1. NEWMAR 115 – 12 – 20AU Full-Wave Rectifier with Choke-Input Filter

2. Choke-Input Filter

3. DC Operation V dc + - V ’ dc + - V’ dc = V dc (R inductor ) / (R inductor + R load )

4. AC Operation (approximate) Normally, make X capacitor << R load

5. Approximate the Circuit VrVr V’ r - + - + V’ [rms] = (X capacitor / X inductor )(V r[rms] ) Usually, X inductor >> X capacitor

6. Full-Wave Rectifier Output Output frequency = twice the line frequency Second Harmonic (first ac component)

7. 2π(120)

8. “Critical” Inductance, L c 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

9. Minimum Inductance L c

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

11. Range of values for the Filter Choke NEWMAR 115 – 12 – 20AU Power Supply L max > R 1 /1000 = 5/1000 = 5mH  50mH L c >= R 1 /1000 = (12 V/20 A)/1000 = 0.6mH