Permanent Magnet Motor with Pole Arc Segmented Variable Permanent Magnets for Electric Vehicles

Abstract

The present invention provides a permanent magnet motor with segmented pole arcs and variable permanent magnets for electric vehicles, belonging to the technical field of automotive motor electrical appliances. Inside the rotor core, 4 √-shaped grooves are evenly distributed along the circumferential direction. An inverted √-shaped groove is provided between adjacent √-shaped grooves. V-shaped grooves are provided on the outer sides of both the √-shaped grooves and the inverted √-shaped grooves. First magnetic isolation grooves are provided at the inner ends of the long sides of the √-shaped grooves, and second magnetic isolation grooves are provided at the inner ends of the long sides of the inverted √-shaped grooves. Radial magnetic isolation grooves are provided between the long sides of the √-shaped grooves and the inverted √-shaped grooves. The √-shaped grooves and the inverted √-shaped grooves are symmetric about the radial magnetic isolation grooves. The pole arc of each magnetic pole is divided into three segments, and the magnetic field of each segment of the pole arc is provided by different permanent magnets. This motor adopts a double-layer permanent magnet structure, including an outer layer symmetric V-shaped permanent magnet structure, an inner layer asymmetric √-shaped permanent magnet structure, and an inverted √-shaped permanent magnet structure, enabling the adjustable magnetic pole magnetic field, more uniform magnetic field distribution, the smallest harmonic content of the air-gap magnetic density, reducing torque ripple and motor losses.

Description

Technical Field

[0001] The present invention provides a permanent magnet motor with pole arc segmented variable permanent magnets for electric vehicles, belonging to the technical field of automotive motor electrical appliances. Background Art

[0002] The air-gap magnetic density harmonics are composed of fluctuating components with different frequencies in the magnetic field. These fluctuations have a significant impact on the performance of the motor. Therefore, it is necessary to reduce the content of air-gap magnetic density harmonics and improve the sinusoidality of the air-gap magnetic density. At present, technologies for reducing air-gap magnetic density harmonics have been proposed. For example, in the prior art, the Chinese patent announced: A rotor of a multi-layer segmented built-in permanent magnet synchronous motor for electric vehicle drive, application number: 201610823516.5, discloses a rotor structure with three-layer segmented neodymium iron boron magnetic steel and magnetic barriers. By optimizing the pole arc coefficient of each layer of permanent magnets, the harmonic content of the air-gap magnetic density of the built-in permanent magnet synchronous motor rotor is minimized. The Chinese patent announced: A rotor of an in-built permanent magnet motor, application number: 201110380616.2, discloses a structure in which multiple permanent magnets are distributed at intervals inside the rotor, and multiple air slots are arranged at the ends of adjacent permanent magnets and close to the outer circumference of the rotor. By changing the magnitude of the rotor reluctance, an approximately sinusoidal air-gap magnetic density is generated. However, the rotor with a three-layer segmented magnetic steel structure makes the rotor structure relatively complex, increasing the manufacturing process and the cost of the motor; in the rotor disclosed in the second announced Chinese patent, the magnetic field will have a depression at the magnetic pole center, affecting the stability of the motor. Summary of the Invention

[0003] The technical problem to be solved by the present invention is: on the premise of ensuring no increase in processing procedures, process difficulty, and no significant change in the motor cost, overcoming the deficiencies of the prior art, providing a permanent magnet motor with pole arc segmented variable permanent magnets for electric vehicles. The structure of this motor is a double-layer permanent magnet with a permanent magnet motor having three pole arcs, and the three pole arcs are respectively provided with magnetic fluxes by different permanent magnets, improving the air-gap magnetic density waveform, reducing the distortion rate of the air-gap magnetic density waveform, weakening the cogging torque, and reducing magnetic leakage.

