Composite rotor cooling mechanism of permanent magnet synchronous traction motor

Abstract

The invention discloses a composite rotor cooling mechanism of a permanent magnet synchronous traction motor. A rotor core of the mechanism is provided with a skewed pole structure and is provided with a magnetic isolation groove, permanent magnets are uniformly arranged on the peripheral surface of the rotor core at intervals along the circumferential direction, a sheath is sleeved on the permanent magnets and the rotor core and is provided with a magnetic isolation groove, and wind thorns are arranged on the end surface of the air inlet side of the composite rotor cooling mechanism and are positioned at the magnetic isolation groove. In a limited cooling space, the magnetic isolation grooves parallel to the skewed poles are arranged, and the wind thorns are additionally arranged on the air inlet sides of the magnetic isolation grooves, so that the convective heat transfer coefficient in the magnetic isolation grooves is improved, the effect of cooling the motor is better achieved, the loss of the motor is reduced through the skewed poles of the rotor and the magnetic isolation grooves, and the temperature rise of the motor is reduced from the source. The magnetic isolation grooves, the skewed poles and the inner hole are used in a matched mode, starting from the two aspects of reducing loss and improving the heat dissipation coefficient, compared with a single cooling structure, the cooling mechanism has a better effect on reducing temperature rise, and the cooling mechanism can be applied to a more complex motor.

Description

Technical Field

[0001] The invention relates to a composite rotor cooling mechanism, in particular to a composite rotor cooling mechanism of a permanent magnet synchronous traction motor. Background Art

[0002] Permanent magnet synchronous motors have the characteristics of small size, high efficiency, and high power factor. They have been widely used in recent years, such as in electric vehicles, rail transit, and wind power generation. Compared with transmission asynchronous starting motors, permanent magnet synchronous motors use permanent magnet excitation in the motor rotor to avoid excitation losses caused by the excitation current generating a magnetic field. However, the requirements for permanent magnet motors in the above-mentioned application fields are small power and moderate speed or high power and low speed, while the requirements for permanent magnet motors used in centrifugal compressors are: high power and high speed. In actual use, there are the following difficulties: high power, high heat generation, high speed, small size, and small heat dissipation space, which leads to difficulties in heat dissipation when running at high power. Therefore, it is necessary to adopt forced heat dissipation measures to take away the heat inside the motor to prevent the permanent magnets inside the rotor from demagnetizing and failing due to long-term operation in a high-temperature environment.

[0003] Existing permanent magnet synchronous motors are divided into two types according to the type of cooling method: open motors and closed motors or semi-closed motors. Open motors are often air-cooled, which uses internal fan blades to drive the air flow around the stator and rotor to take away heat for dissipation. This motor structure is easy to implement, but because the cooling medium is air, the heat that air can take away during heat exchange is limited. For permanent magnet motor rotors with sheaths, traditional cooling methods cannot cool them well. Therefore, the traditional air cooling method of open motors has certain limitations. Closed motors use liquid refrigerant to introduce evaporative cooling into the stator to obtain a better cooling effect on the stator surface. Most existing compressor motors use this cooling method.

[0004] In recent years, with the upgrading of material performance, the application scenarios of permanent magnet synchronous motors have begun to tend more and more towards high-speed applications. In order to prevent the permanent magnet part of the motor from detaching, the sleeve has begun to be widely used in the motor. However, the sleeve on the rotor side of the motor will affect the heat dissipation of the motor. Therefore, the method of opening holes in the sleeve is adopted to dissipate the heat of the motor, which effectively improves the application and promotion of high-power motors. It is the cooling model that should be optimized as much as possible at present. Summary of the invention

[0005] In order to solve the problems existing in the background technology, the present invention provides a composite rotor cooling mechanism for a permanent magnet synchronous traction motor. The present invention utilizes the effects of rotor skew poles and open-hole wind thorns to reduce motor losses and optimize cooling channels, cool the motor to a greater extent, solve the problem of cooling the stator and rotor of a high-power motor, and avoid failure of the motor in a long-term operation in a high-temperature environment, which causes serious losses to equipment, etc.

