E-Mobility Engineering 019 | In conversation: Stephen Lambert l WAE EVR l Battery case materials focus l Quality control insight l Clipper Automotive Clipper Cab digest l Optimising battery chemistries insight l Powertrain testing focus

May/June 2023 | E-Mobility Engineering 31 their type of customer will probably use those cars, it’ll be a bit like the Ferrari FXX – the three-motor configuration will probably be the optimal choice.” Although there is already a lot of flexibility in the powertrain configurations thatWAE can implement on the EVR, McCawnotes that in-wheel motors do notmakemuch sense for the skateboard. “We’ve looked into in-wheel motors for the EVX, but for the power, torque and speed wewant on the EVR, we need inboard motors; there just isn’t an in-wheel motor yet that can deliver those targets. “And in-wheel systems rely on having quite a large seal around the outside of their hub motor to stop the ingress of the water, grit and other road detritus they’d otherwise be exposed to. “The large surface contact area between the seal and the rim going around it becomes critical at that point, and the larger the diameter of the wheel, the larger and more hazardous the differential of speed at the seal interface.” As mentioned, WAE has also begun researching and showcasing range extenders based on hydrogen (with the company planning to use green rather than blue or grey hydrogen). A fuel cell is currently in development in-house to allowWAE’s engineers to explore future routes towards sustainable, long-range electric driving. it for sustainability or resilience in supply chains. As a result, it has designed the back of the EVR with packaging space for potentially larger motors built using less power-densemagneticmaterials but which can still achieve levels of power appropriate for sportscars. As with the battery packs, WAE is sticking with tried-and-tested water- glycol cooling for the powertrain, and it intends to stipulate to suppliers that these systems must be packaged in a manner that shares common cooling channels between all the different systems and sections, even if the motors, inverters and gearboxes come from different suppliers. “And because of the software integration in the powertrain, we can effectively ask the inverter manufacturer to supply a ‘dumb’ systemwhere we just request a desired level of torque, and they design it to the necessary current for that,” McCaw explains. “We then use our own algorithms to establish how the motors and epicyclics need to behave in order to optimise the torque output and vectoring for different performance targets. That can be for safety reasons, handling and dynamics, or to make it understeer. Having a range of drive modes is pretty common for production EVs now, so we’ve made sure to cover that for our customers.” Future plans WAE sees the EVR being offered in three main configurations. Rear-wheel drive is the smallest and lightest arrangement, as it leaves the most space and freedom for redesigning different sections of the EVR or adding components such as supplementary battery packs or range extenders. It is the powertrain most often showcased by WAE and is something of a de facto baseline. “The package we have at the rear could be moved to the forward wheels for front-wheel drive, but because of weight transfer during hard accelerations, we’ve found it doesn’t actually deliver all the torque down to the ground,” McCaw explains. “So, at the very least it would make sense to downsize the motors for a front-drive version, with maybe 66-75% of the torque and power of the RWD, and that would then allow opportunities to take out weight. “That’s essentially how we would do frontal motors for a 4WD configuration for across-the-board torque vectoring, which is the second option we’ll offer.” Third is a single central drive motor at the front (along with the RWD) installed either through a limited-slip differential or potentially a clutch-pack torque vectoring differential. That would reduce weight, cost and complexity at the front compared with the 4WD approach, while still essentially delivering a 4WD solution, albeit possibly without all- wheel torque vectoring, depending on the exact differential installed. “The torque vectoring you’d get from just a single axle actually delivers 80% of the benefit you’d get from all-wheel torque vectoring, particularly in normal track driving conditions,” McCaw notes. “The all-wheel torque vectoring really comes into its own in adverse conditions, such as wet or icy weather or if there’s gravel on the road. But if you think about the kinds of integrators who will build upon the EVR, and how Among WAE’s future r&d targets is a hydrogen fuel cell powertrain to enable longer ranges than batteries without incurring CO 2 emissions