Low loss laminations on a 20000 RPM, 150 kW brushless DC motor

To make the drive system as effective as possible the stator for the brushless DC machine running at 20000 RPM, 150 kW is run as close to its thermal limit as is practicable. Even with chilled water cooling (~20°C) there is still a need to minimise, optimise and carefully balance the heat introduced into the stator from I²R losses from the windings and eddy current and hysteresis losses induced by the rotating magnets in the stator. To achieve a design optimised to match the constraints, the motor laminations must be carefully thought out in terms of geometry of slot and backiron, choice of material, and thickness of material