The new edition of the RECOM DC/DC Book of Knowledge has been released, with an additional chapter on magnetics. More than 1,000 online copies have been downloaded by engineers worldwide, in the first few weeks. This shows how valuable this source of in-depth practical power design information is to the power supply community. The author, Steve Roberts, says: “I am overwhelmed to hear that the new book of knowledge has been so well accepted in the industrial and educational communities. This makes all the hard work in writing the additional chapter worthwhile.”
recom-bookThe new edition features an additional chapter on magnetics to cover the fundamentals of inductors and transformers. The chapter begins with terminology, core saturation, air-gapped inductors, core geometry, core losses, the skin effect and proximity effect. Worked examples of buck and boost DC/DC converter designs show how to correctly dimension the magnetic components and how to calculate the losses in the magnetic core and switching elements. The section continues with DC/DC transformer design, showing how to specify Royer push-pull, forward and flyback transformers – again with worked examples to demonstrate how to calculate the dimensions, turn ratios, losses and duty cycle limits for these topologies. For flyback transformers, the gap length and bobbin dimension calculations are also explained. The effects of leakage flux, leakage inductance and leakage capacitance are discussed and winding techniques to reduce these effects are explored. The chapter concludes with a short discussion on designing for low EMI and adequate internal core temperature safety margins.
While a single chapter cannot cover all aspects of inductor and transformer component design, it offers a useful introduction to the fundamentals of magnetics and the worked examples show how the theory can be put into practice.
Since the original publication in December 2014, more than 15,000 copies of the RECOM DC/DC Book of Knowledge have been distributed globally. Hard copies can be bought at Digi-Key and Chip1Stop. Free PDF versions are available in English, German, Chinese and Japanese at www.recom-power.com/bok

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