Design method of asymmetric magnetic pole built-in permanent magnet motor rotor and permanent magnet motor

Abstract

The invention provides a design method of an asymmetric magnetic pole built-in permanent magnet motor rotor and a permanent magnet motor, each magnetic pole unit of the rotor is internally provided with two permanent magnets, the two permanent magnets comprise a first permanent magnet and a second permanent magnet, and the size of the first permanent magnet is larger than that of the second permanent magnet. The design method of the asymmetric magnetic pole built-in permanent magnet motor rotor is used for establishing a mapping rule between a preset magnetic pole offset electrical angle theta e and the sizes of two permanent magnets. Wherein the magnetic pole offset electrical angle theta e is defined as an electrical angle between an equivalent magnetic field center line of a single magnetic pole unit and a geometric center line of the magnetic pole unit. According to the invention, the problem of low design efficiency of an asymmetric rotor of a built-in permanent magnet motor in the prior art is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of permanent magnet motors, in particular to a design method of an asymmetric-pole built-in permanent magnet motor rotor and a permanent magnet motor. BACKGROUND

[0002] Built-in permanent magnet motors (IPM) have an important position in industrial applications and electrical drive fields due to their high efficiency, wide speed regulation range, and the use of reluctance torque to improve torque density. However, traditional IPM designs usually adopt symmetric rotor structures and do not include magnetic barrier structures in the rotor design. Although this design is mature in process and simple in structure, it has certain limitations in the performance of IPM.

[0003] The limitations are specifically manifested in that the arrangement of the magnetic poles (permanent magnets) in the current IPM is usually symmetrical to simplify the design and manufacturing process. However, the peak values of the permanent magnet torque (Tpm) generated by the permanent magnets and the reluctance torque (Tr) generated by the change in reluctance appear at different current angle phases, and the phase difference between them is usually 90° or less, but will not be less than 45°. The existence of this current angle phase difference makes it impossible to maximize the permanent magnet torque and the reluctance torque at the same current angle phase, which limits the total torque of the IPM and reduces the efficiency and torque density of the IPM.

[0004] To achieve a higher performance IPM, the arrangement of the magnetic poles on the rotor can be adjusted to be asymmetric. However, how to quantify the change in the arrangement of the magnetic poles so that it can be systematized and applied to IPMs of different types and specifications is a challenge. Traditional design methods often rely on experience or a large number of trial-and-error processes, which not only consumes time and costs a lot, but also makes it difficult to ensure that each design can reach the optimal state.

[0005] That is, the existing IPM has the problem of low design efficiency of asymmetric rotors. SUMMARY

[0006] The main purpose of the present application is to provide a design method of an asymmetric-pole built-in permanent magnet motor rotor and a permanent magnet motor to solve the problem of low design efficiency of asymmetric rotors in the existing IPM.

[0007] According to one aspect of the present application, a design method of an asymmetric-pole built-in permanent magnet motor rotor is provided, each magnetic pole unit of the rotor is provided with two permanent magnets, the two permanent magnets include a first permanent magnet and a second permanent magnet, the size of the first permanent magnet is larger than the size of the second permanent magnet, and the design method is used to establish a preset magnetic pole offset electrical angle θ ea mapping rule between the size of the two permanent magnets and the size of the magnetic pole offset electric angle θ e defined as: the electric angle between the equivalent magnetic field center line of a single magnetic pole unit and the geometric center line of the magnetic pole unit;

[0008] The above design method comprises the steps of:

[0009] Step 1: input the preset magnetic pole offset electric angle θ e ;

[0010] Step 2: according to the preset magnetic pole offset electric angle θ e , determine the first segment central angle θ1, the second segment central angle θ2 and the third segment central angle θ3 of the air gap on the outer circle corresponding to the single magnetic pole unit of the rotor, wherein θ2=θ3;

[0011] Step 3: based on the first segment central angle θ1, the second segment central angle θ2 and the third segment central angle θ3, determine the width of the two permanent magnets in the circumferential direction of the rotor, the width of the first permanent magnet is W m1 , and the width of the second permanent magnet is W m2 ;

[0012] Step 4: based on the first segment central angle θ1, the second segment central angle θ2 and the third segment central angle θ3, and according to the relationship that the magnetomotive force of the permanent magnet is balanced with the magnetic pressure drop of the air gap, determine the thickness T m of the permanent magnet; wherein the mapping rule for performing steps 2 to 4 is to make the size of the two permanent magnets calculated according to the preset magnetic pole offset electric angle θ e and the magnetic barrier arranged according to the size of the two permanent magnets physically realize the magnetic pole offset electric angle θ e .

[0013] Further, in step 2, the magnetic pole offset electric angle θ e and the third segment central angle θ3 satisfy the relationship:

[0014]

[0015] wherein p represents the number of magnetic pole pairs of the rotor.

[0016] Further, in step 3, in the circumferential direction of the rotor, the ratio of the width W m1 of the first permanent magnet to the width W m2 of the second permanent magnet is determined according to the first segment central angle θ1 and the second segment central angle θ2, according to the principle of making the air gap magnetic flux density sinusoidal distribution along the outer circle of the rotor.

[0017] Further, the width W m1 of the first permanent magnet and the width W m2The ratio of the first air gap magnetic flux density B

[0018]

[0019] Further, the above design method further comprises: based on the first segment circle central angle θ1, the second segment circle central angle θ2, the third segment circle central angle θ3 and the corresponding first air gap magnetic flux density B g1 , the second air gap magnetic flux density B g2 , the third air gap magnetic flux density B g3 , determine the target air gap average magnetic flux density B av .

