A microprocessor-based self-adjusting system for integral cycle power control of RL loads

Abstract

A microprocessor-based method is introduced to eliminate the DC current offset component in integral cycle-controlled resistive and inductive (RL) loads. After choosing a suitable initial value of the triac (or thyristor) firing angle alpha (90 degrees for best results), the microprocessor adjusts alpha , bringing it closer to the load power factor angle phi at every burst of conduction. A firing angle that is almost equal to phi is reached after few bursts. This eliminates the undesired DC current offset component. The use of the microprocessor allows a simpler and more flexible solution to the problem than conventional techniques. >