Methods and apparatus for controlling magnetic levitation systems; magnetic levitation systems

Abstract

This application discloses a method for controlling a magnetic levitation system. The magnetic levitation system includes: a refrigerant circulation loop, comprising a condenser, a dryer filter, a plate heat exchanger, an evaporator, and a compressor connected in sequence; a liquid suction line, comprising a cold storage tank and a refrigerant pump, the refrigerant pump being connected in series between the liquid inlet of the cold storage tank and the liquid outlet of the evaporator; a liquid return line, connected in series between the first liquid outlet of the cold storage tank and the liquid inlet of the evaporator; a first gas supply line, comprising an electronic expansion valve, one end of which is connected to the second liquid outlet of the cold storage tank, and the other end of which is connected to the air inlet of the compressor via the plate heat exchanger; and a second gas supply line, one end of which is connected to the outlet of the dryer filter, and the other end of which is connected to the air inlet of the compressor. The method includes: determining the suction pressure P and suction temperature T at the compressor suction port; and controlling the opening degree of the electronic expansion valve and the speed of the refrigerant pump according to P and T to increase the superheat of the refrigerant at the compressor suction port to avoid liquid carryover during suction.

Description

Technical Field

[0001] This application relates to the field of smart home appliance technology, such as a method and apparatus for controlling a magnetic levitation system, and a magnetic levitation system. Background Technology

[0002] Currently, surge is an inherent characteristic of chiller units, and how to avoid surge has become an urgent problem to be solved.

[0003] The related technology discloses a variable frequency centrifugal chiller unit, which includes a variable frequency centrifugal compressor, an evaporator and a condenser. The compressor includes an air intake port connected to the evaporator and an exhaust port connected to the condenser. A flow detection device for detecting the real-time exhaust volume of the compressor is also provided at the air intake port end. A bypass pipeline is also provided in parallel between the air intake and exhaust ports of the compressor, and a bypass valve device with an adjustable opening is provided on the bypass pipeline.

[0004] In the process of implementing the embodiments of this disclosure, at least the following problems were found in the related art:

[0005] If the refrigerant at the compressor suction port is not sufficiently superheated, the compressor is prone to liquid carryover during suction. Liquid refrigerant enters the compressor suction port, and the liquid refrigerant impacts the high-speed rotating impeller, thereby damaging the compressor. Summary of the Invention

[0006] To provide a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. This summary is not intended as a general commentary, nor is it intended to identify key / important components or describe the scope of protection of these embodiments, but rather as a prelude to the detailed description that follows.

[0007] This disclosure provides a method and apparatus for controlling a magnetic levitation system, thereby avoiding the occurrence of air-liquid contamination and reducing damage to the compressor.

[0008] In some embodiments, the magnetic levitation system includes: a refrigerant circulation loop, comprising a condenser, a dryer filter, a plate heat exchanger, an evaporator, and a compressor connected in sequence; a liquid suction line, comprising a cold storage tank and a refrigerant pump connected in sequence, the refrigerant pump being connected in series between the liquid inlet of the cold storage tank and the liquid outlet of the evaporator, for drawing liquid from the evaporator into the cold storage tank; a liquid return line, connected in series between the first liquid outlet of the cold storage tank and the liquid inlet of the evaporator; a first gas supply line, comprising an electronic expansion valve, one end of which is connected to the second liquid outlet of the cold storage tank, and the other end of which is connected to the air inlet of the compressor via the plate heat exchanger; a second gas supply line, one end of which is connected to the outlet of the dryer filter, and the other end of which is connected to the air inlet of the compressor; the method includes: determining the suction pressure P and suction temperature T of the compressor suction port; controlling the opening degree of the electronic expansion valve and the speed of the refrigerant pump according to P and T, so as to increase the superheat of the refrigerant in the compressor suction port to avoid liquid carryover during suction.

[0009] In some embodiments, the apparatus includes a processor and a memory storing program instructions, the processor being configured to execute the method described above for controlling a magnetic levitation system when the program instructions are executed.

[0010] In some embodiments, the magnetic levitation system includes: a refrigerant circulation loop comprising a condenser, a dryer filter, a plate heat exchanger, an evaporator, and a compressor connected in sequence; a liquid suction line comprising a cold storage tank and a refrigerant pump connected in sequence, the refrigerant pump being connected in series between the liquid inlet of the cold storage tank and the liquid outlet of the evaporator for drawing liquid from the evaporator into the cold storage tank; a liquid return line connected in series between the first liquid outlet of the cold storage tank and the liquid inlet of the evaporator; a first gas supply line comprising an electronic expansion valve, one end of which is connected to the second liquid outlet of the cold storage tank, and the other end of which is connected to the air inlet of the compressor via the plate heat exchanger; a second gas supply line, one end of which is connected to the outlet of the dryer filter, and the other end of which is connected to the air inlet of the compressor; and the aforementioned device for controlling the magnetic levitation system.

[0011] The method and apparatus for controlling a magnetic levitation system, and the magnetic levitation system provided in this disclosure, can achieve the following technical effects:

[0012] A refrigerant pump extends a suction line from the evaporator drain port. The pump speed is controlled based on the compressor suction pressure and temperature, ensuring the low-temperature, low-pressure refrigerant in the evaporator enters the cold storage tank more effectively, lowering the evaporator liquid level and preventing liquid carryover due to excessive liquid level. Simultaneously, the opening of the electronic expansion valve in the first makeup gas line is controlled based on the compressor suction pressure and temperature. This prevents direct heat exchange between the low-pressure, low-temperature refrigerant in the cold storage tank and the high-temperature, high-pressure refrigerant from the dryer filter within the heat exchanger, forming superheated gaseous refrigerant. This superheated gaseous refrigerant mixes with the unsaturated refrigerant at the compressor suction port, ultimately increasing the superheat of the suction port refrigerant and preventing liquid carryover due to insufficient suction superheat. This avoids liquid carryover in the compressor suction and prevents impact between the liquid refrigerant and the high-speed rotating impeller, reducing damage to the compressor.

