PERFORMANCE OF A LINE COMMUTATED INVERTER FED INDUCTION MOTOR DRIVE

Abstract

The dissertation deals /\ the design, analysis and experimantal studies of a line commutated inverter fed induc-tion motor drive. In this scheme, a three phase a.c. supply is converted into a variable d.c. supply using a combina-tion of three phase uncontrolled bridge converter and an auto transformer. The commutation of thyristors of line commutated inverter is achieved using three phase capacitor bank which are charged by the back e.m.f. of motor. The whole work of dissertation broadly has been categorized as literature survey, design and fabrication of firing and power circuits 9 theoretical prediction of steady state performance of induction motor and experimental studies. The literature survey at the begining of dissertation reveals the progress made in the field of line commutated inverter for variable frequency output and solid state converters fed variable frequency operation of cage I.M. In chapter-II the details of experimental setup in which system discription and design of power and firing circuits are discussed. The starting methods and detailed experimental investigations to study the feasibility of the system as well as to obtain performance of motor under varied operating conditions are given in chapter-III. In ( iv) (v) chapter-IV steady state analysis and performance of the system has been predicted analytically using equivalent circuit approach as well as digital simulation along-with experimental results to establish the validity of predicted results. The feasibility of the line commutated inverter fed induction motor system to operate as a variable fre-quency source and as a group drive are described in chapter-V and VI, respectively., Lastly the main con-clusions and suggestions for further work are given.