A digital phase-locked loop based on the linear phase-shifted control implemented by a finite impulse response filter for a single-phase power system

A finite impulse response (FIR) filter can guarantee the linear phase characteristics; therefore the method of constructing two voltage vectors vα, vβ, in the αβ stationary reference based on a FIR filter is proposed in this paper. According to the principle of the digital phase-locked loop (DPLL) by means of the transformation from αβ stationary reference to dq synchronously rotating reference for a three-phase system, and the synchronously sampling technique is used to assure the constant filter order, a DPLL on the basis of a fictitious two-phase transformation for a grid-connected single-phase power conversion system is implemented. Taking some parameters such as the fluctuations of the voltage magnitude and grid frequency and the 3rd harmonic content into consideration, the proposed method is simulated in PSIM software. A simulative inverter with the control core of DSP TMS320C32 is installed. The experimental results verify that the method is feasible and it has the better static and dynamic performances.