JP2021164304A - motor - Google Patents

Abstract

To provide a motor having a plurality of coil groups with different power systems, in which torque characteristics can be finely adjusted.SOLUTION: A motor 1 includes: a stator 30 having a plurality of coils 33 lined up around a central axis; and a rotor 20 rotating relative to the stator. The plurality of coils constitute a first coil group and a second coil group having power systems different from each other. The coils of the first coil group and the coils of the second coil group have the number of conductor turns different from each other. The supply ratio of the amount of power supplied to the first coil group to the amount of power supplied to the second coil group may be adjusted.SELECTED DRAWING: Figure 1

Description

The present invention relates to a motor.

In recent years, a motor that ensures redundancy by forming a three-phase motor with a plurality of wiring connections has been known (for example, Patent Document 1). Such a motor has an advantage that the minimum function can be maintained by functioning a three-phase circuit of at least one system.

JP-A-2018-042328

In general, the torque characteristics of the output of a motor are determined mainly by the wire diameter of the conducting wire and the number of turns. The wire diameter of the conductor is standardized for each predetermined dimension, and the number of turns can be changed only for each turn. Therefore, it has been difficult to finely adjust the torque characteristics.

In view of the above circumstances, one of the objects of the present invention is to provide a motor having a plurality of coil groups having different power systems and capable of finely adjusting the torque characteristics.

One aspect of the motor of the present invention includes a stator having a plurality of coils arranged around the central axis, and a rotor that rotates relative to the stator. The plurality of coils form a first coil group and a second coil group having different power systems from each other. The coil of the first coil group and the coil of the second coil group have different numbers of turns of the conducting wire. The supply ratio of the amount of electric power supplied to the first coil group and the amount of electric power supplied to the second coil group may be adjusted.

According to one aspect of the present invention, there is provided a motor having a plurality of coil groups having different power systems and capable of finely adjusting the torque characteristics.

FIG. 1 is a cross-sectional view of the motor of one embodiment. FIG. 2 is a partially enlarged view of FIG. FIG. 3 is a schematic diagram showing a two-system three-phase circuit composed of 12 coils. FIG. 4 is a graph comparing torque characteristics in motors having different numbers of conductor turns.

Hereinafter, the motor 1 according to the embodiment of the present invention will be described with reference to the drawings. The scope of the present invention is not limited to the following embodiments, and can be arbitrarily changed within the scope of the technical idea of the present invention. Further, in the following drawings, in order to make each configuration easy to understand, the scale and number of each structure may be different from the actual structure.

The drawings show the Z axis. The central axis J of the motor 1 extends parallel to the Z axis. In the following description, the radial direction centered on the central axis J is simply referred to as the "diametric direction", and the circumferential direction centered on the central axis J, that is, the circumference of the central axis J is simply referred to as the "circumferential direction". The direction parallel to the central axis J (that is, the Z-axis direction) is called the axial direction.

FIG. 1 is a cross-sectional view of the motor 1 in a cross section orthogonal to the central axis J. FIG. 2 is a partially enlarged view of FIG.

The motor 1 of the present embodiment is an 8-pole, 12-slot three-phase AC motor. Further, the motor 1 of the present embodiment is an inner rotor type motor. The motor 1 includes a rotor 20 and a stator 30.

The rotor 20 rotates relative to the stator 30 about the central axis J. The rotor 20 includes a shaft 21, a rotor core 24, and a rotor magnet 23.

The shaft 21 extends about the central axis J. The shaft 21 is rotatably supported around the axis of the central axis J by bearings (not shown).

The rotor core 24 is fixed to the shaft 21. The rotor magnet 23 is fixed to the rotor core 24. The rotor magnet 23 is a permanent magnet having eight poles (8 poles) in the circumferential direction. The rotor core 24 and the rotor magnet 23 rotate around the central axis J together with the shaft 21.

The stator 30 is arranged in an annular shape around the central axis J. The stator 30 faces the rotor 20 in the radial direction through a gap. The stator 30 surrounds the radially outer side of the rotor 20. The stator 30 includes a stator core 31, an insulator 39, and a coil 33.

