Design of Controllers PD, PI &PID for Speed Control of DC Motor Using IGBT Based Chopper

This paper presents a novel approach for determination of optimum values of Kp, Ki and Kd for design of controllers such as PD, PI & PID for enhancement of performance parameters of Permanent Magnet Direct Current (PMDC) Motor drives using IGBT based chopper in MATLAB/SIMULINK toolbox environments. The effectiveness of proposed novel approach has been presented so that the better performance parameters of PMDC motor drives are achieved in closed loop as compared to in open loop systems. This work is very useful for researchers, scientists, engineers and industrial persons. Index Terms Optimization of Kp, Ki and Kd for Controller design, PMDC motor modeling, IGBT based chopper  INTRODUCTION Developments of high performance motor drives are very essential for industrial applications. A high performance motor drive system must have good dynamic speed command tracking and load regulating response. DC drives, because of their simplicity, ease of application, reliability and favourable cost have long been a backbone of industrial applications. DC drives are less complex as compared to AC drives systems. DC drives are normally less expensive for low horse power ratings. DC motors provide excellent control of speed for acceleration and deceleration. The power supply of a DC motor connects directly to the field of the motor which allows for precise voltage control, and is necessary for speed and torque control applications [1]-[5]. AC drives with this capability would be more complex and expensive. Properly applied brush and maintenance of commutator is minimal. DC motors are capable of providing starting and accelerating torques in excess of 400% of rated. D.C motors have long been the primary means of electric traction. They are also used for mobile equipment such as golf carts, quarry and mining applications. DC motors are conveniently portable and well fit to special applications, like industrial equipment and machineries that are not easily run from remote power sources [6]-[8]. The closed-loop controllers are very common means of keeping motor speed at the required "set-point" under varying load conditions. It is also able to keep the speed at the set-point value where for example, the set-point is ramping up or down at a defined rate. PI, PD and PID controllers are the speed controllers most commonly used to obtain the desired speed in any drive. There are various methods of setting optimum GERMAN JOURNAL OF RENEWABLE AND SUSTAINABLE ENERGY RESEARCH (GJRSER) Singh, et al., Vol. 1, Issue.1, pp. 29-49, 2013 30 control parameters in these controllers to achieve the desired response. In Trial and error method, the parameters are adjusted by watching system responses [9]-[13]. PROBLEM FORMULATION The mathematical modeling of PMDC motor with IGBT based chopper and PD, PI and PID controllers are as follows. A. PMDC Motor The schematic diagram of PMDC motor is shown in Fig.1. Fig.1. Schematic Diagram of DC motor To find the transfer function for the block diagram of the open system a differential equation to describe the system dynamics. Kirchhoff’s voltage law is used to map the armature circuitry dynamics of the motor. r a a a a a K dt dI L r I V     (1) ( V Vdc  )   V K r I L dt dI r a a a a a      1 (2) The electromagnetic torque developed by PM dc motor: a a e I K T  (3) The viscous friction torque: