Induction-motor stator and rotor winding temperature estimation using signal injection method

A new method to estimate the induction-motor stator and rotor resistance (R/sub s/ and R/sub r/) and temperature (T/sub s/ and T/sub r/) was proposed in this paper. Two signals with proper frequencies that yield high sensitivities of the terminal measurement to R/sub s/ and R/sub r/ at a given rotor speed are injected to the induction machine to estimate R/sub s/ and R/sub r/. The estimated R/sub s/ and R/sub r/ are then used to estimate T/sub s/ and T/sub r/, respectively, according to the relationships between R/sub s/ and T/sub s/, and R/sub r/ and T/sub r/. Simulation and experimental work have been carried out to verify the proposed method. The proposed method can estimate both stator and rotor resistance and temperature with high accuracy, and the estimated R/sub s/ and R/sub r/ can be updated in real time. It does not require an additional hardware or a large amount of finite-element analysis (FEA) or experimental data for implementation.