News

A New Material Solution for Low Wear, Low Friction, and Electrical Insulation in Automotive Transmissions

Posted on 31st March 2026

Geoff Lewis, Technical Director, Duvelco

What is a New Material?

Being ‘new’ is claimed with some regularity in the world of polymers; however, step changes in performance are less frequent. Here, I am going to look at an innovation that may pass the test and rightfully be called a new material. The polymer in question has the trade name Ducoya.

In terms of chemical type, it is a semicrystalline thermoplastic block copolymer bearing the unfamiliar name PMDA-ODA or, in long form, PyroMellitic DiAnhydride – 4,4‘-OxyDiAniline. The repeat unit is shown below:

This is a polyimide with an ‘I’; not a polyamide. Polyimides are a vast and rapidly growing class of polymers. The number of polyimide papers written annually has exploded in recent years. Polyimides include thermosets, thermoplastics, amorphous, semicrystalline, and photo-imageable materials.

The above graph shows the number of papers regarding polyimide. Source: Researchgate – Number of citations per year from 1975 to 2019, Web of Science.

Some may recognise this molecule as being from the 1960s; however, that is not the new part. This molecule, initially developed for NASA’s space programme, has long seemed too difficult to source and too expensive for many automotive applications.

This is especially the case as the industry moves into an era of cost-competitive BEVs, and, from a European and North American perspective, an era of low-cost, possibly subsidised Chinese BEV imports to compete with.

So, if it isn’t the molecule, what is new?

The innovation here is a new, patented manufacturing process that also covers the resulting material. Many high-performance plastics, including those produced by the traditional PMDA-ODA Manufacturing method, utilise monomers dissolved in harmful, high-VOC solvents. The environmental and high-cost considerations of these solvents mean they must be separated, distilled, and reused, consuming a large amount of energy in the process.

Ducoya avoids most volatile solvents used in the process and instead employs supercritical carbon dioxide and a catalyst.

Therefore, it is straightforward to separate the polymer from supercritical carbon dioxide by lowering the pressure. The carbon dioxide is repressurised and stored for reuse. This single step greatly streamlines manufacturing at scale, making the polymer considerably more accessible for automotive applications. However, this is not the end of the story. While the original aim of the invention was to simplify manufacturing at scale, when the properties of the resulting polymer were compared with those of its traditional predecessors, something remarkable emerged – dramatically improved mechanical and tribological properties.

The above graph consists of Ducoya preliminary data – arithmetic mean of five specimens, and best traditional values taken from published datasheets, none of which reported data over 260 °C.

The above graph consists of Ducoya preliminary data – arithmetic mean of thirty specimens, and best traditional values taken from published datasheets, none of which reported data over 260 °C.

Datasheet1

Ducoya G021 ISO is a filled version of Ducoya, containing 15 % wear- and friction-optimised graphite. Initial investigations of tribological properties in dry conditions indicate a significant improvement in wear factor compared to the best traditionally produced polyimides of this type. While much work remains to be done with this
specific molecule, this result seems to confirm earlier work by Irisawa et al. on several polymers, showing that the wear rate is inversely proportional to the product of tensile strength and elongation.

Of particular importance is the continued performance of this molecule at significantly elevated temperatures. This is because, when dry friction occurs – whether by design or due to off-design operation under adverse conditions – temperatures on the wear surface can rise substantially compared to the bulk material. For instance, regular operation at 120 °C can quickly lead to temperatures exceeding 240 °C on the wear surface under harsh sliding conditions (High PV value).

It should be noted that this general hypothesis applies only to materials of the same type (in this case, PMDA-ODA polyimides) and only when tested under identical conditions. Further work will determine whether this prediction holds for Ducoya G021 in comparison with other PMDA-ODA polyimide polymers.

Why would this be important to Battery Electric Vehicles?

As BEVs increase in torque, while package space and cost must decrease, this can lead to higher PV values as the available load area diminishes. This also reduces the weight of single-speed and multi-ratio transmissions. Epicyclic transmission layouts may particularly benefit from this improvement. Furthermore, Ducoya, being wear-resistant, although still relatively soft compared to metal, allows metallic debris, such as burrs and wear particles from gears, to embed in its material and be removed as contaminants from the lubricating oil. While this embedding must be limited, removing metallics before they can interfere with the proper functioning of the electric motor – often sharing the same lubricating oil as the transmission – can only be beneficial.

Conclusion

An interesting new material that adds a new dimension to accessibility and performance in automotive applications. Here, we have focused on mechanical and tribological properties.

Future Work

Future publications will describe why this unusual and newly applied process using supercritical carbon dioxide should lead to such improved mechanical and tribological performance.

Opportunities arising from the resulting electrical performance in conjunction with the latest high-precision
moulding techniques will be highlighted.

In addition, test results will be published in which the relationship between t·ε2 and wear rates in various
situations, as described above, will have been investigated.

1 DuPont Vespel® SP-21 ISO Reference No. VPE-A10863-00-B0614 published 2010 and 2021.

Proposal of Next-generation HEV System

Posted on 24th March 2026

Kazuyoshi Hiraiwa, President, FINEMECH
Shinji Morihiro, Representative, M Powerlabo

Background of the proposal

In recent years, the problem of BEV has become apparent, and the value of HEVs has been reevaluated. Under these circumstances, we would like to propose a next-generation HEV system.

Purpose of the proposal

This proposal is based on the THS (Toyota Hybrid System). This is because the THS is superior to the series model in terms of power transmission efficiency as an E-CVT. The THS used in the Prius is simple system but it is generally said to have problems with starting acceleration performance and high-speed fuel economy. Looking at the specifications of the Prius, in order to ensure starting acceleration performance, the capacity of the MG2 (Motor Generator 2) for driving in recent models is larger than that of the initial model. However, the increased capacity of the MG2 makes to a deterioration in high-speed fuel economy. On the other hand, Toyota has added a four-speed automatic transmission planetary gear mechanism to the THS for LEXUS to improve both fuel efficiency and acceleration performance. However, this can only be applied to FR cars due to the axle length.

This proposal aims to improve fuel efficiency and acceleration performance by applying a dog-clutch parallel-shaft transmission mechanism to the THS, while also realizing a configuration that can be installed in FF vehicles. (see Figure 1)

Proposal Overview

The power transmission route between the ring gear and the output shaft of the planetary gear for torque division is the „mechanical route“ (M route), and the route that transmits power from the sun gear to the output shaft via MG1 and MG2 is the „electric route (E route)”. If the route between the input shaft and the output shaft is a „direct connection route (D route)”, a dog clutch type transmission mechanism is provided for each route (see Fig. 2). That is, there are only three sleeves. Normally, both the M route and the E route are transmitted as an E-CVT, but when switching from H-1 to H-4, which will be described later, the gear is shifted through the D route to avoid loss of output shaft torque when driving on one route while driving on the other route, and when shifting under high load.