The stator core 31 of this embodiment is a split core. The stator core 31 is composed of a plurality of core pieces 32 arranged in an annular shape along the circumferential direction. In the stator core 31, core pieces 32 adjacent to each other in the circumferential direction are connected to each other. That is, the stator core 31 is configured by connecting a plurality of core pieces 32 along the circumferential direction.

The core piece 32 has a core back portion 32a and a teeth portion 32b. The stator core 31 of the present embodiment is composed of 12 core pieces 32. Therefore, the stator 30 of the present embodiment has 12 teeth portions 32b. The number of the core piece 32 and the teeth portion 32b is not limited to this.

The core back portion 32a extends along the circumferential direction. The core back portion 32a is connected to the core back portion 32a of the adjacent core piece 32 at the end portion facing the circumferential direction. The core back portions 32a adjacent to each other in the circumferential direction are joined by welding or the like. As a result, the core back portions 32a of all the core pieces 32 are connected in an annular shape.

The tooth portion 32b extends radially inward from the center of the core back portion 32a in the circumferential direction. The tip surface of the teeth portion 32b faces the rotor 20 in the radial direction. The plurality of tooth portions 32b are arranged along the circumferential direction. A slot 35 is provided between the tooth portions 32b adjacent to each other in the circumferential direction. An umbrella portion 32c is provided at the tip of the teeth portion 32b. The tooth portion 32b has a large width dimension (dimension along the circumferential direction) in the umbrella portion 32c.

A coil 33 is wound around the outer peripheral surface of the teeth portion 32b between the core back portion 32a and the umbrella portion 32c via an insulator 39. That is, the coil 33 is mounted on the teeth portion 32b via the insulator 39. The insulator 39 is made of an insulating material. The insulator 39 covers the outer peripheral surface of the teeth portion 32b. The insulator 39 is sandwiched between the outer peripheral surface of the teeth portion 32b and the coil 33.

The coil 33 is configured by winding the conducting wires 33a and 33b around the teeth portion 32b via the insulator 39. The conductors 33a and 33b pass through the slot 35 between the teeth portions 32b. The plurality of coils 33 are arranged in an annular shape around the central axis J. In this embodiment, the stator 30 is provided with 12 coils 33.

FIG. 3 is a schematic diagram showing a two-system three-phase circuit composed of 12 coils 33.
The 12 coils 33 of the stator 30 are four U-phase coils U1a, U1b, U2a, U2b, four V-phase coils V1a, V1b, V2a, V2b, and four W-phase coils W1a, W1b, W2a, W2b. And, it is classified into. An alternating current whose phase is shifted by 120 ° is passed through the U-phase coil, the V-phase coil, and the W-phase coil. Further, currents having the same phase flow through the U-phase coils, the V-phase coils, and the W-phase.

The stator 30 has a U-phase coil, a V-phase coil, and a W-phase coil as one coil group, and the coil group (first coil group 11 and second coil) of a plurality of systems (two systems in this embodiment). Group 12). The three-phase circuits of each system have different power systems. That is, the plurality of coils 33 constitute a first coil group 11 and a second coil group 12 having different power systems.

According to the present embodiment, the stator 30 has a plurality of coil groups (first coil group 11 and second coil group 12). As a result, the redundancy of the motor 1 can be ensured. That is, even if a problem occurs in any one of the coil groups 11 and 12 of the plurality of systems, the motor 1 can be driven by using the coil groups of the other systems.

The coil 33 of the first coil group 11 is classified into U-phase coils U1a and U1b, V-phase coils V1a and V1b, and W-phase coils W1a and W1b. The coil 33 of the second coil group 12 is classified into U-phase coils U2a and U2b, V-phase coils V2a and V2b, and W-phase coils W2a and W2b. Two coils 33 are provided in each phase (U phase, V phase, W phase) of each system. Two coils 33 of the same phase in each system are connected in series. Two coils 33 having the same system and the same phase are wound in a continuous arc with each other, for example.

In the first coil group 11, the U-phase coils U1a and U1b, the V-phase coils V1a and V1b, and the W-phase coils W1a and W1b are connected to each other by Y connection. Similarly, in the second coil group 12, the U-phase coils U2a and U2b, the V-phase coils V2a and V2b and the W-phase coils W2a and W2b are connected to each other by Y connection.

