NSK is developing a new method to prevent electrical erosion
NSK is developing a new method to prevent electrical erosion in electric vehicle drivetrains. By using a patented plastic casing around deep groove ball bearings, electric vehicle manufacturers will be able to save on expensive ‘hybrid’ bearings with ceramic insulators. Eddy currents can enter electric motors in a number of ways, using conditions such as an inverter that frequently switches between different phases. Some electric motor architectures can also cause different current flows in bearings, such as rotor bearing leakage currents, bearing circulating currents and electrical discharge machining (EDM) currents. Electrical erosion is a serious risk to bearings, as it can cause arcing at certain voltages, which in turn leads to uncontrolled discharges with high amps. These discharges alter the morphology of steel bearing rings and balls, which melt and solidify on the surface of the bearing raceways, causing deep cracks. NSK is developing a patented insulating layer that can be applied to the inner and outer ring of the bearing, with a thickness ranging from 0.7 to 1.2 mm. This layer can prevent electrical erosion of bearings in electric vehicle transmissions.
