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Preview of presentation at the CTI Symposium USA: Kumar Rajasekhara, Marsilli North America

Posted on 9th May 2023

Watch the video of Mr Rajasekhara with first insights into his lecture
“Stator and Rotor Winding Innovations for Automotive High-Voltage E-Traction Drives”
at the CTI Symposium USA.“

Tomorrow’s electromobility – carbon-free and full of innovations

Posted on 25th April 2023

Automotive mobility is saying farewell to combustion engines and heading for a carbon-free electric future. This far-reaching technology shift is stimulating the creativity and innovative powers of developers. Their intelligent solutions not only support sustainability and global climate protection, but also convince, or even inspire, customers in daily life. Next-generation EVs are playing to their inherent strengths – and lifting comfort, driving dynamics and safety to the next level.

The CTI Symposium USA – where ideas compete to shape progress

In the plenum, experts and decision-makers from leading OEMs and suppliers will present their strategies and technologies live. Hear all the facts – and join in the discussion yourself. Our twelve Deep Dive sessions have all the latest electric drive systems and key components covered. Get an overview of what’s happening, and discover interesting aspects such as cutting-edge series products, realistic market research, and a teardown semiconductor comparison.

Magna EtelligentReach – advanced e-drive double act to enter series production

In early 2021, Magna unveiled its EtelligentReach electric all-wheel drive (eAWD), which achieved a new level of driving dynamics and range. The second generation followed in 2022 and included further improvements in lateral dynamics, plus even higher system efficiency. Now Dr. Daniel Lindvai-Soos, (Magna Powertrain, Austria) will be reporting on the Magna eAWD technology that will soon be entering production in a new series EV model.

The eAWD technology doubles overall power without significantly reducing range. The enabling factors include a complementary powertrain layout in which the primary and secondary drives interact. Key components include dedicated optimized inverters for both drives, the latest high-efficiency electric motors, a decoupling system for the secondary drive, and an intelligent operating strategy.

As eAWD shows, high-performance motors and efficiency need not be mutually exclusive. In this system, the driving strategy uses the motors’ efficiency maps in a way that can improve overall efficiency. Magna’s EtelligentReach technology also provides longitudinal torque vectoring, for excellent levels of ride control and active safety. In his presentation, Dr. Lindvai-Soos will describe the overall powertrain system approach and the components involved in detail. The speaker will place particular emphasis on the e-motor and inverter technology, the complementary system approach, and further opportunities through the integration of advanced ADAS and Connectivity.

What do owners love and hate about their EVs? A survey and its implications

When it comes to improving product quality, the best policy is to listen carefully to the praise and criticism your customers can offer. The consulting firm Strategic Vision systematically surveys new EV buyers in the USA and China. Evaluations are based on authentic statements from owners. “They tell us what they love about their vehicles, and what they hate,” says Paul Haelterman (Strategic Vision, USA). His presentation will focus on three key areas: battery range, Human Machine Interface (HMI) and Advanced Driver Assistance System (ADAS).

Strategic Vision’s methodology has already been validated in numerous countries. The insights distilled from tens of thousands of surveys reflect what people really think, and how they make decisions. The main conclusions Paul Haelterman presents will show how well consumer needs are being met, how wide the expectation gap is, and whether upcoming technologies will be able to close it. Particularly in China, new technologies will likely be presented soon.

Semiconductors as efficiency boosters; silicon carbide too costly for Tesla. What do experts say?

The fact that next-generation electric drives offer greater motor efficiency across multiple driving scenarios, plus impressive ranges and shorter charging times, is largely due to sophisticated semiconductor technology. The arrival of bidirectional charging, where the charger also feeds electricity from the car into the smart grid, likewise calls for high-performance semiconductors.

In his plenary lecture, Patrick Leteinturier (Infineon, Germany) will therefore describe semiconductors as a key technology for tomorrow’s smart, green mobility. Infineon offers a broad portfolio of highly developed semiconductor modules for all relevant EV applications, and is continuously working on innovative solutions. For CTI Symposium USA attendees, Patrick Leteinturier’s outlook is sure to be of great interest.

“75 percent less silicon carbide!” When Tesla announced this target for its new drive unit at the Tesla Investor Day in early March 2023, people sat up and took notice. SiC technology enables highly efficient, ultra-compact inverters – but due to high costs and scalability issues, the jury is still out.

Wolfspeed is a leading semiconductor manufacturer that specializes in silicon carbide. Jeff Casadi (Wolfspeed, USA) will explain the specific challenges that arise when developing and producing silicon carbide power components specifically for EV drivetrains. He will provide insights into work, studies and data across the entire product lifecycle. One focus point will be silicon carbide’s reliability, from initial qualification through long-term wear mechanisms during service life to end-of-life failure. The speaker will also discuss manufacturing scalability across the entire vertical supply chain.

