Cooling and lubrication for electric drives – a matter of smart management

Specialized e-fluids play a key role in electric drives. Whereas ICE drives only need a water pump and a radiator, modern electric powertrains require complex thermal management systems. Using immersive cooling with ultra-low viscosity e-fluids, developers can achieve highly integrated, highly efficient 3-in-1 e-drives. All these topics, with their many facets, are well worth exploring in depth.

CTI SYMPOSIUM GERMANY 2024: The big picture, plus all the details
The transition to sustainable mobility is one of today’s key issues, and one to which we are deeply committed. In 14 Deep Dive sessions with over 80 specialist presentations, our focus in Berlin will be on two things: precise research results, and real-life products. Because these individual steps are what bring us closer to our ultimate goal.

New technology analyzes heat management, including fuel efficiency
Hyundai Transys has developed a new analysis technology that predicts the heat transfer performance of 3-in-1 electric powertrains, quickly and accurately. The method that Sang-Min Park (Hyundai-Transys) will present in Berlin analyzes the heat management (heating/cooling) and fuel efficiency of a 3-in-1 system in real time under specific driving conditions, based on the torque requirements and rpm of the powertrain. The new technology involves three elements. First, the company developed a heat transfer analysis model that would run as fast as possible. Second, they added a model that can accurately predict the temperature of each individual powertrain component. And third, they developed an integrated model that reflects the results of heat transfer in the powertrain when analyzing vehicle fuel consumption. To verify the method’s fuel efficiency predictions, Hyundai compared them with an analysis of heat transfer performance (heat exchanger capacity, etc.) of a Hyundai IONIQ 5 in MCT mode. As Sang-Min Park will explain, developers have already used the new analysis technology on Hyundai Transys HEV and EV powertrains, to hone their competitive edge.

Immersion cooling for batteries: More efficiency, more safety
Direct immersion cooling is becoming more widespread in electric powertrains. In the field of battery technology, however, developers remain sceptical due to the hardware adjustments required. But if Ilaria Travi (Petronas) has her way, that could soon change. In the study she presents in Berlin, she will show the real-life benefits of immersion cooling. Petronas ran flow simulations to compare the results of indirect cooling with water/glycol coolant, and direct cooling with various dielectric fluids. The results were then validated by testing real battery cells with different geometries, cylindrical and pouch cells. The data shows that in a standard WLTP cycle, immersion cooling is up to 5% more effective than standard indirect cooling.

Petronas also ran thermal runaway studies to evaluate the safety benefits of immersion cooling. In real-life thermal runaway tests with cylindrical NCA and NMC cells, a central cell was heated to trigger thermal propagation. The results indicate that direct dielectric cooling can delay thermal runaway by up to six minutes. This would give vehicle occupants valuable time in which to escape, and offer the battery management system a window in which to secure the system.

New valve block type solves issues in the refrigerant circuit
Adding heat pump functionality to the refrigerant circuits of BEVs makes them significantly more complex. As Frank Hohmann (IAV) will describe in Berlin, IAV GmbH has now developed a new type of valve block, together with a customer. The aim was to simplify the refrigerant circuit – and hence reduce system costs – via high levels of integration. Unlike conventional solutions, where each changeover valve requires a separate electric actuator, the new valve block requires just one electric actuator overall. So by eliminating actuators, connections and controls, the new development reduces costs.

The refrigerant valve block was developed on the basis of the R744 refrigerant circuit in the VW ID.3. It can also be used in a modified form for other refrigerant circuits and common refrigerants, such as R1234yf and R290. Frank Hohmann will present the innovative valve block in detail, and will round off his presentation with an outlook on the next development steps.

A successful co-operation: Developing a tailor-made Electric Driveline fluid for an e-axle platform
New technologies for innovative e-drives bring fresh tribological challenges in their wake.

Building on their long-standing cooperation, Magna Powertrain and FUCHS have now implemented a new project. This involves harnessing their broad experience in conventional drive technology to develop an innovative electric driveline fluid (EDF) that is perfectly tailored to Magna Powertrain’s e-drive platform. As Thomas Kraft (FUCHS Lubricants Germany) will explain in Berlin, the main aim was to find solutions in four key areas: optimized oil viscosity for efficiency, wear protection and NVH; oil foam formation and entrainment at higher e-machine rpm; compatibility with copper and other e-machine materials; and clutch performance with torque vectoring. The new fluid – FUCHS BluEV EDF – ticks all those boxes, and is suitable for use across the entire Magna Powertrain e-drive platform portfolio.

