NEWMAR 115 12 20 AU FullWave Rectifier with

NEWMAR 115 – 12 – 20 AU Full-Wave Rectifier with Choke-Input Filter ECE 442 Power Electronics 1

Choke-Input Filter ECE 442 Power Electronics 2

DC Operation + + Vdc V’dc - - V’dc = Vdc(Rinductor) / (Rinductor + Rload) ECE 442 Power Electronics 3

AC Operation (approximate) Normally, make Xcapacitor << Rload ECE 442 Power Electronics 4

Approximate the Circuit + + Vr V’r - Usually, Xinductor >> Xcapacitor V’[rms] = (Xcapacitor / Xinductor)(Vr[rms]) ECE 442 Power Electronics 5

Full-Wave Rectifier Output frequency = twice the line frequency Second Harmonic (first ac component) ECE 442 Power Electronics 6

2π(120) ECE 442 Power Electronics 7

“Critical” Inductance, Lc Must keep the load current flowing for the complete cycle of the input voltage The dc load current must be > the peak value of the ac component of the load current ECE 442 Power Electronics 8

Minimum Inductance Lc ECE 442 Power Electronics 9

“Bleeder” Resistor • The bleeder resistor provides 2 functions – keeps a minimum current flowing through the inductor – discharges the filter capacitor after turn-off • Rbleeder = R 1 = the largest value of Rload – sets the maximum value of inductor L ECE 442 Power Electronics 10

Range of values for the Filter Choke • NEWMAR 115 – 12 – 20 AU Power Supply • Lmax > R 1/1000 = 5 m. H 50 m. H • Lc >= R 1/1000 = (12 V/20 A)/1000 = 0. 6 m. H ECE 442 Power Electronics 11