Switching motor control: toward an integrated amplifier design with position feedback

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 an integrated motion-control architecture based on a third-order motor model to be implemented in digital logic at an equally high rate. A switching controller combines the current and position feedback paths into a single loop. A model-based observer estimates the unsensed motor velocity. When compared to second-order controllers implemented with traditional amplifiers, the proposed design promises increased performance, better efficiency, and improved velocity estimation. Advances in semiconductor technology provide the required fast switching and logic with relatively standard components. Preliminary experiments characterized nonlinearities in the motor electrical dynamics and verified good performance at frequencies up to 5 MHz.