High-voltage power frequency operation permanent magnet synchronous motor rotor structure

Abstract

The invention discloses a high-voltage power frequency operation permanent magnet synchronous motor rotor structure which comprises permanent magnet magnetic steel and a rotor punching sheet, the rotor punching sheet is concentrically matched with a stator punching sheet of a high-voltage power frequency operation permanent magnet synchronous motor, and a uniform air gap is reserved between the outer diameter of a rotor and the inner diameter of a stator. The rotor punching sheet is internally provided with a permanent magnet magnetic steel groove, a conducting bar groove for arranging a rotor conducting bar and a ventilation hole, the rotor punching sheet is provided with an inner circle for placing a rotating shaft, and interference fit is realized through hot sleeving of the rotating shaft and the inner circle of the rotor. The internal structural layout of the rotor is optimized, the overall electromagnetic performance of the motor is improved, higher power density is expected to be achieved for existing permanent magnet products in the market, and therefore the lower product cost under the same specification requirement is met, and the rotor has the advantages of being good in structural strength, high in power density and good in heat dissipation performance.

Description

Technical Field

[0001] The invention relates to the technical field of high-voltage permanent magnet motors, and in particular to a rotor structure of a high-voltage permanent magnet motor with variable frequency starting and industrial frequency operation. Technical Background

[0002] In the field of industrial drive, high-voltage permanent magnet synchronous motors have attracted extensive attention from the industry and have been promoted in a variety of application scenarios due to their low rotor loss and high power factor compared to traditional asynchronous motors of the same specifications. Permanent magnet motor products currently on the market can be divided into three categories: variable frequency operation, variable frequency starting and industrial frequency operation, and self-starting operation, according to different starting and operating modes.

[0003] Specifically, the variable frequency running permanent magnet motor needs to be used in conjunction with the frequency converter. Its rotor structure is simple and does not require guide bars, but it has a significant disadvantage, that is, it cannot be disconnected from the frequency converter and connected to the grid independently. The rotors of permanent magnet motors that are running at industrial frequency and self-starting at variable frequency starting need to be arranged with guide bars. The main difference between the two is that the guide bar size and performance of the self-starting variable frequency permanent magnet motor need to take into account the heat generation and load impact during starting, while the guide bar starting requirements of the permanent magnet motor that is running at industrial frequency and variable frequency starting have relatively low requirements, and can be connected to the grid after the frequency converter is started, thereby realizing one frequency converter driving multiple motors.

[0004] Although permanent magnet motor products have been used to a certain extent, there are still some shortcomings in the design of existing products, which limit the wider promotion of products. The main problems include:

[0005] 1) Compared with traditional asynchronous motors, permanent magnet motors have lower product power density. Due to the mutual constraints between the electromagnetic properties of permanent magnets and the ventilation and heat dissipation characteristics, the heat dissipation performance is limited when the total volume is constant;

[0006] 2) In the design of permanent magnet rotor laminations with rotor bars (i.e. damping system), the distance between the bar slots and the magnetic steel slots is too close, which easily leads to structural weaknesses. In addition, the uniformly distributed bar slots affect the optimal arrangement of the magnetic steel slots, and also limit the optimization design space of the bar slots in the later stage.

[0007] In summary, the shortcomings and deficiencies of the current permanent magnet motor design are manifested in the low power density and the mutual influence between the arrangement of the damping slots and the magnetic steel slots.

[0008] Regarding the power density, under the condition of a certain total volume, increasing the magnetic steel and magnetic conductive materials can improve the electromagnetic performance and power, but correspondingly, the loss increases and the ventilation area decreases. At present, the rotor part of the mainstream permanent magnet motor adopts V-shaped, one-shaped or combined magnetic steel arrangement. The rotor core is connected to the welded or milled rib shaft by thermal sleeve. The air enters axially through the gap between the shaft and the core, and the inside of the rotor is cooled by radial air ducts. To improve the power density, it is necessary to combine the electromagnetic design with the ventilation design to achieve the optimal electromagnetic design within the temperature rise limit.

[0009] The rotor damping and magnet arrangement have mutual constraints between electromagnetic design and structural design in a limited space. The magnets are arranged in a traditional V-shape or one-shape, and considering the gaps to be reserved when assembling the magnets, the actual magnet slots will inevitably occupy the space at the outer diameter of the rotor. When arranging the damping slots, if the two are too close, there will be less core material left in the middle of the slots, which will become a structural weak point both during the core punching process and when the motor is running. Summary of the invention

[0010] The purpose of the present invention is to overcome the defects of the prior art and to provide a high-voltage industrial frequency operating permanent magnet synchronous motor rotor structure, which can overcome the shortcomings of low rotor structural strength and the inability to balance electromagnetic performance and heat dissipation, and has the advantages of good structural strength, high power density and good heat dissipation performance.

