Abstract: Information indicative of the placement of spindle motor components may be obtained and used to provide a correction to one or more BEMF-derived attributes used to control the spindle speed. In some implementations, first and second signals indicative of BEMF of different stator windings may be used to determine a speed-related characteristic. The speed related characteristic may be used to determine an error amount, which may be used to determine a correction factor to control the speed of the spindle motor.

Abstract: Information indicative of the placement of spindle motor components may be obtained and used to provide a correction to one or more BEMF-derived attributes used to control the spindle speed. In some implementations, first and second signals indicative of BEMF of different stator windings may be used to determine a speed-related characteristic. The speed related characteristic may be used to determine an error amount, which may be used to determine a correction factor to control the speed of the spindle motor.

Abstract: A processor for controlling a sensorless, brushless DC motor is disclosed comprising a first output for providing a control signal to a potentiometer controlling the speed and voltage of the DC motor. The processor also includes a second input for receiving a back-EMF voltage from an open phase of a three phase winding. The processor determines a digital error signal from the back-EMF voltage and generates a control signal responsive to the digital error signal. The control signal decreases the speed of the motor when the digital error signal is in a first range. The processor decreases both the speed and voltage of the motor when the digital error signal is in a second range. The processor increases the speed of the motor when the digital error signal is in a third range. The processor increases both the speed and voltage of the motor when the digital error signal is in a fourth range.

Abstract: A method and apparatus for operating a polyphase dc motor selectively in dual-coil or uni-coil commutation modes. The motor has a plurality of "Y" connected driving coils connected together at a center tap. Each driving coil has an input node at an end opposite the center tap, and is driven by a switch pair. Each switch pair is arranged for connection in series across a power supply voltage, and has a node between each switch connected to a respective one of the coil input nodes. An additional pair of switches are provided for connection in series across the power supply with a connection node between each switch connected to the center tap. A circuit is provided to operate the switches to cause a driving current to be passed between sequentially selected pairs of the driving coils for an initial start-up time.