CN1913284A - Halbach permanent magnet fault-tolerant brushless DC machine - Google Patents

Abstract

The utility model relates to a Halbach permanent magnet fault-tolerant brushless DC motor, which belongs to the DC motor of the motor category. The motor includes a rotor and a stator. The rotor includes a rotor core (1) and an external magnetic field halbach column (2). Each pole of the halbach column is composed of two magnets: a radial magnetization magnet (5) and a tangential magnetization magnet (6). Composition, they are radial magnetization and tangential magnetization respectively, produce square wave air gap flux density. The stator is composed of a stator core (3) and a concentrated winding (4). The teeth of the stator core can be in various tooth structures, and can be pole shoes or non-pole shoes. The stator can be straight teeth or helical teeth, and each phase is concentrated. Winding structure, the phases are sleeved on the stator teeth. The characteristic of this motor is that the square-wave air-gap magnetic density that meets the requirements is generated through the special regulations of the magnetic steel, and combined with the method of concentrating the tooth inlays between the full-pitch windings, the brushless DC motor of the present invention not only has the characteristics of high power density Moreover, it has the fault-tolerant capability of magnetic isolation of each phase and thermal isolation of each phase.

Description

Halbach Permanent Magnet Fault Tolerant Brushless DC Motor

1. Technical field

The Halbach permanent magnet fault-tolerant brushless DC motor of the present invention belongs to the DC motor of the motor class.

2. Technical background

In 1979, the famous American scholar Klaus Halbach proposed a novel design for the structure of permanent magnets - the Halbach column. Subsequently, scholars from various countries conducted a lot of research on the Halbach series and its application: Z.Q.Zhu, a Chinese scholar at the University of Sheffield in the United Kingdom, systematically sorted out various theories of Halbach motors, and established a set of Halbach motor design methods; Ohio State University in the United States used finite elements Optimized the design of the Halbach motor; Massachusetts Cambridge Institute of Technology analyzed the similarities and differences between the Halbach column and the ordinary permanent magnet structure, pointed out the superiority of the Halbach column in the surface-mounted permanent magnet motor, and elaborated on the generation of the Halbach motor torque ; Zurich University in Sweden, Chungnam University in South Korea, Osaka University in Japan, and CAPE Town University in South Africa have all done in-depth research on Halbach motors. Based on the above research, the Halbach motor has the following advantages: (1) High power density. Compared with the ordinary permanent magnet structure, due to the overlapping of the tangential magnetic field and the radial magnetic field after the decomposition of the Halbach column, the magnetic induction intensity of the air gap is greatly improved, which can effectively reduce the volume of the motor and increase the power density of the motor. (2) Stator and rotor no longer need chute. In the Halbach motor, due to the sinusoidal distribution of the air gap magnetic field, the harmonic content is small, and the stator and rotor do not need inclined slots. (3) Halbach column self-shielding effect, for the Halbach motor with external magnetic field, the rotor can use non-iron core material; for the Halbach motor with internal magnetic field, the shell does not need magnetic material, or even the shell, so as to reduce the volume and weight of the motor . And make the motor have a lower moment of inertia. (4) Concentrated windings can be used. In the Halbach motor, due to the sinusoidal distribution of its magnetic field, the harmonic magnetic field is small, and concentrated windings can be used to improve the utilization rate of conductive materials.

The Halbach column researched at home and abroad has two structural forms: using sintering or die casting to form a ring and magnetizing it in a special magnetizing device to form a sinusoidal distribution magnetic field Halbach column and using anisotropic magnetic steel of equal width, arranged in a certain direction to form Roughly satisfy the Halbach column of the sinusoidally distributed magnetic field. Both of these generate sinusoidal magnetic fields and are used in AC motors.

With the development of the aerospace industry, higher requirements are put forward for the high reliability and fault-tolerant performance of the motor. It is the best solution to realize the fault tolerance of the motor body without increasing the hardware cost and system complexity. When one or more phases of the motor fail, it can still achieve full output or only lose a small part of its performance. The key to the fault tolerance function is that the windings of each phase have a large enough self-inductance to limit the short-circuit current, and at the same time, the mutual inductance between phases is small enough to avoid the influence of the fault relative to the normal phase, that is, the magnetic isolation between phases.

The hardware fault tolerance of the motor includes the magnetic isolation of each phase of the winding and the thermal isolation of each phase. Switched reluctance motors and electrically excited doubly salient motors are magnetically isolated in each phase, but there are two or more sets of windings in the same slot, and the heat generated by one winding will quickly affect other windings. Compared with permanent magnet motors, the volume is larger and the power density low torque and large torque ripple, so using the advantages of the Halbach column to design a high-reliability permanent magnet motor not only has the characteristics of small size, high power density, but also has the fault tolerance capability of magnetic isolation and thermal isolation of each phase. The original intention of the invention.

