阅读说明：本技术 一种交直轴磁阻可控式永磁无刷电机 (Quadrature-direct axis magnetic resistance controllable permanent magnet brushless motor ) 是由 朱孝勇 刘玫 王腾光 周雪 吴文叶 于 2019-11-26 设计创作，主要内容包括：本发明公开电机制造领域中的一种交直轴磁阻可控式永磁无刷电机,最外部是定子铁心,转子铁心内部沿圆周方向均匀嵌有8组混合永磁体,每组混合永磁体均由2块钕铁硼永磁体和6块铝镍钴永磁体构成,每块钕铁硼永磁体上嵌有3块铝镍钴永磁体,每组混合永磁体相对于直轴对称布置,每组混合永磁体中的2块钕铁硼永磁体之间形成导磁桥,相邻的两组混合永磁体相对于交轴对称布置,每块钕铁硼永磁体和铝镍钴永磁体均是圆弧形的结构,每块钕铁硼永磁体在靠近交轴的一端上嵌3块铝镍钴永磁体,3块铝镍钴永磁体沿径向每层各1块；在相邻的两组混合永磁体之间的转子铁心上设有关于交轴对称分布的内外多层磁障,通过两类永磁体共同作用产生可变永磁转矩。(The invention discloses a quadrature-direct axis reluctance controllable permanent magnet brushless motor in the field of motor manufacturing, wherein the outermost part is a stator core, 8 groups of mixed permanent magnets are uniformly embedded in a rotor core along the circumferential direction, each group of mixed permanent magnets is composed of 2 neodymium iron boron permanent magnets and 6 aluminum nickel cobalt permanent magnets, each neodymium iron boron permanent magnet is embedded with 3 aluminum nickel cobalt permanent magnets, each group of mixed permanent magnets is symmetrically arranged relative to a direct axis, a magnetic conduction bridge is formed between 2 neodymium iron boron permanent magnets in each group of mixed permanent magnets, two adjacent groups of mixed permanent magnets are symmetrically arranged relative to a quadrature axis, each neodymium iron boron permanent magnet and each aluminum nickel cobalt permanent magnet are of an arc-shaped structure, one end of each neodymium iron boron permanent magnet close to the quadrature axis is embedded with 3 aluminum nickel cobalt permanent magnets, and each layer of the 3 aluminum nickel cobalt permanent magnets is; and an inner layer of magnetic barriers and an outer layer of magnetic barriers which are symmetrically distributed about a quadrature axis are arranged on a rotor iron core between two adjacent groups of mixed permanent magnets, and variable permanent magnet torque is generated through the combined action of the two types of permanent magnets.)

1. The utility model provides a controllable formula permanent magnet brushless motor of quadrature-direct axis magnetic resistance, it is outermost stator core (1), and rotor core (3) are located inside stator core (1), characterized by: 8 groups of mixed permanent magnets are uniformly embedded in the rotor iron core (3) along the circumferential direction, each group of mixed permanent magnets is composed of 2 neodymium iron boron permanent magnets (4) and 6 aluminum nickel cobalt permanent magnets (5), each neodymium iron boron permanent magnet (4) is embedded with 3 aluminum nickel cobalt permanent magnets (5), each group of mixed permanent magnets is symmetrically arranged relative to a straight axis, 2 neodymium iron boron permanent magnets (4) in each group of mixed permanent magnets are not connected or communicated, a magnetic conduction bridge (9) symmetrical relative to the straight axis is formed between the two groups of adjacent mixed permanent magnets, the two groups of adjacent mixed permanent magnets are symmetrically arranged relative to a quadrature axis, each neodymium iron boron permanent magnet (4) and each aluminum nickel cobalt permanent magnet (5) are both in an arc-shaped structure, and the arc-; each neodymium iron boron permanent magnet (4) is embedded with 3 alnico permanent magnets (5) at one end close to the quadrature axis, the 3 alnico permanent magnets (5) are arranged into three layers along the radial direction, and each layer is provided with 1 block; an inner magnetic barrier and an outer magnetic barrier which are symmetrically distributed about a quadrature axis are arranged on a rotor iron core (3) between two adjacent groups of mixed permanent magnets; the magnetizing directions of 2 neodymium iron boron permanent magnets (4) and 6 aluminum nickel cobalt permanent magnets (5) in the same group of mixed permanent magnets are the same, the magnets are magnetized along the radial directions of the magnets, and the magnetizing directions of the neodymium iron boron permanent magnets (4) and the aluminum nickel cobalt permanent magnets (5) in the two adjacent groups of mixed permanent magnets are opposite.

2. The quadrature-direct axis reluctance controllable permanent magnet brushless motor of claim 1, wherein: the multilayer magnetic barriers are magnetic leakage barrier groups (6) located on the outer side of the mixed permanent magnet and fan-shaped like magnetic barriers (7) located on the inner side of the mixed permanent magnet, and the magnetic leakage barrier groups (6) are composed of outer bow-shaped like magnetic barriers and inner fan-shaped magnetic barriers.

