CN113364155A

CN113364155A - Single-phase brushless direct current motor and electrical equipment

Info

Publication number: CN113364155A
Application number: CN202010146155.1A
Authority: CN
Inventors: 葛梦; 吴迪; 龚黎明; 诸自强
Original assignee: Guangdong Welling Motor Manufacturing Co Ltd; Midea Welling Motor Technology Shanghai Co Ltd
Current assignee: Guangdong Welling Motor Manufacturing Co Ltd; Midea Welling Motor Technology Shanghai Co Ltd
Priority date: 2020-03-05
Filing date: 2020-03-05
Publication date: 2021-09-07

Abstract

The invention provides a single-phase brushless direct current motor and electrical equipment. The single-phase brushless DC motor includes: a stator and a rotor. The stator comprises a stator iron core, the stator iron core comprises a stator magnetic yoke and an even number of stator teeth connected with the stator magnetic yoke, any stator tooth comprises a tooth body extending along the radial direction and a tooth crown connected with the tail end of the tooth body, the tooth crown comprises two pole shoes, and the two pole shoes extend towards the two sides of the corresponding tooth body along the rotation direction of the rotor; the number of poles of the rotor is three times the number of stator teeth. Through the design, the number of pole pairs of the stator and the rotor is unequal, and the rotor magnetic field can generate more working harmonics under the action of the modulated rotor magnetic field and the stator magnetic field, so that the torque amplification effect of the vernier permanent magnet motor is realized, the output torque of the motor is increased, and the operation efficiency of the motor is improved. Meanwhile, the counter electromotive force of the motor is lower in harmonic content, the waveform is more sinusoidal, the motor runs more stably, the torque fluctuation is smaller, and the improvement of the vibration noise performance of the motor is facilitated.

Description

Single-phase brushless direct current motor and electrical equipment

Technical Field

The invention relates to the technical field of motors, in particular to a single-phase brushless direct current motor and electrical equipment comprising the same.

Background

The single-phase brushless direct current has the characteristics of small volume, light weight, simple structure, low manufacturing cost and the like, and is often applied to small-power equipment such as water pumps, refrigerator fans, computer driving motors and the like. The single-phase direct current brushless motor that adopts among the prior art is four groove quadrupole structures, has following problem: the output torque is small, the efficiency is low, and the torque fluctuation is large.

Disclosure of Invention

In order to solve at least one of the above technical problems, an object of the present invention is to provide a single-phase brushless dc motor.

Another object of the present invention is to provide an electric apparatus including the above-mentioned single-phase brushless dc motor.

In order to achieve the above object, a first aspect of the present invention provides a single-phase brushless dc motor, including: the stator comprises a stator core and a winding wound on the stator core, the stator core comprises a stator magnetic yoke and an even number of stator teeth connected with the stator magnetic yoke, any one of the stator teeth comprises a tooth body extending along the radial direction and a tooth crown connected with the tail end of the tooth body, and the tooth crown comprises two pole shoes extending towards two sides of the corresponding tooth body along the rotation direction of the rotor; and the rotor is matched with the stator and is suitable for rotating relative to the stator, and the number of poles of the rotor is three times that of the teeth of the stator.

In the single-phase brushless direct-current motor provided by the technical scheme of the first aspect of the invention, the number of poles of the stator is N (N is an even number), the number of poles of the rotor is 3N, and 2N pole shoes of the stator play a role in magnetic field modulation. Through the design, the number of pole pairs of the stator and the rotor is unequal, and the rotor magnetic field can generate more working harmonics under the action of the modulated rotor magnetic field and the stator magnetic field, so that the torque amplification effect of the vernier permanent magnet motor is realized, the output torque of the motor is increased, and the operation efficiency of the motor is improved. Meanwhile, the design enables harmonic content in the counter electromotive force of the motor to be lower, the waveform to be more sinusoidal, the motor to run more stably, torque fluctuation to be smaller, and improvement of vibration noise performance of the motor is facilitated.

Specifically, in the present application, the pole shoe of the stator functions as a modulation means and performs a magnetic field modulation function. The number of the stator teeth is N, each tooth body is provided with a left pole shoe and a right pole shoe, the number of the pole shoes is 2N, namely the number of the modulation units is 2N. As the motor is a single-phase motor, the number of pole pairs of the stator is N/2, the number of pole pairs of the rotor is 3N/2, and the number of pole pairs of the stator is not equal to the number of pole pairs of the rotor. However, the sum of the number of pole pairs of the stator and the number of pole pairs of the rotor is equal to the number of modulation units. Therefore, the rotor magnetic field can act with the stator magnetic field after passing through the modulation unit to generate torque, and the magnetic field modulation torque amplification effect is realized. After modulation, the motor has higher content of no-load counter electromotive force fundamental waves, and is beneficial to increasing the output torque of the motor and improving the running efficiency of the motor. And the harmonic content in the modulated counter electromotive force is lower, the waveform is more sinusoidal, so that the motor runs more stably, the torque fluctuation is smaller, and the vibration noise performance of the motor is favorably improved.