[0013] The above general description and the description below are exemplary and illustrative only and are not intended to limit this application. Attached Figure Description

[0014] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations and drawings do not constitute a limitation on the embodiments. Elements having the same reference numerals in the drawings are shown as similar elements. The drawings are not to be scaled. And wherein:

[0015] Figure 1 This is a schematic diagram of the structure of a magnetic levitation system provided in an embodiment of this disclosure;

[0016] Figure 2 This is a schematic diagram of a method for controlling a magnetic levitation system provided in an embodiment of this disclosure;

[0017] Figure 3 This is a schematic diagram of another method for controlling a magnetic levitation system provided in an embodiment of this disclosure;

[0018] Figure 4 This is a schematic diagram of another method for controlling a magnetic levitation system provided in an embodiment of this disclosure;

[0019] Figure 5 This is a schematic diagram of another method for controlling a magnetic levitation system provided in an embodiment of this disclosure;

[0020] Figure 6 This is a schematic diagram of a device for controlling a magnetic levitation system provided in an embodiment of this disclosure.

[0021] Figure label:

[0022] 1: Refrigerant circulation loop; 11: Condenser; 12: Dryer filter; 13: Economizer; 14: Plate heat exchanger; 15: Evaporator; 16: Compressor; 17: Temperature sensor; 18: Pressure sensor; 2: Liquid suction line; 21: Cold storage tank; 22: Refrigerant pump; 23: Check valve; 3: Liquid return line; 31: Solenoid valve; 4: First gas supply line; 41: Electronic expansion valve; 5: Second gas supply line. Detailed Implementation

[0023] To provide a more detailed understanding of the features and technical content of the embodiments of this disclosure, the implementation of the embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. The accompanying drawings are for illustrative purposes only and are not intended to limit the embodiments of this disclosure. In the following technical description, for ease of explanation, several details are used to provide a full understanding of the disclosed embodiments. However, one or more embodiments may still be implemented without these details. In other cases, well-known structures and devices may be simplified in their depiction to simplify the drawings.

[0024] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this disclosure described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0025] Unless otherwise stated, the term "multiple" means two or more.

[0026] In this embodiment of the disclosure, the character " / " indicates that the objects before and after it are in an "or" relationship. For example, A / B means: A or B.

[0027] The term "and / or" describes an association between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or A and B.

[0028] The term "correspondence" can refer to an association or binding relationship. The correspondence between A and B means that there is an association or binding relationship between A and B.

[0029] Combination Figure 1As shown, this embodiment of the present disclosure provides a magnetic levitation system, including a refrigerant circulation loop 1, a liquid suction line 2, a liquid return line 3, a first air supply line 4, and a second air supply line 5. The refrigerant circulation loop 1 includes a condenser 11, a dryer filter 12, a heat exchanger 14, an evaporator 15, and a compressor 16 connected in sequence. The liquid suction line 2 includes a cold storage tank 21 and a refrigerant pump 22 connected in sequence. The refrigerant pump 22 is connected in series between the liquid inlet of the cold storage tank 21 and the liquid outlet of the evaporator 15, for drawing liquid from the evaporator 15 into the cold storage tank 21. The liquid return line 3 is connected in series between the first liquid outlet of the cold storage tank 21 and the liquid inlet of the evaporator 15. The first air supply line 4 includes an electronic expansion valve 41, one end of which is connected to the second liquid outlet of the cold storage tank 21, and the other end is connected to the air inlet of the compressor 16 via the heat exchanger 14. The second air supply line 5 is connected at one end to the outlet of the dryer filter 12 and at the other end to the air inlet of the compressor 16.

[0030] Optionally, plate heat exchanger 14 includes flash plate heat exchanger.

[0031] Optionally, the exhaust port of compressor 16 is connected to the suction port of condenser 11, and the suction port of compressor 16 is connected to the exhaust port of evaporator 15.

[0032] Optionally, the refrigerant circulation loop also includes an economizer 13. The economizer 13 is connected in series between the dryer filter 12 and the heat exchanger 14. The inlet of the economizer 13 is connected to the outlet of the dryer filter 12, and the outlet of the economizer 13 is connected to the heat exchanger 14. One end of the second make-up gas line 5 is connected to the outlet of the dryer filter 12 through the outlet of the economizer 13.

[0033] Optionally, the refrigerant circulation loop 1 also includes a temperature sensor 17 and a pressure sensor 18. The temperature sensor 17 is connected in series between the suction port of the compressor 16 and the discharge port of the evaporator 15 to detect the suction temperature of the compressor 16. The pressure sensor 18 is connected in series between the suction port of the compressor 16 and the discharge port of the evaporator 15 to detect the suction pressure of the compressor 16.

[0034] Optionally, the suction line 2 also includes a one-way valve 23. The one-way valve 23 is connected in series between the liquid inlet of the cold storage tank 21 and the refrigerant pump 22.

[0035] Optionally, the return line 3 includes a solenoid valve 31. The solenoid valve 31 is connected in series between the outlet of the economizer 13 and the inlet of the compressor 16. When the evaporator liquid level is too low, the solenoid valve 13 opens, and the liquid in the cold storage tank 21 replenishes the liquid level of the evaporator 15 under pressure.

[0036] Optionally, the head of the refrigerant pump 22 ensures the pressure P inside the cold storage tank 21. 储冷罐 Pressure P of evaporator 15 蒸发器The relationship is: P 储冷罐 =P 蒸发器 +P0. Where P0 is the preset pressure difference. Specifically, the value of P0 ranges from [50 kPa to 100 kPa].