[0006] The technical solution adopted by the present invention is:

[0007] The composite rotor cooling mechanism of the permanent magnet synchronous traction motor of the present invention comprises a rotor core provided with a plurality of oblique pole structures and a plurality of magnetic isolation grooves.

[0008] The composite rotor cooling mechanism comprises a plurality of permanent magnets which are evenly spaced and arranged on the outer peripheral surface of the rotor core along the circumferential direction.

[0009] The composite rotor cooling mechanism comprises a sheath which is sleeved on the permanent magnet and the rotor core and has a plurality of magnetic isolation grooves.

[0010] The composite rotor cooling mechanism comprises a plurality of wind thorns which are installed on the end surface of the composite rotor cooling mechanism at the air inlet side and are located at the magnetic isolation grooves on the sleeve and the rotor core.

[0011] The middle part of the rotor core is a cylindrical structure arranged along the axial direction of the composite rotor cooling mechanism. A number of mutually parallel oblique pole structures are evenly spaced on the circumference of the cylindrical structure. The oblique pole structure is a strip-shaped fan body bent with the same arc. The two end surfaces of the oblique pole structure are respectively located on the same plane as the two end surfaces of the composite rotor cooling mechanism. A magnet slot is formed between every two oblique pole structures, and each permanent magnet is arranged in one of its own magnet slots.

[0012] The magnetic isolation grooves are arranged on the oblique pole structure and the sheath on both sides of each permanent magnet. Magnetic isolation grooves are provided on both sides of each permanent magnet on the air inlet side and the air inlet side of the composite rotor cooling mechanism. Each two opposite magnetic isolation grooves on the air inlet side and the air inlet side are interconnected along the length direction of the oblique pole structure to form a cooling channel.

[0013] The skewed pole structure can reduce the axial flow length of eddy current loss in the permanent magnet, and the magnetic isolation groove can increase the magnetic resistance. Both methods can reduce the rotor side loss. Both structures can reduce the generation of electromagnetic loss on the rotor side.

[0014] The wind thorns are two 90-degree bent plate structures, each of which is evenly spaced along the circumference of the end face of the air inlet side of the composite rotor cooling mechanism. Each wind thorn is surrounded by a respective magnetic isolation groove, and the direction of the magnetic isolation groove from the sheath to the oblique pole structure is its own length direction. One section of the wind thorn is located on the outer side of the magnetic isolation groove and is perpendicular to the length direction of the magnetic isolation groove, and the other section of the wind thorn is located on the same side edge of the magnetic isolation groove and is parallel to the length direction of the magnetic isolation groove. The other section of the wind thorn is at 45 degrees to the end face of the composite rotor cooling mechanism.

[0015] Compared with straight openings, the coordination of the oblique-pole structure opening channels and wind thorns can further reduce the deflection angle of the fluid, increase the convection coefficient of the fluid between the holes, and enhance the heat dissipation capacity.

[0016] Due to the temperature rise changes caused by the core loss on the rotor side and the eddy current loss of the permanent magnet, it may cause difficulty in heat dissipation of the motor, which in turn causes irreversible demagnetization of the permanent magnet. Therefore, cooling by opening a channel in the rotor core can better reduce the rotor temperature and avoid motor failure. The composite rotor cooling mechanism of the present invention is designed to combine the permanent magnet slant pole structure on the rotor side of the permanent magnet motor with the cooling of the magnetic isolation slot channel, and a composite cooling channel with wind thorns at the air inlet. When the motor is working, under the promotion of the wind thorns, the cooling airflow passes through the rotor magnetic isolation slot to better cool the motor rotor, thereby achieving the purpose of enhanced heat exchange. Compared with simple rotor opening cooling, the present invention combines the two models of rotor slant pole and rotor magnetic isolation slot with wind thorns, and optimizes the combination from the two aspects of reducing eddy current loss and improving heat transfer coefficient, comprehensively improving the cooling effect of the motor, and can effectively solve the cooling problem of high-power open motors.