Dr. Yu Yang (Yole Intelligence, France) will present a detailed roadmap for power modules used in main inverter applications. The analysis will cover key aspects such as substrates, packaging technology and cooling, incorporating key technological trends. An in-house Teardown Comparison of the latest Si IGBT and SiC MOSFET power modules offers detailed insights into their outer profiles, internal geometries, detailed interconnection and material analysis, based on a well-defined methodology at Yole System Plus. The modules analyzed come from Denso, STMicroelectronics, Wolfspeed and other manufacturers.

Mercedes-AMG GT 63 S E PERFORMANCE – turbocharged with adrenaline

If needed, drivers have a massive 620 kW (843 hp) of power and 1,400 Nm of torque at their command. If they use it, the iconic sound of the Mercedes-AMG GT 63 S E PERFORMANCE is sure to remind them that they are pushing performance to the max. Driving out of the garage and through the suburbs, on the other hand, is silent, emission-free and electric.

The most powerful Mercedes-AMG supercar to date is also the first to feature a plug-in hybrid drive. As Joe Mueller (American Axle Manufacturing, USA) will explain, the rear axle Electric Drive Unit (EDU) is supplied by AAM. By electrifying its premium AMG models, Mercedes is able to meet tighter vehicle emissions regulations while simultaneously improving the driving performance its customers expect. This vehicle can accelerate from 0-60 mph in a breathtaking 2.9 seconds, yet fuel consumption is surprisingly low – a perfect example of boosting and recuperation working as a team.

AAM’s P3 EDU comprises a Permanent Synchronous e-Machine (PSM), an electrically actuated two-speed transmission, and an electronic limited slip differential. It is housed in the rear axle. AAM’s compact, yet powerful power unit requires no significant modifications to the vehicle’s powertrain or body structure. In his presentation, Joe Mueller will detail the EDU’s design features and illustrate the resulting performance characteristics, using pictures and videos taken during lab and in-car testing.

The Mercedes-AMG GT 63 S E PERFORMANCE EDU follows the successful Jaguar I-PACE EDU, which launched in 2018. AAM has also secured further orders globally for electric drives that will launch before 2025.

The CTI Symposium USA – from plenary hall to test track

Plan your trip to the 17th CTI Symposium USA now – and compile your very own two-day program packed with highlights. Which plenary speeches and discussions are top of your list? Which of the twelve Deep Dive sessions interest you most? During the breaks, you can check out important innovations for yourself at the CTI Expo – or experience the latest EV innovations at first hand in a series or demo vehicle on the CTI Ride & Drive parcours. As for networking, the CTI Networking Night @Meadow Brook Hall is the place to be. Chat with colleagues, speakers, exhibitors and sponsors over delicious food and drinks – and make valuable new business contacts in a relaxed atmosphere.

Welcome to the CTI Symposium USA!

Visit the CTI SYMPOSIUM USA

Optimum sustainability, performance or cost effectiveness? Choose all three!

Posted on 12th April 2023

Tomorrow’s automotive mobility will be sustainable and carbon neutral. While that would be impossible for internal combustion engines, for battery-electric drives the goal is in sight. From the considerable heights already scaled, developers are aiming higher still by improving the operation and production of electric motors. Innovative technologies are boosting efficiency and range while lowering costs; valuable raw materials are being used more sparingly; and CO₂ balances are improving, even during production.

Highly efficient – just like the CTI Symposium USA

At the CTI Symposium USA, experts and decision-makers from leading OEMs and suppliers will present their strategies and technologies for tomorrow’s carbon neutral mobility. Come and get the latest information live at first hand – and contribute to the discussion yourself. Explore the latest electric drive systems and their key components in twelve Deep Dive sessions. Discover the developments and field results that matter for you. On two days, in a single location, all this and more awaits you.

A comprehensive range of electric motors (PM, ASM, SSM, HPM), plus a star

Switching to electric drives is an urgent necessity. At the same time, the process is also paying off for companies and releasing synergies. “By continuously focusing on electric motor development, we have found further improvements in reducing our CO₂ footprint during production, all while improving efficiency,” says Jonathan Getz (Schaeffler, USA).

Schaeffler’s broad range of modular electric motors offers ideal solutions for the diverse challenges posed by the world’s growing variety of electric drive vehicles. From traditional PSM motors to advanced magnet-free motors with powered rotor coils, sustainability is always baked in. Schaeffler uses special tools for eMotor optimization that take torque, power, efficiency, strength and NVH into account, all while balancing the financial and environmental costs of the motor.

As a special example of this development work, Jonathan Getz will highlight the Separately-Excited Synchronous Motor (SSM). Here, replacing the permanent magnets with rotor windings has substantially reduced both the CO₂ footprint during production, and the dependency on rare earth materials. Special optimizations to the cooling system, plus the use of brushless, inductive transmitters, further boost the motor’s efficiency.

