Novel Control Strategy of Instantaneous Power Based CVCF Inverter

This paper describes a novel control strategy of an instantaneous power based CVCF inverter. The most important feature of this strategy is a direct selection of switching states of the CVCF inverter to restrict errors between feedback values and command values of the active and reactive power. A theoretical analysis on relationship between the instantaneous power and the switching states is investigated, which is essential to compose a switching state table in the controller. Effectiveness of the proposed technique was examined through several computer simulations and experimental tests, using a 2.5-kW prototype. As a result, the output voltages were confirmed to be stable sinusoidal waveforms with total harmonic distortion of only 1.13% under a nonlinear load condition. Excellent voltage balance is also achieved by the proposed system even under unbalanced load conditions.