Auto-Sector Interview Preparation

Designs, develops and tests electric vehicle systems such as batteries, motors and power electronics.

A vehicle driven by one or more electric motors using energy stored in a battery.

A cell is the basic unit; modules group cells; a pack groups modules into the full battery.

A rechargeable battery using lithium ions, common in EVs for its high energy density.

A Battery Management System, which monitors and protects the battery.

The remaining charge in a battery as a percentage of its capacity.

The battery current capacity relative to when it was new.

Kilowatt-hour, the unit of battery energy capacity.

To convert electrical energy into mechanical motion to drive the wheels.

Recovering kinetic energy during braking and storing it back in the battery.

A device that converts DC from the battery into AC for the motor.

It steps the high-voltage battery down to power the 12V systems.

It converts AC grid power to DC to charge the battery.

AC charging uses the on-board charger; DC fast charging feeds the battery directly.

A defined plug and protocol such as CCS, CHAdeMO or Type 2.

The distance the vehicle can travel on a full charge.

A driver worry about running out of charge before reaching a charger.

A unit of power that indicates motor output or charging rate.

The traction circuit operating at hundreds of volts to drive the motor.

High voltage can be lethal, so isolation, interlocks and procedures are essential.

Controlling the temperature of the battery, motor and electronics for performance and safety.

A Permanent Magnet Synchronous Motor, common in EVs for high efficiency.

A brushless DC motor that is efficient and low maintenance.

An AC motor without permanent magnets that is robust and cost-effective.

The energy stored per unit of mass or volume.

Its typical operating voltage, about 3.6 to 3.7 volts.

An uncontrolled rise in battery temperature that can cause a fire.

A hybrid uses an engine plus a motor; a battery EV uses only electric power.

One full charge and discharge of a battery.

The charge or discharge rate relative to the battery capacity.

A safety circuit that disables high voltage if a connector is opened.

To connect or disconnect the high-voltage battery from the system.

Energy is total capacity in kWh; power is the rate of delivery in kW.

A protective device that breaks the circuit during a fault.

Equalising the charge across cells for safety and full usable capacity.

The system of battery, power electronics and motor that drives the vehicle.

The ratio of mechanical output power to electrical input power.

To remove heat and keep cells within a safe temperature range.

A common AC charging connector used in many regions.

Zero tailpipe emissions, high efficiency, low running cost and instant torque.

It monitors voltage, current and temperature, balances the cells and limits charge and discharge to safe limits.

Through coulomb counting and voltage-based models, often combined with a Kalman filter.

Calendar ageing, high temperature, deep cycling and high charge rates.

The motor acts as a generator, converting kinetic energy to electrical energy fed back to the battery.

Limits from battery acceptance, motor capacity and the need for friction braking at low speed and high deceleration.

By varying the frequency and amplitude of the AC using pulse-width modulation.

A method that controls motor torque and flux independently for smooth, efficient operation.

For their high efficiency, power density and good torque, despite the magnet cost.

DC bypasses the on-board charger and feeds the battery directly at high power.

Cell chemistry, temperature, state of charge and thermal management; high rates cause heat and degradation.

It is the power profile during charging, which drops at higher state of charge to protect the cells.

It heats or cools the cells to keep them in the optimal temperature band for power and life.

Contactors connect the pack and the pre-charge limits inrush current to protect the system.

De-energise per procedure, verify zero voltage, use insulated PPE and tools and follow lockout.

Liquid cooling is more effective and uniform; air cooling is simpler and cheaper but limited.

Passive bleeds energy from high cells; active transfers energy between cells.

An internal short, overcharge or overheating; mitigated by BMS limits, cooling and pack design and venting.

Divide the usable energy in kWh by the consumption in kWh per kilometre.

Cold weather, high speed, HVAC use, terrain and aggressive driving.

It rectifies and conditions AC grid power into controlled DC for the battery, managed by the BMS.

It powers the 12V network and accessories from the high-voltage battery.

PMSM is more efficient; induction avoids magnets and is robust and cheaper but slightly less efficient.

Electric motors produce maximum torque from zero speed without a clutch or gears.

It detects loss of isolation between the HV system and chassis to prevent a shock hazard.

Run controlled charge and discharge cycles and measure capacity, internal resistance and balance.

A conductor that connects cells and modules to carry high current.

NMC offers higher energy density; LFP offers better safety, life and cost.

Typically over the CAN bus, sharing state of charge, limits, faults and temperatures.

A contactor stuck closed keeps the HV live, so the system must detect and respond to it.

Reduce mass and drag, improve motor and inverter efficiency and optimise thermal and regen strategies.

Onboard AC charging uses the vehicle charger; offboard DC charging converts power externally.

A blending controller uses regen first and adds friction braking as needed for the total demand.

To limit inrush current to the inverter capacitors when the high voltage is connected.

Measure state of health and consumption, check thermal behaviour and rule out driving and HVAC factors.

Standards such as the IEC charging standards and the ISO 26262 functional-safety framework.

Use liquid cooling sized for peak heat, even flow distribution and BMS-controlled charge limits by temperature.

Track capacity fade and resistance growth, model degradation against cycles and temperature, and project to the end-of-life threshold.

It detects abnormal cell behaviour, isolates the pack and controls cooling, while the design adds thermal barriers and venting.

Reduce mass and drag, improve drivetrain efficiency, optimise thermal and regen and tune the control strategies.

Reducing the magnetic flux lets the motor run above base speed at constant power.

Use insulation monitoring, isolate sections, measure resistance to chassis and locate the leakage path safely.

Trade chemistry, pack design and thermal and BMS controls against the application risk and range needs.

Define the safety goals and ASIL, do hazard analysis, design safety mechanisms and verify with tests and fault injection.

Follow a temperature and state-of-charge dependent charging curve that limits current to keep cells safe.

Map the losses in the battery, inverter, motor and gearing, then improve the largest contributors.

Check the balancing function, cell matching, temperature gradients and any weak or high-resistance cells.

Coordinate regen and hydraulic braking smoothly while respecting battery limits, ABS and a consistent pedal feel.

Pre-condition and heat the pack, limit charge and discharge until warm, and manage range expectations.

Optimise the switching frequency, use suitable semiconductors such as silicon carbide and improve layout and filtering.

Errors cause range and protection issues; they are minimised with sensor accuracy, model calibration and filtering.

Include insulation monitoring, interlocks, contactors with pre-charge, fusing and clear service de-energisation.

Match the motor type and pack voltage to the torque, power and efficiency needs while controlling cost and packaging.

Analyse usage data, charging habits, temperatures and state-of-health trends to find and address the cause.

Match cell resistance, design low-impedance busbars and monitor for imbalance.

Model consumption from mass, drag, rolling resistance, drivetrain efficiency and a drive cycle, then verify on test.

Detect it via voltage and current checks, alert the driver and follow a controlled safe-state procedure.

Better cooling allows higher charge rates with less heat and degradation, extending battery life.

Use balancing where justified, monitor per-cell data over CAN and balance during charge and rest.

Weigh charging speed, cost, grid impact and use case to set the supported charging strategy.

Define requirements, select the battery, motor and electronics architecture, model and simulate, validate components and integration, and verify safety and performance.