Magnetic flux reverse permanent magnet motor

Abstract

The invention discloses a magnetic flux reverse permanent magnet motor, and belongs to the technical field of motors. The magnetic flux reverse permanent magnet motor comprises a rotor, a stator, an armature winding and a non-magnetic rotating shaft, excitation units are arranged on the inner surface of the stator in the circumferential direction; each excitation unit comprises a plurality of permanent magnets, each excitation unit is provided with a plurality of magnetic poles with different widths, and a plurality of permanent magnet excitation magnetomotive force working harmonic waves can be generated; on the basis, the stator comprises stator armature teeth and stator auxiliary teeth which are arranged along the circumferential direction of the stator in a staggered manner, and the tooth surface width of the stator armature teeth is greater than that of the stator auxiliary teeth, so that the span of an armature winding is increased, and the winding coefficient of each harmonic of armature magnetomotive force is changed; and low-order non-working harmonic waves of the armature can be converted into working harmonic waves, so that the torque density is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of motor technology, and more specifically, relates to a flux-reversing permanent magnet motor. Background Technology

[0002] Based on the location of the permanent magnets, permanent magnet motors can be divided into stator permanent magnet motors and rotor permanent magnet motors. Stator permanent magnet motors have permanent magnets attached to the inner surface of the stator teeth and use a high-strength reluctance rotor, offering advantages such as high robustness and easy thermal management. They are suitable for high-speed operation and have broad application prospects in fields such as electric vehicles. Stator permanent magnet motors mainly include switched flux permanent magnet motors (permanent magnets placed inside the stator teeth), doubly salient pole permanent magnet motors (permanent magnets placed in the stator yoke), and flux-reversing permanent magnet motors (permanent magnets placed on the stator tooth surface). Among these, flux-reversing permanent magnet motors have high permanent magnet utilization and are easy to install. Therefore, researching a flux-reversing permanent magnet motor is of great significance.

[0003] In traditional flux-reversing permanent magnet motors, multiple stator teeth of the same size and shape are evenly distributed along the circumference of the air gap, and each tooth surface is equipped with a pair of identical radially magnetized permanent magnets with opposite magnetization directions. Under this design, only the stator teeth's working permanent magnet magnetomotive force harmonics of the order several and multiples thereof can be generated, and there is serious leakage flux between adjacent permanent magnets, which greatly weakens the motor's torque output capability and results in low torque density. Summary of the Invention

[0004] In view of the above-mentioned defects or improvement needs of the prior art, the present invention provides a flux-reversing permanent magnet motor to solve the technical problem of low torque density in the prior art.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a flux-reversing permanent magnet motor, comprising: a rotor, a stator, an armature winding, and a non-magnetic shaft;

[0006] The rotor includes rotor teeth and rotor yoke. The rotor yoke is fixed on a non-magnetic shaft, and the rotor teeth are evenly arranged along the circumference of the rotor yoke.

[0007] The stator and rotor are coaxially mounted, and there is an air gap between the stator and rotor teeth;

[0008] The stator includes stator armature teeth and stator auxiliary teeth that are staggered along the circumferential direction of the stator; stator slots are provided between adjacent stator armature teeth and stator auxiliary teeth; the number of stator armature teeth and stator auxiliary teeth is the same, denoted as N; the tooth surface width of the stator armature teeth is greater than the tooth surface width of the stator auxiliary teeth.

[0009] N excitation units are arranged on the inner surface of the stator along the circumferential direction; the N excitation units correspond one-to-one with N pairs of adjacent stator armature teeth and stator auxiliary teeth; each excitation unit includes multiple permanent magnets, and each excitation unit has multiple magnetic poles of different widths; the inner surface is the side closest to the air gap.

[0010] The armature winding is wound around the stator armature teeth;

[0011] The armature winding magnetomotive force contains |Z| pole pairs. r ±P m / 2| of the subharmonics;

[0012] The number of stator slots, the number of armature winding pole pairs, and the number of rotor teeth satisfy the following:

[0013]

[0014] Among them, P a Z represents the number of pole pairs in the armature winding. r P is the number of rotor teeth; m Z is the number of pole pairs of the fundamental magnetomotive force of the permanent magnet, and its value is equal to Z. s Z s GCD(Z) represents the number of stator slots. s ,P a ) represents the least common divisor of the number of stator slots and the number of armature winding pole pairs; k is an integer greater than or equal to 1.

