Beyond the Battery: Functional Safety in Electric Vehicles
As the transformation to electric mobility unfolds, enhancing the safety of electric vehicles (EVs) is on everyone’s mind. It’s not all about physical safety, though. Functional safety (FuSa), a crucial aspect of EV design, addresses the prevention and mitigation of hazards caused by system faults and malfunctions. In this blog post, we will outline the importance of FuSa and discuss standards and considerations that are paramount in EV engineering to increase operational consistency and predictability.
ISO 26262: Road Vehicles – Functional Safety
ISO 26262 defines best practices for functional safety and guiding product development on a system, hardware and software level.
The ISO 26262 standard provides guidelines and recommendations throughout the product development process, from conceptual development through end-of-life. It details how to realize an acceptable risk level by defining the risk reduction activities for development(left hand side of the systems engineering V) and testing (right hand side of the V). In general, ISO 26262:
- Provides an automotive safety lifecycle (management, development, production, operation, service, decommissioning) and supports tailoring the necessary activities during these lifecycle phases.
- Provides an automotive-specific risk-based approach for determining risk classes, e.g., Automotive Safety Integrity Levels (ASILs).
- Uses ASILs for specifying the item’s necessary safety requirements for achieving an acceptable risk level.
- Provides requirements for validation and confirmation measures to provide an independent measure of functional safety.
Through application of the ISO 26262 standard, we help identify safety measures to mitigate the risks of the vehicles high voltage systems.
Hazard analysis and risk assessment
The process of functional safety excellence begins with a hazard analysis and risk assessment. This involves identifying potential hazardous malfunctions, assessing their severity across a variety of scenarios, determining any controllability opportunities, and determining the level of risk mitigation required for each malfunction. Upon completion of this activity, engineers can establish safety goals and define the necessary safety requirements to achieve them.
Functional safety concepts and practices in electric vehicle designs
The thermal and functional risks of the high voltage system in an electric vehicle are quickly and generally understood. Certainly, without the application of ISO 26262 in the design process, an architecture would still include redundancy and monitoring to ensure that critical functions like propulsion can be maintained even in the event of a failure of the electronics.
However, safety being taken into consideration is insufficient compared to the systematic, disciplined approach provided by the ISO 26262 standard, which enables quantifiable risk reduction practices. Is simple redundancy enough? Battery management systems (BMS) play a vital role in monitoring and controlling the state of the battery pack. Redundancy measures are implemented within the BMS, as well, to enable accurate monitoring, fault detection and even cell balancing. However, common redundant elements may not provide the level of risk reduction necessary to achieve an acceptable risk tolerance level.
To protect the electrical components and support safe operation, EVs incorporate overcurrent protection mechanisms and current limiting devices. These systems continuously monitor the current flow and intervene to prevent excessive current, which can lead to component damage or safety hazards.
Efficient thermal management and cooling systems are critical for maintaining safe operating temperatures in EVs. Overheating can lead to performance degradation, accelerated wear, and potential safety risks. Active cooling mechanisms, such as liquid or air cooling, are employed to regulate temperatures and prevent thermal runaway.
Failure modes
Failure modes and effects analysis (FMEA) or system theoretic process analysis (STPA) are systematic methods used to identify potential failure modes, their causes, and their effects. By analyzing the failure modes, we can help implement design modifications and safety features to mitigate the identified risks.
Cybersecurity and functional safety
With the increasing connectivity in EVs, cybersecurity becomes a significant element of functional safety. EVs must employ cybersecurity measures to prevent unauthorized access, data manipulation, or remote control of critical systems. We can also help you become compliant with ISO 21434 with our holistic approach to process excellence during R&D.
Implementing secure communication protocols between vehicle components and external systems helps prevent disasters. Encryption and authentication mechanisms play a significant role in enhancing the integrity and security of all communications.
Conclusion
Electric vehicles have emerged as a revolutionary technology that is here to stay. However, physical and functional safety is vital to gaining public trust and widespread adoption of EVs.
Our consulting and training services can help you meet standards relating to automotive components and systems. This includes the battery management system (BMS), vehicle control unit (VCU), onboard charger (OBC), thermal management systems (TMS) and much more.