CN107181382A - A kind of rotor alternate angle stator magnetic barrier type axial permanent magnetic aids in double salient-pole electric machine - Google Patents

Abstract

A rotor staggered stator magnetic isolation type axial permanent magnet assisted double salient pole motor, belonging to the field of double salient reluctance motors; comprising: two sets of magnetic isolation type stators, two sets of circumferential staggered angle rotors, a rotating shaft, a casing, Axial ring-type composite permanent magnet, magnetic strip and excitation winding, the axial ring-type composite permanent magnet is ringed in the center of the shaft, and two sets of circumferential staggered rotors are fixed on the shafts on both sides of the axial ring-type composite permanent magnet Above, the magnetically isolated stator includes a partitioned stator yoke and salient poles; each salient stage is wound with an excitation winding; the magnetically isolated stator is set correspondingly to the circumferentially staggered rotor, and there is an air gap; the casing is coaxial with the rotating shaft The inner wall of the casing is provided with six magnetic isolation strips, the magnetic isolation stator is fixed in the magnetic isolation groove of the casing, and the magnetic conductive strips are used to connect the stator yokes on both sides to act as a magnetic bridge. The invention can effectively improve the output torque. Reduce the armature current under certain conditions, improve the torque ripple of the motor, and reduce the loss of the stator yoke, thereby improving the operating efficiency of the motor and improving the performance index of the motor.

Description

A magnetic-isolated axial permanent magnet assisted double salient pole motor with staggered rotor angle and stator

technical field

The invention belongs to the field of double salient pole reluctance motors, in particular to a rotor staggered stator magnetic isolation type axial permanent magnet auxiliary double salient pole motor.

Background technique

As the most commonly used doubly salient motor, switched reluctance motor is developing rapidly. The driving circuit of switched reluctance motor is simple, and it can maintain high-efficiency operation in a wide speed range. However, the torque ripple of ordinary salient reluctance motor Larger, the magnetic flux loss of the yoke between adjacent stator teeth is larger and wastes energy.

Contents of the invention

Aiming at the deficiencies in the above-mentioned prior art, the present invention provides an axial permanent magnet assisted double-salient pole motor with staggered rotor angle and magnetic separation of the stator. The motor can effectively increase the output torque and reduce the armature current under certain conditions. , improve the torque ripple of the motor, reduce the loss of the stator yoke, thereby improving the operating efficiency of the motor and improving the performance index of the motor;

Technical scheme of the present invention:

A rotor staggered stator magnetic isolation type axial permanent magnet assisted double salient pole motor, comprising:

Two sets of magnetically separated stators, two sets of circumferentially staggered rotors, rotating shafts, housings, axial ring-type composite permanent magnets, magnetic strips and excitation windings;

The axial ring-type composite permanent magnet includes a permanent magnet and a magnetically conductive material bonded at both ends thereof, and the axial ring-type composite permanent magnet is ringed in the center of the rotating shaft, and a certain gap is left between the rotating shaft;

The rotating shaft adopts a magnetic isolation material;

The circumferential staggered rotor is a composite structure, including a tubular magnetizer and a rotor yoke around the tubular magnetizer. Four salient poles are evenly distributed on the rotor yoke, that is, rotor teeth. The rotor yoke and rotor teeth are laminated by silicon steel sheets. The tubular magnetic conductor is closely combined with the rotor yoke to ensure the corresponding rigidity of high-speed rotation; the two sets of circumferentially staggered angle rotors are respectively fixed on the rotating shafts on both sides of the axial ring-type composite permanent magnet in a circumferentially staggered manner, and are connected to the rotating shaft Coaxial rotation;

The magnetically isolated stator is formed by laminating partitioned silicon steel sheets, including a partitioned stator yoke and 6 salient poles evenly distributed on it, that is, stator teeth; each convex stage is wound with an excitation winding with the same number of turns; two sets of The magnetically isolated stators are respectively arranged corresponding to two sets of circumferential staggered rotors, and there is a certain air gap between the magnetically isolated stators and the circumferential staggered rotors; the casing is arranged coaxially with the rotating shaft, and the inner wall of the casing is provided with six parallel The raised magnetic isolation bar on the rotating shaft forms a magnetic isolation slot, and the magnetic isolation type stator is fixed in the magnetic isolation slot of the casing; the magnetic isolation slot is used to isolate the magnetic leakage magnetic circuit between adjacent stator teeth, and Fix the partitioned stator yoke to prevent it from falling off due to the magnetic torque generated between the stator and rotor teeth of the motor; the casing is made of magnetic isolation material.

