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HOERBIGER innovative solutions for electric drive trains

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.

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Ajedium™ PEEK Slot Liner Enables 800V eMotor Downsizing & Weight Reduction

DeeDee Smith, Luigi Marino, Brian Baleno

Solvay Materials

A significant challenge for eMotor 800 Volt designers is to design smaller and more compact eMotors. Successfully doing so allows for the potential to reduce the mass of both the eMotor and battery pack. A new slot liner material, Ajedium™ PEEK films, gives engineers the design freedom to down-size their eMotor as well as achieve weight savings.

Most eMotors utilize conventional slot liner materials such as paper and paper laminates. A major challenge for both paper and paper laminates is that as eMotors move from 400V to 800V systems, the increase in voltage leads to an increased thickness of the slot liner.

Engineers typically need to balance the copper fill factor, the heat rejection capability, and achieve the right level electrical insulation that guarantees the right life expectancy and reliability. Therefore selecting the right slot liner insulation properties and thickness plays a pivotal role in the overall design of the eMotor.In order to quantify the value of using a PEEK slot liner, a virtual engineering software was used (ALTAIR FluxMotor 2021). Figure 1 below shows the eMotor design conditions used in the simulation.

Figure 1: Design inputs for virtual engineering simulation

Three different thicknesses of PEEK slot liners were used in the study: 100 micron, 150 micron, and 250 micron and compared to 250 micron NKN (paper laminate).

Figure 2: Virtual engineering results comparing NKN to PEEK

Virtual engineering determined the number of conductors that can be allocated in the slot by maintaining the same number of turns and winding layout. Figure 2 above shows the improved thermal behavior enabled by PEEK (vs NKN) where Ajedium™ allows for increased slot fill factor (at 100 and 150 microns), reducing not only winding but also other sub-components temperature.

The PEEK design advantage is enabled by using thinner slot liners which improve fill factor and heat transfer, thanks to the lower needed thickness and the higher thermal conductivity value of PEEK (0.17 W/mK).

The efficiency and thermal benefit of PEEK can be factored into more compact eMotor designs. The considered temperature reference was the peak value obtained during a targeted drive cycle simulation and not just the one obtained on a single operating point, which can be misleading.

A 250 micron NKN slot liner was used as the baseline and simulated over the targeted drive cycle. The same was done with 150 micron PEEK slot liners. The same motor length (84 mm) was initially taken into account, which showed a temperature drop. The next step was to factor in the reduction of the maximal winding temperature in an effort to make the eMotor more compact. A reduction in the motor length results in an increased motor temperature because there is less heat dissipation. This occurs due to the lower heat exchange surface, and a higher eMotor load (phase current). The overall target was to reduce the length until the original maximal winding temperature was observed again. These steps are summarized at Fig 3.

However, the fully optimized design with a thinner and more thermally conductive slot liner would probably have a slightly different L/D (length over diameter) ratio. Hence, this optimization method would lead to conservative results on the benefits that an improved slot liner would provide.

Figure 3: Stator and Rotor mass reduction with thinner PEEK (150 micron) slot liners

Figure 4 summarizes the overall aspect of optimizing eMotor slot liner thickness. Not only do thinner PEEK slot liners provide both motor compactness and light-weighting, up to 6.3% reduction in this case study, there is also a 2.1% improvement in motor efficiency. This efficiency figure is calculated as the average obtained for the simulated drive cycle. The drive cycle was purposely designed to span all the typical operating points, with reasonable cumulative time spent on each of them. Therefore, this result has a direct impact on the expected range of the BEV as well as the potential battery downsizing for that same range.

Figure 4: Summary of Results with varying slot liner thickness

Figure 4 summarizes the overall aspect of optimizing eMotor slot liner thickness. Not only do thinner PEEK slot liners provide both motor compactness and light-weighting, up to 6.3% reduction in this case study, there is also a 2.1% improvement in motor efficiency. This efficiency figure is calculated as the average obtained for the simulated drive cycle. The drive cycle was purposely designed to span all the typical operating points, with reasonable cumulative time spent on each of them. Therefore, this result has a direct impact on the expected range of the BEV as well as the potential battery downsizing for that same range. Finally, PEEK provides many design advantages over paper and paper laminates. Some benefits of using PEEK slot liners include improved eMotor efficiency, potential reduction in the length of the motor, and also weight reduction of both the stator and rotor.

Full Car Computer could be a reality by 2027

As electrification progresses, in-vehicle hardware and software architectures will evolve from distributed electronics to a “full car computer and zonal” model. We spoke with Patrick Leteinturier, Fellow Automotive Systems, Infineon Technologies, about these new architectures, new semiconductor materials, and the central role of “motion control”.

Increasingly, vehicles are becoming software-defined. What does that mean for the way OEMs and Tier 1/2 suppliers cooperate?

Software-defined vehicle (SDV) is a disruptive step in the digital transformation of automobiles and even wider the complete mobility sector. In SDV, the software takes a major role and a part of it migrates from the endpoint electronic control units (ECU) to the aggregation and transformation layer, or even to the central car computer. That will lead to a change of ownership. The OEMs do write the software on a higher level, which should speed up development, but the endpoint software that controls the endpoint devices will still be delivered by a supplier. The way tasks are shared will change. Either way, both parties will need to collaborate more than in traditional architectures. We’ll have to see who takes ownership of the development, integration, testing, and validation.

You foresee a change from distributed architectures and zone computers to Full Car Computer. When will that become a reality?

According to data from S&P Global Market Intelligence, Full Car Computer will have a market penetration of around 30% by 2034. The S-curve is starting now, and full adoption will take maybe 10 or 15 years to achieve. Practically all OEMs are working hard on this. For example, Volkswagen with Cariad. General Motors, Stellantis, and Ford are on it, and many others too. They’re not all at the same stage, and they are not running at the same speed and solution. General Motors, for example, are fully committed and are putting their full power behind it. Some OEMs may have a full car computer as early as 2027.

How will the physical bus systems change with this migration?

