Editing Electromagnetic interference
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Electromagnetic interference a.k.a. '''EMI''' (also called radio-frequency interference or '''RFI''') is disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation emitted from an external source. The disturbance may interrupt, obstruct, or otherwise degrade or limit the effective performance of the circuit. These effects can range from a simple degradation of data to a total loss of data.[2] The source may be any object, artificial or natural, that carries rapidly changing electrical currents, such as an electrical circuit, the Sun or the Northern Lights. [http://en.wikipedia.org/wiki/Electromagnetic_interference] | Electromagnetic interference a.k.a. '''EMI''' (also called radio-frequency interference or '''RFI''') is disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation emitted from an external source. The disturbance may interrupt, obstruct, or otherwise degrade or limit the effective performance of the circuit. These effects can range from a simple degradation of data to a total loss of data.[2] The source may be any object, artificial or natural, that carries rapidly changing electrical currents, such as an electrical circuit, the Sun or the Northern Lights. [http://en.wikipedia.org/wiki/Electromagnetic_interference] | ||
See more at Wikipedia: http://en.wikipedia.org/wiki/Electromagnetic_interference | See more at Wikipedia: http://en.wikipedia.org/wiki/Electromagnetic_interference | ||
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==Coupling methods== | ==Coupling methods== | ||
Most common methods of EMI transfer from source to victim are: | Most common methods of EMI transfer from source to victim are: | ||
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*Magnetic coupling | *Magnetic coupling | ||
*Capacitive coupling | *Capacitive coupling | ||
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===Capacitive coupling in motor control=== | ===Capacitive coupling in motor control=== | ||
In motor control applications capacitive coupling is the most common cause for EMI problems. Capacitive coupling occurs when unshielded conductors are in each other's proximity and source conductor is carrying voltage signal with high slew rate (dv/dt). Example of such source is the motor leads carrying high voltage [[PWM]] signal. | In motor control applications capacitive coupling is the most common cause for EMI problems. Capacitive coupling occurs when unshielded conductors are in each other's proximity and source conductor is carrying voltage signal with high slew rate (dv/dt). Example of such source is the motor leads carrying high voltage [[PWM]] signal. | ||
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| − | + | The most effective methods of suppressing this noise are: | |
| − | [[ | + | *Use shielded conductor and tie cable shield to stable voltage potential such as earth. Cable shield provides Faraday's cage that attenuates capacitive coupling outside the shield. |
| − | + | *Use [[EMI suppression cores]] near the EMI source. | |
