A permanent magnet generator having a plurality of permanent magnet generator units which produce a controlled output potential by mutual magnetic flux linkage between the permanent magnet generator units to produce the controlled output potential in accordance with the invention includes a plurality of permanent magnet rotors (20 and 22) mounted on a drive shaft (26) with at least one of the rotors being rotatable with respect to the drive shaft to vary an angular position of the at least one of the rotors relative to the shaft to produce a mutual variable magnitude magnetic axial field extending parallel to the drive shaft; at least one stator (26, 28, 72) disposed at a position axially offset from the plurality of rotors which is magnetically coupled to the variable magnitude permanent magnet axially field; and a mechanism (46, 48) responsive to a stator fault for angularly positioning the rotors relative to each other so that the permanent magnetic field coupled to the at least one stator is zero.
