Abstract: This project aims to achieve vital cycle switching, a technique that removes complete cycles or fractions of cycles from an AC signal. This technique is used to manage AC power in linear loads, such as heaters in electric ovens. The project uses a comparator for zero crossing detection, fed as an interrupt to a microcontroller of the 8051 family, to generate triggering pulses. These pulses are then driven by opto-isolators to trigger the TRIAC, achieving integral cycle control as per the input switches interfaced to the microcontroller. A series motor or lamp can be used to verify the output, but this may cause an imbalance in the input current or voltage waveform as the cycles are switched on and off across the load. A lamp is provided in the project for demonstration purposes, but the real objective is to verify whether the load switches on at zero cross of the waveform during random switching. The power supply consists of a step-down transformer 230/12V, which steps down the voltage to 12V AC, converts it to DC using a Bridge rectifier, removes ripples using a capacitive filter, and regulates it to +5V using a voltage regulator 7805. The project can be enriched by using a feedback mechanism to automatically maintain the desired output to the load by appropriate cycle stealing. Integral cycle switching is achieved by using a microcontroller of the 8051 family programmed in assembly/C language, ensuring that the actual time-average voltage at the load is proportionately lower than the whole signal. A comparator is used for zero crossing detection, and the microcontroller produces output based on the received interrupt and generates triggering pulses. These pulses drive opto-isolators to trigger the TRIAC, achieving integral cycle control as per the input switches interfaced to the microcontroller.

Keywords: microcontroller, Bridge rectifier, current

| DOI: 10.17148/IARJSET.2023.10717