A magnetic suspension compressor head internal circulation liquid cooling-air cooling collaborative control method, system, device and storage medium

Abstract

This invention relates to the field of cooling control technology for magnetic levitation compressors, and more particularly to a method, system, equipment, and storage medium for coordinated control of internal circulating liquid cooling and air cooling in the compressor head of a magnetic levitation compressor. It is applicable to temperature control and levitation stability protection of the compressor head in magnetic levitation centrifugal compressors, magnetic levitation air compressors, and high-speed compressors supported by magnetic bearings. This invention divides the compressor head into heat load zones such as the motor stator, rotor air gap, radial magnetic bearing, and axial magnetic bearing. It collects zone temperatures, coolant heat transfer parameters, rotor displacement, and magnetic bearing control current to calculate the heat load index and levitation stability index. Based on these two indices, it coordinately adjusts the liquid-cooled pump, zone regulating valve, bypass valve, air-cooled fan, and dampers. This scheme can reduce local temperature rise and temperature gradient, minimize the disturbance of sudden liquid cooling changes to rotor levitation stability, and improve the operational reliability of the compressor.

Description

Technical Field

[0001] This invention relates to the field of cooling control technology for magnetic levitation compressors, and more particularly to a method, system, equipment, and storage medium for coordinated control of internal circulating liquid cooling and air cooling in the compressor head of a magnetic levitation compressor. It is applicable to temperature control and levitation stability protection of the compressor head of magnetic levitation centrifugal compressors, magnetic levitation air compressors, and high-speed compressors supported by magnetic bearings. Background Technology

[0002] Magnetic levitation compressors typically use high-speed permanent magnet synchronous motors or high-speed induction motors to directly drive the impeller rotation, and achieve contactless rotor support through radial and axial magnetic bearings. Compared with traditional mechanical bearing compressors, magnetic levitation compressors have advantages such as low friction loss, high speed, low maintenance, and high operating efficiency. However, their compressor head integrates the motor stator, rotor, radial magnetic bearings, axial magnetic bearings, impeller end sealing structure, and power output components, resulting in a compact space, concentrated heat sources, and the high-speed rotor is highly sensitive to air gap temperature, magnetic bearing temperature rise, and local thermal deformation. If the internal temperature distribution of the compressor head is uneven or local hot spots cannot be eliminated in time, it may cause problems such as winding insulation aging, increased risk of magnet demagnetization, excessive temperature rise of magnetic bearing coils, rotor thermal expansion and misalignment, and abnormal increase in control current, thereby affecting the rotor levitation accuracy and the reliability of continuous compressor operation.

[0003] Existing technologies already include control schemes for internal cooling and magnetic bearing stability in magnetic levitation compressors. For example, Chinese patent application CN109654779A discloses a control device, control method, compressor, and air conditioner for a compressor's magnetic levitation bearing. This method incorporates a first control valve and a second control valve in the compressor's cooling circuit. It utilizes a bearing current detection device and a motor temperature sensor to collect the current before and after the shaft, as well as the motor temperature. Based on these detection signals, it controls the opening degrees of the first and second control valves to throttle the refrigerant flow from the compressor, thereby improving the cooling and operating condition of the magnetic levitation bearing. This scheme focuses on adjusting the opening degrees of the refrigerant inlet and outlet valves and the influence of bearing current and motor temperature on refrigerant throttling, thus achieving a balance between cooling effect and magnetic bearing operating condition to a certain extent.

[0004] However, the aforementioned solutions primarily focus on controlling the throttling of the refrigerant circuit, failing to divide the internal structure of the magnetic levitation compressor head into multiple heat load zones based on different heat sources such as the motor stator, rotor air gap, front radial magnetic bearing, rear radial magnetic bearing, and axial magnetic bearing. Furthermore, they do not establish separate heat load indices, liquid cooling channels, and air-cooling compensation channels for each zone. Therefore, when a rapid temperature rise occurs in a localized area of ​​the compressor head or a significant temperature gradient appears between adjacent areas, simply adjusting the refrigerant valve opening uniformly is insufficient to accurately identify hotspot locations and achieve differentiated cooling for different heat load zones. In addition, rapid changes in refrigerant or coolant flow can cause abrupt changes in the local temperature field, pressure field, or structural thermal deformation of the compressor head, thereby disturbing the levitation stability of the high-speed rotor. Current technology lacks a liquid cooling ramp-up limiting mechanism that integrates rotor displacement, displacement change rate, and magnetic bearing control current.

[0005] Another existing technology uses air cooling to cool the main motor of a magnetic levitation air compressor. For example, Chinese patent application CN113738675A discloses an air-cooled constant temperature system for the main motor of a magnetic levitation air compressor. This system utilizes a portion of the compressed air generated by the air compressor itself, which is then fed into the air-cooling inlet of the main motor after passing through a throttling and pressure-stabilizing component. A temperature sensor detects the temperature of the main motor, and the opening of an electric regulating valve is adjusted accordingly to achieve constant air cooling of the main motor. This solution requires no additional power source, utilizes compressed air to cool the main motor, and automatically adjusts the airflow based on temperature feedback.

[0006] However, purely air-cooled solutions typically have low heat transfer coefficients, making it difficult to quickly remove heat from the motor stator, magnetic bearing coils, and areas near the local air gap in the high heat flux density region of a high-speed magnetic levitation compressor head. While purely liquid-cooled solutions offer stronger heat transfer capabilities, rapid changes in coolant flow rate, valve opening, and bypass ratio can cause localized thermal shock or overcooling, potentially increasing condensation, sealing reliability, and the risk of levitation disturbances. Especially in scenarios involving magnetic levitation compressors during acceleration, loading, surge-edge operation, frequent changes in operating conditions, or significant ambient temperature fluctuations, the degree of heat generation varies across different areas of the compressor head, and there is a coupling relationship between motor stator temperature rise, magnetic bearing temperature rise, rotor displacement deviation, and magnetic bearing control current. If the control system adjusts cooling solely based on single-point temperature or the overall temperature of the main motor, problems such as delayed cooling response, coexisting localized overcooling or overheating, independent operation of liquid and air cooling, and continued increase in liquid cooling flow even during levitation anomalies can easily occur.

[0007] Therefore, there is an urgent need for a new cooling control scheme for the compressor head of a magnetic levitation compressor. This scheme can divide the internal heat source of the compressor head into multiple heat load zones, and collect parameters such as zone temperature, coolant inlet and outlet temperatures, coolant flow rate, rotor displacement, rotor displacement change rate, and magnetic bearing control current for each zone. Based on these parameters, a heat load index and a suspension stability index are established, and the internal circulating liquid cooling pump speed, zone regulating valve opening, bypass valve opening, air-cooled fan speed, and air-cooled zone damper opening are adjusted in synergy with these two parameters. In this way, liquid cooling undertakes the main heat dissipation task in high heat flux density areas, while air cooling compensates for liquid cooling limitations, decreased suspension stability, anti-condensation control triggering, or insufficient heat exchange. This reduces the local temperature rise of the compressor head while minimizing the impact of cooling actions on the stability of the magnetic levitation rotor, thereby improving the thermal safety, suspension stability, and continuous operation reliability of the magnetic levitation compressor under complex operating conditions. Summary of the Invention

[0008] The purpose of this invention is to provide a method and system for coordinated control of internal circulating liquid cooling and air cooling in a magnetic levitation compressor head based on thermal load zoning and suspension stability constraints. This method involves dividing the motor stator, rotor air gap, front radial magnetic bearing, rear radial magnetic bearing, and axial magnetic bearing within the magnetic levitation compressor head into thermal load zones. By combining zone temperature, coolant heat exchange status, rotor displacement, rotor displacement change rate, and magnetic bearing control current, the internal circulating liquid cooling flow rate, zone valve opening, bypass ratio, and air cooling compensation air volume are coordinated and adjusted. This addresses the problems in existing magnetic levitation compressor head cooling control, such as inaccurate identification of local hot spots, independent liquid cooling and air cooling actions, sudden changes in cooling flow affecting suspension stability, and the difficulty of adapting to complex and variable operating conditions with single temperature feedback control.

[0009] Firstly, in order to achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0010] A method for coordinated control of internal circulating liquid cooling and air cooling in a magnetic levitation compressor head, the method comprising the following steps:

[0011] S1. According to the location of the heat source, the arrangement of the cooling channel and the location of the magnetic levitation support in the magnetic levitation compressor head, the magnetic levitation compressor head is divided into multiple heat load zones. The heat load zones include at least the motor stator zone, the rotor air gap zone, the front radial magnetic bearing zone, the rear radial magnetic bearing zone and the axial magnetic bearing zone. A corresponding temperature acquisition point, an internal circulation liquid cooling channel and an air cooling compensation channel are established for each heat load zone.

[0012] S2, collect the zone temperature of each heat load zone. Coolant inlet temperature Coolant outlet temperature Coolant flow rate Rotor displacement Rotor displacement change rate Magnetic bearing control current And air-cooled outlet temperature ;

[0013] S3, based on the temperature deviation, temperature rise rate, and liquid cooling heat transfer deviation of each heat load zone, calculate the heat load index of each heat load zone. ;

[0014] S4, based on , and Calculate the suspension stability index corresponding to each heat load zone. ;

[0015] S5, according to and Generate the internal circulation liquid cooling control quantity and air cooling compensation control quantity for each heat load zone; when Higher than the liquid cooling start-up threshold and When the coolant flow rate is below the levitation safety threshold, prioritize increasing the coolant flow rate in the corresponding internal circulation liquid cooling channel or reducing the bypass ratio; when Higher than the liquid cooling start-up threshold and When the flow rate is not lower than the suspension safety threshold, the rate of increase of coolant flow is limited, and the air volume of the corresponding air-cooled compensation channel is increased first.

[0016] S6, when any heat load zone When the speed exceeds the suspension warning threshold, the system enters the suspension stability constraint mode. Under this mode, the liquid cooling pump speed, the opening of the zone regulating valve, and the opening of the bypass valve are limited, while the air-cooled fan speed is increased to reduce the disturbance of the rotor suspension state caused by sudden changes in coolant flow.

