Presented by: Will Lockhart 12/19/03

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Presented by Will Lockhart 12/19/03
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What does the Flyback Converter need from the
transformer ?
? Energy Storage ? Electrical Isolation ? Current
Limiting Inductance ? Support Considerable DC
Component
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ac change on input ? causes ? Bac in core ?
causes ? Hac DC on input ? causes HDC in core ?
causes BDC
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Calculation method of transformer design has a
number of approximations that must be initially
made
? Core Size ? On Time of Circuit ? Minimum DC
Input ? Working Flux Density Swing
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Nomogram for Core Material
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Flux Density Saturation Vs. Temperature
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Start Calculating
? Number of Turns on Primary ? Number of Turns on
Main Secondary ? Readjust Earlier
Approximations ? Number of Turns on Any Other
Secondary
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Core Air Gap
Affects Primary Inductance
Affects Current Waveforms
Affects Stress on Components
Affects Flux Retention,
Br Affects Working Range of
Flux Density, ?Bac And
Effect of DC generated Flux
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Check Saturation
? By Measurement ? By Calculation
Bac BDC Bmax lt Bsat
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Another Way to Design ? PExpert
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A Selection of Options---------Quickly
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Core and Material Data is Readily Available
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In Conclusion
? I learned that there is a lot of variation in
transformer design and the transformers
intended application is more critical than I
realized ? PExpert can be much faster for
designing and trying variations ? Even with
fancy programming tools or cookbook recipes you
still have to understand what you are doing