Electromagnetic rotating apparatus

Electromagnetic rotating apparatus comprising a rotating shaft, a bi-polar permanent magnet fixed to said rotating shaft and radially magnetized, a non-magnetic insulating fixed core having a plurality of axially extending slots formed in the outer peripheral surface of a hollow cylinder which embraces rotating side and peripheral surfaces of said permanent magnet, a fixed solenoid coil wound around said core so as to surround said permanent magnet, a holding soft magnetic segment fixed to both opposite end portions of said outer peripheral surface of said fixed coil so as to close the open ends of said fixed coil, an energizing circuit to selectively energize said fixed coil positively or inversely, and first and second stoppers to limit the rotating of said permanent magnet within an angular range of less than 180 degrees and make maximum the magnetic flux interlinking with said fixed coil.