A Novel Synchronous Reference Frame Frequency-Locked Loop

This letter proposes a new design of frequency-locked loop (FLL) which is based on synchronous (dq) reference frame instead of stationary ({\alpha}\b{eta}) reference frame. First, a synchronous reference frame FLL (briefly called SRF-FLL0) equivalent to the conventional FLL is proposed. Then the SRF-FLL0 is improved by utilizing the phase error to acquire a better performance. The small-signal modeling and parameter tuning of the improved synchronous reference frame FLL (SRF-FLL) are presented. Finally, the theoretical analysis and experiment results verify the superiority and effectiveness of proposed SRF-FLL.