As shown in FIG. 1, the coil 33 of the first coil group 11 (that is, the coils U1a, U1b, V1a, V1b, W1a, W1b) and the coil 33 of the second coil group 12 (that is, the coils U2a, U2b, V2a, V2b, W2a, W2b) are alternately arranged along the circumferential direction.

The coil 33 of the first coil group 11 is composed of the first conductor 33a, and the coil 33 of the second coil group 12 is composed of the second conductor 33b. A part of the coils 33 adjacent to each other in the circumferential direction is arranged in the slot 35. Therefore, the first conductor 33a and the second conductor 33b pass through one slot 35.

In the present embodiment, the number of turns of the first conductor 33a constituting the coil 33 of the first coil group 11 is larger than the number of turns of the second conductor 33b constituting the coil 33 of the second coil group 12. The number of turns in the present specification means the number of laps when the conducting wire constituting one coil 33 is wound around the teeth portion 32b.

FIG. 4 is a graph comparing the relationship (torque characteristics) between the torque and the rotation speed of motors having different numbers of turns. The torque characteristics of the motor having a large number of turns in FIG. 4 are the characteristics of the rotation speed and torque of the motor when all the coils are replaced with only the coils 33 of the first coil group 11. Further, the torque characteristics of the motor having a small number of turns in FIG. 4 are the characteristics of the rotation speed and torque of the motor when all the coils are replaced with only the coils 33 of the second coil group 12.

By increasing the number of turns of the conducting wires constituting the coil, the number of interlinkage magnetic fluxes passing through the coil can be increased. That is, the torque of the motor can be increased by increasing the number of turns of the conducting wire. However, as the number of turns increases, the conductors that make up the coil become longer. Since the resistance value of the coil is proportional to the length of the conducting wire, the resistance value increases by increasing the number of turns, and it becomes difficult for the current to flow especially in the region where the rotation speed becomes high (high speed region). As a result, in a motor having a large number of turns, the torque drop in the high speed range becomes remarkable. On the other hand, a motor having a small number of turns suppresses a drop in torque in a high speed range as compared with a motor having a large number of turns. That is, a motor having a large number of turns tends to increase the torque of the motor in the low speed range, and a motor having a small number of turns tends to increase the torque of the motor in the high speed range.

The number of turns of the conductors that make up the coil can only be changed for each turn. When the number of turns of the motor constituting the coil is increased, the torque in the high speed range decreases and the torque in the high speed range increases. When all the coils are composed of only one type of turns, the torque in the high speed range and the low speed range can be adjusted only for each turn.

On the other hand, in the motor 1 of the present embodiment, the number of turns of the conducting wires 33a and 33b is different between the coil 33 of the first coil group 11 and the second coil group 12 having different power systems. Therefore, according to the present embodiment, a motor having a torque characteristic between a motor composed of only the number of turns of the first coil group 11 and a motor composed of only the number of turns of the second coil group 12 Can be obtained. Therefore, by separately changing the number of turns of the first coil group 11 and the second coil group 12, it is possible to obtain a motor in which the torque characteristics are finely adjusted.

As shown in FIG. 1, the cross-sectional shapes of the first conductor 33a and the second conductor 33b of the present embodiment are both circular. In the present embodiment, the wire diameter of the first conductor 33a is larger than the wire diameter of the second conductor 33b.

Since the resistance value per unit length of the conducting wire is inversely proportional to the cross-sectional area of the conducting wire, the resistance value of the conducting wire can be reduced by increasing the cross-sectional area of the conducting wire. However, if the cross-sectional area of the conducting wire is increased, the occupied area per slot becomes large, so that it is difficult to increase the number of turns of the conducting wire.

In a motor having a small cross-sectional area of the conducting wire, the number of turns can be increased, so that the torque of the motor in the low speed range can be increased. However, since the resistance value of the conducting wire is large, the torque drops significantly in the high speed range. On the other hand, in a motor with a large cross-sectional area of the conductor, it is difficult to increase the number of turns, so the torque of the motor in the low speed range cannot be increased. It can be suppressed. That is, a motor having a small cross-sectional area of a conducting wire tends to increase the torque of the motor in a low speed range, and a motor having a large cross-sectional area of a conducting wire tends to increase the torque of a motor in a high speed range.

