Permanent Magnet Motor with Field Weakening

A permanent-magnet electrical machine is disclosed in which the rotor or stator have at least one movable iron segment. A magnetic field of the electric machine is weakened when the movable iron segment is moved a position away from the rotor or stator, respectively. When the movable iron segment is in a first position, such as in contact with the rotor or stator, the field strength is high. When the movable iron segment is in a second position in which the movable iron segment is displaced away from the rotor or stator, the field strength is low. The ability to weaken the field strength causes the constant-power, speed ratio to be increased and thereby increases the utility of the electric machine for applications in which a wide speed range is desired. The electric machine may be used as both a permanent-magnet motor and generator.