L3

30/07/26 Thu 10:35am

Intro to system engineering

importance → system requirements define measurable targets for design and validation

example ev power train requirements

• 0 -100 km/h acceleration $<$ 10 secs
• battery range $\ge$ 400 km per charge

Requirements help in:
bench-marking performance
ensuring component compatibility

trade-offs in system engineering

efficiency vs cost
performance vs weight
safety vs manufacturability

a well designed set of system requirement ensures an optimal balance.

Understanding an EV as a system

an EV consists of multiple interconnected components, including:

• battery pack
• motor & motor controller
• Power Electronics
• thermal management system
• braking system
• chassis & sensors
• communication networks

System Boundary of an EV

• the vehicle itself forms the system boundary

The System Perspective: Beyond Individual Components

• Analyzing individual components alone is not enough to predict full vehicle behaviour
• Subsystem interactions can cause emergent behaviours — Unexpected effect not seen in isolation.
• A holistic approach ensures seamless integration and optimal operation

Illustrative Examples:
Larger Battery

• Increases driving range
• Adds weight → impacts acceleration, braking, and structural intergrity
  Regenerative Braking
• Improves energy efficiency
• Must be balanced with mechanical braking for safety & stability across conditions
• Systems thinking ensures EV design is not just optimal at component level, but coherent, safe, and efficient as a whole.

System Success vs. System Failure

• Success:
  • Desired behaviour emerges as expected
• Failure occurs when:
  • Expected behavior doesn’t occur
    • E.x, EV expected to run 300 km only acheives 250 km due to unforseen power losses
  • Unexpected, undesirable behaviour occurs
    • E.g, Thermal-electrical interaction causing battery overheating

Introduction to System Engineering Process

• After grasping the definition and approach of systems engineering, the next step is to understand its step is to understand its structured process
• This methodology ensures a Logical, efficient development cycle for complex systems like EV powertrains
• Why it matters:
  Guides engineers through requirement definition, design, integration and validation
• Ensures each phase is aligned with system objectives, performance, and reliability needs

Systems Engineering Process

1. Requirements Engineering
   • Define and document clear, measurable system requirements.
2. Functional Analysis & Allocation
   • Break down system-level requirements into subsystems and components.
   • Ensure functional alignment across different domains.
3. Synthesis (System architecture development)
   • Design and integrate hardware & software architectures.
   • Ensure seamless operation of all components.
4. Verification & Validation (V&V)
   • Test & validate that the system meets design specifications.
   • Ensure efficiency, safety, and reliability through systematic testing.

Requirement Specifications for an EV Powertrain

Why Quantitative Specifications Matter?

→ Clear requirement engineering ensures performance, efficiency, and competitiveness in EV design.
→ Quantitative targets help in component selection and system optimization.

Example: Acceleration Requirement

• Specification: The EV must accelerate from 0 to 100 km/h within 8 seconds.
• Which ensures quick response for better drivability & market competitiveness.
• Requires sufficient torque & efficient power delivery from the motor & battery.

Example: Driving Range Requirement

• Specification: The EV should have a minimum range of 400 km per charge under standard test conditions.

Example: Gradeability Requirement

• Specification: The EV must maintain 40 km/h speed while climbing a 15% gradient with a full load.