Permanent magnet synchronous motor direct drive centrifugal compressor unit

Abstract

The utility model discloses a centrifugal compressor unit of permanent magnet synchronous motor direct drive, aims at solving the problem of low energy efficiency, high maintenance cost, bulky and noise pollution of traditional asynchronous motor and gear box drive centrifugal compressor unit. The machine set permanent magnet synchronous motor rotor shaft directly drives compressor three element milling impeller. Motor configuration active magnetic suspension bearing, no mechanical contact, long life. Motor, compressor and embedded lubricating oil station are integrated in public base. It can cooperate frequency converter to realize stepless speed regulation of rated speed, and compressor shaft end is provided with dry gas seal. The utility model has high industrial gas compression transmission efficiency, and system energy efficiency is improved compared with traditional machine set, land occupation is reduced, and running noise is small, and is suitable for multiple medium compression scene.

Description

Technical Field

[0001] This utility model belongs to the field of industrial gas compression, specifically relating to a centrifugal compressor unit directly driven by a permanent magnet synchronous motor. Background Technology

[0002] Centrifugal compressor units, as key power equipment in industrial gas compression, large-scale air conditioning and refrigeration, heat pump systems, and air separation, directly impact the energy costs and production stability of downstream industries due to their operational efficiency, reliability, and compactness. Currently, mainstream centrifugal compressor units in the industry generally employ a traditional drive structure using an asynchronous motor and gearbox. This structure requires the asynchronous motor to provide power, and then relies on the gearbox's speed reduction / increase function to match the speed requirements of the motor and compressor impeller. It also requires an independent lubrication station, cooling system, and distributed mounting base to meet the unit's operational needs. However, this traditional structure has gradually revealed several technical shortcomings in long-term application, making it difficult to adapt to the current industrial sector's upgrade requirements for efficient, low-consumption, and compact equipment. Specific problems include:

[0003] (1) High intermediate transmission losses and low system energy efficiency. During operation, the gearbox generates mechanical friction loss, wind resistance loss and oil churning loss, resulting in low overall transmission efficiency. At the same time, the asynchronous motor needs to generate a magnetic field through excitation current, resulting in high rotor copper loss. In addition, traditional units mostly adopt constant speed drive mode, which requires throttling or bypass adjustment through inlet guide vanes to achieve flow control. This method will cause additional throttling losses, further deteriorating energy efficiency under variable load conditions.

[0004] (2) Complex structure, high maintenance cost and poor reliability. As a core transmission component, the gearbox has inherent risks of failure such as gear wear, tooth surface fatigue and bearing failure. It needs to be disassembled for inspection and replacement of gear oil and filter elements regularly, resulting in high maintenance costs and long downtime. At the same time, the gearbox needs to be equipped with an independent lubrication station, which is separate from the lubrication system of the motor and compressor. This leads to complex pipeline layout and problems such as oil leakage and oil circuit blockage, which further increases the risk of failure. In addition, the motor, compressor and lubrication station of traditional units are mostly installed on a decentralized base. On-site coaxiality calibration of multiple devices is required. Assembly deviation is difficult to control. Vibration coupling is easy to occur during operation, which aggravates the wear of bearings and seals and shortens the service life of the whole machine.

[0005] (3) Large size and high installation space requirements. The distributed base design requires the motor, compressor and independent lubrication station to occupy separate sites, and pipelines and maintenance space need to be reserved between each piece of equipment, resulting in a large overall footprint of the unit. At the same time, the asynchronous motor has a low power density due to the excitation structure limitation, and the additional volume of the gearbox increases the difficulty of infrastructure planning and space utilization.

[0006] (4) Noise and pollution problems are prominent. The gear meshing noise during gearbox operation is the main noise source of the unit. Combined with the electromagnetic noise of the asynchronous motor and the fan noise, additional noise reduction equipment such as soundproof covers is required, which increases costs and space consumption. In addition, traditional units mostly use rolling bearings, which rely on grease lubrication. During long-term operation, grease leakage is prone to occur, contaminating the compressed medium.

