CN100405704C - Fractional slot winding of low-speed large-torque permanent magnet brushless motor - Google Patents

Abstract

The invention relates to a fractional slot winding in a permanent magnet brushless motor, wherein coils of the winding are embedded in stator core slots and correspond to N, S poles of a rotor, the pitch of the winding is 1 slot pitch, and the winding is wound in a double-layer overlapping manner; the iron core is characterized in that the number P of the magnetic poles, the number Z of the iron core slots, the number M of phases and the distribution number Q meet the following conditions: 1) when the distribution number Q is an odd number, the number Z of the iron core slots is Q multiplied by M multiplied by K, and the number P of the magnetic poles is Z plus or minus K; wherein K is a natural number; 2) when the distribution number Q is an even number, the number Z of the iron core slots is Q multiplied by M multiplied by K, and the number P of the magnetic poles is Z plus or minus 2K; wherein K is a natural number. The invention can be suitable for low-speed large-torque permanent magnet brushless motors with various sizes and power levels, and because the pitch of the coil is 1 slot pitch, the length of the end part of the motor winding can be obviously shortened, thereby saving winding materials and energy; meanwhile, the manufacturing process of the winding is simple, and the winding is suitable for large-scale industrial production; in addition, the invention can also reduce the processing cost of the permanent magnet.

Description

Fractional-slot winding of low-speed high-torque permanent magnet brushless motor

technical field

The invention belongs to the technical field of permanent magnet brushless motors, in particular, the invention relates to fractional slot windings in which the multiphase multipole winding pitch is one slot pitch in the permanent magnet brushless motor.

Background technique

Brushless motor is a new type of DC motor developed with the rapid development of electronic technology in the 1950s. Its excellent characteristics are also revealed in the direct drive system. The winding of the brushless motor usually adopts a three-phase star winding, the minimum number of magnetic poles is 2 poles, and the corresponding number of slots is at least 6 slots, if it is 4 poles, it is 12 slots, etc., that is, the number of slots is usually 3 of the magnetic poles. (number of phases) times (Ye Jinhu et al.: "Brushless DC Motor", Science Press (First Edition) 1982.1, pp 17-20); in low-speed brushless motor systems, most of them adopt multi-pole structure or multi-phase multi-pole Structure, to achieve low-speed stable high-torque output. However, as the number of magnetic poles and phases increases, the number of motor slots of a certain size will increase several times. Due to the limitation of mechanical technology, the number of magnetic poles and phases cannot be too much. Therefore, the characteristics of low-speed and high-torque are limited to a certain extent. Due to the complexity of the process of traditional fractional slot windings, and the number of slots is far greater than the number of magnetic poles, fractional slot windings are mostly used in large hydroelectric generators and AC motors for special purposes, and most motors do not use them.

Contents of the invention

The purpose of the present invention is to provide a fractional slot winding with a winding pitch of 1 slot pitch applied in a brushless motor. in the brush motor.

In order to achieve the purpose of the above invention, the present invention provides a fractional slot winding of a low-speed, high-torque permanent magnet brushless motor. The coils of this winding are embedded in the stator core slots, and are aligned with the magnetic poles arranged alternately on the N and S poles on the rotor. Correspondingly, the pitch of the winding is 1 slot pitch, double-layer stacked winding, Q series windings are distributed in a phase band to form a phase winding, and other phase windings are arranged circularly in sequence according to the phase sequence of the motor; it is characterized in that the number of magnetic poles P, the number of core slots Z and the number of phases M and Q meet the following conditions:

1) When Q is an odd number, the number of iron core slots Z=Q×M×K, the number of magnetic poles P=Z±K; where Q=1, 3, 5, 7, 9,..., the number of phases M=2, 3, 4, 5, 6, 7, 8, 9, 10, ..., K is a natural number 1, 2, 3, 4, 5, ...;

2) When Q is an even number, the number of iron core slots Z=Q×M×K, the number of magnetic poles P=Z±2K; where Q=2, 4, 6, 8, 10,..., the number of phases M=2, 3, 4, 5, 6, 7, 8, 9, 10, ..., K is a natural number 1, 2, 3, 4, 5, ....