3. The quadrature-direct axis reluctance controllable permanent magnet brushless motor of claim 1, wherein: the radial thickness of the outer 2 alnico permanent magnets (5) of the inlayer and the inlayer in 3 alnico permanent magnet (5) is the same with the radian, be embedded in neodymium iron boron permanent magnet (4) completely, and the tip of the 2 alnico permanent magnets (5) of inlayer and inlayer is the parallel and level with the tip of neodymium iron boron permanent magnet (4), the radial thickness and the radian of 1 alnico permanent magnet (5) in intermediate level are greater than the radial thickness and the radian of the 2 alnico permanent magnets (5) of inlayer and inlayer, and its tip stretches out neodymium iron boron permanent magnet (4) and protrudes to the quadrature axis side.

4. The quadrature-direct axis reluctance controllable permanent magnet brushless motor of claim 1, wherein: each Nd-Fe-B permanent magnet (4) has the same center O with 3 Al-Ni-Co permanent magnets (5) embedded on the Nd-Fe-B permanent magnet₁Two centers O of 2 neodymium iron boron permanent magnets (4) in each group of mixed permanent magnets₁Is symmetrical relative to a straight shaft, and the centers O of the Nd-Fe-B permanent magnet (4) and the Al-Ni-Co permanent magnet (5)₁The radial distance from the center O of the rotor core (3) is 1.15R₄，R₄Is the inner radius of the rotor core (3).

5. According to claim 1The alternating-direct axis magnetic resistance controllable permanent magnet brushless motor is characterized in that: the radial thickness of the neodymium iron boron permanent magnet (4) is h₁The radial thickness of the alnico permanent magnet (5) positioned in the middle layer is h₂₁Radian of theta₂₁Satisfy h₂₁＝h₁A/3; the inner radius of the alnico permanent magnet (5) at the inner layer is equal to the inner radius of the neodymium iron boron permanent magnet (4); radian theta of inner alnico permanent magnet 5₂₂＝0.5θ₂₁Radial thickness of h₂₂Satisfy h₂₂＝0.5h₂₁(ii) a The radian and the radial thickness of the outer alnico permanent magnet (5) are respectively the same as those of the inner alnico permanent magnet (5).

6. The quadrature-direct axis reluctance controllable permanent magnet brushless motor of claim 2, wherein: a shallow arc-shaped groove (8) is arranged on the outer wall of the rotor core (3) corresponding to the radial position of each leakage magnetic barrier group (6), the shallow arc-shaped grooves (8) are symmetrically arranged relative to the intersecting axis, the arc-shaped opening of each shallow arc-shaped groove (8) faces towards the outside, and the arc-shaped center O is positioned at the center₂On the quadrature axis, the radius is r₈The middle section of the outer side of the similar arc magnetic barrier in the magnetic leakage magnetic barrier group (6) is arc-shaped, and the center is O₂Radius r₆₁The radial distance between the outer bow-like magnetic barrier and the inner fan-shaped magnetic barrier in the leakage magnetic barrier group (6) is h₃Satisfy r₆₁-r₈＝2h₃(ii) a The outer side surface of the fan-shaped magnetic barrier of the inner layer in the magnetic leakage magnetic barrier group (6) is arc-shaped, the opening of the arc is inward, and the center O of the arc is arc-shaped₃On the intersecting axis, the radius of the circular arc is r₆₂Satisfy r₆₂＝0.5r₆₁The inner side surface of the outer-layer similar arch magnetic barrier in the magnetic leakage magnetic barrier group (6) is arc-shaped, and the center is O₃Center O of₃The radial distance from the center O of the rotor core (3) is 1.5R₄Center O of₂The radial distance from the center O of the rotor core (3) is 2.25R₄，R₄Is the inner radius of the rotor core (3).

7. The method of claim 2 wherein the quadrature axis reluctance is controllableFormula permanent magnetism brushless motor, characterized by: the outer side surface of the fan-shaped magnetic barrier (7) is in a circular arc shape, and the center O of the circular arc shape₄On a quadrature axis with a radius r₇₁(ii) a Center O₄The radial distance from the center O of the rotor core (3) is 1.25R₄，R₄Is the inside radius of the rotor core (3); the inner side surfaces of the fan-shaped magnetic barriers (7) are two circular arcs which are symmetrical relative to the intersecting axis, and the centers of the circular arcs are O₅Radius r₇₂And satisfy r₇₁＝1.5r₇₂(ii) a Center O₅And the center O₄Has a tangential distance of 0.5r₇₁。

8. The quadrature-direct axis reluctance controllable permanent magnet brushless motor of claim 1, wherein: the magnetic leakage magnetic barrier group (6) and the fan-shaped magnetic barrier (7) are internally provided with air gaps or embedded with non-magnetic material blocks.

