Rotor structure of a permanent magnet motor

Abstract

Rotor structure of a permanent magnet motor, comprising: a stator located on the outside, having a ring-shaped structure and wound with coils wired in a specific way; a rotor having a cylindrical structure with an imperfect circular shape, wherein there is an air gap between the stator and the rotor and the distance of which is not specified, wherein the rotor has several V-shaped recesses in which a magnet is arranged, wherein the magnet arranged in each V-shaped recess is fixed by the limit of the stop block arranged in that recess, wherein magnetic field guide recesses are provided on the outer edge contour of the rotor, each V-shaped recess corresponds to the magnetic field guide recesses and the magnetic field guide recesses are arranged symmetrically on two sides of that V-shaped recess; wherein a respective V-shaped depression serves as a dividing line and divides the rotor into two areas, the inside of the V-shaped angle being referred to as the upper V-area and the outside of the V-shaped angle being referred to as the lower V-area, wherein a first rectangular hole is provided on the center line of the upper V-area of ​​a respective V-shaped depression, a second rectangular hole is provided on the center line between any two V-shaped depressions and a round hole is provided on the center line of the lower V-area of ​​a respective V-shaped depression.

Description

Field of the invention

[0001] The present invention relates to a rotor structure of a permanent magnet motor that enables many features to be achieved by utilizing the magnetic field guide grooves of a rotor, such as low cogging torque, maximum torque corresponding to high speed torque, and weight reduction. The present invention is particularly advantageous for application in electric motors for electric motorcycles that require wide speed control. State of the art

[0002] Cogging torque is the torque generated in a permanent magnet motor between the rotor magnets and the stator tooth slots. This torque occurs when no current flows through the stator and varies periodically with changes in the rotor position. Simply put, cogging torque is the magnetic resistance created by the distribution of the magnetic field in the motor. This torque affects the smoothness of the motor and is particularly noticeable at low speeds, which can lead to vibration and noise during operation.

[0003] It will be Fig. 1 (TWI617115B) and Fig. 2 (TW202318756A). Conventional techniques involve reducing the cogging torque through the auxiliary holes on both sides and the center hole. Although the auxiliary holes on both sides suppress magnetic flux leakage to some extent, two leakage flux paths still form in the guide area. Combined with the influence of the center hole blocking the main magnetic flux path, conventional techniques excessively sacrifice average torque in exchange for low cogging torque.

[0004] Conventional techniques involve reducing cogging torque through various measures such as rounding the pole pieces, rounding the rotor, providing helical grooves in the rotor, and providing guide holes in the rotor, etc. However, these measures result in a 5% to 10% decrease in the average torque of the motor. The above-mentioned cogging torque reduction measures, such as rounding the pole pieces, rounding the rotor, providing helical grooves in the rotor, and providing guide holes in the rotor, are not particularly effective for reducing motor weight.

[0005] In addition, the Fig. 1 (TWI617115B) and Fig. 2 (TW202318756A) and the center hole are affected by centrifugal force during high-speed operation. The width of a leakage flux path in the guide area must be controlled to maintain a certain size, which limits the orifice size and further restricts the design. This is not ideal and therefore requires improvement.

[0006] For the reasons mentioned above, there is still room for improvement in conventional technology. With this in mind, the inventor, drawing on his many years of professional experience, has dedicated himself to solving the problem and, after numerous modifications, experiments, and improvements, has finally produced the present invention. Object of the invention

[0007] The main objective of the present invention is to provide a rotor structure of a permanent magnet motor that can achieve low cogging torque, maximum torque corresponding to high speed torque, and weight reduction by utilizing the magnetic field guide grooves of a rotor. The present invention is particularly advantageous for application in electric motors for electric motorcycles that require wide speed control.

[0008] It is a further object of the present invention to provide a rotor structure of a permanent magnet motor in which the present invention comprises magnetic field guide grooves. Due to the geometric properties of the guide grooves, the leakage flux path in the guide region is reduced to a single path, and there is no center hole. Compared to conventional techniques, which excessively sacrifice average torque in exchange for lower cogging torque, the present invention offers greater advantages.

[0009] It is still another object of the present invention to provide a rotor structure of a permanent magnet motor such that, due to the geometric characteristics of the magnetic field guide grooves in the present invention, only the width of a single leakage flux path in the guide area needs to be controlled, thus providing more space for design.

[0010] To achieve the above-mentioned objects, the present invention provides a rotor structure of a permanent magnet motor comprising a stator and a rotor, the stator being located on the outside and wound with coils wired in a specific manner, an air gap being provided between the stator and the rotor, and the distance thereof being not fixed. Due to the imperfect circular shape of the rotor, the magnetic resistance is gradually increased or decreased, thereby reducing the cogging torque. The rotor has a plurality of V-shaped recesses, each of which houses two magnets. By means of the stopper block arranged in each V-shaped recess, the magnets arranged in this recess can be fixed by the limitation of this stopper block.A plurality of magnetic field guide recesses are provided on the outer edge contour of the rotor, wherein each V-shaped recess corresponds to two magnetic field guide recesses and the two magnetic field guide recesses are arranged symmetrically on two sides of this V-shaped recess.

