JP2000166135A - Brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-efficiency, high-torque brushless motor superior in productivity. SOLUTION: Teeth 13, nine in total, are formed at every 40 deg. of a central angle in a stator core 12 which constitutes a stator 11, and each stator coil of phases U, V, and W is wound concentratedly. At this time, an angle formed by one end side end edge of one tooth 13 and the other end side end edge of a tooth adjoining is set to 180 deg. or more by electrical angle. A groove 14, having a cross section in the shape of an equilateral triangle, is formed in the axial direction in the central part of the internal circumference side end surface of each tooth 13, and one side of this equilateral triangle is set to one-third of the width of the tooth 13. Additionally, an arc-shaped housing part 19, six in total, is formed at each 60 deg. of a central angle in a rotor core 17 which constitutes a rotor 16. At this time, each arc is formed with its protruded side pointing toward the center, and an arc-shaped permanent magnet 20 is inserted into each housing part 19. Moreover, a through-hole 22 having a circular cross section is formed in the axial direction on the side of the recession of each permanent magnet 20, in the peripheral brim part of the rotor core 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a 3n slot, 2n pole structure (n = 1, 2, 2) comprising a stator on which concentrated winding is performed and a rotor having a plurality of permanent magnets embedded therein.
3,...).

[0002]

2. Description of the Related Art IPM (Interior) in which permanent magnets are embedded
Permanent Magnet) As a brushless motor provided with a rotor, there is, for example, a configuration as described in JP-A-6-339240 or JP-A-6-339241, which is configured as shown in FIG.

[0003] That is, as shown in FIG.
U-phase stator windings 1U, 2U, V-phase stator windings 1V, 2V and W-phase stator windings 1W, 2W are inserted and arranged in twelve slots 3 formed in an annular stator core 2. It is configured. Here, openings 3 a are formed in the inner peripheral portion of the stator core 2 so as to correspond to the slots 3.

Further, the rotor 4 has a rotor core 6 fitted and fixed to the shaft 5, and four permanent magnets 8 having a substantially arc-shaped cross section in a storage portion 7 formed in the rotor core 6.
Are inserted from the axial direction. At this time, the rotor 4 is rotatably disposed inside the stator 1 with the inner periphery of the stator core 2 and a predetermined gap.
Further, the four permanent magnets 8 have N poles and S poles alternately magnetized.

[0005]

However, the above-mentioned IP
Conventional brushless motors provided with an M rotor often have a structure of multiple slots and four poles, so that the windings of the stator are generally distributedly wound. In the case of the distributed windings, the coil ends of the windings are large. Therefore, there is a problem that the copper loss tends to increase. In addition, since the productivity of the stator is poor in distributed winding, it is not suitable for mass production of motors.

In a conventional multi-slot type brushless motor provided with an IPM rotor, the magnet torque generated by the permanent magnet 8 on the rotor 4 side is represented by a solid line in FIG. 6 (where the horizontal axis indicates the mechanical angle). M, and the reluctance torque R, which is the difference between the ease of flow of the magnetic flux generated by the stator 1 in the gap between the adjacent permanent magnets 8 on the rotor 4 side and the ease of flow in other parts, is shown in FIG. The curve changes as indicated by the one-dot chain line.

As shown in FIG. 6, at the position of the electrical angle where the reluctance torque R becomes zero, the rotor 4
And the magnet torque M also becomes maximum at the same time as the holding torque becomes maximum. Therefore, the combined torque C of these two torques R and M becomes a curve shown by a two-dot chain line in FIG. 6, and the combined torque C is the reluctance torque. It takes the maximum value at the position where R becomes maximum.

At this time, there is a 90 ° electrical angle deviation between the position where the combined torque C is maximum, ie, the position where the reluctance torque R is maximum, and the position where the magnet torque M is maximum. When the motor drive at the maximum position of the motor 1 and the motor drive at the maximum position of the combined torque C are switched by the drive circuit including the same inverter, there is a problem that it is very difficult to control the timing of switching the current supply to each winding of the stator 1. .

Further, since the rotation speed of the motor depends on the magnitude of the magnet torque M, and there is a relationship that the motor rotation speed decreases when the magnet torque M is increased, a higher torque is required at the same rotation speed. It is effective to use reluctance torque that does not depend on the rotational speed in order to obtain it.However, with the conventional structure, the reluctance torque can be obtained even at the energized point where the magnet torque is smaller than that of the motor using only the magnet torque, that is, at the point where the rotational speed is high Although a higher torque can be obtained, it was impossible to obtain a higher torque by making good use of the maximum of the magnet torque and the maximum of the reluctance torque.

