Re[2]: [Discuss-gnuradio] DC-DC converter

[Cory Papenfuss]

> My  concern  would be how the inductors tend to smack the diodes. Once
> the  diode  gives  in  to  being  smacked around by the inductor, your
> 4702/4707  is  the  next  target.  If you pull/break the diode on many
> simple   charge  pump  circuits,  it  simply  stops  working.  If  you
> pull/break the diode on the inductive buck circuit, it tends to create
> what  ever  voltage  the inductor desires. The inductors are defiantly
> better  for  the  power output. The charge pump definitely can't touch
> the 3 amps.
>
> Best regards,
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Jared Harvey                        HAM KB1GTT

	You are both right and wrong.  A *properly designed* power 
electronic circuit does not abuse any device except as a second-order 
effect (requiring snubbers, limiting di/dt and dv/dt, etc).  If you do not 
design it correctly and have "shoot-through" faults (for a voltage-source 
converger, i.e. capacitor) or "open" faults (for a current-source, i.e. 
inductor) then you will destroy the devices.  A switched capacitor circuit 
abuses the devices as a *first-order* operating parameter (i.e. connecting 
capacitors directly across voltage sources/sinks means *huge* current 
spikes.)  A proper power electronics circuit simply passes the "baton" 
(voltage to inductors and current to capacitors) gracefully.

	For the buck circuit you mentioned it's true that if you remove 
the diode the switch will blow up.  That is the "open" fault to be avoided 
for the current-source converter.  If the circuit is properly designed, 
the diode won't fail.

-Cory

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* Cory Papenfuss                                                        *
* Electrical Engineering candidate Ph.D. graduate student               *
* Virginia Polytechnic Institute and State University                   *
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