[0037] The magnetic levitation system provided in this embodiment uses a refrigerant pump to draw liquid from the evaporator drain port. Adjusting the pump speed allows the low-temperature, low-pressure refrigerant in the evaporator to better enter the cold storage tank, lowering the evaporator liquid level and preventing liquid carryover due to excessive liquid level. Simultaneously, controlling the opening of the electronic expansion valve in the first gas supply line prevents direct heat exchange between the low-pressure, low-temperature refrigerant in the cold storage tank and the high-temperature, high-pressure refrigerant from the dryer filter within the heat exchanger. This creates superheated gaseous refrigerant, which mixes with the unsaturated refrigerant at the compressor suction port, ultimately increasing the superheat of the suction port refrigerant and preventing liquid carryover due to insufficient suction superheat. This avoids liquid carryover in the compressor suction and prevents impact between the liquid refrigerant entering the suction port and the high-speed rotating impeller, reducing damage to the compressor.

[0038] Combination Figure 2 As shown, this disclosure provides a method for controlling a magnetic levitation system, including:

[0039] S201, The magnetic levitation system determines the suction pressure P and suction temperature T at the compressor's suction port.

[0040] S202, the magnetic levitation system controls the opening degree of the electronic expansion valve and the speed of the refrigerant pump according to P and T, so as to increase the superheat of the refrigerant in the compressor suction port to avoid liquid carry-in during suction.

[0041] The method for controlling a magnetic levitation system provided in this disclosure involves a refrigerant pump leading to a liquid suction line at the evaporator drain port. The pump speed is controlled based on the suction pressure and temperature at the compressor suction port, allowing the low-temperature, low-pressure refrigerant in the evaporator to better enter the cold storage tank, thus lowering the evaporator liquid level and preventing liquid carryover due to excessive liquid level. Simultaneously, the opening of the electronic expansion valve in the first make-up gas line is controlled based on the suction pressure and temperature at the compressor suction port. This prevents the low-pressure, low-temperature refrigerant in the cold storage tank from directly contacting the high-temperature, high-pressure refrigerant from the dryer filter within the heat exchanger, forming superheated gaseous refrigerant. This superheated gaseous refrigerant mixes with the unsaturated refrigerant at the compressor suction port, ultimately increasing the superheat of the refrigerant at the suction port and preventing liquid carryover due to insufficient suction superheat. This avoids liquid carryover in the compressor suction port and prevents impact between the liquid refrigerant and the high-speed rotating impeller caused by liquid refrigerant entering the suction port, reducing damage to the compressor.

[0042] Optionally, the magnetic levitation system controls the opening degree of the electronic expansion valve and the speed of the refrigerant pump based on P and T, including: the magnetic levitation system determines the unit superheat T based on P and T. 吸气过热 The magnetic levitation system is based on T 吸气过热 Controlling the opening of the electronic expansion valve and the speed of the refrigerant pump allows for better control of the electronic expansion valve opening and the refrigerant pump speed in the first replenishment gas line. This helps determine the unit's superheat based on the compressor's suction pressure and temperature, and then uses the unit's superheat to determine whether the magnetic levitation system is experiencing liquid carryover during suction. This prevents liquid carryover caused by insufficient suction superheat.

[0043] Optionally, the magnetic levitation system determines the unit superheat T based on P and T. 吸气过热 This includes: the magnetic levitation system determining the saturation temperature T corresponding to the refrigerant saturation pressure based on P1. 饱和 The magnetic levitation system is based on T1 and T2. 饱和 Determine the unit superheat T 吸气过热 This approach first determines the saturation temperature corresponding to the refrigerant saturation pressure based on the suction pressure at the compressor's suction port. Then, it determines the unit's superheat based on the saturation temperature corresponding to the refrigerant saturation pressure and the suction temperature. This allows for better determination of whether the magnetic levitation system experiences liquid carryover during suction based on the unit's superheat. Consequently, it enables better control of the opening of the electronic expansion valve in the first replenishment gas pipeline and the speed of the refrigerant pump based on the unit's superheat, thereby preventing liquid carryover during suction caused by insufficient suction superheat.

[0044] Optionally, the magnetic levitation system determines the saturation temperature T corresponding to the refrigerant saturation pressure based on P1. 饱和 This includes: calculation of T for magnetic levitation systems. 饱和 = A*P1+B. Where, T 饱和 Let A and B be the saturation temperature corresponding to the refrigerant's saturation pressure, and A and B be constants. Specifically, A = A1 + A2 + A3 + A4 + A5 + A6, where A1, A2, A3, A4, A5, and A6 are constants. More specifically, taking R134a refrigerant as an example, the value of A1 can be -2.3691, the value of A2 can be 21.434, the value of A3 can be -78.312, the value of A4 can be 150.32, the value of A5 can be -170.29, the value of A6 can be 144.71, and the value of B can be -22.567. The values ​​of A1, A2, A3, A4, A5, A6, and B are related to the refrigerant type and can be adjusted according to the refrigerant type; these will not be listed here. In this way, the higher the suction pressure at the compressor's suction port, the higher the saturation temperature corresponding to the refrigerant's saturation pressure, which is beneficial for determining the saturation temperature corresponding to the refrigerant's saturation pressure based on the suction pressure at the compressor's suction port.

[0045] Optionally, the magnetic levitation system is based on T1 and T2. 饱和 Determine the unit superheat T 吸气过热 This includes: calculation of T for magnetic levitation systems. 吸气过热 =T1-T 饱和 Among them, T 吸气过热 This refers to the unit's superheat. This allows for a better determination of the unit's superheat based on the saturation temperature and suction temperature corresponding to the refrigerant's saturation pressure, which in turn helps in determining whether the magnetic levitation system is experiencing suction liquid carryover.