[0015] More preferably, the excitation unit includes: a tangentially magnetized permanent magnet group and a radially magnetized permanent magnet; the tangentially magnetized permanent magnet group includes: a first tangentially magnetized permanent magnet and a second tangentially magnetized permanent magnet with opposite magnetization directions;

[0016] The first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet are embedded in the corresponding stator armature tooth surface and are symmetrical about the central axis of the stator armature tooth; the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet are the same; the circumferential distance between the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet along the inner surface of the stator is greater than 1 / 2 of the tooth surface width of the corresponding stator armature tooth;

[0017] Radial magnetized permanent magnets are attached to the inner surface of the corresponding stator auxiliary teeth.

[0018] More preferably, the thicknesses of the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet are different from the thickness of the radially magnetized permanent magnet;

[0019] When the excitation directions of the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet both point to the central axis of the corresponding stator armature tooth, the magnetization direction of the radially magnetized permanent magnet points in the direction away from the air gap along the radial direction of the motor.

[0020] When the excitation directions of the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet are both away from the central axis, the magnetization direction of the radially magnetized permanent magnet points towards the air gap along the radial direction of the motor.

[0021] More preferably, the excitation unit includes: a tangentially magnetized permanent magnet group and a DC excitation winding; the tangentially magnetized permanent magnet group includes: a first tangentially magnetized permanent magnet and a second tangentially magnetized permanent magnet with opposite magnetization directions;

[0022] The first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet are embedded in the corresponding stator armature tooth surface and are symmetrical about the central axis of the stator armature tooth; the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet are the same; the circumferential distance between the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet along the inner surface of the stator is greater than 1 / 2 of the tooth surface width of the corresponding stator armature tooth;

[0023] The DC excitation winding is wound around the corresponding stator auxiliary teeth.

[0024] More preferably, when the magnetization directions of the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet both point to the central axis of the corresponding stator armature tooth, the excitation direction of the DC excitation winding points radially away from the air gap.

[0025] When the magnetization directions of the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet are both away from the central axis, the excitation direction of the DC excitation winding points radially toward the air gap.

[0026] More preferably, the excitation unit includes: a first radially magnetized permanent magnet, a second radially magnetized permanent magnet, a third radially magnetized permanent magnet, and a fourth radially magnetized permanent magnet; the first radially magnetized permanent magnet, the second radially magnetized permanent magnet, and the third radially magnetized permanent magnet are sequentially attached to the inner surface of the corresponding stator armature tooth, and the fourth radially magnetized permanent magnet is attached to the inner surface of the corresponding stator auxiliary tooth.

[0027] The first and third radially magnetized permanent magnets have the same width, but their widths differ from those of the second radially magnetized permanent magnet.

[0028] More preferably, the first radially magnetized permanent magnet, the third radially magnetized permanent magnet, and the fourth radially magnetized permanent magnet have the same magnetization direction, and are opposite to the magnetization direction of the second radially magnetized permanent magnet.

[0029] More preferably, the armature winding is a single-layer winding.

[0030] More preferably, the stator and rotor are coaxially mounted as follows: the stator is mounted outside the rotor or the stator is mounted inside the rotor.

[0031] More preferably, the structure of the flux-reversing permanent magnet motor is a rotary motor structure, a linear motor structure, or an axial flux motor structure.

[0032] In a second aspect, the present invention provides an electric motor, comprising: the flux-reversing permanent magnet motor provided in the first aspect of the present invention.

[0033] Thirdly, the present invention provides a generator, comprising: the flux-reversing permanent magnet motor provided in the first aspect of the present invention.

[0034] In summary, the above-described technical solutions conceived in this invention can achieve the following beneficial effects:

[0035] 1. This invention provides a flux-reversing permanent magnet motor, wherein an excitation unit is arranged on the inner surface of the stator along the circumferential direction; each excitation unit includes multiple permanent magnets and has multiple magnetic poles of varying widths, which can generate multiple permanent magnet excitation magnetomotive force working harmonics; based on this, the stator includes stator armature teeth and stator auxiliary teeth arranged alternately along the circumferential direction of the stator, and the tooth surface width of the stator armature teeth is greater than the tooth surface width of the stator auxiliary teeth, which increases the armature winding pitch, thereby changing the winding coefficient of each harmonic of the armature magnetomotive force, and can convert the low-order non-working harmonics of the armature into working harmonics, which greatly improves the torque density.

[0036] 2. Furthermore, the flux-reversing permanent magnet motor provided by this invention employs a pair of tangentially excitation permanent magnets with opposite magnetization directions on the stator armature teeth. This excitation structure has a magnetic focusing effect, resulting in stronger excitation capability and significantly improved torque density. Radial excitation permanent magnets are provided on the stator auxiliary teeth, causing the permanent magnets to be unevenly distributed on the stator side. This generates multiple working permanent magnet excitation magnetomotive force harmonics, which can be synergistically utilized to participate in electromechanical energy conversion, further improving the utilization rate of permanent magnets and the motor's torque density and power factor. Simultaneously, this invention utilizes permanent magnets for all excitation, resulting in strong excitation capability and minimal space occupation in the armature windings. This effectively suppresses leakage flux, significantly reducing the risk of permanent magnet leakage flux and irreversible demagnetization under heavy load conditions, which is beneficial for improving torque density.