MG capacity (at ICE power 1) is assumed as follows: This takes into account that if the input shaft is fixed and used as a PHEV, the driving force equivalent to that of an ICE can be obtained. Also, the specs of the early PRIUS were almost this ratio.
MG1 0.4
MG2 0.6

Basic rule of Sleeve switching (Dog clutch)

Torque is set to 0 and the engagement is related, and the engagement is carried out with a speed difference of 50rpm or less.

Operation

First, we will explain the shifting operation of the E-CVT in HV mode. If the sleeves are S1, S2, and S3, then the H-1 is a combination of the M route (S1) and the E route (S2) with Lm and Le. Switching from H-1 to H-2 is done as follows: When driving on Lm on the M route, the MG2 torque is reduced to zero at the mechanical point (when MG1 stops), making it easier to switch the E route from Le to Me, and the output torque can be shifted without change. That is, the switching from H-1 to H-2 is carried out with gear ratios near the mechanical point of H-1.

Also, switching between H-2 and H-3 is done through the D-route Ld (D-1). In other words, if the gear ratio is equal to the value of Ld while driving in H-2, the speed of the S3 and the opponent’s gear matches, so it is easy to shift S3 and switch to D-1 at this point. S1 and S2 can be freely operated while driving in D-1, so if you revive the power generation of MG1 and the drive of MG2 by connecting H-3 in the operation chart, it will switch to H-3. This can also be done without any change in output torque.

Similarly, it is easy to switch from H-2 to H-4 via D-3. You can switch in the same way in these reverse orders.

In addition, the above switching is done with a fixed gear ratio, but especially in low to medium load driving, it is possible to switch without the drive of the D-route in any gear ratio. This means that you can drive on one route, M route and E route, while switching between the other. In this way, in low- to mediumload driving, it is possible to switch between any gear ratio without little change in output torque.

Kickdown

If you press the throttle pedal sharply while cruising on the H-3, follow these steps:
When the ICE power is increased and the gear ratio is equal to the value of D-1, switch S3 to Ld (D-1) and operate S1 and S2 to switch to the desired drive mode while driving with D-1.

If you press the throttle pedal sharply while cruising on the H-4, follow these steps:
When the ICE power is increased and the gear ratio is equal to the value of D-2, switch the S3 to Hd (D-2), and operate the S1 and S2 to switch to the desired drive mode while driving with D-2.

Of course, if the amount of throttle pedal depression is not very large, you can switch at any gear ratio by switching while driving on either the M route or the E route mentioned above.

MG1 & MG2 Stops

It is widely known that power loss due to dragging torque of MG1 and MG2 occurs when the ICE stops at medium or high speeds, or when MG2 is driven at low load at high speeds. The system allows MG1 and MG2 to be stopped as needed. (See Figure 5)

This means that if the ICE stops while driving at medium to high speeds, you can stop MG1 by putting S1 in neutral. If you want to revive the connection of MG1, rotate MG1 to synchronize and shift S1 again. In addition, the gear ratio near the mechanical point of the H-4 and the low-load high-speed driving on the D-1 and D-2 can keep the MG2 at a standstill if the S2 is neutral. This avoids loss of drag torque and improves fuel economy.

Application to PHEV

As is well known, PHEV is established by increasing the battery capacity and providing a means to fix the input axis, allowing MG1 to participate in driving in addition to MG2 in EV mode. In this case, by driving one of the M routes and the E route while switching between the other using the same method as above, you can switch between EV mode while preventing loss of output torque. This means that it is possible to smoothly switch between the MG2’s three-stage drive and the MG1’s two-stage drive without losing drive torque. Of course, this is when switching, not to mention that after the switch is complete, you can drive both MG2 and MG1, or even one of them. It can also be driven by stopping one side, allowing for a variety of drives.

Advantages of this system

• The multi-stage THS reduces the capacity of the MG2 while ensuring acceleration performance in the low speed range and driving torque during reverse driving.
• In HV mode, the drive mode can be switched without changing the output torque. Moreover, in medium and low load driving, it can be switched with any gear ratio.
• No oil pump or friction clutch required.
• MG2 and MG1 can be stopped when it is not needed.
• By reducing the size and stopping of the MG2, fuel efficiency can be improved by about 6 ~ 8 % during high-speed cruising.
• When applied to a PHEV, it makes EV mode driving in multiple modes to achieve smooth shifting.
• While having the above functions, it fits into a size that can be installed on an FF car.

When compared to the THS+4AT and Renault systems, we can see that this system has many advantages. (See Figure 6).

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References

• TOYOTA Hybrid System, Development of Multi Stage Hybrid Transmission , K. Okuda, Y. Yasuda, M. Adachi, A. Tabata, H., Suzuki, K. Takagi(Toyota), T. Atarashi, R. Horie (Aisin AW), 2017 SAE World Congress, No.2017-01-1156 (2017/4/4-6)
• Renault HEV System, The new DHT from Alliance Renault/Nissan, Antoine Vignon (Renault FRANCE), CTI Symposium 2017 Berlin

Boosted Sustainable Electrically Excited Synchronous Motors

Posted on 19th March 2026

Dr-Ing. Philippe Farah, CEO – Founder YEESMA SARL
Dr-Ing. Shafigh Nategh, CTO – Founder, YEESMA SARL
Yu-Chi Tsai, Business Development & Marketing, YEESMA SARL

Electrically Excited Synchronous Machines (EESM) is one of the strong candidates to solve the supply chain risks, costs and sustainability issues due to the Rare-Earth magnets presently used in almost 90 % of the Traction Motors. However, for long, EESM presented lower Performances, especially in terms of Torque density: approximately 10 to 20 % bigger volume required combined with Lower Efficiency (down to 3 %) compared to Radial Flux Interior Permanent Magnets Solutions considered as today’s Benchmark.

Introduction and Objectives:

YEESMA combined 2 major concepts into what’s called YEESMA that stands for Yokeless (Yoked) Electrically Excited Synchronous Machines. This Proprietary solution consists of an Axial Flux AND Electrically Excited Topology. Preferred topology is a Dual Rotor, Single Stator that helps solving the Packaging and Performances challenges: up to 20 % Torque volumetric density, with more than 60 % Bill Of Material (BOM) cost reduction AND 60 % Higher Sustainability Index.

 

Figure 1: Topologies Comparison

 

Inverter Phase current is also significantly reduced thank to a Unity Power Factor and participates to the 60 % Cost reduction mentioned above.

YEESMA Technology

YEESMA solution is an Axial Flux based topology. Preferred solution is typical Single Wound-Stator sandwiched between 2 Wound-Field Rotors. Note that intrinsic to Axial Flux, inner diameter areas being “empty”, YEESMA can incorporate there both Position Sensor and Rotor Power Supply (being Brush type, or Brushless Inductive Transformer).

 

Figure 2: YEESMA Technology

 

Development Methodology

YEESMA developed their own FEA & Optimization models to reduce development time while still keeping “Digital-Twin” approach: Define at best all requirements’ details, from Performances outputs through Environment Specifications, like e.g. Air Cooling requirements for a 2-Wheelers or Oil-cooling specifications for a Truck Application. Our Approach heavily relies on conducting thorough Simulation Analysis before building Hardware parts. Such optimization process through a 3D-FEA Electromagnetic analysis is shown hereafter:

 

Figure 3: Optimization Process

 

The genetic algorithm progressively concentrates the population of candidate designs in the performance-optimal region of the search space.

Case Studies Results

Several Case Studies were conducted following same “Digital Twin” process. For simplicity and confidentiality reasons, only 4 cases studies are presented here.

For each case, we used CO2 footprint as a Sustainably Quantifier. This is done through summing up for each design material amount (active parts only), mostly Steel, Copper or Aluminum, and rare-earth permanent magnets for Benchmarks solutions.

 

Figure 4: YEESMA Case Studies Results

 

Proof Of Concept Experimental Results

To further validate all our design tools, YEESMA designed, built and tested its own Proof Of Concept Hardware [1] – [2]. This has been done through the Department of Engineering “Enzo Ferrari”, University of Modena and Reggio Emilia (Italy).

Picture hereafter shows (manually) wound rotor.

 

Figure 5: YEESMA Wound-Rotor

 

Whole tests were conducted on a dynamometer setup, with an external drive capable to provide both Stator Armature AC currents and Rotor field DC current.

Thorough analysis was done at first at no-load comparing theoretical BACK-EMF and measured voltages at various excitations levels. Exceptional confirmation was obtained through the whole excitation current range. Figure below measured data at 2000 rpm and 6.0A (considered as nominal excitation current)

 

Figure 6: Comparison between Measured and Simulated Back-EMF

 

Load-tests focused first in the Continuous Torque/Speed area and shows as well very good fit between FEA Simulation and Experimental Results. Less than 5 % difference can be reported up to 1.6 times Maximum Continuous Torque

 

Figure 7: Comparison between Measured and Simulated Torque

 

Conclusion

This study has presented the Yokeless Electrically Excited Synchronous Machine (YEESMA) as a viable, high-performance, and sustainable alternative to conventional rare-earth permanent magnet machines. By eliminating the need for rare-earth materials and transitioning from a radial flux to an axial flux configuration, the YEESMA topology achieves significant reductions in copper usage, weight, and raw material demand, while maintaining competitive torque and power density. In addition, the proposed design achieved close to unity-power factor, it significantly reduces Inverter current demands and participates to the Overall Cost reduction.

Further development work will focus on the Manufacturing axis with Production-intend designs developed with an Industrial Partner.

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References

[1] V. Mangeruga, A. Piergiacomi, S. Nategh, P. Farah and S. Nuzzo, „Structural Investigations on Yokeless Electrically-Excited Segmented Armature Axial Flux Motor,“ 2025 IEEE Workshop on Electrical Machines Design, Control and Diagnosis
(WEMDCD), Valletta, Malta, 2025, pp. 1 – 6
[2] Design Optimization and Experimental Validation of an Innovative and Sustainable Electric Machine Topology,“ in IEEE Transactions on Transportation Electrification, Oct. 2025. (Submitted)

UK testbed for sustainable gear manufacturing: scaling to Indian volume production

Posted on 11th March 2026

Dr Agnes Ragondet, Group Sustainability Director, Hewland/Hero Motors.

This paper presents a sustainability-driven manufacturing initiative that leverages a UK-based pilot facility to develop, test, and optimise sustainable technologies in gear manufacturing with the objective to enable scalable implementation in Indian high-volume production facilities.

UK gear manufacturing market benefits from a strong industrial heritage and highly skilled workforce [1]. A focus on high quality products and high end applications are key drivers of the UK sector [2].

The UK gear manufacturing market is part of a broader £1.3bn bearing and gear manufacturing industry. The precision gearbox market itself generated $30.3 million in 2023 and is projected to grow at 3.4 % CAGR through 2030 [3].

However, high operational costs, wastes, labour expenses and pressure from raw material price inflation limits the overall advantages of UK manufacturing [4, 5, 6].

Figure 1. The drivers of sustainable manufacturing

In addition, the nature of low volume and custom-designed market leads to higher operational costs, highlighting the demand for greater efficiency and optimisation in both design & manufacturing processes.

The global gear manufacturing market is projected to increase by USD 137.8 billion at 8.1 % CAGR over the 2024 – 2029 period [7]. The market growth is fuelled notably by industrial expansion and increasing demand for high-Performance transmission solutions across various sectors [8].

In India, price competitiveness is a major challenge for gear manufacturing, due to strong competition from low-cost producers abroad. Balancing competitive pricing with quality and profitability in highvolume production remains an ongoing challenge [9].

This paper demonstrates how a sustainability-driven approach to gear manufacturing can address these challenges and enhance efficiency using IoT and smart manufacturing technologies.

The initiative illustrates how implementing these practices within a controlled, low-volume manufacturing environment in the UK can facilitate the technology transfer to high-volume gear manufacturing industry in India.

Process monitoring and operational optimisation

Gear manufacturing is an energy-intensive process that generates significant amount of bi-product material waste.

On average at Hewland, a low volume manufacturing organisation, energy costs associated with gear and transmission production can account for up to 65 % of total factory energy costs, which includes heat treatment capability, while 40 % of the raw materials used in machining operations are lost as waste. In general, manufacturing sector is energy intensive and can consume up to 20 – 25 % of world’s total energy [10].

Additionally, frequent tooling changes, small batch sizes, and customized new designs greatly affect operational efficiency, with up to 35 % of cycle time attributed to indirect production activities such as tooling setup, programming adjustments, and part inspections.

Finally, historical operational standards can lead to a significant increase in downtime, accounting for up to 50 % of an asset’s total energy usage.

All these factors together contribute to a significant increase in the product’s carbon footprint. Figure 1 shows the drivers of sustainable manufacturing study.

Firstly, the case study involved integrating IoT and smart factory tools into each individual manufacturing asset to monitor and analyse productivity and efficiency through energy data combined with manufacturing operation management data.

It involved a physical energy monitoring and data collection device paired with a custom-developed intelligent tool for data processing and analysis.

The combined analysis of energy consumption data and manufacturing operations management software offered valuable insights into operational efficiency, revealing opportunities for both energy savings and performance improvement.

First key outcomes included:

• 20 % average asset downtime reduction
• 260,000 kWh reduction (16 % of annual consumption)
• 52tCO2e reduction
• Greater process standardisation
• Optimised operational cost prediction

The in-house developed smart factory tool delivered precise data on the status of each manufacturing operation, enabling its use as a powerful digital twin to correlate asset and operational costs, and facilitating easy transfer to high-volume manufacturing cost predictions.

Circular manufacturing strategies

The next phase of the study focused on exploring circularity opportunities in manufacturing. Given the large volume of swarf waste generated during operations, it was crucial to identify ways to minimize waste while creating opportunities for material reuse.

The case study focused on components requiring a central hole to be machined in the steel bar. Two turning operation methods were assessed:

• A conventional process where the entire hole was produced by cutting through the material, converting all removed material into swarf.
• A more sustainable process using an optimised tool path that cut around the hole’s perimeter, enabling the recovery of a solid steel piece that could be reused to manufacture another component.

