Power inductors with temperature sensor

[acd]

We are currently designing a compact, medium power buck converter and we would like to measure the temperature in the various components.
The power stage includes temperature sensors, but for the inductors (around 40A,
560nH) we did not find any with a temperature sensor.
I would have thought that it should be easy to integrate a wire-based temp sensor.
Since we use mostly closed-core inductors and the wire in the inductor is what gets hot, adding a temperature sensor to an existing product does not really make sense.

Andreas

 

[Frank Miles]

We are currently designing a compact, medium power buck converter and we
would like to measure the temperature in the various components. The
power stage includes temperature sensors, but for the inductors (around
40A, 560nH) we did not find any with a temperature sensor. I would have
thought that it should be easy to integrate a wire-based temp sensor.
Since we use mostly closed-core inductors and the wire in the inductor
is what gets hot, adding a temperature sensor to an existing product
does not really make sense.

Andreas

I've epoxied thermocouples to various devices as part of product testing.
This is for development/testing, not production, right?

 

[Frank Miles]

We are currently designing a compact, medium power buck converter and we
would like to measure the temperature in the various components. The
power stage includes temperature sensors, but for the inductors (around
40A, 560nH) we did not find any with a temperature sensor. I would have
thought that it should be easy to integrate a wire-based temp sensor.
Since we use mostly closed-core inductors and the wire in the inductor
is what gets hot, adding a temperature sensor to an existing product
does not really make sense.

Andreas

I've epoxied thermocouples to various devices as part of product testing.
This is for development/testing, not production, right?

 

[acd]

Am Donnerstag, 24. Januar 2013 17:02:19 UTC+1 schrieb cassiope:

I've epoxied thermocouples to various devices as part of product testing.

This is for development/testing, not production, right?

Yes, it is a research project.
The problem is that I think the temperature of the coil will be much higher than that of the core, and we use closed-core inductors.
How could I get a thermocouple inside the inductor?
Of course, your solution is better than nothing, and we will probably do that.

Andreas

 

[[email protected]]

Am Donnerstag, 24. Januar 2013 17:02:19 UTC+1 schrieb cassiope:












Yes, it is a research project.
The problem is that I think the temperature of the coil will be much higher than that of the core, and we use closed-core inductors.
How could I get a thermocouple inside the inductor?
Of course, your solution is better than nothing, and we will probably do that.

Andreas

I'd think the core and the coil would quickly reach the same
temperature
can't be much thermal isolation between coil and core

but if you want t oget fancy something like this:
http://www.faqs.org/patents/app/20110156687

and the Tc of copper

-Lasse

 

[Nico Coesel]

We are currently designing a compact, medium power buck converter and we would like to measure the temperature in the various components.
The power stage includes temperature sensors, but for the inductors (around 40A,
560nH) we did not find any with a temperature sensor.
I would have thought that it should be easy to integrate a wire-based temp sensor.
Since we use mostly closed-core inductors and the wire in the inductor is what gets hot, adding a temperature sensor to an existing product does not really make sense.

Actually the core of the inductor gets hot due to losses in the core.
The best thing to do is to calculate core and copper losses and see if
the core doesn't get too hot if you design your own inductor.

If you buy a readily made inductor the datasheet should tell you up to
which temperature an inductor can be used at its rated current and how
it should be derated at higher ambient temperatures.

In both cases the temperature of the core should give you a rough
estimate whether your calculations where right.

 

[Tim Williams]

If you buy a readily made inductor the datasheet should tell you up to
which temperature an inductor can be used at its rated current and how
it should be derated at higher ambient temperatures.

Manufacturers of "closed core inductors" have a bad habit of providing no
information whatsoever with regards to losses. At least some will provide
information on request (in at least one series, Bourns uses Kool-Mu cores,
from which I was able to establish the pertinent information).

Tim

 

[whit3rd]

As others have said, one can use the copper winding resistance to
measure temperature.

For heavy machinery, it is not uncommon for an extra winding or two to
be employed as a 'copper resistor'. If your coils are custom-wound,
just add some fine wire (bifilar wound) in non-inductive winding
(i.e. two matched windings in anti-series connection).

It's also possible to get optic fiber thermometers so
the pickup of electrical noise won't confuse the issue.
I haven't used these, but know that some properties (time
delay of ruby fluorescence) have well-known temperature
effects.