Advances in drive system technologies continue to provide increased performance, functionality, higher levels of efficiency, safety technology and ease of use. This paper offers a basic review of current AC drive system technology and details the features important to converting machinery drive system design. The topics covered in this paper will include; A review of the drive control modes, i.e., V/hz, Vector and Servo control modes. A comparison of drive performance types, i.e., general purpose vs. high performance system drives. An overview of synchronous and asynchronous motor technologies and best application practices for each type. Current motor feedback options with respect to application practice. Drive system architecture options and considerations for utilizing AC/AC drives and common DC bus technology. Drive power section technologies and the economic attractiveness when applied to common DC bus systems. Drive safety options and real world applications.