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In this paper, a phase-locked loop algorithm appropriated for digital-signal-processor-based control implementations, where the operation of a static-power converter needs to be synchronized with an ac network, is presented. The proposed algorithm includes a multiplier, a filter, a feedback closed loop, and a numerically controlled oscillator stage. As a result, a discrete sine (and cosine) signal is generated in synchronism with the fundamental component of an external-reference (ER) signal. Moreover, the sampling period of the algorithm is adjusted at each sampling instant such that an integer number of sampling periods per period of the ER signal is ensured. This is the main feature, and it is achieved by using a discrete rectangular window filter and a discrete controller. The proposed algorithm code is simple, stable, and presents high noise rejection. A comprehensive theoretical justification and various rigorous experimental tests are included. [ABSTRACT FROM AUTHOR]

Presents an analysis of a voltage sag compensator for critical loads in electrical power distribution systems. Conceptual design of the proposed approach; Topology of the pulsewidth modulation ac-ac converter; Details of the simulation and experimental results.

Presents a switching strategy for multilevel cascade inverters based on the space-vector theory. Description of the inverter; Vector control scheme; Generation of the gating pulses.