BRUSHLESS MOTOR DRIVE SYSTEM

PURPOSE:To regulate the phase of driving current electrically to a predetermined amount by obtaining a sine wave and a cosine wave from two position detecting elements and then adding/subtracting one of them to/from the other with same ratio through an amplifier. CONSTITUTION:A variable gain amplifier 52c multiplies a 90 deg. leading position detection signal C by K to produce a signal KC which is then added to a position signal S in an adder/subtractor 52a thus producing a position detection signal +Ss having phase lead alpha ahead S. A variable gain amplifier 52d multiplies a 90 deg. phase leading position detection signal -S by K to produce a signal -KS which is then added to the position detection signal C in an adder/subtractor 52b thus producing a position detection signal +Cs having phase lead alpha ahead S. The adder/subtractor then adds the signals +Ss, +Cs and their inverted signals -Ss, -Cs, while weighing according to a resistance ratio, thus combining the timing signal.