Monitoring the thermal condition of permanent-magnet synchronous motors

An approach for monitoring the condition of small permanent-magnet synchronous motors operating under thermal stress is presented. The approach begins with the estimation of temperature-dependent motor parameters from measurement of line voltages and currents. The parameters are then used to derive estimates for motor temperatures. The electrically estimated temperatures are combined with a dynamic thermal model of the motor to yield an observer that is a Kalman filter. The temperatures estimated by the observer are used for failure prevention. By modifying the observer, it is tuned to use the geometric properties of its innovation for failure detection.<>