[0017] The beneficial effects of the present invention are:

[0018] 1) Solve the heat dissipation problem of high-power motor rotors to prevent the motor from significantly degrading its performance or even failing due to long-term operation in a high-temperature environment.

[0019] 2) In a limited cooling space, a magnetic isolation slot parallel to the oblique pole is set, and wind thorns are added on the air inlet side of the air magnetic isolation slot to improve the convection heat transfer coefficient in the magnetic isolation slot and better cool the motor.

[0020] 3) The motor loss is reduced by using rotor skew poles and air magnetic isolation slots, thus reducing the motor temperature rise from the source.

[0021] The present invention uses magnetic isolation grooves, oblique poles and inner hole heat dissipation in coordination with each other, starting from reducing losses and improving heat dissipation coefficients. Compared with a single cooling structure, the composite structure has a better effect on reducing temperature rise, and this cooling mechanism can be applied to more complex motors. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the rotor structure of the present invention;

[0023] Figure 2 This is a schematic diagram of the air-cooling circulation model of the present invention;

[0024] In the figure: 1. sheath, 2. magnetic isolation groove, 3. permanent magnet, 4. rotor core, 5. wind thorns, 6. oblique pole structure, 7. air outlet side, 8. air inlet side. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] like Figure 1 and Figure 2As shown, the composite rotor cooling mechanism of the permanent magnet synchronous traction motor of the present invention includes a rotor core 4 provided with a plurality of oblique pole structures 6 and a plurality of magnetic isolation grooves 2, a plurality of permanent magnets 3 are evenly spaced along the circumferential direction and arranged on the outer circumferential surface of the rotor core 4, a sleeve 1 is sleeved on the permanent magnets 3 and the rotor core 4 and is provided with a plurality of magnetic isolation grooves 2, and a plurality of wind thorns 5 are installed on the end face of the air inlet side 7 of the composite rotor cooling mechanism and are located at the magnetic isolation grooves 2 on the sleeve 1 and the rotor core 4.

[0027] The middle part of the rotor core 4 is a cylindrical structure arranged along the axial direction of the composite rotor cooling mechanism. A number of mutually parallel oblique pole structures 6 are evenly spaced on the circumferential surface of the cylindrical structure. The oblique pole structure 6 is a strip-shaped fan-shaped body bent with the same arc. The two end surfaces of the oblique pole structure 6 are respectively located on the same plane as the two end surfaces of the composite rotor cooling mechanism. A magnet slot is formed between every two oblique pole structures 6, and each permanent magnet 3 is arranged in one of its own magnet slots.

[0028] The magnetic isolation grooves 2 are provided on the oblique pole structure 6 and the jacket 1 on both sides of each permanent magnet 3. The magnetic isolation grooves 2 are provided on both sides of each permanent magnet 3 on the air inlet side 7 and the air inlet side 8 of the composite rotor cooling mechanism. Each two magnetic isolation grooves 2 on the air inlet side 7 and the air inlet side 8 are mutually connected along the length direction of the oblique pole structure 6 to form a cooling channel. The oblique pole structure 6 can reduce the axial flow length of the eddy current loss in the permanent magnet 3, and the magnetic isolation grooves 2 can increase the magnetic resistance. Both methods can reduce the rotor side loss, and both structures can reduce the generation of electromagnetic loss on the rotor side.

[0029] The wind thorn 5 is a two-section plate-shaped structure bent at 90 degrees. Each wind thorn 5 is evenly spaced along the circumference of the end face of the air inlet side 7 of the composite rotor cooling mechanism. Each wind thorn 5 surrounds a respective magnetic isolation groove 2. The direction of the magnetic isolation groove 2 from the jacket 1 to the oblique pole structure 6 is its own length direction. One section of the plate of the wind thorn 5 is located on the outer side of the magnetic isolation groove 2 and is perpendicular to the length direction of the magnetic isolation groove 2. The other section of the plate of the wind thorn 5 is located on the same side of the magnetic isolation groove 2 and is parallel to the length direction of the magnetic isolation groove 2. The other section of the plate of the wind thorn 5 and the end face of the composite rotor cooling mechanism are 45 degrees. Compared with the straight opening, the coordination of the oblique pole structure 6 opening channel and the wind thorn 5 will further reduce the deflection angle of the fluid, improve the convection coefficient of the fluid between the holes, and increase the heat dissipation capacity.

