Variable reluctance motor systems

Details Variable reluctance motor systems Variable reluctance motor systems

1998-06-18

1999-12-21

Ramirez, Nestor

Electrical generator or motor structure

Dynamoelectric

Rotary

310186, 310167, 318701, H02K 1906

Patent

active

060053216

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
This invention relates to variable reluctance motor systems.
2. Description of Related Art
A single phase variable reluctance motor system typically comprises a stator having a pair of oppositely disposed salient poles provided with energising windings, a rotor having a pair of oppositely disposed salient poles without windings, and a control circuit for rotating the rotor by supplying current pulses to the stator windings in synchronism with rotation of the rotor. Such a motor system offers the advantage, over a conventional motor system having rotor windings, that commutator brushes, which are wearing parts, are not required for supply of current to the rotor. Furthermore significant advantages over other motor systems are provided by the fact that there are no conductors on the rotor, and high-permanence magnets are not used in the motor construction.
However, although they are simple in construction, conventional single phase variable reluctance motor systems suffer from the fact that they are non-self-starting since it is inherent in their construction that positive torque is available for only 180.degree. at most per 360.degree. cycle, and there are large zones (of about 90.degree.) intermediate the stator poles where positive torque is not available so that, if the rotor has stopped with its poles orientated in these zones, the motor system cannot be re-started without first having to turn the rotor to a position in which torque becomes available. This rules out such single phase variable reluctance motor systems for certain applications and in particular for driving difficult loads such as those which combine direct drive and high friction, for instance.


SUMMARY OF THE INVENTION

It is an object of the invention to provide a hybrid single-phase variable reluctance motor system which is capable of generating driving torque for starting at substantially all rotor positions.
According to the present invention there is provided a hybrid single-phase variable reluctance motor system comprising a stator having a pair of substantially oppositely disposed salient main poles provided with at least one main winding and oppositely disposed salient auxiliary poles provided with at least one auxiliary winding and disposed intermediate the main poles on the stator, a rotor having a pair of substantially oppositely disposed salient poles without windings, and control means for rotating the rotor during normal running by supplying current pulses to said at least one main stator winding in synchronism with rotation of the rotor and for rotating the rotor on starting and/or low speed operation by supplying current pulses to both the main and auxiliary stator windings in synchronism with rotation of the rotor, wherein two pairs of oppositely disposed salient auxiliary poles provided with auxiliary windings are disposed on the stator intermediate the main poles
By supply of current pulses to the auxiliary stator windings as well as the main stator windings on starting, it is possible to ensure that positive torque can be produced at substantially all rotor positions, thus guaranteeing that the motor system can be started regardless of the position in which the rotor has previously come to rest. Preferably the arrangement is such as to be capable of generating bidirectional driving torque at all rotor positions on starting, thus rendering both starting in either direction and reversing possible, whilst allowing the normal advantages associated with a single-phase variable reluctance motor system during normal running. Such advantages include high efficiency at high speed due to the lower iron losses associated with lower pulsing frequency as compared with variable reluctance motor systems of two or more phases.


BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention may be more fully understood, a preferred embodiment of hybrid single-phase variable reluctance motor system in accordance with the invention will now be described, by way of example, with re

REFERENCES:
patent: 4942345 (1990-07-01), Horst

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