On 22/12/05, microsoftwarecontrol <microsoftwarecontrol@yahoo.ca> wrote:
> I need to control the output V of flyback/froward
> switch power supply. But it seems very hard, due
> to that isolation transformer, which has fixed tune
> ratio.
>
> I test several switched power supply, after I
> decreased out put V, it shows very low loading
> capability.
>
> Any idea and success about this? Do switched power
> supplies only have fix output V?
>
>
Most definately not.
Usually the output voltage is controlled by changing the PWM ratio of
the drive to the output devices. Other control methods exist though,
such as changing the frequency or adjusting the phases to two
different drivers.

The turns ratio on the transformer is normally set by the control
requirements at either full load or no load - or maximum or minimum
input voltage.

RP
RP

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