INVESTIGATIONS ON PWM RECTIFIER FED D.C. MOTOR DRIVE

Abstract

Statically controlled D.C. motors are widely used for variable speed drives in industry due to .ease in control. The input performance of phase controlled converter . namely input power, factor deteriorates at reduced output voltage. Attempts are being made to control the converter operation so as to reduce the lower order harmonics and to improve the fundamental power factor and the input power factor. To achieve this goal present scheme employs a .three phase pulse width modulated converter. This dissertation deals with the design, 'development & performance investigation of 3-PWM converter fed DC drives. The closed loop speed control is realized through software using 8031 - chip micro controller dedicated system. The performance of the drive is investigated in both open loop and closed loop. The speed PI controller parameters and the current PI controller parameter has been designed from the stability analysis of the closed loop drives. In chapter I, various methods of speed control of D.C. _ motor, advantages of converter fed DC drive ,phase controlled converters, power factor techniques ,and literature review 'related to the proposed scheme has been discussed._ 'Chapter II deals with PWM' converter. In chapter III mathematical modelling of the system is developed and PI 'controller parameters, for both speed and current. loop, are determined for stability analysis by D-partitioning technique.. Chapter IV describes., the hardware required for the proposed scheme and its software implementation. Chapter V give the experimental results and last chapter draws the overall coiiclusion and scope for future work. .