In the above technical solution, the magnetic pole is made of NdFeB permanent magnet material, and the permanent magnet pole rotor can be an inner rotor, an outer rotor or an end rotor.

In the above technical solution, in the fractional slot winding of the low-speed high-torque permanent magnet brushless motor, the structure of the stator core can be a slot structure or a slotless structure.

In the above technical solution, the fractional slot winding of the low-speed high-torque permanent magnet brushless motor can be installed in a permanent magnet brushless motor or a permanent magnet brushless generator.

The invention can be applied to low-speed and high-torque permanent magnet brushless motors of various sizes and power levels. Since the coil pitch is 1 slot pitch, the end length of the motor winding can be significantly shortened, which can save winding materials (at the same time, the structural material can be saved due to the shortened axial length of the motor) and energy saving (reduce the copper loss and additional loss of the motor) ; At the same time, the manufacturing process of the winding is simple, and it can be directly embedded by hand or embedded by an automatic wire insertion machine, which is suitable for mass industrial production. For a permanent magnet brushless motor of a certain size, with the increase of permanent magnet poles, the magnetic density of the magnetic yoke can be reduced, the amount of iron used can be reduced, and the weight of the motor can be reduced; at the same time, the tile type (inner rotor, outer rotor Magnet) The radius of curvature of the permanent magnet is increased and can be replaced by a cuboid, which reduces the processing cost of the permanent magnet.

Description of drawings

Figure 1 is the expansion diagram of the three-phase winding when the distribution number Q=1

The arrangement of the windings in the figure is: the number of slots Z=Q×M×K (M represents the number of phases, that is, M=3, K is a natural number 1, 2, 3, 4, 5, 6, ...) is 3, 6 , 9, 12, 15, 18..., then the number of magnetic poles P=Z±K is 2, 4, 6, 8, 10, 12... (when "-" is taken, it is a short distance), or The value is 4, 8, 12, 16, 20, 24... (when "+" is selected, it is a long distance)

Figure 2 is the expansion diagram of the three-phase winding when the distribution number Q=2

The arrangement of the windings in the figure is: the number of slots Z=Q×M×K (M represents the number of phases, that is, M=3, K is a natural number 1, 2, 3, 4, 5, 6, ...) is 6, 12 , 18, 24, 30, 36..., the number of magnetic poles P=Z±2K is 4, 8, 12, 16, 20, 24... (when "-" is taken, it is a short distance), or The value is 8, 16, 24, 32, 40, 48... (when "+" is selected, it is a long distance)

Figure 3 is the expansion diagram of the three-phase winding when the distribution number Q=3

The arrangement of the windings in the figure is: the number of slots Z=Q×M×K (M represents the number of phases, that is, M=3, K is a natural number 1, 2, 3, 4, 5, 6, ...) is 9, 18 , 27, 36, 45, 54..., the number of magnetic poles P=Z±K is 8, 16, 24, 32, 40, 48... (when "-" is taken, it is a short distance), or The value is 10, 20, 30, 40, 50, 60... (when "+" is selected, it is a long distance)

Figure 4 is an expanded view of the three-phase winding when the distribution number Q=4

The arrangement of the windings in the figure is: the number of slots Z=Q×M×K (M represents the number of phases, that is, M=3, K is a natural number 1, 2, 3, 4, 5...) is 12, 24, 36, When 48, 60..., the number of magnetic poles P=Z±2K is 10, 20, 30, 40, 50... (when "-" is taken, it is a short distance), or the value is 14, 28, 42, 56, 70...(When "+" is taken, it is a long distance)

Figure 5 is a partial structural diagram of the hub motor of an electric vehicle

Figure 6 is a partial structural diagram of the permanent magnet wind turbine

Fig. 7 Schematic diagram of winding surface of small power permanent magnet slotless end face (plane) rotor brushless motor

Detailed ways

The most common three-phase (i.e. M=3) brushless motor is used as an example below to illustrate the relationship between the number of permanent magnet poles (P) and the number of iron core slots (Z) and the number of phases (M) and distribution number (Q) of the present invention Law (multi-phase motor and so on):

When the distribution number Q is an odd number 1, 3, 5, 7, 9, ..., the number of iron core slots of the motor is Z=M×Q×K, and the number of magnetic poles is P=Z±K, where K is a natural number 1, 2, 3, 4, 5, ..., when the number of magnetic poles is P=Z+K, it is a long-distance winding, and when P=Z-K, it is a short-distance winding.

