CN110212665B - Hybrid rotor continuous pole permanent magnet synchronous motor and method for reducing torque ripple thereof - Google Patents
Hybrid rotor continuous pole permanent magnet synchronous motor and method for reducing torque ripple thereof Download PDFInfo
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- CN110212665B CN110212665B CN201910382092.7A CN201910382092A CN110212665B CN 110212665 B CN110212665 B CN 110212665B CN 201910382092 A CN201910382092 A CN 201910382092A CN 110212665 B CN110212665 B CN 110212665B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K1/00—Details of the magnetic circuit
- H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
- H02K1/22—Rotating parts of the magnetic circuit
- H02K1/27—Rotor cores with permanent magnets
- H02K1/2706—Inner rotors
- H02K1/272—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis
- H02K1/274—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets
- H02K1/2753—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets the rotor consisting of magnets or groups of magnets arranged with alternating polarity
- H02K1/276—Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM]
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K1/00—Details of the magnetic circuit
- H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
- H02K1/22—Rotating parts of the magnetic circuit
- H02K1/27—Rotor cores with permanent magnets
- H02K1/2706—Inner rotors
- H02K1/272—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis
- H02K1/274—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets
- H02K1/2753—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets the rotor consisting of magnets or groups of magnets arranged with alternating polarity
- H02K1/278—Surface mounted magnets; Inset magnets
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K2213/00—Specific aspects, not otherwise provided for and not covered by codes H02K2201/00 - H02K2211/00
- H02K2213/03—Machines characterised by numerical values, ranges, mathematical expressions or similar information
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K29/00—Motors or generators having non-mechanical commutating devices, e.g. discharge tubes or semiconductor devices
- H02K29/03—Motors or generators having non-mechanical commutating devices, e.g. discharge tubes or semiconductor devices with a magnetic circuit specially adapted for avoiding torque ripples or self-starting problems
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Abstract
The invention discloses a hybrid rotor continuous pole permanent magnet synchronous motor and a method for reducing torque pulsation thereof; a hybrid rotor continuous pole permanent magnet synchronous machine comprising: an outer stator and an inner rotor; the outer stator is provided with five-phase distributed armature windings; the inner rotor is provided with surface embedded permanent magnets and spoke type permanent magnets; a method for reducing torque pulsation of a hybrid rotor continuous pole permanent magnet synchronous motor specifically comprises the following steps: firstly, torque ripple is reduced by increasing the number of phases of the permanent magnet motor; then, torque pulsation is reduced again by optimizing the pole arc coefficient and the thickness of the surface-embedded permanent magnet and the length and the width of the spoke type permanent magnet; then, the spoke-type permanent magnets are angularly offset, further reducing torque ripple. The motor overcomes the defects of large torque pulsation, large eddy current loss of the permanent magnet and easy demagnetization of the permanent magnet during overload of the traditional continuous pole permanent magnet synchronous motor, and simultaneously keeps the characteristics of large torque density and high utilization rate of the permanent magnet of the original motor.
Description
Technical Field
The invention relates to a design of a hybrid rotor continuous pole permanent magnet synchronous motor, in particular to a method for reducing torque pulsation of the hybrid rotor continuous pole permanent magnet synchronous motor, and belongs to the technical field of motor manufacturing.
Background
At present, permanent magnet synchronous motors are widely applied, and play an important role in a plurality of fields from automobiles to aerospace. This benefits mainly from several significant features of permanent magnet synchronous motors, including high torque density, high efficiency, and small weight and volume. The permanent magnet synchronous motor adopts the magnetic material with high magnetic energy product to replace the traditional excitation winding, thereby not only eliminating the negative effect brought by the excitation winding, but also simplifying the mechanical structure of the motor, improving the operation reliability of the motor and correspondingly reducing the mechanical loss.