[0011] The technical solution to achieve the above-mentioned purpose is: a rotor structure of a high-voltage industrial frequency permanent magnet synchronous motor, including a permanent magnet steel and a rotor punching. The rotor punching is concentrically matched with the stator punching of the high-voltage industrial frequency permanent magnet synchronous motor, and a uniform air gap is left between the outer diameter of the rotor and the inner diameter of the stator. It is characterized in that the rotor punching is provided with slots for arranging permanent magnet steel slots, slots for arranging rotor bars, and ventilation holes. The rotor punching is provided with an inner circle for placing a rotating shaft, and an interference fit is achieved by shrink fitting the rotating shaft and the inner circle of the rotor.

[0012] In the above-mentioned high-voltage industrial frequency operating permanent magnet synchronous motor rotor structure, six pairs of permanent magnet steel slots are opened inside the rotor punching sheet, and the shape is W-shaped.

[0013] In the above-mentioned high-voltage industrial frequency operating permanent magnet synchronous motor rotor structure, eleven rectangular guide bar grooves are provided inside each pair of permanent magnet magnetic steel slots, and the guide bar grooves are used to arrange rotor guide bars.

[0014] In the above-mentioned high-voltage industrial frequency operating permanent magnet synchronous motor rotor structure, the rotor punchings are provided with distributed ventilation holes on the inner side of each pair of magnetic steel slots near the inner diameter of the rotor for forming an axial air inlet duct after assembly.

[0015] In the above-mentioned high-voltage industrial frequency operating permanent magnet synchronous motor rotor structure, according to the coupling factor between the ventilation hole and the magnetic circuit of the magnetic steel, the shape of the ventilation hole is determined to be an irregular shape, and the irregular shape is composed of six sides divided into three sides symmetrically distributed on the left and right, and has sharp corners on the inner side of each pair of magnetic steel slots, and is relatively blunt near the inner diameter of the rotor, so as to achieve sufficient ventilation circuit for the motor on the basis of the magnetic circuit of the magnetic steel.

[0016] The beneficial effects of the present invention are: it can optimize the internal structure layout of the rotor, improve the overall electromagnetic performance of the motor, and is expected to achieve higher power density than existing permanent magnet products on the market, thereby meeting lower product costs under the same specification requirements. The present invention has the advantages of good structural strength, high power density, and good heat dissipation performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of a punching sheet of a stator and rotor structure of a high-voltage power-frequency operating permanent magnet synchronous motor of the present invention;

[0018] Figure 2 yes Figure 1 A is a partial enlarged schematic diagram in FIG.

[0019] Explanation of the numbers in the figure: 1. stator punching sheet, 2. rotor punching sheet, 3. rotor inner circle, 4. magnetic steel slot, 5. rotor guide bar slot, 6. ventilation hole, 8. magnetic steel, 9. rotor guide bar, 10. stator coil. DETAILED DESCRIPTION

[0020] In order to better understand the technical solution of the present invention, the following is a detailed description through specific embodiments in conjunction with the accompanying drawings:

[0021] like Figure 1 As shown, a stator and rotor punching of a high-voltage variable frequency starting power frequency running motor stator and rotor structure, the stator punching 1 is consistent with the stator punching of a traditional asynchronous motor, and the inner diameter of the punching is provided with evenly distributed open slots along the circumference for arranging the stator coil. The rotor punching 2 is concentrically matched with the stator punching, and a uniform air gap is left between the outer diameter of the rotor and the inner diameter of the stator.

[0022] The rotor punching has magnetic steel slots 4 for arranging permanent magnets, slots 5 for arranging rotor bars, and ventilation holes 6. The rotor punching has an inner circle 3 for placing a solid shaft with the same circular cross-section. The shaft and the rotor inner circle are heat-shrink-fitted to achieve interference fit.

[0023] like Figure 1 As shown, the rotor punching provided by the present invention has six pairs of permanent magnet steel slots in the interior, and the shape forms a W shape. Each pair of permanent magnets is arranged as follows Figure 2As shown. The rotor punching surface is evenly spaced with 11*6=66 ​​rectangular slots along the diameter direction, that is, each magnetic pole W-shaped has 11 rectangular slots inside for arranging rotor bars. Different from the existing permanent magnet synchronous motor rotor bar slots uniformly distributed on the rotor surface, the present invention takes into account that if the rotor bar slots are uniformly distributed in the circumferential direction, they will interfere with the magnetic steel slot space, so the bar slot design of the interfering part is cancelled, and the remaining number of bars can still meet the function of providing damping for the permanent magnet motor power frequency operation.