When the values of M and Q are determined, the number of slots and the number of poles are distributed according to a certain law. Below are a few examples in the form of a table. Table 1 shows the relationship between the number of slots and poles when M=3, Q=1, Table 2 shows the relationship between the number of slots and poles when M=3, Q=3, and Table 3 shows M=3, The relationship between the number of slots and the number of poles when Q=5.

Table 1

Table 2

table 3

Similarly, when M=3, Q=7, 9..., the corresponding relationship between the number of slots and the number of poles can be obtained by analogy with the above three examples.

When the distribution number Q is an even number 2, 4, 6, 8, 10, ..., the number of iron core slots of the motor is Z=M×Q×K, the number of magnetic poles is P=Z±2K, and the number of magnetic poles is P=Z+2K It is a long-distance winding, and it is a short-distance winding when P=Z-2K.

When the values of M and Q are determined, the number of slots and the number of poles are distributed according to a certain law. The following also gives several examples in the form of tables. Table 4 shows the relationship between the number of slots and the number of poles when M=3 and Q=2, and Table 5 shows the relationship between the number of slots and the number of poles when M=3 and Q=4.

Table 4

table 5

Similarly, when M=3, Q=6, 8..., the corresponding relationship between the number of slots and the number of poles can be obtained by analogy with the above two examples.

Figures 1, 2, 3, and 4 are the expansion diagrams of three-phase (M=3) windings under different parameters. Similarly, two-phase (M=2), four-phase (M=4), and five-phase ( M=5) and a series of winding expansion diagrams, according to the design requirements of the motor, adopt different combinations of the number of slots and the number of poles to achieve the best design effect. For brushless motors with a slotless structure, the number of slots in this paper is the number of virtual slots.

Example 1

Fractional slot windings for in-wheel motors for electric vehicles

Figure 5 is a schematic diagram of the local structure of the hub motor of an electric vehicle. The form and connection of the fractional slot winding refer to Figure 3 and Table 2. The coil of this winding is embedded in the stator core slot, and the magnetic poles arranged alternately with the N and S poles on the rotor Correspondingly, the winding pitch of the winding is 1 slot pitch, the double-layer winding is stacked, and 3 (that is, the distribution number Q=3) series windings are distributed in a phase band to form a phase winding, and the other phase windings are in sequence according to the phase sequence of the motor Circular arrangement.

The number of magnetic poles P, the number of iron core slots Z, the number of phases M, and the number of distributions Q in this embodiment satisfy the condition 1) when the number of distributions Q is an odd number, the number of iron core slots Z=Q×M×K, and the number of magnetic poles P= Z±K; where Q=1, 3, 5, 7, 9, ..., phase number M = 2, 3, 4, 5, 6, 7, 8, 9, 10, ..., K is a natural number 1, 2, 3, 4, 5, ....

Referring to FIG. 5 , in this embodiment, the inner stator core 3 is made of silicon steel sheets for motors, and 72 slots are evenly distributed on its circumferential surface. The permanent magnetic pole 2 adopts NdFeB cuboid magnetic steel, N and S magnetic poles are alternately and evenly distributed, and the total number of magnetic poles is 64. The outer rotor casing 1 is made of magnetically conductive material. The motor in this embodiment is a permanent magnet brushless DC motor with a slotted structure on the outer rotor, a three-phase multi-pole fractional slot winding, a low-speed high-torque direct drive wheel, a maximum power of up to 20kW, a voltage of 400V, and a speed of 800rpm. The overload capacity is 3-5 times.

Example 2

Fractional slot windings for wind turbines

Figure 6 is a schematic diagram of a partial structure of a permanent magnet wind power generator. Refer to Figure 4 and Table 5 for the form and connection of the fractional slot winding. The magnetic poles are corresponding, the winding pitch of the winding is 1 slot pitch, double-layer winding, and 4 (that is, the distribution number Q=4) series windings are distributed in a phase band to form a phase winding, and the other phase windings follow the phase sequence of the motor Circular arrangement in sequence.

