JP2799748B2 - Three-phase semiconductor motor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-phase semiconductor motor used for a spindle motor of an information recording / reproducing apparatus, and more particularly, to a structure of a rotation phase detector of the motor.

2. Description of the Related Art A three-phase brushless motor is mainly used as a spindle motor for an information recording / reproducing apparatus such as a floppy disk drive.

Further, the three-phase brushless motor in this case is also called a three-phase semiconductor motor because it uses a Hall element as a rotation phase detecting means.

FIG. 5 is a partially cutaway perspective view of a conventional three-phase semiconductor motor,
FIG. 6 is a vector diagram showing a method for producing a three-phase rotational phase detector signal from only two-phase rotational phase detector signals, and FIG. 7 is a graph showing the state of output voltage and output current with respect to the rotational phase detector signal. It is.

Hereinafter, a conventional structure will be described with reference to FIGS.

In FIG. 5, the magnetic circuit of the three-phase semiconductor motor includes a fixed yoke 1, a permanent magnet (rotating magnet) 2, and a rotor yoke 3.

On the surface of the fixed yoke 1, six coils (armature coils) 7a to 7f (7b is not shown) and Hall elements 8a and 8b are fixed.

The six coils 7a to 7f are connected to each other so as to oppose each other, and each pair forms a U phase, a V phase, and a W phase.

There are only two Hall elements (rotational phase detectors), U-phase and V-phase, and the W-phase output is synthesized from the U-phase and V-phase.

 The method of driving the motor will be described later.

A bearing unit 6 is fitted in the center of the fixed yoke 1, and a spindle 5 is rotatably supported in the center of the bearing unit 6.

A boss 4 is fitted to the other end of the spindle 5.
, The rotor yoke 3 is fixed.

A permanent magnet (rotating magnet) 2 is fixed to a surface of the rotor yoke 3 on the fixed yoke 1 side, and the rotor yoke 3
A frequency generator (FG magnet) 9 for detecting the rotational speed
Is fixed.

Further, a speed detecting element 10 is arranged to face the side surface (outer peripheral surface) of the FG magnet 9.

Note that a holding table for supporting the speed detecting element 10 is not shown.

Next, a method (two-sensor method) for generating three-phase rotation phase signals from only two-phase rotation phase signals will be described with reference to FIG.

The following technical items are necessary as prerequisites for realizing the two-sensor system.

Condition I: The hall output waveform is a sine wave, and the third-order Fourier component is 20% or less.

In FIG. 6, the mapping of U to the x-axis is the output of the Hall element 8a, and the mapping of V to the x-axis is the output of the Hall element 8b.

= Cosωt + isinωt = cos (ωt + 2/3 · π) + isin (ωt + 2/3 · π) A vector can be calculated from the two vectors.

= −− = cos (ωt−2 / 3 · π) + isin (ωt−2 / 3 · π) FIG. 7 shows the time dependence of the input, output voltage and output current of the Hall amplifier.

Although the Hall amplifier inputs are only the U-phase and V-phase, the W-phase is created by the above-described calculation method.

Each phase of the output voltage is output corresponding to the vector.

 In FIG. 7, only the U-phase output current is shown.

The motor is rotationally driven by energizing each phase by 120 degrees in electrical angle.

FIG. 8 is a plan view of a conventional armature assembly.
The positions of the Hall elements 8a and 8b will be described with reference to FIG.

In FIG. 8, the Hall elements 8a and 8b are fixed in a gap at the center of the armature coil.

On the other hand, the permanent magnets 2 facing these Hall elements 8a and 8b are magnetized with a sine wave to satisfy the condition I.

[Technical problem to be solved by the invention]

However, in the above conventional example, since it is a two-sensor system,
Although the number of parts is reduced and there is a cost merit, on the other hand, since there is a restriction such as the condition I in the Hall amplifier input,
There were the following technical issues.

i) Since the sine wave magnetization is performed on the permanent magnet, the generated torque cannot be increased.

ii) In the type in which the rotational frequency signal is directly generated from the permanent magnet, the frequency signal is generated from the sine wave magnetization, and the signal amplitude cannot be increased.

SUMMARY OF THE INVENTION The present invention has been made in view of the above technical problem, and the invention of claim 1 can drive a two-lance motor without causing a decrease in motor output torque, and can reduce the size of the motor. It is an object of the present invention to provide a low-cost, high-performance three-phase semiconductor motor. The invention according to claim 2 is capable of driving a two-sense motor without causing a decrease in motor output torque. It is an object of the present invention to provide a low-cost, high-performance three-phase semiconductor motor capable of maximizing output.

