CN109194082B - Amorphous alloy axial flux motor with wide field weakening speed expansion and low rotor loss - Google Patents

Abstract

The amorphous alloy axial flux motor comprises a double-stator structure and a single-rotor structure, wherein the rotor structure is positioned between the two stator structures; the stator comprises a stator yoke part and a stator tooth part which are formed by winding amorphous alloy materials; the stator yoke is directly contacted with the end cover; the stator yoke part and the stator tooth part jointly form a stator core; circumferential disc-shaped water channels are arranged in the end covers at the two ends of the shell; the double-layer distributed armature winding is embedded in the stator iron core; the rotor structure is a single-disk structure, wherein the number of pole pairs of the permanent magnet and the soft magnetic pole is equal; the soft magnetic pole is particularly an SMC soft magnetic pole with low conductivity; the permanent magnet is specifically a sintered neodymium iron boron permanent magnet and bonded neodymium iron boron permanent magnets with low conductivity on two sides of the sintered neodymium iron boron permanent magnet; the rotor bracket is sleeved on the motor shaft; the flux-weakening motor has larger quadrature-direct axis inductance and lower rotor loss, can fully utilize reluctance torque generated by the unequal quadrature-direct axis inductance of the axial flux motor, and has wider flux-weakening speed expansion range.

Description

Amorphous Alloy Axial Flux Motor with Wide Field Weakening Speed and Low Rotor Loss

technical field

The invention belongs to the field of axial magnetic flux motor design, and mainly relates to an amorphous alloy axial magnetic flux motor with wide weak magnetic expansion speed and low rotor loss.

Background technique

Amorphous alloy axial flux permanent magnet synchronous motors have attracted more and more attention in recent years due to their compact structure, high power density, and high efficiency, making them suitable for use in electric vehicles, wind power and other fields. get great application. However, the electrical conductivity of the permanent magnet and the rotor bracket of the motor is high, the rotor eddy current loss is large, and the rotor heats up very seriously at high frequency and high speed, and the air gap magnetic field in the motor is basically kept constant due to the inherent hard magnetic properties of the permanent magnet material itself. Axial flux permanent magnet synchronous motors mostly use bilateral air-gap topology, which has a large air gap, fewer series turns per phase, and most of the rotors are surface-mounted magnetic poles, which makes the motor inductance smaller. When the traditional method of increasing the direct-axis demagnetizing current to weaken the air-gap magnetic field, its weak-field expansion capability is limited, which has become a bottleneck restricting the development of amorphous alloy axial flux motors.

In order to reduce the eddy current loss of the rotor, increase the inductance of the AC-DC axis of the amorphous alloy axial flux permanent magnet synchronous motor, effectively adjust and control the air-gap magnetic field, and realize the high-efficiency weak magnetic speed expansion of the motor. The reluctance torque generated by the unequal inductance increases the power density of the motor. Many researchers have proposed using different types of topology to solve the traditional permanent magnet synchronous motor rotor eddy current loss, difficult to adjust the magnetic field, not conducive to weak magnetic speed expansion, etc. problems, but there are still various degrees of defects:

(1) Chinese patent CN105680649A proposes that the present invention discloses an axial radial flux double salient permanent magnet motor, including a lower axial rotor, a permanent magnet ring, a lower axial stator, an upper axial stator, and a radial rotor , radial stator, upper axial rotor and rotating shaft; the radial rotor is arranged in the radial stator, and the permanent magnet ring is embedded in the radial stator; the rotating shaft passes through the upper axial stator, the upper axial rotor and the radial rotor in turn , the lower axial rotor and the lower axial stator, and the upper axial rotor, the radial rotor and the lower axial rotor are fixedly installed on the rotating shaft; the upper axial stator and the lower axial stator are respectively fixedly installed on the upper and lower end faces of the radial stator The upper and lower ends of the rotating shaft are respectively rotatably mounted on the upper axial stator and the lower axial stator. The motor of the present invention forms a set of radial magnetic fluxes and two sets of axial magnetic fluxes, which combines the advantages of the axial magnetic flux motor and the double salient pole motor, and has small rotational inertia, large starting torque, small starting current, and large output. , which enhances operational security. However, the armature reaction of the motor is small, which is not conducive to the weak field speed expansion of the motor, so it is difficult for the motor to exert its advantages in the application of wide rotation speed.

