Lower real EV inverter cost without compromising safety, quality, or test coverage

In the evolving world of eMobility one thing remains constant – the inverter is the heart and soul of electric vehicles. When it comes to testing inverters, the trend has been to pull tests further up the development cycle, using virtualization to simulate components at lower costs and test scenarios faster than in-vehicle field testing. Power-level hardware-in-the-loop (pHIL) testing extends traditional signal-level HIL to include testing the power electronics circuits on EV traction inverters in a closed-loop simulator.

Join this session at the Charged Virtual Conference on EV Engineering, presented by NI and D&V Electronics, to learn how traction inverter validation engineers can extend their testing capabilities by emulating the motor and the other power components in an EV powertrain to cover a broader range of realistic and repeatable test scenarios including under multiple failure conditions that would not be easily reproducible on the road.

Register here—it’s free!

Johnson Matthey partners with OnTo Technology on battery production scrap recycling

Johnson Matthey has entered into an agreement with OnTo Technology, a developer of battery recycling methods, to scale up OnTo’s process for the direct recycling of lithium-ion battery scrap.

OnTo’s patented Cathode Healing process restores the coating material to use in new battery production, and avoids energy-intensive refining processes.

Jane Toogood, Chief Executive of Johnson Matthey, says, “We believe direct cathode recycling is an important goal in delivering a truly sustainable electric car. We are delighted to be working with OnTo and UKBIC to bring this technology closer to commercialization.”

Bloomy opens new HQ for battery testing and control systems

Bloomy, a provider of automated testing, data acquisition and control systems, has opened a new 30,000-square-foot headquarters in South Windsor, Connecticut. The facility houses 25 independent manufacturing cells for concurrent assembly, testing and integration.

Bloomy’s automated test systems are largely based on commercial, off-the-shelf technologies, and enable customers to take advantage of the rapidly progressing state of digital transformation. Bloomy also uses its own battery cell simulators, variable differential transformer, thermocouple and avionic bus communication devices, and automated test software. 

“There is a strong movement towards autonomy, digital transformation and electrification among our customers,” said Peter Blume, President of Bloomy. “We expanded our manufacturing space with the capability to provide all of the automated electronic test equipment for a new aircraft, robotics or vehicle program, allowing OEMs and suppliers to focus their resources on developing their products instead of designing and maintaining test equipment.”

Austin transit agency orders 197 electric buses

Capital Metro, the transit agency serving Austin, Texas, has approved the purchase of 197 new electric buses, which will expand its zero-emission bus fleet to more than 200 units. The agency’s eventual goal is to convert its entire fleet of more than 400 buses to zero-emission.

The new buses, from Proterra and New Flyer,  support both plug-in and overhead charging, and come with modern features such as USB charging ports and digital displays for passengers. They will replace legacy diesel buses and expand the fleet for the new Expo Center and Pleasant Valley MetroRapid lines.

Austin’s first shipment of e-buses is scheduled to arrive by the end of 2022.

The order includes 26 Proterra ZX5 Max 40-foot buses, each with 675 kWh of energy storage and up to 329 miles of range. This procurement is Capital Metro’s third and largest from Proterra. The agency currently operates 6 Proterra e-buses, and its North Operations electric bus yard uses Proterra Energy’s interoperable charging infrastructure.

“Proterra is proud to deliver our fifth-generation electric bus technology to help Austin realize its goal of 100% zero-emission transportation,” said Josh Ensign, President of Proterra Transit. “Through its embrace of next-generation electric bus technology and charging infrastructure, CapMetro is setting a model for others to follow in the transition to clean, quiet transportation for all.”

New Flyer’s newest electric buses offer “lighter weight, longer range, and better energy recovery than ever before,” said New Flyer President Chris Stoddart.

“Using zero-emissions buses adds to the quality of life of the Austin community,” said District 3 Council Member Pio Renteria. “Once these buses are in service, they will be used for new bus routes in underserved areas of East Austin.”

