A low noise slotless parametric motor suited for use in quiet environment

The causes of acoustic noise generation and the capability of acoustic noise reduction of a slotless parametric motor have been investigated, and are compared with those of an ordinary motor. It was clarified that the acoustic noise of the parametric motor is lower than that of an ordinary motor, because the parametric motor has no slot and no tooth. When the motors are operated by a source with high-frequency components such as a square wave, the increment of the acoustic noise of the parametric motor is smaller than that of an ordinary motor. The parametric motor is suited for use in a quiet environment. The acoustic noise of the parametric motor is mainly generated by the clattering, and may be reduced by using 6.5%Si-Fe plates for the cores of the motor. The acoustic noise of the parametric motor can be reduced more by pressing a rotor shaft into the ball bearing, performing the varnish impregnation of windings, and enclosing the components of the motor by a frame