AC power Control

Date : Jul 2015 - Jun 2016

This project has been designed to control the AC power supplied to a load by using a Triac. A Triac consists of two thyristors connected in anti-parallel fashion. Hence firing angle control of thyristors is used to vary the output power given to the load, which is a bulb in this case. As triac is combination of two thyristors therefore it gives complete firing control over positive nad negative half cycles of AC supply. The project uses a PIC 18f45k22 microcontroller along with a DC power supply. The DC Voltage is regulated to 5 volts for proper operation of microcontroller. Voltage regulation is done by using LM7805 voltage regulator which gives a constant 5 V DC supply. This system uses LTV 814-s opto-coupler as zero crossing detector which detects whenever voltage crosses the zero volt reference. In this project, the intensity of a lamp is controlled through a TRIAC which is connected to the microcontroller along with MOC3021 opto-isolator. The microcontroller generates pulses which are given to the opto isolator which in turn sends signal to TRIAC’s gate. Opto-isolator is used to isolate DC circuit from AC supply. A 16*2 LCD display is interfaced to the microcontroller for viewing the output power. The AC power is controlled by varying the trigger pulses from the microcontroller. User gives the required intensity to the controller through a matrix keypad or through a Bluetooth device. The microcontroller receives the percentage of output intensity and generates triggering pulses for Triac switching accordingly. The Triac further controls the electrical load connected to it.