Brushless motor
阅读说明:本技术 无刷电动机 (Brushless motor ) 是由 大堀龙 盐田直树 杉山友康 早田圣基 于 2018-05-01 设计创作,主要内容包括:无刷电动机(1)具有具备定子芯(5)和绕组(6)的定子(2)、具备磁铁(13)的转子(3)、以及检测转子(3)的旋转位置的磁传感器(18)。转子(3)具有偏斜构造,对磁铁(13)实施了偏斜磁化。磁铁(13)具有伸出部(14),磁传感器(18)与伸出部(14)的轴向端面(20)相向地配置。磁铁(13)的偏斜角在将磁传感器(18)配置在绕组励磁的影响小的最佳位置的状态下,与基于Δ接线、正弦波驱动等电动机规格的传感器配置的角度偏差相匹配地设定。(A brushless motor (1) is provided with a stator (2) having a stator core (5) and a winding (6), a rotor (3) having a magnet (13), and a magnetic sensor (18) for detecting the rotational position of the rotor (3). The rotor (3) has a skew structure and performs skew magnetization on the magnet (13). The magnet (13) has an extension portion (14), and the magnetic sensor (18) is disposed so as to face an axial end surface (20) of the extension portion (14). The offset angle of the magnet (13) is set so as to match the angular deviation of the sensor arrangement based on the motor specifications such as delta connection and sine wave drive, in a state where the magnetic sensor (18) is arranged at an optimum position where the influence of the winding excitation is small.)
1. A brushless motor has:
a stator including a stator core and a winding wound around the stator core;
a rotor disposed radially inside the stator and including a magnet; and
a magnetic sensor that detects a rotational position of the rotor by detecting a magnetic force of the magnet,
it is characterized in that the preparation method is characterized in that,
the rotor has a skew configuration in which switching positions of magnetic poles of the magnets are shifted in a rotational direction along an axial direction,
the magnet has a protruding portion that does not face the stator core but extends in an axial direction from an axial end of the stator core,
the magnetic sensor is disposed to face an axial end surface of the protruding portion of the magnet.
2. The brushless motor of claim 1,
the winding has a winding thickening portion formed from an axial end portion of the stator core toward an axial direction,
the protruding portion extends in the axial direction beyond the winding thickening portion, and is disposed closer to the magnetic sensor than the winding thickening portion.
3. The brushless motor according to claim 1 or 2,
the magnetic sensor is disposed at a distance in the axial direction from the magnet, and at least a part of the magnetic sensor is provided so as to overlap with an axial end face of the protruding portion facing the magnet.
4. The brushless motor according to any one of claims 1 to 3,
when the position of the projecting portion side in the switching positions of the magnetic poles at both ends of the magnet is represented by P and the position on the opposite side of the projecting portion is represented by Q,
assuming that the axial dimension of the stator core is L, the skew angle of the magnet corresponding to the axial dimension of the stator core is θ T, and the axial dimension of the extension portion is OH, the skew angle θ R between P, Q indicating the skew angles of the entire magnet including the extension portion is represented by θ R ═ θ T + (θ T/L) × OH,
when the offset angle from the magnetic pole switching position Q to the magnetic pole center position M of the magnet is represented by θ M, the θ M is represented by θ T/2,
the offset angle thetax from the magnetic pole center position M to the magnetic pole switching position P is set to thetaR-thetaM according to the motor specification.
5. The brushless motor of claim 4,
the skew angle thetaX is set in a range of 0 DEG < theta.ltoreq.60 DEG (electrical angle).
Technical Field
The present invention relates to a brushless motor, and more particularly to a brushless motor of a so-called direct sensing type that directly senses magnetic flux of a rotor magnet without using a sensor magnet.
