flyback converter current

[pol]

my flyback converter I input 3 ,2 A and I output 1 ,5 A,
what cause it???

i using flyback converter conduction continous mode..with f 20 khz..

please help??

 

[mister_rf]

Missing all important details about your flyback converter…

 

[BradtheRad]

1.

If it's a flyback type then you have a transformer in the output stage.

It must be a step-down transformer, right?

With a diode in series? That will create a fraction of a volt drop.

2.

A transformer only conveys AC to the secondary.

So when you say continuous conduction mode, do you mean the transformer primary receives AC with a continual DC component?

Then this is inefficient use of the transformer. Only the AC component will transfer any power.

------------

Edit: Reading an article I see there is such a thing as using continuous mode in a flyback converter. Unexpected.

I was going to mention that your transformer might be saturating, but I suppose you selected one which can handle the currents you are sending through it, at your stated frequency of 20 kHz.

 

[goldsmith]

Dear Pol
Hi
How much is your input voltage and of course out put voltage before your filter ?
Best Wishes
Goldsmith

 

[pol]

i have done the flyback converter,,
but i dont know how to make the current limiter, any one can help me???

please......

 

[goldsmith]

Hi pol
It is simple . but it depends on that what topology you have used for ? e.g current mode or voltage mode ? and also it depends on what driver IC you have used ? if you tell me more informations i can help you as well .
Best Wishes
Goldsmith

 

[FvM]

Post #2 still holds.

 

[pol]

i using the flyback topology,
i use ic sg3524,
now i use voltage mode....

help me please...

 

[goldsmith]

Hi pol
Well it has a pin that called i sense . if you read it's datasheet it gave you the manner for current limiting as well . but if you need variable current you will need an opamp and then a reference voltage that can be variable .
Good luck
Goldsmith

 

[pol]

how to make the current limiter depends on datasheet i'm confused,???

 

[goldsmith]

Hi pol
What i have told ? i have told that there is two pin that called isense . did you see that ? an important think is how to read a datasheet carefully . no problem ! see below , please :

Good luck
Goldsmith

- - - Updated - - -

Pol , of course there are many other manners available for this aim . but it depends on you ! for example if your IC had not any pin for current limiting do you know what you could do ? it is simple ! breaking the voltage feedback pin !!