CN111120411B

CN111120411B - Cooling control device, magnetic suspension system and cooling control method thereof

Info

Publication number: CN111120411B
Application number: CN201911328593.3A
Authority: CN
Inventors: 赵科杰; 孙建东; 龙皓明; 胡叨福
Original assignee: Gree Electric Appliances Inc of Zhuhai
Current assignee: Gree Electric Appliances Inc of Zhuhai
Priority date: 2019-12-20
Filing date: 2019-12-20
Publication date: 2020-11-24
Anticipated expiration: 2039-12-20
Also published as: CN111120411A

Abstract

The invention discloses a cooling control device, a magnetic suspension system and a cooling control method thereof, wherein the device comprises: the acquisition unit is used for acquiring a displacement signal of a motor rotor of the magnetic suspension system and acquiring a liquid level signal of a refrigerant in a cavity of the magnetic suspension compressor; a determination unit for determining whether the displacement signal is greater than or equal to a set reference displacement; if the displacement signal is greater than or equal to the set reference displacement, further determining that the magnetic suspension compressor is greater than or equal to the set reference liquid level after the set time length; if the liquid level signal is greater than or equal to the set reference liquid level, generating a refrigerant reduction signal; and the control unit is used for controlling the refrigerant input quantity of the cavity of the magnetic suspension compressor to be reduced and/or controlling the refrigerant output quantity of the cavity of the magnetic suspension compressor to be increased according to the refrigerant reducing signal. According to the scheme, the problem that the accumulated liquid of the cavity of the compressor can influence the operation stability of the magnetic suspension compressor can be solved, and the effect of ensuring the operation stability of the magnetic suspension compressor is achieved.

Description

Cooling control device, magnetic suspension system and cooling control method thereof

Technical Field

The invention belongs to the technical field of magnetic suspension, and particularly relates to a cooling control device, a magnetic suspension system and a cooling control method thereof, in particular to a magnetic suspension compressor cooling control device, a magnetic suspension system and a cooling control method thereof.

Background

In the power electronic industry, the good cooling of the motor stator can ensure the safe and efficient operation of the motor. In some compressors, a motor winding is mainly cooled, and a refrigerant cooling mode is adopted, so that the cooling requirement of the motor winding can be met under the normal condition; in the magnetic suspension compressor, besides the motor winding, the magnetic bearing needs to be cooled, and the amount of refrigerant and a cooling channel are different from those of the cavity of the common compressor.

Different from a conventional centrifugal compressor, the stable suspension precision of a rotor of a magnetic suspension centrifugal compressor is a premise for normal operation of the compressor. When a refrigerant is used for cooling a motor winding and a magnetic bearing, the problem of liquid accumulation in a cavity of a compressor occasionally occurs, the liquid level of the liquid accumulation submerges a magnetic bearing rotor under severe conditions, interference is caused to stable suspension of the rotor, and particularly, the liquid accumulation possibly causes the magnetic suspension rotor to rotate abnormally in the starting and frequency increasing process and the high-speed rotation process of the compressor.

The above is only for the purpose of assisting understanding of the technical aspects of the present invention, and does not represent an admission that the above is prior art.

Disclosure of Invention

The invention aims to provide a cooling control device, a magnetic suspension system and a cooling control method thereof to solve the problem that when a refrigerant is used for cooling a magnetic suspension centrifugal compressor, the running stability of the magnetic suspension compressor is affected by accumulated liquid in a cavity of the compressor, so that the effect of ensuring the running stability of the magnetic suspension compressor is achieved.

The present invention provides a cooling control device, including: the device comprises an acquisition unit, a determination unit and a control unit; the system comprises an acquisition unit, a control unit and a control unit, wherein the acquisition unit is used for acquiring a displacement signal of a motor rotor of a magnetic suspension system and acquiring a liquid level signal of a refrigerant in a magnetic suspension compressor cavity of the magnetic suspension system; a determination unit for determining whether a displacement signal of the motor rotor is greater than or equal to a set reference displacement; if the displacement signal of the motor rotor is greater than or equal to the set reference displacement, further determining whether the liquid level signal of the refrigerant in the cavity of the magnetic suspension compressor is greater than or equal to the set reference liquid level after the set time length; if the liquid level signal of the refrigerant in the cavity of the magnetic suspension compressor is greater than or equal to the set reference liquid level, generating a refrigerant reduction signal for reducing the amount of the refrigerant in the cavity of the magnetic suspension compressor; and the control unit is used for controlling the refrigerant input quantity of the cavity of the magnetic suspension compressor to be reduced and/or controlling the refrigerant output quantity of the cavity of the magnetic suspension compressor to be increased according to the refrigerant reducing signal.

Optionally, the method further comprises: the acquisition unit is also used for acquiring temperature signals of a motor winding of the magnetic suspension system and/or a bearing of the magnetic suspension system; the determining unit is also used for determining whether the liquid level signal of the refrigerant in the cavity of the magnetic suspension compressor is greater than or equal to a set reference liquid level; if the liquid level signal of the refrigerant in the cavity of the magnetic suspension compressor is less than the set reference liquid level, further determining whether the temperature signal of the motor winding and/or the bearing is greater than or equal to the set reference temperature; if the temperature signal of the motor winding and/or the bearing is greater than or equal to the set reference temperature, generating a refrigerant increasing signal for increasing the refrigerant quantity in the cavity of the magnetic suspension compressor; and the control unit is also used for controlling the refrigerant input quantity of the cavity of the magnetic suspension compressor to be increased and/or controlling the refrigerant output quantity of the cavity of the magnetic suspension compressor to be reduced according to the refrigerant increasing signal.

Optionally, the controlling of the decrease of the refrigerant input amount of the magnetic suspension compressor cavity and/or the increase of the refrigerant output amount of the magnetic suspension compressor cavity includes: controlling the opening degree of a refrigerant input valve of the magnetic suspension compressor cavity to be reduced and/or controlling the opening degree of a refrigerant output valve of the magnetic suspension compressor cavity to be increased; or, controlling the refrigerant input quantity of the magnetic suspension compressor cavity to increase and/or controlling the refrigerant output quantity of the magnetic suspension compressor cavity to decrease comprises: and controlling the opening of a refrigerant input valve of the cavity of the magnetic suspension compressor to increase and/or controlling the opening of a refrigerant output valve of the cavity of the magnetic suspension compressor to decrease.

Optionally, the method for controlling the opening degree of the refrigerant input valve of the magnetic suspension compressor cavity to decrease, or controlling the opening degree of the refrigerant output valve of the magnetic suspension compressor cavity to increase, or controlling the opening degree of the refrigerant input valve of the magnetic suspension compressor cavity to increase, or controlling the opening degree of the refrigerant output valve of the magnetic suspension compressor cavity to decrease includes: a step control mode, a linear control mode or a curve control mode.