[0037] 3. Furthermore, the flux-reversing permanent magnet motor provided by this invention employs a pair of tangentially excitation permanent magnets with opposite magnetization directions on the stator armature teeth. This excitation structure has a magnetic focusing effect, resulting in stronger excitation capability and significantly improved torque density. DC excitation windings are wound on the stator auxiliary teeth, causing the permanent magnets to be unevenly distributed on the stator side. This generates multiple working permanent magnet excitation magnetomotive force harmonics, which can be synergistically utilized to participate in electromechanical energy conversion, further improving the utilization rate of permanent magnets and the motor torque density and power factor.

[0038] 4. Further, the flux-reversing permanent magnet motor provided by the present invention includes an excitation unit comprising: a first radially magnetized permanent magnet, a second radially magnetized permanent magnet, and a third radially magnetized permanent magnet attached to the inner surface of the corresponding stator armature tooth, and a fourth radially magnetized permanent magnet attached to the inner surface of the corresponding stator auxiliary tooth; the first radially magnetized permanent magnet and the third radially magnetized permanent magnet have the same width, but different width from the second radially magnetized permanent magnet; the arrangement of multiple permanent magnets with different widths can generate multiple permanent magnet excitation magnetomotive force working harmonics, which is beneficial to improving torque density. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the structure of the flux-reversing permanent magnet motor provided in Embodiment 1 of the present invention;

[0040] Figure 2 This is a schematic diagram of the structure of a conventional flux-reversing permanent magnet motor provided in Embodiment 1 of the present invention;

[0041] Figure 3 The following are the equivalent permanent magnet magnetomotive force (PMMF) waveforms of the conventional flux-reverse permanent magnet motor and the flux-reverse permanent magnet motor of Embodiment 1 of the present invention after stator tooth modulation, and their FFT decomposition results; wherein, (a) is the equivalent permanent magnet PMMF waveform of the conventional flux-reverse permanent magnet motor and the flux-reverse permanent magnet motor of Embodiment 1 of the present invention after stator tooth modulation; (b) is the result of FFT decomposition of the equivalent permanent magnet PMMF waveforms of the conventional flux-reverse permanent magnet motor and the flux-reverse permanent magnet motor of Embodiment 1 of the present invention after stator tooth modulation;

[0042] Figure 4 The following is a waveform diagram of the unloaded air gap magnetic flux density and its FFT decomposition result provided in Embodiment 1 of the present invention; wherein, (a) is the waveform diagram of the unloaded air gap magnetic flux density; and (b) is the result of the unloaded air gap magnetic flux density waveform diagram after FFT decomposition.

[0043] Figure 5 The no-load back EMF waveform diagrams of the flux-reversing permanent magnet motor and the conventional flux-reversing permanent magnet motor provided in Embodiment 1 of the present invention are shown.

[0044] Figure 6 This is a schematic diagram of the structure of the flux-reversing permanent magnet motor provided in Embodiment 2 of the present invention;

[0045] Figure 7 This is a schematic diagram of the structure of the flux-reversing permanent magnet motor provided in Embodiment 3 of the present invention. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0047] To achieve the above objectives, in a first aspect, the present invention provides a flux-reversing permanent magnet motor, comprising: a rotor, a stator, an armature winding, and a non-magnetic shaft;

[0048] The rotor includes rotor teeth and rotor yoke. The rotor yoke is fixed on a non-magnetic shaft, and the rotor teeth are evenly arranged along the circumference of the rotor yoke.

[0049] The stator and rotor are coaxially mounted, and there is an air gap between the stator and rotor teeth;

[0050] The stator includes stator armature teeth and stator auxiliary teeth that are staggered along the circumferential direction of the stator; stator slots are provided between adjacent stator armature teeth and stator auxiliary teeth; the number of stator armature teeth and stator auxiliary teeth is the same, denoted as N; the tooth surface width of the stator armature teeth is greater than the tooth surface width of the stator auxiliary teeth.

[0051] N excitation units are arranged on the inner surface of the stator along the circumferential direction; the N excitation units correspond one-to-one with N pairs of adjacent stator armature teeth and stator auxiliary teeth; each excitation unit includes multiple permanent magnets, and each excitation unit has multiple magnetic poles of different widths; the inner surface is the side closest to the air gap.