[0020] Further, the target air gap average magnetic flux density B av is determined by the following formula:

[0021]

[0022] Wherein, the first segment circle central angle θ1 corresponds to the first air gap area A g1 , the second segment circle central angle θ2 corresponds to the second air gap area A g2 , the third segment circle central angle θ3 corresponds to the third air gap area A g3 , B m is the working magnetic flux density of the permanent magnet, kl is the leakage magnetic coefficient, τ p is the pole pitch.

[0023] Further, in step 4, the thickness T m of the permanent magnet satisfies the following relationship:

[0024]

[0025] Wherein, B g is the air gap working magnetic flux density, μ M is the magnetic permeability of the permanent magnet, kr is the magnetic resistance coefficient, g is the air gap width, B r is the residual magnetism of the permanent magnet, μ0 is the vacuum magnetic permeability.

[0026]

[0027] Further, the above design method further comprises the following steps:

[0028] Step 5: according to the width W m1 of the first permanent magnet, the width W m2 of the second permanent magnet, the thickness T mThe first segment central angle θ1, the second segment central angle θ2, and the third segment central angle θ3 are used to determine the positions of the first permanent magnet slot, the second permanent magnet slot, the pole cap magnetic barrier slot located between the first permanent magnet slot and the second permanent magnet slot, and the permanent magnet outer magnetic barrier slot located on the side away from the pole cap magnetic barrier slot outside the second permanent magnet slot, and the arrangement of the first permanent magnet slot and the second permanent magnet slot is offset towards the side away from the permanent magnet outer magnetic barrier slot.

[0029] According to another aspect of the present invention, a permanent magnet motor is provided, wherein the rotor of the permanent magnet motor is designed and manufactured using the above-described design method.

[0030] Applying the technical solution of this invention, each pole unit of the asymmetric pole-embedded permanent magnet motor rotor is provided with two permanent magnets, including a first permanent magnet and a second permanent magnet, wherein the size of the first permanent magnet is larger than the size of the second permanent magnet. The design method for the asymmetric pole-embedded permanent magnet motor rotor is used to establish a preset pole offset electrical angle θ. e The mapping rule between the dimensions of the two permanent magnets; where the electric angle θ of the magnetic pole offset e Defined as: the electrical angle between the center line of the equivalent magnetic field of a single magnetic pole unit and the geometric center line of the magnetic pole unit;

[0031] The above design method includes the following steps:

[0032] Step 1: Input the preset magnetic pole offset electrical angle θ e ;

[0033] Step 2: Based on the electric angle θ of the magnetic pole offset e Determine the first segment central angle θ1, the second segment central angle θ2, and the third segment central angle θ3 of the air gap on the outer circle corresponding to a single magnetic pole unit of the rotor, where θ2 = θ3;

[0034] Step 3: Based on the first segment central angle θ1, the second segment central angle θ2, and the third segment central angle θ3, determine the width of the two permanent magnets in the circumferential direction of the rotor. The width of the first permanent magnet is W. m1 The width of the second permanent magnet is W m2 ;

[0035] Step 4: Based on the first segment central angle θ1, the second segment central angle θ2, and the third segment central angle θ3, and according to the phase balance relationship between the magnetomotive force of the permanent magnet and the magnetic pressure drop of the air gap, determine the thickness T of the permanent magnet. m Among them, the mapping rules based on steps 2 to 4 are executed so that the magnetic pole offset electrical angle θ is determined. e The calculated dimensions of the two permanent magnets, along with the magnetic barriers arranged according to those dimensions, can physically achieve an electrical angle θ between the magnetic poles. e.

[0036] By introducing the electric angle θ of magnetic pole offset e The preset electric angle θ of magnetic pole offset was effectively established. e The mapping rule between the dimensions of two permanent magnets, one large and one small. First, input the specific preset magnetic pole offset electric angle θ. e Then, according to the preset magnetic pole offset electric angle θ e The first segmented central angle θ1, the second segmented central angle θ2, and the third segmented central angle θ3 of the air gap on the outer circumference corresponding to a single magnetic pole unit of the rotor are determined. When the second segmented central angle θ2 equals the third segmented central angle θ3, the distribution of air gap magnetic flux density is more uniform, which helps reduce harmonic content, decreases noise and vibration of the built-in permanent magnet motor, improves the overall performance of the built-in permanent magnet motor, and achieves optimized configuration of air gap magnetic flux density. Subsequently, based on the above segmented central angles, the width of the two permanent magnets in the rotor circumferential direction can be accurately calculated. Then, through the balance principle of magnetomotive force and magnetic pressure drop, the thickness T of the permanent magnets is determined. m The above mapping rules ensure that the calculated dimensions of the two permanent magnets, one large and one small, and the corresponding arrangement of the magnetic barriers can achieve the preset magnetic pole offset angle θ at the physical level. e This reduces the phase difference between the peak values ​​of the permanent magnet torque and the reluctance torque. The design method described in this application can quickly design magnetic pole offset angles θ with preset values. e The asymmetric pole embedded permanent magnet motor rotor is suitable for embedded permanent magnet motors with arbitrary pole-slot ratios. The above design method significantly reduces the design cost of embedded permanent magnet motors, while making more effective use of reluctance torque and improving the torque density and operating efficiency of embedded permanent magnet motors.

[0037] Furthermore, in order to achieve the preset magnetic pole offset electrical angle θ e In this case, the size of the two permanent magnets, one large and one small, and the arrangement of the corresponding magnetic barriers are more reasonable in terms of physical layout. This can optimize the distribution of magnetic flux in the air gap and the back electromotive force waveform of the built-in permanent magnet motor, making it closer to the ideal sine waveform. This effectively reduces torque fluctuations and improves the smoothness and low-frequency performance of the built-in permanent magnet motor, thereby ensuring the efficiency of the built-in permanent magnet motor. Attached Figure Description

[0038] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0039] Figure 1 A flowchart illustrating a design method for an asymmetric pole-embedded permanent magnet motor rotor according to an optional embodiment of the present invention is shown.

