Low-Complexity Triangular In-Phase and Quadrature Signal Generator-Based Phase-Locked Loop

The second-order generalized integrator (SOGI)-based phase-locked loop (PLL) is commonly employed in grid-following converters for phase and frequency synchronization. However, the computational burden associated with SOGI-based in-phase and quadrature signal generation (IQG) and feedback sine generation limits its suitability for implementation on resource-constrained processors. This paper introduces a low-complexity triangular IQG, termed triangular-SOGI (tSOGI), which significantly reduces real-time computational requirements. The proposed tSOGI algorithm is analyzed using vector field approach and its parameter is tuned via an observation-based state-space approach to obtain a desired performance. Furthermore, three novel PLL structures-tPLL 1 , tPLL 2 , and tPLL 3-are developed, utilizing the tSOGI to reduce the complexity associated with the sinusoidal signals in conventional techniques. The algorithms are implemented on an FPGA-based platform using discrete realization and are experimentally evaluated under diverse grid disturbance scenarios. The results demonstrate that the proposed PLLs achieve performance equivalent to the conventional SOGI-PLL while reducing computational complexity, achieving a significant reduction in computational resources and 40% faster execution time.