Invertor Variable frequency drive of power transformers
« on: December 30, 2018, 01:35:19 PM »
This is something I touched on in another post , Id like to seek out more opinions on it .

I want to try a single phase VFD to to provide a variable voltage and frequency input to a mains transformer , that way I could tune both voltage and frequency , reduce core loss in the transformer,reduce magnetic radiation from it  ,and make PSU filtering much more effective at say 400hzx2   . Comercial motor drives are coming in cheap from China  ,typically .5kw is the smallest . Extra filtering between VFD and transformer might be a good plan , would a standard mains filter like used in modern switchers be appropriate here?

I might try the idea out at work next week , I could have the VFD and logging multimeter attached to the transformer then sweep the frequency under load and measure the resulting ripple after a bridge and cap . Would a current clamp meter in close proximity to the transformer give an indication of how much magnetic leakage  was being radiated ?


Re: Invertor Variable frequency drive of power transformers
« Reply #1 on: January 01, 2019, 02:58:01 AM »
most of the VFD's i have seen put out hideous noise, might have even blown up a scope with one of those,

the big ones have been known to interfere with air traffic frequencies by radiating noise back along the power grid,
If I can't fix it, I can fix it so nobody else can!
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Re: Invertor Variable frequency drive of power transformers
« Reply #2 on: January 01, 2019, 04:24:12 PM »
Hmmm yes now you mention it we have a huge 100kw VFD in work for testing motors , when the thing is switched on theres an audible high pitched drone sound fills the whole building , most likely a motor doesnt care about noise on the line at all so probably no need for a sine wave on the output of these things , I might still try an experiment on a small scale just to see what happens , might just end up trading 60hz magnetic noise for tons of hash instead , nothing ventured nothing gained though . I'll certain be very carefull about my test equipment while Im at it .

Many thanks once again CJ , best wishes to you in 2019


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