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5 months ago in Power Electronics By Shubham

Why is a boost converter the go-to for power factor correction?

For active PFC, everyone uses a boost converter. Why not a buck? It can step down voltage, which seems useful.

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By Aamir Answered 2 months ago

The magic is in the input current. A boost converter, operating in continuous conduction mode (CCM), draws a continuous current from the AC line. That lets you shape it to follow the sinusoidal voltage waveform near-unity PF. A buck converter's input current is inherently discontinuous (chopped). Shaping that into a clean sine wave is much harder and less efficient. Boost gives you a smooth handle on the current. Buck gives you a headache. That's why boost wins.

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