Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1996-06-14
1998-04-14
Dougherty, Thomas M.
Electrical generator or motor structure
Dynamoelectric
Rotary
310268, 310266, 310 67R, 310121, 310264, 310265, 310114, H02K 1700
Patent
active
057396132
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a three-phase reluctance type motor which is flat in shape and capable of generating a large output and rotating at high speeds, preferably to be used as a drive source for a floppy disk and a hard disk.
BACKGROUND ART
The drive motor for a floppy disk or a hard disk is normally required to be so flat that the number of magnetic poles is restricted to approximately 15, and the width of a rotary magnet is required to be reduced to approximately 3 mm. Thus, such a drive motor has disadvantage in that its output torque is so small and its operating efficiency drops largely as its rotational speed increases.
However, when a drive motor is reluctance type, a larger output can be obtained even when it is made flat. However, a reluctance-type motor is generally characterized in that the magnetic path of armature coils, formed by salient poles and magnetic poles, is almost closed, enlarging its inductance. This enlarged inductance will increase the amount of magnetic energy stored in or discharged from magnetic poles or salient poles, and also will increase the repetition frequency of such energy storage and discharge during one complete revolution of the rotor. Thus, a reluctant-type motor has an advantage of being capable of producing a large output but has a disadvantage of being incapable of producing a high revolution speed.
DISCLOSURE OF INVENTION
An object of the present invention is to provide a flat, three-phase, reluctance type motor capable of generating a large output torque and rotating at high speeds.
In order to accomplish above purpose, the present invention provides a flat, three-phase, half-wave, reluctance type motor, comprising a flat stationary armature having a circumferential surface on which there are disposed three or its integral multiple number of magnetic poles wound by first, second and third phase armature coils, salient poles of a magnetic rotor fixed to the inside of the outer periphery of a cup-shaped rotor, a ball bearing supporting a rotational shaft of the cup-shaped rotor so as to allow the outer peripheral surface of the magnetic poles confronting the inner peripheral surface of the salient poles through a slight air gap therebetween to rotate when the rotational shaft is rotated, and a current supply control circuit for enabling the motor to rotate at a high speed by quickly controlling the supply of current to the first, second and third-phase armature coils in response to the position detection signals to be generated by detecting the positions of salient poles.
Furthermore, according to the present invention, it will be possible to provide a three-phase, full-phase, reluctance type motor by adding another set of a stationary armature and a rotor to the above-described three phase, half-wave, reluctance type motor. In this case, the torque ripple can be reduced by offsetting the phase of magnetic poles of one stationary armature by a predetermined electric angle from the phase of corresponding magnetic poles of the other stationary armature.
The current supply control circuit for supplying current to armature coils comprises an electric circuit designed to sharply decrease the flow of current through the armature coil by allowing the magnetic energy stored in the armature coil to flow, through a diode, into a small-capacitance capacity for being charged therein, when the supply of current to the armature coil is stopped, and, another electric circuit designed for sharply building up current by allowing the magnetic energy stored in the small-capacitance capacitor to flow into the armature coil simultaneously with start of current supply when the armature coil is supplied with the current.
With the above-described arrangement, it becomes possible to obtain a three-phase reluctance type motor flat in shape and being capable of generating a large output torque and rotating at high speeds.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a transversal cross-sectional view showing a three-phase reluctance type motor in accordance
REFERENCES:
patent: 3189770 (1965-06-01), Henry-Baudot
patent: 5138244 (1992-08-01), Bahn
patent: 5214365 (1993-05-01), Bahn
patent: 5218251 (1993-06-01), Allwine
patent: 5254892 (1993-10-01), Boseman et al.
patent: 5260635 (1993-11-01), Bahn
patent: 5406184 (1995-04-01), Bahn
Dougherty Thomas M.
Kabushikigaisha Sekogiken
Williams Timothy A.
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