[0004] The technical solution adopted by the present invention to solve its technical problems is: A permanent magnet motor with pole arc segmented variable permanent magnets for electric vehicles, including a front end cover, a machine shell, a stator, a rear end cover, a rotating shaft, a rotor core, √-shaped grooves, reverse √-shaped grooves, V-shaped grooves, and permanent magnets, characterized in that:

[0005] The rotor core is evenly distributed with 4 √-shaped grooves along the circumferential direction. The long side of the √-shaped groove is perpendicular to the magnetic pole center line where the √-shaped groove is located, and the proximal ends of the √-shaped grooves are connected;

[0006] Reverse √-shaped grooves are provided between adjacent √-shaped grooves. The long side of the reverse √-shaped groove is perpendicular to the magnetic pole center line where the reverse √-shaped groove is located, and the proximal ends of the reverse √-shaped grooves are connected;

[0007] V-shaped grooves are provided in the middle of the outer sides of both the √-shaped groove and the reverse √-shaped groove, and the proximal ends of the V-shaped grooves are not connected;

[0008] A radial magnetic isolation groove is provided between the long sides of the √-shaped groove and the reverse √-shaped groove. The radial magnetic isolation groove is along the diameter direction of the rotor core, and the √-shaped groove and the reverse √-shaped groove are symmetric about the radial magnetic isolation groove;

[0009] The inner end of the long side of the √-shaped groove is the first magnetic isolation groove, and the inner end of the long side of the reverse √-shaped groove is the second magnetic isolation groove;

[0010] Permanent magnets are placed on the short sides of the √-shaped groove, permanent magnets are placed on the short sides of the reverse √-shaped groove, permanent magnets are placed on the outer ends of the long sides of the √-shaped groove, permanent magnets are placed on the outer ends of the long sides of the reverse √-shaped groove, and permanent magnets are placed in the V-shaped grooves.

[0011] There is a non-connected distance of 1.5 mm between the outer end of the short side of the √-shaped groove and the outer circle of the rotor core; there is a non-connected distance of 1.5 mm between the outer end of the short side of the reverse √-shaped groove and the outer circle of the rotor core;

[0012] There is a non-connected distance of 1.5 mm between the outer end of the radial magnetic isolation groove and the outer circle of the rotor core;

[0013] There is a non-connected distance of 1.5 mm between the outer end of the V-shaped groove and the outer circle of the rotor core;

[0014] The included angle of the √-shaped groove is greater than 90°;

[0015] The proximal end of the radial magnetic isolation groove is connected to the proximal end of the √-shaped groove, and the proximal end of the radial magnetic isolation groove is connected to the proximal end of the reverse √-shaped groove.

[0016] A single magnetic pole adopts a design of variable permanent magnets with segmented pole arcs, and the permanent magnet pole arc coefficients corresponding to each segment of the pole arc are optimized. The pole arc coefficient a1 of the permanent magnet inside the short side of the √-shaped groove is 0.21, the pole arc coefficient a2 of the permanent magnet in the V-shaped groove is 0.27, and the pole arc coefficient a3 of the permanent magnet inside the long side of the √-shaped groove is 0.31. At this time, the distortion rate of the air-gap magnetic density waveform is 23.1%, and the 5th, 7th, and 11th harmonics are greatly reduced.

[0017] Compared with the prior art, the present invention has the following technical effects:

[0018] (1) Adopting a double-layer permanent magnet structure, including an outer-layer symmetric V-shaped permanent magnet structure, an inner-layer asymmetric √-shaped permanent magnet structure, and a reverse √-shaped permanent magnet structure, enables the magnetic field of the magnetic pole to be adjustable and the magnetic field distribution to be more uniform;

[0019] (2) Compared with the traditional symmetric rotor structure, this structure divides each magnetic pole arc into three segments, and the magnetic fields of each segment of the pole arc are provided by different permanent magnets respectively. On the premise of ensuring that the motor has sufficient torque density, the harmonic content of the air-gap magnetic density is minimized, reducing torque ripple and motor loss;

[0020] (3) Radial magnetic barriers are used to separate adjacent permanent magnets of the poles, reducing the rotor mass while reducing the magnetic leakage between adjacent poles and improving the power density.

[0021] (4) With the same volume and permanent magnet usage, the total mass is smaller, the output torque is larger, and it has better electromagnetic performance.

[0022] Figure 1 It is a schematic diagram of the rotor structure of the present invention.

[0023] Figure 2 It is a comparison diagram of the magnetic flux density waveforms between the permanent magnet motor with segmented variable permanent magnets of pole arcs and the traditional U-shaped permanent magnet motor of the present invention.

