1.5kva pure sine wave inverter

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hi,

I need circuit design and guidance for designing 1.5kva pure sine wave inverter. am gonna use 24volt battery.

i need transformer design details also how to decide secondary side voltage , if primary is 230 V.



Thanks in advance
 

Are you planning to use a Cu/Fe 50/60 Hz transformer - or all high freq switchmode ... ?
 

probably best to go open loop, pwm on the 24V, filter to a sine wave, then put thru 50Hz transformer ... full bridge, one slow, one fast (pwm )

feedback via dia amp from the LV primary ... 14v : 230V step up
 

7.2V Per 12V battery will be sufficient. You may need to go for a split bobbin transformer to achieve required leakage inductance if your switching frequency is less than 40Khz.
 
it's not that great idea to use leakage L in the mains freq Tx to do filtering - all you do is increase losses in the Tx

far better to filter first and have a sine wave in the Tx with limited filtering on the Tx o/p - this means that for a closely coupled Tx ( e.g. toroid ) you can sense the Vout on the LV side ...
 

Easy peasy said:
probably best to go open loop, pwm on the 24V, filter to a sine wave, then put thru 50Hz transformer ... full bridge, one slow, one fast (pwm )

feedback via dia amp from the LV primary ... 14v : 230V step up
Click to expand...



so primary 14v:230v secondary
and feedback voltage asusual 14volt ..

is this right?

for 1.5kva.. if primary 14v . then primary current is 108 A..(p=vi). Can i design max primary current as 108 A or more ??
 

Switching 108 amps at say 20kHz, is not for the first timer, don't forget the 1st filter inductor must carry this current also - and attenuate the switching harmonics of the square edges - and the first filter cap must carry appreciable AC current too, in performing the filtering, then the 14V pri will carry only the load current ( and the magnetising current ) a modest cap on the HV output side ( 230Vac) of the Tx, say 2u2, 630VDC, can then provide the final filtering, using the small amount of leakage in the Tx.
Again - if you have not done this before - it will be a significant challenge.
 

Yeah this is going to be a monster.

20Khz is slow and will result in a huge inductor. Why not higher switching frequency?

Multiple phases would also be a common approach to this problem.
 

switching 108 amps at > than 20kHz is a challenge if you have not done it before - a low leakage mains Tx will give only a little droop with load and allow the Vout to be differentially taken from the LV side - simplifying control ...
 

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