Patent ID: 6196650
Filing Date: 2001-03-06
Classification: H02P

Abstract:
A sensorless motor driving circuit, for driving a motor having a rotor and a plurality of excitation coils for the rotor, comprising:detection means for detecting a reference position for the rotating rotor based on an excitation coil induction voltage;differential pulse generating means, coupled to an output of said detection means, for generating a differential pulse using a detection means output signal;a phase-locked loop circuit for generating a clock pulse, having a phase comparator for comparing the differential pulse with the clock pulse after the clock pulse has been frequency divided;an activation pulse generator for counting the clock pulses and generating an activation pulse when the differential pulse is not generated within the duration of a prescribed number of counts;a latch circuit for generating a delayed pulse delayed by a prescribed amount from the reference position of the rotor by counting the clock pulses or by using the activation pulse;a generating circuit for generating conduction switching signals for the excitation coils based on the delayed pulse; anda driver circuit for bringing about conduction in the excitation coils based on said conduction switching signals.