Combustion engine vehicles have technology that identifies when an oil change is needed or when there is a problem with the motor. Electric motors also can wear and become brittle from use where these parts are made up of tightly wound copper wires that in turn are coated with insulating resin. However, it is currently not possible to identify if the insulation around the wires is still intact or if the entire motor needs to be replaced.
Researchers at Martin Luther University Halle-Wittenberg (MLU) have developed dyes that can be directly integrated into the insulation. When the dyes change color, it reveals how much the insulating resin layer around the copper wires in the EV motor has degraded.
"This insulation changes over time,” said Wolfgang Binder from the Institute of Chemistry at MLU. “It becomes brittle as it degrades due to heat and chemical processes."
MLU developed a test rig that they used to analyze four different resin systems over several months to determine which degradation products form at different temperatures. They discovered that the four resin systems consistently released a specific alcohol under the different temperature conditions.
Researchers worked with Elantas to find a sensor molecule for this alcohol that is easily detectable and has properties that change when the alcohol binds to it. The sensor molecule must also withstand high temperatures and normal production processes. Additionally, the alcohol could not change the insulation’s electrochemical properties.
The MLU team discovered a dye, whcih normally glows reddish orange under UV light, changes color to light green when it binds with alcohol. The different color of the dye could be analyzed using special devices that could be installed directly into the engine.
"This way, you can see if a replacement is necessary without having to open up the engine," Binder said.
As these dyes change color, it may potentially help drivers avoid unnecessary motor replacements in the future or help to quickly identify when a part in electric vehicles needs maintenance.
The full research can be found in the journal Advanced Materials.
