spwm inverter no load

[mr.man]

why in no load, the output only show the rectangular waveform. Is it to be pure sine wave after we applied LC filter?
i already got nice sine wave with pure resistive load.

thank you

 

[Tahmid]

You filter the output of the bridge (which you are driving with SPWM signals) using an LC filter and apply a load. Observe the output. And you should get a sine wave output.

Is it to be pure sine wave after we applied LC filter?

Yes, you have to use the LC filter. After filtration by the LC filter, you can observe a sine wave output.

Since you have an LC filter (part of which is an inductance), as far as I know, you need a certain minimum load to observe sine wave output.

Hope this helps.
Tahmid.

 

[FvM]

The output of an reasonably dimensioned LC filter (= the voltage across the filter capacitor) can't be a square wave. Apparently the measurement setup is wrong, e.g. viewing a bridge output signal single ended instead of differentially.

There may be other effects at no load, e.g. output voltage out of range.