[0052] The armature winding is wound around the stator armature teeth;

[0053] The armature winding magnetomotive force contains |Z| pole pairs. r ±P m / 2| of the subharmonics;

[0054] The number of stator slots, the number of armature winding pole pairs, and the number of rotor teeth satisfy the following:

[0055]

[0056] Among them, P a Z represents the number of pole pairs in the armature winding. r P is the number of rotor teeth; m Z is the number of pole pairs of the fundamental magnetomotive force of the permanent magnet, and its value is equal to Z. s Z s GCD(Z) represents the number of stator slots. s ,P a ) represents the least common divisor of the number of stator slots and the number of armature winding pole pairs; k is an integer greater than or equal to 1.

[0057] It should be noted that there are multiple ways to implement the above excitation unit, and no specific method is specified here.

[0058] In one alternative embodiment, the excitation unit includes: a tangentially magnetized permanent magnet group and a radially magnetized permanent magnet; the tangentially magnetized permanent magnet group includes: a first tangentially magnetized permanent magnet and a second tangentially magnetized permanent magnet with opposite magnetization directions;

[0059] The first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet are embedded in the corresponding stator armature tooth surface and are symmetrical about the central axis of the stator armature tooth; the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet are the same; the circumferential distance between the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet along the inner surface of the stator is greater than 1 / 2 of the tooth surface width of the corresponding stator armature tooth;

[0060] Radial magnetized permanent magnets are attached to the inner surface of the corresponding stator auxiliary teeth.

[0061] It should be noted that, based on the above optional implementation method one, the thickness of the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet can be the same as or different from the thickness of the radially magnetized permanent magnet; preferably, further, the thickness of the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet is smaller than the thickness of the radially magnetized permanent magnet, which can give full play to the magnetic focusing effect of the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet, improve the utilization rate of permanent magnets, and at the same time increase the stator permeability constant term, which is beneficial to the torque density improvement.

[0062] Preferably, based on the above optional embodiment one, when the excitation directions of the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet both point to the central axis of the corresponding stator armature tooth, the magnetization direction of the radially magnetized permanent magnet points in the direction away from the air gap along the motor radial direction; when the excitation directions of the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet both point away from the central axis, the magnetization direction of the radially magnetized permanent magnet points in the direction towards the air gap along the motor radial direction.

[0063] In an optional second embodiment, the excitation unit includes: a tangentially magnetized permanent magnet group and a DC excitation winding; the tangentially magnetized permanent magnet group includes: a first tangentially magnetized permanent magnet and a second tangentially magnetized permanent magnet with opposite magnetization directions;

[0064] The first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet are embedded in the corresponding stator armature tooth surface and are symmetrical about the central axis of the stator armature tooth; the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet are the same; the circumferential distance between the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet along the inner surface of the stator is greater than 1 / 2 of the tooth surface width of the corresponding stator armature tooth;

[0065] The DC excitation winding is wound around the corresponding stator auxiliary teeth.

[0066] Preferably, based on the above optional embodiment two, when the magnetization directions of the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet both point to the central axis of the corresponding stator armature tooth, the excitation direction of the DC excitation winding points radially away from the air gap; when the magnetization directions of the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet both point away from the central axis, the excitation direction of the DC excitation winding points radially towards the air gap.

[0067] In one optional embodiment three, the excitation unit includes: a first radially magnetized permanent magnet, a second radially magnetized permanent magnet, a third radially magnetized permanent magnet, and a fourth radially magnetized permanent magnet; the first radially magnetized permanent magnet, the second radially magnetized permanent magnet, and the third radially magnetized permanent magnet are sequentially attached to the inner surface of the corresponding stator armature tooth, and the fourth radially magnetized permanent magnet is attached to the inner surface of the corresponding stator auxiliary tooth;

[0068] The first and third radially magnetized permanent magnets have the same width, but their widths differ from those of the second radially magnetized permanent magnet.

[0069] Preferably, based on the above optional embodiment three, the first radially magnetized permanent magnet has the same magnetization direction as the third and fourth radially magnetized permanent magnets, and the magnetization direction is opposite to that of the second radially magnetized permanent magnet. The first radially magnetized permanent magnet can be directed radially away from the air gap or radially towards the air gap; this is not limited here.

