Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Analysis of a SEPIC (calculating duty cycle with coupled inductors)

Status
Not open for further replies.

uoficowboy

Full Member level 3
Full Member level 3
Joined
Apr 4, 2009
Messages
169
Helped
6
Reputation
12
Reaction score
5
Trophy points
1,298
Location
Seattle, Wa, USA
Activity points
2,964
Hi - I have been working on researching and understanding SEPIC power supplies. I was able to calculate duty cycle (and everything else that was interesting to me) of a SEPIC (operating in continuous mode) when the inductors are not coupled. I made the assumption that the capacitors had a constant voltage, which I think should be good enough for a first order approximation. I solved for the duty cycle by looking at the change in current of each of the inductors while the switch is on, and then looking at the change in current in each inductor when the switch is off. The sum of the changes (ie IL1on + IL1off) should be zero - so that gave me two equations with two unknowns - DC and Vc (voltage of the series capacitor). Very solvable.

But I'm just not sure where to even start when you have coupled inductors. I believe the duty cycle stays the same but the ripple is halved, but I'd like to actually see the math that shows me why that is.

Any suggestions?

Thank you!
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top