Quite a simple question!
The 100Kw bit makes the problem interesting; like the thing probably will weigh 500 Kg and be oil cooled.
1000Hz is not high enough to help that much... is there any reason not to go to 100KHz?Actually I am doing the simulations for IBE Robots resistive welding machines at 1000 Hz frequency. The transformer design should be step down where the current should be more than 10KA at secondary side.. (Iron Powder Core, Amorphous core, Powerlite C core or nano crystaline core)..
I am trying to calculate the area and length of the core.. So can ant please help me with some example formulas ..
Thanking you in advance...
Mahesh,
Vlad is almost helpful, but his contribution highlights the need to establish B.
This is the saturation flux density of the core material.
I can do the design for you, but you will learn nothing.
So, the first thing you must do is to select a core material.
At 1000 Hz, this frequency is low enough that eddy current loss wont be too great if you select a silicon steel. For a transformer of this size, it is unlikely that a ceramic type material will be available. With ceramic material one has to have a very big mould. Its possible that large ceramic cores are made but are probably not readily available. With sheet steel, the core can be laminated to a very large size.
You need to examine manufacturers data for their transformer steels and you will be looking for the power loss versus flux density. It is probable that data will be available for 50/60 Hz and not 1000. You need to establish the factor for power loss increase versus frequency. This will be at least 1000/50 times greater than the 50 Hz value. When you have the material selected, then come back to me.
This sounds like somebody sitting in a room came up with the notion that all they have to do is crank up the frequency to get "more efficient" and save money and size on the transformer.Hi Dan,
At present in industries for the Resistive welding Transformers they were using mostly 50Hz and 400Hz transformers. Now they are increasing the frequency of the transformers. So, my task is to increasing the frequency from 1000Hz to 10KHz and checking for the efficiency.
Mostly and at present in an IBE Robot the welding machine efficiency is 44%
I think you should stick to transformer equation, rewritten this is what it says:
N*S=U/(4.44*f*B)
In your case:
N*S=565V/(4.44*1000Hz*1.7T)
https://www.scribd.com/doc/27073343/Transformer-Engineering
As for the first part of my previous post, it may be misleading and not useful in this case
but here is what I get.
Your power is not reactive, your load is resistive.
Average P=100kW so E=P/(2*f) for one semi-cycle.
1/(2*f) is time for one semi-cycle.
L=E/(I^2)
L=1.63 mH
Ok,
Mr al says the transformer equation is;
N=E x 10^8 /(4.4 x F x A x Bsat)
Bsat you say is at least 17000 gauss(1.7T). Frankly I think this is high because it might be for the material, but in a real core could be less. Nevertheless, you can play with these numbers. Now you need to play with the core cross section area (in cm 2) and N. You will need to determine the cross section area of the wire. What current density in the primary wire will you assume? For starters I usually take 2000 A /per square inch.
The loading on this transformer is likely to be hard to predict, and is likely to vary through the weld cycle The load is effectively a short circuit and the connecting cables will probably be a significant influence on the final performance. This is all about refining the design. You might want to develop an equivalent circuit using the 'perfect transformer' to get the final secondary turns.
Mahesh,
you've had a good bit of help and now YOU have to lay the egg. The consenus is that the crossection is at lest 10 square cm. You have information on 'C' cores. You have information on current density in the copper. You now have to put it together. Take the winding space and fill half of it with primary winding and half of it with secondary winding. Will you use one 'C' core and two coils or or 2 'C' cores and one winding. Make the winding space as big as you need to and if you have to increase the cross section of the core to make it all fit, then drop the number of turns on the primary a bit. Just keep on iterating till you get something close. That's how its done. Theory supports the practice.
Hope you get to your dead line but dont wait much longer; over to you and out from me.
Hi,
When i use E=565 and F=1000 and B=15600G and N=75 i get Area=10.9 square centimeters.
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