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langwenfei1-Visitor
1-Visitor
August 11, 2010
Question

help me about uint problem

  • August 11, 2010
  • 2 replies
  • 3713 views

when design a transformer of switch power supply.I can`t solve the promble of KG. The KG`s unit is cm^4,but can`t get this result .other proble is KE`s unit ,it should be none .

I need help .

2 replies

M
MikeArmstrong1-Visitor
1-Visitor
August 11, 2010

A few points first.

  • Modify your post as its nearly impossible to read.
  • Post worksheet in Mathcad 11 format for a wider audience.
  • Not sure what language or text style you are using but I can't read it.

Mike

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RichardJ19-Tanzanite
19-Tanzanite
August 11, 2010
Not sure what language or text style you are using but I can't read it.

Chinese. In my case most of it is in a font I don't have, so it appears as squares. If you copy and paste it into Google translate then it will show the Chinese characters, and will give you a translation (not always a very good one, but often good enough to get the idea of what is being said).

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RichardJ19-Tanzanite
19-Tanzanite
August 11, 2010

Firstly, you are redefining Mathcad units as variables (N, A, ton, W). That's why the variable names have little squiggly lines under them in the definitions: it's a warning. Don't do that and expect units to then work correctly. Use different variable names. It's not the source of the problem, but if you do that then one day it will be.

It looks like the equation for Ke is an empirical equation. That means the values of Po and Bm should be unitless, but should be correct numerical values for the units expected for the empirical equation. So you should divide Bm and Po in the expression by the units expected for the empirical equation (which may not be the same as the units you used to define the variables!)

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