Permanent magnet motor of pole-arc segmented variable permanent magnet for electric automobile

Abstract

The invention provides a permanent magnet motor of a pole-arc segmented variable permanent magnet for an electric automobile, and belongs to the technical field of automobile motors and electric appliances. Four V-shaped grooves are evenly distributed in the rotor core in the circumferential direction, reverse V-shaped grooves are formed between every two adjacent V-shaped grooves, V-shaped grooves are formed in the outer sides of the V-shaped grooves and the reverse V-shaped grooves, first magnetic isolation grooves are formed in the inner ends of the long edges of the V-shaped grooves, second magnetic isolation grooves are formed in the inner ends of the long edges of the reverse V-shaped grooves, radial magnetic isolation grooves are formed between the long edges of the V-shaped grooves, and the radial magnetic isolation grooves are formed in the outer sides of the V-shaped grooves. The V-shaped grooves and the reverse V-shaped grooves are symmetrical about the radial magnetic isolation grooves, the pole arc of each magnetic pole is divided into three sections, the magnetic field of each section of the pole arc is provided by different permanent magnets, and the motor adopts a double-layer permanent magnet structure which comprises an outer-layer symmetrical V-shaped permanent magnet structure, an inner-layer asymmetrical V-shaped permanent magnet structure and a reverse V-shaped permanent magnet structure, so that the magnetic field of the magnetic poles is adjustable. The magnetic field distribution is more uniform, the air gap flux density harmonic content is minimum, and the torque pulsation and the motor loss are reduced.

Description

Technical Field

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

[0002] The air gap flux harmonics are composed of fluctuating components of 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 harmonic content of the air gap flux and improve the sinusoidal nature of the air gap flux. At present, the technology of reducing the harmonics of the air gap flux has been proposed, such as the prior art, the published Chinese patent: a multi-layer segmented internal permanent magnet synchronous motor rotor for electric vehicle drive, application number: 201610823516.5, discloses a rotor structure with three-layer segmented NdFeB magnets and magnetic barriers, and minimizes the harmonic content of the air gap flux of the internal permanent magnet synchronous motor rotor by optimizing the pole arc coefficient of each layer of permanent magnets. The published Chinese patent: a rotor of an internal permanent magnet motor, application number: 201110380616.2, discloses a structure in which multiple permanent magnets are spaced and distributed 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, and an approximately sinusoidal air gap flux is generated by changing the size of the rotor magnetic resistance. However, the rotor with a three-layer segmented magnetic steel structure makes the rotor structure more complicated, increasing the manufacturing process and motor cost; the arrangement of permanent magnets in the rotor disclosed in the second published Chinese patent will produce a depression in the magnetic field at the center of the magnetic pole, affecting the stability of the motor. Summary of the invention

[0003] The technical problem to be solved by the present invention is: under the premise of ensuring that the processing procedures are not increased, the process difficulty and the motor cost are not greatly changed, the shortcomings of the prior art are overcome, and a permanent magnet motor with a pole arc segmented variable permanent magnet for electric vehicles is provided. The motor structure is a double-layer permanent magnet, a permanent magnet motor with three pole arcs, and the three pole arcs are provided with magnetic flux by different permanent magnets respectively, thereby improving the air gap magnetic flux waveform, reducing the air gap magnetic flux waveform distortion rate, weakening the cogging torque, and reducing leakage flux.

[0004] The technical solution adopted by the present invention to solve the technical problem is: a permanent magnet motor with a pole arc segmented permanent magnet for electric vehicles, comprising a front cover, a housing, a stator, a rear cover, a rotating shaft, a rotor core, a √-shaped groove, an inverse √-shaped groove, a V-shaped groove, and a permanent magnet, characterized in that: The rotor core has four √-shaped slots evenly distributed along the circumference, the long sides of the √-shaped slots are perpendicular to the center lines of the magnetic poles where the √-shaped slots are located, and the proximal ends of the √-shaped slots are connected; An inverted √-shaped groove is provided between adjacent √-shaped grooves, the long side of the inverted √-shaped groove is perpendicular to the center line of the magnetic pole where the inverted √-shaped groove is located, and the proximal ends of the inverted √-shaped grooves are connected; A V-shaped groove is provided in the middle of the outer sides of the √-shaped groove and the reverse √-shaped groove, and the proximal ends of the V-shaped groove are not connected; A radial magnetic isolation groove is provided between the long side of the √-shaped groove and the long side of the anti-√-shaped groove. The radial magnetic isolation groove is along the diameter direction of the rotor core. The √-shaped groove and the anti-√-shaped groove are symmetrical about the radial magnetic isolation groove. 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; A permanent magnet is placed on the short side of the √-shaped slot, a permanent magnet is placed on the short side of the reverse √-shaped slot, a permanent magnet is placed on the outer end of the long side of the √-shaped slot, a permanent magnet is placed on the outer end of the long side of the reverse √-shaped slot, and a permanent magnet is placed inside the V-shaped slot.