The study revealed that cycle times could be reduced by 60 % to 90 %, depending on the hole size, cutting energy cost per operation by similar proportions, while waste generated per part decreased by up to 60 %.

Such simple but yet effective approach enables substantial material savings, particularly in high volume production. For instance, machining a 400cm3 piece of steel using the perimeter tool path would save 15tons of steel and 29tCO2e in a 5,000-part batch, allowing the recovered material to be reused for producing other components.

Sustainable design optimisation

The final phase of the study focussed on sustainable design opportunities, examining how design choices impact overall manufacturing costs, cycle times, material usage and product carbon footprint.

The component selected was a shaft with a primary wheel, originally manufactured as two separate parts welded together. This two-part design was compared with a redesigned single-part solution.

As shown in Table 1 the single-part design solution achieved a 51 % reduction in energy consumption, in-house cycle time and CO2e emissions, while material wastage during production decreased by 11 %.

Note: the overall cycle time and cost of the two-part solution was greatly increased due to an additional welding operation that also sub-contracted.

The single-part design solution needed revision to account for a greater gap between the gears to allow for grinding operation. Although this process would not be necessary for motorsport application, it is essential for EV application in order to reach NVH requirements. High volume machining operations such as power skiving and gear honing are also considered to reduce the gap to a minimum while the choice of gear type, spur vs helical, can also impact the required distance between the gears.

Table 1. Comparison of energy cost, material wastage and carbon footprint between 1 part and 2 part design solutions

Overall, this case study demonstrates various opportunities for a more efficient and sustainable gear manufacturing approach that can be easily transferred from low volume to high volume manufacturing context as summarised in Figure 2. While low volume context allows for quick and flexible development, the high volume implementation allows for greater savings and optimisation benefits.

Manufacturing and design decisions can be influenced by a sustainability approach to be more energy efficient, more cost effective and generating a lower carbon footprint of the product.

Figure 2. Process and benefits of low volume case study to high volume technology transfer

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References
[1] The cost-benefit of manufacturing in the UK
[2] UK automotive manufacturing: facing up to the challenges of the future
[3] UK Precision Gearbox Market Size & Outlook, 2030
[4] https://www.manufacturingmanagement.co.uk/content/news/uk-manufacturing-challenges-make-uk-survey-findings
[5] https://www.cbi.org.uk/media-centre/articles/uk-manufacturing-struggles-to-regain-momentum-as-cost-pressures-mountand-orders-remain-weak-cbi-industrial-trends-survey-july-2025
[6] https://www.expressandstar.com/news/business/business-picks/2023/09/19/supply-raw-materials-and-import-costs-top-ukmanufacturing-concerns
[7] https://www.technavio.com/report/gear-manufacturing-market-industry-analysis#:~:text=Gear%20Manufacturing%20Market%20Size%202025,in%20this%20evolving%20market%20landscape.
[8] https://www.prnewswire.co.uk/news-releases/industrial-gearbox-market-to-reach-usd-37-1-billion-by-2029–key-trends-growth-drivers—valuates-reports-302394728.html#:~:text=Major%20Factors%20Driving%20the%20Growth,strong%20emphasis%20on%20energy%20efficiency.
[9] https://www.imarcgroup.com/india-gear-market
[10] https://zipdo.co/sustainability-in-the-manufacturing-industry-statistics/

Smart Chassis Meets Smart Powertrains

Posted on 9th March 2026

A Practical Guide to Integrated Motion Control in 2026 and Beyond

This whitepaper explains why chassis–powertrain integration is no longer optional, but a strategic imperative for OEMs and Tier 1s. It focuses on concrete use cases – torque vectoring with brake-by-wire, steer-by-wire with active suspension, and centralized vehicle motion control – and discusses the engineering methods, architectures and safety concepts required to master this integration.

A Long Journey from the First Hair-pin Stator Line to Continuous Flow Winding

Posted on 4th March 2026

Edoardo Freschi, EV-Traction Sales Director, IMA EV-TECH

It was early in 2009 when ATOP started developing the first fully automatic line to produce hair-pin stators. Being a medium-sized company and not having, at that time, the capacity to support such a wide range of solutions, it was necessary to make a choice between the well-known, state-of-the-art coil insertion technology or exploring the brand-new copper bar technology with a pioneering approach. With a focus on the future, the choice was to explore this new territory and today we can say the decision was the right one.

As has always been the case in over 30 years of IMA EV-TECH – ATOP history, process equipment must preserve some of the unique characteristics that have always distinguished our machines: they must be innovative, flexible and compact in design.

The main focus was on hair-pin forming process, considered the true key to the success of this new solution. The innovation requirement was met through the introduction of a CO₂ laser for enamel removal on the wire combined with a fully programmable 3D forming robot used to bend copper wire. This solution perfectly matched the second prerequisite of flexibility. In fact, like for the pin forming, all machines in the line had to be suitable for different products with varying dimensions, slot geometries, and conductors per slot.

The application of QCO (Quick Change Over) technology to the new machines in stage of development, appears as a perfect combination. New machines are born with the natural predisposition to receive different sets of tooling for different products. The idea was to have a complete tool installed in the machine with fixed references,requiring no fine-tuning or adjustments to start production. Given the high value of EV motor components, it was defined that, after all quality checks, the first part produced must be a good part. The presence of electric axes to control all process functions definitively helped engineers in their work.

With the experience gained in the electric motor manufacturing field, it was considered an added value to approach the third pre-requisite: compact design. We integrated the electrical and pneumatic cabinets inside the machine frame. Further on, we had chance to learn how automotive industry standards were different in this field. While Tier and Tier 2 customers accepted this solution, OEMs required a more conventional external electrical cabinet. To satisfy both philosophies, today both configurations are available.

In over 15 years of experience with copper bar stators for e-Mobility applications, we have grown our experience thanks to the scientific approach always applied even through a close cooperation of our R&D with universities. Nonetheless, events and reaction of the copper that initially appeared to be inexplicable, have gradually found their explanation. Experience taught us to define the copper “the alive material” because, like a chameleon is capable to change his characteristics so quickly and sometime without any apparent reasons.

Welding is keen while producing the hair-pin technology. From the very beginning the idea to use a mask to align the couple of wires was developed and applied. This solution was later abandoned in all those cases of high slot numbers and small diameters. Where it was preferred clamping by gripper. Today, the alignment by mask is made using a three-effect mask that allows to make tangential and radial wires alignment while providing axial containment. The new mask, thanks to its reduced thickness, perfectly meets the needs of extremely short wire leads, those known in Asia as “minipins”. This is not a novelty, since we already have high-capacity lines in serial production with wire terminals below 6 mm in straight path.

The current state of the art is the ATOP machines generation that represent the fourth generation of machines developed for hairpin stator technology. Maintaining the original pre-requisites, achievements of this latest generation, are the condensation of all experiences matured in those year, with higher process speed and productivity.

What about the future of e-mobility motor design? It is a widely shared opinion that hair-pin stators may represent a transitional solution toward a simpler and more cost-effective process.

