Re: [SI-LIST] : Flyback Transformer Model

Michael T Zhang (Michael_T_Zhang@ccm.jf.intel.com)
Mon, 15 Dec 97 07:40:00 PST

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Derek,

I've used the following two ways to model a transformer in SMPS.

(1) Dependent sources:
V2=V1/n; I1=I2/n; where n is the turns-ratio, 1 and 2 are denoting the
primary- and secondary-side correspondingly.

(2) Coupled inductor:
L1=***uH; L2=***uH; M=0.999; where L1 and L2 are magnetizing inductance of
the transformer seen from the primary and secondary sides (they should be
in proportion to the square of the primary and secondary turns), and M is
the mutual coupling.

The transformer in a flyback converter behaves more like a coupled inductor
than a transformer. Method #2 should work better.

-Michael Z

Phone: (503)264-2301
Fax: (503)264-6053
Michael_T_Zhang@ccm.jf.intel.com
Intel Corporation, Platform Architecture Lab

______________________________ Reply Separator _________________________________
Subject: [SI-LIST] : Flyback Transformer Model
Author: owner-si-list@silab.Eng.Sun.COM at SMTPGATE
Date: 12/12/97 5:54 PM

Hi Chaps,

I'm in the process of modelling a switched mode power supply, and I'm having
difficulty visualising how my transformer will look in SPICE.

The transformer has a single primary winding, with 5 secondaries. Any
suggestions anyone?

Seasons greetings,

Derek Walton.
Owner L F Research EMC Design and Test Facility

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Subject: [SI-LIST] : Flyback Transformer Model
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