| Abstract |
In the applications of three-phase two-level voltage source inverters (VSIs) relatively large energy storagecapacitors are used to absorb the high DC-link current ripples mainly caused by the circulating reactivepower, the switched AC phase current flowing to the DC-link, and other dynamic and/or asymmetricoperating conditions. Especially for electrolytic capacitor technology the typically high current stressand consequent losses is known to limit the power electronics lifetime, thus the design and selection ofthis component is critical for the whole system. To alleviate this problem, a new model predictive control(MPC) cost function which enables DC-link capacitor current ripple reduction is proposed in this paper.Based on the derived DC-link current mathematical model and the available VSI switching states, thefuture DC current ripple can be predicted, and then the optimized space vectors that best tracks the sinusoidaloutput current and minimizes the DC-link current ripple are chosen. Compared with conventionalDC-link capacitor current reduction methods, the proposed approach has the advantage to incorporatean outstanding fast current control dynamics as well as being of relatively simple implementation becausethere is no need to adjust the switching signals or space vectors in the modulation as function ofoperational conditions of the system. Simulation and experimental results are presented verifying theeffectiveness of the proposed MPC method. |