The middle part of the casing is provided with a device for fixing the axial ring-type composite permanent magnet and the magnetic strip, so that the axial ring-type composite permanent magnet and the magnetic strip are fixed in the middle of the casing, and the number of the magnetic strips is Six, using magnetically permeable materials, used to connect the yokes between the stators on both sides as a magnetic bridge.

The structures on both sides of the middle vertical plane of the rotating shaft are arranged in parallel except for the rotor, and are completely symmetrical to the middle vertical plane of the rotating shaft.

Beneficial effects: Compared with the prior art, the rotor staggered angle stator magnetic isolation type axial permanent magnet assisted double salient pole motor of the present invention has the following advantages:

(1) The permanent magnet auxiliary excitation structure is adopted, and the excitation current of the stator is reduced through the excitation effect of the permanent magnet in the magnetic circuit, which effectively reduces the copper loss of the excitation winding;

(2) The rotors on both sides are installed at staggered circumferential angles, which increases the number of convex teeth of the motor rotor. Its special structure can be approximately regarded as a 12/8-level structure, which has a smaller step angle than the classic 6/4-level structure. Effectively increase the output torque of the motor, improve torque smoothness and reduce noise;

(3) By adopting the double-side excitation and rotor staggered-angle synchronous control method, it can effectively realize the complementarity of the torque peak and valley connection on both sides, reduce the switching frequency of electronic devices, improve the service life and effectively reduce the core loss of the stator and rotor;

(4) The stator and rotor are laminated with silicon steel sheets, which greatly reduces the quality of the motor, reduces the moment of inertia of the motor, reduces the complexity of motor control, and makes the stator and rotor have good magnetic permeability;

(5) The magnetic isolation stator and the magnetic bridge effectively "plan" the magnetic circuit of the motor to a specific path, reducing the loss of magnetic leakage on the non-energized phase and the casing;

(6) The combination of permanent magnet auxiliary technology and stator magnetic isolation can effectively increase the air gap magnetic energy increment and improve the motor output torque index per unit mass.

Description of drawings

Fig. 1 is a radial sectional view of a rotor staggered stator magnetic isolation type axial permanent magnet assisted double salient pole motor according to an embodiment of the present invention, wherein (a) is a two-dimensional radial sectional view, and (b) is a three-dimensional radial sectional view sectional view;

Fig. 2 is a three-dimensional structural schematic diagram of an axial ring type composite permanent magnet according to an embodiment of the present invention;

Fig. 3 is a schematic diagram of a wrong angle of a rotor according to an embodiment of the present invention;

Fig. 4 is a side view of a rotor staggered stator magnetic isolation type axial permanent magnet assisted double salient pole motor with different rotor positions according to an embodiment of the present invention, wherein (a) is that one side A starts to be energized, and the two sides A have been energized The side view when the power is on, (b) is the side view when the phase A on both sides is powered off, the phase A on one side remains energized, and the phase B on the two sides starts to be powered on; (c) is the phase A winding on one side is powered off, and the phase B on the two sides The side view when the phase remains energized and the B phase on one side starts to be energized;

Fig. 5 is a schematic diagram of a magnetic circuit according to an embodiment of the present invention;

Fig. 6 is a schematic diagram of the variation of motor phase inductance with rotor position according to an embodiment of the present invention;

Fig. 7 is a schematic diagram of a casing and a magnetically isolated stator according to an embodiment of the present invention, wherein (a) is a schematic diagram of a casing with a magnetically isolated strip, (b) is a schematic diagram of a magnetically isolated stator, and (c) is a casing Schematic diagram of assembling with magnetic isolation stator;

Fig. 8 is a schematic diagram of a magnetic strip according to an embodiment of the present invention, wherein (a) is a three-dimensional schematic diagram of a motor without a casing end cover, and (b) is a front view of a motor without a casing end cover;

Fig. 9 is an overall schematic diagram of a motor according to an embodiment of the present invention;

Among them, 1-rotating shaft, 2-casing, 3-axial sleeve type composite permanent magnet, 3a-permanent magnet, 3b-magnetic conductor, 4-magnetic conductive strip, 5-excitation winding, 6-end cover, 7- Tubular magnetic conductor, 8-rotor yoke, 9-salient pole, 10-partitioned stator yoke, 11-stator teeth, 12-casing protrusion, 13-magnetic separation slot, 14-magnetic strip, 15-gas gap;

Fig. 10 is a schematic diagram of the change of the magnetic co-energy when the current is constant according to an embodiment of the present invention.

detailed description

An embodiment of the present invention will be described in detail below in conjunction with the accompanying drawings.