[0017] S7, when all heat load zones Below the recovery threshold and After the temperature drops below the levitation safety threshold and remains stable for a preset time, the system exits the levitation stability constraint mode and returns to the energy-saving cooling mode, following the order of decreasing liquid cooling flow rate first and then decreasing air cooling flow rate.

[0018] Preferably, in step S1, the multiple heat load zones are configured into a zone mapping table according to the axial position of the machine head and the type of heat source. The zone mapping table includes at least the zone number, temperature acquisition point number, internal circulation liquid cooling channel number, air cooling compensation channel number, corresponding magnetic bearing number, and corresponding rotor displacement direction. Among them, the front radial magnetic bearing zone and the rear radial magnetic bearing zone correspond to the radial displacement signal, the axial magnetic bearing zone corresponds to the axial displacement signal, and the motor stator zone and the rotor air gap zone correspond to the winding temperature and the air gap temperature, respectively.

[0019] The control method according to claim 1 is characterized in that, in step S3, the heat load index satisfy:

[0020] ;

[0021] In the formula, For the i-th heat load zone in Heat load index at any given time; For the i-th heat load zone in The zone temperature at any given time; The target temperature for the i-th heat load zone; Let be the upper limit temperature allowed for the i-th heat load zone; Let be the temperature rise rate of the i-th heat load zone; Let be the allowable temperature rise rate for the i-th heat load zone; The difference between the coolant outlet temperature and the coolant inlet temperature in the internal circulation liquid cooling channel corresponding to the i-th heat load zone; Let be the target heat exchange temperature difference for the i-th heat load zone; This represents the upper limit of the allowable heat exchange temperature difference for the i-th heat load zone; , and These are the weighting coefficients for temperature deviation, temperature rise rate, and liquid cooling heat transfer deviation, respectively.

[0022] And / or, in step S3, the heat load index is further corrected based on the temperature gradient between adjacent heat load zones. The corrected heat load index is obtained. :

[0023] In the formula, The heat load index is the corrected heat load index for the i-th heat load zone; The heat load index before correction for the i-th heat load zone; This is the set of heat load zones adjacent to the i-th heat load zone; For the i-th heat load zone in Temperature of the zone at any given time; For the j-th heat load zone in Temperature of the zone at any given time; This represents the allowable temperature gradient between the i-th heat load zone and the j-th heat load zone; This is the temperature gradient correction factor;

[0024] And / or, in step S3, the suspension stability index satisfy:

[0025] ;

[0026] In the formula, For the i-th heat load zone in The moment-to-moment suspension stability index; This represents the rotor displacement corresponding to the i-th heat load zone; This corresponds to the target levitation position of the rotor; Permissible rotor displacement limits; The rotor displacement change rate; To limit the allowable rate of change of rotor displacement; The magnetic bearing control current corresponding to the i-th heat load zone; This is the corresponding magnetic bearing reference control current; To allow for the control current deviation limit of the magnetic bearing; , and These are the weighting coefficients for rotor displacement, rotor displacement change rate, and magnetic bearing control current, respectively.

[0027] Preferably, in step S5, the internal circulation liquid cooling control quantity includes the target rotational speed of the liquid cooling pump. Target opening degree of zone control valve and bypass valve target opening Among them, the target opening degree of the zone control valve Determine as follows:

[0028] ;

[0029] In the formula, The target opening degree of the zone control valve for the i-th heat load zone; The reference opening degree of the zone control valve for the i-th heat load zone; This is the heat load gain coefficient; For the i-th heat load zone in Heat load index at any given time; Let be the liquid cooling start-up threshold for the i-th heat load zone; The levitation constraint gain coefficient; For the i-th heat load zone in The moment-to-moment suspension stability index; The levitation safety threshold; Indicates when Take when greater than 0 Otherwise, take 0; This means that the calculation results are limited to the minimum and maximum allowable opening of the zone control valve.

[0030] And / or, in step S5, the air-cooling compensation control quantity includes the target speed of the air-cooled fan. Air-cooled zone damper opening And the start-up time of air-cooled compensation, including the target speed of the air-cooled fan. Determine as follows:

[0031] ;

[0032] In the formula, The target speed for the air-cooled fan; This is the reference speed for the air-cooled fan; This is the gain coefficient for heat load air cooling compensation; For the i-th heat load zone in Heat load index at any given time; The air-cooling compensation threshold for the i-th heat load zone; This is the gain coefficient for compensation of abnormal air cooling during suspension. For the i-th heat load zone in The moment-to-moment suspension stability index; The levitation safety threshold; Indicates when Take when greater than 0 Otherwise, take 0; Indicates when Take when greater than 0 Otherwise, take 0; This means that the calculation results are limited to the minimum and maximum allowable speeds of the air-cooled fan.

[0033] Preferably, in step S6, the ramp-up limit includes the limit on the rate of change of liquid cooling pump speed, the limit on the rate of change of the zone control valve opening, and the limit on the rate of change of the bypass valve opening; when the suspension stability index Above the levitation safety threshold And below the hovering shutdown threshold At that time, the rate of change of the liquid cooling pump speed should satisfy:

[0034] ;

[0035] In the formula, This represents the rate of change of the liquid cooling pump speed. This refers to the maximum permissible rate of change of rotational speed for the liquid-cooled pump. The threshold for levitation shutdown; For the i-th heat load zone in The moment-to-moment suspension stability index; For the levitation safety threshold; when The closer The smaller the rate of change of the liquid cooling pump speed is limited, the better;

[0036] And / or, in step S7, the energy-saving cooling mode includes: [the following is unclear due to incomplete sentence fragment: "at heat load index"] Below the recovery threshold and the rate of temperature rise When the temperature rise rate is less than the preset threshold, first reduce the liquid cooling pump speed and the opening of the zone regulating valve according to the preset descent slope; at the coolant outlet temperature With zone temperature After the heat exchange temperature difference between them stabilizes, the speed of the air-cooled fan is reduced according to the preset downward slope to avoid the local temperature rebound of the machine head caused by the simultaneous decrease of the internal circulation liquid cooling and air cooling.

[0037] Preferably, an anti-condensation control step is also included: based on the ambient dew point temperature. Determine the lower limit temperature of liquid cooling based on the lowest wall temperature of the compressor head. When the coolant inlet temperature Below the liquid cooling lower limit temperature At this time, increase the bypass valve opening or reduce the liquid cooling pump speed, and maintain heat dissipation through the air-cooled compensation channel; among which, the lower limit temperature of liquid cooling Determine as follows:

[0038] ;

[0039] In the formula, for The lower limit temperature of liquid cooling at any given time; for The ambient dew point temperature at any given time; To prevent condensation, a safe temperature difference is required.

[0040] Secondly, the present invention also provides a magnetic levitation compressor head internal circulating liquid cooling-air cooling coordinated control system, comprising:

[0041] The zone acquisition module is used to acquire the zone temperature of the motor stator zone, rotor air gap zone, front radial magnetic bearing zone, rear radial magnetic bearing zone, and axial magnetic bearing zone. Coolant inlet temperature Coolant outlet temperature Coolant flow rate Rotor displacement Rotor displacement change rate Magnetic bearing control current And air-cooled outlet temperature ;

[0042] The heat load zoning calculation module is used to calculate the heat load index of each heat load zone based on the temperature deviation, temperature rise rate, liquid cooling heat transfer deviation, and temperature gradient between adjacent heat load zones. ;

[0043] The suspension stability constraint module is used to determine the rotor displacement. Rotor displacement change rate and magnetic bearing control current Calculate the suspension stability index for each heat load zone. And determine whether to enter the suspension stability constraint mode;

[0044] The internal circulation liquid cooling actuator module includes a liquid storage unit, a liquid cooling pump, a heat exchanger, a zone regulating valve, a bypass valve, and zoned liquid cooling channels located within the compressor head, used to adjust the cooling output according to the heat load index. and suspension stability index Adjusting the coolant flow rate Zone control valve opening and bypass valve opening ;

[0045] The air-cooled compensation execution module includes an air-cooled fan, an air-cooled partition damper, and an air-cooled compensation channel set in the head unit. It is used to perform air-cooled compensation on the corresponding heat load partition when liquid cooling is limited by suspension stability constraints, liquid cooling heat exchange is insufficient, or anti-condensation control is triggered.

[0046] The collaborative control module is used to execute the control method and output the target speed of the liquid cooling pump. Target opening degree of zone control valve Bypass valve target opening degree Target speed of air-cooled fan Air-cooled partition damper opening .

[0047] Preferably, the collaborative control module includes a fault degradation unit, which is configured as follows:

[0048] When the temperature acquisition point is abnormal, the zone temperature of the adjacent heat load zone is used. Coolant outlet temperature and magnetic bearing control current Estimate the heat load index of the corresponding heat load zone ;

[0049] When the rotor displacement sensor malfunctions, the magnetic bearing control current is used. Magnetic bearing control current change rate Estimating the suspension stability index using rotor vibration signals ;

[0050] When the liquid cooling pump, zone regulating valve or bypass valve malfunctions, shut down the liquid cooling increment regulation of the malfunctioning zone and increase the airflow of the corresponding air cooling compensation channel.

[0051] When the suspension stability index Reaching the hovering shutdown threshold When necessary, output a compressor load reduction or shutdown protection command.

[0052] Thirdly, the present invention also provides an electronic device, including a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, it implements the method described above.

[0053] Fourthly, the present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method described thereon.

