15-16 May 2024, Novi, MI, USA

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