JP2018207651A - Brushless motor and motor for power steering device - Google Patents

Abstract

To suppress vibration in conduction drive of one system to be small in a brushless motor in configurations of 10 poles and 12 slots, or 14 poles and 12 slots.SOLUTION: A brushless motor 1 is used as a power source for an electric power steering system, and has a stator 2 and a rotor 3. The stator 2 is provided with: 12 teeth 8; and two systems of coils 6 which are wound around the teeth 8, and with different conduction system. The rotor 3 is provided with 10 or 14 magnets 13. As for the coils 6, the ones (for example U1a(+) and U2b(-)) of the same phase with different conduction systems are adjacently arranged, and the coils (for example, U1a(+) and W1a(+)) belonging to the same system are adjacently arranged at one part, respectively, in the respective conduction systems. A set P of the coils 6 belonging to the same system which are adjacently arranged are arranged at positions facing by 180° on the basis of a stator center O.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a brushless motor, and more particularly to a brushless motor effective when applied to a motor for an electric power steering (hereinafter abbreviated as EPS) device mounted on a vehicle such as an automobile.

  An EPS system mounted on a vehicle such as an automobile has a great influence on the steering performance of the vehicle, and thus requires high safety. For this reason, in recent EPS systems, a configuration has been adopted in which a function that was previously only one system is changed to an independent multiple system, and even if one system fails, the function can be continued in the remaining system. ing. As a result, the electric motor used in the EPS system is required to have the same correspondence. For example, as in Patent Documents 1 and 2, a configuration in which the current system to be energized is divided into two independent systems has been proposed. In this case, the arrangement of the two current-carrying windings is, for example, as shown in Patent Document 1, in which two current-carrying windings are arranged symmetrically (FIG. 7 (a)), or two in-phase windings. There is known a set of lines that are alternately arranged in the circumferential direction (FIG. 7B).

Japanese Patent No.4492781 Japanese Patent No. 3875188

  However, if the winding arrangement of each phase described in [First Embodiment] of Patent Document 1 is used, when one of the systems fails and the motor is rotated only by the remaining systems, the energized winding is in the circumferential direction. It will be in a state of being unbalanced. For this reason, there exists a problem that it will be in a magnetically imbalanced state compared with the case where both systems are functioning, and vibration will become large.

  Further, when the winding arrangement in which the first system winding and the second system winding described in [Other Embodiments] of Patent Document 1 are distributed is arranged, one of the systems fails, and only the remaining system is used. When the motor is rotated in this manner, since the energization winding does not exist at the symmetrical position, there is a problem that the state becomes magnetically unbalanced compared to the case where both systems are functioning, and the vibration becomes large. For this reason, there is a possibility that the system in which the motor is incorporated may be adversely affected. In particular, in the EPS system, if the vibration of the motor increases, the influence on the vehicle and the driver's steering feeling may be increased. There was a problem that there was concern about the decline of

  On the other hand, in the motor of Patent Document 2, two systems of windings are alternately arranged in the circumferential direction, and the same-phase windings of the same system are arranged to face each other by 180 ° (FIG. 7C). For this reason, even if one of the systems fails, the remaining energized windings are present at symmetrical positions, and large vibrations are unlikely to occur when one system fails, as compared with the arrangement of Patent Document 1. However, in the case of the winding arrangement of Patent Document 2, since a difference occurs in the phase of the induced voltage waveform between the two energization systems, it is necessary to devise control such as making the energization phase different during normal motor driving. In other words, such a winding arrangement can avoid vibrations in an emergency, but increases the difficulty of control in normal times.

  On the other hand, EPS motors are required to have not only safety but also small size and high output, and low torque ripple and low cogging. For this reason, as one effective means for achieving them, the number of magnetic poles and slots of the motor may be 10 poles and 12 slots, or 14 poles and 12 slots. However, these combinations of poles / slots tend to deform the magnetic circuit into an ellipse more easily than other combinations, and there is a high possibility that a large vibration will occur when resonating. For this reason, when two independent circuits with 10 poles and 12 slots and 14 poles and 12 slots are employed, it is expected that particularly large vibrations will occur if only one system is driven. Therefore, there has been a demand for a method for reducing vibration during single-system drive.

  An object of the present invention is to suppress vibration during energization driving of one system even in a brushless motor having a 10-pole 12-slot or 14-pole 12-slot configuration.

  The brushless motor of the present invention includes a stator and a rotor disposed on the radially inner side of the stator, and the stator is wound with 12 teeth and concentrated windings around the teeth. The rotor is a brushless motor comprising 10 or 14 magnets, and the stator has the same phase winding with different energization systems. The wires are arranged adjacent to each other, and the windings belonging to the same system are arranged adjacent to each other in each energizing system.