Optionally, the method further comprises: the determining unit is also used for determining whether the displacement signal of the motor rotor is greater than or equal to a set reference displacement; if the displacement signal of the motor rotor is smaller than the set reference displacement, generating a first refrigerant maintaining signal for maintaining the refrigerant quantity in the cavity of the magnetic suspension compressor; or if the temperature signal of the motor winding and/or the bearing is less than the set reference temperature, generating a second refrigerant maintaining signal for maintaining the refrigerant quantity in the cavity of the magnetic suspension compressor; and the control unit is also used for controlling the magnetic suspension system to maintain the current running state according to the first refrigerant maintaining signal or the second refrigerant maintaining signal.

In accordance with the above apparatus, a magnetic levitation system is provided in another aspect of the present invention, including: the cooling control device described above.

In accordance with the magnetic levitation system, another aspect of the present invention provides a cooling control method for a magnetic levitation system, including: acquiring a displacement signal of a motor rotor of a magnetic suspension system, and acquiring a liquid level signal of a refrigerant in a magnetic suspension compressor cavity of the magnetic suspension system;

determining whether a displacement signal of the motor rotor is greater than or equal to a set reference displacement; if the displacement signal of the motor rotor is greater than or equal to the set reference displacement, further determining whether the liquid level signal of the refrigerant in the cavity of the magnetic suspension compressor is greater than or equal to the set reference liquid level after the set time length; if the liquid level signal of the refrigerant in the cavity of the magnetic suspension compressor is greater than or equal to the set reference liquid level, generating a refrigerant reduction signal for reducing the amount of the refrigerant in the cavity of the magnetic suspension compressor; and controlling the input quantity of the refrigerant of the cavity of the magnetic suspension compressor to be reduced and/or controlling the output quantity of the refrigerant of the cavity of the magnetic suspension compressor to be increased according to the refrigerant reducing signal.

Optionally, the method further comprises: collecting temperature signals of a motor winding of the magnetic suspension system and/or a bearing of the magnetic suspension system; determining whether a liquid level signal of a refrigerant in a cavity of the magnetic suspension compressor is greater than or equal to a set reference liquid level; if the liquid level signal of the refrigerant in the cavity of the magnetic suspension compressor is less than the set reference liquid level, further determining whether the temperature signal of the motor winding and/or the bearing is greater than or equal to the set reference temperature; if the temperature signal of the motor winding and/or the bearing is greater than or equal to the set reference temperature, generating a refrigerant increasing signal for increasing the refrigerant quantity in the cavity of the magnetic suspension compressor; and controlling the refrigerant input quantity of the cavity of the magnetic suspension compressor to increase and/or controlling the refrigerant output quantity of the cavity of the magnetic suspension compressor to decrease according to the refrigerant increasing signal.

Optionally, the method further comprises: if the displacement signal of the motor rotor is smaller than the set reference displacement, generating a first refrigerant maintaining signal for maintaining the refrigerant quantity in the cavity of the magnetic suspension compressor; or if the temperature signal of the motor winding and/or the bearing is less than the set reference temperature, generating a second refrigerant maintaining signal for maintaining the refrigerant quantity in the cavity of the magnetic suspension compressor; and controlling the magnetic suspension system to maintain the current running state according to the first refrigerant maintaining signal or the second refrigerant maintaining signal.

According to the scheme, the opening of the cooling air inlet valve and the opening of the cooling air outlet ball valve of the cavity of the magnetic suspension compressor are regulated and controlled according to the liquid level height of the refrigerant in the cavity of the magnetic suspension compressor, so that the operation stability of the magnetic suspension compressor can be ensured, and the cooling effect on the motor winding and the magnetic bearing can be taken into consideration.

Furthermore, according to the scheme of the invention, the liquid level sensor is arranged in the cavity of the compressor, and the opening of the cooling air inlet valve and the opening of the cooling air outlet ball valve are regulated and controlled according to the liquid level height, so that the temperature of the motor winding and the temperature of the magnetic bearing are controllable, and the effects of considering the operation stability of the magnetic suspension compressor and cooling the motor winding and the magnetic bearing are achieved.

Furthermore, according to the scheme provided by the invention, the liquid level sensor is arranged, the liquid refrigerant amount in the compressor cavity is monitored in real time, the opening of the cooling air inlet valve and the opening of the cooling air return ball valve are regulated and controlled, the problem of liquid accumulation in the compressor cavity can be effectively avoided, the suspension stability of the rotor is ensured, and the displacement precision of the magnetic suspension rotor is improved.

Therefore, according to the scheme of the invention, the opening degree of the cooling air inlet valve and the opening degree of the cooling air outlet ball valve of the magnetic suspension compressor cavity are regulated and controlled according to the liquid level height of the refrigerant in the magnetic suspension compressor cavity, so that the problem that the running stability of the magnetic suspension compressor is influenced by accumulated liquid in the compressor cavity when the magnetic suspension centrifugal compressor is cooled by using the refrigerant is solved, and the effect of ensuring the running stability of the magnetic suspension compressor is achieved.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

The technical solution of the present invention is further described in detail by the accompanying drawings and embodiments.

Drawings

FIG. 1 is a schematic structural diagram of an embodiment of a cooling control apparatus according to the present invention;

FIG. 2 is a schematic diagram of cooling and detecting amount of a compressor cavity of a magnetic levitation unit according to an embodiment of the magnetic levitation system of the present invention;

FIG. 3 is a schematic view of a reference level versus rotor position for an embodiment of the magnetic levitation system of the present invention;

FIG. 4 is a logic control schematic of the magnetic levitation compressor cooling control of one embodiment of the magnetic levitation system of the present invention;

FIG. 5 is a schematic flow chart of the cooling control of the magnetically levitated compressor of an embodiment of the magnetically levitated system of the present invention;

fig. 6 to 11 are schematic diagrams illustrating a control manner of cooling control of a magnetic levitation compressor according to an embodiment of a magnetic levitation system of the present invention, wherein fig. 6 is a schematic diagram illustrating a step control manner of increasing the valve opening, fig. 7 is a schematic diagram illustrating a linear control manner of decreasing the valve opening, fig. 8 is a schematic diagram illustrating a step control manner of increasing the valve opening, fig. 9 is a schematic diagram illustrating a linear control manner of decreasing the valve opening, fig. 10 is a schematic diagram illustrating a nonlinear control manner of increasing the valve opening, and fig. 11 is a schematic diagram illustrating a nonlinear control manner of decreasing the valve opening;

FIG. 12 is a schematic flow chart diagram illustrating an embodiment of a cooling control method of the present invention;

FIG. 13 is a schematic flow chart diagram illustrating one embodiment of over-temperature control in cooling control in the method of the present invention;

FIG. 14 is a flow chart illustrating an embodiment of shutdown control following cooling control in the method of the present invention.

