Improved Fault Tolerant Control of a Redundant Actuation System Provided with Dual Stator Six Phases BLDC Motor for Autonomous Driving Applications

Current trends in the automotive industry are increasingly focusing on the concept of autonomous/ automated driving. At the heart of this concept is the need to provide new solutions dedicated to increase safety in operation, reduce the risk of accidents and make automotive systems more efficient. To meet these criteria, the new systems need to be as reliable as possible, provide complete full-time assistance and be also able to provide partial assistance in case of fault (1 FIT - Failure in Time). To this is added the requirement for reduced energy consumption, which implies higher efficiency of the considered systems. The paper presents a theoretical study doubled by a simulation analysis of some efficient strategies for controlling a redundant actuation system, which is viable both in normal and fault mode operation. In order to provide a high level of redundancy in both hardware and software, this concept implies the use of two independent control systems that provide command to two B6 bridge inverters and feeds the phases of a dual stator brushless direct current (BLDC) motor. The proposed system can be successfully integrated both in the electric power steering and braking systems of today's modern vehicles, as well as in autonomous driving platforms. To obtain a reliable and realistic BLDC motor model, the mathematical analysis was matched to a specific model design obtained in FEA (Finite Element Analysis). In order to validate the presented theoretical aspects, this study is followed by the implementation of the equivalent mathematical models in MATLAB / Simulink simulation environment.