JP2001258188A - Position detector for permanent magnet embedded motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure accurate control of the r.p.m. of a motor by detecting the vicinity of boundary of different magnetic poles of a permanent magnet rotor through Hall ICs. SOLUTION: In a permanent magnet embedded motor 10 comprising a permanent magnet rotor 18 having field permanent magnets 46 embedded in the slit holes 38 of a rotor core 44 formed by stacking electromagnetic steel plates 42, and a stator 14 having three-phase stator windings U, V, W applied to the salient pole parts of a stator core 38 and rotary driving the permanent magnet rotor 18 by supplying currents through the three-phase stator windings, a magnetic steel plate 48 having position detecting air gap parts 50a, 50b of different shape from the air gap parts 38a, 38b of another electromagnetic steel plate 42 is fixed to the upper end part of the rotor 18 through a stainless plate 52 of the same shape as the electromagnetic steel plate 42 and three Hall ICs 22-26 are disposed oppositely to the stator side through a gap with respect to the end part of a permanent magnet 46 facing the position detecting air gap part. Position of the permanent magnet rotor 18 is detected by means of these Hall ICs.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting the position of a permanent magnet embedded motor, and more particularly, to a permanent magnet embedded type motor for detecting the position of a rotor using a field permanent magnet embedded in the rotor and a magnetic sensor. The present invention relates to a motor position detecting device.

[0002]

2. Description of the Related Art Generally, in order to rotationally drive a permanent magnet embedded motor in which a permanent magnet is embedded in a rotor in an axial direction, that is, a brushless motor, it is necessary to detect the position of the rotor and to use various sensors. And a case where a sensor is not used. In the case where a magnetic sensor such as a Hall element is used in the sensor, position detection is usually performed by detecting the magnetic poles of the rotor, but this position detection is performed directly from the field permanent magnet embedded in the rotor. There is a method and a method of performing indirectly from another permanent magnet provided for position detection.

[0003] A permanent magnet rotor in which a field permanent magnet is embedded in a rotor core and a stator in which a stator winding is mounted on salient poles of the stator core are provided. In a permanent magnet embedded motor in which the permanent magnet rotor is driven to rotate by rotation, the position of the permanent magnet rotor is detected by a field permanent magnet embedded in the rotor and a magnetic sensor attached to the stator. Since the magnetic flux density distribution on the rotor surface (rotor surface) is disturbed near the boundary between different magnetic poles due to the interval between adjacent gap portions, there is a problem that the rotor position cannot be accurately detected by the magnetic sensor.

[0004] That is, as shown in FIGS. 10A and 10B, when the rotor 2 of the permanent magnet embedded motor 1 is configured by laminating a plurality of circular electromagnetic steel plates 3, each electromagnetic steel plate 3, three trapezoidal slit holes 4 are formed at equal intervals in the peripheral portion at a central angle of about 90 degrees. The trapezoidal slit hole 4 is inserted with the field permanent magnet plate 5 except for the gap portions 4a and 4b at both ends, and the gap between the adjacent gap portions 4a and 4b of the adjacent trapezoidal slit holes 4 and 4. However, in the case of 5 mm as shown, the distribution of the magnetic flux density (T) on the rotor surface is as shown in FIG. 9 (a), and the rotor 2 is connected to the three-phase stator windings U, V, W. When the Hall element 7 for position detection is inserted into the mounted stator 6 and supported by a suitable mounting member on the stator side, the distribution of the magnetic flux density (T) near the Hall element 7 (Hall element portion) Is as shown in FIG. 9B.

[0005]

As is apparent from FIG. 9B, when the detection level of the Hall element 7 is A and B, there is a time lag in the output. As a result, the position of the rotor cannot be accurately detected.

SUMMARY OF THE INVENTION Therefore, a main object of the present invention is to provide a permanent magnet embedded type which can accurately detect the position of the rotor by making the rotor surface magnetic flux distribution uniform even near the boundary between different magnetic poles with a simple structure. An object of the present invention is to provide a device for detecting a rotational position of a motor.

[0007]

According to the present invention, there is provided a permanent magnet rotor in which permanent magnets for field are buried in slit holes of a rotor core formed by laminating magnetic steel sheets except for gaps at both ends.
In a permanent magnet embedded motor, including a stator having a stator winding mounted on a salient pole portion of the stator core, and a magnetic sensor disposed on the stator side to detect a position of a permanent magnet rotor.
At the end of the permanent magnet rotor, a magnetic steel sheet is provided with a position detecting magnetic steel sheet having a different slit hole shape facing the field permanent magnet, and a magnetic steel sheet is further provided with an adjacent gap portion between adjacent slit holes of the magnetic steel sheet. A position detecting device for a permanent magnet embedded motor, wherein an interval is narrower than an interval between adjacent gap portions of adjacent slit holes of an electromagnetic steel plate forming a rotor.