The common understanding is that Ethernet-based communication will become much faster. There are some limitations with CAN. The Ethernet reaches from the endpoint to the aggregation and transformation layer; it will usually be 10BASE-T1S. Then from the zone controller to the central car computer, it will be fast Ethernet. Gigabit Ethernet is already in use, but now we are even talking about 50 Gbps. With CAN or LIN, we have some limiting factors. LIN is super low-cost and very simple, but end-to-end encrypted communication is almost impossible. It is not feasible for reprogrammable functions over the air, for example. If you want a more advanced endpoint, CAN could do that, but it would need some additional CANsec to enable security end-to-end. To simplify, it depends on the SOTA “software over the air” strategy from OEM to deploy the right physical bus.

When computing is centralized, what new challenges and opportunities could arise in terms of functional safety?

Today, we have a car with distributed electronics. But in the future, many functions will be synchronized on the central car computer layer. Take vehicle motion, for example. In terms of synchronization, this has the highest complexity. You have four wheels, each with just a few square centimeters of grip on the road. And via these small friction points, you control propulsion, regenerative braking, mechanical braking, steering, suspension, etc. When we apply e-motor power to each wheel, the propulsion can steer, brake, and propel. Of course, there will be more complexity in the way sensor and actuator information need to be handled and merged. We need a seamless OS platform, dependable electronics, new security, as well as fail-operational and redundancy concepts. But on the other hand, a centralized vehicle motion control setup, in conjunction with by-wire technology, also offers new opportunities. If one wheel fails, for example, the other three can compensate via all the integrated actuators, including the e-motors.

Let’s talk about semiconductors: What materials will tomorrow’s semiconductor materials use, and what are the benefits?

Firstly, SiC is a technology that was developed a long time ago for higher efficiency in solar and wind energy. We have been in volume production for a long time, and we have a lot of experience in manufacturing. We know all the figures for reliability and robustness. SiC is superior because it lets you reduce the internal resistance and the conduction losses of power electronics. And it’s also quite good in terms of switching, so you have lower switching losses. This is extremely beneficial at part load. On the other hand, the material and its processing are rather expensive. However, we can blend SiC and IGBT (Insulated-Gate Bipolar Transistor). IGBT will work very efficiently at full load, and the silicon carbide will be used for part load. You could combine these properties across two axles – for example, IGBT at the rear and SiC at the front. But you can also combine them within the same power module, make a multiple die, and put them in parallel. This blend is much more efficient in both propulsion and regeneration and enables around 12% more range. On the other hand, the next technology GaN is already on the horizon and we are preparing that as well to be used in automotive applications and further increase efficiency to pay into decarbonization.

Semiconductors help to improve efficiency and range. But they are also part of a control system that requires a lot of energy. How can that be optimized?

That’s a great question! People need to understand that we‘re not just talking about propulsion and regenerative braking. There are a lot of energy consumers, you still have to power up and supply a large number of electronic components. So you need to be very careful about your power mode, and your strategy for deciding whether an ECU needs to be on or off. Imagine you‘re at home, for example, and you hook your EV up to the charger. It’s going to be plugged in for a long, long time… so gradually, even low energy consumption will add up to high consumption. So the aim is to only power the electronics you need. With a software-defined vehicle that is widely networked, you have to power the central computer, which consumes quite a lot of energy. On the other hand, it is also the ‘brain’ that handles power supplies vehicle-wide. Whether it’s single zones, endpoints, or whatever, power consumption can be reduced or even switched off. So if my battery capacity runs low while I’m driving, for instance, I could switch off the cabin air conditioning or heating. The good thing about the car computer is that it has all the data to make the most efficient decisions. So yes, a central computer does consume energy. But more importantly, it’s an enabler for intelligent energy and load management.

Interview: Gernot Goppelt

Electric Drive Module (EDM) with eLocker

JJE’s New 300kW SiC EDM with the World’s First Bi-stable Electromagnetic Locker

The development of the electric drive module continues to trend towards higher performance, power and efficiency with improved NVH characteristics all while integrating functional features such as differential lockers and disconnects. Jing-Jin Electric (JJE) is bringing this functionality matching the various requirements in the market with its latest Silicon Carbide (SiC) EDM. The system features a hairpin motor with 300kW peak power at 400V and a torque output level up to 6000Nm which is driven by JJE’s newest SiC inverter. As an additional feature, the system includes the world’s first DirectFluxTM bi-stable electromagnetic differential locker (eLocker).

Figure 1. JJE’s Newest 300kW, 6000Nm SiC EDM with DirectFluxTM Bi-stable eLocker

High Performance 3-in-1 EDM System
The system efficiency is remarkably improved by applying multiple advanced technologies. An active lubrication system lowers the churning loss while the water and oil cooling system increases the
motor’s overall performance. A highly integrated design eliminates several bearings and seals, helping the EDM package within a smaller environment and further reduces mechanical losses. Applying
these advanced technologies allows the EDM’s system efficiency to achieve 95.26%

For the cooling system, the EDM continues to feature JJE’s water and oil combined cooling technology which provides 160kW continuous output power sustained into the motor’s high-speed range.
Water flows through the cooling channel within the water jacket which provides cooling to the stator core and windings. The oil cooling system includes oil spray using a distributing ring located at the
winding end as well as oil splash through the hollow shaft. This unique combined technology increases performance by 11% when compared to water cooling alone and 8% compared to oil cooling.

The EDM utilizes an active lubrication system which allows the gearbox mechanical churning losses to be reduced by 30%. This improvement is achieved by lowering the ATF’s level within the EDM allowing most of the gears and bearings not to soak in the ATF during operation.

JJE utilized a system level approach when analyzing NVH characteristics. By considering mode shape, gear order, bearing order, JJE was able to avoid overlapping noise orders for the different  rotational parts. This allows the EDM to maintain low noise levels at all operating speeds. The motor incorporates JJE’s patented Interior Acoustic Shied (IASTM) technology, which effectively dampens high frequency noise utilizing dampening materials injected into motor’s housing. The addition of this technology allows the motor’s noise to be reduced by 5 – 10dB in mid-speed and 10 – 15dB at  high speed.

