Magnetics: The Eternal Battle with Myths, Mysteries and Black Magic – or Maybe Really all Just a Matter of Basic Principles and Physics?


Alexander Gerfer, CTO at Würth Elektronik eiSos

Alexander Gerfer

Is magnetism an esoteric science of the 18th century or perhaps even black magic?
Are magnetics really a closed book for the user?
Or EMC ferrites an unknown entity? 

We observe that the majority of engineers, including our own junior engineers, are not well trained in the basics. Much is omitted in training and higher education, but it already starting in high school. A classic example, Pythagoras' theorem, is no longer included in many curricula. It appears as though this is simply too trivial? Yet, without a foundation of well understood (!) basic knowledge, only superficial knowledge proliferates, or in the worst case, ignorance is not overcome. 

This example demonstrates exactly where the problem lies with magnetics too. Regardless of which country’s college and university curriculum you look at, EMC (Electromagnetic Compliance) and inductive components are often just side topics. In addition, the basic knowledge taught is not only diluted, but often outdated. Today’s inductive components are based on the same physical principles – but the diversity of core materials has expanded rapidly; they work in quite different frequency ranges and in many other application areas than those described in the text books as “in practice”. For instance, Dr. Ray Ridley impressively described at APEC2016 that students could not even recognize a transformer on a photo, but they could certainly identify the robotic comic figure, “Bumble Bee”, as a “Transformer” on another photo!

Competitiveness in the market depends on companies being in a position to achieve a fast time-to-market. Whoever is faster to the market with their solution has a decisive influence on prices and market shares. Competitiveness also depends on whether this solution is achieved without interference emission and with interference immunity, whether it is efficient and of highly durable and reliable quality!

Speed to market is compromised if the basic principles on the origins of interference are not understood and then the devices have to be made EMC compliant in laborious EMC tests and redesigns. Inductive components are blamed for lack of efficiency in power supplies in over 60% of cases. However, going into more detail reveals that much would have been resolved by choosing the right topology, correct component selection and understanding, e.g. of current density and the associated limit of miniaturization. Service life depends largely in whether the design stays cool. High operating temperatures are a curse for all electronics!

So we can only hope that the young engineers actively keep abreast of their continuing education. Not only based on Wikipedia, but also in the numerous good seminars offered by the manufacturers. 
We at Würth Elektronik eiSos have offered handbooks for many years and we provide enlightenment on this subject in seminars. But how was it in Kant’s famous definition, “Enlightenment is man's emergence from his self-incurred immaturity.” I can only appeal: Keep on learning! Don’t be scared by black magic, demystify EMC and inductive components! 

Source: Bodo's Power Systems, November 2016