Explain The Different EMI Terminology


Explain The Different EMI Terminology

EMI Mitigation

Explain the different EMI terminology.

1. Shielding

To manage the emission, shielding is applied at the supply or at the affected device.

Shielding the damaged the device , needs  nonstop metal covering around the piece of
Equipment  which allows the EMI  close to the shield but not inside the shield.

As soon as EMI attacks the shield, eddy current is injected into the shield.

High conductivity material like copper and aluminium are used for shielding.

The shielding depends on the thickness which has larger strength, matching to the EMl frequency.

                             ( Figure)

2. Filters

They are used to reduce the attenuation of conducted emission.

Filter do not remove entire attenuation, but they reduce the level of that can be beared by the sensitive devices.

Passive filters are generally used to filter the particular frequency band.

For other frequency bands, multi band filters can be employed.

Before applying the filters, it is essential to find out the choice of offending frequencies.

Occasionally filters may be applied in series to obtain higher attenuation.

3.  Device Location

As seen earlier, electrical and magnetic fields vanish as if the distance of the signal and
wire increases.

Attenuation can be reduced to great extent, if the damaged device is removed from the EMI source.

The area should be minimum, to have low noise pickups.

4. Snubber

For mitigating EMI interference, dil/dt and dv/dt should be reduced.

Though noises are decreased, it increase the parasitic involvement in EMI.

5.  Soft Switching

The soft switching with IGBT, MOSFET and diode as a switching component is able to
reduce the EMI with low di/dt and dv/dt.

With low resonance produced in switching, EMI can be suppressed greatly.

6. Parasitic Cancellation

EMI can be controlled by reducing the usage of generating sources.

This can be accomplished by deletion of the parasitic effects which add to EMI generation and discharge in the circuit.

7. Interleaving

Interleaving is an analogous approach in which multi switching devices are coupled with an equal switching frequency.

It produces lower current ripples and red
Reduces the EMI effects.

8.  Compensation

The idea behind this is to produce a noise badly.

This is primarily focused on common mode EMI and compensation is realized by sinking the earth current.

9. Grounding

An appropriate grounding is the cost effective and one of the most common methods to
mitigate EMI in a device.

The radius of a grounding conductor is not that important. For EMI mitigation, area of the conductor is the other significant aspect since high frequency EMI moves on the surface of conductors than inside the conductor.

10. Enclosure

For EMI mitigation, enclosure should be made up of magnetic steel.

Separate enclosure for incoming and outgoing power and mitigate EMI more effectively.

EMI gaskets can be used for eliminating noise. 

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