The Powertrain as an Intelligent System

The automotive world is changing, and the CTI Symposium is helping to drive the transformation. Where will the boundaries of powertrains lie in future? While powertrains will still be centre stage of the Symposium, the scope will expand. Artificial intelligence will play a growing role, and so will the provision of energy sources.

The 22nd CTI Symposium 2023 in Berlin (5 – 6 December) began with an important announcement, as Prof. Ferit Küçükay handed over his role as chairperson to Prof. Malte Jaensch. Jaensch‘s primary role is Chair of Sustainable Mobile Powertrain at the Technical University of Munich. Professor Küçükay will stay with the Symposium in the role of Founding Chairman. Malte Jaensch justifiably praised his predecessor’s work for CTI as a “lifetime achievement.”

For nearly 25 years, Professor Küçükay shaped the themes of the CTI Symposium, and oversaw a number of paradigm shifts along the way. It all began in late 2000, just after Professor Küçükay became head of the Institute of Automotive Engineering at the TU Braunschweig. One day, he took a call from Sylvia Zenzinger, now the symposium’s conference director. Would he be interested in chairing a new congress on vehicle drives? Küçükay agreed right away.

Since then, both the Symposium’s topics and its tagline have evolved steadily. In 2010, hybrid and electric drives were added to the programme and tagline. Recently, “Automotive Drivetrains, Intelligent, Electrified” has reflected the growing importance of electrification. Today, the CTI Symposium is a major international event, with presentations held exclusively in English.

This December, the Symposium changed its tagline to “Automotive Powertrain Systems”. This reflects two current developments: Firstly, that electrification is now a perfectly normal powertrain topic; secondly, that adopting a system view is crucial when developing vehicle drives.

The BEV for Everybody
As Professor Malte Jaensch specified in his opening speech, we need to consider the powertrain as a system and understand how all the individual components work. That starts with electric motors, gearboxes for elctric drives, inverters and batteries – and extends right up to the overall vehicle and, of course, the consumers’ wishes.

With BEVs, another question is how to make them affordable for everyone. In Berlin, this was the focus of the Executive Discussion “The BEV for Everybody”, with participants Karsten Bennewitz, Volkswagen, Marcus Lott, Opel, Prof. Maximilian Fichtner, Helmholtz Institute Ulm, and David Green from Lynk.

The first question was, “When will BEVs dominate the vehicle market?” Using their voting app, the majority of audience members said it would be when cost parity was achieved with other drive types. In second place came adequate infrastructure, followed by sufficient range and/or faster charging times.

On costs, Bennewitz agreed that we need to approach cost parity, but said Germany already had an adequate charging infrastructure, with high numbers of fast charging stations. He cited fun-to-drive as a further important factor for winning over consumers to BEV. From an OEM perspective, he does not foresee an immediate switch to BEV, saying markets such as India had totally different requirements.

Marcus Lott took a similar view. He said combustion engines are still needed for other markets, but PSA and Opel have started their electric transformation process early on, driven by legislation. If legislation were to develop less stringently in Europe, reverting to conventional drives would not pose a problem. That said, consumers who switch to BEV “never go back”. As for costs, the competition in China is making us “fit and lean”.

David Green, from the Geely subsidiary Lynk, said other forms of ownership were a way to reduce costs. Lynk’s offering includes a subscription model that could be canceled at any time, but also a
rental model that increases vehicle use times, and thus distributes costs more effectively over the life cycle. Unlike Bennewitz, Green thinks charging options could be improved, noting that ‘BEV for Everybody’ would not work if you lived in an apartment in Munich, or any other urban area with poor charging availability.

For Professor Fichtner, a battery expert at the Helmholtz Institute, the main lever for making BEVs affordable is new battery technology. In future, he said, charging times of ten minutes for a range of 700 km would be possible. In addition, cost issues should be bundled with other issues: whereas batteries can be recycled, fossil fuels are “gone” once you burn them.

The discussion may have been a starting point for further questions in the future. One may be: How can we make make used BEVs more attractive, for example through more hardware and software update abilities?

The advent of new battery technologies
But back to batteries for now: Prof. Fichtner examined batteries more closely in his plenary speech, “Recent trends in battery research and development”. Given the growth of e-mobility, he said, Europe would need a production capacity of around 1 TWh in 2030, compared to just 21 kWh in 2020. On the other hand, we need higher numbers of sustainable batteries, and hence new raw materials. On the cathode side, these would lithium iron phosphate (LiFePO4), lithium manganese oxide (LiNi3/4Mn1/4O2) and nickel manganese (LiMnO2), all without cobalt. New anode materials were also expected, such as silicon carbon composites. These would enable 40% more energy content at cell level, putting them on a par with solid-state batteries – a technology he said has had a great future for a long time, but one that might not materialize.

