Magnetic Design

The Magnetic Core Is the Foundation of Transformer Performance

The magnetic core determines much of a high-frequency transformer’s electrical and thermal behavior.

Selecting a core is therefore more than choosing a physical size.

HY MFG evaluates the relationship between:

Frequency → Flux Density → Core Material → Core Loss → Temperature → Power Density

Core Material Selection

Different ferrite materials have different magnetic characteristics across frequency and temperature ranges.

Core selection considers:

• Operating frequency
• Flux density
• Core loss
• Temperature
• Power level
• Core geometry
• Availability and production requirements

The goal is to select a magnetic material appropriate for the actual operating conditions.

Flux Density

Flux density is one of the fundamental parameters in transformer design.

Operating the core at excessive flux density can result in:

• Increased core loss
• Higher temperature
• Reduced efficiency
• Possible saturation

On the other hand, unnecessarily conservative flux density can increase core size and cost.

The design therefore seeks an appropriate balance between:

Magnetic Performance + Efficiency + Size + Thermal Margin

Core Loss

At high switching frequencies, core loss becomes an important part of the overall transformer loss budget.

Core loss depends on factors including:

• Frequency
• Flux density
• Temperature
• Magnetic material
• Operating waveform

For this reason, transformer design should evaluate the actual operating waveform rather than relying only on nominal frequency.

Power Density

Modern power supplies increasingly require smaller magnetic components.

Higher power density can reduce system size, but it also increases thermal challenges.

HY MFG considers:

Core Size + Window Utilization + Winding Loss + Core Loss + Cooling Conditions

as part of the magnetic design process.

Magnetic Design Beyond the Core

A complete magnetic design also considers:

• Magnetizing inductance
• Leakage inductance
• Coupling
• Air gap where applicable
• Winding arrangement
• Parasitic capacitance
• EMI considerations

The magnetic structure must ultimately work with the switching circuit.

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