Generally, a continuous pole permanent magnet synchronous motor is a surface-embedded continuous pole permanent magnet synchronous motor, which has high torque density and high permanent magnet utilization rate, but also has high torque pulsation, and the permanent magnet is easy to demagnetize when being overloaded.
Many permanent magnet synchronous motors use rare earth permanent magnets with high power density, and the permanent magnets are expensive and are the main cost of the permanent magnet synchronous motors. The continuous pole permanent magnet synchronous motor can greatly improve the utilization rate of the permanent magnet, so that the research on the continuous pole permanent magnet synchronous motor becomes a hotspot in recent years. Continuous pole permanent magnets can greatly improve the permanent magnet utilization in fractional slot concentrated winding motors, so that they can reduce the material cost of the motor. But the existing continuous pole permanent magnet is hardly applied to the permanent magnet synchronous motor with the integral slot distributed winding. Continuous pole permanent magnets, once applied in an integer slot distributed winding machine, can introduce high torque ripple. Although continuous pole PMSM possesses a number of advantages, many difficulties remain for demanding high performance applications, such as electric steering systems, servo motors, wind generators, electric vehicle drive systems, and the like. These applications place high demands on the operational stability of the motor, i.e., the output torque ripple of the motor is as small as possible to achieve smooth and accurate thrust transmission, and it is very valuable to study the reduction of the output torque ripple. In summary, it is very valuable to study the attenuation of the output torque ripple of the continuous pole integer slot permanent magnet synchronous motor.
At present, the suppression of the torque ripple of the fractional-slot concentrated winding continuous pole permanent magnet synchronous motor is deeply researched at home and abroad, such as methods of optimizing pole arc coefficients, adopting multilayer windings, adopting skewed slots, optimizing rotor structures and the like. However, the technology for suppressing the torque ripple of the integral slot continuous pole permanent magnet synchronous motor is very limited and is less researched. Secondly, for the unequal pole arc coefficient method, the prior art only aims at the reduction of the cogging torque and is only used in the traditional discontinuous pole permanent magnet synchronous motor. In the embedded or surface-embedded motor which is widely applied at present, the source of the torque ripple is not limited to the cogging torque, but can be derived from the permanent magnet torque and the reluctance torque, and the cogging torque only occupies a very small part of the torque ripple. On the basis, the analysis of the cogging torque limited to the non-continuous pole permanent magnet synchronous motor is far from enough. Therefore, how to effectively reduce the major harmonic in the torque ripple of the integer slot continuous pole permanent magnet synchronous motor is a direction that needs to be intensively studied. The traditional continuous pole permanent magnet synchronous motor has large eddy current loss of the permanent magnet, and the permanent magnet is easy to generate demagnetization phenomenon when being overloaded, so that the reduction of the eddy current loss of the permanent magnet and the enhancement of the demagnetization resistance of the permanent magnet are very significant and necessary for improving the efficiency and the reliability of the motor. In summary, it is very significant and necessary to research a hybrid rotor continuous pole permanent magnet synchronous motor and a method for reducing torque ripple thereof.
Disclosure of Invention
In view of the problems in the prior art, the invention provides a hybrid rotor continuous pole permanent magnet synchronous motor, which mixes surface-embedded permanent magnets and spoke-type permanent magnets to form a novel hybrid rotor continuous pole permanent magnet synchronous motor, and the hybrid rotor continuous pole permanent magnet synchronous motor has the characteristics of low cost, high torque density, high reliability, high efficiency and the like. Aiming at the problem of high torque ripple in the prior art, the invention provides a method for reducing the torque ripple of a hybrid rotor continuous pole permanent magnet synchronous motor, which achieves the effect of reducing the torque ripple by optimizing the pole arc coefficient of a surface embedded permanent magnet, the thickness of the surface embedded permanent magnet and the length and width of a spoke type permanent magnet of the hybrid rotor continuous pole permanent magnet synchronous motor. On the basis of a multivariable optimized mixed rotor continuous pole permanent magnet synchronous motor, the spoke type permanent magnets are subjected to angle deviation, and the torque pulsation of the motor is further reduced.
