> Did anyone find this interesting? I spent a while photocopying it in 
> the
> library, scanning it, converting it to PDF.. :-)

>> http://martin.klingensmith.info/ieee_cuk.pdf

Anything with Cuk's name on is liable to be interesting :-)

The great thing here is the Duty_Cycle^2 conversion ratio so that an 
eg 10:1 change in duty cycle gives 100:1 change in output voltage. He 
also has other conversion 'laws' and a "systematic synthesis 
procedure" which derives all applicable topologies.

The greatest disadvantage that I see in his basic N^2:1 design is the 
fully floating switch - but that's easy enough to handle and the end 
result is liable to be very useful. His basic circuit is essentially 
cascaded N:1 ratio buck converters with the topology rearranged to 
allow the single switch. Use of an isolating transformer allows, in a 
number of his topologies, a ground referenced switch. Others allow a 
ground referenced switch without isolation.

I've never yet had the need to employ a CUK converter. This will 
probably induce me to have a play. A current application I have has 
about a 20:1 conversion ratio requirement. An N^2:1 circuit would 
allow only a ~4:1 duty cycle change.



        Russell


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