A parameter estimation method for on-line failure detection in permanent magnet AC-brushless motors having current-dependent parameters

With reference to anisotropic permanent magnet (PM) brushless motors, the papers deals with a procedure for on-line identification of electrical parameters, based on the “recursive least square method”, designed for the cases of strong parameters variation depending on the operating condition. The identification procedure is superimposed to a conventional control diagram of PM AC-brushless drives (either torque-control or speed-control) and is really very simple. The results of this analysis can be used as identifiers of failure conditions in the drive; otherwise, during motor characterization on a test-bench, the method can be a simple instrument to map motor parameters in different operating conditions. The proposed technique is tested by means of numerical investigation on a motor whose electrical parameters have been off-line evaluated by experimental measurements and mapped in different operating conditions.