Reliability analysis of a vehicle motor control unit in consideration of functional safety of ISO 26262

To guarantee the safety of electrical and electronic systems used in road vehicles, ISO 26,262 has been issued, emphasizing automotive functional safety. In this study, the reliability of a motor control unit (MCU) developed for a small-size electric vehicle is investigated in parallel with the functional safety concept of ISO 26,262. The MCU, together with the motor it controls, is considered a system, and the system's performance is simulated by software by the concept of hardware-in-the-loop (HIL). Potential component-faults are injected into the system to test the fault tolerances of the system. The recovering potential of the system under each injected component-fault named fault-coverage of the system is found accordingly. Within specific functional requirements, a Markov model is employed to find quantitative reliability of the system in consideration of the simulation results and the occurrence probabilities of component-faults. Sensitivity study is also performed to investigate how the component-faults affect the system reliability, and to find the most critical safety-related component of the system. The contribution of this study is to demonstrate through the example of MCU how the safety requirements of ISO 26,262 can be implemented and achieved.