The EDM uses JJE’s high-end SiC inverter which features 47kW/L power density with up to 460kW of peak power. Efficiency of this inverter reaches 99.5%. Motor control, differential locker control and system control are developed using ASPICE processes, and includes ASIL-D level functional safety and Cyber Security.

World’s First Bi-stable Differential Locker
As a high-end EDM for off-road vehicles, pick-up trucks and SUVs, the differential locker plays a key role in performance. JJE introduces the most advanced electromagnetic technology in this differential locker application called the DirectFluxTM Bi-stable Electromagnetic Dog Clutch (Bi-stable EMDC). This technology brings an increased safety level when compared to the mono-stable electromagnetic clutch. With over a decade of development on the electromagnetic clutch, this generation is able to overcome limitations of existing designs in the market. Coils have evolved into smaller solenoids and magnetic circuits are further optimized to reduce flux leakage. Most importantly this clutch is Bi-stable – meaning it uses permanent magnets to hold the clutch in its engaged position, while still allowing the electromagnetic coil to “push” the clutch plate away while disengaging. As the clutch can selfhold
at both engaged and disengaged positions, there is no need for the holding current that a mono-stable clutch requires. The operating current curve illustrates the difference between the mono-stable and bi-stable designs. For the bi-stable clutch design only a current pulse is required to switch the clutch’s state (see Fig. 7).

The differential locker featured with this bi-stable EMDC technology is mechanically fail-safe. In the event of a critical electrical or control fault the locker driven by bi-stable EMDC will eliminate a sudden loss of wheel torque which is critical during climbing maneuvers or while operating on low traction surfaces.

The Bi-stable technology nearly eliminates energy consumption as there is no current needed during engagement and operates 3-10 times faster than competitor’s products available in the market today. This differential locker has been tested on high-end off-road vehicles in winter and summer tests and produces remarkable performance and durability during these tests. JJE’s newest 6000Nm, 300kW Silicon Carbide EDM with bi-stable differential locker will be launched into production in 2023 for a high-end 4×4 SUV produced by a leading OEM and will feature over 100% gradeability.

“We are excited to introduce this enhanced 3-in-1 electric drive system with Silicon Carbide inverter, higher efficiency, more powerful cooling and fast, secure differential locker”,

says Ping Yu, JJE’s Founder, Chairman and Chief Engineer.

“This EDM will help JJE maintain our leadership in high performance eDrive systems, and uniquely serve customer’s needs in continuous high speed or towing, demanding NVH performance, as well as differential locking.”

Iluka’s Australian Rare Earths Refinery; Delivering a Sustainable Alternative

As the world moves towards an electrified future, the demand for permanent magnets is amplifying the already intense pressures on global supply chains.

But in the sandplains of Western Australia, a small regional community called Eneabba is at the centre of what is set to become a globally significant and strategic hub for the downstream processing of rare earth resources, a critical component of permanent magnets.

Construction is underway for Australia’s first fully-integrated rare earths refinery, the result of long term strategic planning by Iluka Resources, a leading producer of zircon and high grade titanium dioxide feedstocks (rutile and synthetic rutile).

In approximately two years Iluka will be producing both light and heavy separated rare earth oxides, including the ‘magnet’ rare earths − neodymium (Nd), praseodymium (Pr), dysprosium (Dy) and terbium (Tb). Found in electric vehicles, wind turbines, electronics and a range of defence and communication applications, the demand for magnet rare earth oxides has resulted in a global supply deficit for these critical minerals.

So why would a company that produces zircon and titanium dioxide feedstocks build a rare earths refinery?

Rare earths co-exist with Iluka’s mineral sands products and, since the 1970s, Iluka has stockpiled its rare earth baring minerals in a former mining void in Eneabba. Separated during the processing
and extraction of zircon and titanium dioxide feedstocks, over 1 million tonnes of heavy mineral concentrate has been stockpiled by Iluka. Rich in the highly valuable light and heavy rare earths,
Iluka’s stockpile is now the world’s highest grade rare earths operation.

In April of 2022, Iluka announced that the company had entered into a risk sharing arrangement with the Australian Government to develop a globally significant rare earths refinery in Australia. This arrangement included a A$1.25 Billion non-recourse loan from the government’s Critical Minerals Facility, established to provide support for critical minerals projects.

The refinery will be capable of processing up to 23,000¹ tonnes per annum of separated rare earth oxides, with processing, separation and finishing all completed at the one location in Eneabba. The state-of-the-art design will also enable flexibility in processing of feedstock, including product produced by Iluka and by third parties.

said Iluka’s Managing Director, Tom O’Leary.

By 2026, excluding supply from China, Iluka’s refinery is forecast to produce over 60 % of refined heavy rare earth oxides, dysprosium and terbium from the company’s stockpile of material alone. As Iluka introduces additional feedstocks through the refinery, the volume of refined magnet oxides produced is forecast to increase.

The company has already begun work on securing additional feed, including developing internal Iluka projects that contain rare earths and through investment in third parties. Iluka recently announced a strategic partnership with Northern Minerals Ltd, who are developing a rare earths project in Western Australia that is characterised by a high assemblage of heavy rare earths (Dy and Tb).

Aside from the security offered through a diversified supply chain, Iluka is working to produce a low-impact product, that is responsibly mined and processed under Australian regulations.

Iluka‘s production of rare earth oxides as a co-product provides significant advantages in sustainability when compared to current production.

The closed circuit design of the refinery will enable the recovery and reuse of both water and reagents used in the processing circuit, dramatically reducing the volume of waste produced while also lowering the refinery’s processing costs.

To demonstrate the overall lower impact of its rare earth products compared to many other producers, and to identify and plan for scenarios to reduce their impact, Iluka is completing a Life Cycle Assessment (LCA) for its rare earth products. The LCA will evaluate the effects that Iluka’s rare earth products have on the environment during the mining and processing, including the global warming potential, power and water usage, and human toxicity potential.

