inverter whine

[richerdick]

I am looking at a three phase inverter driven motor 7.5kw that is reported to be whining more than usual. i can hear a whine that sounds specifically like a standard inverter motor whine. However can think of no reason why the whining would have got worse. Have inspected the connections and tested the motor with a megger and all looks ok. There is an inline contactor between drive output and motor and contacts measure ok with a multimeter. other than the noise there is no other reason to quetion the motor/ drive.
I have no reason to susupect that the switching frequency would have changed
any ideas?

 

[itsmoked]

Yes. A mechanical reason. If some mechanical change has occurred. Like the bolts have gotten loose holding the motor down. Shaft coupling has worn out. The driven load has changed in the same manner. All these things could cause sound-boarding where the sound is now better coupled to the air. Hence louder.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[boaterbill]

If the windings of the motor are starting to fail the carrier frequency whine can increase. Also if there is stray currents through the bearings it can make the motor sound louder.

I would change the carrier freq and see if the problem noise follows suit.

 

[Skogsgurra]

I have had resonance in the cover for the motor connection box. Tightening or loosening the bolts may change the sound. Nothing to worry about. Tightening the bolts is usually best.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[sreid]

To hear audable noise, something has to be moving and usually the resonance frequency is the same as the PWM frequency. Changing the PWM frequency may make the noise go away.

One source of increasing noise is loose stator laminations.

 

[ozmosis]

Changing the PWM frequency may identify the source of the noise but a lot of drives need de-rating, or will automatically derate their output current if you increase the PWM switching frequency. So just be mindful of this if the load is high at present. Higher switching frequency (PWM) will increase the heat output of the drive and possibly increase RFI (Radio Frequency Interference).