inductive temperature controller

[taylosmith92]

New to this sort of thing but I want to make a temperature controller that takes an IR temperature sensor as the input and an inductive coil or air as the output to adjust/maintain the temperature. How would I do something like this? I have looked up circuits for temperature control, but I'm not sure how they can help me.

My understanding is that I need some sort of comparator to compare the temperature it is at, to the temperature I want it to be at. Also, how would I even set the temperature to begin with? This is obviously very rough and any help would be appreciated. Thanks!

 

[crutschow]

What type of IR temperature sensor?
How will an inductive coil adjust the temperature?

 

[taylosmith92]

The ir sensor I will need to look up. But the inductive coil heats up a small piece of copper. A better method would be to use a thermocouple welded to the surface of the copper to sense the temperature and then use the inductive coils to heat the copper or cool with air

 

[Tunelabguy]

Induction heating uses a radio frequency signal to induce currents or magnetic effects in the target metal. The magnetic hysteresis in magnetic metals like iron generate heat when exposed to such RF magnetic fields. And eddy currents in these materials also heat up the metal. The trouble is, none of this helps very much with copper. Copper is not magnetic, so it will not have magnetic hysteresis heating. And it has very low resistivity, so it will not generate much heat from eddy currents - no more so than the copper coils generating the RF field in the first place. So unless your induction coils are made of superconducting materials, your coils will get as hot as the target metal. You might as well just use straight conduction heating by touching the target metal with a hot conductor - just like a soldering iron. Induction heating is not well-suited to heating copper.

 

[taylosmith92]

The copper I am using is only 2 mils thick so there is not very much mass. Essentially, I am envisioning it is a copper sheet sandwiched on either side with induction coils that would then heat the copper in between the coils.

 

[Tunelabguy]

Are your induction coils water-cooled? What power level of RF will be driving these coils? Induction heaters typically use 1 to 30 kW. That is a huge radio frequency amplifier!

 

[crutschow]

Why not heat the copper with an IR lamp? Seems easier.

 

[jiripolivka]

Why not heat the copper with an IR lamp? Seems easier.

As an induction heater generates heat by eddy currents in any close metal object, it is difficult to shield any thermo-sensor from such heating if its circuit is made of conductors.
One possibility is to use a PIR or IR sensor which responds to target-body temperature over a distance. Some IR sensors can work through an optical fiber, so no induction would affect sensor response.

Commercial induction heaters for home/restaurant use utilize thermocouples attached to the heater surface , which generate DC voltage while the induction uses high frequency. The thermocouple circuit is filtered by a low-pass filter, to reject the induced voltage.