Utaka, R., Kaneiwa, H., Umeda, A., Mizutani, T. et al., "Development of Down-sized Motor Stator," SAE Technical Paper 2013-01-1763, 2013, doi:10.4271/2013-01-1763.
Down-sizing and dielectric insulation were required for the traction motors of hybrid vehicles. By utilizing the newly developed coil with thick resin insulation atop the conventional enamel film, the use of conventional inter-phase insulation paper was abolished. Furthermore, by adopting the stair-shaped coil structure and spiral winding configuration, the stator size was minimized. With the above technologies, the motor installation to smaller hybrid vehicles was realized, thus contributing to weight reduction of hybrid vehicles.