How to Choose Magnetic Components for High Power Supplies?

ElecSuppliers Electronics GuideAug 12, 2026

Magnetic components are essential in high power supply systems. Transformers provide isolation and voltage conversion, while inductors store energy, control current and reduce ripple. Chokes and other magnetic components are also used for EMI filtering.

As power levels increase, selecting these components becomes more difficult. Higher current creates greater copper losses, while higher switching frequencies can increase core and winding losses. The magnetic components therefore need to be selected according to the complete power supply design.

Identify the Magnetic Components You Need

Start by identifying the role of each magnetic component in the power supply.

Common types include:

High frequency transformers

Power inductors

Output inductors

Common mode chokes

Differential mode inductors

EMI filter inductors

The requirements are different for each type. A transformer designed for isolation cannot simply be replaced by a standard power inductor, even if their physical sizes are similar.

Check the Power Rating

The first consideration is the power that the magnetic component needs to handle.

Higher power normally means higher current, greater stored energy or a larger magnetic core.

For a transformer, check the required transferred power. For an inductor, consider both continuous current and peak current.

The component should have enough capacity for the maximum operating condition rather than only the normal load.

Consider Operating Frequency

Switching frequency has a major effect on magnetic component selection.

At higher frequencies, magnetic components can often be made smaller. However, core losses and AC winding losses can also increase.

The core material, number of turns and winding structure should therefore be selected for the actual operating frequency.

This is particularly important in high-frequency switching power supplies and GaN-based power conversion systems.

Choose the Right Core Material

Core material affects inductance, saturation and power loss.

Ferrite materials are widely used in high-frequency transformers and inductors. Other magnetic materials may be more suitable for certain high-current or energy-storage applications.

The material should be evaluated according to frequency, flux density, temperature and required energy storage.

Choosing a core based only on its physical dimensions can lead to poor performance.

Check Saturation Characteristics

Saturation is especially important for power inductors.

When the magnetic core approaches saturation, inductance can decrease significantly. This can cause current to increase rapidly and may place additional stress on switching devices.

For high-current applications, check the inductance-versus-current characteristics rather than relying only on the nominal inductance value.

Consider DC Resistance

Winding resistance contributes to copper losses.

At high current, even a relatively small resistance can produce significant heat.

For power inductors and transformer windings, a lower DCR can improve efficiency and reduce temperature rise.

However, reducing resistance may require larger conductors, more copper or a larger winding area.

Consider High Frequency Winding Losses

DC resistance is not the only winding loss.

At high frequencies, skin effect and proximity effect can increase the effective AC resistance of the conductor.

This is why high-frequency transformers may use techniques such as multiple parallel wires, litz wire or copper foil depending on the application.

The winding structure should match the frequency and current waveform of the power supply.

Check Transformer Parameters

For high-power switching supplies, the transformer should be evaluated using more than the turns ratio.

Important parameters can include:

Magnetizing inductance

Leakage inductance

Winding resistance

Turns ratio

Insulation

Core loss

Temperature rise

These parameters can directly affect the operation and efficiency of the converter.

Consider Thermal Performance

Heat is one of the main challenges in high-power magnetic components.

Core losses and winding losses both generate heat.

The component needs to remain within its permitted temperature range during continuous operation.

When selecting a magnetic component, consider the actual airflow, heatsink arrangement, enclosure and surrounding components rather than relying only on laboratory conditions.

Consider Power Density

High-power equipment increasingly requires more power from a smaller physical volume.

A magnetic component with high power density can help reduce the overall size of the power supply.

However, increasing power density can also increase thermal stress.

The design therefore needs to balance size, efficiency, current capacity and temperature rise.

Check Insulation Requirements

Transformers used for isolated power supplies need an appropriate insulation system.

Important considerations include insulation material, creepage distance, clearance and withstand voltage.

The required insulation depends on the input voltage, output voltage and application.

For EV chargers, industrial power supplies and other high-voltage equipment, insulation should be considered from the beginning of the transformer design.

Consider EMI Performance

High-power switching circuits can generate significant electromagnetic interference.

Common mode chokes and differential mode inductors are often used to reduce conducted EMI.

Transformer construction can also influence EMI through leakage inductance and parasitic capacitance.

Magnetic component selection should therefore be part of the overall EMI design rather than treated as a separate issue.

Consider the Converter Topology

The appropriate magnetic component depends on the power supply topology.

For example, different transformer requirements apply to:

Flyback converters

Forward converters

Half-bridge converters

Full-bridge converters

LLC resonant converters

Dual-active-bridge converters

The same transformer specification may not work properly across different topologies.

The magnetic design should be developed around the voltage and current waveforms generated by the converter.

Evaluate Efficiency

High-power power supplies can operate continuously, so magnetic losses can have a significant effect on total energy consumption.

Both core loss and winding loss should be considered.

A component with a slightly higher purchase price may be worthwhile if it significantly reduces power losses during long-term operation.

This is particularly relevant to data centers, EV charging equipment, solar inverters and energy storage systems.

Check Current Capacity

High-power inductors and transformers may carry substantial current.

The conductor size, winding structure and thermal design need to support the expected current.

Do not select a component only according to its nominal inductance or voltage rating.

Continuous current, peak current and temperature rise should all be evaluated.

Consider Custom Magnetic Components

Standard components may not provide the required combination of power, frequency, size and efficiency.

A custom transformer or inductor can be designed around the actual power supply.

The manufacturer can adjust the:

Core material

Core size

Air gap

Number of turns

Winding structure

Conductor size

Insulation system

Leakage inductance

Magnetizing inductance

This can be useful for high-power and high-density applications.

Test Magnetic Components Under Real Conditions

Prototype testing should be performed before mass production.

Important measurements may include:

Inductance

DCR

Saturation current

Core temperature

Winding temperature

Leakage inductance

Magnetizing inductance

Insulation resistance

Withstand voltage

The component should also be tested inside the actual power supply because the operating waveform and surrounding components can affect its performance.

Choose a Magnetic Component Supplier

When selecting a supplier, look at more than manufacturing capacity.

Check the supplier's experience with high-power applications, core materials, winding technology and testing equipment.

For custom components, engineering support is particularly important.

A capable supplier should be able to understand the power supply topology and electrical requirements before recommending a transformer or inductor.

Magnetic Components for Modern Power Supplies

High-power applications such as AI servers, data centers, EV chargers, solar inverters, energy storage systems and industrial power supplies are placing greater demands on magnetic components.

Higher power density and switching frequency make core selection, winding design, thermal management and EMI performance increasingly important.

The right magnetic component should therefore be selected as part of the complete power supply design, with efficiency, reliability, size and operating conditions considered together.