Performance of Digital Phase Locked Loop Based on Notch Filter in Industrial ARM-Cortex Microcontrollers

Abstract

Phase-locked loop (PLL) is a key algorithm in a grid-connected power converter. The PLL must have excellent performance but consume minimum resources when implemented in a microcontroller.As the phase detector in the PLL system, causing the second harmonic signal, a notch filter is applied to cancel the second and higher harmonic that caused in PLL system to get better output signal. A simple second-order notch filter was implemented on the microcontroller.The performance of implemented digital PLL will be measured through several experiments. The experiment results show that the proposed digital PLL performs well after tested with emulatedvoltage sag, distorted input waveforms, and phase-jump conditions.