Electricity: motive power systems – Synchronous motor systems – Hysteresis or reluctance motor systems
Patent
1991-04-30
1993-05-25
Ro, Bentsu
Electricity: motive power systems
Synchronous motor systems
Hysteresis or reluctance motor systems
318254, H02K 1910
Patent
active
052143651
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a three-phase reluctance type electrical motor, which is used as a driving source instead of a conventional DC motor and an induction motor having an inverter, and which is used particularly when a motor of a small diameter and small output torque is required or when a narrow and long type motor having a large output power and less vibration is necessary.
2. Description of the Related Art
A reluctance type electric motor is well known in the art and it can provide a large output torque. Although it has been used in a robot arm as a direct driving device for a load, no such a device is available on the market and put into practice since the rotation of speed thereof is extremely low.
The motor is sometimes used as a small stepping motor, but wide application thereof is not yet found.
SUMMARY OF THE INVENTION
As the first subject problem to be solved by this invention, there is a problem that the reluctance type motor generates large amount of mechanical vibration and noise caused by the mechanical vibration. A detailed explanation thereof is made later.
As the second subject problem, there is a problem that, in the reluctance type motor, magnetic flux between magnetic and salient poles for generating rotation torque flows into other magnetic and salient poles to generate counter torque since the salient pole of a rotor and the magnetic pole producing a field are set substantially in a short-circuited state (because a gap between the salient pole and the magnetic pole is small) magnetic path. Therefore, a problem occurs in that the output torque is reduced and the efficiency is lowered.
As a third subject problem, there is a problem that a reluctance type semiconductor motor cannot be formed to have a large number of phases unlike an ordinary commutator motor. This is because the price of the semiconductor circuit on each phase is high and it becomes less practical.
Therefore, stored magnetic energy of each magnetic pole increases and it takes a long time to discharge and store the magnetic energy, and a problem occurs in that high speed cannot be attained although high torque can be attained.
As the fourth subject problem, there is a problem that it is difficult to construct a reluctance type motor of small output power with a small diameter because the number of salient poles becomes larger.
Accordingly, an object of this invention is to provide a small sized three-phase reluctance type electric motor of high speed and high torque in which generation of mechanical vibration and noise can be suppressed in the driving operation.
According to this invention a three-phase reluctance type electric motor of three-phase half-wave energization type comprise a fixed armature having an outer peripheral surface fixed on an outer casing; a rotation shaft rotatably supported by bearings disposed on both sides of the outer casing; a magnetic rotor fixed on the rotation shaft; eight salient poles of the same height formed to project to the outer peripheral surface of the magnetic rotor, having a width of 180 electrical degrees and disposed at a regular pitch; first-phase magnetic poles formed to project from the inner peripheral surface of the fixed armature, having a width of 180 electrical degrees and separated by the same angle, the end portions thereof facing the salient poles with a small gap set therebetween and every two of the first-phase magnetic poles constituting a pair; second- and third-phase magnetic poles having the same construction as the first-phase magnetic poles and disposed to be sequentially separated from the first-phase magnetic poles by 120 mechanical degrees; a position detecting unit for detecting the position of the salient poles of the magnetic rotor by use of position detecting elements to generate a first position detection signal of first-phase rectangular wave and to generate second and third position detection signals of the same waveform and of the second and third phases which are successively generated
REFERENCES:
patent: 4025859 (1977-05-01), Smith
patent: 4506207 (1985-03-01), Ferrari
patent: 4647802 (1987-03-01), Konecny
patent: 4748362 (1988-05-01), Hedlund
patent: 4883999 (1989-11-01), Hendershot
patent: 4998032 (1991-03-01), Burgbacher
patent: 5043643 (1991-08-01), Hedlund et al.
Kabushikigaisha Sekogiken
Ro Bentsu
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