Induction Motor Drive Dc Link Capacitor Failure Analysis Using Thermal Modelling Approach

Abstract

Variable frequency drive (VFD) is widely used to control the speed of induction motor in industrial requirements. It mainly comprises of power converters and dc link capacitor. The dc link capacitor act as a filter in VFD and provides the low impedance path for ac ripple currents. According to history of failure rate of industry drives, around 20% of failure caused by dc link capacitor due to high surface temperature from the convertor units. In this paper, dc link capacitor in the form of heat transfer model is analyzed at different load and ambience conditions using FEM(Finite element method) based numerical method. And also, thermal characteristics of dc link capacitor 1500 μF, 450V in 22kW inverter drive is studied. The capacitor model is simulated in the environment of COMSOL multiphysics software and simulation results are shown to verify the performance of the capacitor.