Study on the topology of three-phase inverter systems based on parallel-connected bridges

A new topology of three-phase inverter systems based on parallel-connected bridges was proposed. Each module was paralleled directly without passing through the filter circuit. Each module shared a common large filter circuit. The advantages and disadvantages of the topology based on parallel-connected bridges and the traditional topology based on parallel-connected output were analyzed. The influence of the circulating current because of the multiple modules distributed parameters based on parallel-connected output was given. The influence of the circulating current because of the synchronization error between multiple modules based on parallel-connected bridges was analyzed. A control strategy based on fiber ring net was proposed, it was designed to improve the synchronization accuracy. Simulation proves that the proposed topology was feasible and the circulating current analysis was clear and correct.