Iluka’s rare earths development is progressing from strength to strength. The company has commissioned a Screening Plant and a Beneficiation Plant to further upgrade the material before entering the refinery circuit and, despite the global supply chain challenges, work on the refinery remains on schedule. Beyond the production of rare earth oxides, Iluka is considering progressing even further along the rare earth supply chain, including rare earth metallisation, an essential step in the development of permanent magnets.

For further information on Iluka visit www.iluka.com

¹ The final plant capacity determined on the feed blends used

E-Motor Efficiency and Lower Costs are Stacked in Your Favor

glulock® – A unique in-tool bonding technology for e-laminations in motor stacks

Motor-cores have been build by mechanically interlocking individual motor laminations for decades. With materials in laminations for e-motor cores becoming thinner and thinner and increased efficiencies of electrified propulsion systems this process of mechanically interlocking the „stacks“ has become more and more difficult and less efficient.

With glulock®, an in-tool bonding process for e-laminations, Feintool provides solutions fully integrated into the stamping process.

To address the shortcomings of mechanically interlocked e-sheets the industry developed alternative secondary bonding processes that eliminates any sheet gaps and improves stacking factors to above 96%.

Traditional Secondary Bonding Processes Result in Commercial Shortcomings

Traditional secondary bonding processes such as “Backlack” have several commercial disadvantages. First, the bonding agent is applied to the actual raw material which results to be locked into certain raw material suppliers. In addition, the already applied bonding agent is subject to a limited shelf life and in some of the grades, sensitive to heat exposure during shipping for example in a container or truck during the hot summer months.

However, the biggest shortcoming is that a secondary, costly energy and labor-intensive process is necessary to stack and bond the individual sheets together to a rotor and stator core exposing them to a secondary heating process after they have been stamped as single laminations.

The Solution – glulock®

The unique glulock in-tool bonding process for e-laminations provides solutions fully integrated into the stamping process. Feintool’s glulock is an e-sheet lamination bonding process that continuously applies dot adhesive integrated in the stamping tool during the stamping process. The  result is an instantly bonded e-motor core without any additional and expensive secondary operations or the need to use proprietary raw material with a bonding agent that results in limited shelf life and logistic challenges.

“ With the glulock technology, its consistent further development, and our proximity to customers and the market, I am firmly convinced that we have already found the right answers to the requirements of the future.”
MARKUS LOCK, Head of R&D and Engineering, Feintool System Parts

17 years of innovation and countless engineering hours and practical trials are the foundation of the glulock system. An advanced control system with various functions for consistently monitoring flow and valve functions are at the heart of the technology.

Temperature Resistant

In addition to the mechanical/magnetic advantages of glulock – glulock is chemical resistant and offers a temperature resistance up to 180 degrees Celsius / 356 degrees Fahrenheit. For example, glulock can be used in ATF oil within a temperature class H.

An Evolution to glulockMD® technology

The advantage of glulock is that the system is fully integrated in the high-speed stamping press as part of the e-lamination tooling. The 2-component glue is applied in real time and is currently tested with stroke rates exceeding 200 strokes per minute. With the possibility to apply multiple dots in a controlled size and a 360-degree pattern it is possible to place several glue dots on the stamped e-lamination in such a way that an almost full-surface bonding is ensured.

What are the advantages of glulockMD?

With the trend towards bonding laminations and therefore increase performance and reduce losses in the e-motor glulockMD offers following technical benefits:

• Improved flux density compared to a mechanical interlocked stack/motor core
• Higher stacking factor (>96%); reduced stack tolerance
• Processing of thinner material (up to 0.1mm)
• Improved shape accuracy
• High stability of stack
• Improved efficiency
• Increased torque
• High process speed

Improved flux density:
The glulockMD bonding process results in a significant reduction of sheet gap – therefore achieving a higher stacking factor compared to mechanical interlocking.

Sealing Properties

Further developments in electric motor show that, in addition to the growing mechanical and thermal requirements, their cooling also has potential for optimization.

Especially for e-motors with higher and higher rpm’s the trend is to have the cooling integrated into the rotors and stators. This requires impermeable stacking, sealing and surface bonding. With glulock it is possible to place several glue dots on the sheet in such a way that an almost full surface bonding is ensured. In addition to the sealing function, the bonding on the yoke and tooth segments ensures additional rigidity of the motor core stack.

Proven Technology

We are seeing a lot of success by major OEMs and tier suppliers with our glulock technology. Feintool is producing all the motor stacks for a major German OEM for their latest, most efficient electric motor with glulock technology.

ABOUT FEINTOOL
Feintool is a world-leading technology group specializing in fineblanked and formed components that provide high-precision, functional, and critical automotive parts.

We offer production of electro motor lamination, electro core stacks, and copper parts for BEV and hybrid vehicles. Where you make it makes a difference. Feintool helps to keep your production line running. You’ll get the highest quality parts, made with the most advanced vertically integrated processes. Because together we can.

Feintool US operates a technology center in Cincinnati, a sales office in Detroit, and specialized production plants in Cincinnati and Nashville.
Learn more at: www.feintool.us/power/.

Efficient Turnkey Machining of Complex e-Drive Components

Perfect E-Shaft with Integrated Production Solution

For the transmissions of electric vehicles to develop the desired high torque under all driving conditions, a very large gear ratio is needed, which requires high speeds. And to ensure sufficient momentum at all speeds and enable the driver to accelerate without shifting gears, the electric drive has to achieve up to 15,000 rpms, which is about three times that of a typica combustion engine. This puts a lot of strain on the rotor shaft. The manufacturers of rotor shafts are thus facing new challenges, such as the significantly lower shape and position tolerances and the need for greater machining precision.

Lower shape and position tolerances as well as fine surfaces also help to avoid vibrations from moving components and thus minimize the background noise of the drive system, i.e., optimize the NVH behavior. Since electric motors work virtually silently, the noise emissions are much more critical than with a petrol or diesel engine.

