Novel estimator of distorted and unbalanced electromotive force of the grid for control system of PWM rectifier with active filtering

Control of PWM rectifier with active filtering is realized by fast and precise shaping of its AC currents. In the paper the control system with predictive algorithms of both set currents calculation and currents control is proposed. These algorithms provide very high accuracy and dynamics of AC currents shaping which is limited only by parameters of the power circuits. In both algorithms calculations are based on precise information about present and future samples of in general distorted and unbalanced equivalent electromotive force (emf) of the grid. For this purpose the novel, grid voltages sensorless, precise estimator and predictor of grid emf is proposed. This robust algorithm is based on digital signal processing techniques and requires relatively low computational effort. In this paper the simulations and experimental results are presented which show the performance of proposed estimator and predictor of grid emf and its influence on operation of the control system of PWM rectifier with active filtering