System and method for determining stator winding resistance in an AC motor

摘要

A system and method for determining stator winding resistance, and a temperature of the stator windings based on the stator winding resistance for thermal protection of an AC motor. The system includes a circuit having an input connectable to an AC source and an output connectable to an input terminal of an AC motor. The circuit includes at least one contactor and at least one switch to control current flow and terminal voltages in the AC motor. The system also includes a controller connected to the circuit and configured to modify a switching time of the at least one switch to create a DC component in an output of the system corresponding to an input to the AC motor and determine a stator winding resistance of the AC motor based on the injected DC component of the voltage and current.