  In the present invention, in a brushless motor having a 10-pole 12-slot or 14-pole 12-slot configuration, (A) windings of the same phase of different systems are arranged adjacent to each other, and (B) The windings belonging to the system are arranged adjacent to each other. As a result, even when one energization system fails and the motor is driven only by the remaining system, the fluctuation of electromagnetic force is suppressed as compared with a motor with a conventional winding arrangement, and the motor during one system drive Vibration is reduced.

  In the brushless motor, among the windings, the set of windings belonging to the same system adjacent to each other may be disposed at a position opposed by 180 ° with respect to the center of the stator. Further, among the windings, the same-phase windings belonging to the same system may be arranged at positions separated by 150 ° with respect to the center of the stator.

  On the other hand, the motor for an electric power steering apparatus of the present invention is characterized by using any of the brushless motors described above. In the present invention, one energization system fails and the other remaining energization system Even when the motor is driven only by this, the vibration of the motor can be suppressed to a small level. For this reason, it is possible to reduce the influence on the vehicle due to the motor vibration at the time of failure, a decrease in the driver's steering feeling, and the like.

  The brushless motor of the present invention is a brushless motor having a stator having twelve teeth and a rotor having ten or fourteen magnets, and in-phase windings of different systems are arranged adjacent to each other, Since the windings belonging to the same system are arranged adjacent to each other in each system, even when one energization system fails and the motor is driven only by the remaining system, the motor with the conventional winding arrangement is used. Compared to the above, fluctuations in electromagnetic force can be suppressed, and vibration of the motor during one-system drive can be reduced.

  The motor for an electric power steering apparatus according to the present invention has a stator having 12 teeth and a rotor having 10 or 14 magnets, and adjacent windings having the same phase in different systems are arranged. In each system, a brushless motor in which windings belonging to the same system are arranged adjacent to each other is used. Therefore, even when one energizing system fails and the motor is driven only by the remaining system, As compared with a motor having a winding arrangement, fluctuations in electromagnetic force can be suppressed, and vibration of the motor during single-system driving is reduced. For this reason, it is possible to reduce the influence on the vehicle due to motor vibration at the time of failure, a decrease in the steering feeling of the driver, and the like, and it is possible to provide a motor suitable for an electric power steering apparatus.

It is explanatory drawing which shows the structure of the brushless motor (14P12S) which is Embodiment 1 of this invention. It is explanatory drawing which shows the structure of the EPS system in which the brushless motor of FIG. 1 is used. It is explanatory drawing which shows arrangement | positioning of two systems of electricity windings in the brushless motor of FIG. It is explanatory drawing which shows the coil | winding supplied with electricity when an electricity supply system fails, (a) has shown the case where the 1st system fails, (b) has each shown the case where the 2nd system has failed. It is explanatory drawing which showed transition of the electromagnetic force which arises in a stator when only one system is energized in the conventional winding arrangement and the winding arrangement according to the present invention. It is explanatory drawing which shows the structure of the brushless motor (10P12S) which is Embodiment 2 of this invention. It is explanatory drawing which shows the winding arrangement | positioning of the conventional brushless motor.

(Embodiment 1)
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory diagram showing the configuration of a brushless motor 1 (hereinafter abbreviated as “motor 1”) according to Embodiment 1 of the present invention, and FIG. 2 shows an EPS system (EPS device) 20 in which the motor 1 is used. It is explanatory drawing which shows a structure. The motor 1 is used as a power source for the EPS system 20 and is an inner rotor type brushless motor in which a stator 2 is arranged on the outside and a rotor 3 is arranged on the inside.

  The stator 2 includes a housing 4, a stator core 5 fixed to the inner peripheral side of the housing 4, and a three-phase (U, V, W) winding (coil) 6 wound around the stator core 5. It has a configuration. The stator core 5 has a structure in which a large number of steel plates are laminated, and is formed of a ring-shaped yoke portion 7 and a plurality of teeth 8 projecting inward from the yoke portion 7. In the motor 1, twelve teeth 8 are provided. Slots 9 are formed between the teeth 8, and the motor 1 has a 12-slot configuration including 12 slots 9. In the slot 9, the winding 6 wound around the tooth 8 is accommodated.

  The rotor 3 is disposed inside the stator 2 and has a configuration in which a rotating shaft 11, a rotor core 12, and a magnet 13 are arranged coaxially. A cylindrical rotor core 12 in which a large number of steel plates are laminated is attached to the outer periphery of the rotating shaft 11. A magnet 13 is fixed to the outer periphery of the rotor core 12. Fourteen magnets 13 are arranged along the circumferential direction, and the motor 1 has a 14-pole 12-slot (14P12S) configuration.

