Control and elimination of sinusoidal harmonics in power electronics equipment: A system approach

The paper provides a general framework, with theoretical contributions and overview of methods for the analysis of elimination and control of harmonic components in power electronics applications. The internal model principle was introduced first as it provides a general controller formulation for tracking of (a) DC type of signals (b) harmonic - sine and cosine signals and (c) repetitive - arbitrary periodic waveforms that are often found in power electronics and drives. Following, the transfer function of a resonant regulator was derived by combining 2 synchronous regulators rotating in direct and inverse direction and transforming them into stationary reference frame. Repetitive regulator then followed as a parallel connection of large number of resonant regulators. The methodology was compared with single frequency Adaptive Noise Canceling (ANC) algorithm broadly used in signal and acoustic noise processing. It was shown that linear combiner and lest mean square (LMS) algorithm from ANC perform function of integrator in a synchronous reference frame and have the same transfer function as a harmonic regulator in stationary reference frame.