[0070] It should be noted that, although all three implementation methods of the excitation unit have multiple magnetic poles of varying widths, there is space competition between the AC armature winding and the DC excitation winding in implementation method two. To achieve a better magnetization effect, the average torque will inevitably be lost. Compared to implementation method two, implementation methods one and three have the advantage of being entirely excited by permanent magnets, resulting in strong excitation capability and occupying less armature winding space, which is beneficial for improving torque density. In implementation method three, all permanent magnets are attached to the stator tooth surface without spacing between adjacent permanent magnets, leading to problems such as large permanent magnet leakage and low utilization rate. Furthermore, surface-mounted permanent magnets are prone to irreversible demagnetization under heavy load conditions, seriously affecting the service life of the motor. In contrast, in implementation methods one and two, there is spacing between adjacent permanent magnets, eliminating the above-mentioned problems. Therefore, implementation method one has the best performance and is the preferred solution of this invention.

[0071] It should be noted that the armature winding can be a single-layer winding or a double-layer winding; this is not limited here, but a single-layer winding is preferred because it produces richer harmonics. The armature winding can be three-phase or multi-phase; this is not limited here, but three-phase is preferred.

[0072] In one alternative embodiment, the stator and rotor are coaxially mounted as follows: the stator is mounted outside the rotor or the stator is mounted inside the rotor.

[0073] In one alternative embodiment, the structure of the flux-reversing permanent magnet motor is a rotary motor structure, a linear motor structure, or an axial flux motor structure.

[0074] It should be noted that the stator core and rotor core in this invention are both made of magnetically conductive materials. Preferably, in an optional embodiment, they are made of magnetically conductive materials such as silicon steel sheets.

[0075] It should be noted that the permanent magnet in this invention is a permanent magnet material, preferably, in an optional embodiment, a permanent magnet material such as neodymium iron boron, samarium cobalt, or ferrite.

[0076] To further illustrate the flux-reversing permanent magnet motor provided in the first aspect of the present invention, the following detailed description is provided in conjunction with specific embodiments:

[0077] Example 1

[0078] This embodiment provides a flux-reversing permanent magnet motor with Z stator slots. s The number of armature winding pole pairs P is 12. a The number of permanent magnet pole pairs Z is 5. s The number of rotor teeth is 12, Z. r The value is 17; the magnetomotive force of the permanent magnet includes 6 pairs of pole harmonics, 12 pairs of pole harmonics, and multiples of 6 harmonics.

[0079] The excitation unit in this embodiment includes: a tangentially magnetized permanent magnet group and a radially magnetized permanent magnet; the tangentially magnetized permanent magnet group includes: a first tangentially magnetized permanent magnet and a second tangentially magnetized permanent magnet with opposite magnetization directions;

[0080] The first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet are embedded in the corresponding stator armature tooth surface and are symmetrical about the central axis of the stator armature tooth; the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet are the same; the circumferential distance between the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet along the inner surface of the stator is greater than 1 / 2 of the width of the stator armature tooth surface;

[0081] Radial magnetized permanent magnets are attached to the inner surface of the corresponding stator auxiliary teeth.

[0082] like Figure 1As shown, the flux-reversing permanent magnet motor of this embodiment includes a stator, a rotor, an armature winding, and a non-magnetic shaft.

[0083] The rotor includes rotor teeth and rotor yoke. The rotor yoke is fixed on a non-magnetic shaft. The rotor teeth are evenly arranged around the rotor yoke. The stator is located outside the rotor teeth and there is an air gap between the stator and the rotor teeth.

[0084] The stator comprises a stator yoke, stator armature teeth, stator auxiliary teeth, and permanent magnets. It can be considered as a combination of multiple stator units. Each stator unit includes one stator armature tooth, one stator auxiliary tooth, a pair of tangentially excitation permanent magnets with opposite magnetization directions, and a radially excitation permanent magnet. The pair of tangentially excitation permanent magnets with opposite magnetization directions are symmetrical about the axis of the stator armature tooth and are inserted on both sides of the stator armature tooth core. The stator armature tooth is split into two ferromagnetic poles of unequal width. A radially excitation permanent magnet is attached to the surface of the stator auxiliary tooth. The three permanent magnets are unevenly distributed along the inner side of the stator, which can generate multiple permanent magnet excitation magnetomotive force harmonics.

[0085] The armature winding is wound around the stator armature teeth. The rotor has neither permanent magnets nor windings. Placing the permanent magnets, armature windings, and excitation windings on the stator facilitates heat dissipation for the permanent magnets and windings. In this embodiment, the armature winding is a three-phase armature winding.

[0086] In this embodiment, when the excitation directions of the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet both point to the central axis of the corresponding stator armature tooth, the magnetization direction of the radially magnetized permanent magnet points in the direction away from the air gap along the radial direction of the motor.