Background
Conventionally, a drive method is known in which, at the time of drive control of a brushless motor, the position of a rotor is detected by directly sensing magnetic flux of a rotor magnet without using a sensor magnet (for example, patent document 1). Such a driving manner is called direct sensing. Since the direct sensing type motor does not require a sensor magnet in the motor, the number of parts is reduced, and the size and cost of the device can be reduced. However, the direct sensing type motor has a problem that the sensing of the rotor position is easily hindered due to the influence of magnetic flux from the winding excitation. Therefore, in the conventional direct sensing type motor, in order to minimize the influence of the winding excitation, as shown in fig. 5(a), a sensor is usually disposed at a position farthest from the winding of the conducting phase to detect the switching of the magnetic pole.
The
Disclosure of Invention
Problems to be solved by the invention
However, in the direct sensing type motor, the sensor arrangement as shown in fig. 5 is an ideal position in which the influence of the excitation is minimized in the case of the Y-line-rectangular wave drive, but the sensor arrangement is deviated by 30 ° in the electrical angle from the ideal position in the case of the Δ -line or sine wave drive. Therefore, if the sensor is arranged in accordance with the connection state or the driving method, it is difficult to provide the sensor at a position where the sensor is originally intended to be provided in order to suppress the influence of the magnetic field flux. That is, for the reason of motor design, there is a problem that the sensor cannot be arranged at an ideal position which is less susceptible to the influence of the excitation of the winding.
Means for solving the problems
A brushless motor of the present invention includes: a stator including a stator core and a winding wound around the stator core; a rotor disposed radially inside the stator and including a magnet; and a magnetic sensor that detects a magnetic force of the magnet to detect a rotational position of the rotor, wherein the rotor has a skew structure in which a switching position of a magnetic pole of the magnet is shifted in a rotational direction along an axial direction, the magnet has a protruding portion that does not face the stator core and extends from an axial end portion of the stator core along the axial direction, and the magnetic sensor is disposed so as to face an axial end surface of the protruding portion of the magnet.
In the present invention, the magnetic sensor is disposed so as to face the axial end face of the extension portion of the magnet, and the magnetic sensor is axially spaced from the winding, whereby the influence of the winding excitation on the magnetic sensor is suppressed to a small extent. In addition, by using a rotor of a skew structure, it is possible to reduce cogging torque and set a skew angle in accordance with an angular deviation of sensor arrangement based on motor specifications. Thus, the magnetic sensor is arranged at an optimum position where the influence of the winding excitation is small, and the magnetic sensor is adapted to the specifications (Δ connection, sine wave drive, and the like) of the motor. As the skew structure of the rotor, a magnet magnetized obliquely or a stepped skew structure using a segmented magnet can be used.
In the brushless motor, the winding may have a winding thickening portion formed from an axial end portion of the stator core in an axial direction, and the protruding portion may be provided to extend in the axial direction beyond the winding thickening portion and may be disposed closer to the magnetic sensor than the winding thickening portion.
The magnetic sensor may be disposed at a distance in the axial direction from the magnet, and at least a part of the magnetic sensor may be disposed so as to overlap an axial end face of the protruding portion facing the magnet.
When the position of the projecting portion side in the switching positions of the magnetic poles at both ends of the magnet is P and the position on the opposite side to the projecting portion is Q, if the axial dimension of the stator core is L, the skew angle of the magnet corresponding to the axial dimension of the stator core is θ T, and the axial dimension of the projecting portion is OH, the skew angle θ R between the P, Q indicating the skew angles of the entire magnet including the projecting portion is represented by θ R ═ θ T + (θ T/L) × OH. When θ M is a skew angle from the magnetic pole switching position Q to the magnetic pole center position M of the magnet, θ M is represented by θ T/2. In this case, the skew angle θ X from the magnetic pole center position M to the magnetic pole switching position P may be set to θ R — θ M according to the motor specification. In this case, the skew angle θ X may also be set in a range of 0 ° < θ ≦ 60 ° (electrical angle).
