ISSUE 011 Autumn 2021 Candela C-7 hydrofoil speedboat dossier l In conversation: Robert Hoevers l Battery recycling focus l Vehicle dynamics insight l ZeroAvia hydrogen-electric aircraft digest l Motor materials

with the insulating resin material is key to avoiding them, but coating the wires with enamel gives a longer period of service. The impregnating resin will also protect against discharges, as the ceramic density slows down the erosion of the material. The enamel materials are also used to protect the welding of hairpin and eye pin rotors, where the ends of the wires are stripped, inserted and welded again but need to be re-insulated. Manufacturing process Reducing the cost of a motor also means reducing the number of manufacturing processes, but that also depends on the materials used. A simpler manufacturing process allows the motor to be assembled alongside the rest of the vehicle. “If you make an e-machine using fewer processes and components you’d be able to build micro-factories for the motors,” says Price. “You can then produce them at the destination on demand, but that can only happen if the machine has a simple design.” Polymers Using recycled materials in the motor is also important for lighter housings; they are easier to produce using injection moulding. That allows production closer to the end-market, as well as local recycling, as the temperatures used for recycling and manufacturing them are much lower than for steel or aluminium. This is aimed particularly at lower performance personal mobility systems such as delivery e-bikes and e-scooters Conclusion Achieving the best possible efficiency, power-to-weight ratio and cost of assembly of an e-mobility motor is about much more than just the materials in the magnet. New processing techniques are reducing the amount of HREs in the magnets while still allowing the motor to be smaller. Other combinations of HRE materials support higher temperature operation for higher efficiencies in generators and motors on electric aircraft. Using a carbon fibre sleeve avoids the eddy currents produced by using a steel jacket. Other designs are removing the rare earth materials entirely and relying on more complex control algorithms to compensate for the lower performance while achieving a more cost-effective construction. Others still are removing the magnets entirely to boost reliability. Achieving thinner laminations of the stator steel boosts the performance further, while materials with higher thermal conductivity can carry the heat away, and adhesives can allow more effective cooling channels to be built in the stator. Different wire topologies in the stator boost efficiency, while other designs aim to eliminate copper wires entirely and use a single cast coil for a simpler, more cost-effective construction. The use of recycling polymers formed at lower temperatures than steel or aluminium will also allow motors to be constructed closer to where the end-vehicle is assembled, boosting local supply chains and reducing the cost and complexity of e-mobility machines of all kinds. Deep insight | E-motor materials The insulating materials used here are based on a polymer resin with a ceraTic Äller (Courtesy of (_alta) 62 Autumn 2021 | E-Mobility Engineering