[0040] Figure 2 A parameter diagram of a single magnetic pole unit on the rotor of an asymmetric magnetic pole built-in permanent magnet motor according to an optional embodiment of the present invention is shown.

[0041] Figure 3 A schematic diagram of the air gap magnetic flux density of an asymmetric pole-embedded permanent magnet motor rotor according to an optional embodiment of the present invention is shown.

[0042] Figure 4 A schematic diagram of the built-in permanent magnet motor according to Embodiment 1 of the present invention is shown;

[0043] Figure 5 It shows Figure 4 A schematic diagram of the structure of a single magnetic pole unit of a built-in permanent magnet motor;

[0044] Figure 6 A schematic diagram of a single magnetic pole unit of a built-in permanent magnet motor is shown in Comparative Example 1.

[0045] The above figures include the following reference numerals:

[0046] 10. Rotating shaft; 30. Magnetic pole unit; 31. First permanent magnet slot; 32. Pole cap magnetic barrier slot; 33. Second permanent magnet slot; 34. Magnetic barrier slot on the outer side of permanent magnet; 50. Rib bridge; 51. Auxiliary hole; 61. First permanent magnet; 62. Second permanent magnet; 70. Stator; 71. Armature coil. Detailed Implementation

[0047] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0048] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0049] In this invention, unless otherwise stated, directional terms such as "upper," "lower," "top," and "bottom" are generally used in relation to the direction shown in the accompanying drawings, or in relation to the vertical, perpendicular, or gravitational direction of the component itself; similarly, for ease of understanding and description, "inner" and "outer" refer to the inner and outer contours of each component itself, but the above directional terms are not intended to limit this invention.

[0050] To address the problem of low design efficiency in existing built-in permanent magnet motors due to asymmetrical rotors, this invention provides a design method for an asymmetrical magnetic pole built-in permanent magnet motor rotor and a permanent magnet motor.

[0051] like Figures 1 to 5As shown, each pole unit 30 of the asymmetric pole-embedded permanent magnet motor rotor contains two permanent magnets, including a first permanent magnet 61 and a second permanent magnet 62. The size of the first permanent magnet 61 is larger than that of the second permanent magnet 62. The design method of the asymmetric pole-embedded permanent magnet motor rotor is used to establish a preset pole offset electrical angle θ. e The mapping rule between the dimensions of the two permanent magnets; where the electric angle θ of the magnetic pole offset e Defined as: the electrical angle between the center line of the equivalent magnetic field of a single magnetic pole unit 30 and the geometric center line of the magnetic pole unit 30;

[0052] The above design method includes the following steps:

[0053] Step 1: Input the preset magnetic pole offset electrical angle θ e ;

[0054] Step 2: According to the preset magnetic pole offset electric angle θ e Determine the first segment central angle θ1, the second segment central angle θ2, and the third segment central angle θ3 of the air gap on the outer circle corresponding to a single magnetic pole unit 30 of the rotor, where θ2 = θ3;

[0055] Step 3: Based on the first segment central angle θ1, the second segment central angle θ2, and the third segment central angle θ3, determine the width of the two permanent magnets in the circumferential direction of the rotor. The width of the first permanent magnet 61 is W. m1 The width of the second permanent magnet 62 is W. m2 ;

[0056] Step 4: Based on the first segment central angle θ1, the second segment central angle θ2, and the third segment central angle θ3, and according to the phase balance relationship between the magnetomotive force of the permanent magnet and the magnetic pressure drop of the air gap, determine the thickness T of the two permanent magnets. m ;

[0057] Among them, the mapping rules based on steps 2 to 4 are executed so that the magnetic pole offset electrical angle θ is preset. e The calculated dimensions of the two permanent magnets, and the magnetic barriers arranged according to these dimensions, physically achieve an electrical angle θ for the magnetic poles to deflect. e .

[0058] By introducing the electric angle θ of magnetic pole offset e The preset electric angle θ of magnetic pole offset was effectively established. e The mapping rule between the dimensions of two permanent magnets, one large and one small. First, input the specific preset magnetic pole offset electric angle θ. e Then, according to the preset magnetic pole offset electric angle θ eThe first segmented central angle θ1, the second segmented central angle θ2, and the third segmented central angle θ3 of the air gap on the outer circumference corresponding to a single magnetic pole unit 30 of the rotor are determined. When the second segmented central angle θ2 equals the third segmented central angle θ3, the distribution of air gap magnetic flux density is more uniform, which helps to reduce harmonic content, decrease noise and vibration of the built-in permanent magnet motor, improve the overall performance of the built-in permanent magnet motor, and achieve optimized configuration of air gap magnetic flux density. Subsequently, based on the above segmented central angles, the width of the two permanent magnets in the rotor circumferential direction can be accurately calculated. Then, through the balance principle of magnetomotive force and magnetic pressure drop, the thickness T of the permanent magnets is determined. m The above mapping rules ensure that the calculated dimensions of the two permanent magnets, one large and one small, and the corresponding arrangement of the magnetic barriers can achieve the preset magnetic pole offset angle θ at the physical level. e This reduces the phase difference between the peak values ​​of the permanent magnet torque and the reluctance torque. The design method described in this application can quickly design magnetic pole offset angles θ with preset values. e The asymmetric pole embedded permanent magnet motor rotor is suitable for embedded permanent magnet motors with arbitrary pole-slot ratios. The above design method significantly reduces the design cost of embedded permanent magnet motors, while making more effective use of reluctance torque and improving the torque density and operating efficiency of embedded permanent magnet motors.