[0030] The motor cooling mechanism composed of the above principles can reduce the loss of the motor from the source, and then strengthen the cooling effect of the motor through convection cooling inside the rotor side. This reduces the possibility of motor failure and is also conducive to extending the service life of the motor. Overall, it also improves the reliability of motor operation.

[0031] The implementation of the present invention is applicable to surface-mounted permanent magnet synchronous motors, and provides an additional channel for heat dissipation of the motor with a rotor sheath 1, and has a better cooling effect on the motor permanent magnets 3 and the rotor core 4. Similarly, for other types of permanent magnet synchronous motors, the cooling structure principle can also be applied, providing a new solution for other types of rotor side cooling methods in the future.

Claims

1. A composite rotor cooling mechanism for a permanent magnet synchronous traction motor, Features: It comprises a rotor core (4) provided with a plurality of oblique pole structures (6) and a plurality of magnetic isolation slots (2); It comprises a plurality of permanent magnets (3) which are evenly spaced and arranged on the outer peripheral surface of a rotor core (4) along the circumferential direction; It comprises a sheath (1) which is sleeved on a permanent magnet (3) and a rotor core (4) and has a plurality of magnetic isolation grooves (2); It comprises a plurality of wind thorns (5) which are installed on the end surface of the air inlet side (7) of the composite rotor cooling mechanism and are located at the magnetic isolation grooves (2) on the jacket (1) and the rotor core (4).

2. The composite rotor cooling mechanism of the permanent magnet synchronous traction motor according to claim 1, Features: The middle part of the rotor core (4) is a cylindrical structure arranged along the axial direction of the composite rotor cooling mechanism. A plurality of mutually parallel oblique pole structures (6) are evenly spaced on the circumference of the cylindrical structure. The oblique pole structure (6) is a strip-shaped fan-shaped body bent with the same arc. The two end surfaces of the oblique pole structure (6) are respectively located on the same plane as the two end surfaces of the composite rotor cooling mechanism. A magnet slot is formed between every two oblique pole structures (6), and each permanent magnet (3) is arranged in a respective magnet slot.

3. The composite rotor cooling mechanism of the permanent magnet synchronous traction motor according to claim 1, Features: The magnetic isolation grooves (2) are arranged on the oblique pole structure (6) and the sleeve (1) on both sides of each permanent magnet (3); magnetic isolation grooves (2) are arranged on both sides of each permanent magnet (3) on the air inlet side (7) and the air inlet side (8) of the composite rotor cooling mechanism; and each two magnetic isolation grooves (2) opposite to each other on the air inlet side (7) and the air inlet side (8) are interconnected along the length direction of the oblique pole structure (6) to form a cooling channel.

4. The composite rotor cooling mechanism of the permanent magnet synchronous traction motor according to claim 1, Features: The wind thorns (5) are two-section bent plate-shaped structures, and each wind thorn (5) is evenly spaced along the circumference of the end face of the air inlet side (7) of the composite rotor cooling mechanism. Each wind thorn (5) surrounds a respective magnetic isolation groove (2), and the direction of the magnetic isolation groove (2) from the sheath (1) to the oblique pole structure (6) is its own length direction. One section of the wind thorn (5) is located on the outer side of the magnetic isolation groove (2) and is perpendicular to the length direction of the magnetic isolation groove (2), and the other section of the wind thorn (5) is located on the same side of the magnetic isolation groove (2) and is parallel to the length direction of the magnetic isolation groove (2). The other section of the wind thorn (5) and the end face of the composite rotor cooling mechanism are at 45 degrees.

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