An asynchronous starting permanent magnet synchronous motor with an asymmetric built-in alternating pole structure

Abstract

The present invention discloses an asynchronous starting permanent magnet synchronous motor with an asymmetric built-in alternating pole structure, belonging to the technical field of permanent magnet motors. The motor rotor core (1) is formed by laminating punching sheets, and a plurality of rotor slots of the same slot size arranged at intervals are arranged on the surface. Non-magnetic cage windings (2) and magnetic cage windings (3) are mixedly arranged inside the rotor core (1). A plurality of rotor permanent magnets (4) are embedded at intervals inside the rotor core (1), and the permanent magnet poles and iron poles corresponding to the rotor permanent magnets (4) are arranged alternately along the circumferential direction. The non-magnetic cage windings (2) and the magnetic cage windings (3) are arranged such that a plurality of cage windings on one side of the central axis of the permanent magnet poles are magnetic cage windings (3), and the remaining cage windings are non-magnetic cage windings (2). Asymmetric iron poles (5) are arranged between the cage windings arranged at intervals. The present invention can effectively improve the starting performance of the motor, ensure the output torque of the motor, and effectively reduce the harmonic content and cogging torque in the air gap flux density.

Description

Technical Field

[0001] The present invention belongs to the technical field of permanent magnet motors, and in particular relates to an asynchronous starting permanent magnet synchronous motor with an asymmetric built-in alternating pole structure, which is suitable for related airborne equipment of a certain type of civil aircraft. Background Art

[0002] According to the relevant standards CCAR-25-R4, "Airworthiness Standards for Transport Category Aircraft," and GJB299C-2006, "Electronic Equipment Reliability Prediction Handbook," motors used in civil aircraft must be reliable, easy to maintain, and capable of reducing takeoff weight. Therefore, asynchronous-start permanent magnet synchronous motors, characterized by their self-starting capability, light weight, simple structure, high efficiency, and high power factor, offer significant advantages in their application in civil aircraft-related airborne equipment.

[0003] At present, most asynchronous start permanent magnet synchronous motors have built-in permanent magnet rotors, and their application still has some problems: during the starting process, due to the slip rate between the stator magnetic field and the permanent magnet magnetic field, a braking torque is generated, affecting the starting performance of the motor; due to the presence of the squirrel cage winding, the volume of the permanent magnet is limited and sufficient output torque cannot be obtained; the squirrel cage winding will generate a large current during the starting process, increasing the risk of permanent magnet demagnetization; the motor stator and rotor are slotted on both sides, resulting in a large motor cogging torque and an increase in the harmonic content of the air gap magnetic field.

[0004] Regarding self-starting permanent magnet synchronous motors, CN201110046135.8 provides a self-starting permanent magnet synchronous motor with composite starting bars. This patent utilizes a composite material of brass and copper-iron alloy to increase the rotor resistance of a single squirrel-cage bar, resulting in a motor with a low starting current and moderate starting torque. However, this motor increases the difficulty of the motor's manufacturing process and reduces its steady-state performance.

[0005] For permanent magnet synchronous motors with alternating-pole structures, CN113489200A proposes an alternating-pole rotor with asymmetric magnetic steel. Each pole of this patented rotor contains at least two magnets with asymmetric magnet sizes. The resulting alternating-pole permanent magnet synchronous motor has high and stable output. However, this patented rotor has low structural strength and suffers from uneven air gap flux density. Summary of the Invention

[0006] The purpose of the present invention is to overcome the problems of poor starting performance, insufficient output torque, large starting current, high cogging torque and air gap magnetic field harmonics of the current asynchronous starting permanent magnet synchronous motor. To this end, the present invention provides an asynchronous starting permanent magnet synchronous motor with an asymmetric built-in alternating pole structure.

[0007] This asynchronous starting permanent magnet synchronous motor with an asymmetric built-in alternating pole structure includes a rotor core, a non-magnetic cage winding, a magnetic cage winding, a rotor permanent magnet, and an asymmetric iron pole. The surface of the rotor core is provided with a plurality of rotor slots of the same slot shape and size arranged at intervals, and a non-magnetic cage winding and a magnetic cage winding are arranged inside. A plurality of rotor permanent magnets are embedded at intervals on the inner side of the rotor core, and the permanent magnetic poles corresponding to the rotor permanent magnets are arranged alternately with the iron poles along the circumferential direction. The arrangement of the non-magnetic cage winding and the magnetic cage winding is such that a plurality of cage windings on one side of the central axis of the permanent magnet pole are magnetic cage windings, and the remaining cage windings are all non-magnetic cage windings. Asymmetric iron poles are arranged between the spaced cage windings.