The reference numbers in the embodiments of the present invention are as follows, in combination with the accompanying drawings:

1-a liquid level sensor; 2-first control valve (e.g. cooling inlet valve of magnetic suspension compressor cavity); 3-a second control valve (such as a cooling air outlet ball valve of a magnetic suspension compressor cavity); 4-a throttling device; 5-front radial magnetic bearing; 6-rear radial magnetic bearing; 7-motor rotor.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the specific embodiments of the present invention and the accompanying drawings. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

According to an embodiment of the present invention, there is provided a cooling control apparatus. Referring to fig. 1, a schematic diagram of an embodiment of the apparatus of the present invention is shown. The cooling control apparatus may include: the device comprises an acquisition unit, a determination unit and a control unit.

For example: a determination unit, which may include: displacement comparison unit and liquid level comparison unit. For the displacement comparison unit, the acquisition unit may be a displacement sensor. For the level comparison unit, the acquisition unit may be a level sensor. The displacement comparing unit may be a displacement comparing circuit. The liquid level comparison unit can be a liquid level comparison circuit. The control unit may be a controller.

In an alternative example, the acquisition unit may be configured to acquire a displacement signal of a motor rotor of the magnetic levitation system, and acquire a liquid level signal of a refrigerant in a cavity of a magnetic levitation compressor of the magnetic levitation system.

For example: and acquiring a displacement signal of a motor rotor of the magnetic suspension system through a displacement sensor. Liquid level signals of refrigerants in the magnetic suspension compressor cavity of the magnetic suspension system are collected through a liquid level sensor arranged in the magnetic suspension compressor cavity.

In an alternative example, the determination unit may be configured to determine whether a displacement signal of the motor rotor is greater than or equal to a set reference displacement; if the displacement signal of the motor rotor is greater than or equal to the set reference displacement, keeping the state that the displacement signal of the motor rotor is greater than or equal to the set reference displacement for a set time length, and further determining whether the liquid level signal of the refrigerant in the cavity of the magnetic suspension compressor is greater than or equal to the set reference liquid level after the set time length; and if the liquid level signal of the refrigerant in the cavity of the magnetic suspension compressor is greater than or equal to the set reference liquid level, determining that the accumulated liquid of the refrigerant in the cavity of the magnetic suspension compressor appears, and generating a refrigerant reduction signal which can be used for reducing the refrigerant quantity in the cavity of the magnetic suspension compressor.

For example: a displacement comparison circuit for comparing the displacement signal V_disAnd a reference displacement voltage V_refComparing, when the displacement signal V is_disGreater than or equal to the reference displacement voltage V_refThe comparator output is 1. Further, for example: a liquid level signal comparison circuit for comparing the real-time liquid level signal L_disAnd a reference liquid level L_refComparing the two liquid level signals when the real-time liquid level signal L is detected_disGreater than or equal to the reference level L_refThe comparator output is 1.

In an optional example, the control unit may be configured to control, according to the refrigerant reduction signal, a decrease in refrigerant input amount of the cavity of the magnetic suspension compressor and/or an increase in refrigerant output amount of the cavity of the magnetic suspension compressor, so that a liquid level of the refrigerant is lower than a suspension position of the magnetic bearing rotor, which may effectively avoid a problem of liquid accumulation in the cavity of the compressor, and the magnetic suspension rotor is located in a gas environment, thereby ensuring suspension stability of the rotor.

For example: the opening degree of the first control valve 2 (such as a cooling air inlet valve of the magnetic suspension compressor cavity) is controlled to be reduced, and/or the opening degree of the second control valve 3 (such as a cooling air outlet ball valve of the magnetic suspension compressor cavity) is controlled to be increased. Of course, the air inlet valve and the air outlet valve can be optionally adjusted under the condition that the air inlet valve for small cooling needs to be closed and the air outlet valve for large cooling needs to be opened; for example, the air outlet ball valve can be independently adjusted without adjusting the air inlet valve; or the air inlet valve is independently adjusted without adjusting the air outlet ball valve. In addition, under the condition that the operations of closing the small cooling air inlet valve and opening the large air outlet valve are required, the air inlet valve and the air outlet ball valve are designed to be manually adjusted and also automatically adjusted.

For example: the displacement accuracy can be used as a condition for adjusting the cooling valve, and when the accuracy is not in a reasonable range, further judgment and control are carried out. If the liquid level sensor can be installed in the cavity of the compressor, the liquid level of the refrigerant in the cavity can be monitored in real time, and the liquid level signal is received and the opening of the cooling valve is regulated and controlled through the MCU. If the liquid level sensor is arranged in the cavity of the compressor, the opening degree of the cooling air inlet valve and the opening degree of the cooling air outlet ball valve can be regulated and controlled according to the liquid level height, so that the opening degree of the cooling valve can be automatically regulated and controlled in real time through closed-loop control, the temperature of the motor winding and the temperature of the magnetic bearing can be controlled, and the effects of considering the operation stability of the magnetic suspension compressor and cooling the motor winding and the magnetic bearing are achieved.

For example: through installation level sensor, liquid refrigerant volume in the real-time supervision compressor cavity, regulation and control cooling air inlet valve aperture and cooling return air ball valve aperture even the problem of cavity hydrops appears, also make refrigerant liquid level height be less than magnetic bearing rotor suspension position, make the rotor be in among the gaseous environment. Like this, can effectively avoid the problem of compressor cavity hydrops, make the magnetic suspension rotor be in gaseous environment, ensure the stability of rotor suspension, improve the displacement precision.

From this, through when the displacement precision is not in reasonable within range, through monitoring liquid refrigerant volume in the compressor cavity and regulation and control cooling air inlet valve aperture and cooling return air ball valve aperture, can make refrigerant liquid level highly be less than magnetic bearing rotor suspension position, make electric motor rotor be in gaseous environment to effectively avoid the problem of compressor cavity hydrops, ensure the stability of electric motor rotor suspension, thereby promote magnetic suspension system's operating stability.

Optionally, the controlling unit controls the refrigerant input amount of the magnetic suspension compressor cavity to decrease and/or controls the refrigerant output amount of the magnetic suspension compressor cavity to increase, and the controlling unit may include: and controlling the opening degree of a refrigerant input valve of the cavity of the magnetic suspension compressor to be reduced and/or controlling the opening degree of a refrigerant output valve of the cavity of the magnetic suspension compressor to be increased.

For example: starting up the machine set, and measuring the displacement precision V of the rotor in real time_disCollecting and setting reference displacement precision V_refComparing, when the output value is 1, the current displacement precision is poor, and the time delay t can be carried out in software_refAnd the displacement comparison circuit always outputs 1 in the delay stage, and the cooling valve adjusting function module is started. And when the liquid level comparison circuit outputs 1, the execution valve adjusting function module indicates that the cavity accumulated liquid is serious, and the operations of closing the small cooling air inlet valve and opening the large air outlet valve are required, and then whether the machine is stopped is judged.

Therefore, the control of reducing the refrigerant quantity in the cavity of the magnetic suspension compressor is realized by controlling the opening degrees of the refrigerant input valve and the refrigerant output valve, the control mode is simple, and the control precision and flexibility can be ensured.

