EMI Filters for Motor Drive Applications


In Variable Frequency Drives (VFD), the input rectifier stage that rectifies the incoming AC power into DC power is largely prone to EMI. The non-sinusoidal current from the power supply creates current harmonics on the power supply and subsequent voltage distortion.


Modern VFDs using IGBT switches for motor frequency control are prone to much higher EMI being generated because of high frequency transistor switching. High dV/dt rates at the motor attached to the VFD result in radiated electric fields and voltage spikes conducted along the motor cabling.

These emissions can be conducted to other electrical equipment connected to the utility. EMI VFD problems range from corrupted data transmission to electric motor drive damage.

EMI Filters are a mandatory prerequisite to obtain certifications such as CE Marking for VFD exports to European and other international markets.

EMIS offers

Single Phase EMI Filters

High attenuation, compact size. Available also with shock proof terminals.

  • Power line filters
  • Surge Suppressors
  • Filters for dV / dt voltage spikes

3 Phase filters

General purpose, cost effective filters. High performance with shock proof terminals.

  • Conventional type
  • Book shelf design
  • Foot Print Design
  • Bus bar type
  • Panel mount

AC Line Reactors

Used at input side of power system to provide input impedance. Helps to reduce harmonic distortion and increase VFD component lifetime, limit the flow of electrical current in transient, short circuit currents, attenuate line spikes and surge currents.

  • Single phase and three phase Line Reactors with 2-5% impedance for various power quality applications
  • Consisting of steel core electrical grade laminations and copper wound coils.
  • Designed corresponding to EN 61558-2-20, EN 60076-6, UL61800-5-1 specifications.
  • Full compliance with Industry Standards such as CE Marking.

Other solutions

for EMI noise suppression in drives include

  • Shielded power cables
  • Output Ferrite Chokes
  • Comprehensive Grounding and coupling solutions
See our full range of EMI/EMC products
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