Timing Management for Acquisitions of AC Voltage and Current Signals Using an AVR Microcontroller Based System

Acquisitions of alternating voltage and current signals are widely implemented whether for monitoring or control applications. Precise timings during the acquisitions of the signals are needed to attain appropriate consecutive sampling of the signals. This paper presents a technique to manage the acquisition timings so that the sampled AC voltage and current signals can be further processed such as determining the power and their harmonic contents. The voltage and current signals were consecutively acquired through the use of a voltage transformer and a current transducer. In the developed technique, the timing management is supported by the implementation of some peripherals inside an AVR microcontroller and interrupt mechanisms. The software for the microcontroller was developed to control the implemented hardware and perform calculations to get important parameters such as RMS voltage and current, power, and harmonic contents. Some experimentations were carried out by acquiring the signals with 256 samples and sending the results to a computer to be analyzed. The results showed that the technique could successfully manage the timings for acquiring the ac signals precisely. The use of the interrupt mechanisms could also avoid timing disturbances which could be caused by tasks which were not related to the acquisition processes and executed by the microcontroller.