In an alternative embodiment, the method may further include: and (3) an over-temperature control process in cooling control.

In an alternative example, the detection unit can also be used to detect a temperature signal of a motor winding of the magnetic levitation system and/or a bearing of the magnetic levitation system. For example: and collecting the temperature of the motor winding and the temperature of the bearing.

In an optional example, the determining unit may be further configured to determine whether a liquid level signal of a refrigerant in the cavity of the magnetic levitation compressor is greater than or equal to a set reference liquid level; if the liquid level signal of the refrigerant in the cavity of the magnetic suspension compressor is less than the set reference liquid level, further determining whether the temperature signal of the motor winding and/or the bearing is greater than or equal to the set reference temperature; and if the temperature signal of the motor winding and/or the bearing is greater than or equal to the set reference temperature, determining that the temperature of the motor winding and/or the bearing is too high, and generating a refrigerant increasing signal which can be used for increasing the refrigerant quantity in the cavity of the magnetic suspension compressor so as to control the temperature of the motor winding and the temperature of the magnetic bearing.

For example: a liquid level signal comparison circuit for comparing the real-time liquid level signal L_disAnd a reference liquid level L_refComparing the two liquid level signals when the real-time liquid level signal L is detected_disLess than reference level L_refWhen the output is 0, the signal is inverted and compared with the temperature to perform an AND operation. The temperature signal comparison circuit can collect the temperature of the motor winding and the temperature of the bearing to obtain a real-time temperature signal T of the temperature of the motor winding and the temperature of the bearing_dis(ii) a Will real-time temperature signal T_disWith a reference temperature T_refComparing the real-time temperature signal T_disGreater than or equal to the reference temperature T_refThe comparator output is 1.

In an optional example, the control unit may be further configured to control an input amount of the refrigerant of the magnetic suspension compressor cavity to be increased and/or control an output amount of the refrigerant of the magnetic suspension compressor cavity to be decreased according to the refrigerant increase signal. For example: the opening of the first control valve 2 (such as a cooling air inlet valve of the magnetic suspension compressor cavity) is controlled to be increased, and/or the opening of the second control valve 3 (such as a cooling air outlet ball valve of the magnetic suspension compressor cavity) is controlled to be decreased. Of course, the inlet valve and the outlet valve can be optionally adjusted under the condition that the large cooling inlet valve and the small cooling outlet valve need to be opened; for example, the air outlet ball valve can be independently adjusted without adjusting the air inlet valve; or the air inlet valve is independently adjusted without adjusting the air outlet ball valve. In addition, under the condition that the large cooling air inlet valve needs to be opened and the small air outlet valve needs to be closed, the air inlet valve and the air outlet ball valve are designed to be manually adjusted and also can be automatically adjusted.

For example: the displacement accuracy can be used as a condition for adjusting the cooling valve, and when the accuracy is not in a reasonable range, further judgment and control are carried out. For example, the opening degree of the cooling valve can be regulated and controlled through the temperature of the motor winding and the temperature of the magnetic bearing, so that the temperature of the motor winding and the temperature of the magnetic bearing can be controlled.

For example: the controller can perform signal processing by sampling bearing displacement signals, liquid level signals and temperature signals, output control signals, control bearing current to enable the bearing to be stably suspended, and control the opening degree of the valve to adjust the refrigerant inlet and outlet amount.

Therefore, when the displacement precision of the bearing of the magnetic suspension system is not in a reasonable range and the liquid level signal of the refrigerant in the cavity of the magnetic suspension compressor is smaller than a set reference liquid level, the opening degree of the cooling valve can be regulated and controlled through the temperature of the motor winding and/or the temperature of the magnetic bearing, so that the temperature of the motor winding and the temperature of the magnetic bearing are controllable, closed-loop control is realized, and the operation stability of the magnetic suspension system is improved.

Optionally, the controlling unit controls an increase of refrigerant input amount of the magnetic suspension compressor cavity and/or controls a decrease of refrigerant output amount of the magnetic suspension compressor cavity, and may include: and controlling the opening of a refrigerant input valve of the cavity of the magnetic suspension compressor to increase and/or controlling the opening of a refrigerant output valve of the cavity of the magnetic suspension compressor to decrease.

For example: if the valve regulation function module is executed, when the output of the liquid level comparison circuit is 0, the output 0 signal is inverted and is subjected to AND operation with the output of the temperature comparison circuit, when the output result is 1, the situation that the temperature of a winding or a bearing is too high, the operation of opening a large cooling air inlet valve and closing a small air outlet valve is required is indicated, and then whether the machine is stopped or not is judged.

Therefore, the increase of the refrigerant quantity in the cavity of the magnetic suspension compressor is controlled by controlling the opening degrees of the refrigerant input valve and the refrigerant output valve, the control mode is simple, and the control precision and flexibility can be ensured.

More optionally, the controlling unit may control the opening degree of the refrigerant input valve of the magnetic suspension compressor cavity to decrease, or control the opening degree of the refrigerant output valve of the magnetic suspension compressor cavity to increase, or control the opening degree of the refrigerant input valve of the magnetic suspension compressor cavity to increase, or control the opening degree of the refrigerant output valve of the magnetic suspension compressor cavity to decrease, and the controlling unit may include: a step control mode, a linear control mode or a curve control mode.

For example: the control mode of valve regulation can be step control, linear control or other nonlinear control modes.

Therefore, the control of the opening degree of the refrigerant input valve and/or the opening degree of the refrigerant output valve is realized through various modes, the control mode is flexible, and the control device can be applied to the control of occasions with various control requirements.

In an alternative embodiment, the method may further include: a process of shutdown control after the cooling control.

In an optional example, the determining unit may be further configured to determine whether the displacement signal of the motor rotor is greater than or equal to a set reference displacement; if the displacement signal of the motor rotor is smaller than the set reference displacement, determining that no accumulated liquid exists in the refrigerant in the cavity of the magnetic suspension compressor, and generating a first refrigerant holding signal which can be used for holding the amount of the refrigerant in the cavity of the magnetic suspension compressor so as to control the magnetic suspension system to maintain the current running state; or if the temperature signal of the motor winding and/or the bearing is less than the set reference temperature, determining that the temperature of the motor winding and/or the bearing is not high, and generating a second refrigerant maintaining signal which can be used for maintaining the refrigerant quantity in the cavity of the magnetic suspension compressor so as to control the magnetic suspension system to maintain the current operation state.

In an optional example, the control unit may be further configured to control the magnetic levitation system to maintain the current operation state according to the first refrigerant retaining signal or the second refrigerant retaining signal.

For example: starting up the machine set, and measuring the displacement precision V of the rotor in real time_disCollecting and setting reference displacement precision V_refAnd comparing, when the output value is 0, the displacement precision is good, and the unit can normally keep running, namely, if the displacement signal of the motor rotor is smaller than the set reference displacement, the magnetic suspension system is controlled to normally run. Such as: a displacement comparison circuit for comparing the displacement signal V_disAnd a reference displacement voltage V_refComparing, when the displacement signal V is_disLess than a reference displacement voltage V_refThe comparator output is 0.