Schaeffler’s advanced PSM, ASM, SSM and HPM (Hybrid Permanent Magnet) motors for different applications offer solutions that are efficient and sustainable, yet also cost effective. The electric motor designs can be applied to build to print, build to motor, and even build to system specifications.

WLTC is too imprecise – more highway, more range for LCV

Light commercial vehicles (LCV) in particular are virtually made for battery-electric drives, says Daniele Zecchetti (Marelli Europe, Italy) in his introduction. As delivery vehicles, their local emission-free operation guarantees them access to current and future urban clean air zones. The electric drive ensures low downtime and service costs, and range is rarely an issue because vehicles can charge at the depot overnight.

Essentially, this performance profile is what defines LCV electric drive specifications, whereby both LCVs and passenger cars use WLTC to certify emissions and fuel consumption, or to measure their electric range. But today, that strong focus on urban deliveries is no longer enough for battery-electric LCVs. Good efficiency and range in extra-urban and typical highway conditions, with maximum payload, have also begun to influence electric powertrain specifications and design.

Marelli has developed a method for systematically developing and optimizing electric motor design according to defined requirements. Daniele Zecchetti will explain the tool chain used, and will present the results of vehicle simulations in relevant cycles. The goal was to find the best compromise between range, maximum total weight and costs for LCV electric drives, in line with the new framework parameters.

Convincing technology, low cost – a wheel hub drive that forces you to think again

“Today’s electric vehicles still suffer from low efficiency and insufficient range, especially in cold weather and when driving on the freeway,” says Dr. Alexander Rosen, co-founder of the German start-up DeepDrive. In WLTP and EPA, the average plug-to-wheel efficiency of modern electric vehicles is below 60%. Now DeepDrive has developed a new motor architecture for in-wheel motors that focuses on high efficiency, especially in everyday driving situations.

The motor topology is based on a highly innovative radial flux approach with novel winding technology. The no-transmission motor presented by the speaker offers high specific torque densities of up to 60 Nm/kg. The special design of the stator reduces iron losses and enables very high efficiency levels, especially in the partial load range. Dr. Rosen will discuss in depth the critical issue of unsprung masses; the solution includes the innovative integration of a lightweight brake system.

Until now, the main obstacle for wheel hub drives has been their cost. Dr. Rosen will counter this by showing how the DeepDrive wheel hub drive combines sparing use of materials  (e.g. for the magnetic mass and sheet metal packages) with simple, cost-effective manufacturing processes (e.g. for the windings).

His case study for a mid-size vehicle will show how these wheel hub drives can reduce EV purchase and operating costs by up to €5,000 while also increasing range by 20% with the same battery capacity. The drives are suitable for all EV types, from compact cars to premium SUVs and even sports cars.

The heart of the electric motor – innovative solutions for rotor and stator windings

To a large extent, coil windings are what determine the efficiency and cost-effectiveness of electric traction motors. So in addition to the established stator manufacturing processes (hairpin and insertion technology) and wound rotors (flyer and needle windings), there is still a demand for innovations – especially with the shift toward higher voltages in e-traction drives.

Summing up his company’s strategy, Kumar Rajasekhara (Marsilli, USA) has this to say: “We have developed solutions that get the best out of traditional technologies by combining their advantages, and reducing their drawbacks.”

The speaker will begin his presentation with an update on the latest developments in Marsilli’s Distributed High Density (DHD) stator winding technology. This patented winding solution is specifically used to reduce high-frequency losses and ensure high flexibility in e-motor design and the winding scheme, and also boasts a high fill factor. Last year, the winding technology was introduced to the North American market with a comparative analysis based on 400V, 3,500 RPM DHD-wound motors. This year, Marsilli will present study results in which DHD-wound prototypes also performed well at higher voltage (800V) and higher (18,000) RPM.

As his second focus point, Kumar Rajasekhara will cover new rotor winding technologies for Externally Excited Synchronous Motors (EESM). Marsilli has developed two new solutions for high performing rotors that achieve the winding scheme stability and geometric winding scheme accuracy demanded by high-voltage drives. The speaker will present and analyze the features, functionality, differences and use cases of both solutions in detail.

Production lines for hairpin stators – processes, modules and surprising insights into copper wires

Since EV drive motors need stators in large quantities – and will continue to do so in future –, flexible and highly efficient production lines are required in order to meet market demand. Matthias Weber (Felsomat, Germany) will describe the latest developments in hairpin stator manufacturing. When designing customer-specific configurations, the entire process chain, modular processing machines and buffer loops are all examined.