(2) Chinese patent CN103997145A proposes an axial flux permanent magnet synchronous motor. The motor includes a rotating shaft, a rotor is assembled to the rotating shaft, at least one permanent magnet is assembled to the rotor, and also includes a stator assembly, the stator assembly includes stator modules oriented in an axial direction, and each stator module includes a pair of yoke parts. Connected stator teeth and multiple windings, each wound on a stator module. The invention is characterized in that: the axial flux motor uses low-cost ferrite magnets, and the cogging torque vibration noise is reduced, but the motor is difficult to exert its advantages in the application of wide rotational speed.

(3) Chinese patent CN10530757A proposes a topological structure of a double interleaved hybrid excitation motor. The motor includes a front end cover, a rear end cover and a casing. A rotor yoke is provided on the rotating shaft. The rotor yoke has inherent permanent magnet N pole and permanent magnet S pole and iron pole, the casing is evenly provided with armature iron core and field core, the armature iron core is provided with AC armature winding, and the field core is provided with AC excitation winding; rotating shaft, rotor yoke, permanent magnet N pole, permanent magnet S pole The rotor and the iron pole constitute the rotor; the AC armature winding, the armature iron core, the AC excitation winding, the excitation core and the casing constitute the stator. The characteristics of the invention are: the motor is a radial magnetic flux structure, the air gap magnetic flux is adjusted by AC current, the excitation magnetomotive force and the armature magnetomotive force are in a parallel relationship, and the induction is changed by adjusting the distribution of the magnetic flux. The size of the electric potential can achieve a wider range of speed regulation in variable-speed electric occasions, but the motor has a complex manufacturing process and is not suitable for high-frequency and high-speed applications.

(4) Chinese patent CN105375655A proposes an axial flux motor using a soft magnetic powder core with high saturation magnetic induction, specifically using a soft magnetic powder core with high saturation magnetic induction on a composite permanent magnet or iron core. Compared with the prior art, after using a soft magnetic powder core with high saturation magnetic flux density for composite permanent magnets or high-power iron cores, due to its high saturation magnetic flux density, a larger excitation magnetic field can be used under the same iron core material. Excited stator with stronger field flux density. According to theoretical calculations and experiments, the maximum excitation flux density is significantly larger than that of traditional amorphous iron cores and newer ironless stators, with higher output power. However, the motor armature reaction is small, and it is difficult to exert its advantages in the application of wide speed.

(5) Chinese patent CN103915961A discloses a new type of axial flux doubly salient permanent magnet generator, and the technical problem to be solved is: the existing generators have problems such as overly complicated structure and large energy consumption. The technical scheme adopted is: including the rotor, the outer stator of the generator, the inner stator of the generator, the permanent magnet ring and the rotor shaft; the inner stator of the generator is nested in the outer stator of the generator, and between the inner stator of the generator and the outer stator of the generator There is a gap; the permanent magnet ring is installed in the aforementioned gap; the rotor shaft is arranged at the center of the rotor and is fixed as a whole; the rotor shaft passes through the center of the inner stator of the generator, and is not connected to the inner stator of the generator. contact; the rotor is positioned above the generator outer stator and the generator inner stator. The invention organically combines the double salient permanent magnet motor and the axial flux motor, and has the advantages of high efficiency, high power density, compact structure, low noise and low starting wind speed. However, it is difficult for this motor to exert its advantages in wide-speed applications.

