Programming instructions

Transformer

 National Instruments Corporation 2-29 Multisim Component Reference Guide

Within the Bmain expression, the segment Lo*(1-0.1/(Idc^2)*i(v1)^2)* v_di_dt is exactly the

inductor equation we desire:

The if-statement switches between the non-linear inductor model and the constant linear

inductor model when the inductance falls to 10% of nominal value (or current has reached

3*Idc).

References

[1] Martin O’Hara, “Modeling Non-Ideal Inductors in SPICE, Martin O’Hara,” EETimes

Asia, April 2002

2.10 Transformer

The transformer is one of the most common and useful applications of inductance. It can step

up or step down an input primary voltage (V1) to a secondary voltage (V2). The relationship

is given by V1/V2 = n, where n is the ratio of the primary turns to the secondary turns. The

parameter n can be adjusted by editing the transformer's model.

To properly simulate the transformer, both sides must have a common reference point, which

may be ground. The transformer can also be used in a center-tapped configuration. A

center-tap is provided which may be used for this purpose. The voltage across the tap is half

of the total secondary voltage.

This transformer is suitable for getting quick results. To simulate realistic devices that include

a transformer, you should use the nonlinear transformer.

Note Both sides of a transformer must be grounded.

2.10.1 Characteristic Equation

The characteristic equation of an ideal transformer is given by:

VnV

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