Integrated production solution for E-shafts
In order to meet these very stringent requirements, the DVS TECHNOLOGY GROUP (DVS), an association of experienced companies with core competencies in the field of machining technologies, has developed a forward-looking, integrated production solution for the turnkey machining of monoblock E-shafts from raw to finished parts. This means that these complex drive components can be manufactured up to 40% more economically.

Soft machining by skiving
First in the production chain is the Pittler V300, an innovative multi-technological production solution that combines fully automatic turning, milling, and drilling operations as well as gear cutting using the highly productive skiving process. This enables complete soft machining of the hollow shafts in just two setups on one machine. It reduces setup, transport, and idle times, which means that the total processing time is also shorter. In addition, processing on just one machine means lower investment costs and a shorter time-to-production.

Skiving is used for the production of gears in green-machining. This is a metal cutting process for the production of gears which is based on a patent filed by Wilhelm von Pittler in 1910. Thanks to the latest developments in manufacturing technology, skiving has emerged as an efficient and flexible alternative over recent years for the gearing of components.

One of the characteristics of skiving is the oblique arrangement of the tool axis to the workpiece axis (Figure 3). This is called an axis intersection angle. This positioning of the tool, a defined axial feed, and the coupled speed of the tool and workpiece result in a relative movement. This relative movement “peels” the
tooth gap out of the workpiece along the main cutting direction.

The contact kinematics of skiving require a tapered tool when the cutting point is on the direct line connecting the tool and workpiece axis. To avoid this, the DVS Group has further developed the POWER-SKIVING process: The cutting position is shifted in the Y direction out of the direct line connecting the tool and work-piece axis. This optimization enables the use of cylindrical tools with a substantial increase in tool life through frequent regrinding of the tools. Accordingly, the cost of tools is reduced significantly.

The quickly changing cutting forces of the skiving process cause vibration in the machine and the control system. That is why skiving requires extremely rigid machine structures, tool and workpiece carriers as well as highly optimized control circuits. This is precisely what the Power Skiving machine concepts from DVS were designed for.

Skiving technology comparison
Compared to other processes, skiving stands out due to a number of processing characteristics:

Skiving
Advantages:

• Short primary processing time
• High metal removal rate
• Moderate tool costs
• Can be combined with other machining methods
• Production of internal and external gears in one clamping

Disadvantages:

• New technology

Shaping:
Advantages

• Flexible
• Simple technology

Disadvantages:

• Long primary processing times due to idle stroke (about 3–8 times longer)
• Higher workpiece costs
• Can not be combined with other processes

Hobbing
Advantages:

• High metal removal rate
• Short primary processing time
• Low tool costs
• Proven technology

Disadvantages:

• Suitable only for external gears
• Requires larger run-out compared to skiving

Broaching
Advantages:

• High throughput with large quantities
• Very short primary processing times

Disadvantages:

• Suitable only for external gears
• Requires larger run-out compared to skiving

Using skiving for the production of gears with green machining has a number of advantages. Two of the unique selling points are the possibility of manufacturing internal and external gears in one clamping as well as the possibility of machining all-in-one or combine it with other machining.

Grinding and hard turning on the Buderus 235VH/M
The heat treatment of the shaft is followed by the first hard-fine machining step. Most rotor shafts have a similar design due to the required properties. A typical monobloc E-shaft consists of a running gear or spline, two bearing seats, two sealing surfaces, and a rotor seat. Depending on how the laminated core is fixed, the rotor seat is additionally provided with notches or spanner flats.

The bearing seats and sealing surfaces are machined by plunge grinding (Figure 10) and the rotor seat by peel grinding or plunge grinding (Figure 11). End faces and cut-ins are usually machined by hard turning during the same clamping, as a rotary turret can be integrated into the Buderus 235VH/M if required. Tolerances in the micrometer range should be achieved on the bearing seats, sealing surfaces, and rotor seats. Experience has shown that typical tolerance requirements range between 0.004–0.03mm for cylindricity, 0.002–0.025 mm for roundness, 0.005–0.08 mm for coaxiality, and 0.008–0.1mm for concentricity. For sealing surfaces and rotor seats, it is also necessary to obtain a peak-to-valley height of up to 1 μm. This accuracy is possible by grinding with the Buderus 235VH/M in a single clamping.

The 235 VH machine concept stands for the highest quality, low unit costs, and maximum adaptability. The innovative machine platform is specially designed for the machining of rotationally symmetrical shaft components with a diameter of up to 300 mm and a length of up to 1,000 mm.

The machines enable both combined and simultaneous machining processes. The flexible configuration options enable a wide variety of machining technologies from grinding, hard turning, and honing to the use of powered tools.

Buderus is also a specialist on the use of center drive technology. The latest development is the 235VM center drive machine with an advanced drive head. This head achieves a  orking speed of up to 2,500 rpm and thus also enables the hard turning of components. The main advantage of the center drive technology is the fact that inner and outer geometries can be machined in just one clamping, which results in greater precision as well as significantly higher efficiency.

Gear honing – advantages of honing for generating grinding
The last step in the DVS process chain before the hollow shaft is ready for installation is gear honing. In recent years, the DVS subsidiary Präwema has further developed a technology that enables lower friction losses when the gears roll off. This so-called “power honing” process is now standard in much of the international vehicle industry. The honed gear surfaces are critical for the reduction of noise levels and to lower energy consumption in electric vehicles.

High workpiece qualities are achieved through some unique processing properties of honing. For example, as the cutting speeds do not exceed 12 m/min there is no grinding burn, which is usually an almost invisible byproduct of grinding due to too high cutting speeds. A high induced surface tension can also increase the service life of the gearing and reduce the risk of pitting. Moreover, the entire toothing width is machined simultaneously using the plunge method, and the surface structure runs diagonally across the flank to improve quiet running.

In addition, short cycle times, low tool costs, and the possibility of processing closely adjacent gears that cannot be processed by a worm grinding wheel make honing extremely economical.