[Means for solving the problem]

The invention according to claim 1 includes a rotating magnet and a fixed yoke provided with a plurality of armature coils opposed to the rotating magnet. The fixed yoke is provided in a space between the rotating magnet and the fixed yoke. In a two-sensor three-phase semiconductor motor provided with a rotating phase detector, the rotating magnet is magnetized with a rectangular wave, and at least two of the plurality of armature coils have a radial dimension on an inner circumferential side. The rotary phase detector is formed of a short coil and is installed inside the inner circumferential diameter of the magnetized portion of the rotating magnet and on the inner circumferential side of the armature coil which has been shortened. With the configuration described above, the above object is achieved.

The invention according to claim 2 includes a rotating magnet and a fixed yoke provided with a plurality of armature coils opposed to the rotating magnet, and the fixed yoke is provided in a space between the rotating magnet and the fixed yoke. In a two-sensor three-phase semiconductor motor provided with a rotating phase detector, the rotating magnet is rectangularly magnetized in a first annular portion from an inner peripheral diameter to a radially outer first radius. The second annular portion from the first radius to the radially outer second radius is sine wave magnetized, and the third annular portion from the second radius to the radially outer peripheral radius is square wave magnetized. The above object is achieved by a configuration in which the rotational phase detector is arranged at a position facing the second annular portion.

〔Example〕

Hereinafter, the present invention will be specifically described with reference to FIGS.

FIG. 1 is a plan view of an armature assembly of a three-phase semiconductor motor according to a first embodiment of the present invention as viewed from a permanent magnet side.

In FIG. 1, six armature coils 7a, 7b, 11a, 11b, 7e, 7f and two Hall elements 8a, 8b are fixed to the surface of the fixed yoke 1 on the permanent magnet side.

Here, r ₁ indicates the inner diameter of the permanent magnet 2, and r ₂ indicates the outer diameter of the permanent magnet 2.

 The permanent magnet 2 is magnetized with a rectangular wave.

Therefore, in the present embodiment, the armature coils 11a and 11b are constituted by short coils having short radial dimensions, and the Hall elements (rotational phase detectors) 8a and 8b are arranged in gaps formed inside the respective coils. Have been.

FIG. 2 is a schematic diagram for explaining the magnetic flux sensed by the Hall elements 8a and 8b. FIG. 2A is a cross-sectional view of the permanent magnet 2 and the rotor yoke 3 at the point r where the magnetic flux density on the permanent magnet surface is measured. _i, r _c, show the r _o, (B) is a diagram showing a Hall element output when the round with three respective radii.

As apparent from FIG. 2 (B), the Hall element output is made a sine wave at the inner r _i of the permanent magnet (rotary magnet) 2, becomes a square wave at the central portion r _c of the permanent magnet 2, the permanent outer r _o the third harmonic component of the magnet 2 is in large waveform.

From the characteristics shown in FIG. 2, in the embodiment shown in FIG. 1, since the Hall elements 8a and 8b are located on the inner side r _i of the permanent magnet 2, the outputs of the Hall elements 8a and 8b are sinusoidal. Signal.

In this case, it is not necessary for the permanent magnet 2 to perform sine wave magnetization.

The reason is that, generally, when short coils 11a and 11b as shown in FIG. 1 are used, imbalance of generated torque occurs due to asymmetry with other coils, which causes motor vibration and noise. However, since the outer diameter side actually contributes more to the torque and the inner portion contributes less to the torque, the above-described influence can be ignored.

According to the embodiment shown in FIG. 1, in addition to enabling the motor driving of the two-sense method without causing a decrease in the torque of the motor output, the rotating magnet 2 is magnetized with a rectangular wave and At least two of the armature coils 11
a, 11b are formed of short coils having a short radial dimension on the inner peripheral side, and the rotary phase detectors 8a, 8b are
Of an inner than the inner peripheral diameter r ₁ of magnetized portions, the short coiled been armature coils 11a, since the structure to be installed in a gap formed on the inner peripheral side of 11b, the short coils 11a, By installing the rotation phase detectors 8a and 8b using the gap on the inner peripheral side of 11b, it is possible to magnetize the inner peripheral side of the rotating magnet 2 and to achieve the miniaturization of the motor. .

FIG. 3 is a plan view of the armature assembly of the three-phase semiconductor motor according to the second embodiment of the present invention on the permanent magnet side.

In FIG. 3, the arrangement of the six armature coils 7a to 7f fixed on the fixed yoke 1 and the two rotational phase detectors (Hall elements) 8a and 8b is the same as the conventional structure of FIG. It is.

However, in the embodiment of FIG. 3, the method of magnetizing the permanent magnet 2 is different from that of the conventional example, and the magnet is magnetized as follows.

That is, the inner circumference in the annular portion of the radial r ₁ to a radius r ₃ which is set in the center is a rectangular wave magnetized, the annular portion from the radius r ₃ to a radius r ₄ that is set on the outside, Hall element 8a, 8b is a sine wave output (more than 20% tertiary component) magnetized such that (hereinafter, referred to as a sine wave magnetization) is applied, the square wave at the annular portion from the radius r ₄ to the outer diameter r ₂ It is magnetized.

