Double Fault-Tolerant LLC Resonant Converter With Reconfiguration Method

A fault-tolerant converter is widely used in high-reliability applications. To satisfy the high-reliability requirements, fault tolerance is an essential feature and can be achieved by redundant converters. However, a large number of redundant converters degrade the overall power density and cost. This article proposes a novel fault-tolerant LLC converter, which can reduce the number of redundant converters. Its structure is based on the input-parallel, output-series two half-bridge LLC converters, and a midpoint connection on the secondary side. The proposed converter can withstand double short-circuit faults (SCFs) by utilizing only two converters instead of three converters. The redundant converter is used to achieve a single fault-tolerant capability against an SCF. When a second SCF occurs in the switch, the proposed converter is reconfigured to regulate the output voltage without additional semiconductor components. By analyzing the proposed converter, it is demonstrated that the proposed converter achieves high-power density and low cost without degradation of efficiency. In addition, it can be easily extended to have multiple fault-tolerant capabilities. Finally, the performance and feasibility of the proposed converter were confirmed with a 100 V/12 A 1200 W prototype.