Induction motors thermal monitoring by means of rotor resistance identification

Abstract

Rotor and stator temperature are of concern in both shortterm machine protection and in longer term condition monitoring for large induction machines. Especially, when operating with overload cycles, it is necessary to monitor rotor bars and stator winding temperatures to make sure that the temperature remains below prescribed limits. The purpose of this paper is to present a thermal monitoring technique, for induction motors steady-state operation, based on the rotor resistance identification. Experimental results, for a 4-kW four-pole squirrel cage induction motor, show the industrial viability of the proposed technique.

Detection of broken rotor bars in induction motors using nonlinear Kalman filters

“…A thermal variation in R r can [26]. Therefore, as a part of the EKF/UKF estimation process, the thermal variation in the rotor resistance is compensated by using the same approach developed in [6,26]. In fact, it is easy to monitor the rotor temperature by estimating its resistance and then its temperature using…”

“…These recursive update equations can be stated as follows: (6) where the state prediction vectorx k+1|k , innovation vector v k+1 , Kalman gain matrix K k+1 , state prediction covariance matrix P k+1|k , and innovation covariance matrix P v k+1|k may be defined as below:…”

“…Ideally, monitoring and diagnostics of induction motors should use passive electronic sensors and not any thermal or mechanical * Corresponding author. sensors [6,7]. In this way, in [8] a failure monitoring system was proposed that combines the induction motor physical model with the data provided by a few number of sensors.…”

Rotor Temperature Modeling of an Induction Motor using Subspace Identification**This work was supported by the German "Federal Ministry of Education and Research" (BMBF) within the priority program "ICT2020" under project funding reference number "16N11869".

“…Others estimate the rotor resistance, e.g. Beguenane and Benbouzid (1999). A relatively new approach is to inject an additional electric signal with specific properties into the terminals of the motor and then determine the motor state from the response on these signals.…”

Supply frequency tracking in resistance-based induction motor rotor temperature estimation

“…A resistance-based rotor temperature estimator achieves such an objective by deriving a rotor temperature from a rotor resistance based on an induction motor equivalent circuit model using voltage and current measurements and a slip frequency [2], [3]. The slip frequency is often resolved from a rotor slot harmonic frequency by applying spectral estimation techniques to acquired current samples [4].…”