For certain applications, permanent magnets can provide the magnetic field of a generator. The rotor structure can provided by a doughnut of magnetic iron with magnets fixed on its surface.
A magnetic flux density can be provided using by a radial depth of various types of magnetic materials comprising of neodymium-boron-iron or samarium-cobalt of less than 10 millimetres in the air gap corresponding to that produced with field windings.
A considerable reduction in air-gap flux density can be achieved by using magnet materials such as ferrite. Although this causes a corresponding increase in dimensions of the generator.
Permanent-magnet generators are simple because no system for the provision of field current is required. Although they are very dependable but they do not carry any means for assuring the output voltage.
A true example of application is with a wind turbine where the generator output of variable voltage and frequency is supplied to a power system through an electronic frequency converter.
A magnetic flux density can be provided using by a radial depth of various types of magnetic materials comprising of neodymium-boron-iron or samarium-cobalt of less than 10 millimetres in the air gap corresponding to that produced with field windings.
A considerable reduction in air-gap flux density can be achieved by using magnet materials such as ferrite. Although this causes a corresponding increase in dimensions of the generator.
Permanent-magnet generators are simple because no system for the provision of field current is required. Although they are very dependable but they do not carry any means for assuring the output voltage.
A true example of application is with a wind turbine where the generator output of variable voltage and frequency is supplied to a power system through an electronic frequency converter.
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