[0011] A respective V-shaped recess serves as a dividing line and divides the rotor into two regions, the inside of the V-shaped angle being referred to as the upper V-region and the outside of the V-shaped angle being referred to as the lower V-region, a first rectangular hole being provided on the center line of the upper V-region of a respective V-shaped recess and serving both for connection by riveting and for suppressing leakage flux, a second rectangular hole being provided on the center line between each two V-shaped recesses and serving both for connection by riveting and for guiding the magnetic field, a round hole being provided on the center line of the lower V-region of a respective V-shaped recess and serving both for suppressing leakage flux and for weight reduction.

[0012] To better understand the features and technical content of the present invention, the drawings of the present invention are described in detail below. However, the accompanying drawings are for reference and illustration purposes only and are not intended to limit the present invention in any way. Brief description of the drawings Fig. 1 shows a plan view of the use state of the rotor structure of patent TWI617115B (prior art); Fig. Fig. 2 shows a plan view of the use state of the rotor structure of patent TW202318756A (prior art); Fig. 3 shows a plan view of the rotor structure of a permanent magnet motor according to the invention; Fig. 4 shows a plan view of the use state of the rotor structure of a permanent magnet motor according to the invention; Fig. 5 shows an enlarged partial view according to Fig. 4; Fig. 6 shows a data line diagram of the operating points of the rotor structure of a permanent magnet motor according to the invention; Fig. 7 shows a data line diagram of the cogging torque of the rotor structure of a permanent magnet motor according to the invention. Detailed description of the embodiment

[0013] It is based on the Fig. 3 to 5. The present invention relates to a rotor structure of a permanent magnet motor, comprising a stator 10 and a rotor 20, wherein the stator is located on the outside and is wound with coils wired in a specific way, wherein an air gap 15 exists between the stator 10 and the rotor 20 and the distance of which is not fixed. Due to the imperfect circular shape of the rotor 20, the magnetic resistance is gradually increased or decreased, thereby reducing the cogging torque. The rotor 20 has a plurality of V-shaped recesses 22, in each of which two magnets 24 are arranged. By means of the stop block 34 arranged in each V-shaped recess 22, the magnets 24 arranged in this recess 22 can be fixed by the limitation of this stop block 34.A plurality of magnetic field guide recesses 26 are provided on the outer edge contour of the rotor 20, wherein each V-shaped recess 22 corresponds to two magnetic field guide recesses 26, and the two magnetic field guide recesses 26 are arranged symmetrically on two sides of this V-shaped recess 22. Each V-shaped recess 22 serves as a dividing line and divides the rotor 20 into two regions, wherein the inside of the V-shaped angle is referred to as the upper V-region and the outside of the V-shaped angle is referred to as the lower V-region. A first rectangular hole 28 is located on the center line of the upper V-region of each V-shaped recess 22 and serves both for connection by riveting and for suppressing leakage flux. A second rectangular hole 30 is located on the center line between each two V-shaped recesses 22 and serves both for connection by riveting and for guiding the magnetic field.A round hole 32 is located on the center line of the lower V-region of a respective V-shaped recess 22 and serves both to suppress stray flux and to reduce weight.

[0014] In the rotor structure of a permanent magnet motor according to the invention, the magnetic field guide grooves 26 of the rotor 20 are used to achieve the goals of low cogging torque, maximum torque corresponding to the high speed torque, and weight reduction. The present invention is particularly advantageous for application in electric motors for electric motorcycles, which require wide speed control.

[0015] The rotor structure of a permanent magnet motor according to the invention comprises magnetic field guide grooves 26. Due to the geometric properties of the guide grooves 26, the leakage flux path in the guide area is reduced to a single path, and there is no center hole. Compared to conventional techniques, which excessively sacrifice average torque in exchange for lower cogging torque, the present invention offers greater advantages.

[0016] Due to the geometric properties of the magnetic field guide recesses 26, in the rotor structure of a permanent magnet motor according to the invention, only the width of a single leakage flux path in the guide area needs to be controlled, so that more space is available for design.

[0017] A first rectangular hole 28 is provided above the centerline of each V-shaped recess 22, and a second rectangular hole 30 is provided between each two V-shaped recesses 22. These holes serve to suppress magnetic flux leakage from the lower magnets. When the product is designed for high-priced or high-performance applications, hot-rolled self-adhesive silicon steel sheets are used to manufacture the iron core to increase product performance. In this case, the first rectangular holes 28 and the second rectangular holes 30 serve to suppress magnetic flux leakage and reduce the weight of the rotor.

