The Need for a Clear View of Future Powertrain Technologies is Greater than Ever
The transition from fossil-fueled transport to clean sustainable mobility does not progress in a straight line. Bumps and twists line the road: new technologies are being developed, new players are entering the market, new alliances are sought.
Strategies and technologies for carbon-free mobility
The automotive industry is transforming rapidly towards zero-emissions mobility.
While net zero emissions can be achieved with different drive systems and primary energy carriers, all solutions have one thing in common: CO2-neutral mobility based on renewable energy sources.
The International CTI SYMPOSIUM and its flanking specialist exhibition is THE industry event in Europe dedicated to sustainable automotive powertrain technologies for passenger cars and commercial vehicles. The event brings together automotive decision makers and industry experts discussing latest strategies, technologies, innovations and the automotive powertrain as part of the greater energy transition!
Team Brudeli Green Mobility The heavy-duty trucking industry faces significant challenges in reducing emissions and meeting increasingly stringent regulations. With medium and heavy-duty trucks contributing approximately 5% of global carbon emissions, there is an urgent need for innovative solutions beyond the fully electric vehicles. Brudeli Green Mobility (Brudeli) has developed and tested the Brudeli Powerhybrid™, […]
The heavy-duty trucking industry faces significant challenges in reducing emissions and meeting increasingly stringent regulations. With medium and heavy-duty trucks contributing approximately 5% of global carbon emissions, there is an urgent need for innovative solutions beyond the fully electric vehicles. Brudeli Green Mobility (Brudeli) has developed and tested the Brudeli Powerhybrid™, a plug-in hybrid powertrain technology that promises to accelerate electrification in these hard-to-abate sectors.
Technical approach and configuration advantages
The Brudeli Powerhybrid TM utilizes a P2.5/3 configuration (figure 1), a sophisticated plug-in hybrid system designed specifically for heavy-duty trucks. This configuration integrates two electric motors into the transmission.
The P2.5/3 design offers several key advantages over the more common P2 configuration. Its flexible power management through a dual-motor setup allows for both parallel and serial hybrid modes, optimizing efficiency across various driving conditions. In serial mode, efficiency is improved as one motor can generate electricity while the other drives the wheels, particularly enhancing performance in low-speed or stop-and-go traffic. The enhanced powershift capability, achieved through integration within the transmission, enables smoother gear changes without power interruption, improving driving comfort and energy management during acceleration and deceleration.
Fig. 1: Schematic overview of the Brudeli Powerhybrid™ patented concept.
ICE – Internal Combustion Engine,
AMT – Automated Manual Transmission,
C – Clutches, X – Input fixed gear,
Y – Output fixed gear,
EM1/EM2 – electric motors.
The new principle makes it possible to drive the vehicle entirely electrically. Two electric motors are controlled and will act as a mechanical gearbox. In our concept, this is arranged by electric motor 1 (EM1) being permanently connected to the input gearbox shaft (AMT – Automated Manual Transmission), while electric motor 2 (EM2) is alternately connected to E1 or, during gear changes, connected to the output gearbox shaft.
Higher electric power potential is achieved through the dual-motor design, which can deliver more electric power and higher power density than a single P2 motor, enhancing performance in electric-only mode. The system features seamless AMT (Automated Manual Transmission) integration, as being integrated into the transmission allows it to work optimally with the AMT for precise gear shifts and power delivery. Advanced regenerative braking is achieved through eMotors positioned at two drivetrain points, allowing for more efficient energy recuperation during braking.
Key technical features of the Brudeli Powerhybrid TM include:
Dual electric motor design (2 x electric motors, totally 429 kW, 800V)
Advanced Powershift capability for seamless gear changes
Integrated electric power takeoff for auxiliary systems
Power takeout could also run mechanical from ICE engine
Compatibility with existing diesel, gas, and hydrogen drivetrains
Real-time route optimization and energy management
Methodology and development
Brudeli’s development approach is focused on maximizing energy efficiency and flexibility while minimizing costs. The company conducted simulations and is performing real-world tests to optimize the system for various driving scenarios.
Although novel at system level, each functional element can be seen as established and mature technology, allowing for optimized time to market. Furthermore, the modular and scalable architecture – the external electric motors make a key element – enables scaling of system cost and performance per use case.
A target area of innovation at Brudeli is the real-time route optimization, accounting for factors such as geography, topography, traffic conditions, and available charging infrastructure. In a driving plan, continuously the driving modes and gear shifts are optimized to maximize efficiency. Clearly, energy efficiency and emission can be traded vs cost and time.