[0024] like Figure 2 As shown, the rotor punching sheet has distributed ventilation holes 6 on the inner side of the magnetic steel slot near the inner diameter of the rotor, which are used to form an axial air inlet after assembly. The ventilation holes 6 are coupled with the magnetic circuit of the magnetic steel 8. After calculation and optimization, irregular-shaped ventilation holes 6 are used. The irregular shape is composed of six sides divided into three sides with left-right symmetrical distribution, and sharp angles are present on the inner side of each pair of magnetic steel slots 4, and the sharp angles are relatively blunt near the inner diameter of the rotor, so that the motor can meet the sufficient ventilation circuit on the basis of the magnetic circuit of the magnetic steel 8. By preparing the corresponding mold, the punching of special-shaped ventilation holes can be realized.

[0025] In this way, the shape of the ventilation hole makes the magnetic circuit space larger on the outside and smaller on the inside, so that the overall magnetic circuit is balanced and there is no saturation point.

[0026] The solution of the present invention solves the problem of the original bar grooves of the permanent magnet motor with rotor bars and the rotor magnetic steel grooves occupying each other from a structural point of view. By eliminating the original uniformly distributed bar grooves at the magnetic steel grooves, the magnetic steel can be arranged in an optimized arrangement shape to improve the electromagnetic performance.

[0027] In addition, reference Figure 2 The relative position relationship between the guide bar and the magnetic steel slot is shown, and the two are not affected by the offset. This provides space for the subsequent optimization of the shape and size of the rotor guide bar. The damping effect of the rotor guide bar can be optimized and adjusted according to the actual working conditions of the motor, and even expanded to a self-starting rotor guide bar design.

[0028] In terms of ventilation, the traditional rotor core shaft ventilation is changed to an air duct on the rotor core. Through this change, the shape of the rotor ventilation hole can be designed in an irregular shape, so that the magnetic field distribution of the permanent magnet in the rotor core is optimized, and the electromagnetic performance is further optimized. The special ventilation hole shape can be realized on the core punching sheet with the help of a mold, and its processing difficulty is lower than that of the rotating shaft welding or milling ribs.

[0029] The present invention is described in detail above in conjunction with the embodiments of the accompanying drawings. A person skilled in the art can make various variations of the present invention according to the above description. Therefore, certain details in the embodiments should not constitute a limitation of the present invention, and the scope of protection of the present invention shall be defined by the scope of the attached claims.

Claims

1. A rotor structure of a high-voltage power-frequency permanent magnet synchronous motor, comprising a permanent magnet steel (8) and a rotor punching (2), wherein the rotor punching (2) is concentrically matched with a stator punching (1) of the high-voltage power-frequency permanent magnet synchronous motor, and a uniform air gap is left between the outer diameter of the rotor and the inner diameter of the stator, characterized in that: The rotor punching sheet has a permanent magnet steel slot (4), a rotor bar slot (5), and a ventilation hole (6) inside. The rotor punching sheet has an inner circle (3) for placing a rotating shaft, and an interference fit is achieved by shrink-fitting the rotating shaft with the rotor inner circle.

2. A high voltage power frequency operating permanent magnet synchronous motor rotor structure according to claim 1, characterized in that: A total of six pairs of permanent magnet steel slots (4) are provided inside the rotor punching sheet, and the shape is W-shaped.

3. A high voltage power frequency operating permanent magnet synchronous motor rotor structure according to claim 2, characterized in that: Eleven rectangular guide bar grooves (5) are arranged inside each pair of permanent magnet magnetic steel grooves, and the guide bar grooves are used for arranging rotor guide bars.

4. A high voltage power frequency operating permanent magnet synchronous motor rotor structure according to claim 1 or 2, characterized in that: The rotor punching sheet is provided with distributed ventilation holes (6) on the inner side of each pair of magnetic steel slots (4) near the inner diameter of the rotor, so as to form an axial air inlet duct after assembly.

5. A high voltage power frequency operating permanent magnet synchronous motor rotor structure according to claim 4, characterized in that: According to the coupling factor between the ventilation hole (6) and the magnetic circuit of the magnetic steel (8), it is determined that the shape of the ventilation hole (6) is an irregular shape, that is, the six sides are divided into three sides and are symmetrically distributed on the left and right, and the inner side of each pair of magnetic steel slots (4) is sharp-angled, and the sharp angle is relatively blunt near the inner diameter of the rotor, so that on the basis of the magnetic circuit of the magnetic steel (8), a sufficient ventilation circuit of the motor can be achieved.

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