The most critical part of the hairpin stator is the CU wire used. The composition and material specifications needed for this wire go beyond the specifications that are commonly listed. This leaves automotive OEMs and stator line manufacturers in the dark, a situation Felsomat was not prepared to accept. “We have carried out many trials, laboratory and specification tests, leading to endless application adjustments,” says Matthias Weber. The speaker will share these insights with his audience. The knowledge obtained through researching material properties and tolerances plays a key role in enabling production lines to run at optimal speeds and tolerances, and contributes directly to optimal stator quality.

Turn off your screen – and come to CTI Symposium USA

Get out of the office for two days and visit the CTI Symposium USA! Follow the discussions live in the plenum, then catch up on the latest news from your specialist field in the sessions. During the breaks, check out important innovations by taking a tour of CTI Expo. Series and demo vehicles await you at our CTI Ride & Drive parcours, where you can experience real-world progress in electric propulsion for yourself, either behind the wheel or as a passenger. As for networking, the CTI Networking Night @Meadow Brook Hall is the place to be. Get talking with colleagues, speakers, exhibitors and sponsors over delicious food and drinks – and make valuable new business contacts in a relaxed atmosphere!

Welcome to the CTI Symposium USA.

Visit the CTI SYMPOSIUM USA

Development if a multi-Speed Two-Drive-Powertrain

Posted on 17th March 2023

Aaron Kappes , Steffen Frei , Sebastian Luz , Prof. Stephan Rinderknecht, Institute for Mechatronic Systems, TU Darmstadt; Institute for power electronics and control of drives, TU Darmstadt

An electric Two-Drive-Powertrain using two electric machines is presented, which allows a highly efficient over all usage. The multi-motor approach achieves a downsizing effect, when one motor is deactivated during moderate driving. The novel features of the powertrain are its electric synchronized dog clutches and its two highly overloadable electric machines, each connected to a two-speed sub transmission providing a total of four different electric speeds. This arrangement enables full torque support during shifting processes. In addition, the waste heat from the inverters and the electric machines is used for heating the transmission oil under cold environmental conditions, thus increasing efficiency. Furthermore, the possibility and advantages of adding an internal combustion engine mechanically linked to both sub transmissions and its realization in a public founded project is addressed.

Introduction

Increasing efficiency is a major target in the development of electric drivetrains. In parallel to established BEVs with one electric motor and a fixed transmission ratio, multi-speed [1, 2] and multi-motor [3, 4, 5] con-cepts are gaining importance. At the IMS of the TU Darmstadt, research is focused on multi-motor and multi-speed drives called TDT („Two-Drive-Transmission“). These electric drives combine high efficiency and performance by using a downsizing effect, according to which a highly utilized electric drive can be operated more efficiently than a large one in its corresponding partial load.

The conceptual benefits of an all-electric concept with two small electric machines with two speeds each, called TDT22, have al-ready been outlined in [6]. Efficiency advantages of up to 8.3% were identified for urban use compared to a benchmark fixed speed BEV. For short and slow driving, there is almost no alternative to a BEV from an ecological point of view. When it comes to long range, [7] stated that it is currently not reasonable to realize high ranges by using larger and heavier batteries. The battery capacity of BEVs ca-pable of reliably reaching distances greater than 500 km increases to more than 100 kWh. A current P2 hybrid concept with optimized energy storage sizes and propulsion machines shows poten-tial to reduce the CO2 footprint from cradle to grave because of its smaller battery. To achieve this, however, it must be charged regularly and driven mainly electrical. In addition, there are user benefits such as rapid refueling e.g., using renewable fuels in the future if an even longer distance is to be covered.

With these potentials in perspective, this paper will focus on the de-velopment of a hybrid version of a TDT22 already mentioned in [8]; a TDT4LR („Two-Drive-Transmission for Long Range“). This concept is based on a DRT (Dedicated Range-Extender Transmission) and is cur-rently being developed and built in the public funded Project DE4LoRa for a dedicated use case.

1. Development

The vehicle being developed in DE4LoRa is designed for a typical German average user and leaves a minimal environmental footprint. According to the “Kraftfahrt-Bundesamt” [9] the 101-110 kW power class contained in 2020 by far the most new-registrations in one of the dis-crete subdivisions. This number was only topped by the open-ended category of more than 151 kW. At the same time, the most frequently registered class was the rather unspecific one of SUVs, closely followed by the C-segment [10]. As the former is not suited for an ecological vehicle, the focus is on the latter. According to a study from the Federal Ministry for Digital and Transport called “Mobility in Germany” sur-veyed in 2017 [11], approx. 80% of passenger car trips covered less than 20 km, with only approx. 30% of the total mileage of a vehicle reached on short distances of less than 20 km in total. Therefore, the develop-ment of the drivetrain was focused on this use case (e.g., daily commute to work and twice a year a long trip on vacation).

