Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1992-06-10
1994-03-15
Skudy, R.
Electrical generator or motor structure
Dynamoelectric
Rotary
310162, 310183, 310198, 310210, H02K 124
Patent
active
052948579
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a synchronous machine having a salient pole rotor.
A method and an arrangement for reducing at least one frequency component of a periodic pulsation is described in European Patent No. EP-A1-0 268 160. In this arrangement, a synchronous generator is driven by a drive motor. Particularly a high-power synchronous generator driven by a diesel engine, and pulsations of an electrical quantity are compensated at the output of the synchronous generator with a frequency that deviates from the synchronous generator's own frequency. The control is effected on the path formed by the diesel engine, generator and power system by intervening in the excitation of the generator (i.e., by controlling the direct-axis magnetic field) or by influencing the operating conditions of the diesel engine (quantity and timing of the fuel injection are controlled), or by an impedance (adjustable additional load) arranged at the output of the generator. These types of control are costly, since in some circumstances one of these measures is not sufficient by itself to achieve a complete compensation of the periodic pulsation.
An object of the present invention is to provide a synchronous machine of the type mentioned above, in which the effects of mechanical oscillations of the salient pole rotor, which can be attributed to influences both on the drive side and on the load side, are compensated in a simple manner.
SUMMARY OF THE INVENTION
In the synchronous machine of the present invention, in addition to the exciting coils which generate a controllable direct-axis magnetic field in a conventional manner, control coils are provided which generate a controllable quadrature-axis magnetic field. The control coils are arranged on the salient pole rotor in such a way that the quadrature-axis magnetic field generated by the control coils is superimposed on the direct-axis magnetic field in the air gap. Therefore, an additional intervention parameter is obtained for compensating the fluctuations caused by mechanical oscillations of the salient pole rotor on the electrical side.
As a result of the control of the quadrature-axis magnetic field simultaneously with the mechanical oscillations, a regularly rotating fundamental flux resulting from the direct-axis magnetic field and quadrature-axis magnetic field can be accomplished. Comparable operating conditions to those of a regularly rotating salient pole rotor are thus obtained, that is to say without oscillations.
The arrangement of these control coils is advantageous in high-power slow-running synchronous generators which are driven, for example, by diesel engines having an irregular torque. Until this time, generators of this type have had to be dimensioned in such a way that they have a correspondingly high mass moment of inertia, which is unfavorable with respect to costs and to weight and space requirements.
The quadrature-axis magnetic field generated by the control coils is superimposed on the direct-axis magnetic field. In order to achieve this, it is possible, to provide control coils which are arranged on additional poles designed in the manner of commutating poles. Apart from the constructional problems and the manufacturing outlay for such additional poles, with such an arrangement of the control coils, the pole pitch for the direct-axis magnetic field and hence the machine utilization (output for a given machine volume) would be reduced to a relatively high degree. Moreover, with the aforementioned arrangement it is not readily possible to achieve sufficiently high amplitudes for the quadrature-axis magnetic field.
In an embodiment of the synchronous machine of the invention, both a high pole pitch for the direct-axis magnetic field and a sufficiently high amplitude for the quadrature-axis magnetic field is ensured. By virtue of the arrangement of the control coils according to the invention, the quadrature-axis magnetic field essentially permeates only the pole shoes, that is to say only the upper pole region adjoin
REFERENCES:
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patent: 3127532 (1964-03-01), Gynt
patent: 3870912 (1975-03-01), Kipke
patent: 4435664 (1984-03-01), Boesel
patent: 4937486 (1990-06-01), Schwanda
Patent Abstracts Of Japan, vol. 8, No. 281, Dec. 21, 1984, & JP-A-59 148554 (Fuji Denki Seizo K.K.) Aug. 25, 1984.
Auinger Herbert
Waldmann Hermann
Siemens Aktiengesellschaft
Skudy R.
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