Top Electric Vehicle Interview Questions With Answers Must Know

June 25, 2020November 17, 2022 CS Electrical And Electronics

Hello guys, welcome back to our blog. Here in this article, we will be discussing the top electric vehicle interview questions with answers, the most commonly asked EV interview questions, and by doing a lot of research we have collected these electric vehicle interview questions with answers.

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Electric Vehicle Interview Questions

01. What if fuel cells, replace the lithium-ion cells in electric vehicles?

Ans. Well guys the future of passenger and short-range vehicles (such as inner-city delivery vehicles) will be with battery-electric powertrains. While hydrogen fuel cell-powered electric vehicles are also believed to have applications in fields such as largely focused on using hydrogen fuel cells for larger scale, long-distance transportation, heavy vehicles, etc.

If one of your primary objectives is to protect the world, battery electric vehicles are much more energy-efficient than hydrogen fuel cell-powered vehicles when you think of the series of steps between power generation and propulsion. With a battery-electric vehicle, once the electricity is produced (from a renewable source) the method of delivering this to your vehicle charging site means that about 5% of it is lost. And during charging and discharging the lithium-ion battery loses another 10%. Eventually, the motor makes wastes another 5% when the vehicle is being operated. That causes a total loss of 20%.

If the hydrogen fuel cell is utilized, you must preferably convert the electricity to hydrogen through electrolysis, which has only 75% efficiency. The gas then must be condensed, chilled, and thrilled, losing another 10%. The fuel cell operation of converting hydrogen back to electricity is just 60% efficient, behind which you hold the same 5% loss from operating the vehicle motor as for a battery-electric vehicle. The overall total is a 62% loss — more than three times as compared to Battery one.

To arrange it in another form, for every kW of electricity supply, you get 800W of energy for a battery-electric vehicle but just 380W for a hydrogen fuel cell vehicle — smaller than half as much. That’s a massive inefficiency if you’re wishing for a greener tomorrow and this doesn’t even account for the reality that 95% of hydrogen is presently generated from fossil fuel sources.

02. Why electric vehicle is expensive compared to fuel combustion engines?

Ans. While electric cars arrive with more irregular moving parts than diesel-powered or petrol automobiles, the considerably costly part is the lithium-ion cells. The lithium-ion battery pack makes for more than 50% of the price of the car. Replacing or repairing batteries is expensive, which is one cause why insurance compensations are higher.

03. What are the types of electric motors used in electric vehicles?

Ans. The most popular motors used in electric vehicles by different manufacturers are:

Induction motor
Permanent magnet synchronous motor
brushless dc motor

04. How much distance normal EV can cover once it is fully charged?

Ans. Present electric vehicles travel approximately 250 miles on a charge, and though there are some electric vehicles, for example, Teslas, that can do approximately 350 miles on a full charge. Numerous automakers have revealed techniques to convey to demand for electric vehicles that promise more extended range and actually faster charging.

Tata Motors newly launched the revised long-range arrangement of Nexon EV named Nexon EV Max in the market. It is open in XZ+ and XZ+ Lux variants and has a licensed maximum driving span of 437 km.

05. What kind of motor control technique will be used in EV?

Ans. At present, BLDC, Induction motor, and PMSM motors are very popular for electric vehicles and the control strategies used for these motors are DTC and FOC.

Direct torque control (DTC) is one technique utilized in varying-frequency drives to handle the torque (and therefore ultimately the speed) of motors like BLDC, PMSM, Induction motor, etc. This concerns computing an estimation of the motor’s torque and magnetic flux based on the measured current and voltage of the motor.

Field-Oriented Control (FOC), also understood as vector control, is a strategy utilized to handle AC induction motors (ACIM) and Permanent Magnet Synchronous Motor (PMSM). Field-Oriented Control (FOC) delivers good managing capability over the maximum torque and the speed ranges.

06. How much time it will take to charge the EV battery pack?

Ans. The major reason is that charging EVs is slow. While drivers today are habituated to filling their gas tank or fuel tank in just five minutes or less than it, EVs, relying on the scope and specifications of the battery, generally take at least 30-40 minutes to get 80 percent of charge at the quickest charging stations out there. Still, some research is going on fast-charging stations and solar EVs.

07. Why lithium-ion cells are used in EV?

Ans. Lithium-ion batteries are presently utilized in most EVs or electric vehicles because of their increased energy per unit mass compared to different electrical energy storage methods. They even hold an increased power-to-weight ratio, suitable high-temperature performance, increased energy efficiency, and lower self-discharge.

08. What is a battery management system in an electric vehicle?

Ans. BMS or Battery Management System plays a very important role in electric vehicles. To monitor and maintain the battery pack for proper usage, a BMS is needed. The main functions of BMS are

Cell balancing: equalizing the Soc and voltage of each cell
Protecting the battery pack from overcurrent, overvoltage, & under-voltage conditions
Monitoring the temperature, & isolating the BMS if the temperature exceeds
Monitoring current, voltage, SoC (state of charge), SoH (state of health)
Efficient charging & discharging

09. What are the advantages of using electric vehicles compared to fuel combustion engines?

Ans. There are various benefits of electric vehicles when compared to fuel combustion engines, they are no fuel like petrol and diesel is needed, no noise pollution, no release of toxic elements, and it offers smooth driving.

10. What is the battery pack rating of an electric bike?

Ans. The battery pack rating of an electric bike is 47-49 volts and 25-30 Ah (rated capacity).

