PFC Boost Inductor

L = Vin² × (Vout − Vin) / (Vout × ΔI × f × Pout)

Calculator

Result
—

Formula

L = Vin² × (Vout − Vin) / (Vout × ΔI × f_sw × Pout)

Description

Active power factor correction uses a boost converter operated in continuous conduction mode to shape the input current waveform to follow the input voltage, achieving near-unity power factor. The PFC inductor is the critical component determining the ripple current magnitude. The worst-case ripple occurs at the peak of the input voltage (or at specific duty cycles depending on the topology). This formula gives the inductance needed to limit the maximum current ripple to ΔI. PFC is mandatory for power supplies above 75 W per IEC 61000-3-2.

Variables

  • V_in — RMS input voltage (V)
  • V_out — PFC output voltage, typically 380-400 V (V)
  • ΔI — Maximum allowable ripple current (A)
  • f — Switching frequency (Hz)
  • P_out — Output power (W)

Practical Notes

Typical values: 230 V input, 400 V output, 65 kHz switching, 20% ripple gives L ≈ 200-600 µH for 100-1000 W supplies. The inductor must handle the peak current (√2 × Iin_rms + ΔI/2) without saturating. Powdered iron or gapped ferrite cores are typically used. Core loss is significant due to the 100/120 Hz current envelope and must be carefully evaluated.

Related Formulas

Linear Regulator Dissipation Efficiency Buck Converter Boost Converter Peukert Effect Energy After Losses

Need more features?

Save calculations, import telemetry data, simulate battery discharge, and collaborate with your team.

Try the App