It is an object of the present invention to provide a brushless motor having high efficiency, high torque and excellent productivity.

[0011]

In order to solve the above-mentioned problems, the present invention provides a stator in which a plurality of magnetic teeth are formed by concentrating windings around a core, and a plurality of permanent magnets embedded therein. In a brushless motor having a 3n slot and a 2n pole structure (n = 1, 2, 3,...) Provided with a set rotor, one edge of the tooth and the other edge of the tooth adjacent to the tooth are formed. An electrical angle between the teeth is set to 180 ° or more, and an axial groove is formed on each of the core end surfaces corresponding to the end surfaces of the teeth.

According to such a configuration, the electrical angle between the one edge of the tooth and the other edge of the tooth adjacent to the tooth is set to 180 ° or more, so that the rotor is adjacent to the tooth. The electrical angle between the gap between the permanent magnets and the adjacent gap is larger than that of the adjacent magnets, and the magnetic flux generated by the stator in this gap is easier to flow than in other parts.

[0013] Therefore, the reluctance increases, the reluctance torque increases, and the maximum value of the combined torque of the magnet torque and the reluctance torque by the permanent magnet on the rotor side also increases.

The electrical angle between one edge of the tooth and the other edge of the tooth adjacent to the tooth is 1
By making the angle 80 ° or more, the difference between the phase in which the combined torque of the reluctance torque is maximized and the phase in which the magnet torque is maximized is smaller than in a case where such setting is not made, and the reluctance torque is used. The motor can be driven by a large combined torque obtained by combining this with the magnet torque.

Therefore, by rotating the motor with this combined torque, it is possible to obtain high torque with high efficiency even at the same rotational speed as compared with the conventional structure. Further, since the stator windings are concentratedly wound, productivity can be improved as compared with a distributed winding stator in a conventional multi-slot structure.

At this time, the permanent magnet to be embedded in the rotor may be either a flat plate or an arc.

Further, the present invention is characterized in that the cross section of each groove is triangular. In this case, the magnetic flux passing through the teeth is concentrated by the groove, and the efficiency can be improved. At this time, it is preferable that the triangle, which is the cross-sectional shape of the groove, is a regular triangle whose one side length is 1/3 of the tooth width t.

Further, the present invention is characterized in that an axial through hole is formed in an outer peripheral portion of each of the permanent magnets at a peripheral portion of the rotor. This makes it difficult for the generated magnetic flux of the permanent magnet to pass through the through-hole, so that the generated magnetic flux distribution of the permanent magnet becomes substantially trapezoidal. And the magnet torque can be increased.

Further, according to the present invention, each of the permanent magnets has a substantially arc-shaped cross section, and the convex side of each of the substantially arc-shaped permanent magnets is embedded toward the center of the rotor. It is characterized by.

This makes it very easy to process the embedding storage space in the rotor in comparison with the case where the convex side is embedded toward the outer periphery of the rotor. In addition, by making each permanent magnet substantially arc-shaped in cross section and embedding its convex side toward the center of the rotor, the area that can be arranged inside the rotor becomes larger than in the case of embedding a flat permanent magnet. Thus, a large amount of magnetic flux generated by the permanent magnet can be secured.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment in which the present invention is applied to a 9-slot, 6-pole brushless motor will be described with reference to FIGS. 1 is a plan view, FIG. 2 is a partially enlarged plan view, and FIGS. 3 and 4 are operation explanatory diagrams.

In FIG. 1, reference numeral 11 denotes a stator. Nine teeth 13 are formed on a stator core 12 at every central angle of 40 °.
The stator winding of each phase of V and W is concentratedly wound. Here, each of the teeth 13 has a constant width t, and is an edge in FIG.
The angle θ between the end and the end B in FIG. 2 which is the other end of the tooth 13 adjacent to the end is set to be 180 ° or more in electrical angle.

In FIG. 1, reference numeral 14 denotes a groove, which is formed in the axial direction at the center of the end face of the stator core 12 corresponding to the inner peripheral end face of each tooth 13 and has a regular triangular cross section. At this time, one side of the regular triangle is set to １ ／ of the width t of the teeth 13. As described above, when the grooves 14 each having a regular triangular cross section whose length of one side is １ ／ of the width t of the teeth 13 are formed in each of the teeth 13,
Is concentrated in this groove 14.

