PARAMETERS IDENTIFICATION OF A 3-PHASE LC FILTER USED FOR VARIABLE FREQUENCY DRIVE BASED ON PRACTICAL INDUCTION MOTOR TESTING

Abstract

A lot of harmonics exist inherently in the front end of 3-phase rectifier feeding Variable Frequency Drive (VFD) of 3-phase induction motor due to the nonlinearities behavior in such loads. The harmonics cause energy losses and deficiency to the overall system. The goal of this paper is to reduce the harmonics for a variable frequency drive by calculating the equivalent circuit of the 3-phase induction motor and identifying the parameters of a passive filter, which is connected to the input side for the rectifier from the VFD converter. The equivalent circuit for the 3-phase squirrel cage induction motor is achieved according to the results of laboratory tests. The concept of point of common coupling (PCC) is implied into the calculations of harmonics and power factor. The performance of the VFD described is simulated using Matlab /Simulink (2008).