And packing more wires into the same amount of space gives EVs a power boost by providing additional voltage.
"As you know, in recent years, the electrification of vehicles such as (electric, hybrid and plug-in hybrid vehicles) has been advanced rapidly with the aim of reducing environmental impact," Yagi said. "Along with that, from the viewpoint of improving fuel/motor efficiency, engine performance, output density of vehicles, space saving and higher output of the motor generator are required."
At present, electric and plug-in electric vehicles are running with inverter-drive motors that generate between 200 and 400 volts. But demand for voltage continues to climb, and it's likely that next-generation EVs will need as much as 800 volts.
The impacts of these higher voltage demands, coupled with additional requirements—from a governmental or environmental perspective, for instance—are driving the need for new materials, particularly when it comes to wire jacketing.
"It is said that there are some issues that existing materials are facing, for instance, as for this structure where PI and PAI are used as enamel layer, it has insufficient reliability for high voltage due to thickness limitation, and pinhole defect occurs as well," Yagi said. "And as for this structure where PEEK and PPS are used as polymer layer by extrusion process, it has been facing poor adhesion, resulting in (needed) primer, cracking when bending, and poor flexibility.
"Other than that, especially along with higher voltage requirements for the future, by generated inverter surge invading into winding wires and parts, discharge occurs, insulating film deteriorates and the withstand voltage life of the motor gets low."