STEADY STATE ANALYSIS OF CURRENT SOURCE INVERTER FED INDUCTION MOTOR DRIVE

Abstract

This dissertation concerns an induction motor drive feel from a constant current source realized by a 3d,~* full controlled rectifier feeding a 30 inverter. It describes the analytical and experimental studies of the drive in the steadyp•s tale operating condition. The wort in the begining describes the progress f made in the field of current source inverter. fed induction motor drives so far. The various configurations of currentS-source inverter are discussed in Chapter II alongwith the current source inverter operation in auto- sequential mode, The requirement of firing pulses for auto•~seque• :'tial current source inverter ar~ discussed in Chapter III. In this chapter a suitable firing circuit which fulfills the above requirement is also developed. The design of the different blocks of firing circuit is given and oscill--' ograms of firing circuit are discussed. The guide lines for the selection of 'various components of the drive are presented in Chapter IV. In Chapter V, the system equations i.n oncordia's per unit system are developed and a suitable .mathematical model is formulated for steady•-state analysis of the drive. Chapter VI deals with the steadv°state analysis of the (iv) drive. The system equations are written for stead T--s tate operation and solved with the help of computer to obtain the steady—state performance of the drive with slip as independent parameter at different p.u. operating f.requ•--encies and d.c. l.in1 currents, results of this analysis are plotted and discussed. The results of experimental investigation of he fabricated system are presented in Chapter VII. These incorporate the experimental_ observations and oscillograms of current source inverter at resistive and induction motor load. The observations at induction motor load are obtained at different operating frequencies and d.c. link currents. The experimental oscillograms incorporate the oscillograms of line voltage, line current and of voltage drop at different points of inverter circuit. The oscillograms of line voltage and line current are compared with the ideal one and causes of discrepancies between the two are discussed. The effect of change of load and operating frequency on voltage and current waveforms is also shown with the help of oscil..lo-- grams and discussed.