a dc dynamoelectric machine with interpoles between field poles operable in sparkles even under heavy operating conditions comprising a solid soft iron magnetic flux bypassing members , each disposed between respective field poles and interpoles at their ends near its armature with an air gap between the field pole for controlling interpole magnetic flux , the solid soft iron magnetic flux bypassing member suppresses sudden change of magnetic flux flowing therethough by permitting flow of eddy current therethrough and maintains the interpole magnetic flux at a desired amount even during a sudden change of load current .