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This paper describes an offset-free model predictive control (MPC) algorithm using a disturbance observer (DOB) to control the active/reactive powers of a three-phase ac/dc converter. The strategy of this paper is twofold. One is the use of DOB to remove the offset error, and the other is the proper choice of the weighting matrices of a cost index to provide fast error decay with small overshoot. The DOB is designed to estimate the unknown disturbances of the ac/dc converter following the standard Luenberger observer design procedure. The proposed MPC minimizes a one-step-ahead cost index penalizing the predicted tracking error by performing a simple membership test without any use of numerical methods. A systematic way for choosing the weights of the cost index, which guarantees the global stability of the closed-loop system, is proposed. Use of the DOB eliminates the offset tracking errors in the real implementation. Using a 25-kW ac/dc converter, it is experimentally shown that the proposed MPC enhances the power tracking performance while considerably reducing the mutual interference of the active/reactive powers as well as the output voltage. [ABSTRACT FROM PUBLISHER]

This paper presents a control scheme for the dynamic performance improvement of an AC/DC converter using the model predictive direct power control (MPDPC) with a duty cycle. In the MPDPC, the active and reactive power is simultaneously controlled with a single cost function. If either of the two control targets has a large power variation, the control weight is concentrated on one side, which causes mutual interference. Because of such mutual interference, the control dynamics of the AC/DC converter deteriorates. Due to the control weight being concentrated on one side using the single cost function, even if the control dynamics of the other side decreases, the dynamic performance of the system is improved by reconfiguring the cost function that has the weighting factor to minimize the decline of the system dynamics that is caused by the mutual interference. The effectiveness of the proposed control scheme is verified by comparing its results with those of the conventional MPDPC. The results are obtained through the simulations and experiments. [ABSTRACT FROM PUBLISHER]