[0005] There is a 1.5mm non-connected distance between the outer end of the short side of the √ slot and the outer circle of the rotor core; There is a 1.5mm non-connected distance between the outer end of the short side of the reverse √ slot and the outer circle of the rotor core; There is a 1.5mm disconnected distance between the outer end of the radial magnetic isolation slot and the outer circle of the rotor core; There is a 1.5mm disconnected distance between the outer end of the V-slot and the outer circle of the rotor core; √The angle of the groove is greater than 90°.

[0006] The radial magnetic isolation groove is connected with the proximal end of the √-shaped groove, and the radial magnetic isolation groove is connected with the proximal end of the reverse √-shaped groove.

[0007] A single magnetic pole adopts a pole arc segmented variable permanent magnet design, and the pole arc coefficient of the permanent magnet corresponding to each pole arc is optimized. The pole arc coefficient a1 of the permanent magnet in the short side of the √-shaped slot is 0.21, the pole arc coefficient a2 of the permanent magnet in the V-shaped slot is 0.27, and the pole arc coefficient a3 of the permanent magnet in the long side of the √-shaped slot is 0.31. At this time, the air gap magnetic flux waveform distortion rate is 23.1%, and the 5th, 7th, and 11th harmonics are greatly reduced.

[0008] Compared with the prior art, the present invention has the following technical effects: (1) A double-layer permanent magnet structure is adopted, including an outer symmetrical V-shaped permanent magnet structure, an inner asymmetrical √-shaped permanent magnet structure, and an inverted √-shaped permanent magnet structure, so that the magnetic pole magnetic field is adjustable and the magnetic field distribution is more uniform; (2) Compared with the traditional symmetrical rotor structure, this structure divides each magnetic pole arc into three sections, and the magnetic field of each section of the pole arc is provided by different permanent magnets. Under the premise of ensuring that the motor has sufficient torque density, the harmonic content of the air gap magnetic density is minimized, reducing torque pulsation and motor loss; (3) Adjacent magnetic pole permanent magnets are separated by radial magnetic barriers, which reduces the rotor mass, reduces the magnetic leakage between adjacent magnetic poles, and improves the power density; (4) With the same volume and permanent magnet dosage, the total mass is smaller, the output torque is larger, and it has better electromagnetic performance.

[0009] Figure 1 It is a schematic diagram of the rotor structure of the present invention.

[0010] Figure 2 It is a comparison diagram of the magnetic flux waveforms of the permanent magnet motor with segmented pole arc variable permanent magnets of the present invention and the traditional U-shaped permanent magnet motor.

[0011] In the figure: 1. rotating shaft; 2. rotor core; 3. √-shaped groove; 4. reverse √-shaped groove; 5. V-shaped groove. DETAILED DESCRIPTION

[0012] A permanent magnet motor with a pole arc segmented permanent magnet for electric vehicles comprises a front cover, a housing, a stator, a rear cover, a rotating shaft 1, a rotor core 2, a √-shaped groove 3, an inverse √-shaped groove 4, a V-shaped groove 5, and a permanent magnet, and is characterized in that: The rotor core 2 has four √-shaped slots 3 evenly distributed along the circumferential direction, the included angle of the √-shaped slots 3 is greater than 90°, the long side of the √-shaped slots 3 is perpendicular to the center line of the magnetic pole where the √-shaped slots 3 are located, and the proximal ends of the √-shaped slots 3 are connected; An inverted √-shaped groove 4 is provided between adjacent √-shaped grooves 3, the included angle of the inverted √-shaped groove 4 is greater than 90°, the long side of the inverted √-shaped groove 4 is perpendicular to the center line of the magnetic pole where the inverted √-shaped groove 4 is located, and the proximal ends of the inverted √-shaped grooves 4 are connected; A V-shaped groove 5 is provided in the middle of the outer sides of the √-shaped groove 3 and the reverse √-shaped groove 4. The two sides of the V-shaped groove 5 are symmetrical about the center line of the magnetic pole, and the proximal ends of the V-shaped groove 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. The √-shaped groove 3 and the reverse √-shaped groove 4 are symmetrical 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; A permanent magnet is placed on the short side of the √-shaped groove 3, a permanent magnet is placed on the short side of the inverted √-shaped groove 4, a permanent magnet is placed on the outer end of the long side of the √-shaped groove 3, a permanent magnet is placed on the outer end of the long side of the inverted √-shaped groove 4, and a permanent magnet is placed in the V-shaped groove 5.

