AC Supply Power Controlling System

AC Supply Power Controlling System

AC Power Controlling System

Most of the electrical appliances used at home require AC power for their operation. This AC power or AC current is given to the appliances through the switching operation of some power electronic switches. For a smooth operation of the loads, it is necessary to control the AC power applied to them, by providing this control the level of illumination in a room, speed of food mixers, electric drills, sewing machines and heat generated by a heating element in an oven can be controlled with better accuracy and efficiency. This is achieved in turn by controlling the switching operation of the power electronic switches, like an SCR(Silicon Controlled Rectifier).

the firing angle of a Silicon Controlled Rectifier(SCR) and Triac in power control circuits is limited to 𝟗𝟎°possibility of controlling the ac power that is delivered to a load in the entire period of each half-cycle of a sinusoidal voltage prompts the use of a microcontroller in this work. so  here we are introducing AC power controlling system in which A microcontroller is used to adjust the firing angle of a Triac in ten equal steps within each half-cycle of the mains ac voltage (220 V, 50Hz). The results indicate that firing angles between 𝟎° and 18𝟎° can be obtained using the circuit.

Block diagram:

In This project we control the intensity of the lamp by controlling the AC power to the lamp. This is done by delaying the application of triggering pulses to the TRIAC or using the firing angle delay method. The zero crossing detector supplies pulses at every zero crossing of the AC waveform which is applied to the Microcontroller. Initially the Microcontroller gives these pulses to the opto-isolator  which accordingly triggers the thyristor without any delay and thus the lamp glows with full intensity.

Now using the keypad interfaced to the Microcontroller, the required intensity in percentage is applied to the Microcontroller and it is programmed to accordingly delay the application of pulses to the opto isolator. Thus the triggering of the thyristor is delayed and accordingly the intensity of the lamp is controlled and the result of total power percentage is provided by user is shown on LCD.

Hardware Requirements:

·       8051 Microcontroller

·       Zero Crossing Detector

·       Regulator

·       Opto isolator

·       Thyristor (TRIAC)

·       AC supply

·       Rectifier

·       Transformer

·       Keypad

·       LCD

·       Load/lamp

Software Requirements:

·       MC Programming Language: Embedded C

·       Keil version IDE

·       Proteus For Circuit &PCB Design