ABSTRACT
A wide range of speed control for dc motors is traditionally achieved using armature voltage control and field current control. Line-commutated silicon-controlled rectifier (SCR) converters are simple, economical, and reliable, and they are extensively employed for single-quadrant, two-quadrant, or four-quadrant operation of variable-speed dc motors. However, line-current pollution is the major challenge associated with SCR-fed dc motor systems. This chapter introduces circuit operation of converter-fed dc motors, and then it investigates line-current harmonics in semi-converters and full converters. Improved switching schemes for performance enhancement are discussed. The chapter ends with a vivid explanation of the four-quadrant operation of dc motors.
