A fast-response current controller for microprocessor-based SCR-DC motor drives

An LSI firing circuit, in conjunction with a high-speed digital signal processor (DSP), has been developed to adjust the thyristor firing angle between 0 and 180 degrees for both positive and negative current control in a dual antiparallel-connected three phase power converter connected to a DC motor. A fast-response current controller is obtained by using feedforward techniques and a variable-structure proportional-integral (PI) compensator to produce an optimal current response under both continuous and discontinuous current conduction. Theoretical derivations and practical results of a predictive control strategy are shown. The main objective of this control scheme is to analyze the mathematical behavior of the system and use this knowledge to advantage in the control of armature current.<>