[0008] Furthermore, the squirrel cage winding uses non-magnetic materials with low magnetic permeability and high electrical conductivity, including but not limited to cast aluminum or brass; the used magnetic materials have high magnetic permeability and low electrical conductivity, including but not limited to 1010 steel bars or Sendust alloy.

[0009] Furthermore, the rotor permanent magnets have the same size and magnetizing direction, and a magnetic isolation bridge is provided at the end of the rotor permanent magnet; the magnetic pole structure includes but is not limited to V-type, bipolar, W-type, and straight-line magnetic poles.

[0010] Furthermore, the asymmetric iron poles have different pole arc widths, and the pole arc width of the iron pole close to the magnetic squirrel cage winding is larger.

[0011] Compared with the existing technology, the advantages of the present invention are: the use of an alternating pole structure reduces the braking torque generated during the starting process, increases the utilization rate of the permanent magnet, and improves the starting performance; a magnetic squirrel cage winding is arranged on one side of the central axis of the permanent magnet pole, and the magnetic field offset effect is utilized to increase the output torque and reduce torque pulsation; the selected magnetic material has a high resistivity, which reduces the starting current and improves the starting performance; the asymmetric iron pole structure weakens the harmonic content of the air gap magnetic field and reduces the slot torque of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Schematic diagram of the cross section of an asynchronous starting permanent magnet synchronous motor with an asymmetric built-in alternating pole structure;

[0013] Figure 2 This is a partial enlarged cross-section of the permanent magnet poles of an asynchronous starting permanent magnet synchronous motor with an asymmetric built-in alternating pole structure; DETAILED DESCRIPTION

[0014] The embodiments of the present invention will be further described with reference to the accompanying drawings.

[0015] The present invention proposes an asynchronous starting permanent magnet synchronous motor with an asymmetric built-in alternating pole structure. Figure 1As shown in the cross-sectional diagram of the asynchronous start permanent magnet synchronous motor with an asymmetric built-in alternating pole structure, the asynchronous start permanent magnet synchronous motor with an asymmetric built-in alternating pole structure has a uniform air gap structure, and the rotor core is formed by stacking a number of rotor punchings.

[0016] The rotor core (1) is made of silicon steel material with the grade of DW310. Thirty rotor slots with the same slot size are arranged at intervals on the surface of the rotor core (1) and a non-magnetic squirrel cage winding (2) and a magnetic squirrel cage winding (3) are provided. The rotor core (1) includes permanent magnet poles and iron poles arranged alternately along the circumferential direction. Four permanent magnet embedding slots are provided on the permanent magnet poles for embedding permanent magnets (4). The iron poles arranged between the rotor slots are asymmetric iron poles (5) with different pole arc widths.

[0017] The rotor slot is a trapezoidal open slot, in which a non-magnetic squirrel cage winding (2) and a magnetic squirrel cage winding (3) are arranged. Figure 2 As shown, two cage bars made of magnetic conductive material are inserted into the squirrel cage winding on one side of the permanent magnet pole center axis, and the remaining squirrel cage windings are all inserted with squirrel cage bars made of non-magnetic conductive material. The magnetic conductive material is 1010 steel bar, and the non-magnetic conductive material is brass. The non-magnetic cage winding (2) and the magnetic cage winding (3) are mixed and distributed. There is no need to set up magnetic barrier asymmetry or magnetic steel asymmetry. The magnetic field offset effect is utilized without reducing the rotor structural strength or increasing the processing difficulty. The following formula is the output torque expression under the conditions of symmetrical and asymmetric magnetic circuits:

[0018]

[0019] Among them, T out Indicates the motor's combined output torque, T pm Represents the permanent magnet torque of the motor, T rel Represents the motor reluctance torque, α represents the intrinsic angle difference between the permanent magnet torque and the reluctance torque peak value, α mfs The magnetic field offset position angle is represented by φ(1). The pole arc angle corresponding to the magnetic cage winding (3) is used as an optimization factor to improve the output torque of the motor. In addition, the 1010 steel bar is a material with high magnetic permeability and low electrical conductivity, which increases the rotor resistance, reduces the starting current generated by the cage winding during starting, and improves the starting performance of the motor.