[0059] Furthermore, in order to achieve the preset magnetic pole offset electrical angle θ e In this case, the size of the two permanent magnets, one large and one small, and the arrangement of the corresponding magnetic barriers are more reasonable in terms of physical layout. This can optimize the distribution of magnetic flux in the air gap and the back electromotive force waveform of the built-in permanent magnet motor, making it closer to the ideal sine waveform. This effectively reduces torque fluctuations and improves the smoothness and low-frequency performance of the built-in permanent magnet motor, thereby ensuring the efficiency of the built-in permanent magnet motor.

[0060] It should be noted that the above mapping rule refers to a quantitative mapping relationship, specifically a technical method used to solve the problem of low design efficiency of asymmetrical rotors in existing built-in permanent magnet motors.

[0061] It should be noted that the geometric center line of a single magnetic pole unit 30 refers to a straight line that is radially symmetrical about the single magnetic pole unit 30 along the rotor. The equivalent magnetic field center line of a single magnetic pole unit 30 is an equivalent straight line formed by the combined action of the permanent magnet and the magnetic barrier on the single magnetic pole unit 30.

[0062] In addition to steps 1 to 4 above, the design method also includes step 5. For example... Figure 1 As shown, in step 5, according to the width W of the first permanent magnet 61 m1 The width W of the second permanent magnet 62 m2 The thickness T of the permanent magnet mThe first segment central angle θ1, the second segment central angle θ2, and the third segment central angle θ3 are determined within a single magnetic pole unit 30 of the rotor. The positions of the first permanent magnet slot 31, the second permanent magnet slot 33, the pole cap magnetic barrier slot 32 located between the first permanent magnet slot 31 and the second permanent magnet slot 33, and the permanent magnet outer magnetic barrier slot 34 located outside the second permanent magnet slot 33 away from the pole cap magnetic barrier slot 32 are determined. The arrangement of the first permanent magnet slot 31 and the second permanent magnet slot 33 is biased toward the side away from the permanent magnet outer magnetic barrier slot 34.

[0063] The rotor of the asymmetric magnetic pole built-in permanent magnet motor of this application has multiple magnetic barriers. These magnetic barriers include at least a first permanent magnet slot 31, a second permanent magnet slot 33, a pole cap magnetic barrier slot 32, and a permanent magnet outer magnetic barrier slot 34 arranged sequentially. The arrangement of the first permanent magnet slot 31 and the second permanent magnet slot 33 is biased towards the side away from the permanent magnet outer magnetic barrier slot 34. This relative arrangement of the magnetic barriers can guide and compress the magnetic flux between the first permanent magnet 61 and the second permanent magnet 62 towards the vicinity of the first permanent magnet 61, and force the magnetic flux of the second permanent magnet 62 to flow towards the side away from the permanent magnet outer magnetic barrier slot 34, providing a physical basis for the asymmetric magnetic pole design method. After executing the mapping rules based on steps 2 to 4, according to the size W of the permanent magnet... m1 W m2 T m The first segment central angle θ1, the second segment central angle θ2, and the third segment central angle θ3 can ultimately determine the optimal position of the magnetic barrier, thereby optimizing the magnetic circuit distribution, improving the quality of the back EMF waveform of the built-in permanent magnet motor, and achieving stable magnetic pole offset.

[0064] It should be noted that, as Figure 2 As shown, the first permanent magnet 61 is embedded in the first permanent magnet slot 31, and the second permanent magnet 62 is embedded in the second permanent magnet slot 33. In the circumferential direction of the rotor, the width W of the first permanent magnet 61 is... m1 The distance between the first permanent magnet 61 and the center line of the first permanent magnet slot 31, and the width W of the second permanent magnet 62. m2 The distance between the second permanent magnet 62 and the center line of the second permanent magnet slot 33 is given. The center line of the first permanent magnet slot 31 is formed by connecting the midpoints of its two ends along the radial direction of the rotor, and the center line of the second permanent magnet slot 33 is formed by connecting the midpoints of its two ends along the radial direction of the rotor. The thickness T of the first permanent magnet 61 is given. m1 It is the distance of the first permanent magnet 61 on the center line of the groove perpendicular to the first permanent magnet groove 31, and the thickness T of the second permanent magnet 62. m2 It is the distance of the second permanent magnet 62 on the center line of the groove perpendicular to the second permanent magnet groove 33.

[0065] Optionally, a gap may be left at both ends of the first permanent magnet slot 31 and the second permanent magnet slot 33 in the radial direction of the rotor.

[0066] It should be noted that, as Figure 4 As shown, the rotor of the built-in permanent magnet motor has a rotating shaft 10 and a stator 70 disposed on the outer periphery of the rotor, with stator slots inside the stator 70. The aforementioned arbitrary pole-to-slot ratio refers to the ratio of the number of arbitrary pole pairs of the built-in permanent magnet motor to the number of stator slots.

[0067] In some alternative embodiments, in step 2, the magnetic poles are deflected by an electrical angle θ. e It satisfies the following relationship with the central angle θ3 of the third segment:

[0068]

[0069] Where p represents the number of pole pairs of the rotor.

[0070] Magnetic pole offset electric angle θ e As a design parameter of the rotor of an asymmetric pole-embedded permanent magnet motor, it directly affects the position of the permanent magnet and the magnetic barrier. This is achieved by offsetting the magnetic poles by an electrical angle θ. e The direct correlation with the number of pole pairs of the rotor allows the design method of this application to be applied to built-in permanent magnet motors with any pole-slot ratio, improving the versatility and efficiency of the above design method.

[0071] Preferably, the magnetic pole offset electrical angle θ e The range is between 0° and 45°. Magnetic pole offset electrical angle θ e By setting the angle between 0° and 45°, the interaction between the permanent magnet and the magnetic barrier can be balanced, effectively controlling the distribution of magnetic flux density in the air gap, enabling the built-in permanent magnet motor to achieve higher torque density and efficiency during operation.

