Phase controlled rectifiers

Analiziranjem mosnog diodnog spoja zaključuje se da sklop ispravlja punovalno ispravlja ulazni signal a rezultirani signal je dvostruko manjeg perioda od ulaznog signala i dvostruko veće frekvencije. Kod mosnog spoja sa samim omskim otporom dobiva se ispravljeni izlazni signal međutim takav oblik izlaznog signala je nepoželjan. Ako se želi postići sklop sa boljim faktorom snage potrebno je paraleleno sa omskim trošilom spojiti kondenzator koji će izgladiti signal i povećati faktor snage. Fazno upravljivi sklopovi izlaznim signalom upravljaju pomoćnim strujnim impulsom koji se dovodi na vrata SCR-a. Ovisno o kutu α strujnog impulsa na izlazu se dobivaju različiti naponski oblici. Teoretska analiza pokazuje da se za kut α = 0 na izlazu dobiva maksimalna srednja vrijednost napona. Važno je naglasiti da u strujne krugove koji uključuju induktivna trošila treba dodati filtere signala kako bi se eliminirala neizbježna pojava viših harmonika.Results of bridge diode rectifier analisys show that the effects of single phase full wave rectification on the output voltage are as follows: output voltage has its frequency doubled and period halved compared to input voltage. Different circuit loads yield different output voltages, while bridge rectifier with R load offers DC signal its waveform is far from useful in real life applications. Reason behind this is low power factor value which results with high energy losses in the circuit. Solution for this problem is addition of filter capacitors that smooth out the output signal and increase value of power factor. Phase controlled rectifiers are the next improvement from the diode bridge rectifier because the use of SCR allows control of the output signal. Output signal varies depending on the value of the delay angle α. Maximum value of average output signal is achieved when α=0°. Lastly, it is important to emphasize the effect that inductive loads have on rectifier circuits. Inductive loads generate harmonics both in supply system as well as in load circuits so adding filters is inevitable