In addition, the single-phase brushless dc motor in the above technical solution provided by the present invention may further have the following additional technical features:

in the above technical solution, the tooth crown faces the end face of the rotor and is provided with a groove at a position opposite to the tooth body, and the groove is located between the two pole shoes.

The tooth crown is provided with the groove close to the air gap side, so that the magnetic resistance of a magnetic leakage magnetic circuit can be increased, and the interpolar magnetic leakage is reduced, thereby improving the output power of the motor and promoting the utilization rate of the permanent magnet.

In the technical scheme, the cross section of the groove is symmetrically arranged relative to the center line of the cross section of the tooth body; or the cross section of the groove is asymmetrically arranged relative to the center line of the cross section of the tooth body.

The cross section of the groove is symmetrically arranged relative to the central line of the cross section of the tooth body, so that the structure of the stator core is regular, and the stator core is convenient to machine and form.

The cross section of the groove is asymmetrically arranged relative to the central line of the cross section of the tooth body, so that a certain offset angle is generated between the magnetic field of the stator and the magnetic field of the rotor, and a certain starting angle is generated when the motor is started, thereby avoiding the dead point position, realizing self-starting and solving the problem of the starting dead point of the single-phase motor. Meanwhile, the asymmetric structure of the groove enables the rotor to have different bidirectional starting capabilities, and the rotor is particularly suitable for application occasions with different requirements on the bidirectional starting capabilities, such as electric tools, window lifting mechanisms and the like.

It is understood that, in the present application, the center line of the cross section of the tooth body refers to a straight line that perpendicularly intersects the center axis of the stator yoke and extends in the radial direction of the stator yoke and bisects the cross section of the tooth body.

In the above technical solution, two ends of the cross section of the groove along the rotation direction of the rotor are respectively marked as a first end and a second end, and a distance between the first end and a center line of the cross section of the tooth body is greater than or less than a distance between the second end and the center line of the cross section of the tooth body.

By the design, the center line of the stator magnetic field and the center line of the rotor magnetic field are not overlapped, and a certain starting angle is generated when the motor is started, so that the dead point position is avoided, and the starting is realized.

In the technical scheme, the cross section of the groove is U-shaped, V-shaped or arc-shaped.

The cross section of the groove is U-shaped, the structure is simple, and the processing and forming are convenient.

The cross section of the groove is V-shaped or arc-shaped, so that a non-uniform air gap is conveniently formed between the stator and the rotor, dead point positions are favorably avoided, the motor is convenient to start, and the groove is simple in structure and convenient to machine and form.

In the above technical solution, a width of the groove in a rotation direction of the rotor is greater than a width of the tooth body in the rotation direction of the rotor.

By the design, on one hand, the magnetic resistance of a magnetic leakage magnetic circuit is further increased, and the inter-pole magnetic leakage is further reduced, so that the output power of the motor is further improved, and the utilization rate of the permanent magnet is further improved; on the other hand, through the position at the circumference both ends of control recess, two pole shoes of the same tooth body both sides of being convenient for form asymmetric structure, and then form asymmetric air gap structure between stator and rotor, this can make the center of stator magnetic field and rotor magnetic field not coincide to realize the motor and start.

Of course, the width of the groove in the rotation direction of the rotor may also be equal to or smaller than the width of the tooth body in the rotation direction of the rotor.

In any of the above solutions, the distance between the pole shoes and the rotor varies along the circumferential direction of the rotor, so that a non-uniform air gap is formed between the stator and the rotor.

By controlling the distance between the pole shoe and the rotor, a non-uniform air gap is formed between the stator and the rotor, so that dead point positions can be avoided, and the motor can be started conveniently. Meanwhile, an unequal air gap is formed between each pole shoe and the rotor, so that the equivalent air gap of the motor is smaller, and higher output performance can be still maintained while starting is realized.

In any of the above technical solutions, two pole shoes of the same stator tooth are respectively marked as a first pole shoe and a second pole shoe, the first pole shoe and the second pole shoe form an asymmetric structure with respect to a perpendicular plane of the tooth body of the same stator tooth, and the perpendicular plane passes through a central axis of the stator yoke.

The first pole shoe and the second pole shoe are designed asymmetrically, so that a certain offset angle can be generated between the magnetic field of the stator and the magnetic field of the rotor, the self-starting of the single-phase motor is realized, and the problem of starting dead points of the single-phase motor is solved.

It is understood that in the present application, the perpendicular plane of the tooth body refers to a plane passing through the central axis of the stator yoke and perpendicularly bisecting the tooth body. The projection of the perpendicular plane on the cross section of the tooth body is the central line of the cross section of the tooth body.

Of course, the first pole shoe and the second pole shoe of the same stator tooth can also be symmetrically arranged relative to the vertical plane of the corresponding tooth body, so that the structure of the stator core is simplified, the processing and the forming are convenient, symmetrical equal-thickness air gaps are also convenient to form, the vibration and the noise of the motor are reduced, the motor operates more stably, and the starting stability of the motor is enhanced.