A BEV designed for this user profile needs a large and heavy battery, barely using its full capacity. In contrast, the DE4LoRa concept was de-veloped to cover ranges of up to 100 km electric combined with the high efficiency benefits of a TDT22. To reduce complexity, two iden-tical electric machines have been designed, each realizing a continu-ous power of at least 40 kW to enable highly efficient driving with one EM during moderate cycles like the WLTC. Furthermore, they can jointly provide 120 kW peak power for short sporty driving. To enable shifting without interrupting traction even at high accelerations, both electric motors are able to provide 120 kW each for the very short duration of a shifting process. The development of these permanent magnet syn-chronous machine is further described in [12].

Assuming constant transmission efficiencies, as well as a constant bat-tery voltage and temperatures, a simple heuristic operating strategy for electric modes can be created. The resulting shifting map for this TDT22 is shown in Figure 1. The advantages of four different electric gears com-pared to a non-shiftable transmission are described in more detail in [6].

In an overall assessment of the electric consumption, the relatively low transmission losses cause a significant proportion of the total loss-es due to the high efficiency of power electronics, electric machines, and batteries. Therefore, electrically synchronized dog clutches were chosen to avoid friction losses which would occur in mechanical syn-chronization units. Furthermore, the losses of a transmission increase with higher viscosity of the transmission oil e.g., at low temperatures. To keep the efficiency as high as possible after a frequently expected cold start in winter, it can be beneficial to use the waste heat from the electrical components for conditioning the transmission oil. To further increase electrical efficiency, DE4LoRa also uses a rather high voltage level up to 820 V. Since the efficiency drops with the voltage over the state of charge of a battery, the latter should be kept as high as possible. In this concept, the electrical consumption in the WLTC increases by ap-prox. 5% if started at an SOC of 25% compared to 90%.

For the use case described above, highly efficient short-range electric driving alone is insufficient. To improve the concept for occasional long-distance, a monovalent methane gas engine is added. This engine can be connected to both sub-transmissions with different gear ratios, as shown in Figure 2, enabling multiple parallel and serial hybrid modes. This integration combined with the high dynamics and performance of the electric drive allowes the gas motor to be operated in a phlegma-tized manner, thus minimizing emissions and maximizing its efficiency.

In addition, methane provides a high energy density per carbon atom, can be produced synthetically more efficiently than liquid synthetic fuels, and, unlike hydrogen, is easy to store and benefits from an existing infrastruc-ture. Optimizing the gear ratios of this transmission involves a compro-mise between highly efficient electric and SOC-neutral hybrid modes, with SOC-neutral consumption being more sensitive to changes. It has been shown that an electric overdrive provides efficiency benefits, re-sulting in a top speed of 180 km/h in SOC-neutral operation in the third, not fourth gear.

2. Oil-Conditioning

During optimization constant transmission efficiencies were assumed between 96.9 and 97.8% for each mode-dependent combination of two spur gears. In real applications, these effi-ciencies depend not only on the acting speeds and torques but also on the viscosity of the gear oil and thus its temperature. With lower temperatures, the transmission losses increase disproportionately. The inverter and electric machine generate usually unused waste heat. If the lubrication concept of the transmis-sion already uses an oil pump, the heat can be used for conditioning the oil by adding a heat exchanger.

The potential depends on several parameters like the current efficien-cies, the water flow rate, and the oil used. To investigate the possibili-ties for this project, an analytical transmission loss model was created, which includes the viscosity of the gear oil in its calculations of churning losses, meshing losses, sealing losses, and bearing losses. Not only the load-carrying elements but also all co-rotating parts for every mode are considered. This model is supplemented by a lumped-element thermal model of all transmission components. All loss effected transmission parts as well as a water-oil heat exchanger and 30% of the losses of the electric machine at the input shafts are implemented as heat sources. Thus, both the self-heating of the gearbox and the heat transfer from an external water circuit is represented.

Two different transmission oils and two different scenarios were consid-ered, using only modes with one EM for simplification. First, a common rather more viscous transmission oil was modeled corresponding to a SAE 80W90. Figures 3 and 4 show the simulation results for a cold start in the Artemis Urban cycle with 0°C ambient temperature.

The efficiency changes of the transmission are shown in Figure 4; in blue without using the heat exchanger, in red with a water flow rate of 1 l/min. In addition, the efficiency with an oil temperature of 60°C at the beginning is shown as a benchmark in gray. Figure 5 shows the most relevant results of the simulations. The heat exchanger in this configuration enables an efficiency advantage of 1.3% which is no-ticeable, but significantly lower than the efficiency with already warm oil. If the gear layout and the acting surface pressures allow the use of an oil with (very) low viscosity, much higher total savings are pos-sible. On the other hand, the benefits of conditioning are hardly notice-able with this lubricant. Finally, the potential in a WLTC at 20°C ambi-ent temperature is evaluated, whereby the heat exchanger leads to an 0.6% lower energy consumption. Prospectively, the usage of additional waste heat by other consumers, such as an internal combustion engine, could achieve greater improvements. Furthermore, the effect could be improved by further optimizing the flow rates and quantity of water and oil.

