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Electronics => PCB/EDA/CAD => Topic started by: Circlotron on September 16, 2020, 04:14:10 am

Title: Simulating zig zag transformer produces DC output!
Post by: Circlotron on September 16, 2020, 04:14:10 am
Using Simetrix to try and simulate a zig zag transformer. If I simply wire it up as per normal I get huge circulating currents in two of the phases. If I put a 10 ohm resistor in the wires that go to ground, one of the wires has zero current and the other two have opposite polarity DC currents, or so the simulator says. I've spent several hours on this and I can't get it right. Any ideas?
What a zig zag tranny is -> https://www.mathworks.com/help/physmod/sps/powersys/ref/groundingtransformer.html (https://www.mathworks.com/help/physmod/sps/powersys/ref/groundingtransformer.html)
Title: Re: Simulating zig zag transformer produces DC output!
Post by: T3sl4co1l on September 16, 2020, 05:00:40 am
Try setting the sources initially to zero?

Tim
Title: Re: Simulating zig zag transformer produces DC output!
Post by: Circlotron on September 16, 2020, 07:02:32 am
Try setting the sources initially to zero?

Tim
Yep, that was it. Phase A was starting at the zero crossing but the other naturally were not. Now B starts 6.66mS after A, and C a further 6.66mS. i had to put 1mR current limiting resistors in series with the sources otherwise the simulator got upset. Now it seems to work. Now to try it out with that three phase rectifier ripple cancelling idea! Thanks Tim.  :-+ :-+ :-+