Here at IMA EV-TECH, we continue to monitor developments and, just as we did 15 years ago, try to explore possible alternatives. Wave winding, as it stands today, presents clear limitations in terms of motor design constraints, lack of process control, cost, floor space occupation of the production lines and difficulties in achieving a fully automated process.

An interesting alternative to traditional wave winding is the CFW solution, acronym for Continuous Flow Winding. This technology was developed to meet the requirement of the motor from MAVEL. This already solved most of the criticality typical of a wave winding:

• Closed-gap inner diameter, because the insertion is made from outside
• Helicoidal slot profile, offering a well-distributed magnetic flow distribution and helps tremendously on having in a smooth wire insertion process
• Small waves development, that leads to compact footprint equipment. A complete line having the floor space occupation similar to an hair-pin stator line
• Low-height copper headers outside the slots, with crown height contained below 24 mm thanks to outer-slot insertion

Applications with Litz-wire have been developed in recent years, with flexible conductor used to wind single poles stators as well as rigid bars for hair-pin production. It is hard to define what the future will bring, but one thing is sure: IMA EV-TECH will be there supporting the growth of our customers.

Safe and Sustainable-by-Design: Setting New Standards for EV Coolants

Posted on 25th February 2026

Dr. Sander Clerick, Development Chemist, Arteco

The automotive industry is rapidly shifting to low- and zero-emission solutions. Electrification, including hybrid, battery, and fuel cell electric vehicles (EVs), is driving innovation in powertrain and thermal management systems. Moving away from internal combustion engines is crucial to reducing greenhouse gases, air pollution, and their impact on the climate. With transportation accounting for ~28% of global emissions, reducing its impact is essential to achieving global decarbonisation.

Effective thermal management plays a key role in maximising performance and durability. Arteco develops high-performance engine and electric vehicle coolants designed to meet strict safety and environmental standards, with a focus on long-term durability. These formulations are specifically engineered for modern vehicle systems where thermal control is essential.

By applying safe and sustainable-by-design (SSbD) principles during R&D, Arteco ensures its solutions are aligned with future environmental and regulatory standards. This approach balances technical expertise with human and environmental safety, supporting the industry’s shift towards sustainability. The introduction of specialised product ranges marks a significant step forward, setting a new benchmark for minimising environmental impact by embedding safety and sustainability at the heart of product design.

Safe-by-Design

Water–glycol-based engine coolants are widely used in electric vehicles for indirect liquid cooling. Their excellent heat transfer properties, proven automotive performance, compatibility, and ease of handling make them a commercially preferred solution for thermal management. In EV systems, the coolant is physically separated from electrical components, often by using a battery bottom cooling plate, to ensure safe and reliable operation.

For demanding scenarios such as fast charging, the industry is trending towards increased battery-to-coolant integration. Closer contact between the fluid and battery, with higher heat exchange surface, enhances thermal management by improving heat transfer efficiency. As a result, the coolant’s electrical properties become increasingly critical. Traditional engine coolants, while robust and corrosion-resistant, typically have electrical conductivities between 2.000 and 10.000 µS/cm. If leakage occurs within the battery pack, this level of conductivity can pose a serious electrical safety risk. Eects can range from external short circuits triggering rapid battery discharge to internal cell Damage and even thermal runaway if the situation is not properly managed.

To address this challenge, there is a growing focus on dedicated EV coolants that not only deliver thermal performance and material compatibility, but also fulfil a safety-critical function throughout the product’s lifecycle.

Recognising this need early, Arteco’s pioneering work led to the development of Freecor® EV Milli coolants with low electrical conductivity, specifically designed to enhance the safety of battery systems.

To demonstrate the eect of coolant leakage into battery cells, Arteco collaborated with leading academic research institutions and independent specialised testing institutes to conduct controlled abuse testing. The experimental setup (Figure 1) featured a 57 Ah Li NMC prismatic cell at 100% state of charge (SoC), partially submerged in water–glycol coolants of varying electrical conductivity. A 1 cm gap was maintained between the battery’s negative terminal and a copper busbar, across which a 400 V potential was applied, simulating a worst-case short-circuit event at the pack level.

When exposed to a conventional engine coolant (pink, 5.000 µS/cm), the system immediately exhibited short-circuit behaviour. The coolant boiled locally at the electrode, and electrical arcing was observed. Battery surface temperature rose rapidly, to levels potentially initiating thermal runaway. The combined effects of hydrogen generation via coolant hydrolysis and electrical arcing created a severely hazardous scenario within a very short timeframe.

In contrast, testing with a low-conductivity coolant (blue, 100 µS/cm) demonstrated substantially improved safety characteristics. Electrical arcing was entirely suppressed, and the battery surface temperature increased only gradually under identical abuse conditions. While hydrogen evolution could not be fully prevented due to the high applied voltage, the overall risk profile was significantly reduced. This delay in escalation provides critical time for users to evacuate and for emergency responders to intervene.

In light of these findings, industry standards have begun to impose stricter limits on electrical conductivity. For example, ASTM D8566 specifies a maximum electrical conductivity of 100 µS/cm for fresh coolants used in battery Electric vehicle applications. A significant regulatory step was taken with the implementation of China’s GB29743.2 standard in October 2025. This regulation mandates that as-supplied coolants used in newly developed vehicle platforms in the People’s Republic of China must not exceed 100 µS/cm, particularly for systems using water–glycol battery cooling.

Maintaining low levels of electrical conductivity, a parameter often overlooked or insufficiently emphasised in existing specifications, is essential to ensure system robustness. During controlled atmosphere brazing of aluminium components, such as radiators, cold plates, and other battery cooling structures, brazing aids and fluxes leave behind ionic residues on internal surfaces. Once the cooling system is assembled and filled, these residues dissolve into the coolant as residual salts, leading to a sharp increase in electrical conductivity. If the coolant is not specifically formulated to counteract this effect, the resulting conductivity spike may compromise the intended safety improvements (see Figure 2, 300 µS/cm).

Freecor® EV Milli technology resists such electrical conductivity spikes upon contact with brazed aluminium surfaces (Figure 3). Ist formulation helps maintain the initial safety benefits by stabilising conductivity levels, ensuring continued electrical insulation throughout the vehicle’s operational life.

Sustainable-by-Design

While EV-specific coolants are developed to meet safety and performance requirements, Arteco has gone further by addressing their climate impact. Recent life cycle assessment (LCA) studies show that the most significant climate Impacts associated with coolants are largely attributable to raw material extraction and end-of-life treatment. In response, Arteco has prioritised resource efficiency in its development strategy, leading to the creation of the Freecor® EV ECO coolant range.

Freecor® EV ECO coolants incorporate base fluids linked to bio-based or recycled feedstocks, allocated via a certified mass balance approach. This method enables the integration of alternative raw materials into existing production systems, while ensuring full traceability and third-party certification across the supply chain. The base fluids used, Monoethylene Glycol (MEG) or Monopropylene Glycol (MPG), are traditionally virgin-grade materials linked to fossil resources. The Freecor® EV ECO product line helps reduce reliance on virgin fossil resources. To confirm the traceability and reliability of this process, Arteco has received the International Sustainability and Carbon Certification (ISCC) PLUS certification for its mass balance approach towards bioeconomy and circular economy.