9. The quadrature-direct axis reluctance controllable permanent magnet brushless motor of claim 1, wherein: the stator core (1) is composed of stator slots (11), stator teeth (12) and a stator yoke (13), 36 stator slots (11) are uniformly distributed on the inner wall of the stator yoke (13) along the circumferential direction, the stator teeth (12) are arranged between every two adjacent stator slots (11), and armature windings (2) distributed in a single layer are placed in the stator slots (11).

Technical Field

The invention belongs to the field of motor manufacturing, relates to a permanent magnet brushless motor, is used for driving a hybrid electric vehicle and a pure electric vehicle, and particularly relates to a high-torque permanent magnet brushless motor with controllable alternating-direct axis reluctance.

Background

Hybrid electric vehicles and pure electric vehicles are developing rapidly, and the performance requirements of the vehicle driving motor are gradually improved. The traditional permanent magnet brushless motor is widely applied to a driving system of an electric vehicle due to the advantages of simple structure, high power density, strong reliability and the like. Because the permanent magnet brushless motor adopts single permanent magnets such as neodymium iron boron and the like as excitation sources, the permanent magnet brushless motor has a constant air gap magnetic field and a narrow weak magnetic speed regulation range, and therefore, the permanent magnet brushless motor has the advantages of improving the torque in the driving process of the permanent magnet brushless motor in a controllable manner and widening the speed regulation range of the motor.

The existing reluctance motor generally adopts a multilayer magnetic barrier structure, and the structure can fully utilize reluctance torque generated by the asymmetric characteristic of a rotor magnetic circuit. Although the reluctance motor has the advantages of low manufacturing cost, low loss and the like, the torque density and the speed regulation range of the reluctance motor are difficult to meet the requirements of electric automobiles. The motor disclosed in the chinese patent publication No. CN109450211A is a permanent magnet flux-assisted synchronous reluctance motor formed by disposing permanent magnets in tangential slots in U-shaped slots, and such a motor has problems of non-adjustable torque, narrow motor operating range, and the like, although torque density, efficiency, and the like are improved by using reluctance torque and permanent magnet torque.

In general, effectively adjusting the air gap field of a permanent magnet motor can broaden the speed regulation range of the motor. The permanent magnet memory motor is a magnetic flux controllable permanent magnet motor, adopts permanent magnets with the magnetization levels capable of being memorized, such as alnico, samarium cobalt and the like, and achieves the flexible adjustment of the air gap magnetic field intensity by adjusting the magnetization degree of the permanent magnets on line, thereby achieving the purpose of flux weakening and speed expansion. The document with the Chinese patent number of 200810023409.X provides a magnetic flux memory type stator permanent magnet motor which realizes wide speed regulation by utilizing the mutual matching of a direct current magnetizing winding and an alnico permanent magnet, the motor widens the speed regulation range by applying transient direct current magnetizing current and smaller weak magnetic current, but the motor has lower space utilization rate and lower power density because of the addition of a winding for online regulating the air gap magnetic field intensity. In addition, the permanent magnet adopted by the permanent magnet memory motor has low magnetic energy product, and the permanent magnet working point is easily influenced by the armature winding magnetic field, so that the air gap main flux is not high.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides the alternating-direct axis magnetic resistance controllable permanent magnet brushless motor which can reasonably and effectively adjust an air gap magnetic field, has high torque, wide speed regulation and high efficiency.

In order to achieve the purpose, the invention adopts the technical scheme that: the outermost part is a stator core, the rotor core is positioned in the stator core, 8 groups of mixed permanent magnets are uniformly embedded in the rotor core along the circumferential direction, each group of mixed permanent magnets is composed of 2 neodymium iron boron permanent magnets and 6 aluminum nickel cobalt permanent magnets, each neodymium iron boron permanent magnet is embedded with 3 aluminum nickel cobalt permanent magnets, each group of mixed permanent magnets is symmetrically arranged relative to a straight axis, 2 neodymium iron boron permanent magnets in each group of mixed permanent magnets are not connected or communicated, a magnetic conduction bridge symmetrical relative to the straight axis is formed between the two adjacent groups of mixed permanent magnets, the two adjacent groups of mixed permanent magnets are symmetrically arranged relative to an intersecting axis, each neodymium iron boron permanent magnet and each aluminum nickel cobalt permanent magnet are both in an arc-shaped structure; each neodymium iron boron permanent magnet is embedded with 3 alnico permanent magnets at one end close to the quadrature axis, the 3 alnico permanent magnets are radially arranged into three layers, and each layer is provided with 1 block; an inner magnetic barrier and an outer magnetic barrier which are symmetrically distributed about a quadrature axis are arranged on a rotor iron core between two adjacent groups of mixed permanent magnets; the magnetizing directions of the 2 neodymium iron boron permanent magnets and the 6 aluminum nickel cobalt permanent magnets in the same group of mixed permanent magnets are the same, the two permanent magnets are magnetized along the respective radial directions, and the magnetizing directions of the neodymium iron boron permanent magnets and the aluminum nickel cobalt permanent magnets in the two adjacent groups of mixed permanent magnets are opposite.