[0054] This invention divides the magnetic levitation compressor head into multiple heat load zones and establishes a heat load index H for each zone. i (t) and suspension stability index M i (t) enables cooling control to no longer rely solely on single-point temperature or the overall temperature of the main motor, but instead identifies temperature deviations, temperature rise rates, liquid cooling heat transfer deviations, and temperature gradients between adjacent zones in different heat-generating areas, thereby improving the accuracy of local hot spot identification and the targeted nature of cooling distribution. By incorporating rotor displacement, rotor displacement change rate, and magnetic bearing control current into the cooling control logic, the internal circulation liquid cooling capacity is prioritized when the suspension state is normal. When the suspension state approaches the warning level, the rate of change of liquid cooling pump speed, zone regulating valve opening, and bypass valve opening is limited, and the airflow of the air-cooled compensation channel is increased simultaneously. This reduces the impact of sudden changes in coolant flow, local thermal shock, or structural thermal deformation on the suspension stability of the high-speed rotor. The invention employs control modes such as liquid cooling priority, air cooling compensation, anti-condensation control, suspension stability constraint, and energy-saving recovery. Liquid cooling undertakes the primary heat dissipation task in high heat flux density areas, while air cooling provides auxiliary compensation when liquid cooling is limited, heat exchange is insufficient, condensation is at risk, or suspension stability decreases. This balances rapid heat dissipation, stable suspension, and energy-saving operation. Compared to solutions using only single air cooling, single liquid cooling, or cooling based on single-point temperature regulation, this invention reduces local temperature rise and zoned temperature gradients in the compressor head, minimizes abnormal fluctuations in magnetic bearing control current, reduces the risk of rotor displacement deviation expansion, and improves the thermal safety, suspension stability, and continuous operation reliability of the magnetic levitation compressor under acceleration, loading, frequent changing operating conditions, and high ambient temperature conditions. Attached Figure Description

[0055] Figure 1 This is a schematic flowchart of a method for coordinated control of internal circulating liquid cooling and air cooling in a magnetic levitation compressor head based on thermal load zoning and suspension stability constraints, according to the present invention.

[0056] Figure 2 This is a schematic diagram of the control system of the present invention.

[0057] Figure 3 This is a schematic diagram of the thermal load zoning of the magnetic levitation compressor head of the present invention.

[0058] Figure 4 This is a schematic diagram of the arrangement of the internal circulation liquid cooling channel and the air cooling compensation channel of the present invention.

[0059] Figure 5 This is a schematic diagram illustrating the generation logic of the heat load index and suspension stability index of the present invention.

[0060] Figure 6 This is a schematic diagram of the liquid-cooled-air-cooled coordinated control and mode switching of the present invention.

[0061] Figure 7 This is a schematic diagram of the fault degradation control of the present invention.

[0062] Figure 8 This is a temperature change curve of each heat load zone under steady-state load conditions according to an embodiment of the present invention.

[0063] Figure 9 This is a graph showing the changes in heat load index and zone control valve opening under step loading conditions in an embodiment of the present invention.

[0064] Figure 10 This is a comparison chart of rotor displacement deviation and liquid cooling pump speed change rate under suspension disturbance conditions between embodiments and comparative examples of the present invention. Figure 10 (a) shows a comparison of rotor displacement deviations. Figure 10 (b) shows a comparison of the rate of change of liquid cooling pump speed.

[0065] Figure 11 This is a comparison chart of the embodiment of the present invention and the comparative example in terms of hot spot temperature and cumulative cooling energy consumption at the machine head. Detailed Implementation

[0066] The following is in conjunction with the appendix Figures 1 to 11 The specific embodiments of the present invention will be described below. It should be understood that the following embodiments are used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Without departing from the concept of the present invention, those skilled in the art can make adaptive adjustments to the number of sensors, threshold range, control cycle and actuator form according to the specifications, power level, compressor head structure, coolant type, air-cooling channel arrangement and controller type of the magnetic levitation compressor.

[0067] I. Terminology Explanation

[0068] In this embodiment, the magnetic levitation compressor head refers to the core component of a compressor that integrates a high-speed motor, rotor, impeller, radial magnetic bearing, axial magnetic bearing, housing, sealing structure, and related cooling structure. The compressor head typically features a compact internal space, concentrated heat source, high heat flux density, high rotor speed, and high precision requirements for magnetic levitation control.

[0069] The heat load zoning refers to dividing the machine head into several regions based on the location of heat sources, heat transfer paths, cooling channel layout, and magnetic levitation support within the machine head. These regions are capable of independently acquiring temperature, calculating heat load, and receiving differentiated cooling control. The heat load zoning includes at least the motor stator zone, rotor air gap zone, front radial magnetic bearing zone, rear radial magnetic bearing zone, and axial magnetic bearing zone.

[0070] The internal circulation liquid cooling refers to a closed or semi-closed circulation of coolant within the compressor head, consisting of zoned liquid cooling channels, liquid cooling pumps, heat exchangers, liquid storage units, zoned regulating valves, and bypass valves, without directly relying on the compressor's working medium as the cooling medium. Internal circulation liquid cooling primarily handles the rapid heat dissipation task in areas with high heat flux density.

[0071] The aforementioned air-cooling compensation refers to providing auxiliary cooling airflow to the corresponding area of ​​the machine head through air-cooled fans, air-cooled partition dampers, and air-cooling compensation channels, supplementing heat dissipation capacity when liquid cooling is limited by suspension stability constraints, liquid cooling heat exchange is insufficient, anti-condensation control is triggered, or the local temperature gradient is large.

[0072] The aforementioned suspension stability constraint refers to the fact that, in the cooling control process, not only the temperature is considered, but also the rotor displacement, rotor displacement change rate, and magnetic bearing control current are used as constraints to limit sudden changes in liquid cooling flow, valve opening, and bypass ratio, so that the cooling action will not significantly disturb the suspension stability of the high-speed rotor.

[0073] II. System Structure

[0074] like Figure 2 As shown, the control system of the present invention includes a zone acquisition module, a heat load zone calculation module, a suspension stability constraint module, an internal circulation liquid cooling execution module, an air cooling compensation execution module, a collaborative control module, and a fault degradation unit.

[0075] The zone acquisition module is used to collect operating parameters for each heat load zone. Specifically, it includes temperature sensors located near the motor stator windings or stator core; temperature acquisition points located near the rotor air gap or adjacent to the housing; temperature acquisition points located near the front and rear radial magnetic bearings; temperature acquisition points located near the axial magnetic bearing; coolant temperature sensors located at the liquid cooling inlet and liquid cooling outlet of each zone; flow sensors located on the liquid cooling branches of each zone; displacement sensors for detecting rotor radial and axial displacement; a current acquisition unit for acquiring the magnetic bearing control current; and a temperature acquisition point for detecting the air cooling outlet temperature.

[0076] The heat load zoning calculation module is used to calculate the heat load index of each heat load zone based on the zone temperature, temperature rise rate, coolant inlet temperature, coolant outlet temperature, liquid cooling heat exchange temperature difference, and temperature difference between adjacent zones. This module can be integrated into the compressor main controller, magnetic levitation controller, dedicated cooling controller, or industrial controller.

[0077] The levitation stability constraint module calculates the levitation stability index based on rotor displacement, rotor displacement change rate, and magnetic bearing control current. It then uses this index to determine whether the current cooling adjustment needs to enter a levitation stability constraint mode that restricts rapid changes in liquid cooling. This module can communicate with the magnetic bearing controller to read rotor displacement, current, and status flags.

[0078] The internal circulation liquid cooling actuator module includes a liquid storage unit, a liquid cooling pump, a heat exchanger, a bypass valve, multiple zone regulating valves, and zoned liquid cooling channels located inside the compressor head or in the casing interlayer. The liquid cooling pump provides the power for coolant circulation, the heat exchanger releases the heat absorbed by the coolant to the external environment or auxiliary cooling circuits, the zone regulating valves change the coolant flow rate in different heat load zones, and the bypass valves adjust the actual proportion of coolant entering the compressor head zoned liquid cooling channels when liquid cooling is too strong, anti-condensation, or suspension stability constraints are triggered.

[0079] The air-cooled compensation execution module includes an air-cooled fan, air-cooled zone dampers, and air-cooled compensation channels. The air-cooled compensation channels can be located around the circumference of the head housing, on the outside of the magnetic bearing housing, on the outside of the motor stator, or near the end cover, with their outlet positions corresponding to the heat load zones. The air-cooled zone dampers are used to adjust the airflow in different zones, and the air-cooled fan provides adjustable airflow.

[0080] The collaborative control module integrates the heat load index and the suspension stability index, outputting the target speed of the liquid-cooled pump, the target opening degree of the zone regulating valve, the target opening degree of the bypass valve, the target speed of the air-cooled fan, and the opening degree of the air-cooled zone damper. The fault degradation unit is used to perform alternative estimations, shut down abnormal liquid-cooling increments, increase air-cooling compensation, or output load reduction and shutdown protection commands when sensors or actuators malfunction.

[0081] III. Overall Technical Approach of Control Methods

[0082] like Figure 1 As shown, the control method of the present invention includes the following general route: First, a heat load zone is established based on the machine head structure and the location of the heat source; then, the temperature, coolant state, rotor displacement, and magnetic bearing control current are acquired through the zone acquisition module; next, the heat load index and suspension stability index of each heat load zone are calculated; then, the cooling demand is determined based on the heat load index, and whether the liquid cooling action can change rapidly is determined based on the suspension stability index; finally, the mode is switched between liquid cooling priority, air cooling compensation, ramp limiting, anti-condensation, and energy saving recovery.

[0083] The key to this invention lies not in simply adding liquid cooling or air cooling, but in making the liquid cooling and air cooling operations no longer independent. Liquid cooling, due to its strong heat exchange capacity, is suitable for handling basic heat dissipation and rapid cooling in the high heat flux density area of ​​the engine head. Air cooling, due to its gentle response and minimal impact on liquid pressure and localized thermal shock to the engine head, is suitable as a compensation method when the levitation stability is approaching warning levels, liquid cooling flow needs to be limited, anti-condensation control requires reducing liquid cooling intensity, or liquid cooling heat exchange is insufficient. Through this synergistic relationship, the adverse effects on magnetic levitation stability caused by the existing control method of simply increasing the coolant flow rate in response to a temperature increase can be avoided.

[0084] (a) Step S1: Establishment of heat load zones

[0085] Combination Figure 3 In step S1, the magnetic levitation compressor head is divided into multiple heat load zones according to the location of the heat source, the arrangement of the cooling channels, and the location of the magnetic levitation support within the compressor head. Preferably, the heat load zones include at least a motor stator zone, a rotor air gap zone, a front radial magnetic bearing zone, a rear radial magnetic bearing zone, and an axial magnetic bearing zone.

[0086] The stator section primarily corresponds to the motor windings and stator core area. Heat generation in this area mainly originates from copper losses, iron losses, and additional losses during high-speed operation. The rotor air gap section primarily corresponds to the rotor surface, air gap, and adjacent housing area. Temperature variations in this area can affect air gap uniformity, rotor thermal expansion, and motor magnetic field stability. The front and rear radial magnetic bearing sections correspond to the radial support positions at both ends of the rotor, respectively. Heat generation in this area mainly comes from magnetic bearing coil resistance losses and high-frequency control losses. The axial magnetic bearing section corresponds to the axial thrust control position; temperature variations in this area affect axial support stiffness and axial displacement control margin.