(6) Chinese patent CN1808846A proposes a double-fed hybrid excitation axial magnetic field permanent magnet motor topology. The motor includes a rotor and two left and right stators placed on both sides of the rotor. The magnetic poles of the rotor are divided into two inner and outer circles by the magnetic isolation area, the outer circle is the iron core pole, and the inner circle is a permanent magnet with alternating polarities; The inner side of the outer teeth is installed with the magnetic field control winding, while the main armature winding is installed around the inner and outer teeth. The characteristics of the invention are: by changing the current amplitude and direction in the magnetic field control winding to adjust the total magnetic flux of the air gap of the motor, to achieve the purpose of changing the size of the induced potential, but the structure of the motor has a large amount of permanent magnets and weak magnetic field expansion speed. The scope is rather limited.

SUMMARY OF THE INVENTION

Purpose of the invention: Due to the inherent hard magnetic properties of the permanent magnet material, the air gap magnetic field in the motor is basically kept constant. Most of the traditional axial flux permanent magnet synchronous motors adopt a bilateral air gap topology, which has a large air gap and The number of series turns per phase is small, and the rotor is mostly surface-mounted magnetic poles, which makes the motor inductance small. When the traditional method of increasing the direct-axis demagnetization current to weaken the air gap magnetic field is used, its weak magnetic speed expansion capacity is limited, and the traditional method The permanent magnet and rotor bracket of the axial flux motor have high electrical conductivity, and the rotor eddy current loss is large, and the rotor heats up very seriously at high frequency and high speed. In order to reduce the rotor eddy current loss and realize the simple, flexible, cost-effective adjustment and control of the air-gap magnetic field of the axial flux permanent magnet synchronous motor and improve the motor speed regulation and driving performance, a wide field-weakening speed expansion and low rotor loss are introduced. Amorphous alloy axial flux motor.

Technical solutions:

An amorphous alloy axial flux motor with wide field weakening speed expansion and low rotor loss, comprising a double stator structure and a single rotor structure, and the rotor structure is located in the middle of the two stator structures;

The stator structure comprises: a stator yoke part and a stator tooth part wound by an amorphous alloy material; the stator yoke part is directly in contact with the end cover; the stator yoke part and the stator tooth part together constitute a stator core;

The end covers at both ends of the casing are provided with circumferential disc-shaped water channels;

The double-layer distributed armature winding is embedded in the pear-shaped slot of the stator core;

The rotor structure is a single-disc structure, including a stainless steel rotor bracket, permanent magnets and soft magnetic poles embedded in the rotor bracket arranged up and down; the number of pole pairs of the permanent magnets and the soft magnetic poles is equal;

The soft magnetic pole is specifically a low-conductivity SMC soft magnetic pole;

The permanent magnets are specifically sintered NdFeB permanent magnets and low-conductivity bonded NdFeB permanent magnets on both sides thereof;

The rotor bracket is sleeved on the motor shaft.

In the described amorphous alloy axial flux motor with wide weak magnetic field expansion and low rotor loss, preferably: the stator iron core adopts a low-loss amorphous alloy strip cut into a pear-shaped slot structure along the radial direction of the motor It is wound and attached to both sides of the end cover with a circumferential disc-shaped water channel. The armature winding of the stator scattered copper wire adopts a double-layer fractional slot distributed winding.

In the amorphous alloy axial flux motor with wide weak magnetic field expansion and low rotor loss, preferably: the outer circumference of the rotor support is provided with a notch.

In the described amorphous alloy axial flux motor with wide weak magnetic field expansion and low rotor loss, preferably: on the rotor support, permanent magnets and soft magnetic poles are arranged in a circularly evenly distributed sector; wherein the soft magnetic poles are located close to the motor shaft. The permanent magnet is located on the side away from the motor shaft; the permanent magnet is a three-layer structure, and the sintered NdFeB permanent magnet is sandwiched between two bonded NdFeB permanent magnets.

Advantages and Effects:

The present invention is an amorphous alloy axial flux motor with wide weak magnetic expansion speed and low rotor loss, and has the following advantages and beneficial effects:

1. The present invention is a double stator and single rotor structure. By opening the water channel of the circumferential disc structure on the end cover in contact with the stator core, the heat generated on the stator can be effectively taken away and the power of the axial flux motor can be improved. density.