In the above technical solution, the length of the surface of the first pole shoe facing the rotor in the rotation direction of the rotor is smaller or larger than the length of the surface of the second pole shoe facing the rotor in the rotation direction of the rotor; and/or the area of the surface of the first pole shoe facing the rotor is smaller or larger than the area of the surface of the second pole shoe facing the rotor.

The surface of the pole shoe facing the rotor may be referred to as the working surface of the pole shoe (or pole face of the pole shoe). The working surface of the first pole shoe and the working surface of the second pole shoe of the same stator tooth are unequal in circumferential length, an asymmetric design is formed, and an asymmetric air gap structure is formed by an air gap between the stator and the rotor. This can make the center of stator magnetic field and rotor magnetic field not coincide, makes to produce certain offset angle between stator magnetic field and the rotor magnetic field to realize the motor self-starting.

In a similar way, the areas of the working surface of the first pole shoe and the working surface of the second pole shoe of the same stator tooth are not equal, and an asymmetric design is formed, so that an asymmetric air gap structure is formed between the stator and the rotor. This can make the center of stator magnetic field and rotor magnetic field not coincide, makes to produce certain offset angle between stator magnetic field and the rotor magnetic field to realize the motor self-starting.

In the above technical solution, a distance between a surface of the first pole shoe facing the rotor and a central axis of the stator yoke is denoted as a first distance, and a distance between a surface of the second pole shoe facing the rotor and the central axis of the stator yoke is denoted as a second distance; at least one of the first distance and the second distance is gradually decreased or gradually increased in a rotation direction of the rotor; and/or at least one of a radial thickness of the first pole piece and a radial thickness of the second pole piece taper in a direction away from the corresponding tooth body.

The distance between the working surface of the pole shoe and the central axis of the stator magnet yoke is gradually increased or reduced, so that an air gap with non-uniform thickness is conveniently generated between the pole shoe and the permanent magnet of the rotor, dead point positions are favorably avoided, the motor is convenient to start, the permanent magnet of the rotor can adopt a regular equal-thickness structure, and the structure of the rotor is simplified. Meanwhile, unequal air gaps are conveniently formed between each pole shoe and the rotor, so that the equivalent air gap of the motor is smaller, and higher output performance can be still maintained while starting is realized.

The radial thickness of pole shoe reduces along the direction of keeping away from corresponding tooth body (promptly with the tooth body that the pole shoe corresponds and is connected) gradually for the magnetic resistance of pole shoe increases along the direction of keeping away from corresponding tooth body gradually, and the design like this can improve the air gap magnetic field waveform, makes the waveform smoother, and then makes the operation of motor more steady, start-up reliable.

In any of the above solutions, the rotor includes a rotor yoke and a permanent magnet; the radial thickness of the permanent magnet is gradually reduced or gradually increased along the rotation direction of the rotor.

The radial thickness of the permanent magnet is gradually reduced or gradually increased along the rotation direction of the rotor, an air gap with non-uniform thickness is conveniently generated between the pole shoe and the permanent magnet of the rotor, the dead point position is favorably avoided, the motor is convenient to start, the working surface of the pole shoe can adopt an arc surface which is concentric with the magnetic yoke of the stator, and the structure of the stator is simplified. Meanwhile, unequal air gaps are conveniently formed between each pole shoe and the rotor, so that the equivalent air gap of the motor is smaller, and higher output performance can be still maintained while starting is realized.

In any of the above technical solutions, the rotor is sleeved inside the stator; or the rotor is sleeved outside the stator.

The rotor is sleeved on the inner side of the stator to form an inner rotor motor. The rotor is sleeved outside the stator to form an outer rotor motor.

A technical solution of a second aspect of the present invention provides an electrical apparatus, including: an apparatus main body; and the single-phase brushless direct current motor according to any one of the first aspect solutions, connected to the apparatus main body.

The electric device provided by the second aspect of the present invention includes any one of the single-phase brushless dc motors in the first aspect, so that all the advantages of any one of the above-mentioned technical solutions are provided, and details are not repeated herein.

In the above technical solution, the electrical device may be, but is not limited to: water pump, refrigerator fan, computer, etc.

Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a schematic, diagrammatic view of a single-phase brushless DC motor in accordance with one embodiment of the present invention;

FIG. 2 is a no-load magnetic flux distribution diagram of the single-phase brushless DC motor shown in FIG. 1;

FIG. 3 is a comparison graph of no-load back emf waveforms for a single phase brushless DC motor of the present invention and a prior art single phase brushless DC motor;

FIG. 4 is a graph comparing the results of no-load back emf Fourier decomposition of a single phase brushless DC motor of the present invention and a prior art single phase brushless DC motor;

FIG. 5 is a schematic, diagrammatic view of a single-phase brushless DC motor in accordance with an embodiment of the present invention;

FIG. 6 is a schematic, diagrammatic view of a single-phase brushless DC motor in accordance with an embodiment of the present invention;

FIG. 7 is a schematic block diagram of an appliance according to some embodiments of the present invention.