[0046] Optionally, the magnetic levitation system is based on T 吸气过热 Controlling the opening degree of the electronic expansion valve and the speed of the refrigerant pump includes: [at T...] 吸气过热 When the speed is greater than T0, the magnetic levitation system keeps the electronic expansion valve and refrigerant pump closed, ensuring that both the opening of the electronic expansion valve and the speed of the refrigerant pump are zero. At T... 吸气过热 When T ≤ T0, the magnetic levitation system controls the opening degree of the electronic expansion valve to be Y% and the speed of the refrigerant pump to be Z. The magnetic levitation system is based on T... 吸气过热 The first time, the opening degree of the electronic expansion valve and the speed of the refrigerant pump were recontrolled, so that T 吸气过热 =T obj Where T0 is the preset superheat threshold, Y% is the preset initial opening degree, Z is the preset initial rotational speed, and T... obj The target superheat is T0. Specifically, T0 can be 1°C, T... obj The value can be 3℃. T0, T obj The value of can be adjusted according to the properties of the magnetic levitation system, which will not be listed here. Thus, in T 吸气过热 When the temperature exceeds T0, it indicates that the magnetic levitation system is operating normally. At this time, the electronic expansion valve and refrigerant pump remain closed, and there will be no air intake or liquid carryover. However, at T... 吸气过热 When the temperature is ≤T0, it indicates that liquid carryover is about to occur in the magnetic levitation system. At this point, the opening of the electronic expansion valve is controlled to Y% and the refrigerant pump speed to Z. Then, based on the unit's superheat, the opening of the electronic expansion valve and the refrigerant pump speed are readjusted to ensure the unit's superheat reaches the target superheat, preventing liquid carryover due to insufficient suction superheat. This avoids liquid carryover in the compressor and prevents the impact of liquid refrigerant entering the suction port with the high-speed rotating impeller, reducing damage to the compressor.

[0047] Optionally, the magnetic levitation system is based on T 吸气过热 The first time, the opening degree of the electronic expansion valve and the speed of the refrigerant pump were recontrolled, so that T 吸气过热 =T obj Including: in T 吸气过热When T > T0, the magnetic levitation system controls the electronic expansion valve to maintain an opening of Y%, and adjusts the refrigerant pump speed according to the PID control to ensure T 吸气过热 =T obj In T 吸气过热 When T ≤ T0, the opening degree of the electronic expansion valve controlled by the magnetic levitation system increases by M% every preset time interval, and the speed of the refrigerant pump increases by N every preset time interval. The magnetic levitation system is based on T... 吸气过热 The opening degree of the electronic expansion valve and the speed of the refrigerant pump were recontrolled a second time, so that T 吸气过热 =T obj Where M% is the preset opening increase and N is the preset rotational speed increase. Specifically, the preset duration can be 1 second. The preset duration can be adjusted according to the properties of the magnetic levitation system, which will not be listed here. Thus, when T 吸气过热 After controlling the electronic expansion valve opening to Y% and the refrigerant pump speed to Z when T ≤ T0, the electronic expansion valve opening and refrigerant pump speed are controlled again based on the unit's superheat. At T 吸气过热 When the temperature exceeds T0, it indicates that the magnetic levitation system has resumed normal operation. At this time, the opening of the electronic expansion valve is kept constant, and the speed of the refrigerant pump is finely adjusted according to the PID control to avoid large fluctuations in the unit's overheating and to prevent liquid carryover during air intake. At T... 吸气过热 If the temperature is ≤T0, it indicates that the magnetic levitation system is still about to experience liquid carryover during intake. In this case, the opening of the electronic expansion valve and the speed of the refrigerant pump are both increased. Then, the opening of the electronic expansion valve and the speed of the refrigerant pump are readjusted based on the unit's superheat. This ensures the unit's superheat reaches the target superheat, preventing liquid carryover due to insufficient intake superheat. This avoids liquid carryover in the compressor and prevents the impact of liquid refrigerant entering the intake port with the high-speed rotating impeller, reducing damage to the compressor.

[0048] Optionally, the magnetic levitation system is based on T 吸气过热 The opening degree of the electronic expansion valve and the speed of the refrigerant pump were recontrolled a second time, so that T 吸气过热 =T obj Including: in T 吸气过热 When T > T0, the magnetic levitation system maintains the opening of the electronic expansion valve at (Y+a*M)%, and adjusts the speed of the refrigerant pump according to the PID control, so that T 吸气过热 =T obj In T 吸气过热 When T ≤ T0, the magnetic levitation system will trigger an alarm. Here, a is a constant. Thus, when T... 吸气过热 After controlling the opening degree of the electronic expansion valve to Y% and the speed of the refrigerant pump to Z when T ≤ T0, T is detected again. 吸气过热 After increasing both the opening degree of the electronic expansion valve and the speed of the refrigerant pump at T ≤T0, 吸气过热When T > T0, it indicates that the magnetic levitation system has resumed normal operation. At this time, the opening of the electronic expansion valve is kept constant, and the speed of the refrigerant pump is finely adjusted according to the PID control to avoid large fluctuations in the unit's overheating and prevent liquid carryover during air intake. When the electronic expansion valve is at its preset maximum opening, and T... 吸气过热 If the temperature is ≤T0, it indicates that the magnetic levitation system is about to experience liquid carryover during air intake. At this point, it is no longer possible to adjust the opening of the electronic expansion valve, and an alarm should be triggered to alert the user to the abnormal operation of the magnetic levitation system. This prevents liquid carryover during air intake of the compressor and avoids the impact between the liquid refrigerant entering the intake port and the high-speed rotating impeller, thus reducing damage to the compressor.

[0049] Combination Figure 3 As shown, this disclosure provides another method for controlling a magnetic levitation system, including:

[0050] S301, the magnetic levitation system determines the suction pressure P and suction temperature T at the compressor's suction port.

[0051] S302, the magnetic levitation system controls the opening degree of the electronic expansion valve and the speed of the refrigerant pump according to P and T, so as to increase the superheat of the refrigerant in the compressor suction port to avoid liquid carry-in during suction.

