Phase control circuit having independent half cycles

摘要

A phase control circuit according to the present invention is configured for connection between and AC source and an AC load. The AC source supplies an AC drive signal having a plurality of sequential positive and negative half cycles. The phase control circuit comprises first and second power switches coupled between the AC source and the AC load. The first power switch conducts current of the AC drive signal after a first phase delay during the positive half cycles. The second power switch conducts current of the AC drive signal after a second phase delay during the negative half cycles. A feedback balance circuit is coupled between the AC load and the first and second power switches. The feedback balance circuit determines a DC current component in the AC load and generates a phase delay correction signal as a function of the DC current component. At least one of the first and second phase delays is adjusted independently of the other phase delay as a function of the phase delay correction signal to limit the DC current component.