High precision VSS motion control of servo drives

Abstract

In this paper we investigate the advantages and feasibility of motor control using very fast (MHz) switching in place of traditional amplifiers. We also propose integrated motion-control architecture based on a sliding mode control to be implemented in digital logic at an equally high rate. A switching controller combines the current and motion feedback paths into a single loop. A model-based observer estimates the load torque. When compared to second-order controllers implemented with traditional amplifiers, the proposed design promises increased performance, better efficiency, and improved load estimation. Recent advances in semiconductor technology provide the required fast switching and logic with relatively standard components. Simple implementation make concepts of switching control very attractive in motion control systems like control of dc or ac servomotors. The control algorithm designed by proposed approach can be easily implemented on DSP/FPGA platforms.