Nissan replaces e-NV200 with new Townstar EV, a modified Renault Kangoo

Nissan has introduced the Townstar, a new commercial that will replace its e-NV200 in European markets. Actually, the Townstar isn’t new—Nissan neglected to tell us (but InsideEVs helpfully did) that it’s a rebadged and slightly modified 2021 Renault Kangoo that will be available with either a gas or electric powertrain.

The Nissan Townstar EV, like the Kangoo E-Tech Electric, is built on the Alliance CMF-C platform, and it will come in both panel van and passenger versions. It has a 44 kWh battery pack and an expected range of about 177 miles. The motor delivers 90 kW (122 hp) of power and 245 Nm (180 lb-ft) of torque to the front wheels.

Level 2 charging takes place at 11 kW, or 22 kW with an optional upgrade. CCS fast charging musters 75 kW.

The Townstar offers up to 3.9 cubic meters of cargo space, and features a swiveling bulkhead—it can handle two Euro pallets and up to 800 kg (1,763 lbs) of cargo. Towing capacity (with either gas or electric powertrain) is up to 1,500 kg (3,307 lbs).

The Townstar integrates Nissan’s Around View Monitor—a suite of cameras that gives the driver a 360-degree overview of their surroundings. It also features Nissan’s ProPilot driving assistance system. Driver assistance features include Side Wind Assist, Trailer Sway Assist, Intelligent Emergency Braking, Pedestrian and Cyclist Detection, Hands-Free Parking and Intelligent Cruise Control. Driver amenities include Apple CarPlay, Android Auto and wireless phone charging.

“Offering two efficient powertrain solutions, ergonomic design and unique technologies, the all-new Townstar is comprehensively equipped to meet customers’ ever-changing needs,” said Emmanuelle Serazin, LCV and Corporate Sales Director, Nissan Europe. “With tougher emissions standards, urban access restrictions and ever-increasing demand for last-mile delivery, businesses need to find effective and sustainable solutions to remain competitive and optimize their operations.”

Thermally conductive adhesives for next generation cell-to-pack configurations

Sponsored by Parker Lord

With the significant growth and development of battery pack technologies, manufacturers of Electric Vehicles (EVs) are placing an increased emphasis on pack design optimization. Manufacturers seek lighter weight, yet more compact solutions to gain additional energy density and reduce cost. In parallel, they also strive for simpler and more affordable manufacturing operations. One immediate route to achieving these goals is the elimination of the housings of battery modules and bonding individual cells directly to the cooling plate, a strategy known as “cell-to-pack” [1-3]. Longer term solutions, albeit mostly conceptional, even involve bonding cells directly to the vehicle chassis [3-4]. To address these emerging trends, new thermally conductive adhesive technology is needed, especially given the imposition of more demanding environmental and mechanical performance conditions.

Driven by highly stringent safety standards coupled with affordable and abundant supply chains, a majority of EV manufacturers have converged to a common battery pack configuration (see Figure 1). This battery pack configuration consists of numerous battery modules, each of which contains groups of individual battery cells. This approach enables control, monitoring, and service of discrete battery modules. It also provides the batteries with additional crash and environmental protection, incorporates greater electrical isolation between and around modules, and, in-turn, helps prevent fire propagation in the event of thermal runaway. From a thermal management standpoint, a minimum of two discrete thermal interface materials (TIMs) or “gap fillers” (GF) are typically employed in the current, modular-based, battery pack configuration, as illustrated in Figure 2. 

Cross-section of current battery pack configuration based on prismatic cells contained in discrete modules

Both gap fillers, with the aid of a liquid-cooled plate, help regulate the temperature of the modules to ensure safe and efficient performance. The upper gap filler fills in the large spaces or gaps between the lower sides of individual batteries and the gaps between the bottom of the batteries and the inside wall of the module housing; this serves to firmly adhere the batteries in place while providing a continuous, thermally conductive (TC) pathway through which heat can travel. Such a gap filler, referred to here as a Cell-to-Module (CTM) gap filler, is often based on chemistries such as urethanes that offer strong adhesion, yet good flexibility to help absorb stresses. 

