Everything you need to know about professional magnetic component design.
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15 Chapters
100+ Illustrations
Engineering Design Examples
Interactive Calculators
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Introduction
Understanding magnetic theory is important, but practical engineering requires applying that knowledge to real-world designs.
Throughout this guide we have explored the principles that govern magnetic components, including:
- Inductance
- Core materials
- Energy storage
- Saturation
- Core geometry
- Winding design
- Loss mechanisms
- Thermal performance
In this chapter, we will walk through several practical examples that demonstrate how these concepts are combined to create manufacturable inductors.
The goal is not simply to calculate an answer.
The goal is to understand the engineering decisions that transform electrical requirements into a reliable magnetic component.
Example 1: Buck Converter Output Inductor
Design Requirements
Assume a switching regulator requires:
| Parameter | Value |
|---|---|
| Inductance | 100 µH |
| RMS Current | 5 A |
| Peak Current | 6 A |
| Switching Frequency | 100 kHz |
| Maximum Temperature Rise | 40°C |
Step 1: Calculate Energy Storage
As discussed in Chapter 06: Energy Storage in Magnetic Components, stored energy is:
Substituting:
Result:
This tells us how much energy the magnetic structure must safely store.
Step 2: Select Core Material
Referring to Chapter 04: Understanding Magnetic Core Materials, ferrite is an excellent choice for 100 kHz operation because it provides:
- Low core loss
- Good efficiency
- Wide availability
Step 3: Select Core Geometry
Using the concepts from Chapter 08: Selecting the Right Core Geometry, an ETD or EE core would be appropriate.
Reasons:
- Adequate winding window
- Good thermal performance
- Easy manufacturing
Step 4: Verify Saturation Margin
As discussed in Chapter 07: Understanding Magnetic Saturation, verify that peak current does not push the core near saturation.
Maintain a comfortable design margin.
Step 5: Estimate Losses
Copper losses:
Core losses:
Use manufacturer loss curves or Steinmetz parameters discussed in Chapter 10: Understanding Core Losses.
Final Result
A ferrite ETD core with an appropriate air gap and properly sized winding produces a compact, efficient inductor suitable for the application.
Example 2: High-Current Power Inductor
Design Requirements
| Parameter | Value |
|---|---|
| Inductance | 10 µH |
| RMS Current | 30 A |
| Peak Current | 40 A |
| Frequency | 200 kHz |
Primary Design Challenge
The challenge is no longer inductance.
The challenge becomes handling current while minimizing copper losses.
Conductor Selection
Referring to Chapter 09: Choosing the Correct Wire and Winding Method, a single conductor may not be practical.
Potential solutions include:
- Parallel conductors
- Copper foil
- Litz wire
The resistance relationship is:
Increasing conductor area reduces resistance.
Thermal Considerations
As discussed in Chapter 12: Thermal Design of Inductors, high-current designs are often limited by temperature rather than inductance.
Losses must be carefully evaluated.
Final Result
A larger core with multiple parallel conductors produces significantly lower winding losses and improved thermal performance.
Example 3: Compact Portable Device Inductor
Design Requirements
| Parameter | Value |
|---|---|
| Inductance | 22 µH |
| Current | 1.5 A |
| Frequency | 500 kHz |
| Height Restriction | 8 mm |
Design Challenge
Physical size is the primary constraint.
Core Selection
Using concepts from Chapter 08, an EFD core may be appropriate because it offers:
- Low profile
- Efficient use of space
- Good manufacturability
Frequency Considerations
Referring to Chapter 10, higher frequencies increase core losses.
Material selection becomes particularly important.
Final Result
A compact ferrite EFD design satisfies both electrical and mechanical requirements while maintaining reasonable efficiency.
Example 4: EMI Filter Inductor
Design Requirements
| Parameter | Value |
|---|---|
| Inductance | High |
| Current | Moderate |
| Efficiency | Secondary |
| EMI Reduction | Critical |
Design Challenge
The primary objective is noise suppression.
Core Selection
Referring to Chapter 08, toroidal cores offer:
- Excellent magnetic containment
- Low leakage flux
- Reduced EMI
Design Trade-Off
Toroids are more difficult to manufacture but often provide superior EMI performance.
Final Result
A toroidal ferrite design minimizes external magnetic fields and improves EMI compliance.
Example 5: Designing for Lowest Cost
Design Requirements
| Parameter | Value |
|---|---|
| Moderate Inductance | Yes |
| Moderate Current | Yes |
| Lowest Cost | Critical |
Design Strategy
When cost is the dominant factor:
- Use standard core families
- Minimize material variety
- Simplify assembly
- Avoid specialized conductors
Core Selection
EE cores are often an excellent solution because they are:
- Widely available
- Easy to wind
- Inexpensive
Final Result
A simple ferrite EE design provides acceptable performance at minimal cost.
