Possible magnetic electricity problem

jjae6

Mechanics is also important. Each motor will support  an acceleration and maximum speed type depending on the motor size and type and connected mechanics.
If the problem is mechanical, try first the motor engine with nothing connected: spindle, pulleys, etc, etc.

Edited:  Oh, reading your question I've realized that it can be an electrical problem derived from the inverter or power supply that makes interferences. Try removing those items from the main box and installing them outside.