Analyses of unbalanced voltages on startup transients of a three-phase induction motor using EMTP MODELS

This paper presents a novel scheme on startup transients of a three-phase induction motor under unbalanced voltages. The new simulation tool-the Electro-Magnetic Transients Program (EMTP) MODELS is employed to accurately simulate the transient behavior of an induction motor during startup. The three-phase voltages applied to the stator windings of the studied induction motor are controlled by respectively adjusting the magnitude and phase angle of phase a and keep the voltages of the other phases. The voltage unbalanced factor (VUF) of the three-phase source voltages can then be varied to examine the different values of VUF on a machine´s startup transients. Experimental results obtained from a laboratory 300 W induction machine supplied by a computer-controlled three-phase MOSFET inverter are also performed to confirm the feasibility of the simulated results