High-efficiency next-generation powertrains
At present, fully and hybrid electric vehicle motors develop their highest efficiency — around 95 % — within a speed range of typically one fourth to one third of the maximum rotating speed. However, in the plurality of driving cycles, the motor operates at a wider range of speeds and at partial load, resulting in lower overall efficiency. The EU-funded project 'Materials and drives for high & wide efficiency electric powertrains' (HI-WI) addressed the mismatch between the high-efficiency region and the wide region of frequent operation with advances in the design and manufacture of drivetrains. The focus was on optimising drivetrain performance over a whole drive cycle rather than a single point. HI-WI members demonstrated that the total system efficiency can be enhanced by using a distributed power train with dissimilar machine technologies at the front and rear. To achieve high efficiency over a wide operating range, the motors for one of the axles should have high efficiency, while the motors for the other axle should exhibit low idling loss. Another project achievement was the development of smart power systems to ensure highly integrated, energy-efficient power conversion using technologies that reduce energy losses and potential perturbations that might disturb other electronic components. In addition to efficiency gains, HI-WI coupled its novel design approach to developments in magnetic materials. Nano-scale manufacturing advances led to creating permanent magnets having ideal geometries, reduced size and weight, as well as improved mechanical and thermal behaviour. For high-performance magnetic materials design and production, researchers investigated the synthesis of novel magnetic composites as pre-formed bulk components, and modelled their properties and behaviour. Use of such materials minimised reliance on rare earth elements, reduced the dysprosium content by about 80 % and improved motor torque. Project advancements in magnetic modelling and simulation tools should allow extensive studies into the nano-structured and nanocomposite materials, and computation of machine efficiency, respectively. HI-WI outputs should contribute to the development of a European standard reference technology platform for electric vehicle design. This will contain architectures, models, methods and tools for real-time embedded system development, verification, validation and testing.
Keywords
Powertrains, electric motors, drive systems, rare earth materials, electric vehicle
