Fail-Operational LLC Topologies with Fault-Tolerance Integrated Redundant Capabilities

Abstract:
The paper presents a novel fail-operational (FO) strategy designed for HV/LV DC-DC converters in Autonomous Drives (AD). Its primary objective is to ensure high availability through standalone fault-tolerant capability as well as redundancy for maintaining compliance with the Automotive Safety Integrity Level (ASIL) D, the highest safety standard. The proposed approach is implemented in Input-Parallel Output-Parallel (IPOP) LLC converters, where one of the two modules possesses inherent fault-tolerant capability. Each LLC module is designed to operate at 400 / 12 V and 1.8 kW, with an input voltage range spanning from 220 V to 440 V. Results indicate consistent power supply, soft switching capabilities both pre- and post-fault occurrence, and efficiencies exceeding 96 %.