[0008]

[Function] Another magnetic steel sheet having a position detecting gap different from that of the laminated electromagnetic steel sheet constituting the rotor is attached to the end of a permanent magnet rotor in which a field permanent magnet is embedded in the axial direction. Therefore, leakage of magnetic flux near the boundary between different magnetic poles is reduced, and the position of the magnetic pole of the permanent magnet rotor can be accurately detected by the magnetic sensor.

[0009]

According to the present invention, in the permanent magnet embedded type motor, the magnetic sensor can detect the vicinity of the boundary between the different magnetic poles of the permanent magnet rotor, and as a result, it is possible to accurately control the rotational speed of the motor. Become.

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A permanent magnet embedded motor 10 according to an embodiment of the present invention shown in FIG. 1 has a stator 14 press-fitted and held in a cylindrical casing 12 formed of two members, and an interior of the stator 14. And a permanent magnet rotor 18 having a rotating shaft 16 provided at the center and having a rotating shaft 16 at the center, and three mounted on a mounting substrate 20 held on the cylindrical casing 12 and located above the rotor 18. , For example, Hall ICs 22, 24 and 26.

Upper bearings 32 are provided in recesses 28 and 30 provided at the center of the upper and lower surfaces of the cylindrical casing 12, respectively.
And a lower bearing 34, and the rotating shaft 16 of the permanent magnet rotor 18 is supported by the upper and lower bearings 32 and 34.

As shown in FIG. 2, the stator 14 has a stator core 36 having nine salient pole portions 36a, 36b,... 36i on the inner surface side, and a three-phase stator wound around the salient pole portions. Includes windings U, V, W.

Further, as shown in FIGS. 3 and 4, the permanent magnet rotor 18 is a circular electromagnetic steel plate having six trapezoidal slit holes 38 formed at equal intervals on the peripheral edge and a rotary shaft insertion hole 40 formed at the center. Rotor core 44 formed by laminating a plurality of sheets 42
And each trapezoidal slit hole 38 has a gap 38a at both ends thereof.
6 plate-like permanent magnets 4 inserted and buried except 38b and 38b
6 is included.

At the upper end of the permanent magnet rotor 18, a required number of position detecting magnetic steel sheets 48 having substantially the same shape as the circular electromagnetic steel sheet 42 are mounted. That is, as shown in FIGS. 4A and 4B, six trapezoidal slit holes 50 are formed in the peripheral portion of the magnetic steel plate 48 similarly to the electromagnetic steel plate 42, and the adjacent trapezoidal slit holes are formed. Adjacent trapezoidal slit holes 3 formed in the electromagnetic steel sheet 42 with an interval between adjacent void portions 50a and 50b of, for example, 1 mm being 1 mm, for example.
The distance between the adjacent gap portions 38a and 38b of the gaps 8 and 38, for example, is smaller than 5 mm. And this interval,
In the case of 1 mm as shown in the figure, the magnetic flux density distribution on the surface of the permanent magnet rotor 18 and the vicinity of the Hall IC (Hall IC part)
Are shown in FIGS. 8A and 8B, respectively.

As is apparent from FIG. 8, adjacent trapezoidal slit holes 50, 50 formed in the magnetic steel sheet 48 for position detection.
When the gap between the adjacent gap portions 50a and 50b is 1 mm, the polarity is smoothly inverted near the center of the gap, so that the displacement at the time of detecting the rotor position is reduced.

As shown in FIG. 5, when the magnetic steel sheet 42 having a different slit shape (different gaps) is overlapped with the magnetic steel sheet 48 for position detection, a path through which magnetic flux leaks is formed in the hatched portion in the figure. If the area of this path (shaded area) is small, it is saturated immediately and the leakage magnetic flux is small and there is almost no influence. However, if this area is large, there is a possibility that the influence of the leakage magnetic flux may appear.

If magnetic flux leakage is a problem, FIG.
As shown in (1), it is necessary to form a magnetic gap with a non-magnetic material (inserted as a spacer). For example, a stainless steel plate 52 as a non-magnetic member may be overlapped with the electromagnetic steel plate 42 to form the slit 38 together with the electromagnetic steel plate 42 and sandwiched between the magnetic steel plate 48 for position detection. Of course, also in this case, each plate-shaped permanent magnet 46 is
2. It passes through the slit holes 38, 38 and 50 of the stainless steel plate 52 and the magnetic steel plate 48 for position detection.

