I would like to ask about the problem of SPWM wave passing through a low-pass filter

Aguilera

I would like to ask about the problem of SPWM wave passing through a low-pass filter [Copy link]

I have a question. When the SPWM wave generated by the 200HZ sine wave and the 20KHZ triangle wave passes through a 400HZ low-pass filter, why does the restored sine wave fluctuate?

maychang

A four-trace oscilloscope is used in the simulation diagram, but only two channels are actually used. Then two-trace oscilloscopes XSC3 and XSC4 are used. Why not connect a four-trace oscilloscope to the input and output of U3A and the output after LC filtering to view the waveforms at three locations at the same time?

davidzhu210

Look at the two input waveforms of the comparator

qwqwqw2088

Looking at the simulation, there are harmonics

There are requirements for the voltage of the two input waveforms. The sine wave Vpp cannot exceed the triangle wave Vpp, so that there is an SPWM wave output at the output end of the comparator.

关外秀才

Thanks for sharing, I learned a lot.