Design and fabrication of voltage stabilizer using 8051 microcontroller

Abstract

This study deals with the design and fabrication of a single-phase voltage stabilizer using 8051 microcontroller. The basic building blocks for this design include an AT89S51 microcontroller, a solid-state relay (SSR), a stabilizer transformer, a diode-based bridge rectifier, a 7805 regulator, an

ADC 0804 and LEDs to display the digital value of the input voltage. This

design is based on the principle of varying the input voltage to obtain an output voltage that is considerably constant. Any time there is a change in the input mains supply voltage, a corresponding voltage is digitised and fed into the microcontroller which then switches on an appropriate SSR to add or

subtract a winding to or from the transformer, so as to maintain the output

voltage. Apart from the voltage stabilisation, the device also provides voltage

protection against transient voltages that are harmful to industrial, laboratory

and domestic appliances. The voltage differences from red, yellow and green windings were however higher. The sudden change in AC voltage was due to only two additional windings. As a result, three relays were used to select the

output voltages as the input voltage changes. This situation can be avoided

when a transformer with more windings (tappings) are used. A variable

transformer was used to vary the AC input voltage from 270 V AC and the

corresponding voltages on the ADC output and the AC outputs from the Red,

Yellow and Green tappings of the transformer were recorded.