Experimental comparison of operational amplifier and voltage sensor-based zero-crossing detector circuits for power electronic converters

Osamah Al-Dori – Ahmet Mete Vural

   Zero-crossing detection (ZCD) circuits are widely utilized to synchronize power electronics converters with the grid and measure frequency and phase angle. They are usually designed using an operational amplifier (op-amp) or a voltage sensor accompanied by a processing device. The performance profile of these circuits alters depending on many factors, including the input voltage level. An experimental comparison between the two ZCD circuits across various input voltage levels does not appear to be presented in the literature. This work experimentally compares the performance of an op-amp and an isolated voltage sensor-based ZCD circuits, considering their rise/fall latency and precision in detecting the zero-crossing points (ZCPs). The design process and the experimental results demonstrated that the op-amp-based ZCD circuit is susceptible to false and multiple detections of ZCPs and is best suited for relatively low-voltage applications. On the other hand, the voltage sensor-based ZCD circuit allows signal conditioning and is best suited for relatively high voltage applications.

Keywords: AC-AC conversion, grid synchronization, grid-connected converter, operational amplifier (op-amp), phase detection, voltage sensor, zero-crossing detection (ZCD)

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