Selecting the right core for a current transformer.!! :?:

[ThaineSasman]

achieving right ratio current transformers

Hi guys,

Im busy struggling a bit finding a comprehensive guide to selecting the correct core for a current transforer.

I have a 3 phase brushless dc motor I'm going to run at 6800rpm, thus making the frequency about 115Hz. The motor will pull approx 43A @ 11V which I need to transform to a smaller current using a current transformer, so that a voltage < 5V can be read across my load resister and then put into an A/D converter.

My problem is selecting a core/windings ratio for the transformer.
Ive read a couple of the other similar posts, but it hasn't helped me toward a more specific solution. Please could you help!?

Thanx!

 

[FvM]

selecting type of current transformer

An AC current transformer doesn't allow current measurement at low speeds down to standstill. A DC capable current sensor is the usual solution for current measurement in variable frequency drives.

 

[ThaineSasman]

selecting current transformer

How about something like this?

**broken link removed**

Operating current and frequency ranges are suitable I think?

 

[Tahmid]

selecting the right transformer

Hi ThaineSasman,
Search net and you will find lot of Application Notes and Books. You have to study al lot to understand that.
Thanks.