Power Factor Correction (PFC) stages are commonly used in industrial power supplies, EV chargers, telecom equipment, and high-power AC-DC converters.

One of the most critical components in a boost PFC stage is the boost inductor.

In this example, we will walk through the design process for a 2 kW continuous-conduction-mode (CCM) PFC inductor.

The objective is to demonstrate the engineering process used to select and optimize a practical magnetic design.

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Design Requirements

Input Voltage:

90–265 VAC

Output Voltage:

400 VDC

Output Power:

2000 W

Switching Frequency:

100 kHz

Target Efficiency:

95%+

Maximum Temperature Rise:

40°C

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Quick Design Estimate

Before performing detailed calculations, engineers often estimate candidate magnetic designs.

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Step 1: Determine Output Current

Output current:

2000 W ÷ 400 V

= 5 A

This establishes the minimum output current requirement.

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Step 2: Determine Input Current

At low-line operation:

90 VAC

Input current becomes substantially higher.

This operating condition usually drives the magnetic design.

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Step 3: Select Ripple Current Target

A common design goal is:

20%–40% ripple current

For this example:

30% ripple current

is selected.

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Calculate Ripple Current

Ripple current influences:

• Core size
• Copper losses
• Temperature rise
• Saturation margin

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Step 4: Determine Required Inductance

The boost inductor must maintain continuous conduction while limiting ripple current.

Key design considerations include:

• Worst-case line voltage
• Switching frequency
• Maximum current
• Efficiency targets

Inductance is typically optimized iteratively rather than chosen from a single equation.

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Step 5: Evaluate Energy Storage

PFC inductors store significant magnetic energy.

Engineers must verify:

• Core size
• Energy capability
• Saturation margin

👉 Related Guide: How to Calculate Inductor Energy Storage

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Step 6: Select Core Material

Common choices include:

• Ferrite
• Powdered Iron
• Nanocrystalline

For high-power PFC designs:

Ferrite is frequently preferred because of:

• Low losses
• High-frequency performance
• Wide availability

👉 Related Guide: How to Choose the Right Core Material

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Step 7: Check Saturation Margin

PFC inductors often operate near their design limits.

Saturation analysis is critical.

👉 Related Guide: Understanding Magnetic Saturation

Verify Saturation Margin

Adequate margin must be maintained at low line and maximum load conditions.

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Step 8: Select Conductor Size

Large currents require careful conductor selection.

Possible options include:

• Single large conductor
• Parallel conductors
• Litz wire
• Copper foil

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Evaluate Wire Options

Wire selection directly influences:

• DCR
• Copper losses
• Thermal performance

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Step 9: Estimate Losses

Losses come from:

• Copper losses
• Core losses
• AC winding losses

Reducing losses improves:

• Efficiency
• Reliability
• Thermal performance

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Estimate Magnetic Losses

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Step 10: Thermal Evaluation

Thermal design verifies:

• Maximum winding temperature
• Core temperature
• Long-term reliability

👉 Related Guide: How to Reduce Inductor Temperature Rise

The target is:

Less than 40°C temperature rise

under worst-case conditions.

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Practical Optimization Process

A real engineering workflow typically evaluates:

• Multiple core families
• Multiple gap sizes
• Multiple wire configurations
• Thermal performance
• Cost

before selecting a final design.

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Conclusion

PFC boost inductors represent one of the most important magnetic components used in modern power electronics.

A successful design balances:

• Efficiency
• Saturation margin
• Temperature rise
• Manufacturability
• Cost

while meeting stringent performance requirements.

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Need Help Designing PFC Magnetics?

The SolidMagnetics platform helps engineers optimize:

• Core selection
• Air gap sizing
• Saturation margin
• Thermal performance
• Manufacturability

while automatically generating CAD models, engineering drawings, BOMs, and production-ready outputs.