High-speed oil-cooled PMSM with novel permanent magnet shape and carbon fiber sleeved rotor for high-performance powertrain

Abstract For high-performance vehicles with a single-speed gearbox, maximizing the gravimetric peak power and peak torque density combined with a high maximum speed is the decisive design goal of the electric machine. A low vehicle mass leads to a high vehicle acceleration, while a high maximum rotational speed leads to a high top speed. Therefore, this work presents the design and optimization of a high-speed, oil-cooled permanent magnet synchronous machine with a novel circular sector-like permanent magnet shape and a carbon fiber sleeved rotor in combination with cobalt iron laminations. The result is a gravimetric peak power density of 50.9 kW/kg, a gravimetric peak torque density of 30.8 Nm/kg, and a maximum rotational speed of 30000 rpm. The use of two of these electric machines on one drive axle leads to a gravimetric peak axle power density of 12.1 kW/kg and a gravimetric peak axle torque density of 72.1 Nm/kg at system level, including electric machines, gearboxes and inverters.