System for controlling the in-phase operation of a pair of motors

摘要

The operation of a first motor and a second motor generates first and second frequency signals, respectively, which are fed to a phase lock loop (59) for phase comparison. A tri-level detection circuit (61) develops an output signal in response to the phase relationship between the first and second frequency signals. The first frequency signal is converted to a voltage signal by a converter (63) which is fed to an amplifier (64). A feedback circuit (66) is connected across the amplifier and includes several selectable levels of impedance. A switching network (62) responds to the output signal of the detection circuit (61), and thereby in response to the phase relationship between the first and second frequency signals, to connect one of the impedance levels of the feedback circuit (66) across the amplifier circuit (64). The amplified voltage signal is fed to a controller within a motor drive (72) for the second motor to control the speed of the second motor and insure in-phase operation thereof with the first motor.