In future, sodium batteries would enable batteries that required no critical raw materials. And generally, lithium, nickel, cobalt, graphite and copper could be replaced by sodium, iron, magnesium, hard carbon and aluminum. Since some new developments would mean reduced energy density, Fichtner advocates close collaboration between chemists and engineers in order to optimize battery weight and packaging at the construction level. He cited CATL‘s cell-to-pack process as an example.

Battery topics were also discussed intensively in the Deep Dive sessions. Presentations by TotalEnergies and Valeo covered cooling aspects, while APL reported on “Mastering Thermal Runaway” and Marelli dealt with wireless battery management systems.

Remarkable progress in e-motors and e-drives
As to future electric drives, Jörg Gindele from Magna Powertrain talked about the companies next gen e-drive portfolio. He said system efficiency of the new development is 93% (motor efficiency 96.3%), namely in WLTC and with additional highway components – so basically, in real life operation.

The high system-level efficiency is due to the significantly expanded sweet spot, Gindele said. This also helped for what Magna calls the ‘complementary operation’ of the front and rear axle drives. Basically, this means the gear ratio of the front primary drive can be made longer, and hence more efficient, while the secondary (rear) drive, which can be activated at will, can be configured for performance.

A few design features: The drive is so compact that it can tilt 90 degrees and be used on either the front or rear axle. To optimize motor costs, the magnets are fixed by mechanical means only, using flaps. The active fluid control system uses a pump actuator taken from transmission technology. Since its direction of rotation is reversible, the oil flow can, for example, be distributed between the motor shaft and the winding heads. An HV Embedding process reduces shift losses, while Optimized Pulse Patterns smooth out the drive’s pulse – and hence vibration – behavior.

Gindele concluded with an outlook for further goals in tomorrow’s drives. These included new magnet-free motor concepts, the elimination of rare earths, GaN architectures for both 800 and 400 V, and further digitalization, for example the Digital Energy Twin, to improve range prediction.

His speech is just one example for the lively development activitiy in the e-drive field. In Berlin, no fewer than three Deep Dive sessions with over 14 presentations were dedicated to e-motors and e-drives. Just a few examples:

Volkswagen presented their new electric MEB platform in detail. Great wall introduced the e-drive architecture of their ORA Lightning Cat. DeepDrive talked about the advantes of the radial-flux electric machines. New e-motor technologies and approaches were presented by ZF, Infimotion, BorgWarner, Dana and Valeo. American Axle discussed solutions for high-speed e-motors, Valeo talked about optimizing e-drive efficiency. AVL List presented their development process for an e-drive system, and Hofer Powertrain several torque vectoring solutions for unique markets.

This short list shows how manifold the e-drive topic is and there is much more to come and discuss on upcoming CTI symposia.

How are OEMs electrifying?
Volkswagen, Mercedes-Benz and Opel gave insights into their plans for further electrification.

In his plenary speech, Thorsten Jablonski showed how the Volkswagen Components Group was transforming itself into an Electric Powertrain Supplier. Until recently, the group and its 69,000 employees manufactured transmissions, combustion engines and more. Today, it’s becoming an electric drive supplier with a holistic perspective that includes e-drives, inverters, batteries and thermal management, as well as their system integration. In future, Jablonski said, the SSP platform (Scalable Systems Platform) would be used in a scalable manner for all Group brands and segments. His comments on scalable battery technology were equally interesting: At its Powerco subsidiary in Salzgitter, Volkswagen is planning different cell chemistries for different vehicle segments: iron phosphate for the entry level, high manganese for the mass market, and increased silicon content as a best-in-class application.

Konstantin Neiß, Mercedes-Benz, began his plenary speech by reiterating his company‘s commitment to becoming CO2-neutral by 2039. He said Mercedes was also investing in transforming its Stuttgart plant for more electrification, with a focus on batteries and e-drives. This includes small series production of Li-ion cells, though Mercedes plans to buy in more from various sources. Neiß also mentioned the acquisition of Yasa, which will produce performance electric motors at its Berlin factory. In 2025, Mercedes plans to launch its first ‘electric first’ platform (MMA), for which combustion engines are just one of several options. Neiß then showed a vehicle based on this MMA platform: the Concept CLA Class. He put the powertrain overall efficiency at 93%, with an energy consumption as low as 12 kWh per 100 km. The range would be 750 km (WLTC), and 400 km of range could be ‘refueled’ in 15 minutes. The speaker then touched briefly on the Vision One-Eleven vehicle, which features axial flux machines by Yasa. The advantages of this design: very short, very good continuous performance, and low weight.

