Calculation-Methods for Converter Fed Electrical Machines

Abstract

Different basis quantities of asynchronous machines need to be calculated within a drive application. The machine current, stalling torque, losses and temperatures do belong to these quantities. Converters are in principle capable to create a relatively sinusoidal current if they use an appropriate converter design and pulse frequency, but in order to save costs the supplied voltage form may be far beyond any sinusoidal supply. In both cases it is often sufficient to determine the losses and temperature increase based upon the current of the first harmonic and add an appropriate temperature margin for the higher harmonics.