GKN Automotive Focuses on Powertrain Developments for EVs

Examines battery systems, vehicle range and charge speed

GKN’s modular and scalable electric drive (eDrive) system can fulfil customer requirements for a wide range of vehicles.

As the world shifts towards sustainable energy solutions, the demand for electric vehicles (EVs) continues to increase, and at pace. This transition impacts the priorities of those throughout the industry—from OEMs to suppliers—as traditional automotive components are being replaced by electric motors, battery systems, power electronics, and thermal management systems.

For us, as a Tier One supplier, it comes down to making suitable choices. Across the range, we must prudently decide where to add value, which components to manufacture in-house or contract out, and which technologies we want to invest our knowledge and capital into.

At present, the three main areas of focus in the industry are: battery systems and optimizing range and charge speed; the charging system, both inside the vehicle and the charging infrastructure; and the motors and inverters within the driveline.

The question of efficiency feeds into every area of research and development within the EV industry. Efficiency is key to driving greater performance and enhanced sustainability. Put simply, the development and improvement of EVs comes down to its ability to efficiently convert battery energy into miles travelled.

Our key areas of focus are the efficient generation of torque using that energy and transferring that torque to the individual wheels.

Torque generation involves the transformation of energy in the battery into torque in the driveline system. For a battery EV, this consists of the inverter, motor and reducer which convert electrical energy into mechanical.

Inverters convert DC from the batteries into AC current for the motors. While this is a seemingly simple concept, the field of inverters demonstrates the speed at which the industry has needed to move forwards, as research finds new efficiencies and consumer demand evolves. The latest inverters offer a power output increase, as well as an increase in power density and power-to-weight ratio increases. These lead to faster charging times, decreased battery sizes, and improved performance.

More than 10 years ago, inverters typically offered around 110 V technology. Now, the most widely available technology is 400 V, with an increasing number of manufacturers looking to 800 V, and beyond.

As it stands, the adoption of 800 V systems looks to be slower than 400 V systems, due to the costs associated with the Silicon Carbide inverters used for an 800 V system. However, Gallium Nitride could follow Silicon Carbide into the power module market, which could drive down costs and increase capabilities.

The opportunities and challenges of 800 V systems also impact motor technology. While the rotor design for the most part will be like a 400 V system, it requires—amongst other things—different insulation design on the stator as well as different terminal racks.

Within the torque generation system, the advancement of electric motors is pivotal in enhancing the driving experience, extending range, and accelerating the transition to sustainable transportation.

In recent years, significant progress has been made in EV motor technology, covering everything from efficiency to power density. Motor designs, such as permanent magnet synchronous motors have dominated, utilizing high-strength magnets and winding configurations to achieve higher torque output and efficiency.

Like internal combustion engines, electric motors generate a considerable amount of heat during operation. In EV motors, resistance encountered in the motor generates thermal energy, resulting in a loss of energy in the system through the dissipation of this heat.

To improve the efficiency, longevity, and performance of EV motors, it is essential to reduce and manage these heat losses. As such, we have solutions for active oil-cooled motors that enable delivery of the same power output as larger units, but in a smaller, lighter, more affordable package.