  The EPS system 20 driven by such a motor 1 has a column assist type structure that applies an operation assisting force to the steering shaft 21. A steering wheel 22 is attached to the steering shaft 21, and the steering force of the steering wheel 22 is transmitted to the tie rod 24 via a pinion and a rack shaft (not shown) disposed in the steering gear box 23. A wheel 25 is connected to both ends of the tie rod 24, and the tie rod 24 is operated in accordance with the operation of the steering wheel 22, and the wheel 25 is steered to the left and right via a knuckle arm or the like (not shown).

  In the EPS system 20, an assist motor unit 26 that is a steering force assist mechanism is provided on the steering shaft 21. Along with the motor 1, the assist motor unit 26 is provided with a speed reduction mechanism unit 27 and a torque sensor 28. A worm and a worm wheel (not shown) are arranged in the speed reduction mechanism portion 27, and the rotation of the motor 1 is transmitted to the steering shaft 21 while being reduced by the speed reduction mechanism portion 27. The motor 1 and the torque sensor 28 are connected to a control device (ECU) 29.

  When the steering wheel 22 is operated and the steering shaft 21 rotates, the torque sensor 28 is activated. The ECU 29 appropriately supplies electric power to the motor 1 based on the torque detected by the torque sensor 28. When the motor 1 is actuated, the rotation is transmitted to the steering shaft 21 via the speed reduction mechanism 27 and a steering assist force is applied. The steering shaft 21 is rotated by the steering assist force and the manual steering force, and this rotational motion is converted into a linear motion of the rack shaft by rack-and-pinion coupling in the steering gear box 23, and the steering operation of the wheels 25 is performed. Is done.

  On the other hand, also in the motor 1 according to the present invention, multiplexing of energization systems is achieved to ensure redundancy, and the motor 1 is driven by two independent energization systems. For this reason, the winding 6 is also wired in two independent systems. FIG. 3 is an explanatory diagram showing the arrangement of two current-carrying windings. The numbers (1, 2) after U, V, W in the figure indicate the system to which the windings belong (the first current-carrying system or 2nd electricity supply system) is shown. The winding 6 of the motor 1 is Y-connected by concentrated winding. As shown in FIG. 3, first, (A) windings of different phases in different systems (for example, U1a (+) and U2b (-): FIG. The solid solid circles) are arranged adjacent to each other. Further, in the motor 1, (B) in each system, windings belonging to the same system (for example, U1a (+) and W1a (+): dotted circles in the drawing) are arranged adjacent to each other. Yes.

  In such a winding arrangement, the in-phase windings (for example, U1a (+) and U1b (+)) of each system are positions facing each other by 150 ° with respect to the center O of the stator 2 (same as the center of the rotor 3). Arranged. That is, although not opposed by 180 °, the in-phase winding is disposed at a position shifted by 30 ° therefrom. Further, the winding sets P (broken circles) belonging to the same system and arranged adjacent to each other are arranged at positions facing each other by 180 ° with respect to the center O of the stator 2.

  Therefore, in the motor 1 according to the present invention, when one of the two systems fails, the energization winding remains in the form as shown in FIG. FIG. 4A shows a case where the first system has failed, and FIG. 4B shows a case where the second system has failed. As shown in FIG. 4A, when the first system fails, only the second system winding 6 (U2, V2, W2) is energized. In this case, the in-phase winding 6 (for example, U2a (−) and U2b (−)) of the second system exists at a position facing 150 ° as described above. For this reason, although it is not a perfect symmetrical position, it supplies with electricity to the coil | winding 6 of the substantially opposing position.

  Similarly, when the second system fails, as shown in FIG. 4B, only the first system winding 6 (U1, V1, W1) is energized, and at this time, the first system in-phase winding 6 is turned on. (For example, U1a (+) and U1b (+)) are present at positions facing 150 ° as described above. For this reason, even if the second system breaks down, the energization is performed on the windings 6 that are generally opposed to each other, although not in a completely symmetrical position.

  FIG. 5 shows a stator when only one system is energized in the conventional winding arrangement (conventional example 1: FIG. 7A, conventional example 2: (FIG. 7B)) and the winding arrangement according to the present invention. 4A and 4B are explanatory diagrams showing the transition of the electromagnetic force generated in FIG. 3, where FIG. 3A shows the electromagnetic force in the X direction and FIG. 3B shows the electromagnetic force in the Y direction. As can be seen from FIG. 5, the fluctuation of the electromagnetic force in the radial direction that occurs during one-system drive is about 2 for Conventional Example 1 and about 5 for Conventional Example 2 when the fluctuation in the configuration of the present invention is 1. Yes. That is, in the configuration of the present invention, the fluctuation of the electromagnetic force at the time of one-system drive is about 1/2 of Conventional Example 1 and about 1/5 of Conventional Example 2, and the electromagnetic force fluctuation can be greatly reduced. Become.