[0013] 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, and 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 inverse √-shaped groove 4 is equal to the length of the long side of the inverse √-shaped groove 4; There is a 1.5mm non-connected distance between the outer end of the short side of the √-shaped slot 3 and the outer circle of the rotor core 2; there is a 1.5mm non-connected distance between the outer end of the short side of the reverse √-shaped slot 4 and the outer circle of the rotor core 2; There is a 1.5mm disconnected distance between the outer end of the radial magnetic isolation slot 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, and there is a non-connected distance of 1.5 mm between the proximal ends of the V-shaped grooves 5.

[0014] √ The angle of the groove is greater than 90°, and the center line of the magnetic pole passes through the first magnetic isolation groove and the second magnetic isolation groove; 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.

[0015] A single magnetic pole adopts a pole arc segmented variable permanent magnet design, and the pole arc coefficient of the permanent magnet corresponding to each pole arc is optimized. The pole arc coefficient a1 of the permanent magnet in the short side of the √-shaped slot 3 is 0.21, the pole arc coefficient a2 of the permanent magnet in the V-shaped slot 5 is 0.27, and the pole arc coefficient a3 of the permanent magnet in the long side of the √-shaped slot 3 is 0.31. At this time, the air gap magnetic flux waveform distortion rate is 23.1%, and the 5th, 7th, and 11th harmonics are greatly reduced.

Claims

1. A permanent magnet motor with a pole arc segmented permanent magnet for electric vehicles, comprising a front cover, a housing, a stator, a rear cover, a rotating shaft (1), a rotor core (2), a √-shaped groove (3), an inverse √-shaped groove (4), a V-shaped groove (5), and a permanent magnet, characterized in that: The rotor core (2) has four √-shaped slots (3) evenly distributed along the circumferential direction, the long sides of the √-shaped slots (3) are perpendicular to the center lines of the magnetic poles where the √-shaped slots (3) are located, and the proximal ends of the √-shaped slots (3) are connected; An inverted √-shaped groove (4) is provided between adjacent √-shaped grooves (3), the long side of the inverted √-shaped groove (4) is perpendicular to the center line of the magnetic pole where the inverted √-shaped groove (4) is located, and the proximal ends of the inverted √-shaped grooves (4) are connected; A V-shaped groove (5) is provided in the middle of the outer sides of the √-shaped groove (3) and the reverse √-shaped groove (4), and the proximal ends of the V-shaped groove (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 inverted √-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 inverted √-shaped groove (4) are symmetrical 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; A permanent magnet is placed on the short side of the √-shaped groove (3), a permanent magnet is placed on the short side of the inverted √-shaped groove (4), a permanent magnet is placed on the outer end of the long side of the √-shaped groove (3), a permanent magnet is placed on the outer end of the long side of the inverted √-shaped groove (4), and a permanent magnet is placed inside the V-shaped groove (5).

2. The permanent magnet motor with arc segmented permanent magnet for electric vehicles 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 slot (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 slot (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 groove (3) is greater than 90°.

3. The permanent magnet motor with arc segmented permanent magnet for electric vehicles according to claim 1, characterized in that: The radial magnetic isolation groove is in communication with the proximal end of the √-shaped groove (3), and the radial magnetic isolation groove is in communication with the proximal end of the reverse √-shaped groove (4).

4. The permanent magnet motor with segmented pole arc permanent magnets for electric vehicles according to claim 1, characterized in that: The pole arc of each magnetic pole is divided into three sections, and the magnetic field of each section of the pole arc is provided by a different permanent magnet. The first section of the pole arc magnetic field in the magnetic pole where the √-shaped groove (3) is located is provided by the permanent magnet on the short side of the √-shaped groove (3), the second section of the pole arc magnetic field 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 third section of the pole arc magnetic field 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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