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reverse diode voltage (full bridge forward converter)

R

reggie

Jan 1, 1970
0
Hi all,

I have found a formula that I would like to understand the derivation
of.

I am trying to work out the peak reverse voltage on a secondary side
full bridge forward converter rectifier diode. The secondary is centre
tapped with two diodes, top diode D1 and bottom diode D2, an output
choke and capacitor.

I understand the operation of the circuit and would assume the reverse
voltage is the primary voltage referred to the secondary during the
time that say D1 turns off. But I have found this formula that states

Vrrm >= [((Vout +Vf).Vinmax)/(duty max . Vinmax)] + leakage inductance
spike

Vrrm = diode repeat reverse voltage
Vout= dc output voltage of converter
Vf = it doesn’t state which diode voltage drop this is, maybe it’s the
other secondary diode (when d1=off d2=on)
Vinmax = max dc bus voltage = input voltage to converter

I have found a link that has the waveforms which I understand but not
how to work out the magnitude of the Vd1s reverse voltage. it’s the
waveform titled: These are typical waveforms in a full-bridge PWM
topology

http://www2.electronicproducts.com/Optimal_output_rectifier_selection-article-MAYINT1-MAY2002.aspx

Please can someone explain this formula or explain how they would work
out the Vrrm on a secondary rectifying diode for a full bridge forward
converter.

reggie
 
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