Reluctance type motor

Details Reluctance type motor Reluctance type motor

2000-02-18

2001-05-22

Mullins, Burt (Department: 2834)

Electrical generator or motor structure

Dynamoelectric

Rotary

C310S254100, C310S269000, C318S701000

Reexamination Certificate

active

06236132

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a multi-phase half-wave reluctance type electrical motor and a driving method therefor.
2. Description of the Related Art
A reluctance type motor is generally simple in structure and provides high output torque. However, it has been used in a limited field because of its high torque ripples.
JP-A-1-318579 proposes a method of reducing the torque ripples by increasing the number of poles. In such a method, phase current is switched on and off in an electrically tandem switching manner. However, the magnetic flux for generating output torque in the reluctance motor disclosed in the publication flows through portions of the stator that generate counter torque. This does not sufficiently reduce such torque ripples.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an improved reluctance type motor which can reduce such counter torque in a simple structure.
According to a main feature of the invention, a multi-phase reluctance type motor including a rotor having 2n rotor protrusions with an arc angle X°, a stator having 2m of stator protrusions with an arc angle Y° and m pairs of exciting coils. Each of the pairs of exciting coils is disposed around one of said stator protrusions spaced apart at 180° in mechanical angle, and the following conditions are necessary: q≧5, X°, Y°>360°/(n×q), X°+Y°=180°
−&agr;°, where &agr;° is a counter torque marginal angle which is larger than 0°.
According to another feature of the invention, at least the rotor protrusions or the stator protrusions of the above reluctance motor have a plurality of slits. As portions of the rotor protrusion and the stator protrusion overlapping with each other increase, magnetic flux flowing therethrough increases, so that a flat torque characteristic can be provided.
According to another feature of the invention, each of the stator protrusions has a wider base portion than other portions. As a result, magnetic saturation of the stator protrusion due to leakage flux from the sides of the stator protrusions can be reduced, thereby preventing reduction in the output torque at a latter part of the energizing period of the exciting-coils.
According to another feature of the invention, in a method of driving the reluctance type motor as stated above, the exciting coils are energized at a mechanical angle not larger than &agr;° in advance of the rotor every 360°/(2n×q) mechanical angle. As a result the exciting coils can be energized in a shorter time, the torque ripples can be reduced and the output torque can be increased.


REFERENCES:
patent: 4647802 (1987-03-01), Koneeny
patent: 5111095 (1992-05-01), Hendershot
patent: 5717269 (1998-02-01), Tang
patent: 5747912 (1998-05-01), Sakuma et al.
patent: 5777416 (1998-07-01), Kolomeitsev
patent: 5838087 (1998-11-01), Tang
patent: 63-283457 (1988-11-01), None
patent: 1-318579 (1989-12-01), None
Denki Gakkai Kenkyuukai Shiryou RM-96-1-5, Ohno et al. “Performance Characteristic of Switched Reluctance Motor”, Published on Mar. 1, 1996.

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