Development of Pulse Width Modulation Technique for Controlling Inverters Under Balanced and Unbalanced Operations

In this paper, three control methods based on pulse width modulation technique are proposed for controlling the voltage source inverters. In each switching period, the desired output voltages are generated by calculating their average values. Using the proposed control methods, it is possible to generate the balanced and unbalanced output voltages. By applying the instantaneous value of dc-link voltage in calculations, the effect of variations of dc-link voltage on the output voltages is eliminated. As a result, it is possible to reduce the value of energy storage element in dc-link. In comparison with the most of conventional control methods, implementation of the proposed control methods is simple. The proposed control methods guarantee the occurrence of the short-circuit fault at dc-link and open-circuit fault at the output is impossible. The validity of the proposed control methods is verified with the simulation and experimental results.