The extremely productive process enables ultra-precise machining in gearing qualities IT below 6 and super-fine surfaces with an Rz under 1. For optimal NVH behavior, specific micro-geometries (e.g., profile angle and profile shape deviations) can be used for the running gears. Test results are available upon request.

Tool solutions for gear honing
Another important factor for gear honing are the tools and their geometry and material. The tool solutions tailored to the respective process ensure the highest level of quality when it comes to the surface and profile of toothed components. The product range of DVS Tooling covers the entire scope of gear honing tools. The main products include the PRÄWEMA ORIGINAL honing (Figure 11) and the VarioSpeedDresser (VSD) dressing tool (Figure 13).

The forces applied during gear honing for highly precise machining results are enormous. These forces in combination with component-specific influences can lead to undesirable vibrations during machining, which must be absorbed to prevent inaccuracies. This is why PRÄWEMA ORIGINAL honing rings have two zones: The geared processing zone enclosed by a second zone, the so-called damping zone. This second zone dampens the vibrations that occur during machining, preventing their transfer onto the honing head and the machine.

Pre-cut PRÄWEMA original honing rings feature quality that comes much closer to the required series quality than comparable honing rings on the market, which is usually only achieved after dressing during the process. We make this possible with Vario Speed Profiling® (VSP for short), which yields extremely high pitch accuracy and profile shape quality through profiling during rolling, while at the same ensuring that the entire honing ring gearing remains at a constantly high quality.

The latest generation of PRÄWEMA SynchroFine® gear honing machines uses the so-called VSD technology for dressing the honing tools. “VSD” stands for Vario Speed Dressing®   and describes a dressing process with a geometrically defined cutting edge in which only the leading cutter of the dressing tool enters the honing ring. Compared to conventional dressing with diamond dressing gears, VSD dressing tools achieves previously unattainable profile shapes and accuracies. The achievable roughness improves from 2.0 μm to 1.3–1.4
μm. Through the use of our proprietary DVS LaserCut finishing technology on the VarioSpeedDresser, the surface quality and profile quality of toothed components can be increased even further. During a special vibration process, the achievable roughness can be increased from 1.3–1.4 μm to 0.8 μm using a refined VarioSpeedDresser and a honing ring with special grain. The downside is that the honing time increases by 3–5 seconds.

Economy with maximum precision
By precisely coordinating all process steps, the integrated manufacturing solution developed by the DVS TECHNOLOGY GROUP enables the production of high-quality rotor shafts that meet all the requirements of EV transmissions. With this process, the DVS Group also enables highly efficient production while at the same time significantly reducing the cost per unit. In some cases, the costs are up to 40% less compared to conventional production.

Media relations:
DVS TECHNOLOGY GROUP . Kerstin Stumpf-Trautmann . Head of Marketing
Johannes-Gutenberg-Str. 1, 63128 Dietzenbach, Germany
Phone: +49 6074 3040640 – Mobile +49 171 7528052
E-mail: kerstin.stumpf-trautmann@dvs-technology.com
Website: www.dvs-technology.com

NVH Testing as the Key to Successful e-Drives

E-mobility gives rise to new challenges in drivetrain testing

Vehicle acoustics are essential for driving comfort and safety

New approaches to NVH testing from ATESTEO, the drivetrain testing market leader

Throughout the world, including since recently at its new testing location in East Lansing, Michigan, the leading drivetrain testing specialist ATESTEO demonstrates how OEMs and powertrain developers can sustainably optimize powertrains using early drivetrain testing. This applies in particular to NVH in electric vehicles.

Developments in New Mobility are strongly driven by electromobility. Completely new powertrains provide emission-free propulsion in vehicles. To ensure the quality, performance, design, efficiency, and comfort of future standard production vehicles from the outset, the drivetrain and powertrain are tested at an early stage of development.

Developments in New Mobility are strongly driven by electromobility. Completely new powertrains provide emission-free propulsion in vehicles. To ensure the quality, performance, design, efficiency, and comfort of future standard production vehicles from the outset, the drivetrain and powertrain are tested at an early stage of development. Vehicle acoustics, including noise and vibrations, play an important role in driving comfort. Electric drivetrains have the advantage of being quieter; thus increase driver comfort. However, the noises of the gearbox and power electronics are no longer masked by combustion engines. The quieter electric vehicles become, the more prominently the noises of the subsystems and aggregates are perceived. This is why measuring the acoustics of electric drives is becoming more and more critical to success.

NVH behavior of the electric powertrain and its effects

NVH phenomena (noise, vibration, harshness) are audible or tangible vibrations in the vehicle. The aim of NVH testing is to recognize and avoid these vibrations during drivetrain development. NVH phenomena in e-mobility arise primarily through new components with higher frequencies such as inverters and e-motors. Gear noise and rattling and clonk effects can also arise from these components.

How NVH phenomena arise in the e-drive unit (EDU): The elastic deformation of the transmission, along with tiny manufacturing deviations and tolerances, leads to tooth contact creating a dynamic excitation as a source of noise. The shafts and bearings transfer this excitation to the housing. The housing in turn radiates the dynamic energy. In the resonance areas of the housing, the vibration becomes audible. Other parts such as the mounting system or side shafts can also transmit the excitation to the body of the vehicle, which in turn also radiates the noise.

How to counter NVH phenomena in development and testing

The inverter, e-motor, and cables, along with new transmission designs for high speeds, lead to new challenges for NVH testing. Certain inverters have thin and flat housings that tend to radiate the noise at natural frequencies. New transmission designs feature planetary gears with high speeds and interaction between motor shaft and sun gear. The challenge of optimizing the NVH properties of the inverter lies in IGBT clocking. The inverter has a high unpleasant frequency around 10 kHz and can emit electromagnetic disturbance (EME). An electric motor runs at speeds of up to 25,000 RPM, which leads to high sound radiation. Testing service providers need to react to these changed requirements by finding new solutions. For example, quieter test cells are needed to test e-drive units, special frames with a high degree of stiffness have to be built. High-speed test bench motors are required to test fast-running e-motors and reduction gears.

