Electricity: motive power systems – Open-loop stepping motor control systems
Patent
1994-08-09
1997-07-29
Sircus, Brian
Electricity: motive power systems
Open-loop stepping motor control systems
318254, H02P 312
Patent
active
056524927
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a current supply control circuit for a reluctance motor designed to supply the armature coils with armature current flowing in both forward and backward directions.
BACKGROUND ART
A reluctance motor with a fixed armature having a magnetic pole wound repeatedly with armature coils of plural phases will be explained hereinafter with respect to current supply to the armature coils. In the following explanation, angles without any special comments are electric angles.
Furthermore, in the following description, the terms "one direction" may be replaced with the terms "forward direction" or "going direction", while the term "the other direction" may be replaced with the term "reverse direction" or "returning direction".
FIG. 1 is a cross-sectional view showing a fixed armature and a rotor. Rotors 1, each formed by laminating electromagnetic steel sheets, are equipped with salient poles 1a, 1b, each having a width of 180 degrees (=90 degrees in terms of mechanical angle), and are mutually spaced with a phase difference of 360 degrees. A rotational shaft 2 is provided at a center of the rotor 1. The arrow A indicates a rotational direction of the rotor 1.
A fixed armature 3, similarly formed by laminating electromagnetic steel sheets, has an inside surface provided with twelve uniformly spaced slots 3a, 3b, 3c, - - - , and is fixed to a frame member 4.
The slots 3a, 3d are respectively wound with one coil, while the slots 3g, 3j are respectively wound with another coil. To constitute a 1st-phase armature coil, these two coils are connected with each other in series or in parallel, although they are connected in series in this embodiment.
The slots 3b, 3e be are wound with one coil, while the slots 3h, 3k are wound with another coil. These two coils are connected with each other in series, thus constituting a 2nd-phase armature coil.
The slots 3c, 3f are wound with one coil, while the slots 3i, 3l are wound with another coil. These two coils are connected with each other in series, thus constituting a 3rd-phase armature coil.
FIG. 2 is an embodiment showing the rotor 1, a rotational plate 15 detecting the position of rotor 1, and armature coils.
In FIG. 2, armature coils 5a and 5d represent the previously-described 1st-phase armature coil. Armature coils 5b and 5e represent the previously-described 2nd-phase armature coil. Armature coils 5c and 5f represent the previously-described 3rd-phase armature coil. Lead terminals of 1st-, 2nd- and 3rd-phase armature coils are denoted by reference numerals 6a, 6b and 6c, 6d and 6e, 6f, respectively.
The above-described 1st-, 2nd- and 3rd-phase armature coils 5a, 5d and 5b, 5e and 5c, 5f are referred to as armature coils 7a, 7b and 7c, respectively, hereinafter.
Next, an explanation will be made as to the case where the above-described armature coils 7a, 7b and 7c are respectively supplied with electric current through a well-known current supply control circuit which has switching elements at the side of the positive pole as well as at the side of the negative pole of the armature coil, and designed to supply the current flowing in one direction, from the side of the positive pole to the side of negative pole of the armature coil.
In FIGS. 1 and 2, when the armature coil 7b is activated, the salient poles 1a and 1b are magnetically attracted, causing the rotor 1 to rotate in a direction of the arrow A. When the rotor 1 rotates 90 degrees, the armature coil 7b is deactivated, and the armature coil 7c is activated. When the rotor 1 further rotates 120 degrees, the armature coil 7c is deactivated, and the armature coil 7a is activated. A current supply mode is cyclically alternated in every 120-degree rotation in order of armature coil 7a.fwdarw.armature coil 7b.fwdarw.armature coil 7c. That is, the armature coils are supplied with electric current in order of 1st-phase.fwdarw.2rd-phase.fwdarw.3rd phase. Repetition of such a current supply mode enables a motor to be driven as a three-phase half-wave motor.
As indicated by the
REFERENCES:
patent: 3624472 (1971-11-01), Graham
patent: 4024444 (1977-05-01), Dewan et al.
patent: 4763049 (1988-08-01), Magee
patent: 4774443 (1988-09-01), Herzig
patent: 5334919 (1994-08-01), Willard
Kabushikigaisha Sekogiken
Sircus Brian
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