Conclusion

The concept idea for a hybrid TDT22, the development process as well as the results achieved in the DE4LoRa project so far were stated. It is tailored to fulfill the requirements of an average Ger-man driver with minimized ecological footprint. It covers short distances in highly efficient elec-tric driving due to the advantages of four speeds, uses a comparatively small and thus light battery, a high voltage level, and supplementary oil conditioning. To maximize efficiency, it is rec-ommended to keep the SOC as high as possible. In addition, the effect of transmission oil con-ditioning was examined in more detail, and in summary, the loss reduction potential depends primarily on the oil used. If a conventional trans-mission oil is used, there can be considerable efficiency benefits for short trips and cold am-bient temperatures – 1.3% in this example. How-ever, if the design or maintenance strategy al-lows using a low-viscosity oil, the effect if an oil conditioning decreases significantly and com-bined with longer driving distances and higher ambient temperatures, becomes unnoticeable small.

Gratification We want to thank Max Clauer, Zhihong Liu, and Arved Eßer for theirhelpful feedback and advice.References[1] Biermann, T, “The Innovative Schaeffler Modular E-Axle“, April 2018, Schaeffler Symposium[2] Schmidt, C., Dhejne H., Vallant, W.,

„AVL Two-speed e-Axle – High Efficient and Shiftable Under Load”, November 2021, CTI Symposium, Berlin[3] Xu X., Liang J., Hao Q., Dong, P, et al., “A Novel Electric Dual Motor Transmission for Heavy Commercial Vehicles”, Januar 2021, Automotive Innovation, Springer[4] Hirano, K., Hara, T., “Development of dual motor multi-mode e-axle”, November 2021, CTI Symposium, Berlin[5] Brückner, U., Strop, M., Zimmer, D., „Mehrmotorenantriebssys-teme – intelligente Betriebsstrategie“, May 2017, Antriebstechnik[6] Eßer, A., Mölleney, J., Rinderknecht, S., „Potentials to reduce the Energy Consumption of Electric Vehicles in Urban Traffic”, Juli 2022, VDI Dritev, Baden-Baden[7] Eßer, A., “Realfahrtbasierte Bewertung des ökologischen Potentials von Fahrzugantriebskonzepten“, 2021, Shaker[8] Langhammer, F., Kappes, A., Viehmann, A., Rinderknecht, S., „Novel “Two-Drive-Transmission for Long-Range” Powertrain: Ecology and Efficiency meet Driving Comfort”, October 2021, VDI Dritev, Bonn[9] Kraftfahrt-Bundesamt, „Fahrzeugzulassungen (FZ) Neuzulassungen von Personenkraftwagen und Krafträdern nach Motorisierung Jahr 2020“ – FZ 22; https://www.kba.de/SharedDocs/Downloads/DE/Statistik/Fahrzeuge/FZ22/fz22_2020.pdf?__blob=publicationFile&v=5 last checked: 11-10-2022[10] Kraftfahrt-Bundesamt, „Neuzulassungen von Personenkraftwagen nach Segmenten und Modellreihen“ – FZ 11; https://www.kba.de/DE/Statistik/Fahrzeuge/Neuzulassungen/Segmente/n_segmente_node.html?yearFilter=2020 last checked: 11-10-2022[11] infas, DLR, IVT und infas 360, “Mobilität in Deutschland – MiD: Ergebnisbericht,” Im Auftrag des BMVi, 2017;http://www.mobilitaet-in-deutschland.de/pdf/MiD2017_Ergebnis-bericht.pdf last checked: 11-10-2022[12] Clauer, M., Binder, A., “Automated Fast Semi-Analytical Calculation Approach for the Holistic Design of a PMSM in a Novel Two-Drive Transmission”, September 2022, ICEM, Valencia

HOERBIGER: Innovative Solutions for Electric Drivetrains

Posted on 16th March 2023

Your reliable system and component supplier for future mobility

From development to production of innovative components and complete systems for conventional and alternative powertrains – HOERBIGER offers you everything from a single source. The portfolio for electrified drive trains includes transmission synchronizers and innovative shift elements for coupling and decoupling as well as components and clutch assemblies.

The emDOC, one of the new products from HOERBIGER, is an efficient electromagnetic comfort dog clutch for connect/disconnect or multi-speed in HEV and BEV powertrains. It offers an intelligent sensor technology and control for maximum comfort and NVH requirements. The smart 2 in 1 solution of a dog clutch coupling and an intelligent actuator reduces installation space and costs by eliminating external mechanics.