2. The position of the inner surface of the rotor facing the inner teeth of the amorphous alloy stator iron core proposed by the present invention adopts the connection of the permanent magnet and the soft magnetic pole. When the demagnetization current is applied to the armature winding, it can be connected to the permanent magnet. The soft magnetic pole of the magnetic field produces a reverse magnetic field, which can weaken the air gap magnetic field to a greater extent, so that the axial flux motor has a wider operating speed.

3. Compared with the traditional axial flux permanent magnet synchronous motor, the permanent magnets and the soft magnetic poles have the same number of embedded pole pairs inside the stainless steel rotor bracket proposed by the present invention, and the permanent magnets and the soft magnetic poles work together The combination can make full use of the reluctance torque generated by the unequal inductance of the axial flux motor and the direct axis, improve the torque density of the motor, help reduce the amount of permanent magnets, and reduce the manufacturing cost of the motor.

4. The soft magnetic poles formed by the powder metallurgy material SMC used in the single-disk rotor of the axial flux motor proposed by the present invention, the two sides of the sintered NdFeB permanent magnets are bonded NdFeB permanent magnets with low electrical conductivity, and the permanent magnets and The soft magnetic poles have equal number of pole pairs, and are embedded in a high-strength stainless steel rotor bracket arranged up and down. The rotor bracket embedded with magnetic poles is sleeved on the rotating shaft of the motor. The slot on the upper end of the rotor bracket is used to reduce the eddy current loss of the rotor bracket.

5. The stator iron core of the coiled amorphous alloy strip proposed by the present invention has significantly less iron loss of the motor at high frequency than the traditional silicon steel sheet due to the amorphous alloy material. Alloy axial flux motors are especially suitable for high frequency and high speed applications.

Description of drawings:

Figures 1 and 2 are schematic diagrams of an amorphous alloy axial flux motor with wide field-weakening speed and low rotor loss.

FIG. 3 is a schematic diagram of the stator structure of an amorphous alloy axial flux motor with wide field-weakening speed expansion and low rotor loss.

FIG. 4 is a schematic diagram of the rotor structure of an amorphous alloy axial flux motor with wide field-weakening speed expansion and low rotor loss.

FIG. 5 is a schematic diagram of the rotor pole structure of an amorphous alloy axial flux motor with wide field-weakening speed expansion and low rotor loss.

Description of reference numbers:

Amorphous alloy axial flux motor with wide field weakening speed expansion and low rotor loss. In Figures 1, 2, 3, 4, and 5, the symbol 1 is the motor disk water channel; 2 is the end cover of the motor; 3 is the casing of the motor; 4 is the armature winding of the motor; 5 is the rotor bracket of the motor; 6 is the stator core yoke of the motor; 7 is the rotating shaft of the motor; 8 is the stator core tooth of the motor; 9 is the sintered NdFeB permanent magnet of the motor; 10 is the SMC soft magnetic pole of the motor; 11 is the notch of the rotor bracket of the motor; 12 is the bonded NdFeB permanent magnet of the motor; 13 is the bearing of the motor.

Detailed ways:

The present invention will be further described below in conjunction with the accompanying drawings:

The present invention provides an amorphous alloy axial flux motor with wide weak magnetic field expansion and low rotor loss, as shown in FIG. It is composed of rotor, permanent magnets and soft magnetic poles; it is characterized in that: the stator core is wound with amorphous alloy material, and the stator cores on both sides are directly in contact with the end covers with a circumferential disc-shaped water channel structure, and the amorphous alloy stator core is wound. Embedded in the casing, the double-layer distributed armature windings are embedded in the amorphous alloy stator core of the pear-shaped slot, the rotor of the motor adopts a single-disc structure, and the soft magnetic poles with low conductivity are made of low-powder metallurgy material SMC. , The two sides of the sintered NdFeB permanent magnet are bonded NdFeB permanent magnets with low conductivity. The number of pole pairs embedded in the rotor bracket is equal, and the permanent magnets and soft magnetic poles are side by side without gaps. The number of pole pairs between the permanent magnet and the soft magnetic pole is equal. , and are embedded in the high-strength stainless steel rotor bracket in an up and down arrangement. The upper end of the rotor bracket is notched, and the rotor bracket embedded with the magnetic poles is sleeved on the rotating shaft of the motor. The rotating shaft is supported at the center of the end cover through a bearing.

