Parallel converter systems with maximum current limit control scheme for reliability improvement

A control strategy for improving parallel converter system reliability is proposed. This control combines the central-limit control with a maximum current limit and a fault-tolerance control feature to increase the degree of converter redundancy. This schedule assumes that the system consists of converter modules (CMs) operated in a continuous conduction mode, a current reference generator, and a system controller. There is no interconnection between CMs. Also, because each individual CM is directly controlled by the system controller, its failure can be detected and approximate correction actions can be given subsequently. Moreover, the proposed scheme is capable of determining a required number of CMs in the active state for any load condition. Thus, the degree of redundancy in the system is increased significantly. Only a few converters are activated at light loads. Therefore, the number of spare CMs increases virtually and the overall system reliability and performance is increased. The comparison between the proposed and conventional approaches on the aspects of system reliability is presented. In this comparison, the merit of the proposed control strategy in improving system reliability is highlighted