Switchmode sinking current

[Charl]

Hello folks,

I am building my own smps (forward converter), and so far it seems to
be working out (as in, I didn't blow anything up yet). However, I
would like this PSU to be able to sink current as well as source it.
Is the topology I'm using okay for that and do I just have to
full-wave rectify the secondary or do I have to use a whole different
principle of operation?

Thanks for any help.
Regards,
- Charl

 

[Terry Given]

"Charl" <charl@home.nl> wrote in message
news:567d7ec3.0405170047.45fa8a8c@posting.google.com...

Hello folks,

I am building my own smps (forward converter), and so far it seems to
be working out (as in, I didn't blow anything up yet). However, I
would like this PSU to be able to sink current as well as source it.
Is the topology I'm using okay for that and do I just have to
full-wave rectify the secondary or do I have to use a whole different
principle of operation?

Thanks for any help.
Regards,
- Charl

If you have a synchronous rectifier then in theory your converter can be
bidirectional - it looks like a buck converter when driving the load, and a
boost converter when the load drives the supply (ie it "sinks" current).
With a free-wheeling diode, it cannot sink current - trace out the current
path, there is nowhere for it go go except the output cap, until that
charges above the input supply, at which point the buck switch diode (assume
its a FET) will conduct.

Terry