3. Contents of the invention

The purpose of the present invention is: to overcome the deficiencies of the prior art, and propose a Halbach permanent magnet fault-tolerant brushless DC motor with small volume, high power density and magnetic isolation of each phase and thermal isolation of each phase.

The Halbach permanent magnet fault-tolerant brushless DC motor of the present invention is composed of a rotor, a stator and other accessories. The rotor includes a rotor core and an external magnetic field Halbach column. The rotor core is a ring of magnetically permeable material, and an external magnetic field Halbach column is pasted on the outside. Each pole of the halbach column is composed of two magnets, a radial magnetization magnet and a tangential magnetization magnet. They are radial magnetization and tangential magnetization respectively, and produce square wave air gap flux density. The stator is composed of a stator core and a concentrated winding. The teeth of the stator core can be in various tooth structures, and can be pole shoes or non-pole shoes. The stator can be straight teeth or helical teeth. Each phase is a concentrated winding structure. On the stator teeth, the same-phase windings can be output in series or in parallel.

The Halbach permanent magnet fault-tolerant brushless DC motor of the present invention can have five phases or more than five phases. The number of stator teeth is 4mn times the number of phases, m is the number of phases, n is an integer, which can be a natural number from 1 to 15, each phase has 2n sets of windings, and the stator has a total of 2m sets of windings, and the phases are set on the stator teeth. Only one of the two teeth has a winding on it, and there is only one set of windings in the same slot. The polar logarithm can be any natural number except m or an integer multiple of m. The windings of each phase can be rectified and output by the full bridge, and can be used as a brushless DC generator, or can be fed with a square wave current, and can be used as a brushless DC motor.

The radially magnetized magnets of the Halbach row are evenly distributed on the rotor core according to the law of N-S-N-S..., the tangentially magnetized magnets fill the remaining core space, and the N poles point to the N poles of the radially magnetized magnets, and the S poles point to The S poles of the radially magnetized magnetic steel are assembled together to form a magnetic ring. The size of the two pieces of magnetized magnetic steel can be unequal, and the shape can be different. The number of pole pairs of the Halbach column can be any natural number except m or an integer multiple of m, and m is the phase number.

The Halbach permanent magnet fault-tolerant brushless DC motor of the present invention, compared with the prior art, breaks KlausHalbach's constraints on the uniform shape and equal size of the Halbach column magnetic steel, and produces a square wave air gap that meets the requirements through the special regulations of the magnetic steel. magnetic density, thus the Halbach column is quoted in the brushless DC motor; the special Halbach column is combined with the method of concentrating the teeth inlays between the entire pitch windings, so that the brushless DC motor of the present invention not only has the characteristics of high power density of the permanent magnet motor , and has the fault-tolerant capability of magnetic isolation of each phase and thermal isolation of each phase.

4. Description of drawings

Figure 1 is a cross-sectional view of a five-phase, eight-pole, twenty-tooth motor;

Figure 2 is a schematic diagram of the magnetization mode of the rotor Halbach column magnets, and the direction of the arrow represents the magnetization direction of the magnets;

Figure 3 is the magnetic flux path of the A-phase winding;

Figure 4 is used as a generator, the connection between the stator winding and the power circuit;

Figure 5 is the five-phase normal working phase potential waveform and output DC potential waveform;

Fig. 6 is lacking a phase (example A phase) working phase potential waveform and output DC potential waveform;

Label names in the above figure: 1. Stator core, 2. Armature winding, 3. Halbach column, 4. Rotor core, 5. Radial magnetization magnet, 6. Tangential magnetization magnet, A-A' stands for A phase Winding, BB' stands for B-phase winding, CC' stands for C-phase winding, DD' stands for D-phase winding, EE' stands for E-phase winding.

5. Specific implementation

Since the structure of a motor with more than five phases is similar to that of a five-phase motor, the specific implementation will be described below by taking a five-phase, eight-pole, twenty-tooth motor as an example.

The Halbach permanent magnet fault-tolerant brushless DC motor of the present invention is composed of a rotor, a stator and other accessories, and its motor cross-sectional view is shown in FIG. 1 . The stator is composed of a stator core 1 and an armature winding 2. The stator core 1 is made of laminated silicon steel sheets. The teeth of the stator core can be in various tooth structures, and can be pole shoes or non-pole shoes, and can be straight teeth. or helical tooth form. The number of stator teeth is 4mn times the number of phases, m is the number of phases, n is an integer, which can be a natural number from 1 to 15, each phase has 2n sets of armature windings 2, and the stator has a total of 2mn sets of armature windings 2, and the phases are set in the stator On the teeth, only one of the two adjacent teeth has an armature winding 2, and there is only one set of armature winding 2 in the same slot, and the tooth widths of the windings are equal, and the electrical angle is 180 degrees (that is, the winding is a full pitch) close to 180 degrees electrical angle, and may not be equal to the width of non-winding teeth. The phase winding can be rectified by the full bridge and output as a brushless DC generator, as shown in Figure 4, or it can be fed with a square wave current to be used as a brushless DC motor.

