Determination of performance parameters of a small-size high-speed induction motor using the field-circuit method

Core losses generated in small size high-speed induction motors constitute a significant part of total losses in the motor, in particular at higher frequencies. Precise determination of these losses is vital to assure the proper functioning of the motor. Core losses in electrical machines depend on the power loss density of the electrical sheets used, which in turn depends strongly on frequency, magnitude and form of the applied magnetic field. The specific losses are usually only given for the 50 Hz alternating flux. Consequently, various estimations are applied for higher frequencies. To avoid errors associated with such an approach a direct use of specific losses measured on ring samples has been proposed. The no-load and load losses in the core have been calculated using a field-circuit and a circuit method. The machine parameters and load characteristics have also been determined at supply frequencies from 50 to 200 Hz. The computational results have been verified against measurements.