Robust e-fluid cooling concepts for e-drives with high power density
Next-generation EVs require highly integrated powertrains that can perform on a par with their larger counterparts, yet dissipate heat within a smaller volume. Dr Stephan Schlimpert (Flanders Make) believes that directly oil-cooled motors are a promising solution, but says some challenges still need to be overcome in order to make them robust. By way of a solution concept, he will present a robust design methodology, coupled with novel cooling and non-contact sealing technologies. The methodology was developed in close cooperation with Lubrizol, and included rigorous testing and analysis of material compatibility with a dielectric oil under various operating conditions. Using the novel Design Guide and the non-contact sealing concept, a robust e-motor with modified robust materials was created. It has a power density of 50 to 70 percent, and incurs no additional churning loss from oil penetrating the air gap. The Guide that Dr Schlimpert will present in Berlin sets out a strategic approach to fluid powertrain compatibility without the need for costly design iterations. It also outlines the next steps towards a unified e-fluid solution for electric vehicles.

Optimizing e-fluids: Do standardized drive cycle tests (WLTP) tell the whole story?
OEMs are switching to lower viscosity fluids, and wish to quantify potential efficiency improvements in electrified powertrains without compromising on hardware protection. For this, as Andrew Wood (Infineum UK) will explain in detail, WLTP tests alone are not enough. The only way to obtain sufficiently differentiated test results is by combining WLTP with steady-state tests that cover the entire operating range. Infineum has conducted both WLTP and steady-state tests in electric drive units at different temperatures, loads and speeds. The company has also examined the effects of viscosity (low and ultra-low viscosity fluids), the quality of the base material (Class III and IV base material), and boundary friction additives. In addition to efficiency gains, the tests also examined the impact on hardware protection. In Berlin, Andrew Wood will be discussing a wealth of individual results in detail. For example, it can be proven that boundary friction additives significantly improve efficiency, especially at low speeds and high temperatures –a fact that WLTP tests do not reveal. The new findings can assist companies in developing special lubricant formulations for high-efficiency e-drives. Infineum is currently in contact with a number of customers and OEMs to assess their interest in this approach.

Diverse challenges: Lubricant solutions for electrified heavy-duty drivetrains
The wide range of electric motor concepts and architectures for on-highway applications calls for various specific lubricant solutions. As the market leader, Shell has now launched a new e-fluid portfolio with tailor-made products for wet and dry electric motors. In his presentation, Leonard Kieckebusch (Shell Global Solutions) will discuss the demands that different electric HD drivetrain systems make on specific e-fluids. With wet electric motors, for example, what are the trade-offs in terms of wear protection, corrosion protection and electrical properties?
The specific test procedures used in the heavy-duty sector are equally fascinating. Shell uses drivetrain test benches to compare the properties of candidate fluids at various relevant load points. These load points vary from city buses to long-haul transport, and must be carefully selected in collaboration with the OEMs. When developing new lubricants, the overarching focus  is sustainability. In Berlin, Leonard Kieckebusch will present examples of circular economy initiatives and low-carbon components for e-fluid formulations, such as reclaimed base oil.

Ultra-low viscosity e-fluids: Reduce to the max
Low viscosity e-fluids offer better heat management, and can further improve the efficiency of directly cooled electric motors. Hence, developers now strive to take viscosity values ​​as low as possible. But as Dr Amanda Eastwood (Lubrizol) will ask at the start of her presentation: “How low can we go?” Lower viscosity can sometimes weaken the strength of the oil film, and to protect the hardware, appropriate wear behaviour – as defined by original equipment manufacturer (OEM) engineers – must be ensured. With this in mind, Dr Eastwood will discuss and answer the question of what viscosity values ​​can actually be achieved in real life. As she will show, new advances in e-fluid powertrain technology mean there is no need to compromise on other performance aspects, such as transmission wear and bearings protection. Dr Eastwood will conclude her analysis by sharing results on how the new e-fluid technology performs in real-life e-hardware.