[0007] In summary, existing centrifugal compressor units have significant shortcomings in terms of energy efficiency, reliability, compactness, and cleanliness, requiring an innovative technological solution that can simplify the structure and improve efficiency. Utility Model Content

[0008] This utility model addresses the problems in the existing technology by achieving technological innovation through an innovative architecture that integrates permanent magnet synchronous motor direct drive, magnetic levitation bearings, and a common base.

[0009] This utility model proposes a centrifugal compressor unit directly driven by a permanent magnet synchronous motor, including a common base (1), a permanent magnet synchronous motor system, a centrifugal compression system, and a coupling assembly;

[0010] The common base (1) is an integrated load-bearing structure with an embedded lubricating oil station and a motor base (11) on the top outside.

[0011] The permanent magnet synchronous motor system includes a synchronous motor (4) and active magnetic levitation bearings located at both ends of the rotor of the synchronous motor (4). The synchronous motor (4) is fixedly installed on the motor base (11), and a motor shaft head (12) is provided at one end of the rotor shaft of the synchronous motor (4).

[0012] The centrifugal compression system includes a centrifugal impeller (7) and a compressor volute (10). The centrifugal impeller (7) is directly mounted on the motor shaft head (12) of the synchronous motor (4). The compressor volute (10) has a compressor inlet flange (8) on one side and a compressor exhaust flange (6) on the other side. The connection end between the centrifugal impeller (7) and the rotor shaft of the synchronous motor (4) is provided with a Lamilin dry gas seal.

[0013] The coupling assembly is secured to the motor shaft (12) of the synchronous motor (4) and the centrifugal impeller (7) by the tooth end face engagement, and is fastened by the tie rod bolt (13) and the lock nut (14).

[0014] Preferably, the common base (1) is covered with a patterned stainless steel anti-slip cover plate on the top and has pre-embedded anchor bolts, leveling pads and stainless steel pads at the bottom; at least two grounding terminals are installed opposite each other at both ends of the common base (1).

[0015] Preferably, the lubrication station includes an oil tank, a gear pump, a cooler, and a filter, and the lubrication station provides lubrication and cooling for both the magnetic levitation bearing and the coupling assembly.

[0016] Preferably, the synchronous motor (4) is a high-speed permanent magnet synchronous motor, and the rotor of the synchronous motor (4) has a built-in neodymium iron boron permanent magnet; an oil mist fan (5) is installed on the top of the synchronous motor (4), and the outer shell of the synchronous motor (4) is provided with a cooling air duct, which is connected in series with the cooler of the lubricating oil station.

[0017] Preferably, the compressor inlet flange (8) is provided with an electric inlet guide vane installation interface, the compressor exhaust flange (6) has a raised sealing surface, and the compressor exhaust flange (6) is provided with high-strength bolts, nuts and oil-resistant asbestos gaskets.

[0018] Preferably, an accumulator (3) is installed on the side of the common base (1), and the accumulator (3) is connected in series with the outlet pipeline of the lubricating oil station; a drain outlet with a ball valve is provided at the corner of the common base (1).

[0019] Preferably, it also includes a pipeline and instrumentation integration system (9), which is located on a common base (1), with its pipeline portion extending to the edge of the common base (1) and equipped with matching flanges, bolts, nuts and gaskets, and its instrumentation portion including an integrated junction box and an open-frame instrument panel.

[0020] Preferably, the pipeline and instrumentation integration system (9) further includes sensors, including a synchronous motor (4) winding temperature sensor, an active magnetic levitation bearing temperature sensor, a compressor exhaust flange (6) pressure sensor and a lubricating oil pressure sensor; the wiring of the sensors is protected by galvanized steel pipes and led to an open-frame instrument panel.

[0021] Preferably, it also includes a frequency converter, which is electrically connected to the synchronous motor (4), and the frequency converter and the electric inlet guide vane at the compressor inlet flange (8) work together to control the flow.