The multilayer magnetic barriers are magnetic leakage magnetic barrier groups positioned on the outer side of the mixed permanent magnet and fan-shaped like magnetic barriers positioned on the inner side of the mixed permanent magnet, and each magnetic leakage magnetic barrier group is composed of an outer bow-shaped like magnetic barrier and an inner fan-shaped magnetic barrier.

After the technical scheme is adopted, the invention has the beneficial effects that:

1. the invention combines the corresponding control strategy to realize the effective regulation of the quadrature-direct axis component in the magnetic leakage magnetic circuit. Two groups of special mixed permanent magnets of the adjacent structures on the direct axis of the rotor increase the direct axis magnetic resistance, so that the motor has the initial magnetic resistance characteristic that the direct axis magnetic resistance is greater than the quadrature axis magnetic resistance. The magnetic flux generated by the mixed permanent magnet passes through the rotor core between the similar bow-shaped magnetic barrier and the air gap to reach the permanent magnet on the adjacent side to form a first magnetic leakage path; meanwhile, the permanent magnet which passes through the rotor core between the similar arc magnetic barrier and the fan-shaped magnetic barrier and reaches the adjacent side forms a second magnetic leakage path.

When armature current I_qWhen the magnetic flux leakage path is 0A, the saturation degree of the q-axis component is low, and the direct-axis magnetic resistance R is_dGreater than quadrature axis reluctance R_qThe d-axis leakage flux is large; when armature current I_qWhen increasing to the set value, R_d＝R_qThe leakage flux is reduced with the armature current I_qThe saturation degree of the q-axis component in the leakage magnetic path is increased, the quadrature-direct axis magnetic resistance is increased, but the change rates of the quadrature-axis magnetic resistance and the direct-axis magnetic resistance are obviously different, namely the quadrature-axis magnetic resistance increase rate is greater than the direct-axis magnetic resistance increase rate, rho_q＞ρ_dThe leakage magnetic flux is greatly reduced or even eliminated, so that the motor presents R_d＜R_qThe magnetoresistive characteristics of (1).

When weak magnetic current I is added_dAt this time, the d-axis component in the leakage flux path begins to be saturated, and the direct-axis magnetic resistance R_dIncreasing quadrature reluctance R_qDecrease, finally trend towards R_d＞R_qMagnetoresistive steady state. And d-axis magnetizing and demagnetizing pulse current further enhances the saturation degree of a magnetic leakage path by regulating and controlling the magnetization state of the alnico, and ensures the stable magnetic resistance state.

Therefore, the saturation degree of the dq axis component of the leakage magnetic path is controlled by changing the armature current, the controllable quadrature-direct axis magnetic resistance and the variable leakage magnetic flux are realized, the main magnetic flux of the motor is effectively adjusted, the torque of a low-speed operation area is further improved, the speed regulation range of the motor is expanded, and the efficiency of the motor in the high-speed operation area is improved.

2. The invention adopts the high-coercivity neodymium iron boron permanent magnet and the low-coercivity alnico permanent magnet, and reasonably distributes the use amount of the permanent magnets to form the quadrature-direct axis reluctance controllable high-torque permanent magnet brushless motor. The variable permanent magnet torque is generated by the combined action of the two types of permanent magnets. The neodymium iron boron permanent magnet provides constant basic torque, and the motor is guaranteed to have large torque density. The magnetization level of the alnico permanent magnet is adjusted on line through the direct-axis magnetizing and demagnetizing pulse current, the air gap main flux is actively adjusted, and the motor torque is flexibly adjusted. The problem of the effective main flux utilization of the motor is reduced due to the self-leakage flux of the permanent magnet or the interpolar leakage flux when the motor operates is solved, and the high torque density of the motor in the whole operation process is ensured.

3. The arc-shaped mixed permanent magnet group is matched with the multiple layers of magnetic barriers with different shapes, so that double-layer leakage magnetic paths with different widths are formed, and the alternate and direct axis magnetic resistance of the motor is promoted to be different. The armature winding is added with load current, so that the saturation degree of the quadrature-direct axis component in the leakage magnetic path is adjusted, the variation of the quadrature-direct axis magnetic resistance is further controlled, and the trend of the main magnetic circuit is changed. On the basis of the method, d-axis pulse current is added to adjust the alnico magnetization state on line, so that the change of the quadrature-axis and direct-axis magnetic resistance in a magnetic leakage path is further promoted, and the magnetic leakage degree is adjusted. Therefore, the invention can effectively control the magnetic resistance change of the alternating-direct axis, adjust the magnetic flux of the main magnetic field of the air gap, widen the speed adjusting range and improve the output torque, and meet the requirements of the electric automobile on multiple operating conditions.