The invention aims to provide a hybrid rotor continuous pole permanent magnet synchronous motor with low cost, low pulsation, high torque density, high reliability and high efficiency and a method for reducing the torque pulsation of the hybrid rotor continuous pole permanent magnet synchronous motor.
The technical scheme adopted by the invention is as follows: a rotor structure of a hybrid rotor continuous pole permanent magnet synchronous motor comprises surface embedded permanent magnets, spoke permanent magnets and a rotor iron core; the surface-embedded permanent magnets are 2n, n is 1,2 and 3 …, the shape design structure is an arc structure, the radial magnetizing directions of the permanent magnets are consistent, the permanent magnets are symmetrically embedded on the circumference of the inner side of the rotor core, and each surface-embedded permanent magnet and the adjacent rotor core form a pair of poles; the spoke type permanent magnets are 4n, the shape is designed to be a rectangular structure, every two spoke type permanent magnets are symmetrically arranged in a rotor core, every two adjacent spoke type permanent magnets form a pair of poles, each surface-embedded type permanent magnet and every two adjacent spoke type permanent magnets are distributed in a staggered mode in space, the included angle between every two adjacent spoke type permanent magnets is 45 degrees/n before deviation, and every two spoke type permanent magnets are deviated towards the central lines of the spoke type permanent magnets by theta/n angles after deviation; the motor rotor structure is symmetrical about a horizontal line and a vertical line.
Furthermore, the surface embedded permanent magnets are 2, and the spoke permanent magnets are 4.
Further, the offset angle θ is 1 °.
The invention discloses a method for reducing torque pulsation of a hybrid rotor continuous pole permanent magnet synchronous motor, which comprises the following steps of:
and 3, performing angle deviation theta on the spoke type permanent magnet on the basis of the obtained model of the optimized motor, thereby achieving the purpose of further reducing torque pulsation.
Further, the permanent magnet synchronous motor in the step 1 is five-phase, and the torque ripple T of the permanent magnet synchronous motor is TpulThe calculation formula of (2) is as follows:
wherein, mu0Is the permeability of air, p is the pole pair number, g is the air gap length, rgIs the radius of the intermediate air gap, L is the lamination stack length, γdExpressed as current angle, h harmonic order, FshAnd FrhH-order stator and rotor magnetomotive forces, respectively. So as to be able to produce torque rippleThe harmonic order of the magnetic kinetic potential of the stator and the rotor is as follows: when h is 10m ± 1 and m is 1,2,3 …, the harmonic order of the rotor air gap flux density affecting the torque ripple is: h is 10m + -1, m is 1,2,3 …; compared with a traditional three-phase motor, the motor is designed into a five-phase motor, and the torque main pulsation order of the motor is increased from 6m times to 10m (m is 1,2,3 …) times.
Further, the pole arc coefficient of the optimized table-embedded permanent magnet in step 2 is 0.65, the thickness of the table-embedded permanent magnet is 4.1mm, the length of the spoke type permanent magnet is 18.4mm, and the width of the spoke type permanent magnet is 4.8mm, so that the harmonic order (10m ± 1, m ═ 1,2,3 …) of the rotor air gap flux density influencing the torque ripple is reduced, namely the harmonic order (10m ± 1, m ═ 1,2,3 …) causing the torque ripple in the rotor magnetomotive force is reduced, and therefore, the proposed hybrid rotor continuous pole permanent magnet synchronous motor provides a basis for multivariable optimized motor torque.
Further, the offset angle θ in step 3 is 1 °.
