Direct instantaneous harmonic distortion minimization control for three phase sinusoidal current converter

In this paper, a novel instantaneous current control strategy for AC control loop of a voltage-type converter was developed in which two switching vectors are selected sequentially in one sampling period. Vector selection is based on control error minimization theorem to bring both fast response and low current ripple. Switching timing is determined in real time according to the THD (total harmonic distortion) minimization theorem with instantaneous THD definition as a direct evaluation function. With this algorithm, instantaneous control can be realized in almost fixed switching frequency. Experimental investigation confirmed the validity of proposed control algorithms