[0087] In practical implementation, the controller pre-establishes a partition mapping table. This table includes at least the partition number, partition name, temperature acquisition point number, internal circulation liquid cooling channel number, air-cooled compensation channel number, corresponding magnetic bearing number, corresponding rotor displacement direction, and corresponding control priority. For example, the motor stator partition can be assigned a higher thermal protection priority, the front and rear radial magnetic bearing partitions can be assigned a higher levitation stability priority, and the axial magnetic bearing partitions can be assigned a higher axial displacement protection priority. Through this mapping table, the controller can accurately assign the acquired temperature, flow rate, displacement, and current data to the corresponding heat load partition, avoiding misjudgments caused by multiple heat sources sharing a single temperature signal.

[0088] In terms of mechanical structure, the liquid cooling channels for each zone can adopt annular channels, spiral channels, axial channels, or partially jacketed channels. For the motor stator zone, the liquid cooling channel is preferably located in the stator housing or stator water jacket area; for the front radial magnetic bearing zone and the rear radial magnetic bearing zone, the liquid cooling channel is preferably located near the outer housing of the magnetic bearing coil; for the axial magnetic bearing zone, the liquid cooling channel is preferably located near the housing of the axial magnetic bearing end cover or thrust plate. The air-cooled compensation channel can adopt housing air duct, end cover air duct, zoned air guide shroud, or directional air jet structure to ensure that the compensation air volume can reach the heat load zone corresponding to the liquid cooling channel.

[0089] This step enables subsequent control to move beyond the overall temperature of the machine head or the temperature of a single motor point, and instead establish a zoned control system that is locatable, calculable, and differentially adjustable.

[0090] (II) Step S2: Acquisition and preprocessing of operating parameters

[0091] In step S2, the zone acquisition module acquires the zone temperature of each heat load zone. Coolant inlet temperature Coolant outlet temperature Coolant flow rate Rotor displacement Rotor displacement change rate Magnetic bearing control current And air-cooled outlet temperature .

[0092] To ensure stable and reliable control data, amplitude limiting, filtering, and validity checks can be performed on the acquired data before it enters the collaborative control module. Temperature signals can be filtered using a moving average or first-order low-pass filter. The rotor displacement signal can be directly output by the magnetic bearing controller as the high-frequency displacement average and displacement fluctuation amplitude. The magnetic bearing control current can be the average, peak, or root-mean-square value within the control cycle. The temperature rise rate can be calculated based on the temperature difference between adjacent sampling cycles.

[0093] ;

[0094] In the formula, For the i-th heat load zone in The rate of temperature rise over time; For the i-th heat load zone in Temperature of the zone at any given time; Let be the zone temperature of the i-th heat load zone at the previous sampling time; This represents the time interval between two adjacent samples.

[0095] The temperature difference in liquid cooling heat exchange can be calculated using the following formula:

[0096] ;

[0097] In the formula, For the i-th heat load zone, the corresponding internal circulation liquid cooling aisle is in The liquid cooling heat exchange temperature difference at any given moment; The coolant outlet temperature of the internal circulation liquid cooling channel corresponding to the i-th heat load zone; This refers to the coolant inlet temperature.

[0098] The rotor displacement change rate can be calculated using the following formula:

[0099] ;

[0100] In the formula, This represents the rotor displacement change rate corresponding to the i-th heat load zone; For the rotor corresponding to the i-th heat load zone in Displacement at any given moment; This represents the rotor displacement at the previous sampling time. This represents the time interval between two adjacent samples.

[0101] This step is a basic data acquisition step, and its contribution to creativity is lower than that of the subsequent exponent generation and constraint control steps, but it plays an important role in the feasibility of the solution. Those skilled in the art can implement this step based on the sampling period of the magnetic levitation compressor controller, the sensor type, and the communication protocol.

[0102] (III) Step S3: Generation of heat load index

[0103] like Figure 5 As shown, step S3 does not simply determine whether a certain temperature exceeds a threshold, but rather takes into account the temperature deviation of each zone, the rate of temperature rise, and the liquid cooling heat transfer deviation to generate the heat load index for each heat load zone. The heat load index is used to characterize the current cooling capacity requirement of the i-th heat load zone.

[0104] In a preferred embodiment, the heat load index of each heat load zone is calculated using the following formula:

[0105] ;

[0106] In the formula, For the i-th heat load zone in Heat load index at any given time; For the i-th heat load zone in Temperature of the zone at any given time; The target temperature for the i-th heat load zone; Let be the upper limit temperature allowed for the i-th heat load zone; Let be the temperature rise rate of the i-th heat load zone; Let be the allowable temperature rise rate for the i-th heat load zone; The liquid cooling heat exchange temperature difference of the internal circulation liquid cooling channel corresponding to the i-th heat load zone; Let be the target heat exchange temperature difference for the i-th heat load zone; This represents the upper limit of the allowable heat exchange temperature difference for the i-th heat load zone; , and These are the weighting coefficients for temperature deviation, temperature rise rate, and liquid cooling heat transfer deviation, respectively.

[0107] In the above formula, the first term reflects how close the zone temperature is to the target temperature and the allowable upper limit temperature. If... Gradually approaching The first indicator indicates an increased thermal risk in that zone, necessitating increased cooling capacity. The second indicator reflects the temperature rise trend; even if the current temperature has not yet exceeded the preset threshold, a high rate of temperature rise allows the system to increase cooling response in advance, preventing localized overheating caused by delayed temperature control. The third indicator reflects the liquid cooling heat exchange status; when the temperature difference between the liquid cooling outlet and inlet temperatures is significantly greater than the target heat exchange temperature difference, it indicates that the liquid cooling channel in that zone absorbs a large amount of heat, potentially leading to higher heat loads or a decrease in heat exchange margin.

[0108] Furthermore, in order to identify local hotspots and temperature imbalances between adjacent areas, this embodiment can also correct the heat load index based on the temperature gradient between adjacent heat load zones:

[0109] ;

[0110] In the formula, The heat load index is the corrected heat load index for the i-th heat load zone; The heat load index before correction for the i-th heat load zone; This is the temperature gradient correction factor; This is the set of heat load zones adjacent to the i-th heat load zone; For the i-th heat load zone in Temperature of the zone at any given time; For the j-th adjacent heat load zone in Temperature of the zone at any given time; This represents the allowable temperature gradient between the i-th heat load zone and the j-th heat load zone.

[0111] The significance of this correction lies in the fact that even if the temperature of a certain zone itself has not yet reached an overheated state, but a large temperature difference has already occurred between it and adjacent areas, it may lead to local thermal deformation of the machine head, stress concentration in the casing, or air gap misalignment. By incorporating the temperature gradient into the heat load index, this invention enables the control system to prioritize handling localized non-uniform thermal states, rather than passively cooling after the overall temperature rises.

[0112] In practical implementation, the controller can or It is compared with multiple thresholds. For example, when the heat load index is lower than the recovery threshold, the zone is in a low heat load state; when the heat load index is higher than the liquid cooling start threshold, the liquid cooling of the zone is started or enhanced; when the heat load index is higher than the air cooling compensation threshold, it is determined whether to increase the air cooling volume synchronously based on the suspension stability index; when the heat load index is higher than the high temperature protection threshold, the compressor can be triggered to reduce load, limit speed, or shut down for protection.

[0113] This step upgrades cooling control from single-point temperature feedback to zoned, multi-parameter, trend-based, and gradient-based heat load identification, providing a basis for subsequent liquid-cooling-air-cooling coordinated allocation.

[0114] (iv) Step S4: Generation of Suspension Stability Index

[0115] like Figure 5 As shown, step S4 is based on rotor displacement. Rotor displacement change rate and magnetic bearing control current Calculate the suspension stability index corresponding to each heat load zone. The suspension stability index is used to reflect whether the rotor suspension state near the corresponding zone is stable, and whether the liquid cooling system is currently allowed to perform rapid flow changes or valve opening changes.

[0116] In a preferred embodiment, the suspension stability index is calculated using the following formula:

[0117] ;

[0118] In the formula, For the i-th heat load zone in The moment-to-moment suspension stability index; This represents the rotor displacement corresponding to the i-th heat load zone; This corresponds to the target levitation position of the rotor; Permissible rotor displacement limits; The rotor displacement change rate; To limit the allowable rate of change of rotor displacement; The magnetic bearing control current corresponding to the i-th heat load zone; This is the corresponding magnetic bearing reference control current; To allow for the control current deviation limit of the magnetic bearing; , and These are the weighting coefficients for rotor displacement, rotor displacement change rate, and magnetic bearing control current, respectively.

[0119] In the above formula, the rotor displacement term reflects whether the rotor deviates from the target levitation position. The rotor displacement change rate term reflects whether the rotor motion state tends to change drastically. Even if the current displacement has not exceeded the limit, as long as the displacement change rate increases, it indicates that the system has a risk of levitation disturbance. The magnetic bearing control current term reflects the control margin consumed by the magnetic bearing to maintain levitation. When the magnetic bearing control current deviates significantly from the reference value, it may indicate that the rotor is affected by external disturbances, thermal deformation, or air gap misalignment, and it is necessary to avoid sudden changes in cooling flow to further aggravate the disturbance.

[0120] In existing magnetic levitation compressor cooling control, the cooling system often only receives temperature signals or motor temperature signals, while the magnetic bearing controller independently handles the rotor levitation problem. This invention introduces the levitation state into the cooling control, making the cooling system no longer an auxiliary system independent of magnetic levitation control, but rather a collaboratively controlled object constrained by levitation stability. Especially when the liquid cooling channel is close to the magnetic bearing, rotor air gap, or stator housing, a rapid increase in coolant flow can lead to rapid changes in local temperature differences, causing minor thermal deformation of the housing or uneven temperature in the air gap. If the rotor already has displacement deviation or the control current is too high at this time, continuing to rapidly increase liquid cooling may be detrimental to levitation stability. This invention addresses this issue by... This state can be identified in advance, thereby limiting liquid cooling operation and using air cooling compensation.