[0087] Figure 2 It is a traditional flux-reversing permanent magnet motor. Figure 3 Figure 1 shows the equivalent permanent magnet magnetomotive force (PMMF) waveforms of the conventional flux-reversing permanent magnet motor and the PMF of this embodiment after stator tooth modulation, along with their FFT decomposition results. Figure 2 shows the equivalent PMMF waveforms of the conventional flux-reversing permanent magnet motor and the PMF of this embodiment after stator tooth modulation; Figure 3 shows the FFT decomposition results of the equivalent PMMF waveforms of the conventional flux-reversing permanent magnet motor and the PMF of this embodiment after stator tooth modulation. Figure 1 As can be seen from this, in a traditional flux-reversing permanent magnet motor, the permanent magnet magnetomotive force only has 12 pole pairs and their multiples of harmonics, because the number of permanent magnet pole pairs P e =12. In the flux-reversing permanent magnet motor of this embodiment, due to the uneven distribution of permanent magnets and different excitation directions, the permanent magnet magnetomotive force not only has 12 pairs of poles, but also 6 pairs of poles and 6 odd multiples of pole pairs (e.g., 18 pairs of poles) of harmonics, but the amplitude loss of the 12 pairs of permanent magnet magnetomotive force is obvious.

[0088] After modulation by the rotor teeth, the unloaded air gap magnetic flux density waveform can be obtained, specifically, as follows: Figure 4 The figures show the unloaded air gap magnetic flux density waveform and its FFT decomposition result; Figure (a) shows the unloaded air gap magnetic flux density waveform; Figure (b) shows the result of the unloaded air gap magnetic flux density waveform after FFT decomposition. Due to the number of rotor teeth Z... r =17, so in a conventional flux-reversing permanent magnet motor, the number of air gap magnetic flux density operations is |12-17|=5 times and |12×2-17|=7 times. In the flux-reversing permanent magnet motor of this embodiment, the number of air gap magnetic flux density operations is not only |12-17|=5 times and |12×2-17|=7 times, but also |6-17|=11 times, |6×3-17|=1 time and |6×5-17|=13 times.

[0089] It should be noted that the 1st, 5th, and 7th air gap magnetic flux density, modulated by the rotor teeth, are working magnetic flux density harmonics, contributing both back electromotive force and torque. Other air gap magnetic flux density harmonics not modulated by the rotor teeth, i.e., those with frequencies equal to the permanent magnet magnetomotive force, are non-working magnetic flux density harmonics, such as the 6th, 12th, and their multiples. Because they are not modulated by the rotor teeth, these magnetic flux density harmonics are stationary and cannot induce back electromotive force in equally stationary windings, thus failing to generate torque. Therefore, these magnetic flux density harmonics are non-working magnetic flux density harmonics.

[0090] The armature winding method used in this embodiment is the same as that of the conventional flux-reversing motor, but the coil span is different, thus changing the winding coefficients of each armature harmonic, as listed in Table 1. In the conventional flux-reversing permanent magnet motor winding, the 5th and 7th operating magnetic flux densities are tooth harmonics, both of which can induce positive no-load back EMF in the winding and are the main operating harmonics. In this embodiment, the flux-reversing permanent magnet motor increases the coil span, improves the winding coefficients of lower-order armature harmonics, and reduces the winding coefficients of higher-order armature harmonics. The 1st, 5th, 7th, 11th, and 13th are the main operating harmonics, of which the 1st, 5th, and 7th contribute positive no-load back EMFs, while the 11th and 13th contribute negative no-load back EMFs.

[0091] Table 1 Comparison of Harmonic No-Load Back EMF between Conventional Flux Reverse Permanent Magnet Motor and This Embodiment

[0092]

[0093] Comparing the harmonic no-load back EMF contributions of the two flux-reversing permanent magnet motors, it can be seen that due to the loss of the 12-pole permanent magnet magnetomotive force in this embodiment, the contributions of the 5th and 7th harmonics are reduced. However, thanks to the introduction of the lower-order 1st operating harmonic, the no-load back EMF contribution is significantly improved. The no-load back EMF waveforms of the two flux-reversing permanent magnet motors are as follows: Figure 5As shown in the table, the fundamental amplitude of the no-load back EMF of the flux-reversing permanent magnet motor of this invention is 23% higher than that of the conventional flux-reversing permanent magnet motor. Table 2 compares other performance characteristics of the conventional flux-reversing permanent magnet motor and the flux-reversing permanent magnet motor of this invention. It can be found that the present invention has higher torque density, higher efficiency, and higher power factor.

