Help in Boost rectifier's simulation

[AbhimanyuSingh]

What is the supposed output of the first circuit I have attached here in this post? Isnt it a DC? But when I simulated the same circuit, I got a half rectified AC voltage at the output> My simulated circuits's image is also attached. Why is it so?

 

[AbhimanyuSingh]

i missed the attachments.

 

[mtwieg]

The time constant of your load resistance and output capacitance is too low. It should be much greater than the period of your line frequency (like at least 20ms). Also with no feedback you won't get any decent regulation, so it may not look good anyways.

 

[RCinFLA]

A circuit like that is used for power factor correction front end for a DC power supply.

The switching duty cycle is adjusted to fit the line frequency full wave rectified waveform so the input charging current on the cap is also full wave rectified current shaped yielding a good power factor. The average of the full wave charging current must equal the average DC current taken off the capacitor.

Since the input current is line freq at full wave rectification, the output cap value must be large enough to remove most of the ripple voltage. It needs a feedback control circuit to make the switching control adjustments. There are two or three inputs to the control logic. A sample of the full wave rectifier output provides the stencil for the switcher to do the good sinewave shaped capacitor charge. The output voltage is used to adjust the gain of the switcher cycling. The third sense is an output current feedback that may also feed into gain control or just provide current limit detections.