ISSUE 012 Winter 2021 Sigma Powertrain EMAX transmission dossier l In conversation: David Hudson l 48 V systems focus l 2021 Battery Show North America and Cenex-LCV reports l Everrati Porsche 911 digest l Switching insight l Motor laminations focus

TheGrid The system will be suitable for cars and commercial, marine and construction vehicles Fast charge ahead for BMWvehicles Heavy-duty EVs compressor project Sprint Power is leading the development of an 800 V fast-charging system for BMW (writes Nick Flaherty). The Celeritas project is a £9.7 million effort to develop fast-charging cells and battery packs for battery EVs and fuel cell hybrid EVs. As well as BMW, its members include the UK’s Advanced Propulsion Centre, BP, AMTE Power, Clas-SiC and Eltrium. The 800 V battery packs will be able to charge to 80% in 12 minutes, but that will require more accurate control and measurement of their state of charge by the BMS than existing systems. The current best-in-class charging systems take about 22 minutes for a 10-80% charge. Sprint Power will design and develop the 800 V battery platform, the 800 V DC-DC A project is aiming to develop a high-speed, electrically driven two-stage compressor for heavy-duty EVs (writes Nick Flaherty). The HiComp2 r&d project has four consortium partners: Equipmake, HiETA Technologies, Bladon and the Institute for Advanced Automotive Propulsion Systems (IAAPS). They are developing a compressor that is lighter, cheaper and more efficient than current air compressor systems. The shift to hybrid and full electric powertrains has brought a growing awareness of the need for more efficient ancillary systems. All medium and heavy commercial vehicles require a compressed air supply for braking and suspension, but a conventional compressor is driven by the engine. An EV requires that the compressor be electrically driven. The compressor combines a high- voltage inverter and electric motor designed by Equipmake running on high- speed, low-friction air bearings from Bladon with a pair of back-to-back centrifugal compressors from IAAPS. Between the converter and BMS technologies, and will integrate all the system electronics and incorporate multiple charging protocols. The design targets BMW’s future battery specifications and requirements, with rapid charging cell technology being developed two compression stages, a 3D-printed intercooler from HiETA Technologies conditions the partially compressed air from the first, ‘low pressure’ stage before feeding it into the second, ‘high pressure’ stage compressor, for improved compression performance. As the lead project partner, Equipmake is the system integrator, while Bladon brings its understanding of high-speed rotating machinery to develop and supply the air bearings, and HiETA is using its expertise in additive manufacturing (AM) for the intercooler. The consortium partners expect to deliver a working pre-production prototype capable of matching the system performance of existing competitor products by March 2022. Researchers at the IAAPS and the University of Bath are developing the compressor impeller and housing designs using 3D computational fluid dynamics as well as 1D system-level modelling to optimise the design of both compressors. Optimising the entire design of the compressors and impellor reduces the by AMTE Power. BP will supply its thermal management and next-generation EV fluid technology, Clas-Sic will provide 1200 V SiC switching devices, and Eltrium will contribute its high-voltage manufacturing capabilities. The project will deliver two battery systems, one for battery EV applications and one for hybrids. The systems will include an integrated 800-14 V DC-DC converter, an 800 V BMS and multiple charging interfaces that will include provision for wireless charging in the future. The platform architecture will be suitable for electric cars as well as commercial, marine and construction vehicles. The system will be delivered in 2023. size of the motor and inverter required to deliver a given airflow, typically 220 litres/minute, reducing the weight. Equipmake’s APM 125 permanent magnet motor weighs just 14 kg and uses a proprietary ‘spoke’ architecture to maximise cooling capability, while providing a peak power of 125 kW at 12,000 rpm. Once in production, it is expected that Equipmake will introduce the compressor unit on electric bus designs that are currently in development. Equipmake worked with HiETA on another project, called Ampere, that uses metal AM for a motor with a peak power of 220 kW at 30,000 rpm that weighs less than 10 kg. It has a power density of 20 kW/kg, four times that of standard permanent magnet motors currently in use. The AM allows thermally efficient thin walls and optimised fine surface details that can be combined directly with the motor’s structure, replacing multi-part assemblies with a single, complex architecture that provides more efficient cooling. CHARGING COMPRESSORS 8 Winter 2021 | E-Mobility Engineering