[0052] S303, The magnetic levitation system determines the compressor's actual speed V1 and surge speed V. 喘 .

[0053] S304, the magnetic levitation system is based on V1 and V 喘 Control the opening of the electronic expansion valve to increase the suction pressure at the compressor inlet to avoid surge.

[0054] The method for controlling a magnetic levitation system provided in this disclosure involves a refrigerant pump leading to a suction line at the evaporator drain port. The pump speed is controlled based on the suction pressure and temperature at the compressor suction port, allowing the low-temperature, low-pressure refrigerant in the evaporator to better enter the cold storage tank, thus lowering the evaporator liquid level and preventing liquid carryover due to excessive liquid level. Simultaneously, the opening of the electronic expansion valve in the first make-up gas line is controlled based on the suction pressure and temperature at the compressor suction port, and also based on the actual compressor speed and surge speed. This ensures that the low-pressure, low-temperature refrigerant in the cold storage tank does not directly contact the high-temperature, high-pressure refrigerant from the dryer filter for heat exchange within the heat exchanger, forming a superheated gaseous refrigerant. This superheated gaseous refrigerant mixes with the unsaturated refrigerant at the compressor suction port, ultimately increasing the superheat of the suction port refrigerant and preventing liquid carryover due to insufficient suction superheat. Simultaneously, increasing the suction pressure at the compressor suction port reduces the compression ratio between the cold storage tank and the compressor to avoid surge. This avoids liquid carryover and surge phenomena in the compressor during intake, and prevents the impact between the liquid refrigerant entering the intake port and the high-speed rotating impeller, thus reducing damage to the compressor.

[0055] Optionally, the magnetic levitation system is based on V1 and V 喘 Controlling the opening of the electronic expansion valve includes: the magnetic levitation system based on V1 and V... 喘 The speed deviation ΔV between the surge speed and the actual compressor speed is determined. The magnetic levitation system controls the opening of the electronic expansion valve based on ΔV. This allows for better judgment of whether surge has occurred in the magnetic levitation system based on the speed deviation between the actual compressor speed and the surge speed. Consequently, it facilitates better control of the electronic expansion valve opening based on this speed deviation, increasing the suction pressure at the compressor intake port and reducing the compression ratio between the cold storage tank and the compressor to avoid surge.

[0056] Optionally, the magnetic levitation system is based on V1 and V 喘 Determine the speed deviation ΔV between the surge speed and the actual compressor speed, including: ΔV = V 喘 -V1. Where ΔV is the speed deviation between the surge speed and the actual compressor speed. This helps to better determine the speed deviation between the surge speed and the actual compressor speed based on the actual compressor speed and the surge speed.

[0057] Optionally, the magnetic levitation system controls the opening of the electronic expansion valve based on ΔV, including: when ΔV < ΔV0, the magnetic levitation system keeps the electronic expansion valve closed, making its opening zero. When ΔV ≥ ΔV0, the magnetic levitation system controls the opening of the electronic expansion valve to Y%. The magnetic levitation system then re-controls the opening of the electronic expansion valve based on ΔV for the first time. Here, ΔV0 is a preset speed deviation threshold, and Y% is a preset initial opening. Specifically, the value of ΔV0 can be 500 RPM. The value of ΔV0 can be reasonably set according to the properties of the magnetic levitation system, and will not be listed here. Thus, when ΔV < ΔV0, it indicates that the magnetic levitation system is operating normally, and keeping the electronic expansion valve closed will not cause surge. When ΔV ≥ ΔV0, it indicates that the magnetic levitation system is experiencing slight surge, and the opening of the electronic expansion valve is controlled to Y%. Subsequently, the opening of the electronic expansion valve is re-controlled based on the speed deviation between the surge speed and the actual speed of the compressor. This helps to increase the suction pressure at the compressor's intake port and reduce the compression ratio between the cold storage tank and the compressor, thus avoiding surge.

[0058] Optionally, the magnetic levitation system re-controls the opening of the electronic expansion valve based on ΔV for the first time, including: when ΔV < ΔV0, the magnetic levitation system maintains the opening of the electronic expansion valve at Y%. When ΔV ≥ ΔV0, the magnetic levitation system increases the opening of the electronic expansion valve by M% every preset time interval. The magnetic levitation system then re-controls the opening of the electronic expansion valve based on ΔV for the second time. Here, M% is the preset opening increase. Thus, when ΔV ≥ ΔV0, after controlling the opening of the electronic expansion valve to Y%, the system re-determines whether micro-surge will occur based on the speed deviation between the surge speed and the actual compressor speed. When ΔV < ΔV0, it indicates that the magnetic levitation system has returned to normal operation; maintaining the opening of the electronic expansion valve at Y% will not cause surge. When ΔV ≥ ΔV0, it indicates that the magnetic levitation system is still experiencing micro-surge; the opening of the electronic expansion valve is increased, and the opening of the electronic expansion valve is re-controlled based on the speed deviation between the surge speed and the actual compressor speed. This helps to increase the suction pressure at the compressor's intake port and reduce the compression ratio between the cold storage tank and the compressor, thus avoiding surge.

[0059] Optionally, the magnetic levitation system re-controls the opening of the electronic expansion valve based on ΔV, including: when ΔV < ΔV0, the magnetic levitation system maintains the opening of the electronic expansion valve at (Y + a*M)%. When the opening of the electronic expansion valve is at the preset maximum opening and ΔV ≥ ΔV0, the magnetic levitation system triggers an alarm. Thus, after controlling the opening of the electronic expansion valve to Y% when ΔV ≥ ΔV0, and then detecting ΔV < ΔV0 and increasing the opening of the electronic expansion valve, if ΔV < ΔV0, it indicates that the magnetic levitation system has returned to normal operation. Maintaining the opening of the electronic expansion valve at (Y + a*M)% will not cause surge. If the opening of the electronic expansion valve is at the preset maximum opening and ΔV ≥ ΔV0, it indicates that the magnetic levitation system is still experiencing slight surge. In this case, the opening of the electronic expansion valve cannot be adjusted, and an alarm is triggered to alert the user to the abnormal operation of the magnetic levitation system. This helps to increase the suction pressure at the compressor's suction port and reduce the compression ratio between the cold storage tank and the compressor, thereby avoiding surge.

