Automatically synchronized synchronous motor drive system

摘要

In a current-fed static controlled synchronous motor drive which includes a ramp logic for establishing the desired firing retardation for the naturally commutated thyristors, an optical encoder provides a position signal and a velocity signal, while the ramp counting the velocity pulses is automatically aligned with the position signal by means of a phase detector causing either to add pulses from a local oscillator or to inhibit velocity pulses so as to compensate for a phase error in either direction. Alignment is also provided within 60 DEG initially by presetting the ramp counting in relation to a digital representation of sine 60 DEG time intervals over a fundamental cycle.