[0094] Table 2 Performance Comparison between Conventional Flux Reverse Permanent Magnet Motor and the Embodiment Here

[0095]

[0096]

[0097] Example 2

[0098] This embodiment is similar to Embodiment 1, except that the excitation unit includes: a tangentially magnetized permanent magnet group and a DC excitation winding; the tangentially magnetized permanent magnet group includes: a first tangentially magnetized permanent magnet and a second tangentially magnetized permanent magnet with opposite magnetization directions;

[0099] The first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet are embedded in the corresponding stator armature tooth surface and are symmetrical about the central axis of the stator armature tooth; the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet are the same; the circumferential distance between the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet along the inner surface of the stator is greater than 1 / 2 of the tooth surface width of the corresponding stator armature tooth;

[0100] The DC excitation winding is wound around the corresponding stator auxiliary teeth.

[0101] In this embodiment, the flux-reversing permanent magnet motor is as follows: Figure 6 As shown.

[0102] In this embodiment, when the magnetization directions of the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet both point to the central axis of the corresponding stator armature tooth, the excitation direction of the DC excitation winding points radially away from the air gap.

[0103] The relevant technical solutions and analyses are the same as in Example 1, and will not be repeated here.

[0104] Example 3

[0105] This embodiment is similar to Embodiment 1, except that the excitation unit includes: a first radially magnetized permanent magnet, a second radially magnetized permanent magnet, a third radially magnetized permanent magnet, and a fourth radially magnetized permanent magnet; the first radially magnetized permanent magnet, the second radially magnetized permanent magnet, and the third radially magnetized permanent magnet are sequentially attached to the inner surface of the corresponding stator armature tooth, and the fourth radially magnetized permanent magnet is attached to the inner surface of the corresponding stator auxiliary tooth;

[0106] The first and third radially magnetized permanent magnets have the same width, but their widths differ from those of the second radially magnetized permanent magnet.

[0107] In this embodiment, the flux-reversing permanent magnet motor is as follows: Figure 7 As shown.

[0108] In this embodiment, the first radially magnetized permanent magnet and the third radially magnetized permanent magnet have the same magnetization direction, and the magnetization direction is opposite to that of the second radially magnetized permanent magnet.

[0109] The fourth radially magnetized permanent magnet has the same magnetization direction as the radially magnetized permanent magnet attached to the inner surface of the adjacent stator armature tooth.

[0110] The relevant technical solutions and analyses are the same as in Example 1, and will not be repeated here.

[0111] In summary, the flux-reversing permanent magnet motor of this invention has a higher torque density. Compared with conventional flux-reversing motors, the amount of permanent magnets, stator core, windings, and rotor in this invention are the same; therefore, the cost is basically the same for the same motor volume. However, within the same motor volume, this invention can significantly improve torque and power. Therefore, if the same power output is maintained, the flux-reversing motor of this invention is smaller, lighter, and less expensive.

[0112] The flux-reversing permanent magnet motor of this invention has a higher power factor. The capacity of the motor controller depends on the power factor. For the same power output, a higher motor power factor results in a smaller controller capacity and lower controller cost. Therefore, the flux-reversing permanent magnet motor of this invention can reduce system controller costs.

[0113] The flux-reversing permanent magnet motor of this invention has higher efficiency. With the same input power, higher efficiency results in higher output power, making it more energy-efficient and environmentally friendly.

[0114] This invention is a stator permanent magnet motor, in which the permanent magnet, armature winding, and excitation winding are all located on the stator, which is beneficial for heat dissipation of the permanent magnet and winding. The rotor is the same as the salient pole rotor of a switched reluctance motor, with a simple, robust, and highly reliable structure.

[0115] In a second aspect, the present invention provides an electric motor, comprising: the flux-reversing permanent magnet motor provided in the first aspect of the present invention.

[0116] The relevant technical solutions are the same as those provided in the first aspect of this invention for the flux-reversing permanent magnet motor, and will not be described in detail here.

[0117] Thirdly, the present invention provides a generator, comprising: the flux-reversing permanent magnet motor provided in the first aspect of the present invention.

[0118] The relevant technical solutions are the same as those provided in the first aspect of this invention for the flux-reversing permanent magnet motor, and will not be described in detail here.