For another example: and when the liquid level comparison circuit outputs 0, the execution valve adjusting function module shows that no accumulated liquid exists in the cavity or the accumulated liquid does not contact with the rotor, and the action of the air inlet and outlet valve is not needed. Namely, if the temperature signal of the motor winding and/or the bearing is less than the set reference temperature, the magnetic suspension system is controlled to keep normal operation. Such as: the temperature signal comparison circuit can collect the temperature of the motor winding and the temperature of the bearing to obtain a real-time temperature signal T of the temperature of the motor winding and the temperature of the bearing_dis(ii) a Will real-time temperature signal T_disWith a reference temperature T_refComparing the real-time temperature signal T_disLess than a reference temperature T_refThe comparator output is 0. For another example: and when the output result is 0, the temperature of the motor winding and the magnetic bearing is normal, and the unit can continue to operate normally.

Certainly, after the cooling control, for example, after the control unit controls the refrigerant input amount of the magnetic suspension compressor cavity to increase and/or controls the refrigerant output amount of the magnetic suspension compressor cavity to decrease, or after the control unit controls the magnetic suspension system to maintain the current operation state, if the control unit receives a stop signal, the control unit controls the magnetic suspension system to stop, and then the cooling control process can be performed again after the unit is started again. If the controller commands shutdown, the shutdown action is executedIf not, returning to the real-time rotor displacement precision V after the unit is started_disCollecting and setting reference displacement precision V_refAnd (5) comparing.

Therefore, after or in the cooling control process, if the shutdown signal is received, the magnetic suspension system can be controlled to be reliably stopped, and the cooling control is carried out again after the starting, so that the cooling control can be reliably and automatically carried out in the normal operation process.

Through a large number of tests, the technical scheme of the invention regulates and controls the opening of the cooling air inlet valve and the opening of the cooling air outlet ball valve of the cavity of the magnetic suspension compressor according to the liquid level height of the refrigerant in the cavity of the magnetic suspension compressor, can ensure the operation stability of the magnetic suspension compressor, and can also take account of the cooling effect of the motor winding and the magnetic bearing.

According to an embodiment of the invention, a magnetic levitation system corresponding to the cooling control apparatus is also provided. The magnetic levitation system may include: the cooling control device described above.

In an optional embodiment, the scheme of the invention provides a magnetic suspension compressor cooling control system, which can regulate and control the opening degree of a cooling air inlet valve and the opening degree of a cooling air outlet ball valve according to the liquid level height by installing a liquid level sensor in a compressor cavity, so that the opening degree of the cooling valve can be automatically regulated and controlled in real time through closed-loop control, the temperature of a motor winding and the temperature of a magnetic bearing can be controlled, and the effects of considering the operation stability of the magnetic suspension compressor and cooling the motor winding and the magnetic bearing are achieved.

The magnetic suspension compressor cavity is cooled by a refrigerant, and the opening degrees of a cooling air inlet valve and an air return ball valve can be adjusted manually. Along with the difference of the motor frequency, the heat generated by the motor winding is also different; the magnetic bearing current fluctuates or continues to generate large currents, which also generate different amounts of heat. Although the fixed opening of the cooling valve can play a role in cooling the motor winding and the magnetic bearing, the problem of insufficient cooling or excessive cooling to form effusion of a compressor cavity exists at the same time.

And through installation level sensor, the liquid refrigerant volume in real-time supervision compressor cavity, regulation and control cooling air inlet valve aperture and cooling return air ball valve aperture, even the problem of cavity hydrops appears, also make refrigerant liquid level highly be less than magnetic bearing rotor suspension position, make the rotor be in gaseous environment. Like this, can effectively avoid the problem of compressor cavity hydrops, make the magnetic suspension rotor be in gaseous environment, ensure the stability of rotor suspension, improve the displacement precision.

In an alternative example, the displacement accuracy may be used as a condition for adjusting the cooling valve, and when the accuracy is not within a reasonable range, further judgment and control are performed.

Optionally, a liquid level sensor can be installed in the compressor cavity, the liquid level of the refrigerant in the cavity can be monitored in real time, and the liquid level signal is received and the opening of the cooling valve is regulated and controlled through the MCU.

Optionally, the opening degree of the cooling valve can be regulated and controlled by the temperature of the motor winding and the temperature of the magnetic bearing, so that the temperature of the motor winding and the temperature of the magnetic bearing can be controlled.

In an alternative embodiment, a specific implementation process of the scheme of the present invention can be exemplarily described with reference to the examples shown in fig. 2 to fig. 11.

Fig. 2 is a schematic diagram of cooling and detecting quantity of a compressor cavity of a magnetic suspension unit.

As shown in fig. 2, a liquid level sensor 1 is installed in the compressor cavity, and the first control valve 2, i.e. the first controllable valve, and the second control valve 3, i.e. the second controllable valve, are adjustable electromagnetic valves. For example: the first control valve 2 may be a cooling inlet valve of the magnetic levitation compressor cavity. The second control valve 3 can be a cooling air outlet ball valve of a magnetic suspension compressor cavity. In the magnetic levitation system shown in fig. 2, a throttle device 4 is further provided between the condenser and the first control valve 2, a front radial magnetic bearing 5 is further provided on the front side of the magnetic bearing of the magnetic levitation compressor, and a rear radial magnetic bearing 6 is further provided on the rear side of the magnetic bearing of the magnetic levitation compressor.

FIG. 3 is a schematic view of a reference level versus rotor position.

As shown in FIG. 3, a level reference L may be set_refFor rotor stoppingThe lower surface of the motor rotor 7 is high in a floating state.

Fig. 4 is a logic control schematic diagram of cooling control of the magnetic levitation compressor.

As shown in fig. 4, the cooling control system of the magnetic levitation compressor may include: the device comprises a rotor precision judging module and a cooling valve adjusting function module. Wherein, the rotor precision judging module may include: a displacement comparison circuit. A cooling valve adjustment function module, which may include: liquid level signal comparison circuit, temperature signal comparison circuit and controller.

Optionally, a displacement comparator circuit for comparing the displacement signal V_disAnd a reference displacement voltage V_refComparing, when the displacement signal V is_disLess than a reference displacement voltage V_refWhen the voltage is zero, the output of the comparator is 0; when the displacement signal V_disGreater than or equal to the reference displacement voltage V_refThe comparator output is 1.

Optionally, the liquid level signal comparison circuit can compare the real-time liquid level signal L_disAnd a reference liquid level L_refComparing the two liquid level signals when the real-time liquid level signal L is detected_disLess than reference level L_refWhen the output is 0, the signal is subjected to inversion and temperature comparison to carry out AND operation on the signal; when the real-time liquid level signal L_disGreater than or equal to the reference level L_refThe comparator output is 1.

