A remote and sensorless stator winding thermal protection scheme for line-connected AC machines

An advanced remote and sensorless thermal protection technique for line-connected AC machines is proposed in this paper. The proposed technique includes an algorithm for detecting abnormal cooling conditions due to reduced motor cooling ability in addition to a stator resistance (R/sub s/)-based stator temperature (T/sub s/) estimation scheme. The motor cooling ability monitoring algorithm can be implemented using the R/sub s/ estimates of an existing DC injection-based R/sub s/ estimation scheme without additional hardware or parameter information. In addition, the influence of the fuse, circuit breaker, and cable resistances on the R/sub s/ estimate is investigated, and methods for compensation are suggested for improving the accuracy of the R/sub s/ estimate, and therefore, the reliability of T/sub s/ monitoring. Experimental results under various abnormal cooling conditions verify that the reduced cooling ability of the motor can be reliably detected and that it can be used in addition to the T/sub s/ estimate for complete motor thermal protection.

[1]  D. R. Turner,et al.  Real Time Prediction of Temperatures in an Induction Motor Using a Microprocessor , 1988 .

[2]  William H. Middendorf,et al.  Handbook of Electric Motors , 1994 .

[3]  M. Jhaveri,et al.  Intelligent microprocessor based devices provides advanced motor protection, flexible control, and communication in paper mills , 1996, Conference Record of 1996 Annual Pulp and Paper Industry Technical Conference.

[4]  Austin H. Bonnett,et al.  Rotor Failures in Squirrel Cage Induction Motors , 1986, IEEE Transactions on Industry Applications.

[5]  J.H. Lang,et al.  Monitoring the thermal condition of permanent-magnet synchronous motors , 1991, Conference Record of the 1991 IEEE Industry Applications Society Annual Meeting.

[6]  Thomas G. Habetler,et al.  A thermal monitoring and parameter tuning scheme for induction machines , 1997, IAS '97. Conference Record of the 1997 IEEE Industry Applications Conference Thirty-Second IAS Annual Meeting.

[7]  Jeffrey C. Lagarias,et al.  Convergence Properties of the Nelder-Mead Simplex Method in Low Dimensions , 1998, SIAM J. Optim..

[8]  T.G. Habetler,et al.  An on-line stator winding resistance estimation technique for temperature monitoring of line-connected induction machines , 2001, Conference Record of the 2001 IEEE Industry Applications Conference. 36th IAS Annual Meeting (Cat. No.01CH37248).