H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
H01F7/00—Magnets
H01F7/06—Electromagnets; Actuators including electromagnets
H01F7/08—Electromagnets; Actuators including electromagnets with armatures
H01F7/18—Circuit arrangements for obtaining desired operating characteristics, e.g. for slow operation, for sequential energisation of windings, for high-speed energisation of windings
H—ELECTRICITY
H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
H02P9/00—Arrangements for controlling electric generators for the purpose of obtaining a desired output
H02P9/14—Arrangements for controlling electric generators for the purpose of obtaining a desired output by variation of field
H02P9/20—Arrangements for controlling electric generators for the purpose of obtaining a desired output by variation of field due to variation of continuously-variable ohmic resistance
H02P9/22—Arrangements for controlling electric generators for the purpose of obtaining a desired output by variation of field due to variation of continuously-variable ohmic resistance comprising carbon pile resistance