[0022] This utility model has the following beneficial effects:

[0023] (1) Elimination of intermediate transmission losses: The traditional gearbox is abandoned, and the compressor impeller is directly driven by the rotor shaft of the permanent magnet synchronous motor, which completely avoids the mechanical friction, wind resistance and oil churning losses in the operation of the gearbox. At the same time, the rotor of the permanent magnet synchronous motor adopts neodymium iron boron permanent magnets, which do not require excitation current, reduce rotor copper loss and significantly improve efficiency.

[0024] (2) Reduce flow regulation loss: It can be used with frequency converter to realize stepless speed regulation of motor, and can be controlled in conjunction with the electric inlet guide vane reserved in the compressor inlet to replace the throttling or bypass regulation method of the inlet guide vane of the traditional fixed speed unit, thus avoiding throttling loss; under variable load conditions, the overall energy efficiency of the system is improved compared with the traditional unit, and long-term operation can significantly reduce the energy consumption cost of downstream industries.

[0025] (3) Reduce failure risk: The active magnetic levitation bearing replaces the traditional rolling bearing. The magnetic levitation bearing has no mechanical contact wear, extends its service life and does not require grease lubrication, thus eliminating potential failures such as gear wear, bearing failure and grease leakage from the root. At the same time, the lubrication station is embedded in the common base and integrated with the lubrication system of the motor and compressor, reducing the pipeline layout of the independent oil station and avoiding problems such as oil circuit blockage and oil leakage.

[0026] (4) Simplified installation and maintenance, reduced footprint and volume: The integrated common base for motor-compressor-lubricating oil station is adopted, and the coaxiality error can be precisely controlled by leveling pads, improving assembly efficiency. The permanent magnet synchronous motor has high power density, and the overall structure of the unit is highly integrated, reducing the footprint.

[0027] (5) Low operating noise and clean medium: The main noise sources such as gearbox meshing noise are eliminated. At the same time, sound-absorbing cotton is pasted on the inside of the coupling cover, so no additional soundproof cover is required. The magnetic levitation bearing is grease-free and the compressor shaft end is sealed with a Lamilin dry gas seal, which can effectively prevent lubricating oil from entering the compression chamber and avoid contamination of the compressed medium, thus meeting the needs of the pharmaceutical, electronics and other industries for high-cleanliness compressed media.

[0028] This invention solves the problems of traditional centrifugal compressor units in terms of energy efficiency, reliability, compactness, cleanliness, and ease of operation and maintenance, and meets the current industrial sector's upgrade requirements for high-efficiency, energy-saving, low-maintenance, and compact equipment. Attached Figure Description

[0029] Figure 1 This is an assembly diagram of a centrifugal compressor unit directly driven by a permanent magnet synchronous motor, according to an embodiment of the present invention.

[0030] Figure 2 This is a diagram showing the connection of the motor compressor tooth end face in an embodiment of this utility model.

[0031] Explanation of reference numerals in the attached diagram: 1-Common base; 2-Electric motor oil station; 3-Accumulator; 4-Synchronous motor; 5-Oil mist fan; 6-Compression machine exhaust flange; 7-Centrifugal impeller; 8-Compressor inlet flange; 9-Pipeline instrumentation integrated system; 10-Compressor volute; 11-Motor base; 12-Motor shaft head; 13-Tie rod bolt; 14-Locking nut. Detailed Implementation

[0032] To further understand this utility model, the embodiments of this utility model are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of this utility model, and not for limiting the scope of the claims of this utility model.

[0033] Example 1

[0034] This utility model discloses a centrifugal compressor unit directly driven by a permanent magnet synchronous motor, suitable for industrial gas compression, large-scale air conditioning refrigeration, heat pump systems, and air separation. It adopts a single-layer indoor installation method and features a compact integrated design. The core achieves high-efficiency compression and stable operation through a fully integrated architecture without intermediate transmissions. The unit mainly consists of a common base and auxiliary components, a permanent magnet synchronous motor system, a centrifugal compression system, a coupling and protective cover assembly, and a pipeline and instrumentation integrated system. These parts work together in a coordinated manner, such as... Figure 1 and Figure 2 As shown, the specific structure and functions are as follows:

[0035] I. Common base and accessories

[0036] The common base 1 serves as the load-bearing and integration foundation for the unit. It adopts an integrated load-bearing design for the motor, compressor, and lubrication station, achieving a unified installation benchmark for core components, reducing assembly deviations, and improving system stability.

