When Does Custom Magnetics Make Sense?

Custom vs Off-the-Shelf Magnetics in Power Electronics Design

(5 Minute Read)

Selecting the right magnetic component is an important part of power electronics design. In many applications, standard off-the-shelf transformers and inductors provide a fast and cost-effective solution. However, as electrical, thermal, mechanical and other requirements become more demanding, engineers often encounter limitations with standard catalog components.

Understanding when a custom magnetic solution makes sense can help improve efficiency, reduce thermal issues, simplify layouts, and improve long-term product reliability.

Below are some of the most common situations where engineers transition from standard magnetics to custom-designed solutions.

1. Space Constraints Require Higher Power Density

One of the most common reasons engineers move toward custom magnetics is limited board or enclosure space.

Off-the-shelf components are typically designed for broad compatibility across many applications, which often means:

• Larger footprints
• Conservative thermal margins
• Less optimized winding structures
• Higher losses from copper and core materials

In compact power electronics designs, these limitations can become problematic.

Custom magnetics allow engineers to optimize:

• Core selection
• Winding configuration
• Mounting orientation
• Height restrictions
• Thermal performance

This becomes especially important in:

• Telecom power systems
• Industrial controls
• Automotive electronics
• High-density power supplies

In many cases, improving magnetic integration can help reduce overall system size and simplify PCB layout constraints.

2. Thermal Performance Becomes a Limiting Factor

Thermal management is one of the most common challenges in high-power designs.

Standard magnetic components may meet electrical requirements while still creating:

• Excessive heat generation
• Uneven thermal distribution
• Reduced efficiency at higher loads

Custom magnetic designs allow engineers to better optimize:

• Copper loss
• Core loss
• Winding structure
• Cooling performance
• Operating frequency behavior

A common issue in power electronics is selecting a standard transformer that performs adequately during prototype testing but struggles thermally under sustained production operating conditions.

Custom designs help engineers balance electrical performance and thermal reliability more effectively.

3. EMI and Noise Requirements Are More Demanding

As switching frequencies increase, EMI performance becomes increasingly important.

Off-the-shelf magnetics may not be optimized for:

• Common-mode noise reduction
• Leakage inductance control
• Shielding requirements
• Sensitive system environments

This is especially important in:

• Medical devices
• Industrial automation and other applications
• Communication systems
• High-frequency switching power supplies

Custom magnetic solutions allow engineers to tailor winding structure and shielding strategies around specific EMI requirements rather than relying on generalized catalog performance.

In many designs, improving magnetic structure early in development can reduce downstream EMI troubleshooting later in the project cycle.

4. Long-Term Availability and Lifecycle Stability Matter

Another common reason OEMs move toward custom magnetics is long-term product stability.

Off-the-shelf components may eventually face:

• End-of-life notifications
• Specification changes
• Allocation risk
• Supply chain instability

This can create major challenges for long-life industrial and medical programs.

Custom magnetics often provide:

• Better lifecycle control
• Stable documentation
• More consistent sourcing strategies
• Greater flexibility for future revisions

For long-term production programs, supply chain stability can become just as important as electrical performance.

5. System-Level Optimization Is Required

In many advanced power electronics applications, engineers eventually reach the limitations of generalized catalog components.

Custom magnetics allow optimization around:

• Switching frequency
• Efficiency targets
• Thermal constraints
• Mechanical packaging
• Regulatory and safety requirements
• Assembly considerations

Rather than designing the system around available components, engineers can design magnetic solutions around the system itself.

This often becomes important in applications where:

• Efficiency margins are tight
• Thermal headroom is limited
• PCB space is constrained
• Reliability requirements are high

Custom magnetics may increase upfront engineering effort, but they can significantly improve long-term manufacturability and system performance.

Final Thoughts

Off-the-shelf magnetic components remain an excellent solution for many applications, particularly during rapid prototyping and lower-complexity designs.

However, as power density, thermal requirements, EMI performance, and long-term reliability become more critical, custom magnetic solutions can provide significant advantages.

At PalPilot, our engineering and manufacturing teams work closely with customers to support custom magnetic solutions for a wide range of power electronics applications, helping optimize performance, manufacturability, and long-term production stability.

Need support for a custom magnetics project? Contact PalPilot to discuss your design requirements.