Improved predictive current controller for four-quadrant converters

Abstract

Predictive current controller is often adopted to compensate time delays caused by digital control. But traditional predictive current control algorithm for four-quadrant converters is an open-loop current observer essentially. Current value predicted is affected by many factors such as grid voltage extrapolation error, inductance error and dead-zone time. All of them will aggravate the grid current distortion. Current predictive algorithm based on repetitive control observer was proposed which has the advantages of simplicity and easy to be implemented on microprocessors in this paper. The proposed method can improve the predictive current precision and reduce the grid current distortion. The proposed method was verified by the experimental results.I.

Analysis of nonlinear oscillation of four-quadrant converter based on discrete describing function approach

“…It's shown in [5], [6] and [7] that these oscillations are related to the instability of the system. Four quadrant converter often uses double loop control, in which the inner loop is current loop [8].…”