The number of magnetic poles P, the number of iron core slots Z, the number of phases M, and the number of distributions Q in this embodiment satisfy the condition 2) when the number of distributions Q is an even number, the number of iron core slots Z=Q×M×K, and the number of magnetic poles P= Z±2K; where Q=2, 4, 6, 8, 9, ..., phase number M = 2, 3, 4, 5, 6, 7, 8, 9, 10, ..., K is a natural number 1, 2, 3, 4, 5, ....

As shown in FIG. 6 , the inner stator core 3 in this embodiment is made of silicon steel sheets for motors, and 108 slots are evenly distributed on its circumferential surface. The permanent magnetic pole 2 adopts NdFeB cuboid magnetic steel, N and S magnetic poles are alternately and evenly distributed, and the total number of magnetic poles is 90. The outer rotor casing 1 is made of magnetically conductive material. The generator in this embodiment is an outer rotor permanent magnet brushless wind generator with slot structure, three-phase multi-pole fractional slot winding, low-speed direct drive blades, power 1-500kW, speed 100rpm.

The two types of outer rotor motors (motor, generator) in Embodiment 1 and Embodiment 2 can also easily implement a conventional inner rotor structure or a slotless structure, which is easily understood by those skilled in the art.

Example 3

Small power permanent magnet slotless end face (plane) rotor brushless motor

Figure 7 is a schematic diagram of the winding surface of a small-power permanent magnet slotless end face (plane) rotor brushless motor. The form and connection of the fractional slot winding refer to Figure 3 and Table 2. The inner stator core 3 is made of magnetically conductive material (disc type), without Motor windings are glued on the end face of the slot, and 36 equal parts are evenly distributed on the end face of the disc, that is, 36 virtual slots 4, and each equal part has double-layer distributed windings. The permanent magnetic pole 2 adopts NdFeB fan-shaped magnetic steel, and the N and S magnetic poles are alternately and evenly distributed. The motor has a power of 500W, a flat structure without slots, number of virtual slots Z=36, number of poles P=32, three-phase low-speed and large-torque DC brushless motor.

Claims (5)

1. A fractional slot winding of a low-speed high-torque permanent-magnet brushless motor, the coil of which is embedded in the stator core slot, corresponding to the magnetic poles arranged alternately with N and S poles on the rotor, the windings The winding pitch is 1 slot pitch, double-layer stacked winding, Q series windings are distributed in a phase belt to form a phase winding, and other phase windings are arranged in a cycle according to the phase sequence of the motor; it is characterized in that the number of magnetic poles P, the core slot The following conditions are satisfied between the number Z, the phase numbers M and Q: 1) When Q is an odd number, the number of iron core slots Z=Q×M×K, the number of magnetic poles P=Z±K; where Q=1, 3, 5, 7, 9,..., the number of phases M=2, 3, 4, 5, 6, 7, 8, 9, 10, ..., K is a natural number 1, 2, 3, 4, 5, ...; 2) When Q is an even number, the number of iron core slots Z=Q×M×K, the number of magnetic poles P=Z±2K; where Q=2, 4, 6, 8, 10,..., the number of phases M=2, 3, 4, 5, 6, 7, 8, 9, 10, ..., K is a natural number 1, 2, 3, 4, 5, .... 2. by the fractional slot winding of the described low-speed high-torque permanent magnet brushless motor of claim 1, it is characterized in that, the magnetic pole that described magnetic pole is made of permanent magnet material, and permanent magnet magnetic pole rotor is inner rotor, outer rotor or end rotor. 3. The fractional slot winding of the low-speed and high-torque permanent magnet brushless motor according to claim 2, wherein the permanent magnet material is NdFeB permanent magnet material. 4. The fractional slot winding of the low-speed high-torque permanent magnet brushless motor according to claim 1, wherein the structure of the stator core is a slotted structure. 5. The fractional slot winding of the low-speed, high-torque permanent magnet brushless motor according to claim 1, wherein the fractional slot winding is installed in a permanent magnet brushless motor or a permanent magnet brushless generator.

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