Performance improvement of servo motor drive controls

This research program is being undertaken at the Industrial Research Institute of Swinburne University of Technology (IRIS) in Melbourne Australia as part of collaboration with the Cooperative Research Centre (CRC) for Intelligent Manufacturing Systems and Technologies (IMST) and ANCA Pty. Ltd. The research is expected to be completed by 2002. In broad terms, the objective of the research program is to enhance the performance of servo motor drive control systems as they pertain to precision machine tool applications. Specifically, the research here investigates the issue of so-called 'dead-time effect', which arises from the finite switch-off time associated with power semiconductor devices in motor drives---this is a period in which the transistors in a given portion of the motor drive are switched off to avoid short-circuiting. The dead-time effect leads to a number of performance degradation issues in motor drive systems The objective of this paper is to provide an overview of the problem at hand and the issues that are being investigated. The software compensation of dead time effects is investigated in this research and presented herein. It is composed of a fully integrated digital set-up, implemented on a programmable logic device and digital signal processor (DSP). The technique is based on an adequate feed forward compensation of the transistor switching sequence generation on the basis of the stator phase current signs/polarity and of the switching state of the power modules