Generally, a copper electric wire having a coating such as enamel called an enamel wire is used as a conducting wire constituting the coil. As such a conductor, a standardized wire having a specific wire diameter is prepared. If you want to use a wire with a standardized wire diameter, you need to prepare a custom-made product, and the price of the conductor becomes expensive. Therefore, when the motor is manufactured at low cost, the torque in the high speed range and the low speed range cannot be adjusted by a fine wire diameter.

On the other hand, according to the motor 1 of the present embodiment, the wire diameters of the conducting wires 33a and 33b are different between the coil 33 of the first coil group 11 and the second coil group 12 having different power systems. According to the present embodiment, the motor has a torque characteristic between a motor composed of only the wire diameter conductors of the first coil group 11 and a motor composed of only the wire diameter conductors of the second coil group 12. You can get a motor. Therefore, by separately changing the wire diameters of the conductors of the first coil group 11 and the second coil group 12, it is possible to obtain a motor in which the torque characteristics are finely adjusted.

In the present embodiment, the first conductor 33a and the second conductor 33b are made of the same material. However, the materials of the first conductor 33a and the second conductor 33b may be different from each other. The wire diameter of the second conductor 33b is larger than that of the first conductor 33a, and the resistance value per unit length is lower than that of the first conductor 33a. Therefore, for example, by adopting a material as the second conductor 33b, which has a higher resistance value than the first conductor 33a but is inexpensive, the motor 1 as a whole can be made inexpensive while suppressing the influence on the torque characteristics of the motor 1. be able to.

According to the present embodiment, the coil 33 of the first coil group 11 and the coil 33 of the second coil group 12 are alternately arranged along the circumferential direction. The coils 33 of the first coil group 11 and the second coil group 12 that are adjacent to each other in the circumferential direction share one slot 35. Therefore, in the slot 35, the occupancy rate of one of the coils 33 of the first coil group 11 and the second coil group 12 can be increased and the occupancy rate of the other can be decreased. Therefore, according to the present embodiment, it is possible to increase the variety of combinations of the coils 33 of the first coil group 11 and the second coil group 12.

As shown in FIG. 2, a center line VL is drawn between adjacent tooth portions 32b. The center line VL is a virtual line that passes through the center axis J and extends along the radial direction when viewed from the axial direction. Further, the center line VL is located in the middle of the adjacent teeth portions 32b. The slot 35 is divided into two regions having the same cross-sectional area by the center line VL. Here, in the slot 35, the region on the coil 33 side of the first coil group 11 is referred to as the first region 35A, and the region on the coil 33 side of the second coil group 12 is referred to as the second region 35B. ..

A part of the first conductor 33a of the first coil group 11 is arranged on the second region 35B side beyond the center line VL. That is, according to the present embodiment, one of the pair of coils 33 mounted on the tooth portions 32b adjacent to each other in the circumferential direction is arranged beyond the center line VL. In this way, since the coils 33 of the first coil group 11 and the second coil group 12 share one slot 35, one coil 33 can be arranged beyond half of the slot 35. As a result, the number of turns of the coil 33 of one of the coil groups of the plurality of systems (the first coil group 11 in the present embodiment) can be further increased.

As shown in FIG. 3, the U-phase coils U1a and U1b, the V-phase coils V1a and V1b, and the W-phase coils W1a and W1b of the first coil group 11 are connected to the first control unit 15. A current having a first current value A1 is passed from the first control unit 15 to each coil 33 of the first coil group 11.

On the other hand, the U-phase coils U2a, U2b, V-phase coils V2a, V2b and the W-phase coils W2a, W2b of the second coil group 12 are connected to the second control unit 16. A current having a second current value A2 is passed from the second control unit 16 to each coil 33 of the second coil group 12.

An alternating current having the same frequency is passed through the first coil group 11 and the second coil group 12. Further, the effective values of the currents flowing through the first coil group 11 and the second coil group 12 may be the same value or different values as described later.

The first control unit 15 and the second control unit 16 are a part of the integrated control unit (control unit) 17. That is, the motor 1 has a general control unit 17. The integrated control unit 17 controls the motor 1 by controlling the first control unit 15 and the second control unit 16. More specifically, the overall control unit 17 controls the first current value A1 flowing through the first coil group 11 via the first control unit 15, and the second coil group via the second control unit 16. The second current value A2 flowing through the 12 is controlled.