4. The invention adopts a control mode suitable for different operation conditions to change the magnitude of the magnetic resistance of the quadrature-direct axis, so that the dq axis components in the magnetic leakage path are mutually matched, and the performances of high torque, wide speed regulation and the like of the motor are promoted to be realized. During low-speed heavy-load operation, the alternating-direct axis magnetic resistance is changed by applying larger armature current, and the magnetic resistance state is R_q＞R_dThe saturation degree of the q-axis component in the leakage flux path is greater than that of the d-axis component, so that the air gap flux is increased while the leakage flux is reduced, and the output torque of the motor is improved; in addition, by adding direct-axis magnetizing pulse current, the magnetization level of the alnico permanent magnetic material is improved, and q-axis component saturation and R are further promoted_qAnd the permanent magnet torque and the reluctance torque are increased, so that the motor is promoted to realize high torque density. At a high levelWhen the ship is cruising at high speed, the straight-axis magnetic resistance R is increased by applying smaller weak magnetic current and straight-axis demagnetizing pulse current_dReduce the quadrature axis magnetic resistance R_qAnd the degree of magnetization of the alnico permanent magnet is reduced to exhibit R_q＜R_dThe magnetic resistance state of the motor is that the saturation degree of a q-axis component in a magnetic leakage magnetic circuit is reduced, the saturation degree of a d-axis component in the magnetic leakage magnetic circuit is increased, the magnetic leakage flux is increased, the effective magnetic flux of an air gap is reduced, and the speed regulation range of the motor is widened.

5. The invention realizes the effective regulation of the air gap field of the motor by adopting two modes of 'alternating-direct axis magnetic resistance controllable' and 'permanent magnetic memory material on-line magnetic regulation', so that the motor does not need larger weak magnetic current and larger direct axis demagnetizing pulse current in the running process, and the aims of expanding the running range of the motor by times, effectively reducing the weak magnetic copper consumption, improving the efficiency of the high-speed running area of the motor and outputting high torque can be achieved.

6. The invention discloses a rotor core quadrature axis central line, which is provided with three layers of magnetic barriers with different shapes from the air gap side to the rotating shaft side, wherein in order to promote a mixed permanent magnet to generate rich interpolar leakage flux, a bow-like magnetic barrier with an inward concave outer cambered surface at the first layer and a fan-shaped magnetic barrier with an arc surface at the second layer close to an air gap are designed to jointly form a double-layer magnetic barrier; the third layer of magnetic barrier adopts a fan-shaped structure with an arc surface close to the axis and two concave sides, and aims to inhibit the self-leakage generated by the mixed permanent magnet and form a leakage magnetic circuit by matching with the double-layer magnetic barrier and the mixed permanent magnet.

Drawings

The invention is further described with reference to the following figures and detailed description:

fig. 1 is a schematic view of a radial cross-sectional structure of a quadrature-axis and direct-axis reluctance controllable permanent magnet brushless motor according to the present invention;

FIG. 2 is a schematic diagram of the stator structure of FIG. 1 and a three-phase armature winding layout;

FIG. 3 is an enlarged view of the hybrid permanent magnet of FIG. 1 at the straight axis of the rotor;

FIG. 4 is an enlarged view of the multi-layer magnetic barriers of FIG. 1 at the cross-axis position of the rotor;

FIG. 5 is an enlarged view of the magnetization direction and the quadrature-direct axis of the hybrid permanent magnet on the rotor of FIG. 1;

FIG. 6 is a schematic view of the magnetic circuit of the motor of the present invention;

FIG. 7 is a cross-axis and direct-axis equivalent magnetic circuit diagram of the motor of the present invention;

FIG. 8 is a simplified cross-axis and direct-axis equivalent magnetic circuit diagram of FIG. 7

FIG. 9 is a magnetic flux distribution diagram of the motor of the present invention under low speed and heavy load;

FIG. 10 is a magnetic flux distribution plot for a motor of the present invention during high speed cruise;

FIG. 11 is a graph comparing torque speed performance of the present invention and a conventional interior permanent magnet brushless motor;

in the figure: 1. a stator core; 2. an armature winding; 3. a rotor core; 4. a neodymium iron boron permanent magnet; 5. an alnico permanent magnet; 6. a leakage magnetic barrier group; 7. a fan-like magnetic barrier; 8. a shallow arc groove on the outer side of the rotor; 9. a magnetic conducting bridge; 10. a rotating shaft; 11. a stator slot; 12. stator teeth; 13. a stator yoke.

Detailed Description

Referring to fig. 1, the present invention includes a stator core 1, an armature winding 2, a rotor core 3, and a rotating shaft 10. The outermost part is a stator core 1, a rotor core 3 is positioned inside the stator core 1, and a central slot of the rotor core 3 is used for placing a rotating shaft 10. An air gap is arranged between the inner wall of the stator core 1 and the outer wall of the rotor core 3, and the thickness of the air gap is related to the power grade of the motor, the mixed permanent magnetic material and the processing and assembling processes of the stator core 1 and the rotor core 3. The stator iron core 1 and the rotor iron core 3 are formed by laminating silicon steel sheets with the same thickness, the laminating thickness is 0.35mm, and the laminating coefficient is 0.95. The shaft 10 is made of a non-magnetic conductive material.

