How can powertrain advances deliver lighter EV engines?
How can technical advances on the powertrain side deliver lighter, more compact engines for electric vehicles? Louise Davis asks an electrification innovator how his team is tackling this task
Vitesco Technologies’ website proudly declares that the firm is “pioneering the powertrain electrification”. What it might also be doing is pioneering advances in lightweighting, as Gerd Rösel, the company’s Head of Innovation Electrification Solutions, explains. “The weight of a vehicle plays a crucial role in its efficiency. Less mass means less power is required to propel the vehicle,” begins Rösel. “This is especially important for battery electric vehicles (BEVS), where achieving a higher range necessitates larger batteries, which in turn increases weight. Our simulation indicates that for every 100kg of weight, an additional 2.3% of power is required for a D-segment vehicle,” he adds.
Rösel is keen to point out that the electrification expert’s focus isn’t just on making engines lighter: for Vitesco Technologies, the overarching aim is to enable cleaner, greener vehicles. “Our primary focus is on reducing CO2 emissions to minimise the environmental impact of individual mobility. But reduction of weight is very often a resulting effect,” Rösel notes.
So, what sort of technologies and methodologies can be applied to achieve those dual goals of lighter and greener? “Achieving lower emissions often involves using new materials, innovative product designs and different electric motor topologies. Parallel to that, efficiency is another critical factor in reducing weight and costs,” states Rösel. “By improving the efficiency of the electric motor and electronics, other components such as the battery can be reduced in size and weight while maintaining the same driving range. And as a third aspect, greater integration of components into complete systems can further reduce both weight and cost.”
COMPACT COMPONENTS
Vitesco Technologies offers an array of powertrain solutions that are lighter and more compact than ever before, and Rösel reports that these end products are a direct result of continual R&D. He says: “Looking at our products, they have become increasingly compact with each successive generation. For instance, our integrated axle drive, Electronics Motor and Reducer (EMR), saw a weight reduction of up to 25% from the third to the fourth generation. In absolute numbers, it is a double-digit kg reduction in weight at only one component.” Although Rösel may make such reductions sound easy, it’s noteworthy that genuine improvements in lightweighting often come like this; incrementally, rather than in revolutionary leaps.
EMR4 is the fourth generation of this particular axle drive and it’s a highly integrated, three-in-one drive platform, consisting of an electric machine, power electronics and a gearbox. The fourth version saw new technologies and comprehensive industrialisation know-how applied to make the solution more efficient and powerful. The company says that due to its very compact dimensions, low weight, high efficiency and ease of vehicle integration, the EMR is one of the most successful Tier 1 axle drive systems on the market.
The product is certainly being embraced by those automakers searching for smarter, lighter powertrain solutions. The EMR3 variant is powering the Honda CR-V e:FCEV, which is being marketed in the USA and Japan initially. This is the first time that one of the company’s drive systems will be integrated into a hydrogen fuel cell electric vehicle.
And the latest version is proving even more popular: Vitesco Technologies received a massive €2 billion order to produce around three million units of the EMR4 for a forthcoming EV from Hyundai. The order was so big that the company has recently opened a new, 2,800m2 manufacturing space at its Icheon, South Korea site to produce the units. The version produced for Hyundai will be a 400V system with a nominal power of 160kW.
The abovementioned size and weight reduction advances are undoubtedly impressive, and of course raise the question of ‘if such a reduction can be achieved with just one component, what else can be achieved via multiple other components?’ Naturally, this is an area that Rösel is also giving much thought to: “Yes, we have achieved excellent, tangible progress so far, but our development efforts do not stop there. Our ongoing goal is to make components even more compact in future generations.”
INDIVIDUAL MEASURES, OVERALL GAINS
To protect Vitesco Technologies’ IP, Rösel can’t share detailed news on exactly what he will be working on next. But he does offer a hint as to areas of interest for the firm’s R&D team: “As well as the bigger, full-component advances, individual small measures can also lead to weight loss in total.” Such as? “For example, new electrical/electronic (E/E) architectures and the switch to a zonal structure of control units make it possible to reduce the amount of individual and distributed ECUs,” answers Rösel. “In addition, wireless technologies and functional integration of systems also lead to reduced complexity, which has a natural knock-on effect on weight,” he adds.
Triple threat
As well as the axle drive product discussed in the main article, in June 2024, Vitesco Technologies announced another three-in-one solution: its new Rotor Lock Actuator. The module for electric vehicles includes a park lock function, precise rotor position sensing and (optionally) the brush system for externally excited synchronous machines (EESM). This reduces complexity, packaging space on the e-axle and costs for customers.
To secure the parking position, the majority of EVs use a mechanical park lock in the reducer gearbox in addition to the park brakes at the wheels. This takes up considerable space in the vehicle. The rotor lock approach relocates this park lock functionality from the gearbox to the rotor shaft of the e-machine, creating a more streamlined and cost-effective system design.
The end-of-shaft position on the rotor enables a smaller actuator, which can be easily integrated into the vehicle’s drive. This high degree of mechatronic integration minimises the space required in the vehicle, leading to a more compact packaging. Furthermore, this new position facilitates the integration of further functions in the module, such as the brush system for EESM as well as the inductive Rotor Position Sensor, which eliminates the need for separate control units, sensors and harnesses.
