Patent ID: 6147465
Filing Date: 2000-11-14
Classification: H02P

Abstract:
A motor powered by a dc power source comprising:a stator having a single phase winding;a power switching circuit having power switches for selectively connecting the dc power source to the single phase winding;a permanent magnet rotor in magnetic coupling relation to the stator;a position sensor on the stator for detecting the position of the rotor and providing a position signal indicating the detected position; anda control circuit including a microprocessor responsive to the position signal and connected to the power switching circuit for selectively commutating the power switches to commutate the single phase winding as a function of the position signal;wherein a resonance will occur during operation of the motor within a predetermined range of rotational speeds of the permanent magnet rotor causing increased vibration and/or increased audio noise; andwherein the control circuit is programmed to operate the motor to selectively avoid the predetermined range of rotational speeds at which the resonance occurs.