Optionally, the temperature signal comparison circuit may collect the motor winding temperature and the bearing temperature to obtain a real-time temperature signal T of the motor winding temperature and the bearing temperature_dis(ii) a Will real-time temperature signal T_disWith a reference temperature T_refComparing the real-time temperature signal T_disLess than a reference temperature T_refWhen the voltage is zero, the output of the comparator is 0; when the real-time temperature signal T_disGreater than or equal to the reference temperature T_refThe comparator output is 1.

Optionally, the controller may perform signal processing by sampling a bearing displacement signal, a liquid level signal, and a temperature signal, output a control signal, control a bearing current to make the bearing stably suspend, and control a valve opening to adjust an amount of refrigerant inflow and outflow, etc.

The scheme of the invention aims to solve the problems of cavity liquid accumulation and insufficient cooling, the judgment is divided into two steps, firstly, the displacement precision is judged, and on the premise of poor displacement precision, the cavity refrigerant liquid level, the bearing temperature and the motor winding temperature are judged, otherwise, the cavity refrigerant liquid level, the bearing temperature and the motor winding temperature are not judged; in the aspect of the present invention, the chamber pressure is not used as the determination condition.

Fig. 5 is a schematic working flow chart of the cooling control of the magnetic levitation compressor.

As shown in fig. 5, in the solution of the present invention, the control process of the cooling control system of the magnetic levitation compressor may include:

step a, starting the unit, and carrying out real-time rotor displacement precision V_disCollecting and setting reference displacement precision V_refComparing, when the output value is 0, indicating that the displacement precision is good, and the unit can normally keep running; when the output value is 1, the current displacement precision is poor, and the delay t can be carried out in software_refAnd the displacement comparison circuit always outputs 1 in the delay stage, and the cooling valve adjusting function module is started.

B, executing a valve adjusting function module, when the liquid level comparison circuit outputs 1, indicating that the cavity accumulated liquid is serious, and needing to close a small cooling air inlet valve and open a large air outlet valve, and then judging whether to stop the machine; when the liquid level comparison circuit outputs 0, the cavity is indicated to have no accumulated liquid or the accumulated liquid is not contacted with the rotor, and the air inlet and outlet valve does not need to be operated.

For example: the bearing controller is a unit operation logic, and judges whether a shutdown instruction is received or not after the operation is executed each time when the unit is in an operation state. The shutdown is caused not only by large accumulated liquid amount, but also by two faults, such as too large accumulated liquid amount of a cavity or no accumulated liquid and too large cavity pressure; in addition, the controller receives other stop commands and stops the machine.

C, when the output of the liquid level comparison circuit is 0, inverting the output 0 signal, and carrying out AND operation on the output of the temperature comparison circuit, and when the output result is 0, indicating that the temperatures of a motor winding and a magnetic bearing are normal, and the unit can continuously keep normal operation; when the output result is 1, the temperature of the winding or the bearing is overhigh, the operation of opening a large cooling air inlet valve and closing a small air outlet valve is needed, and then whether the machine is stopped or not is judged.

Here, the shutdown is determined only by the logic requirements of the controller design, and the shutdown is performed as long as the bearing controller receives any shutdown command.

And d, if the command of the controller is shutdown, executing shutdown action, otherwise, returning to the step a for execution.

Optionally, the inlet valve and the outlet valve may be optionally adjusted in case of the operation of closing the cooling inlet valve and opening the large outlet valve in step b and in case of the operation of opening the large cooling inlet valve and closing the large outlet valve in step c. For example, the air outlet ball valve can be independently adjusted without adjusting the air inlet valve; or the air inlet valve is independently adjusted without adjusting the air outlet ball valve.

Optionally, in the case that the operation of closing the cooling intake valve and opening the large exhaust valve is required in step b, and in the case that the operation of opening the large cooling intake valve and closing the large exhaust valve is required in step c, the intake valve and the exhaust ball valve are designed to be manually or automatically adjustable.

Fig. 6 to 11 are schematic diagrams illustrating a control method of cooling control of the magnetic levitation compressor.

As shown in fig. 6 to 11, the control method for valve adjustment may be a step-type control as shown in fig. 6 and 7, a linear control as shown in fig. 8 and 9, or other non-linear control methods as shown in fig. 10 and 11.

Since the processing and functions of the magnetic levitation system of this embodiment are basically corresponding to the embodiments, principles and examples of the apparatus shown in fig. 1, the description of this embodiment is not given in detail, and reference may be made to the related descriptions in the embodiments, which are not described herein again.

Through a large number of tests, the technical scheme of the invention is adopted, and the opening of the cooling air inlet valve and the opening of the cooling air outlet ball valve are regulated and controlled according to the liquid level height by installing the liquid level sensor in the cavity of the compressor, so that the temperature of the motor winding and the temperature of the magnetic bearing are controllable, and the effects of considering the operation stability of the magnetic suspension compressor and cooling the motor winding and the magnetic bearing are achieved.

According to an embodiment of the present invention, there is also provided a cooling control method of a magnetic levitation system corresponding to the magnetic levitation system, as shown in fig. 12, which is a schematic flow chart of an embodiment of the method of the present invention. The cooling control method of the magnetic levitation system may include: step S110 to step S130.

In step S110, a displacement signal of a motor rotor of the magnetic levitation system is collected, and a liquid level signal of a refrigerant in a cavity of a magnetic levitation compressor of the magnetic levitation system is collected.

At step S120, it is determined whether the displacement signal of the motor rotor is greater than or equal to a set reference displacement; if the displacement signal of the motor rotor is greater than or equal to the set reference displacement, keeping the state that the displacement signal of the motor rotor is greater than or equal to the set reference displacement for a set time length, and further determining whether the liquid level signal of the refrigerant in the cavity of the magnetic suspension compressor is greater than or equal to the set reference liquid level after the set time length; and if the liquid level signal of the refrigerant in the cavity of the magnetic suspension compressor is greater than or equal to the set reference liquid level, determining that the accumulated liquid of the refrigerant in the cavity of the magnetic suspension compressor appears, and generating a refrigerant reduction signal which can be used for reducing the refrigerant quantity in the cavity of the magnetic suspension compressor.

In step S130, according to the refrigerant reduction signal, the refrigerant input amount of the magnetic suspension compressor cavity is controlled to be reduced, and/or the refrigerant output amount of the magnetic suspension compressor cavity is controlled to be increased, so that the liquid level of the refrigerant is lower than the suspension position of the magnetic bearing rotor, the problem of liquid accumulation in the compressor cavity can be effectively avoided, the magnetic suspension rotor is in a gas environment, and the suspension stability of the rotor is ensured. For example: the opening degree of the first control valve 2 (such as a cooling air inlet valve of the magnetic suspension compressor cavity) is controlled to be reduced, and/or the opening degree of the second control valve 3 (such as a cooling air outlet ball valve of the magnetic suspension compressor cavity) is controlled to be increased. Of course, the air inlet valve and the air outlet valve can be optionally adjusted under the condition that the air inlet valve for small cooling needs to be closed and the air outlet valve for large cooling needs to be opened; for example, the air outlet ball valve can be independently adjusted without adjusting the air inlet valve; or the air inlet valve is independently adjusted without adjusting the air outlet ball valve. In addition, under the condition that the operations of closing the small cooling air inlet valve and opening the large air outlet valve are required, the air inlet valve and the air outlet ball valve are designed to be manually adjusted and also automatically adjusted.

