Novel EV society based on motor/ capacitor/ wireless — Application of electric motor, supercapacitors, and wireless power transfer to enhance operation of future vehicles

Abstract

Why do we need to supply “big energy” to electric vehicles (EVs) “while stopping” and “for a short time”? The energy form of electricity is absolutely different from gasoline. We may not need to take the same style of gasoline vehicle. Future EVs will be linked to the electric power system infrastructure; the vehicles will operate through frequent electric charging, as is the case with electric trains. Wireless power transfer based on magnetic resonance will be an extremely important technique to receive energy from the infrastructure. In a laboratory experiment, this technique enabled approximately 1kW power transfer with more than 90% efficiency at a distance of 1 m. It opens a new way to the novel EV world. Supercapacitors, rather than batteries, will play an important role in the future for charging of EVs. Supercapacitors have a long operating life (a few million times charge/ discharge life), large current density, and environmentally friendly composition. Further, their energy level can be estimated from the terminal voltage. Our EVs powered by supercapacitors can operate for more than 20 min after being charged for only 30 s. Electric motors have three major advantages: motor torque generation is quick and accurate, a motor can be attached to each wheel, and motor torque can be estimated precisely. These advantages enable the realization of high performance antilock braking and traction control systems, control of two-dimensional chassis motion, and estimation of road surface condition. Such motion control techniques improve energy efficiency and safety of future EVs. In summary, we can achieve a large-scale development of future vehicles that employ three techniques: Electric Motors, Supercapacitors, and Wireless Power Transfer. This eliminates the requirement for engines, high performance Li-ion batteries, and quick charging stations.