×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

VVVF Drive Electrical Noise

VVVF Drive Electrical Noise

VVVF Drive Electrical Noise

(OP)
Hi,

can a VVVF drive radiate noise back onto the mains line?
What are the typical frequencies that are emitted?
If not into the mains, where else can this noise be radiated?

Cheers,

Vudu

RE: VVVF Drive Electrical Noise

Contamination of the power lines has been a problem developed by VFDs; harmonic currents are the result of non-sinusoidal current, which is characteristic of diodes or SCRs.
Some of the problems that could arise are:
Communications interference, overheating of transformers, increased heating of motor lamination and conductors, resonance with power capacitors.
 The magnitude and frequency of harmonics changes from system to system, then a specific analysis or measurement should be conducted for each application.
To reduce these negative effects, several techniques have been developed, such as: DC Link choke/inductor, line reactors, drive isolation transformers, multipulse method converters, harmonic filters, etc.

RE: VVVF Drive Electrical Noise

Hello Vudu

Yes, VVVF do create many frequencies which radiate from the motor, the cable between the inverter and the motor, the inverter itself, and the incoming supply lines.
The input circuit of the inverter is a rectifier which converts the AC current into DC current. This generates low frequency harmonic currents in the supply. These harmonics can be reduced by the use of DC Bus chokes and AC line reactors.
The output stage of the inverter comprises 6 switching elements that are operated at a high speed following a form of PWM pattern to regenerate the three phase current to the motor. These switching elements are FETs on low voltage low current inverters, and IGBTs on higher voltage (400 - 600) higher current inverters.
The switching time of these switching elements is very fast (much less than 1 uS) and this results in considerable high frequency energy which is difficult to filter completely.
Most VVVF manufacturers can supply/recomend filters to reduce this interference and there are regulations (EMC) in many parts of the world now covering the acceptable levels of electromagnetic interference from these devices.

The use of AC line reactors, DC Bus chokes and output filters all help to reduce the level of interference.

Best regards,

Mark Empson
http://www.lmphotonics.com

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources