Posted on 21st October 2025

How a dual-drive EDU, design-to-CO₂e thinking, and battery innovation converge to deliver <10 kWh/100 km energy demand and >94% system efficiency – ready for vehicle application.

Dipl.-Ing. (FH) Wilhelm Vallant, Product and Business Development Manager Transmission & E-Axle, AVL List GmbH

The automotive industry is at a turning point, and OEMs face a dual challenge: delivering uncompromised performance while meeting stringent sustainability and cost targets. AVL’s latest technology demonstrator addresses this challenge head-on, setting new benchmarks for energy efficiency, lifecycle CO₂e reduction, and system integration.

The project’s objectives were clear: achieve an Electric Drive Unit (EDU) average cycle efficiency of over 94 % (WLTP) and reduce vehicle energy demand to below 10 kWh/100 km. These goals demanded a holistic approach – optimizing the EDU, battery systems, and vehicle aerodynamics in unison.

At the heart of the demonstrator vehicle lies a dual-motor EDU featuring two Permanent Magnet Synchronous Machines (PMSMs), a compact single stage spur-gear transmission, and a dual Silicon Carbide (SiC) inverter. One motor operates continuously for maximum efficiency, while the second engages only for boost and recuperation via a dog clutch. This intelligent operating strategy minimizes losses across real-world duty cycles. Using AVL’s Powertrain System Optimizer (PSO) and AI-driven Design of Experiments methodology ensured optimal sizing and control strategies. The result: validated average EDU efficiencies of 94.1 % in real-world testing and 94.4 % in customer-specific cycles.

Efficiency alone is not enough. AVL integrated lifecycle CO₂e considerations from concept to production, applying a “Design-to-CO₂e” methodology to further reduce material usage, cutting system weight, cost, and lifecycle CO₂e.

Two battery concepts complement the EDU: A performance-optimized pack leveraging silicon-anode/NMC811 chemistry, advanced evaporative side cooling, and cell-to-pack integration for maximum energy density.

A cost-optimized LFP pack featuring cylindrical cells, multifunctional cooling plates, and CO₂-based evaporative cooling – eliminating the need for a separate low-temperature circuit and reducing system complexity.

Vehicle-level efficiency was enhanced through a fully virtual aerodynamic optimization process, achieving a 23 % drag reduction in simulation and 20 % in coast-down testing – critical to meeting the sub-10 kWh/100 km energy demand target.

This demonstrator is more than a showcase; it’s a blueprint for scalable, production-ready solutions. By combining cutting-edge EDU design, battery innovation, and lifecycle sustainability, AVL empowers OEMs to deliver electric powertrains and complete vehicle designs that excel in efficiency, performance, and environmental responsibility.

 

Range anxiety is history! Get up to speed here on the hottest topics in electric powertrains

Ranges of over 600 km, ultra-high-speed charging … recent BEVs have long since proven how practical they are – and tomorrow’s models will go further still. To solve today’s pres-sing challenges, manufacturers need three things: expertise, innovative technologies, and courage.

CTI Symposium Germany 2025: see for yourself how e-mobility is progressing!

Fourteen deep-dive sessions with over 80 expert presentations await you in Berlin. Two deep-dive sessions are dedicated entirely to the latest developments in powertrains. How much potential do axial flux motors, range-extender drives and high-speed motors have? Will powertrains soon be a magnet-free zone? What’s the most compelling alternative to the permanent magnet synchronous motors that still prevail today? Find out more about our fascinating symposium program below.

Manufacturers present their highlights: From range extender solutions to long-haul trucks

The new Nissan LEAF: What makes the 3rd generation of this bestseller so convincing?

When Nissan launched the LEAF in 2010, it was the world’s first mass-produced electric vehicle. Up until late 2019, it was also the world’s best-selling BEV. In June 2025, the com-pany unveiled its third-generation LEAF. In Berlin, Shunsuke Shigemoto (Nissan) will describe the new model’s key innovations. These include a new battery system, a compact integrated drive unit, and a bidirectional onboard charger. A ‘big module’ increases the battery’s capacity density and charging performance. The integrated 3-in-1 drive unit com-bines the inverter, motor, and transmission in a single housing, for improved rigidity and a compact package. Benefits include improved NVH performance with unprecedented smoothness, and higher efficiency for greater range. The new model ships with a new bidi-rectional onboard charger as standard – ideal for charging e-bikes or powering tools. In fu-ture, the LEAF will also permit vehicle-to-grid backfeeding.

The electric axle of the Mercedes-Benz eActros600. Find out what powers the International Truck of the Year 2025.