The rotor of the Halbach permanent magnet fault-tolerant brushless DC motor of the present invention is composed of a rotor core 3 and a Halbach row 4, and the rotor core 3 can be formed by laminating silicon steel sheets or processed from a whole piece of steel. The Halbach column 4 is arranged with radial magnetization magnet steel 5 and tangential magnetization magnet steel 6 to form a magnetic ring. Different from the existing researched Halbach column, each pole is composed of only two magnets—the radial magnetization magnet 5 and the tangential magnetization magnet 6, and the radial magnetization magnet 5 and the tangential magnetization magnet 6 Comes in different shapes and sizes. Radial magnetization magnets 5 are tile-shaped, and their mechanical pole arc coefficient is greater than 720/m, m is the number of phases, radial magnetization magnets 5 are evenly distributed on the rotor core according to the law of N-S-N-..., tangential magnetization magnets 6 is filled with the remaining iron core space, its N pole points to the N pole of the radially magnetized magnet steel 5, and the S pole points to the S pole of the radially magnetized magnet steel 5, which together form a magnetic ring to produce a flat top air gap magnetic density , as long as the air-gap magnetic density is provided by the radially magnetized magnetic steel 5, the size of the tangentially magnetized magnetic steel 6 is fine-tuned to make the top width of the air-gap magnetic density greater than 720/m degrees electrical angle. The number of pole pairs of the Halbach column can be any natural number except m or an integer multiple of m, and m is the phase number.

In the Halbach permanent magnet fault-tolerant brushless DC motor of the present invention, the main magnetic flux path of each set of windings is: the tooth where the winding is located → air gap → radial magnetization magnet 5 → tangential magnetization magnet 6 → air gap → adjacent No winding tooth → stator yoke → the tooth where the winding is located, only very little magnetic flux is coupled to other phase windings, as shown in Figure 3 (the A-phase magnetic flux path is shown in the figure), so each phase winding has magnetic isolation capability, The failure of one phase winding has negligible effect on other phase windings. And there is only one set of windings in the same slot, and the windings have thermal isolation capability. Due to the square wave of air gap flux density and the full pitch of the winding, the potential of each phase is a square wave, and the top width of the square wave is greater than 720/m electrical angle. The output is rectified by the rectifier bridge shown in Figure 4. When each phase is working normally , the potentials of each phase and the rectified output potential are shown in Figure 5. When a phase fault occurs, the system cuts off the winding of this phase, and the potentials of the other phases and the rectified output potential are shown in Figure 6. The waveform of the rectified output potential remains basically unchanged.

Claims (1)

1, a kind of Halbach permanent magnet fault-tolerant brushless DC machine, comprise the stator that constitutes by stator core (1) and armature winding (2), rotor by rotor core (3) and Halbach row (4) formation, it is characterized in that, the stator number of teeth of described stator is 4mn a times of the number of phases, m is the number of phases, n is 1～15 natural number, every have 2n to overlap armature winding (2) mutually, the total 2mn cover of stator armature winding (2), and alternate being sleeved on the stator tooth, two teeth that face mutually have only armature winding (2) on the tooth, have only a cover armature winding (2) in the same groove, has the wide of armature winding tooth to equate, be 180 degree electrical degrees or, and can be not equal to the wide of non-armature winding tooth near 180 degree electrical degrees; Each utmost point of the Halbach row (4) of described rotor is made up of diametrical magnetization magnet steel (5) and tangential magnetization magnet steel (6), diametrical magnetization magnet steel (5) is a tile, its mechanical pole embrace is greater than 720/m, m is the number of phases, and press N-S-N-S-... rule be evenly distributed in the rotor core, tangentially magnetize magnet steel (6) and be full of remaining space unshakable in one's determination, its N utmost point points to the N utmost point of diametrical magnetization magnet steel (5), the S utmost point points to the S utmost point of diametrical magnetization magnet steel (5), is combined into magnet ring jointly; The size of diametrical magnetization magnet steel (5) and tangential magnetization magnet steel (6) can be unequal, and shape can be different, and the number of pole-pairs of Halbach row can be any natural number except that the integral multiple of m or m, and m is the number of phases.

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