[0037] The main body of the common base 1 is welded from Q355B low-alloy high-strength steel plate. After welding, it undergoes overall aging treatment to eliminate internal stress and ensure no deformation during long-term operation. The top of the base is covered with a patterned stainless steel anti-slip cover to prevent personnel from slipping during inspections. The bottom is equipped with pre-embedded anchor bolts, leveling shims, and stainless steel washers. The anchor bolts are made of 40Cr steel with a galvanized anti-corrosion surface, and the leveling shims are made of gray cast iron HT200. The leveling shims can be used to precisely adjust the levelness of the base to ensure that the coaxiality error between the synchronous motor 4 and the compressor meets the operating requirements.

[0038] The lubrication station is directly embedded inside the common base 1, requiring no additional space. Its core components include an oil tank, a gear pump, a cooler, and a filter. The oil tank has a volume of 80L and is made of 304 stainless steel. The gear pump has a flow rate of 10m³ / h. The cooler is a shell-and-tube type made of 316L stainless steel. The filter has a precision of 10μm. It can simultaneously provide lubrication and cooling for the magnetic levitation bearings and couplings of the synchronous motor 4, avoiding the complex pipeline problems caused by setting up a separate oil station.

[0039] Two nickel-plated brass grounding terminals are installed opposite each other at both ends of the common base 1. The terminal specifications are M16×50 and they are connected to the base body by a copper braided strap to ensure that the grounding resistance is ≤4Ω during unit operation, thus ensuring the safety of equipment and operators.

[0040] II. Permanent Magnet Synchronous Motor System

[0041] The permanent magnet synchronous motor system provides power to the unit. It adopts a high-speed permanent magnet direct drive and magnetic levitation bearing design, which eliminates the excitation loss and gearbox transmission of traditional asynchronous motors and achieves efficient power output. It mainly includes synchronous motor 4, magnetic levitation bearing, auxiliary heat dissipation and oil mist treatment components.

[0042] Synchronous motor 4 is a high-speed permanent magnet synchronous motor with a rated power of 160kW and a rated speed of 12000r / min. The rotor uses built-in neodymium iron boron permanent magnets, with the permanent magnet grade being N38SH and resistant to high temperatures up to 150℃. It requires no excitation current, and the rotor copper loss is reduced by more than 90%. The efficiency of synchronous motor 4 is ≥96% under rated load, and still maintains ≥94% under partial load (30%-70%), which is significantly better than asynchronous motors of the same power. The stator winding of the motor uses H-class insulation material, and the protection level is IP54, which can be adapted to indoor industrial environments. Synchronous motor 4 is stably mounted on common base 1 via motor base 11.

[0043] The rotor of synchronous motor 4 is equipped with active magnetic levitation bearings at both ends, which achieve rotor levitation without mechanical contact through electromagnetic force, with the levitation gap controlled at 0.1-0.2mm. Compared with traditional rolling bearings, these magnetic levitation bearings have no frictional wear, extend their life to over 80,000 hours, and do not require grease lubrication, avoiding lubricant contamination of the motor's interior. The control system of the magnetic levitation bearings is integrated into the side of synchronous motor 4, which can monitor the rotor position in real time and dynamically adjust the electromagnetic force to ensure stable high-speed operation of the motor.

