressure P of the cooling source of the motor (105, 105') cool and the pressure P at the return gas position ret The cooling flow correction factor X is obtained based on the following formula: X = (P) cool – P ret ) / A-1, where A is a constant; and Based on the input power P of the motor (105, 105') motor P motor The rated power P of the motor (105, 105') rated P rated The method for obtaining the motor heating correction factor Y includes using the following formula: Y = 1 - P motor / (B*P rated ), or Y = 1 - P motor ' / (B*P rated '), where B is a constant.

5. The control method for motor cooling of a compressor in a refrigeration unit according to claim 1, characterized in that, The overheating correction factor K is the motor heating and cooling correction factor Z. Wherein, the temperature T is based on the winding temperature of the motor (105, 105'). winding T winding The temperature threshold T of the windings of the motor (105, 105') thre T thre To obtain the motor heating and cooling correction coefficient Z.

6. The control method for motor cooling of a compressor in a refrigeration unit according to claim 5, characterized in that, Based on the temperature T of the windings of the motor (105, 105') winding T winding The temperature threshold T of the windings of the motor (105, 105') thre T thre The method for obtaining the motor heating and cooling correction coefficient Z includes using the following formula: Z=1 / (D*(T) winding –T thre )), or Z=1 / (D*( T winding '–T thre ')), where D is a constant.

7. The control method for motor cooling of a compressor in a refrigeration unit according to claim 1, characterized in that, The superheat offset step width is different under different operating conditions of the refrigeration unit (100, 100'). The superheat correction factor K is the sum of the cooling flow correction factor X and the motor heating correction factor Y, wherein the cooling flow correction factor X is a superheat correction factor that corrects the target value of superheat at the return gas position based on the cooling liquid supply of the motor, and the motor heating correction factor Y is a superheat correction factor that corrects the target value of superheat at the return gas position based on the power of the motor, or The overheating correction factor K is the motor heating and cooling correction factor Z, wherein the motor heating and cooling correction factor Z is an overheating correction factor that corrects the target value of overheating at the return gas position based on the winding temperature of the motor.

8. The control method for motor cooling of a compressor in a refrigeration unit according to claim 1, characterized in that, The target value of the superheat at the return gas location of the motor (105, 105') cooling is greater than the minimum superheat threshold.

9. A refrigeration unit, characterized in that, The refrigeration unit (100, 100') includes the following components: Compressor (101'), condenser (102'), and evaporator (104'); or Compressor (101), condenser (102), economizer (103) and evaporator (104). The refrigeration unit (100, 100') further includes: Several detection devices (110, 111, 112, 113, 114; 110', 112', 113', 114'), configured to detect the operating status parameters of components of the refrigeration unit (100, 100'); and A control device (108, 108') comprising a processor (109, 109') configured to perform a control method (200) for motor cooling of a compressor for a refrigeration unit as claimed in any one of claims 1-8.

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