[0024] In the figure: 1, rotating shaft; 2, rotor core; 3, √-shaped groove; 4, reverse √-shaped groove; 5, V-shaped groove. Specific implementation manner

[0025] The permanent magnet motor with segmented variable permanent magnets of pole arcs for electric vehicles includes a front end cover, a machine shell, a stator, a rear end cover, a rotating shaft 1, a rotor core 2, a √-shaped groove 3, a reverse √-shaped groove 4, a V-shaped groove 5, and permanent magnets, and is characterized in that:

[0026] Four √-shaped grooves 3 are evenly distributed along the circumference of the rotor core 2. The included angle of the √-shaped grooves 3 is greater than 90°. The long side of the √-shaped groove 3 is perpendicular to the center line of the pole where the √-shaped groove 3 is located, and the proximal ends of the √-shaped grooves 3 are connected.

[0027] A reverse √-shaped groove 4 is provided between adjacent √-shaped grooves 3. The included angle of the reverse √-shaped groove 4 is greater than 90°. The long side of the reverse √-shaped groove 4 is perpendicular to the center line of the pole where the reverse √-shaped groove 4 is located, and the proximal ends of the reverse √-shaped grooves 4 are connected.

[0028] V-shaped grooves 5 are provided in the middle of the outer sides of the √-shaped grooves 3 and the reverse √-shaped grooves 4. The two sides of the V-shaped groove 5 are symmetric about the center line of the pole where it is located, and the proximal ends of the V-shaped grooves 5 are not connected.

[0029] A radial magnetic isolation groove is provided between the long side of the √-shaped groove 3 and the long side of the reverse √-shaped groove 4. The radial magnetic isolation groove is along the diameter direction of the rotor core 2, and the √-shaped groove 3 and the reverse √-shaped groove 4 are symmetric about the radial magnetic isolation groove.

[0030] The inner end of the long side of the √-shaped groove 3 is the first magnetic isolation groove, and the inner end of the long side of the reverse √-shaped groove 4 is the second magnetic isolation groove.

[0031] Permanent magnets are placed in the short sides of the √-shaped grooves 3, permanent magnets are placed in the short sides of the reverse √-shaped grooves 4, permanent magnets are placed at the outer ends of the long sides of the √-shaped grooves 3, permanent magnets are placed at the outer ends of the long sides of the reverse √-shaped grooves 4, and permanent magnets are placed in the V-shaped grooves 5.

[0032] The sum of the length of the first magnetic isolation groove and the length of the permanent magnet inside the outer end of the long side of the √-shaped groove 3 is equal to the length of the long side of the √-shaped groove 3. The sum of the length of the second magnetic isolation groove and the length of the permanent magnet inside the outer end of the long side of the reverse √-shaped groove 4 is equal to the length of the long side of the reverse √-shaped groove 4;

[0033] There is a non-connected distance of 1.5 mm between the outer end of the short side of the √-shaped groove 3 and the outer circle of the rotor core 2; there is a non-connected distance of 1.5 mm between the outer end of the short side of the reverse √-shaped groove 4 and the outer circle of the rotor core 2;

[0034] There is a non-connected distance of 1.5 mm between the outer end of the radial magnetic isolation groove and the outer circle of the rotor core 2;

[0035] There is a non-connected distance of 1.5 mm between the outer end of the V-shaped groove 5 and the outer circle of the rotor core 2, and there is a non-connected distance of 1.5 mm between the proximal ends of the V-shaped groove 5.

[0036] The included angle of the √-shaped groove is greater than 90°, and the magnetic pole center line passes through the first magnetic isolation groove and the second magnetic isolation groove;

[0037] The radial magnetic isolation groove is connected to the proximal end of the √-shaped groove 3, and the radial magnetic isolation groove is connected to the proximal end of the reverse √-shaped groove 4.

