Self-Tuned Feed-Forward Compensation for Harmonic Reduction in Single-Phase Low-Voltage Inverters

A new self-tuned feed-forward control strategy for low-voltage single-phase inverters to reduce the harmonic distortion in the output voltage is proposed. A discrete composite observer enables separate and independent control of the fundamental and harmonic components of the distorted inverter voltage and load current. The observer also facilitates the application of single-phase dq transformation by providing the fundamental in-phase and quadrature signals. In addition, the extracted voltage and load current harmonics from the observer are used for online identification of the series inductance and the equivalent resistance of the LC filter. While the feed-forward compensation is made self-tuned, the leftover harmonic distortion is reduced by small harmonic feedback. Simulation and experimental realization with Cyclone II field-programmable gate array have been carried out.