[0060] Combination Figure 4 As shown, this disclosure provides another method for controlling a magnetic levitation system, including:

[0061] S401, the magnetic levitation system determines the suction pressure P and suction temperature T at the compressor's suction port.

[0062] S402, the magnetic levitation system determines the unit superheat T based on P and T. 吸气过热 .

[0063] S403, Magnetic levitation system judgment T 吸气过热 > Whether T0 is true.

[0064] S404, in T 吸气过热 When the value is greater than T0, the magnetic levitation system controls the electronic expansion valve and refrigerant pump to remain closed, so that the opening degree of the electronic expansion valve and the speed of the refrigerant pump are both zero.

[0065] S405, in T 吸气过热 When T0 is less than or equal to 0, the opening degree of the electronic expansion valve controlled by the magnetic levitation system is Y% and the speed of the refrigerant pump is Z.

[0066] S406, Magnetic levitation system judgment T 吸气过热 > Whether T0 is true.

[0067] S407, in T 吸气过热 When T > T0, the magnetic levitation system controls the electronic expansion valve to maintain an opening of Y%, and adjusts the refrigerant pump speed according to the PID control to ensure T 吸气过热 =T obj .

[0068] S408, in T 吸气过热When T0 is less than or equal to 0, the opening degree of the electronic expansion valve controlled by the magnetic levitation system increases by M% every preset time interval, and the speed of the refrigerant pump increases by N every preset time interval.

[0069] S409, Magnetic levitation system judgment T 吸气过热 > Whether T0 is true.

[0070] S410, in T 吸气过热 When T > T0, the magnetic levitation system maintains the opening of the electronic expansion valve at (Y+a*M)%, and adjusts the speed of the refrigerant pump according to the PID control, so that T 吸气过热 =T obj .

[0071] S411, when the opening degree of the electronic expansion valve is the preset maximum opening degree, and T 吸气过热 When the time is ≤T0, the magnetic levitation system will trigger an alarm.

[0072] Where T0 is the preset superheat threshold, Y% is the preset initial opening degree, Z is the preset initial rotational speed, and T obj The target superheat is M%, the preset opening increase is M%, the preset rotational speed increase is N%, and a is a constant.

[0073] The method for controlling a magnetic levitation system provided in this embodiment uses a refrigerant pump to draw a liquid suction line from the evaporator drain port. The superheat of the unit is determined based on the suction pressure and temperature at the compressor suction port. Based on the superheat and a threshold superheat threshold, the speed of the refrigerant pump is controlled or an alarm is triggered. This ensures that the low-temperature, low-pressure refrigerant in the evaporator enters the cold storage tank more effectively, lowering the evaporator liquid level and preventing liquid carryover due to excessively high liquid levels. Simultaneously, based on the superheat and the threshold superheat threshold, the opening of the electronic expansion valve in the first replenishment line is controlled or an alarm is triggered. This prevents the low-pressure, low-temperature refrigerant in the cold storage tank from directly contacting the high-temperature, high-pressure refrigerant from the dryer filter within the heat exchanger, forming a superheated gaseous refrigerant. This superheated gaseous refrigerant mixes with the unsaturated refrigerant at the compressor suction port, ultimately increasing the superheat of the suction port refrigerant and preventing liquid carryover due to insufficient suction superheat. This avoids liquid carryover during compressor intake, prevents liquid refrigerant from entering the intake port and causing impact between the liquid refrigerant and the high-speed rotating impeller, and reduces damage to the compressor.

[0074] Combination Figure 5 As shown, this disclosure provides another method for controlling a magnetic levitation system, including:

[0075] S501, the magnetic levitation system determines the suction pressure P and suction temperature T at the compressor's suction port.

[0076] S502, the magnetic levitation system controls the opening degree of the electronic expansion valve and the speed of the refrigerant pump according to P and T, so as to increase the superheat of the refrigerant in the compressor suction port to avoid liquid carry-in during suction.

[0077] S503, The magnetic levitation system determines the compressor's actual speed V1 and surge speed V1. 喘 .

[0078] S504, the magnetic levitation system is based on V1 and V 喘 Determine the speed deviation ΔV between the surge speed and the actual speed of the compressor.

[0079] S505, Determine whether the condition △V<△V0 holds true for a magnetic levitation system.

[0080] S506, when ΔV < ΔV0, the magnetic levitation system controls the electronic expansion valve to remain closed, so that the opening of the electronic expansion valve is zero.

[0081] S507, when ΔV≥ΔV0, the opening degree of the electronic expansion valve controlled by the magnetic levitation system is Y%.

[0082] S508, Determine whether the condition △V<△V0 holds true for a magnetic levitation system.

[0083] S509, when ΔV < ΔV0, the opening degree of the electronic expansion valve controlled by the magnetic levitation system is maintained at Y%.

[0084] S510, when △V≥△V0, the opening degree of the electronic expansion valve controlled by the magnetic levitation system increases by M every preset time interval.

[0085] S511, Determine whether the magnetic levitation system holds true if ΔV < ΔV0.

[0086] S512, when ΔV < ΔV0, the opening of the electronic expansion valve controlled by the magnetic levitation system is maintained at (Y + a * M)%.

[0087] S513, when the opening of the electronic expansion valve is the preset maximum opening and △V≥△V0, the magnetic levitation system will perform an alarm.

[0088] Where △V0 is the preset speed deviation threshold, Y% is the preset initial opening, M% is the preset opening increase, and a is a constant.