The development process also prioritized compliance with upcoming regulations. The Brudeli PowerhybridTM system is designed to meet the EU’s VECTO standards for 2024 and beyond, as well as the US EPA Phase 3 and California’s Advanced Clean Fleets (ACF) regulations. Furthermore, the flexible configuration is optimal for meeting future, more stringent regulations.
Results and innovation
The Brudeli Powerhybrid™ demonstrates several significant advantages over conventional powertrains and competing electrification technologies:
Up to 80% electric driving capability, reducing diesel consumption and emissions proportionally
Lower total cost of ownership compared to both conventional diesel and fully electric trucks for long-haul routes
Flexible operation, allowing trucks to complete all routes without range limitations
Smaller battery (200-400 kWh) requirements compared to fully electric trucks, reducing upfront costs
Electric driving and leading cost without the need for Higher Power charging infrastructure
Superior CO 2 abatement cost-effectiveness, performing on par with battery electric technology in standard drive cycles
Brudeli’s analysis shows that for a typical long-haul route of 480 km per day, the Powerhybrid™ system achieves a carbon abatement cost of 644 EUR/ton CO 2 , comparable to 602 EUR/ton for battery electric and significantly better than other alternatives like hydrogen fuel cells (1514 EUR/ton) or standard hybrids (3007 EUR/ton). If including compensation for cost factors such as charging infrastructure, vehicle availability, and payload, this would skew such analysis further toward the Powerhybrid™.
Market impact and future outlook
The Brudeli Powerhybrid™ addresses a critical gap in the electrification of heavy-duty trucking. While battery electric vehicles are making inroads in short-haul and urban applications, long-haul and heavy-duty segments remain challenging to electrify due to range and infrastructure limitations. Total addressable market of heavy- and medium duty trucks worldwide is 4.3 million vehicles. Brudeli projects that by 2050, nearly all diesel and alternative fuel trucks, including hydrogen-powered vehicles, will incorporate plug-in hybrid technology. This transition is driven by both economic factors and regulatory pressures, with new EU targets calling for a 45% reduction in heavy-duty vehicle emissions by 2030 and 90% by 2040.
The Brudeli PowerhybridTM system’s flexibility and compatibility with various fuel types position it as a „future-proof“ solution. As charging infrastructure expands and green electricity becomes more prevalent, hybrid trucks can progressively increase their electric driving percentage, further improving their environmental performance.
Conclusion
The Brudeli Powerhybrid TM , with its advanced P2.5/3 configuration, represents a significant innovation in heavy-duty truck electrification. By offering a flexible, efficient, and cost-effective solution that can be implemented across existing fleets and routes, it has the potential to accelerate emission reduction in a sector that has proven difficult to decarbonize. The system’s sophisticated power management, enhanced efficiency, and the compatibility with various drivetrains make it a compelling option for manufacturers and fleet operators looking to meet increasingly stringent emissions regulations while maintaining operational flexibility.
As the transportation industry continues its transition towards sustainability, technologies like the Brudeli Powerhybrid™ will play a crucial role in the gap between conventional powertrains and fully electric solutions, paving the way for a more sustainable future in heavy-duty trucking.
Fig. 3: Brudeli Powerhybrid™ MK1 exhibition model shown at ACT Expo 2024 and IAA Transportation 2024
Michael Numberger, CTO, Hyperdrives GmbH Hyperdrives’ hollow conductor technology improves stator cooling for electric motors by an order of magnitude, achieving exceptional power density and efficiency. Seamless integration of proprietary manufacturing processes into existing hairpin stator lines makes it ideal for high-volume automotive, heavy-duty and aerospace applications. Introduction and objectives The ongoing electrification in the […]
Hyperdrives’ hollow conductor technology improves stator cooling for electric motors by an order of magnitude, achieving exceptional power density and efficiency. Seamless integration of proprietary manufacturing processes into existing hairpin stator lines makes it ideal for high-volume automotive, heavy-duty and aerospace applications.
Introduction and objectives
The ongoing electrification in the automotive sector and other industries demands a new generation of electric drives that are more powerful, efficient, and cost-effective. A central challenge is thermal management, as high power densities must be combined with more efficient heat dissipation. Hyperdrives‘ hollow conductor technology presents a novel solution for stator cooling, boosting both power density and efficiency while reducing motor production as well as operational costs. This article aims to present the technical innovations, performance capabilities, and application areas of this technology.
Technical basis
Hyperdrives’ technology utilizes hollow copper conductors, focused on optimizing the heat flow between cooling fluid and copper winding. At maximum torque, over 90% of total motor losses are attributed to the copper winding. Hyperdrives achieves an unprecedented low copper-to-coolant temperature gradient by leveraging several key design features:
Direct coolant-to-copper contact: The hollow conductors allow the cooling fluid to be in direct contact with the copper conductors’ inner channels’ surface, enabling direct heat dissipation precisely where it is generated.
