# 12 to 220 modified inverter

1. ## 12 to 220 modified inverter

I have built my 12 to 220 modified inverter (1000 watt).
I use ATMEGA8 and IRF3205 in my design.
I am sure about 220V and 50Hz on output.
My design almost look like this.

In addition to feedback signal.
My problem is : this inverter Destroyed my three home fans (its driver board use triacs).

Is there any way to solve this problem?

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2. ## Re: 12 to 220 modified inverter

220 modified
This sounds as though your inverter is modified sinewave, correct? A waveform whose appearance is halfway between square wave and sinewave?

The problem might be a matter of how high your peak voltage goes, in order to match the RMS power of a sinewave.

A 220V sine has a peak amplitude of 220 x √2, or 311V. Does your inverter put out a greater amplitude?

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3. ## Re: 12 to 220 modified inverter

The speed control circuit using triacs in the fan expects a smooth sinewave, not the abrupt pulses of a modified sinewave.
The 10V transformer does not produce enough output voltage for the average voltage to be 220AC. The peak voltage of 220VAC is 311V but the 10V transformer produces a peak voltage of less than 12/10V x 220V= 264V. Then the average output voltage is only 187VAC.

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