Single-phase frequency-fixed all-pass filter QT1-PLL with inherent dc offset suppression

Samir Gautam*, Anant Kumar Verma, Claudio Burgos-Mellado, Diego Munoz-Carpintero, Foad Taghizadeh, Binod Prasad Rimal, Pedro Roncero-Sanchez

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The all-pass filter (APF) is an orthogonal signal generator (OSG) structure that is widely adopted in single-phase systems because of its simpler implementation. One of its applications is in the form of synchronous reference frame (SRF)-based phase-locked loop (PLL). The APF basically provides unity gain in the whole frequency spectrum while altering its phase according to the frequency. The APF is, however, devoid of a filtering capability. The dc offset poses a particularly serious challenge and this issue is usually addressed with the integration of additional filtering structures. This article shows the development of a two-stage modified APF (TSMAPF)-based OSG structure that is capable of suppressing dc offset while maintaining a frequency-fixed structure. The proposed OSG relies only on optimized parameter tuning without the need for auxiliary filtering units. The TSMAPF is then combined with a quasi type-1 (QT1) PLL to provide an innovative single-phase PLL with a fast dynamic response and the capacity to reject disturbances. Both simulation and experimental results verify the effectiveness of the proposed PLL.

Original languageEnglish
Article number1503910
Number of pages10
JournalIEEE Transactions on Instrumentation and Measurement
Volume73
DOIs
Publication statusPublished - 2024

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