Sensorless temperature estimator of the rotor for submersible motor based on input voltages and currents

In the later stage of oil field exploitation, the submersible motor will lead to overheating and excessive energy consumption because of underrunning. Monitoring of the rotor temperature is very important for both control and protection of induction machines. Temperature sensors are usually avoided due to additional wiring. In this paper, a novel temperature identification method based on rotor slot harmonics is proposed. The mathematical model of submersible motor under high temperature and high pressure is established by analyzing the laws between the motor parameters and load, voltage and current. And the parameters and temperature identification of submersible motor can be carried out according to calculating the proposed model with the sampling voltage and current, so as to realize accurate system monitoring and reliable fault diagnosis. Opposed to temperature sensors and previous solutions where temperature is calculated based on the real part of the impedance, the presented method is calculated from the change of the rotor resistance.