Although electric vehicles (EVs) currently comprise less than 2% of the U.S. light-vehicle market, the transportation sector is bursting with established companies and startup enterprises turning practically full attention to electrification. And in most cases, electrification for moving vehicles doesn’t come unless there are batteries. On the tip of everyone’s tongue who “virtually” attended the 2020 Battery Show and EV Tech Digital Days: How to make batteries better or cheaper. Preferably both.
No coincidence that the show co-joins battery and EV technology, as a preponderance of discussion, presentations and product showcases were directed as much at EVs and rapidly evolving EV engineering as at the hard technology of batteries themselves. And mirroring what analysts have stressed, electrification is demonstrating urgent momentum in the commercial-vehicle (CV) sector, where more-defined duty cycles and less need to cover an exhaustive spectrum of consumer requirements make electrification look more attractive by the day.
Diverse markets but common needs
The range of the show’s to-the-point series of “lightning talks” demonstrated the diversity of interest in battery and electrification technology. Moving in just 45 minutes from an evaluation of various electrified drivetrains for heavy trucks to high-performance inverter innovations from the United Kingdom’s McLaren Applied to thermal-management systems that enable a new generation of fast-recharging technology.
In the presentation “Evaluating Different Commercial Vehicle Electric Drivetrain and eAxle Configurations, Danfoss Editron director of R&D Josh Ley said he believes all electrified CV drivetrains will migrate to some form of eAxle because they are “extremely power-dense,” and their modularity allows the elimination of many conventional drivetrain components. Ley also said multi-speed transmissions for drive motors will demonstrate meaningful efficiency gains in many applications, even thought there are losses involved with more gearing. Nonetheless, he said, “Very significant efficiency gains are made at low speed,” for emachines with more than one gear ratio and “can be much more efficient than a direct-drive system.”
Meanwhile, Steve Lambert, McLaren Applied Technologies’ head of electrification, detailed what he asserts will be one of the key factors in improving EV performance in coming years: a shift to silicon carbide (SiC) power inverters as an upgrade over today’s insulated gate bi-polar transmission (IGBT) inverters. Lambert said SiC technology is important for many reasons, but primarily for its upgrade in overall drivetrain efficiency because its higher switching frequencies enable as much as a 60% reduction in cooling needs, an increase of up to 7% in driving range and the potential to use smaller-higher speed traction motors — all of which means an EV “system will be cheaper overall.”
McLaren has been developing subsequently more powerful inverters, Lambert said, including those for the Formula E racing series and McLaren Speedtail hybrid supercar. He said he envisions SiC technology at up to 800V capacity reaching an “inflection point” around 2027, adding that 800V vehicle electrical systems are going to be “pervasive as soon as the [recharging] infrastructure is there,” because of reduced overall system costs.
‘RISE’ of the electrified machine
One Battery Show 2020 exhibitor, Rise Robotics, offered a fascinating look at electrification for commercial vehicles that is not propulsion-related. Rise’s engineering-educated leadership aims to replace time-tested but inherently inefficient hydraulic actuation for all manner of CVs with a motor-driven, belt-actuated RISE cylinder, which the company said “delivers hydraulic-like performance and an unprecedented level of power.” The electromechanical RISE cylinder is claimed to reduce a machine’s hydraulic net energy consumed by more than 50%. When retracting or lowering weight, the cylinder’s design recovers that energy and returns it to the battery.
The company’s website said it has developed proprietary, steel-reinforced flat belts to transfer power from the cylinder’s DC brushless motor into linear motion and deliver long and virtually maintenance-free service life “without the mess and maintenance of hydraulic systems.” Using its RISE cylinders enables easy conversion of heavy machinery to electric power, the company said, by drastically reducing the amount of required onboard energy – i.e. that typically supplied by a diesel engine. The RISE cylinder thus can be specified for new fully electric machines or to enable converting existing machinery to battery power. In April 2020, the company completed a $3-million funding round that including investment from The Engine, a venture firm “spun out of MIT that invests in early-stage Tough Tech companies that are solving the world’s most urgent problems, such as climate change.”
A show presentation from Ulf Herlin, Protean Electric’s director of business development, detailed the potential for in-wheel motors as a propulsion alternative to motor-driven axles. Although the dialogue about the engineering advantages and disadvantages of hub motors is not new, it has revived because the technology — though not that of Protean — is earmarked for use by startup company Lordstown Motors for its Endurance battery-electric pickup truck.
Lordstown Motors is emblematic of a new wave of startup EV makers seeking to leverage the comparative simplicity of EV platforms to enable profitable vehicle manufacturing on a scale markedly smaller than that of most traditional automakers — and many of these startups in fact are relying on the fast development pace and cost-reduction innovations touted by many innovators at the Battery Show and EV Tech Digital Days conference.
Protean’s Herlin discussed cost and vehicle-dynamics concerns for in-wheel motors and markets other than automotive for which they may prove advantageous. There are several types of off-road commercial vehicles, for example, that might benefit from independent propulsion control at each wheel. For passenger vehicles, he said in-wheel traction motors now can be packaged in the same space as conventional braking systems — meaning no change to conventional wheel sizing — and offer potential for improved acceleration compared even to AWD EVs with a traction motor at each axle.
Equally intriguing is Protean’s suggestion that by relocating the propulsion function to the wheels, the vehicle-platform space opened by the elimination of the conventional drive motors enables fitment of considerably more battery capacity, offering the possibility of creating a “super long-range” EV configuration.Continue reading »