The project is designed to achieve integral cycle switching, a method to remove the whole cycle, cycles, or portions of cycles of an AC signal. The control of AC power is very important. Generally, phase angle control is used for controlling AC power but due to that a sustainable amount of harmonics is generated in the system.
This technique is especially for linear loads such as heaters used in electric furnaces. This technique introduces a lesser amount of harmonics. However, the concept of achieving the integral cycle control by use of microcontroller can be very accurate as per the program written in assembly / C language so that the actual average voltage or currently obtained at the load is comparatively lower than the whole signal is applied to the load. In place of a linear load to be used in the output, a series motor, fan, or lamp can be used to verify the output.
One side effect of utilizing this scheme is an imbalance in the input current or voltage waveform as the cycles are switched on and off across the load. In this technique, we are using a comparator for zero-crossing detection which is fed as an interrupt to Atmega 328p microcontroller. Here the microcontroller delivers the output based on the interrupt given as input as the reference for generating triggering pulses.
Using these pulses, we drive the optoisolators for triggering the TRIAC to achieve integral cycle control as per the input switches interfaced with the microcontroller. A lamp or a fan is provided in this project in place of a motor for demonstration purposes. Further this project can be enhanced by using feedback mechanisms to automatically maintain the desired output to the load by appropriate cycle switching.