System and method for regulating RMS voltage delivered to a load

摘要

A system and method for regulating the root mean square (RMS) voltage delivered to a load by an alternating current (AC) electrical circuit having a line voltage. To avoid radio frequency interference (RFI), the load is disconnected from the AC electrical circuit when energy stored in the load is at or near zero and is reconnected when the line voltage is at or near zero. Inductive loads are disconnected when the line current is at or near zero while capacitive loads are disconnected when the line voltage is at or near zero. The duration of the disconnection does not exceed one half-cycle of the fundamental frequency. Disconnections alternate between removing positive voltage half-cycles and negative voltage half-cycles to avoid a direct current (DC) bias. A system incorporating digital logic elements is provided for implementing the method and for detecting whether the load is inductive or capacitive.