[0044] For auxiliary heat dissipation and oil mist treatment, an oil mist fan 5 is installed on the top of the synchronous motor 4. The oil mist fan 5 is made of 304 stainless steel and has an air volume of 500m³ / h. It exhausts the trace amount of oil mist generated during motor operation through forced ventilation to keep the inside of the motor clean. The synchronous motor 4 has a cooling air duct in its outer casing, which is connected in series with the cooler of the lubricating oil station to achieve indirect cooling of the motor stator and control the motor temperature rise to ≤80K. The power output end of the synchronous motor 4 is equipped with a motor shaft head 12 for connection to the centrifugal compression system.

[0045] III. Centrifugal Compression System

[0046] The centrifugal compression system adopts a single-stage cantilever and direct-drive impeller structure, which simplifies the transmission chain and improves compression efficiency. It mainly includes a centrifugal impeller 7, shaft end seal and compressor volute 10, and intake adjustment structure.

[0047] The centrifugal impeller 7 is a three-dimensional high-efficiency milled impeller, made of TC4 titanium alloy or 6061-T6 high-strength aluminum alloy (selected according to the corrosiveness of the medium). It is formed by five-axis linkage milling, and the blade profile conforms to the three-dimensional flow field design, with a compression efficiency of ≥88%. The centrifugal impeller 7 is directly mounted on the rotor shaft of the synchronous motor 4, without a separate compressor shaft. The synchronous motor 4 and the centrifugal impeller 7 rotate at the same speed (12000 r / min), avoiding the speed matching loss of the "motor-gearbox-compressor" structure in the traditional structure.

[0048] The shaft end seal adopts a Lamilin dry gas seal, with nitrogen as the sealing medium at a pressure of 0.2 MPa and a leakage rate of ≤0.5 Nm³ / h. This effectively prevents leakage of compressed media (such as air or refrigerant) and avoids lubricating oil entering the compression chamber. The compressor volute 10 is cast from ductile iron QT450-10 and is integrally mounted on the high-speed shaft end of the synchronous motor 4. The compressor volute 10 has internal guide ribs to efficiently collect the pressurized medium from the centrifugal impeller 7 and guide it to the outlet. The compressor inlet flange 8 and compressor exhaust flange 6 are welded to both sides of the compressor volute 10, respectively. The flange pressure rating is PN1.6 MPa, and the sealing surface is raised face (RF). It is equipped with 8.8 grade high-strength bolts, nuts, and oil-resistant asbestos gaskets for easy connection to external pipelines.

[0049] In terms of intake regulation, the intake port of the compressor volute 10 is reserved with an inlet guide vane installation interface. Electric inlet guide vanes can be added according to actual load requirements. With the frequency conversion speed regulation of the synchronous motor 4, stepless flow regulation can be achieved, further expanding the efficient operating range of the unit.

[0050] IV. Coupling and Cover Assembly

[0051] The coupling and protective cover assembly is the core of the transmission connection between the synchronous motor 4 and the centrifugal compression system, and also ensures operational safety. It mainly includes the coupling and the safety cover.

[0052] The coupling adopts a connection structure of tooth end face mating and tie rod bolt 13. The motor shaft head 12 of the synchronous motor 4 and the connection end of the centrifugal impeller 7 are precisely mated through tooth end face mating, and then fastened to the locking nut 14 through tie rod bolt 13. This structure has no mechanical clearance, high transmission efficiency, can compensate for coaxiality deviation caused by installation or operating temperature rise, and is impact-resistant and vibration-resistant, avoiding the wear problem of traditional gear couplings.

[0053] The safety cover is welded from Q235 steel plate and has a fully enclosed structure with an IP23 protection rating. The top is equipped with an organic glass observation window (5mm thick) for easy observation of the coupling's operating status during inspections. The cover is fixed to the common base 1 with bolts and is aligned coaxially with the coupling. The inner side is lined with sound-absorbing cotton (10mm thick) to reduce the noise generated by the coupling's rotation (noise reduction ≥10dB) and prevent personnel from accidentally touching the rotating parts.

[0054] V. Piping and Instrumentation Integration System

[0055] The pipeline and instrumentation integration system 9 enables unified transmission and monitoring of internal media and signals within the unit, improving the convenience of operation and maintenance. It mainly includes integrated pipelines, instruments and control components, and auxiliary components.

