Unwanted oscillations in flyback simulation (LTSpice)

Status
Not open for further replies.
L

LaMontagne

Newbie level 3
Joined
Apr 27, 2013
Messages
4
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,316
Hello,

I am currently working on a simulation for a bidirectional flyback circuit (output diode replaced by a NMOS). When I am using generic components, everything works fine. However when I use
manufacturer supplied spice models for the MOSFETs, I keep getting unwanted oscillations while the mutual inductor is charged (current ramping up).

I assume the oscillations come from the LC tank consisting of the transformer primary inductance and the MOSFET parasitic capacitance. Could this be a simulation problem? I attached the waveform of the transformer primary current showing the oscillations.

Thanks for any help!
 

In contrast to simulation artefacts, the oscillations look smooth and the waveforms plausible at first sight. You must know if the parameters of your simulation have been selected according to real-world circuit parameters. The oscillation during ton looks somehow strange, probably due to unusual or unrealistic circuit parameters. Viewing the LTSpice design could clarify things.
 

Thanks a lot for the response. Here is the circuit I am trying to simulate:


It seems that these oscillations are less of a problem if the on-time is higher. Can I expect to see similar oscillations in the real circuit? (I ask this as I would like to avoid using any RCD clamps etc. if possible)
 

Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…