Design of microprocessor-based system for positioning servomechanism with induction motor

Digital control algorithms are proposed for a position-controlled system with an inverter-fed induction motor. Two structures for the positioning servomechanism are suggested in which the appropriate digital control laws are applied and a straightforward method for adjusting of controller parameters is developed. The method enables the designer to match the desired dynamic performance and to eliminate the steady-state position error due to the presence of a constant or a slowly varying load disturbance. Particular attention is paid to the nonlinear position control design, which preserves the desired response even in the case when electrical torque reaches limits imposed by the inverter current capacity. To illustrate the proposed design procedure and to verify the efficiency of the nonlinear control laws, simulation results and waveforms from an experimental setup are presented.