Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1989-12-04
1991-05-14
Stephan, Steven L.
Electrical generator or motor structure
Dynamoelectric
Rotary
310114, 310181, 310186, 310261, H02K 2114
Patent
active
050159020
DESCRIPTION:
BRIEF SUMMARY
A multiphase, synchronous, electrical machine that is excited by a permanent magnet, incorporating a stator winding that is supplied with power through a static converter in such a way that apart from the primary excitation field produced by the permanent magnets there is an additional magnetic longitudinal field that is generated by the armature winding through which current flows, this additional longitudinal field being added to or subtracted from the primary excitation field in the magnets arranged within the winding-free rotor, as well as soft magnetic materials with intervening spaces of non-magnetic material which form loops that lie within each other and that are open towards the air gap, these enclosing the pole gap.
An electrical machine of this kind, excited by permanent magnets, which can be altered in the field, is known from DE-OS 34 01 163, in particular from FIGS. 10 and 11, and from pages 17 and 18. The known machine is based on a flow-concentration arrangement (collector configuration). The permanent magnets--which extend in a radial direction--each lie in a pole gap, and the pole is divided into two part poles by a central gap. The connection between the permanent magnets that are perpendicular to the gap between the part poles in their direction of flow and the air gap at the stator is achieved through a laminar soft-iron pole arrangement with interposed non-magnetic spaces. These soft iron laminations that are of steel that is magnetically conductive or of several layers of dynamo or core sheet, thus form loops that are located one within the other and are open to the air gap, and these enclose the pole gap in which the permanent magnet is located - which extends in a radial direction across all the soft-iron laminations and thereby interrupts the loop. The pole gap is formed in that the permanent magnet and the innermost loop of soft-iron laminations are at a distance from the air gap, the width of the pole gap being such that the excitation flux required for the magnetic longitudinal field that is to be superposed and that is additionally generated by the stator, is available. For this reason it must correspond to at least one groove division of the stator winding.
Because of this special constructive configuration of the rotor of the known electrical rotating machine that is excited by a permanent magnet, the basic excitation field for a specific degree of excitation is produced esclusively wattless from the permanent magnets, whereas higher and lower densities can be made available with the assistance of the armature excitation. This additional longitudinal magnetic field, generated by the stator, is superposed on the basic excitation field with variable signs and amounts. Thus the field of the machine with permanent-magnet excitation can be varied by this means. However, due to the flux concentration construction, considerable restrictions of the effectiveness of this known arrangement are caused by both the magnet resistance that is decisive for the stator longitudinal field because of the transverse arrangement of the permanent magnets to the magnetic longitudinal axis and the remaining armature cross field, and thus the cost for static converters or static frequency changers is relatively high.
For this reason, it is the task of the present invention to improve a multiphase electrical machine of this kind, which is excited by permanent magnet, with the possibility of field regulation (field attenuation) quantitatively so as to arrive at a higher field regulation range or so as to reduce expenditures for static converters or static frequency changers.
In order to solve this problem, in a multiphase electrical machine that is excited by permanent magnet, of the type described in the introduction hereto, according to the present invention the rotor is divided into at least two differently constructed sections that lie axially one behind the other, of which only the first section is provided with permanent magnets and the open loops of soft-magnetic material, and the other, second
REFERENCES:
patent: 3078381 (1963-02-01), Volkrodt et al.
patent: 4099106 (1978-07-01), Nikaido
patent: 4556809 (1985-12-01), Beisse et al.
patent: 4656379 (1987-04-01), McCarty
Rebsch D. L.
Siemens Aktiengesellschaft
Stephan Steven L.
LandOfFree
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