Wherein, the correspondence between the reference numbers and the part names in fig. 1 to 7 is:

1, a stator, 11 stator iron cores, 111 stator yokes, 112 tooth bodies, 113 tooth crowns, 1131 grooves, 1132 first pole shoe, 1133 second pole shoe and 12 windings;

2 rotor, 21 rotor yoke, 22 permanent magnet;

100 electrical equipment, 102 equipment main body and 104 single-phase brushless direct current motor.

Detailed Description

In order that the above objects, features and advantages of the present invention can be more clearly understood, a more particular description of the invention will be rendered by reference to the appended drawings. It should be noted that the embodiments and features of the embodiments of the present application may be combined with each other without conflict.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced in other ways than those specifically described herein, and therefore the scope of the present invention is not limited by the specific embodiments disclosed below.

A single-phase brushless dc motor and an electric device according to some embodiments of the present invention will be described with reference to fig. 1 to 7.

As shown in fig. 1, 5 and 6, an embodiment of the first aspect of the present invention provides a single-phase brushless dc motor 104, including: a stator 1 and a rotor 2.

Specifically, the stator 1 includes a stator core 11 and a winding 12 wound around the stator core 11. The stator core 11 includes a stator yoke 111 and an even number of stator 1 teeth connected to the stator yoke 111. Each stator 1 tooth includes a tooth body 112 extending in the radial direction and a crown 113 connected to the tip of the tooth body 112. The tooth crown 113 includes two pole shoes extending toward both sides of the corresponding tooth body 112 in the rotational direction of the rotor 2.

The rotor 2 is fitted with the stator 1 and is adapted to rotate relative to the stator 1, and the number of poles of the rotor 2 is three times the number of teeth of the stator 1.

In the single-phase brushless dc motor 104 according to the embodiment of the first aspect of the present invention, the number of poles of the stator 1 is N (N is an even number), the number of poles of the rotor 2 is 3N (i.e., 3 times of N), and 2N pole shoes of the stator 1 (i.e., 2 times of N) perform a magnetic field modulation function. Through the design, the number of pole pairs of the stator 1 and the rotor 2 is not equal, and the rotor magnetic field can generate more working harmonics under the action of the modulated rotor magnetic field and the stator magnetic field, so that the torque amplification effect of the vernier permanent magnet motor is realized, the output torque of the motor is increased, and the operation efficiency of the motor is improved. Meanwhile, the design enables harmonic content in the counter electromotive force of the motor to be lower, the waveform to be more sinusoidal, the motor to run more stably, torque fluctuation to be smaller, and improvement of vibration noise performance of the motor is facilitated.

Specifically, in the present application, the pole shoe of the stator 1 functions as a modulation means and performs a magnetic field modulation. The number of the teeth of the stator 1 is N, each tooth body 112 is provided with a left pole shoe and a right pole shoe, and the number of the pole shoes is 2N, that is, the number of the modulation units is 2N. Since the motor is a single-phase motor, the number of pole pairs of the stator 1 is N/2 (i.e., half of N), and the number of pole pairs of the rotor 2 is 3N/2 (i.e., half of 3N), the number of pole pairs of the stator 1 is not equal to the number of pole pairs of the rotor 2. However, the sum of the number of pole pairs of the stator 1 and the number of pole pairs of the rotor 2 is equal to the number of modulation units. Therefore, the rotor magnetic field can act with the stator magnetic field after passing through the modulation unit to generate torque, and the magnetic field modulation torque amplification effect is realized. After modulation, the motor has higher content of no-load counter electromotive force fundamental waves, and is beneficial to increasing the output torque of the motor and improving the running efficiency of the motor. And the harmonic content in the modulated counter electromotive force is lower, the waveform is more sinusoidal, so that the motor runs more stably, the torque fluctuation is smaller, and the vibration noise performance of the motor is favorably improved.

In some embodiments, further, the tooth crown 113 is provided with a groove 1131 facing the end face of the rotor 2 and opposite to the tooth body 112, and as shown in fig. 1 and 2, the groove 1131 is located between the two pole shoes.

The grooves 1131 are formed in the tooth crown 113 close to the air gap side, so that the magnetic resistance of a magnetic leakage path can be increased, and the interpolar magnetic leakage is reduced, so that the output power of the motor is improved, and the utilization rate of the permanent magnet 22 is improved.

In some embodiments, the cross-section of the grooves 1131 is symmetrically disposed with respect to the centerline of the cross-section of the tooth body 112, as shown in fig. 1 and 2.

The cross section of the groove 1131 is symmetrically arranged relative to the center line of the cross section of the tooth body 112, so that the structure of the stator core 11 is regular and is convenient for processing and forming.

It is to be understood that, in the present application, the center line of the cross section of the tooth body 112 refers to a straight line perpendicularly intersecting the central axis of the stator yoke 111 and extending in the radial direction of the stator yoke 111 and bisecting the cross section of the tooth body 112.

