delta06

Need help from all,

I wanted to build a small inverter (50 - 100 W) for my school project, just want to know about the transformer, is it an ordinary transformer that was just connected in reverse? I don't know much about electronics yet, thanks in advance.

mvs sarma

If the frequency of the inverter is around 50 or 60Hz, perhaps the ordinary transformers could be used.But , there is a problem. The core saturates with DC flow in the low voltage primary. It is generally overcome by packing the core of the transformer in a special way. All "E"s of the E & I core one one side and all the "I"s on the other side. With a reluctance air gap calculated. this gap can be in the form of Teflon sheeting to meet the required "mills"(=1/1000 of inch is a mill - perhaps you might already know it).

with such arrangement and if the primary wire is thick enough to carry the required current for deliver 50 to 100W on secondary, leaving margins for system efficiency and Power factor and also for square wave vs Sine wave.

Once all the above criteria are met , you will observe the size of the transformer will increase.

On the other hand if high frequency is used, like the modern ones (PWM type), you might need a Ferrite cored Transformer- the size could be reduced if high frequency versions are designed.

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Regards,
Sarma.