Optionally, the controlling of the decrease of the refrigerant input amount of the magnetic suspension compressor cavity and/or the increase of the refrigerant output amount of the magnetic suspension compressor cavity in step S130 may include: and controlling the opening degree of a refrigerant input valve of the cavity of the magnetic suspension compressor to be reduced and/or controlling the opening degree of a refrigerant output valve of the cavity of the magnetic suspension compressor to be increased.

In an optional embodiment, the method may further include: and (3) an over-temperature control process in cooling control.

The following further describes a specific process of the over-temperature control in the cooling control with reference to a schematic flow chart of an embodiment of the over-temperature control in the cooling control in the method of the present invention shown in fig. 13, which may include: step S210 to step S230.

Step S210, collecting temperature signals of a motor winding of the magnetic suspension system and/or a bearing of the magnetic suspension system. For example: and collecting the temperature of the motor winding and the temperature of the bearing.

Step S220, determining whether the liquid level signal of the refrigerant in the cavity of the magnetic suspension compressor is greater than or equal to a set reference liquid level; if the liquid level signal of the refrigerant in the cavity of the magnetic suspension compressor is less than the set reference liquid level, further determining whether the temperature signal of the motor winding and/or the bearing is greater than or equal to the set reference temperature; and if the temperature signal of the motor winding and/or the bearing is greater than or equal to the set reference temperature, determining that the temperature of the motor winding and/or the bearing is too high, and generating a refrigerant increasing signal which can be used for increasing the refrigerant quantity in the cavity of the magnetic suspension compressor so as to control the temperature of the motor winding and the temperature of the magnetic bearing.

And step S230, controlling the refrigerant input quantity of the cavity of the magnetic suspension compressor to increase and/or controlling the refrigerant output quantity of the cavity of the magnetic suspension compressor to decrease according to the refrigerant increasing signal. For example: the opening of the first control valve 2 (such as a cooling air inlet valve of the magnetic suspension compressor cavity) is controlled to be increased, and/or the opening of the second control valve 3 (such as a cooling air outlet ball valve of the magnetic suspension compressor cavity) is controlled to be decreased. Of course, the inlet valve and the outlet valve can be optionally adjusted under the condition that the large cooling inlet valve and the small cooling outlet valve need to be opened; for example, the air outlet ball valve can be independently adjusted without adjusting the air inlet valve; or the air inlet valve is independently adjusted without adjusting the air outlet ball valve. In addition, under the condition that the large cooling air inlet valve needs to be opened and the small air outlet valve needs to be closed, the air inlet valve and the air outlet ball valve are designed to be manually adjusted and also can be automatically adjusted.

Optionally, the controlling of the increase of the refrigerant input amount of the magnetic suspension compressor cavity and/or the controlling of the decrease of the refrigerant output amount of the magnetic suspension compressor cavity in step S230 may include: and controlling the opening of a refrigerant input valve of the cavity of the magnetic suspension compressor to increase and/or controlling the opening of a refrigerant output valve of the cavity of the magnetic suspension compressor to decrease.

More alternatively, the method of controlling the opening degree of the refrigerant input valve of the magnetic suspension compressor cavity to decrease, or controlling the opening degree of the refrigerant output valve of the magnetic suspension compressor cavity to increase, or controlling the opening degree of the refrigerant input valve of the magnetic suspension compressor cavity to increase, or controlling the opening degree of the refrigerant output valve of the magnetic suspension compressor cavity to decrease in step S130 or step S230 may include: a step control mode, a linear control mode or a curve control mode.

The following further describes a specific process of shutdown control after cooling control with reference to a flowchart of an embodiment of shutdown control after cooling control in the method of the present invention shown in fig. 14, which may include: step S310 and step S320.

Step S310, if the displacement signal of the motor rotor is smaller than the set reference displacement, determining that no accumulated liquid exists in the refrigerant in the cavity of the magnetic suspension compressor, and generating a first refrigerant maintaining signal which can be used for maintaining the refrigerant quantity in the cavity of the magnetic suspension compressor so as to control the magnetic suspension system to maintain the current running state; or if the temperature signal of the motor winding and/or the bearing is less than the set reference temperature, determining that the temperature of the motor winding and/or the bearing is not high, and generating a second refrigerant maintaining signal which can be used for maintaining the refrigerant quantity in the cavity of the magnetic suspension compressor so as to control the magnetic suspension system to maintain the current operation state.

Step S320, controlling the magnetic suspension system to maintain the current operation state according to the first refrigerant retaining signal or the second refrigerant retaining signal.

Of course, after the cooling control, for example, after the control unit controls the refrigerant input amount of the magnetic suspension compressor cavity to increase and/or controls the refrigerant output amount of the magnetic suspension compressor cavity to decrease, or the control unit controls the refrigerant input amount of the magnetic suspension compressor cavity to increase and/or controls the magnetic suspension compressor cavity to decreaseAfter the refrigerant output quantity of the compressor cavity is reduced or the control unit controls the magnetic suspension system to maintain the current running state, if the control unit receives a stop signal, the control unit controls the magnetic suspension system to stop, and then the cooling control process can be carried out again after the unit is started again. If the controller commands to stop, executing the stop action, otherwise, returning to the real-time rotor displacement precision V after the unit is started_disCollecting and setting reference displacement precision V_refAnd (5) comparing.

Since the processing and functions implemented by the method of this embodiment basically correspond to the embodiments, principles and examples of the magnetic levitation system, the description of this embodiment is not detailed, and reference may be made to the related descriptions in the embodiments, which are not repeated herein.

Through a large amount of experimental verifications, adopt the technical scheme of this embodiment, through installation level sensor, the liquid refrigerant volume in the real-time supervision compressor cavity, regulation and control cooling air inlet valve aperture and cooling return air ball valve aperture can effectively avoid the problem of compressor cavity hydrops, ensure the stability of rotor suspension, improve the displacement precision of magnetic suspension rotor.

In summary, it is readily understood by those skilled in the art that the advantageous modes described above can be freely combined and superimposed without conflict.

