Transformer output as a constant current or voltage source

Thread Starter

abdulbadii

Joined Aug 30, 2017
85
Is transformer output a real voltage constant source (not current), as seen a circuit next to it apply current divider behavior having no the first resistor except usual rectifying diode in parallel to its RC snubber ?
 
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Papabravo

Joined Feb 24, 2006
21,159
I don't think so. A constant voltage source will supply any amount of current into a load. I don't think a transformer can do that.

ETA: The ability of a transformer to "look like" a constant voltage source depends on the relationship between the load impedance and the voltage source impedance on the primary side as the following simulation demonstrates.

1676381871060.png

For load impedances of 1Ω and larger the output does look like a constant voltage source. The traces for 1, 10 and 100 are all overlapped. Change the source impedance of V1 and there will be a different load impedance above which the secondary looks like a constant voltage source.

Since transformers are modeled as coupled inductors there will also be frequency effects.
 
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RPLaJeunesse

Joined Jul 29, 2018
252
In addition to the source supply impedance each transformer winding has inherent resistance and leakage inductance, considered as series elements in the circuit. Those also affect what voltage is seen at the output terminals as the load current changes (due to the resistance) and frequency changes (due to the inductance).
 

Ian0

Joined Aug 7, 2020
9,677
It depends on what is supplying the transformer. The output reflects what is going on at the input (with the addition of all the parasitic components)
 

crutschow

Joined Mar 14, 2008
34,285
For an ideal transformer, the output reflects the input source.
So the output will be constant current for a constant-current source, and a constant voltage for a constant-voltage source.
 
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