Inductor in LC filter

[Aan]

What type of inductors typically used in LC filter, is it toroidal or solenoid ?

Thanks.

 

[AN920]

There's LC filters of all kinds, low/high frequency and of various power levels. For example, you won't use toroid at very high frequencies because of the losses. Each applicarion will require its own selection.

 

[indulis]

The amount of current and frequency has a lot to do with selecting the proper core shape (for cross sectional area) and material (for Bsat). How much ripple current can yo live with?

For example, you won't use toroid at very high frequencies because of the losses.

You can get toriods in soft ferrite material now and the "Cool-Mu" toriods from Magnetics work very well in SMPS.

 

[AN920]

Maybe we should define "very high frequency"

 

[Aan]

I recommend a search on google for the type of filter you need.....

I have searched google and have not yet find any good site to use as reference to build LC filter..

There's LC filters of all kinds, low/high frequency and of various power levels. For example, you won't use toroid at very high frequencies because of the losses. Each applicarion will require its own selection.

I build a DC-AC converter with class D amplifier with frequency carrier of 10kHz.

The amount of current and frequency has a lot to do with selecting the proper core shape (for cross sectional area) and material (for Bsat). How much ripple current can yo live with?

0.1mAmp..how much ripple current typically find in any design of LC filter ?

 

[audioguru2]

The 10kHz noise will drive you nuts. Use a carrier frequency above 20kHz so it won't be heard.

 

[prateeksikka]

i dont think frequency is the criteria .
it is just the question of current carrying capability.

 

[indulis]

Frequency does matter.

In a power application for example... take a simple buck converter, Vout/Vin will tell you the ~ duty cycle, but the frequency will determine the "off time" (flywheel period during which current is flowing out of the inductor) of the converter. That "off time" plays a role in the inductor value and will determine the ripple current amplitude. A properly sized "power inductor" that works at 100KHz will not work at 1KHz... it will saturate. Frequency will determine max flux excursion and hence, max current capability.