Hero Electric Powertrain Engineer Interview: Rounds, Questions and Preparation

What the job involves

A Powertrain Engineer in the EV sector designs, integrates, and validates electric drivetrain systems, including motors, motor controllers, transmissions, and battery interfaces. Day to day, you may size components, run simulations, test prototypes on dynamometers, analyse data, and work with suppliers to meet performance, efficiency, and cost targets. At companies like Hero Electric, you would help develop affordable, reliable electric two- and three-wheelers for Indian road conditions.

Role and EV powertrain fundamentals

1. 1

   What are the main components of an electric powertrain in an e-scooter, and how do they work together?

   Cover battery, BMS, motor controller, motor, and transmission. Explain power flow from battery to wheel and the role of each component.

2. 2

   Compare BLDC and PMSM motors for a Hero Electric-type e-scooter. Which would you choose and why?

   Discuss efficiency, cost, torque density, control complexity, and maintenance. Relate to Indian cost-sensitive and urban driving conditions.

3. 3

   How do you calculate the torque and power required for a two-wheeler to climb a 10-degree slope at 20 km/h?

   Use road load equation: force = rolling resistance + aerodynamic drag + gradient force. Then power = force x velocity, and torque = force x wheel radius / gear ratio.

4. 4

   What is the role of the motor controller, and what is field-oriented control?

   Explain that the controller regulates current to the motor based on throttle and feedback. FOC controls stator current vector to achieve smooth torque and high efficiency.

Battery, BMS, and energy management

1. 5

   How does a battery management system protect and optimise a lithium-ion pack in an e-scooter?

   Mention cell balancing, overcharge/discharge protection, temperature monitoring, SOC estimation, and communication with the controller.

2. 6

   What factors affect the range of an electric two-wheeler, and how can you improve it?

   List battery capacity, motor efficiency, weight, aerodynamics, tyre pressure, driving style, and temperature. Suggest improvements like regenerative braking, lightweight materials, and efficient control.

3. 7

   Explain the difference between SOC and SOH. How would you estimate them?

   SOC is remaining charge, SOH is battery health. Methods: voltage lookup, coulomb counting, impedance tracking, and model-based estimation.

4. 8

   What safety considerations are critical for a high-voltage battery pack in Indian conditions?

   Discuss thermal runaway, IP67 sealing, vibration resistance, overcurrent protection, and compliance with AIS-156 standards.

Practical scenarios and problem solving

1. 9

   During a test ride, the e-scooter loses power on inclines. How would you diagnose the issue?

   Check battery voltage sag, controller current limit, motor temperature, and gear ratio. Use CAN logs to see if the controller is derating due to thermal or current limits.

2. 10

   You need to reduce the cost of the powertrain by 15 percent without affecting performance. What steps would you take?

   Consider motor redesign with fewer magnets, controller optimisation, local sourcing, reducing cable length, and integrating components. Validate with simulation and testing.

3. 11

   How would you test and validate a new motor controller before production?

   Outline bench tests for efficiency, thermal performance, and fault handling, then vehicle-level tests for driveability, EMI/EMC, and durability. Follow a test plan with pass/fail criteria.

4. 12

   What data would you log during a dyno test of an electric motor, and how would you analyse it?

   Log voltage, current, torque, speed, temperature, and efficiency. Plot efficiency maps, torque-speed curves, and thermal trends to identify losses and validate against targets.

Behavioural and HR questions

1. 13

   Why do you want to work in the EV powertrain domain, and why Hero Electric?

   Show passion for clean mobility, awareness of India's EV growth, and alignment with Hero Electric's affordable and practical products. Mention specific models or initiatives.

2. 14

   Describe a project where you worked in a team to solve an engineering problem. What was your role?

   Use STAR method: situation, task, action, result. Highlight collaboration, technical contribution, and learning. Quantify results if possible.

3. 15

   Tell me about a time you faced a failure or setback in a project. How did you handle it?

   Be honest, focus on what went wrong, how you analysed it, and what you changed. Show resilience and a learning mindset.

4. 16

   How do you keep up with the latest developments in EV powertrain technology?

   Mention sources like SAE papers, IEEE journals, EV forums, YouTube channels, and online courses. Give an example of a recent advancement you found interesting.