11. What is the C rating in the battery?

Ans. A C-rate is a measurement of the rate at which a battery is discharged comparable to its full capacity. A 1C rate indicates that the discharge current will discharge the whole battery in 1 hour.

For a battery with a capacity of 100 Ah, this correlates to a discharge of 100 Amps of current. A 5C rate for this battery will be 500 Amps, and a C/2 rate will be 50 Amps. Likewise, an E-rate represents the discharge power. A 1E rate is the discharge power to discharge the whole battery in 1 hour.

12. Top 10 electric cars in the world?

Ans. The top 10 electric cars in the world are;

Hyundai Ioniq Electric
BMW i3
Tesla Model X
Volkswagon e-Golf
Renault Zoe
Tesla Model S
Nissan Leaf
Hyundai Kona Electric
Jaguar I-pace
Kia e-Niro

13. What is ECU in electric vehicles?

Ans. An electronic control unit (ECU), also known as an electronic control module (ECM) in automotive electronics, is an embedded system that regulates one or more electrical systems or subsystems of a vehicle.

Depending on its role, an ECU gets data from various sections of the car. When a passenger presses the door lock/unlock button on a car door or a wireless key fob, for example, a door lock ECU receives input. Crash sensors and sensors that detect when someone is seated in a specific seat would provide input to an airbag ECU. In addition, forward-facing radars that detect when the vehicle is approaching an impediment too quickly would provide input to an automatic emergency braking ECU.

14. What are DTC and FOC control methods?

Ans. Field-oriented Control (FOC) and Direct Torque Control (DTC) are the popular vector control methods of the drives which mainly consist of electric motors.

Field-oriented control (FOC) has a special configuration with the linear controllers and the pulse width modulation (PWM) technique to control the load voltage of the electrical motor. This FOC is mainly used for the control of the permanent magnet synchronous motor and ac induction motors and it has the best control capability over the full torque and speed ranges.

Direct torque control mainly uses two-loop methods to control the drives such as the speed control and the torque control loops which will work together with the motor model. The DTC will assume the torque values and it will compare to the values of the drives then the operation of the DTC will be started after comparison. The comparator output will decide the output of the DTC. The DTC is one of the easiest and most economical controls of the drives.

15. What is cell balancing and why it is needed?

Ans. To preserve battery performance over a prolonged service life in a large-format battery system, it is normally required to achieve a charge balancing approach to account for differences in cell performance. An efficient cell_balancing system preserves the desired level of battery production throughout the life of the battery with a proper safety margin, without adding unnecessary cost, weight, or complexity.

Balancing is the process of equalizing the level of charge in lithium-ion cells on a cell-by-cell basis. There are two ways to do cell balancing such as active cell balancing and passive cell balancing.

16. How to avoid thermal runaway in an electric vehicle?

Ans. When the lithium-ion batteries/cells get overheated and catch fire due to various causes (such as lack of cooling system, overcharging, short circuit) is known as a thermal runaway in electric vehicles. Thermal runaway starts when the heat developed within a battery surpasses the quantity of heat that is dispersed to its surroundings.

01. Determine battery requirements for vehicle performance & fuel consumption / range targets.
02. Get a first battery design meeting the requirements starting from a database of commercial lithium-ion cells.
03. Design & analyze electrochemical reactions & detailed geometry of battery cells.
04. Calculate 3D thermal, fluid & electrochemical properties of battery modules & packs.

17. What are the different types of algorithms used for SoC estimation?

Ans. The different types of algorithms used for SoC estimation are;

Kalman filter, Extended Kalman filter, unscented kalman filter
Voltage method
Coulomb counting
Fuzzy logic
Artificial neural network Or ANN

18. What is SoH or state of health?

Ans. When compared to a new battery, the State of Health is a “measurement” that represents the general state of the battery and its capacity to achieve the required performance. Charge acceptance, internal resistance, voltage, and self-discharge are all aspects considered. It is a measure of the battery’s long-term capabilities and provides an “indication,” rather than an absolute measurement, of how much of the battery’s possible “lifetime energy throughput” has been spent and how much remains. It can be compared to the “odometer” display function on a car, which shows the number of miles driven since the vehicle was purchased.

The SoH of a battery is usually 100 percent when it is manufactured and gradually decreases with time and use. However, a battery’s performance at the time of production may fall short of its standards, resulting in an initial SoH of less than 100%. Driver patterns, driving aggressiveness, climate, cabin thermal dynamics, and infrastructure are the most significant contributors to battery deterioration, with driver patterns and climate being the most significant.

The SOH is a measure of the battery’s state in comparison to a new battery and indicates when it has reached the end of its life cycle.

19. What is the pyro switch in an electric vehicle?

Ans. It’s a high-voltage positive battery terminal fuse that bursts and permanently disconnects the electrical connection to prevent a short circuit or fire in the event of an automobile accident or crash. The positive terminal of the battery is unplugged at the same time, causing the automobile to crash.

20. How electric vehicle works?

Ans. The drivetrain of an electric vehicle gives the power to move the wheels. The powertrain includes both the motor and the drivetrain system.

The power generated by the motor is transferred to the drive wheels with the help of a gearbox with a simple single-speed transmission as the motor is much more efficient.

Even achieving the reverse gear is quite easy in an electric car by just changing the order of the power phase. Here an electric car transmission is only needed for reducing speed and its associated torque multiplication.

In the tesla, this is accomplished using a state-of-the-art algorithm with help from sensors and controllers. Tesla has replaced a complex mechanical hardware system with smart, responsive software.

This was about “Electric Vehicle Interview Questions“. I hope this article may help you all a lot. Thank you for reading.

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