Starting performances of delta-modulated inverter-fed submersible induction motors

An analysis of the starting performance of tuned delta-modulated inverter-fed submersible motors is presented. Submersible motors are induction motors having unique constructional features. These motors are required to operate in one of the harshest environmental conditions. The operating characteristics of a submersible motor pump system require a soft starting facility and variable speed operation. To satisfy both requirements, a delta-modulated inverter supply is proposed, and its starting performance is presented. The soft starting characteristic of the motor was obtained by the inherent V/f, control of the delta-modulated inverter. The analysis was carried out using time domain representation of inverter voltages and the d-q axis model of the motor. The time domain representation of inverter voltages was done using gate functions. The starting performances of the submersible motor improved substantially. Although the analysis and results presented are for a submersible model, these are equally applicable for any type of polyphase induction motor