Transformer Transient Analysis

Thread Starter

BlackMelon

Joined Mar 19, 2015
126
Dear All,

I am studying transformers in power supply (AC-DC converter). On the first picture, there is one transformer having 3 windings: the primary (1) that takes high voltage input and driven by MOSFET, the secondary (2) that gives low voltage output which will be rectified and become the supply output, the auxiliary (3) that supplies low voltages to control IC.

If I separate the auxiliary winding into the 2nd transformer (2nd picture). Would the start up time measured from when we apply the AC input and when the aux. voltage becomes stable be faster than the 1st picture?
I would appreciate if you provide me names of references I can read further.

Sincerely,
BlackMelon
 

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Ian0

Joined Aug 7, 2020
3,785
You appear to have DC across the transformer in the second picture - so it won't work at all.
Did you mean to put the two transformer primaries in parallel? If so - it might do, but it depends on the output capacitors.
 

Thread Starter

BlackMelon

Joined Mar 19, 2015
126
A MOSFET, as shown, cannot control an AC voltage.
The intrinsic source-drain diode will conduct on every half-cycle.
Sorry for the wrong schematic. I will bring a complete one

You appear to have DC across the transformer in the second picture - so it won't work at all.
Did you mean to put the two transformer primaries in parallel? If so - it might do, but it depends on the output capacitors.
This is very helpful. I have never tried or seen this technique before. Thank you
 
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