[0038] A single magnetic pole adopts a design of segmented variable permanent magnets for the pole arc, and the pole arc coefficient of the permanent magnet corresponding to each pole arc segment is optimized. The pole arc coefficient a1 of the permanent magnet inside the short side of the √-shaped groove 3 is 0.21, the pole arc coefficient a2 of the permanent magnet inside the V-shaped groove 5 is 0.27, and the pole arc coefficient a3 of the permanent magnet inside the long side of the √-shaped groove 3 is 0.31. At this time, the distortion rate of the air-gap magnetic density waveform is 23.1%, and the 5th, 7th, and 11th harmonics are significantly reduced.

Claims

1. A permanent magnet motor with segmented arc variable permanent magnets for electric vehicles, comprising a front end cover, a housing, a stator, a rear end cover, a rotating shaft (1), a rotor core (2), √-shaped grooves (3), reverse √-shaped grooves (4), V-shaped grooves (5), and permanent magnets, characterized in that: Four √-shaped grooves (3) are evenly distributed along the circumferential direction of the rotor core (2). The long sides of the √-shaped grooves (3) are perpendicular to the center line of the magnetic pole where the √-shaped grooves (3) are located, and the proximal ends of the √-shaped grooves (3) are connected; Reverse √-shaped grooves (4) are provided between adjacent √-shaped grooves (3). The long sides of the reverse √-shaped grooves (4) are perpendicular to the center line of the magnetic pole where the reverse √-shaped grooves (4) are located, and the proximal ends of the reverse √-shaped grooves (4) are connected; V-shaped grooves (5) are provided in the middle of the outer sides of the √-shaped grooves (3) and the reverse √-shaped grooves (4), and the proximal ends of the V-shaped grooves (5) are not connected; A radial magnetic isolation groove is provided between the long side of the √-shaped groove (3) and the long side of the reverse √-shaped groove (4). The radial magnetic isolation groove is along the diameter direction of the rotor core (2), and the √-shaped groove (3) and the reverse √-shaped groove (4) are symmetric about the radial magnetic isolation groove; The inner end of the long side of the √-shaped groove (3) is the first magnetic isolation groove, and the inner end of the long side of the reverse √-shaped groove (4) is the second magnetic isolation groove; Permanent magnets are placed in the short sides of the √-shaped grooves (3), permanent magnets are placed in the short sides of the reverse √-shaped grooves (4), permanent magnets are placed at the outer ends of the long sides of the √-shaped grooves (3), permanent magnets are placed at the outer ends of the long sides of the reverse √-shaped grooves (4), and permanent magnets are placed in the V-shaped grooves (5).

2. The permanent magnet motor with segmented permanent magnets for the pole arc of an electric vehicle according to claim 1, characterized in that: There is a non-connected distance of 1.5 mm between the outer end of the short side of the √-shaped groove (3) and the outer circle of the rotor core (2); there is a non-connected distance of 1.5 mm between the outer end of the short side of the reverse √-shaped groove (4) and the outer circle of the rotor core (2); There is a non-connected distance of 1.5 mm between the outer end of the radial magnetic isolation groove and the outer circle of the rotor core (2); There is a non-connected distance of 1.5 mm between the outer end of the V-shaped groove (5) and the outer circle of the rotor core (2); The included angle of the √-shaped groove (3) is greater than 90°; 3. The permanent magnet motor with segmented permanent magnets of pole arc for electric vehicles according to claim 1, characterized in that: The radial magnetic isolation groove is connected to the proximal end of the √-shaped groove (3), and the radial magnetic isolation groove is connected to the proximal end of the reverse √-shaped groove (4); 4. The permanent magnet motor with segmented permanent magnets of pole arc for electric vehicles according to claim 1, characterized in that: The pole arc of each magnetic pole is divided into three segments, and the magnetic fields of each segment of the pole arc are provided by different permanent magnets respectively. The magnetic field of the first segment of the pole arc in the magnetic pole where the √-shaped groove (3) is located is provided by the permanent magnet in the short side of the √-shaped groove (3), the magnetic field of the second segment of the pole arc in the magnetic pole where the √-shaped groove (3) is located is provided by the permanent magnets on both sides of the V-shaped groove (5), and the magnetic field of the third segment of the pole arc in the magnetic pole where the √-shaped groove (3) is located is provided by the permanent magnet at the outer end of the long side of the √-shaped groove (3).

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