The open torque is little and the valve can self compensate after wearing because of big chocking force. The seal performance is good and stable.

For the BLDCM which has a sinusoidal back EMF, this paper presents a self-synchronous SVPWM control method using six discrete position signals for minimizing torque ripple.

Through decoupling control of the torque windings and suspending force windings, the rotor of motor simultaneously have functions of producing torque and self-suspension.