Abstract: A method and apparatus for controlling the supply of three-phase power by calculating phase trigger firing delays for all six zero-crossing points based on the measurement of one zero-crossing point of one phase. The method includes the steps of (a) measuring the zero-crossing point of a single phase, (b) calculating the timing of phase triggers for all phases based on this measurement, and (c) firing the phase triggers based on the calculated sequence timing. In one embodiment, the invention provides power factor correction to the system by measuring power factor to determine whether it is within predetermined limits and introducing a delay into the timing of the phase triggers if it is not. In another embodiment, the invention balances the voltage of the three separate phases by introducing a delay based on comparisons between each of the separate phases.

Abstract: A method and apparatus for controlling the supply of three-phase power by calculating phase trigger firing delays for all six zero-crossing points based on the measurement of one zero-crossing point of one phase. The method includes the steps of (a) measuring the zero-crossing point of a single phase, (b) calculating the timing of phase triggers for all phases based on this measurement, and (c) firing the phase triggers based on the calculated sequence timing. In one embodiment, the invention provides power factor correction to the system by measuring power factor to determine whether it is within predetermined limits and introducing a delay into the timing of the phase triggers if it is not. In another embodiment, the invention balances the voltage of the three separate phases by introducing a delay based on comparisons between each of the separate phases.