[0089] The method for controlling a magnetic levitation system provided in this disclosure involves a refrigerant pump with a suction line leading from the evaporator drain port. The pump speed is controlled based on the suction pressure and temperature at the compressor suction port, allowing the low-temperature, low-pressure refrigerant in the evaporator to better enter the cold storage tank, thus lowering the evaporator liquid level and preventing liquid carryover due to excessive liquid level. Simultaneously, the opening of the electronic expansion valve in the first replenishment line is controlled based on the suction pressure and temperature at the compressor suction port. The deviation between the surge speed and the actual compressor speed is determined based on the actual and surge speeds of the compressor. The opening of the electronic expansion valve is controlled or an alarm is triggered based on this deviation. This ensures that the low-pressure, low-temperature refrigerant in the cold storage tank does not directly contact the high-temperature, high-pressure refrigerant from the dryer filter within the heat exchanger, forming superheated gaseous refrigerant. This superheated gaseous refrigerant mixes with the unsaturated refrigerant at the compressor suction port, ultimately increasing the superheat of the suction port refrigerant and preventing liquid carryover due to insufficient suction superheat. Simultaneously, increasing the suction pressure at the compressor's inlet and reducing the compression ratio between the cold storage tank and the compressor helps prevent surge. This avoids liquid carryover and surge in the compressor's suction, and prevents the impact of liquid refrigerant entering the suction port with the high-speed rotating impeller, thus reducing damage to the compressor.

[0090] Combination Figure 6 As shown, this disclosure provides an apparatus for controlling a magnetic levitation system, including a processor 100 and a memory 101. Optionally, the apparatus may further include a communication interface 102 and a bus 103. The processor 100, communication interface 102, and memory 101 can communicate with each other via the bus 103. The communication interface 102 can be used for information transmission. The processor 100 can call logical instructions in the memory 101 to execute the method for controlling the magnetic levitation system described in the above embodiment.

[0091] Furthermore, the logic instructions in the aforementioned memory 101 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium.

[0092] The memory 101, as a computer-readable storage medium, can be used to store software programs and computer-executable programs, such as program instructions / modules corresponding to the methods in the embodiments of this disclosure. The processor 100 executes functional applications and data processing by running the program instructions / modules stored in the memory 101, that is, it implements the method for controlling the magnetic levitation system in the above embodiments.

[0093] The memory 101 may include a program storage area and a data storage area. The program storage area may store the operating system and applications required for at least one function; the data storage area may store data created based on the use of the terminal device. Furthermore, the memory 101 may include high-speed random access memory and may also include non-volatile memory.

[0094] This disclosure provides a magnetic levitation system, including a refrigerant circulation loop, a liquid suction line, a liquid return line, a first gas supply line, a second gas supply line, and the aforementioned device for controlling the magnetic levitation system. The refrigerant circulation loop includes a condenser, a dryer filter, a heat exchanger, an evaporator, and a compressor connected in sequence. The liquid suction line includes a cold storage tank and a refrigerant pump connected in sequence, with the refrigerant pump connected in series between the inlet of the cold storage tank and the outlet of the evaporator to draw liquid from the evaporator into the cold storage tank. The liquid return line is connected in series between the first outlet of the cold storage tank and the inlet of the evaporator. The first gas supply line includes an electronic expansion valve, one end of which is connected to the second outlet of the cold storage tank, and the other end is connected to the inlet of the compressor via the heat exchanger. The second gas supply line has one end connected to the outlet of the dryer filter and the other end connected to the inlet of the compressor.

[0095] This disclosure provides a computer-readable storage medium storing computer-executable instructions configured to perform the above-described method for controlling a magnetic levitation system.

[0096] This disclosure provides a computer program product, which includes a computer program stored on a computer-readable storage medium. The computer program includes program instructions that, when executed by a computer, cause the computer to perform the above-described method for controlling a magnetic levitation system.

[0097] The aforementioned computer-readable storage medium may be a transient computer-readable storage medium or a non-transitory computer-readable storage medium.

[0098] The technical solutions of this disclosure can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes one or more instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in this disclosure. The aforementioned storage medium can be a non-transitory storage medium, including: a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk, and other media capable of storing program code; it can also be a transient storage medium.

[0099] The foregoing description and accompanying drawings fully illustrate embodiments of this disclosure to enable those skilled in the art to practice them. Other embodiments may include structural, logical, electrical, procedural, and other changes. The embodiments represent only possible variations. Individual components and functions are optional unless explicitly required, and the order of operation may vary. Parts and features of some embodiments may be included in or replace parts and features of other embodiments. Moreover, the terminology used in this application is for describing embodiments only and is not intended to limit the claims. As used in the description of embodiments and claims, the singular forms “a,” “an,” and “the” are intended to equally include the plural forms unless the context clearly indicates otherwise. Similarly, the term “and / or” as used in this application means including one or more of the associated listed items and all possible combinations thereof. Additionally, when used in this application, the term "comprise" and its variations "comprises" and / or "comprising" refer to the presence of stated features, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof. Without further limitations, an element defined by the phrase "comprises a..." does not exclude the presence of other identical elements in the process, method, or apparatus that includes said element. In this document, each embodiment may focus on the differences from other embodiments, and similar or identical parts between embodiments can be referred to mutually. For methods, products, etc., disclosed in the embodiments, if they correspond to the method section disclosed in the embodiments, the relevant parts can be referred to the description of the method section.

