High-Speed Reluctance Machine Design

Silphenix GmbH is an engineering and consulting firm in Switzerland specializing in high-speed electrical machines, magnetic bearings, and electromagnetic field analysis. One project focus is compact high-speed flywheel systems for day storage of solar photovoltaic energy on the order of 0.5 to 5 KWh usable energy. An important constraint for energy day storage is extremely low loss per day (e.g. 1% per hour). This means that the idling losses have to be less than 5 W and 50 W for 0.5-kWh and 5-kWh units, respectively. Minimizing the idling losses requires not only operation in a vacuum environment, but also low bearing losses (magnetic bearings), low eddy current losses (reluctance machine), and low drag losses (cylindrical rotor surface).