SYSTEM SAFETY SUPPORT

Background
The department Battery Controls and ECU platform at the Company are responsible for functional safety of the traction battery. The responsibility is shared between several teams within propulsion and energy unit. Over time the responsibility scope has increased and includes concept to software development. Both application software and basic software for the traction battery is developed in-house. We are currently working in multiple platforms finalizing the work products as defined in ISO26262, and need some support with these activities.

Main functionality of the Traction Battery:

• Receive and store electrical energy (charge)
• Deliver electrical energy (discharge) to the high voltage loads
• State of Function Monitoring: Deliver storage status: state of charge (SOC) to the driver.
• Thermal control of the battery (function for optimizing battery life, reliability and performance).
• Controls the battery disconnection units
• Responsible for the HV battery cells data to work optimally

System name	Classification	SOP
Battery Management System	ASIL D

 The system safety criteria for the traction battery system are:

1. Compliance to management of functional safety ISO 26262-2.
2. Compliance to concept phase of functional safety ISO 26262-3.
3. Compliance to product development at the system level ISO 26262-4.
4. Compliance to product development at the software level ISO 26262-6
5. Compliance to production, operation, service and decommissioning ISO 26262-7.
6. Compliance to supporting processes ISO 26262-8.
7. Compliance to automotive safety integrity level (ASIL)- oriented and safety oriented analysis ISO 26262-9.

Timing

We wish to start this assignment as soon as possible.

Scope of Work

There are two main work packages that we would like to have support with and they shall be offered separately.

 Work package 1. SFMEA for battery system and BMS

To ensure compliance according to ISO 26262-4 a technical safety concept shall be done for the

battery system. Traction battery is a part in the high voltage system architecture including also high

voltage loads as inverters, thermal systems and DCDCs used to power supply low voltage loads.

The concepts on a high level are developed and a SFMEA shall be done in parallel with system level work to ensure all failure modes are covered.

 SFMEA for HV battery system functionalities:

1. Symmetrization and isolation faults
2. Keep voltage levels on high voltage bus
3. Voltage, temperature and current monitors of the HV battery cells
   1. Safety level 2
   2. Safety level 1
   3. Safety level 1 counter
4. Battery limphome at BMS HW related faults
5. Battery disconnection
6. Battery disconnection at crash
7. Protection against electric schock
8. DCDC control
9. Bank balancing
10. Temperature monitor

 Due to that battery SW is developed inhouse an additional technical safety concept shall be done for

the battery management system BMS, including battery ECU and sensors. Note that both

application and basic software module are done inhouse even if parts are bought by Tier1. HW is

done by Tier 1 that are responsible for the HW design based on HW safety requirements. The low

level design is under construction in cooperation with HW supplier and SW architects. The SFMEA is

expected to be done in parallel with the design work.

 For BMS SFMEA additional breakdown is needed and to be done on BMS system level. BMS

SFMEA includes both functional and non functional parts according below:

1. BMS design strategy for above functionalities
2. Power supply
3. Communication
4. Memory
5. MCU and external watchdog
6. Wake up

 Note that only major parts are described here additional functionalities might need to be added.

Work package 2. SW safety processes

SW development processes, work within a cross domain team to define central processes within

propulsion and energy department. To define these processes a checklist shall be done that is a copy

of ISO26262 requirements into a more understandable checklist. After that a template shall be done

that fulfilles the requirements from the checklist.  For some of the processe the checklist is already

done but for some of the both checklist and templates are remaining. For support needed see list

below:

1. Production release report checklist and template
2. Calibration data checklist and template
3. Configuration data checklist and template
4. SW safety analysis template
5. SW architectural design template
6. HW SW interface specification template
7. HW SW interface verification checklist and template
8. SW integration test template
9. SW verification report template
10. SW unit implementation checklist and template
11. SW environment checklist and template

 Prerequisites

We expect the candidates performing the assignment to have a degree in Electrical and Electronics Engineering, with experience in software development and software engineering, and deep knowledge in functional safety standard ISO26262, especially part4, part5 & part 6. Proven experience within this field is a must.
It is meritorious if the candidates have experience/knowledge of working within the HV-battery domain, or another part of the electrical driveline.