Asymmetrical PWM technique for AC choppers

An asymmetrical pulse-width modulated (APWM) control technique for an AC chopper which can improve the input power factor and suppress the harmonic contents of currents at both its input and its load sides is proposed. The ideal switching function for the proposed technique is derived and converted into the APWM pattern for practical implementation of an AC voltage regulator. By digital simulation several characteristics are investigated theoretically and then compared with those of the phase angle control and conventional PWM technique. The experimental results show good agreement with calculated ones, indicating the feasibility of the proposed technique