Carbon Nanotubes as an Alternative to Copper Wires in Electrical Machines: A Review

Abstract

The surge in electric vehicles (EVs) and their electrical appliances requires highly efficient, lightweight electrical machines with better performance. However, conventional wire used for electrical machine windings have certain limits to the current requirements. Copper is a commonly used material in electrical windings, and due to its ohmic resistance, it causes 75% of total losses in electrical machines (copper losses). The high mass of the copper results in a bulky system size, and the winding temperature of copper is always maintained at less than 150 °C to preserve the thermal insulation of the electric machine of the windings. On the other hand, carbon nanotubes and carbon nanotube materials have superior electrical conductivity properties and mechanical properties. Carbon nanotubes ensure 100 MS/m of electrical conductivity, which is higher than the copper electrical conductivity of 59.6 MS/m. In the literature, various carbon nanotubes have been studied based on electrical conductivity, temperature co-efficient with resistivity, material thickness and strength, insulation, and efficiency of the materials. Here, we review the electrical and mechanical properties of carbon nanotubes, and carbon nanotube composite materials are reviewed with copper windings for electrical wires.