The benefits of the ECO coolants are reflected in their significantly reduced Product Carbon Footprint (PCF) compared to their traditional virgin fossil-based equivalents.

Arteco’s strategy involves identifying a strong supplier network capable of meeting stringent sustainability and quality standards. Sustainable sourcing plays a central role in this strategy, supported by thorough evaluation of all Input materials to ensure coolant performance and reliability are never compromised.

Interpreting environmental data remains inherently complex, particularly in quantifying carbon savings. Variables such as feedstock origin and methodological assumptions can substantially influence the outcome of impact assessment. To strengthen data quality and transparency, Arteco collaborates with accredited external partners to develop a scientifically grounded, reliable database of product environmental information.

Developing sustainable coolants is a shared responsibility across the value chain. A proactive strategy focused on climate action, responsible resource use, and stakeholder collaboration is essential to achieve meaningful progress.

Arteco’s advancements in EV coolant technology contribute to the evolution of safe, sustainable mobility. Its solutions specifically designed for indirect liquid cooling in EVs, address the industry’s increasingly stringent safety and performance requirements. With the introduction of ECO coolants, Arteco is raising the bar for decarbonisation eorts across the entire value chain.

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Disclaimer: Statements regarding environmental benefits, CO reductions and other sustainability-related performance characteristics of the product(s) referenced herein are based on recognised scientific evidence and internal and/or external data available to us at the time of publication. Actual environmental performance may vary depending on use, conditions, and context. Supporting data and methodology are available on request (info@arteco-coolants.com). This information is provided for transparency purposes and does not constitute a guarantee of performance in all circumstances.

Effective Solutions for Bearing Insulation to Prevent Electrical Corrosion in E-Drive Systems

Posted on 19th February 2026

Philippe Pauchard, Application Engineers at DuPont (Switzerland)
Christoph Berger, Application Development Manager, DuPont (Germany)
Ruth Jackowiak, Application Engineers at DuPont (Switzerland)

The automotive industry is progressing toward high-voltage systems for electric vehicles (EVs) with enhanced efficiency. Reliable and durable components are increasingly critical, particularly bearings in electric motors, which can suffer from electrical erosion due to parasitic currents, causing significant damage and premature failure. This challenge is addressed by using insulation provided by DuPont™ Vespel® polyimide parts.

Vespel® polyimide insulating bearing sleeves

Vespel® S is a sintered polyimide which has no observable glass transition temperature or melting point. Its high-temperature resistance allows it to be used as an insert in die-cast aluminum parts. Its unique property is key for applications where high loads and elevated temperatures can occur, as may be the case in traction motors in critical drive modes or in the case of malfunction.

Vespel® polyimide insulating bearing sleeves, can be used to electrically insulate the rotor from the housing and suppress discharge currents. They offer a versatile and cost-effective solution for mitigating electrical corrosion in e-motor bearings. These sleeves can be installed during final assembly by press-fitting onto either the rotor shaft or one of the bearing rings (Figure 1). In all cases, standard steel ball bearings can be utilized with Vespel® sleeve, eliminating the need for expensive ceramic
rolling elements such as hybrid bearings. Vespel® polyimide insulating layer between 1 and 2 mm offers robust insulation by significantly increasing electrical impedance. This effectively attenuates high-frequency currents traversing the bearing, thereby reducing the risk of electrical erosion. Vespel® polyimide also exhibits mechanical
damping properties that may help reduce noise, vibration, and harshness (NVH) in electric motor systems.

Figure 1: Vespel® bearing insulation sleeves (left) and Stress analysis of the Vespel® sleeve press-fitted over the shaft and assembled on the inside diameter of the bearing (right).

Existing solutions, such as ceramic and polymeric coatings provide adequate insulation in DC environments, they often fail to prevent electrical discharge under AC conditions, particularly at higher frequencies, and may suffer from mechanical fragility.

Electrical insulation performance

Various tests have been conducted to support the use of Vespel® sleeves in addressing electrical corrosion issues. The electrical impedance has been measured by IMKT (Institut für Maschinenkonstruktion und Tribologie at Leibniz Universität Hannover). Results indicate that the electrical insulation performance of Vespel® SP-1, although
slightly lower than that of the hybrid bearing, remains in the same order of magnitude and significantly higher than the ceramic-coated bearing solution [8], even when compared to the thickest layer of ceramic coating (Figure 2).

Figure 2: Comparison of Electrical Impedance Across Various Insulated Bearing Solutions

Designing Vespel® polyimide Insulating sleeve

The design of the Vespel® polyimide sleeve requires studying the different press-fitting scenarios and checking that the loads resulting from the press-fitting of the various parts, combined with thermal expansion, are acceptable (Figure 1). Bearing manufacturers typically provide maximum hoop stress and radial stress; this information is used to properly dimension the Vespel® polyimide sleeve. Although proper testing needs to be conducted on the final system to ensure the parts behave appropriately, simulations are used to build confidence and quickly design a working prototype (Figure 1).

Other polymeric solutions could be used, but they need to be reinforced with fibers to enhance mechanical strength. The fibers are abrasive and easily cause wear issues when they are in contact with aluminum. In EV cars, this phenomenon is amplified with the vibration generated by electrical motors causing fretting wear issues on aluminum housing.

Unlike standard polymers, Vespel® polyimide, with extreme temperature capabilities, does not require fiber reinforcement to maintain its mechanical performance and withstand the maximum temperature of 150°C, observed at the bearing position for traction motors. Tests conducted at the DuPont Tribological Laboratory under similar conditions revealed that fiber-reinforced thermoplastics caused significant wear on aluminum components, whereas Vespel® polyimide resulted in no measurable wear (Figure 3).

Figure 3: Wear performance of Vespel® polyimide vs polymeric solution against die cast aluminum

 

Aluminum die-casting insert

Another innovative solution involves the use of Vespel® polyimide as an insert in aluminum die-casting, leveraging its exceptional high-temperature resistance and lack of a melting point, which enables it to withstand aluminum processing temperatures up to 680 °C. By integrating a Vespel® insert directly into the mold, an electrically insulating barrier is formed between the traction motor housing and the bearing. Following the die-casting process, the insert can be machined to achieve precise tolerances – a standard step prior to bearing assembly.

In collaboration with Swiss aluminum die caster Aluwag AG, the feasibility of this concept was successfully demonstrated through the production of aluminum housings incorporating a 90 mm diameter Vespel® insert (Figure 4). Notably, the interface exhibited no structural or dimensional changes after multiple thermal cycles ranging from –40 °C to 150 °C, underscoring its suitability for long-term use in demanding application environments.