Welcome to the CTI Symposium Germany!
Be there on December 3rd and 4th, 2024, when decision-makers and experts share their cutting-edge insights into the topics that are moving our industry. Discover your personal highlights in a two-day program packed with special Deep Dive sessions, lectures and discussions – both in the plenary session, and at CTI EXPO.

“Create a female network early in your career”

At the 2024 USA CTI Symposium in Novi, the ‘Female Session’ – organized by CTI and the AWA foundation – took place for the first time. We spoke to Sarah Zitouni, Director of Hybrid Powertrain Strategy at Aurobay, who shared her experience as a speaker in the session.

Ms Zitouni, what were the goals of the first Female Session at the CTI symposium last May?
The interest in having a dedicated female session at an international conference is at least twofold. Firstly, it’s essential to demonstrate the presence of women to one another. It can feel isolating to sit in a room with 360 chairs, like we have at CTI, and not see another woman nearby. Therefore, it’s important to encourage women to attend more of these events. Being a pioneer is never easy. The second aspect is that this session provides an opportunity for networking and exchanging information, which can benefit our companies. Connections made among women in the industry may be stronger than those formed otherwise.

What was your role, and how did you contribute to the session?
One session in particular, the one I proposed, focused on how to become a speaker at events. If we look at the CTI program now, despite the organizers’ best efforts, there are still very few female speakers. Few panelists are women, and none of the chairs are held by women. We need to increase these numbers, and this requires a collective effort from everyone. My contribution to this effort, as a speaker at Novi, was to share how I got here, how can you prepare your presentation, and how can young female engineers become the next speakers at CTI.

What can the younger generation do better to get there?
That’s the key aspect, the significance of diversity. Diversity brings different opinions and perspectives into the room, which is crucial in today’s world – a world undergoing the fastest transition any of us have ever experienced. Solving these complex issues requires more minds and greater diversity. We need to open up the room and share speaking opportunities with a broader range of people because they will bring new insights to the table that we haven’t heard before.

How do you experience the drive to get more female engineers into powertrain development?
I think it varies greatly from company to company. I’ve seen some companies take a very active role and make real progress. Let me give you a number: more diverse companies have turnovers and profits that are eight percent higher than those of less diverse companies. So there’s literally money in diversity. Some companies are leading the way in this regard. I know of some that have increased their share of female engineers from 20 to 40 percent, which is almost at parity – an impressive achievement. On the other hand, some companies still seem to rely on things happening on their own. They say, „We don’t discriminate,“ and hope that will be enough. But it requires an active approach – to actively seek out talent and to demonstrate through role models that being a woman in the automotive industry is normal.

Speaking of diversity, what was the reason for launching the Female Session as an exclusively female group?
The need for a non-mixed conversation, or a conversation in a non-open setting, stems from the freedom of speech it allows. The truth is that when you’re in a group with a shared understanding, discussions, stories, and ideas flow more easily. Several studies have shown that even adding just one man to the group, even if he’s an ally and supportive, can stifle that flow of thoughts, making it harder to share difficult experiences. It’s a bit like what happens with unions – they also gather among themselves. Based on those discussions, it’s then productive to have conversations with management and other stakeholders. This is the same idea.

For me as a boy, a long time ago, it seemed natural to be interested in technical things. How do girls find out they are interested too, and have the talent?
Many studies show that girls begin to underestimate themselves as early as age four, so it’s crucial to address this issue early on. All games and activities related to STEM subjects – science, technology, engineering, and math – should be equally targeted at both boys and girls from a young age. It’s important to continue fostering interest in these topics. We should also highlight role models, as CTI is doing, by showcasing those who are already succeeding in these fields. When we show that women can be inventors, creators, directors, or CEOs, it helps normalize that image in everyone’s mind, for both boys and girls, and opens up perspectives that may not exist today.

How has your own career path been, and what suggestions do you have for others?
My journey in the automotive industry has been quite bumpy. I dreamt of playing with big cars since I was four years old. When my dad explained how a combustion engine worked, I couldn’t understand why all kids weren’t fascinated by it. Every decision I made during my studies was aimed at getting to where I am now. But at every step in my career, I encountered people who told me that what I was doing was uncommon or even not allowed. My ambition is for the next generation to have the freedom to pursue whatever they want. So, my advice is not to listen to those who say it’s impossible. There are many role models in the industry – Mary Barra is one of them. Another piece of advice: build a strong network early on, including experienced women, because that network can help you progress.

