CN103312103A - Bearingless switched reluctance motor with composite rotor structure - Google Patents

Abstract

The invention relates to a bearingless switched reluctance motor with a compound rotor structure, which belongs to the field of magnetic levitation switched reluctance motors. A set of windings is wound on the stator teeth of the stator; the rotor is composed of a torque rotor and a levitation force rotor, and the torque rotor and the levitation force rotor are axially superimposed in the stator; the torque rotor is used to generate torque, and the levitation force rotor is used for Generate levitation force and partial torque The present invention provides a bearingless switched reluctance motor with a composite rotor structure. There is only one winding on the stator teeth. Compared with the traditional double-winding bearingless switched reluctance motor, the structure is simple and the slot fill rate is high. Copper and silicon steel sheets are saved, which can reduce the cost of motor manufacturing. Structurally, the suspension force and torque are decoupled, the control method is simple, and the motor suspension performance is good. The levitation control is implemented by using the minimum inductance area, the influence of the levitation current on the torque current is small, and the coupling effect between phases is small. The winding utilization rate is high, the power density is high, and the high-speed adaptability is strong.

Description

A composite rotor structure bearingless switched reluctance motor

technical field

The invention relates to a bearingless switched reluctance motor with a compound rotor structure, which belongs to the field of magnetic levitation switched reluctance motors of motors.

Background technique

The bearingless switched reluctance motor is a new type of magnetic levitation motor developed at the end of the 20th century. The double-winding bearingless switched reluctance motor is to stack the levitation winding that generates the levitation force and the winding of the original ordinary switched reluctance motor on the stator of the motor. By controlling the current of the two sets of windings, it has the ability to rotate and self-levitate at the same time So as to realize the ultra-high speed operation of the motor. The single-winding bearingless switched reluctance motor has the ability to rotate and self-suspend at the same time by controlling the current of a set of windings. The single-winding bearingless switched reluctance motor has become a research hotspot and development trend of bearingless switched reluctance motor because the stator has only one winding, the structure is simpler, and the control algorithm is simple.

Regardless of the double-winding bearingless switched reluctance motor or the single-winding bearingless switched reluctance motor, there is a strong coupling between the torque and the levitation force, and it is difficult to achieve complete decoupling of the two in the control strategy and mathematical model. It is one of the main factors that make it difficult to improve the running performance of the bearingless switched reluctance motor. In addition, due to the suspension force control, the winding current must be controlled by chopping. When running at high speed, the surge of back electromotive force makes it impossible to control the winding current by tracking and chopping, that is, the current cannot be chopped. It affects the high-speed performance of the bearingless switched reluctance motor.

In order to solve the above two shortcomings of the bearingless switched reluctance motor, and based on the perspective of reducing the cost of the motor system, simplifying the control system, and improving and optimizing the performance of the suspension force, Korean scholars proposed two-phase motors with 8/10 and 12/14 structures. The bearingless switched reluctance motor is characterized in that the levitation force and torque are separately generated by the levitation winding and the torque winding respectively, the motor is a two-phase working system, and the power density of the motor is low.

Contents of the invention

The purpose of this invention is to propose a new type of bearingless switched reluctance motor with single winding structure, suspension force and torque decoupling, high speed adaptability and high power density.

The present invention adopts following technical scheme:

A bearingless switched reluctance motor with composite rotor structure according to the present invention comprises a stator, a torque rotor, a suspension force rotor, and a winding; a set of windings is wound on the stator teeth of the stator; the rotor is composed of a torque rotor and a suspension The torque rotor and the levitation force rotor are axially superimposed and arranged in the stator; the torque rotor is used to generate torque, and the levitation force rotor is used to generate levitation force and partial torque.

In the bearingless switched reluctance motor with composite rotor structure of the present invention, the stator has a salient pole structure and the number of teeth is 12.

In the bearingless switched reluctance motor with composite rotor structure described in the present invention, both the torque rotor and the levitation force rotor have eight rotor teeth.

In the composite rotor structure bearingless switched reluctance motor of the present invention, the winding form is a concentrated winding, and each phase winding is composed of four windings on the stator separated by 90°, and the four windings of each phase are independently controlled.