The above description is only an example of the present invention, and is not intended to limit the present invention, and it is obvious to those skilled in the art that various modifications and variations can be made in the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A cooling control apparatus, comprising: the device comprises an acquisition unit, a determination unit and a control unit; wherein the content of the first and second substances,

the acquisition unit is used for acquiring a displacement signal of a motor rotor of the magnetic suspension system and acquiring a liquid level signal of a refrigerant in a magnetic suspension compressor cavity of the magnetic suspension system;

a determination unit for determining whether a displacement signal of the motor rotor is greater than or equal to a set reference displacement; if the displacement signal of the motor rotor is greater than or equal to the set reference displacement, further determining whether the liquid level signal of the refrigerant in the cavity of the magnetic suspension compressor is greater than or equal to the set reference liquid level after the set time length; if the liquid level signal of the refrigerant in the cavity of the magnetic suspension compressor is greater than or equal to the set reference liquid level, generating a refrigerant reduction signal for reducing the amount of the refrigerant in the cavity of the magnetic suspension compressor;

and the control unit is used for controlling the refrigerant input quantity of the cavity of the magnetic suspension compressor to be reduced and/or controlling the refrigerant output quantity of the cavity of the magnetic suspension compressor to be increased according to the refrigerant reducing signal.

2. The apparatus of claim 1, further comprising:

the acquisition unit is also used for acquiring temperature signals of a motor winding of the magnetic suspension system and/or a bearing of the magnetic suspension system;

the determining unit is also used for determining whether the liquid level signal of the refrigerant in the cavity of the magnetic suspension compressor is greater than or equal to a set reference liquid level; if the liquid level signal of the refrigerant in the cavity of the magnetic suspension compressor is less than the set reference liquid level, further determining whether the temperature signal of the motor winding and/or the bearing is greater than or equal to the set reference temperature; if the temperature signal of the motor winding and/or the bearing is greater than or equal to the set reference temperature, generating a refrigerant increasing signal for increasing the refrigerant quantity in the cavity of the magnetic suspension compressor;

and the control unit is also used for controlling the refrigerant input quantity of the cavity of the magnetic suspension compressor to be increased and/or controlling the refrigerant output quantity of the cavity of the magnetic suspension compressor to be reduced according to the refrigerant increasing signal.

3. The apparatus of claim 2, wherein,

the refrigerant input quantity of control magnetic suspension compressor cavity reduces, and/or the refrigerant output quantity of control magnetic suspension compressor cavity increases, includes: controlling the opening degree of a refrigerant input valve of the magnetic suspension compressor cavity to be reduced and/or controlling the opening degree of a refrigerant output valve of the magnetic suspension compressor cavity to be increased;

alternatively, the first and second electrodes may be,

the coolant input volume of control magnetic suspension compressor cavity increases, and/or the coolant output volume of control magnetic suspension compressor cavity reduces, includes: and controlling the opening of a refrigerant input valve of the cavity of the magnetic suspension compressor to increase and/or controlling the opening of a refrigerant output valve of the cavity of the magnetic suspension compressor to decrease.

4. The apparatus of claim 3, wherein the means for controlling the opening degree of the refrigerant input valve of the magnetic suspension compressor cavity to decrease, the opening degree of the refrigerant output valve of the magnetic suspension compressor cavity to increase, the opening degree of the refrigerant input valve of the magnetic suspension compressor cavity to increase, or the opening degree of the refrigerant output valve of the magnetic suspension compressor cavity to decrease comprises: a step control mode, a linear control mode or a curve control mode.

5. The apparatus of any of claims 2 to 4, further comprising:

the determining unit is also used for determining whether the displacement signal of the motor rotor is greater than or equal to a set reference displacement; if the displacement signal of the motor rotor is smaller than the set reference displacement, generating a first refrigerant maintaining signal for maintaining the refrigerant quantity in the cavity of the magnetic suspension compressor; or if the temperature signal of the motor winding and/or the bearing is less than the set reference temperature, generating a second refrigerant maintaining signal for maintaining the refrigerant quantity in the cavity of the magnetic suspension compressor;

and the control unit is also used for controlling the magnetic suspension system to maintain the current running state according to the first refrigerant maintaining signal or the second refrigerant maintaining signal.

6. A magnetic levitation system, comprising: the cooling control apparatus according to any one of claims 1 to 5.

7. A cooling control method of a magnetic levitation system as claimed in claim 6, comprising:

acquiring a displacement signal of a motor rotor of a magnetic suspension system, and acquiring a liquid level signal of a refrigerant in a magnetic suspension compressor cavity of the magnetic suspension system;

determining whether a displacement signal of the motor rotor is greater than or equal to a set reference displacement; if the displacement signal of the motor rotor is greater than or equal to the set reference displacement, further determining whether the liquid level signal of the refrigerant in the cavity of the magnetic suspension compressor is greater than or equal to the set reference liquid level after the set time length; if the liquid level signal of the refrigerant in the cavity of the magnetic suspension compressor is greater than or equal to the set reference liquid level, generating a refrigerant reduction signal for reducing the amount of the refrigerant in the cavity of the magnetic suspension compressor;

and controlling the input quantity of the refrigerant of the cavity of the magnetic suspension compressor to be reduced and/or controlling the output quantity of the refrigerant of the cavity of the magnetic suspension compressor to be increased according to the refrigerant reducing signal.

8. The method of claim 7, further comprising:

collecting temperature signals of a motor winding of the magnetic suspension system and/or a bearing of the magnetic suspension system;

determining whether a liquid level signal of a refrigerant in a cavity of the magnetic suspension compressor is greater than or equal to a set reference liquid level; if the liquid level signal of the refrigerant in the cavity of the magnetic suspension compressor is less than the set reference liquid level, further determining whether the temperature signal of the motor winding and/or the bearing is greater than or equal to the set reference temperature; if the temperature signal of the motor winding and/or the bearing is greater than or equal to the set reference temperature, generating a refrigerant increasing signal for increasing the refrigerant quantity in the cavity of the magnetic suspension compressor;

and controlling the refrigerant input quantity of the cavity of the magnetic suspension compressor to increase and/or controlling the refrigerant output quantity of the cavity of the magnetic suspension compressor to decrease according to the refrigerant increasing signal.

9. The method of claim 8, wherein,

alternatively, the first and second electrodes may be,

10. The method of claim 9, wherein the controlling of the opening degree of the refrigerant input valve of the magnetic suspension compressor cavity to decrease, the opening degree of the refrigerant output valve of the magnetic suspension compressor cavity to increase, the opening degree of the refrigerant input valve of the magnetic suspension compressor cavity to increase, or the opening degree of the refrigerant output valve of the magnetic suspension compressor cavity to decrease comprises: a step control mode, a linear control mode or a curve control mode.

11. The method of any one of claims 8 to 10, further comprising:

if the displacement signal of the motor rotor is smaller than the set reference displacement, generating a first refrigerant maintaining signal for maintaining the refrigerant quantity in the cavity of the magnetic suspension compressor; or if the temperature signal of the motor winding and/or the bearing is less than the set reference temperature, generating a second refrigerant maintaining signal for maintaining the refrigerant quantity in the cavity of the magnetic suspension compressor;

and controlling the magnetic suspension system to maintain the current running state according to the first refrigerant maintaining signal or the second refrigerant maintaining signal.