Development of Functional Safety in a Multi-Motor Control System for Electric Vehicles 2012-01-0028
Despite increasing interest in alternatives to internal-combustion engine powered vehicles, still few manufacturers are releasing mass production electric vehicles to the market. The typical vehicle segments for EVs are urban vehicles, such as scooters, passenger cars or light-duty trucks due to their particular usage profiles and end users' acceptance of lower speeds and range.
Applus IDIADA has electrified a small 4WD SUV with one electric motor per wheel. The main objective was to develop, test and validate new strategies for improving dynamic stability control by actively regulating the torque distribution between the four electric motors.
Independent wheel drive concepts contribute to better driveability; however, they also involve new safety risks. A failure in a motor or related component can lead to a strong disruption of the vehicle's dynamic stability, causing critical situations for the driver or passengers.
For this reason, throughout the development, testing and validation process a strict consideration of all aspects of safety was undertaken, and, analysis and simulations were performed to define the possible failures, related failure modes and expected effects on the vehicle as well as the solutions to prevent them.
The paper presents the monitoring algorithms developed in the central drive controller to ensure good driveability with a maximum level of safety regarding component failures (motor, inverters, central drive control ECU) and also the design modifications in the HV architecture.