Designing for Efficiency
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2.1 Operating Principle
In a push-pull converter, two MOSFETs alternately energize opposite halves of a center-tapped transformer primary. Each
switching interval transfers energy to the secondary while the following half-cycle resets the core.
Magnetic flux swing is governed by Faraday's law:
For rectangular excitation:
This relationship shows that increasing voltage or on-time increases flux excursion. Designers choose turns and timing to
keep the core safely below saturation.
Push-pull converters rely on symmetry. If one switch applies slightly more volt-seconds than the other,
an incremental flux bias is introduced:
Over time this bias increases magnetizing current and switching stress. Careful timing symmetry minimizes this effect.
These operating principles directly describe the switching behavior of the reference converter shown in Figure 1.
2.2 Device Configurations
Two otherwise identical schematics isolate semiconductor behavior.
Silicon implementation
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MOSFET: IRFP27N60K
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Diode: 1N1190
Silicon carbide implementation
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MOSFET: SCT4045DE
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Diode: STPSC20065W
All passive components and operating conditions remain unchanged.