In other embodiments, the cross-section of the groove 1131 is asymmetrically disposed with respect to a centerline of the cross-section of the tooth body 112, as shown in FIG. 5.

The cross section of the groove 1131 is asymmetrically arranged relative to the center line of the cross section of the tooth body 112, so that a certain offset angle is generated between the magnetic field of the stator and the magnetic field of the rotor, and further a certain starting angle is generated when the motor is started, so that a dead point position is avoided, self-starting is realized, and the problem of starting dead points of a single-phase motor is solved. Meanwhile, the asymmetric structure of the groove 1131 enables the rotor 2 to have different bidirectional starting capabilities, and is particularly suitable for application occasions with different requirements on the bidirectional starting capabilities, such as electric tools and window lifting mechanisms.

Further, both ends of the cross section of the groove 1131 in the rotation direction of the rotor 2 are respectively referred to as a first end and a second end, and the distance between the first end and the center line of the cross section of the tooth body 112 is greater than or less than the distance between the second end and the center line of the cross section of the tooth body 112, as shown in fig. 5.

In some embodiments, particularly, the cross section of the groove 1131 is U-shaped, as shown in fig. 1 and 2, so that the structure is simple and the processing and forming are convenient.

In other embodiments, the cross section of the groove 1131 is V-shaped or arc-shaped, so that a non-uniform air gap is formed between the stator 1 and the rotor 2, a dead point position is avoided, the motor is started conveniently, and the structure is simple and is convenient for machining and forming.

Further, the width of the groove 1131 in the rotation direction of the rotor 2 is larger than the width of the tooth body 112 in the rotation direction of the rotor 2, as shown in fig. 1, 5, and 6.

By the design, on one hand, the magnetic resistance of the magnetic leakage magnetic circuit is further increased, and the interpolar magnetic leakage is further reduced, so that the output power of the motor is further improved, and the utilization rate of the permanent magnet 22 is further improved; on the other hand, by controlling the positions of the two circumferential ends of the groove 1131, the two pole shoes on the two sides of the same tooth body 112 form an asymmetric structure, and then an asymmetric air gap structure is formed between the stator 1 and the rotor 2, which causes the centers of the stator magnetic field and the rotor magnetic field to be misaligned, thereby realizing the starting of the motor.

Of course, the width of the groove 1131 in the rotation direction of the rotor 2 may be equal to or smaller than the width of the tooth body 112 in the rotation direction of the rotor 2.

In some embodiments, further, the spacing between the pole shoes and the rotor 2 varies along the circumference of the rotor 2 to create a non-uniform air gap between the stator 1 and the rotor 2, as shown in fig. 6.

By controlling the distance between the pole shoe and the rotor 2, a non-uniform air gap is formed between the stator 1 and the rotor 2, so that the dead point position is avoided, and the motor is started conveniently. Meanwhile, an unequal air gap is formed between each pole shoe and the rotor 2, so that the equivalent air gap of the motor is smaller, and higher output performance can be still maintained while starting is realized.

In other embodiments, the distance between the pole shoe and the rotor 2 is kept constant along the circumferential direction of the rotor 2, as shown in fig. 1 and 5, so that an air gap with the same thickness is formed between the pole shoe and the rotor 2, which is beneficial to reducing vibration and noise of the motor, enabling the motor to run more smoothly, and enhancing the starting stability of the motor.

In some embodiments, the two pole pieces of the same stator 1 tooth are respectively identified as a first pole piece 1132 and a second pole piece 1133. The first pole piece 1132 and the second pole piece 1133 form an asymmetric structure with respect to a median vertical plane of the tooth body 112 of the same stator 1 tooth, which passes through the central axis of the stator yoke 111, as shown in fig. 5 and 6.

The asymmetric design of the first pole piece 1132 and the second pole piece 1133 can generate a certain offset angle between the magnetic field of the stator and the magnetic field of the rotor, thereby realizing the self-starting of the single-phase motor and solving the starting dead point problem of the single-phase motor.

It is understood that, in the present application, the perpendicular plane of the tooth body 112 refers to a plane passing through the central axis of the stator yoke 111 and vertically bisecting the tooth body 112. The projection of the plane of median height on the cross section of the tooth body 112 is the center line of the cross section of the tooth body 112.

In other embodiments, the first pole piece 1132 and the second pole piece 1133 of the same stator 1 tooth may also be symmetrically disposed about the perpendicular bisector of the corresponding tooth body 112, as shown in fig. 1 and 2. The structure of the stator core 11 is simplified, the processing and forming are convenient, symmetrical equal-thickness air gaps are convenient to form, the vibration and noise of the motor are reduced, the motor operates more stably, and the starting stability of the motor is enhanced.

In one embodiment, the length of the surface of the first pole shoe 1132 facing the rotor 2 in the rotation direction of the rotor 2 is smaller than the length of the surface of the second pole shoe 1133 facing the rotor 2 in the rotation direction of the rotor 2, as shown in fig. 5.