Further, the pole arc coefficient of the surface-embedded permanent magnet is 0.5-0.7, the ratio of the thickness of the surface-embedded permanent magnet to the difference between the inner diameter and the outer diameter of the rotor iron core corresponding to the surface-embedded permanent magnet is 0.1-0.16:1, the ratio of the length of the spoke-type permanent magnet to the difference between the inner diameter and the outer diameter of the rotor iron core corresponding to the surface-embedded permanent magnet is 0.5-0.8:1, and the ratio of the length of the spoke-type permanent magnet to the difference between the inner diameter and the outer diameter of the rotor iron core corresponding to the spoke-type permanent magnet is 0.5: 1; the four inner arcs of the rotor core are all 90 degrees relative to the circle center.
The invention has the following beneficial effects:
1. the pole arc coefficient of the surface-embedded permanent magnet is 0.5-0.7, the ratio of the thickness of the surface-embedded permanent magnet to the difference between the inner diameter and the outer diameter of the rotor iron core corresponding to the surface-embedded permanent magnet is 0.1-0.16:1, the ratio of the length of the spoke-type permanent magnet to the difference between the inner diameter and the outer diameter of the rotor iron core corresponding to the surface-embedded permanent magnet is 0.5-0.8:1, and the ratio of the length of the spoke-type permanent magnet to the difference between the inner diameter and the outer diameter of the rotor iron core corresponding to the spoke-type permanent magnet is 0.5: 1; the four inner arcs of the rotor core are 90 degrees relative to the circle center, so that the permanent magnet motor can simultaneously take the two advantages of high permanent magnet utilization rate and high torque density into consideration.
2. The hybrid rotor continuous pole permanent magnet synchronous motor of the invention provides possibility for reducing torque pulsation of the continuous pole permanent magnet synchronous motor, is not limited to reducing torque pulsation caused by cogging torque, can also effectively reduce torque pulsation caused by permanent magnet torque or reluctance torque, optimizes counter electromotive force and reduces final output torque pulsation, thus obviously improving the stability of the motor.
3. The hybrid rotor continuous pole permanent magnet synchronous motor can reduce the eddy current loss of the permanent magnet and enhance the demagnetization resistance of the permanent magnet of the motor during overload.
4. The hybrid rotor continuous pole permanent magnet synchronous motor has the advantages of low cost, low pulsation, high torque density, high reliability and high efficiency, and can comprehensively improve the performance of the motor.
5. The method for reducing the torque ripple of the continuous pole motor can be applied to motors with different phase numbers or with different slot poles, so that different motors can achieve similar effects.
The invention relates to a hybrid rotor continuous pole permanent magnet synchronous motor, which organically combines a continuous pole surface embedded permanent magnet and a spoke type permanent magnet to create a novel hybrid rotor continuous pole permanent magnet synchronous motor. First, the motor is designed as a five-phase motor, and compared with a conventional three-phase motor, the torque main pulsation order of the motor is increased from 6m (m is 1,2,3 …) times to 10m (m is 1,2,3 …) times, so that the torque pulsation of the motor is fundamentally reduced when the motor is designed. And secondly, optimizing the pole arc coefficients of the surface-embedded permanent magnets, the thicknesses of the surface-embedded permanent magnets and the lengths and the widths of the spoke-type permanent magnets to reduce the harmonic orders (10m +/-1, m is 1,2 and 3 …) of the magnetic density of the rotor air gap influencing the torque ripple, namely the harmonic orders (10m +/-1, m is 1,2 and 3 …) causing the torque ripple in the rotor magnetomotive force, thereby achieving the effect of reducing the torque ripple again. On the basis of a multivariable optimized mixed rotor continuous pole permanent magnet synchronous motor, the spoke type permanent magnets are subjected to angle deviation, and the torque pulsation of the motor is further reduced.
Drawings
Fig. 1 is a schematic structural diagram of a conventional continuous pole permanent magnet synchronous motor (primary motor) according to the present invention.
Fig. 2 is a schematic structural diagram of a hybrid rotor continuous pole permanent magnet synchronous motor (an embodiment motor) according to the present invention.