In the composite rotor structure bearingless switched reluctance motor of the present invention, the axial lengths of the torque rotor and the levitation force rotor, according to the actual torque and levitation force requirements, the torque rotor is used to generate most of the torque, and the levitation force rotor It is mainly used to generate suspension force and contribute part of the rotation.

Beneficial effect

A bearingless switched reluctance motor with a composite rotor structure provided by the invention has only one winding on the stator teeth. Compared with the traditional double-winding bearingless switched reluctance motor, the structure is simple, the slot fill rate is high, and copper and silicon steel sheets are saved. Reduce motor manufacturing costs. Structurally, the suspension force and torque are decoupled, the control method is simple, and the motor suspension performance is good. The levitation control is implemented by using the minimum inductance area, the influence of the levitation current on the torque current is small, and the coupling effect between phases is small. The winding utilization rate is high, the power density is high, and the high-speed adaptability is strong.

Description of drawings

Fig. 1 is a three-dimensional structural cross-sectional view of a bearingless switched reluctance motor with a composite rotor structure of the present invention

Fig. 2 is a schematic diagram of phase A winding of the bearingless switched reluctance motor with composite rotor structure of the present invention.

Fig. 3 is a graph showing the variation curves of the winding inductance and current and the rotor position angle of the bearingless switched reluctance motor with composite rotor structure of the present invention.

In the figure, 1 is the stator core, 2 is the torque rotor, 3 is the suspension force rotor, 4 is the winding, 5 is the winding inductance, 6 is the winding current in the suspension phase, and 7 is the winding current in the torque phase.

Detailed ways

Below in conjunction with accompanying drawing, the present invention is described in further detail;

As shown in Figure 1: a bearingless switched reluctance motor with a composite rotor structure, including a stator 1, a torque rotor 2, a suspension force rotor 3, and a winding 4; a set of windings 4 are wound on the stator teeth of the stator 1; The torque rotor 2 and the levitation force rotor 3 are composed of the torque rotor 2 and the levitation force rotor 3, which are axially superimposed and arranged in the stator 1; the torque rotor 2 is used to generate torque, and the levitation force rotor 3 is used to generate levitation force and part of the rotational speed. moment.

The stator is a salient pole structure with 12 teeth. Both the torque rotor 2 and the levitation force rotor 3 have 8 rotor teeth; the winding 4 is in the form of a concentrated winding, and each phase winding is composed of four windings on the stator separated by 90°, and the four windings of each phase are independently controlled.

The rotor tooth height of the torque rotor is relatively large, and the salient pole characteristics are obvious, so it is called a large salient pole rotor, which is used to generate most of the torque; while the other rotor (ie, the suspension force rotor) is mainly used to generate suspension force and contributes little Partial torque, the tooth height of the suspension rotor is small, and the salient pole characteristics are not obvious, so it is called a small salient pole rotor. The rotor height of the small salient pole rotor is related to the air gap length, and the value is 2~5 times the air gap length ;According to requirements, the levitation force rotor can also be divided into two, distributed on both sides of the torque rotor axis; the winding form adopts concentrated winding, each phase winding is composed of four windings on the stator separated by 90°, The 4 windings are independently controlled; by controlling the current of the winding, the levitation force and torque are generated in time and area, and the two are structurally decoupled; the minimum inductance flat-top area is used as the area for generating levitation force, and the levitation current has an effect on the torque current. The influence is small, and the coupling effect between phases is small. The axial length of the torque rotor and the levitation force rotor, according to the actual torque and levitation force requirements, the torque rotor is used to generate most of the torque, and the levitation force rotor is mainly used to generate the levitation force and contribute part of the rotation.

Fig. 2 is a schematic diagram of phase A winding of a bearingless switched reluctance motor with a three-phase 12/8-pole composite rotor structure. The one-phase winding is composed of coils distributed on 4 opposite teeth, spaced 90° apart from each other, and these 4 windings are controlled independently, and the levitation force and torque are generated in time and area. The four windings of phase B and phase C have the same structure as that of phase A, only differing from phase A by 30° and -30° in position.