The surface of the pole shoe facing the rotor 2 may be referred to as the working surface of the pole shoe (or pole face of the pole shoe). The working surfaces of the first pole shoe 1132 and the second pole shoe 1133 of the same stator 1 tooth have different circumferential lengths, so as to form an asymmetric design, so that the air gap between the stator 1 and the rotor 2 also forms an asymmetric air gap structure. This can make the center of stator magnetic field and rotor magnetic field not coincide, makes to produce certain offset angle between stator magnetic field and the rotor magnetic field to realize the motor self-starting.

In one embodiment, the area of the surface of the first pole shoe 1132 facing the rotor 2 is smaller than the area of the surface of the second pole shoe 1133 facing the rotor 2.

The areas of the working surfaces of the first pole pieces 1132 and the second pole pieces 1133 of the same stator 1 tooth are not equal, and an asymmetric design is also formed, so that an asymmetric air gap structure is also formed by an air gap between the stator 1 and the rotor 2. This can make the center of stator magnetic field and rotor magnetic field not coincide, makes to produce certain offset angle between stator magnetic field and the rotor magnetic field to realize the motor self-starting.

In one embodiment, the distance between the surface of the first pole piece 1132 facing the rotor 2 and the central axis of the stator yoke 111 is denoted as a first distance, and the distance between the surface of the second pole piece 1133 facing the rotor 2 and the central axis of the stator yoke 111 is denoted as a second distance. At least one of the first distance and the second distance is gradually decreased or gradually increased in the rotation direction of the rotor 2, as shown in fig. 6.

The distance between the working surface of the pole shoe and the central axis of the stator magnetic yoke 111 is gradually increased or gradually reduced, so that an air gap with non-uniform thickness is conveniently generated between the pole shoe and the permanent magnet 22 of the rotor 2, the dead point position is favorably avoided, the motor is convenient to start, the permanent magnet 22 of the rotor 2 can adopt a regular uniform-thickness structure, and the structure of the rotor 2 is simplified. Meanwhile, unequal air gaps are conveniently formed between each pole shoe and the rotor 2, so that the equivalent air gap of the motor is smaller, and higher output performance can be still maintained while starting is realized.

In one embodiment, at least one of the radial thickness of the first pole piece 1132 and the radial thickness of the second pole piece 1133 tapers in a direction away from the corresponding tooth body 112, as shown in fig. 1, 5, and 6.

The radial thickness of the pole shoe is gradually reduced along the direction far away from the corresponding tooth body 112 (namely the tooth body 112 correspondingly connected with the pole shoe), so that the magnetic resistance of the pole shoe is gradually increased along the direction far away from the corresponding tooth body 112, the design can improve the waveform of an air gap magnetic field, the waveform is smoother, and the running of the motor is more stable and the starting is reliable.

In any of the above embodiments, the rotor 2 comprises a rotor yoke 21 and permanent magnets 22, as shown in fig. 1. The radial thickness of the permanent magnets 22 gradually decreases or gradually increases in the rotational direction of the rotor 2.

The radial thickness of the permanent magnet 22 is gradually reduced or gradually increased along the rotation direction of the rotor 2, an air gap with non-uniform thickness is conveniently generated between the pole shoe and the permanent magnet 22 of the rotor 2, the dead point position is favorably avoided, the motor is convenient to start, the working surface of the pole shoe can adopt an arc surface which is concentric with the stator magnetic yoke 111, and the structure of the stator 1 is simplified. Meanwhile, unequal air gaps are conveniently formed between each pole shoe and the rotor 2, so that the equivalent air gap of the motor is smaller, and higher output performance can be still maintained while starting is realized.

In some embodiments, the rotor 2 is sleeved inside the stator 1 to form an inner rotor 2 motor.

In other embodiments, the rotor 2 is sleeved outside the stator 1, as shown in fig. 1, 5 and 6, to form an outer rotor 2 motor.

As shown in fig. 7, an embodiment of the second aspect of the present invention provides an electric apparatus 100, including: an apparatus body 102 and a single-phase brushless dc motor 104 as in any of the embodiments of the first aspect. A single-phase brushless dc motor 104 is connected to the apparatus main body 102.

The electric device 100 provided in the embodiment of the second aspect of the present invention includes the single-phase brushless dc motor 104 in any one of the embodiments of the first aspect, so that all the advantages of any one of the embodiments described above are provided, and details thereof are not repeated herein.

In the above embodiment, the electric device 100 may be, but is not limited to: water pump, refrigerator fan, computer, etc.

Specifically, the electric device 100 is a water pump, the device body 102 includes an impeller, and the single-phase brushless dc motor 104 is connected to the impeller.

The electrical appliance 100 is a refrigerator or a refrigerator blower, and the appliance body 102 includes an impeller to which a single-phase brushless dc motor 104 is connected.

The electrical apparatus 100 is a computer, and the apparatus main body 102 includes an impeller to which a single-phase brushless dc motor 104 is connected.

Several specific examples are described in detail below.

Concrete example 1

Fig. 1 is a schematic view of a first specific example of the present invention.

