CN106712355B

CN106712355B - Cooling method and cooling system for high-speed permanent magnet motor rotor

Info

Publication number: CN106712355B
Application number: CN201710091124.9A
Authority: CN
Inventors: 张回良; 林伟伟; 张�杰; 刘涛; 肖旭
Original assignee: Shanghai United Compressor Co ltd
Current assignee: Shanghai United Compressor Co ltd
Priority date: 2017-02-20
Filing date: 2017-02-20
Publication date: 2023-06-27
Anticipated expiration: 2037-02-20
Also published as: CN106712355A

Abstract

The invention relates to a cooling method and a cooling system of a high-speed permanent magnet motor rotor, wherein the permanent magnet motor rotor rotates at a high speed under the bearing support, two to four air pipelines for cooling the rotor are uniformly arranged in a stator winding which is at a distance from the surface of the rotor and is close to the surface, one end of each air pipeline is blocked, and a plurality of air holes with the diameter of 1.5mm are uniformly arranged at the side of the air pipeline, which is close to the shaft, at a distance of 10mm, so that fresh coolant or air is blown to the whole heating surface of the shaft to form convection heat exchange, and the cooling effect is optimal; six to sixteen holes with proper diameters are uniformly formed in the motor shell in the circumferential direction and communicated with the atmosphere, and finally a coolant circulation loop from the inlet of the air pipeline to the outflow of the air from the holes in the motor shell is formed. The invention directly carries out direct convection heat exchange within the range of most axial length of the shaft, so that the heat exchange efficiency is better, and the invention is more practical and reliable, simpler in structure, lower in cost and better in effect.

Description

Cooling method and cooling system for high-speed permanent magnet motor rotor

Technical Field

The invention relates to a cooling mode of a high-speed permanent magnet motor rotor, in particular to a high-power (more than or equal to 100 kW) ultrahigh-speed (more than or equal to 10000 RPM) permanent magnet motor device, and mainly relates to a cooling method and a cooling system for heat dissipation of the high-power high-speed permanent magnet motor rotor.

Background

High-speed permanent magnet motors are highly electromechanical integrated products integrating various advanced technologies such as machinery, electricity, control, power electronics, new materials and the like. The motor is characterized in that the functions of the motor and the traditional transmission systems such as a gearbox are structurally integrated, a complex intermediate transmission link is omitted, and the motor has the advantages of wide speed regulation range, small rotational inertia, low energy consumption, high working efficiency, easiness in realizing stepless speed regulation, precise control and the like. With the continuous development of the modern equipment manufacturing industry to the high speed, high efficiency, low energy consumption and high automation, the technical improvement and structural innovation of the high-speed motor are more and more urgent. Because the high-speed permanent magnet motor has high heating power, the temperature of a stator and a rotor is easy to be overhigh, the motor efficiency is influenced, and even the rotor permanent magnet can be irreversibly demagnetized, so that the motor is scrapped. Therefore, how to ensure the operation temperature of the motor (especially the operation temperature of the rotor permanent magnet) within the safety range is one of the difficulties in designing the high-speed permanent magnet motor. The current common permanent magnet motor rotor cooling mode is as follows:

1. as shown in fig. 1, the motor stator 7 is cooled by cooling water flowing from the cooling water inlet 2 to the cooling water outlet 3. The motor rotor 10 is cooled by injecting compressed air for cooling through the cooling air inlet 1. Compressed air of 0.2Mpa to 0.4Mpa is injected from the cooling air inlet 1 to cool the rotor surface while flowing over the bearings 4, 5, and finally discharged to the atmosphere. This cooling air requires a pressure of about 0.2Mpa to 0.4 Mpa. The disadvantage of this kind of scheme lies in that the cooling air only blows to the axle in the middle part of the rotor, and the pressure air current easily causes the rotor atress unbalanced, and most surfaces of axle do not directly exchange heat with fresh cold air, and heat exchange efficiency is poor, and air pressure is great, causes frictional loss great.

2. As shown in fig. 2, the intermediate position is the motor rotor 30, air 50 is sucked from the atmosphere, sucked from both ends of the motor rotor 30, negative pressure cooling air 60 passes through the stator 40 through the intermediate position, is discharged through the vacuum pump 70 or the air ejector, and is released to the atmosphere. In fig. 2, the lower exhaust passage communicates with the upper exhaust passage and shares a vacuum pump 70. This cooling method can reduce friction loss, but has a problem of slightly poor heat exchange efficiency as in the device of fig. 1.