FIG. 3 is a comparison of the rotor air gap flux density of the original motor and the motor of the embodiment of the present invention.
Fig. 4 is a graph of the rotor air gap flux density harmonic analysis of the original motor and the motor of the embodiment of the invention.
FIG. 5 is a comparison of counter electromotive forces of the original motor and the motor of the embodiment of the present invention.
Fig. 6 is a diagram showing back emf harmonics of the original motor and the motor of the embodiment of the present invention.
FIG. 7 is a comparison of cogging torque of the original motor and the motor of the embodiment of the present invention.
FIG. 8 is a graph comparing output torques of a motor according to the present invention and a motor according to an embodiment.
Fig. 9 is an analysis diagram of harmonic output torque of the motor of the embodiment of the present invention.
Fig. 10 is a graph comparing loss of output torque of the original motor and the motor of the embodiment of the present invention.
FIG. 11 is a graph showing the comparison of the efficiency of the original motor and the motor of the embodiment of the present invention.
Detailed Description
The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.
The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
Fig. 1 is a schematic structural diagram of a conventional continuous pole permanent magnet synchronous motor (primary motor) according to the present invention. As shown in fig. 1, the conventional continuous pole permanent magnet synchronous motor includes an outer stator 1 and an inner rotor 2; the outer stator 1 comprises 40 stator slots and armature windings 3 embedded therein; the inner rotor 2 comprises a rotor iron core and 4 arc-shaped permanent magnetic poles 4.
Fig. 2 is a schematic structural diagram of a hybrid rotor continuous pole permanent magnet synchronous motor (an embodiment motor) according to the present invention. As shown in fig. 2, the proposed five-phase hybrid rotor continuous pole permanent magnet synchronous motor includes an outer stator 1 and an inner rotor 2; the outer stator 1 comprises 40 stator slots and armature windings 3 embedded therein; the inner rotor 2 comprises a rotor iron core, 2 arc-shaped permanent magnetic poles 4 and 4 spoke-type permanent magnetic poles 5, and the spoke-type permanent magnets are subjected to theta angle deviation.
The structure and method steps of a five-phase hybrid rotor continuous pole permanent magnet synchronous motor are shown below.
Step 1, a rotor structure of a hybrid rotor continuous pole permanent magnet synchronous motor, which is characterized in that: the novel rotor structure of the hybrid rotor continuous pole permanent magnet synchronous motor comprises surface embedded permanent magnets, spoke permanent magnets and a rotor iron core; the surface embedded permanent magnets are 2, the shape design structure is an arc-shaped structure, the radial magnetizing directions of the permanent magnets are consistent, the permanent magnets are symmetrically surface-embedded on the circumference of the inner side of the rotor core, and each surface-embedded permanent magnet and the adjacent rotor core form a pair of poles; the radial permanent magnets are 4, the shape is designed to be a rectangular structure, every two radial permanent magnets are symmetrically arranged in a rotor core, every two adjacent radial permanent magnets form a pair of poles, each surface-embedded permanent magnet and every two adjacent radial permanent magnets are distributed in a staggered mode in space, the included angle between every two adjacent radial permanent magnets is 45 degrees before the deviation, and every two radial permanent magnets are deviated to the central lines of the two radial permanent magnets by theta/n degrees after the deviation of the radial permanent magnets; the pole arc coefficient of the surface-embedded permanent magnet is 0.5-0.7, the ratio of the thickness of the surface-embedded permanent magnet to the difference between the inner diameter and the outer diameter of the rotor iron core corresponding to the surface-embedded permanent magnet is 0.1-0.16:1, the ratio of the length of the spoke-type permanent magnet to the difference between the inner diameter and the outer diameter of the rotor iron core corresponding to the surface-embedded permanent magnet is 0.5-0.8:1, and the ratio of the length of the spoke-type permanent magnet to the difference between the inner diameter and the outer diameter of the rotor iron core corresponding to the spoke-type permanent magnet is 0.5: 1; the four inner arcs of the rotor core are all 90 degrees relative to the circle center; the magnetizing direction of the permanent magnet is shown by a white arrow in FIG. 2; the rotor in the motor is symmetrical about a horizontal line and a vertical line.