Therefore, even on the surface of the fixed yoke 1 facing the permanent magnet 2, the opposing area between the radius r ₃ and r _4, i.e., the sine wave magnetized portions of the central portion of the permanent magnet 2 The Hall element (rotational phase detector) 8a at a position facing
8b is located.

Accordingly, the Hall element output can be a sine wave, moreover, since the inside and outside of the region r ₁ ~r ₃ and region r ₄ ~r ₂ in square wave magnetization can be larger torque output.

FIG. 4 shows that, according to the embodiment of FIG. 3, in addition to enabling the motor driving of the two-sance method without causing a decrease in the torque of the motor output, the rotating magnet 2 has an inner peripheral diameter r _1. A first annular portion extending radially outward from a first radius r ₃ to a second annular portion extending from the first radius r ₃ to a radially outer second radius r _4. in the sine wave magnetized, in the third annular portion from said second radius r ₄ to the radially outer peripheral diameter r ₂ is the square wave magnetized, the rotational phase detector 8a, 8b is the second As it is configured to be located at the position facing the annular part, the output of the rotational phase detectors 8a, 8b is made a sine wave, and the torque output is maximized by magnetizing the rectangular wave inside and outside the area can do. FIG. 7 is a partially cutaway perspective view of another configuration example of the three-phase semiconductor motor, in which a rotational phase detector (Hall element) is shown.
8a and 8b are outside the armature coils 7c and 7d, and
It is arranged at a position facing the lower surface of the magnet 9.

In this case, the lower surface of the FG magnet 9 is magnetized in a sine wave with the same number of poles as the permanent magnet 2.

The other parts of FIG. 4 are substantially the same as the structure of FIG. 5 described above, and corresponding parts are denoted by the same reference numerals, respectively, and detailed description thereof will be omitted.

The three-phase semiconductor motor having the structure described above with reference to FIG. 4 also has the same structure as the embodiment described with reference to FIGS.
The two-sensor system could be realized without lowering the output torque.

In the configuration example shown in FIG. 4, FG magnetization is performed on the side surface of the FG magnet 9 and sine wave magnetization is performed on the lower surface of the FG magnet 9 with the same number of poles as the permanent magnet 2. FG on the underside of FG magnet 9
Magnetization may be applied, and sine wave magnetization may be applied to the side surface of the FG magnet 9 with the same number of poles as the permanent magnet 2.

In that case, a frequency signal is output by forming an FG pattern on the surface of the fixed yoke 1 outside the armature coils 7a to 7f and facing the lower surface of the FG magnet 9.

In this case, the rotation phase detector (Hall element) 8
a and 8b are arranged facing the side surface of the FG magnet 9.

FIG. 9 is a schematic diagram showing a magnetizing method for carrying out the present invention. Hereinafter, a sine wave magnetizing method will be described with reference to FIG.

In FIG. 9, (A) shows a first method of sine wave magnetization, (B) and (C) show a second method of sine wave magnetization, and (D) shows a method of sine wave magnetization. A third method will be described.

FIG. 9A is a cross-sectional view of the portion 12 of the permanent magnet 2 subjected to the sine wave magnetization by the first method, wherein the arrow indicates the direction of magnetization, and the length of the arrow indicates the strength of magnetization. Show.

In the example shown in (A), magnetization is performed in which the intensity of magnetization is changed along the circumferential direction, and since the change in magnetization is sinusoidal, the Hall elements 8a and 8b output sine waves. .

FIGS. 9B and 9C show two structural examples of the permanent magnet 2 magnetized by the second method, in which a sine-wave magnetized portion 12 is set inside the permanent magnet 2. 12a indicates a magnetized portion, and 12b indicates a non-magnetized portion.

 The magnetization of the magnetized portion 12a is substantially uniform.

Along the circumferential direction of the sine wave magnetized portion, when magnetized by the method (B), the magnetized portions 12a and non-magnetized portions 12b are present alternately, and when magnetized by the method (C). Represents the ratio of the magnetized portion 12a to the non-magnetized portion 12b.

FIG. 9 (D) is obtained by cutting off the non-magnetized portion 12b in FIG. 9 (B) and forming sine wave magnetized.

When this sine wave magnetizing method is adopted, the sine wave magnetized portion may be formed by cutting the non-magnetized portion 12b after magnetizing as shown in FIG. 9 (C).

In practicing the present invention, as a method of sine wave magnetization, a method in which the magnetized portion has a structure in which the magnetization intensity changes along the circumferential direction (first method), A method (second method) in which the sum of the radial lengths of the non-magnetized portions is constant, and the ratio of the diameters of the magnetized portions and the non-magnetized portions changes along the circumferential direction (second method). Alternatively, various methods may be used, such as a method of forming a notch in the magnet 2 of the magnetized portion by cutting out the non-magnetized portion in the second embodiment (third method).