Referring to fig. 2, a stator core 1 is formed of stator slots 11, stator teeth 12, and a stator yoke 13. 36 stator slots 11 are uniformly distributed on the inner wall of the stator yoke 13 along the circumferential direction, and a T-shaped stator tooth 12 is arranged between every two adjacent stator slots 11. The stator slot 11 is internally provided with the discharge armature winding 2, and the armature winding 2 adopts a single-layer distribution mode, so that the torque is easier to improve and the field weakening speed regulation range is easier to expand than that of a concentrated winding.

Referring to fig. 1, 3 and 5, in the rotor ironInside the core 3, 8 groups of mixed permanent magnets with 4 pairs of magnetic poles are uniformly embedded along the circumferential direction, each group of mixed permanent magnets is composed of 2 neodymium iron boron permanent magnets 4 and 6 aluminum nickel cobalt permanent magnets 5, each neodymium iron boron permanent magnet 4 is embedded with 3 aluminum nickel cobalt permanent magnets 5, as shown in figure 3, each group of mixed permanent magnets is symmetrically arranged relative to a straight shaft, 2 neodymium iron boron permanent magnets 4 in each group of mixed permanent magnets are not connected or communicated, and therefore the tangential width of l is formed between 2 neodymium iron boron permanent magnets 4 in each group of mixed permanent magnets₁The magnetic bridge 9 is symmetrical relative to the straight axis of the magnetic bridge 9. As shown in fig. 1 and 4, two adjacent sets of hybrid permanent magnets are arranged symmetrically with respect to the intersecting axis. Each neodymium iron boron permanent magnet 4 and each alnico permanent magnet 5 are both arc-shaped structures, and the arc-shaped openings face the inner sides.

On 2 neodymium iron boron permanent magnets 4 of each group of mixed permanent magnet, 3 alnico permanent magnets 5 are embedded on one end (namely one end close to the quadrature axis) far away from the magnetic bridge 9, and the 3 alnico permanent magnets 5 are radially arranged in three layers, 1 each layer. The radial thickness of 2 alnico permanent magnets 5 of skin and inlayer is the same with the radian, is embedded in neodymium iron boron permanent magnet 4 completely, and 2 alnico permanent magnets 5's tip and neodymium iron boron permanent magnet 4's tip parallel and level. While the radial thickness and radian theta of the 1 alnico permanent magnet 5 in the middle layer₂₁The radial thickness and radian of the 2 alnico permanent magnets 5 which are larger than the inner layer and the outer layer are larger than the inner layer, the end parts of the alnico permanent magnets extend out of the neodymium iron boron permanent magnet 4 and protrude towards the quadrature axis side, and the radian of the protruding parts is 0.25 theta₂₁。

Each Nd-Fe-B permanent magnet 4 and 3 Al-Ni-Co permanent magnets 5 embedded on the Nd-Fe-B permanent magnet have the same center O₁Two centers O of 2 Nd-Fe-B permanent magnets 4 in each group of mixed permanent magnets₁Symmetrical with respect to the straight axis, and has a tangential distance of 0.5l from the straight axis₁. Center O of Nd-Fe-B permanent magnet 4 and Al-Ni-Co permanent magnet 5₁A radial distance of 1.15R from the center O of the rotor core 3₄，R₄Is the inside radius of the rotor core 3.

The radial thickness of the Nd-Fe-B permanent magnet 4 is h₁Radian of theta₁Inside radius of R₁. The inner side radius of the alnico permanent magnet 5 positioned at the intermediate layer is R₂Radian of theta₂₁Radial thickness of h₂₁And satisfy h₂₁＝h₁A/3; the inner side radius of the inner layer alnico permanent magnet 5 is equal to the inner side radius of the neodymium iron boron permanent magnet 4, and the inner side radii are R₁Radian of theta₂₂And satisfies the condition theta₂₂＝0.5θ₂₁Radial thickness of h₂₂And satisfy h₂₂＝0.5h₂₁(ii) a The outer side inner radius of the outer layer AlNiCo permanent magnet 5 is R₃The radian and the thickness of the alnico permanent magnet 5 in the inner layer are the same.

Referring to fig. 1, 3 and 4, a rotor core 3 between two adjacent groups of mixed permanent magnets is provided with a plurality of layers of magnetic barriers symmetrically distributed about a quadrature axis, and the magnetic barriers are a leakage magnetic barrier group 6 positioned on the outer side of the mixed permanent magnet and a fan-like magnetic barrier group 7 positioned on the inner side of the mixed permanent magnet, and the leakage magnetic barrier group 6 is composed of an outer layer of the bow-like magnetic barrier and an inner layer of the fan-like magnetic barrier. The unique design can increase the cross-axis magnetic resistance R_qReducing quadrature axis inductance L_qThe quadrature-direct axis magnetic resistance is beneficial to control, and the influence on the direct axis flux linkage is reduced while the quadrature-axis flux linkage is blocked as far as possible. The leakage magnetic barrier group 6 and the fan-shaped magnetic barrier group 7 are embedded with non-magnetic material blocks such as epoxy resin and carbon fiber, and in order to simplify the process and reduce the weight of the motor, air gaps can be directly adopted as the non-magnetic material blocks.

