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12vdc to 230 vac inverter freewheeling diode burning.

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Hi,

again, please read how LC filter work. I think it is important that you understand what you design. In every description you can see where the input is connected and the output.
Then you will see that the load must be connected to the Cs.
Only change the upper load connection to the upper node of the Cs, so that the load is in parallel to the Cs.

Klaus
 
KlausST said:
Hi,

again, please read how LC filter work. I think it is important that you understand what you design. In every description you can see where the input is connected and the output.
Then you will see that the load must be connected to the Cs.
Only change the upper load connection to the upper node of the Cs, so that the load is in parallel to the Cs.

Klaus
Click to expand...

:-(
I am sorry but i cant understand what you said,do you mean an LC filter at secondary, just before load is connected.
 

You are trying to knock down a square wave to a sine wave at 50 - 60 Hz. Big expensive inductor, you could try using a primary or secondary of a large iron transformer for the inductor.
 

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FlapJack said:
You are trying to knock down a square wave to a sine wave at 50 - 60 Hz. Big expensive inductor, you could try using a primary or secondary of a large iron transformer for the inductor.
Click to expand...

I have e25 bobbins for ferrite transformers, I can wind them with 20 swg copper, can I use them instead of transformer ?
 

myfaithnka said:
I have e25 bobbins for ferrite transformers, I can wind them with 20 swg copper, can I use them instead of transformer ?
Click to expand...

No, ferrite is for high frequency, It would take a HUGE ferrite core to have any effect on 50-60Hz
 
FlapJack said:
No, ferrite is for high frequency, It would take a HUGE ferrite core to have any effect on 50-60Hz
Click to expand...

ok,I wonder what is done in older square ware inverters,to solve this problem.I think most of them are still square wave type.
 

myfaithnka said:
ok,I wonder what is done in older square ware inverters,to solve this problem.I think most of them are still square wave type.
Click to expand...

Yes, the older inverters Were square wave out. But it should be fairly easy to find an old iron transformer and just try one of the windings for an inductor. You will see the results right away on the oscilloscope.
 
There are no free-wheeling diodes used in this design. Remove them.
The voltage created should not exceed the Vds in this setup transformer which should have a 20:1 turns ratio and VA rated for your load. Since the drive is from switched current sources, the negative feedback into pin 1 is the control point for PWM regulation of the inverter.

This design would be overkill for just a 20W CFL as they operate on rectified line voltage DC, which you could supply instead of AC for your boost convertor using a small HF transformer instead of a steel core step up 50Hz type.
 
Here is a simple simulation, showing how a second order butterworth filter can turn a square wave into a reasonable sine wave, using the coil and capacitor values shown.

3754637400_1409841399.png


The load calculates to be 950 ohms (based on the 50 W figure mentioned earlier).
 
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