"Zero-loss core transformer"
Signification, Thu Nov 22 2018, 07:36AMHas anyone looked at the short youtube video entitled:
"New electrical transformer design with no core losses"
I think it was invented in the 80's in South Africa.
At about timestamp 1:16 wouldn't there be EDDY current losses as the flux passes through the conducting secondary shell?
Re: "Zero-loss core transformer"
Dr. Slack, Thu Nov 22 2018, 09:57AM
It's unfortunately based on a woolly misunderstanding of how transformers work. In 1:20 to 1:38, he offers an incorrect explanation of transformer action.
It eliminates core loss by eliminating the lossy core material.
There is no nominal eddy current loss (nominal meaning assuming perfect symmetry and zero thickness wires). In practice there will be tiny eddy current losses from assymetry, fields from the lead-in wires and suchlike, but not the gross eddy current losses caused by the conventional 'shorted turn' cross section of core material that's perpendicular to the flux (note the secondary tube cross section is not perpendicular tot he flux)
It's a low(ish) leakage inductance arrangement, though it's easy to see where the leakage is going to come from, the flux that circulates around the primary wires inside the secondary tube without passing through the secondary hole. The mutual coupling flux is that which threads the hole in the centre of the secondary circuit.
It's not necessary for transformers to have this arrangement to be 'good' in terms of core loss, regulation, or any measure of efficiency. It's not sufficient to use this arrangement either. As it's unneccesrry and insufficient, that explains why we aren't generally building transformers like this. The one exception is in very particular circumstances where the physical construction is useful and a single secondary turn is needed, RF baluns for instance.
Dr. Slack, Thu Nov 22 2018, 09:57AM
It's unfortunately based on a woolly misunderstanding of how transformers work. In 1:20 to 1:38, he offers an incorrect explanation of transformer action.
It eliminates core loss by eliminating the lossy core material.
There is no nominal eddy current loss (nominal meaning assuming perfect symmetry and zero thickness wires). In practice there will be tiny eddy current losses from assymetry, fields from the lead-in wires and suchlike, but not the gross eddy current losses caused by the conventional 'shorted turn' cross section of core material that's perpendicular to the flux (note the secondary tube cross section is not perpendicular tot he flux)
It's a low(ish) leakage inductance arrangement, though it's easy to see where the leakage is going to come from, the flux that circulates around the primary wires inside the secondary tube without passing through the secondary hole. The mutual coupling flux is that which threads the hole in the centre of the secondary circuit.
It's not necessary for transformers to have this arrangement to be 'good' in terms of core loss, regulation, or any measure of efficiency. It's not sufficient to use this arrangement either. As it's unneccesrry and insufficient, that explains why we aren't generally building transformers like this. The one exception is in very particular circumstances where the physical construction is useful and a single secondary turn is needed, RF baluns for instance.
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