The use of high-speed electrical machines and drives is in continuous evolution for a number of engineering applications, including electrical spindles for milling cutters and grinding, turbochargers, electrical turbo-compounding systems, aeroengine spools, helicopter and racing engines, and fuel pumps. The academic and industrial interests in this topic are growing very fast, pushing their research toward improvements in the involved technologies with a significant impact in many application areas. One of the main advantages of high-speed machines and drives is the reduction of system weight for a given power conversion. This is particularly desirable in all transportation applications where a weight reduction directly results in reduced fuel consumption and emissions. The electric transportation system is one of main topics with a significant push for advancing high-speed technologies.