wherein, mu0Is the permeability of air, p is the pole pair number, g is the air gap length, rgIs the radius of the intermediate air gap, L is the lamination stack length, γdExpressed as current angle, h harmonic order, FshAnd FrhH-order stator and rotor magnetomotive forces, respectively. Therefore, the harmonic order of the magnetomotive force of the stator and the rotor capable of generating torque ripple is as follows: when h is 10m ± 1 and m is 1,2,3 …, the harmonic order of the rotor air gap flux density affecting the torque ripple is: h is 10m + -1, m is 1,2,3 …; compared with the traditional three-phase motor, the motor is designed into a five-phase motor, the torque main pulsation order of the motor is increased from 6m (m is 1,2 and 3 …) times to 10m (m is 1,2 and 3 …) times, and therefore, when the motor is designed, the torque pulsation of the motor is fundamentally reduced.
Fig. 1 is a schematic structural diagram of a conventional continuous pole permanent magnet synchronous motor, which is used as an original motor in the invention.
Fig. 2 is a schematic structural diagram of a hybrid rotor continuous pole permanent magnet synchronous motor, which is taken as an embodiment of the motor. The invention carries out a hybrid rotor on the basis of the original motor (PM1 and PM4 are surface embedded permanent magnets, PM2, PM3, PM5 and PM6 are spoke type permanent magnets), obtains an embodiment motor, compares the performances of the two motors and explains the beneficial effects of the invention.
Fig. 3 and 4 show the comparison of the air gap flux density of the rotor of the original motor and the rotor of the motor of the embodiment and the harmonic analysis aspect of the air gap flux density, respectively. As shown in fig. 3, after using the hybrid continuous pole rotor, the 9, 11, 19 and 21 th rotor air gap flux density harmonics are greatly reduced, which means that the 9 and 11 th rotor magnetomotive force harmonics will be greatly reduced.
Fig. 5 and 6 show a comparison between the original motor and the motor of the embodiment in terms of back emf and harmonic analysis thereof, respectively. As shown in fig. 6, after the motor uses the hybrid rotor, not only the harmonic content of the no-load back electromotive force is reduced, but also the amplitude of the fundamental wave is slightly increased, which means that the average torque is only slightly increased while the performance of the motor in terms of torque pulsation is greatly improved. It can be seen that after using the hybrid continuous pole rotor, the 9, 11, 19 and 21 th back emf harmonics are greatly reduced, representing the 1 and 2 st major harmonics (10) of the torque ripplethAnd 20thHarmonics) are substantially attenuated.
FIG. 7 is a comparison of cogging torque of the original motor and the motor of the embodiment of the present invention. As can be seen from fig. 7, the cogging torque of the motor of the example was greatly reduced from 10.82Nm to 2.09Nm due to the use of the hybrid rotor.
Fig. 8 and 9 reflect a comparison of the original motor and the example motor in terms of final output torque and harmonic analysis thereof. The embodiment motor has a significantly reduced 1 st major harmonic of the torque ripple as compared to the original motor. The torque ripple of the motor of the embodiment is greatly reduced, and the torque ripple is reduced from the original 67.5% to 6.7%. And the average value of the output torque is increased from 19.04Nm to 19.10 Nm. Also as can be seen in FIG. 9, the 1 st and 2 nd major harmonics (10) of the torque ripplethAnd 20thHarmonics) are substantially attenuated.
Fig. 10 is a graph comparing loss of the original motor and the motor of the embodiment of the present invention. As can be seen from FIG. 10, the iron loss of the motor of the embodiment is slightly reduced from 29.73W to 29.09W and the eddy current loss of the permanent magnet is reduced from 2.17W to 1.36W due to the use of the hybrid rotor.
