Induction Motor Control with a Small Dc-Link Capacitor Inverter Fed by Three-Phase Diode Front-End Rectifiers

Abstract

The main objective of the work presented in this paper is to design and simulate a new and simple 3-phase, Space Vector Modulated (SVM) front end rectifier feeding induction motor drive for near unity power factor operation with low supply current harmonics. The indirect vector controlled induction motor drive is used as load, but any load which is capable of regenerating can be employed. The various design considerations for linear operation of SVM front end rectifier are discussed. The expression to compute the required value  of line inductance, a method based on modulation index control for regulating dc link voltage and a method based on instantaneous phase compensation for achieving unity power factor operation are proposed. These methods are computationally less complex. A prototype system for 5-HP 3-ph induction motor is implemented in a MATLAB/SIMULINK environment. The dc link voltage, reference speed tracking and line side phase current are observed and total harmonic distortions (THD) are recorded. The unity power factor operation with acceptable current THDs and stiff dc link voltage conform the validity of control scheme.