Electricity: motive power systems – Synchronous motor systems – Hysteresis or reluctance motor systems
Patent
1990-02-21
1991-02-05
Ro, Bentsu
Electricity: motive power systems
Synchronous motor systems
Hysteresis or reluctance motor systems
318254, H02P 602
Patent
active
049908430
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
In reluctance motors it is common to provide stator poles which are cooperating in pairs and which are equally disposed along the way of movement of the rotor poles. Like the stator, the rotor has a shape such that its poles are cooperating in pairs. Hence, during the turning of the rotor, the two poles of a stator pole pair simultaneously cooperate with the corresponding poles of a rotor pole pair. In operation, the stator pole pairs are connected to a source of DC voltage in proper order and, in principle, a selected stator pole pair is connected to the DC voltage upon a rotor pole being about to turn over the stator pole. The voltage remains until the rotor pole has been fully turned over the stator pole. For the control of the motor speed the moments of connecting and disconnecting, respectively, of the supply voltage can be varied.
Detailed information about reluctance motors of the kind indicated has been published under the heading "Variable-speed Switched Reluctance Motors" in IEE PROC., Vol. 127, Pt. B, No. 4, July 1980.
The moments of connection and disconnection of the stator pole pairs are controlled by sensors indicating those positions in which a rotor pole begins to overlap a stator pole. In order for the rotor at start to turn in the desired direction, up to now one sensor has been required for each stator pole pair.
SUMMARY OF THE INVENTION
The object of the invention is to simplify a reluctance motor of the kind indicated so that irrespective of the number of poles only one sensor be required for start of the motor in the desired one of the two possible directions of rotation. The object will be achieved in a motor having the features indicated in the appending claims.
BRIEF DESCRIPTION OF THE DRAWINGS
A reluctance motor according to the invention will now be described in detail with reference to the enclosed drawings.
FIG. 1 schematically shows the construction of a reluctance motor having six stator poles and four rotor poles.
FIG. 2 shows in perspective the rotor shaft of the motor of FIG. 1 completed by a sensor device.
FIG. 3 shows the three-sensor positions prior art arrangement.
FIGS. 4 and 5 show two different sensor discs to be used in a single sensor arrangement according to the invention.
FIG. 6 is a diagram of sensor signal waveforms of a motor constructed in accordance with FIG. 1 and including three sensors according to prior art.
FIGS. 7 and 8 are diagrams of sensor signal waveforms relating to the single sensor embodiments of FIG. 4 and FIG. 5, respectively.
Finally, FIG. 9 is a block diagram of a control device for a reluctance motor of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the paper referred to above, formulas have been given for the calculation of optimum combinations of pole numbers of the stator and the rotor. The embodiment chosen is one such optimum combination wherein a reluctance motor 10, which is schematically shown in FIG. 1, comprises a stator 11 having six poles and a rotor 12 having four poles. The stator poles are disposed so as to form pairs of poles in each of which the poles are diametrically opposite each other and three pole pairs 1,1': 2,2'; 3,3' are evenly distributed along the way of movement of the rotor poles generally designated 13. The pole surface of each stator pole has an extension along the way of movement of the rotor poles which equals the pole gap between two stator poles. The four rotor poles 13 are situated so as to form a cross and the pole surfaces have an extension along the way of movement of the rotor causing a rotor pole which is, just in front of a stator pole to completely match the stator pole.
The rotor is made from soft magnetic material and the stator poles are magnetized by means of windings 14,15 which via terminals 16,17, schematically indicated, connect the poles of a pole pair in series to a DC source such that the poles cooperate to drive the motor in the direction chosen. Between the DC source, designated 18 in FIG. 9, and the respective pair 14,15 of
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patent: 4616165 (1986-10-01), Compter
patent: 4631459 (1986-12-01), Fujioka et al.
patent: 4748387 (1988-05-01), Tanuma et al.
patent: 4777419 (1988-10-01), Obradovic
patent: 4814676 (1989-03-01), Van Hout
patent: 4835448 (1989-05-01), Dishner et al.
patent: 4882523 (1989-11-01), Denzlingen
Hedlund Bengt G.
Moren Lars G.
Electrolux Mecatronik Aktiebolag
Ro Bentsu
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