Power semiconductors

What is the purpose of a power factor correction (PFC) circuit used in power supplies?

  1. ATo double the output voltage
  2. BTo increase supply noise
  3. CTo shape the input current into a sine wave matching the voltage, bringing the power factor close to 1
Show answer and explanation

Answer: C. To shape the input current into a sine wave matching the voltage, bringing the power factor close to 1

In a simple rectifier with a smoothing capacitor, input current flows only near the voltage peaks, producing a distorted waveform; the power factor drops and harmonics disturb the power grid. A PFC circuit makes the input current a sine wave with the same shape as the voltage, improving the power factor and suppressing harmonics.

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