As shown in Figures 1 and 2, it is a schematic diagram of an amorphous alloy axial flux motor with wide field-weakening speed and low rotor loss. The stator iron cores 6 and 8 are wound with amorphous alloy materials. The stator iron cores 6 and 8 on both sides are directly in contact with the end cover with the circumferential disc-shaped water channel 1 structure. The amorphous alloy stator iron cores 6 and 8 are embedded in the casing. The double-layer distributed armature winding 5 is embedded in the amorphous alloy stator cores 6 and 8 of the pear-shaped slot. The rotor of the motor adopts a single-disc structure, and the soft magnetic pole 10 with low conductivity is made of low-powder metallurgy material SMC. , both sides of the sintered NdFeB permanent magnet 9 are bonded NdFeB permanent magnets 12 with low electrical conductivity. The NdFeB permanent magnets 9 and 12 are equal to the number of pole pairs of the soft magnetic pole 10, and they are arranged up and down and embedded in high-strength stainless steel. In the rotor bracket 5, the upper end of the rotor bracket is provided with a slot 11, the rotor bracket 5 embedded with the magnetic poles is sleeved on the rotating shaft 7 of the motor, and the two ends of the casing 3 are respectively provided with end covers 2, and the rotating shaft 7 of the motor passes through the bearing 8 Supported in the center of the end cap 2 .

As shown in Figure 3, it is a schematic diagram of the stator structure of an amorphous alloy axial flux motor with wide weak field expansion and low rotor loss. The lossy amorphous alloy strip is wound along the radial direction of the motor, and is closely attached to both sides of the end cover 2 with the circumferential disc-shaped water channel 1. The armature winding 4 of the stator scattered copper wire is made of a type that can increase the reluctance torque. Double layer fractional slot distributed winding.

As shown in Figure 4, it is a schematic diagram of the rotor structure of the amorphous alloy axial flux motor with wide weak field expansion and low rotor loss. It is made of low powder metallurgy material SMC. The number of NdFeB permanent magnets 9, 12 and SMC soft magnetic pole 10 are equal in pole pairs, and they are arranged up and down and embedded in the high-strength stainless steel rotor bracket 5. The rotor bracket with magnetic poles is embedded in it. 5 is set on the shaft 7 of the motor. Adopting this structure is beneficial to reduce the eddy current loss on the permanent magnets 9 and 12, and at the same time, it is also beneficial to save the amount of the permanent magnets 9 and 12, reduce the cost, and improve the performance of the motor.

As shown in Figure 5, it is a schematic diagram of the rotor pole structure of an amorphous alloy axial flux motor with wide weak magnetic expansion speed and low rotor loss. Both sides of the sintered NdFeB permanent magnets 9 are bonded NdFeB permanent magnets 12 with low electrical conductivity. , Since the harmonic magnetic field mainly acts on the surface of the bonded permanent magnet with low conductivity, it can effectively weaken the rotor eddy current loss.

