Common-Mode Voltage Reduction in a VSI Inverter Applying Sequential Predictive Control

In the classical predictive control (CPC) implementation a cost function designed in terms of the control objectives and constants known as weighting factors must be minimized. Weighting factors are usually obtained by trial and error since there is no methodology to find the best factors, which also improve the controller performance. One possible solution is sequential predictive control (SPC) that proposes to eliminate weighting factors by sequential evaluation of simple cost functions. The contribution of this work is to analyze in detail the SPC performance and compare the results with a classic predictive current controller, in a VSI converter feeding an RL load where common-mode voltage is also reduced. Matlab/Simulink simulation results show that the SPC technique is able to reduce the common-mode voltage by half and still obtaining a balanced current system with an allowable THD, which is not feasible for the CPC technique. These findings demonstrate that SPC can improve results obtained with CPC without using weighting factors.