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NEWMAR 115 – 12 – 20AU Full-Wave Rectifier with Choke-Input Filter. Choke-Input Filter. DC Operation. +. +. V dc. V ’ dc. -. -. V’ dc = V dc (R inductor ) / (R inductor + R load ). AC Operation (approximate). Normally, make X capacitor << R load. Approximate the Circuit. +.
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NEWMAR 115 – 12 – 20AUFull-Wave Rectifier with Choke-Input Filter ECE 442 Power Electronics
Choke-Input Filter ECE 442 Power Electronics
DC Operation + + Vdc V’dc - - V’dc = Vdc(Rinductor) / (Rinductor + Rload) ECE 442 Power Electronics
AC Operation (approximate) Normally, make Xcapacitor << Rload ECE 442 Power Electronics
Approximate the Circuit + + Vr V’r - - Usually, Xinductor >> Xcapacitor V’[rms] = (Xcapacitor / Xinductor)(Vr[rms]) ECE 442 Power Electronics
Full-Wave Rectifier OutputOutput frequency = twice the line frequency Second Harmonic (first ac component) ECE 442 Power Electronics
2π(120) ECE 442 Power Electronics
“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
Minimum Inductance Lc ECE 442 Power Electronics
“Bleeder” Resistor • The bleeder resistor provides 2 functions • keeps a minimum current flowing through the inductor • discharges the filter capacitor after turn-off • Rbleeder = R1 = the largest value of Rload • sets the maximum value of inductor L ECE 442 Power Electronics
Range of values for the Filter Choke • NEWMAR 115 – 12 – 20AU Power Supply • Lmax > R1/1000 = 5/1000 = 5mH 50mH • Lc >= R1/1000 = (12 V/20 A)/1000 = 0.6mH ECE 442 Power Electronics