A low noise slotless parametric motor being much suited for the uses of quiet environment

In many places such as hospitals, offices, homes etc., the quiet environment has been required, and the reduction of acoustic noise which is mainly originated from a motor is desired. In the ordinary motor, the higher harmonics of the induced mmfs caused by the slots and teeth give rise to the harmonic distortion such as vibration, electromagnetic noise, rotating fluctuation etc.. The parametric motor has no slot and no tooth in a stator, therefore the noise parametric motor is expected to be lower than that of an ordinary motor. This report provides a comparative study of the acoustic noise of a parametric motor and an ordinary motor.