Fig. 3 is a three-phase 12/8-pole composite rotor structure bearingless switched reluctance motor winding inductance and current variation curve with the rotor position angle. Define the alignment position of the stator teeth and the rotor teeth as the zero degree position, that is, the alignment position. For a three-phase 12/8-pole bearingless switched reluctance motor, if the period angle of a rotor is 45°, the range of levitation force generated by each phase winding is 15°, so as to ensure the stable levitation operation of the motor. Due to the time-division area control strategy of torque and suspension force, two phase windings need to be conducted at the same time at each moment, one phase winding is used to generate suspension force, and the other phase winding generates torque.

Take phase A as an example to illustrate the operating principle of the motor. When the rotor is located at [15°, 30°], it is the suspension stage. At this time, the magnetic permeability of the motor magnetic circuit is the smallest, and the inductance value is the smallest and constant. This area is called the minimum inductance flat top. region, the compound rotor structure bearingless switched reluctance motor of the present invention generates levitation force in this region, and does not generate torque in this region, so as to realize the decoupling of torque and levitation force. In the levitation interval, that is, when the rotor is located at [15°, 30°], since the rotor tooth height of the levitation force rotor is very small relative to the torque rotor, the reluctance of the magnetic circuit of the levitation force rotor is very small compared to the torque rotor; And because the levitation force is inversely proportional to the reluctance of the magnetic circuit, the levitation force generated by the torque rotor part is negligible relative to the levitation force rotor part, and the levitation force that provides the motor levitation is mainly generated by the levitation force rotor. The specific levitation force control principle is: the levitation force in the α direction is controlled by the winding currents i _{a 1} and i _{a 3} , when i _{a 1} > i _{a 3} , the levitation force in the positive direction of α is generated, otherwise, the levitation force in the negative direction of α is generated; Similarly, the levitation force in the β direction is controlled by the winding currents ia ₂ and ia _4. When ia ₂ > ia ₄ , the levitation force in the positive direction of β will be generated, otherwise, the levitation force in the negative direction of β will be generated; The directional levitation force can be synthesized into the levitation force in any direction, so through the asymmetric excitation of the four windings, the levitation force of any direction and size can be generated, and then the self-levitation function of the motor can be realized. Similarly, the levitation forces in the intervals of [0, 15°] and [30°, 45°] can be generated by the B-phase and C-phase windings respectively, thereby realizing the levitation operation in the entire rotor cycle.

When the rotor is located at [30°, 45°], it is the electric stage, and the inductance is in the rising area at this time, generating positive torque. When the phase A suspension excitation ends, the currents of the four windings of the A phase are not equal due to the asymmetrical excitation, so the same drive signal is required to control the main power switch of the A phase winding, so that the currents of the four windings are the same first, and then It is controlled by the current control method of the switched reluctance motor, and the specific current control method adopts chopping current control or PWM control or single pulse control. When it is turned on in the inductance drop area, it is power generation operation, and the control strategy is the same as that of the electric stage.

A person skilled in the art can easily associate other advantages and variants based on the above implementation types. Therefore, the present invention is not limited to the above-mentioned specific examples, which are merely used as examples to describe in detail and exemplary one form of the present invention. Within the scope of not departing from the gist of the present invention, technical solutions obtained by those skilled in the art through various equivalent replacements based on the above specific examples shall be included in the scope of the claims of the present invention and their equivalent scope.

Claims (4)

1. a composite rotors structure bearing-free switch reluctance motor is characterized in that: comprise stator (1), torque rotor (2), suspending power rotor (3), winding (4); Be wound with a cover winding (4) on the stator tooth of described stator (1); Rotor is comprised of torque rotor (2) and suspending power rotor (3), and torque rotor (2) axially superposes with suspending power rotor (3) and is arranged in the stator (1); Torque rotor (2) is for generation of torque, and suspending power rotor (3) is for generation of suspending power and part torque.

2. composite rotors structure bearing-free switch reluctance motor according to claim 1, it is characterized in that: described stator is that salient-pole structure and the number of teeth are 12.

3. composite rotors structure bearing-free switch reluctance motor according to claim 1 is characterized in that: described torque rotor (2) is 8 with the rotor tooth number average of suspending power rotor (3).

4. according to claim 1 and 2 or 3 described composite rotors structure bearing-free switch reluctance motors, it is characterized in that: described winding (4) form is centralized winding, every phase winding is comprised of the winding on four 90 ° of stators of being separated by, and four windings of every phase are independently controlled.

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