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Help needed ...

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New Member
Hello friends !
It's my first post here to have some help from you people. I hope that I'll get it.

In fact, I'm making an inverter ( for a small level UPS) in which I have 12V dc supply and the inverter is successful to convert it into 12V peak ac square wave (12V RMS). Now, I want to step it up to 220V RMS. I have the frequency of 50 Hz. only. At this low frequency, a step-up transformer produces spikes due to inductor action. Tell me friends, what should I do to have 220V peak ac square wave (220V RMS) ?


New Member
One way to get rid off the spikes is to use a diode that is in reverse bias with respect to your transformer secondary.

Do you really need a 220 V square wave or is 220 V sine wave ok?

Here is some suggestion off the top of my head:

If sine wave on secondary is ok, then you could use a filter on the 12V side to get rid off some harmonics before you send the signal through the transformer. However, since this could be impractical a better solution is to connect load neutral to the dc battery midpoint. (e.g node in between two 6 V batteries). This would eliminate the 3rd harmonic which is most significant and also 9, 15, 21 etc. (these are not very significant). Of course you could also use different PWM techniques to get rid off harmonics. If you want sinusiodal output you could use SPWM or MSPWM, however if you want to get rid off specific harmonics only I suggest that you use the harmonic elimination techniques. Having ess harmonics means that you would have less spikes in your secondary voltage

I don't know if this helps
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