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And I think you are wrong.
Correction. I know you are wrong. No one suggested ttransformer wasn't "bog standard"; its the signal driving it that is different to your expectations.
Seems my suspicions were correct -- or at least, not completely wrong.
I found this description of high voltage audio systems; I bolded the salient part:
In essence, the audio transformers see a low current, essentially steady DC voltage with a ripple.
Where an AC transformer core sees the...
I suspect that audio transformers 'get away with it', because unlike an AC supply voltage, the signal they carry is not a pure sine wave; but I do not know enough on the subject to justify that suspicion.
But I will find out.
What a wonderfully polite way of telling me I am wrong :)
The "theory" being quoted are numbers that come out of FEMM written by David Meeker, which has been the go to 2D magnetostatic simulation software for the research community since 1998.
It's numbers are proveably reliable. My...
Perhaps the lesson here is: that if you try to use a core designed for 50Hz, at 400Hz, it is bigger than required, so has more core material in which to induce eddy currents; so greater losses.
The figures quoted are core losses only.
There's more data available from the simulation -- and much more can be derived with some more simulation time and some complex math -- but it is of little relevance, given the core used for this quick example bears no relation to the real one.
50Hz...
Changing the turns ratio and coil currents of my (preexisting) model to match that -- 4:1 turns ratio (800/200); with 1.45A in the primary and 5A in the secondary, the total losses calculated are:
50Hz -> 0.3W
400Hz -> 19.3W
This is a 37 x 45 x 11 x 4 x 0.18 lamiinated steel e-core, with...
To get closer still, add a second fudge factor by subtracting 40 from the previous result and rounding to the nearest 10:
sub x{
my $n = shift;
$n += 37;
$n >>= 1;
$n -= 256;
$n *= 11;
$n -= 40
int( $n/10 ) * 10;
}
Gives:
37 => -2440
38 => -2440
39 => -2430
40...
If you feed my method 237, you get -2380.
If you feed it 937, you get 2120.
If you want to get closer to your spec, add 37 to the input and multiply by 11 instead of 10.
Ie:
sub x{
my $n = shift;
$n += 37;
$n >>= 1;
$n -= 256;
$n *= 11;
return $n
}
Which gives...
A given transformer, at a given current, will have 50x greater total losses (hysterysis, proximity, eddy current and resistive combined) at 400Hz than it does at 50Hz.
Whether this is important depends upon what ratio, power and frequency the transformer was designed for.
eg. This overly...
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