Maximum Power Point Tracking (MPPT) converters are widely used in solar energy systems to maximize power extraction from photovoltaic panels.

One of the most important magnetic components in an MPPT converter is the power inductor.

In this example, we will walk through the design process for an MPPT inductor used in a 48V battery charging system.

The objective is to demonstrate the engineering workflow used when selecting and optimizing a practical magnetic design.

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Design Requirements

Solar Panel Voltage:

30V to 80V

Battery Voltage:

48V

Output Power:

1500W

Switching Frequency:

100 kHz

Target Ripple Current:

25%

Maximum Temperature Rise:

40°C

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Quick Design Estimate

Before detailed calculations, engineers often evaluate candidate magnetic solutions.

[solidmag_quick_estimator]

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Step 1: Determine Output Current

Output current:

1500W ÷ 48V

≈ 31A

This establishes the primary current requirement.

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Step 2: Select Ripple Current

A common design target is:

20–30% ripple current.

For this example:

25% ripple current

Ripple current target:

31A × 0.25

≈ 7.8A

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Calculate Ripple Current

[solidmag_ripple_calculator]

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Why Ripple Current Matters

Ripple current affects:

• Peak current
• RMS current
• Copper losses
• Temperature rise
• Saturation margin

👉 Related Guide: Ripple Current Explained

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Step 3: Calculate Peak Current

Peak current becomes:

31A + (7.8A ÷ 2)

≈ 35A

This value is used for saturation analysis.

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Step 4: Verify Saturation Margin

The magnetic design must remain below saturation at:

• Maximum power
• Worst-case solar conditions
• Elevated temperatures

👉 Related Guide: Understanding Magnetic Saturation

Check Saturation Margin

[solidmag_saturation_checker]

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Step 5: Select Core Material

Potential candidates include:

• Ferrite
• Powdered Iron
• Nanocrystalline

For a 100 kHz MPPT converter:

Ferrite is often preferred because of:

• Low losses
• Good efficiency
• Broad availability

👉 Related Guide: How to Choose the Right Core Material

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Step 6: Determine Wire Size

The winding must safely carry:

31A average current

while minimizing losses.

Possible options:

• AWG10
• AWG9
• Parallel conductors
• Copper foil

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Evaluate Wire Options

[solidmag_wire_calculator]

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Step 7: Estimate Losses

Major losses include:

• Copper losses
• Core losses
• AC winding losses

Reducing losses improves:

• Efficiency
• Battery charging performance
• Reliability

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Estimate Losses

[solidmag_loss_estimator]

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Step 8: Evaluate Thermal Performance

The design target is:

Less than 40°C temperature rise

under worst-case operating conditions.

👉 Related Guide: How to Reduce Inductor Temperature Rise

Thermal analysis should always accompany magnetic design.

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Step 9: Compare Candidate Cores

Engineers often evaluate:

• ETD34
• ETD39
• PQ35
• PQ40

Tradeoffs include:

• Size
• Cost
• Losses
• Thermal performance

Multiple iterations are typically required.

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Practical Optimization Process

A real MPPT magnetic design may evaluate:

• Multiple inductance values
• Multiple core families
• Different conductor arrangements
• Thermal performance
• Manufacturability

before selecting a final design.

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Conclusion

Solar MPPT inductors must balance:

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

A systematic design approach helps engineers create reliable and efficient renewable energy systems.

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Need Help Designing Solar Magnetics?

The SolidMagnetics platform helps engineers optimize:

• Core selection
• Saturation margin
• Wire sizing
• Thermal performance
• Manufacturability

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