If the gap between adjacent gap portions 38a and 38b is reduced from, for example, 5 mm to 1 mm so that the slit shape of the laminated electromagnetic steel plates 42 becomes the same as the slit shape of the magnetic steel plate 48 for position detection, This eliminates the need to use the position detecting magnetic steel sheet 48 at the end of the rotor.

Here, a basic motor drive circuit in this embodiment shown in FIG. 7 will be briefly described.

The three-phase stator windings U, V,
W is connected to a DC power supply 56 via a three-phase inverter circuit 54 configured by connecting three sets of two transistors connected in series to each other, each of which includes six diodes connected to a backflow prevention diode. The position detection signals from the three Hall ICs 22, 24 and 26 for detecting the rotational position of the permanent magnet rotor 18 are processed by the microcomputer 58 to generate a motor drive control signal. Circuit 5
4, the DC power supply 5
6 is converted into AC to convert three-phase stator windings U, V,
W is sequentially supplied with power. As a result, the motor 10 is driven to rotate to obtain a necessary rotational force.

[Brief description of the drawings]

FIG. 1 is an illustrative view showing a longitudinal section of a permanent magnet embedded type motor according to an embodiment of the present invention.

FIG. 2 is an illustrative cross-sectional view corresponding to the direction of arrow AA in FIG. 1;

FIG. 3 is a side view of a permanent magnet rotor including the rotation shaft of FIG. 1;

4 (a) and 4 (b) are illustrations of an electromagnetic steel sheet and a magnetic steel sheet each including a permanent magnet in a trapezoidal slit hole constituting a rotor section and a position detection section of the permanent magnet rotor shown in FIG. 3;

FIG. 5 is an illustrative view of a relevant part when the electromagnetic steel sheet and the magnetic steel sheet shown in FIG. 4 are overlapped;

FIG. 6 is an illustrative view of another embodiment corresponding to FIG. 3;

FIG. 7 is a block circuit diagram showing an example of a basic drive circuit of the motor.

FIGS. 8A and 8B are characteristic diagrams showing a magnetic flux density distribution between a rotor surface and a sensor (Hall IC) when an air gap is 1 mm.

FIGS. 9A and 9B are characteristic diagrams showing a magnetic flux density distribution between a conventional rotor surface and a sensor (Hall IC) when an air gap is set to 5 mm.

FIGS. 10 (a) and (b) are schematic illustrations of a main part of a rotor part and a motor part of a conventional permanent magnet embedded motor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Permanent magnet buried motor 14 ... Stator 18 ... Permanent magnet rotor 20 ... Mounting board 22, 24, 26 ... Hall IC (magnetic sensor) U, V, W ... Three-phase stator winding 38 ... Trapezoidal slit Holes 38a, 38b: gaps at both ends of trapezoidal slit hole 42: circular electromagnetic steel plate 46: plate-shaped permanent magnet 48: magnetic steel plate for position detection 50: trapezoidal slit hole 50a, 50b: gap portions at both ends of trapezoidal slit hole

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Mamoru Kubo 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Yoshio Togashi 2-5-5 Keihanhondori, Moriguchi-shi, Osaka No. 5 Sanyo Electric Co., Ltd. F-term (reference) 5H002 AA01 AB01 AC06 AE07 AE08 5H019 BB01 BB05 BB11 BB15 BB20 BB23 CC03 CC06 CC09 DD01 EE14 5H621 BB10 GA01 GA04 HH03 HH08 JK02 JK05 JK14 CA03CA03 PP07 PP10 PP11 QB06

Claims (4)

[Claims] 1. A permanent magnet rotor in which permanent magnets for a field are buried in slit holes of a rotor core formed by laminating magnetic steel sheets except for gaps at both ends, and a stator winding is provided on salient pole portions of the stator core. A stator equipped with a wire, and a magnetic sensor disposed on the stator side for detecting a position of the permanent magnet rotor,
In the permanent magnet embedded type motor, the electromagnetic steel plate is provided at the end of the rotor with a position detecting magnetic steel plate having a different slit hole shape facing the field permanent magnet, and further adjacent to the magnetic steel plate. The position of the permanent magnet embedded type motor, characterized in that the interval between adjacent gap portions of the slit holes is smaller than the interval between adjacent gap portions of the adjacent slit holes of the electromagnetic steel sheet constituting the rotor. Detection device. 2. The permanent magnet buried type according to claim 1, further comprising a non-magnetic member having the same shape as said electromagnetic steel sheet, between said electromagnetic steel sheet and said position detecting magnetic steel sheet constituting said rotor core. Motor position detector. 3. The position detecting device according to claim 2, wherein the non-magnetic member includes a stainless steel plate. 4. The position detecting apparatus according to claim 1, wherein said magnetic sensor includes a Hall element or a Hall IC.