The working process of the present invention is as follows:

The invention proposes an amorphous alloy axial flux motor with wide weak magnetic expansion speed and low rotor loss. The stator iron core is made of amorphous alloy strips and wound in the radial direction, and then the wound stator iron core is wound along the radial direction. Pear-shaped grooves are radially opened, permanent magnets and soft magnetic poles are embedded in the stainless steel rotor bracket, and double-layer distributed armature windings are embedded in the stator core. The armature windings are respectively supplied with three-phase sinusoidal alternating current with a difference of 120°, and then the soft magnetic poles at the corresponding positions of the rotor are magnetized, so that the soft magnetic poles on the rotor and the permanent magnets work together to generate a synthetic magnetic field. The alloy stator core is closed, and under the action of the electromagnetic field, the motor rotor rotates under the support of the bearing to output mechanical energy. Because the invention proposes an amorphous alloy axial flux motor structure with wide weak magnetic expansion speed and low rotor loss, it can effectively save the amount of permanent magnets, reduce the eddy current loss of the rotor, and make full use of the reluctance torque of the motor. It inherits the characteristics of high power density, high torque density and high efficiency of the traditional axial flux permanent magnet motor, and at the same time improves the weak field speed expansion capability of the axial flux motor.

Conclusion: In the amorphous alloy axial flux motor with wide weak magnetic field expansion speed and low rotor loss described in the present invention, the stator core is replaced by the traditional silicon steel sheet with the amorphous alloy strip which has a significant inhibitory effect on the core loss. Divide the permanent magnets on the rotor of the traditional axial flux permanent magnet synchronous motor into two parts, and replace part of them with soft magnetic poles pressed by powder metallurgy material SMC. Thereby increasing the speed range of the motor to improve its driving performance. Both sides of the sintered NdFeB permanent magnet are bonded NdFeB permanent magnets with low conductivity, and the upper end of the rotor bracket is slotted to effectively weaken the rotor eddy current loss. Compared with the traditional axial-flux permanent magnet synchronous motor, the axial-flux motor has larger inductance of the AC-direction axis, lower rotor loss, and can make full use of the magnetic field generated by the unequal inductance of the AC-direction axis of the axial-flux motor. Resistance torque, with a wider range of weak field expansion.

Claims (3)

1. an amorphous alloy axial flux motor with a wide weak magnetic field expansion speed and low rotor loss, comprising a double stator structure and a single rotor structure, and the rotor structure is located in the middle of the two stator structures, and is characterized in that: The stator structure comprises: a stator yoke portion (6) and a stator tooth portion (8) formed by winding an amorphous alloy material; the stator yoke portion (6) is in direct contact with the end cover (2); the stator yoke portion (6) and the stator teeth (8) together form the stator core; The end covers (2) at both ends of the casing (3) are provided with circumferential disc-shaped water channels (1); The double-layer distributed armature winding (4) is embedded in the pear-shaped slot of the stator core; The rotor structure is a single-disk structure, comprising a stainless steel rotor bracket (5), permanent magnets and soft magnetic poles embedded in the rotor bracket (5) arranged up and down; the number of pole pairs of the permanent magnets and the soft magnetic poles is equal; The soft magnetic pole is specifically a low-conductivity SMC soft magnetic pole (10); The permanent magnets are specifically sintered NdFeB permanent magnets (9) and low-conductivity bonded NdFeB permanent magnets (12) on both sides thereof; The rotor bracket (5) is sleeved on the motor shaft; Permanent magnets and soft magnetic poles are arranged on the rotor support (5) in a fan shape evenly distributed around the circumference; the soft magnetic poles are located on the side close to the motor shaft, and the permanent magnets are located on the side away from the motor shaft; the permanent magnets are of a three-layer structure, sintered NdFeB The permanent magnet (9) is sandwiched between two bonded NdFeB permanent magnets (12). 2 . The amorphous alloy axial flux motor with wide weak magnetic field expansion and low rotor loss according to claim 1 , wherein the stator iron core adopts a low-loss amorphous alloy sheared into a pear-shaped slot structure. 3 . The strip is wound along the radial direction of the motor, and is closely attached to both sides of the end cover with the circumferential disc-shaped water channel. The armature winding (4) of the stator scattered copper wire adopts a double-layer fractional slot distributed winding. 3 . The amorphous alloy axial flux motor with wide weak magnetic field expansion and low rotor loss according to claim 1 , wherein a slot ( 11 ) is formed on the outer circumference of the rotor support ( 5 ). 4 .

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