Hollow pin topology:
Defined and even hollow channels, typically between 1 and 2mm in size, are engineered to maximize cooling surface area and facilitate consistent fluid flow and heat transfer at all sections of the winding.
Decoupling of electric and hydraulic connection: Optimization of the hydraulic cooling fluid flow path independent from the electrical winding layout.
Low-viscosity cooling fluid: Hyperdrives employs a low-viscosity dielectric oil as the cooling fluid, combining water-like viscosity with electrically insulating properties. By solving the pressure drop challenge – maintaining a minimal pressure drop of less than 1 bar – Hyperdrives enables the use of standard, cost-effective pumps with minimal energy consumption instead of specialized, high-cost and high energyconsuming alternatives.
High-velocity, turbulent fluid flow: The cooling fluid moves at high velocities, promoting turbulent heat transfer with a heat transfer coefficient (HTC) exceeding 2,000 W/m²K. This turbulence intensifies cooling by enhancing heat dispersion from the copper surface.
Together, these features enable superior stator cooling by precisely and uniformly dispersing heat across the copper windings. With cooling integrated directly through the hollow conductors, there is no need for a conventional water-cooled jacket, freeing up valuable installation space around the stator. This allows for a more compact motor design or can be leveraged to increase torque output by enabling a larger airgap diameter and optimized stator geometry. Hyperdrives motors can handle ultra-high current densities of up to 75 Arms/mm² copper cross section in steady-state operation, pushing the boundaries of motor performance. The entire cooling circuit, including both the inverter and motor in one circuit, remains compact and low-cost, offering a highly efficient, space-saving, and economically competitive solution for high-demand, high-volume applications.
Comparison with conventional stator cooling
Compared to state-of-the-art water-jacket plus spray-oil cooled hairpin stators, Hyperdrives’ hollow conductor technology enhances heat dissipation by a factor of 10 and boosts continuous current density by a factor of 3 (75 vs. 25 Arms/mm² continuous). This breakthrough enables the system (motor incl. inverter) to achieve peak power densities up to 15 kW/kg and over 12 kW/kg continuous. All while using standard materials without relying on costly Cobalt-Iron laminates, or 3D-printed windings. By achieving these results with conventional materials, the established inner runner motor topology and proven manufacturing techniques, Hyperdrives sets a new benchmark for performance-to-cost in electric motors.
Efficiency gains and customer benefits
Optimal motor sizing for maximum efficiency is unique to each application and should be evaluated on system level rather than focusing solely on the motor. In aviation, for example, weight savings can take precedence over pure peak efficiency. Hyperdrives’ technology enables groundbreaking designs by shifting conventional thermal boundaries, making it possible to achieve maximum efficiency exactly where it matters most. For the majority of automotive, heavy-duty, and aerospace applications, this is part-load. The enhanced motor efficiency characteristics can yield up to a 10% improvement in energy onsumption and range. These efficiency gains translate into significant lifetime cost savings and deliver clear customer benefits.
Mass production and cost reduction
One of Hyperdrives’ key advantages in using hollow I-pins and hairpins is its compatibility with existing automotive hairpin stator manufacturing processes, which enables full automation, fast scaling and cost-effective integration in existing production lines. Hyperdrives’ proprietary methods for joining hollow pins and sealing the cooling manifold fit seamlessly into current production workflows, reducing conversion costs and simplifying adoption in mass production.
Distributed stator windings enhance compatibility with all available rotor topologies, offering increased design flexibility, especially for cost-sensitive applications. Rare-earth magnets can be optional, mitigating potential geopolitical dependencies and tackling the environmental aspect.
Durability and reliability
Hyperdrives has successfully completed extensive testing to validate the durability and reliability of its technology. Test specimens have demonstrated extreme robustness by withstanding rigorous heavy-duty shaker tests, followed by 25,000 full thermal cycles and pressure pulses, effectively simulating ten years of daily use. This testing confirms that Hyperdrives’ cooling system is engineered for long-term performance, ensuring reliability and robustness under real-world conditions in demanding applications.
Market model and commercial application
Hyperdrives’ system not only maximizes performance but also minimizes production complexity and cost. This makes it ideal for large-scale deployment across automotive, heavy-duty, and aerospace sectors, providing a scalable solution that meets the rigorous demands of these industries without compromising on quality or efficiency. Hyperdrives follows two business models: direct sales of complete systems for customers with low-to-medium production volumes and technology licensing for large-scale manufacturers. Leveraging on close partnerships with industry innovators, along with established production processes, both models remain cost-effective and scalable.