In this example, the present invention provides a single-phase brushless dc motor including a stator 1 and a rotor 2 rotating relative to the stator 1. The stator 1 includes a stator core 11 and a winding 12 wound on the stator core 11. In the winding 12, the direction of current flow in conductors in the same slot is the same, and the direction of current flow in conductors in adjacent slots is opposite. The stator core 11 includes a stator yoke 111, a tooth body 112 (or stator tooth body) extending from the annular stator yoke 111 to the air gap side in the radial direction, and a tooth crown 113 formed at the tip of the tooth body, and the number N of stator teeth is an even number. The crown 113 is provided with a groove 1131 at a position close to the air gap side and opposite to the tooth body 112, and the width of the groove 1131 may be larger than the width of the tooth body 112. On the left and right sides of the groove 1131, there are circumferentially extending stator pole pieces (including a first pole piece 1132 and a second pole piece 1133). The rotor 2 comprises an annular rotor yoke 21 and a plurality of permanent magnets 22, and the polarities of adjacent permanent magnets are opposite.

Wherein, the number of the rotor poles is 3 times of the number of the stator poles, namely 3N.

The invention is a brushless DC motor, which adopts a DC power supply to supply power to the windings of the motor, and the current commutates once every 180 degrees of electrical angle, namely commutates once every (120/N) degrees of mechanical angle, so that the stator magnetic field and the rotor magnetic field always keep about 90 degrees of electrical angle in space, thereby driving the motor to rotate continuously.

In the invention, the stator pole shoe is used as a modulation unit and plays a role of magnetic field modulation. The number of the stator teeth is N, and each tooth part is provided with a left stator pole shoe and a right stator pole shoe, so that the number of the stator pole shoes is 2N, namely the number of the modulation units is 2N. As the motor is a single-phase motor, the number of the stator pole pairs is N/2, the number of the rotor pole pairs is 3N/2, and the number of the stator pole pairs and the number of the rotor pole pairs are not equal. But the sum of the number of the stator pole pairs and the number of the rotor pole pairs is equal to the number of the modulation units. Therefore, the rotor magnetic field can act with the stator magnetic field after passing through the modulation unit to generate torque, and the magnetic field modulation torque amplification effect is realized. After modulation, the motor has higher content of no-load counter electromotive force fundamental waves, and is beneficial to increasing the output torque of the motor and improving the running efficiency of the motor. And the harmonic content in the modulated counter electromotive force is lower, the waveform is more sinusoidal, so that the motor runs more stably, the torque fluctuation is smaller, and the improvement of the vibration noise performance of the motor is facilitated.

However, because the number of the rotor poles is more and the interpolar magnetic leakage is larger, in order to reduce the magnetic leakage of the rotor poles, improve the output of the motor and improve the utilization rate of the permanent magnet, the stator tooth crown is provided with the groove close to the air gap side, and the interpolar magnetic leakage is reduced by increasing the magnetic resistance of the magnetic leakage path. Fig. 2 is a magnetic force line distribution diagram when the motor is unloaded. It can be seen that the flux leakage between the permanent magnet poles is small after the grooves are arranged. In addition, the groove is positioned at the extension of the stator tooth body, and the width of the groove can be larger than that of the stator tooth body.

Further, fig. 3 is a comparison graph of back electromotive force waveforms of the single-phase brushless dc motor of the present invention and the single-phase brushless dc motor of the prior art when they are idle, and fig. 4 is a comparison graph of the results of the fourier decomposition of the idle back electromotive force of the single-phase brushless dc motor and the single-phase brushless dc motor. It can be seen that through the design, the motor no-load counter electromotive force has higher fundamental wave content, smaller harmonic distortion rate and more sinusoidal waveform. This is advantageous in improving the output torque of the motor and reducing torque ripple.

Concrete example 2

On the basis of the specific example 1, the cross section of the stator groove 1131 is asymmetric with respect to the center line of the stator tooth body. As shown in fig. 5, it can be seen that the distance from one end of the stator groove to the center line of the tooth body is d1, the distance from the other end of the groove to the center line of the tooth body is d2, and d1 ≠ d 2. By the design, the center line of the stator magnetic field and the center line of the rotor magnetic field are not overlapped, and a certain starting angle is generated when the motor is started, so that the dead point position is avoided, and the starting is realized.

In the above embodiments, the cross section of the groove may be V-shaped or arc-shaped.

Further, the first and

second pole pieces

1132 and 1133 are asymmetric about a centerline of the stator tooth body. Similarly, a certain offset angle can be generated between the stator magnetic field and the rotor magnetic field, so that the motor starting is realized.

Specific example 3

On the basis of the specific example 2, further, as shown in fig. 6, distances from the working surfaces of the first and

second pole pieces

1132 and 1133 to the center of the stator are not equal in the circumferential direction. Specifically, the first pole piece 1132 has an outer diameter that gradually decreases from its edge to the edge of the groove 1131, and the second pole piece 1133 has an outer diameter that gradually decreases from the edge of the groove 1131 to the edge of the pole piece.