In FIG. 1, reference numeral 16 denotes a rotor,
A shaft insertion hole 18 (not shown) is formed at the center of the rotor core 17.
Six arc-shaped storage portions 19 are formed at every 0 ° so as to penetrate the rotor core 17 with its convex side toward the center, and an arc-shaped permanent magnet 20 is inserted into each storage portion 19 from the axial direction. Have been. Here, with the stator 11 having an inner circumference of the stator core 12 and a predetermined gap, the rotor 1
6 is rotatably arranged. In addition, the six permanent magnets 20 are magnetized such that N poles and S poles alternate.

Further, as shown in FIG.
On the concave side of each of the storage portions 19, a through hole 22 having a circular cross-section in the axial direction is provided at every central angle of 60 °. These through holes 22 are located on the center line of each of the permanent magnets 20, and the magnetic flux generated by each of the permanent magnets 20 is difficult to pass through each of the through holes 22. Therefore, as shown in FIG. Instead of an arc shape (two-dot chain line in FIG. 3), the shape becomes substantially trapezoidal (solid line in FIG. 3).
The gradient of the cut between the N pole and the S pole becomes large, and the magnet torque increases. In addition, A and B in FIG.
It corresponds to the A end and B end in the middle.

As described above, the angle between the end A of the tooth 13 (see FIG. 2) and the end B of the tooth 13 adjacent to the end 13 (see FIG. 2) becomes 180 ° or more in electrical angle. As a result, as shown in FIG. 4, the phase at which the reluctance torque R is maximized (that is, the combined torque C
Is the maximum phase) and the phase at which the magnet torque M is maximum is 10 ° in mechanical angle and 30 ° in electrical angle.
゜, which is much smaller than the conventional 90 ° shown in FIG.

The angle between the end A of the tooth 13 and the end B of the tooth 13 adjacent thereto is 180 electrical degrees.
゜, and is set to be larger than the electrical angle (<180 °) between the gap between the adjacent permanent magnets 20 and the adjacent gap, so that the stator 11 in the gap between the adjacent permanent magnets 20 Of the generated magnetic flux is larger than the ease of the flow in other parts.

Moreover, the magnetic flux passing through the teeth 13 is
4, the magnetic flux generated by the stator 11 becomes particularly easy to flow in the gap between the adjacent permanent magnets 20.
The difference between the generated magnetic flux and the ease with which it flows in other parts is further increased.

As a result, the reluctance increases, and the reluctance torque R indicated by the dashed line in FIG.
The maximum value of the combined torque C shown by the two-dot chain line in FIG. 4 obtained by combining the magnet torque M and the reluctance torque R by the permanent magnet 20 on the rotor 16 side shown by the solid line in FIG.

Thus, according to the above-described embodiment,
Since the difference between the phase at which the reluctance torque R is maximized and the phase at which the magnet torque M is maximized can be reduced to an electrical angle of 30 °, it is possible to use the reluctance torque R independent of the rotation speed. Permanent magnet 2
Motor drive using the combined torque C of the magnet torque M and the reluctance torque R due to 0 can be performed.

At this time, the magnetic flux passing through each tooth 13 is transferred to the groove 1 by the groove 14 having an equilateral triangular section.
4 and the reluctance torque R can be increased as described above.

Further, by forming the through holes 22 in the rotor core 17, the distribution of the magnetic flux generated by the permanent magnets 20 is made substantially trapezoidal, and the gradient of the cuts of the N pole and S pole of each permanent magnet 20 can be increased. And the magnet torque M can be increased.

Therefore, a larger reluctance torque R
And the magnet torque M, the combined torque C is much larger than in the prior art, so that even with the same motor rotation speed, a higher torque than the conventional structure (see FIG. 5) can be obtained with high efficiency. .

Further, since the stator windings are concentratedly wound, the productivity can be improved as compared with the conventional distributed winding stator in the multi-slot structure, and the brushless motor itself can be mass-produced.

Further, as described above, the difference between the phase at which the reluctance torque R is maximized (the phase at which the combined torque C is maximized) and the phase at which the magnet torque M is maximized can be made smaller than before. Therefore, even when the motor drive at the maximum position of the magnet torque M and the motor drive at the maximum position of the combined torque C are switched by a drive circuit including the same inverter, the winding to the windings of the stator 11 is performed at almost the same timing. The energization switching can be performed, and the control of the drive circuit in this case can be easily performed.

Further, when the embedding storage portion 19 is formed on the rotor 16 by processing, it is much easier to process than when embedding the convex side toward the outer peripheral side of the rotor 16. Furthermore, since each permanent magnet 20 has a substantially arc-shaped cross section and is buried with its convex side toward the center of the rotor 16, the area that can be arranged inside the rotor 16 is smaller than when a flat permanent magnet is buried. As a result, the magnetic flux generated by the permanent magnet can be increased, and the magnet torque M can be increased.

