Predictive Current Control for Three-Level Four-Leg Indirect Matrix Converter Under Unbalanced Input Voltage

Abstract

In this paper, a robustness evaluation of model predictive current control with instantaneous reactive power minimization for a three-level four-leg indirect matrix converter is presented. Unbalanced voltages can be extremely dangerous, especially for motors and other inductive equipment. Unbalanced voltages can have a detrimental effect on equipment and the power system, which is exacerbated by the fact that a small phase voltage imbalance can result in a disproportionately large phase current imbalance. The robustness test is carried out by considering balance and unbalanced input voltages. The proposed control predicts the behavior of the load current and the instantaneous reactive power for every possible 96 switching states. Subsequently, it selects the optimum switching state which fulfils the objectives of the control without the need of modulators. The cost function has been adequately modified to consider the asymmetrical aspect of the input voltage. Experimental validation using a laboratory prototype was conducted by using FPGA under a wide range of input voltage unbalance. The experimental results show high fidelity load current reference tracking while maintaining relatively low instantaneous reactive power during the transient and steady-state condition. The percentage of reactive power after setting the optimal weighting factor, the average reactive power was found to reduce to approximately 10-20%.

Performance improvement of an indirect AC/DC/AC matrix converter‐based IPMSM drive system under unbalanced three‐phase input voltages

“…The ideas of previously published papers are correct and useful [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. However, all of the papers focused on unbalanced issues that used matrix converters to control three-phase loads of resistances connected to inductances.…”

“…Experimental results validate the theoretical analysis. In addition, this paper proposes a simple method to control the matrix converter that uses six input current vectors at the virtual AC/DC converter and six output vectors at the virtual inverter separately, which is simpler than the method proposed in previous articles [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. The AC/DC stage control to obtain constant power of the virtual DC-link by adjusting the three-phase input currents is an original idea here as well.…”

“…Moreover, the papers only focused on the relationship between output and input voltages and currents due to the static characteristics of three-phase R-L loads. Furthermore, virtual DC-link voltages or power control have not been investigated [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. In the real world, approximately 65% of the electricity that is used in industry is consumed by electric motors.…”

“…The AC/DC stage control to obtain constant power of the virtual DC-link by adjusting the three-phase input currents is an original idea here as well. To the authors' best knowledge, the ideas proposed for the inverter stage control and AC/DC stage control for IPMSM drive systems are original and have not been investigated in previously published articles [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21].…”

“…Nguyen also investigated a simplified predictive control for an AC/DC matrix converter with active damping control under unbalanced grid voltages [20]. Basri presented a three‐level four‐leg matrix converter under unbalanced input voltages [21]. Liu et al.…”