Through advanced simulation tools and innovative design techniques, this collaboration achieved compact, high-efficiency solutions tailored for the demanding automotive sector.

Challenge

Optimizing Series Inductance Across Multiple Frequencies in DAB Converters

The primary challenge involved controlling the series inductance, which varied significantly with the operating frequency in a DAB Converter. Different techniques were applied to optimize efficiency at various frequencies:

• Selecting appropriate materials and wires for each frequency.
• Reducing losses under diverse operating conditions.

Solution

Innovative Approaches for High-Frequency Transformer Design

To meet the requirement for the highest leakage inductance value in the 100 kHz design, a "mergence" approach was adopted, combining the transformer and an external inductor in a single structure to reach the desired value. For the 250 kHz and 500 kHz designs, the transformer's inherent leakage inductance was exploited by altering the winding configuration and incorporating ferrite shunts.

• For the 100 kHz design, a "mergence" approach was adopted, combining the transformer with an external inductor to achieve the desired leakage inductance.
• For the 250 kHz and 500 kHz designs, winding configurations and ferrite shunts were optimized to utilize inherent leakage inductance effectively.

Key Points:

• Integrated Leakage Inductance.
• Use of High-Frequency Ferrite Material.

Results

Compact, High-Efficiency Design for Automotive Onboard Chargers

The collaboration between ST France and Frenetic resulted in:

The relationship between frequency and magnetic component size reduction is not always linear. Moreover, overall converter efficiency must be considered, as high-frequency operation leads to increased semiconductor switching losses. By combining ST's low-loss semiconductor technologies with Frenetic’ s transformer design expertise, a compact solution with nearly 98% efficiency is achieved.

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