Design and Experimentation of a Single-Phase PLL With Novel OSG Method

Different phase-locked loop algorithms applied to three-phase grid voltages implement a closed control loop based on the Park transform to obtain the grid voltage instantaneous phase and frequency. When a single-phase grid voltage must be processed, one of the inputs of the Park transform is generated by a block that, starting from the available voltage, computes an additional signal with the same frequency of the grid voltage and ideally orthogonal to it. This paper introduces a novel method for the orthogonal signal generation and gives a detailed analysis of its functioning. Then, after sizing the control loop of the phase-locked loop, the paper considers different aspects relevant to implementation of the presented orthogonal signal generation and of the phase-locked loop on a digital signal controller, such as the finite numerical resolution, the memory usage and the computation time. Finally, the paper checks the comprehensive performance of the orthogonal signal generation and phase-locked loop pair by experimental tests and compares the obtained results with those available in the literature.