Product specifications and outlook
Hyperdrives now offers an integrated silicon carbide (SiC) inverter and ready-to-go motor control with its motors. The development of the Hyperdrives ONE model, aimed at automotive applications, has been successfully completed. Building on this achievement, Hyperdrives has initiated the development of Hyperdrives ULTRA, a model tailored to meet the rigorous demands of aircraft applications.
The Hyperdrives team is excited to connect with potential partners and clients to discuss custom development of drive systems tailored to your specific application using our versatile and scalable technology. Whether the need is for high-speed or high-torque direct drives, our team is ready to collaborate and create a solution that meets your unique requirements. Reach out to us at info@hyperdrives.de to explore how we can support your project with cutting-edge, adaptable drive technology.
Mathias Deiml, AVL Software and Functions GmbH Katharina Berberich, AVL Software and Functions GmbH Wilhelm Vallant, AVL List GmbH The e-mobility market is facing the challenge of an increasing pressure to reduce unit costs and increase power density and performance at the same time. AVL’s second-generation high-speed e-axle increases power density to reduce material usage, […]
Mathias Deiml, AVL Software and Functions GmbH Katharina Berberich, AVL Software and Functions GmbH Wilhelm Vallant, AVL List GmbH
The e-mobility market is facing the challenge of an increasing pressure to reduce unit costs and increase power density and performance at the same time. AVL’s second-generation high-speed e-axle increases power density to reduce material usage, focusing on the e-motor and gearbox, with CO2-equivalent footprint as a key comparison criterion.
With the updated design in Generation 2 it achieves a power density of over 4.3 kW/kg, features a 30,000rpm motor, silicon carbide double inverter, and loss optimized gearbox. It minimizes magnet and copper use, reducing unit costs, CO2 emissions and improving efficiency.
Speed and cost – Why 30.000 RPM
Electric motors, such as PMSM based machines widely used for automotive applications, consist of high masses of expensive materials: dynamo sheet metal, magnets, copper. Reducing the size of the motor reduces these costs. Downside of this characteristic is that scaling down motor size means to reduce its torque.
Pmech = ω * M; M ~ d 2 * l;
d: diameter; l: lamination length
To maintain the power rating the rotational speed needs to be increased when reducing motor dimensions. An increase of factor 2 in motor speed results in a reduction of active motor material by a factor of 2. Provided that special or expensive technologies in motor and transmission can be avoided there is a substantial cost saving in the motor. Weight and size of the motor can be reduced accordingly and are additionally beneficial for vehicle features and again costs.
Fig. 1: Speed vs Cost
These relations between speed and weight/volume/cost are shown in Fig. 1. AVL’s engineers were looking
for the optimal speed, at which weight and cost are both low [1] and found it at 30.000 RPM.
High speed e-machine development
To develop this e-motor for the required 30.000 rpm without using expensive technology like cobalt steel lamination, the following challenges had to be overcome:
Mechanical rotor strength due to high centrifugal forces
Bearing technology at high rotational speed in partnership with SKF
High frequency losses in copper windings
Increased iron losses due to higher fundamental frequency of 1500Hz
The developed Solutions included new innovative designs for
Hairpin Windings
Cooling concept
Selecting hairpin winding technology helps to deal with the high frequency losses: A six-layer hair pin winding with bended copper on one side and copper forming and welding on the other side was chosen. A copper fill factor of 60% was achieved. This factor includes the oil channels for cooling, described in the cooling chapter. A slot-liner with only 0.1 mm thickness was used. The slot was optimized for coolant flow in combination with copper fill factor.
There is no need for resin in the slot. Thus, additional micro-oil channels along the copper improve coolant flow. Recycling of copper is facilitated; the winding can be removed in one piece without shredding. [2]
The prototypes were manufactured using SLM selective laser melting, a 3D copper printing process. This has further advantages:
Smaller winding heads possible
Low cost for tooling
Smaller resistance compared to welding
Copper printing, may be only the beginning, further optimizations like free shaping of super short winding heads can be realized in later steps. It is suitable for small series production. For large scale volumes welding shall be used. AVL’s current design enables both manufacturing processes. [2]
The sophisticated direct cooling concept shown in more detail:
Direct oil cooling means that the coolant is directly in contact with the copper winding in the slots and winding heads. The stator is fully filled with oil, which is pumped along the stator slots. Thus, the copper losses are very efficiently cooled. An air gap tube keeps the oil away from the rotor space, so no friction or splashing losses are present. [3]
The transmission uses a dedicated lubrication fluid with an own oil pump and filter. In addition – compared to Gen 1 – there is now a transmission fluid cooler integrated. This device can be installed optionally, for high performance application, where it is needed. [2]
The magnets are cost-effective quality with low heavy rare earth content.
