# Forward Converter: core reset question.

Discussion in 'General Electronics Chat' started by BlackMelon, Apr 30, 2016.

1. ### BlackMelon Thread Starter Member

Mar 19, 2015
33
0
Hello guys,

As far as I know, according to the B-H curve, the way to clear magnetizing fluxes is to reduce a magnetic field strength until it reaches a "coercive force", a negative magnetic field strength in case that B is positive before and vice versa. From H=NI, at some point, we will need the current to reverse its direction to clear the fluxes.

According to this link http://www.eetimes.com/document.asp?doc_id=1273232, fig 3a and 3b shows that the two-switch forward converter's current flows only one direction. Is it right that the primary winding of the forward converter "walks" along the green path as I made in the attached picture? Since the green path clears magnetizing fluxes only once (positive coercive), will this bring any downsides to the converter compared to the full bridge converter? Will sharp falling of the fluxes be dangerous?

Thank you
BlackMelon

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May 23, 2013
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3. ### BlackMelon Thread Starter Member

Mar 19, 2015
33
0
Ok, if the path I made is correct, there were 2-3 following questions. I also want to know its downsides due to the path. Walking just on the half-right plane vs. walking all along the curve. I mean walking only on the half right plane can still reset the B to zero, as walking all along the curve. So how is it advantageous or disadvantageous?

4. ### BlackMelon Thread Starter Member

Mar 19, 2015
33
0
I mean, if the green path is correct, when the primary winding current is zero, the forward converter clears the residual fluxes by reversing its direction first ,and later, increasing a primary's current til H reaches the positive coercive (so positive coercive force +Hc only that clear the fluxes). But I want to compared this method to the full bridge's, which walks completely along the B-H curve, providing clearing at both +Hc and -Hc. I want to know pros and cons of both methods.