Control of mechanical vibrations in DC machines

A method of reducing mechanical vibrations generated in a DC machine is presented. The method consists of an addition of ampere turns to the usual excitation and armature currents. Extra coils have been wound on the main excitation poles and when properly supplied, the vibration level at different points on the outer surface of the motor is significantly reduced. It appears that for a given frequency, the rate of reduction may be as high as 30 dB without modifying other frequencies.<
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