The safety issue of an electric vehicle and components has attracted intensive attention and discussions worldwide. To assure the safety of electrical/electronic systems and components of an electric vehicle, the International Organization for Standardization has developed ISO 26262 in recent years, in which risk assessment and reliability assurance are emphasized. To let manufacturers of electrical/electronic components understand more about ISO 26262, a motor control unit (MCU) to be used in an electric vehicle was taken as an example and related research was carried out. Based on the study of fault tolerance of the system, failure modes of components which result in failure of the system were found. Sensitivity study was performed to investigate how component failures would affect the system reliability. Numerical analysis was carried out based on the result of performance simulation as well as components failure rates documented in the US military reliability handbook. The final result indicates the mean time to failure (MTTF) of the studied MCU is long enough and the speed sensor is the most critical component of the system. It also shows that by reducing both speed sensor’s and current sensor’s failure rates, the MCU can reach the functional safety level required by ISO 26262.

Keywords

ISO 26262, motor control unit, performance simulation, functional safety, reliability