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Forum Index : Electronics : Baby 72v off grid system

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wiseguy

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Joined: 21/06/2018
Location: Australia
Posts: 1206
Posted: 03:10am 12 Jun 2021
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  oreo said  
  Wiseguy said  
When I was bench testing my inverters on the bench and powering them from a mains input power supply, I had a similar varying of the inverter output voltage.
It turned out that it was due to the fact the inverter operating frequency was slowly drifting compared to the mains frequency and my power supply had a very small amount of ripple under load. As the two frequencies drifted relative to each other there was a few volts variance at the inverter output, between when the peaks lined up and when they drifted away. It lead to a very slowly changing output voltage that for a while I was convinced it was an inverter problem - which in my case it wasn't.


Interesting inverter ripple problem.  You must have a pretty strong power supply, to power your inverter.  And yes I am using a cheap and nasty AC watt meter, so I am having problems with reported power not being correct.


I missed this line in your original reply - I have 3 Elteks in parallel giving a total of ~ 6kW - briefly before the breaker trips.  Prior to that I used a 0-20V 40A variable supply and a different toroid to suit the lower voltage - this gave a worse ripple result compared to the Elteks.
Edited 2021-06-12 13:20 by wiseguy
If at first you dont succeed, I suggest you avoid sky diving....
Cheers Mike
 
Warpspeed
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Joined: 09/08/2007
Location: Australia
Posts: 4406
Posted: 03:21am 12 Jun 2021
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One way around the frequency beating problem would be to phase lock your inverter to the grid frequency.

My own off grid dc inverter supply is three phase, so I get none of those problems.
Cheers,  Tony.
 
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