As described above, in the motor 1, the torque of the coil 33 of the first coil group 11 increases in the low speed range, and the torque of the coil 33 of the second coil group 12 increases in the high speed range (see FIG. 4). Therefore, the drive of the coil 33 of the first coil group 11 is dominant in the low speed range, and the drive of the coil 33 of the second coil group 12 is dominant in the high speed range, so that the drive of the coil 33 of the second coil group 12 is dominant in any speed range. The torque can be increased. That is, it is preferable that the motor 1 is adjusted in the supply ratio of the amount of electric power supplied to the first coil group 11 and the amount of electric power supplied to the second coil group 12. As a result, high torque can be obtained in both the low speed range and the high speed range while keeping the power consumption constant.

A specific control method of the motor 1 by the integrated control unit 17 will be described.
As shown in FIG. 4, a graph of the torque characteristics of the motor composed of only the coils 33 of the first coil group 11 and a graph of the torque characteristics of the motor composed of only the coils 33 of the second coil group 12 Intersects at the boundary between the low speed range and the high speed range. Here, the number of rotations at the intersection of the two graphs is defined as the intersection value P0.
In the present embodiment, the integrated control unit 17 stores in advance a first threshold value P1 larger than the intersection P0 and a second threshold value P2 smaller than the intersection P0. The first threshold value P1 and the second threshold value P2 are values in the vicinity of the intersection P0, and are predetermined values so that the control switching of the current value, which will be described later, can be smoothly switched. By smoothly switching the current value, the torque fluctuation at the time of switching can be reduced. Thereby, when the motor 1 is adopted for a steering system, for example, it is possible to suppress the shock caused by the torque fluctuation from being transmitted to the driver.

The general control unit 17 sets the first current value A1 (the value of the current flowing through the first coil group 11) until the motor 1 is started and the rotation speed of the rotor 20 exceeds the first threshold value P1. 2 Make it larger than the current value A2 (the value of the current flowing through the second coil group 12).

Further, the integrated control unit 17 switches the magnitude of the current value when the rotation speed of the rotor 20 exceeds the first threshold value P1 at the time of switching from the low speed region to the high speed region. That is, the integrated control unit 17 makes the second current value A2 larger than the first current value A1 when the rotation speed of the rotor 20 exceeds the first threshold value P1.

Further, the integrated control unit 17 is in a state where the second current value A2 is larger than the first current value A1 until the rotation speed falls below the second threshold value P2 after the rotation speed of the rotor 20 exceeds the first threshold value P1. To maintain.

Further, when switching from the high speed range to the low speed range, the integrated control unit 17 switches the magnitude of the current value when the rotation speed of the rotor 20 falls below the second threshold value P2. That is, the integrated control unit 17 makes the first current value A1 larger than the second current value A2 when the rotation speed of the rotor 20 falls below the second threshold value P2.

Further, in the general control unit 17, after the rotation speed of the rotor 20 falls below the second threshold value P2, the first current value A1 is larger than the second current value A2 until the rotation speed exceeds the first threshold value P1 again. Maintain the state.

As shown above, when the rotation speed of the rotor 20 exceeds the first threshold value P1, the integrated control unit 17 sets the first current value A1 to be larger than the second current value A2, and sets the second threshold value P2. When the value is less than the above, the first current value A1 is made larger than the second current value. As a result, the drive of the motor 1 by the first coil group 11 is dominant in the low speed range, the torque in the low speed range can be increased, and the drive of the motor 1 by the second coil group 12 is dominant in the high speed range. , The torque in the high speed range can be increased.

In the present embodiment, the first threshold value P1 is larger than the second threshold value P2. However, the magnitude relationship between the first threshold value P1 and the second threshold value P2 is not limited to this embodiment. That is, the second threshold value P2 may be larger than the first threshold value P1, and the first threshold value P1 and the second threshold value P2 may be equal to each other. When the first threshold value P1 and the second threshold value P2 are equal, it is preferable that the value coincides with the intersection value P0.

