Digitally controlled multiple-pulse-width-modulated AC chopper for power control.

Multiple pulse width modulated (MPWM) AC choppers are gaining popularity over phase controlled circuits mainly due to the minimization of harmonics and the improvement in the input power factor. In this paper a direct digitally controlled MPWM AC Chopper using power transistors is described. A 120° chopping period is used for the main transistors in the three-phase power circuit to allow the circuit to accommodate loads of any power factor angle. Single-phase sensing is used to generate all control signals necessary for three-phase power control. The experimental results obtained with a three-phase prototype circuit are presented. The circuit described is expected to find extensive use in microprocessor based MPWM AC power controllers and AC line regulators. [ABSTRACT FROM AUTHOR]