Energy and power needs of electric vehicles

Both energy and energy rate (power) requirements are described based on the mechanical output requirements of typical electric automobiles, the electrical input requirements at the inverter, and the requirements from a utility into a charger. The impact of lithium-ion battery input-output efficiency is considered. A fully loaded full-size car with a mass of 2000 kg, for example, requires only about 15 kW of mechanical effort to operate at 105 km/hr. Effects of charging levels (Level 1 from a basic convenience outlet, Level 2 from a high-capacity residential source, Level 2A from a basic three-phase connection, and Level 3 from a fast charger) are explored. Comparisons are made with energy and power capabilities of fuel-driven cars. Cost comparisons are discussed based on expected utility rate structures. It is shown that EV energy and power requirements are well within established capabilities of electric machines and power electronics, but still push limits of batteries. Short-range EV driving offers far better energy use and much lower cost than the same use of fuel-driven cars. Charge flexibility can increase the effective range, and even basic convenience outlet infrastructure offers substantial range enhancement.