Barrier movement operator speed control

摘要

Methods and apparatus for controlling the speed of an A.C. induction motor are disclosed and shown in operation for controlling the movement of a barrier. Included are voltage configuration circuits which selectively gate portions of the half-cycles of AC mains voltage to the induction motor. When the motor is started increasing amounts of mains AC voltage is applied to the motor and decreasing portions of the mains AC are applied to the motor during a stopping routine. The motor can also be energized with less than full mains AC to permit differences in barrier movement speed dependent on operating parameters.