Industrial electronics
Myth vs fact
Does a PWM Inverter Output a Pure Sine?
Your inverter's output looks nothing like a sine wave
Quick check · tap an answer to continue
Lesson notes
Key points
- The switches only connect plus or minus DC voltage, so the raw output voltage is a train of rectangular pulses.
- An inductor, or an LC low-pass filter, blocks the high-frequency switching harmonics while passing the low-frequency fundamental.
Myth: A PWM inverter directly outputs a pure sine voltage
Fact: It outputs pulses; filtering or load inductance shapes them into a near-sine
Takeaway: PWM gives pulses; filters and inductance give the sine.
Quick check: Myth or fact: raising the carrier frequency makes harmonics easier to filter.
- Myth
- Fact
- Depends
Harmonics move higher, further from the fundamental, so a smaller filter works.
Switched outputLC filter
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