[0018] If the product is designed for low-cost or ordinary applications, ordinary silicon steel sheets riveted together are used to manufacture the iron core. In this case, the first rectangular holes 28 and the second rectangular holes 30 for riveting the silicon steel sheets serve as connection points and simultaneously contribute to a certain extent to reducing magnetic flux leakage.

[0019] The minimum distance between each first rectangular hole 28 and the corresponding V-shaped recess 22 depends on the maximum speed of the motor. Typically, the minimum distance is 1 times the thickness of the silicon steel sheet.

[0020] A round hole 32 is provided below the center line of each V-shaped recess 22, the purpose of which, in addition to suppressing the magnetic flux leakage of the lower magnets and reducing weight, is also to effectively block the magnetic flux leakage to the shaft, thereby reducing the risk of interference with the position sensor located at the shaft end and thus avoiding deterioration of the motor performance.

[0021] It is based on the Fig. 6 and Fig. 7, which show a data line diagram of the operating points and a data line diagram of the cogging torque. In Fig. 6 shows that the average torque at the low speed operating point decreases slightly (↓1.2%) after adding the magnetic field guide grooves, while the average torque at the high speed operating point increases slightly (↑1.0%) after adding the magnetic field guide grooves. Fig. Figure 7 shows that the peak cogging torque drops significantly by 54% after adding the magnetic field guide grooves. A significant improvement in cogging performance is achieved at a comparable torque (approximately ±1%).

[0022] A rotor structure of a permanent magnet motor thus comprises a stator and a rotor, with the stator located on the outside and wound with coils wired in a specific way, with an air gap between the stator and the rotor, the distance between which is not fixed. Due to the imperfect circular shape of the rotor, the magnetic resistance is gradually increased or decreased, thereby reducing the cogging torque. The rotor has several V-shaped recesses, each of which contains two magnets. The stop block arranged in each V-shaped recess allows the magnets arranged in this recess to be fixed by the limit of this stop block.A plurality of magnetic field guide grooves are provided on the outer edge contour of the rotor, wherein each V-shaped groove corresponds to two magnetic field guide grooves, and the two magnetic field guide grooves are arranged symmetrically on two sides of this V-shaped groove. Each V-shaped groove serves as a dividing line and divides the rotor into two regions, wherein the inside of the V-shaped angle is referred to as the upper V-region and the outside of the V-shaped angle is referred to as the lower V-region. A first rectangular hole is provided on the center line of the upper V-region of each V-shaped groove, a second rectangular hole is provided on the center line between each two V-shaped grooves, and a round hole is provided on the center line of the lower V-region of each V-shaped groove.

[0023] Although the present invention has been described above with reference to a preferred embodiment, it is not limited thereto. All equivalent changes and modifications that can be made by one skilled in the art in accordance with the description and drawings of the invention are within the scope of the present invention. The scope of the invention is defined by the appended claims. List of reference symbols 10 Stator 15 Air gap 20 rotors 22 V-shaped recess 24 Magnet 26 Magnetic field guide recess 28 first rectangular hole 30 second rectangular hole 32 round hole 34 stop block QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] TW 202318756A [0003, 0005, 0012]

Claims

[1] Rotor structure of a permanent magnet motor, comprising: a stator located on the outside, having a ring-shaped structure and wound with coils wired in a specific way; a rotor having a cylindrical structure with an imperfect circular shape, wherein an air gap exists between the stator and the rotor and the distance between which is not fixed, wherein the rotor has a plurality of V-shaped recesses, in each of which a magnet is arranged, wherein the stop block arranged in a respective V-shaped recess fixes the magnet arranged in this recess by the limitation of this stop block, wherein magnetic field guide recesses are provided on the outer edge contour of the rotor, a respective V-shaped recess corresponds to the magnetic field guide recesses and the magnetic field guide recesses are arranged symmetrically on two sides of this V-shaped recess; wherein a respective V-shaped recess serves as a dividing line and divides the rotor into two regions, the inside of the V-shaped angle is referred to as the upper V-region and the outside of the V-shaped angle is referred to as the lower V-region, wherein a first rectangular hole is provided on the center line of the upper V-region of a respective V-shaped recess, a second rectangular hole is provided on the center line between each two V-shaped recesses and a round hole is provided on the center line of the lower V-region of a respective V-shaped recess. [2] A rotor structure of a permanent magnet motor according to claim 1, wherein two magnets are arranged in a respective V-shaped recess. [3] A rotor structure of a permanent magnet motor according to claim 1, wherein a plurality of magnetic field guide grooves are provided on the outer peripheral contour of the rotor, wherein a respective V-shaped groove corresponds to two magnetic field guide grooves. [4] A rotor structure of a permanent magnet motor according to claim 1, wherein a round hole is provided below the center line of each V-shaped recess, the purpose of which, in addition to suppressing the magnetic flux leakage of the lower magnets and reducing weight, is also to effectively block the magnetic flux leakage to the shaft.

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