[0121] In practical implementation, the controller can be set with a levitation safety threshold, a levitation warning threshold, and a levitation shutdown threshold. When When the temperature is below the levitation safety threshold, this zone allows liquid cooling to be increased normally according to heat load demand; when... When the speed is above the suspension safety threshold but below the suspension warning threshold, the rate of change of liquid cooling pump speed and valve opening is slightly limited; when When the value exceeds the suspension warning threshold, the system enters suspension stability constraint mode; when When the suspension shutdown threshold is reached, a load reduction or shutdown protection command is output.

[0122] This step directly establishes a constraint relationship between thermal management and magnetic levitation stability control, which distinguishes this invention from existing solutions that adjust the cooling amount only based on temperature or refrigerant status.

[0123] (V) Step S5: Coordinated control of internal circulation liquid cooling and air cooling compensation

[0124] like Figure 6As shown, step S5 is based on the heat load index. and suspension stability index This process generates the internal circulation liquid cooling control quantity and air cooling compensation control quantity for each heat load zone. This step is crucial for achieving a balance between cooling efficiency and suspension stability in this invention.

[0125] When a certain heat load zone Above the liquid cooling start-up threshold, and corresponding When the coolant flow rate falls below the levitation safety threshold, it indicates that the affected zone has a high heat dissipation requirement, and the current levitation state allows for normal enhancement of the liquid cooling system. In this case, the controller prioritizes increasing the coolant flow rate in the corresponding zone's liquid cooling channel, or reduces the bypass valve opening to allow more coolant to enter the engine head zone's liquid cooling channel. This mode can be called liquid cooling priority mode.

[0126] When a certain heat load zone Above the liquid cooling start-up threshold, but When the temperature is not lower than the levitation safety threshold, it indicates that although the zone requires enhanced cooling, the corresponding levitation state is approaching or entering an unstable trend. In this case, the controller does not directly and rapidly increase the liquid cooling pump speed or valve opening, but instead limits the rate of change of liquid cooling action and prioritizes increasing the airflow in the air-cooling compensation channel. This mode can be called air-cooling compensation priority mode or liquid-cooling limited compensation mode.

[0127] In a preferred embodiment, the target opening degree of the zone control valve is... Determine by the following formula:

[0128] ;

[0129] In the formula, The target opening degree of the zone control valve for the i-th heat load zone; The reference opening degree of the zone control valve for the i-th heat load zone; This is the heat load gain coefficient; For the i-th heat load zone in Heat load index at any given time; Let be the liquid cooling start-up threshold for the i-th heat load zone; The levitation constraint gain coefficient; For the i-th heat load zone in The moment-to-moment suspension stability index; The levitation safety threshold; Indicates when Take when greater than 0 Otherwise, take 0; This means that the calculation results are limited to the minimum and maximum allowable opening of the zone control valve.

[0130] This formula embodies the control concept of this invention: the higher the heat load, the more the valve opening tends to increase; the higher the suspension stability index, the more the increase in valve opening is suppressed. In other words, liquid cooling does not simply increase indefinitely with rising temperature, but rather increases as needed under the constraint of suspension stability.

[0131] Target speed of air-cooled fan It can be determined by the following formula:

[0132] ;

[0133] In the formula, The target speed for the air-cooled fan; This is the reference speed for the air-cooled fan; This is the gain coefficient for heat load air cooling compensation; For the i-th heat load zone in Heat load index at any given time; The air-cooling compensation threshold for the i-th heat load zone; This is the gain coefficient for compensation of abnormal air cooling during suspension. For the i-th heat load zone in The moment-to-moment suspension stability index; The levitation safety threshold; Indicates when Take when greater than 0 Otherwise, take 0; Indicates when Take when greater than 0 Otherwise, take 0; This means that the calculation results are limited to the minimum and maximum allowable speeds of the air-cooled fan.

[0134] This formula reflects the dual role of air cooling: on the one hand, when the heat load in any heat load zone is high, air cooling provides auxiliary heat dissipation; on the other hand, when the suspension stability index increases and the liquid cooling action needs to be limited, air cooling assumes a compensatory function. Therefore, liquid cooling and air cooling are no longer two independent cooling systems, but rather form a complementary relationship.

[0135] In specific control operations, the collaborative control module can output control quantities according to the following rules: when higher and At lower speeds, the liquid cooling pump speed and the opening of the zone control valve increase according to the heat load demand, while the air cooling system maintains low or medium speed operation; when higher and When the pressure increases, the liquid cooling pump speed increases according to the limit curve, the opening of the zone regulating valve changes slowly, and at the same time, the air-cooled fan speed and the corresponding zone damper opening increase; when When the temperature difference between the two zones is consistently higher than the target and the liquid cooling pump is close to its limit, increase the airflow of the air-cooled compensation channel. When the temperature gradient between adjacent zones is large, increase liquid cooling or air cooling for the zone with higher temperature and avoid overcooling the zone with lower temperature.

[0136] This step maps the heat load demand and suspension stability constraints together into control quantities for two execution systems: liquid cooling and air cooling, forming a composite cooling control mechanism with synergistic effects.

[0137] (vi) Step S6: Suspension Stability Constraint Mode

[0138] Step S6 is a crucial step that distinguishes this invention from conventional liquid cooling or air cooling control. When the suspension stability index of any heat load zone... When the speed exceeds the suspension warning threshold, the collaborative control module enters the suspension stability constraint mode. In this mode, the controller implements ramp-up limits on the liquid cooling pump speed, the opening of the zone regulating valve, and the opening of the bypass valve, while increasing the speed of the air-cooled fan to reduce the disturbance of sudden changes in coolant flow to the rotor suspension state.

[0139] In a preferred embodiment, the rate of change of the liquid cooling pump speed satisfies:

[0140] ;

[0141] In the formula, This represents the rate of change of the liquid cooling pump speed. This refers to the maximum permissible rate of change of rotational speed for the liquid-cooled pump. The threshold for levitation shutdown; For the i-th heat load zone in The moment-to-moment suspension stability index; This is the floating safety threshold.

[0142] From the above formula, it can be seen that when near At that time, the liquid cooling pump still allows for adjustment at a relatively large rate of change; when Gradually approaching At this time, the rate of change of the liquid cooling pump speed is gradually compressed, thereby preventing the liquid cooling system from continuing to generate strong disturbances when the suspension state deteriorates.

[0143] Similarly, the rate of change of the opening of the zone control valve can satisfy:

[0144] ;

[0145] In the formula, Let be the rate of change of the opening degree of the zone control valve for the i-th heat load zone; The maximum allowable rate of change of opening of the zone control valve for the i-th heat load zone; The threshold for levitation shutdown; For the i-th heat load zone in The moment-to-moment suspension stability index; This is the floating safety threshold.

[0146] The bypass valve opening change rate can meet the following requirements:

[0147] ;

[0148] In the formula, The rate of change of the bypass valve opening; This refers to the maximum allowable rate of change of the bypass valve opening. The threshold for levitation shutdown; For the i-th heat load zone in The moment-to-moment suspension stability index; This is the floating safety threshold.

[0149] In the suspended stability constraint mode, if the heat load index remains high, the controller prioritizes compensation by increasing the speed of the air-cooled fan and opening the corresponding air-cooled zone dampers, rather than forcibly and rapidly increasing liquid cooling. If the temperature continues to rise and approaches the shutdown threshold, the controller can output a load reduction command to the compressor's main control system, causing the compressor to reduce its speed, reduce its load, or exit the high-risk operating condition. If the levitation shutdown threshold is reached, a shutdown protection command will be output.

[0150] The technical advantage of this step is that it ensures the cooling control actions conform to the stability requirements of the magnetically levitated rotor. Especially under high-speed operating conditions, even though liquid cooling has a stronger heat dissipation capacity, it cannot be allowed to change drastically in a way that could disturb the levitation state. The introduction of air-cooling compensation allows the system to maintain the necessary heat dissipation capacity while limiting changes in liquid cooling, thus balancing thermal safety and levitation stability.

[0151] (vii) Step S7: Energy-saving recovery mode

[0152] In step S7, when the heat load index of all heat load zones... Below the recovery threshold, and the suspension stability index After the temperature drops below the levitation safety threshold and remains stable for a preset time, the controller exits the levitation stability constraint mode and returns to the energy-saving cooling mode, following the order of decreasing liquid cooling flow rate first and then decreasing air cooling flow rate.

[0153] In this step, the liquid cooling speed is reduced first because it has a more direct impact on local temperature changes. If both liquid and air cooling speeds are reduced simultaneously, it may cause a local temperature rebound. Reducing the air cooling speed later allows it to continue providing gentle cooling during the liquid cooling speed reduction process, gradually balancing the temperature field at the compressor head. Preferably, during the reduction of the liquid cooling pump speed and the opening of the zone control valve, the controller continuously monitors the zone temperature, temperature rise rate, and temperature gradient between adjacent zones. If any heat load zone experiences a temperature rebound, the reduction is paused or the system re-enters the liquid-air cooling coordinated control mode.

[0154] In energy-saving cooling mode, the controller can maintain low-speed operation of the liquid-cooled pump, reference opening of the zone regulating valve, moderate opening of the bypass valve, and low-speed operation of the air-cooled fan to reduce energy consumption and noise. When the compressor enters high-load, rapid-speed-up, or high ambient temperature conditions, the system readjusts the cooling strategy according to the heat load index and suspension stability index.

[0155] (viii) Anti-condensation control

[0156] To prevent condensation from forming on the engine head surface or localized structures due to excessively low coolant temperature, this embodiment may also include an anti-condensation control step. The controller calculates the ambient dew point temperature based on the ambient temperature and relative humidity. And determine the lower limit temperature of liquid cooling. :

[0157] ;

[0158] In the formula, for The lower limit temperature of liquid cooling at any given time; for The ambient dew point temperature at any given time; To prevent condensation, a safe temperature difference is required.

[0159] When the coolant inlet temperature Below When this happens, the controller increases the bypass valve opening, reduces the liquid cooling pump speed, or decreases the proportion of coolant entering the corresponding zone's liquid cooling channel, while maintaining heat dissipation through the air-cooled compensation channel. This prevents the compressor head surface temperature from falling below the dew point temperature due to excessive liquid cooling, reducing the impact of condensation on electrical insulation, magnetic bearing coils, and sensor reliability.