Interview: Gernot Goppelt

Efficiency drives: Electric powertrains with endless possibilities – and slim solutions.

The transition to sustainable mobility is all about efficiency. Key demands include frugal energy consumption for electric drive systems, and faster development processes. From a vast range of possible architectures and technical alternatives, designers must develop highly individual concepts – then fit them into ultra-slim drive units. 

CTI SYMPOSIUM GERMANY 2024: An inspiring ideas pool, and a dependable guide
In fourteen Deep Dive sessions with over 80 specialist presentations, all the latest technical developments are on the agenda in Berlin. Browse our program and discover all the relevant topics and current trends for your specific field – plus a wealth of surprising insights and groundbreaking solutions. 

Highly integrated EDUs
In the rapidly evolving EV industry, efficiency, cost reduction, and system simplification are paramount. hofer powertrain’s new xONEsolutions set a new standard with innovative eDrive systems that integrate key components into a compact unit, reducing materials and costs by up to 25% and achieving up to 97% efficiency. The xONEdrive and xONEbattery combine vital functions like onboard charging, DC-DC conversion, and thermal management into scalable solutions, supporting voltages from 400 V to 1250 V. These advancements offer a plug-and-play approach for OEMs, enhancing flexibility and paving the way for the future of e-mobility.

In his analysis, Dr Håkan Sandquist (InfiMotion Technology Europe) is equally upbeat on the benefits of integrating additional functions such as DC/DC conversion, on-board charging and battery management system (BMS) into the traction inverter. As he will explain in Berlin, the speaker sees it as a “decisive step on the road to more efficient, more compact and more cost-effective electric drive systems in next-generation vehicles”. Dr Sandquist will underscore how integration permits seamless communication and the coordination of different subsystems, both of which boost overall system performance. He will also share up-to-the-minute information, and present an innovative X-in-1 EDU developed by InfiMotion whose SOP recently began in China. 

Always a gripping topic : Wheel hub drives and AWDs
Sophisticated all-wheel drives with two powerful electric motors and ultra-compact wheel hub motors are one of the most fascinating e-drive applications – and an endless source of interesting challenges for developers. 

How do different e-motor architectures and axle decoupling options affect the energy efficiency and system costs of 4WD BEVs? To answer that question, Jeff Waterstredt (BorgWarner) will be presenting a simulation-based study that compares the performance of permanent magnet (PM) and induction (IM) motors on front and rear axles, with and without disconnect clutches, under different driving cycles and power-to-weight ratios. The study also examines the impact of the disconnect clutches’ positioning on transmission drag losses and motor efficiency. As the speaker will show, the best configuration for optimal energy efficiency and system cost reduction across all operating conditions is a combination of IM and PM motors with disconnect clutches on both axles. This finding challenges the conventional view that induction motors for secondary axles eliminate the need for, or benefits of, axle decoupling. 

Are there new opportunities for wheel hub drives, and could they even become cost-effective for the mass market? In his analysis, Patrick Starke (IAV) will first point out the classic advantages in terms of package and driving cycle consumption, then show how factors such as axial flow machines and radial flow machines with double rotors can improve affordability by increasing power and torque densities. The speaker will present a study that offers in-depth answers for a passenger car in the C segment. He will compare various wheel hub drive trains with a conventional central drive, and analyse the combination of inverter, electric motor and battery with regard to costs, energy consumption and package. Other points will include the benefits of improved vehicle aerodynamics, and the use of more cost-effective battery storage in various future scenarios. 

Tough challenges : Three highly efficient solutions 
Cost-sensitive customers, rising material prices, falling subsidies … electromobility is facing serious challenges. To succeed, modern drives must be developed quickly, then made market-ready as soon as possible. The three projects described below show how this can be achieved. 