In his plenary speech, Marcus Lott, Opel, talked about the “BEV for Everybody” that Opel and its parent company Stellantis are striving for. From 2024, Opel wants to offer at least one BEV in every vehicle series; from 2025 on, every new launch would be a BEV. In future, Opel would have access to four Stellantis platforms with ranges of 500 to 800 km. The group was pursuing a circular strategy for batteries, including a ‘second life’ and materials recycling. Lott noted that Opel has also offered an FCEV transporter – the Vivaro-e Hydrogen – since 2021. The design is interesting: a 45 kW fuel cell stack, and a battery and electric drive with a maximum output of 100 kW each. At 10.5 kWh, the battery is fairly large and provides around 50 km of electric driving; the total range is 400 km. Opel describe this as a “mid-power concept” with an optimal balance of customer benefits. In 2023, Lott said, Europe had over 150 700-bar gas stations; by the end of 2025, that should rise to more than 450. According to the EU AFIR (EU Alternative Fuels Infrastructure Regulation), from 2030 on filling stations of this type will be mandatory every 200 km, plus an additional station at every urban node.

Heavy commercial vehicles have diverse requirements
Requirements in the heavy commercial vehicle segment are different from those for passenger cars, as the Expert Discussion “Who Will Take the Heavy-Duty Vehicle Volume – FCEV, Green ICE or BEV?” confirmed. The participants were Gernot Graf, AVL, Michael Himmen, Hydrogenics, Loek van Seeters, DAF, and Götz von Esebeck, Traton.

Right at the start, audience members were able to cast their app votes in response to the question: “Which drive concept will take the volume in heavy-duty vehicles in the long run?” Multiple answers were permitted. Overall, 47% said BEV, 45% FCEV, 31% H2 combustion, 22% e-fuels, 18% HEV and 14% diesel engines. This showed just how diverse the possible solutions are considered to be.

This diversity was reflected in the views of the discussion participants. Gernot Graf argued in favor of hydrogen for both FCEVs and combustion engines, saying fuel cell had an efficiency of around 50%, a combustion engine slightly more. He said, it all depends on the application: Above a certain performance threshold, you need a combustion engine with its better power-to-weight ratio. Fuel cell are better under partial load, combustion engines at high and full load.

Götz von Esebeck was sure that BEV would dominate in terms of volume. In the transport business, he said, TCO is king, and electricity weill be the cheapest option in future. He even sees opportunities for BEV on long hauls, especially since fast charging were not an issue for the large batteries involved. Of course, the infrastructure would need to be built first.

For Michael Himmen there is no “super answer for all”. Fuel cell would come; there is a “momentum”, he said, as the industry has special requirements in terms of weight and distance. Transporting goods from Poland to Spain, for example, would remain challenging for a long time to come. Markets like India would still need ICEs for many years, due to the lack of infrastructure. Interestingly, Himmen also sees fuel cell mainly for stationary applications. He said Hydrogenics and its parent company Cummins were covering this aspect as well.

In the discussion and the plenary speech he gave earlier, Loek van Seeters spoke in favor of developing all drive options, then seeing which prevailed. After all, new technologies needed a certain ramp-up time. Today we still needed diesel engines; drives that used no fossil fuels would not arrive around 2040 – but DAF is committed to developing them. In his talk, the speaker presented the manufacturer‘s range of drives for commercial vehicles. Besides conventional drives, this includes hybrid drives, purely electric tractors and, as of 2021, a tractor with a hydrogen combustion engine. But in order to achieve the EU goal of reducing CO2 emissions from electrically powered trucks and buses by 45% by 2030, he said a lot more would have to happen. Per year, 42 TWh – the equivalent of 17 million households or 11 nuclear power plants – would have to be upgraded. We also needed 280,000 charging stations and 50,000 public charging stations; the rollout is still progressing far too slowly, he said.

AI – the 5th revolution?
Another topic is currently growing at breakneck speed: artificial intelligence. The catalyst here may have been ChatGPT, the AI tool that is already being used for automated text creation.

In Berlin, Hamidreza Hosseini, CEO of Ecodynamics GmbH, gave a highly anticipated speech entitled: “GenAI, & ChatGPT‘s Impact on Future Automotive Development and Engineering”. Hosseini described and demonstrated how generative AI can also change processes in the automotive industry. GenAI can generate new content by processing patterns drawn from training data; ChatGPT, now familiar to many people, is just one part of it.

