Fault tolerant control of three phase 2-parallel AC/DC PWM converter systems

摘要

This paper proposes a fault tolerant control method of an open-switch fault for a single IGBT in two parallel-connected three-phase AC/DC PWM converter systems. Recently, parallel converter has been widely used in the high power application. However, if the open-switch fault of the IGBT occur in the parallel converter, faulty condition causes the dc-link voltage fluctuation, the distorted grid current and the circulating current of the zero sequence. These problems could be mitigated by using the conventional fault tolerant control methods for the single converter, but the distorted grid current cannot satisfy the grid code. Therefore, this paper proposes the new fault tolerant control method by using the combination control of the two converters to compensate the distorted current of the fault side converter. Both dc-link voltage fluctuation and the THD of the grid current can be improved by applying the proposed fault tolerant control method. The performance and the effectiveness of the proposed fault tolerant control method are verified through the simulation.