Success factor 1: high-performance NVH test benches. To fulfill the higher demands of NVH testing in e-mobility, ATESTEO developed two new NVH test benches with 700 kW and 1,000 V DC power plus a new high-performance test bench with an inverter with 10 kHz IGBT clocking and a fast speed and torque controller. ATESTEO employs the test benches to conduct very dynamic test cycles for simulating real conditions of operation.

Electrical Drive Unit (EDU) for sound power measurements with 10 microphones

• Triaxle and uniaxial acceleration sensors:
  • Important positions are bearings, large surfaces, EOL point
  • Rubber mounting position at active and passive side
• High damping frame
• Factor of ten times stiffer than the engine mounts
• Original rubber mounting at the stands

Success factor 2: a high-speed test bench motor. At ATESTEO, a key test bench component for NVH testing on EDUs is a completely liquid-cooled high-speed test bench motor with a maximum speed of 25,000 RPM with vibration of less than 1 mm/s RMS. The motor can apply a torque of up to 600 Nm with an efficiency of 96.5 %

uccess factor 3: an innovative test bench layout. All components of the EDUs, transmission, and e-motors can be tested on the NVH test benches at ATESTEO. The 6.5 by 6.5 meter large ISO 3745 class 1 acoustic chamber contains a 60-tonne decoupled test bed. The frequency range is 150–16,000 Hz with the background noise level of less than 35 dB(A). The DC 1,000 V, 1000 A, and 700 kW power ratings fulfill all the requirements of high-performance electric vehicles.

Success factor 4: EMV testing. The electrification of drivetrains leads to the necessity of testing the electromagnetic compatibility of the electrical components and systems in the vehicle. For this purpose, ATESTEO is planning an EMC test bench with a semi-anechoic chamber for measuring emissions in accordance with CISPR25 and immunity measurements in accordance with ISO 11452. The chamber focuses on the testing of electrical components such as EDUs, e-motors, or inverters under full load and maximum speed. Specifications: 1200 V and 500 A (800 A peak), 5,000 Nm torque per side shaft and a maximum speed up to 25,000 RPM for testing an e-motor.

NVH test field of ATESTEO: Currently, there are five test benches. On two identical test benches, a front and a rear EDU of AWD vehicles can be run simultaneously, which shortens the test time. Commissioning and parameterization are carried out on the high-performance functional test bench.

Equipped for the mobility of the future

The new challenges of e-mobility are clearly presented and solved in the testing environment. OEMs require the full spectrum of NVH testing, especially for testing and avoiding new NVH phenomena. Competence, experience, and technological know-how are what is needed. Leading drivetrain testers such as ATESTEO offer the entire spectrum of NVH testing on test benches developed in-house according to the highest standards with detailed knowledge of their working behavior. They test wherever powertrain development takes place. ATESTEO now conducts testing at its site at the heart of the American automotive industry, in East Lansing, Michigan, offering testing sites in Germany, China, and Japan as well.

Suitable Battery Models for Different Applications

Mareike Schmalz, Manager Battery Advanced Development, APL in Landau, Germany
Morten Kronsted, Manager Design and Simulation, APL in Landau, Germay
Dr. Marcus Gohl, Senior Manager Advanced Development, APL in Landau, Germany

The rapid transformation to climate-neutral mobility is only possible through accelerated design processes with increasing front-loathing. This gives simulation ever greater importance as an essential development tool. A key area of application is in batteries, from the establishment of new cell chemistries to the coherent overall system design. APL responds to the increasing complexity by tightly integrating simulation and testing environments. The following article takes a closer look at the challenges of battery development and the modeling approaches used in each case.

Necessity of battery simulation

The development objectives for traction batteries and their various system levels require a variety of modeling and simulation tools, Figure 1. Starting with conceptual design and basic layout the entire system must first be considered and dimensioned. This is best done using system simulations, as shown in the example in Figure 2. To predict the behavior of the battery system of a BEV while driving, a vehicle model with an integrated battery model was created. The parameterization and validation took place both via component tests on test benches and through vehicle investigations
under real driving conditions. Such an overall vehicle simulation allows the initial design of the electric powertrain in new systems. Furthermore, it forms the basis for revealing optimization
potentials and allows for benchmark comparisons to existing vehicles.

Figure 2: Simulation of a battery system embedded in the APL BEV-model and validation with measurement data.

In addition to the proper basic design, the performance of the overall system is highly dependent of how the system levels and components interact. Each battery cell in itself is a highly complex electrochemical system. All internal reactions and physical processes have their own dependencies on the influencing factors acting on them, such as temperature. This often results in a complex interplay of overlapping effects, the sum of which influences the macroscopic cell and system behavior, Figure 3. There, the dependence of the battery internal resistance was measured on a BEV for benchmark purposes. The influences of State of Charge (SoC) and temperature are clearly visible.

Figure 3: Impact of the parameters State of Charge and temperature on the internal resistance of a battery system in a vehicle

When connecting several hundred cells, individual effects can be further amplified. Therefore, the APL Cell-to-Pack model describes each single cell, with their respective characteristics, in the simulation of a battery pack accordingly. Specific system properties and cell-to-cell variations can lead to local hot or cold spots, strong current peaks and drifts in the state of charge, as the simulation results show, Figure 4. These effects strain the overall battery system and significantly increase the burden on particular cells: higher temperatures, higher current loads and more extreme states of charge. The cells show accelerated degradation which manifests as an increase in internal resistance and a loss of storage capacity. This can lead to a self-reinforcing effect. The performance of the total battery pack worsens due to the limitation of individual cells.

Figure 4: Simulation results of a battery module of 12 individual cells. The different characteristics of the cells lead to local hot- and cold-spots.

The illustration of the mutual interactions between the system levels makes it clear that a variety of measures and optimizations in the development and operation of the system are necessary in order to address the problem in a targeted manner. These extend to all levels of the battery system, starting with the choice of the appropriate cell in terms of chemistry, geometry and quality, the design of the circuit topology or the cooling system up to the operating and balancing strategies used. These questions are answered with the aid of suitable simulation models.