Hosseini also pointed out that ethical issues are involved, and that systemic transparency is a prerequisite for using AI tools of this kind. But what stuck most in listeners’ minds was the message that artificial intelligence could change work processes in the automotive industry very quickly. Hosseini spoke of a 5th industrial revolution, adding that others could follow. In 50 to 60 years’ time, the “merging of humans and machines” could be next.

The CTI symposium helps shaping the transition
What were the key learnings from the CTI Symposium Berlin? Summing up, chairperson Prof. Malte Jaensch mentioned several points. Firstly, it’s becoming more and more important to see the powertrain as a system – a development that is reflected in the new symposium tagline “Automotive Powertrain Systems”. Secondly, there is no such thing as “one size fits all”. Instead, we need to strike the optimal balance between sustainability, development, production, cost, efficiency and more besides.

Thirdly, as the conference showed, drive options for heavy-duty vehicles were more varied than for passenger cars. All the same, it was important for passenger car and heavy-duty developers to exchange ideas at the CTI Symposium, and to learn from each other across functional and product boundaries.

In general – and despite the importance of overall systems – powertrains would always be at the heart of the CTI symposium, Jaensch added. That said, there would be changes. The topic of AI in automotive engineering could – and probably will – be accompanied by a growing number of lectures and discussions. Jaensch said we should see this as an opportunity, not a threat.

He also mentioned the topic of “Energy Formability,” which essentially places the system idea in a larger context. Powertrains alone could not be “green”; instead, we must consider drives, mobility and energy together as a whole. This included topics such as bidirectional charging, vehicle-to-x or “second life of batteries”, which could likewise become symposium topics in future.

The next CTI Symposium Berlin is scheduled for 3 – 4 December 2024. The next US symposium takes place much earlier (15 – 16 May 2024, in Novi near Detroit), and we warmly invite you to attend.

“Serial-parallel hybrid designs will become increasingly popular”

At the CTI Symposium USA in May 2024, Aditya Dattawadkar, Schaeffler, presented recent advances in hybrid architectures in his talk “Hybrids are Making a Comeback”. In our interview, we followed up by asking: What will tomorrow’s hybrid drives look like?

Interest in hybrids has been growing again recently in the US, as well as in the UK for example. Why would you say that is?

I think right now, people everywhere are looking for an option that lets them try going electric as they look for better performance or more fuel economy. Because of range and charging network availability, many don’t want to jump straight from an engine-based car to a battery-electric. That’s where hybrids come in. They allow people to try these electric vehicles, let’s say semi-electric vehicles, without jumping straight to BEV. And whether it’s in the US, UK or somewhere else, I think the challenges and anxieties are similar.

Powertrain diversity is generally increasing. How would you differentiate between designs for various vehicle segments – for example B to E and SUVs or pick-up trucks?

If someone buys a smaller vehicle, they will likely lean towards a battery electric vehicle, as long as the price is OK and it has a decent range. People mostly use them for daily commuting or for short-distance travel. But bigger vehicles, like SUVs or pick-up trucks, are generally meant for longer distances – towing boats or trailers, transporting bigger families, and so on. That’s where hybrids are better suited, either as plug-ins or full hybrids. Whether you choose plug-in or full hybrid will depend on efficiency calculations. If you’re constantly driving long distances, a full hybrid might be better than a plug-in because you reduce the amount of energy conversions or carry a smaller size motor. Additionally, the city v/s highway driving can influence these calculations. But if you want to sample the flavor of a battery-electric vehicle, a plug-in hybrid is a good solution.

So far, most hybrid designs in western markets have been add-on P2 designs, not dedicated solutions. Which type would you recommend?

Part of the reason why P2 designs have been popular is because you can fit them in into existing powertrains with less difficulty. You don’t need to change the engine design; you don’t have to change the transmission architecture significantly. Having said that, I think in future, serial-parallel designs will see increased adoption. Then of course a P1/P3 multimode transmission like ours also has great potential in my opinion. We will probably see that each of these solutions has an advantage for a specific application. When hybrids started, they were basically an electric motor that supported the ICE. Now we’re going to see hybrids that are more of an electric vehicle, with an ICE for support. So, it’s going to be a different type of hybrid than what we’ve seen in the past.

Will multimode hybrids and range extenders replace P2 designs, or is there still a place for them?

Serial and multimode hybrids make a lot of sense for people with flexible driving habits. But P2 still makes most sense for people who have consistently longer drives and heavy load requirements, because we don’t want to get into ICE recharging mode regularly. Due to the additional energy conversions, the goal should be to use the feature of recharging battery with ICE in serial hybrids only occasionally when necessary. Based on use cases of individuals every hybrid architecture provides some advantages based on the application.

How close can a PHEV with a suitable drive architecture get to a BEV in terms of efficiency, in electric operation?

