Direct self control (DSC) of inverter-fed induction machine: a basis for speed control without speed measurement

Mechanical speed measurement used to be an undesired necessity for inverter-fed induction machines. A possible way of calculating the exact speed without mechanical devices is presented. In addition, a simplified algorithm that is applicable for drives that do not demand high dynamic speed control performance (e.g., fans and pumps) is described. The control scheme is based on the analog basic version of direct self control (DSC) of inverter-fed induction machines and needs only a few additional operational amplifiers for signal processing. The performance, including start-up of an already rotating drive, is documented