Inverter low pass filter

Because of the high currents involved.

A simple low pass circuit is shown here..

However the value or R would have to be very small to avoid voltage and power losses. That means C would have to be huge or the cutoff frequency is too high. You could improve things by replacing the R with an inductor but Inductors also have resistance.

Well the corner frequency occurs when the impedance of the L is the same as the impreance of the C.

Write the equation for each. Put an equals sign between them Rearrange to give L or C.

My place doesn't have high capacity capacitors.

Yes but watch out for...

The resistance of the inductor (and the resulting power lost in it). The ripple current rating of the capacitor and it's rated design life.

Look it up.

Hope you're not Emma's brother!

The reason for this is that no simple cheap low pass filter can do that. You need pretty much filtering and components rated for considerable power to do the needed filteting at the power range that the typical square wave inverters use. If it would be cheap and easy, there would be pretty much more of those sinewave inverters out there.

In a typical cheap capacitor in parallel and inductor in series low pass filter with the load. How many percentage do you think is the suppression of the high frequency from a square wave signal, 70%, 90%? Do you know of a design where 99% or even 100% of the high frequency can be suppressed. I don't mind the cost. I'm just studying inverter efficiency for future marketing. Pls. share me a site or diagram where I could build one and test in an oscilloscope. Many thanks.

Manny

Anyone got time to help "Manny"?

If you have then perhaps you could also answer his physics questions as well over on sci.physics :-)

Modelling Photoelectric Effect Without Photons All 2 messages in topic - view as tree Manny Jul 1, 10:52 pm show options

Newsgroups: sci.physics From: "Manny" - Find messages by this author Date: 1 Jul 2005 19:52:01 -0700 Local: Fri,Jul 1 2005 10:52 pm Subject: Modelling Photoelectric Effect Without Photons Reply | Reply to Author | Forward | Print | Individual Message | Show original | Report Abuse

In 1905. There is still no good model of the atoms. Why can't one say that as the frequency of the electromagnetic field increases, the electron orbital can no longer take the energy and so gets ejected from the atom. Why does it have to be a photon particle hitting the electron. What if the electron orbital can only accept certain energies in terms of the frequencies and when it exceed it, the electron orbital gets destructed resulting in the electron leaving the atom?

Has anyone got an alternative atomic model whereby photoelectric effect can occur without using the concept of photon particles? For those who hate photons (like Dr. Richard Perry). You must come up with how the atomic can eject the electron by mere electromagnetic wave energy. This also goes for the compton scattering.

Manny

What you could do is generate various levels of DC and switch between them.

That would leave you with a sine approximation, which would mean you only need to filetr out a higher freqency.

Or even better, use PWM and a small output filter - essentially adjusting a DC power supply from 0 to max to 0 - and then reversing polarity with a bridge.

Thomas

So you are saying that low pass filters used on a square wave output can only exist in these configurations only 1. single inductor

1. inductor in series with capacitor in parallel 3. T shape double inductor 4. Pi shape configurations. Meaning to create more sophisticated ones I have redesigned the entire source to produce the desired output. Is this what you mean?? All agrees? Tnx.

Manny