Barrier movement operator having obstruction detection

摘要

A barrier movement operator includes an A.C. motor having a rotatable rotor connected to a barrier for movement thereof. A sensing apparatus generates motor signals representing an operational variable of the motor. The movement of the barrier is controlled by a controller, which responds to the motor signals by selectively stopping rotation of the rotor or reversing the rotation of the rotor. A power control arrangement provides energizing power to the motor by receiving AC power input substantially in the form of a sine wave and conducts portions of successive cycles of the sine wave of the received AC power to the motor to enhance the sensed operational variable to torque characteristic of the motor.