After Bertram Wunderlich (Daimler Truck)’s presentation, you’ll know exactly why the eAcross600 deserves its Truck of the Year Award. Having already developed an e-axle for heavy-duty distribution traffic, Daimler Truck is now expanding its portfolio with an e-axle for long-haul applications. This is one of the next steps towards emission-free freight transport and the decarbonization of the industry.

In part one of his presentation, Bertram Wunderlich will explain the concept and design of the new eAxle. He will offer insights into possible concepts and their advantages and disadvantages, and will explore ideas for increasing efficiency. Part two will examine the technical implementation, the main components, and their respective functions. Starting with the inverter, the speaker will cover the entire eDrive train, including the motor, housing, transmission, axle, and cooling system. Finally, he will discuss the application of the unit in the vehicle, and the challenges it faces in a global vehicle portfolio.

Li Auto’s new Range Extender Powertrain – the next chapter in a successful story

Li Auto is a highly successful specialist manufacturer of REEVs (Range Extender Electric Vehicles) in the Chinese market. In Berlin, Dr. Qiang Liu (Li Auto) will describe the sys-tem architecture and key technologies of his company’s 3rd-generation range extender powertrain. His presentation will illustrate Li Auto’s systematic vehicle-to-chip technical ap-proach, which began by deriving system performance requirements and boundary condi-tions from the vehicle performance. On the component level, the speaker will explain how the electrical magnetic design of the PSM motor enhances generator efficiency, and will describe the key technologies of a high power density ASM traction motor. Dr. Qiang Liu will also cover solutions for power electronics and semiconductor technology (including the software structure) in detail, right down to the size and number of high-voltage IGBT and diode chips. Finally, the speaker will discuss how the platform solution can be scaled and extended for use in different vehicle segments.

Developers have a new favorite: electrically excited synchronous machines (EESMs), including high-speed brushless versions

The vast majority of EVs are still powered by permanent magnet synchronous motors (PMSMs). But driven by sustainability concerns and supply chain risks, the call for magnet-free electric motors is growing louder, and electrically excited synchronous machines (EESMs) could be the solution. Either way, high-speed motors are definitely trending.

The study presented by Brice Lecole (Valeo) will examine the significant system-level benefits of a high-speed e-axle architecture for EVs. The focus rests on ‘upspeeding’, which boosts power density via higher rpm at lower torque. Using advanced electric motor technology, a high-speed carbon-clad rotor was integrated into a standard two-step high-

ratio reduction gearbox. An optimal top speed of 22 – 25k RPM was determined for the tar-geted power range. As the study results show, higher motor speeds offer significant poten-tial for downsizing the electric motor. This in turn can reduce material consumption, motor manufacturing costs, and the overall mass of the e-axle.

In Berlin, Martin Burgbacher (AAM) will go one step further with a solution that involves motor speeds of 30,000 rpm. Together with a highly integrated propulsion inverter, this can substantially increase the power density of the motor and inverter to over 25 kW/liter. These targets were envisioned for a 650Vdc EDU application rated at over 200kW for both primary and secondary drive applications. As the speaker will explain, the 30k RPM motor cuts design costs by reducing the amount of copper and magnetic lamination materials re-quired. The stator is encapsulated with a thermally conductive plastic material, while the high-speed rotor was designed using copper bars for high efficiency. The transmission u-ses a high reduction ratio of 23:1, which translates to 4500Nm of torque at the axle. A highly integrated 650Vdc ring inverter is tightly integrated into the inner diameter of the stator end turns, and provides a max phase current of 350Arms.

Valeo and MAHLE have joined forces to develop an innovative, magnet-free electric axle system for high-end EVs with peak power ranging from 220 kW to 350 kW. As Camelia Jivan (Valeo) and Thomas Hennings (Mahle) will explain, the aim of this cutting-edge technology is to revolutionize the performance and efficiency of magnet-free electric mo-tors (EESMs). The project combines Valeo’s expertise in electric motors, high-efficiency inverters (SiC and switching cell technologies) and associated motor control with MAHLE’s expertise in magnet-free rotors and its MAHLE Contactless Transmitter (MCT) technology. In tests, the fully integrated brushless motors demonstrated efficiency levels of >96%, con-tinuous peak power in excess of 60%, and a 40% smaller carbon footprint than PMSMs of the same power. In their presentation, the speakers will describe the key design decisions, compare brushless and brush motors, and emphasise that brushless motors are the main alternative to PMSM.

Axial flux machines: more than just a niche product?