A shallow arc groove 8 is provided on the outer wall of the rotor core 3 corresponding to the radial position of each leakage magnetic barrier group 6, so that 8 shallow arc grooves 8 in total are uniformly distributed on the outer wall of the rotor core 3 in the circumferential direction. The shallow arc grooves 8 are arranged symmetrically with respect to the quadrature axis. The arc opening of the shallow arc groove 8 faces outwards, and the center of the arc is O₂Center O of₂On the quadrature axis, the radius is r₈. The middle section of the outer side of the similar arc magnetic barrier in the magnetic leakage magnetic barrier group 6 is also arc-shaped, and the center is O₂Radius r₆₁. The radial distance between the outer bow-like magnetic barrier and the inner fan-shaped magnetic barrier in the leakage magnetic barrier group 6 is h₃And the radial distance between the shallow arc-shaped groove 8 and the outer bow-shaped magnetic barrier is h₃Twice of, i.e. r₆₁-r₈＝2h₃Satisfies the relation r₆₁＝r₈+2h₃(ii) a The leakage magnetic flux can be shunted and the mechanical strength of the motor can be ensured.

The outer side of the fan-shaped magnetic barrier of the inner layer in the magnetic leakage magnetic barrier group 6 is arc-shaped, the opening of the arc is inward, and the center of the arc is O₃Radius of arc r₆₂Satisfies the relation r₆₂＝0.5r₆₁. The inner side surface of the outer-layer similar-arch magnetic barrier in the magnetic leakage magnetic barrier group 6 is arc-shaped, and the center is O₃The radial distance from the fan-shaped magnetic barrier of the inner layer is h₃。

The outer side surface of the fan-shaped magnetic barrier 7 is arc-shaped, and the center of the arc is O₄Radius r₇₁. The inner side surfaces of the fan-like magnetic barriers 7 are two circular arcs which are symmetrical relative to the cross bearing, and the centers of the circular arcs are O₅Radius r₇₂And satisfies the relation r₇₁＝1.5r₇₂。

The outer diameter of the rotor core 3 is R₅Inner diameter is R₄With center O and center O₂Center of circle O₃Center of circle O₄On the same axis, i.e. the cross axis. Center O₂Center O₃Center O₄The radial distances from the center O are respectively: 2.25R₄、1.5R₄、1.25R₄. Center O₅And the center O₄Has a tangential distance of 0.5r₇₁。

Referring to fig. 5, the magnetizing directions of 2 ndfeb permanent magnets 4 and 6 alnico permanent magnets 5 in the same group of mixed permanent magnets are the same and are all magnetized along their own radial directions, and the magnetizing directions of the ndfeb permanent magnets 4 and the alnico permanent magnets 5 in two adjacent groups of mixed permanent magnets are opposite to each other, forming a pair of mixed magnetic poles. The central line in each group of mixed permanent magnets is a straight axis, and the central line between two adjacent groups of mixed permanent magnets is a quadrature axis.

Referring to fig. 1-5, the quadrature-direct axis reluctance controllable permanent magnet brushless motor of the present invention realizes high torque, wide speed regulation, etc. when working. To further illustrate the design concept of controllable magnetic resistance of the quadrature-direct axis, fig. 6, 7 and 8 show the magnetic circuit and the simplified quadrature-direct axis equivalent magnetic circuit diagram of the motor of the present invention. R_pm1Is a neodymium-iron-boron permanent magnet4 magnetoresistance, R_pm2Is an AlNiCo permanent magnet 5 reluctance, R_barrierIs the q-axis magnetic barrier reluctance, R_gdIs d-axis air gap reluctance, R_gqIs q-axis air gap reluctance, F_pm1Is a neodymium-iron-boron permanent magnet with 4 magnetic potentials, F_pm2Is an AlNiCo permanent magnet 5 magnetic potential, F_gdIs d-axis magnetic potential, F_gqIs the q-axis magnetic potential. Wherein R is_pm1、R_pm2And R_gdForming d-axis reluctance R_d，R_barrierAnd R_gqForming a q-axis reluctance R_q. By applying magnetizing pulse current and armature current I, the magnetization level of the alnico permanent magnet 5 is increased, the magnetic resistance of the quadrature-direct axis is increased, and the change rate is rho_q＞ρ_d，ρ_qIs the rate of increase of quadrature axis reluctance, and

ρ_dis the rate of increase of the direct axis reluctance, and

the q-axis component in the leakage flux path tends to be saturated, effective turn chains between the permanent magnetic flux and the armature winding are increased, and the motor torque is increased. On the contrary, when weak magnetic current and demagnetizing pulse current are applied, the magnetization level of the AlNiCo permanent magnet 5 is reduced, and the quadrature axis magnetic resistance R is reduced_qReduced, straight axis reluctance R_dThe d-axis component in the leakage magnetic path tends to be saturated, and the leakage magnetic flux is increased, so that the motor R_d＞R_qThe main magnetic flux of the air gap is reduced, and the running range of the motor is expanded. The first magnetic adjusting mode of the invention is to control the saturation degree of the dq axis component of the magnetic leakage magnetic circuit through the change of the quadrature-direct axis magnetic resistance; the second magnetic modulation mode is to change the magnetization state of the alnico permanent magnet 5 by applying a direct-axis demagnetizing pulse current to the stator winding. When the motor operates, two magnetic adjusting modes are reasonably used according to operation requirements, so that the speed adjusting range of the motor can be effectively widened, the torque density can be improved, and the relatively high-torque operation of the motor under different working conditions can be realized.

