On-line determination of nonlinear parameters of induction motor with squirrel-cage rotor.

New mathematical relationships for the contactless determination of the active resistance of the rotor winding, excitation circuit inductance, and the electromagnetic time constant of the rotor are presented for an operating motor. The relations include parameters that are available for direct measurement in the control system or known from the design documentation and needed for calculations. We have revealed new interdependences between the basic parameters of operating frequency-controlled induction motors for any mode at different saturations of the magnetic circuit and any temperature of stator and rotor windings. [ABSTRACT FROM AUTHOR]