Radial flux motors are inherently more efficient than their axial flux counterparts, but may need higher gear ratios to deliver the same amount of torque to the axle. Axial flux ma-chines promise high power density – but does that still apply in combination with a trans-mission? In Berlin, Kristoffer Nilsson (Alvier Mechatronics) will offer a comprehensive comparison of axial and radial flux topologies. His simulation study compares two axial flux machines with two radial flux machines, across two types of transmissions: a standard two-layshaft design, and a coaxial planetary design. The study evaluates these combina-tions over standard WLTC driving cycles, as well as for acceleration capability, on two dif-ferent vehicle specifications. How did the candidates fare, and what conclusions can we draw? In Berlin, Kristoffer Nilsson will reveal all this and more.

Electrically excited synchronous motors (EESMs) are a promising alternative to permanent magnet synchronous motors (PMSMs), whose downsides include supply chain risks, costs, and sustainability. In Berlin, Dr. Philippe Farah (Yeesma) will show how the ad-vantages of EESMs can be perfectly combined with those of axial motors. YEESMA is cur-rently developing an innovative Electrically Excited Axial Flux solution. The dual rotor, sin-gle stator approach helps solve packaging and performance challenges by delivering up to 20% more torque volumetric density, cost savings of over 50%, and a 60% higher sustain-ability index score. Dr. Philippe Farah will also describe how novel manufacturing solutions are helping Yeesma to reduce the challenges of assembling axial flux motors. The inverter phase current has also been significantly reduced, contributing to the 50% cost savings described above. The presentation will examine applications ranging from 10 kW to 350 kW in detail.

CTI Symposium Berlin: Book now for this ultra-high performance density event!

Come and join us on December 2nd and 3rd, 2025, when decision-makers and experts provide cutting-edge insights into the topics that are driving the industry. Choose your per-sonal highlights from a top-notch program featuring 14 deep-dive sessions and over 80 lectures, as well as plenary sessions and discussions. Get talking to exhibitors at the CTI EXPO, and to young innovators in the Startup Area. Then in the evening, make invaluable new contacts in the relaxing atmosphere of our CTI Networking Night.

Welcome to Berlin!

Further Development of the Limestone Engineering Continuously Variable Transmission (CVT)

James Kalkstein, PE, Chief Engineering Officer and Principal, Limestone Engineering Services, LLC
Limestone Engineering Services, LLC (LES)

Limestone Engineering Services, LLC (LES) has continued development of our unique and patented CVT under patent #11,371,592. The development has moved from the Research Proof-of-Concept Prototype as shown in the patent disclosure to an engineered Development Prototype (DP#1) shown in the figure below (Figure#1).

*Figure #1: Development Prototype #1 (DP#1) on Test Bench Setup

The DP#1 is constructed from 3D-Printed Hyper-PLA material. This material is rated at a tensile strength that is approximately 20 % of the strength of typical aluminum. Therefore DP#1 has a limited torque capacity when compared to a full-production metallic unit. However, the belt is a production-ready 5Mx15mm cog-type timing belt with a torque capacity of approximately 95 N-M (70 lb-ft). The gear-ratio span for the DP#1 unit is setup to be from approximately 1.2:1 to 0.8:1.

The ratio-change actuator in the DP#1 uses a threaded rod to actuate the devices that changes the ratio. However, the patent includes actuation devices of any kind, including but not limited to; 1) electromechanical; 2) hydraulic, or 3) pneumatic.

Please note that:

1. Virtually any timing belt width and pitch is possible allowing for virtually any torque capacity and;
2. Ratio spans are a function of the physical size of the unit and can be increased or reduced by design.

Several design iterations have been made for the idler pulley arrangements. All proved to be satisfactory, and the final choice should be based on the final design chosen.

Testing:

This DP#1 has been tested on a test bench using a simple Prony-Brake absorber system. The test-applied torque/speed capacity is approximately 20 N-M (15 lb-ft) maximum at approximately 1,000 rpm. Please note that this is using non-metallic Hyper-PLA material and not aluminum or other metallic material components. Additionally, the input drive device was limited to these values (20 N-M (15 lb-ft) @ 1,000 rpm). We believe that this testing level was very close to the ultimate-strength of the component design using this Hyper-PLA material. However, a material change (e.g … to aluminum or steel) should bring the capability to the level of the belt ultimate-strength without any additional design changes.

Cost and Supply Chain:

The supply chain for the DP#1 requires no special components for belts, fasteners, or bearings (rotational, thrust and linear). They are all Commercial Off-The-Shelf (COTS) items. However, the main operating components are specially designed for this application. We have investigated small batch fabrication for a small number (~ 5 units) of DP#1 for full-power test-bench testing. We estimate that these units would cost approximately $500 − $750 per unit to produce, not including assembly labor and special assembly fixtures. We estimate that in series-production, the cost would fall by, at a minimum, one order of magnitude , but could have even greater reductions in larger volumes.