Thermal Analysis and In-Slot Cooling Design of Variable-Section Hairpin Winding Traction Motor for EV Based on Lumped Parameter Thermal Network

In order to improve the full-frequency domain efficiency of traction motor for EV and enhance the effect of heat dissipation in the slot, an in-slot cooling design of variable-section transposed hairpin winding permanent magnet synchronous motor is proposed. In this paper, the losses of four different variable-sections winding are first compared and analyzed. Subsequently, the lumped parameter thermal network model is constructed and its accuracy is verified. Then the effect of interstrand transposition of the windings on the winding losses and temperature is explored. Finally, a cooling scheme is proposed to replace a part of Litzpin conductors with cooling paths and the cooling effect is demonstrated.