Electricity: motive power systems – Positional servo systems – Digital or numerical systems
Patent
1997-05-29
1999-07-20
Martin, David
Electricity: motive power systems
Positional servo systems
Digital or numerical systems
318254, 318701, 318439, G05B 1929
Patent
active
059260009
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an improvement of a position detector for a three-phase DC motor.
RELATED ART
A three-phase DC motor (e.g., reluctance motor) requires use of an apparatus for obtaining three-phase position detection signals. Conventionally, therefore, three coils for use as position detecting elements are fixed to the body of the motor, while a conductor rotor is made to rotate synchronously with the motor. When the conductor rotor rotates facing the coils, change in the impedance of each coil is detected through the conductor rotor, whereby the three-phase position detection signals are obtained.
As described above, according to the prior art, the three-phase DC motor requires three position detecting coils, and this gives rise to problems such as complicated construction, large-sized body, and resultant high cost.
SUMMARY OF THE INVENTION
The object of the present invention is to provide an apparatus for obtaining three-phase position detection signals for a three-phase DC motor by means of two position detecting coils.
In order to achieve the above object, a plurality of projections, half-projections, and recesses, each having a width equal to an electrical angle of 120 degrees, are formed on the outer peripheral portion of a conductor disk that rotates synchronously with a motor. On the other hand, a stationary armature has a first coil, which is located in a position so that it faces only the projections, and a second coil, which is located in a position so that it faces the projections and the half-projections but does not face the outer periphery of the disk that constitutes the recesses. The first and second coils are energized, and three-phase position detection signals are obtained in accordance with the mode of change in impedances corresponding to a first section in which the projections face the first and second coils, a second section in which the half-projections face only the second coil, and a third section in which none of the projections and half-projections face either coil.
According to the present invention, as described above, the three-phase position detection signals can be obtained using two coils, as one set of components, for position detection. As a result, an electric circuit for obtaining the position detection signals can be simplified.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view showing a stationary armature and a rotor of a reluctance motor;
FIG. 2 is a side view of an apparatus for obtaining position detection signals according to the present invention;
FIG. 3 is a plan view of a rotating disk for position detection of the apparatus of FIG. 2;
FIG. 4 is a development view showing the armature and the rotor of FIG. 1;
FIG. 5 is a development view showing the rotating disk for position detection of FIG. 3;
FIG. 6 shows an example of an electric circuit diagram of the apparatus of FIG. 2;
FIG. 7 shows another example different from the electric circuit diagram of FIG. 6;
FIG. 8 is a plan view of a position detecting coil of the apparatus of FIG. 2; and
FIGS. 9(a)-9(e) are graphs showing signals delivered from output terminals of the circuits shown in the electric circuit diagrams of FIGS. 6 and 7.
BEST MODE OF CARRYING OUT THE INVENTION
Referring first to the plan view of FIG. 1 and the development view of FIG. 4, an arrangement of a three-phase-polarization reluctance motor to which the present invention is applied will be described. In the description to follow, all the angle indications are of electrical angle.
Referring to FIG. 1, a rotor 1 and a stationary armature 14 of the reluctance motor will be described. Eight salient poles 1a, 1b, 1c, . . . 1h are formed at regular intervals in the circumferential direction around the rotor 1. The width of each salient pole measures 180 degrees, and the salient pole (1a) and its adjacent salient pole (1b) have a phase difference of 360 degrees. This rotor 1 is made from well-known means obtained by laminating silicon steel sheets. The rotor 1 is fixed to a rotating shaft 5
REFERENCES:
patent: 4107587 (1978-08-01), Ban et al.
patent: 4818908 (1989-04-01), Tamae et al.
patent: 5331262 (1994-07-01), Francisco
Kabushikigaisha Sekogiken
Martin David
LandOfFree
Apparatus for obtaining three-phase position detection signals b does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus for obtaining three-phase position detection signals b, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus for obtaining three-phase position detection signals b will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1324608