[0072] In some alternative embodiments, in step 3, the width W of the first permanent magnet 61 m1 Width W of the second permanent magnet 62 m2 The ratio is determined by the first segment central angle θ1 and the second segment central angle θ2, based on the principle of making the air gap magnetic flux density sinusoidally distributed along the outer circle of the rotor.

[0073] To optimize the electromagnetic performance of the built-in permanent magnet motor, the above design method follows the following... Figure 3 The principle of sinusoidal distribution of air gap magnetic flux density along the outer circle of the rotor is shown. By reasonably adjusting the width ratio of the two permanent magnets, it is possible to ensure that the air gap magnetic flux density of the rotor of the asymmetrical pole built-in permanent magnet motor exhibits an ideal sinusoidal distribution during rotation, thereby improving the waveform quality of the back electromotive force, reducing torque ripple, and improving the efficiency and operational stability of the built-in permanent magnet motor.

[0074] It should be noted that the determination of the central angle θ1 of the first segment and the central angle θ2 of the second segment needs to be calculated through a mathematical model. Specifically, for example... Figure 2 As shown, on a single magnetic pole unit 30 of the rotor, the intersection of the centerline of the first permanent magnet slot 31 and the outer circle of the rotor is point A; the intersection of the centerline of the pole cap magnetic barrier slot 32 and the outer circle of the rotor is point B; the intersection of the centerline of the second permanent magnet slot 33 and the outer circle of the rotor is point C; the intersection of the centerline of the outer magnetic barrier slot 34 of the permanent magnet and the outer circle of the rotor is point D; and the intersection of the centerline of the first permanent magnet slot 31 and the centerline of the second permanent magnet slot 33 is point M. The rotor has a center O. Connecting the rotor's center O to point A, and connecting the rotor's center O to point B, creates a first segmented central angle θ1 between lines AO and BO; connecting the rotor's center O to point B, and connecting the rotor's center O to point C, creates a second segmented central angle θ2 between lines BO and CO; connecting the rotor's center O to point C, and connecting the rotor's center O to point D, creates a third segmented central angle θ3 between lines CO and DO. The designer provides the total central angle of a single magnetic pole unit 30 and a preset magnetic pole offset electrical angle θ. e Then, based on the electric angle θ of the magnetic pole offset e The expression can be used to calculate the specific value of the third segment central angle θ3. Under the condition that the second segment central angle θ2 is equal to the third segment central angle θ3, the specific value of the first segment central angle θ1 can also be calculated.

[0075] Taking the built-in permanent magnet motor of Embodiment 1 of this application as an example, such as Figure 4 As shown, the stator 70 of the built-in permanent magnet motor in Embodiment 1 has 54 stator slots, each stator slot housing an armature coil 71, and also has 12 pairs of magnetic poles (p=12), meaning the rotor has 24 magnetic pole units 30. The specifications of the built-in permanent magnet motor in Embodiment 1 are designated "54S12P", with a rated power of 11kW and a rated speed of 1500rpm. Embodiment 1 uses an asymmetric magnetic pole built-in permanent magnet motor rotor manufactured using the design method of this application. Figure 5 The image shows a magnetic pole unit 30 on the rotor of an asymmetric magnetic pole built-in permanent magnet motor.

[0076] In Example 1, the designer sets a preset magnetic pole offset electrical angle θ. e The angle is 11.25°. Based on the fact that the total central angle of a single magnetic pole unit 30 is 30°, the central angles θ1, θ2, and θ3 of the first segment can be calculated to be 15°, 7.5°, and 7.5°, respectively.

[0077] It should be noted that the electric angle θ of the magnetic pole deflection e It can also be expressed in electrical degrees as the central angle θ3 formed between the lines CO and DO, representing the third segment.

[0078] In some alternative embodiments, the width W of the first permanent magnet 61 is [missing information] in the circumferential direction of the rotor. m1 Width W of the second permanent magnet 62 m2 The ratios satisfy the following relationship:

[0079]

[0080] In a built-in permanent magnet motor, the width of the permanent magnet in the rotor circumferential direction directly affects the magnetic flux distribution in the air gap. For example... Figure 2 As shown, based on the principle of sinusoidal distribution of air gap magnetic flux density along the outer circle of the rotor, the width W of the first permanent magnet 61 m1 Width W of the second permanent magnet 62 m2 The essence of the relationship satisfied by the ratio is that the air gap magnetic flux density distribution corresponding to the width of the permanent magnet in the circumferential direction of the rotor is sinusoidal, so as to satisfy the ideal design of the air gap magnetic flux density distribution being closest to a sine wave.

[0081] It should be noted that the integral part of the above relationship is based on the assumption that the air gap magnetic flux density is distributed according to a sinusoidal law. In the design of rotors of asymmetric pole-embedded permanent magnet motors, pursuing a sinusoidal magnetic flux density distribution in the air gap helps to reduce harmonics, thereby reducing torque ripple and electromagnetic noise.

[0082] Specifically, it can be approximated that the air gap magnetic flux density corresponding to the first segment central angle θ1 is provided by the first permanent magnet 61, and the air gap magnetic flux density corresponding to the second segment central angle θ2 and the third segment central angle θ3 is provided by the second permanent magnet 62, and the air gap magnetic flux density corresponding to the second segment central angle θ2 and the third segment θ3 is equal. In other words, the above relationship reflects the ratio of the contribution values ​​of the first permanent magnet 61 and the second permanent magnet 62 to the corresponding air gap magnetic flux density. Based on the first segment central angle θ1 and the second segment central angle θ2, combined with the number of pole pairs p of the rotor, the width W of the first permanent magnet 61 can be calculated. m1 Width W of the second permanent magnet 62 m2 The ratio of .