In the normal operation process, q-axis armature current and quadrature axis magnetic resistance R are added into the armature winding_qStraight axis reluctance R_dAre all increasedPlus, but the quadrature-direct axis reluctance increases at different rates, the following relationship exists: rho_q＞ρ_d. Along with the obvious increase of the quadrature-direct axis magnetic resistance, the saturation degree of the q-axis component of the magnetic leakage magnetic path is increased, the interpolar magnetic leakage flux generated by the neodymium iron boron permanent magnet in the magnetic leakage path is reduced, the excitation flux is increased, and the torque required by normal operation can be provided. When the electric automobile is in a heavy-load climbing working condition, d-axis magnetizing pulse current is added to magnetize an AlNiCo permanent magnet, AlNiCo generates excitation magnetic flux, q-axis component of a leakage magnetic circuit is promoted to reach deep saturation, and quadrature axis magnetic resistance R is presented_qGreater than the direct axis reluctance R_dThe magnetic resistance characteristic of (2) reduces the invalid magnetic leakage in the magnetic leakage path, further improves the output torque of the motor, and meets the high torque output requirement during heavy load climbing. Weak magnetic current is applied during high-speed cruising, the mixed permanent magnet is promoted to generate interpolar magnetic leakage, the saturation of a d-axis component in a double-layer magnetic leakage path is promoted, and a direct-axis magnetic resistance R is presented_dIncreasing quadrature reluctance R_qReduced and gradually stabilized direct axis reluctance R_dGreater than quadrature axis reluctance R_qThe initial high-speed operation is realized. In order to further improve the operation range, d-axis demagnetizing pulse current is added to reduce the excitation magnetic flux generated by the alnico permanent magnet, the d-axis component in the double-layer magnetic leakage path reaches deep saturation, and the direct-axis magnetic resistance R_dContinuing to increase until a new steady state, and, similarly, quadrature axis reluctance R_qThe stable state is reduced until a new stable state, the stable magnetic resistance characteristic during the initial speed expansion is broken, and the operation range is expanded again.

A36-slot 8-pole motor with a rated rotation speed of 1200rpm and a rated torque of 28Nm is taken as an example. Referring to fig. 9 and 10, magnetic force lines of the motor under different operation modes caused by the controllable characteristic of the quadrature-direct axis reluctance of the present invention are shown, where fig. 9 is a magnetic force line graph during low-speed heavy loading, and fig. 10 is a magnetic force line graph during high-speed cruising. When the low-speed heavy-load operation is carried out, the alnico permanent magnet 5 is magnetized, and current is applied to the armature winding 2, so that the leakage flux passing through the leakage flux path is reduced, the main flux flowing to the stator core 1 is increased, and high torque density is obtained. Along with the increase of the rotating speed, the aluminum nickel cobalt permanent magnet 5 is demagnetized gradually, and weak magnetic current is added, so that the leakage magnetic flux is increased gradually, more magnetic flux flows into the adjacent permanent magnet through the leakage magnetic paths on the two sides of the leakage magnetic barrier group 6, and the high-rotating-speed operation is realized. Because the main magnetic flux is variable by using the controllable characteristic of the quadrature-direct axis magnetic resistance, the motor applies relatively small direct axis demagnetizing pulse current to the alnico permanent magnet 5 in the high-speed weak magnetic area, thereby not only avoiding the risk of irreversible demagnetization of the alnico permanent magnet 5, but also further ensuring the torque output capacity of the motor in the high-speed weak magnetic area.

Referring to fig. 11, a comparison graph of torque and rotation speed performance of the embodiment of the present invention and the conventional built-in permanent magnet brushless motor is obtained by using the same power and the same control method and through finite element simulation analysis, and advantages of high torque and wide speed regulation of the quadrature-direct axis reluctance controllable motor of the present invention are verified. When the motor runs at a low speed, the total torque is slightly larger than that of the traditional built-in permanent magnet brushless motor due to the saturation of a leakage magnetic circuit, the main torque generated by the neodymium iron boron and the secondary torque generated by the alnico permanent magnet; when the motor runs at high speed, because the magnetic resistance of the quadrature-direct axis changes in controllability, the torque is higher than that of the traditional built-in permanent magnet brushless motor, and the speed regulation range is wider.