How to control the Power with high accuracy from a resistor

[Vauxdvihl]

Hi friends,

i have got the following curve from a resistor depending up the temperature. The resistor is only used for heating.
The red line is the normal curve and the blue dotted line is the interpolated characteristic.

On the x axis you can see the temperature and on the y axis you can see the resistor varying with the temperature.

As you can see the resistor value varied in a range from 656mOhms@-40°C to 877mOhms@600°C.
We need to control the temperature from the resistance.
The min. voltage is 8,6V, regarding to that we have currents in the range of 9,5A to 13,5A.
We are not able to measure the temperature directly, so we are forced to control either the power or only the voltage or currents.

Has anybody designed a control circuit to control the resistance with such a small resistance range.
What about the accuracy of the ACS750LCA-050 ?
Somebody experience with that part ?

Thank you very much

Regards

 

[lll]

I think you can sense the current through the varying resistor. If you have enough money, you can use LEM. Once voltage and current all know, you know the resistance, then the temperature. I think you can use a MCU (cpu like 8051) with a curve table to solve the problem.

 

[Vauxdvihl]

Re: How to control the Power with high accuracy from a resis

We have not enough money and we have not enough space on a pcb fpr a Lem sensor...... :roll: