Control for a 3kW Thermal Resistance

[Chandus]

Hi, guys, I just find this page, and is an amazing one.  ;D

I've got a problem with this kind of circuit, I'm thinking a dimmer could solve the problem, just one thing, I need to control the power from 0-100% with one voltage input of 6.67V max, so I want to know your opinion, if you think that a dimmer of 15A would work fine or some other circuit, I thought also of a saw tooth signal with a reference of 6.67V max controlling a Triac based circuit :-\. If you can aid me with circuits diagrams I would be pleased, thanks.  :)

[Chandus]

I didn't give full details, the main supply voltage comes from a 220V line, and the resistance is of 16.1Ohms with a current of 13.6A.

[prateeksikka]

hi chandus!
welcome!!!
why are u not using a variac for your mains supply?
If that is not acceptable u can use a pot in series with your resistor.
But i am unable to understand one thing.where are u getting 6.6 V with 220V
input?
However i guess u dont need a triac or SCR for such a simple application.
:D
prateek

[Chandus]

Thanks! I've got my welcome when I saw some really good topics around.........
About the 6.6V, well, they are outputs of a National Instruments tool, FieldPoint, which you can vary from LabView from 0 to 6.67V, and that's why I want a mechanism to control with 0V-0W and 6.67V-3kW or something near to those values. I'm a newbie in power electronics, so I don't know if a variac could solve my problem, thank u for your answer.  ;D

[Chandus]

I'm thinking in something like the block diagram in the image, but I have issues about the way the PWM is going to use the phase obtained by the transformer, how do I take the phase into consideration in an op-amp circuit? There's also the consideration of the Vref coming from the FieldPoint and the circuit tolerance to the high current of 13.7A. Please add any comments.

Triac_con_control_de_fase.rar