Publication: Sensorless microcontroller based zero-crossing detection system for ac signals using a rounding function
Loading...
Date
2024-01-01
Authors
Ali Ahmed Ali Saleh
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Microcontroller-based methods for zero-crossing detection (ZCD) presented in
the literature employ external integrated circuits (ICs) to sense electrical signals, and
their algorithms are sophisticated. Therefore, this work proposes a simple open-loop
sensorless microcontroller-based algorithm for determining zero-crossing (ZC)
instants of sinusoidal signals that can be used for phase detection (PD) in phase locked loops (PLLs). The proposed algorithm employs a built-in rounding function in
the Arduino software environment. The developed system was simulated using
MATLAB Simulink® to demonstrate its prominent features in recognizing zero crossing points in two cases: a pure sine signal at a grid frequency of 50 Hz, and
distorted signals with total harmonic distortions (THD) of 10%, 20%, 30%, and 40%.
In the simulation, the proposed system exhibited outstanding results in terms of
simplicity, accuracy, and robustness. However, in practice, accuracy and robustness
are relative terms, because they depend on the specifications of the microcontroller
board. In this study, two low-cost microcontroller boards Arduino Uno and Arduino
Due were used. The Uno is an 8-bit board with a 16-MHz clock speed and the Due is
a 32-bit with an 80-MHz clock speed. Therefore, an error in terms of the phase shift
emerges in the output signal, which was measured to be 0.0314 rad (1%) and 0.0126
rad (0.4%) for the two boards respectively at 50 Hz. Moreover, the proposed system
detected the ZC points for distorted signals with a THD of up to 30% without using
filters and failed at a THD of 40% because the waveform crossed the zero level
multiple time in a half-cycle. Finally, the ZC points were identified in a three-phase system, and the validity of applying the proposed method to polyphase systems was
demonstrated.