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

Specifications WAE EVR Skateboard-type platform All-electric Rear wheel drive Battery energy: 85 kWh Maximum power output: 1650 kW Maximum range between charges: about 450 km Maximum speed: about 400 kph Mass: about 1800 kg 30 May/June 2023 | E-Mobility Engineering losses in the motor and in turn higher thermal efficiency. It all starts to add up when you look at the efficiency of components, and when we look at the market we see inverters that can now run at 98-99% efficiency and motors at 96%. But getting that last 1% is incredibly difficult, so we’re willing to try out new and relatively less mature technologies if it means we could offer that.” While WAE declines to disclose the precise topology of the SiCs used in the inverter, it says the cylindrical housing has posed a considerable technical challenge to make it a fully integrated and simplified part of the powertrain that can be easily handled, installed and removed. “The rear suspension architecture is designed to have the springs running up and down the sides of the vehicle, rather than across the top, and in the show car at LCV we installed an onboard charger in that top space,” McCaw notes. “That was a rectangular package, andwith it we essentially showcased that two or four conventional, rectangularly enclosed inverters could be packaged across that space at the back, with themotors then seated underneath. Sowe have quite a few in-house design templates already with different approaches towards the kinds of powertrain sub-components or architectures that integratorsmight want.” WAE is similarly agnostic regarding the EVR’s motors, so the platform is capable of using induction motors and switched reluctance motors for example; at the time of writing, the two baseline motors were permanent magnet AC machines. They are radial flux designs with their rotors running internally to their external stators, and integrate what McCaw describes as “the latest high-end, neodymium-type rare earth magnets, in order to deliver enough power in a compact package”. The company notes however that a growing number of its customers want to use alternatives to rare earthmagnets, be Directly behind the battery connectors are the two inverters, seated back-to-back inside the central part of the powertrain cylinder. They are recognisable as the very smooth middle section, whereas the ribbed sections on either side house the motors. Outboard of these sections are the epicyclic transmissions that form the final part of the powertrain and output the final torque and speed for the wheels. WAE describes these as single- speed systems, heavily influenced by work on previous hypercar programmes, with the epicyclic layout having been chosen to suit the package constraints of the vehicle. “We are developing a novel two- speed concept, but can’t share any details about it at this stage due to IP,” McCaw adds. Like the battery, the inverter is also an 800 V system; 800 V has been the power supply target across the board in order to eliminate the need for DC-DCs that would take up additional volume and weight as well as leading to (minute) losses regardless of conversion efficiency. “At the moment, the inverter runs using SiC transistors, but we are also working with other suppliers that are using GaN solutions in power distribution boards, and as we see technology moving forwards in the next few years, we see the price point of GaN really starting to shift,” McCaw says. “That’s likely to stem from the increasing availability of materials and parts as well as falling production costs, but for now the SiCs are a must-have.” Although there is a debate between proponents of SiC and those of GaN, for WAE there are three key parameters that help inform its ultimate decision as to which it will primarily offer with the EVR – availability, cost and the architectures of the inverter systems that can be achieved using the chosen transistors. McCaw explains, “Each architecture can have slight differences in critical variables such as where losses are coming from. Inverter suppliers are doing a lot of work at the moment on issues such as how to stack their switches, and having multiple different switch levels of GaN systems on top of each other, to give smoother, more sinusoidal waves for the motor. “That leads to lower hysteresis Dossier | WAE EVR Different drivetrain configurations can be installed, including a three-motor set-up that strikes a middle ground between RWD and 4WD