Slim e-axles for affordable vehicles 
Matthieu Rihn (Marelli EPT Strasbourg) is convinced that the demand for compact, affordable vehicles will grow. In his talk, he cites trends in markets such as India and quotes Luca de Meo (CEO of Renault), who proposed targeted promotion measures for European small cars in his “Letter to Europe”. For the e-axles these vehicles require, weight and cost reductions are top priorities, and their system power should not exceed 100kW. As Matthieu Rihn will explain, developing slim e-axles calls for a new approach at system level. The e-motors are small, with high RPM; inverters are integrated into the main housing, and preferably run at 400 V; cooling and lubricant circuits are optimized to the max. The aim is to not only use existing, proven technology, but to integrate it intelligently as well. When it comes to slim e-axles, less is definitely more. 

EDU system with > 94% average cycle efficiency 
AVL has been looking at ways of increasing range and charging speeds by improving the overall efficiency of BEVs. As Wilhelm Vallant (AVL) will show in Berlin, the result is a highly efficient EDU that consumes just 10 kWh/100km and has an average WLTC cycle efficiency of >94% at the charging point. The speaker will first describe the framework conditions AVL set in order to determine the most suitable EDU system for a B/C segment vehicle with maximum energy efficiency. The methodology for the concept evaluation and initial dimensioning of the electric motor, transmission and inverter components was structured with the aid of AI-supported DOE. Target achievement was verified by means of hardware bench tests. To achieve the highest average final efficiency in both WLTC and CLTC, various system designs were also compared and their differences mapped. The study was based on a customer project that ran in parallel to the company’s internal R&D activities. 

Valeo Gen5 eDrive : A platform solution with extreme power density 
Karsten Kühlkamp (Valeo eAutomotive) will be presenting a new electric axle platform called Valeo Gen5 Drive. With a wealth of technical options (400V or 800V nominal voltage, oil and water-cooled motors, parking locks and disconnectors, scalable power modules), this new drive is designed to meet market requirements in full. The Valeo Gen5 eDrive is an optimiszed, scalable solution for power classes from 100 kW to 250 kW, in a flexible vertical or horizontal architecture with common interfaces, components and subsystems. As the speaker will explain, this is the key to continuous optimiszation processes in terms of performance and efficiency. In his presentation, Karsten Kühlkamp will focus on the platform solution for the medium (150 kW) power segment. His simulation and test results will show how the prototype based on the platform solution combines outstanding power density with high WLTC driving cycle efficiency. In a more detailed analysis, he will identify different design features that help to reduce losses, and discuss possible measures for taking efficiency higher still. 

Toyota’s Accessible People Mover: Mobility for Olympic participants 
At the 2024 Olympics and Paralympics in Paris, Toyota provided an entire fleet of Accessible People Movers (APMs) for people with reduced mobility. Toyota Motor Europe was responsible for all aspects of vehicle development, from initial design concepts to vehicle production at Toyota Caetano. Key project partners were FEV Europe GmbH, and the battery supplier Forsee Power. In a joint presentation, Thomas Haine (Toyota Motor Europe), Frederik Baudrier (Forsee Power) and Nabal Pandey (FEV Europe) will provide insights into how the APM electric drive system was developed.   

In their three-part talk, they will pay special attention to the 48V traction battery. Part One will describe how the development work was frontloaded by creating a virtual vehicle model, then running simulations to select standard drivetrain components. Part Two will describe how the selected components were integrated into the drivetrain system. Part Three will cover the validation process for both the design, and the effectiveness of countermeasures derived from the design review. Overall, the presentation will offer deep insights into the development of 48-volt electric drivetrain systems for low volume production. By combining cost-effective design solutions with flexible control logic, Toyota and its partners were able to meet unique product requirements. 

CTI Symposium Berlin: Book now to end 2024 on a high note! 
Be right there when decision-makers and experts share cutting-edge insights into the topics that are moving our industry on December 3rd and 4th, 2024 in Berlin. Select your own personal highlights from a two-day program packed with Deep Dive sessions, lectures and discussions by decision-makers and experts in the plenary session and at CTI EXPO. Once again, the undisputed glamour highlight will be the Networking Night, held in the Arminius Market Hall. This year’s program also features two new highlights: The special START UP AREA is a showcase for potential stars of tomorrow, while our WOMEN @ CTI SPECIAL PROGRAM is reserved exclusively for female participants.  

Welcome to Berlin!