Spindle motor control system
 A control system for a brushless direct current motor providing linear closed loop speed control when the motor is operating near its desired speed and providing pulse width modulation closed loop speed control when the motor is not operating near its desired speed. A current sensing feedback loop is provided to drive the transistor linearly controlling the electronic commutation of the motor into pulse width modulation when the current through the motor exceeds a predetermined value. An inductor may be coupled in series with control transistor and positive feedback may be supplied to the current sensor. 
Minnesota Mining and Manufacturing Company
G H
G11B H02P
inventional inventional
Martyn A.
Lewis