[0100] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the embodiments of this disclosure. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0101] The methods and products (including but not limited to devices and equipment) disclosed in the embodiments herein can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For instance, the division of units may be merely a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the shown or discussed units may be through some interfaces, and the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the units may be selected to implement this embodiment according to actual needs. Furthermore, the functional units in the embodiments of this disclosure may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0102] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to embodiments of this disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. In some alternative implementations, the functions marked in the blocks may occur in a different order than that shown in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. In the descriptions corresponding to the flowcharts and block diagrams in the accompanying drawings, the operations or steps corresponding to different blocks may also occur in a different order than disclosed in the description, and sometimes there is no specific order between different operations or steps. For example, two consecutive operations or steps may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. Each block in a block diagram and / or flowchart, and combinations of blocks in a block diagram and / or flowchart, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

Claims

1. A method for controlling a magnetic levitation system, characterized in that, The magnetic levitation system includes: a refrigerant circulation loop, comprising a condenser, a dryer filter, a plate heat exchanger, an evaporator, and a compressor connected in sequence; a liquid suction line, comprising a cold storage tank and a refrigerant pump connected in sequence, the refrigerant pump being connected in series between the liquid inlet of the cold storage tank and the liquid outlet of the evaporator, for drawing liquid from the evaporator into the cold storage tank; a liquid return line, connected in series between the first liquid outlet of the cold storage tank and the liquid inlet of the evaporator; a first gas supply line, comprising an electronic expansion valve, one end of which is connected to the second liquid outlet of the cold storage tank, and the other end of which is connected to the air inlet of the compressor via the plate heat exchanger; and a second gas supply line, one end of which is connected to the outlet of the dryer filter, and the other end of which is connected to the air inlet of the compressor; the method includes: Determine the suction pressure at the compressor inlet. P Intake temperature T ; according to P , T Control the opening degree of the electronic expansion valve and the speed of the refrigerant pump to increase the superheat of the refrigerant in the compressor suction port to avoid liquid carryover in the suction. Among them, according to P , T Determine the unit superheat T 吸气过热 ;exist T 吸气过热 > T With a value of 0, the electronic expansion valve and refrigerant pump are kept closed, so that the opening degree of the electronic expansion valve and the speed of the refrigerant pump are both zero. exist T 吸气过热 ≤ T With a value of 0, the opening degree of the electronic expansion valve is controlled to be Y% and the speed of the refrigerant pump is Z; according to T 吸气过热 The first time, the opening degree of the electronic expansion valve and the speed of the refrigerant pump were recontrolled, so that... T 吸气过热 = T obj ; T 0 represents the preset superheat threshold, Y% represents the preset initial opening degree, and Z represents the preset initial rotational speed. T obj The target is overheating.

2. The method according to claim 1, characterized in that, According to T 吸气过热 The first time, the opening degree of the electronic expansion valve and the speed of the refrigerant pump were recontrolled, so that... T 吸气过热 = T obj , include: exist T 吸气过热 > T With a value of 0, the opening of the electronic expansion valve is maintained at Y%, and the speed of the refrigerant pump is adjusted according to the PID control to ensure that... T 吸气过热 = T obj ; exist T 吸气过热 ≤ T When the value is 0, the opening degree of the electronic expansion valve is increased by M% every preset time interval, and the speed of the refrigerant pump is increased by N every preset time interval; according to T 吸气过热 The second time, the opening degree of the electronic expansion valve and the speed of the refrigerant pump were recontrolled, so that... T 吸气过热 = T obj ; Where M% is the preset opening increase and N is the preset speed increase.

3. The method according to claim 2, characterized in that, According to T 吸气过热 The second time, the opening degree of the electronic expansion valve and the speed of the refrigerant pump were recontrolled, so that... T 吸气过热 = T obj , include: exist T 吸气过热 > T With a value of 0, the opening of the electronic expansion valve is maintained at (Y+a*M)%, and the speed of the refrigerant pump is adjusted according to the PID control, so that... T 吸气过热 = T obj ; exist T 吸气过热 ≤ T If the value is 0, an alarm will be triggered. Where a is a constant.

4. The method according to any one of claims 1 to 3, characterized in that, Also includes: Determine the actual speed of the compressor V 1 and surge speed V 喘 ; according to V 1 and V 喘 Control the opening of the electronic expansion valve to increase the suction pressure at the compressor inlet to avoid surge.

5. The method according to claim 4, characterized in that, According to V 1 and V 喘 Controlling the opening degree of the electronic expansion valve includes: according to V 1 and V 喘 Determine the speed deviation Δ between the surge speed and the actual compressor speed. V ; According to △ V Control the opening degree of the electronic expansion valve.

6. The method according to claim 5, characterized in that, According to △ V Controlling the opening degree of the electronic expansion valve includes: In △ V <△ V When the value is 0, the electronic expansion valve is kept closed, so that the opening degree of the electronic expansion valve is zero. In △ V ≥△ V When the value is 0, the opening degree of the electronic expansion valve is controlled to be Y%; according to △ V The opening degree of the electronic expansion valve was controlled again for the first time; Among them, △ V 0 represents the preset speed deviation threshold, and Y% represents the preset initial opening degree.

7. A device for controlling a magnetic levitation system, comprising a processor and a memory storing program instructions, characterized in that, The processor is configured to, when executing the program instructions, perform the method for controlling a magnetic levitation system as described in any one of claims 1 to 6.

8. A magnetic levitation system, characterized in that, include: The refrigerant circulation loop includes a condenser, a dryer filter, a plate heat exchanger, an evaporator, and a compressor connected in sequence. The liquid suction line includes a cold storage tank and a refrigerant pump connected in sequence. The refrigerant pump is connected in series between the liquid inlet of the cold storage tank and the liquid outlet of the evaporator to draw liquid from the evaporator into the cold storage tank. The return line is connected in series between the first liquid outlet of the storage tank and the liquid inlet of the evaporator. The first gas supply line includes an electronic expansion valve. One end of the electronic expansion valve is connected to the second liquid outlet of the cold storage tank, and the other end is connected to the air inlet of the compressor through a plate heat exchanger. The second air supply line connects at one end to the outlet of the dryer filter and at the other end to the air inlet of the compressor; and, The device for controlling a magnetic levitation system as described in claim 7.

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