Starting performance of delta-modulated inverter-fed submersible motors

An analysis of the starting performance of tuned delta-modulated inverter-fed submersible motors is presented. Submersible motors are induction motors that have unique constructional features. These motors are required to operate in one of the most harsh environmental conditions. The operating characteristics of a submersible motor pump system require soft starting facility and variable-speed operation. To satisfy both requirements, a delta-modulated inverter supply is proposed, and the system starting performance is presented. The soft starting characteristic of the motor is obtained by the inherent V/F control of the delta-modulated inverter. The analysis is 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 is done using gate functions. The starting performances of submersible motors improved substantially. Though the analysis and results presented in this paper are for a submersible motor, they are equally applicable for any type of polyphase induction motor.<>