AC voltage controller with PWM control
AC voltage controller with PWM control is a power electronic circuit which can be used to control the electrical power from the AC source to an electrical load. As shown in Fig. 1, S1 and S2 perform as the switching devices controlled by the PWM pattern, and S1 and S2 perform as the free-wheeling devices.
The Pulse Width Modulation (PWM) control has higher efficiency than the phase control technique; however, the drawbacks of this control scheme are the high switching gloss and the complex control circuit. Normally, the PWM pattern is designed by the conventional fixed duration pulse technique, in which the width of pulse controls the output RMS voltage of the circuit. F ig. 2 shows an example of the output voltage waveform from the conventional technique. In this figure, the switching frequency of PWM is 1 kHz; the AC input voltage is 220 V, 50 Hz, and the numerical calculation of the RMS Voltage is 160.9 Vms.