[0160] (ix) Fault Degradation Control

[0161] like Figure 7 As shown, this embodiment also includes fault degradation control. If a certain temperature acquisition point is abnormal, such as the acquired value exceeding the physical reasonable range, remaining unchanged for a long time, or having an abnormal temperature difference with adjacent zones, the controller uses the temperature of adjacent heat load zones, coolant outlet temperature, and magnetic bearing control current to estimate the heat load index of the corresponding heat load zone, and marks that zone as a degraded state.

[0162] If the rotor displacement sensor malfunctions, the controller uses magnetic bearings to control the current. Magnetic bearing control current change rate Estimating the suspension stability index using rotor vibration signals The rate of change of the magnetic bearing control current can be calculated using the following formula:

[0163] ;

[0164] In the formula, Let be the rate of change of the magnetic bearing control current corresponding to the i-th heat load zone; for The magnetic bearing control current at any given moment; This represents the magnetic bearing control current at the previous sampling time. This represents the time interval between two adjacent samples.

[0165] If the liquid cooling pump, zone regulating valve, or bypass valve malfunctions, the controller will shut down the liquid cooling incremental regulation of the malfunctioning zone and increase the airflow of the corresponding air-cooled compensation channel. If the suspension stability index reaches the suspension shutdown threshold, the controller will output a compressor load reduction or shutdown protection command.

[0166] Through fault degradation control, this invention can maintain basic heat dissipation and levitation protection capabilities when some acquisition units or actuators are abnormal, avoiding the complete failure of the cooling system due to a single point of failure.

[0167] IV. Specific Application Examples and Experimental Data

[0168] (I) Experimental Objectives and Experimental Platform

[0169] To verify the technical effectiveness of the present invention's method and system for coordinated control of internal circulation liquid cooling and air cooling in a magnetic levitation compressor head based on thermal load zoning and suspension stability constraints, the applicant constructed a thermal management test platform for a magnetic levitation centrifugal compressor head. The test platform includes a magnetic levitation compressor head, a frequency converter, a magnetic bearing controller, an internal circulation liquid cooling circuit, an air cooling compensation circuit, a temperature acquisition system, a coolant flow acquisition system, a rotor displacement acquisition system, a magnetic bearing control current acquisition system, and a host computer data recording system.

[0170] The magnetic levitation compressor head is according to Figure 3 The circuit is divided into four zones: stator zone, rotor air gap zone, front radial magnetic bearing zone, rear radial magnetic bearing zone, and axial magnetic bearing zone. Temperature acquisition points are set up in each zone, and coolant outlet temperature acquisition points are also set up at the outlet of the corresponding liquid cooling branch. The internal circulation liquid cooling circuit is configured according to... Figure 4The configuration shown includes a liquid storage unit, a liquid-cooled pump, a heat exchanger, a bypass valve, a zone regulating valve, and a zoned liquid-cooled channel; the air-cooled compensation circuit includes an air-cooled fan, an air-cooled zone damper, and an air-cooled compensation channel. The control system is based on... Figure 2 The system receives data on the temperature of each zone, the inlet and outlet temperatures of the coolant, the coolant flow rate, the rotor displacement, the rate of change of rotor displacement, and the magnetic bearing control current in the manner shown, and follows the instructions. Figure 5 , Figure 6 The logic shown generates the heat load index. Suspension stability index And the corresponding control commands.

[0171] During the test, the compressor head was set to three typical operating conditions: the first was a steady-state medium-load condition, used to verify the effect of the invention on the balanced control of the compressor head zone temperature; the second was a step-load condition, used to verify the invention's response capability to local rapid temperature rise; and the third was a suspension disturbance condition, used to verify the invention's ability to limit the liquid cooling action and use air cooling compensation when the suspension stability index increases.

[0172] (ii) Proportional Setting

[0173] To illustrate the technical effects of the present invention, the following comparative examples and embodiments are provided.

[0174] Comparative Example 1 uses a single air-cooling control method. This method only adjusts the speed of the air-cooled fan according to the temperature of the motor stator zones, without setting up an internal circulating liquid cooling loop, or establishing a heat load zoning index and a suspension stability index.

[0175] Comparative Example 2 uses a single liquid cooling control method. This method adjusts the liquid cooling pump speed according to the temperature of the motor stator zones and adjusts the bypass valve opening according to the average temperature of the compressor head, but does not perform suspension stability constraints on the liquid cooling action based on rotor displacement, rotor displacement change rate, and magnetic bearing control current, nor does it set priority logic for air cooling compensation.

[0176] Comparative Example 3 employs a parallel control method for liquid cooling and air cooling. This method simultaneously sets up liquid cooling and air cooling, but the two operate independently based on temperature thresholds. When the temperature rises, the speed of the liquid cooling pump and the speed of the air cooling fan are increased simultaneously. It does not perform zoned adjustment based on differences in heat load zones, nor does it limit the rate of change of liquid cooling based on the suspension stability index.

[0177] Example 1 employs the control method of the present invention. This method is based on... Figure 1 The process shown involves first establishing heat load zones, and then calculating the heat load index for each zone. and suspension stability index And based on the coordinated adjustment of the two, the liquid cooling pump speed, the opening of the zone control valve, the opening of the bypass valve, the air-cooled fan speed, and the opening of the air-cooled zone damper. When rise and When the temperature is below the levitation safety threshold, liquid cooling is preferentially enhanced; when... rise and When the pressure is not lower than the levitation safety threshold, the liquid cooling action is limited by ramping, and the air volume of the corresponding air cooling compensation channel is increased.

[0178] (III) Evaluation Indicators

[0179] The following indicators were mainly used in this experiment to evaluate the cooling control effect and the suspension stability effect:

[0180] 1. Highest zone temperature at the test head indicates the maximum temperature of each heat load zone during the test;

[0181] 2. Maximum zone temperature gradient, representing the maximum temperature difference between adjacent heat load zones;

[0182] 3. Temperature stabilization time, which indicates the time required for the temperature of each zone to enter a stable fluctuation range after the compressor is subjected to a step load;

[0183] 4. Maximum radial displacement deviation, which represents the maximum deviation of the radial rotor displacement relative to the target suspension position;

[0184] 5. Peak value of magnetic bearing control current, which represents the maximum control current when the magnetic bearing maintains a levitated state;

[0185] 6. Comprehensive energy consumption of the cooling system, which represents the total power consumption of the liquid cooling pump and the air-cooled fan during the test period.

[0186] Among them, the maximum zone temperature gradient Calculate according to the following formula:

[0187] ;

[0188] In the formula, The maximum zone temperature gradient; For the i-th heat load zone in Temperature at any moment; For the j-th adjacent heat load zone in Temperature at any moment; Let i be the set of heat load zones adjacent to the i-th heat load zone.

[0189] (iv) Application Example 1: Zone Temperature Equalization Test under Steady-State Load Conditions

[0190] This application example verifies the invention's ability to maintain a balanced temperature distribution in the compressor head during steady-state load operation. In the experiment, the magnetic levitation compressor head operated continuously at a set speed and stable load, with an ambient temperature of 25°C and an initial coolant inlet temperature of 28°C. All scenarios were tested under the same compressor head, environment, and operating time.

[0191] The experimental results are shown in Table 1.

[0192] Table 1 Temperature control results under different control methods under steady-state medium load conditions.

[0193]

[0194] As shown in Table 1, under steady-state load conditions, the highest zone temperature of the machine head in Example 1 is 61.9℃, which is lower than that of Comparative Example 1 (78.6℃), Comparative Example 2 (69.8℃), and Comparative Example 3 (66.5℃). The maximum zone temperature gradient in Example 1 is 6.2℃, which is significantly lower than that of Comparative Example 1 (18.4℃), Comparative Example 2 (13.7℃), and Comparative Example 3 (10.9℃). This demonstrates that the present invention... Figure 3 The heat load zones shown are Figure 5 The heat load index calculation logic shown can identify the heat load differences between different zones, and through... Figure 4 The partitioned liquid cooling channel and air cooling compensation channel are used for differentiated cooling, thereby reducing local hot spots and temperature unevenness in the head section.

[0195] Meanwhile, the overall energy consumption of the cooling system in Example 1 is 1.68 kWh, lower than the 2.11 kWh of Comparative Example 3. This is because the present invention does not simply increase liquid cooling and air cooling simultaneously as the temperature rises, but rather adjusts the cooling system based on the heat load index of each zone. and suspension stability index By allocating liquid cooling and air cooling outputs, liquid cooling is prioritized for heat dissipation in areas with high heat flux density, while low heat load areas maintain a lower cooling intensity, thereby reducing unnecessary energy consumption of fans and liquid cooling pumps.

[0196] Figure 8 This is a temperature comparison curve of the motor stator zone, rotor air gap zone, front radial magnetic bearing zone, rear radial magnetic bearing zone, and axial magnetic bearing zone under steady-state load conditions.

[0197] (V) Application Example 2: Rapid Temperature Rise Response Test under Step Loading Condition

[0198] This application example verifies the invention's response to localized temperature rises when the compressor load increases rapidly. In the experiment, the compressor head initially operated at low to medium loads. After the temperatures of each heat load zone stabilized, the compressor load was increased rapidly within a short period, causing a rapid temperature rise in the motor stator zone and the rear radial magnetic bearing zone. The experiment continuously recorded the zone temperature, coolant heat exchange temperature difference, liquid-cooled pump speed, zone control valve opening, and air-cooled fan speed.

[0199] The test results are shown in Table 2.

[0200] Table 2 Dynamic response results of different control methods under step loading conditions

[0201]

[0202] As shown in Table 2, under the step loading condition, Comparative Example 1, due to the use of only air cooling, has insufficient heat exchange intensity, and the highest temperature after the step reaches 86.3℃, while the highest temperature of the rear radial magnetic bearing reaches 82.7℃. Although Comparative Example 2 uses liquid cooling, it does not perform zoned heat load identification, resulting in a lag in the local temperature rise response of the rear radial magnetic bearing zone. Although Comparative Example 3 improves both liquid cooling and air cooling, it does not distinguish between different heat load zones, resulting in some zones being over-cooled while hot spots are under-cooled.