The lower gap filler fills in large spaces between the cell modules and the large cooling plate for the entire battery pack (see Figure 2). This material, referred to here as a Module-to-Pack (MTP) gap filler, also serves to provide heat conduction between the adjacent interfaces, but unlike the CTM gap filler, is designed to lightly adhere to the cooling plate surfaces. The low bonding strength enables easy removal of discrete modules for serviceability reasons. MTP gap fillers are typically based on very compliant, chemical backbones, such as silicone or soft urethanes.

Despite the many benefits of the conventional modular design, there comes numerous tradeoffs. For example, the inactive portions of the module (e.g. the housing, terminal plates, side plates, internal connectors, controls, etc.) add weight, occupy precious volume, and ultimately translate in compromised pack energy density. Moreover, the many discrete parts increase complexity of the design, manufacturing, and supply chain logistics. Given these challenges, many EV and battery manufacturers are eliminating modulus entirely and directly bonding batteries to the cooling plate as illustrated in Figure 3. 

Cross-section of the next generation, module-free or “Cell-to-Pack” battery pack configuration

This new module-free approach, referred to as “Cell-to-Pack” (CTP), reportedly increases volume-utilization space from 15-50%, depending upon battery cell design [1-2]. Moreover, the number of parts is claimed to be reduced up to 40% [2]. This change not only greatly improves pack energy density, but also gives EV manufacturers the option to use less expensive, lower energy density cells given the extra space. 

From a thermal management standpoint, the new CTP design results in half the thermal interface materials (1 vs. 2), half the number of interfaces (2 vs. 4), and no module housing. This change greatly lowers the thermal resistance of the stack which offers reduced cooling (or heating) loads by the cooling plate and/or enables the use of lower conductivity gap fillers. On the other hand, this change has invoked more stringent environmental resistance and mechanical performance requirements since the module housing is no longer available to protect the batteries from the environment. For example, numerous OEMs are now requiring thermally conductive gap fillers capable of maintaining strong, flexible bonds between polyethylene terephthalate (PET) wrapped battery cells to aluminum-based cooling plates after 1000 hours (6 weeks) of aging at 85°C and 85% relative humidity (RH). The PET is primarily used to provide individual, prismatic cells an additional layer of electrical insulation to prevent electric arcing. 

To address this CTP trend and associated requirements, Parker LORD has been developing new adhesive technology. Their latest white paper highlights recent developments for thermally conductive, CTP urethane adhesives. Urethane chemistry, in a 2-part form, was selected due to its good balance of strength, ductility, and formulation versatility. Specific attention is devoted to adhesive performance on PET plastic and aluminum substrates with environmental aging in mind. Comparisons to conventional urethanes are made. Additional properties such as rheology, density, conductivity, and bulk mechanical properties are briefly discussed.

Cell-to-Pack Adhesive Innovation

As previously mentioned, new CTP designs are requiring adhesives to maintain excellent adhesion under more stringent environmental testing conditions given the lack of the once protective modular housing. It is not uncommon for CTP pack designers to require lap shear strength levels in excess of 6 MPa after exposure to 1000 hours of 85°C and 85% RH. Historically, urethane adhesives have often had difficulty maintaining high levels of adhesion particularly on plastics and aluminum substrates after extended exposure to 85°C and 85%RH. Adhesives containing high levels of thermally conductive filler pose an even a greater challenge.

Through unique formulation developments in their laboratory, Parker LORD has been able to achieve noteworthy results after extended 85°C / 85%RH aging. Their new CTP adhesives are capable of delivering a balance of rheology needed for ease of manufacturing, low density for light-weighting of vehicles, good thermal conductivity for effective battery heat management, strong bulk properties to assist in handling mechanical loads, and low dielectric constant to prevent electrical charge buildup. Moreover, their scientists and engineers can tailor CTP adhesive performance to meet the requirements of specific CTP applications. 

Click here to view the whitepaper which contains data and complete test results comparing cell to module gap fillers and new thermally conductive cell to pack adhesives. If you have a specific question, reach out to a member of their team today.