Novel Orthogonal Signal Generator for Single Phase PLL Applications

What is it about?

Single-phase phase-locked loops (PLL) are used in various types of power electronics applications, including voltage source inverters, PWM rectifiers and different other types of grid-tied power converter utilities. The orthogonal signal generators (OSG), used in single-phase PLL, are generally based on various types of filters, and they need to operate robustly in relation to the grid voltage disturbances and frequency variations. In this study, a novel OSG is proposed based on a modified firstorder all-pass filter, which enables the PLL phase detector (PD) to operate with different response speeds, tuned by means of a single parameter. The PLL is experimentally verified and compared with a number of conventional solutions. Tests include responses to phase angle disturbances, frequency steps, and PLL input voltage distortions. Results show that novel OSG filter enables faster PLL responses when compared to several conventional OSG filters, all designed to have the same disturbance attenuation at double fundamental frequency.

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Why is it important?

A new orthogonal signal generator has been proposed, to be used in single-phase PLL applications, based on the modified first-order filter. When compared to conventional SOGI, Park and APF OSG filters, the novel MFO enables the faster orthogonal signal generation to be achieved.

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