〔The invention's effect〕

As is apparent from the above description, according to the invention of claim 1, the rotating magnet and the fixed yoke provided with a plurality of armature coils opposed to the rotating magnet are provided. In a two-sensor three-phase semiconductor motor including a rotating phase detector provided on the fixed yoke in a space between the rotating yoke and the rotating magnet, the rotating magnet is magnetized with a rectangular wave and at least two of the plurality of armature coils are provided. One is formed of a short coil having a short radial dimension on the inner peripheral side, and the rotational phase detector is located inside the inner peripheral diameter of the magnetized portion of the rotating magnet, and the armature coil of the shortened coil is formed. Since it is configured to be installed in the gap formed on the inner circumference side, it is possible to drive the motor of the 2-sance method without lowering the torque of the motor output, and in addition to the inner circumference side of the short coil, By installing a rotation phase detector by utilizing a gap, a three-phase semiconductor motor to allow the magnetized on the inner peripheral side of the rotary magnet can achieve miniaturization of the motor is provided.

According to the invention of claim 2, there is provided a rotating magnet and a fixed yoke provided with a plurality of armature coils opposed to the rotating magnet, and the fixed yoke in a space sandwiched between the rotating magnet and the fixed yoke. In a two-sensor three-phase semiconductor motor having a rotating phase detector provided thereon, the rotating magnet is magnetized with a rectangular wave in a first annular portion from an inner diameter to a first outer radius in a radial direction, A second annular portion from the first radius to a radially outer second radius is magnetized with a sine wave, and a third annular portion from the second radius to a radially outer radius is a rectangular wave. The rotation phase detector is magnetized, and is arranged at a position facing the second annular portion, so that the motor drive of the two-sance method can be performed without causing a decrease in the torque of the motor output. In addition, the rotational position The output of the detector as well as a sine wave, a three-phase semiconductor motor capable of increasing the torque output to the maximum by square wave magnetization in the region of its inside and outside is provided.

[Brief description of the drawings]

FIG. 1 is a plan view of an armature assembly of one embodiment of a three-phase semiconductor motor according to the present invention, and FIG. 2 is a diagram showing a change in the output of a rotary phase detector due to a difference in the position of the rotary phase detector with respect to a rotary magnet. FIG. 3 is a plan view of an armature assembly of another embodiment of the three-phase semiconductor motor according to the present invention, FIG. 4 is a partially cutaway perspective view of another configuration example of the three-phase semiconductor motor, and FIG. FIG. 6 is a partially cutaway perspective view of a conventional three-phase semiconductor motor, FIG. 6 is a vector diagram showing a method of generating a three-phase rotational phase detector signal from only two-phase rotational phase detector signals, and FIG. FIG. 8 is a graph showing the state of output voltage and output current with respect to the detector signal, FIG. 8 is a plan view of an armature assembly of a conventional three-phase semiconductor motor, and FIG. It is a schematic diagram for demonstrating a magnetic method. 1 ... fixed yoke, 2 ... rotating magnet (permanent magnet), 3 ... rotor yoke, 5 ... spindle, 7a-7f
…… armature coil, 8a, 8b …… rotational phase detector (Hall element), 9 …… FG magnet, 11a, 11b …… armature coil, 12
... Sine wave magnetized area.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) H02K 29/00-29/14

Claims (2)

(57) [Claims] A rotating yoke; and a fixed yoke provided with a plurality of armature coils opposed to the rotating magnet, wherein a rotating phase is provided on the fixed yoke in a space sandwiched between the rotating magnet and the fixed yoke. 2 provided with detector
In the sensor-type three-phase semiconductor motor, the rotating magnet is magnetized with a rectangular wave, and at least two of the plurality of armature coils are formed of short coils having a short radial dimension on an inner peripheral side. The three-phase detector is installed in a gap formed inside the inner diameter of the magnetized portion of the rotating magnet and on the inner side of the armature coil having a reduced coil length. Semiconductor motor. 2. A rotary magnet, comprising: a rotating magnet; and a fixed yoke provided with a plurality of armature coils opposed to the rotating magnet, wherein a rotating phase is provided on the fixed yoke in a space sandwiched between the rotating magnet and the fixed yoke. 2 provided with detector
In the sensor-type three-phase semiconductor motor, the rotating magnet is magnetized with a rectangular wave in a first annular portion from an inner diameter to a first outer radius in a radial direction, and a radially outer magnet from the first radius. The second annular portion up to a radius of 2 is magnetized with a sine wave, and the third annular portion extending from the second radius to a radially outer periphery is magnetized with a rectangular wave, and the rotating phase detector is A three-phase semiconductor motor arranged at a position facing the second annular portion.