[0083] In some optional embodiments, the above design method further includes: based on the first segmented central angle θ1, the second segmented central angle θ2, the third segmented central angle θ3, and the corresponding first air gap magnetic flux density B. g1 Second air gap magnetic flux density B g2 Third air gap magnetic flux density B g3 Determine the target air gap average magnetic flux density B av .

[0084] Specifically, the first air gap magnetic flux density B was obtained. g1 Second air gap magnetic flux density B g2 Third air gap magnetic flux density Bg3 The steps include:

[0085] First, based on the first segment central angle θ1, the second segment central angle θ2, the third segment central angle θ3, and the rotor radius D... r Let the first air gap arc length W corresponding to the first segment central angle θ1, the second segment central angle θ2, and the third segment central angle θ3 be respectively. g1 The second air gap arc length W g2 The third air gap arc length W g3 The first air gap arc length W g1 The second air gap arc length W g2 The third air gap arc length W g3 The satisfied relationship is:

[0086]

[0087] Secondly, based on the first air gap arc length W g1 The second air gap arc length W g2 The third air gap arc length W g3 and rotor stack thickness L stk The central angle θ1 of the first segment corresponds to the area A of the first air gap. g1 The second segment's central angle θ2 corresponds to the second air gap area A. g2 The central angle θ3 of the third segment corresponds to the area A of the third air gap. g3 The satisfied relationship is:

[0088]

[0089] Then, along the rotor stack thickness L stk The direction, the perpendicular magnetic circuit area A of the first permanent magnet 61 m1 The perpendicular magnetic circuit area A of the second permanent magnet 62 m2 The satisfied relationship is:

[0090]

[0091] According to Gauss's law, the total magnetic flux through the permanent magnet is the same as the total magnetic flux through the air gap. The satisfied relationship is:

[0092]

[0093] The magnetic flux density passing through the permanent magnet is B. m The leakage coefficient is kl, which reflects the degree of attenuation of the magnetic field of the permanent magnet in the actual built-in permanent magnet motor. The leakage coefficient kl is approximately calculated to be 0.9.

[0094] Then, the magnetic flux density of the first air gap is B. g1 Second air gap magnetic flux density Bg2 Third air gap magnetic flux density B g3 The satisfied relationship is:

[0095]

[0096] It should be noted that, through the second air gap area A g2 The magnetic flux and the area A through the third air gap g3 The magnetic flux is provided by the second permanent magnet 62, through the second air gap area A g2 The magnetic flux is equal to the magnetic flux through the area A of the third air gap. g3 The magnetic flux (in opposite directions) is related by the following formula:

[0097]

[0098]

[0099] Due to the magnetic flux density B in the second air gap g2 With the third air gap magnetic flux density B g3 Since the absolute values ​​are equal, we can conclude that the central angle θ2 of the second segment is equal to the central angle θ3 of the third segment.

[0100] Specifically, based on the first air gap magnetic flux density B g1 Second air gap magnetic flux density B g2 Third air gap magnetic flux density B g3 The pole pitch τ of the built-in permanent magnet motor p Target air gap average magnetic flux density B av The satisfied relationship is:

[0101]

[0102] Among them, B m Let B be the magnetic field strength of the permanent magnet. m The satisfied relationship is:

[0103]

[0104] Where, μ M H is the permeability of a permanent magnet. m B is the magnetic field strength of the permanent magnet. r To compensate for the residual magnetism of the permanent magnet, the pole pitch τ of the built-in permanent magnet motor p satisfy:

[0105]

[0106] Based on the target air gap average magnetic flux density B av Based on the principle of sinusoidal distribution of air gap magnetic flux along the outer circle of the rotor, the first air gap magnetic flux B g1 Second air gap magnetic flux density Bg2 Third air gap magnetic flux density B g3 The design concept satisfies the following relationship:

[0107]

[0108] Optionally, in this field, the average air gap magnetic flux density B of the built-in permanent magnet motor av Within a defined high-efficiency range, namely between 0.54T and 0.66T (T, Tesla), the above-mentioned air gap average magnetic flux density B av The specified range can improve the overall efficiency of the built-in permanent magnet motor, ensure its smooth operation, and extend its service life. In other words, the target air gap average magnetic flux density B... av The value is selected between 0.54T and 0.66T. The target air gap average magnetic flux density B is determined. av After that, W can be calculated. m1 +2W m2 The specific value.

[0109] By reasonably setting the target air gap average magnetic flux density B av The design method of this application can ensure that the built-in permanent magnet motor achieves the optimal magnetic flux density distribution in the air gap during operation, thereby enabling the built-in permanent magnet motor to exhibit the best electromagnetic torque characteristics under different working conditions.

[0110] In Embodiment 1, the rotor radius D of the built-in permanent magnet motor in Embodiment 1 r The rotor thickness is 167.5 mm, and the rotor stack thickness is L. stk The air gap is 110 mm thick, and the average magnetic flux density is B. av The value is 0.60T. Based on the width W of the first permanent magnet 61... m1 Width W of the second permanent magnet 62 m2 The ratio of W m1 +2W m2 The specific value can be used to calculate the width W of the first permanent magnet 61. m1 The width W of the second permanent magnet 62 is 24mm. m2 It is 4mm.

