Pure sine wave or modified inverter?

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arvinfx

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Hi,

I know that modified sine wave is not appropriate for all loads.
But nowhere I could find what about smps ? I need to supply a pc and a LED TV only.

Is the modified sine wave suitable with smps or not? this is the question
 
Sine wave inverters are best for loads that are primarily inductive, such as motors. Most common switch mode supplies really don't care what the wave shape is, since they just feed a rectifier and capacitor.

Many 'universal input' supplies can run just fine on 150 to 350 Volts DC.

Known exceptions:
- If the supply has a 115/230 volt range switch, then it needs AC for the low range since it uses a voltage doubler. But they should work fine on ~350VDC for the high range.
- Photo flash supplies may also use voltage multipliers.
- Clocks or other products where the line frequency is used as a time base.
 
I would prefer a sine wave inverter. A "modified sine wave" is actually two square waves, one (smaller) on top of the other (bigger) and the fast rise times of the waveform cause stress on the rectifier diodes and filter capacitor because the capacitor charging current is i = C dv/dt . The line filter components will also be stressed removing the additional harmonics of the modified sine waveform.

Timescope
 
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