[0203] Example 1: After step loading, the heat load index of each zone was calculated. It can identify the increasing trend of temperature rise rate in the rear radial magnetic bearing section and the motor stator section; and simultaneously combine the liquid cooling heat exchange temperature difference. The system determines that the heat load of the corresponding liquid cooling channel is increasing, and therefore prioritizes increasing the opening of the corresponding zone's regulating valve and appropriately increasing the liquid cooling pump speed. When the local heat load is high but the suspension stability index does not exceed the suspension safety threshold, the present invention enables the liquid cooling system to quickly intervene; when the local temperature gradient is large, the hot spot zone is compensated with air cooling through the air cooling zone damper. Therefore, the highest temperature after the step change in Example 1 is only 64.7℃, the maximum temperature rise rate is reduced to 2.4℃ / min, and the temperature stabilization time is shortened to 12.6min.

[0204] It is recommended to add this information to the instruction manual. Figure 9 , Figure 9 This can be named as a schematic diagram of the change in heat load index and zone control valve opening under step loading conditions in an embodiment of the present invention. Figure 9 The center can display the rear radial magnetic bearing partition. As the temperature gradient increases, the opening of the corresponding zone control valve also increases, while the damper of the air-cooled zone opens synchronously as the temperature gradient increases. This figure can be used to demonstrate that the present invention is not simply based on single-point temperature control, but rather on directional adjustment based on the zone heat load index.

[0205] (vi) Application Example 3: Liquid Cooling Limitation and Air Cooling Compensation Test under Suspension Disturbance Conditions

[0206] This application example verifies that the present invention can limit drastic actions of the liquid cooling system and maintain heat dissipation capacity through air-cooling compensation when the magnetic levitation rotor experiences displacement fluctuations or the magnetic bearing control current increases. In the experiment, when the compressor head was operating under high load, changes in load and minor disturbances on the intake side increased the radial displacement fluctuation of the rotor corresponding to the rear radial magnetic bearing section, causing the magnetic bearing control current to show an upward trend. The maximum radial displacement deviation, peak magnetic bearing control current, liquid cooling pump speed change rate, and rear radial magnetic bearing section temperature were recorded under different control modes.

[0207] The test results are shown in Table 3.

[0208] Table 3 Suspension stability results under different control methods during suspension disturbance conditions.

[0209]

[0210] As shown in Table 3, under the suspension disturbance condition, Comparative Examples 2 and 3 continued to rapidly increase the liquid cooling pump speed or liquid cooling flow rate after detecting a temperature increase. The maximum speed change rate of the liquid cooling pump reached 165 rpm / s and 142 rpm / s, respectively, leading to rapid changes in the local heat exchange conditions of the compressor head, and large fluctuations in the rotor radial displacement deviation and magnetic bearing control current. Example 1 passed... Figure 6 The suspension stability constraint mode shown has a suspension stability index. When the speed exceeds the suspension safety threshold, the ramp speed of the liquid cooling pump is reduced according to the limit rule of the liquid cooling pump speed change rate, and the air volume of the air-cooled compensation channel is increased, so that the maximum speed change rate of the liquid cooling pump is reduced to 58 rpm / s, while the maximum radial displacement deviation is controlled at 16.8 μm and the peak value of the magnetic bearing control current is controlled at 6.4A.

[0211] Under this operating condition, the highest temperature of the radial magnetic bearing after Example 1 was 64.5°C, which was still lower than that of Comparative Examples 2 and 3. This shows that the present invention does not sacrifice cooling effect for suspension stability, but rather maintains the necessary heat dissipation capacity while reducing liquid cooling abrupt disturbances through a combination of liquid cooling limiting and air cooling compensation.

[0212] Figure 10 This is a comparison chart of rotor displacement deviation and liquid cooling pump speed changes under suspension disturbance conditions between embodiments and comparative examples of the present invention. Figure 10 It may include two or more curves: one type of curve represents the change of rotor displacement deviation over time, and another type of curve represents the change of liquid cooling pump speed over time, which is used to prove that the present invention can suppress rapid liquid cooling ramp-up and reduce rotor displacement fluctuation when the suspension state deteriorates.

[0213] (vii) Application Example 4: Anti-condensation and Energy-saving Recovery Test

[0214] This application example verifies the anti-condensation control effect of the present invention under conditions of high ambient humidity and low coolant inlet temperature, as well as its energy-saving recovery effect after load reduction. In the experiment, the ambient temperature was 26°C and the relative humidity was 75%. The compressor initially operated under high load, then decreased to a medium-low load. Comparative Example 2 still reduced the liquid cooling pump speed according to temperature, but did not set an anti-condensation lower limit control; Example 1 calculated the liquid cooling lower limit temperature according to the anti-condensation control steps of the present invention. When the coolant inlet temperature When the temperature is below the liquid cooling lower limit, increase the bypass valve opening and increase the air cooling compensation ratio.

[0215] The test results are shown in Table 4.

[0216] Table 4 Results of different control methods under anti-condensation and energy-saving recovery conditions

[0217]

[0218] Table 4 shows that Comparative Example 2 exhibited condensation under high humidity and low coolant inlet temperature conditions, with the lowest compressor head wall temperature reaching 18.7℃. While Comparative Example 3 experienced some relief from condensation due to air cooling, slight condensation still occurred in some areas. Example 1 determined the lower limit temperature for liquid cooling based on the ambient dew point temperature and the safe temperature difference for preventing condensation. When the coolant inlet temperature is below this lower limit, the liquid cooling intensity is reduced by increasing the opening of the bypass valve, and the heat dissipation is maintained by the air-cooled compensation channel. Therefore, no condensation phenomenon was observed.

[0219] Furthermore, during the recovery phase after load reduction, Comparative Examples 2 and 3, due to their relatively simple cooling system reduction strategies, were prone to localized temperature rebounds after liquid or air cooling was discontinued. Example 1, by discontinuing the enhanced cooling state in the order of first reducing liquid cooling flow rate and then air cooling airflow, controlled the temperature rebound after load reduction to 2.1℃, while the energy consumption during the recovery phase was 0.69 kWh, lower than Comparative Examples 2 and 3. This result demonstrates that the present invention not only improves heat dissipation under high loads but also balances temperature stability and energy saving during the low-load recovery phase.

[0220] Figure 11 This is a schematic diagram showing the changes in liquid cooling inlet temperature, liquid cooling lower limit temperature, and bypass valve opening under anti-condensation and energy-saving recovery conditions in an embodiment of the present invention. Figure 11 Used to illustrate when Close to or below At this time, the bypass valve opening increases, the air-cooling compensation is enhanced, thereby avoiding condensation.

[0221] (viii) Comprehensive technical effect analysis

[0222] As can be seen from the above application examples 1 to 4, the present invention achieves at least the following technical effects.

[0223] First, this invention can reduce the highest zone temperature of the compressor head. In Example 1, the highest zone temperature under steady-state load conditions is 61.9℃, which is 16.7℃ lower than 78.6℃ with single air cooling, 7.9℃ lower than 69.8℃ with single liquid cooling, and 4.6℃ lower than 66.5℃ with parallel control of liquid and air cooling. This demonstrates that this invention, through heat load zoning and zone cooling control, can more effectively reduce the temperature of high heat flux density areas of the compressor head.

[0224] Second, the present invention can reduce the temperature gradient in different zones. The maximum temperature gradient in zone 1 of Example 1 is 6.2℃, which is significantly lower than that of Comparative Examples 1, 2 and 3, indicating that the present invention can reduce the local temperature difference in the head and reduce the risk of local thermal deformation and air gap misalignment.

[0225] Third, this invention can improve the temperature response speed under step loading. In Example 1, the temperature stabilization time under step loading is 12.6 min, which is significantly shorter than the 19.5 min of Comparative Example 2 and the 17.4 min of Comparative Example 3, indicating that the heat load index... It can identify the rate of temperature rise and heat transfer deviation in advance, thereby improving the timeliness of cooling response.

[0226] Fourth, this invention can reduce the disturbance to suspension stability caused by liquid cooling. In Example 1, the maximum radial displacement deviation under suspension disturbance conditions was 16.8 μm, lower than 28.6 μm in Comparative Example 2 and 25.4 μm in Comparative Example 3; the peak value of the magnetic bearing control current was 6.4 A, lower than 8.9 A in Comparative Example 2 and 8.2 A in Comparative Example 3. These results demonstrate that this invention reduces the impact of liquid cooling on suspension stability. Limiting liquid cooling ramps and maintaining heat dissipation through air cooling compensation can improve magnetic levitation stability while ensuring cooling performance.

[0227] Fifth, this invention can reduce the risk of condensation and improve the energy-saving recovery process. In Example 1, no condensation was observed under high humidity and low coolant temperature conditions, and the temperature rebound after the load decreased was only 2.1°C, indicating that the anti-condensation control and the energy-saving recovery strategy of reducing the load first for liquid cooling and then for air cooling can improve system reliability and operational stability.

[0228] The foregoing description of embodiments of the present invention, through which those skilled in the art are able to implement or use the present invention, will be readily apparent to those skilled in the art. Various modifications to these embodiments will be readily apparent to those skilled in the art. The general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novelty disclosed herein.