[0119] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements 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 flux-reversing permanent magnet motor, characterized in that, include: Rotor, stator, armature windings, and non-magnetic shaft; The rotor includes rotor teeth and a rotor yoke. The rotor yoke is fixed on the non-magnetic shaft, and the rotor teeth are evenly arranged circumferentially along the rotor yoke. The stator and the rotor are coaxially mounted, and there is an air gap between the stator and the rotor teeth; The stator includes stator armature teeth and stator auxiliary teeth that are staggered along the circumferential direction of the stator; stator slots are provided between adjacent stator armature teeth and stator auxiliary teeth; the number of stator armature teeth and stator auxiliary teeth is the same, denoted as N; the tooth surface width of the stator armature teeth is greater than the tooth surface width of the stator auxiliary teeth. The inner surface of the stator is provided with N excitation units along the circumferential direction; the N excitation units correspond one-to-one with N pairs of adjacent stator armature teeth and stator auxiliary teeth; each excitation unit includes multiple permanent magnets, and each excitation unit has multiple magnetic poles of different widths; the inner surface is the side closest to the air gap. The armature winding is wound around the stator armature teeth; The armature winding magnetomotive force contains |Z| pole pairs. r ±P m / 2| of the subharmonics; The number of stator slots, the number of armature winding pole pairs, and the number of rotor teeth satisfy the following: Among them, P a Z represents the number of pole pairs in the armature winding. r P is the number of rotor teeth; m Z is the number of pole pairs of the fundamental magnetomotive force of the permanent magnet, and its value is equal to Z. s Z s GCD(Z) represents the number of stator slots. s ,P a ) represents the least common divisor of the number of stator slots and the number of armature winding pole pairs; k is an integer greater than or equal to 1.

2. The flux-reversing permanent magnet motor according to claim 1, characterized in that, The excitation unit includes: a tangentially magnetized permanent magnet group and a radially magnetized permanent magnet; the tangentially magnetized permanent magnet group includes: a first tangentially magnetized permanent magnet and a second tangentially magnetized permanent magnet with opposite magnetization directions; The first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet are embedded in the corresponding stator armature tooth surface and are symmetrical about the central axis of the stator armature tooth; the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet are the same; the circumferential distance between the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet along the inner surface of the stator is greater than 1 / 2 of the tooth surface width of the corresponding stator armature tooth; The radially magnetized permanent magnet is attached to the inner surface of the corresponding stator auxiliary tooth.

3. The flux-reversing permanent magnet motor according to claim 2, characterized in that, The thicknesses of the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet are different from the thickness of the radially magnetized permanent magnet; When the excitation directions of the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet both point to the central axis of the corresponding stator armature tooth, the magnetization direction of the radially magnetized permanent magnet points in the direction away from the air gap along the radial direction of the motor. When the excitation directions of the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet are both away from the central axis, the magnetization direction of the radially magnetized permanent magnet points radially toward the air gap.

4. The flux-reversing permanent magnet motor according to claim 1, characterized in that, The excitation unit includes: a tangentially magnetized permanent magnet group and a DC excitation winding; the tangentially magnetized permanent magnet group includes: a first tangentially magnetized permanent magnet and a second tangentially magnetized permanent magnet with opposite magnetization directions; The first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet are embedded in the corresponding stator armature tooth surface and are symmetrical about the central axis of the stator armature tooth; the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet are the same; the circumferential distance between the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet along the inner surface of the stator is greater than 1 / 2 of the tooth surface width of the corresponding stator armature tooth; The DC excitation winding is wound around the corresponding stator auxiliary teeth.

5. The flux-reversing permanent magnet motor according to claim 4, characterized in that, When the magnetization directions of the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet both point to the central axis of the corresponding stator armature tooth, the excitation direction of the DC excitation winding points radially away from the air gap. When the magnetization directions of the first tangentially magnetized permanent magnet and the second tangentially magnetized permanent magnet are both away from the central axis, the excitation direction of the DC excitation winding points radially toward the air gap.

6. The flux-reversing permanent magnet motor according to claim 1, characterized in that, The excitation unit includes: a first radially magnetized permanent magnet, a second radially magnetized permanent magnet, a third radially magnetized permanent magnet, and a fourth radially magnetized permanent magnet; the first radially magnetized permanent magnet, the second radially magnetized permanent magnet, and the third radially magnetized permanent magnet are sequentially attached to the inner surface of the corresponding stator armature tooth, and the fourth radially magnetized permanent magnet is attached to the inner surface of the corresponding stator auxiliary tooth. The first radially magnetized permanent magnet and the third radially magnetized permanent magnet have the same width, but the width of the third radially magnetized permanent magnet is different from that of the second radially magnetized permanent magnet.

7. The flux-reversing permanent magnet motor according to claim 6, characterized in that, The first radially magnetized permanent magnet, the third radially magnetized permanent magnet, and the fourth radially magnetized permanent magnet have the same magnetization direction, which is opposite to the magnetization direction of the second radially magnetized permanent magnet.

8. The flux-reversing permanent magnet motor according to any one of claims 1-7, characterized in that, The stator and the rotor are coaxially mounted as follows: the stator is mounted outside the rotor, or the stator is mounted inside the rotor.

9. An electric motor, characterized in that, include: The flux-reversing permanent magnet motor according to any one of claims 1-8.

10. A generator, characterized in that, include: The flux-reversing permanent magnet motor according to any one of claims 1-8.

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