Top 10 Technical Interview Questions for an EV Engineer

 

Job interview questions for an electrical engineer can be anywhere from basic to advanced concepts. Interviews are your chances to prove your expertise. Your skills and knowledge are put to the test you have gained over the years. But the interview ends with only a few questions and within an hour. 

Basic knowledge about electric vehicles will make you eligible for the role of an EV engineer. Initially, prepare yourself by searching what are the basic interview questions for an electrical engineer and learn domain-specific questions. We have compiled a set of electrical engineer technical interview questions that were asked during interviews. Our students have answered these questions and have been placed in many companies, including OLA Electric, TATA Technologies, and TATA Elxsi.

 

Below are the frequently asked interview questions for an EV Engineer.

 

What do you mean by an Electric Vehicle? What are the problems with EVs?

Electric vehicles are automobiles that utilise the power stored in a battery, driven by the motor, to set them in motion. There are different types of electric vehicles based on the degree to which it depends on the battery. A Battery EV has no IC (Internal Combustion) engine, whereas a hybrid electric vehicle uses both a battery and IC engine to power the vehicle.

The primary concern for EVs is the charging time. The time needed to fully charge the battery of the Tata Nexon EV car is 8 hours. Also, the lack of infrastructure support is another pressing issue to be addressed, i.e. we need sufficient charging stations for EVs in public places. 

 

What are the advantages of EVs?

The most important advantage of electric vehicles is their efficiency. The e-powertrain system offers high efficiency when compared to a transmission system with an IC engine. The efficiency of EVs is further increased with the aid of a regenerative braking mechanism. In this mechanism, the kinetic energy of the moving car is converted to electrical energy. 

 

Explain Regenerative braking

When the driver applies the brake in a conventional vehicle, the wheels in motion are forced to stop. Any moving object would possess some kinetic energy, and according to the law of conservation of energy, 'energy can neither be created nor be destroyed; it can only be converted from one form to the other'. So when brakes are applied, the wheels' kinetic energy is dissipated in the form of heat to the surroundings.

Under normal conditions, the motor transmits torque to the wheel when the driver accelerates. But when brakes are applied, the wheel turns the motor, and now the motor acts as a generator. The kinetic energy is converted to mechanical energy and is used to drive. The reverse process happens, and energy flows into the battery.

 

What are the forces to consider while designing the regenerative braking mechanism?

Designing a regenerative mechanism is quite complicated. This mechanism alone cannot provide the necessary braking force to the vehicle. So a combination of frictional braking force by disc and regenerative force is required. We need to divide the force in an optimised way to achieve the best result.

 

What is the simulation, and why is it required in the designing stage?

Simulation is the process of testing your model by applying real-world conditions. Engineers perform simulations with the help of software tools; this allows for knowing the failure points in the design without actually creating the prototype. By analysing the result, we can fine-tune our design and improvise its performance. This ultimately cuts down the cost of creating the prototype and arriving at the best solution with less time.

 

 

What is more dangerous between Over current and Short circuits? 

Short Circuit is more dangerous than an overload or overcurrent. By definition, overload is a condition when the voltage is higher than the rated voltage of the circuit or device or machine.

A short circuit is a condition in which, two or more conducting elements in a circuit are connected. In overloading conditions, the current is low, and the voltage is high. But in short-circuiting, the potential difference or voltage remains almost zero, but the current is high. This high flow of current generates heat that can even burn the insulator in the vicinity of the short-circuited area. 

 

What are the types of power converters that can be implemented in EVs? 

Power converters can be classified into two broad classifications. They are isolated and non-isolated power converters.

An isolated converter completely isolates the input and output by deploying a transformer. There is no physical connection here. Isolated converters like full bridge, half-bridge, flyback, push-pull and forward DC/DC converters can be used depending on the requirement. They are primarily used to step up or step down the input voltage.

Non-isolated converters are used when voltage needs to be stepped down to a small voltage. The five main converters in this group are buck, boost, buck-boost, cuk and charge-pump.

 

Explain the working principle of the Induction motor

The induction motor works on the principle of electromagnetic induction. Electromagnetic induction is a phenomenon in which an emf (electromotive force) is induced in the conductor placed in a changing electric field. In an induction motor, a conductor is placed in a rotating magnetic field. Initially, the conductor tries to resist the changing magnetic field. But later, it starts to rotate along with the rotating magnetic field.

 

What do you mean by the degree of hybridisation?

Hybrid electric vehicles utilise the combined power of a motor and IC engine to drive the vehicle. In some hybrids, the motor alone cannot drive the vehicle, and in some hybrids, they do. The percentage of contribution of the motor to drive the hybrid vehicle is called the degree of hybridisation. It can be calculated using a formula,

 

Degree of hybridisation = Motor power Motor Power + Engine Power 100 %

 

What do you know about OBC?

An OBC or On-Board Charger is a unit seeded inside the plug-in EVs. It converts the AC input voltage from the grid to a DC supply to charge the battery. It eliminated the necessity for an external converter.

The above-mentioned ten Interview Questions for an EV Engineer will give you an overall idea about the concepts that you need to learn.

Global EV sales have hit 6.6 million in 2021. By 2030, the Indian EV market is expected to sell 17 electric vehicles. The EV sector in India is likely to witness a huge investment of Rs 94,000 crore by 2025. Alongside the growth of the EV sector, many job opportunities are being created.

Skilled engineers with interests in automotive are the need of the hour to lead the EV industry. At Skill-Lync, we provide industry-relevant PG Programs along with placement training. Our placement training includes mock interviews, resume building and LinkedIn profile building. Get in touch with us to know more about courses.