[0056] Regarding integrated piping, all pipelines within the common base 1 area (including lubricating oil pipes, cooling water pipes, sealed nitrogen pipes, and compressed medium bypass pipes) adopt a "hidden arrangement within the base." The pipe materials are selected according to the characteristics of the medium: lubricating oil pipes use 20# seamless steel pipes (outer diameter 25mm, wall thickness 3mm), cooling water pipes use 304 stainless steel pipes (outer diameter 32mm, wall thickness 2.5mm), and sealed nitrogen pipes use 316L stainless steel pipes (outer diameter 15mm, wall thickness 2mm). All pipe ends extend to the edge of the common base 1 and are equipped with matching flanges (of the same material as the pipes), bolts, nuts, and gaskets to ensure seamless connection with external systems and avoid the cumbersome secondary piping on site.

[0057] In terms of instrumentation and control, the common base 1 integrates an instrument junction box (made of 304 stainless steel, IP65 protection rating). All sensor wiring (such as the synchronous motor winding temperature sensor, magnetic levitation bearing temperature sensor, six pressure sensors at the compressor exhaust flange, and lubricating oil pressure sensor) is protected by galvanized steel conduit (20mm outer diameter) and led to the open-frame instrument panel on top of the common base 1. The instrument panel is made of cold-rolled steel plate with powder coating (IP54 protection rating) and integrates modules such as speed display, temperature / pressure alarm, and lubricating oil system status indicator. It also has a reserved 485 communication interface for connection to the factory's DCS system, enabling remote monitoring and automatic control.

[0058] Regarding auxiliary components, an accumulator 3 is installed on the side of the common base 1. The accumulator 3 is made of 304 stainless steel, has a volume of 5L, and a working pressure of 1.0MPa. It is connected in series with the outlet pipeline of the lubricating oil station to stabilize the lubricating oil pressure and prevent sudden pressure changes caused by the start-up and shutdown of the oil pump or load fluctuations. A drain port (with a ball valve) is set in the corner of the common base 1 to facilitate the drainage of condensate or leaked oil inside the base and prevent liquid accumulation from corroding the base.

[0059] The working process of the unit in this embodiment of the utility model is as follows:

[0060] (1) During startup, the frequency converter drives the synchronous motor 4 to start smoothly (starting current ≤ 1.5 times the rated current, achieving soft start). The rotor shaft of the synchronous motor 4 directly drives the centrifugal impeller 7 to rotate through the coupling structure of the tooth end face and the tie rod bolt 13. After the centrifugal impeller 7 reaches the rated speed, the process medium (such as air) enters through the compressor inlet flange 8, and after being pressurized by the high-speed rotation of the three-dimensional centrifugal impeller 7, it is collected by the compressor volute 10 and transported to the downstream system through the compressor exhaust flange 6.

[0061] During operation, the lubrication station continuously provides lubrication and cooling for the magnetic levitation bearing and coupling of the synchronous motor 4, the accumulator 3 stabilizes the lubricating oil pressure, and the oil mist fan 5 discharges trace amounts of oil mist from the synchronous motor 4. The pipeline and instrumentation integration system 9 monitors key parameters such as the temperature of the synchronous motor 4, the pressure at the compressor exhaust flange 6, and the unit speed in real time. When the parameters exceed the limits, the instrument panel issues an audible and visual alarm and triggers protection logic (such as stopping the synchronous motor 4 and opening the compressed medium bypass valve) to ensure the safe and stable operation of the unit.

[0062] The above description of the embodiments is only for the purpose of helping to understand the method and core idea of ​​this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made to this utility model without departing from the principle of this utility model, and these improvements and modifications also fall within the protection scope of the claims of this utility model.