With eSYN you have best NVH behavior and efficiency thanks to a newly developed pre-synchronizer unit that uses annular springs to fix the synchronizer rings axially and radially, thus preventing oscillation and the associated rattling noise. Increased power density due to reduced switching distances and times and up to 10% less installation space. Friction lining is possible in caron, sinter or steel.

The Dog clutch offers you more performance for automated shifting and decoupling operations. Thanks to a spline geometry the system improves shift dynamics and noise comfort (NVH).

Furthermore, HOERBIGER is your reliable system partner for clutch assemblies with comprehensive know-how in tribology and friction lining technology for best performance. Steel-, friction and end plates come from a single source. Thanks to the different friction linings developed and produced in-house and the extensive expertise in special surface treatment, HOERBIGER offers solutions optimized for your application.

https://www.hoerbiger.com/de/produkte-and-services/komponenten-fuer-elektrischen-antriebsstrang.html

Ruiping Wang, Geely Auto Senior VP, Plenary Speech at CTI SYMPOSIUM Germany 2022

Posted on 16th March 2023

Ruiping Wang, Geely Auto Senior Vice President, joined CTI SYMPOSIUM GERMANY 2022 as plenary speaker via video from China. See her contribution “Geely’s strategy and practice in powertrain electrification” as video and hear about BEV growth rates, the regulatory context, and Geely´s drive solutions and outlook on HEV, PHEV and BEV in the Chinese market.

ElringKlinger: Metalobond – Supporting Direct Cooling Systems

Posted on 15th March 2023

ElringKlinger Metalobond is a new full face gluing system for laminated stacks with a high sealing capability to support direct cooling systems in rotors and stators and increase performance.

With increasing rotation speed and less installation space in advance electric engine concepts, heat becomes more and more an issue.
The best way to cope with this issue is to avoid heat generation by reducing electromagnetic losses, e.g. in the iron core. A second approach is to use an efficient direct cooling system to get heat out of the system and therefore increase continues performance of the electric motor significantly.

The first approach drives the sheet metal thickness of the laminated stacks below 0.3 mm. The target is to reduce the eddy current losses in the system and by doing so, reducing the generated heat.
To increase the process efficiency of stamping thin sheet metal layers for laminated stacks, ElringKlinger has developed its multilayerstamping process. Three layers of gluecoated sheet metal are combined to a compound, punched, stacked and full face glued to a form package.

The packages produced in this process with the MetaloBond gluing system achive good values in strength and setting behavoir.

In the second approach, a direct cooling system can be used to remove heat. If the direct cooling system shall be designed within the iron core, a reliable and lifetime durable sealing between the single layers of the iron core must be ensured. With Elringklingers MetaloBond gluing system, this sealing capability is guaranteed. Due to its clear focus on selaing performance it allows a bigger degree of design freedom as other gluing systems on the market. With ElringKlinger MetaloBond, cooling channels can be placed with a distance of only 0.7 mm to the permeter and still seal pressures up to 200bar, even under thermal cycling and thermal shock conditions.

This allows to place cooling channels where they are needed. Either close to the hot spots or close to the perimeter to reduce interruption of magnetic flux. The result is an efficient cooled system with a dramatic increase in continues performance. As a full service supplier, ElringKlinger is able to support you with the full range of services from heat flux calculation, lasered and punched prototypes to fluid flow testing with thermal cycling or shock. If you have further questions or want to discuss your application please visit us at our booth no. A7 at CTI in Novi.

ElringKlinger Contacts

Alexander Heinzelmann
alexander.heinzelmann@elringklinger.com
Fon: +49 (7123) 724 88401

Daniel Roming
daniel.roming@elringklinger.com
Fon: +49 (7123) 724 88114

JJE Advances Electromagnetic ClutchTechnology to a New Level

Posted on 8th March 2023

JJE DirectFluxTM Mono-stable and Bi-stable Electromagnetic Clutches for Disconnect and Differential Locker Applications

Jing-Jin Electric (JJE) has been developing electromagnetic clutches for various electric drive applications over a decade. Instead of using “reluctance” magnetic force, JJE electromagnetic clutches utilize direct magnetic force – flux in the same direction as the magnetic force – which is named “DirectFluxTM”. A mono-stable clutch is engaged by actuation current, and disengaged by spring force when the current is off. A bi-stable clutch will only change its state when there’s an affirmative pulse of command current; otherwise, it will hold its state. Earlier this year, JJE launched industry’s first bi-stable electromagnetic clutch for automotive applications.

The technology roadmap for developing an electromagnetic dog clutch (EMDC) plays a key role in the product’s developing stage. Back to 2009, JJE started to develop the electromagnetic clutch in “DirectFluxTM” concept. The first generation (Gen 1) EMDC product is a circle configuration, mainly applied on hybrid systems as a hybrid mode clutch, which was very successful in China’s commercial market.