[0020] The permanent magnet poles are provided with permanent magnet embedding grooves for embedding permanent magnets (4), which are embedded symmetrically in a V-shape. Magnetic isolation bridges are provided at both ends of the permanent magnets (4). The magnetic steel material adopts samarium cobalt permanent magnets to improve the reliability of the permanent magnets (4) when used in civil aircraft-related airborne equipment. The magnetization directions of the embedded permanent magnets (4) are all the same, and the number of rotor poles is equal to the number of pole pairs, forming an alternating pole structure. The alternating pole structure improves the utilization rate of the permanent magnets. When applied to the structure of an asynchronous starting permanent magnet synchronous motor, the amount of permanent magnets used is reduced. During the starting process, the braking torque generated by the slip rate between the stator magnetic field and the rotor permanent magnet magnetic field improves the starting ability of the motor to a certain extent.

[0021] The asymmetric iron pole (5) has unequal pole arc widths, and the pole arc width of the iron pole on one side close to the magnetic cage winding is greater than the corresponding pole arc width of the iron pole on the other side. By taking the air gap magnetic flux harmonics as the optimization target and the asymmetric iron pole pole arc width as the optimization factor (the asymmetric iron pole pole arc width should not be too large, which affects the self-starting ability of the motor), the harmonic content in the air gap magnetic flux, especially the even harmonics, can be greatly reduced, and the cogging torque of the motor can be reduced.

[0022] The asynchronous starting permanent magnet synchronous motor with an asymmetric built-in alternating pole structure of the present invention can effectively improve the starting performance of the motor, ensure the output torque of the motor, and effectively reduce the harmonic content and cogging torque in the air gap flux density. It has reliable structural strength and is easy to manufacture, and has good application prospects in the field of civil aircraft-related airborne equipment.

[0023] The above are only preferred embodiments of the present invention, which are used to help understand the present invention. Any changes or improvements made by relevant technical personnel without departing from the technical ideas of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. An asynchronous starting permanent magnet synchronous motor with an asymmetric internal alternating pole structure, characterized by: The invention comprises a rotor core (1), a non-magnetic cage winding (2), a magnetic cage winding (3), a rotor permanent magnet (4), and an asymmetric iron pole (5); the surface of the rotor core (1) is provided with a plurality of rotor slots of the same slot shape and size arranged at intervals, and the non-magnetic cage winding (2) and the magnetic cage winding (3) are arranged inside the rotor core (1); a plurality of rotor permanent magnets (4) are embedded at intervals inside the rotor core (1), and the permanent magnetic poles and the iron poles corresponding to the rotor permanent magnets (4) are arranged alternately along the circumferential direction; the arrangement of the non-magnetic cage winding (2) and the magnetic cage winding (3) is such that a plurality of cage windings on one side of the permanent magnetic pole center axis are magnetic cage windings (3), and the remaining cage windings are all non-magnetic cage windings (2); and asymmetric iron poles (5) are arranged between the cage windings arranged at intervals.

2. The asynchronous start permanent magnet synchronous motor with an asymmetric internal alternating pole structure according to claim 1, characterized in that: The non-magnetic squirrel cage winding (2) and the magnetic squirrel cage winding (3) use non-magnetic materials including but not limited to cast aluminum or brass, and use magnetic materials including but not limited to 1010 steel bars or Sendust aluminum alloy.

3. The asynchronous start permanent magnet synchronous motor with an asymmetric internal alternating pole structure according to claim 1, characterized in that: The rotor permanent magnets (4) have the same size and magnetization direction, and are provided with magnetic isolation bridges at both ends; the magnetic pole structures include but are not limited to V-type, bipolar, W-type, and straight-line magnetic poles.

4. The asynchronous start permanent magnet synchronous motor with an asymmetric internal alternating pole structure according to claim 1, characterized in that The asymmetric iron pole (5) has different pole arc widths, and the pole arc width of the iron pole close to the magnetic cage winding is larger.

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