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.