DOI: 10.36347/sjet.2020.v08i09.001

Pages: 168-174

Power factor correction is a way of counteracting the undesirable effects of electric load that create power factor less than unity. The word “converter” in wider perspectives include all the devices that convert electrical energy from one form to another, e.g. inverters, rectifiers or power pack. The term can also denote frequency converter and/or circuit that beat signals together to form a new signal frequency. Pulse Width Modulation (P.W.M) is a method of varying the mark-to-space ratio of the output voltage waveform during a cycle so as to minimize the magnitude of harmonics in the output. Modulation may be done by using transistors as switches instead of thyristors because transistors have much higher switching frequencies, thus, leading to improve and more efficient operation of the thyristors with switching time of about 1 to 2 seconds. In this paper, a single-phase and three-phase bridge rectifier circuits’ power factors were modeled and simulated in MATLAB. The resulting voltage wave forms displayed in Figures 4 and 5 respectively showed that P.W.M method is a premier compared with other methods and is also better at low output voltage demand. Again, by using several pulses in each half cycle of the output voltage, it can reduce harmonic contents at low output voltages. In P.W.M, control is made independent of alpha (), the firing angle of thyristor, and as such all the switching loss problems and electromagnetic interference (EMI) noise associated with switches/switching are totally eliminated here.