ADVANTAGEOUS EFFECTS OF INVENTION
According to the brushless motor of the present invention, the magnetic sensor is disposed so as to face the axial end face of the protruding portion of the magnet, whereby the magnetic sensor can be separated from the winding in the axial direction, and the influence of the winding excitation on the magnetic sensor can be suppressed to a small extent. Further, by adopting a skew structure in which the switching position of the magnetic poles of the magnets is shifted in the rotational direction along the axial direction, the cogging torque can be reduced, and the skew angle can be set so as to match the angular deviation of the sensor arrangement according to the motor specification. Therefore, the magnetic sensor can be arranged at the optimum position in accordance with the specification of the motor. As a result, even when the magnetic sensor cannot be arranged at the optimum position in the rotation direction in consideration of design, the magnetic sensor can be arranged at the optimum position by adjusting the inclination angle.
Drawings
Fig. 1 is an explanatory diagram showing a structure of a brushless motor according to an embodiment of the present invention.
Fig. 2 is an explanatory diagram showing a relationship between the protrusion amount and the detection angle delay of the magnetic flux due to the influence of the winding excitation.
Fig. 3 is an explanatory diagram showing a positional relationship between the magnetic sensor and the magnet.
Fig. 4 is an explanatory diagram showing the arrangement of the magnetic sensor.
Fig. 5 is an explanatory diagram showing a conventional sensor arrangement in a brushless motor of the direct sensing system.
Detailed Description
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. An object of the following embodiments is to provide a brushless motor in which a magnetic sensor can be disposed at a position that is less susceptible to magnetic flux excited by a winding, regardless of the design specifications of the motor. Fig. 1 is an explanatory diagram showing a structure of a brushless motor 1 (hereinafter, simply referred to as a motor 1) as an embodiment of the present invention. The
The
The
In the
In the brushless motor that performs direct induction, a difference occurs in the detection position of the magnetic pole switching between the energization state and the non-energization state due to the influence of the magnetic flux of the winding excitation, and the detection angle tends to be delayed in the energization state compared to the non-energization state. Fig. 2 is an explanatory diagram showing a relationship between the protrusion OH and a detection angle delay of the magnetic flux (delay of switching detection of the magnetic pole) due to the influence of the winding excitation, where (a) shows when the current is 6A, and (b) shows when the current is 15A. According to the analysis of the inventors, it is found that the delay of the detection angle is smaller as the protrusion OH is larger, and the delay increase is larger as the protrusion OH is smaller than the dimension B of the winding thickening
The
In order to detect the commutation timing of each phase, 3 (18U, 18V, 18W)
In the
In this case, when the skew angle corresponding to the axial dimension (stator lamination thickness) L of the
On the other hand, the offset angle θ M at the magnetic pole center position M of the
For example, when the sensor arrangement is deviated from the ideal position by an electrical angle of 30 ° (
As described above, in the
The
The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.
For example, in the above-described embodiments, the present invention is applied to the motor having the so-called SPM structure in which the magnet is arranged on the outer periphery of the rotor, but the structure of the motor is not limited to this. The present invention can also be applied to a motor of a so-called IPM structure in which a magnet is embedded in a rotor, for example. The inclination direction and angle of the skew can be set appropriately according to the motor specification.
As the deflection structure of the
Industrial applicability
The brushless motor according to the present invention can be applied not only to a motor for a sunroof of an automobile but also to motors used in various vehicle-mounted motors such as a motor for a power window and a motor for a power-driven adjustable seat, home electric appliances such as an air conditioner, and the like.
Description of reference numerals
1
3
5
6 winding 7 yoke
8-tooth 9 insulator
11 rotating
13
15 winding thickening
17
19 axial end face of
51
53 winding
53Ua, Ub, 53Va, Vb, 53Wa, Wb phase winding
54 magnetic sensor
54U, 54V, 54W magnetic sensor
B axial dimension OH overhang of the coil upset
Switching position W magnet width of S magnetic pole
Switching position of magnetic pole on P-one end side
Switching position of magnetic pole on the other end side of Q
Center position of M magnetic pole
L axial dimension of stator core (stator lamination thickness)
Skew angle corresponding to theta T and stator lamination thickness
Skew angle at central position M of theta M magnetic pole
Skew angle of theta R magnet as a whole
Angle of deviation of θ X from magnetic pole center position M to point P
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