Achieved eMotor performance
The efficiency map shows a maximum of over 97%, in a wide range. Due to NO20, segmented magnets and high copper fill factor the losses at high speeds are well balanced. This is shown in Fig. 2.
The map is generated for 180°C copper temperature. Thanks to direct oil cooling, the copper temperature is typically 90°C, resulting in ever better efficiency.
Fig. 2: High Speed E- Machine Performance and Efficiency at 180° C Machine Temperature
Overall EDU system implementation
The EDU design with the new e-Motor continued to focus on overall cost reduction, reduction of material usage and increased power density without losing efficiency. Scalability and high-volume rollout were also key considerations. With these requirements the resulting concept is described:
1. EDU:
a. dual motor, dual torque path to enable torque vectoring for premium segment
b. central gearbox for optimal length of drive shafts in
various vehicles
c. low profile design to support flat chassis
2. High speed motor:
a. standard materials for sheet metal and magnets
b. PSM technology for best power density and system efficiency
c. high frequency winding for low factor AC_loss / DC_loss
d. cooling with best-in-class effectiveness, combined with the inverter
e. mechanical rotor stability up to 1,2 * n max
3. SIC inverter:
a. high power density in complete package
b. best efficiency, fast switching slopes, variable switching frequency
c. combined DC link, interleaved switching, low EMC emissions
4. Gearbox:
a. 2 stage transmission, single speed
b. lay shaft concept
c. high efficient tooth geometry, optimal NVH tradeoff
d. injection lubrication, separate fluid than motor
CO2e footprint and comparison to other systems for AVLs e-axle technology
Besides the already discussed technological and cost targets, a future proven EDU concept must also comply to a sustainable design to reduce CO 2 e footprint and increase efficiency in the life cycle.
„Design-to-CO 2 e“ as a holistic approach in the course of the systems engineering meant a transition from an original focus on „design to function“ and „design to cost“, to the additional dimension of CO 2 equivalent over the life cycle. [4] The total life cycle includes Production, Use and End of Life with. recycling or 2 nd life.
Cost, weight & CO 2 e comparison
To compare our EDU system with different solutions, three systems with a peak power rating of 160 kW were evaluated: a baseline PMSM system, AVLs new high-speed PMSM system, and an externally excited synchronous motor (EESM) system.
For the complete EDU system, the evaluation included weight, cost, and CO 2 e of active motor parts, power inverter, and transmission, considering additional components like rotor shaft, bearings, and motor housing. Rotor excitation for the EESM system is considering cabling, sensors, and rotor interface as part of the power inverter.
Collector ring and copper bars/wires to the rotor windings are already considered with the E-Motor active parts. A potential for saving in terms of weight and cost was identified in the magnitude of 17 kg and 8% respectively with the use of high-speed motor, where EESM shows the potential of 5% cost saving but a disadvantage of up to 13kg in terms of system weight (see Fig. 3).
Fig. 3: Weight, cost & C0 2 e evaluation – EDU System
Evaluating the sustainability of EDU systems by comparing calculated CO 2 e emissions shows an advantage
of 10% with the High Speed PMSM System and a potential increase in terms of CO 2 e emissions of up to 6%
with the EESM system. [3]
Conclusion and outlook
AVL’s high speed EDU is in the second generation with an efficiency and performance above state of the art and improved sustainability due to high power density of 4.3kW/kg.
The described technology is tested continuously, e.g. in 2 AVL demo cars, which are running since 2020. Furthermore, the AVL torque vectoring function has been developed for and demonstrated in the vehicle.
Planning of our Gen 3 includes further improvement of inverter power density by 50%, a single motor derivate EDU for compact cars with only 25kg at 120kW/3400Nm, and intensive use of AI based machine control, such as rotor temperature determination.
References
[1] M. Deiml, A. Simonin, P. Jafarian: High Speed Electric Drive by AVL, CTI Berlin, 2018
[2] M. Deiml, M. Schneck: Increasing the Sustainability of Electric Drives by High Speed Motor Technology, CTI Berlin, 2022
[3] A. Angermaier; M. Deiml; W. Vallant; G. Fuckar:, Electric drive units with high power density and sustainability through high speed and maximum efficiency, Wiener Motoren Symposium, 2024
[4] Sams, C.; von Falck G.; Sorger H.: Cost Engineering as an Essential Part of Systems Engineering. In Systems Engineering for Automotive Powertrain Development. Schweiz: Springer, 2021