State of the art review into power transmission technologies

Electric power cables for hybrid electric vehicles (HEVs) and electric vehicles (EVs) should provide both layout flexibility to cope with the limited space in vehicles and high heat resistance to withstand large currents at high temperatures near the engine. Moreover, a halogen-free (no chlorine or bromine), heat-resistant cable is required in order to avoid environmental damage. All types of electric cable consist essentially of a low resistance conductor to carry the current (except in special cases such as heating cables) and insulation to isolate the conductors from each other and from their surroundings. There are many factors, which limit the amount of current that can be passed through a cable, the most significant being the cross sectional area of the conductor [1-2]. By increasing the cross sectional area of a conductor, the electrical loss due to resistance decreases. However, the cables with a large cross sectional area are expensive and heavy, and hence there are practical limits to the size of the cross section of a cable. For these practical limits, it is necessary to utilize a forced cooling for electric cable in order to reduce the cross sectional area and to reduce the cable temperature at high current. In recent years, many research studies and patents in the internal cooling systems for electric cable have been published [3-7]. These studies presented the internal cooling systems using a variety of heat dissipation methods in an effort to increase the current cable carrying capacity and to reduce the cross sectional area of the electric cable. Furthermore, many types of electric cables are used throughout the electric power industry. In Electric Vehicles applications, electric cables are used for the transmission of power, communication, and control signals. Cables are generally designed for a specific application. The design process for cables includes the selection of the conductor, insulation, shield, jacket, and armor material and the determination of the size of the conductor required for the service requirements of the cable.
This report reviews and discusses the required specifications for the electric cables, which will be applied in the vehicle proposed in this project. Therefore, guidelines for the design of the power cables will be given. These guidelines will consider the key properties of the cable such as, the type of cables, the cooling system and the insulation material. In addition, these guidelines will be applied on the particular case of the vehicle developed within this project, and a cabling design will be proposed.