The Electromagnetic Losses Analysis of Inverter-Fed Induction Motor Accounting for Interbar Current and Rotor Slip Frequency

Abstract

Compared with the fundamental loss, the harmonic losses become very complicated because of the coupling between the power supply harmonics and the motor harmonics. To dispose of this problem, a multislice 2-D finite element model considering the interbar currents and a fast rotor harmonics identification method is employed to identify the harmonics of the rotor current density and flux density of the inverter-fed induction motor (IM). Considering the complex coupling phenomenon of time–space harmonics, a two-term iron model with piecewise-defined variable coefficients (PVCIL model) and a finite element analysis (FEA)-based copper loss method are then used to calculate the iron and copper loss components of the inverter-fed IM. Finally, based on the introduced methods, both the electromagnetic field and different losses terms of the same 5.5-kW inverter-fed IM under different load and supply conditions are calculated and analyzed. The experimental validation of those two losses’ calculation methods is performed on a 5.5-kW IM with different operating conditions. The results obtained in this article can provide the theoretical basis for targeted harmonic elimination and loss reduction in the design phase of the inverter-fed IM.