As shown in Figure 1-9, a rotor staggered stator magnetic isolation type axial permanent magnet assisted double salient pole motor, including:

Two sets of magnetically isolated stators, two sets of circumferentially staggered rotors, rotating shaft 1, housing 2, axial ring-type composite permanent magnet 3, magnetic strip 4, field winding 5 and end cover 6.

As shown in Figure 2, the axial ring-type composite permanent magnet 3 includes a permanent magnet 3b and a magnetic conductor 3a bonded at both ends thereof. There is a certain gap between them; the magnetic conductor 3a is made of magnetic permeable material.

The rotating shaft 1 is made of magnetic isolation material.

The use of permanent magnets to assist excitation can reduce the stator current while the output performance of the motor remains unchanged, saving energy. Since the permanent magnet and the field winding generate the air-gap magnetic density in the air gap at the same time, the addition of the permanent magnet can correspondingly reduce the excitation current and increase the air-gap magnetic density to increase the torque.

As shown in Figure 3-4, the circumferential staggered rotor is a composite structure, including a tubular magnetizer 7 and a rotor yoke 8 on the periphery of the tubular magnetizer. Four salient poles, namely rotor teeth 9, are evenly distributed on the rotor yoke. The rotor yoke 8 and the rotor teeth 9 are made of laminated silicon steel sheets, and the tubular magnet 7 is closely combined with the rotor yoke 8 to ensure the corresponding rigidity of high-speed rotation; the two sets of circumferentially staggered rotors adopt the circumferential The staggered angles are respectively fixed on the rotating shafts 1 on both sides of the axial ring type composite permanent magnet 3, and rotate coaxially with the rotating shaft 1.

Using the circumferential staggered angle method, since this motor can be approximately regarded as a 12/8 reluctance motor, compared with the ordinary 6/4 reluctance motor, the number of rotor stages is increased, the step angle is reduced, and the smooth output of the motor torque is improved. stability and reduce noise. The step angle is Among them, t _r is one period of electrification, and the pole distance of one rotor after one rotation is t _r =360/Nr, m is the number of phases, and Nr is the number of poles of the motor rotor.

As shown in Figures 4(a)-4(c), the magnetically isolated stator is formed by laminating partitioned silicon steel sheets, including a partitioned stator yoke 10 and 6 salient poles evenly distributed along the circumference on it, that is, the stator 11 teeth; each convex stage is wound with an excitation winding 5 with the same number of turns; two sets of magnetically isolated stators are set correspondingly to two sets of circumferentially staggered rotors, and there is a certain distance between the magnetically isolated stators and circumferentially staggered rotors. Air gap 15.

The salient pole design is adopted for the stator and rotor, and the "minimum reluctance principle" is used to generate tangential pulling force to realize the starting, braking, stopping and four-quadrant operation of the motor.

The operation principle and control method of the rotor staggered stator magnetic isolation type axial permanent magnet assisted double salient pole motor are as follows:

The excitation windings on both sides of the axial ring type permanent magnet are evenly divided into A phase, B phase and C phase as shown in FIG. 4 , and the distribution of the windings on both sides is symmetrical. The windings on both sides are separately controlled by two sets of control systems to realize the direction of the magnetic flux path as shown in Figure 5. When the drive motor is running, the magnetomotive force is generated by passing current into the excitation coil of the one-phase stator, and the stators at both ends form N poles and S poles respectively. The end rotor teeth form S poles and N poles respectively, and the magnetomotive forces generated by the permanent magnet 3b and the field winding 5 are superimposed and act on the closed magnetic circuit to generate air gap flux density. According to the "minimum reluctance principle", a tangential pulling force is generated, and the motor can be rotated by controlling the conduction of the excitation winding in sequence. Motor magnetic circuit: stator convex stage 11 on one side, air gap 15, rotor convex stage 9 on one side, magnet conductor 7, axial ring-type composite permanent magnet 3, magnet conductor 7, rotor convex stage 11 on the other side, air gap 15. The stator convex stage 9 on the other side, the magnetic strip 14, and the stator convex stage 11 on one side. Since the addition of permanent magnets increases the total magnetomotive force in the magnetic circuit and strengthens the magnetic density of the air gap in the magnetic circuit, a smaller excitation current can be used to achieve the given magnetic density effect of the air gap.