Similarly, the first and

second pole pieces

1132 and 1133 may not have equal thicknesses or have different circumferential lengths.

Through the design, an asymmetric air gap structure can be formed, so that the centers of the magnetic fields of the stator and the rotor are not overlapped, and starting is realized. And an unequal air gap is separately arranged around each pole shoe, so that the equivalent air gap of the motor is smaller, and the higher output performance is still maintained while the starting is realized.

Similarly, the thickness of each permanent magnet in the rotor gradually decreases or gradually increases in the rotational direction of the rotor. Through the design, the offset between the stator magnetic field and the rotor magnetic field center line can be generated, and therefore starting is achieved.

In addition, the above examples are all outer rotor single-phase motors, but the structure is also applicable to inner rotor single-phase motors.

In conclusion, the single-phase brushless direct current motor can increase the average torque of the motor, reduce the flux leakage between poles, further improve the output performance of the motor and improve the operation efficiency of the motor.

In the present invention, the terms "first", "second", and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance; the term "plurality" means two or more unless expressly limited otherwise. The terms "mounted," "connected," "fixed," and the like are to be construed broadly, and for example, "connected" may be a fixed connection, a removable connection, or an integral connection; "coupled" may be direct or indirect through an intermediary. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "left", "right", "front", "rear", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the referred device or unit must have a specific direction, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention.

In the description herein, the description of the terms "one embodiment," "some embodiments," "specific embodiments," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A single-phase brushless dc motor, comprising:

the stator comprises a stator core and a winding wound on the stator core, the stator core comprises a stator magnetic yoke and an even number of stator teeth connected with the stator magnetic yoke, any one of the stator teeth comprises a tooth body extending along the radial direction and a tooth crown connected with the tail end of the tooth body, and the tooth crown comprises two pole shoes extending towards two sides of the corresponding tooth body along the rotation direction of the rotor; and

a rotor engaged with the stator and adapted to rotate relative to the stator, the number of poles of the rotor being three times the number of teeth of the stator.

2. The single-phase brushless DC motor according to claim 1,

the tooth crown faces to the end face of the rotor and is provided with a groove at a position opposite to the tooth body, and the groove is located between the two pole shoes.

3. The single-phase brushless DC motor according to claim 2,

the cross section of the groove is symmetrically arranged relative to the center line of the cross section of the tooth body; or

The cross section of the groove is asymmetrically arranged relative to the center line of the cross section of the tooth body.

4. The single-phase brushless DC motor according to claim 2,

the two ends of the cross section of the groove along the rotation direction of the rotor are respectively marked as a first end and a second end, and the distance between the first end and the center line of the cross section of the tooth body is larger than or smaller than the distance between the second end and the center line of the cross section of the tooth body.

5. The single-phase brushless DC motor according to claim 2,

the cross section of the groove is U-shaped, V-shaped or arc-shaped.

6. The single-phase brushless DC motor according to claim 2,

the width of the groove along the rotating direction of the rotor is larger than the width of the tooth body along the rotating direction of the rotor.

7. The single-phase brushless DC motor according to any one of claims 1 to 6,

the distance between the pole shoes and the rotor varies along the circumference of the rotor to form a non-uniform air gap between the stator and the rotor.

8. The single-phase brushless DC motor according to any one of claims 1 to 6,

the two pole shoes of the same stator tooth are respectively marked as a first pole shoe and a second pole shoe, the first pole shoe and the second pole shoe form an asymmetric structure relative to a middle vertical plane of the tooth body of the same stator tooth, and the middle vertical plane passes through the central axis of the stator magnet yoke.

9. The single-phase brushless DC motor according to claim 8,

the length of the surface of the first pole shoe facing the rotor in the rotation direction of the rotor is smaller or larger than the length of the surface of the second pole shoe facing the rotor in the rotation direction of the rotor; and/or

The area of the surface of the first pole shoe facing the rotor is smaller or larger than the area of the surface of the second pole shoe facing the rotor.

10. The single-phase brushless DC motor according to claim 8,

the distance between the surface of the first pole shoe facing the rotor and the central axis of the stator yoke is recorded as a first distance, and the distance between the surface of the second pole shoe facing the rotor and the central axis of the stator yoke is recorded as a second distance; at least one of the first distance and the second distance is gradually decreased or gradually increased in a rotation direction of the rotor; and/or

At least one of a radial thickness of the first pole piece and a radial thickness of the second pole piece tapers in a direction away from the corresponding tooth body.

11. The single-phase brushless DC motor according to any one of claims 1 to 6,

the rotor comprises a rotor yoke and a permanent magnet;

the radial thickness of the permanent magnet is gradually reduced or gradually increased along the rotation direction of the rotor.

12. The single-phase brushless DC motor according to any one of claims 1 to 6,

the rotor is sleeved on the inner side of the stator; or

The rotor is sleeved outside the stator.

13. An electrical device, comprising:

an apparatus main body; and

the single-phase brushless dc motor according to any one of claims 1 to 12, connected to the apparatus main body.