Career in Hybrid Electric Vehicles - Drive Development

This is a multi-disciplinary field, in the product development domain you need to have a lot of system knowledge to work in this field. 

• Mechanical: Deals with system and component design, working with simulation and testing, vehicle calibration and testing. 

• Electrical: Electric system/motor development, developing and designing battery systems, voltage systems, power electronics. Along with developing the controllers for the batteries and the motors.

• Chemistry/materials: Battery cell development

• Software: Controller software, component, and supervisory levels

• Compliance with standards, functional safety, electrical standards, and HV safety. Engineers can from a variety of fields - Mechanical, Electric, Computer Science. 

Case study: P0 hybrid

Parallel Zero Level Hybrid is one of the basic architectures to make a vehicle hybrid, and they are also known as Micro-Hybrid Systems and Start-Stop technology, for example, the Saturn by General Motors, Mahindra Scorpios has a micro-hybrid badge, as well as many Audi’s.

The system shuts off the engine when it is idling this will put the engine at 0 speed so it will not use fuel. It is beneficial in stop-and-go environments, like traffic blocks, when the car frequently needs to brake, as this wastes fuel and generated emissions with conventional vehicles. They also have boosting and regenerative braking depending on the battery size and motor size. It can provide a boost of power for high acceleration event for a short time.

Mahindra Microhybrid Systems

The highlighted portion is a Belted Starter Generator (BSG) and a lead-acid battery that is powering the motor, which is controlled by the Electric Management System (EMS). The engine is represented in blue with the four cylinders. They are connected and controlled by the LIN and CAN networks, which you can read about here.

There are two different modes of operating Mahindra Microhybrid systems. One is used for start-up and boosting which means that if you need to start the engine you need to provide torque or power from the BSG back to the engine, so it takes the power from the battery back to the BSG and that is provided to the engine, so that is used for engine start-up. For example, if you let go of your foot form the brake-pedal the engine will startup. This motor provides that instant torque to start the engine and it can also be used it you want to overtake someone, in which case, you increase the accelerator-pedal input, and at the instant, the electric motor will provide extra torque and extra power to the system. 

Regenerative braking takes energy from the wheels to the engine and puts the energy into the battery to charge it In which the pathway that is mentioned above is reversed, through the engine putting the energy into the electric motor and into the battery. If you were to brake the vehicle, the energy will be stored in the battery. 

Product development cycle

The product cycle begins with the requirements, for example, the requirements of the customer for the vehicle. Then that needs to be converted into a system design, for example, how it should look, and what features it should have. After that, it moves into the component design, for example, how the system will be designed, then implementation such as making the parts. After this, it needs to be tested;  unit testing, integration testing, and system testing. 

This course focuses on System Design, in which we analyze how we would convert the requirements of the client into system designs. By simulating the system design can understand if system design works as intended and saves us time and money from having to create a part from scratch. 

System design in P0 hybrid. 

Motor generator unit - A normal engine has an alternator that is connected to the engine converting some of the energy back into electric energy to keep the electric units in the vehicle running. In P0 hybrids, this is replaced by a belted starter generator or belted alternate starter, which provides power to the engine and it can also take power from the engine. This is generally a 12V-48V system. 

Case study: System design

• Performance-based design has requirements in terms of performance such as acceleration, fuel economy, We need to know what the inputs are, what the engine operating conditions are, and the starting dynamics. You will need to know the time delay between the vehicle coming to a complete stop and the engine shutting down. You will need to understand what the boost required by the customer is, and if it’s plausible with the battery and engine at your disposal.
  Since this is an electric motor you will need to know what a torque-speed curve or a power curve is, which plots speed against torque. An electric motor provides max torque from the get-go and slowly depreciates as the speed increases. You will have to know the maximum speed that you can run the motor at while also understanding the efficiency at all the different operating points, along with the inertia of how much torque and power will be required to spin the vehicle. 

• Battery: You need to know the operating voltage is, the capacity is, you will have to understand if the batteries are connected in series or in parallel how quickly you can charge and discharge the battery, what the efficiency is at those rates. Battery cells changes with the State Of Charge. You will have to know what the operating voltage is and the efficiency of these parts, along with the amount of current they can provide.
  Since this is a BSG, you will have to take into account the gear ratio, belt, and tension specifications. 

How to get into this domain?

Gain relevant knowledge. Through colleges or through online courses such as these. Following which you will need practical experience, which you can get work on industry projects, like the ones Skill-Lync provides for our students, you can follow this up by entering into a company and developing hands-on experience. This is a multi-specialty domain, there is a lot of employment opportunities and since this is still evolving field there are a lot of new discoveries being made every day that change the game, you will need to have awareness about current affairs.