I think it’s a little bit unfair to compare the efficiency of PHEVs and BEVs, because the goal of a PHEV is to let you drive electrically for a limited range. PHEVs exist because today’s battery-electric vehicles can’t meet every customer’s needs, especially their long-range needs. A fair question might be whether PHEVs are better than the ICEs we have. I think they are, because you can charge them with an outlet. So, then you have a cleaner source of energy for driving in cities, where you want to focus on limiting emissions due to congestion. One has the ability to use some PHEVs similar to BEVs for limited range.

China announced last year that the ICE would be needed up until 2060. Looking at the US and Europe, what prospects do you see for HEVs and PHEVs?

It’s really hard to predict what kind of drives we will have in 2060. Just ten or fifteen years ago, people were only just starting to talk about battery electric vehicles and plug-in hybrid drives as mainstream vehicles. Now battery-electric vehicles are already at ten percent, or much higher if you include plug-ins and hybrids. I think there is a lot of strong motivation to go to electric drives. In particular, tech innovations in the fields of batteries, charging infrastructure and charging speed could change things quickly. What is more predictable is, say, 10 to 15 years ahead. On that horizon, I expect to see all three options: ICE, hybrids, and battery electric vehicles.

Interview: Gernot Goppelt

Interview “Digital Twin enables a whole new functional level”

At the CTI Symposium Berlin in December 2023, Dr Jörg Gindele, Magna Powertrain, spoke on progress in new electric drives. We interviewed him about new developments in hardware and software, functional integration on a higher software level – and the new possibilities that the ‚Digital Twin‘ opens up.

Dr Gindele, you presented a new generation of electric drives at the CTI Symposium in Berlin. What is new?

We’ve made improvements in many areas. First of all, we increased efficiency further still with an improved electromagnetic design. One particular highlight is that we managed to expand the sweet spot significantly. In this context, I want to mention the cooperation with our JV partner LG Magna, who contributed several improvements here. We also implemented several improvements at the system level, such as improved cooling and reduced ohmic and inductive scattering losses. I’d like to give three more innovations a special mention: active fluid control, which uses a pump actuator to distribute cooling flows flexibly between the motor shaft and the winding heads; HV module embedding, which enables us to design a highly integrated semiconductor package that’s integrated into the inverter; and software-optimized pulse patterns, which further reduce electric motor and inverter losses.

The importance of software-level integration into the overall system is growing. How does the new generation reflect this?

Our main focus is on stronger integration at the system level. Software is the enabler here. For example, our Motion and Energy Control software can control the electric motors and the brakes simultaneously; it integrates their functionalities on a higher level. That benefits driving dynamics considerably and also improves driving safety. Another example is the way the thermal management system interacts with the drive control. This means you can coordinate the energy flows, and use them synergistically. We have developed a new software platform that can regulate the entire energy and power flow in BEVs. Additional new features are available as cloud-based functions. These enable predictive driving functionalities, as well as a row of applications.

You also spoke about ‘complementary electric all-wheel drives’. What does that mean?

It means coordinating the drive units in a 4WD system in such a way that they complement each other in various operating scenarios. This can deliver even higher energy efficiency than a 2WD system. Put simply, you give the primary drive unit a longer gear ratio, which is good for efficiency. The secondary drive unit, which is usually on the rear axle, is mainly for high available torque. In terms of efficiency, you could say the result of this interaction is ‘guilt-free’ performance. With features like its expanded sweet spot, our new-generation drive is designed for just such a system. And thanks to its compact package, it can be used flexibly on either the front or the rear axle.

You could also use a two-speed transmission. What are your thoughts on that?

Multi-speed transmissions can certainly make better use of the efficiency map, and also improve climbing and towing performance. But in many of today’s drive solutions, the extra effort involved outweighs the benefits. That said, they are worth considering in applications like performance vehicles, pickup trucks, or light commercial vehicles. Looking ahead, another interesting aspect is that by teaming up multi-speed transmissions with new types of e-machines, we could potentially make system-level solutions that require no rare earths.

What does the ‘Digital Twin’ do in the new drive generation?

Digitalization plays a key role in lifting drive technology to a new functional level, while also saving time and money during development. The Digital Twin is a precise digital image of the product you are developing. It helps you to reach higher levels of maturity faster, and to avoid many expensive and time-consuming hardware loops. In series applications, a Digital Twin lets you catch quality issues faster and monitor the ‘health’ of your product. But the possibilities go far beyond that. Another example is improved range forecasts, based on the accuracy that a Digital Twin model provides. And that‘s just the beginning – the possibilities seem to be almost infinite.

Interview: Gernot Goppelt