Patent ID: 7282876

Claim:
A brushless DC motor drive system comprising: a) a pole-position detector for detecting respective pole positions of permanent magnets of a rotor of a brushless DC motor; b) a present speed computing means for computing present speed of said brushless DC motor on the basis of an output signal from said pole-position detector; c) a speed differential computing means for computing a differential speed between a speed command and said present speed; d) an energization start time computing means for computing an energization start time in a present instance on the basis of an energization start time in a preceding instance and said speed differential; e) an energization start instruction means for instructing an energization start upon the elapse of said energization start time in the present instance from a phase changeover point in time; f) an energization completion time computing means for computing an energization completion time by subtracting said energization start time in the present instance from a preceding pulse time; and g) an energization completion instruction means for instructing energization completion upon the elapse of said energization completion time from said phase changeover point in time.