[0229] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0230] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0231] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0232] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0233] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0234] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0235] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

Claims

1. A magnetic suspension compressor head internal circulation liquid cooling-air cooling collaborative control method, characterized in that, The method includes the following steps: S1. According to the location of the heat source, the arrangement of the cooling channel and the location of the magnetic levitation support in the magnetic levitation compressor head, the magnetic levitation compressor head is divided into multiple heat load zones. The heat load zones include at least the motor stator zone, the rotor air gap zone, the front radial magnetic bearing zone, the rear radial magnetic bearing zone and the axial magnetic bearing zone. A corresponding temperature acquisition point, an internal circulation liquid cooling channel and an air cooling compensation channel are established for each heat load zone. S2, collect the zone temperature of each heat load zone. Coolant inlet temperature Coolant outlet temperature Coolant flow rate Rotor displacement Rotor displacement change rate Magnetic bearing control current And air-cooled outlet temperature ; S3, based on the temperature deviation, temperature rise rate, and liquid cooling heat transfer deviation of each heat load zone, calculate the heat load index of each heat load zone. ; S4, based on , and , calculate the suspension stability index corresponding to each thermal load partition ; S5, according to and Generate the internal circulation liquid cooling control quantity and air cooling compensation control quantity for each heat load zone; when Higher than the liquid cooling start-up threshold and When the coolant flow rate is below the levitation safety threshold, prioritize increasing the coolant flow rate in the corresponding internal circulation liquid cooling channel or reducing the bypass ratio; when Higher than the liquid cooling start-up threshold and When the flow rate is not lower than the suspension safety threshold, the rate of increase of coolant flow is limited, and the air volume of the corresponding air-cooled compensation channel is increased first. S6, when any heat load zone When the speed exceeds the suspension warning threshold, the system enters the suspension stability constraint mode. Under this mode, the liquid cooling pump speed, the opening of the zone regulating valve, and the opening of the bypass valve are limited, while the air-cooled fan speed is increased to reduce the disturbance of the rotor suspension state caused by sudden changes in coolant flow. S7, when all heat load zones are... Below the recovery threshold and After the temperature drops below the levitation safety threshold and remains stable for a preset time, the system exits the levitation stability constraint mode and returns to the energy-saving cooling mode, following the order of decreasing liquid cooling flow rate first and then decreasing air cooling flow rate.

2. The control method according to claim 1, characterized in that, In step S1, the multiple heat load zones are mapped according to the axial position of the machine head and the type of heat source. The mapping table includes at least the zone number, temperature acquisition point number, internal circulation liquid cooling channel number, air cooling compensation channel number, corresponding magnetic bearing number, and corresponding rotor displacement direction. Among them, the front radial magnetic bearing zone and the rear radial magnetic bearing zone correspond to the radial displacement signal, the axial magnetic bearing zone corresponds to the axial displacement signal, and the motor stator zone and the rotor air gap zone correspond to the winding temperature and the air gap temperature, respectively.

3. The control method according to claim 1 is characterized in that, In step S3, the heat load index satisfy: ； In the formula, For the i-th heat load zone in Heat load index at any given time; For the i-th heat load zone in The zone temperature at any given time; The target temperature for the i-th heat load zone; Let be the upper limit temperature allowed for the i-th heat load zone; Let be the temperature rise rate of the i-th heat load zone; Let be the allowable temperature rise rate for the i-th heat load zone; The difference between the coolant outlet temperature and the coolant inlet temperature in the internal circulation liquid cooling channel corresponding to the i-th heat load zone; Let be the target heat exchange temperature difference for the i-th heat load zone; This represents the upper limit of the allowable heat exchange temperature difference for the i-th heat load zone; , and These are the weighting coefficients for temperature deviation, temperature rise rate, and liquid cooling heat transfer deviation, respectively. And / or, in step S3, the heat load index is further corrected based on the temperature gradient between adjacent heat load zones. The corrected heat load index is obtained. : In the formula, The heat load index is the corrected heat load index for the i-th heat load zone; The heat load index before correction for the i-th heat load zone; This is the set of heat load zones adjacent to the i-th heat load zone; For the i-th heat load zone in The zone temperature at any given time; For the j-th heat load zone in The zone temperature at any given time; This represents the allowable temperature gradient between the i-th heat load zone and the j-th heat load zone; This is the temperature gradient correction factor; And / or, in step S3, the suspension stability index satisfy: ； In the formula, For the i-th heat load zone in The moment-to-moment suspension stability index; This represents the rotor displacement corresponding to the i-th heat load zone; This corresponds to the target levitation position of the rotor; Permissible rotor displacement limits; The rotor displacement change rate; To limit the allowable rate of change of rotor displacement; The magnetic bearing control current corresponding to the i-th heat load zone; This corresponds to the magnetic bearing reference control current; To allow for the control current deviation limit of the magnetic bearing; , and These are the weighting coefficients for rotor displacement, rotor displacement change rate, and magnetic bearing control current, respectively.

4. The control method according to claim 1, characterized in that, In step S5, the internal circulation liquid cooling control quantity includes the target rotational speed of the liquid cooling pump. Target opening degree of zone control valve and bypass valve target opening Among them, the target opening degree of the zone control valve Determine as follows: ； In the formula, The target opening degree of the zone control valve for the i-th heat load zone; The reference opening degree of the zone control valve for the i-th heat load zone; This is the heat load gain coefficient; For the i-th heat load zone in Heat load index at any given time; Let be the liquid cooling start-up threshold for the i-th heat load zone; The levitation constraint gain coefficient; For the i-th heat load zone in The moment-to-moment suspension stability index; The levitation safety threshold; Indicates when Take when greater than 0 Otherwise, take 0; This means that the calculation results are limited to the minimum and maximum allowable opening of the zone control valve; And / or, in step S5, the air-cooling compensation control quantity includes the target speed of the air-cooled fan. Air-cooled zone damper opening And the start-up time of air-cooled compensation, including the target speed of the air-cooled fan. Determine as follows: ； In the formula, The target speed for the air-cooled fan; This is the reference speed for the air-cooled fan; This is the gain coefficient for heat load air cooling compensation; For the i-th heat load zone in Heat load index at any given time; The air-cooling compensation threshold is the threshold value for the i-th heat load zone. This is the gain coefficient for compensation of abnormal air cooling during suspension. For the i-th heat load zone in The moment-to-moment suspension stability index; The levitation safety threshold; Indicates when Take when greater than 0 Otherwise, take 0; Indicates when Take when greater than 0 Otherwise, take 0; This means that the calculation results are limited to the minimum and maximum allowable speeds of the air-cooled fan.

5. The control method according to claim 1, characterized in that, In step S6, the ramp-up limit includes the limit on the rate of change of liquid cooling pump speed, the limit on the rate of change of zone control valve opening, and the limit on the rate of change of bypass valve opening; when the suspension stability index Above the levitation safety threshold And below the hovering shutdown threshold At that time, the rate of change of the liquid cooling pump speed should satisfy: ； In the formula, This represents the rate of change of the liquid cooling pump speed. This refers to the maximum permissible rate of change of rotational speed for the liquid-cooled pump. The threshold for levitation shutdown; For the i-th heat load zone in The moment-to-moment suspension stability index; The levitation safety threshold; when The closer The smaller the rate of change of the liquid cooling pump speed is limited, the better; And / or, in step S7, the energy-saving cooling mode includes: [the following is unclear due to incomplete sentence fragment: "at heat load index"] Below the recovery threshold and the rate of temperature rise When the temperature rise rate is less than the preset threshold, first reduce the liquid cooling pump speed and the opening of the zone regulating valve according to the preset descent slope; at the coolant outlet temperature With zone temperature After the heat exchange temperature difference between them stabilizes, the speed of the air-cooled fan is reduced according to the preset downward slope to avoid the local temperature rebound of the machine head caused by the simultaneous decrease of the internal circulation liquid cooling and air cooling.

6. The control method according to claim 1, characterized in that, It also includes anti-condensation control steps: based on the ambient dew point temperature. Determine the lower limit temperature of liquid cooling based on the lowest wall temperature of the compressor head. When the coolant inlet temperature Below the liquid cooling lower limit temperature At this time, increase the bypass valve opening or reduce the liquid cooling pump speed, and maintain heat dissipation through the air-cooled compensation channel; among which, the lower limit temperature of liquid cooling Determine as follows: ； In the formula, for The lower limit temperature of liquid cooling at any given time; for The ambient dew point temperature at any given time; To prevent condensation, a safe temperature difference is required.

7. A magnetic levitation compressor head internal circulating liquid cooling-air cooling coordinated control system, characterized in that, include: The zone acquisition module is used to acquire the zone temperature of the motor stator zone, rotor air gap zone, front radial magnetic bearing zone, rear radial magnetic bearing zone, and axial magnetic bearing zone. Coolant inlet temperature Coolant outlet temperature Coolant flow rate Rotor displacement Rotor displacement change rate Magnetic bearing control current And air-cooled outlet temperature ; The heat load zoning calculation module is used to calculate the heat load index of each heat load zone based on the temperature deviation, temperature rise rate, liquid cooling heat transfer deviation, and temperature gradient between adjacent heat load zones. ; The suspension stability constraint module is used to determine the rotor displacement. Rotor displacement change rate and magnetic bearing control current Calculate the suspension stability index for each heat load zone. And determine whether to enter the suspension stability constraint mode; The internal circulation liquid cooling actuator module includes a liquid storage unit, a liquid cooling pump, a heat exchanger, a zone regulating valve, a bypass valve, and zoned liquid cooling channels located within the compressor head, used to adjust the cooling output according to the heat load index. and suspension stability index Adjusting the coolant flow rate Zone control valve opening and bypass valve opening ; The air-cooled compensation execution module includes an air-cooled fan, an air-cooled partition damper, and an air-cooled compensation channel set in the head unit. It is used to perform air-cooled compensation on the corresponding heat load partition when liquid cooling is limited by suspension stability constraints, liquid cooling heat exchange is insufficient, or anti-condensation control is triggered. A collaborative control module is used to execute the control method according to any one of claims 1 to 6 and output the target speed of the liquid cooling pump. Target opening degree of zone control valve Target opening degree of bypass valve Target speed of air-cooled fan Air-cooled partition damper opening .

8. The control system according to claim 7, characterized in that, The collaborative control module includes a fault degradation unit, which is configured as follows: When the temperature acquisition point is abnormal, the zone temperature of the adjacent heat load zone is used. Coolant outlet temperature and magnetic bearing control current Estimate the heat load index of the corresponding heat load zone ; When the rotor displacement sensor malfunctions, the magnetic bearing control current is used. Magnetic bearing control current change rate Estimating the suspension stability index using rotor vibration signals ; When the liquid cooling pump, zone regulating valve or bypass valve malfunctions, shut down the liquid cooling increment regulation of the malfunctioning zone and increase the airflow of the corresponding air cooling compensation channel. When the suspension stability index Reaching the hovering shutdown threshold When necessary, output a compressor load reduction or shutdown protection command.

9. An electronic device, characterized in that, The method includes a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, it implements the method according to any one of claims 1 to 6.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the method described in any one of claims 1 to 6.

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