In the above-described embodiment, a case has been described in which the present invention is applied to a brushless motor having a 9-slot, 6-pole structure. In short, a brushless motor having a 3n-slot, 2n-pole (n = 1, 2, 3,...) Structure is used. The present invention can be applied to the present invention, and the same effect as the above-described embodiment can be obtained. Also, 3n slots,
The present invention can be expected to be applied not only to the 2n-pole structure but also to a brushless motor having a 9-slot, 8-pole structure or a 10-slot, 8-pole structure.

In the above-described embodiment, the case where the groove 14 formed in each tooth 13 is an equilateral triangle having a length of one side of 1/3 of the width t of the tooth 13 has been described. The cross-sectional shape of the groove is not limited to an equilateral triangle, and the cross-sectional shape of the groove may be an equilateral triangle or another triangle having a different side length, or may be other than a triangle. In short, the magnetic flux passing through the teeth 13 Any shape can be used as long as it can be concentrated in the groove.

Further, in the above embodiment, the permanent magnet 2
Although the case where 0 is a circular arc has been described, even when a flat permanent magnet is embedded in the rotor core 17, the same effect can be obtained by implementing the present invention similarly. .

Further, in the above-described embodiment, the case where the through-hole 22 has a circular cross section has been described, but the diameter of the through-hole 22 at this time is not particularly limited. On the other hand, the shape of the through hole is not limited to the above-described circular cross section.

Further, in the above-described embodiment, the case where the physical teeth 13 are formed on the stator core 12 has been described. However, it is not particularly necessary that the physical teeth 13 are formed, and the magnetic teeth are formed. It should just be.

The present invention is not limited to the above embodiment, and various changes other than those described above can be made without departing from the gist of the present invention.

[0043]

As described above, according to the first aspect of the present invention, the motor can be driven by using the reluctance torque and a large combined torque of the reluctance torque and the magnet torque. In comparison, it is possible to obtain high torque with high efficiency even at the same rotation speed.

In addition, since the stator windings are concentratedly wound, productivity can be improved as compared with a distributed winding stator in a conventional multi-slot structure, and mass production of the brushless motor itself becomes possible.

According to the second aspect of the present invention, since the magnetic flux passing through the teeth can be concentrated in the grooves, the reluctance torque can be increased, and the efficiency can be improved.

According to the third aspect of the present invention, since the through holes in the axial direction are formed in the outer portion of each permanent magnet, the magnetic flux generated by the permanent magnets hardly passes through the through holes.
The distribution of the generated magnetic flux of the permanent magnet becomes substantially trapezoidal, thereby making it possible to increase the gradient of the cuts between the N pole and the S pole of the permanent magnet to increase the magnet torque.

According to the fourth aspect of the present invention, when the storage space for embedding is formed in the rotor by machining, it is much more processed than when embedding the convex side toward the outer peripheral side of the rotor. It will be easier. In addition, by making each permanent magnet substantially arc-shaped in cross section and embedding its convex side toward the center of the rotor, the area that can be arranged inside the rotor becomes larger than in the case of embedding a flat permanent magnet. Thus, it is possible to secure a large amount of magnetic flux generated by the permanent magnet.

[Brief description of the drawings]

FIG. 1 is a plan view of an embodiment of the present invention.

FIG. 2 is an enlarged plan view of a part of one embodiment.

FIG. 3 is an operation explanatory diagram of one embodiment.

FIG. 4 is a diagram illustrating an operation of the embodiment.

FIG. 5 is a partially cut plan view of a conventional example.

FIG. 6 is an operation explanatory diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Stator 12 Stator core 13 Teeth 14 Groove 16 Rotor 20 Permanent magnet 22 Through hole

Claims (4)

[Claims] 1. A 3n slot, 2n pole structure (n = 1) including a stator having a plurality of magnetic teeth formed by concentrating windings around a core and a rotor having a plurality of permanent magnets embedded therein. , 2, 3,...), The electrical angle between one edge of the tooth and the other edge of the tooth adjacent to the tooth is set to 180 ° or more, and the end face of each tooth An axial groove is formed in each of the core end surfaces corresponding to the above (1). 2. The brushless motor according to claim 1, wherein each of the grooves has a triangular cross section. 3. The brushless motor according to claim 1, wherein an axial through hole is formed in a peripheral portion of the rotor and outside of each of the permanent magnets. 4. Each of the permanent magnets has a substantially arc-shaped cross section, and the convex side of each of the substantially arc-shaped permanent magnets is embedded toward the center of the rotor. The brushless motor according to claim 1.