Sine wave inverter LC filter design help needed.

[themaccabee]

I'm trying to build a 110V,50Hz ,100VA sine wave inverter

using a Boost section which delivers 170V and using this section for an H bridge driven by IR2110 ICs and finally an LC filter to create back the Sine wave.The controller im using is PIC.

My problem is the output LC filter design

i went through the link **broken link removed**

and saw the LC filter depicted there..But i couldnt find the correct method to design the same?
Can somebody help me?

Also when i tried with the similar LC topology im getting a square wave at the output at no load?

Shall i use a dummy load? But the dissipation is very high in that case bringing the efficiency down.

 

[FvM]

Also when i tried with the similar LC topology im getting a square wave at the output at no load?

The said example circuit uses a 20 kHz PWM frequency and a LC-filter with about 2.5 kHz cut-off frequency. It's effectively impossible
to get a square wave at the output under similar conditions. (You may get a 50 or 60 Hz square wave by designing the PWM modulator incorrectly...).
What are your operating parameters?

 

[Ice Lord]

Hello guys,

i got the Problem to find the right values for the LC Outputfilter of a H-Bridge...
My H-Bridge delivers a good trilevel PWM Signal.
Specifications are 50Hz Sqaure over 80kHz PWM.
The biggest Problem is to find a suitable Inductor to get a good cutoff Frq.
Which cutoff Frq should i use to get a "good" sinewave, dont have to be a low distortion factor, but should be practiable sinewave, for controlling an AC Rotor!
I thougt about a CLC ρ-filter, and i found some Applications which use mH Inductors. But for my circuit i need up to 10A Peak, and to find those Inductors is impossible for me
The next option would be to wind my own Inductor, but I lost my "how-to-wind-a-powerchoke-in-one-day" book.

Can anybody help me, or give me some tricks to design a suitable Inductor.