[0111] In some alternative embodiments, the thickness of the permanent magnet can be T. m This can be determined by Ampere's circuital law, which satisfies the following relationship:

[0112]

[0113] According to Ampere's circuital law, and considering that the total magnetic flux through the permanent magnet is the same as the total magnetic flux through the air gap, we can conclude that:

[0114]

[0115] Where kr is the rotor internal reluctance coefficient, and in the built-in permanent magnet motor applied in this application, the rotor internal reluctance coefficient kr is taken as 1 to 1.2, H g Let H be the air gap magnetic field strength, μ0 be the free permeability, and H be the air gap magnetic field strength. g The satisfied relationship is:

[0116]

[0117] That is to say, in step 4, the thickness T of the permanent magnet m The following relationship must be satisfied:

[0118]

[0119] Among them, B g Let γ be the air gap working magnetic flux density, kr be the reluctance coefficient, and g be the air gap width, which extends radially along the rotor. m satisfy:

[0120]

[0121] In Embodiment 1, the thickness T of the first permanent magnet 61 m1 The thickness T of the second permanent magnet 62 m2 Similarly, in Example 1, the air gap width g corresponding to a single magnetic pole unit 30 is set to 0.5 mm, and the thickness T of the permanent magnet can be calculated. m The thickness is 2mm. The thickness T of the permanent magnet is obtained through... m The specific value ensures that the magnetic field distribution between the permanent magnet and the air gap reaches the optimal state during the operation of the built-in permanent magnet motor, thereby improving the electromagnetic torque and overall efficiency of the built-in permanent magnet motor.

[0122] Furthermore, the design method of this application can pre-evaluate the thickness of the permanent magnet during the design phase, avoiding trial-and-error costs in subsequent adjustments and improving design efficiency. Of course, Embodiment 1 is a specific application under given embedded permanent magnet motor structure and operating conditions. For different embedded permanent magnet motor designs, the calculated thickness of the permanent magnet still needs to be adjusted based on their respective parameters to achieve optimal matching. In other embodiments not shown in the figures, the thickness of the permanent magnet can also be determined using the design method of this application by changing the remanence or permeability of the permanent magnet, or by adjusting the air gap width and reluctance coefficient, thereby optimizing the performance of the embedded permanent magnet motor.

[0123] It should be noted that, based on the calculated dimensions of the permanent magnet, the permanent magnet and the magnetic barrier are placed in appropriate positions to ensure the realization of magnetic pole deflection. For example... Figure 2As shown, the centerline of the first permanent magnet slot 31 intersects the centerline of the second permanent magnet slot 33 at point M. Connect points M and A, and connect points M and C, so that a permanent magnet angle α is formed between the straight lines MA and MC. The permanent magnet angle α is determined by the finite element method (FEM). According to the finite element method, the permanent magnet angle α is simulated to select a value that satisfies the requirements of smooth magnetic circuit and optimal back EMF. After confirming the permanent magnet angle α, the designers set the positions of the first permanent magnet slot 31, the second permanent magnet slot 33, the pole cap magnetic barrier slot 32 located between the first permanent magnet slot 31 and the second permanent magnet slot 33, and the outer magnetic barrier slot 34 located outside the second permanent magnet slot 33 on the side away from the pole cap magnetic barrier slot 32, according to the final position of the permanent magnet. By applying calculations and the finite element method, it can be ensured that the rotor of the asymmetric magnetic pole built-in permanent magnet motor meets both high performance requirements and economical material usage, providing a basis for optimizing the design of built-in permanent magnet motors.

[0124] Preferably, the included angle α of the permanent magnets is in the range of 90° to 110°.

[0125] In addition, there is a rib bridge 50 between two adjacent magnetic pole units 30, and auxiliary holes 51 are arranged on the rib bridge 50 along the radial direction of the rotor to further optimize the magnetic circuit and reduce eddy current losses.

[0126] In Example 1, the included angle α of the permanent magnet is 92°.

[0127] After the design of Embodiment 1 of this application is completed, the back EMF (RMS) is 342V and the back EMF (THD) is 1%, indicating that Embodiment 1 can meet the voltage requirements of the built-in permanent magnet motor at the rated speed. At the same time, it achieves the optimization of the back EMF waveform, controlling the harmonic components to within 1%, so that the built-in permanent magnet motor will have very stable operating characteristics and high efficiency in actual operation.

[0128] In such Figure 6 In the first comparative example shown, Figure 6 A magnetic pole unit 30 of an internal permanent magnet motor with a symmetrical rotor is shown under the same operating conditions. The difference from Embodiment 1 is that the first permanent magnet 61 and the second permanent magnet 62 are symmetrically arranged, the first permanent magnet slot 31 and the second permanent magnet slot 33 are symmetrically arranged, and the comparative embodiment 1 does not have a pole cap magnetic barrier slot 32 and a permanent magnet outer magnetic barrier slot 34.

[0129] The data for permanent magnet torque, reluctance torque, and electromagnetic torque in Example 1 and Comparative Example 1 are shown in Table 1. It should be noted that the units for permanent magnet torque, reluctance torque, and electromagnetic torque are all Newton-meters (N·m).

[0130] Table 1

[0131]

[0132] As shown in Table 1 above, the peak values ​​of the reluctance torque in both Comparative Example 1 and Example 1 occur at the midpoint between the permanent magnet torque and the reluctance torque, meaning the current angle at the peak of the reluctance torque is 45°. The peak current angle of the permanent magnet torque in Comparative Example 1 is 0°, and its peak value is 73.1 N·m. In Example 1, the peak current angle is 11.2°, and its peak value is 75.2 N. This indicates that the peak current angle of the permanent magnet torque shifts by 11.2°, demonstrating that Example 1 can introduce a shift in the current angle to alter the timing of the peak value of the permanent magnet torque. Furthermore, the peak value of the permanent magnet torque in Example 1 is enhanced due to the magnetic focusing effect generated by the pole shift.

[0133] In other words, by reducing the potential angle phase difference between the peak value of the permanent magnet torque and the peak value of the reluctance torque to 33.8°, the permanent magnet torque and the reluctance torque can be superimposed more effectively. The peak value of the synthesized electromagnetic torque in Comparative Example 1 is 80.7 N·m, and the peak value of the synthesized electromagnetic torque in Example 1 is 84.4 N·m, which means that the peak value of the synthesized electromagnetic torque is increased by 4.5%, indicating that Example 1 can generate a larger output torque density under the same working conditions.