FIG. 11 is a graph showing the comparison of the efficiency of the original motor and the motor of the embodiment of the present invention. As can be seen from fig. 11, the efficiency of the motor of the embodiment is slightly increased from 94.38% to 94.44% due to the use of the hybrid rotor.
In summary, the invention discloses a hybrid rotor continuous pole permanent magnet synchronous motor and a method for reducing torque ripple thereof. A hybrid rotor continuous pole permanent magnet synchronous motor comprises an outer stator and an inner rotor. The outer stator comprises stator slots and five-phase armature windings embedded therein; the inner rotor comprises a rotor iron core, an arc-shaped permanent magnetic pole and a spoke-type permanent magnetic pole. A method for reducing torque ripple of a hybrid rotor permanent magnet synchronous motor specifically comprises the following steps: the traditional continuous pole permanent magnet synchronous motor and the spoke type permanent magnet synchronous motor are combined to form the novel hybrid rotor continuous pole permanent magnet synchronous motor. First, the motor is designed as a five-phase motor, and compared with a conventional three-phase motor, the torque main pulsation order of the motor is increased from 6m (m is 1,2,3 …) times to 10m (m is 1,2,3 …) times, so that the torque pulsation of the motor is fundamentally reduced when the motor is designed. Secondly, the traditional continuous pole arc surface-embedded permanent magnet provides possibility for optimizing the continuous pole permanent magnet synchronous motor of the hybrid rotor, and the harmonic order (10m +/-1, m is 1,2,3 …) causing torque pulsation in the rotor magnetomotive force can be reduced by optimizing the pole arc coefficient of the surface-embedded permanent magnet, the thickness of the surface-embedded permanent magnet and the length and width of the spoke type permanent magnet, so that the effect of reducing the torque pulsation again is achieved. Then, on the basis of the obtained model of the optimized motor, the spoke type permanent magnets are subjected to further angular offset, and the torque ripple is further reduced. The surface-embedded permanent magnet and the embedded spoke-type permanent magnet are mixed to form the novel hybrid rotor continuous pole permanent magnet synchronous motor, the motor effectively overcomes the defects that the traditional continuous pole motor is large in torque pulsation, large in eddy current loss of the permanent magnet and easy to demagnetize when the permanent magnet is overloaded, the demagnetization resistance of the permanent magnet of the motor is enhanced, and meanwhile, the characteristics of large torque density and high utilization rate of the permanent magnet of the original motor are kept, namely, the motor has the characteristics of low cost, low pulsation, high torque density, high reliability, high efficiency and the like.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
Claims (4)
1. The utility model provides a continuous utmost point PMSM rotor structure of hybrid rotor which characterized in that: the radial type permanent magnet rotor comprises a surface embedded permanent magnet, a spoke type permanent magnet and a rotor iron core; the surface-embedded permanent magnets are 2n, n is 1,2 and 3 …, the shape design structure is an arc structure, the radial magnetizing directions of the permanent magnets are consistent, the permanent magnets are symmetrically embedded on the circumference of the inner side of the rotor core, and each surface-embedded permanent magnet and the adjacent rotor core form a pair of poles; the spoke type permanent magnets are 4n, the shape is designed to be a rectangular structure, every two spoke type permanent magnets are symmetrically arranged in a rotor core, every two adjacent spoke type permanent magnets form a pair of poles, each surface-embedded type permanent magnet and every two adjacent spoke type permanent magnets are distributed in a staggered mode in space, the included angle between every two adjacent spoke type permanent magnets is 45 degrees/n before deviation, and every two spoke type permanent magnets are deviated towards the central lines of the spoke type permanent magnets by theta/n angles after deviation; the motor rotor structure is symmetrical about a horizontal line and a vertical line;
the offset angle θ is 1 °;
the number of the surface embedded permanent magnets is 2, and the number of the spoke type permanent magnets is 4.