Figure 4: Cross section of bearing seat with Vespel® insert (© DuPont)

Recyclability of aluminum components with Vespel® polyimide inserts

Die cast aluminum housings containing Vespel® polyimide inserts are currently being evaluated by companies for use in electric vehicle driveline components. In addition to performance testing, there is a need to recycle aluminum housings that exhibit defects. During the casting process, a skimming operation is typically performed to eliminate impurities such as oxides, slag, and other contaminants that form at the surface of the molten aluminum. Preliminary tests have shown that Vespel® polyimide components float on the surface of the molten aluminum, which could simplify their removal during the skimming operation.

Most electric motor housings use steel sleeves to protect aluminum from bearing-induced fretting wear. However, these inserts complicate recycling due to material separation. Vespel® polyimide could offer a more sustainable alternative, replacing steel sleeves used with ceramic bearings while maintaining electrical insulation and simplifying recycling.

Figure 5: Vespel® Inserts Floating on the Surface of Melted Aluminum

Summary

As electric vehicles evolve, the need for reliable and durable components, particularly bearings, is paramount due to their susceptibility to electrical erosion in high-voltage systems. DuPont™ Vespel® polyimide offers a groundbreaking solution with its insulating bearing sleeves, which can enable the use of standard roller bearings instead of costly ceramic alternatives, thereby helping to reduce material costs significantly.

Additionally, Vespel® polyimide inserts can be integrated within aluminum die-casting processes, providing effective electrical insulation and enhanced performance in demanding environments. The combination of these innovative solutions positions Vespel® polyimide as an essential material for the future of electric vehicle technology, promoting safer, more efficient, and sustainable electrified drivetrains.

References
[1] Rösel, G.; Moenius, P.; Daun, N.; Spas, S.; Hackmann, W.; Schmitt, B.; Reich, A.: Konzept für einen Hocheffizienten 800 V Achsantrieb. 41st International Vienna Motoren Symposium, Vienna, 2020
[2] Power Electronics New Zealand: The principles of managing dV/dT in AC variable frequency drives. Online: https://www.power-electronics.co.nz/blog/the-principles-of-managing-dvdt-in-ac-variable-frequency-drives/, access: August 13, 2024
[3] Saucedo-Dorantes, J.; Zamudio-Ramirez, I.; Cureno-Osornio, J.; Osornio-Rios, R. A.; Antonino-Daviu, J. A.: Condition Monitoring Method for the Detection of Fault Graduality in Outer Race Bearing Based on Vibration-Current Fusion, Statistical Features and Neural Network. Online: https://www.mdpi.com/2076-3417/11/17/8033, access: July 17, 2024
[4] NTN: Elektroerosion. Online: https://waelzlagerwissen.de/waelzlagerschaeden/elektroerosion/, access: July 17, 2024
[5] Franquelo, L. G.; Rodriguez, J.; Leon, J. I.; Kouro, S.; Portillo, R.; Prats, M. A. M.: The age of multilevel converters arrives. In: IEEE Industrial Electronics Magazine 2 (2008), No. 2, pp. 28-39
[6] Eireiner, D.; von Petery, G.; Völkel, F.: Bearings Reinvented – Contribution of Rolling Bearings to Improving Ranges and Charging Times of Electric Vehicles. 20th International VDI Congress Dritev – Drivetrain for Vehicles, 2020
[7] Preisinger, G. Cause and Effect of Bearing Currents in Frequency Converter Driven Electrical Motors: Investigations of Electrical Properties of Rolling Bearings. Ph.D. Thesis, TU Wien, Vienna, Austria, 2002

©2025 DuPont. All rights reserved. DuPont™, the DuPont Oval Logo, and all trademarks and service marks denoted with ™, ℠ or ® are owned by affiliates of DuPont de Nemours, Inc. unless otherwise noted. DuPont believes this information to be reliable. It may be subject to change as additional knowledge and experience are gained. It is not intended as a substitute for any testing you may conduct to determine for yourself the suitability of our products and information for your particular purpose. Since conditions for use are outside the DuPont’s control, DUPONT DE NEMOURS, INC. AND ITS AFFILIATES MAKE NO WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE AND ASSUMES NO LIABILITY IN CONNECTION WITH ANY USE OF THIS PRODUCT AND INFORMATION. This information is not intended as a license to operate under or a recommendation to infringe any trademark, patent or technical information of DuPont or other persons covering any material or its use

See the Unseen from NVH Performance of E-powertrain – the Un-audible High Voltage Ripple and Transients that Affects EVs

Posted on 10th February 2026

Xiao Cai, Chairman & CTO, Stropower Technologies Co., Ltd.

• The correlation factors between the NVH performance of e-drive vehicles and its inner high-voltage power network
• Extensive impact of underlying electrical fluctuations and transients on electric drive vehicles
• Development of industry testing standards and testing environment

A key difference in NVH performance between e-drive vehicles and internal combustion engine (ICE) vehicles lies in the electromagnetic excitation vibration caused by the vehicle’s electric drive, such as the humming of the battery pack and the characteristic noise of the motor‘s electrical speed in the high dynamic region. This is the NVH characteristic of the high-voltage system of e-drive vehicles that can be perceived when exposed. However, through a deeper understanding of its mechanism, we will see more widespread high-voltage electronic and electrical fluctuations and transients, which more often and silently affect the control performance – functional status – driving experience – safety and durability of the electric drive. Effective high-voltage testing can help us better predict these potential hazards.

The correlation factors between the NVH performance of e-drive vehicles and its inner high-voltage powernet.

The mechanical structure design and power transmission design of the vehicle body form the self-foundation of the vehicle’s NVH performance. With the assistance of good chassis suspension, noiseabsorbing layers, and wind noise isolation, luxurious and quiet models can achieve better NVH performance in terms of mechanical quality. This is a very important design field in the automotive industry. These measures and means are effective and primary for mechanical vibrations below 100 Hertz. However, in electric vehicle models, there are typical noises in the kilohertz frequency band. These comparably highfrequency noises cannot be effectively suppressed by the absorbing materials and traditionally designed body structures, nor can they be masked by other low-frequency noises due to the difference in timbre. And it suddenly brings about new problems in NVH engineering for e-drive vehicles.

The difference in noise sources is the cause of different timbres. The main noise sources existing inside e-drive vehicles are the electrical fluctuations and transients of the high-voltage system caused by the operations of various power semiconductor switches.

A typical phenomenon can illustrate this issue: when charging your laptop with a charger in a quiet room, in most cases, you can clearly hear the humming sound of the charger. This is a common acoustic noise in daily life caused by electromagnetic fluctuations. The reason is that the power transmission control of switching power supplies relies on the switching actions of power devices. During the use of electric vehicles, similar causes of noise can also often be found: a faint humming sound that can be heard even when the vehicle is not in motion after just being powered on, and the special tonality variation in accordance with your pedal position.

During the power fluctuation of several hundred kilowatts (x kW) in an electric vehicle, the voltage and current of the internal highvoltage system will be subjected to electrical fluctuation impacts of varying speeds, ranging from 1V/MS to 1V/ns, for example. In terms of the composition of the high-voltage system, different electronic and electrical units inside are connected in parallel to the DC bus supported by lithium battery packs and DC link capacitors, and they will experience varying degrees of interference.

