MICROCOMPUTER CONTROLLED CONVERTER . FED DC DRIVE

Abstract

The design, fabrication and performance evaluation of a microcomputer controlled 3-0 Dual Converter operating in non circulating current mode of operation for four quadrant closed loop speed control of a separately excited DC motor has been discussed in this dissertation. It consists of eight chapters. The chapter-wise contents are follows The first chapter discusses the DC drive importance and different methods of its speed control. The second chapter describes the review of literature related to proposed drive system. The chapter three deals with the principle and operation of dual converter. The non-circulating and circulating current mode of operations of dual converter are discussed In detail. The different crossover technique used in non circulating mode of operation is also presented. In the fourth chapter open loop and closed loop control of DC motor drive fed from dual converter is described The transfer function of the separately excited DC motor is derived. Its state space model is also presented. The PI controller design for closed loop speed control of the drive by pole placement technique is discussed in detail. The complete algorithm for calculation of controller gains is presented. The drive performance is simulated by solving system state equations using Runge Kutta fourth order method . The simulated results are also presented. In chapter five complete hardware and its interfacing is discussed. Each block of the hardware is described and its relevant circuit is also given. The chapter six discusses the control strategy for dual converter operation in non-circulating current mode in detail. The 3-phase converter firing pulse control and load current reversal logic are also presented. The flow charts of complete software are given along with their descriptions. The chapter seven deals with the experimental performance evaluation of the drive system. The performance of the drive system is evaluated on the basis of characteristics obtained under steady state and transient operating conditions of the drive system in open loop and closed loop conditions. The chapter eight presents the over all conclusion of the developed drive system and scope for further work is also proposed.