The specific implementation method is shown in Figure 4(a). At this time, the stator A phase on both sides is energized. Specifically, one side A starts to be energized, and the two sides A have already been energized. Due to the tangential magnetic tension generated between the stator and rotor due to the air gap magnetic flux distortion The rotor rotates clockwise; when the rotors on both sides rotate clockwise to the alignment position of the stator and rotor convex stages, as shown in Figure 4(b), at this time, phase A on both sides is powered off, phase A on both sides remains energized, and phase B on both sides starts to be energized ; The rotor continues to rotate. When the rotor on one side is aligned with the stator, as shown in Figure 4(c), at this time, the A-phase winding on one side is powered off, the B-phase on the two sides remains energized, and the B-phase on one side starts to be energized, completing a commutation , and so on, the motor runs clockwise, and the reverse is the opposite of the above process.

The advantage of using the above-mentioned control strategy in this design is that at any time during the entire control process, the windings on both sides, that is, the above-mentioned same-phase or out-of-phase windings, are energized at the same time, so that the torque on both sides can be superimposed to increase the output of the motor; in addition, in this embodiment , there is no process under the energized phase inductance, because the inductance of the energized phase winding changes with the rotor position, as shown in Figure 6, the inductance is the largest when the stator and rotor are aligned, and the smallest in the non-aligned position. Due to the electric torque formula of the switched reluctance motor:

i is the current of the stator winding, L is the inductance of the stator winding, and θ is the angle between the axis of the stator and the rotor. In the above control process, whenever the stator and rotor on a certain side are aligned, the stator winding on this side is controlled to be powered off, so the influence on the torque fluctuation of the motor when the inductance drops is avoided, and the torque ripple problem of the ordinary reluctance motor is improved.

As shown in Figure 7(a)-7(c), the casing 2 is arranged coaxially with the rotating shaft 1, and six protrusions 12 parallel to the rotating shaft are arranged on the inner wall of the casing to form a magnetic isolation groove 13. The magnetic material eliminates the iron loss on the traditional motor casing. The protrusion 12 is a magnetic spacer strip, which plays a role in cutting off the magnetic flux between adjacent stators and fixes the stator to prevent it from falling off due to the magnetic torque generated between the stator and rotor teeth of the motor; wherein, as shown in Figure 7 (b), the spacer The magnetic stator is fixed in the magnetic isolation slot of the casing, which solves the problem of leakage of the magnetic flux generated by the excitation winding of the energized phase to the stator of the non-energized phase, reducing loss.

The middle part of the casing 2 is provided with a device for fixing the axial ring-type composite permanent magnet 3 and the magnetic strip 14, so that the axial ring-type composite permanent magnet and the magnetic strip are fixed on the middle part of the casing, as shown in Figure 8 ( As shown in a)-8(b), the number of the magnetic conductive strips 14 is six, and the magnetic conductive material is used to connect the magnetic flux between the stators on both sides and act as a magnetic bridge.

As shown in FIG. 9 , end covers 6 are provided at both ends of the casing 2 .

The structures on both sides of the middle vertical surface of the rotating shaft 1 are arranged in parallel except for the rotor, and are completely symmetrical to the middle vertical surface of the rotating shaft.

The principle of boosting torque is as follows: The electromagnetic torque of the switched reluctance motor can be calculated from the angle of electromechanical energy conversion and the magnetic energy:

Among them, W is the magnetic co-energy of the motor, as shown in Figure 10, where the area enclosed by the curve OCB (or OA) and the i coordinate axis represents the magnetic co-energy, which is a function of current and flux linkage, and θ is the rotor relative Angular displacement of the stator. Therefore, the torque capability of the motor can be reflected by the I-φ characteristic curve, as shown in Figure 10. The straight line OA in the figure indicates that the centerline of the rotor teeth coincides with the centerline of the stator slot (that is, the position where the axes of the stator and rotor teeth are not aligned) The characteristics of , corresponding to the maximum reluctance position, at this time, due to the large air between the stator and rotor poles, the magnetic circuit is not saturated, so it is an OA straight line; and the curve OCB represents the characteristics when the centerlines of the stator and rotor poles are aligned, corresponding to Minimum reluctance position.

The average torque of each step forward of the rotor is proportional to the enclosing magnetic co-energy increment ΔW of the area OABCO, so the average output torque of the multiphase switched reluctance motor is:

Among them, Nr is the number of motor rotor poles, and m is the number of phases. Obviously, under the same magnetic field energy storage, increasing the number of phases and rotor poles of the motor can also effectively increase the output torque of the motor. But for the traditional structure of the switched reluctance motor, when the outer diameter of the motor is determined, there is a mutual constraint relationship among the three, which is difficult to obtain from the structure. The invention adopts a special structure equivalent to a 12/8-level structure to increase the number of rotor poles and increase the torque.

