Endurance life of nanostructured insulation material for high torque density propulsion motors

The All-Electric Ship platform requires significantly higher torque density and payload efficiency for marine propulsion and electrical power generation. We have developed a nanostructured groundwall insulation for high torque density medium voltage propulsion motors. Our 2D nanoclay composite exhibits 2X combined improvement in electrical, dielectric, and thermal performance over the state-of-the-art micaceous insulation, achieved via a high thermal conductivity of >0.8 W/(m·K)., high breakdown strength of >40 kV/mm, and low loss factor of <2.5% at 155°C. Machine uprating modeling studies based on a 3.3 MW propulsion motor indicate an enhancement entitlement in torque handling capability of 14%. In this study, the endurance characteristics of the nanostructured insulation are fully investigated. The degradation of the nanostructured insulation at different endurance aging stages due mainly to surface/partial discharge is carefully studied to elucidate the discharge resistance mechanism. Unlike traditional composites whose discharge resistance is imparted by inorganic fillers due entirely to the blocking effect, our nanostructured insulation develops in-situ a new nanostructured surface protective coating layer under the attack of the electrical discharges. As a result, a remarkable extended endurance lifetime exceeding 3000 hours has been achieved in the accelerated endurance tests, clearly indicating a high service reliability of our nanostructured material for high torque density propulsion motors.