3. As shown in fig. 3, a blowing fan 11 and a sucking fan 14 are added to the motor casing 13, so that the air flow in the motor forms air flow circulation of 'atmosphere → f11 → f12 → f13 → f14 → f15 → atmosphere', and part of heat on the surface of the rotor 17 is taken away, but the air gap between the rotor 17 and the stator winding 12 is small, the air flow is difficult to directly flow through the surface of the rotor, and the heat dissipation efficiency is extremely low.

4. As shown in FIG. 4, the permanent magnets on the rotor 24 are provided with miniature axial flow impellers 23, the forced cold air flows through the rotor surface during the rotation of the impellers 23, so that 'atmosphere → F21 → F22 → F23 → F24 → F25 → atmosphere' air flow circulation is formed, heat is taken away, and the purpose of cooling the rotor is achieved.

In view of this, those skilled in the art have been working to develop a cooling method and apparatus for cooling the rotor of a high-speed permanent magnet motor to ensure that the operating temperature of the motor is controlled within a safe range.

Disclosure of Invention

The invention aims to provide a cooling method and a cooling system for a high-speed permanent magnet motor rotor, which improve the heat exchange efficiency and solve the problem of heat dissipation of the high-speed permanent magnet motor rotor in the prior art by directly carrying out direct convection heat exchange in the range of most axial length of a shaft.

The technical scheme of the invention is as follows:

a cooling method of a high-speed permanent magnet motor rotor, the rotor of the permanent magnet motor rotates at a high speed under the support of a first bearing and a second bearing, two to four air pipelines for cooling the rotor are uniformly arranged in the axial direction in a stator winding which is close to the surface of the rotor, one end of each air pipeline is blocked, a plurality of air holes with the diameter of 1.5mm are uniformly arranged on one side of each air pipeline, which is close to a shaft, at a distance of 10mm, so that fresh coolant or air is blown to the whole heating surface of the shaft to form convection heat exchange, and the cooling effect is optimized;

six to sixteen holes with proper diameters are uniformly formed in the motor shell in the circumferential direction and communicated with the atmosphere, and finally a coolant circulation loop from the inlet of the air pipeline to the outflow of the air from the holes in the motor shell is formed.

The atmospheric flow path of the coolant circulation loop is as follows: the air enters from the inlet of the air pipeline for cooling the rotor, flows to a plurality of air holes on one side close to the shaft in the air pipeline, flows out from the air holes into the space between the outside of the stator winding and the inside of the motor shell, and flows out from the holes on the motor shell.

A cooling system of a high-speed permanent magnet motor rotor comprises a motor shell, a permanent magnet motor rotor, a thrust disc, a first bearing, a second bearing, a stator winding and a rotor cooling air pipeline;

the permanent magnet motor rotor is arranged in a motor shell, a first bearing and a second bearing are arranged on two sides of the rotor, a stator winding is arranged on the periphery of the rotor, two to four air pipelines for cooling the rotor are uniformly arranged in the stator winding which is far away from the surface of the rotor and is close to the rotor in the axial direction, a plurality of air holes with the diameter of 1.5mm are uniformly arranged on one side of the air pipeline, which is close to the shaft, at a distance of 10mm, six to sixteen holes with the proper diameter are uniformly formed in the circumferential direction of the motor shell, and the air holes are communicated with the atmosphere to form a coolant circulation loop for circulating the atmosphere.

The rotor cooling gas pipeline is connected with the same pressure gas source, and the gas source pressure is 0.5bar (G) to 1bar (G).

The rotor cooling air pipeline is connected with a small vacuum pump, the vacuum pump works to enable negative pressure to be formed around the shaft, opposite air flow directions and circulation loops are arranged, friction loss between the rotor and air is minimized under a negative pressure working condition, and the effect of cooling the rotor of the high-speed permanent magnet motor is achieved.

The air holes arranged on one side of the air pipeline for cooling the rotor, which is close to the shaft, are changed into a whole seam, and the width of the seam is 1mm, so that the heat dissipation of the shaft is more sufficient.

By adopting the cooling method and the cooling system for the high-speed permanent magnet motor rotor, direct convection heat exchange is directly carried out in most axial length ranges of the shaft, so that the heat dissipation problem of the high-power high-speed permanent magnet motor rotor is solved, the heat exchange efficiency is better, the structure is simpler, the cost is lower, and the effect is better.