Because the leakage flux of the adjacent tooth poles of the ordinary switched reluctance motor will generate a braking torque on the rotor, which will greatly affect the output of the motor. Therefore the present invention adopts permanent magnet assistance. The axial permanent magnet assists the magnetic flux direction of the permanent magnet to be opposite to the magnetic flux leakage direction in the stator and rotor cores, so that the magnetic flux leakage between poles is significantly reduced, and the braking torque generated by the magnetic flux leakage is reduced.

It can also be seen from formula (3) that the torque increase of the switched reluctance motor can be realized by increasing the magnetic co-energy increment ΔW. The relationship between the air gap flux and the current when the stator and rotor teeth are aligned is shown in OAB in Figure 10; the direction of the magnetic flux of the permanent magnet is the same as the direction of the magnetic flux generated by the stator winding in the air gap, and the air gap flux is enhanced, thus strengthening the The enclosing magnetic co-energy increment area ΔW of the region OABCO.

Therefore, the axial permanent magnet assisted double salient pole motor of the rotor staggered angle stator magnet isolation type of the present invention realizes the increased torque by increasing the number of rotor stages and increasing the magnetic co-energy increment ΔW.

Claims (7)

1. a kind of rotor alternate angle stator magnetic barrier type axial permanent magnetic aids in double salient-pole electric machine, it is characterised in that including：

Two groups of magnetic barrier type stators, two groups of circumferential alternate angle rotors, rotating shaft, axially casing, sleeved composite permanent magnet and Exciting Windings for Transverse Differential Protection；

The sleeved composite permanent magnet in axial direction includes the permeability magnetic material that permanent magnet and its two ends are cohered, axially sleeved to be combined forever Magnet ring set leaves between rotating shaft certain interval in rotating shaft center；

The circumferential alternate angle rotor is included in the rotor rim of tubulose magnetic conductor and tubulose magnetic conductor periphery, the rotor rim Even distribution salient pole is rotor tooth, and two groups of circumferential alternate angle rotors are individually fixed in axially sleeved composite permanent magnet both sides rotating shaft, With rotating shaft coaxial rotating；

The magnetic barrier type stator includes partition-type stator yoke and equally distributed salient pole is stator tooth thereon；In each convex level around There is identical number of turn Exciting Windings for Transverse Differential Protection；Two groups of magnetic barrier type stators are correspondingly arranged with two groups of circumferential alternate angle rotors respectively, magnetic barrier type stator with Certain air gap is separated between circumferential alternate angle rotor；

The casing is coaxially disposed with rotating shaft, and casing inner wall sets six to form magnet isolation tank parallel to the raised every magnetic stripe of rotating shaft, The magnetic barrier type stator is fixed in the magnet isolation tank of casing.

2. rotor alternate angle stator magnetic barrier type axial permanent magnetic according to claim 1 aids in double salient-pole electric machine, it is characterised in that Six magnetic conduction bars, the magnetic conduction strip adoption permeability magnetic material, for being connected both sides stator are provided between two groups of magnetic barrier type stators Yoke serves as magnetic bridge；The device for fixed axially sleeved composite permanent magnet and magnetic conduction bar is provided with the middle part of the casing, The sleeved composite permanent magnet in axial direction and magnetic conduction bar is set to be fixed in the middle part of casing.

3. rotor alternate angle stator magnetic barrier type axial permanent magnetic according to claim 1 aids in double salient-pole electric machine, it is characterised in that It is uniformly distributed in the rotor rim on 4 salient poles, the partition-type stator yoke and is uniformly distributed 6 salient poles.

4. rotor alternate angle stator magnetic barrier type axial permanent magnetic according to claim 1 aids in double salient-pole electric machine, it is characterised in that The rotating shaft uses NULL.

5. rotor alternate angle stator magnetic barrier type axial permanent magnetic according to claim 1 aids in double salient-pole electric machine, it is characterised in that The rotor rim and rotor tooth are formed by silicon steel plate stacking, and the magnetic barrier type stator is formed using partition-type silicon steel plate stacking.

6. rotor alternate angle stator magnetic barrier type axial permanent magnetic according to claim 1 aids in double salient-pole electric machine, it is characterised in that Described two groups circumferential alternate angle rotors are individually fixed in axially sleeved composite permanent magnet both sides rotating shaft using circumferential alternate angle mode.

7. rotor alternate angle stator magnetic barrier type axial permanent magnetic according to claim 1 aids in double salient-pole electric machine, it is characterised in that The casing uses NULL, and the magnet isolation tank is used for the leakage field magnetic circuit for separating adjacent stators between cog, and fixed partition-type Stator yoke, prevents it because electric machine rotor between cog produces magnetic torque and comes off.