[0134] Furthermore, under the same operating conditions, the internal power factor angle of Comparative Example 1 is 18°, while that of Example 1 is 26.7°, meaning the internal power factor angle has shifted by 8.7°. This changes the current angle phase difference between the current and the magnetic field of the armature coil 71, thereby improving the overall efficiency and performance of the built-in permanent magnet motor.

[0135] As illustrated in Example 1, the design method for a rotor of a permanent magnet motor with asymmetrical magnetic poles provides an effective approach to enhance the permanent magnet torque and reluctance torque of the motor, reduce torque ripple, and improve the motor's torque density and operating efficiency. This design method offers high flexibility and versatility, making it a powerful tool in the field of permanent magnet motor design.

[0136] This application also includes a permanent magnet motor, the rotor of which is designed and manufactured using the above-described design method for asymmetric magnetic pole built-in permanent magnet motor rotor.

[0137] Obviously, the embodiments described above are merely some, not all, embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0138] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0139] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0140] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A design method of a rotor of an asymmetric interior permanent magnet motor, each pole unit (30) of the rotor is provided with two permanent magnets, the two permanent magnets include a first permanent magnet (61) and a second permanent magnet (62), the size of the first permanent magnet (61) is larger than the size of the second permanent magnet (62), characterized in that, The design method is used to establish a preset magnetic pole offset electric angle θ e A mapping rule between the size of the two permanent magnets wherein the magnetic pole offset electrical angle θ e defined as the electrical angle between the equivalent magnetic field centerline of a single said magnetic pole unit (30) and the geometric centerline of said magnetic pole unit (30); the design method comprises the steps of: Step 1: input the preset magnetic pole offset electrical angle θ e ; Step 2: determining the first sector central angle θ1, the second sector central angle θ2, and the third sector central angle θ3 of the air gap on the outer circle corresponding to the single magnetic pole unit (30) of the rotor according to the preset magnetic pole offset electrical angle θ e , wherein θ2=θ3. Step 3: determining the width of the two permanent magnets in the circumferential direction of the rotor based on the first sector angle θ1, the second sector angle θ2, and the third sector angle θ3, the width of the first permanent magnet (61) being W m1 , and the width of the second permanent magnet (62) being W m2 ; Step 4: determining the thickness T of the permanent magnet based on the first sector central angle θ1, the second sector central angle θ2, the third sector central angle θ3, and according to the relationship that the magnetomotive force of the permanent magnet is balanced with the magnetic pressure drop of the air gap m ; The mapping rule is used to execute the steps 2 to 4, so that the magnetic pole offset electric angle θ e The calculated sizes of the two permanent magnets and the magnetic barrier arranged according to the sizes of the two permanent magnets physically realize the magnetic pole offset electric angle θ e .

2. The design method of claim 1, wherein In step 2, the magnetic pole offset electrical angle θ e The third segment central angle θ3 satisfies the relationship: where p represents the number of magnetic pole pairs of the rotor.

3. The method of designing according to claim 1, wherein, In step 3, the width W of the first permanent magnet (61) in the circumferential direction of the rotor is... m1 The width W of the second permanent magnet (62) m2 The ratio is determined by the first segmented central angle θ1 and the second segmented central angle θ2, based on the principle of making the air gap magnetic flux density sinusoidally distributed along the outer circle of the rotor.

4. The method of designing according to claim 3, wherein, width W of the first permanent magnet (61) m1 width W of the second permanent magnet (62) m2 satisfies the following relationship: .

5. The method of claim 1, wherein, The design method further comprises: determining a target air-gap average magnetic flux density B g1 , based on the first sector angle θ1, the second sector angle θ2, the third sector angle θ3 and the corresponding first air-gap magnetic flux density B g2 , the second air-gap magnetic flux density B g3 , and the third air-gap magnetic flux density B av .

6. The method of designing according to claim 5, wherein, The target air gap average magnetic density B av is determined by the following formula: wherein the first segment circle central angle θ1 corresponds to the first air gap area A g1 , the second segment circle central angle θ2 corresponds to the second air gap area A g2 , and the third segment circle central angle θ3 corresponds to the third air gap area A g3 , B m is the working magnetic density of the permanent magnet, kl is the leakage magnetic coefficient, τ p is the pole pitch.

7. The method of claim 1, wherein In step 4, the thickness T of the permanent magnet m satisfies the following relationship: where B g is the air-gap working magnetic flux density, μ M is the permeability of the permanent magnet, kr is the reluctance coefficient, g is the air-gap width, B r is the residual magnetism of the permanent magnet, μ0 is the vacuum permeability, .

8. The design method according to any one of claims 1 to 7, characterized in that, further comprising the steps of: Step 5: according to the width W of the first permanent magnet (61) m1 , the width W of the second permanent magnet (62) m2 , the thickness T of the permanent magnet m and the first segment central angle θ1, the second segment central angle θ2, the third segment central angle θ3, the positions of the first permanent magnet slot (31), the second permanent magnet slot (33), the pole cap magnetic barrier slot (32) located between the first permanent magnet slot (31) and the second permanent magnet slot (33), and the permanent magnet outer magnetic barrier slot (34) located on one side of the second permanent magnet slot (33) away from the pole cap magnetic barrier slot (32) are determined in a single magnetic pole unit (30) of the rotor, and the arrangement of the first permanent magnet slot (31) and the second permanent magnet slot (33) is biased towards the side away from the permanent magnet outer magnetic barrier slot (34).

9. A permanent magnet electric machine characterized by, the rotor of the permanent magnet motor is designed and manufactured by using the design method of any one of claims 1 to 8.

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