Off-Line Flyback with 2 secondaries question

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edaenrico

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Hi,

I got an off-line flyback converter with 2 secondaries.

Primary - 230 VAC
Secondary 1 - 24 VDC - 1 A
Secondary 2 - 9 VDC - 0.5 A

Let's say we know Np/Ns1 and Np/Ns2

How can I calculate the Flyback (reflected) voltage at the primary winding?

Best Regards,
Enrico Migliore
 

Hi,

I got an off-line flyback converter with 2 secondaries.

Primary - 230 VAC
Secondary 1 - 24 VDC - 1 A
Secondary 2 - 9 VDC - 0.5 A

Let's say we know Np/Ns1 and Np/Ns2

How can I calculate the Flyback (reflected) voltage at the primary winding?
Click to expand...

Hi Enrico
Are you familiar with transformers ? and relations between them ? the same with some approximations is applied here in this case !
Best Wishes
Goldsmith
 

Hi Goldsmith,

I'm familiar with single output flyback converter.

I don't know how to calculate the reflected voltage in case of 2 outputs.

Enrico Migliore
 

Hi Enrico
I'm familiar with single output flyback converter.
the reflected voltage in case of 2 outputs.
Click to expand...
What do you mean by that ? i think you've missed the idea !
Well , you should analyze each secondary one by one ! for example consider you have three secondary and one primary . first consider you have 1st secondary with the primary and then consider you have 2nd secondary with he primary and then consider you have third secondary with the primary . that's all ! and then if all of the secondaries should be under the load in the same time use a simple supper position analysis .

Best Wishes
Goldsmith
 

The "reflected voltage" concept only works for ideal flyback transformers (zero leakage inductance). For these, multiple output voltages are always tracking according to the windings ratio, independent of load currents. Thus there's no difference to the single secondary case.
 

Hi Enrico ,
Please send the transformer drawing,

I will tell you the reflected voltage.
 

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