Relevance of thermal simulation

Figure 5 shows the influence of different cooling concepts on the temperature distribution within the cell body. For example, in a cell cooled from below, large temperature differences occur over the height. Depending on the cell geometry, these can amount to several Kelvin. In the warmer cell regions, the electrochemical transport processes are favored; consequently, this part of the cell is more efficient and thus also more electrically stressed. Due to the increased thermal and electrical stress, the cell will age above average in this area. Nevertheless, the bottom cooling remains a widely used cooling concept. It offers significant advantages in terms of economic and safety aspects. To assess the consequences of the thermal management and to develop the right cooling strategy, APL uses a combination of 3D electro-thermal simulations with spatially resolved aging models. CFD calculations are used for the design of the cooling channels.

Basic prerequisite for all above mentioned simulations and design studies is an adequate depiction of the battery cell as the core element. The models used differ in their underlying scientific, technical or mathematical content. The approaches employed at APL can be broadly categorized into the three following types.

Figure 5: Simulation for investing the temperature distribution over the cell body when using different cooling concepts.

n addition, other physical phenomena such as thermal effects, volume changes, material stresses or particle size distributions can be taken into account. The underlying electrochemical model is thus extended to a multi-physics model. Models of this category are used at APL to investigate novel problems such as new material compositions and structures inside the cell. At an even lower level is the field of molecular or atomistic models, which are used, for example, to study the behavior of lithium ions in the course of charge/discharge cycles. These modeling forms are applied to investigate the influence of different crystal structures on the lithium diffusion or to describe the Solid Electrolyte Interphase (SEI) formation on the surface of the electrode particles.

Examples for physicochemical models:

• single particle models to describe the transport processes within a single active material particle of the electrode
• pseudo-2D models, which depict all relevant cell components including current collectors, electrodes, electrolyte, and separator in a simplified way
• multi-dimensional multiphysics models to simulate the internal cell structures and the inclusion of other physical effects such as thermal or mechanical stresses as realistically as possible

In general, electrochemical and physical phenomena are considered, with a focus on lithium diffusion and intercalation. The models illustrate processes and parameters that are not accessible experimentally or only with great difficulty. The aim is to build a better understanding of the mechanisms inside a battery cell and to further optimize the cell design. Thus, this form of modeling is used in particular in cell development and optimization with regard to the selection of materials, the composition and the morphology of electrodes or electrolyte.

Based on basic models for describing individual phenomena, these are supplemented by further physicochemical effects and thus expanded to more complex models. The quality of the predictions made can be increased by the continuous expansion of the model, but at the expense of the computing time. A validation of the models with experimental data is usually only possible at the macroscopic
level. Many of the generated parameters are not directly measurable and are therefore not available for comparison.

The conflict between the level of detail and computational time means that even simpler battery models (for example single particle models) are used in research, provided that they are appropriate.

Equivalent circuit models

In the equivalent circuit models (ECM), an analogy to the battery is created that accurately reflects its electrical behavior. To do so, basic electrical components such as voltage sources, resistors and capacitors are utilized. With the appropriate constellation and parameterization of the components, these models can be applied in a variety of ways.

Examples for ECM:

• the Rint-model, which describes the battery simply by a voltage source and an internal resistance
• the Thevenin model, in which an additional Resistor/Capacitor (RC) element describes the dynamic transient response and the polarization
• the DP (Dual Polarization) model, where concentration polarization and electrochemical polarization are taken into account using two RC elements, Figure 6.

In this form of modeling, the focus is on reliably predicting the external electrical performance of the battery. From direct analogies of the components, correlations to the physical effects inside the cell can be possible to a certain extent. ECM are very flexible to use while remaining fairly computationally efficient. Therefore, equivalent circuit models can be used in real-time applications, such as inside the BMS. They are highly scalable for SoC calculations, adaptive methods (e.g., Kalman filters), and thermal models, and can be applied at the cell, module, or pack level. These key advantages make ECM an extremely popular tool for battery system development and BMS-driven battery operation. Parameterization of the models can be done via pulse tests or electrochemical impedance spectroscopy. APL uses a combination of both methods for optimal mapping of all time domains.

Figure 6: Schematic architecture of equivalent circuit models for battery simulation.

Empirical models and artificial intelligence

Unlike physical-chemical models, empirical models are not based on physicochemical principles but are purely mathematical approaches. They treat the battery cell as a black box. Based on extensive
measurement data, input and output variables are empirically linked. The required data sets are collected in APL’s large test lab for battery cells. With this data the models are trained in battery behavior.

Examples for empirical models:

• neural networks
• analytical terminal voltage models
• stochastic battery models
• fuzzy logic

This class of models is used in particular to model parameters and effects that are difficult or impossible to model physically. Empirical models are particularly popular in the field of aging simulation and lifetime prediction, since the sum of the physical-chemical processes occurring during battery aging is hardly predictable. In aging test series performed over several months, certain influencing parameters, such as the state-of-charge, the current rate or the depth of discharge, are varied under different thermal boundary conditions. Calendar and cycle aging effects can be evoked in isolation. At APL the data is used to train an artificial intelligence for battery state prediction [1].

Applying the models in the development process

Virtual models have become an irreplaceable tool in vehicle and battery development. With the help of simulations, requirements are broken down in a top-down approach from the vehicle requirement to the component and the physical-chemical phenomenon. For the HV battery a great variety of modeling approaches are available. Which is most appropriate depends largely on the application.

In electric powertrain development, equivalent circuit models or highly reduced physicochemical battery models are predominantly used. In cell development with respect to chemistry and materials, meanwhile, it is the physicochemical models that lead the way.

In order to address various engineering tasks and demonstrate the essential synergies from the battery cell to the battery pack, APL combines several models of different types and applies them together. In addition, regular experimental validation of the virtual predictions is performed to ensure the robustness of the results.