Next, another control method of the motor 1 by the integrated control unit 17 will be described.
Here, the number of turns of the first conductor 33a constituting the coil 33 of the first coil group 11 is T1, and the number of turns of the second conductor 33b constituting the coil 33 of the second coil group 12 is T2. ..

The integrated control unit 17 sets the first current value A1 and the second current value A2 to values that satisfy the following equation 1.
T1 / T2 = A2 / A1 (Equation 1)

The number of interlinkage magnetic fluxes passing through one coil 33 is proportional to the number of turns and the current value, respectively. As shown in Equation 1, the current values of the first coil group 11 and the second coil group 12 are distributed in inverse proportion to the number of turns to obtain the number of interlinkage magnetic fluxes of the coil 33 of the first coil group 11. , The number of interlinkage magnetic fluxes of the coil 33 of the second coil group 12 can be matched. Therefore, the force for attracting each magnetic pole of the rotor 20 by the plurality of coils 33 arranged along the circumferential direction can be brought close to a constant value, and the torque ripple of the motor 1 can be reduced.

Although the embodiments of the present invention have been described above, the configurations and combinations thereof in the embodiments are examples, and additions, omissions, substitutions, and other modifications of the configurations are made without departing from the spirit of the present invention. Is possible. Further, the present invention is not limited to the embodiments.

For example, in the above-described embodiment, the case where the motor has two power systems has been described. However, the motor may have three or more power systems. In this case, the torque characteristics of the motor can be finely adjusted by individually changing the number of turns and the cross-sectional area of the conductors of the coil group connected to each power system.

Further, in the above-described embodiment, the case where the cross-sectional shapes of the conducting wires 33a and 33b are circular has been described. However, the cross-sectional shape of the conducting wire may be rectangular or triangular. Further, the cross-sectional shapes of the first conductor 33a and the second conductor 33b may be different from each other.

Further, in the above-described embodiment, each coil group has a three-phase circuit formed by Y connection. However, the coil group may have a three-phase circuit formed by Δ connection.

1 ... motor, 11 ... coil group, 11 ... first coil group, 12 ... second coil group, 17 ... general control unit (control unit), 20 ... rotor, 30 ... stator, 32b ... teeth unit, 33 ... Coil, 33a, 33b ... Conductor, J ... Central axis, P1 ... First threshold, P2 ... Second threshold, VL ... Center line

Claims (8)

A stator with multiple coils lined up around the central axis,
A rotor that rotates relative to the stator is provided.
The plurality of coils form a first coil group and a second coil group having different power systems from each other.
The coil of the first coil group and the coil of the second coil group have different numbers of turns of conducting wires.
motor. A stator with multiple coils lined up around the central axis,
A rotor that rotates relative to the stator is provided.
The plurality of coils form a first coil group and a second coil group having different power systems from each other.
The coil of the first coil group and the coil of the second coil group have different cross-sectional areas of conducting wires.
motor. The motor according to claim 1 or 2, wherein the supply ratio of the amount of electric power supplied to the first coil group and the amount of electric power supplied to the second coil group is adjusted. The coil of the first coil group and the coil of the second coil group are alternately arranged along the circumferential direction.
The motor according to any one of claims 1 to 3. The stator has a plurality of teeth portions arranged along the circumferential direction and to which the coil is mounted.
One of the pair of the coils mounted on the teeth portions adjacent to each other in the circumferential direction is arranged beyond the center line between the adjacent teeth portions.
The motor according to claim 4. A control unit for controlling a first current value flowing through the first coil group and a second current value flowing through the second coil group is provided.
The control unit
When the rotation speed of the rotor exceeds the first threshold value, the second current value is made larger than the first current value.
When the rotation speed of the rotor falls below the second threshold value, the first current value is made larger than the second current value.
The motor according to any one of claims 1 to 5. A control unit for controlling a first current value flowing through the first coil group and a second current value flowing through the second coil group is provided.
The number of turns of the conductor of the coil of the first coil group is T1.
The number of turns of the conductor of the coil of the second coil group is T2,
The first current value is A1,
Let the second current value be A2,
The control unit sets the first current value and the second current value to values satisfying the following equations.
The motor according to any one of claims 1 to 6.
T1 / T2 = A2 / A1 The conductors of the first coil group and the conductors of the second coil group are made of different materials.
The motor according to any one of claims 1 to 7.

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