How do you deal with noise from a motor in a circuit?

Question

Hello,

We have an electric motor in a circuit and up to 2000rpm the circuit works very well, but if we increase the speed of the motor to more than 2000rpm, the circuit becomes instable just like for over 2000rpm the motor generates a noise or interference with the rest of the circuit.

Is there anyway to get the motor running at higher speeds and avoid these noises/interferences?

Thanks

Answer 1

Look at figure 6 of this article: http://eprints.qut.edu.au/archive/00006772/01/6772.pdf
But in order to properly investigate the origin and kind of noise the motor generates, you would need an oscilloscope.

Answer 2

use a tank circuit or other low pass filter to isolate the control parts of the circuit from the motor field current - I assume you are using a dc motor to get the variable output, typically there is a lot of brush noise (making and breaking the field current as the brushes move) - a low pass filter from the load current side into your speed control circuit should help...

Answer 3

run the motor on a separate run of the supply rails and 0volts

add 100nF across the rails of your circuit
(or even some large electrolytics 470uF)

and insert RF filters in the leads going to the motor
(bifilar inductor and 2 capacitors or 2 C's and one or two L's

but it could be that your power supply is collapsing with the increasing power demand

or your circuitry is unstable and the current spikes at the right frequency make it oscillate

Answer 4

Any answer to that question without seeing the control circuit schematic is nothing but a guess.

Also you have not stated the type of motor.

How do you know that noise is the problem? Are you just guessing?

Answer 5

i guess the first thing to do is to measure the vibration spectrum of this noise using a transducer,,inorder to figure out from where exactly does it come from the motor,,,after specifying the location ,,,u can solve this problem by checking whats wrong in that location maybe something's hanging or anything like that but u ve to analyze that noise before doing anything

Answer 6

Earplugs

Answer 7

You can use capicitors to decouple the "noise"...

This should help you figure out how:

http://www.allaboutcircuits.com/vol_6/chpt_4/16.html