BESKYTTELSE AF EN PERMANENT MAGNETGENERATOR

A method for protecting a permanent magnet generator of a wind turbine with a multiphase generator, and n number of isolated converters, the multiphase generator including a rotor carrying permanent magnets and n number of independent multiphase sub-stators comprising a plurality of windings, each converter being connected to an independent multiphase sub-stator and configured to control the plurality of windings of the multiphase sub-stator comprises determining an asymmetrical short circuit current in one of the sub-stators, which generates a first oscillating torque, disconnecting the converter linked to the sub-stator with an asymmetrically short circuited group of windings, and injecting an asymmetrical current with the remaining connected converters, wherein said injected asymmetrical current generates a second oscillating torque that is substantially opposed in phase to the first oscillating torque so that the first oscillating torque is at least partly compensated is disclosed. Permanent magnet generators are also disclosed.