The basic idea of the invention is to use normal temperature air or other gaseous coolant to conduct direct convection heat exchange with most surfaces of the shaft to optimize heat exchange efficiency. Meanwhile, the rotor is not modified, so that the structure is simple to the greatest extent, the manufacturing cost is low, and the cooling gas consumption is reduced.

The cooling air pipeline used in the invention adopts stainless steel or other non-magnetic materials, so that the magnetic attraction force is prevented from being added to the permanent magnet rotor.

The permanent magnet motor belongs to a high-power (more than or equal to 100 kW) ultrahigh-speed (more than or equal to 10000 RPM) device, and the rotor has extremely strong magnetism and extremely high heating power density.

The cooling air pipelines are uniformly distributed in two to four in the circumferential direction, so that the impact forces generated by the air flow on the shaft can be mutually offset, and no additional unbalanced force is generated on the rotor.

In the invention, one end of the cooling air pipeline is connected with a pressure air source or a vacuum pump, and the other end of the cooling air pipeline is completely closed in the motor so as to prevent waste caused by leakage of the coolant.

The cooling air pipeline is provided with a row of holes with the diameter of 0.5-2 mm at one side close to the surface of the shaft, the distance is preferably 8-20 mm, or the width is preferably 0.5-1.5 mm, and the length is adapted to a specific structure so as to facilitate air flow circulation and enable convection heat exchange to be formed.

The pressure of the pressure air source is not required to be too high, and 0.5bar (G) to 1bar (G) is preferable to prevent excessive friction loss.

Compared with other rotor heat dissipation modes, the cooling method and the cooling system can reduce the consumption of cooling air by one time and reduce friction loss to below one half.

The features of the present invention will be apparent from the following detailed description of preferred embodiments, with reference to the accompanying drawings.

Drawings

Fig. 1 to 4 are schematic diagrams of permanent magnet motor structures of existing or patented rotor cooling modes on the market.

Fig. 5 is a schematic structural diagram of a cooling mode of a rotor of a permanent magnet motor according to a first embodiment of the present invention.

Fig. 6 is an enlarged view of a portion of fig. 5, labeled i.

Fig. 7 is an enlarged view of a portion of the reference numeral ii in fig. 5.

Fig. 8 is a schematic diagram of a cooling tube with a continuous gap structure for a rotor cooling mode of a permanent magnet motor according to a second embodiment of the present invention.

Fig. 9 is a schematic structural diagram of a rotor cooling method of a permanent magnet motor according to a third embodiment of the present invention.

Fig. 10 is an enlarged view of a portion of the reference numeral i in fig. 9.

Fig. 11 is an enlarged view of a portion of the reference numeral ii in fig. 9.

Fig. 12 is a schematic view of a cooling tube with a continuous gap structure for a rotor cooling method of a permanent magnet motor according to a fourth embodiment of the present invention.

Reference numerals:

in fig. 1: 1 is a cooling air inlet, 2 is a cooling water inlet, 3 is a cooling water outlet, 4 and 5 are bearings, 7 is a motor stator, and 10 is a motor rotor.

In fig. 2: 20 is a motor shaft, 30 is a motor rotor, 40 is a stator, 50 is air, 60 is negative pressure cooling air, and 70 is a vacuum pump.

In fig. 3: 11 is an air blowing fan, 12 is a stator winding, 13 is a motor casing, 14 is an air suction fan, 15 is a motor end cover, 16 is a bearing, 17 is a rotor, and 18 is a bearing.

In fig. 4: 21 is the motor casing, 22 is the stator winding, 23 is miniature axial flow impeller, 24 is the rotor.

31 is a rotor, 32 is a thrust disk, 33 is a first bearing, 34 is a motor housing, 35 is a rotor cooling air pipe, 36 is a stator winding, 37 is a second bearing, 38 is an air hole, 39 is a full slit, and 41 is a vacuum pump.

Detailed Description

In order that the manner in which the invention is attained, as well as the features and advantages thereof, will be readily understood, a more particular description of the invention will be rendered by reference to specific embodiments thereof.

Referring to fig. 5 to 7, the present invention provides a method for cooling a rotor of a high-speed permanent magnet motor, in which the rotor 31 of the permanent magnet motor rotates at a high speed under the support of a first bearing 33 and a second bearing 37, two to four air pipes 35 for cooling the rotor are uniformly arranged in a shaft direction in a stator winding 36 which is located at a relatively short distance from the surface of the rotor 31, one end of the air pipe 35 is blocked, and a plurality of air holes 38 having a diameter of 1.5mm are uniformly arranged at a distance of 10mm from one side of the air pipe 35 toward the shaft so that fresh coolant or air is blown toward the entire heat generating surface of the shaft to form convection heat exchange, thereby optimizing the cooling effect.

