Lowe, Price, LeBlanc & Becker
Brushless motor speed control arrangement having derived common mode supply signal component
 A method and apparatus for increasing the top speed of a brushless DC motor (BLDCM) or a closed loop step motor (CLSM) which are driven by substantially sinusoidal signals on each of its leads. Art additional signal is generated which has a fundamental frequency component at a harmonic of the frequency of the main sine wave signals applied to the motor leads. The additional signal is added to the normally applied signal on each motor lead. The amplitude and phase of the additional signal are chosen to increase the top speed of the motor, or alternatively, to reduce the supply voltage needed for a given speed. 
Seagate Technology, Inc.
H H
H02P H02P
inventional inventional
Martyn A.
Lewis