Reducing Speed Ripples and Vibrations in Permanent Magnet Synchronous Motors with Unbalanced Loads

Permanent Magnet Synchronous Motors (PMSM) have important features such as high torque, high power density, high acceleration, small volume, low noise and high efficiency. With these features, is widely used in the industry. One of the negativities that occur during the operation of electric motors is speed fluctuations and vibrations due to the unbalanced loads. Unbalanced loading can be caused by the character of the load, as well as the poor mounting of the motor to the load, the misalignment on the shaft and the load itself being an eccentric load. Especially at high speeds, this causes permanent damage to the motors. Specification and elimination of these fluctuations, which occur for different reasons, are very important for a reliable operation. In this study, unbalanced load situations are investigated in an unbalanced PMSM and the speed ripples in the unbalanced load of the motor are attempted to be decreased by the proposed Adaptive Harmonic Injection approach. The simulation is carried out under various operating conditions by abruptly and linearly changing the motor speed under unbalanced load. It is observed that speed fluctuations in the motor can be effectively suppressed under different operating condition.