Variable speed drive with shunt-wound AC motor - has speed-torque characteristics quickly altered by thyristor

摘要

The variable speed drive contains a shunt-wound ac motor with a brush adjusting device and an extra device to alter speed/torque characteristics. The extra device consists of a thyristor (or similar) (7) connected into the motor secondary circuit and switching resistors (18) in and out. The control signals applied to the thyristor can be set by hand (9). The thyristor is controlled from a regulating loop (13). The advantage is that the drive permits rapid changes in speed and correction. Altering the thyristor triggering point allows precise changes in speed/torque characteristics.