Design and Construction of Pic-Based Excitation Control System for Generator

Abstract

The main objective of this PIC-based excitation control system is to control the terminal voltage by adjusting the generator exciter voltage. Unlike the conventional control system, the PIC-based excitation control system is constructed to reduce the number of components and thus the amount of design work and wiring required for the system. As a consequence, this is constructed to be low cost and high performance. In this work, this design is based on the construction of switched mode power supply (SMPS). MOSFET IRF840 is used as switching element to control the field excitation through the field coil. PIC16F628 microcontroller is used as excitation controller and performs the modulator function in firmware. In this modulator function, Pulse Skipping Modulation (PSM) which generates train of pulses to turn IRF840 (switching device) on/off in order to reach the desired output voltage of the generator is used. In the PIC-based excitation control system, PIC microcontroller senses the feedback voltage and compares this voltage with reference voltage by using onboard reference and two comparators. In this control system, PIC microcontroller generates a train of pulses to turn MOSFET (IRF840) on/off to control the field excitation of the generator. This excitation control system provides 10% voltage regulation from no load and provides the continuous maximum current up to 8A at maximum rating of 32, 63, 125 and 250 Vdc.