In 2017, the 2nd generation (Gen 2) EMDC product was launched, and expanded its application to transmission shifting after optimization over mechanical design. The “crescent” configuration was developed and added in the JJE’s EMDC family.

In early 2019, JJE began the development of 3rd generation (Gen 3) EMDC. The third generation (Gen 3) EMDC features further innovations. It has both mono-stable and bi-stable options. It overcame some limitations of the existing design. Coils evolved to smaller solenoids, and magnetic circuit are further optimized to reduce flux leakage. The Gen 3 EMDC is more capable, faster, functionally safer, and more energy efficient.

DirectFluxTM Electromagnetic Clutch

JJE’s DirectFluxTM mono-stable electromagnetic clutch has several advantages because of its unique magnetic circuit design and mechanical structure. Compared to the more conventional reluctance flux magnetic circuit design, the DirectFluxTM design greatly reduces flux leakage, therefore it utilizes the magnetic flux to generate force more effectively. The reluctance flux design cannot avoid magnetization of parts near flux circuit, or “flux leakage”, which cause less effective utilization of the magnetic flux.

Because of the more effective flux utilization, the DirectFluxTM clutch has much higher electromagnetic force than reluctance flux clutch, therefore it acts 2-3 times faster, as shown in the charts.

Bi-stable Electromagnetic Clutch

The bi-stable electromagnetic clutch – still based on JJE’s DirectFluxTM electromagnetics – is an innovation beyond JJE’s mono-stable electromagnetic clutch. It uses permanent magnets to hold the clutch in its en-gaged position, while still allowing the electromagnetic coil to “push” the clutch plate away while disengaging. As the clutch can self-hold at both engaged and disengaged positions, there is no need for holding current as the mono-stable clutch does. The operation current curve exactly illustrates the difference between the mono-stable and bi-stable. For bi-stable clutch, the operation only needs to provide a current pulse to switch the clutch’s state (see Fig.).

The bi-stable clutch is inherently fail-safe as it won’t change state in the event of loss of holding current. This feature brings the bi-stable clutch a higher safety level than mono-stable clutch for disconnect, differential lock-er, and transmission shift applications. As far as energy consumption, the bi-stable clutch’s feature of “zero hold-ing current” achieves the zero consumption.

Figure 4: Operation Comparison Between Mono-stable and Bi-stable Clutch

Disconnect

JJE’s mono-stable clutch has already been successfully applied on electric drive disconnect. In an offset, layshaft reduction gearbox, the disconnect clutch is on the output and is integrated with differential. Compared with disconnect on the input shaft or on the layshaft, the output shaft discon-nect cuts out most mechanical losses. JJE is also introducing bi-stable electromagnetic clutch to disconnect application. There is no holding current or power consumption when the clutch is engaged. It is mechanically fail-safe in the event of critical electrical or control fault. When the vehicle is in AWD state, all-wheel power will be maintained for consistency; when the vehicle is in the 2WD state – or secondary axle disconnected – the secondary axle won’t be suddenly engaged, which would cause big jerk, or even wheel lockup at low traction. DirectFluxTM bi-stable clutch has a great performance on the action time. The differential locker and disconnect driven by DirectFluxTM bi-stable EMDC have been tested on JJE’s Dynamometer. The average action time is less than 70ms, and only current pulses are needed for engagement and disengagement. With JJE’s disconnect clutch, the drag loss reduction is remarkable. In a typical 200kW electric drive unit with permanent magnet motor, at 150km/h vehicle speed, the drag loss reduction is greater than 90%, or from nearly 8kW to less than 500W.

Differential Locker

JJE debuted industry’s first electromagnetic bi-stable differential locker at 2022 CTI US. Bi-stable’s greatest advantage is still fail-safe – in the event of critical electrical or control fault, this bi-stable feature can prevent sudden locker release and dangerous loss of tractionThis bi-stable DirectFluxTM differential locker will be used in high capability pick-up trucks, SUVs and off-road vehicles in independent electric drive module (EDM) or eBeam axles. It will be launched into production in 2023 in JJE’s newest 6000Nm, 300kW Silicon Carbide EDM for a high-end 4×4 SUV by a leading OEM, which features over 100% gradeability.“JJE has been developing and producing electromagnetic clutch for over a decade”, says Ping Yu, JJE’s Chairman and Chief Engineer, “we have pioneered electromagnetic dog clutch’s application in many areas and generated multiple global patents. The introduction of the bi-stable clutch technology is more exciting – it brings security like a mechani-cal sleeve clutch while maintaining or even improving all other great aspects of an electromagnetic clutch. It will further reinforce our leadership in electric drive technology”.