demerit and merit of four quadrant d.c
drive

merits and demerits of four quadrant dc drive employing non circulating and circulating current dual converter

ABSTRACT: In this paper, design of modular brushless dc motor drive and its operation in four quadrants is described. In this design, each permanent magnet BLDC motor is powered by an inverter and number of motors and inverter sets are stacked together in order to give the required power rating and to have good reliability. The four quadrant operation of this design is also done in this paper to operate the motor clockwise and counter clockwise i.e., in
motoring mode and regenerative braking mode. This is essential in saving the power as in the regenerative braking mode of operation, the power is fed back to the supply mains. The speed control of the drive system is also studied in this paper.A four-quadrant gate turn-off (GTO) power converter employing a single six-GTO bridge and four thyristors as reversing switches is described. Such a four-quadrant converter is economical compared to a dual-converter employing two bridges, each with six GTOs. A four-quadrant DC motor drive employing the proposed converter and closed-loop speed control with an inner current control loop is also presented. The controllers are designed using symmetric optimization. Experimental results with a 3 HP DC motor are given for steady-state and transient responses of the drive. A comparative study of the present four-quadrant drive and the one reported earlier is also presented