Claims

1. A centrifugal compressor unit directly driven by a permanent magnet synchronous motor, characterized in that, Includes a common base (1), a permanent magnet synchronous motor system, a centrifugal compression system, and a coupling assembly; The common base (1) is an integrated load-bearing structure with an embedded lubricating oil station and a motor base (11) on the top outside. The permanent magnet synchronous motor system includes a synchronous motor (4) and active magnetic levitation bearings located at both ends of the rotor of the synchronous motor (4). The synchronous motor (4) is fixedly installed on the motor base (11), and a motor shaft head (12) is provided at one end of the rotor shaft of the synchronous motor (4). The centrifugal compression system includes a centrifugal impeller (7) and a compressor volute (10). The centrifugal impeller (7) is directly mounted on the motor shaft head (12) of the synchronous motor (4). The compressor volute (10) has a compressor inlet flange (8) on one side and a compressor exhaust flange (6) on the other side. The connection end between the centrifugal impeller (7) and the rotor shaft of the synchronous motor (4) is provided with a dry gas seal. The coupling assembly is secured to the motor shaft (12) of the synchronous motor (4) and the centrifugal impeller (7) by the tooth end face engagement, and is fastened by the tie rod bolt (13) and the lock nut (14).

2. The centrifugal compressor unit directly driven by a permanent magnet synchronous motor according to claim 1, characterized in that, The common base (1) is covered with a patterned stainless steel anti-slip cover plate on the top and has pre-embedded anchor bolts, leveling pads and stainless steel pads at the bottom; at least two grounding terminals are installed opposite each other at both ends of the common base (1).

3. The centrifugal compressor unit directly driven by a permanent magnet synchronous motor according to claim 1, characterized in that, The lubrication station includes an oil tank, a gear pump, a cooler, and a filter. The lubrication station also provides lubrication and cooling for the magnetic levitation bearing and coupling assembly.

4. The centrifugal compressor unit directly driven by a permanent magnet synchronous motor according to claim 3, characterized in that, The synchronous motor (4) is a high-speed permanent magnet synchronous motor. The rotor of the synchronous motor (4) has a built-in neodymium iron boron permanent magnet. An oil mist fan (5) is installed on the top of the synchronous motor (4). The outer shell of the synchronous motor (4) is provided with a cooling air duct. The cooling air duct is connected in series with the cooler of the lubricating oil station.

5. The centrifugal compressor unit directly driven by a permanent magnet synchronous motor according to claim 1, characterized in that, The compressor inlet flange (8) is provided with an electric inlet guide vane installation interface, the compressor exhaust flange (6) has a raised sealing surface, and the compressor exhaust flange (6) is provided with high-strength bolts, nuts and oil-resistant asbestos gaskets.

6. The centrifugal compressor unit directly driven by a permanent magnet synchronous motor according to claim 1, characterized in that, An accumulator (3) is installed on the side of the common base (1), and the accumulator (3) is connected in series with the outlet pipeline of the lubricating oil station; a drain outlet with a ball valve is provided at the corner of the common base (1).

7. The centrifugal compressor unit directly driven by a permanent magnet synchronous motor according to claim 1, characterized in that, It also includes a pipeline and instrumentation integration system (9), which is located on a common base (1), with its pipeline portion extending to the edge of the common base (1) and equipped with matching flanges, bolts, nuts and gaskets, and its instrument portion including an integrated junction box and an open-frame instrument panel.

8. The centrifugal compressor unit directly driven by a permanent magnet synchronous motor according to claim 7, characterized in that, The pipeline and instrumentation integration system (9) also includes sensors, including a synchronous motor (4) winding temperature sensor, an active magnetic levitation bearing temperature sensor, a compressor exhaust flange (6) pressure sensor and a lubricating oil pressure sensor; the wiring of the sensors is protected by galvanized steel pipes and led to an open-frame instrument panel.

9. The centrifugal compressor unit directly driven by a permanent magnet synchronous motor according to claim 5, characterized in that, It also includes a frequency converter, which is electrically connected to the synchronous motor (4), and the frequency converter and the electric inlet guide vane at the compressor inlet flange (8) work together to control the flow.

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