2. A method for reducing torque ripple of a hybrid rotor continuous pole permanent magnet synchronous motor is characterized by comprising the following steps:
step 1, increasing the number of phases of a permanent magnet synchronous motor, thereby increasing the number of torque ripple cycles of the motor and reducing the torque ripple of the motor;
step 2, by optimizing the pole arc coefficient of the surface-embedded permanent magnet of the hybrid rotor, the thickness of the surface-embedded permanent magnet and the length and width of the spoke-type permanent magnet, the component causing torque pulsation in the magnetomotive force of the rotor is reduced, and the torque pulsation is reduced again;
step 3, performing angle deviation theta on the spoke type permanent magnet on the basis of the obtained optimized motor model, thereby achieving the purpose of further reducing torque pulsation;
the permanent magnet synchronous motor in the step 1 is five-phase, and the torque ripple T of the permanent magnet synchronous motorpulThe calculation formula of (2) is as follows:
wherein, mu0Is the permeability of air, p is the pole pair number, g is the air gap length, rgIs the radius of the intermediate air gap, L is the lamination stack length, γdExpressed as current angle, h harmonic order, FshAnd FrhH-order stator and rotor magnetomotive forces, respectively. Therefore, the harmonic order of the magnetomotive force of the stator and the rotor capable of generating torque ripple is as follows: when h is 10m ± 1 and m is 1,2,3 …, the harmonic order of the rotor air gap flux density affecting the torque ripple is: h is 10m + -1, m is 1,2,3 …; compared with a traditional three-phase motor, the motor is designed into a five-phase motor, and the torque main pulsation order of the motor is increased from 6m times to 10m (m is 1,2,3 …) times;
the pole arc coefficient of the surface-embedded permanent magnet is 0.5-0.7, the ratio of the thickness of the surface-embedded permanent magnet to the difference between the inner diameter and the outer diameter of the rotor iron core corresponding to the surface-embedded permanent magnet is 0.1-0.16:1, the ratio of the length of the spoke-type permanent magnet to the difference between the inner diameter and the outer diameter of the rotor iron core corresponding to the surface-embedded permanent magnet is 0.5-0.8:1, and the ratio of the length of the spoke-type permanent magnet to the difference between the inner diameter and the outer diameter of the rotor iron core corresponding to the spoke-type permanent magnet is 0.5: 1; the four inner arcs of the rotor core are all 90 degrees relative to the circle center.
3. The method for reducing torque ripple of a hybrid rotor continuous pole permanent magnet synchronous motor according to claim 2, wherein: the pole arc coefficient of the optimized surface-embedded permanent magnet in the step 2 is 0.65, the thickness of the surface-embedded permanent magnet is 4.1mm, the length of the spoke type permanent magnet is 18.4mm, the width of the spoke type permanent magnet is 4.8mm, and the harmonic order (10m +/-1, m is 1,2,3 …) of the rotor air gap flux density influencing the torque ripple is reduced, namely the harmonic order (10m +/-1, m is 1,2,3 …) causing the torque ripple in the rotor magnetomotive force.
4. The method for reducing torque ripple of a hybrid rotor continuous pole permanent magnet synchronous motor according to claim 2, wherein: the offset angle θ in step 3 is 1 °.
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| CN113949186B (en) * | 2021-09-30 | 2023-03-14 | 南京航空航天大学 | Few-harmonic alternating-pole hub motor |
| CN114123577B (en) * | 2021-11-05 | 2023-01-31 | 珠海格力电器股份有限公司 | Magnetic steel assembly, rotor assembly and motor |
| CN116738624B (en) * | 2023-08-16 | 2023-11-07 | 江苏大学 | Hybrid rotor permanent magnet motor and vibration optimization design method thereof |
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