  Thus, in the motor 1 according to the present invention, by adopting the winding arrangements (A) and (B) described above, even when one of the energizing systems fails and the motor is driven only by the remaining systems. As compared with a motor with a conventional winding arrangement, fluctuations in electromagnetic force can be suppressed, so that vibration can be reduced. For this reason, even in the EPS system using the motor 1, while ensuring redundancy, adverse effects on the vehicle due to motor vibration at the time of failure can be suppressed, and the deterioration of the steering feeling of the driver can be reduced, and the steering feeling can be reduced. Improvement is achieved. Therefore, even in a motor with a 14-pole 12-slot configuration due to its small size, high output, low torque ripple, and low cogging, vibration during one-system drive can be suppressed, and an electric motor optimal for an EPS system can be provided. Become.

  In the case of the winding arrangement as shown in FIG. 7 (c), it is expected that the vibration at the time of one-system driving is smaller than that of the present invention. The control form at the time of system energization becomes difficult. On the other hand, in the case of the configuration of the present invention, the configuration of FIG. 7C is superior in terms of vibration at the time of failure, but control at the time of two-system energization is easy, and in terms of normal control, The configuration of the invention is superior. In other words, it can be said that the motor 1 of the present invention has a configuration in which normal control is prioritized over failures that rarely occur. According to the present invention, a well-balanced EPS system including the configuration and cost of the control device is provided. Can be provided.

(Embodiment 2)
Next, as a second embodiment of the present invention, an example in which the winding arrangement of the present invention is applied to a 10 pole 12 slot motor will be described. FIG. 6 is an explanatory diagram showing a stator / rotor configuration of a brushless motor 31 (hereinafter abbreviated as “motor 31”) according to the second embodiment. In the present embodiment, the same members and parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

In the motor 31 as well, the windings 6 are arranged in a form that satisfies the following conditions, similarly to the motor 1 of FIG.
(A) In-phase windings of different systems are arranged adjacent to each other.
(B) In each system, the windings belonging to the same system are arranged adjacent to each other.
That is, for example, U1a (+) and U2b (−) are arranged adjacent to each other in the same phase in different systems, and in each system, for example, U1a (+) and W1a (+). One place, windings of the same system are arranged adjacent to each other.

  By adopting such a winding arrangement, even when one of the energizing systems fails and the motor is rotated only by the remaining systems, the energizing windings 6 are generally energized. For this reason, as compared with a conventional motor having a winding arrangement, fluctuations in electromagnetic force are reduced, and generation of vibration can be suppressed. Therefore, even in a motor with a 10-pole 12-slot configuration due to its small size, high output, low torque ripple, and low cogging, vibration during one-system drive can be suppressed, and an electric motor optimal for an EPS system can be provided. Become.

It goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention.
For example, in the above-described embodiment, the example in which the present invention is applied to a motor having a so-called SPM structure in which a magnet is arranged on the outer periphery of the rotor has been described. However, the configuration of the motor is not limited to this, and for example, a magnet is provided in the rotor. The present invention is also applicable to a so-called IPM structure motor that is buried.

  The brushless motor according to the present invention is applicable not only to EPS systems but also to motors used in electric vehicles, hybrid vehicles, home appliances such as air conditioners, various industrial machines, and the like.

DESCRIPTION OF SYMBOLS 1 Brushless motor 2 Stator 3 Rotor 4 Housing 5 Stator core 6 Winding 7 Yoke part 8 Teeth 9 Slot 11 Rotating shaft 12 Rotor core 13 Magnet 20 Electric power steering system 21 Steering shaft 22 Steering wheel 23 Steering gear box 24 Tie rod 25 Wheel 26 Assist motor Part 27 deceleration mechanism part 28 torque sensor 29 ECU
31 Brushless motor O Stator center P Winding set

Claims (4)

A stator, and a rotor disposed radially inward of the stator,
The stator includes twelve teeth and two windings wound around the teeth in a concentrated winding and having different energization systems,
The rotor is a brushless motor comprising 10 or 14 magnets,
In the stator, the same-phase windings having different energization systems are arranged adjacent to each other, and the respective windings belonging to the same system are arranged adjacent to each other in each energization system. Brushless motor. The brushless motor according to claim 1,
Among the windings, the set of windings belonging to the same system arranged adjacent to each other is disposed at a position opposed to 180 ° with respect to the center of the stator. The brushless motor according to claim 1 or 2,
Of the windings, the same-phase windings belonging to the same system are arranged at positions spaced by 150 ° with respect to the center of the stator.   A motor for an electric power steering apparatus, wherein the brushless motor according to any one of claims 1 to 3 is used.

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