EMC design of Switching Power Converters - Part 1

Switch-mode and pulse-width modulated (PWM) power converter technologies are very electromagneticallynoisy – they naturally emit high levels of unintentional EM disturbances.

In fact, these technologies are so noisy that unless good EMC design/construction practices are used, theyalmost inevitably fail any emissions tests, often by a large margin.

Switch-mode and PWM converters with basic switching rates below 150kHz almost always fail conductedemissions tests quite badly, and lower-power ones with small devices that switch power very quickly can failradiated emissions tests too. Those with basic switching rates above 150kHz almost always fail radiatedemissions tests, often quite badly.

So, to legally sell or use products, vehicles or systems, or construct or operate installations, in almost everycountry in the world whilst legally complying with their EMI Regulations (e.g. the EMC Directive,2004/108/EC in Europe) to protect radiocommunications, the designers of switch-mode and PWM powerconverters always have to employ EMC design techniques.

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