Six to sixteen holes with proper diameters are uniformly formed on the motor shell 34 circumferentially and communicated with the atmosphere, and finally a coolant circulation loop from the inlet of the air pipeline 35 to the outflow of the air from the holes on the motor shell 34 is formed.

The atmospheric flow path of the coolant circulation loop is as follows: the air enters from the inlet of the rotor cooling air duct 35, flows through the air duct 35 to the air holes 38 on the shaft side, flows out of the air holes 38 into the space between the outside of the stator winding 36 and the inside of the motor case 34, and flows out of the holes in the motor case 34.

In a preferred embodiment of the invention, the high-speed motor rotor cooling air pipelines (two to four air pipelines are uniformly distributed along the circumferential direction according to the structure and actual requirement) are connected with the same pressure air source, and the air source pressure is 0.5bar (G) to 1bar (G).

In another preferred embodiment of the present invention, the air pipes (two to four air pipes are uniformly arranged in the circumferential direction according to the structure and actual requirement) for cooling the rotor of the high-speed motor are connected with a small vacuum pump 41, and the air flow direction is opposite to that of the previous embodiment, so that the friction loss between the rotor and the air flow can be greatly reduced under the working condition of low pressure.

Referring to fig. 5 to 12, the present invention also provides a cooling system for a rotor of a high-speed permanent magnet motor, which is mainly composed of a motor housing 34, a rotor 31 of the permanent magnet motor, a thrust disk 32, a first bearing 33, a second bearing 37, a stator winding 36, and a gas line 35 for cooling the rotor.

The permanent magnet motor rotor 31 is arranged in a motor shell 34, a first bearing 33 and a second bearing 37 are arranged on two sides of the rotor 31, a stator winding 36 is arranged on the periphery of the rotor 31, two to four air pipelines 35 for cooling the rotor are uniformly arranged in the axial direction of the stator winding 36 which is far away from the surface of the rotor 31 and is close to the surface, a plurality of air holes 38 with the diameter of 1.5mm are uniformly arranged on one side of the air pipeline 35, which is close to the shaft, at a distance of 10mm, six to sixteen holes with the proper diameters are uniformly arranged on the circumferential direction of the motor shell 34, and the air holes are communicated with the atmosphere, so that a coolant circulation loop for circulating the atmosphere is formed.

The rotor cooling gas line 35 is connected to the same pressure gas source, the gas source pressure being 0.5bar (G) to 1bar (G).

As shown in fig. 9, the air pipe 35 for cooling the rotor is connected with a small vacuum pump 41, the vacuum pump 41 works to form negative pressure around the shaft, opposite air flow directions and circulation loops are set, friction loss between the rotor and air is minimized under the negative pressure working condition, and the effect of cooling the rotor of the high-speed permanent magnet motor is achieved.

As shown in fig. 8, the plurality of air holes 38 provided on the side of the rotor cooling air duct 35 toward the shaft are replaced with a single slit 39 having a slit width of 1mm, so that the heat dissipation of the shaft is more sufficient.

Example 1:

referring to fig. 5 to 7, fig. 5 shows a permanent magnet motor with a rotational speed 20000R/min and a power greater than 100kW, the rotor 31 rotates at a high speed supported by the bearing 33 and the bearing 37, two to four air pipes 35 are uniformly arranged in the axial direction of the stator winding 36 which is closer to the surface of the rotor 31, one end of the air pipe 35 is sealed, and air holes with a diameter of 1.5mm are uniformly arranged on the side of the air pipe which is closer to the shaft at a distance of 10mm, so that fresh coolant (air) is blown to the whole heat generating surface of the shaft to form convection heat, and the cooling effect is optimized. Six to sixteen holes with proper diameters are uniformly formed in the circumferential direction of the motor shell 34 and communicated with the atmosphere. Finally, a coolant circulation loop of 'atmosphere- & gt F31- & gt F32- & gt F33- & gt F34- & gt F35- & gt F36- & gt F37- & gt atmosphere' is formed.

Example 2:

referring to fig. 8, the only difference between this solution and embodiment 1 is that the air pipe 35 is changed from an open hole to a full slit 39, and the slit width is about 1mm, and compared with embodiment 1, this solution can make the heat dissipation of the shaft more sufficient and better.

