Efficiency Increase of Electric Machines with Active Thermal Field Weakening A new degree of freedom for innovative cooling concepts

Efficiency in electromobility is key to minimizing energy consumption and thus increasing range. In this context, the electric machine contributes to the losses in the drive train of electric vehicles. With active thermal field weakening, FEV reduces the overall losses and thus increases the range. Currently, permanent magnet synchronous machines are most widely used in electromobility. Rare-earth permanent magnets with high magnetic energy density are used due to high power requirements. Their strength cannot be adapted. The magnetic energy density of rare earth magnets decreases with increasing temperature. This behavior can be used in the field weakening range, to increase the magnet temperature and to ther-mally weaken the permanent magnets. Studies show that this so-called active thermal field weakening can reduce the overall losses in typical driving cycles. © 2022, VDI Verlag GMBH. All rights reserved.