Design and manufacturing of digital MOSFET based-AVR for synchronous generator

Abstract

Automatic voltage regulator is designed to keep the terminal voltage of the generator constant, regardless of all disturbances. It is done so by controlling field current of synchronous generator which is directly related to terminal voltage. Peak detector circuit detects the peak voltage of generator terminal sinusoidal voltage. This peak voltage is then converted to binary code by ADC0804 IC. After that, the binary code is processed by AT89S52 microcontroller. This microcontroller is used to generate PWM according to the peak voltage sensed by Peak detector. If the terminal voltage is higher than desired set point, the PWM duty cycle decreases; if terminal voltage is lower than desired set point, the PWM duty cycle increases. PWM signal is fed to IRF740 MOSFET gate terminal. This PWM gate signal hence increases or decreases the field current of generator which in return, increases or decreases terminal voltage. The designed close loop feedback system ensures the stable output voltage that is necessary for sensitive load. This control strategy can be implemented in an islanded micro grid with renewable energy sources for a regulated output voltage, irrespective of the intermittencies of the renewable energy sources like wind and solar.1