Comparing the Designs
Notice that every example produced a different solution.
| Design Goal | Likely Solution |
|---|---|
| General Purpose | ETD |
| High Current | Large Core + Parallel Conductors |
| Compact Design | EFD |
| EMI Reduction | Toroid |
| Lowest Cost | EE |
This illustrates one of the most important lessons in magnetic design:
Different requirements produce different optimal solutions.
Lessons Learned
All practical inductor designs follow the same general process:
- Define requirements
- Calculate energy storage
- Select material
- Select geometry
- Determine turns
- Verify saturation
- Design winding
- Calculate losses
- Evaluate temperature rise
- Optimize
These steps were explored in detail in Chapter 13: Designing Inductors for Switching Power Supplies.
Connecting Theory to Practice
Every chapter in this guide contributes to the design process.
| Topic | Chapter |
|---|---|
| Inductance | Chapter 02 |
| Flux Density | Chapter 03 |
| Core Materials | Chapter 04 |
| Air Gaps | Chapter 05 |
| Energy Storage | Chapter 06 |
| Saturation | Chapter 07 |
| Core Geometry | Chapter 08 |
| Wire Selection | Chapter 09 |
| Core Losses | Chapter 10 |
| Copper Losses | Chapter 11 |
| Thermal Design | Chapter 12 |
| Design Process | Chapter 13 |
| Common Mistakes | Chapter 14 |
Practical design requires understanding all of them together.
SolidMag Engineering Note
Every Magnetic Design Is a Trade-Off
There is rarely a single perfect solution.
One design may be:
- Smaller
- Cooler
- Cheaper
- More efficient
But seldom all four simultaneously.
The most successful engineers understand that magnetic design is fundamentally an optimization process.
The best design is not the one with the most impressive specifications.
The best design is the one that satisfies the requirements of the application.
What You’ve Learned
In this chapter you learned:
- How magnetic design principles are applied in real products
- How requirements drive design decisions
- Why different applications require different core geometries
- How current affects conductor selection
- Why thermal performance influences core size
- How EMI requirements affect magnetic design
- Why cost optimization changes design choices
- How all previous chapters work together in practical engineering
Conclusion: The Ultimate Guide to Inductor Design
You have now completed the Ultimate Guide to Inductor Design.
You have learned:
- How inductors work
- How magnetic fields store energy
- How core materials affect performance
- How air gaps increase energy storage
- How saturation limits magnetic components
- How core geometry affects design
- How conductor selection impacts efficiency
- How losses create heat
- How thermal performance affects reliability
- How engineers design practical inductors
Magnetic component design combines physics, materials science, thermal management, manufacturing, and optimization.
While the calculations can appear complex, the underlying process is systematic and learnable.
With the knowledge gained throughout this guide, you now have the foundation required to understand, evaluate, and begin designing practical inductors for real-world applications.power electronics systems.
Put Theory Into Practice
The examples in this chapter demonstrate how engineers combine electrical, thermal, and magnetic requirements to create practical inductors.
While manual calculations are valuable for understanding the design process, modern engineering tools can dramatically reduce development time.
SolidMagnetics provides several free design calculators that help engineers quickly evaluate design options before committing to a final magnetic design.
Inductor Design Quick Estimator
Estimate basic inductor parameters from:
- Inductance
- Current
- Frequency
- Ripple requirements
[solidmag_quick_estimator]Ripple Current Calculator
Determine ripple current requirements and understand how ripple affects magnetic design.
[solidmag_ripple_calculator]Wire Size Calculator
Select appropriate conductor sizes and evaluate current-carrying capability.
[solidmag_wire_calculator]Saturation Checker
Verify that a proposed design remains below saturation limits.
[solidmag_saturation_checker]Core Loss Estimator
Estimate magnetic core losses based on:
- Frequency
- Flux density
- Core material
[solidmag_loss_estimator]Introducing Automated Inductor Design
Traditional magnetic design often requires:
- Core selection
- Gap calculations
- Turns calculations
- Wire selection
- Thermal analysis
- Manufacturability review
These steps can require hours of manual calculations and multiple design iterations.
The SolidMagnetics Design Automation System performs these tasks automatically and generates manufacturable magnetic designs in minutes.
What the SolidMagnetics Design System Produces
After entering your design requirements, the system automatically evaluates candidate magnetic designs and generates:
- Complete inductor design recommendations
- Core selection
- Air gap calculations
- Turns calculations
- Wire recommendations
- Thermal estimates
- Loss calculations
Available deliverables include:
- 3D SolidWorks Models
- STEP Files
- Engineering Drawings
- BOM Files
- Manufacturing Documentation
Where To Go Next
Ready to Generate Your Custom Magnetic Design?
Upload your electrical requirements and receive:
- 3D CAD model
- Manufacturing drawings
- BOM
- Build-ready geometry