Example 3:

referring to fig. 9 to 11, the structure of the solution is similar to that of embodiment 1, except that a vacuum pump 41 is added, the vacuum pump 41 works to form negative pressure around the shaft, the air flow direction and the circulation loop are opposite to those of embodiment 1, the coolant circulation path is 'atmosphere → f47 → f46 → f45 → f44 → f43 → f42 → f41 → atmosphere', and under the negative pressure working condition, friction loss between the rotor and the gas is minimized, and the effect of cooling the rotor of the high-speed permanent magnet motor can be achieved.

Example 4:

referring to fig. 12, the only difference between this solution and embodiment 3 is that the air pipe 35 is changed from an opening to a full slit 39, and the slit width is about 1mm, and compared with embodiment 3, this solution can make the heat dissipation of the shaft more sufficient and better.

The foregoing has shown and described the basic principles, principal features and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present invention, and various changes and modifications may be made therein without departing from the spirit and scope of the invention, which is defined by the appended claims. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims

1. A cooling method of a high-speed permanent magnet motor rotor is characterized by comprising the following steps of: the permanent magnet motor rotor (31) rotates at a high speed under the support of a first bearing (33) and a second bearing (37), two to four air pipelines (35) for rotor cooling are uniformly arranged in the axial direction of a stator winding (36) which is positioned at a distance from the surface of the rotor (31) and is closer to the surface, one end of each air pipeline (35) is blocked, and a plurality of air holes (38) with the diameter of 1.5mm are uniformly arranged on one side of each air pipeline (35) close to the shaft at a distance of 10mm, so that fresh coolant or air is blown to the whole heating surface of the shaft to form convection heat, and the cooling effect is optimized;

six to sixteen holes with proper diameters are uniformly formed in the motor shell (34) in the circumferential direction, the holes are communicated with the atmosphere, and finally a coolant circulation loop from the inlet of the air pipeline (35) to the outflow of the air from the holes in the motor shell (34) is formed.

2. A method of cooling a rotor for a high speed permanent magnet machine according to claim 1, wherein: the atmospheric flow path of the coolant circulation loop is as follows: the air enters from the inlet of the air pipe (35) for cooling the rotor, flows in the air pipe (35) to a plurality of air holes (38) near the side of the shaft, flows out from the air holes (38) into the space between the outside of the stator winding (36) and the inside of the motor housing (34), and flows out from the holes on the motor housing (34).

3. A cooling system for a high-speed permanent magnet motor rotor, characterized by: the motor comprises a motor shell (34), a permanent magnet motor rotor (31), a thrust disc (32), a first bearing (33), a second bearing (37), a stator winding (36) and a rotor cooling air pipeline (35);

the permanent magnet motor rotor (31) is arranged in a motor shell (34), a first bearing (33) and a second bearing (37) are arranged on two sides of the rotor (31), a stator winding (36) is arranged on the periphery of the rotor (31), two to four rotor cooling air pipelines (35) are uniformly arranged in the axial direction of the stator winding (36) which is far away from the surface of the rotor (31), a plurality of air holes (38) with the diameter of 1.5mm are uniformly arranged on one side of the air pipeline (35) close to the shaft at the distance of 10mm, six to sixteen holes with the proper diameters are uniformly formed in the circumferential direction of the motor shell (34), and the air is communicated with the atmosphere, so that a coolant circulation loop with atmospheric circulation is formed.

4. A cooling system for a rotor of a high speed permanent magnet machine according to claim 3, wherein: the rotor cooling air pipeline (35) is connected with the same pressure air source, and the air source pressure is 0.5bar (G) to 1bar (G).

5. A cooling system for a rotor of a high speed permanent magnet machine according to claim 3, wherein: the rotor cooling air pipeline (35) is connected with a small vacuum pump (41), the vacuum pump (41) works to enable negative pressure to be formed around the shaft, opposite air flow directions and circulation loops are arranged, friction loss between the rotor and air is reduced to the minimum under a negative pressure working condition, and the effect of cooling the rotor of the high-speed permanent magnet motor is achieved.

6. A cooling system for a rotor of a high speed permanent magnet machine according to claim 3, wherein: the air holes (38) arranged on the side of the rotor cooling air pipeline (35) close to the shaft are changed into a whole slit (39), and the slit width is 1mm, so that the heat dissipation of the shaft is more sufficient.