Development of New Motor for Electric Vehicles 2024-01-2206

The world is currently facing environmental issues such as global warming, air pollution, and high energy demand. To mitigate these challenges, the electrification of vehicles is essential as it is effective for efficient fuel utilization and promotion of alternative fuels. The optimal approach for electrification varies across different markets, depending on local energy conditions and current circumstances. Consequently, Toyota has taken the initiative to offer a comprehensive lineup of battery electric vehicles (BEV), hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV), and fuel cell electric vehicles (FCEV), aiming to provide sustainable solutions tailored to the unique situations and needs of each region.

As part of this effort, Toyota has developed the 5th generation of hybrid electric vehicles. This paper describes the electric motor used in the new Toyota Camry which achieves high torque, high power, low losses, and compact design.

High-strength electromagnetic steel was adopted to allow for magnets to be placed in a novel polygonal arrangement. This new material and design improved the motor torque performance. Increasing the rotor core design flexibility allowed for a reduction of the demagnetizing field. Hence, the adoption of heavy-rare-earth-free magnets in the generator became a reality. In addition, the stator core adopted annealing after the press lamination to facilitate the growth of crystal grains, enabling a reduction in power losses compared to the previous generation motor. A fractional-pitch winding was adopted, and the amount of insulating resin was reduced by using foaming insulating paper that fixes the windings with the stator core. As a result, the end winding height was reduced compared to the previous model. Through these actions, this motor achieves a reduction of 26% in end winding height and an increase of 23% in power density, compared to the previous model.