By conducting ripple injection tests on the lithium battery packs of e-drive vehicles ranging from 10Hz to 150kHz – that is, by simulating the ripple amplitude of the DC bus voltage and applying it to the power battery pack, the acoustic noise spectrum generated by the power battery pack was tested.

From the test results: due to the high-voltage battery pack characteristics of power batteries, there are several uH components in their internal impedance characteristics in the equivalent model at the circuit level. This enables ist response to fluctuations in AC voltage to generate an AC current with a sufficiently high phase difference – that is, the AC current intensity of the power battery pack varies with frequency according to its own impedance-frequency characteristics (D-EIS or in-situ EIS). This also leads to the NVH noise tones produced by the fluctuations of bus voltages of different frequencies on the battery pack being quite distinct. Based on the current test results, the corresponding relationship between the magnetic field stress of the current and the structural vibration (such as copper bars and metal covers) also confirms the causal relationship of frequency correspondence.

Effective control of electromagnetic interference fluctuations that may generate NVH excitation is currently an important research topic in high-voltage electronic and electrical testing. However, due to the very wide differences in the „excitation – transmission – response“ path among different vehicle models, the applicability of general models is limited. More prediction and verification methods still require appropriate test platforms for verification.

Take the electric drive power unit as an example. Under different power density design requirements, the controlled performance of the motor and the electrical shocks, such as ripple and surge, caused by the high-voltage system during the power output process, are related to the designer‘s optimization level of the control process, as well as appropriate peripheral filtering and anti-interference measures. The final production vehicle’s torque ripple wave and NVH characteristics are the result of design efforts coming from multiple aspects.

 

 

Extensive impact of underlying electrical fluctuations and transients on electric drive vehicles

The above description of the explicit NVH performance of vehicles has revealed the impact of electrical fluctuations and transients within the high-voltage system of e-drive vehicles on them, a problem that has not been encountered in ICE models.

In fact, since the large-scale commercial use of electric vehicles began, vehicle problems caused by the dynamic stress of high-voltage electrical systems have been very frequent, and most of these problems do not occur in a way that drivers can perceive.

For example: due to the excessive AC current at the impedance resonance point formed by the high-voltage wiring loop, the relay disengages and the BMS protection signal is mistakenly triggered; the overvoltage warning shutdown of the TMS is triggered by the voltage fluctuation of the DC bus caused by the operation of the MCU; the overvoltage of the DC bus which caused by the energy regnerated during heavy braking, which breaks down the components, etc. From the various electrical dynamics of high-voltage systems that have been mentioned, the major types of threat factors that mainly emerged can be classified in terms of waveform as:

1. Ripple during steady status
2. Transients during dynamic motion

 

 

Among them, the steady-state ripple mainly refers to the regular fluctuations in the bus voltage caused by the controller during the process of stabilizing the power output.

Under normal circumstances, since the on-off control of the switching elements by the controller is implemented by the software, if the load current fluctuates within a defined tolerance range, the command response for a stable Output is completed. This process is usually achieved at a steady state through „feedback-control“, such as typical PID control or complex PID control with algorithm update functions. The timing pulses of the switch nodes formed by the on-off control constitute the AC excitation of the entire in-vehicle high-voltage system, and through the impedance network of the system, the bus current is ultimately formed – this is a typical controlled response. Therefore, the level of ripple is directly related to the excitation composition, which is also the key way to usually increase performance or avoid the frequency of feature problems through control and regulation.

Transients during dynamic motion often occur in an „uncontrolled“ state, such as in a typical load-dump situation: the energy shock and high-voltage pulses generated by the drastic changes in current are natural responses without any controller management, and the survivability of the component unit solely depends on the stress margin at the time of design.

Another type of transient occurs with a higher probability. It also appears at the semiconductor nodes of the power bridge; that is, during the instantaneous process of the bridge arm switching, the voltage or current pulse is commonly seen at the rising and falling edges of the switching waveform. Although these transients cannot be regarded as truly „uncontrolled“, in fact, once a piece of hardware design is completed, it is very difficult to make changes to the ramping rates.

So, it is not difficult to see that the main difference between ripple and transient lies in the rate of voltage change, that is: V/s. Inside e-drive vehicles, with the development of the design trend towards functional integration, more and more functional units are gradually integrated into the same high-voltage system. For instance, several inverters are added to achieve an outdoor power supply, a step-up and step-down voltage module is added to be compatible with high and low voltage charging piles, and a 48V module is added for functionality and comfort, etc. Different units operate at different frequencies, which will apply more voltage variability on the DC bus. As a result, the generation of interference and the verification of anti-interference become important.

Development of industry testing standards and testing environment

At present, the industry is still in the research and early standard establishment stage for the design control and suppression countermeasures of ripple and transient pulses in EVs.

Conducting electronic and electrical tests on the high-voltage system of electric vehicles can simulate the extremely large electrical stress that occurs, thereby verifying the safety design margin and functional anti-interference capability of each component unit inside the vehicle. Avoid situations that threaten driving safety and affect the driver‘s experience.

Starting from the early LV123 standard, mainstream European car manufacturers have made many early efforts in the high-voltage electronic and electrical testing standards of vehicles, such as VW80300.

Today, the main general standards referred to in the industry are ISO 21498-1, -2. Since 2023, Vehicle manufacturers and testing institutions in China have gradually begun to pay attention to the corresponding testing standards and have already made preparations for the release of the corresponding Chinese standards as the testing progresses, and it is expected that the corresponding standards will be released within the next one or two years. In the future, based on the relevant test results and the accumulation of more new test cases, there will also be updated standards to gradually improve the current test standards, enabling them to provide more valuable references for detecting potential design issues of vehicles.

Stropower Technologies has always been dedicated to the development of green energy and the Research and development of zero-emission vehicles R&D. As a major equipment supplier for lithium battery testing and a leading enterprise in the electronic and electrical testing of high-voltage systems for electric vehicles.

Since 2018, based on the VW80300-2016 standard, the world’s first vehicle ripple spectrum response analyzer that fully meets the standard requirements has been developed by Stropower Technologies. Subsequently, it became the first supplier to offer a complete set of test equipment, including different voltage ramping rates and transient pulses.

Stropower Technologies officially released the third-generation vehicle high-voltage electronic and electrical complete test solution in October 2024, which includes a wide-frequency ripple disturbance emulator, a program-controlled test power supply system up to 1200V-1000A, a high-voltage artificial network that fully meets the impedance spectrum characteristics, and other auxiliary test equipment modules. It is a leading test solution provider in the industry that fully complies with test requirements and can comprehensively cover the main power dynamic ranges.

Thanks to the vigorous development of the electric vehicle market in China and the long-term trust and support of major vehicle manufacturers and testing institutions for Stropower Technologies, through the accumulation of hundreds of test cases, the company can not only provide customers with a one-stop complete set of test equipment assembly solutions, moreover, it can provide customers with professional and predictive test environment setup based on their testing purposes and the characteristics of the objects under test, avoiding time waste caused by the lack of understanding of tests and interferences from related variable factors. It also offers professional suggestions and technical support for the correct conduct of tests and the accuracy of test results.