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any pspice expert out there?

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New Member
Hi guys,

im trying to simulate a dc fullbridge converter for my project..

my question is....how do a person choose the right diode for the mosfet use in an inverter so it can generate a nice squarewave at the output...like the ones below..

diagram1 -->>>Yfrog - u1u.jpg &
Yfrog - 6j1.jpg -->>> waveform1

but once i swap it with a higher rating diode....it has this transient at my output and no matter voltage i pump thru the gate..its the same..

diagram2 -->>>Yfrog - 9zxt.jpg &
Yfrog - diagram2graph -->> waveform2

the mosfet that im using is buz45b....with a switching frequency of 10khz.

any advise out there ? thanks :D


New Member
hello again...help anyone ? ehehhe...its ok, i managed to solve the problem..
just a quick reply for anyone who has the same problem...

The spikes are due to the inductor in the circuit....real world "inductors" have voltage limitations...due to eddy current lost etc..but unfortunatetly, pspice/orcad inductors doest..hence will result unrealistic spikes in mosfet switching..

To solve this....the inductor should be connected with a parallel resistor...just play around with the values...to get less spikes...but the drawbacks....hmm..i cant measure the actuall current across my inductor.

I have a new problem with pspice again....while playing with the simulations..i suddenly generated crazy like waveforms...even i have removed the dc source..inductors ...capacitors etc....i still get waveforms in the output....is this a bug in spice ?


Well-Known Member
Most Helpful Member
Spice can give odd results if you don't have the circuit connected properly or have some odd circuit connection. Make sure the circuit is all connected correctly.
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